Reconstructing past fossil-fuel CO2 concentrations using tree rings and radiocarbon in the urban area of Medellín, Colombia

To meet international and national commitments to decrease emissions of fossil fuels, cities around the world must obtain information on their historical levels of emissions, identifying hotspots that require special attention. Direct atmospheric measurements of pollution sources are almost impossible to obtain retrospectively. However, tree rings serve as an archive of environmental information for reconstructing the temporal and spatial distribution of fossil-fuel emissions in urban areas. Here, we present a novel methodology to reconstruct the spatial and temporal contribution of fossil-fuel CO2 concentration ([CO2F]) in the urban area of Medellin, Colombia. We used a combination of dendrochronological analyses, radiocarbon measurements, and statistical modeling. We obtained annual maps of [CO2F] from 1977 to 2018 that describe changes in its spatial distribution over time. Our method was successful at identifying hotspots of emissions around industrial areas, and areas with high traffic density. It also identified temporal trends that may be related to socioeconomic and technological factors. We observed an important increase in [CO2F] during the last decade, which suggests that efforts of city officials to reduce traffic and emissions did not have a significant impact on the contribution of fossil fuels to local air. The method presented here could be of significant value for city planners and environmental officials from other urban areas around the world. It allows identifying hotspots of fossil fuels emissions, evaluating the impact of previous environmental policies, and planning new interventions to reduce emissions.Reconstructing past fossil-fuel CO2 concentrations using tree rings and radiocarbon in the urban area of Medellín, ColombiapublishedVersio

May anomalous X chromosome methylation be responsible for the spontaneous abortion of a male foetus?

Pregnancy loss is an important reproductive problem which appears to be highly associated with genetic factors. A spontaneous abortion occurred before prenatal diagnosis could be performed, in a woman who carried a fragile X full mutation. DNA extracted from formalin-fixed para ffin-embedded chorionic villi preparations indicated that it was a male embryo with an apparently methylated X chromosome. The previous analysis of the family showed that her daughter, who also carried a full mutation, exhibited an extremely skewed X inactivation of the normal allele (100%) and a severe fragile X phenotype. Thus, we speculate that the aberrant pattern of X chromosome methylation in this family may provoke the spontaneous miscarriage of this pregnancy that could be explained by at least partial inactivation of the unique X chromosome in a male foetus. Spontaneous abortion occurs quite frequently in humans, and recurrent pregnancy loss is a significant problem in women’s health (Christiansen 2006). Many cases of spontaneous abortion defy diagnosis and genetic factors have been proposed as a major contribution (Lanasa and Hogge 2000; Sierra and Stephenson 2006). The X chromosome inactiva tion (XCI) is the process in which one of the two X chromosomes present in each cell of female mammals is inactivated during early embryogenesis, to achieve dosage compensation with males (Avner and Heard 2001; Heard 2004). Initial steps of XCI involve a ‘counting process’, which senses the X chromosome/autosome ratio that restricts XCI to female embryos and, thereafter, the choice of which chromosome is inactivated (Morey et al . 2004).Skewed XCI leads to an expression of X-linked recessive disorders in females (Plenge et al. 2002; Mart´ınez et al. 2005; Renault et al. 2007). Another form of X-inactivation called meiotic sex chromosome inactivation (MSCI), takes place in males, during spermatogenesis and is a manifestation of the general meiotic-silencing mechanism (Turner 2007). In this study, we report the spontaneous abortion of a male foetus with an apparently methylated X chromosome, and propose that anomalous inactivation of its uniqueX chromosome could explain nonviability of the embryo and pregnancy loss. Therefore, we strongly suggest, as a follow up, that the methylation status of the X chromosome be tested in early spontaneous abortion of males in the absence of any other known genetic or nongenetic cause

Influence of the substrate on the formation of metallic glass coatings by cold gas spraying

Cold gas spray technology has been used to build up coatings of Fe-base metallic glass onto different metallic substrates. In this work, the effect of the substrate properties on the viscoplastic response of metallic glass particles during their impact has been studied. Thick coatings with high deposition efficiencies have been built-up in conditions of homogeneous flow on substrates such as Mild Steel AISI 1040, Stainless Steel 316L, Inconel 625, Aluminum 7075-T6, and Copper (99.9%). Properties of the substrate have been identified to play an important role in the viscoplastic response of the metallic glass particles at impact. Depending on the process gas conditions, the impact morphologies show not only inhomogeneous deformation but also homogeneous plastic flow despite the high strain rates, 10 8 to 10(9) s(-1), involved in the technique. Interestingly, homogenous deformation of metallic glass particles is promoted depending on the hardness and the thermal diffusivity of the substrate and it is not exclusively a function of the kinetic energy and the temperature of the particle at impact. Coating formation is discussed in terms of fundamentals of dynamics of undercooled liquids, viscoplastic flow mechanisms of metallic glasses, and substrate properties. The findings presented in this work have been used to build up a detailed scheme of the deposition mechanism of metallic glass coatings by the cold gas spraying technology

Local invertibility in Sobolev spaces with applications to nematic elastomers and magnetoelasticity

We define a class of deformations in W^1,p(\u3a9,R^n), p>n 121, with positive Jacobian that do not exhibit cavitation. We characterize that class in terms of the non-negativity of the topological degree and the equality between the distributional determinant and the pointwise determinant of the gradient. Maps in this class are shown to satisfy a property of weak monotonicity, and, as a consequence, they enjoy an extra degree of regularity. We also prove that these deformations are locally invertible; moreover, the neighbourhood of invertibility is stable along a weak convergent sequence in W^1,p, and the sequence of local inverses converges to the local inverse. We use those features to show weak lower semicontinuity of functionals defined in the deformed configuration and functionals involving composition of maps. We apply those results to prove existence of minimizers in some models for nematic elastomers and magnetoelasticity

Influence of Cold Gas Spray process conditions on the microstructure of Fe-based amorphous coatings

Fe-based amorphous metallic coatings were prepared by Cold Gas Spray process. Through this study, the effects of the process conditions such as spraying distance, gas pressure and temperature on the microstructure of as-sprayed coatings are evaluated. Microstructural studies show that the coatings can present a densely layered structure with porosity below 0.5% and thickness around 800 μm depending on the process conditions. Precipitation of nanocrystals in as-sprayed coatings is observed and present results show its dependence on the thermal and kinetic energy implicated in the process. In general, when gas temperature and pressure decreased, in the studied range, coatings displayed a dense and amorphous structure

Agroecología y el diseño de sistemas agrícolas resilientes al cambio climático

Diverse, severe and location-specific impacts on agricultural production are anticipated with climate change.Temperature and water availability remain key factors in determining crop growth and productivity, predicted changes in these factors will lead to reduced crop yields. Climate induced changes in insect pest, pathogen and weed population dynamics and invasiveness could compound such effects. Undoubtedly climate and weather induced instability will affect levels of and access to food supply. Changes that will not radically modify the monoculture nature of dominant agroecosystems may temporarily moderate negative impacts. The biggest and most durable benefits will likely result from more radical agroecological measures that will strengthen the resilience of farmers and rural communities, such as diversification of agroecosytems in the form of polycultures, agroforestry systems and crop-livestock mixed systems accompanied by organic soil management, water conservation and harvesting and general enhancement of agrobiodiversity. Traditional farming systems are repositories of a wealth of principles and measures that can help modern agricultural systems become more resilient to climatic extremes. Many of these agroecological strategies that reduce vulnerabilities to climate variability include, crop diversification, maintaining local genetic diversity, animal integration, soil organic management, water conservation and harvesting, etc. Understanding the agroecological features that underlie the resilience of traditional agroecosystems is an urgent matter, as they can serve as the foundation for the design of adapted agricultural systems. Field surveys and results reported in the literature suggest that agroecosystems are more resilient when inserted in a complex landscape matrix, featuring adapted local germplasm deployed in diversified cropping systems managed with organic matter rich soils and water conservation-harvesting techniques. The identification of systems that have withstood climatic events recently or in the past and understanding the agroecological features of such systems that allowed them to resist and/or recover from extreme events is of increased urgency, as the derived resiliency principles and practices that underlie successful farms can be disseminated to thousands of farmers.Se anticipa que el cambio climático cause impactos sobre la producción agrícola que serán diversos, severos y específicos según la ubicación geográfica. La temperatura y la disponibilidad de agua siguen siendo factores clave que determinan el crecimiento de los cultivos y la productividad. Los cambios predichos en estos factores causarán una baja en el rendimiento de los cultivos. Los cambios inducidos por el clima en cuanto a las dinámicas de población de plagas de insectos, patógenos y malezas y su invasividad podrían agravar los efectos mencionados. Sin duda alguna, la inestabilidad inducida por el clima y el tiempo afectará los niveles de producción de alimentos y el abastecimiento de los mismos. Los cambios para la adaptación que no modifiquen radicalmente la naturaleza dominante del monocultivo podrían moderar temporalmente los impactos negativos. Los beneficios mayores y más duraderos provendrán de medidas agroecológicas más radicales que fortalezcan la resiliencia de los agricultores y las comunidades rurales, tales como la diversificación de los agroecosistemas en forma de policultivos, los sistemas agroforestales y los sistemas que combinen la agricultura con la ganadería, acompañados por el manejo orgánico de los suelos, la conservación y la cosecha de agua y un incremento general de la agrobiodiversidad. Los sistemas agrícolas tradicionales son depósitos de abundantes principios y medidas que pueden ayudar a que los sistemas agrícolas modernos se vuelven más resilientes a los extremos climáticos. Muchas de las estrategias agroecológicas tradicionales que reducen la vulnerabilidad a la variabilidad climática incluyen la diversificación de cultivos, el mantenimiento de la diversidad genética local, la integración de los animales, la adición de materia orgánica al suelo, la cosecha de agua, etc. Urge entender las características agroecológicas que son la base de la resiliencia de los agroecosistemas tradicionales, ya que de ahí se pueden derivar principios útiles que sirvan de base para el diseño de sistemas agrícolas adaptados. Los estudios sobre el terreno y los resultados reportados en la literatura sugieren que los agroecosistemas son más resilientes cuando están insertados en una matriz de paisaje compleja, que incluya germoplasma local adaptado utilizado en sistemas de cultivos diversificados manejados con suelos ricos en materia orgánica y técnicas de conservación-cosecha de agua. Los principios y prácticas de resiliencia en los que se basan las fincas exitosas pueden ser difundidos a miles de agricultores a través de redes campesino a campesino para ampliar las prácticas agroecológicas que incrementan la resiliencia de los agroecosistemas

Charged Annular Disks and Reissner-Nordstr\"{o}m Type Black Holes from Extremal Dust

We present the first analytical superposition of a charged black hole with an annular disk of extremal dust. In order to obtain the solutions, we first solve the Einstein-Maxwell field equations for sources that represent disk-like configurations of matter in confomastatic spacetimes by assuming a functional dependence among the metric function, the electric potential and an auxiliary function,which is taken as a solution of the Laplace equation. We then employ the Lord Kelvin Inversion Method applied to models of finite extension in order to obtain annular disks. The structures obtained extend to infinity, but their total masses are finite and all the energy conditions are satisfied. Finally, we observe that the extremal Reissner-Nordstr\"{o}m black hole can be embedded into the center of the disks by adding a boundary term in the inversion.Comment: 17 revtex pages, 8 eps figure

Preacondicionamiento de la semilla de arveja (pisum sativum l.)

En el Centro de Investigación "La selva ", de la Corporación Colombiana de Investigación Agropecuaria. CORPOICA, ubicado en Rionegro, Antioquia. a 2120 msnm, con una temperatura promedio de 17 °C y perteneciente a la formación ecológica Bosque Húmedo Montano Bajo, se llevó a cabo un estudio con la especie arveja (Pisum sativum L.), con el fin de evaluar el efecto del tratamiento de preacondicionamiento de las semillas, conocido como humedecimiento-secado, sobre la germinación, la emergencia y el establecimiento de plantas. Adicionalmente se evaluó el procedimiento con diferentes concentraciones del fungicida sistémico benomyl, en comparación con agua destilada, buscándose reducir la pérdida de plantas durante el período de establecimiento del cultivo, y se midió el efecto de los tratamientos con y sin fungicida sobre el rendimiento, en comparación con plantas provenientes de semilla no preacondicionada. A nivel de laboratorio se encontró que el tratamiento que produjo mayor velocidad de germinación fué la imbibición hasta el 75% de peso de la semilla, con secado posterior hasta recobrar el peso inicial. Utilizando el tratamiento anterior, se halló que la adición de benomyl, en diferentes concentraciones, no afectó la velocidad de germinación ni la germinación total, incrementándose el porcentaje de plantas sanas obtenidas en comparación con el preacondicionamiento sin fungicida, con valores máximos al imbibir con una solución de benomyl al 0.1%. En el campo no se observó efecto de los tratamientos de preacondicionamiento con y sin fungicida sobre la velocidad de emergencia y la emergencia total, reduciendo los tratamientos con fungicida la incidencia de plantas muertas en forma sensible con una respuesta diferencial en rendimiento, por parte de las dos variedades estudiadas, al aplicar los diversos procedimientos de preacondicionamiento. Así, mientras que con el cultivar 'Small Sieve All Sweet ', no hubo efecto en la productividad por parte de los tratamientos, éste fué evidente en el cultivar 'Bogotana', con rendimiento máximo en las plantas provenientes de semilla preacondicionada con una solución de benomyl al 0.05%

Genre analysis of book reviews in English and Spanish : a look at rhetorical moves and appraisal

Els estudis anteriors han omès la relació entre l'estructura i el llenguatge avaluatiu en les ressenyes acadèmiques en castellà i anglès. Per emplenar aquest buit, el nostre estudi porta a terme una anàlisi a dos nivells, macroestructural i microlingüístic, del llenguatge de la avaluació en 18 ressenyes de llibres (9 per llengua) publicades en reconegudes revistes en lingüística aplicada. Els nostres resultats suggereixen l'existència de variacions estructurals dins dels moviments retòrics i diferències en la forma com s'expressa la lloança en les cultures acadèmiques anglosaxona i hispanoparlant respectivament. Aquestes troballes contribuiran a millorar la comprensió del gènere de la ressenya i oferiran models reals als acadèmics en formació.Los estudios anteriores han omitido la relación entre la estructura y el lenguaje evaluativo en las reseñas académicas en castellano e inglés. Para llenar este vacío, nuestro estudio realiza un análisis en dos níveles, macroestructural y microlingüístico, del lenguaje de evaluación en 18 reseñas de libros (9 por lengua) publicadas en reconocidas revistas en lingüística aplicada. Nuestros resultados sugieren la existencia de variaciones estructurales dentro de los movimientos retóricos y diferencias en la forma cómo se expresa la alabanza en las culturas académicas anglosajona e hispanohablante respectivamente. Estos hallazgos contribuirán a mejorar la comprensión del género de la reseña y ofrecerán modelos reales a los académicos en formación.Previous studies have failed to examine the link between structure and evaluation in book reviews (BRs). To fill this gap, our study carries out a two-tiered macrostructural and microlinguistic analysis of the language of appraisal in English and Spanish BRs. To this end, a corpus of 18 reviews (9 per language) has been created from well-known journals in applied linguistics. Our results suggest structural variations within the rhetorical moves and differences in how Anglo-Saxon and Spanish-speaking academic cultures express appraisal. We hope that our findings will enrich the understanding of the genre and provide real models for scholars in formation