12,628 research outputs found

    Eigenvalue computations with the QUAD4 consistent-mass matrix

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    The NASTRAN user has the option of using either a lumped-mass matrix or a consistent- (coupled-) mass matrix with the QUAD4 shell finite element. At the Sixteenth NASTRAN Users' Colloquium (1988), Melvyn Marcus and associates of the David Taylor Research Center summarized a study comparing the results of the QUAD4 element with results of other NASTRAN shell elements for a cylindrical-shell modal analysis. Results of this study, in which both the lumped-and consistent-mass matrix formulations were used, implied that the consistent-mass matrix yielded poor results. In an effort to further evaluate the consistent-mass matrix, a study was performed using both a cylindrical-shell geometry and a flat-plate geometry. Modal parameters were extracted for several modes for both geometries leading to some significant conclusions. First, there do not appear to be any fundamental errors associated with the consistent-mass matrix. However, its accuracy is quite different for the two different geometries studied. The consistent-mass matrix yields better results for the flat-plate geometry and the lumped-mass matrix seems to be the better choice for cylindrical-shell geometries

    Not All Antibodies Are Created Equal: Factors That Influence Antibody Mediated Rejection.

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    Consistent with Dr. Paul Terasaki's "humoral theory of rejection" numerous studies have shown that HLA antibodies can cause acute and chronic antibody mediated rejection (AMR) and decreased graft survival. New evidence also supports a role for antibodies to non-HLA antigens in AMR and allograft injury. Despite the remarkable efforts by leaders in the field who pioneered single antigen bead technology for detection of donor specific antibodies, a considerable amount of work is still needed to better define the antibody attributes that are associated with AMR pathology. This review highlights what is currently known about the clinical context of pre and posttransplant antibodies, antibody characteristics that influence AMR, and the paths after donor specific antibody production (no rejection, subclinical rejection, and clinical dysfunction with AMR)

    FORTE antenna element and release mechanism design

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    The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system

    Quenching Effects in the Hadron Spectrum

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    Lattice QCD has generated a wealth of data in hadronic physics over the last two decades. Until relatively recently, most of this information has been within the "quenched approximation" where virtual quark--anti-quark pairs are neglected. This review presents a descriptive discussion of the effects of removing this approximation in the calculation of hadronic masses.Comment: To appear in "Lattice Hadron Physics", ed. A.C. Kalloniatis, D.B. Leinweber and A.G. William

    Adam Smith and the theory of punishment

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    A distinctive theory of punishment plays a central role in Smith's moral and legal theory. According to this theory, we regard the punishment of a crime as deserved only to the extent that an impartial spectator would go along with the actual or supposed resentment of the victim. The first part of this paper argues that Smith's theory deserves serious consideration and relates it to other theories such as utilitarianism and more orthodox forms of retributivism. The second part considers the objection that, because Smith's theory implies that punishment is justified only when there is some person or persons who is the victim of the crime, it cannot explain the many cases where punishment is imposed purely for the public good. It is argued that Smith's theory could be extended to cover such cases. The third part defends Smith's theory against the objection that, because it relies on our natural feelings, it cannot provide an adequate moral justification of punishment

    Queering lesbian, gay, bisexual and transgender identities in human resource development and management education contexts

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    Taking human resource development as its primary context, this article asks, ‘How can scholars mobilise queer theory concepts to move beyond treating lesbian, gay, bisexual and transgender identities as binaried, bounded and stable categories?’ While human resource development scholarship has made important, albeit limited, progress here, this article provides a review of queer theory to help scholars engage more deeply with some of its key concepts and theoretical resources to that end. In particular, one of this article’s main contributions is advancing the nascent in-roads Judith Butler’s writing has made into human resource development, management education and learning by linking her theory of gender performativity with the notion of cultural intelligibility. The aim of the article is to show how lesbian, gay, bisexual and transgender identity categories can be destabilised so that they can be examined queerly: performatively constituted and permanently open to contestation and resignification. Crucially, the wider applications and implications of queer theory are drawn out, such as how queer pedagogy can inform management education. This article also highlights possibilities for management learning scholars to queer other identities (e.g. heterosexual), organisations and modes of organising

    Effects of zinc and fluoride on the remineralisation of artificial carious lesions under simulated plaque fluid conditions.

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    The aim was to study the effects of zinc (Zn) and fluoride (F) on remineralisation at plaque fluid concentrations. Artificial carious lesions were created in 2 acid-gel demineralising systems (initially infinitely undersaturated and partially saturated with respect to enamel) giving lesions with different mineral distribution characteristics (high and low R values, respectively) but similar integrated mineral loss values. Lesions of both types were assigned to 1 of 4 groups and remineralised for 5 days at 37°C. Zn and F were added, based on plaque fluid concentrations 1 h after application, to give 4 treatments: 231 μmol/l Zn, 10.5 μmol/l F, Zn/F combined and an unmodified control solution (non-F/non-Zn). Subsequently remineralisation was measured using microradiography. High-R lesions were analysed for calcium, phosphorus, F and Zn using electron probe micro-analysis. All lesions underwent statistically significant remineralisation. For low-R lesions, remineralisation was in the order F(a) < non-F/non-Zn(a) < Zn(a, b) < Zn/F(b), and for high-R lesions F(a) < non-F/non-Zn(b) < Zn(b) < Zn/F(c) (treatments with the same superscript letter not significantly different, at p < 0.05). Qualitatively, remineralisation occurred throughout non-F/non-Zn and Zn groups, predominantly at the surface zone (F) and within the lesion body (Zn/F). Electron probe micro-analysis revealed Zn in relatively large amounts in the outer regions (Zn, Zn/F). F was abundant not only at the surface (F), but also in the lesion body (Zn/F). Calcium:phosphate ratios were similar to hydroxyapatite (all). To conclude, under static remineralising conditions simulating plaque fluid, Zn/F treatment gave significantly greater remineralisation than did F treatment, possibly because Zn in the Zn/F group maintained greater surface zone porosity compared with F, facilitating greater lesion body remineralisation
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