Initial data giving rise to naked singularities in spherically symmetric dust collapse

The phase space corresponding to a particular four-parameter family of initial data for the gravitational collapse of a spherically symmetric dust cloud is investigated. In a certain limit of the parameters, this family reproduces the case of homogenous mass density -constant mass distribution- and zero initial velocity, while in another limit, it generates a globally naked singularity. We show that for initial data characterizing flat density profiles, as well as large initial velocities, the probability of forming a globally naked singularity is low.Comment: 5 pages, 5 figures, prepared for the proceedings of the IX Workshop of the Gravitational and Mathematical Physics Division of the Mexican Physical Society. Refereed versio

Extended I-Love relations for slowly rotating neutron stars

Observations of gravitational waves from inspiralling neutron star binaries---such as GW170817---can be used to constrain the nuclear equation of state by placing bounds on stellar tidal deformability. For slowly rotating neutron stars, the response to a weak quadrupolar tidal field is characterized by four internal-structure-dependent constants called "Love numbers." The tidal Love numbers $k_2^\text{el}$ and $k_2^\text{mag}$ measure the tides raised by the gravitoelectric and gravitomagnetic components of the applied field, and the rotational-tidal Love numbers $\mathfrak{f}^\text{o}$ and $\mathfrak{k}^\text{o}$ measure those raised by couplings between the applied field and the neutron star spin. In this work we compute these four Love numbers for perfect fluid neutron stars with realistic equations of state. We discover (nearly) equation-of-state independent relations between the rotational-tidal Love numbers and the moment of inertia, thereby extending the scope of I-Love-Q universality. We find that similar relations hold among the tidal and rotational-tidal Love numbers. These relations extend the applications of I-Love universality in gravitational-wave astronomy. As our findings differ from those reported in the literature, we derive general formulas for the rotational-tidal Love numbers in post-Newtonian theory and confirm numerically that they agree with our general-relativistic computations in the weak-field limit.Comment: 31 pages, 6 figures, 9 tables; v2: updated to match published versio

Mujeres empresarias en el sector turístico Huatulco, Oaxaca: la mirada masculina

En el turismo es habitual observar que las mujeres encuentran oportunidades de acceder a trabajos remunerados, pero además ofrece oportunidades de emprender negocios, de esta forma se puede encontrar a mujeres como empresarias o dueñas de negocios. El hecho de que una mujer contribuya al ingreso de la familia, la convierte en proveedora y comparta este rol con la pareja, llegando incluso a ganar más que los hombres, lo anterior puede contribuir a generar fricciones o conflictos en las relaciones entre géneros por el rol tradicional atribuido en una sociedad patriarcal a los varones de ser los proveedores, protectores y autoridad. En este texto se presentan los resultados de una investigación en la que se entrevistó a hombres que viven en el Centro Integralmente Planeado Bahías de Huatulco, México para conocer sus percepciones sobre la labor empresarial de las mujeres y cómo influye ésta en sus roles de género a la luz del modelo hegemónico de masculinidad. Los resultados indican que dicho modelo tiene fisuras, ya que a cambio de ser “ayudados” en su rol de proveedor, deben aceptar la participación de las mujeres en las decisiones de la familia y aprender a aceptar cierto nivel de independencia.PROMEP-SE

Why the students of fifth year of the morning shift at Salomón de la Selva high school in Managua have a low level of proficiency in speaking and pronunciation skills in English as a foreign language

Nowadays English language has been one of the most relevant educational factors in Nicaragua and the population is being demanded to acquire it as a second language to exchange our cultural, social, political and economical aspects with foreign countries. During many years students in high schools have been taking English as a part of the curriculum set by the minister of education and therefore used by the teachers in public schools. In this research, we intend to find out the reasons that cause a low level of proficiency in speaking and pronunciation skills that students have in the second language acquisition and mostly, we have observed that the students of fifth year at Salomón de la Selva high school have a lot of difficulties in speaking and pronunciation skills through the teaching and learning process in the classroom. The problem has aroused our interest to look for specific information to help us find a solution. We focus our attention on the possible factors that lead to the problem of our concern: the materials used in the classroom and the kind of techniques the teacher carries out in class in order to fulfill his objectives. Our work lets you know about the previous knowledge and the linguistic problems the students have in English. And also how this can negatively affect them during their learning process in their last level of secondary schoo