Swinging Atwood's Machine: Experimental and Theoretical Studies

A Swinging Atwood Machine (SAM) is built and some experimental results concerning its dynamic behaviour are presented. Experiments clearly show that pulleys play a role in the motion of the pendulum, since they can rotate and have non-negligible radii and masses. Equations of motion must therefore take into account the inertial momentum of the pulleys, as well as the winding of the rope around them. Their influence is compared to previous studies. A preliminary discussion of the role of dissipation is included. The theoretical behaviour of the system with pulleys is illustrated numerically, and the relevance of different parameters is highlighted. Finally, the integrability of the dynamic system is studied, the main result being that the Machine with pulleys is non-integrable. The status of the results on integrability of the pulley-less Machine is also recalled.Comment: 37 page

A list of all integrable 2D homogeneous polynomial potentials with a polynomial integral of order at most 4 in the momenta

We searched integrable 2D homogeneous polynomial potential with a polynomial first integral by using the so-called direct method of searching for first integrals. We proved that there exist no polynomial first integrals which are genuinely cubic or quartic in the momenta if the degree of homogeneous polynomial potentials is greater than 4.Comment: 22 pages, no figures, to appear in J. Phys. A: Math. Ge

Aún viene el coco : origen, pervivencia y transformación de un clásico del miedo infantil

Este artículo se centra en la figura mitológico-folclórica del coco, analizando su origen etimológico, así como sus funciones y significados desde las primeras manifestaciones escritas en el siglo XV. Un trabajo de campo con encuestas y entrevistas realizado entre 2009 y 2016 nos permite conocer de primera mano las variaciones simbólicas de este personaje fantástico en Andalucía, pero también descubrir las continuidades y rupturas con respecto a cómo se provoca y se experimenta el miedo infantil en los siglos XX y XXI, desde una original indefinición vinculada a lo negro y oscuro, hasta las actuales mezcolanzas de la cibercultura, donde se hacen presentes las imágenes de seres terroríficos o inocentes de series televisivas, películas y videojuegos. El análisis del coco nos revela una de las maneras de representación de la otredad, a través de un personaje difuso y confuso, a medio camino entre el hombre, el animal y el monstruo.We discuss in this paper a mythological and folkloric figure, the coco, analyzing its etymological origin, as well as its functions and meanings from its first manifestations in the 15th century. A fieldwork with surveys and interviews done between 2009 and 2016 allows us to know first hand the symbolic variations of this fantastic beeing in Andalusia (Spain), but also to discover the continuities and breaks with regard to how the child's fear is provoked and experienced in the 20th and 21st century, from an original lack of definition linked to the black and dark, up to the current mixtures of the cyberculture, where become present the images of terrifying or innocent beings from television series, movies and video games. The analysis of the coco reveals a way of representation the otherness through a diffuse and confused character, halfway between the man, the animal and the monster

Statins and protein prenylation in cancer cell biology and therapy

El pdf del artículo es la versión post-print.The use of statins has scaled up to become one of the most prescribed medicines in the world and have been very useful in the manegement of cardiovascular diseases and related mortality. The disclosure of their chemical structure similar to that of hydroxy methyl glutaryl-CoA (HMG-CoA) revealed their ability to compete with and inhibit the rate-limiting enzyme HMG-CoA reductase that catalyzes the synthesis of mevalonate, which then serves as the precursor for isoprenoids and cholesterol in the mevalonate pathway. While most of the effects of statins are associated with the lowering of cellular cholesterol levels, it is clear that they also blunt the non-sterol branch of the mevalonate pathway, decreasing formation of isoprenoids and altering protein-prenylation, a critical event in the posttranslational modulation of proteins involved in the regulation of cell cycle progression, proliferation and signaling pathways. Randomized controlled trials for the prevention of cardiovascular diseases indicated that statins elicited provocative and unexpected benefits for reducing a number of different types of cancers, including colorectal carcinoma, melanoma, prostate and hepatocellular carcinoma, although in other cancer types the preclinical expectations of statins were dissapointing. In this review, we will describe the evidence and mechanisms underlying the potential beneficial use of statins and the role of protein prenylation in cancer prevention. Of relevance, the combination of statins with other anti cancer drugs may be a significant asset in malignancies resistant to current therapy. © 2012 Bentham Science Publishers.The work was supported by CIBEREHD, Fundación Mutua Madrileña, Fundació la Marató de TV3, PI11/03025 (META) and grants PI09/0056 (Instituto de Salud Carlos III), SAF2009-11417, SAF2008-02199, SAF2011-23031 (Plan Nacional de I+D), Spain; and P50-AA-11999 (Research Center for Liver and Pancreatic Diseases, NIAAA/NIH).Peer Reviewe

The work of flamenco in a cosmopolitan environment. Dynamics and conceptions.

El tema de este artículo es el flamenco como trabajo en un contexto cosmopolita, Bruselas y Flandes. Se exponen las principales estrategias laborales de los artistas, algunos problemas especiales con los que se encuentran y su diversa concepción del trabajo. Los artistas, que emplean sus recursos de forma creativa y racional, deben 'pasar las fronteras' de continuo. Esto favorece a algunos en detrimento de los depositarios de la tradición, quienes no obstante también juegan sus bazas. El estudio se ha realizado mediante la observación participante y entrevistas a los agentes significativos del flamenco en Bélgica.The subject of this article is flamenco as a job in a cosmopolitan context, Brussels and Flanders. It expounds on the main strategies of the performers, some special problems that they encounter and their conceptions of the job. The performers who utilize their resources in a creative and logical fashion, must constantly go beyond the limits. This benefits some, to the detriment of the custodians of tradition, who nevertheless also play their trump cards. This study has been carried out by means of participative observation and interviews with significant flamenco agents in Belgium.- Grupo de investigación Antropología y Filosofía (SEJ-126). Universidad de Granada. - Área de Antropología Social. Universidad de Jaén. - Laborarorio de Antropología Social y Cultural (HUM-472). Universidad de Almería. - Departamento de Filosofía II. Universidad de Granada

Lógicas para la violencia en la escuela

La violencia escolar está íntimamente ligada a la crisis de las instituciones educativas, en tanto que éstas son, desde el punto de vista histórico, instrumentos privilegiados del Estado-nación. Éste ha cedido su lugar al mercado como absoluto social, y, por consiguiente, el sistema educativo está siendo reconvertido para servir a dicho mercado, lo que implica su desacralización. Las instancias políticas están contribuyendo de forma decisiva a este transcurso, que tiene su elemento más importante en la radical transformación de la figura del docente

De cante, baile y toque en la emigración. Sociabilidad en torno al flamenco en Bélgica, 1956-1975

From the end of the 1950s onwards, numerous workers emigrated from Spain to Belgium. Many of them took flamenco music and dance practice with them as a means of relating to one another at gatherings, parties and other spaces for sociability. Soon, this form of expression became emblematic and constituted a powerful medium to maintain bonds between the emigrants, but it was also an instrument for integration into local society, as well as a source of economic resources. A dense network of restaurants, bars and associations run by Spaniards were formed, in which flamenco played a significant role. This paper describes this process up to the end of Franco’s regime and outlines the main components related with sociability based around flamenco within this context.Desde finales de los años cincuenta emigran a Bélgica numerosos trabajadores procedentes de España. Muchos llevan consigo el flamenco como forma de relación en reuniones, fiestas y otros espacios de sociabilidad. Pronto esta forma expresiva se convirtió en emblemática y constituyó un poderoso medio para el mantenimiento de vínculos entre los emigrantes, pero también un instrumento para la integración en la sociedad local, así como una fuente de recursos económicos. Se formó una densa red de restaurantes, bares y asociaciones regentados por españoles, en los que el flamenco tuvo un papel de gran relevancia. En este artículo se describe ese proceso hasta el final del franquismo, y se exponen los principales componentes relacionados con la sociabilidad en torno al flamenco en ese contexto

Artistas flamencos “en el extranjero”: un entramado cultural

En este artículo abordo el flamenco en el extranjero y en un contexto multicultural, mediante el estudio de varios casos. Es fruto de un trabajo etnográfico realizado en Bélgica entre 2007 y 2010. El flamenco constituye un código que otorga un marco de referencia para los artistas que intervienen en él. Pero esto no implica que compartan significados ni pautas de acción. Los artistas allí residentes se posicionan de diferente manera ante ese código, y articulan diversidad de trayectorias y respuestas. Sus posicionamientos no derivan solo de las estrategias individuales, sino que están mediatizados por factores estructurales, como la etnicidad.In this paper I deal with flamenco in a foreign and multicultural context, by exploring several case studies. It is the result of an ethnographic work in Belgium over the years 2007 to 2010. Flamenco is a code that provides a collective framework for all the artists that play in that field. But this does not mean that they share meanings or patterns of action. Local artists adopt different attitudes towards the flamenco code, and they use diverse ranges of careers and responses. Their positioning is not only a consequence of their individual strategies, but they are influenced by structural factors such as ethnicity