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End Plates (end + plate)
Selected AbstractsDevelopment of an improved method for investigating the frictional properties of lubricants under transient EHD conditionsLUBRICATION SCIENCE, Issue 4 2002B.-O. Åhrström Abstract In the design and evaluation of mechanical system performance it is important to know the frictional qualities of the lubricant. Without correct numerical treatment of the lubricant during simulations of large systems, e.g., drive trains in trucks and buses, the results will, to a large extent, be inaccurate. However, obtaining detailed information places demands on the test equipment as the events are both transient and highly loaded. Under quasi-static conditions, forces are measured with force transducers, but in elasto-hydrodynamically lubricated conjunctions, where pressures are so high that the surrounding surfaces deform elastically, this cannot be done without permanently damaging the equipment. The conceptual design of the test equipment must therefore incorporate the measuring process in transient conditions (loading-unloading times of 200,500 ,s) being performed in real time, and allow extreme pressures of up to 3 GPa without component destruction. One way to obtain accurate friction data successfully is to apply a concentrated force pulse to a non-instrumented surface and to measure the response from that pulse elsewhere. The development of a measurement technique, the Lulea ball and bar apparatus, which utilises wave propagation theory, is presented in this paper. An oblique impact on a robust end plate on a rod was used to generate both non-dispersive compression waves and dispersive flexural waves. The normal force created by the axial wave was measured using strain gauges, while the transverse force was derived from the fast Fourier transforms of two lateral acceleration histories, using dynamic beam theory. The relation between the normal and tangential force histories showed the frictional properties at the impact as a function of time. A variety of lubricants was also studied at Hertzian pressures of up to 2.5 GPa, and the development of the method and results are presented. Experiments indicate that different lubricants exhibit different frictional properties and that the resolution in the test equipment is sufficient to indicate this. [source] HLA,B27,restricted antigen presentation by human chondrocytes to CD8+ T cells: Potential contribution to local immunopathologic processes in ankylosing spondylitisARTHRITIS & RHEUMATISM, Issue 6 2009Maren Kuhne Objective Analysis of the histopathologic features of hip arthritis in patients with ankylosing spondylitis (AS) has revealed accumulation of infiltrating mononuclear cells in the bone end plate and presence of hyaline articular cartilage that is not found in areas of total cartilage destruction. This study was undertaken to assess whether chondrocytes attract lymphocytes and whether cartilage chondrocytes from patients with AS have the potential to directly stimulate T cells in an HLA-restricted manner. Methods Human HLA,B27+ T cell lines, specific for the Epstein-Barr virus,derived peptide EBNA258,266, and autologous chondrocytes, serving as nonprofessional antigen-presenting cells (APCs), were available for use in a model system to study chondrocyte functions in femoral head joint cartilage of patients with AS. Peptide functionality of cytotoxic T cells was assessed by flow cytometry, and cellular interactions were detected by fluorescence confocal microscopy. Results When maintained in an alginate matrix, chondrocytes isolated from the femoral heads of patients with AS constitutively expressed type II collagen and CD80. When pulsed with the EBNA258,266 peptide, autologous chondrocytes functioned as APCs and, specifically, induced interferon-, production in CD8+ T cells. In mixed chondrocyte,T cell cultures, cell,cell contacts were dependent on the presence of the EBNA258,266 peptide. T cells adjacent to chondrocytes produced perforin and granzyme B; both molecules were found in focal aggregates, a prerequisite for antigen-specific lysis of target cells. Conclusion Antigen presentation through human chondrocytes allows the stimulation of peptide-specific CD8+ T cells. These results indicate that human chondrocytes can act as nonprofessional APCs, and suggest that there is an interferon-,,triggered autocrine loop of immune cell,mediated chondrocyte activation in the already inflamed environment. Thus, local HLA-dependent activation of peptide-specific cytotoxic CD8+ T cells by chondrocytes might contribute to inflammatory processes in the spondylarthritides. [source] Disparate Scale Nonlinear Interactions in Edge TurbulenceCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2008M. Yagi Abstract In this topical review, we explain the recent achievement in the study of nonlinear interactions, putting an emphasis on the relevance to edge turbulence. First, we start from the survey of the essence in the nonlinear theory of drift wave -zonal flows systems, and visit the experimental observations of the nonlinear interactions of tokamak edge turbulence. Secondly, the universality of intermittent convective transport in the SOL of different magnetic devices are shown. Then, we discuss evolution of collisional drift wave instability in the linear plasma configuration, which is bounded by end plates having analogy to SOL plasmas. By introducing the Numerical Linear Device, the intermittent evolution of large-amplitude instabilities, generation mechanism of the poloidal flow and other nonlinear process are examined. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Activity alters muscle reinnervation and terminal sprouting by reducing the number of schwann cell pathways that grow to link synaptic sitesDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2003Flora M. Love Abstract In partially denervated rodent muscle, terminal Schwann cells (TSCs) located at denervated end plates grow processes, some of which contact neighboring innervated end plates. Those processes that contact neighboring synapses (termed "bridges") appear to initiate nerve terminal sprouting and to guide the growth of the sprouts so that they reach and reinnervate denervated end plates. Studies conducted prior to knowledge of this potential involvement of Schwann cells showed that direct muscle stimulation inhibits terminal sprouting following partial denervation (Brown and Holland, 1979). We have investigated the possibility this inhibition results from an alteration in the growth of TSC processes. We find that stimulation of partially denervated rat soleus muscle does not alter the length or number of TSC processes but does reduce the number of TSC bridges. Stimulation also reduces the number of TSC bridges that form between end plates during reinnervation of a completely denervated muscle. The nerve processes ("escaped fibers") that normally grow onto TSC processes during reinnervation are also reduced in length. Therefore, stimulation alters at least two responses to denervation in muscles: (1) the ability of TSC processes to form or maintain bridges with innervated synaptic sites, and (2) the growth of axons along processes extended by TSCs. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 566,576, 2003 [source] Seismic performance of a 3D full-scale high-ductile steel,concrete composite moment-resisting frame,Part II: Test results and analytical validationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2008A. Braconi Abstract This paper presents the results of a multi-level pseudo-dynamic seismic test program that was performed to assess the performance of a full-scale three-bay, two-storey steel,concrete composite moment-resisting frame built with partially encased composite columns and partial-strength beam-to-column joints. The system was designed to develop a ductile response in the joint components of beam-to-column joints including flexural yielding of beam end plates and shear yielding of the column web panel zone. The ground motion producing the damageability limit state interstorey drift caused minor damage while the ultimate limit state ground motion level entailed column web panel yielding, connection yielding and plastic hinging at the column base connections. The earthquake level chosen to approach the collapse limit state induced more damage and was accompanied by further column web panel yielding, connection yielding and inelastic phenomena at column base connections without local buckling. During the final quasi-static cyclic test with stepwise increasing displacement,amplitudes up to an interstorey drift angle of 4.6%, the behaviour was ductile although cracking of beam-to-end-plate welds was observed. Correlations with numerical simulations taking into account the inelastic cyclic response of beam-to-column and column base joints are also presented in the paper together. Inelastic static pushover and time history analysis procedures are used to estimate the structural behaviour and overstrength factors of the structural system under study. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of high-intensity focused ultrasound on the intervertebral disc: A potential therapy for disc herniationsJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2006Carina Forslund PhD Abstract Purpose. To determine the potential application of high-intensity focused ultrasound for the minimally invasive treatment of herniated intervertebral discs by developing a probe that produces sufficiently high temperature locally to shrink collagen fibers (65,75°C). Materials and Methods. A 5-mm ultrasound probe was produced with a geometric focal length of 15 mm. The probe produced 2.5 W of acoustic power and was operated at a frequency of 4.1 MHz. Measurements of temperature increase were performed in discs from bovine tails. In vivo experiments were performed to assess histologic changes in the disc as well as in nerve root and muscle. Results. Sufficient temperature increase to produce collagen shrinkage was observed close to the focus of the ultrasound. Temperature measurements in vertebral end plates showed a temperature increase of only 4°C after 60-second exposure of the disc. In vivo experiments revealed histologic changes in the disc consistent with collagen shrinkage, with no adverse effects seen in surrounding tissues. Conclusions. The experiments demonstrated the feasibility of high-intensity focused ultrasound in the treatment of contained herniated discs. This technique has several advantages over other thermal treatment modalities. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:330,338, 2006 [source] Hydrodynamic Cavitation to Improve Bulk Fluid to Surface Mass Transfer in a Nonimmersed Ultraviolet System for Minimal Processing of Opaque and Transparent Fluid FoodsJOURNAL OF FOOD SCIENCE, Issue 9 2007P.J. Milly ABSTRACT:, Ultraviolet (UV)-induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet-Shockwave PowerÔ Reactor (UV-SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce ,controlled cavitation.' Eight UV low-pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I3,chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m2) increased from 97 J/m2 at 0 rpm to over 700 J/m2 for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV-SPR at exit temperatures below 45 °C was greater than 4.5 and 3 logs, respectively. The UV-SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface. [source] Morphologic Correlates for Laryngeal Reinnervation,THE LARYNGOSCOPE, Issue 11 2001Richard R. Gacek MD Abstract Objective To describe morphologic correlates for laryngeal reinnervation. Study Design Review of anatomic experiments dealing with laryngeal innervation performed over a 25-year period. Methods Description of results from experimental studies on the cat and human laryngeal muscles and nerve supply. Results Despite separation of abductor and adductor laryngeal motor neurons in the central nervous system, the mixture of abductor and adductor axons in the recurrent laryngeal nerve indicates that selective re-innervation of an individual laryngeal muscle must be accomplished at the neuromuscular junction (NMJ) of the muscle. The optimal time for a reinnervating neural source to re-occupy vacated NMJ is at the time of denervation. If the reinnervation procedure is attempted long (>1 mo) after denervation, extraneous end plates of other neural systems must be eliminated to provide vacant NMJ. The nerve muscle pedicle (NMP) concept is an effective model for reinnervation of a laryngeal muscle provided its activity pattern is similar to that of the denervated muscle and its insertion into vacated NMJ is timely. Conclusion NMP offers a logical method for selective laryngeal muscle reinnervation. Critical to the success of NMP are the physiological input to the NMP and timing of NMP implantation. [source] | |||||||||||||