Prediction of the shear strength of reinforced masonry walls using a large experimental database and artificial neural networks

This paper analyses the accuracy of a selection of expressions currently available to estimate the in-plane shear strength of reinforced masonry (RM) walls, including those presented in some international masonry codes. For this purpose, predictions of such expressions are compared with a set of xperimental results reported in the literature. The experimental database includes specimens built with ceramic bricks and concrete blocks tested in partially and fully grouted conditions, which typically present a shear failure mode. Based on the experimental data collected and using artificial neural networks (ANN), this paper presents alternative expressions to the different existing methods to predict the in-plane shear strength of RM walls. The wall aspect ratio, the axial pre-compression level on the wall, the compressive strength of masonry, as well as the amount and spacing of vertical and horizontal reinforcement throughout the wall are taken into consideration as the input parameters for the proposed expressions. The results obtained show that ANN-based proposals give good predictions and in general fit the experimental results better than other calculation methods.This work was supported by the Fondo Nacional de Ciencia y Tecnologia de Chile, (Fondecyt de Iniciacion) [grant number 11121161].Aguilar, V.; Sandoval, C.; Adam Martínez, JM.; Garzón-Roca, J.; Valdebenito, G. (2016). Prediction of the shear strength of reinforced masonry walls using a large experimental database and artificial neural networks. Structure and Infrastructure Engineering. 12(12):1661-1674. https://doi.org/10.1080/15732479.2016.1157824S16611674121

Contuciones en canales bovinas. Incidencia y riesgo potencial

A study done in the main slaughterhouse of Santiago (Chile) showed that from 4517 bovine carcasses, 9.3 % had con tusions. The con tusions were classified accordíng to their intensíty, in grade 1,2 and 3 (53.6 %, 46.0% and 0.7 % respectively). The 59.1 % of the contusions occurred in first grade meats, and the 40.9 % in second grade meats. The occurrence of the contusions showed a significant association (P < 0.05) wíth the distance of transportation of the living animals. The Standard Plate Count (viable aerobic mesophiles) showed significant dífferences between samples taken during slaughter and one hour after. Heifers, oxen, cows, steers and bulls, were decreasingly affected. The necessity to establish rules and reguladoras ora living animal transport is emphasízed.Un estudio realizado en el principal Matadero-Frigor&iacute;fico de Santiago (Chile) demostr&oacute; que de 4.517 canales bovinas un 9,3%, de ellas presentaba contusiones. Seg&uacute;n su intensidad un 53%, 46,0% y 0,7% fueron de grados 1, 2 y 3 respectivamente. Un 59,1% de las contusiones se registraron en carnes calificadas de primera y un 40,9 % en carnes de segunda. La presencia de contusiones muestra una asociaci&oacute;n significativa (p &lt; 0,05) con la distancia de transporte del ganado vivo. En el recuento de g&eacute;rmenes aerobios mes&oacute;filos viables se observa diferencias significativas entre muestras tomadas en el momento del beneficio y luego de una hora de haber ocurrido &eacute;ste. Al considerar la categor&iacute;a del bovino, son afectados en orden decreciente, las vaquillas, bueyes, vacas, novillos y toros. Se hace presente la necesidad de reglamentar el transporte del ganado vivo

Protocolo local de indicaciones quirúrgicas en lesiones por presión

No abstract availabl

Rapid turnover of a pea aphid superclone mediated by thermal endurance in central Chile

International audienceGlobal change drivers are imposing novel conditions on Earth’s ecosystems at an unprecedented rate. Among them, biological invasions and climate change are of critical concern. It is generally thought that strictly asexual populations will be more susceptible to rapid environmental alterations due to their lack of genetic variability and, thus, of adaptive responses. In this study, we evaluated the persistence of a widely distributed asexual lineage of the alfalfa race of the pea aphid, Acyrthosiphon pisum, along a latitudinal transect of approximately 600 km in central Chile after facing environmental change for a decade. Based on microsatellite markers, we found an almost total replacement of the original aphid superclone by a new variant. Considering the unprecedented warming that this region has experienced in recent years, we experimentally evaluated the reproductive performance of these two A. pisum lineages at different thermal regimes. The new variant exhibits higher rates of population increase at warmer temperatures, and computer simulations employing a representative temperature dataset suggest that it might competitively displace the original superclone. These results support the idea of a superclone turnover mediated by differential reproductive performance under changing temperatures