Energy and Economic Life Cycle Assessment of Cool Roofs Applied to the Refurbishment of Social Housing in Southern Spain

Energy refurbishment of the housing stock is needed in order to reduce energy consumption and meet global climate goals. This is even more necessary for social housing built in Spain in the middle of the last century since its obsolete energy conditions lead to situations of indoor thermal discomfort and energy poverty. The present study carries out a life cycle assessment of the energy and economic performance of roofs after being retrofitted to become cool roofs for the promotion of social housing in Seville (Spain). Dynamic simulations are made in which the time dependent aging effect on the energy performance of the refurbished cool roofs is included for the whole lifespan. The influence of the time dependent aging effect on the results of the life cycle economic analysis is also assessed. A variety of scenarios are considered in order to account for the aging effect in the energy performance of the retrofitted cool roofs and its incidence while considering different energy prices and monetary discount rates on the life cycle assessment. This is made through a dynamic life cycle assessment in order to capture the impact of the aging dynamic behavior correctly. Results point out significant savings in the operational energy. However, important differences are found in the economic savings when the life cycle analysis is carried out since the source of energy and the efficiency of the equipment used for conditioning strongly impact the economic results

FIBONACCI SUPERLATTICES OF NARROW-GAP III-V SEMICONDUCTORS

We report theoretical electronic structure of Fibonacci superlattices of narrow-gap III-V semiconductors. Electron dynamics is accurately described within the envelope-function approximation in a two-band model. Quasiperiodicity is introduced by considering two different III-V semiconductor layers and arranging them according to the Fibonacci series along the growth direction. The resulting energy spectrum is then found by solving exactly the corresponding effective-mass (Dirac-like) wave equation using tranfer-matrix techniques. We find that a self-similar electronic spectrum can be seen in the band structure. Electronic transport properties of samples are also studied and related to the degree of spatial localization of electronic envelope-functions via Landauer resistance and Lyapunov coefficient. As a working example, we consider type II InAs/GaSb superlattices and discuss in detail our results in this system.Comment: REVTeX 3.0, 16 pages, 8 figures available upon request. To appear in Semiconductor Science and Technolog

Detection of mecC-Methicillin-resistant Staphylococcus aureus isolates in river water : a potential role for water in the environmental dissemination

Methicillin-resistant Staphylococcus aureus (MRSA) is a public health concern due to limited treatment options. The recent description of a mecA homologue, mecC in human and cattle, led to studies to detect this new variant in human and other animal species. Detection of mecC in wild boar and fallow deer in a Spanish game estate led us to further investigate the presence of mecC-MRSA at this location. Samples from cattle, wild animals, workers and river water were tested. A further three mecC-MRSA isolates were obtained from river water. Molecular characterization (multilocus sequence typing and spa typing) and antimicrobial susceptibility testing (broth microdilution) showed that isolates were similar to those detected in wild animals. Whole genome sequencing confirmed that the isolates from the river water and wild animals in the same geographic area were all closely related isolates of ST425 mecC-MRSA. The presence of mecC-MRSA in the river water highlights the potential role of water in the dissemination of mecC-MRSA

Equilibrium properties of a Josephson junction ladder with screening effects

In this paper we calculate the ground state phase diagram of a Josephson Junction ladder when screening field effects are taken into account. We study the ground state configuration as a function of the external field, the penetration depth and the anisotropy of the ladder, using different approximations to the calculation of the induced fields. A series of tongues, characterized by the vortex density $\omega$, is obtained. The vortex density of the ground state, as a function of the external field, is a Devil's staircase, with a plateau for every rational value of $\omega$. The width of each of these steps depends strongly on the approximation made when calculating the inductance effect: if the self-inductance matrix is considered, the $\omega=0$ phase tends to occupy all the diagram as the penetration depth decreases. If, instead, the whole inductance matrix is considered, the width of any step tends to a non-zero value in the limit of very low penetration depth. We have also analyzed the stability of some simple metastable phases: screening fields are shown to enlarge their stability range.Comment: 16 pp, RevTex. Figures available upon request at [email protected] To be published in Physical Review B (01-Dec-96

Metallic diluted dimerization in VO2 tweeds

Altres ajuts: ICN2 was also supported by the CERCA programme (Generalitat de Catalunya).The observation of electronic phase separation textures in vanadium dioxide, a prototypical electron-correlated oxide, has recently added new perspectives on the long standing debate about its metal-insulator transition and its applications. Yet, the lack of atomically resolved information on phases accompanying such complex patterns still hinders a comprehensive understanding of the transition and its implementation in practical devices. In this work, atomic resolution imaging and spectroscopy unveils the existence of ferroelastic tweed structures on ≈5 nm length scales, well below the resolution limit of currently used spectroscopic imaging techniques. Moreover, density functional theory calculations show that this pretransitional fine-scale tweed, which on average looks and behaves like the standard metallic rutile phase, is in fact weaved by semi-dimerized chains of vanadium in a new monoclinic phase that represents a structural bridge to the monoclinic insulating ground state. These observations provide a multiscale perspective for the interpretation of existing data, whereby phase coexistence and structural intermixing can occur all the way down to the atomic scale

Pintura y lectura: La herencia centenaria del proyecto cultural de Vasconcelos

ArtículoLa investigación muestra los inicios de la alfabetización en un contexto posrevolucionario, donde era notorio que en el terreno de la cultura, la educación y la lectura había desigualdades e injusticias para una sociedad con población mayoritariamente analfabeta y con poca cultura plástica visual. Se presenta también un breve panorama de la gestión de José Vasconcelos al frente de la recién creada Secretaría de Educación Pública (SEP) y su ambiciosa campaña cultural. A partir de esto se realiza un análisis de las similitudes y diferencias entre los lenguajes escrito y pictórico que promovió Vasconcelos hace un siglo y que, a pesar de los avatares, siguen vigentes y, además de mantener su función educativa primigenia, cumplen con otros usos. De esta manera se contribuye con apuntes para la configuración de la historia conjunta de la pintura y la lectura en México y su establecimiento como discurso histórico-identitario-nacionalista textual y visual. Así, estos apuntes suman elementos para los estudios históricos sobre la pintura y la lectura que hacen visibles los sucesos, las rupturas o las continuidades de un proyecto cultural nacional próximo a cumplir sus primeros cien años.Propio

Full capacitance-matrix effects in driven Josephson-junction arrays

We study the dynamic response to external currents of periodic arrays of Josephson junctions, in a resistively capacitively shunted junction (RCSJ) model, including full capacitance-matrix effects}. We define and study three different models of the capacitance matrix $C_{\vec{r},\vec{r}'}$: Model A includes only mutual capacitances; Model B includes mutual and self capacitances, leading to exponential screening of the electrostatic fields; Model C includes a dense matrix $C_{\vec{r},\vec{r}'}$ that is constructed approximately from superposition of an exact analytic solution for the capacitance between two disks of finite radius and thickness. In the latter case the electrostatic fields decay algebraically. For comparison, we have also evaluated the full capacitance matrix using the MIT fastcap algorithm, good for small lattices, as well as a corresponding continuum effective-medium analytic evaluation of a finite voltage disk inside a zero-potential plane. In all cases the effective $C_{\vec{r},\vec{r}'}$ decays algebraically with distance, with different powers. We have then calculated current voltage characteristics for DC+AC currents for all models. We find that there are novel giant capacitive fractional steps in the I-V's for Models B and C, strongly dependent on the amount of screening involved. We find that these fractional steps are quantized in units inversely proportional to the lattice sizes and depend on the properties of $C_{\vec{r},\vec{r}'}$. We also show that the capacitive steps are not related to vortex oscillations but to localized screened phase-locking of a few rows in the lattice. The possible experimental relevance of these results is also discussed.Comment: 12 pages 18 Postscript figures, REVTEX style. Paper to appear in July 1, Vol. 58, Phys. Rev. B 1998 All PS figures include

Morphological behavior of Maize inoculated with Azotobacter chroococcum at reduced dosage of nitrogen fertilizer

The inoculation with bacteria that promote plant growth of the genus Azotobacter, is an alternative for the reduction and optimization of nitrogen fertilizers. The objective of this work was to evaluate the response of maize to the inoculation with Azotobacter chroococcum using different doses and applying 50% of the nitrogen fertilizer, as well as a combination of A chroococcum and vermicompost. The work was carried out under an experimental design in random blocks with four treatments and four replicas. The response of the crop to the treatments was evaluated in morphological characters expressed in percentage of germination of the seed, height of the plant, fresh air weight, radical fresh weight, air dry weight and radical dry weight. The results proved the positive response of the maize crop to the inoculation with A. chroococcum and of A. chroococcum with vermicompost in all the variables studied. The best result was obtained with the combined application of A. chroococcum + vermicompost at doses of 15 l ha and 2 t hare spectively, expressed in a percentage of germination of the seed of 98.4%, a height of 1.14 m plant; an air fresh weight of 40.7 g; a radical fresh weight of 20.4 g; an aerial dry weight of 10.1 g and a radical dry weight of 5.1 g

Comportamiento morfológico del Maíz inoculado con Azotobacter chroococcum a dosis reducida de fertilizante nitrogenado

The inoculation with bacteria that promote plant growth of the genus Azotobacter, is an alternative for the reduction and optimization of nitrogen fertilizers. The objective of this work was to evaluate the response of maize to the inoculation with Azotobacter chroococcum using different doses and applying 50% of the nitrogen fertilizer, as well as a combination of A. chroococcum and vermicompost. The work was carried out under an experimental design in random blocks with four treatments and four replicas. The response of the crop to the treatments was evaluated in morphological characters expressed in percentage of germination of the seed, height of the plant, fresh air weight, radical fresh weight, air dry weight and radical dry weight. The results proved the positive response of the maize crop to the inoculation with A. chroococcum and of A. chroococcum with vermicompost in all the variables studied. The best result was obtained with the combined application of A. chroococcum + vermicompost at doses of 15 l ha and 2 t hare spectively, expressed in a percentage of germination of the seed of 98.4%, a height of 1.14 m plant; an air fresh weight of 40.7 g; a radical fresh weight of 20.4 g; an aerial dry weight of 10.1 g and a radical dry weight of 5.1 g.La inoculación con bacterias promotoras del crecimiento vegetal del género Azotobacter, es una alternativa para la reducción y optimización de los fertilizantes nitrogenados. El objetivo de este trabajo fue evaluar la respuesta del maíz (Zea mays) a la inoculación con Azotobacter chroococcum empleando diferentes dosis y aplicando el 50 % del fertilizante nitrogenado, así como una combinación de A. chroococcum y vermicompost. El trabajo se realizó bajo un diseño experimental en bloques al azar con cuatro tratamientos y cuatro replicas. La respuesta del cultivo a los tratamientos se evaluó en caracteres morfológicos expresados en por ciento de germinación de la semilla, altura de la planta, peso fresco aéreo, peso fresco radical, peso seco aéreo y peso seco radical. Los resultados probaron la respuesta positiva del cultivo del maíz a la inoculación con A. chroococcum y de A. chroococcum con vermicompost en todas las variables estudiadas. El mejor resultado se obtuvo con la aplicación combinada de A. chroococcum y vermicompost a dosis de 15 lha-1 y 2 t ha-1 respectivamente, expresados en un por ciento de germinación de la semilla de 98,4 %, una altura de la planta de 1,14 m; un peso fresco aéreo de 40,7 g; un peso fresco radical de 20,4 g; un peso seco aéreo de 10,1 g y un peso seco radical de 5,1 g