Critique [of Racial Intelligence Testing and the Mexican People]

Gilbert Gonzalez’s “Racial Intelligence Testing and the Mexican People is a major contribution in analyzing the educational factors which result in social inequality among the Mexican population in the US. For decades, the power elite has espoused the myth that educational achievement for minorities is the key to social upward mobility. Instead, Gonzalez views education as a system which perpetuates and maintains racial and class divisions in our society

Person to Person in France

While still in the midst of their study abroad experiences, students at Linfield College write reflective essays. Their essays address issues of cultural similarity and difference, compare lifestyles, mores, norms, and habits between their host countries and home, and examine changes in perceptions about their host countries and the United States. In this essay, Luis Santillan-Guzman describes his observations during his study abroad program at the American University Center of Provence in Marseilles, France

Cosmological singularity theorems for f(R)f(R) gravity theories

In the present work some generalizations of the Hawking singularity theorems in the context of $f(R)$ theories are presented. The assumptions are of these generalized theorems is that the matter fields satisfy the conditions $\bigg(T_{ij}-\frac{g_{ij}}{2} T\bigg)k^i k^j\geq 0$ for any generic unit time like field, that the scalaron takes bounded positive values during its evolution, and that the resulting space time is globally hyperbolic. Then, if there exist a Cauchy hyper surface $\Sigma$ for which the expansion parameter $\theta$ of the geodesic congruence emanating orthogonally from $\Sigma$ satisfies some specific conditions, it may be shown that the resulting space time is geodesically incomplete. Some mathematical results of reference \cite{fewster} are very important for proving this. The generalized theorems presented here apply directly some specific models such as the Hu-Sawicki or Starobinsky ones \cite{especif3}, \cite{capoziello4}. However, for other scenarios, some extra assumptions should be implemented for the geodesic incompleteness to take place. However, the negation of the hypothesis of these results does not necessarily imply that a singularity is absent, but that other mathematical results should be considered to prove that.Comment: An improved version is published in JCAP 05 (2016) 02

The Newton constant and gravitational waves in some vector field adjusting mechanisms

As is well known, there exist some Lorentz breaking scenarios which explain the smallness of the cosmological constant in the present era. An important aspect to analyze is the propagation of gravitational waves and the screening or enhancement of the Newton constant $G_N$ in these models. The problem is that the Lorentz symmetry breaking terms may induce an unacceptable value of the Newton constant $G_N$ or introduce longitudinal modes in the gravitational waves. Furthermore there may spoil the standard dispersion relation $\omega=ck$. In [21] the authors have presented a model for which they suggest that the behavior of the gravitational constant is the correct one for asymptotic times. In the present work, an explicit checking is made and we finally agree with these claims. Furthermore, it is suggested that the gravitational waves are also well behaved for large times. In the process, some new models with the same behavior are obtained, thus enlarging the list of possible adjustment mechanisms.Comment: Some subtle detail about the gauge are corrected. No further change