CMB Tensor Anisotropies in Metric f(R) Gravity

We present a description of CMB anisotropies generated by tensor perturbations in f(R) theories of gravity. The temperature power spectrum in the special case of $f(R)=R^n$ is computed using a modified version of CAMB package.Comment: 4 pages, 1 figure. Contribution submitted to the proceedings of the Spanish Relativity Meeting ERE2011, September 2011, Madrid, Spai

On tidal forces in f(R) theories of gravity

Despite the extraordinary attention that modified gravity theories have attracted over the past decade, the geodesic deviation equation in this context has not received proper formulation thus far. This equation provides an elegant way to investigate the timelike, null and spacelike structure of spacetime geometries. In this investigation we provide the full derivation of this equation in situations where General Relativity has been extended in Robertson-Walker background spacetimes. We find that for null geodesics the contribution arising from the geometrical new terms is in general non-zero. Finally we apply the results to a well known class of f(R) theories, compare the results with General Relativity predictions and obtain the equivalent area distance relation.Comment: 9 pages, 2 figure

Covariant gauge-invariant perturbations in multifluid f(R) gravity

We study the evolution of scalar cosmological perturbations in the (1+3)- covariant gauge-invariant formalism for generic $f(R)$ theories of gravity. Extending previous works, we give a complete set of equations describing the evolution of matter and curvature fluctuations for a multi-fluid cosmological medium. We then specialize to a radiation-dust fluid described by barotropic equations of state and solve the perturbation equations around a background solution of $R^{n}$ gravity. In particular we study exact solutions for scales much smaller and much larger than the Hubble radius and show that $n>2/3$ in order to have a growth rate compatible with the M\'esz\'aros effect.Comment: 32 pages, 3 figures, published versio

Estrés laboral y compromiso organizacional de los trabajadores de salud de un policlínico en Lima sur - Perú, 2021

El objetivo de la investigación fue determinar si existe relación entre el estrés laboral y el compromiso organizacional de los trabajadores de salud de un Policlínico en Lima Sur-Perú, 2021. El estudio fue de tipo aplicado, enfoque cuantitativo, diseño no experimental, transversal y correlacional; se aplicó en forma presencial la Escala de Estrés Laboral de la OIT-OMS (α Cronbach de ,965) y la Escala de Compromiso Organizacional (α Cronbach de ,835) a 55 trabajadores de salud. Se obtuvo principalmente un nivel de estrés laboral bajo (61.8%) y un nivel de compromiso organizacional alto (50.9%) de los trabajadores. Además, se determinó una relación inversa baja entre el estrés laboral y el compromiso organizacional (-,337), compromiso afectivo (-,301) y compromiso normativo (- ,300); mientras que con el compromiso de continuidad se dio una relación inversa moderada (-,438); por lo que se concluyó que los niveles de estrés laboral se relacionaron inversamente con los niveles de compromiso organizacional y sus dimensiones en los trabajadores de salud del Policlínico de Lima Sur-Perú, reflejando una adecuada gestión administrativa por parte del establecimiento de salud y una respuesta apropiada de desempeño de los trabajadores por su nivel de compromiso organizacional

Nuclear organization in stress and aging

This article belongs to the Special Issue Nuclear Organisation.The eukaryotic nucleus controls most cellular processes. It is isolated from the cytoplasm by the nuclear envelope, which plays a prominent role in the structural organization of the cell, including nucleocytoplasmic communication, chromatin positioning, and gene expression. Alterations in nuclear composition and function are eminently pronounced upon stress and during premature and physiological aging. These alterations are often accompanied by epigenetic changes in histone modifications. We review, here, the role of nuclear envelope proteins and histone modifiers in the 3-dimensional organization of the genome and the implications for gene expression. In particular, we focus on the nuclear lamins and the chromatin-associated protein BAF, which are linked to Hutchinson–Gilford and Nestor–Guillermo progeria syndromes, respectively. We also discuss alterations in nuclear organization and the epigenetic landscapes during normal aging and various stress conditions, ranging from yeast to humans.Work in the M.A.-S. and P.A. laboratories is funded by the Spanish Ministry of Science, Innovation and Universities (BFU2016-79313-P to P.A. & MDM-2016-0687 to P.A. and M.A.-S.), the European Research Council (ERC-2011-StG-281691 to M.A.-S.) and the European Regional Development Fund.Peer reviewe