Urban Habitability in Public Space, the Historic Center of Toluca, State of Mexico Case

La ciudad, visualizada como el hábitat predominante del hombre contemporáneo, ha venido sufriendo una notoria degradación ambiental y de la vida social. Por ello, temas relativos a lo habitable de los espacios públicos, surgen con gran fuerza sobre todo en América Latina, donde la generalidad de prácticas urbanas no trae implícitos parámetros de calidad que ofrezcan un nivel de vida apropiado a sus habitantes.Esta investigación tiene como objetivo presentar un esquema metodológico para la evaluación de la habitabilidad de los espacios públicos del centro histórico de Toluca, empleando parámetros “universales” enfocados en adultos mayores y usuarios de sillas de ruedas principalmente. Se evaluó la accesibilidad peatonal mediante el paso entre calles, facilidad para caminar por conectividad de calles, percepción de inseguridad ante la delincuencia y ruido ambiental dB(A). Se realizaron mediciones in situ, con imágenes satelitales y encuestas a peatones. La unidad de estudio, bloques de 400 x 400 m. En el centro histórico se identificó inequidad en los accesos y una navegación peatonal difícil. La percepción de seguridad se muestra degradada y con un entorno ruidoso, sobre todo en la región central. El método propuesto integró información mixta con un enfoque holístico y el empleo de la escala a nivel de barrio aporta un valor añadido. Como limitantes resaltamos que la proyección espacial no siempre ofrece explicaciones causales, faltan elementos de evaluación global y se han dejado muchas variables de habitabilidad por resolver. En conclusión, los espacios públicos requieren especial atención para hacerlos habitables y equitativos, empezando por su evaluación e implicación en políticas públicas y de gestión.Universidad Autónoma del Estado de México - Universidad Juárez Autónoma de Tabasc

Calibration of a wide angle stereoscopic system

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.003064. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Inaccuracies in the calibration of a stereoscopic system appear with errors in point correspondences between both images and inexact points localization in each image. Errors increase if the stereoscopic system is composed of wide angle lens cameras. We propose a technique where detected points in both images are corrected before estimating the fundamental matrix and the lens distortion models. Since points are corrected first, errors in point correspondences and point localization are avoided. To correct point location in both images, geometrical and epipolar constraints are imposed in a nonlinear minimization problem. Geometrical constraints define the point localization in relation to its neighbors in the same image, and eipolar constraints represent the location of one point referred to its corresponding point in the other image. © 2011 Optical Society of America.Ricolfe Viala, C.; Sánchez Salmerón, AJ.; Martínez Berti, E. (2011). Calibration of a wide angle stereoscopic system. Optics Letters. 36(16):3064-3067. doi:10.1364/OL.36.003064S306430673616Zhang, Z., Ma, H., Guo, T., Zhang, S., & Chen, J. (2011). Simple, flexible calibration of phase calculation-based three-dimensional imaging system. Optics Letters, 36(7), 1257. doi:10.1364/ol.36.001257Longuet-Higgins, H. C. (1981). A computer algorithm for reconstructing a scene from two projections. Nature, 293(5828), 133-135. doi:10.1038/293133a0Ricolfe-Viala, C., & Sanchez-Salmeron, A.-J. (2010). Lens distortion models evaluation. Applied Optics, 49(30), 5914. doi:10.1364/ao.49.005914Armangué, X., & Salvi, J. (2003). Overall view regarding fundamental matrix estimation. Image and Vision Computing, 21(2), 205-220. doi:10.1016/s0262-8856(02)00154-3Devernay, F., & Faugeras, O. (2001). Straight lines have to be straight. Machine Vision and Applications, 13(1), 14-24. doi:10.1007/pl0001326

Power system stability of a small sized isolated network supplied by a combined wind-pumped storage generation system: a case study in the Canary Islands

Massive integration of renewable energy sources in electrical power systems of remote islands is a subject of current interest. The increasing cost of fossil fuels, transport costs to isolated sites and environmental concerns constitute a serious drawback to the use of conventional fossil fuel plants. In a weak electrical grid, as it is typical on an island, if a large amount of conventional generation is substituted by renewable energy sources, power system safety and stability can be compromised, in the case of large grid disturbances. In this work, a model for transient stability analysis of an isolated electrical grid exclusively fed from a combination of renewable energy sources has been studied. This new generation model will be installed in El Hierro Island, in Spain. Additionally, an operation strategy to coordinate the generation units (wind, hydro) is also established. Attention is given to the assessment of inertial energy and reactive current to guarantee power system stability against large disturbances. The effectiveness of the proposed strategy is shown by means of simulation results

Mollusc-shell debris can mitigate the deleterious effects of organic pollution on marine sediments

1. Organic pollution is widespread in coastal areas and can have profound impacts on the seabed. Coastal sediments play an important role at a global scale in the recycling of organic matter, and this process is influenced by the habitat complexity of the sediments, among other factors. Mollusc shells are produced as a waste product from a range of anthropogenic activities, but we demonstrate that they can be used to increase the habitat complexity of sediments. 2. We studied the effect of mussel-shell debris (shell-hash) on the biogeochemical processes of marine sediments affected by organic pollution, using a mesocosm experiment simulating the bioturbation effects of macrofauna. 3. We found that shell-hash improved the ecological status of organically polluted sediments by reducing the accumulation of sulphide from anaerobic metabolic pathways. 4. Additionally, when shell-hash was present in an organically polluted sediment, there was a decrease in ammonium release to the water column, thus preventing the negative ecological consequences of eutrophication. 5. Synthesis and applications. Our study indicates that shell-hash debris can be used as a potential tool to mitigate the effects of organic enrichment on marine sediments. A density of shell-hash debris of 1900 g m-2 in the sediment can diminish toxic by-products (sulphides and ammonium) derived from the stimulation of anaerobic metabolic pathways by organic pollution, at levels that are biologically relevant. The mitigation effect of shell-hash is more pronounced in sediments where macrofauna is not present.This work has been funded by the projects: GRE14-19 from the University of Alicante, GV/2015/001 from the ‘Conselleria de Educación, Cultura y Deporte’ of the government of the Valencia region and CGL2015-70136-R from the Ministerio de Economía y Competitividad (MINECO/FEDER) of Spain. CS was funded by the contract ‘Juan de la Cierva’ (ref. JCI-2012-12413) from MINECO

Environmental Policy to Foster a Green Differentiated Energy Market

Many products are made by technological processes that cause environmental damage. Current environmental concerns are affecting firms' technological processes as a result of government intervention in markets but also due to environmental awareness on the part of consumers. This paper assumes a spatial competition model where two firms sell a homogeneous product with input differentiation: the product is made by green and polluting inputs. In a two-stage game firms first decide what technology bundle to use (the ratio of green and polluting inputs) and then Bertrand competition takes place. First, it is shown that in the absence of government intervention both firms prefer to produce by using a bundle of green and polluting technologies which is not welfare maximizing. Second, the option of subsidizing green technology and the existence of a publicly-owned firm are analyzed. Overall, both policies yield a more environmentally-friendly technology bundle, except when costs of green energy technologies are high enough. Moreover, environmental social welfare is enhanced

Environmental Policy to Foster a Green Differentiated Energy Market

Many products are made by technological processes that cause environmental damage. Current environmental concerns are affecting firms' technological processes as a result of government intervention in markets but also due to environmental awareness on the part of consumers. This paper assumes a spatial competition model where two firms sell a homogeneous product with input differentiation: the product is made by green and polluting inputs. In a two-stage game firms first decide what technology bundle to use (the ratio of green and polluting inputs) and then Bertrand competition takes place. First, it is shown that in the absence of government intervention both firms prefer to produce by using a bundle of green and polluting technologies which is not welfare maximizing. Second, the option of subsidizing green technology and the existence of a publicly-owned firm are analyzed. Overall, both policies yield a more environmentally-friendly technology bundle, except when costs of green energy technologies are high enough. Moreover, environmental social welfare is enhanced

Contribution of psychoactive substance use and other environmental factors to adolescent pregnancies in Mexico

Introduction: Mexico has the highest prevalence of adolescent pregnancies among all the member countries of the Organization for Economic Co-operation and Development (OECD) with a fertility rate of 70.6 births for every 1000 women aged 15–19 years. This study explored the associations between psychoactive substance use and adolescent pregnancy in 3263 adolescents. Methods: This was a cross-sectional study using data from the National Health and Nutrition Survey 2018. We examined adolescent pregnancy among a sample of currently pregnant, ever pregnant and never pregnant teenage girls. The prevalence of psychoactive substance use was estimated at the state level using the 2016 National Survey of Drug, Alcohol, and Tobacco Use. Multilevel logistic models were fitted to evaluate the association between psychoactive substance use and adolescent pregnancy. Results: Girls living in states with high prevalence of illegal drug use, non-prescription use of medical drugs, alcohol abuse and daily tobacco use had higher odds of having adolescent pregnancy (OR=1.22, 95% CI: 1.17–1.27; OR=2.00, 95% CI: 1.66–2.39; OR=1.10, 95% CI: 1.03–1.13; and OR=1.05, 95% CI: 1.03–1.18, respectively). Finally, adolescent pregnancy was positively associated with population density (OR=0.85, 95% CI: 0.82–0.88) and number of homicides (OR=1.08, 95% CI: 1.03–1.13). Conclusions: The exposure of adolescents to psychoactive substances may directly contribute to having a pregnancy. Also, these findings highlight the importance of attending school, having high school education and being beneficiaries of the social program CCT-POP in reducing adolescent fertility rates.S

Complex I and cytochrome c are molecular targets of flavonoids that inhibit hydrogen peroxide production by mitochondria

AbstractFlavonoids can protect cells from different insults that lead to mitochondria-mediated cell death, and epidemiological data show that some of these compounds attenuate the progression of diseases associated with oxidative stress and mitochondrial dysfunction. In this work, a screening of 5 flavonoids representing major subclasses showed that they display different effects on H2O2 production by mitochondria isolated from rat brain and heart. Quercetin, kaempferol and epicatechin are potent inhibitors of H2O2 production by mitochondria from both tissues (IC50≈1–2μM), even when H2O2 production rate was stimulated by the mitochondrial inhibitors rotenone and antimycin A. Although the rate of oxygen consumption was unaffected by concentrations up to 10μM of these flavonoids, quercetin, kaempferol and apigenin inhibited complex I activity, while up to 100μM epicatechin produced less than 20% inhibition. The extent of this inhibition was found to be dependent on the concentration of coenzyme Q in the medium, suggesting competition between the flavonoids and ubiquinone for close binding sites in the complex. In contrast, these flavonoids did not significantly inhibit the activity of complexes II and III, and did not affect the redox state of complex IV. However, we have found that epicatechin, quercetin and kaempferol are able to stoichiometrically reduce purified cytochrome c. Our results reveal that mitochondria are a plausible main target of flavonoids mediating, at least in part, their reported preventive actions against oxidative stress and mitochondrial dysfunction-associated pathologies

Special Issue on Polarimetric SAR Techniques and Applications

Synthetic Aperture Radar (SAR) polarimetry is an active and fruitful field of research in Earth observation. Polarimetry provides sensitivity to the soil moisture, as well as to the structural and geometric properties of the targets under observation, allowing a more accurate identification and classification than with non-polarimetric data. Moreover, the increasing number of spaceborne SAR systems equipped with polarimetric capabilities, as well as future planned missions, enables the advance in this research field at all levels, from theory and physical modeling to final applications