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

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

Reflections on Restoring Integrity to the United States Immigration System: A Personal Vision

In the debate on US immigration reform, a number of legislative proposals have been introduced.To be effective, reforms must take into account the lessons learned from implementing the Immigration Reform and Control Act of 1986 (IRCA).This policy brief summarizes these lessons learned as follows: * The robust and growing demand for work and family reunification visas must be incorporated into new policies;* Legalization should not be done halfway;* Reducing incentives for fraud should be a top policy goal; and* Migration is a complex phenomenon that cannot be managed unilaterally; it requires cooperation among neighboring countries.The policy brief argues that there are three "E"s required to achieve stable reform:* Enforcement that devises smarter border and interior controls that are consistent with America's values, temperament, and philosophy of government powers;* Expanded numbers of visas that address the continuing demand, especially from citizens of the countries on America's borders; and* Earned regularization that offers a realistic and fair opportunity to the unauthorized resident population in the United States to earn lawful permanent status

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