Derivation of Friedman Equations

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2014, Tutor: Eduard Salvador SoléIn this report we make a detailed derivation of Friedman Equations, which are the dy- namical equations of a homogeneous and isotropic universe. First, we derive them in the framework of the General Relativity keeping the relativistic expressions as a reference for the rest of the report. Then, using the Newtonian formalism and solving some fundamental problems, we reach some dy- namical equations for the universe and compare the results with the relativistic ones, focusing our attention on the meaning of the expressions and on the cosmological constant

El paper de la dona a la publicitat : la manipulació d'una imatge

Aquest article és el fruit del treball dut a terme en un seminari de sociologia durant el curs 1977-1978. A partir de l'anàlisi d'una mostra d'anuncis publicitaris diversos, però que tenen com a denominador comú la presència de la dona, hom intenta veure quin és l'estereotip de la dona vehiculat per la publicitat. L'elaboració d'un codi de classificació permet de situar la dona dels anuncis en diferents etapes de la seva vida i en l'exercici de papers diversos: nena, noia, esposa, mare, mestressa de casa, dona en el treball i dona amant. Però en aquesta diversitat de situacions no hi ha mai contradicció, sinó un model coherent i únic: la nena i la noia són ja dones, i les dones continuen essent sempre criatures; casolana encara que treballi, la dona és simultàniament esposa, mare i amant. Les dues característiques fonamentals d'aquest estereotip de la dona als anuncis publicitaris són, d'una banda, la constant accentuació de la seva dimensió eròtica i sexual i, de l'altra, la seva sistemàtica subordinació a l'home. D'aquesta manera la publicitat acompleix una doble funció, de reproducció de la ideologia dominant, i de legitimació i reforçament d'aquesta mateixa ideologia

Numerical study of the aerodynamics of sound sources in a bass-reflex port

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.The aim of this paper is to study the aerodynamics phenomena of a bass-reflex port that causes noise in the audible frequency range. After discarding structural and mechanical vibration issues, the hypothesis considered is that vortex shedding is the source of the noise. Experimental and numerical evidences of the vortex, an analysis of its noise and the similarities between real and simulated performance are presented. The numerically simulated cases with the original geometry are excited at different frequencies and with modifications of the port geometry. Likewise, the internal performance of an enclosure with a closed port was simulated. The simulations have been performed with axisymmetrical geometries using the open-source OpenFOAM® toolbox. Moreover, experimental measurements were carried out. First, acoustic signal experiments were done to analyse the response of the bass-reflex ports. Secondly, a structure vibration measurement was conducted in order to exclude the cabinet structure vibration as a source of the noise in question. A good agreement was found between numerical and experimental results, especially in the frequency band of the detected noise, i.e. the 1000–1500 Hz range. Despite no remarkable improvement being made with the geometry changes explored, the presented CFD approach has proved a useful and cost-effective tool to address this kind of phenomenon.Peer ReviewedPostprint (published version

Intermediate care: An important contribution to integrate care for older people , in Osona.

Geriatric care, has been playing a key role in the integration of services. Development of intermediate care is a good example. In modern hospitals alternative services to hospitalization had been developed, especially those for elderly patients who are the main users of hospitals. There is an internationally significant interest to create services that occupy the virtual space between primary and hospital care, which is known as intermediate care. The main functions of intermediate care is to provide different options to hospitalization, like preventing admission or easing discharge. The process should last less than 6 weeks and can take place in hospital or at home

Aproximación a la posible existencia de la señal de los ciclos solares 18 y 19 en la pluviometría de la Península Ibérica

Based on the methodology used in a study in the U.S. (Perry, 1994), significant correlations are found between rainfall in the Iberian Peninsula and the most active solar period registered (1939-1969), with a three-year lag for the Atlantic area in the north of the Iberian peninsula, and a four-year lag for the southwest. These delays correspond to the shifting period of sea thermal anomalies within the Gulf current from the north Atlantic tropical calm. Nevertheless, the most unexpected result is the high correlation found in rainfalls on the gulf of Valencia with no temporal gap, a fact that is attributable to the reduced and semi-closed configuration of the Mediterranean.A partir de la metodología empleada en un estudio de los E.E.U.U.(Perry, 1994), se hallan correlaciones significativas entre la pluviometría ibérica y el período solar más activo registrado (1939-1969), con un desfase de tres años, para el ámbito atlántico del norte peninsular, y de 4 años, para el del suroeste. Estos retrasos corresponden al período de desplazamiento, desde las calmas tropicales noratlánticas, de anomalías térmicas marinas en el seno de la corriente del Golfo. No obstante, el resultado más inesperado es la alta correlación hallada con la pluviometría del golfo de Valencia sin desfase temporal, hecho atribuible a la configuración reducida y semicerrada del mar Mediterráneo