Turbulent fluctuations above the buffer layer of wall-bounded flows

The behaviour of the velocity and pressure fluctuations in the logarithmic and outer layers of turbulent flows is analysed using spectral information and probability density functions from channel simulations at Reτ _2000. Comparisons are made with experimental data at higher Reynolds numbers. It is found, in agreement with previous investigations, that the intensity profiles of the streamwise and spanwise velocity components have logarithmic ranges that are traced to the widening spectral range of scales as the wall is approached. The same is true for the pressure, both theoretically and observationally, but not for the normal velocity or for the tangential stress cospectrum, although even those two quantities have structures with lengths of the order of several hundred times the wall distance. Because the logarithmic range grows longer as the Reynolds number increases, variables which are ‘attached’ in this sense scale in the buffer layer in mixed units. These results give strong support to the attached-eddy scenario proposed by Townsend (1976), but they are not linked to any particular eddy model. The scaling of the outer modes is also examined. The intensity of the streamwise velocity at fixed y/h increases with the Reynolds number. This is traced to the large-scale modes, and to an increased intensity of the ejections but not of the sweeps. Several differences are found between the outer structures of different flows. The outer modes of the spanwise and wall-normal velocities in boundary layers are stronger than in internal flows, and their streamwise velocities penetrate closer to the wall. As a consequence, their logarithmic layers are thinner, and some of their logarithmic slopes are different. The channel statistics are available electronically at http://torroja.dmt.upm.es/ftp/channels/

Joven diáspora marroquí y usos mediáticos. Estudio del proceso de adaptación post-migratoria en España

El objetivo de este artículo es analizar los procesos de adaptación de la población joven marroquí, a través de sus usos mediáticos en un contexto de ralentización y estabilización de los flujos migratorios en España. El acceso a los medios de comunicación es un factor importante para entender los procesos de adaptación en la nueva sociedad. En este sentido, los medios de comunicación ofrecen a las familias migrantes oportunidades para conocer de primera mano la sociedad de acogida, sin perder la conexión con la sociedad de origen; y, al mismo tiempo, constituyen una plataforma para la expresión de sus propias experiencias y puntos de vista. Partiendo de una revisión crítica de las concepciones tradicionales de integración, el artículo se fundamenta en la noción de diáspora. Se aplica un cuestionario sobre una muestra de 40 jóvenes marroquíes y de otras nacionalidades del mundo árabe, con el fin de conocer sus trayectorias personales y usos mediáticos. Los resultados muestran el papel central de los medios en los procesos vitales de los jóvenes, así como la conformación de múltiples itinerarios personales que se configuran en torno a una idea de diáspora transnacional, que conecta la comunidad de origen, la sociedad de acogida y la comunidad árabe imaginada.The aim of this paper is to analyze the processes of adaptation of Moroccan young people through their media uses in a context of slowing and stabilization of migration flows to Spain. Access to the media is an important factor to understand the processes of adaptation to the new society. In this sense, the media offer opportunities to migrant families to learn about the host society, without losing the connection with the society of origin, which at the same time provides a platform for the expression of their own experiences and views. Based on a critical review of the traditional concepts of integration, the article is focused on the notion of diaspora. A questionnaire was applied to a sample of 40 young Moroccans and other Arab nationals, in order to know their personal paths and media uses. The results show the central role of the media in their life curse, together with the idea of multiple personal itineraries built around the transnational diaspora conciousness, which connects the community of origin, the host society and the imagined Arab communit

Instalación del problema de la reforma de la Institución Policial en la Pcia. de Bs. As. en la agenda pública, en el período 1996-2007

Fil: González Sendín, María Julia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina

The persuasive use of political terms as source of terminological controversies

El significado emotivo que acompaña a muchos términos políticos ha dado lugar, en el ámbito de la teoría política, a numerosos desacuerdos sobre el uso de los mismos. Para ilustrar esas controversias me referiré a una discusión de Hans Kelsen con Lenin –sobre el concepto de democracia– y a otra con Eric Voegelin, en torno a la noción de representación política. Para identificar de qué tipo de desacuerdos se trata, utilizaré una clasificación de controversias terminológicas que proporciona Genaro CarrióThe emotional meaning that is usually associated with lots of political terms has led, in the frame of political theory, to many disagreements about their use. To illustrate these controversies I will refer to a discussion of Hans Kelsen with Lenin –about the concept of democracy– and another one with Eric Voegelin, that concerns the notion of political representation. To identify what kind of disagreements haven arisen, I will use a classification of terminological controversies provided by Genaro CarrióEste trabajo ha sido realizado en el marco del proyecto de investigación “El desván de la razón: cultivo de las pasiones, identidades éticas y sociedades digitales": PAIDESOC (FFI2017-82535-P

University and constant education: Chronicle of an educational public service failure

Uno de los elementos informadores de la nueva configuración de la formación universitaria es su consideración como un proceso de formación permanente. En este trabajo se analizan las motivaciones que subyacen bajo esta orientación que, en buena medida, conducen a una perdida sustantiva de derechos del trabajador y a un desequilibrio de la formación universitaria hacia la formación de profesionales, olvidando otros aspectos relevantes del sistema educativo. Se destaca en particular la falta de preocupación por dar una respuesta coherente a los colectivos más necesitados de esa formación permanente (desempleados de larga duración y jóvenes titulados que no han podido incorporarse al mercado laboral). Frente a ello choca la profunda atención que se ha prestado por el sistema universitario para rentabilizar estas necesidades de formación. Lo que demuestra el fracaso de las universidades en el cumplimiento de sus tareas como servicio público y su preocupante mercantilización.Education as a constant process is one of the new university system inspiring ideas. This study analyses the real causes of this orientation. This conception involves a loss of worker’s rights and shows a preference for one aspect of the university working system, professional training, leaving out other relevant elements. The lack of concern when it comes to giving a coherent response to the groups most in need of this training (the long-term unemployed and the young graduates who are unable to merge into the labour market) is particularly highlighted. As opposed to this, the deep attention the University system has paid to make these training needs more profitable, looks, to some extent, shocking to us. All of this is a good proof of the failure of universities in the fulfilment of its tasks as a public service and a sign of the University commercialization process

Multi-purpose infrastructure for delivering and supporting mobile context-aware applications

The use of contextual information in mobile devices is receiving increasing attention in mobile and ubiquitous computing research. An important requirement for mobile development today is that devices should be able to interact with the context. In this paper we present a series of contributions regarding previous work on context-awareness. In the first place, we describe a client-server architecture that provides a mechanism for preparing target non context-aware applications in order to be delivered as context-aware applications in a semi-automatic way. Secondly, the framework used in the server to instantiate specific components for context-awareness, the Implicit Plasticity Framework, provides independence from the underlying mobile technology used in client device, as it is shown in the case studies presented. Finally, proposed infrastructure deals with the interaction among different context constraints provided by diverse sensors. All of these contributions are extensions to the infrastructure based on the Dichotomic View of plasticity, which now offers multi-purpose support

El reto de la complejidad : discurso del académico electo Javier Jiménez Sendín leído en el acto de su recepción pública el día 14 de febrero de 2006 y contestación del académico Amable Liñán Martínez

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Direct numerical simulation of statistically stationary and homogeneous shear turbulence and its relation to other shear flows

Statistically stationary and homogeneous shear turbulence (SS-HST) is investigated by means of a new direct numerical simulation code, spectral in the two horizontal directions and compact-finite-differences in the direction of the shear. No remeshing is used to impose the shear-periodic boundary condition. The influence of the geometry of the computational box is explored. Since HST has no characteristic outer length scale and tends to fill the computational domain, long-term simulations of HST are “minimal” in the sense of containing on average only a few large-scale structures. It is found that the main limit is the spanwise box width, Lz, which sets the length and velocity scales of the turbulence, and that the two other box dimensions should be sufficiently large (Lx ≳ 2Lz, Ly ≳ Lz) to prevent other directions to be constrained as well. It is also found that very long boxes, Lx ≳ 2Ly, couple with the passing period of the shear-periodic boundary condition, and develop strong unphysical linearized bursts. Within those limits, the flow shows interesting similarities and differences with other shear flows, and in particular with the logarithmic layer of wall-bounded turbulence. They are explored in some detail. They include a self-sustaining process for large-scale streaks and quasi-periodic bursting. The bursting time scale is approximately universal, ∼20S−1, and the availability of two different bursting systems allows the growth of the bursts to be related with some confidence to the shearing of initially isotropic turbulence. It is concluded that SS-HST, conducted within the proper computational parameters, is a very promising system to study shear turbulence in general

Effectiveness of physical therapy for pregnancy-related low back and/or pelvic pain after delivery: A systematic review

[EN] The aim of this work was to investigate the effectiveness of physical therapy for the treatment of low back pain (LBP) and pelvic girdle pain (PGP) related to pregnancy after delivery. A systematic review of studies published since 1985 in the databases Medline, PEDro, SciELO, SCOPUS, LILACS, and the Cochrane Library was made. Studies that focused on postpartum LBP or PGP, without being related to pregnancy or in other non-pregnant patients, were excluded, as were papers addressing LBP or PGP indicating radiculopathy, rheumatism, or any other serious disease or pathologic condition. In accordance with the exclusion criteria and duplicate articles, of the 105 articles retrieved only six were considered for quality assessment with the PEDro Scale. Among these six papers, two were follow-ups, such that only four trials were included in this review. All trials used exercise for motor control and stability of the lumbopelvic region, but with different intervention approaches. The study affording the best evidence used individual guidance and adjustments given by the physiotherapists. Nevertheless, this systematic review was inconclusive and showed that more randomized clinical trials, with good quality, are needed