Slow relaxation dynamics of clogs in a vibrated granular silo

We experimentally explore the vibration-induced unclogging of arches halting the flow in a two-dimensional silo. The endurance of arches is determined by carrying out a survival analysis of their breaking times. By analyzing the dynamics of two morphological variables, we demonstrate that arches evolve toward less regular structures and it seems that there may exist a certain degree of irregularity that the arch reaches before collapsing. Moreover, we put forward that σ (the standard deviation of all angles between consecutive beads) describes faithfully the morphological evolution of the arch. Focusing on long-lasting arches, we study σ calculating its two-time autocorrelation function and its mean-squared displacement. In particular, the apparent logarithmic increase of the correlation and the decrease of the mean-squared displacement of σ when the waiting time is increased reveal a slowing down of the dynamics. This behavior is a clear hallmark of aging phenomena and confirms the lack of ergodicity in the unclogging dynamics. Our findings provide new insights on how an arch tends to destabilize and how the probability that it breaks with a long sustained vibration decreases with time.Fil: Guerrero Borges, Veronica. Universidad de Navarra; EspañaFil: Pugnaloni, Luis Ariel. Universidad Tecnológica Nacional. Facultad Regional La Plata. Departamento de Ingeniería Mecánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Lozano, C.. Universitat Konstanz; AlemaniaFil: Zuriguel, I.. Universidad de Navarra; EspañaFil: Garcimartín, A.. Universidad de Navarra; Españ

Spin-label EPR study in thylakoid membranes from a new herbicide-resistant D1 mutant from soybean cell cultures deficient in fatty acid desaturation

El pdf del artículo es la versión post-print.Fatty acid desaturation effect on the lipid fluidity in thylakoid membranes isolated from the STR7 mutant was investigated by electron paramagnetic resonance (EPR) using spin label probes. The spectra of both 5- and 16-n-doxylstearic acid probes were measured as a function of the temperature between 10-305 K and compared to those of the wild type. This complete thermal evolution provides a wider picture of the dynamics. The spectra of the 5-n-doxylstearic acid probe were identical in both STR7 mutant and wild type thylakoids as well as their temperature evolution. However, differences were found with the 16-n-doxylstearic acid probe at temperatures between 230-305 K. The differences in the thermal evolution of the EPR spectra can be interpreted as a 5-10 K shift toward higher temperatures of the probe motional rates in the STR7 mutant as compared with that in the wild type. At temperatures below 230 K no differences were observed. The results indicated that the lipid motion in the outermost region of the thylakoids is the same in the STR7 mutant than in the wild type while the fluidity in the inner region of the STR7 mutant membrane decreases. Our data point out a picture of the STR7 thylakoid membrane in which the lipid motion is slower most probably as a consequence of fatty acid desaturation deficiency.M.A. and I.G.-R. were recipients of a contract and a fellowship, respectively, from the Ministerio de Educación y Cultura of Spain. This work was supported by the Dirección General de Investigación Científica y Técnica (Grant PB98-1632) and by the Diputación General de Aragón (Project P17/98).Peer reviewe

Rendimiento diagnóstico de repetir la biopsia guiada por ultrasonido endoscópico después de una primera biopsia negativa en pacientes con lesiones no pancreáticas

ResumenIntroducciónEl ultrasonido endoscópico has sido un método útil para la evaluación de la enfermedad pancreatobiliar por más de una década, sin embargo no es un escenario raro el encontrar resultados patológicos no concluyentes en el tejido obtenido para el diagnóstico. Entre los factores que alteran el rendimiento diagnóstico se encuentran la experiencia del endosonografista, el volumen de procedimientos realizados, el tipo, el tamaño y la localización, entre otros. El objetivo del presente estudio fue evaluar el rendimiento diagnóstico de la segunda USE-BAAF en las lesiones no pancreáticas.Material y métodosSe realizó un estudio retrospectivo y transversal. Se incluyeron pacientes >18 años a los que se les realizó USE-BAAF durante el periodo de 8 años.ResultadosSe realizaron 150 procedimientos en 132 pacientes con lesiones no pancreáticas. Finalmente, el diagnóstico se logró por USE-BAAF en 114/132 pacientes, para un rendimiento diagnóstico global de 86.63%. En total, la mediana (intervalo mínimo-máximo) de biopsias fue de 1 (1-5). El rendimiento diagnóstico de la primera USE-BAAF fue de 77.3% (102/132). Se realizó una segunda biopsia en 16/132 (12.1%) pacientes. Con la segunda USE-BAAF se observó un aumento del rendimiento global a 113/132 pacientes (11/16=68.7%; global 85.6%). No se observaron complicaciones.ConclusiónEl repetir la USE-BAAF en lesiones no pancreáticas es necesario en pacientes con una primera negativa USE-BAAF, ya que mejora el rendimiento diagnóstico.AbstractIntroductionEndoscopic ultrasound has been a useful method for the evaluation of pancreatobiliary pathology for more than a decade, however it is not unusual to find inconclusive pathological results in tissue obtained for diagnosis. The factors affecting diagnostic performance include; endosonographist experience, the volume of procedures performed, type, size and location, amongst others. The aim of this study was to evaluate the diagnostic performance of the second EUS-FNA in non-pancreatic lesions.Material and methodsA retrospective cross-sectional study that includedpatients>18 years who underwent EUS-FNA over a period of 8 years.Results150 procedures were performed in 132 patients with non-pancreatic lesions. Finally, the diagnosis was obtained by EUS-FNA in 114/132 patients for a diagnostic yield of 86.6%. In total, the biopsy median (minimum/maximum interval) was 1 (1-5). The diagnostic yield of the first EUS-FNA was 77.3% (102/132). With the second EUS-FNA 11/16 patients had a histological diagnosis (11/16=68.7%; global 85.6%). No complications were reported.ConclusionRepeat EUS-FNA in patients with non-pancreatic lesions is necessary in patients with a first negative EUS-FNA because it improves the diagnostic yield

Dynamics of breaking arches under a constant vibration

Granular flow through an orifice can be suddenly halted by the formation of arches in the vicinity of the outlet, which are stable under the action of gravity. They may be broken when an external driving (for instance, vibration) is applied. With the aim of shedding light on the dynamics of arch destruction, we built an experiment consisting of a vertical two-dimensional silo filled with monodisperse beads, to which a constant vibration is applied. It was previously found that an important parameter to predict the robustness of the arch is the angle between consecutive beads. We focus on long-enduring arches and study the angles among the beads along time. We have found that in many cases the dynamics of the largest angle determines the breaking of the arch; it does not only determine where the ¿weakest link¿ is, but also the process that leads to the final destabilization. This is interesting because it can provide information about whether the flow will resume in a well-defined time or not, which is especially useful for industrial processes that have to constantly deal with the possible emergence of clogs

Sociologia de l’Activitat Física, l’Educació Física i l’Esport. L’estudi de casos una eina útil per a la docència i la recerca.

Aquesta publicació és fruit de l’experiència desenvolupada durant el curs 2015-16 en el marc del Màster d’Activitat Física i Educació en l’assignatura de Sociologia de l’Activitat Física, l’Educació Física i l’Esport. El present treball parteix de l’interès de l’alumnat sobre la seva realitat laboral i professional i es pretén aconseguir tres tipus d’objectius tal com recull Yin (2003) : a) un exploratori, és a dir, que els resultats obtinguts serveixin de base per formular preguntes d’investigació, ja que l’alumnat es troba immers en el desenvolupament del seu treball final de màster; b) un descriptiu doncs l’alumnat es proposa descriure el que passa en un cas particular; c) un explicatiu que facilita la interpretació de la realitat en la qual viuen professionalment i la comparteixen amb el grup. Els nou casos que es proposen són de gran interès i actualitat especialment pel que fa a la docència i la recerca en el camp de l’educació física i esportiva

Alimentación de los lenguados Cyclopsetta querna y Syacium latifrons en la costa de Jalisco y Colima, México

Flatfish are important components of shrimp fisheries bycatch. The purpose of this study was to analyze feeding habits of Cyclopsetta querna and Syacium latifrons, with the aim of expanding the biological knowledge of these species. Specimens were collected in seven sampling stations with shrimp trawl nets. Stomachs of 196 individuals of C. querna and 313 of S. latifrons were analyzed. The trophic spectrum of C. querna consisted of 12 food components, while 24 were recorded for S. latifrons. The main prey for C. querna were fish, while for S. latifrons it was crustaceans, such as stomatopods. A slight ontogenetic trophic variation was observed in C. querna, not so in S. latifrons; however, no differences were observed considering only the diet by sex. Diversity analyses of the food spectrum were less than 0.5 for both species. It is considered that in both species feeding is given mainly by the seasonal availability of resources and by the ability to capture prey. On the other hand, the coexistence of these species in the same area is due to the difference in the preferential consumption of prey hence reducing the competition for food.Los lenguados forman un componente importante como fauna de acompañamiento del camarón. El objetivo del presente trabajo consistió en analizar la alimentación de Cyclopseta querna y Syacium latifrons, con el fin de ampliar el conocimiento biológico de estas especies. Los ejemplares se colectaron en siete estaciones de muestreo con redes de arrastre de camarón. Se analizaron los estómagos de 196 individuos de C. querna y 313 de S. latifrons. El espectro trófico de C. querna estuvo constituido por 12 componentes alimentarios, mientras que para S. latifrons se registraron 24. Las presas principales de C. querna fueron los peces, mientras que para S. latifrons fueron los crustáceos, como por ejemplo, estomatópodos. Se observó una ligera variación ontogénica en la dieta de C. querna, no así en S. latifrons; sin embargo, en la dieta por sexos no se observaron diferencias. Los análisis de diversidad del espectro alimentario fueron menores de 0,5 para ambas especies. Se considera que en ambas especies la alimentación se da principalmente por la disponibilidad de recursos en las estaciones del año y por la capacidad de captura de presas. Por otra parte, la coexistencia de estas especies en una misma zona se da por diferencias en el consumo preferencial de sus presas al disminuir la competencia por alimento

Slow relaxation dynamics of clogs in a vibrated granular silo

We experimentally explore the vibration-induced unclogging of arches halting the flow in a two-dimensional silo. The endurance of arches is determined by carrying out a survival analysis of their breaking times. By analyzing the dynamics of two morphological variables, we demonstrate that arches evolve toward less regular structures and it seems that there may exist a certain degree of irregularity that the arch reaches before collapsing. Moreover, we put forward that ¿ (the standard deviation of all angles between consecutive beads) describes faithfully the morphological evolution of the arch. Focusing on long-lasting arches, we study ¿ calculating its two-time autocorrelation function and its mean-squared displacement. In particular, the apparent logarithmic increase of the correlation and the decrease of the mean-squared displacement of ¿ when the waiting time is increased reveal a slowing down of the dynamics. This behavior is a clear hallmark of aging phenomena and confirms the lack of ergodicity in the unclogging dynamics. Our findings provide new insights on how an arch tends to destabilize and how the probability that it breaks with a long sustained vibration decreases with time