Exact renormalization in quantum spin chains

We introduce a real-space exact renormalization group method to find exactly solvable quantum spin chains and their ground states. This method allows us to provide a complete list for exact solutions within SU(2) symmetric quantum spin chains with $S\leq 4$ and nearest-neighbor interactions, as well as examples with S=5. We obtain two classes of solutions: One of them converges to the fixed points of renormalization group and the ground states are matrix product states. Another one does not have renormalization fixed points and the ground states are partially ferromagnetic states.Comment: 8 pages, 5 figures, references added, published versio

Aromatase: A neuroprotective enzyme

Estradiol, in addition to its participation in neuroendocrine regulation and sexual behavior, has neuroprotective properties. Different types of brain injury induce the expression of the enzyme aromatase in reactive astroglia. This enzyme catalyzes the conversion of testosterone and other C19 steroids to estradiol. Genetic or pharmacological inhibition of brain aromatase results in marked neurodegeneration after different forms of mild neurodegenerative stimuli that do not compromise neuronal survival under control conditions. Furthermore, aromatase mediates neuroprotective effects of precursors of estradiol such as pregnenolone, dehydroepiandrosterone (DHEA) and testosterone. These findings strongly suggest that local formation of estradiol in the brain is neuroprotective and that the induction of aromatase and the consecutive increase in the local production of estradiol are part of the program triggered by the neural tissue to cope with neurodegenerative insults. Aromatase may thus represent an important pharmacological target for therapies conducted to prevent aging-associated neurodegenerative disorders. © 2003 Elsevier Ltd. All rights reserved.Peer Reviewe

Effect of conductivity and frequency on detection of heterogeneities in solid/liquid interfaces using local electrochemical impedance Theoretical and experimental study

This short communication demonstrates, by solving the Laplace equation with proper boundary conditions (BC) using finite element method (FEM), that it is not possible to establish a correlation between what happens in the electrolyte near an active boundary and what really occurs at the actual boundary if adequate ranges of electrolyte conductivity and input AC signal frequency are not selected, especially when inhomogeneities approximated by Neumann BC are present. Experimental evidence obtained by local electrochemical impedance mapping (LEIM) supports the theoretical results.This work has been supported by the Ministry of Science and Inno-vationofSpain(MAT2006-04486andIPT-020000-2010-0001Projects

Morphostructural characterisation of Spanish Alano as a base for its conservation: preliminar results

Using 68 pure exemplars of the Spanish Alano Dog Breed (37 males and 31 females) we have developed a preliminary study of the breed characterisation analysing several morphostructural variables as a base for the definition of racial pattern, considering that a one of the main objectives of the project entitled Planning of the recuperation and conservation of the Spanish Alano canine breed. All the studied zoometric variables reflected bigger values if males than in females, but we could not proved statistically a clear sexual dimorphism in most of the studied variables. Our results coincide with descriptions and data published by other authors with respect to this breed. In general, from this study we conclude that this population is characterised by braquicephalic proportions, and sublongilineous body proportions, all inside a strong and compact morphostructure. It permit us to clasify this breed inside the group of light molosoids caught dogs.Sobre un total de 68 ejemplares de la raza Alano Español (37 machos y 31 hembras) se realiza un estudio de caracterización racial preliminar, analizando diversas variables morfoestructurales, como base para su utilización en la redacción del patrón racial, considerado como uno de los objetivos iniciales prioritarios en el proyecto denominado Planificación de la recuperación y conservación de la raza canina Alano Español. Todas las variables zoométricas estudiadas reflejaron valores mayores en machos que en hembras, aunque no comprobamos estadísticamente un dimorfismo sexual manifiesto en la mayoría de dichas variables. Asimismo nuestros resultados concuerdan con las descripciones y datos aportados por los distintos autores que estudiaron esta raza anteriormente. En líneas generales, de este estudio se puede concluir que la población estudiada se caracteriza por presentar características braquicéfalas, y proporciones corporales sublongilíneas dentro de una morfoestructura general fuerte y compacta, lo que nos permite encuadrar esta raza dentro del grupo de perros molosos ligeros de presa

Potential impacts of climate variability on Dengue Hemorrhagic Fever in Honduras, 2010

Climate change and variability are affecting human health and disease direct or indirectly through many mechanisms. Dengue is one of those diseases that is strongly influenced by climate variability; however its study in Central America has been poorly approached. In this study, we assessed potential associations between macroclimatic and microclimatic variation and dengue hemorrhagic fever (DHF) cases in the main hospital of Honduras during 2010. In this year, 3,353 cases of DHF were reported in the Hospital Escuela, Tegucigalpa. Climatic periods marked a difference of 158% in the mean incidence of cases, from El Niño weeks (-99% of cases below the mean incidence) to La Niña months (+59% of cases above it) (p<0.01). Linear regression showed significantly higher dengue incidence with lower values of Oceanic Niño Index (p=0.0097), higher rain probability (p=0.0149), accumulated rain (p=0.0443) and higher relative humidity (p=0.0292). At a multiple linear regression model using those variables, ONI values shown to be the most important and significant factor found to be associated with the monthly occurrence of DHF cases (r2=0.649; βstandardized=–0.836; p=0.01). As has been shown herein, climate variability is an important element influencing the dengue epidemiology in Honduras. However, it is necessary to extend these studies in this and other countries in the Central America region, because these models can be applied for surveillance as well as for prediction of dengue

Potential impacts of climate variability on Dengue Hemorrhagic Fever in Honduras, 2010

Climate change and variability are affecting human health and disease direct or indirectly through many mechanisms. Dengue is one of those diseases that is strongly influenced by climate variability; however its study in Central America has been poorly approached. In this study, we assessed potential associations between macroclimatic and microclimatic variation and dengue hemorrhagic fever (DHF) cases in the main hospital of Honduras during 2010. In this year, 3,353 cases of DHF were reported in the Hospital Escuela, Tegucigalpa. Climatic periods marked a difference of 158% in the mean incidence of cases, from El Niño weeks (-99% of cases below the mean incidence) to La Niña months (+59% of cases above it) (p<0.01). Linear regression showed significantly higher dengue incidence with lower values of Oceanic Niño Index (p=0.0097), higher rain probability (p=0.0149), accumulated rain (p=0.0443) and higher relative humidity (p=0.0292). At a multiple linear regression model using those variables, ONI values shown to be the most important and significant factor found to be associated with the monthly occurrence of DHF cases (r2=0.649; βstandardized=–0.836; p=0.01). As has been shown herein, climate variability is an important element influencing the dengue epidemiology in Honduras. However, it is necessary to extend these studies in this and other countries in the Central America region, because these models can be applied for surveillance as well as for prediction of dengue

Constraint rule-based programming of norms for electronic institutions

Peer reviewedPostprin

The Importance of Self-Generation of Electricity through Controlled Recycling: a Case Study in West Sub-Saharan African Regions

Controlled recycling of different materials, typical to household appliances, from the landfills located in developing countries in West Sub-Saharan Africa and their subsequent reuse can favour the social, economic and environmental sustainability of the involved regions. This process reduces the unhealthy conditions associated with landfills and the inadequate use of fuels, and it also solves certain deficits in the population. As a continuation of previous studies, this article proposes a practical example of manufacture through the controlled reuse of an asynchronous wind-powered electricity generation system, analysing the benefits and possibilities detected, especially in domestic self-generation and in the reduction of CO2 emissions into the atmosphere. In summary, the topic is the manufacture of an energy generating system using recycled material for domestic use. In this way, the associated self-generation of electricity can supply or reduce the energy demand of a large part of the population in these regions that do not have electricity supply; for example, for a household in Nigeria, it would save between 15% and 75% of the electricity supply. Providing electricity supply also prevents deforestation in regions that use natural biomass as an alternative energy source, an issue that has a global impact on CO2 emissions into the atmosphere