Eigenvalue gaps for the Laplacian on hypersurfaces of the sphere

We provide lower estimates for the eigenvalues of the laplacian for hypersurfaces of the round sphere.Comment: We repair crucial typos and constant

Acceleration and Cyclotron Radiation, Induced by Gravitational Waves

The equations which determine the response of a charged particle moving in a magnetic field to an incident gravitational wave(GW) are derived in the linearized approximation to general relativity. We briefly discuss several astrophysical applications of the derived formulae taking into account the resonance between the wave and the particle's motion which occurs at $\omega_g=2\Omega$, whenever the GW is parallel to the constant magnetic field. In the case where the GW is perpendicular to the constant magnetic field, magnetic resonances appear at $\omega_g=\Omega$ and $\omega_g=2\Omega$. Such resonant mechanism may be useful to build models of GW driven cyclotron emitters.Comment: 16 pages, 1 figure, accepted for publication in Astronomy & Astrophysic

The instability of naked singularities in the gravitational collapse of a scalar field

One of the fundamental unanswered questions in the general theory of relativity is whether ``naked'' singularities, that is singular events which are visible from infinity, may form with positive probability in the process of gravitational collapse. The conjecture that the answer to this question is in the negative has been called ``cosmic censorship.'' The present paper, which is a continuation previous work, addresses this question in the context of the spherical gravitational collapse of a scalar field.Comment: 35 pages, published version, abstract added in migratio

Corporate Governance as an instrument of change state owned Corporate Governance as an instrument of change state owned companies: The case of the Hellenic Telecommunications Organization

This paper analyses the evolution of Corporate Governance (CG) mechanisms and organizational changes of the Hellenic Telecommunication Organization (HTO) and has two objectives: to enrich the debate and to contribute to the increasing body of literature by examining and analyzing the organizational and institutional changes taken place in the HTO; and to place the HTO’s case within the international debate regarding the privatization of state-owned companies and the importance of CG mechanisms as instruments of change. It is argued that the privatization of state-owned companies, when is accompanied with appropriate reform measures, can produce multiple positive effects. CG reforms were the main instruments that used in order to prepare the telecommunications incumbent to face the open and competitive markets.Corporate Governance Hellenic Telecommunications Organization (HTO), state-owned companies, privatization, change

Immigrants and Homeownership in Urban America: An Examination of Nativity, Socio-economic Status and Place

A unique pilot project conducted in America's small and medium-sized cities shows that broad-based community coalitions can proactively integrate the newcomers who are increasingly transforming Main St., USA. In the first project of its kind, a consortium of leading organizations in three mid-sized metropolitan areas undertook inclusive community-building. The project's final report contains valuable findings for policymakers, funders and organizations collectively approaching the challenge of helping newcomers adapt to their new communities and local communities welcome newcomers