Scalar field quasinormal modes on asymptotically locally flat rotating black holes in three dimensions

The pure quadratic term of New Massive Gravity in three dimensions admits asymptotically locally flat, rotating black holes. These black holes are characterized by their mass and angular momentum, as well as by a hair of gravitational origin. As in the Myers-Perry solution in dimensions greater than five, there is no upper bound on the angular momentum. We show that, remarkably, the equation for a massless scalar field on this background can be solved in an analytic manner and that the quasinormal frequencies can be found in a closed form. The spectrum is obtained requiring ingoing boundary conditions at the horizon and an asymptotic behavior at spatial infinity that provides a well-defined action principle for the scalar probe. As the angular momentum of the black hole approaches zero, the imaginary part of the quasinormal frequencies tends to minus infinity, migrating to the north pole of the Riemann Sphere and providing infinitely damped modes of high frequency. We show that this is consistent with the fact that the static black hole within this family does not admit quasinormal modes for a massless scalar probe.Comment: 17 pages, 5 figures. V2: improved figures. V3: typos corrected, references added and title slightly changed to match the version to appear in EPJ

Talento, experto o las dos cosas

En ocasiones es difícil discernir entre el concepto de individuo con talento e individuo experto. Sin duda se debe a que los roles que ofrecen los individuos que alcanzan el éxito en el deporte, la música, el teatro, la literatura, etc., son una muestra de ambas condiciones: una si se quiere innata, el talento, y otra adquirida, la de ser experto. También, a veces, desearíamos que los talentos trabajasen para además ser expertos, aspecto que los elevaría a un grado superior de excelencia. En el presente artículo se realiza una puesta al día de ambos conceptos con el objeto de establecer una base adecuada sobre la que se sostengan con mayor solidez las decisiones y actuaciones del formador. También se presentan algunas nociones sobre el seguimiento y control de los muchachos que disfrutan en las canteras deportivas siempre con la orientación básica de formar individuos completos con un rendimiento óptimo

Talent, expert o les dues coses

De vegades és difícil distingir els conceptes d’individu amb talent i individu expert. Sens dubte, això és degut a que els individus que assoleixen l’èxit en l’esport, la música, el teatre, la literatura, etc. mostren ambdues condicions: una si es vol innata, el talent, i una altra adquirida, la de ser expert. També, de vegades, desitjaríem que els talents treballessin per a ser experts, aspecte que els elevaria a un grau superior d’excel·lència. En el present article es realitza una posada al dia d’ambdós conceptes amb l’objectiu d’establir una base adequada sobre la que sostenir amb més solidesa les decisions i actuacions del formador. També es presenten algunes nocions sobre el seguiment i control dels nois que gaudeixen en les canteres esportives sempre amb l’orientació bàsica de formar individus complerts amb un rendiment òptim.Distinguishing between the concepts of talent and expertise is sometimes difficult. This is undoubtedly because persons successful in sports, music, acting and literature, etc. show a mixture of both qualities, talent being innate while expertise is acquired. Sometimes we would also wish that talented individuals would apply themselves to becoming experts, which would allow them to achieve a higher degree of excellence. The present article provides an update on both concepts with a view to establishing a solid base for trainers’ decisions and interventions. Some notions on following the progress of boys participating in sports academies are presented from the perspective of producing well-rounded individuals with optimal performance

Creating And Sharing Knowledge Through A Corporate Social Networking Site: The Impact Of Employees\u27 Perceptions On Effectiveness

There have been various claims that enterprise social networking sites (ESN) might improve business effectiveness and performance. Nevertheless, many of the initiatives supported by ESNs have failed. This paper argues that divergent perceptions about ESNs across the different levels of the organization may explain failures in ESNs’ design and implementation. Using an extended version of the Technological Frames of Reference framework (Orlikowski & Gash, 1994), this paper reports on a study that analyzed employee’s perceptions about an ESN within a software engineering firm. It was found that significant divergent perceptions in the organization led to a social order that discouraged employees to create and share knowledge through the ESN. This paper highlights the importance of aligning top management perceptions about the ESN with its actual scope. It also highlights the relevance of aligning perceptions about the ESN across the different levels of the organization. This paper proposes extending the original Technological Frames of Reference framework in order to better understand people’s perceptions about technologies that support knowledge management systems. It also proposes an explanatory model for understanding how people’s perceptions about a corporate social networking site impact on its usage