The cosmological constant as an eigenvalue of the Hamiltonian constraint in Horava-Lifshits theory

In the framework of Horava-Lifshitz theory, we study the eigenvalues associated with the Wheeler-DeWitt equation representing the vacuum expectation values associated with the cosmological constant. The explicit calculation is performed with the help of a variational procedure with trial wave functionals of the Gaussian type. We analyze both the case with the detailed balanced condition and the case without it. In the case without the detailed balance, we find the existence of an eigenvalue depending on the set of coupling constants (g2,g3) and (g4,g5,g6), respectively, and on the physical scale.Comment: RevTeX,11 Pages, Substantial Improvements. References added. To appear in Phys.Rev.

Cultivating Contextual Attributes in the Integration of Latin@ Educational Leadership

Although the Latino population is growing rapidly in the United States, there is a disproportionate paucity of literature on the perspectives and challenges of Latino/a educational leaders. Culturally aware educational leadership can help to improve retention and student engagement of Latino students. The purpose of this article is to explore the factors influencing the educational experience and perspective of Latino/a students and leaders to expand the understanding of Latinos within the education system. Identifying role models, creating network and professional development opportunities, as well as offering training programs are practices to enhance the training and expertise of Latino educational leaders. Implications and recommendations for practice and research are discussed

Magnetic field evolution and equilibrium configurations in neutron star cores: the effect of ambipolar diffusion

As another step towards understanding the long-term evolution of the magnetic field in neutron stars, we provide the first simulations of ambipolar diffusion in a spherical star. Restricting ourselves to axial symmetry, we consider a charged-particle fluid of protons and electrons carrying the magnetic flux through a motionless, uniform background of neutrons that exerts a collisional drag force on the former. We also ignore the possible impact of beta decays, proton superconductivity, and neutron superfluidity. All initial magnetic field configurations considered are found to evolve on the analytically expected time-scales towards "barotropic equilibria" satisfying the "Grad-Shafranov equation", in which the magnetic force is balanced by the degeneracy pressure gradient, so ambipolar diffusion is choked. These equilibria are so-called "twisted torus" configurations, which include poloidal and toroidal components, the latter restricted to the toroidal volumes in which the poloidal field lines close inside the star. In axial symmetry, they appear to be stable, although they are likely to undergo non-axially symmetric instabilities.Comment: MNRAS, accepte

Discrimination in the Workplace: Evidence from a Civil War in Peru

Few events give the opportunity to observe the full range of human behavior as wars do. In the case of civil wars in ethnically-mixed societies, the distribution of violence across various segments of the population can provide evidence on the extent and nature of discrimination. As in the case of markets, identifying discrimination in the warplace is challenging. There is uncertainty on the reconstruction of events as well as the rationale behind the violence. We use a unique data set collected by the Peruvian Truth and Reconciliation Commission on war crimes during the 1980's to show that there is evidence of taste-based discrimination by agents of the state towards ethnic minorities and women. The evidence is robust to different assumptions on the logic of repression and missing data problems. Working Paper 07-3