La integración educativa : la función de preguntar en un sistema integrado de objetivos de la educación.

Conocer las características de la interacción profesor-alumnos, específicamente el comportamiento interrogativo de los estudiantes; y experimentar un método de perfeccionamiento de educadores en servicio destinado a incrementar las consultas discentes. 2.300 alumnos de quinto de EGB de 27 colegios estatales y privados de Móstoles distribuidos en 66 clases con una media de 34 alumnos por clase. Y 66 profesores de 37 años de edad media, con 13 años de experiencia media y mayoritariamente diplomados. Investigación de carácter teórico-experimental que en su primera parte estudia los procesos de interacción y de la acción de preguntar entre discípulos y maestros, sus condicionamientos sociales, psicológicos y pedagógicos. La segunda etapa es un estudio de campo, primero con un periodo exploratorio para conocer y explicar la interacción y las preguntas en quinto de EGB; y por último la intervención propiamente dicha para comprobar si existe relación entre las frecuencias de las preguntas con las características de los alumnos o de los profesores. Se utilizan dos sistemas, el registro de observaciones y las pruebas impresas o cuestionarios. Para comprobar las características de la personalidad de los alumnos se acude a los Test Elemental de Inteligencia de Yela y Test de Cultura Verbal de Cordero. Para medir aspectos de la personalidad del profesor se utilizan el Cuestionario de Personalidad de José Luis Pinillos y la Escala de Autoritarismo de Adorno, Frenkel-Brunswik, Levison, Sanford, Campbell y Stanley. También se mide la interacción verbal en el aula mediante el Sistema de Categorías de Ned A. Flanders, el Sistema de Categorías de Bale y el Sistema ampliado de Amidon y Rosenshine; y se elabora un cuestionario de opiniones para los alumnos. El tratamiento se aplica a la mitad de cada clase, manteniendo la otra mitad como grupo de control. Tras aplicar el tratamiento se observa que aumentó el número de preguntas y el número de alumnos que preguntan; crece una tercera parte la intervención de los niños; y la actuación del profesor se reduce en más de la décima parte. El fomento a la acción interrogativa por parte del profesor, ayuda a dilatarla, pero se comprueba que por cada cuatro actos del profesor que restringen la libertad del alumno, solo uno promueve su autonomía y participación. Las áreas donde se pregunta son Experiencia Social y Naturales, Matemáticas y Lengua. Las causas de este porcentaje reducido de preguntas son la escasa oportunidad que ofrecen los profesores; el desinterés por las materias; y la inhibición. El sexo del profesor no influye pero sí lo hace negativamente su mayor edad o experiencia, y positivamente su mayor estabilidad emocional y control. A mayor inteligencia del alumnos, mayor índice de preguntas, pero no es relevante la aptitud verbal. En los centros privados los alumnos preguntan más aunque sus ideas son memos aceptadas y se les pregunta menos. En resumen, el método empleado ha aumentado la capacidad de los maestros para estimular y suscitar interrogantes en sus discípulos; y sirve para transformar cualitativamente el proceso de enseñanza-aprendizaje al aprovechar el elevado interés de los proferores por mejorar su docencia. La educación es un proceso complejo de interacción humana y por lo tanto profesores y alumnos se influyen recíprocamente.

Genome expansion and gene loss in powdery mildew fungi reveal tradeoffs in extreme parasitism

Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting thatmost effectors represent species-specific adaptations.

Simple method for sub-diffraction resolution imaging of cellular structures on standard confocal microscopes by three-photon absorption of quantum dots

This study describes a simple technique that improves a recently developed 3D sub-diffraction imaging method based on three-photon absorption of commercially available quantum dots. The method combines imaging of biological samples via tri-exciton generation in quantum dots with deconvolution and spectral multiplexing, resulting in a novel approach for multi-color imaging of even thick biological samples at a 1.4 to 1.9-fold better spatial resolution. This approach is realized on a conventional confocal microscope equipped with standard continuous-wave lasers. We demonstrate the potential of multi-color tri-exciton imaging of quantum dots combined with deconvolution on viral vesicles in lentivirally transduced cells as well as intermediate filaments in three-dimensional clusters of mouse-derived neural stem cells (neurospheres) and dense microtubuli arrays in myotubes formed by stacks of differentiated C2C12 myoblasts.

The long wavelength limit of hard thermal loop effective actions

We derive a closed form expression for the long wavelength limit of the effective action for hard thermal loops in an external gravitational field. It is a function of the metric, independent of time derivatives. It is compared and contrasted with the static limit, and with the corresponding limits in an external Yang-Mills field. (C) 2009 Elsevier B.V. All rights reserved.

Instabilities in thermal gravity with a cosmological constant

It is shown that in quantum gravity at finite temperature, the effective potential evaluated in the tadpole approximation can have a local minimum below a certain critical temperature. However, when the leading higher order thermal loop corrections are included, one finds that no static solution exists at high temperature. (C) 2008 Elsevier B.V. All rights reserved.

Finite temperature effective actions

We present, from first principles, a direct method for evaluating the exact fermion propagator in the presence of a general background held at finite temperature, which can be used to determine the finite temperature effective action for the system. As applications, we determine the complete one loop finite temperature effective actions for (0 + 1)-dimensional QED as well as the Schwinger model. These effective actions, which are derived in the real time (closed time path) formalism, generate systematically all the Feynman amplitudes calculated in thermal perturbation theory and also show that the retarded (advanced) amplitudes vanish in these theories. (C) 2009 Elsevier B.V. All rights reserved.

Infrared chiral anomaly at finite temperature

We study the Schwinger model at finite temperature and show that a temperature dependent chiral anomaly may arise from the long distance behavior of the electric field. At high temperature this anomaly depends linearly on the temperature T and is present not only in the two point function, but also in all even point amplitudes. (C) 2011 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.

Effects of confinement on the electron-phonon interaction in Al(0.18)Ga(0.82)As/GaAs quantum wells

Photoluminescence measurements at different temperatures have been performed to investigate the effects of confinement on the electron-phonon interaction in GaAs/AlGaAs quantum wells (QWs). A series of samples with different well widths in the range from 150 up to 750 A was analyzed. Using a fitting procedure based on the Passler-p model to describe the temperature dependence of the exciton recombination energy, we determined a fit parameter which is related to the strength of the electron-phonon interaction. On the basis of the behavior of this fit parameter as a function of the well width thickness of the samples investigated, we verified that effects of confinement on the exciton recombination energy are still present in QWs with well widths as large as 450 angstrom. Our findings also show that the electron-phonon interaction is three times stronger in GaAs bulk material than in Al(0.18)Ga(0.82)As/GaAs QWs.

The new developmentalism as a weberian ideal type

New developmentalism may be seen as a specific set of policies (a national development strategy), or as a broader the theory behind (structuralist development economics) and the corresponding developmental state. Seen in the later sense, as Weberian ideal type, this paper compares new developmentalism with old developmentalism and with liberal orthodoxy. This paper was written in honor of Roberto Frenkel, in 70 years Festrischt.

How to manage macroeconomic policies to foster growth and employment and prevent financial and external crises

My presentation focuses on the implementation of a macroeconomic policy regime which, I believe, is capable of simultaneously attaining several targets, including the promotion of growth and employment and the prevention of external and financial crises.

Propriedades ópticas de nanocristais de SiGe: efeitos de dopagem e desordem

We have used ab initio calculations to investigate the electronic structure of SiGe based nanocrystals (NC s). This work is divided in three parts. In the first one, we focus the excitonic properties of Si(core)/Ge(shell) and Ge(core)/Si(shell) nanocrystals. We also estimate the changes induced by the effect of strain the electronic structure. We show that Ge/Si (Si/Ge) NC s exhibits type II confinement in the conduction (valence) band. The estimated potential barriers for electrons and holes are 0.16 eV (0.34 eV) and 0.64 eV (0.62 eV) for Si/Ge (Ge/Si) NC s. In contradiction to the expected long recombination lifetimes in type II systems, we found that the recombination lifetime of Ge/Si NC s (τR = 13.39μs) is more than one order of magnitude faster than in Si/Ge NC s (τR = 191.84μs). In the second part, we investigate alloyed Si1−xGex NC s in which Ge atoms are randomly positioned. We show that the optical gaps and electron-hole binding energies decrease linearly with x, while the exciton exchange energy increases with x due to the increase of the spatial extent of the electron and hole wave functions. This also increases the electron-hole wave functions overlap, leading to recombination lifetimes that are very sensitive to the Ge content. Finally, we investigate the radiative transitions in Pand B-doped Si nanocrystals. Our NC sizes range between 1.4 and 1.8 nm of diameters. Using a three-levels model, we show that the radiative lifetimes and oscillator strengths of the transitions between the conduction and the impurity bands, as well as the transitions between the impurity and the valence bands are strongly affected by the impurity position. On the other hand, the direct conduction-to-valence band decay is practically unchanged due to the presence of the impurity

Two-colour photocurrent detection technique for coherent control of a single InGaAs/GaAs quantum dot

We present a two-colour photocurrent detection method for coherent control of a single InGaAs/GaAs self-assembled quantum dot. A pulse shaping technique provides a high degree of control over picosecond optical pulses. Rabi rotations on the exciton to biexciton transition are presented, and fine structure beating is detected via time-resolved measurements. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Fast optical preparation, control, and readout of a single quantum dot spin

We propose and demonstrate the sequential initialization, optical control, and readout of a single spin trapped in a semiconductor quantum dot. Hole spin preparation is achieved through ionization of a resonantly excited electron-hole pair. Optical control is observed as a coherent Rabi rotation between the hole and charged-exciton states, which is conditional on the initial hole spin state. The spin-selective creation of the charged exciton provides a photocurrent readout of the hole spin state.