Advanced architectural descriptors in foams: novel 3D computational methods

This work presents 3D computational strategies aimed at providing foam de-structuration of the basic components of a cellular material (struts and cell walls) offering the possibility of analysing separately the structural elements that play an important role in the physical properties of thee materials. Two different methodologies have been used depending on the topological similarities existing between the struts and cell walls: 3D erosion-dilation procedure (thick struts) and solid classification algorithm (thin struts). In a second step, analysis of cell walls is performed in order to show the advantages of analysing separately the two foams components. Particularly, cell wall thickness distribution reveals differences that could not be found prior to the de-structuration

Detecting series periodicity with horizontal visibility graphs

The horizontal visibility algorithm has been recently introduced as a mapping between time series and networks. The challenge lies in characterizing the structure of time series (and the processes that generated those series) using the powerful tools of graph theory. Recent works have shown that the visibility graphs inherit several degrees of correlations from their associated series, and therefore such graph theoretical characterization is in principle possible. However, both the mathematical grounding of this promising theory and its applications are on its infancy. Following this line, here we address the question of detecting hidden periodicity in series polluted with a certain amount of noise. We first put forward some generic properties of horizontal visibility graphs which allow us to define a (graph theoretical) noise reduction filter. Accordingly, we evaluate its performance for the task of calculating the period of noisy periodic signals, and compare our results with standard time domain (autocorrelation) methods. Finally, potentials, limitations and applications are discussed.Comment: To be published in International Journal of Bifurcation and Chao

El lenguaje científico, la divulgación de la ciencia y el riesgo de las pseudociencias

El lenguaje de la ciencia, al igual que los lenguajes técnicos, se caracteriza por su especificidad. En él palabras de uso común 'englobadas en el grupo comunidad científica del resto de la sociedad. No debe pues sorprendernos que el lenguaje científico especializado sea, en no pocas ocasiones, utilizado por algunos científicos 'aquéllos que por el hecho de ser científicos se consideran parte de una élite intelectual' como una suerte de muralla comunicativa, que los mantiene a una distancia 'prudencial' de los profanos y los diferencia del resto de los ciudadanos. Afortunadamente estos científicos son en la actualidad una minoría, ya que la mayoría entiende que la ciencia debe, ante todo, establecer una relación fluida con la sociedad. Y aquí es donde entra en juego la divulgación de la ciencia. Para que la ciencia pueda llegar a la sociedad en su más amplia extensión, y para que pueda ser entendible y aceptada, debe apostar por desprenderse, al menos en parte, de esa incomprensible jerga científica para adoptar un lenguaje más cercano y cotidiano. Pero todo esto colisiona con una corriente opuesta: la adopción por parte de las llamadas 'pseudociencias', como la homeopatía, la osteopatía, o el psicoanálisis de un lenguaje deliberadamente opaco que imita al científico, precisamente con el fin de revestirse de una pátina de respetabilidad, al modo de las ciencias básicas, e incluso para 'protegerse', dificultando el acceso y la comprensión del público general hacia ellas. del vocabulario denominado general' aparecen con significados concretos, en muchas ocasiones diferentes de los que se dan en el discurso cotidiano o general. El discurso científico se caracteriza además por contar con un gran porcentaje relativo de vocabulario específico y exclusivo de este discurso. Esto hace que el lenguaje científico pueda reflejar cierta opacidad, particularmente ante la gente ajena a su uso; lo cual crea una barrera que, en la práctica, aísla a laScientific language is characterized by its specific characteristics. Common general words appear here with specific meanings, frequently different from the ones used in the daily language. Scientific discourse is also characterized by the great relative amount of specific vocabulary, exclusive of this discourse. This makes scientific language to reflect a certain degree of opacity, particularly to people alien to its use; this in turn creates a sort of barrier which in practice isolates the scientific community from the rest of society. It is no surprise that specialized scientific language is often employed by some scientists 'those who believe themselves to be a part of an intellectual élite' as a sort of communicative barrier, which keeps them at a 'prudential' distance away from the laypersons and distinguishes them from the rest of people. Fortunately these elitist scientists are nowadays a minority, for most of them understand that science must, above all, establish a fluid relationship with society. And here comes popularization of science. For science to reach society in its widest extension, and to be understandable, it must get rid of this incomprehensible scientific jargon in order to adopt a closer and more quotidian language. All this collides with an opposite trend: the adoption by the 'pseudo-sciences', such as homeopathy, osteopathy, or psychoanalysis, of a deliberately opaque language which imitates scientific language with the sole aim of arm these pseudo-sciences with a patina of respectability, which serves to protect themselves hence hindering the access to them and the comprehension of the general public

Spin-texture topology in curved circuits driven by spin-orbit interactions

Interferometry is a powerful technique used to extract valuable information about the wave function of a system. In this work, we study the response of spin carriers to the effective field textures developed in curved one-dimensional interferometric circuits subject to the joint action of Rashba and Dresselhaus spin-orbit interactions. By using a quantum network technique, we establish that the interplay between these two non-Abelian fields and the circuit's geometry modify the geometrical characteristics of the spinors, particularly on square circuits, leading to the localisation of the electronic wave function and the suppression of the quantum conductance. We propose a topological interpretation by classifying the corresponding spin textures in terms of winding numbers.Comment: 13 pages, 9 figure

Rapid Decreasing in the Orbital Period of the Detached White Dwarf?main Sequence Binary SDSS J143547.87+373338.5

SDSS J143547.87+373338.5 is a detached eclipsing binary that contains a white dwarf with a mass of 0.5 M⊙ and a fully convective star with a mass of 0.21 M⊙. The eclipsing binary was monitored photometrically from 2009 March 24 to 2015 April 10, by using two 2.4-m telescopes in China and in Thailand. The changes in the orbital period are analyzed based on eight newly determined eclipse times together with those compiled from the literature. It is found that the observed?calculated (O?C) diagram shows a downward parabolic change that reveals a continuous period decrease at a rate of dot{P}=-8.04× {10}-11 s s‑1. According to the standard theory of cataclysmic variables, angular momentum loss (AML) via magnetic braking (MB) is stopped for fully convective stars. However, this period decrease is too large to be caused by AML via gravitational radiation (GR), indicating that there could be some extra source of AML beyond GR, but the predicted mass-loss rates from MB seem unrealistically large. The other possibility is that the O?C diagram may show a cyclic oscillation with a period of 7.72 years and a small amplitude of 0.ͩ000525. The cyclic change can be explained as the light-travel-time effect via the presence of a third body because the required energy for the magnetic activity cycle is much larger than that radiated from the secondary in a whole cycle. The mass of the potential third body is determined to be {M}3{sin}{i}prime =0.0189(+/- 0.0016) M⊙ when a total mass of 0.71 M⊙ for SDSS J143547.87+373338.5 is adopted. For orbital inclinations {i}prime ≥slant 15uildrel{circ}over{.} 9, it would be below the stable hydrogen-burning limit of M3 ∼ 0.072 M⊙, and thus the third body would be a brown dwarf.Fil: Qian, S. B.. Chinese Academy of Sciences; República de ChinaFil: Han, Z. T.. Chinese Academy of Sciences; República de ChinaFil: Soonthornthum, B.. National Astronomical Research Institute of Thailand; TailandiaFil: Zhu, L. Y.. Chinese Academy of Sciences; República de ChinaFil: He, J. J.. Chinese Academy of Sciences; República de ChinaFil: Rattanasoon, S.. National Astronomical Research Institute of Thailand; TailandiaFil: Aukkaravittayapun, S.. National Astronomical Research Institute of Thailand; TailandiaFil: Liao, W. P.. Chinese Academy of Sciences; República de ChinaFil: Zhao, E. G.. Chinese Academy of Sciences; República de ChinaFil: Zhang, J.. Chinese Academy of Sciences; República de ChinaFil: Fernandez Lajus, Eduardo Eusebio. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; Argentin

A modified equation analysis for immersed boundary methods based on volume penalization: applications to linear advection-diffusion and high-order discontinuous Galerkin schemes

The Immersed Boundary Method (IBM) is a popular numerical approach to impose boundary conditions without relying on body-fitted grids, thus reducing the costly effort of mesh generation. To obtain enhanced accuracy, IBM can be combined with high-order methods (e.g., discontinuous Galerkin). For this combination to be effective, an analysis of the numerical errors is essential. In this work, we apply, for the first time, a modified equation analysis to the combination of IBM (based on volume penalization) and high-order methods (based on nodal discontinuous Galerkin methods) to analyze a priori numerical errors and obtain practical guidelines on the selection of IBM parameters. The analysis is performed on a linear advection-diffusion equation with Dirichlet boundary conditions. Three ways to penalize the immerse boundary are considered, the first penalizes the solution inside the IBM region (classic approach), whilst the second and third penalize the first and second derivatives of the solution. We find optimal combinations of the penalization parameters, including the first and second penalizing derivatives, resulting in minimum errors. We validate the theoretical analysis with numerical experiments for one- and two-dimensional advection-diffusion equations

Erigeron cabelloi A. Pujadas, R. García-Salmones & E. López (Asteraceae) a new species from the Pyrennees

Erigeron cabelloi A. Pujadas, R. García-Salmones & E. López (Asteraceae) a new species from the Pyrennees. Palabras clave. Andorra, Compositae, Corología, Erigeron neglectus, Flora Ibérica. Key words. Andorra, Chorology, Compositae, Erigeron neglectus, Iberian Flora

A charge-coupled device photometric study of south hemispheric contact binary AE Phoenicis

The complete charge-coupled device light curves in B, V, R, and I bands of the short-period binary system, AE Phe, are presented. It is found that the light curves of AE Phe belong to typical EW-type light variation. Photometric solutions were derived by using the 2003 version of the Wilson–Devinney code. It showed that AE Phe is a Wsubtype shallow-contact system (f = 14.6%(±0.5%)) with a mass ratio of q = 2.5491(±0.0092). The temperature difference between the two components is 227 K. Analysis of the O − C curve suggests that the period of AE Phe shows a long-term continuous increase at a rate of dP /dt = +6.17(±0.44) × 10−8 days year−1. The longterm period increase, the marginal-contact configuration, and the astrophysical parameters of the binary system, all suggest that it is a shallow-contact binary undergoing a thermal relaxation oscillation evolving into a detached binary.Fil: He, J. J.. Chinese Academy of Sciences; República de ChinaFil: Qian, S. B.. Chinese Academy of Sciences; República de ChinaFil: Fernandez Lajus, Eduardo Eusebio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Fariña, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin