13 research outputs found

    On the energy-momentum tensor for a scalar field on manifolds with boundaries

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    We argue that already at classical level the energy-momentum tensor for a scalar field on manifolds with boundaries in addition to the bulk part contains a contribution located on the boundary. Using the standard variational procedure for the action with the boundary term, the expression for the surface energy-momentum tensor is derived for arbitrary bulk and boundary geometries. Integral conservation laws are investigated. The corresponding conserved charges are constructed and their relation to the proper densities is discussed. Further we study the vacuum expectation value of the energy-momentum tensor in the corresponding quantum field theory. It is shown that the surface term in the energy-momentum tensor is essential to obtain the equality between the vacuum energy, evaluated as the sum of the zero-point energies for each normal mode of frequency, and the energy derived by the integration of the corresponding vacuum energy density. As an application, by using the zeta function technique, we evaluate the surface energy for a quantum scalar field confined inside a spherical shell.Comment: 25 pages, 2 figures, section and appendix on the surface energy for a spherical shell are added, references added, accepted for publication in Phys. Rev.

    Organizational Justice and Employee Work Attitudes: The Federal Case

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    Organizational scientists have claimed that organizational justice is an essential requirement for effective organizational management. Perceived justice in the organization is predicted to influence employees’ attitudes toward their job and workplace significantly. This study explores how perceived organizational justice is related to employees’ work-related attitudes including job satisfaction, trust toward their supervisors and management, and intention to leave their agency. It also examines how gender differences affect these relationships. This study uses the 2005 Merit System Protection Board Survey to measure three types of organizational justice—distributive, procedural, and interpersonal—and tests the relationships using hierarchical regressions. The results indicate that higher levels of three types of organizational justice are positively related to job satisfaction and trust in supervisor and management, whereas they are negatively associated with turnover intentions of employees. Distributive justice is the one most strongly associated with job satisfaction, trust in management, and turnover intention of employees among three attributes of organizational justice. Women show higher levels of trust in management than men when they perceive procedural justice, whereas men show higher levels of trust than women when they perceive distributive and interpersonal justice

    Drug refractory epilepsy in brain damage: effect of dextromethorphan on EEG in four patients.

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    High doses of dextromethorphan (20-42 mg/kg/day) were given to four critically ill children with seizures and frequent epileptiform abnormalities in the EEG that were refractory to antiepileptic drugs. Their acute diseases (hypoxia, head trauma and hypoxia, neurodegenerative disease, hypoglycaemia) were thought to be due in part to N-methyl-D-aspartate (NMDA) receptor mediated processes. Treatment with dextromethorphan, an NMDA receptor antagonist, was started between 48 hours and 14 days after the critical incident. In three patients the EEG improved considerably within 48 hours and seizures ceased within 72 hours. In the patient with neurodegenerative disease the effect on the EEG was impressive, but the seizures were not controlled. Despite the improvement of the EEG the clinical outcome was poor in all children: three died in the critical period or due to the progressing disease; the patient with hypoglycaemia survived with severe neurological sequelae. Plasma concentrations of dextromethorphan varied between 74-1730 ng/ml and its metabolite dextrorphan varied between 349-3790 ng/ml. In one patient corresponding concentrations in CSF were lower than those in plasma. The suppression of epileptic discharges by the doses of dextromethorphan given suggests that such doses are sufficient to block NMDA receptors

    Video-assisted thoracic surgery―the past, present status and the future

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    Video-assisted thoracic surgery (VATS) has developed very rapidly in these two decades, and has replaced conventional open thoracotomy as a standard procedure for some simple thoracic operations as well as an option or a complementary procedure for some other more complex operations. In this paper we will review its development history, the present status and the future perspectives
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