Soil heterogeneity and preferential paths for gas migration

Preferential paths are often reported in connection with gas breakthrough experiments. These preferential paths may be explained, in a deformable soil skeleton, by the action of pressurised gas along a natural path. A natural path is defined in a spatially heterogeneous material by a set of connected spots of higher gas permeability. Along this path the soil will experience a marked desaturation and gas permeability will increase fast. The paper describes a procedure to simulate these effects. Soil heterogeneity is described by means of random fields, which describe the key soil properties for gas migration. Since actual data concerning soil variability at a small (sample) scale is very limited, a number of computer models of increased complexity have been developed. They maintain, however, a close relationship with the known macroscopic data of the average (homogeneous) sample. The effect of some hypothesis concerning the stochastic structure of soil variability and the role of the hydromechanical coupling has also been explored. Once the heterogeneous soil model is defined, a general purpose code for Thermo-Hydro- Mechanical analysis is subsequently used to perform the analysis. The soil is initially saturated and a non-wetting phase (gas) is forced through the saturated mass either at constant pressure or at a constant flow rate. The results of the different analyses are compared in order to advance in the basic understanding of gas migration through clay barriers. Finally, a discussion of the relevance of soil heterogeneity, on the basis of the analysis performed, is presented.Peer Reviewe

Variables que dinamizan el acceso a las tecnologías de información y comunicación en familias de ingreso medio del Valle de Aburrá

RESUMEN: El presente artículo muestra una metodología para seleccionar las variables que tengan una influencia significativa en la dinamización del acceso a las tecnologías de información y comunicación (TIC) en las familias de ingreso medio en el Valle de Aburrá, así como las interrelaciones principales entre esas variables. Las variables se escogen a partir de la combinación de tres métodos de interpretación de resultados, basados en Análisis Estructural con el software MICMAC (Impact Matrix Cross-reference Multiplication).ABSTRACT: This paper presents the methodology for the selection of the most important or essential variables to access information and communication technologies (ICT) in middle-income families from a developing country. The variables are chosen through a combination of three different methods for the interpretation of the results based on structural analysis using MICMAC (Impact Matrix Cross-reference Multiplication) software

Influence of rainfall on the deformation and stability of a slope in overconsolidated clays: a case study

The behaviour of an instrumented unstable slope in a profile of weathered overconsolidated clay has been analysed. Available field investigation data and laboratory tests were integrated in a coupled hydromechanical model of the slope. Particular attention was given to the unsaturated soil conditions above the water table and to the influence of the rainfall record. Recorded pore-water pressures helped to identify the hydrogeological conditions of the slope. The coupled model was used to compute slope deformations and the variation of safety with time. Actual rainfall records were also integrated into the analysis. Comparison of measurements and calculations illustrate the nature of the slope instability and the complex relationships between mechanical and hydraulic factors.Peer Reviewe

Composición de aceites esenciales de diferentes especies de “pimienta” de los géneros Piper, Pimenta, Lindera, Ruta, Schinus y Zanthoxylum

Se ha extraído mediante hidrodestilación el aceite esencial de diez especies usadas como pimienta: Piper borbonense, P. capense, P. retrofractum, P. nigrum, Zanthoxylum bungeanum y Z. armatum, Lindera neesiana, Ruta chalepensis, Schinus terebenthifolia, Pimenta dioica. Los análisis realizados mediante cromatografía de gases acoplada a espectrometría de masas encontraron que todas presentan β-felandreno y derivados de cariofileno y felandreno, siendo estos compuestos de propiedades pungentes los característicos de la especia pimienta. El rendimiento de esencia varía desde 0,43% para R. chalepensis hasta 7,61% para P. borbonense. Los compuestos mayoritarios fueron: P. borbonense (α-felandreno, 12,43%), P. capense (δ-cadineno, 25,59%,), P. retrofractum (γ-cadineno, 31,63%), P. nigrum ((E)-β-cariofileno, 22,88%), P. dioica (eugenol, 48,93%), L. neesiana (miristicina, 14,13%), R. chalepensis (2-undecanona, 64,93%), S. therebenthifolia (δ-3-careno, 29,21%), Z. armatum (linalool, 53,30%); Z. bungeanum (linalool, 64,09%). Todo esto muestra las diferencias en el metabolismo secundario de las pimientas y por tanto sus posibles aplicaciones en diferentes industrias

Coupled analysis of a backfill hydration test

BACCHUS2 in situ isothermal wetting experiment has been analysed by means of a coupled flow-deformation approach. Backfill material, a mixture of Boom clay powder and high density pellets, has been extensively tested in the laboratory in order to determine its hydraulic and mechanical properties. Parameters of constitutive equations were derived from this experimental data base. Two mechanical constitutive models have been used in the simulation of the 'in situ' experiment: a state surface approach and an elastoplastic model. Calculations have shown several features of the hydration process which help to understand the behaviour of expansive clay barriers. Predictions using both models have been compared with each other and with actual measurement records. This has allowed a discussion of the comparative mertis of both approaches and the identiÞcation of some critical parameters of backfill behaviour. Overall agreement between calculations and field measurements is encouraging and shows the potential of the methods developed to model the behaviour of engineered clay barriers in the context of nuclear waste disposal.Peer Reviewe

Riesgo de mercado en Portafolios mexicanos previo a la crisis COVID-19: Portafolio de renta fija vs Portafolio de capital

Market risk in Mexican Portfolios prior to the COVID-19 crisis: Fixed Income Portfolio vs Equity PortfolioThe objective of the research is to show the advantages that investments in fixed income portfolios have over capital investments in the study period. A comparison of both Portfolios is made from January 2017 to May 2019, having as a metric the parametric VaR at 99.9% confidence for each Portfolio. The results show that the investor obtains a greater amount of profits ($9,778.14) in the fixed income Portfolio by investing$ 1,000,000 at 28 days, so prior to the COVID-19 crisis it is oberved that it was feasible to invest in this type of Portfolio. Gaussian returns are assumed as a limitation. The work is original because with real data from the Mexican market it is empirically shown that prior to the COVID-19 crisis period, fixed income portfolios was better in returns than capital portfolios. Finally, it is concluded that nowadays the above does not happen, due to the great fall that the reference rates have had in Mexico derived from the COVID-19 health crisis, even negative real rates are glimpsed soon.El objetivo de la investigación es mostrar las ventajas que tienen las inversiones en Portafolios de renta fija respecto a los de capital en el periodo de estudio. Se realiza un comparativo de ambos Portafolios de enero 2017 a mayo 2019, teniendo como métrica el VaR paramétrico al 99.9% de confianza para cada Portafolio. Los resultados, muestran que el inversionista obtiene una mayor cantidad de ganancias ($9,778.14) en el Portafolio de renta fija al invertir$1,000,000 a 28 días, por lo que previo a la crisis COVID-19 se observa que fue viable invertir en este tipo de Portafolio. Como limitación se asumen rendimientos gaussianos. El trabajo es original porque con datos reales del mercado mexicano empíricamente se muestra que previamente al periodo de crisis COVID-19 el Portafolio de renta fija fue mejor en rendimientos que los Portafolios de capitales. Finalmente se concluye que hoy en día lo anterior no ocurre, debido a la gran caída que han tenido las tasas de referencia en México derivada de la crisis sanitaria COVID-19, incluso se vislumbran a la brevedad tasas reales negativas

Influencia del alginato de sodio sobre la sineresis en jamón cocido.

El objetivo de este estudio fue evaluar la calidad del jamón de cerdo cocido usando alginato de sodio y carragenina durante la elaboración y almacenado a 8 0C durante 35 días. Fueron realizados dos tratamientos con alginato de sodio usando 0,3% y 0,5% y un tratamiento con carragenina 0,5%, después de la elaboración el jamón de cerdo cocido fue empacado al vacío a 8 0C durante 35 días. Los resultados indican que la mayor pérdida de agua fue observada a partir del día 21 del periodo de almacenamiento, sin presentar diferencias significativas entre tratamientos (P and gt;0,05). La menor pérdida de agua correspondió al tratamiento con alginato de sodio al 0,5% y la mayor pérdida fue para el tratamiento con carragenina al 0,5% (

The amino-terminal fragment of pro-brain natriuretic peptide in plasma as a biological marker for predicting mortality in community-acquired pneumonia: a cohort study

Abstract Aim: Community-acquired pneumonia (CAP) is an infectious disease that causes the highest mortality rates in developed countries. The primary endpoint of this study was to evaluate the relationship between the plasma concentration of the amino-terminal fragment of pro-brain natriuretic peptide (NT-ProBNP) at the time of CAP diagnosis in a hospital emergency room (HER) and its severity, determined as mortality at 30 days. Materials and Methods: A prospective, observational cohort study was used to determine NT-ProBNP (ng/L) in patients with CAP, with a follow-up over 30 days and analysis of the mortality rate. Results: A total of 338 patients were assessed. Thirty patients died within the first 30 days (10.5%). The mean NT-ProBNP values in the deceased patients were 14,035 ng/L (SD: 19,271) compared to 1,711 ng/L (SD: 3,835) in survivors (p<0.0001). The cut-off point of 1,769 ng/L showed a negative predictive value (NPV) of 95.3%, whereas 10,808 ng/L showed a positive predictive value (PPV) of 73.3%. The diagnostic performance of NT-ProBNP reached an AUC of 0.783 (95%CI: 0.731–0.829). Entering the potential confounding variables in a logistic regression model revealed that NT-ProBNP behaved like an independent risk factor. Grouping the NT-ProBNP values by every 300, 500, 1,000, and 2,000 ng/L increased the risk of mortality at 30 days by 3%, 5.1%, 10.5%, and 22%, respectively. Conclusion: The NT-ProBNP values at the time of CAP diagnosis are significantly higher among patients that die than those that survive the first 30 days, and it could be a good predictor of early mortality. NT-ProBNP has good overall accuracy and behaves like an independent risk factor. (Eurasian J Emerg Med 2016; 15: 30-8

Detection and elimination of pulse train instabilities in broadband fibre lasers using dispersion scan

[EN]We use self-calibrating dispersion scan to experimentally detect and quantify the presence of pulse train instabilities in ultrashort laser pulse trains. We numerically test our approach against two different types of pulse instability, namely second-order phase fluctuations and random phase instability, where the introduction of an adequate metric enables univocally quantifying the amount of instability. The approach is experimentally demonstrated with a supercontinuum fibre laser, where we observe and identify pulse train instabilities due to nonlinear propagation effects under anomalous dispersion conditions in the photonic crystal fibre used for spectral broadening. By replacing the latter with an all-normal dispersion fibre, we effectively correct the pulse train instability and increase the bandwidth of the generated coherent spectrum. This is further confirmed by temporal compression and measurement of the output pulses down to 15 fs using dispersion scan.The authors acknowledge funding from the Junta de Castilla y León (SA287P18) and FEDER funds; Spanish Ministerio de Economía y Competitividad (MINECO) (FIS2017-87970-R, EQC2018-004117-P, DI-15-07461, PTQ-15-07708); European EUREKA program CDTI-INNO-20171026; CCDR-N via the project Nanotechnology-based functional solutions (NORTE-01-0145-FEDER-000019); Fundação para a Ciência e a Tecnologia (FCT), Portugal (grants ‘UltraGraf’ M-ERA-NET2/0002/2016, M-ERA-NET2/0004/2016, UID/NAN/50024/2013, PTDC/FIS-OTI/32213/2017); Network of Extreme Conditions Laboratories - NECL and CCDR-N (NORTE-07-0124-FEDER-000070, NORTE-01-0145-FEDER-022096); PT2020 (program 05/SI/2017 – SI I&DT Empresarial - DI, grant no. 33573; program 04/SI/2019 Projetos de I&D Industrial à Escala Europeia, grant no. 045932). BA acknowledges funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 798264

250-Year reconstruction of pollarding events reveals sharp management changes in Iberian ash woodlands

Producción CientíficaTree pollarding was a dominant management strategy of European forests for centuries creating open agroforestry landscapes with important cultural and environmental values. This traditional practice has been widely abandoned in last decades with a subsequent impact in terms of biodiversity and cultural loss. Central Spain hosts the largest and best-preserved area of pollarded narrow-leaved ash (Fraxinus angustifolia Vahl.) woodlands in Europe. The main aim of this research is to obtain rigorous historical records of pollarding frequency to get adequate information for traditional ash management. We used dendrochronological techniques to evaluate temporal changes of pollarding frequency and rotation length. We analysed the stand level synchrony and the effect of land property on pollarding activity from 322 trees growing in eight pollard stands in Central Spain. Pollarding events were unequivocally identified at tree level by a characteristic change in growth pattern. We identified 2426 tree-level pruning events with the first event dated in 1777. Historical pruning recurrence ranged between 5 and 10 years with higher pollarding frequency on private lands. Pruning events within each site were synchronous, suggesting the existence of a rotational schema within each stand. Pruning frequency decreased drastically in the 1970s matching with the depopulation of rural areas and the general abandonment of traditional practices. Pollarding practices have recovered in recent decades although with lower intensity and lacking the synchronic historical patterns. Providing technical and economic support to make this traditional activity profitably would have strong environmental revenue due the multiple ecosystem services provided by pollarded ashes.iuFOR Institute Unit of Excellence" of the University of Valladolid, funded by the Junta de Castilla y León and co-financed by the European Union (ERDF "Europe drives our growth") project (CLU-2019-01)Ministerio de Ciencia e Innovación y Agencia Estatal de Investigación - MCIN/AEI/10.13039/501100011033 project PROWARM (PID2020-118444GA-100),(IJC2019-040571-I),(grant PRE2018-084106)Junta de Castilla y León, projects, (VA171P20) and (IR2020-1-UVA08)Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL