Comment on "Tricritical Behavior in Rupture Induced by Disorder"

In their letter, Andersen, Sornette, and Leung [Phys. Rev. Lett. 78, 2140 (1997)] describe possible behaviors for rupture in disordered media, based on the mean field-like democratic fiber bundle model. In this model, fibers are pulled with a force which is distributed uniformly. A fiber breaks if the stress on it exceeds a threshold chosen from a probability distribution, and the force is then redistributed over the intact fibers. Andersen et al. claim the existence of a tricritical point, separating a "first-order" regime, characterized by a sudden global failure, from a "second-order" regime, characterized by a divergence in the breaking rate. We show that a first-order transition is an artifact of a (large enough) discontinuity put by hand in the disorder distribution. Thus, in generic physical cases, a first-order regime is not present. This result is obtained from a graphical method, which, unlike Andersen at al.'s analytical solution, enables us to distinguish the various classes of qualitatively different behaviors of the model.Comment: 1 page, 1 figure included, revte

Structural Flyby Characterization of Nanoporosity

Recently, Ferreira da Silva et al. [3] have performed a gradient pattern analysis of a canonical sample set (CSS) of scanning force microscopy (SFM) images of p-Si. They applied the so-called Gradient Pattern Analysis to images of three typical p-Si samples distinguished by different absorption energy levels and aspect ratios. Taking into account the measures of spatial asymmetric fluctuations they interpreted the global porosity not only in terms of the amount of roughness, but rather in terms of the structural complexity (e.g., walls and fine structures as slots). This analysis has been adapted in order to operate in a OpenGL flyby environment (the StrFB code), whose application give the numerical characterization of the structure during the flyby real time. Using this analysis we compare the levels of asymmetric fragmentation of active porosity related to different materials as p-Si and "porous diamond-like" carbon. In summary we have shown that the gradient pattern analysis technique in a flyby environment is a reliable sensitive method to investigate, qualitatively and quantitatively, the complex morphology of active nanostructures

The Core Mass Function in the Massive Protocluster G286.21+0.17 revealed by ALMA

We study the core mass function (CMF) of the massive protocluster G286.21+0.17 with the Atacama Large Millimeter/submillimeter Array via 1.3~mm continuum emission at a resolution of 1.0\arcsec\ (2500~au). We have mapped a field of 5.3\arcmin$\times$5.3\arcmin\ centered on the protocluster clump. We measure the CMF in the central region, exploring various core detection algorithms, which give source numbers ranging from 60 to 125, depending on parameter selection. We estimate completeness corrections due to imperfect flux recovery and core identification via artificial core insertion experiments. For masses $M\gtrsim1\:M_\odot$, the fiducial dendrogram-identified CMF can be fit with a power law of the form ${\rm{d}}N/{\rm{d}}{\rm{log}}M\propto{M}^{-\alpha}$ with $\alpha \simeq1.24\pm0.17$, slightly shallower than, but still consistent with, the index of the Salpeter stellar initial mass function of 1.35. Clumpfind-identified CMFs are significantly shallower with $\alpha\simeq0.64\pm0.13$. While raw CMFs show a peak near $1\:M_\odot$, completeness-corrected CMFs are consistent with a single power law extending down to $\sim 0.5\:M_\odot$, with only a tentative indication of a shallowing of the slope around $\sim1\:M_\odot$. We discuss the implications of these results for star and star cluster formation theories.Comment: 11 pages, accepted by Ap

Bayesian inference in threshold models using Gibbs sampling

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Replik til HB et al: Sprogpolitik: So ein Ding müssen wir auch haben. So ein Ding haben wir schon seit einem Jahr

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A cell-based smoothed finite element method for kinematic limit analysis

This paper presents a new numerical procedure for kinematic limit analysis problems, which incorporates the cell-based smoothed finite element method with second-order cone programming. The application of a strain smoothing technique to the standard displacement finite element both rules out volumetric locking and also results in an efficient method that can provide accurate solutions with minimal computational effort. The non-smooth optimization problem is formulated as a problem of minimizing a sum of Euclidean norms, ensuring that the resulting optimization problem can be solved by an efficient second-order cone programming algorithm. Plane stress and plane strain problems governed by the von Mises criterion are considered, but extensions to problems with other yield criteria having a similar conic quadratic form or 3D problems can be envisaged

Profesionales de salud y violencia intrafamiliar contra el niño y el adolescente

OBJECTIVES: To understand how heath care professionals approach family violence against children and teenagers. METHODS: This was a qualitative case study with 30 health care professionals. RESULTS: Health care professionals were concerned with the lack of successful family problems resolution. Measures used by health care professionals emphasized punitive actions instead of caring behaviors. The characteristics of the job did not allow of the health care professionals to express their feelings and reactions and to know how to successfully address family violence. Health care professionals' approaches to address violence with families who already experienced violence may also become violent acts against those families. CONCLUSION: Approaches used to address family violence against children and teenagers reflect a lack of integration among the several categories of health care professionals and health care services.OBJETIVO: Comprender el modo cómo los profesionales de salud abordan las situaciones relacionadas a la violencia intrafamiliar contra el niño y el adolescente. MÉTODOS: Se trata de una investigación de naturaleza cualitativa, de tipo estudio de caso, realizado con 30 profesionales de salud. RESULTADOS: Los profesionales se mostraron preocupados con la falta de resolución de los problemas. Revelaron que las medidas emprendidas priorizan la punición en lugar de la atención y que la estructura de trabajo no les permitía exponer sus sentimientos y reacciones y lidiar con ellos. El modo de abordar a las familias que ya vivenciaron violencia puede configurar un acto violento para con éstas. CONCLUSIÓN: La manera cómo se realiza la mayoría de las abordajes en casos de violencia contra el niño y el adolescente refleja la falta de integración entre los profesionales y los diversos sectores.OBJETIVO: Compreender o modo como os profissionais de saúde abordam as situações envolvidas na violência intrafamiliar contra a criança e o adolescente. MÉTODOS: Pesquisa de natureza qualitativo, na modalidade de estudo de caso, realizado com 30 profissionais de saúde. RESULTADOS: Os profissionais mostraram-se preocupados com a falta de resolução dos problemas. Revelaram que as medidas empreendidas priorizam a punição em lugar do atendimento e que a estrutura de trabalho não lhes permitia expor seus sentimentos e reações e com eles lidar. O modo de abordar as famílias que já vivenciaram violência pode configurar um ato violento para com estas. CONCLUSÃO: A maneira como é realizada a maioria das abordagens em casos de violência contra a criança e o adolescente reflete a falta de integração entre os profissionais e os diversos setores.Universidade Federal de Mato Grosso do SulUniversidade Federal de São Paulo (UNIFESP)UNIFESPSciEL

Conceptions held by health professionals on violence against children and adolescents within the family

Este estudo buscou compreender as concepções que os profissionais de saúde têm sobre a violência intrafamiliar contra a criança e o adolescente. Foram utilizadas metodologia qualitativa na modalidade estudo de caso e técnicas de observação participante, entrevista e consulta em documentos. Os participantes eram membros de uma Unidade de Saúde da Família. Evidenciou-se que os profissionais de saúde associam a violência à conjuntura econômica, social e política e a aspectos culturais; para alguns, os atos violentos fazem parte do ciclo intergeracional e da dinâmica familiar. A punição física, considerada violência por uns, é defendida como medida educativa por outros. Definem violência com base em construção prévia dos sujeitos como vítimas ou agressores, perdendo-se, com isso, a dimensão relacional do fenômeno. Constata-se que os profissionais de saúde têm dificuldade para compreender a violência no contexto em que tem significado e para reconhecê-la como conseqüência de dinâmica relacional complexa.Este estudio buscó comprender las concepciones que los profesionales de la salud manifiestan sobre la violencia intrafamiliar contra niños y adolescentes. Fue utilizada la metodología cualitativa a través del estudio de caso y técnicas de observación participante, entrevista y consulta a documentos. Los participantes trabajaban en una Unidad de Salud de la Familia en Brasil. Se observó que estos profesionales asocian la violencia a la coyuntura económica, social, política y a aspectos culturales; para algunos de ellos, los actos violentos son parte del ciclo intergeneracional y de la dinámica familiar. La punición física, considerada violencia por algunos, es defendida por otros como una medida educativa. Definen violencia basándose en una construcción previa que tienen los sujetos como víctimas o agresores, perdiendo así la dimensión relacional del fenómeno. Se observa que los profesionales de la salud tienen dificultad para comprender la violencia dentro del contexto en que tiene significado, así como para reconocerla como una consecuencia de dinámica relacional compleja.The present study sought to understand the conceptions held by health professionals with regards to violence within the family against children and adolescents. Qualitative case-study methodology and techniques of participant observation, interviewing, and search in documents were used. Participants were staffed in a government-run Family Health Basic Unit in Brazil. Health professionals were found to associate violence with the economic, social, and political juncture and with cultural aspects; for some, violent acts are part of the intergenerational cycle and family dynamics. Physical punishment, considered as violence by some, is advocated as an educational measure by others. Participants also base their definition of violence on an a priori construction of subjects as either victims or aggressors, thus missing the relational dimension of the phenomenon. Health professionals were found to have difficulty in understanding violence in the context that gives it a meaning and to recognize it as consequence of a complex relational dynamics

Spatial differences between stars and brown dwarfs: a dynamical origin?

We use $N$-body simulations to compare the evolution of spatial distributions of stars and brown dwarfs in young star-forming regions. We use three different diagnostics; the ratio of stars to brown dwarfs as a function of distance from the region's centre, $\mathcal{R}_{\rm SSR}$, the local surface density of stars compared to brown dwarfs, $\Sigma_{\rm LDR}$, and we compare the global spatial distributions using the $\Lambda_{\rm MSR}$ method. From a suite of twenty initially statistically identical simulations, 6/20 attain $\mathcal{R}_{\rm SSR} << 1$ $and$ $\Sigma_{\rm LDR} << 1$ $and$ $\Lambda_{\rm MSR} << 1$, indicating that dynamical interactions could be responsible for observed differences in the spatial distributions of stars and brown dwarfs in star-forming regions. However, many simulations also display apparently contradictory results - for example, in some cases the brown dwarfs have much lower local densities than stars ($\Sigma_{\rm LDR} << 1$), but their global spatial distributions are indistinguishable ($\Lambda_{\rm MSR} = 1$) and the relative proportion of stars and brown dwarfs remains constant across the region ($\mathcal{R}_{\rm SSR} = 1$). Our results suggest that extreme caution should be exercised when interpreting any observed difference in the spatial distribution of stars and brown dwarfs, and that a much larger observational sample of regions/clusters (with complete mass functions) is necessary to investigate whether or not brown dwarfs form through similar mechanisms to stars.Comment: 7 pages, 5 figures, accepted for publication in MNRA