Modes of wall induced granular crystallisation in vibrational packing

Granular crystallisation is an important phenomenon whereby ordered packing structures form in granular matter under vibration. However, compared with the well-developed principles of crystallisation at the atomic scale, crystallisation in granular matter remains relatively poorly understood. To investigate this behaviour further and bridge the fields of granular matter and materials science, we simulated mono-disperse spheres confined in cylindrical containers to study their structural dynamics during vibration. By applying adequate vibration, disorder-to-order transitions were induced. Such transitions were characterised at the particle scale through bond orientation order parameters. As a result, emergent crystallisation was indicated by the enhancement of the local order of individual particles and the number of ordered particles. The observed heterogeneous crystallisation was characterised by the evolution of the spatial distributions via coarse-graining the order index. Crystalline regimes epitaxially grew from templates formed near the container walls during vibration, here termed the wall effect. By varying the geometrical dimensions of cylindrical containers, the obtained crystallised structures were found to differ at the cylindrical wall zone and the planar bottom wall zone. The formed packing structures were quantitatively compared to X-ray tomography results using again these order parameters. The findings here provide a microscopic perspective for developing laws governing structural dynamics in granular matter

Multiplicity results for a class of asymptotically linear elliptic problems with resonance and applications to problems with measure data

Abstract We study existence and multiplicity results for solutions of elliptic problems of the type -Δu = g(x; u) in a bounded domain Ω with Dirichlet boundary conditions. The function g(x; s) is asymptotically linear as |s| → +∞. Also resonant situations are allowed. We also prove some perturbation results for Dirichlet problems of the type -Δu = gƐ(x, u) where gε(x, s) → g(x, s) as ε → 0. The previous results find an application in the study of Dirichlet problems of the type -Δu = g(x, u)+μ where μ is a Radon measure. To properly set the above mentioned problems in a variational framework we also study existence and properties of critical points of a class of abstract nonsmooth functional defined on Banach spaces and extend to this nonsmooth framework some classical linking theorems

ALMA Observations of Elias 2-24: A Protoplanetary Disk with Multiple Gaps in the Ophiuchus Molecular Cloud

We present ALMA 1.3 mm continuum observations at 0."2 (25 au) resolution of Elias 2-24, one of the largest andbrightest protoplanetary disks in the Ophiuchus Molecular Cloud, and we report the presence of three partiallyresolved concentric gaps located at ∼20, 52, and 87 au from the star. We perform radiative transfer modeling of thedisk to constrain its surface density and temperature radial profile and place the disk structure in the context ofmechanisms capable of forming narrow gaps such as condensation fronts and dynamical clearing by activelyforming planets. In particular, we estimate the disk temperature at the locations of the gaps to be 23, 15, and 12 K(at 20, 52, and 87 au, respectively), very close to the expected snowlines of CO (23-28 K) and N2 (12-15 K).Similarly, by assuming that the widths of the gaps correspond to 4-8x the Hill radii of forming planets (assuggested by numerical simulations), we estimate planet masses in the range of 0.2-1.5 MJup, 1.0-8.0 MJup, and 0.02-0.15 MJup for the inner, middle, and outer gap, respectively. Given the surface density profile of the disk, theamount of missing mass at the location of each one of these gaps (between 4 and 20 MJup) is more than sufficientto account for the formation of such planets.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Circulating anti-galectin-1 antibodies are associated with the severity of ocular disease in autoimmune and infectious uveitis

Galectin (Gal)-1, an endogenous lectin found at sites of immune privilege, plays a critical role in the regulation of the immune response. Therapeutic administration of Gal-1 or its genetic delivery suppresses chronic inflammation in experimental models of autoimmunity. The purpose of this work was to investigate the occurrence of circulating anti-Gal-1 antibodies in patients with autoimmune and infectious uveitis as potential determinant factors of disease progression.Fil: Romero, Marta D.. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Fundación Ver; Argentina. Laboratorio Inmunopatología Investigación y Docencia LIIDO; ArgentinaFil: Muiño, Juan Carlos. Universidad Nacional de Córdoba; Argentina. Fundación Ver; ArgentinaFil: Bianco, German Ariel. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Ferrero, Mercedes. Laboratorio Inmunopatología Investigación y Docencia LIIDO; Argentina. Fundación Ver; ArgentinaFil: Juarez, Claudio P.. Fundación Ver; ArgentinaFil: Luna, José Domingo. Fundación Ver; ArgentinaFil: Rabinovich, Gabriel A.. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentin

A finite element approach to x-ray optics design

Volume: 10236 Host publication title: SPIE Proceedings Host publication sub-title: Damage to VUV, EUV, and X-ray Optics VI Isbn(print): 9781510609730-Non peer reviewe

A finite-element approach to dynamical diffraction problems in reflection geometry

A finite-element approach to the numerical solution of the Takagi-Taupin equations expressed in a weak form is presented and applied to simulate the X-ray reflectivity curves, spatial intensity distributions and focusing properties of bent perfect crystals in symmetric reflection geometry. The proposed framework encompasses a new formulation of the Takagi-Taupin equations, which appears to be promising in terms of robustness and stability and supports the Fresnel propagation of the diffracted waves. The presented method is very flexible and has the potential of dealing with dynamical X-ray or neutron diffraction problems related to crystals of arbitrary shape and deformation. The reference implementation based on the commercial COMSOL Multiphysics software package is available to the relevant user community.Peer reviewe

Cut-off points for isometric handgrip and low limb explosive strength in relation to indicators of overweight/obesity in people with intellectual disabilities: analysis by age groups

Background The prevalence of overweight/obesity has been increasing globally and in people with Intellectual Disabilities (IDs), this problem is exacerbated even more, which added to a low physical condition that contributes to the deterioration of functionality and increases the risk of developing chronic diseases in the course of life. Therefore, the aim of this study was to establish cut-off points for levels of isometric handgrip and low limb explosive strength in children, adolescents and adults, which identify overweight/obesity in people with IDs and their respective associations. Methods The sample was made up of 131 individuals with IDs, belonging to four special and community educational centres in the city of Santiago, Chile. Body mass index (BMI) and waist-to-height ratio (WHR) were used as indicators of overweight/obesity. Handgrip strength was used as a measure of isometric strength, and countermovement jump was used as a measure of low limb explosive strength. For the comparison of variables by age group, the analysis of Ancova, Kruskal–Wallis and chi-square tests were used. The total area under the receiver operating characteristic curve of isometric handgrip and low limb explosive strength was identified as an indicator of overweight/obesity according to age groups. A logistic regression model was used to quantify the effect that strength categories below the cut-off point have on the risk of overweight and obesity. Results Significant differences were observed between the age groups for body weight, height, BMI and WHR, as well as in the levels of absolute handgrip strength and vertical jump with countermovement (P ≤ 0.05). Children showed the lowest cut-off points for absolute and relative strength. The adolescent group showed the highest cut-off points for relative strength and countermovement jump and adults showed the highest value for absolute strength as indicators of overweight/obesity. Different associations between cut-off points with BMI and WHR were found. Conclusions Adolescents showed the highest cut-off point for relative strength and countermovement jump, and adults showed the highest value for absolute strength, according to overweight/obesity indicators (BMI and WHR). It is suggested to adjust resistance training programmes according to age categories for the prevention of overweight/obesity in people with IDs.Universidad de Granada/CBU

Modes de cristallisation granulaire induite par la paroi dans un compactage vibratoire

International audienceGranular crystallisation is an important phenomenon whereby ordered packing structures form in granular matter under vibration. However, compared with the well-developed principles of crystallisation at the atomic scale, crystallisation in granular matter remains relatively poorly understood. To investigate this behaviour further and bridge the fields of granular matter and materials science, we simulated mono-disperse spheres confined in cylindrical containers to study their structural dynamics during vibration. By applying adequate vibration, disorder-to-order transitions were induced. Such transitions were characterised at the particle scale through bond orientation order parameters. As a result, emergent crystallisation was indicated by the enhancement of the local order of individual particles and the number of ordered particles. The observed heterogeneous crystallisation was characterised by the evolution of the spatial distributions via coarse-graining the order index. Crystalline regimes epitaxially grew from templates formed near the container walls during vibration, here termed the wall effect. By varying the geometrical dimensions of cylindrical containers, the obtained crystallised structures were found to differ at the cylindrical wall zone and the planar bottom wall zone. The formed packing structures were quantitatively compared to X-ray tomography results using again these order parameters. The findings here provide a microscopic perspective for developing laws governing structural dynamics in granular matter.https://doi.org/10.1007/s10035-019-0876-8La cristallisation granulaire est un phénomène important dans lequel des structures de garnissage ordonnées se forment dans une matière granulaire sous vibration. Cependant, comparée aux principes bien développés de la cristallisation à l'échelle atomique, la cristallisation dans la matière granulaire reste relativement mal comprise. Pour étudier plus avant ce comportement et relier les domaines de la matière granulaire et de la science des matériaux, nous avons simulé des sphères mono-dispersées confinées dans des conteneurs cylindriques afin d'étudier leur dynamique structurelle lors de la vibration. En appliquant une vibration adéquate, des transitions désordre à ordre ont été induites. Ces transitions ont été caractérisées à l'échelle des particules par le biais de paramètres d'ordre d'orientation de liaison. En conséquence, la cristallisation émergente était indiquée par l'amélioration de l'ordre local des particules individuelles et du nombre de particules ordonnées. La cristallisation hétérogène observée a été caractérisée par l'évolution des distributions spatiales via la granulation grossière de l'indice d'ordre. Les régimes cristallins se développaient par épitaxie à partir de gabarits formés près des parois du conteneur lors de vibrations, appelé ici effet de paroi. En faisant varier les dimensions géométriques des récipients cylindriques, il s'est avéré que les structures cristallisées obtenues différaient au niveau de la zone de paroi cylindrique et de la zone de paroi de fond plane. Les structures de garnissage formées ont été comparées quantitativement aux résultats de tomographie à rayons X en utilisant à nouveau ces paramètres d'ordre. Les résultats présentés ici fournissent une perspective microscopique pour l'élaboration de lois régissant la dynamique structurelle dans la matière granulaire.https://doi.org/10.1007/s10035-019-0876-

Consideration of the mechanical damage behavior of rock salt during calculation of infiltration-cracks in the edge zone of gas storage caverns

Underground storage in salt caverns is a preferred method for the intermediate storage of natural gas to cover seasonal fluctuation in consumption and commercial gas storage. The prove of the stability and tightness of the storage required for safe operation is continuously adapted to the current state of the art. For many years, an intensive scientific investigation has been carried out within the frame-work of repository research with continuous optimization of the rock mechanical modelling of the material behavior of rock salt. From the elaboration of the research results on the pressure-driven infiltration processes into the primarily non-permeable salt rock, it emerges that during gas storage operation, in addition to the areal infiltration, the formation of macroscopic infiltration-cracks in the cavern surrounding salt rock is to be expected as well. This thesis deals with the computational simulation of macroscopic infiltration-cracks within the scope of theoretical modelling of salt cavern behavior during gas storage, taking into account additional mechanical damage processes in the rock salt. On the basis of variational calculus, the infiltration fracture propagation will be evaluated, considering different model approaches in material behavior of the cavern surrounding rock salt mass. As a result of the present work, it should be noted that with regard to the propagation of infiltration-cracks in gas caverns, constitutive model approaches for the description of the mechanical damage and healing behavior of rock salt can be neglected for a conservative assessment