Finite-size effects in intracellular microrheology

We propose a model to explain finite-size effects in intracellular microrheology observed in experiments. The constrained dynamics of the particles in the intracellular medium, treated as a viscoelastic medium, is described by means of a diffusion equation in which interactions of the particles with the cytoskeleton are modelled by a harmonic force. The model reproduces the observed power-law behavior of the mean-square displacement in which the exponent depends on the ratio between particle-to-cytoskeleton-network sizes.Comment: 6 pages 2 figures. To appear in the Journal of Chemical Physic

Liderança critica aplicada através da lens latinas: um abordagem alternativo do liderança educacional

The aims and objectives of this research were to investigate and better understand ways in which race and gender play out as differences of significant consequence in applied leadership practice. Utilizing qualitative case study methodology coupled with counter-story, a critical race theory approach, the authors analyze data on two Mexican descent educational leaders in the US: one Latino K-6 principal and one Chicana university Dean. Findings indicate evidence supporting positive identity leadership traits as practiced through raced and gender lenses, resulting in effective socially just and equitable leadership outcomes for the participants in the study. These findings are new and particularly relevant as demographic shifts in the US and the world include high numbers of Latino/a and Mexican descent individuals. The strategies employed by participants suggest subaltern ways of educational leadership not previously considered in research and literature. The authors discuss evidence of characteristics supporting applied critical leadership (ACL), an emerging leadership theory, in the leadership practices of the participants. Finally, mainstream implications and guidelines are provided for application in multiple educational leadership contextsEl propósito y objetivos de esta investigación fueron investigar y comprender mejor las formas en las que la raza y el género generan importantes consecuencias en la práctica del liderazgo aplicado. Se realiza un estudio de caso cualitativo con contra-historia con un enfoque teórico-crítico sobre raza,. Los autores analizan datos sobre dos líderes educativos de ascendencia mexicana en los EE.UU.: uno director de una escuela K-6 latina y el otro, director de una universidad chicana. Los hallazgos evidencian rasgos de identidad positiva de los líderes que permite la puesta en práctica de un liderazgo equitativo y socialmente justo entre los participantes del estudio. Estos hallazgos son novedosos y especialmente relevantes en EEUU y en el resto de países donde viven un alto número de descendientes de latinos y mexicanos. Las estrategias empleadas por los participantes sugieren alternar formas de liderazgo no consideradas ni en la investigación ni en la literatura. Los autores discuten las evidencias encontradas que definen la teoría emergente del liderazgo crítico aplicado (ACL). Por último, se aportan directrices para su aplicación en diferentes contextosA finalidade e objetivos desta pesquisa foram investigar e entender melhor as maneiras em que raça e gênero têm implicações importantes para a prática da liderança aplicada. Foi feito um estudo de caso qualitativo com contra-história é com uma abordagem teórica e crítica à raça e gênero. Os autores analisaram dados de dois líderes educacionais de ascendência mexicana em EUA: um director de um K-6 escola latina e no outro, diretor do faculdade chicana. Os resultados mostram traços de identidade positiva de líderes, que permite a implementação de uma liderança justa e socialmente justa entre os participantes do estudo. Estes resultados são novos e particularmente relevante em os EUA e outros países onde vivem um elevado número de descendentes de latinos e mexicanos. As estratégias empregadas pelos participantes sugerem formas alternativas de liderança não considerado ou pesquisa ou literatura. Os autores discutem as evidências encontradas que definem a teoria emergente de liderança crítica aplicada (ACL). Finalmente, orientações para a aplicação em diferentes contextos são fornecido

Analytic and bootstrap approximations of prediction errors under a multivariate fay-herriot model

A Multivariate Fay-Herriot model is used to aid the prediction of small area parameters of dependent variables with sample data aggregated to area level. The empirical best linear unbiased predictor of the parameter vector is used, and an approximation of the elements of the mean cross product error matrix is obtained by an extension of the results of Prasad and Rao (1990) to the multiparameter case. Three different bootstrap approximations of those elements are introduced, and a simulation study is developed in order to compare the efficiency of all presented approximations, including a comparison under lack of normality. Further, the number of replications needed for the bootstrap procedures to get stabilized are studied

Mesoscopic non-equilibrium thermodynamics approach to non-Debye dielectric relaxation

Mesoscopic non-equilibrium thermodynamics is used to formulate a model describing non-homogeneous and non-Debye dielectric relaxation. The model is presented in terms of a Fokker-Planck equation for the probability distribution of non-interacting polar molecules in contact with a heat bath and in the presence of an external time-dependent electric field. Memory effects are introduced in the Fokker-Planck description through integral relations containing memory kernels, which in turn are used to establish a connection with fractional Fokker-Planck descriptions. The model is developed in terms of the evolution equations for the first two moments of the distribution function. These equations are solved by following a perturbative method from which the expressions for the complex susceptibilities are obtained as a functions of the frequency and the wave number. Different memory kernels are considered and used to compare with experiments of dielectric relaxation in glassy systems. For the case of Cole-Cole relaxation, we infer the distribution of relaxation times and its relation with an effective distribution of dipolar moments that can be attributed to different segmental motions of the polymer chains in a melt.Comment: 33 pages, 6 figure

The transition to irreversibility in sheared suspensions: An analysis based on a mesoscopic entropy production

We study the shear-induced diffusion effect and the transition to irreversibility in suspensions under oscillatory shear flow by performing an analysis of the entropy production associated to the motion of the particles. We show that the Onsager coupling between different contributions to the entropy production is responsible for the scaling of the mean square displacement on particle diameter and applied strain. We also show that the shear-induced effective diffusion coefficient depends on the volume fraction and use Lattice-Boltzmann simulations to characterize the effect through the power spectrum of particle positions for different Reynolds numbers and volume fractions. Our study gives a thermodynamic explanation of the the transition to irreversibility through a pertinent analysis of the second law of thermodynamics.Comment: 17 pages, 3 figures, paper submitted tp phys rev

Potenciando el aprendizaje proactivo con ILIAS&WebQuest: aprendiendo a paralelizar algoritmos con GPUs

Arquitectura de Computadores es una asignatura troncal de segundo ciclo de la titulación de Ingeniería de Telecomunicación (P.E. 2004) de la Universidad de Jaén, que desde el curso académico 2009/10 cuenta con una metodología de aprendizaje proactivo para motivar al alumno en la realización de las prácticas. En concreto, se ha abordado la enseñanza de la materia de paralelización de algoritmos haciendo uso de GPUs de tarjetas gráficas convencionales. Además, se ha dado soporte telemático al profesorado y alumnado de la asignatura mediante el uso de plataformas web de e-learning como ILIAS y otras como WebQuest. Por último, en este trabajo se presentan algunos de los resultados alcanzados con esta experiencia.Peer Reviewe

Intercambios comerciales internos en el Alto Perú colonial tardío.

Sin resume