45,968 research outputs found
Stellar footprints of a variable G
Theories with varying gravitational constant have been studied since long
time ago. Among them, the most promising candidates as alternatives of the
standard General Relativity are known as scalar-tensor theories. They provide
consistent descriptions of the observed universe and arise as the low energy
limit of several pictures of unified interactions. Therefore, an increasing
interest on the astrophysical consequences of such theories has been sparked
over the last few years. In this essay we comment on two methodological
approaches to study evolution of astrophysical objects within a varying-
theory, and the particular results we have obtained for boson and white dwarf
stars.Comment: This essay received Honorable Mention in the 1999 Essay Competition
of the Gravity Research Foundatio
A Daily Diary Investigation of Latino Ethnic Identity, Discrimination, and Depression
The objectives of the current study were to document the effects of discrimination on Latino mental health and to identify the circumstances by which ethnic identity serves a protective function. Instances of discrimination and depressive symptoms were measured every day for 13 days in a sample of Latino adults (N = 91). Multilevel random coefficient modeling showed a 1-day lagged effect in which increases in depression were observed the day following a discriminatory event. The findings also revealed differential effects of ethnic identity exploration and commitment. Whereas ethnic identity exploration was found to exacerbate the influence of daily discrimination on next-day depression, ethnic identity commitment operated as a stress buffer, influencing the intensity of and recovery from daily discrimination. The findings are discussed within a stress and coping perspective that identifies appropriate cultural resources for decreasing the psychological consequences associated with daily discrimination
Modelling incomplete fusion dynamics of weakly-bound nuclei at near-barrier energies
The classical dynamical model for reactions induced by weakly-bound nuclei at
near-barrier energies is developed further. It allows a quantitative study of
the role and importance of incomplete fusion dynamics in asymptotic
observables, such as the population of high-spin states in reaction products as
well as the angular distribution of direct alpha-production. Model calculations
indicate that incomplete fusion is an effective mechanism for populating
high-spin states, and its contribution to the direct alpha production yield
diminishes with decreasing energy towards the Coulomb barrier. It also becomes
notably separated in angles from the contribution of no-capture breakup events.
This should facilitate the experimental disentanglement of these competing
reaction processes.Comment: 12 pages, 7 figures (for better resolution figures please contact the
author), Accepted in Journal of Physics
Quark matter equation of state and stellar properties
In this paper we study strange matter by investigating the stability window
within the QMDD model at zero temperature and check that it can explain the
very massive pulsar recently detected. We compare our results with the ones
obtained from the MIT bag model and see that the QMDD model can explain larger
masses, due to the stiffening of the equation of state
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