Characterization of mixing and spreading in a bounded stratified medium

Matheron and de Marsily [Matheron M, de Marsily G. Is the transport in porous media always diffusive? A counter-example. Water Resour Res 1980;16:901–17] studied transport in a perfectly stratified infinite medium as an idealized aquifer model. They observed superdiffusive solute spreading quantified by anomalous increase of the apparent longitudinal dispersion coefficient with the square root of time. Here, we investigate solute transport in a vertically bounded stratified random medium. Unlike for the infinite medium at asymptotically long times, disorder-induced mixing and spreading is uniquely quantified by a constant Taylor dispersion coefficient. Using a stochastic modeling approach we study the effective mixing and spreading dynamics at pre-asymptotic times in terms of effective average transport coefficients. The latter are defined on the basis of local moments, i.e., moments of the transport Green function. We investigate the impact of the position of the initial plume and the initial plume size on the (highly anomalous) pre-asymptotic effective spreading and mixing dynamics for single realizations and in average. Effectively, the system “remembers” its initial state, the effective transport coefficients show so-called memory effects, which disappear after the solute has sampled the full vertical extent of the medium. We study the impact of the intrinsic non-ergodicity of the confined medium on the validity of the stochastic modeling approach and study in this context the transition from the finite to the infinite mediu

Effective dispersion in a chemically heterogeneous medium under temporally fluctuating flow conditions

We investigate effective solute transport in a chemically heterogeneous medium subject to temporal fluctuations of the flow conditions. Focusing on spatial variations in the equilibrium adsorption properties, the corresponding fluctuating retardation factor is modeled as a stationary random space function. The temporal variability of the flow is represented by a stationary temporal random process. Solute spreading is quantified by effective dispersion coefficients, which are derived from the ensemble average of the second centered moments of the normalized solute distribution in a single disorder realization. Using first-order expansions in the variances of the respective random fields, we derive explicit compact expressions for the time behavior of the disorder induced contributions to the effective dispersion coefficients. Focusing on the contributions due to chemical heterogeneity and temporal fluctuations, we find enhanced transverse spreading characterized by a transverse effective dispersion coefficient that, in contrast to transport in steady flow fields, evolves to a disorder-induced macroscopic value (i.e., independent of local dispersion). At the same time, the asymptotic longitudinal dispersion coefficient can decrease. Under certain conditions the contribution to the longitudinal effective dispersion coefficient shows superdiffusive behavior, similar to that observed for transport in s stratified porous medium, before it decreases to its asymptotic value. The presented compact and easy to use expressions for the longitudinal and transverse effective dispersion coefficients can be used for the quantification of effective spreading and mixing in the context of the groundwater remediation based on hydraulic manipulation and for the effective modeling of reactive transport in heterogeneous media in general

Erratum: Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

Interpretation: By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning

Handbook of Active Ageing and Quality of Life: From Concepts to Applications

La edición de este libro estuvo a cargo de Fermina Rojo-Pérez y Gloria Fernández-Mayoralas.El documento adjunto contiene la cubierta, portada e índice del libro.This handbook presents an overview of studies on the relationship of active ageing and quality of life. It addresses the new challenges of ageing from the paradigm of positive ageing (active, healthy and successful) for a better quality of life. It provides theoretical perspectives and empirical studies, including scientific knowledge as well as practical experiences about the good ageing and the quality of later life around the world, in order to respond to the challenges of an aged population. The handbook is structured in 4 sections covering theoretical and conceptual perspectives, social policy issues and research agenda, methods, measurement instrument-scales and evaluations, and lastly application studies including domains and geographical contexts.Peer reviewe

Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.

BACKGROUND: The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk-outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk-outcome pairs, and new data on risk exposure levels and risk-outcome associations. METHODS: We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk-outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017

Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

Stanaway JD, Afshin A, Gakidou E, et al. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2018;392(10159):1923-1994.Background The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk outcome pairs, and new data on risk exposure levels and risk outcome associations. Methods We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017. Findings In 2017,34.1 million (95% uncertainty interval [UI] 33.3-35.0) deaths and 121 billion (144-1.28) DALYs were attributable to GBD risk factors. Globally, 61.0% (59.6-62.4) of deaths and 48.3% (46.3-50.2) of DALYs were attributed to the GBD 2017 risk factors. When ranked by risk-attributable DALYs, high systolic blood pressure (SBP) was the leading risk factor, accounting for 10.4 million (9.39-11.5) deaths and 218 million (198-237) DALYs, followed by smoking (7.10 million [6.83-7.37] deaths and 182 million [173-193] DALYs), high fasting plasma glucose (6.53 million [5.23-8.23] deaths and 171 million [144-201] DALYs), high body-mass index (BMI; 4.72 million [2.99-6.70] deaths and 148 million [98.6-202] DALYs), and short gestation for birthweight (1.43 million [1.36-1.51] deaths and 139 million [131-147] DALYs). In total, risk-attributable DALYs declined by 4.9% (3.3-6.5) between 2007 and 2017. In the absence of demographic changes (ie, population growth and ageing), changes in risk exposure and risk-deleted DALYs would have led to a 23.5% decline in DALYs during that period. Conversely, in the absence of changes in risk exposure and risk-deleted DALYs, demographic changes would have led to an 18.6% increase in DALYs during that period. The ratios of observed risk exposure levels to exposure levels expected based on SDI (O/E ratios) increased globally for unsafe drinking water and household air pollution between 1990 and 2017. This result suggests that development is occurring more rapidly than are changes in the underlying risk structure in a population. Conversely, nearly universal declines in O/E ratios for smoking and alcohol use indicate that, for a given SDI, exposure to these risks is declining. In 2017, the leading Level 4 risk factor for age-standardised DALY rates was high SBP in four super-regions: central Europe, eastern Europe, and central Asia; north Africa and Middle East; south Asia; and southeast Asia, east Asia, and Oceania. The leading risk factor in the high-income super-region was smoking, in Latin America and Caribbean was high BMI, and in sub-Saharan Africa was unsafe sex. O/E ratios for unsafe sex in sub-Saharan Africa were notably high, and those for alcohol use in north Africa and the Middle East were notably low. Interpretation By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning. Copyright (C) 2018 The Author(s). Published by Elsevier Ltd

Characterization of mixing and spreading in heterogeneous media

Tesis del Departament de Enginyeria del terreny cartográfica i geofísica de la Universitat Politècnica de Catalunya (UPC).-- Fecha de defensa 2-7-2008.[ESP] En esta tesis investigamos el transporte de solutos en acuíferos heterogéneos. Contrario al comportamiento observado en un escenario homogéneo, donde la mezcla y el spreading (ensanchamiento) son idénticos, en un acuífero heterogéneo, la mezcla y el spreading son mecanismos de transporte que no pueden ser medidos por un coeficiente de dispersión/difusión constante y único. Una de las principales novedades de nuestro trabajo es el análisis sobre la diferencia entre la mezcla y el spreading. Presentamos conceptos para cuantificar separadamente estos fenómenos en términos de coeficientes efectivos de dispersión.Las heterogeneidades espaciales/químicas que inducen variaciones en la velocidad del agua subterránea, así como las fluctuaciones temporales del flujo, son tomadas en cuenta aquí mediante un marco estocástico. Dentro de este marco, un acuífero es considerado como una realización típica del conjunto de todas las posibles realizaciones con las mismas características estadísticas. En una realización, el coeficiente local efectivo es derivado del segundo momento centrado de la distribución de concentración de un soluto que inicia desde un punto de inyección. Para una fuente inicial extendida, el coeficiente efectivo global es definido como el promedio ponderado sobre los coeficientes efectivos de dispersión de las fuentes puntuales que constituyen la fuente extendida. El coeficiente aparente de dispersión, para una fuente inicial extendida, es definido como la mitad de la taza de cambio del ancho de la distribución. Para tiempos cortos, refleja únicamente los efectos de spreading advectivo debido a las variaciones de la velocidad dentro de la distribución extendida.Para el conjunto de realizaciones de acuíferos, los coeficientes de dispersión efectivo y aparente son definidos como el promedio sobre el conjunto de coeficientes obtenido en cada realización. También definimos los coeficientes del conjunto locales y globales, los cuales son derivados del segundo momento centrado del conjunto promediado de distribuciones de concentración. Éstos cuantifican un efecto artificial debido a las fluctuaciones de la posición del centro de masa de realización a realización de los acuíferos heterogéneos.Las medidas efectivas definidas nos permiten cuantificar y caracterizar sistemáticamente la mezcla y el spreading en dos escenarios. Un medio físicamente homogéneo, químicamente heterogéneo sujeto a fluctuaciones temporales del flujo, y un medio estratificado que puede verse como un modelo idealizado de una formación geológica. Herramientas como la teoría de perturbaciones y ecuaciones de momentos axiales son usadas para derivar expresiones analíticas explícitas para los coeficientes efectivos de dispersión. Simulaciones numéricas “random-walk" son empleadas para complementar y verificar las soluciones analíticas de los coeficientes efectivos de transporte. Identificamos los mecanismos que inducen el ensanchamiento de la mezcla y el spreading, y determinamos las escalas espaciales y temporales que controlan su evolución temporal.[ENG] In this thesis we investigate solute transport through a heterogeneous aquifer. In contrast to the behavior observed in a homogeneous scenario, where mixing and spreading are identical, in a heterogeneous aquifer, mixing and spreading are different transport mechanisms which cannot be measured by a constant and common dispersion/diffusion coefficient. One of the aim novelties of our work is the elaboration on the difference between mixing and spreading. We present concepts to characterize and quantify separately these phenomena in terms of effective dispersion coefficients.Spatial/chemical medium heterogeneities that lead to groundwater velocity variability, as well as temporal flow fluctuations, here are taken into account within a stochastic modeling approach. In this approach, an aquifer is seen as a typical realization of the ensemble of all possible realizations with the same statistical properties. In a single realization, the local effective dispersion coefficient is derived from the centered second moment of the spatial concentration distribution of a solute starting from a point-like injection. For an extended initial source, the global effective dispersion coefficient is defined as the weighted average over the local effective dispersion coefficient for the point-sources that constitute the extended source. The apparent dispersion coefficient, for an extended initial source, is defined as the half rate of change of the width of a distribution. For early times, it re reflects the purely advective spreading effect due to velocity variations within the extended distribution. For the ensemble of aquifer realizations, the effective and apparent dispersion coefficients are defined as ensemble averages over their realizations counterparts. We also define local and global ensemble dispersion coefficients, which are derived from the second centered moment of the ensemble averaged concentration distribution. Both quantify an artificial effect due to center of mass fluctuations from realization to realization of the heterogeneous aquifers. The defined effective measures allow us to systematically characterize and quantify mixing and spreading in two scenarios. A physically homogeneous, chemically heterogeneous medium subject to temporal flow fluctuations, and a stratified medium which can be seen as an idealized model of a geological formation. Tools like perturbation theory and axial moment equations are used to derive explicit analytic expressions for the effective dispersion coefficients. Numerical random-walk simulations are used to complement and verify the analytical solutions of the effective transport coefficients. We identify the mechanisms that induce mixing and spreading enhancement, and determine the spatial and time scales which control its temporal evolution.This thesis was funded by the European Commission and the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya and by UPC with a grant to finish Phd thesis. It was developed in the framework of the ENRESA and the EU project UP FUNMIG (Contract No. 516514).Peer reviewe

Lo estético en el arte, el diseño y la vida cotidiana

El texto está dividido en tres apartados en los que se reúnen las investigaciones en los tres campos que consideramos que engloban los problemas de lo estético que nos ocupan: el arte, el diseño y la vida cotidiana. La temática de lo estético en el arte incluye la caracterización del teatro como fuente de placer estético y desarrollo social. Alternativas, desde las artes escénicas, a las categorías tradicionales de estética. Aproximaciones teórico-metodológicas sobre la experiencia artística guiada, como dispositivo de sensibilización estética. La organización de la problemática estética del dibujo. La coincidencia de belleza y verdad en la categoría estética de “bella verdad” aplicada al análisis de la imagen pictórica. El arte como experiencia estética transcultural que hace visibles estructuras sociales subyacentes donde el arte no siempre tiene relación con el gusto. El giro estético presente en la yuxtaposición de la producción de la realidad en un entorno artificial inmerso en la vida cotidiana a través de la experiencia estética. La estética del cine como forma de comprensión de la distopía como un sistema complejo social donde intervienen diferentes niveles de realidad. Y la estética de la violencia como forma de resistencia desde la voz sostenida por las nuevas feminidades. Lo estético en el diseño aborda el fenómeno de lo estético como parte del hombre en todas sus etapas, por lo que la irrupción de la tecnología digital e Internet no es la excepción. Se reflexiona sobre el fanzine como una manifestación cultural y como un fenómeno estético de las sociedades contemporáneas. Lo Trágico es una categoría estética que expresa la insulsa condición del hombre y que se explica en distintos ejemplos gráficos como son la pintura, la fotografía y el diseño de mensajes. La revalorización de la apreciación estética de la vivienda vernácula en México a partir de la valoración que el habitante hace de ella. La apreciación artística como una estrategia didáctica desde la estética para el fortalecimiento y desarrollo de la personalidad de los estudiantes universitarios. El coleccionismo de juguetes es un detonante de experiencias estéticas los juguetes no son sólo artefactos sino, también la nostalgia investida en ellos. Se explora la estética de los videojuegos y su desplazamiento de artefacto de diseño lúdico cotidiano a objeto de arte legitimado. Finalmente, el acercamiento al arte como experiencia estética donde la percepción juega un papel determinante. Lo estético en la vida cotidiana formula que a través de la creación de modelos que integran categorías analíticas transdisciplinarias y complejas podemos repensar la estética del arte popular mexicano de manera novedosa. La estética es analizada desde la perspectiva decolonial donde se considera al arte como dispositivo complejo y transdisciplinario, en particular, problematizados a través de movimientos estéticos comunitarios. Las narrativas que llamamos desobedientes repolitizan la mirada al enfrentar el régimen discursivo dominante. Las estéticas de la calle analizan la práctica estética-artística-cultural-urbana-alternativa conocida como graffiti de escritores, la cual se aleja de las posturas clásicas desde una posición crítica. El concepto de estética vinculándolo a la producción gráfica, establece el concepto de historia y cómo ésta condiciona o posibilita el valor simbólico y social de la actividad cartelística en la calle en la vida de las personas. En este apartado se considera a las prácticas culturales como forma de conocimiento y se evalúa su relación con la experiencia estética, así como se analiza lo estético como producción semiótico-discursiva desde enfoques conceptuales complejos, transdisciplinarios, decoloniales y del análisis del discurso

Global attitudes in the management of acute appendicitis during COVID-19 pandemic: ACIE Appy Study

Background: Surgical strategies are being adapted to face the COVID-19 pandemic. Recommendations on the management of acute appendicitis have been based on expert opinion, but very little evidence is available. This study addressed that dearth with a snapshot of worldwide approaches to appendicitis. Methods: The Association of Italian Surgeons in Europe designed an online survey to assess the current attitude of surgeons globally regarding the management of patients with acute appendicitis during the pandemic. Questions were divided into baseline information, hospital organization and screening, personal protective equipment, management and surgical approach, and patient presentation before versus during the pandemic. Results: Of 744 answers, 709 (from 66 countries) were complete and were included in the analysis. Most hospitals were treating both patients with and those without COVID. There was variation in screening indications and modality used, with chest X-ray plus molecular testing (PCR) being the commonest (19\ub78 per cent). Conservative management of complicated and uncomplicated appendicitis was used by 6\ub76 and 2\ub74 per cent respectively before, but 23\ub77 and 5\ub73 per cent, during the pandemic (both P < 0\ub7001). One-third changed their approach from laparoscopic to open surgery owing to the popular (but evidence-lacking) advice from expert groups during the initial phase of the pandemic. No agreement on how to filter surgical smoke plume during laparoscopy was identified. There was an overall reduction in the number of patients admitted with appendicitis and one-third felt that patients who did present had more severe appendicitis than they usually observe. Conclusion: Conservative management of mild appendicitis has been possible during the pandemic. The fact that some surgeons switched to open appendicectomy may reflect the poor guidelines that emanated in the early phase of SARS-CoV-2