Prismas generados por fracturas en experimentos con fécula

We present a didactic experiment of desiccation using starch-water mixture. The aim is to obtain prismatic joints similar to columns in basalt lava flows, or the desiccation fractures in sediments. Two types of joints were observed in experiments: a) the first formed joints are large, crossing completely the container used in the experiment. The intersection angles among the large joints are about 90°; b) The second joints are smaller; they develop after the large ones forming intersection angles from 90° to 140°. Both large and small joints have dips near 90° with respect the dissection surface. Using Voronoi diagrams we explained patterns which resemble the prismatic joints obtained in the experiment.Presentamos un experimento didáctico de desecación de fécula. El objetivo es obtener patrones prismáticos de fracturas, similares a los que se forman en derrames de basalto, o a las grietas de desecación en sedimentos. Se observaron dos tipos de fracturas en el experimento: a) las primeras que se formaron son grandes, cruzan completamente el contenedor utilizado en el experimento. Dichas fracturas se cruzan con ángulos muy cercanos a 90°. b) Las segundas fracturas que se forman son más pequeñas, se desarrollan después de formadas las grandes y presentan ángulos de intersección de entre 90° y 140°. Tanto las facturas grandes como las pequeñas tienen inclinaciones cercanas a 90° con respecto a la superficie de desecación. Se muestra como utilizando diagramas de Voronoi se puede obtener patrones semejantes a los arreglos de las fracturas del experimento.Palabras clave: Fracturas de desecación; Prismas columnares; Experimento de desecación; Diagramas de Voronoi.Prisms generated by joints in experiments of water-starch mixtureWe present a didactic experiment of desiccation using starch-water mixture. The aim is to obtain prismatic joints similar to columns in basalt lava flows, or the desiccation fractures in sediments. Two types of joints were observed in experiments: a) the first formed joints are large, crossing completely the container used in the experiment. The intersection angles among the large joints are about 90°; b) The second joints are smaller; they develop after the large ones forming intersection angles from 90° to 140°. Both large and small joints have dips near 90° with respect the dissection surface. Using Voronoi diagrams we explained patterns which resemble the prismatic joints obtained in the experiment.Keywords: Desiccation fractures; Basaltic prisms; Desiccation experiment; Voronoi diagrams

Prisms generated by joints in experiments of water-starch mixture

Presentamos un experimento didáctico de desecación de fécula. El objetivo es obtener patrones prismáticos de fracturas, similares a los que se forman en derrames de basalto, o a las grietas de desecación en sedimentos. Se observaron dos tipos de fracturas en el experimento: a) las primeras que se formaron son grandes, cruzan completamente el contenedor utilizado en el experimento. Dichas fracturas se cruzan con ángulos muy cercanos a 90°. b) Las segundas fracturas que se forman son más pequeñas, se desarrollan después de formadas las grandes y presentan ángulos de intersección de entre 90° y 140°. Tanto las facturas grandes como las pequeñas tienen inclinaciones cercanas a 90° con respecto a la superficie de desecación. Se muestra cómo utilizando diagramas de Voronoi se puede obtener patrones semejantes a los arreglos de las fracturas del experimento.We present a didactic experiment of desiccation using starch-water mixture. The aim is to obtain prismatic joints similar to columns in basalt lava flows, or the desiccation fractures in sediments. Two types of joints were observed in experiments: a) the first formed joints are large, crossing completely the container used in the experiment. The intersection angles among the large joints are about 90°; b) The second joints are smaller; they develop after the large ones forming intersection angles from 90° to 140°. Both large and small joints have dips near 90° with respect the dissection surface. Using Voronoi diagrams we explained patterns which resemble the prismatic joints obtained in the experiment.5 página

Deep-sequencing reveals broad subtype-specific HCV resistance mutations associated with treatment failure.

A percentage of hepatitis C virus (HCV)-infected patients fail direct acting antiviral (DAA)-based treatment regimens, often because of drug resistance-associated substitutions (RAS). The aim of this study was to characterize the resistance profile of a large cohort of patients failing DAA-based treatments, and investigate the relationship between HCV subtype and failure, as an aid to optimizing management of these patients. A new, standardized HCV-RAS testing protocol based on deep sequencing was designed and applied to 220 previously subtyped samples from patients failing DAA treatment, collected in 39 Spanish hospitals. The majority had received DAA-based interferon (IFN) α-free regimens; 79% had failed sofosbuvir-containing therapy. Genomic regions encoding the nonstructural protein (NS) 3, NS5A, and NS5B (DAA target regions) were analyzed using subtype-specific primers. Viral subtype distribution was as follows: genotype (G) 1, 62.7%; G3a, 21.4%; G4d, 12.3%; G2, 1.8%; and mixed infections 1.8%. Overall, 88.6% of patients carried at least 1 RAS, and 19% carried RAS at frequencies below 20% in the mutant spectrum. There were no differences in RAS selection between treatments with and without ribavirin. Regardless of the treatment received, each HCV subtype showed specific types of RAS. Of note, no RAS were detected in the target proteins of 18.6% of patients failing treatment, and 30.4% of patients had RAS in proteins that were not targets of the inhibitors they received. HCV patients failing DAA therapy showed a high diversity of RAS. Ribavirin use did not influence the type or number of RAS at failure. The subtype-specific pattern of RAS emergence underscores the importance of accurate HCV subtyping. The frequency of "extra-target" RAS suggests the need for RAS screening in all three DAA target regions