El status actual de las ecoescuelas: el caso de la provincia de Granada (España)

La preocupación progresiva por la sostenibilidad de las organizaciones sociales representa hoy un factor de calidad de la madurez institucional de un país. Las ecoauditorías ambientales son un ejemplo de buenas prácticas ambientales en los centros educativos. En esta comunicación se analiza la aplicación de estas metodologías al campo de la planificación y gestión escolar. La implantación del Programa a 21 ecoescuelas de la Provincia de Granada se evalúa mediante un diseño de investigación cualitativa con estudio de casos, entrevistas y registros fotográficos. Los resultados se interpretan a través de unas tipologías previas de ecoescuelas -señalando debilidades y fortalezas-, analizando el liderazgo de los coordinadores de los programas y marcando estrategias de futuro

Electronic transport and vibrational modes in the smallest molecular bridge: H2 in Pt nanocontacts

We present a state-of-the-art first-principles analysis of electronic transport in a Pt nanocontact in the presence of H2 which has been recently reported by Smit et al. in Nature 419, 906 (2002). Our results indicate that at the last stages of the breaking of the Pt nanocontact two basic forms of bridge involving H can appear. Our claim is, in contrast to Smit et al.'s, that the main conductance histogram peak at G approx 2e^2/h is not due to molecular H2, but to a complex Pt2H2 where the H2 molecule dissociates. A first-principles vibrational analysis that compares favorably with the experimental one also supports our claim .Comment: 5 pages, 3 figure

Coexistence of jaguars (Panthera onca) and pumas (Puma concolor) in a tropical forest in south–eastern Mexico

The biological ranges of the jaguar (Panthera onca) and puma (Puma concolor) overlap in the Yucatan Peninsula, corresponding to the most important population of jaguars in Mexico. The goal of this study in the El Eden Ecological Reserve (EER) was to investigate the factors that permit these two predators to coexist in the dense vegetation of medium–stature tropical forest and secondary forest in the north–eastern Yucatan Peninsula. We assessed their spatial and temporal overlap using Pianka’s index, and evaluated their habitat use by applying occupancy models. A total sampling effort of 7,159 trap–nights over 4 years produced 142 independent photographic records of jaguars, and 134 of pumas. The felids showed high to very high overlap in their use of different vegetation (0.68–0.99) and trail types (0.63–0.97) and in their activity patterns (0.81–0.90). However, their peak activity patterns showed some temporal separation. Time of day, particularly for peak activity time, was the best predictor to explain the coexistence of the felids in this habitat. While occupancy models showed that the presence of potential prey species and vegetation type could predict the presence of felids in the study area. Natural disturbances during 2010 (hurricane) and 2011 (fire) drastically changed habitat use and activity patterns, resulting in pumas and jaguars adjusting their resource–use and activity pattern through a strategy of mutual evasion

First-principles phase-coherent transport in metallic nanotubes with realistic contacts

We present first-principles calculations of phase coherent electron transport in a carbon nanotube (CNT) with realistic contacts. We focus on the zero-bias response of open metallic CNT's considering two archetypal contact geometries (end and side) and three commonly used metals as electrodes (Al, Au, and Ti). Our ab-initio electrical transport calculations make, for the first time, quantitative predictions on the contact transparency and the transport properties of finite metallic CNT's. Al and Au turn out to make poor contacts while Ti is the best option of the three. Additional information on the CNT band mixing at the contacts is also obtained.Comment: 5 pages (two-column format

Ballistic resistivity in aluminum nanocontacts

One of the major industrial challenges is to profit from some fascinating physical features present at the nanoscale. The production of dissipationless nanoswitches (or nanocontacts) is one of such attractive applications. Nevertheless, the lack of knowledge of the real efficiency of electronic ballistic/non dissipative transport limits future innovations. For multi-valent metallic nanosystems -where several transport channels per atom are involved- the only experimental technique available for statistical transport characterization is the conductance histogram. Unfortunately its interpretation is difficult because transport and mechanical properties are intrinsically interlaced. We perform a representative series of semiclassical molecular dynamics simulations of aluminum nanocontact breakages, coupled to full quantum conductance calculations, and put in evidence a linear relationship between the conductance and the contact minimum cross-section for the geometrically favored aluminum nanocontact configurations. Valid in a broad range of conductance values, such relation allows the definition of a transport parameter for nanomaterials, that represents the novel concept of ballistic resistivity

In vivo chromatin targets of the transcription factor Yin Yang 2 in trophoblast stem cells

Background: Yin Yang 2 (YY2) is a zinc finger protein closely related to the well-characterized Yin Yang 1 (YY1). YY1 is a DNA-binding transcription factor, with defined functions in multiple developmental processes, such as implantation, cell differentiation, X inactivation, imprinting and organogenesis. Yy2 has been treated as a largely immaterial duplication of Yy1, as they share high homology in the Zinc Finger-region and similar if not identical in vitro binding sites. In contrast to these similarities, gene expression alterations in HeLa cells with attenuated levels of either Yy1 or Yy2 were to some extent gene-specific. Moreover, the chromatin binding sites for YY2, except for its association with transposable retroviral elements (RE) and Endogenous Retroviral Elements (ERVs), remain to be identified. As a first step towards defining potential Yy2 functions matching or complementary to Yy1, we considered in vivo DNA binding sites of YY2 in trophoblast stem (TS) cells. Results: We report the presence of YY2 protein in mouse-derived embryonic stem (ES) and TS cell lines. Following up on our previous report on ERV binding by YY2 in TS cells, we investigated the tissue-specificity of REX1 and YY2 binding and confirm binding to RE/ERV targets in both ES cells and TS cells. Because of the higher levels of expression, we chose TS cells to understand the role of Yy2 in gene and chromatin regulation. We used in vivo YY2 association as a measure to identify potential target genes. Sequencing of chromatin obtained in chromatin-immunoprecipitation (ChIP) assays carried out with aYY2 serum allowed us to identify a limited number of chromatin targets for YY2. Some putative binding sites were validated in regular ChIP assays and gene expression of genes nearby was altered in the absence of Yy2. Conclusions: YY2 binding to ERVs is not confined to TS cells. In vivo binding sites share the presence of a consensus binding motif. Selected sites were uniquely bound by YY2 as opposed to YY1, suggesting that YY2 exerts unique contributions to gene regulation. YY2 binding was not generally associated with gene promoters. However, several YY2 binding sites are linked to long noncoding RNA (lncRNA) genes and we show that the expression levels of a few of those are Yy2-dependent

Estadio Olímpico de la Ciudad Universitaria

The existing stadium was reconstructed in a precise manner to meet the Olympic requirements, and serve as site of the opening and closing ceremonies of the 19th Olympic Games. It is 3.8 km from the Olympic Village and 15.6 km from the Plaza Mayor. The main adaptations carried out on the existing stadium were the following: the provision of ample press facilities; extension of the higher stands; new structures for the giant scoreboard and for the illumination; improvement of the seats; reconstruction of the athletics track and field, which was covered with a layer of plastic material. The planform of the stadium is an ovoid, inscribed in a circumference of 125 m radius. The axis of the stadiimi makes a slight angle with the longitudinal axis of the athletics field. The stadium can hold 80.000 spectators.<br><br>El Estadio —ya existente— fue sometido a las obras y adaptaciones precisas para que cumpliese los requisitos olímpicos, y sirviese como sede de las ceremonias de apertura y clausura de los XIX Juegos Olímpicos. Se encuentra situado a 3,8 km de la Villa Olímpica y a 15,6 km de la Plaza Mayor. Las principales adaptaciones fueron las siguientes: dotarle de áreas para los servicios de prensa; ampliación de las gradas altas; ejecución de nuevas estructuras para el tablero marcador e iluminación; reforma de los asientos; y reconstrucción del campo y de la pista de atletismo, que se recubrió con una capa de material plástico. Su planta tiene la forma de ovoide, inscrita en una circunferencia de 125 m de radio, con el eje longitudinal desfasado 8 m hacia el oeste con respecto al del campo. El aforo total es de 80.000 localidades

¿Qué herramientas proporcionan las Tecnologías de la Información y la Comunicación a la educación ambiental?

Tras una revisión exhaustiva de la literatura publicada que relaciona los campos de las Tecnologías de la Información y Comunicación (TIC) y la Educación Ambiental para la Sostenibilidad, en este trabajo planteamos un estudio y clasificación de los medios TIC que están a disposición de los educadores ambientales o profesionales de la educación para su tarea docente, en la que se nos muestran las múltiples posibilidades que se nos abren en este campo, todavía escasamente explorado.Palabras clave: TIC; Educación Ambiental; Educación para la Sostenibilidad.Which tools does information comunication technology provide to enviromental education?After an exhaustive revision of the literature published relating to the topics of Information and Communication Technologies (ICT) and Environmental Education for Sustainability, in this work we set out a study and classification of ICT media available for environmental educators or teachers for their educational tasks. After that we show the multiple possibilities that those offer us in this field, still scarcely explored.Keywords: ICT; Environmental Education; Environmental Education for Sustainability

Uso que hacen de las tic los educadores ambientales : estudio diagnóstico y prospectiva

En esta aportación nos centramos en el diagnóstico del uso que hacen los educadores ambientales de las Tecnologías de la Información y la Comunicación (TIC). Inicialmente realizamos una revisión de la bibliografía, hallando muy escasas contribuciones relacionadas con el propósito de nuestra investigación. Posteriormente se diseñó y validó un cuestionario “on line” con 35 items de respuesta cerrada y abierta que fue difundido a través de la red, obteniéndose 232 respuestas de diferentes países iberoamericanos. El análisis de las respuestas conllevó procedimientos cualitativos y cuantitativos. Los resultados de dicho análisis vienen a mostrar el escaso uso de los educadores ambientales de las TIC así como su general desconocimiento de las múltiples posibilidades didácticas de las mismas, aunque reconocen sus potencialidades en el ámbito de la Educación Ambiental

Optimal light harvesting structures at optical and infrared frequencies

One-dimensional light harvesting structures with a realistic geometry nano-patterned on an opaque metallic film are optimized to render high transmission efficiencies at optical and infrared frequencies. Simple design rules are developed for the particular case of a slit-groove array with a given number of grooves that are symmetrically distributed with respect to a central slit. These rules take advantage of the hybridization of Fabry-Perot modes in the slit and surface modes of the corrugated metal surface. Same design rules apply for optical and infrared frequencies. The parameter space of the groove array is also examined with a conjugate gradient optimization algorithm that used as a seed the geometries optimized following physical intuition. Both uniform and nonuniform groove arrays are considered. The largest transmission enhancement, with respect to a uniform array, is obtained for a chirped groove profile. Such enhancement is a function of the wavelength. It decreases from 39% in the optical part of the spectrum to 15% at the long wavelength infrared.Comment: 13 pages, 5 figure