1,073 research outputs found

    The Self-Force of a Charged Particle in Classical Electrodynamics with a Cut-off

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    We discuss, in the context of classical electrodynamics with a Lorentz invariant cut-off at short distances, the self-force acting on a point charged particle. It follows that the electromagnetic mass of the point charge occurs in the equation of motion in a form consistent with special relativity. We find that the exact equation of motion does not exhibit runaway solutions or non-causal behavior, when the cut-off is larger than half of the classical radius of the electron.Comment: 17 pages, 1 figur

    Signatures of Confinement in Axial Gauge QCD

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    A comparative dynamical study of axial gauge QED and QCD is presented. Elementary excitations associated with particular field configurations are investigated. Gluonic excitations analogous to linearly polarized photons are shown to acquire infinite energy. Suppression of this class of excitations in QCD results from quantization of the chromelectric flux and is interpreted as a dual Meissner effect, i.e. as expulsion from the QCD vacuum of chromo-electric fields which are constant over significant distances. This interpretation is supported by a comparative evaluation of the interaction energy of static charges in the axial gauge representation of QED and QCD.Comment: 22 pages (no figures

    Correlation Effects in Nuclear Transparency

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    The Glauber approximation is used to calculate the contribution of nucleon correlations in high-energy A(e,e′N)A(e,e'N) reactions. When the excitation energy of the residual nucleus is small, the increase of the nuclear transparency due to correlations between the struck nucleon and the other nucleons is mostly compensated by a decrease of the transparency due to the correlations between non detected nucleons. We derive Glauber model predictions for nuclear transparency for the differential cross section when nuclear shell level excitations are measured. The role of correlations in color transparency is briefly discussed.Comment: 24 pages revtex, 4 uuencoded PostScript Figures as separate fil

    a business centered approach

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    This thesis aims at exploring the benefits regarding the adoption of nonadjudicative alternative means of dispute resolution (NAADR), mediation in specific, in corporation’s legal frameworks and contracts. This paper reviews literature, categorizes the types of corporate governance conflicts, analyses several studies and presents empirical evidence that shows the positive effects of a NAADR as an enhancing factor in increasing the value of a company. This paper starts by acknowledging the existence of several situations in corporate governance that are commonly identified as irritants for a healthy steering of a company. We can separate these situations causing conflict in two different groups: the conflicts that are board-related and the ones that are corporate governance related conflicts, without needing the presence of the board. The categorization of corporate governance conflicts is followed by an overview of the negative consequences that these conflicts have for the overall performance of a company. It finds, supported on evidence presented, that corporate governance conflicts, on an economic stand point, contribute to undermine a company´s overall performance by making it less profitable, leading inclusively to shareholder value decline. This shareholder decline claim is illustrated by recent two different corporate scandals: The general motors case and the Volkswagen emission case. In both cases, decline in shareholder value happened after public disclosure of information. It continues by building on existence research that analyses the relation between a Director resignation that triggers the necessity of filling the 8-K filling form, and the reaction of the market that followed such happening. It follows, by presenting the ADR procedures continuum, highlighting, in specific the advantages of mediation and its importance on the prevention in what concerns the negatives outcomes resulted from corporate governance conflicts. It concludes by asserting that mediation is one of the best suited nonadjudicative alternative means of dispute resolution for corporations. Nevertheless, it acknowledges its lack of implementation on the corporate governance realm and analyses the main reasons behind that lack of implementation, with a specific focus on the Portuguese legal framework. It concludes that the legal Portuguese framework and the Portuguese lawyer’s mindset doesn´t favor the implementation of mediation as a true “forum” to seek grievance for the resolution of a conflict. This thesis ends by providing a thorough analysis on the macro and micro economic benefits that result from good corporate governance practices where NAADR mechanisms find its rightful place as an enhancing factor for firm growth

    Supersymmetric Quantization of Anisotropic Scalar-Tensor Cosmologies

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    In this paper we show that the spatially homogeneous Bianchi type I and Kantowski-Sachs cosmologies derived from the Brans-Dicke theory of gravity admit a supersymmetric extension at the quantum level. Global symmetries in the effective one-dimensional actions characterize both classical and quantum solutions. A wide family of exact wavefunctions satisfying the supersymmetric constraints are found. A connection with quantum wormholes is briefly discussed.Comment: In Press, Class. Quantum Grav. 20 pages, Late

    A Posterior Interosseous Nerve Syndrome Associated With Spontaneous Rupture of the Extensor Pollicis Longus Tendon

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    Posterior interosseous nerve entrapment syndrome and spontaneous rupture of the extensor pollicis longus tendon are rare conditions. The authors describe the bizarre combination of a spontaneous rupture of the extensor pollicis longus tendon in a 82-year-old lady with a posterior interosseous nerve syndrome. As far as the authors know, this is the first description of such an association in the literature. Surgical exploration revealed compression of the posterior interosseous nerve at the proximal portion of the supinator muscle and at Henry's leash. The nerve was freed, and the tendon of the extensor index proprius was transferred to the extensor pollicis longus. Six months after the procedure, the patient had resumed her daily activities, showing a good functional result

    Semiclassical approximation to supersymmetric quantum gravity

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    We develop a semiclassical approximation scheme for the constraint equations of supersymmetric canonical quantum gravity. This is achieved by a Born-Oppenheimer type of expansion, in analogy to the case of the usual Wheeler-DeWitt equation. The formalism is only consistent if the states at each order depend on the gravitino field. We recover at consecutive orders the Hamilton-Jacobi equation, the functional Schrodinger equation, and quantum gravitational correction terms to this Schrodinger equation. In particular, the following consequences are found: (i) the Hamilton-Jacobi equation and therefore the background spacetime must involve the gravitino, (ii) a (many fingered) local time parameter has to be present on SuperRiemÎŁSuperRiem \Sigma (the space of all possible tetrad and gravitino fields), (iii) quantum supersymmetric gravitational corrections affect the evolution of the very early universe. The physical meaning of these equations and results, in particular the similarities to and differences from the pure bosonic case, are discussed.Comment: 34 pages, clarifications added, typos correcte

    Improving quality of life for people with dementia in care homes: Making psychosocial interventions work

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    This is the author accepted manuscript. The final version is available from Cambridge University Press via the DOI in this recordPsychosocial interventions can improve behaviour and mood in people with dementia, but it is unclear how to maximise their effectiveness or acceptability in residential settings. Aims To understand what underlies the successful implementation of psychosocial interventions in care homes. Method Systematic review and meta-synthesis of qualitative research. Results The synthesis of 39 qualitative papers revealed that beneficial psychosocial interventions met the needs of people with dementia to connect with others, make a meaningful contribution and reminisce. Successful implementation rested on the active engagement of staff and family and the continuing provision of tailored interventions and support. This necessitated staff time, and raised issues around priorities and risk, but ultimately helped redefine staff attitudes towards residents and the caregiving role. Conclusions The findings from the meta-synthesis can help to inform the development and evaluation of psychosocial interventions in care homes and support their widespread implementation in clinical settings.National Institute for Health Research (NIHR

    Estudo sobre os embargos de nulidade e infringentes do julgado previstos no cĂłdigo de processo civil

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    Tese (Catedra) - Faculdade de Direito da Universidade do ParanaInclui referĂŞncias e Ă­ndic
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