La travesía obsoleta: la indefensión del consumidor

La obsolescencia programada es el deseo de tener algo un poco más nuevo, un poco mejor, un poco más rápido de lo necesario. El texto estudia este fenómeno a la luz del Estatuto del Consumidor – Ley 1480 de 2011 para determinar si el consumidor colombiano está suficientemente protegido con él.

El contrato estatal de estabilidad jurídica

En este trabajo de investigación se identifican los principales problemas jurídicos derivados de la suscripción de los Contratos de Estabilidad Jurídica y sus consecuencias en el plano nacional y en el internacional.

Cooperar para competir : sinsentidos varios en excelencia universitaria.

Resumen basado en el de la publicación

La violencia hacia las mujeres y hacia otras personas percibidas como distintas a la norma dominante : el caso de los centros educativos.

Resumen basado en el de la publicación. Monográfico con el título 'Violencia de género y relaciones de poder: implicaciones para la educación'

La planificación de la enseñanza en Francia.

Se analiza la planificación de la enseñanza en Francia. La planificación educativa es un instrumento cada vez más necesario. Ello se debe a que el progreso que se realiza en los diversos sectores económicos está subordinado al desarrollo de los niveles de enseñanza. La planificación educativa permite establecer un equilibrio entre actividad educativa y las actividades económicas, ya que mediante la planificación el sistema educativo es capaz de dar a la industria el potencial humano necesario. De hecho se mantiene que la educación exige estudios de previsión mucho más precisos que en cualquier sector industrial. A continuación se estudia en primer lugar la enseñanza primaria en relación con la planificación, de la que se analiza la evolución de las matrículas, las necesidades de equipo, o previsiones que el Ministerio de Educación Nacional deberá realizar para dar respuesta satisfactoria a los movimientos migratorios de la población. Socialmente las migraciones tienen dos direcciones: de los pueblos hacia las ciudades y del centro de las grandes ciudades a la periferia. También se hace referencia a la enseñanza Terminal, que se destina, según la reforma de 1959, a aquellos alumnos que no pueden seguir con provecho una enseñanza general o profesional larga. Por lo que respecta a la enseñanza de segundo grado, los dos elementos imprescindibles que hay que tener en cuenta para su planificación son: la necesidad de un reparto equitativo de los créditos entre las regiones, y la orientación de los alumnos hacia los diversos ciclos de estudios. Se hace referencia a las modalidades de la encuesta regional, que deberá realizarse en el plano nacional con los mismos principios y directrices idénticas y la evolución de los efectivos. Por último se analiza la enseñanza superior y se sistematizan una serie de conclusiones.

Tratándose de expresiones idiomáticas, ­no te rompas la cabeza ni busques cinco pies al gato!

Resumen tomado de la publicación

Modelo y consecuencia de implantación de las TIC en la comunidad educativa de Extremadura.

Monográfico con el título: 'Aplicabilidad de las TIC a la educación escolar'. Resumen basado en el de la publicación

La documentación pedagógica.

Se trata del estudio de Frank Hilker donde trata la historia y la organización del momento de la documentación pedagógica en España. En el estudio hace un repaso a la historia y el concepto de 'documentación'. Explica los orígenes de la documentación pedagógica. Ahonda sobre lo que supuso la creación de la Conferencia de la Unesco sobre educación para fomentar el trabajo pedagógico y encaminarlo por directrices unitarias. Analiza la organización y los fines de los centros de documentación, precisando las características de los archivos, las bibliotecas y la exposición de material docente. Describe los cometidos pedagógicos en el plano nacional y supranacional de la Documentación Pedagógica: la observación de la vida cultural, el inventario, las publicaciones y las relaciones internacionales.

Reunión de directores y redactores de prensa pedagógica.

Se examina lo acontecido en la primera reunión de directores y redactores de prensa pedagógica que tuvo lugar en julio de 1958. Esta reunión tenía propósitos exploratorios, pues era el primer intento llevado a cabo en este sentido. Se trataba de tantear el camino para posibles Conferencias futuras de más amplio radio. Las tareas realizadas comprendieron dos partes. En primer lugar, cada representante expuso la organización, estructura y necesidades de su revista en relación con el fin de cooperación internacional y con su concepción de las exigencias educativas, de acuerdo con la etapa de desarrollo científico en que se encontraba la problemática educativa en su país. Concluida esta fase se pasó a formular propuestas en orden a las medidas que sería conveniente adoptar para fomentar la colaboración de las diferentes revistas pedagógicas entre sí, en el plano nacional e internacional.

Ethylene and polyamine interactions in morphogenesis of Passiflora cincinnata: effects of ethylene biosynthesis and action modulators, as well as ethylene scavengers

Ethylene is a plant hormone that is of fundamental importance to in vitro morphogenesis, but in many species, it has not been thoroughly studied. Its relationship with polyamines has been studied mainly because the two classes of hormones share a common biosynthetic precursor, S-adenosylmethionine (SAM). In order to clarify whether competition between polyamines and ethylene influences in vitro morphogenetic responses of Passiflora cincinnata Mast., a climacteric species, different compounds were used that act on ethylene biosynthesis and action, or as ethylene scavengers. Treatment with the ethylene inhibitor, aminoethoxyvinylglycine (AVG) caused a greater regeneration frequency in P. cincinnata, whereas treatment with the ethylene precursor, 1-aminocyclopropane-1-carboxylic-acid (ACC) lessened regeneration frequencies. The data suggested that levels of polyamines and ethylene are not correlated with morphogenic responses in P. cincinnata. It was ascertained that neither the absolute ethylene and polyamine levels, nor competition between the compounds, correlated to the obtained morphogenic responses. However, sensitivity to, and signaling by, ethylene appears to play an important role in differentiation. This study reinforces previous reports regarding the requirement of critical concentrations and temporal regulation of ethylene levels for morphogenic responses. Temporal regulation also appeared to be a key factor in competition between the two biosynthetic pathways, without having any effects on morphogenesis. Further studies investigating the silencing or overexpression of genes related to ethylene perception, under the influence of polyamines in cell differentiation are extremely important for the complete understanding of this process.

Neuromuscular electrical stimulation improves GLUT-4 and morphological characteristics of skeletal muscle in rats with heart failure

Aim: Changes in skeletal muscle morphology and metabolism are associated with limited functional capacity in heart failure, which can be attenuated by neuromuscular electrical stimulation (ES). The purpose of the present study was to analyse the effects of ES upon GLUT-4 protein content, fibre structure and vessel density of the skeletal muscle in a rat model of HF subsequent to myocardial infarction. Methods: Forty-four male Wistar rats were assigned to one of four groups: sham (S), sham submitted to ES (S+ES), heart failure (HF) and heart failure submitted to ES (HF+ES). The rats in the ES groups were submitted to ES of the left leg during 20 days (2.5 kHz, once a day, 30 min, duty cycle 50%- 15 s contraction/15 s rest). After this period, the left tibialis anterior muscle was collected from all the rats for analysis. Results: HF+ES rats showed lower values of lung congestion when compared with HF rats (P = 0.0001). Although muscle weight was lower in HF rats than in the S group, thus indicating hypotrophy, 20 days of ES led to their recovery (P < 0.0001). In both groups submitted to ES, there was an increase in muscle vessel density (P < 0.04). Additionally, heart failure determined a 49% reduction in GLUT-4 protein content (P < 0.03), which was recovered by ES (P < 0.01). Conclusion: In heart failure, ES improves morphological changes and raises GLUT-4 content in skeletal muscle.

Antimicrobial activity in the tick Rhipicephalus (Boophilus) microplus eggs: Cellular localization and temporal expression of microplusin during oogenesis and embryogenesis

Arthropods display different mechanisms to protect themselves against infections, among which antimicrobial peptides (AMPs) play an important role, acting directly against invader pathogens. We have detected several factors with inhibitory activity against Candida albicans and Micrococcus luteus on the surface and in homogenate of eggs of the tick Rhipicephalus (Boophilus) microplus. One of the anti-M. luteus factors of the egg homogenate was isolated to homogeneity. Analysis by electrospray mass spectrometry (ESI-MS) revealed that it corresponds to microplusin, an AMP previously isolated from the cell-free hemolymph of X (B.) microplus. Reverse transcription (RT) quantitative polymerase chain reactions (qPCR) showed that the levels of microplusin mRNA gradually increase along ovary development, reaching an impressive highest value three days after the adult females have dropped from the calf and start oviposition. Interestingly, the level of microplusin mRNA is very low in recently laid eggs. An enhance of microplusin gene expression in eggs is observed only nine days after the onset of oviposition, achieving the highest level just before the larva hatching, when the level of expression decreases once again. Fluorescence microscopy analysis using an anti-microplusin serum revealed that microplusin is present among yolk granules of oocytes as well as in the connecting tube of ovaries. These results, together to our previous data. suggest that microplusin may be involved not only in protection of adult female hemocele, but also in protection of the female reproductive tract and embryos, what points this AMP as a considerable target for development of new methods to control R. (B.) microplus as well as the vector-borne pathogens. (c) 2009 Elsevier Ltd. All rights reserved.

On the unification of long-term survival models

In this paper we extend the long-term survival model proposed by Chen et al. [Chen, M.-H., Ibrahim, J.G., Sinha, D., 1999. A new Bayesian model for survival data with a surviving fraction. journal of the American Statistical Association 94, 909-919] via the generating function of a real sequence introduced by Feller [Feller, W., 1968. An Introduction to Probability Theory and its Applications, third ed., vol. 1, Wiley, New York]. A direct consequence of this new formulation is the unification of the long-term survival models proposed by Berkson and Gage [Berkson, J., Gage, R.P., 1952. Survival cure for cancer patients following treatment. journal of the American Statistical Association 47, 501-515] and Chen et al. (see citation above). Also, we show that the long-term survival function formulated in this paper satisfies the proportional hazards property if, and only if, the number of competing causes related to the occurrence of an event of interest follows a Poisson distribution. Furthermore, a more flexible model than the one proposed by Yin and Ibrahim [Yin, G., Ibrahim, J.G., 2005. Cure rate models: A unified approach. The Canadian journal of Statistics 33, 559-570] is introduced and, motivated by Feller`s results, a very useful competing index is defined. (c) 2008 Elsevier B.V. All rights reserved.

A discontinuous-Galerkin-based immersed boundary method with non-homogeneous boundary conditions and its application to elasticity

We propose a discontinuous-Galerkin-based immersed boundary method for elasticity problems. The resulting numerical scheme does not require boundary fitting meshes and avoids boundary locking by switching the elements intersected by the boundary to a discontinuous Galerkin approximation. Special emphasis is placed on the construction of a method that retains an optimal convergence rate in the presence of non-homogeneous essential and natural boundary conditions. The role of each one of the approximations introduced is illustrated by analyzing an analog problem in one spatial dimension. Finally, extensive two- and three-dimensional numerical experiments on linear and nonlinear elasticity problems verify that the proposed method leads to optimal convergence rates under combinations of essential and natural boundary conditions. (C) 2009 Elsevier B.V. All rights reserved.

Substitutional Impurities in PPV Crystals: An Intrinsic Donor-Acceptor System for High V(oc) Photovoltaic Devices

Defects are usually present in organic polymer films and are commonly invoked to explain the low efficiency obtained in organic-based optoelectronic devices. We propose that controlled insertion of substitutional impurities may, on the contrary, tune the optoelectronic properties of the underivatized organic material and, in the case studied here, maximize the efficiency of a solar cell. We investigate a specific oxygen-impurity substitution, the keto-defect -(CH(2)-C=O)- in underivatized crystalline poly(p-phenylenevinylene) (PPV), and its impact on the electronic structure of the bulk film, through a combined classical (force-field) and quantum mechanical (DFT) approach. We find defect states which suggest a spontaneous electron hole separation typical of a donor acceptor interface, optimal for photovoltaic devices. Furthermore, the inclusion of oxygen impurities does not introduce defect states in the gap and thus, contrary to standard donor-acceptor systems, should preserve the intrinsic high open circuit voltage (V(oc)) that may be extracted from PPV-based devices.