Screening of heterogeneous surfaces: charge renormalization of Janus particles

Nonlinear ionic screening theory for heterogeneously charged spheres is developed in terms of a mode-decomposition of the surface charge. A far-field analysis of the resulting electrostatic potential leads to a natural generalization of charge renormalization from purely monopolar to dipolar, quadropolar, etc., including mode-couplings. Our novel scheme is generally applicable to large classes of surface heterogeneities, and is explicitly applied here to Janus spheres with differently charged upper and lower hemispheres, revealing strong renormalization effects for all multipoles.Comment: 2 figure

Individually-rational collective choice

There is a collection of exogenously given socially-feasible sets, and, for each one of them, each individual in a group chooses from an individually-feasible set. The fact that the product of the individually-feasible sets is larger than the socially-feasible set notwithstanding, there arises no conflict between individual choices. Assuming that individual preferences are random, I characterize rationalizable collective choices

Phase diagram and magnetic properties of La1−x_{1-x}Cax_xMnO3_3 compound for 0≤x≤0.230\leq x \leq 0.23

In this article a detailed study of La$_{1-x}$Ca$_x$MnO$_3$ ($0\leq x \leq 0.23$) phase diagram using powder x-ray diffraction and magnetization measurements is presented. Unfortunately, in the related literature no properly characterized samples have been used, with consequence the smearing of the real physics in this complicated system. As the present results reveal, there are two families of samples. The first family concerns samples prepared in atmosphere ($P({\rm O}_2)=0.2$ Atm) which are all ferromagnetic with Curie temperature rising with $x$. The second family concerns samples, where a post annealing in nearly zero oxygen partial pressure is applied. These samples show a canted antiferromagnetic structure for $0\leq x \leq 0.1$ below $T_N$, while for $0.125\leq x <0.23$ an unconventional ferromagnetic insulated phase is present below $T_c$. The most important difference between nonstoichiometric and stoichiometric samples concerning the magnetic behavior, is the anisotropy in the exchange interactions, in the stoichiometric samples putting forward the idea that a new orbital ordered phase is responsible for the ferromagnetic insulating regime in the La$_{1-x}$Ca$_x$MnO$_3$ compound

Modelando la evolución del SARS-COV-2 usando una aproximación fraccionaria

To show the potential of non-commensurable fractional-order dynamical systems in modeling epidemiological phenomena, we will adjust the parameters of a fractional generalization of the SIR model to describe the population distributions generated by SARS-CoV-2 in France and Colombia. Despite the completely different contexts of both countries, we will see how the system presented here manages to adequately model them thanks to the flexibility provided by the fractional-order differential equations. The data for Colombia were obtained from the records published by the Colombian Ministry of Information Technology and Communications from March 24 to July 10, 2020. Those for France were taken from the information published by the Ministry of Solidarity and Health from May 1 to September 6, 2020. As for the methodology implemented in this study, we conducted an exploratory analysis focused on solving the fractional SIR model by means of the fractional transformation method. In addition, the model parameters were adjusted using a sophisticated optimization method known as the Bound Optimization BY Quadratic Approximation (BOBYQA) algorithm. According to the results, the maximum error percentage for the evolution of the susceptible, infected, and recovered populations in France was 0.05%, 19%, and 6%, respectively, while that for the evolution of the susceptible, infected, and recovered populations in Colombia was 0.003%, 19%, and 38%, respectively. This was considered for data in which the disease began to spread and human intervention did not imply a substantial change in the community.Con el objetivo de exponer el potencial de los sistemas dinámicos de orden fraccionario, inconmensurables para la modelación de fenómenos epidemiológicos, en este artículo se ajustarán los parámetros de una generalización fraccionaria del modelo SIR (susceptibles, infectados y recuperados) para describir las distribuciones poblacionales generadas por el SARS-CoV-2 en Francia y Colombia, dos países cuyos contextos son totalmente diferentes. Asimismo, se mostrará cómo el sistema presentado logra describir adecuadamente los dos contextos debido a la flexibilidad proporcionada por las ecuaciones diferenciales de orden fraccionario. Los datos, para Colombia, fueron obtenidos del registro hecho por el Ministerio de Tecnologías de la Información y las Comunicaciones, considerándose las fechas del 24 de marzo del 2020 hasta el 10 de julio del mismo año. Por su parte, para Francia, los datos fueron tomados del monitoreo hecho por el Ministerio de Solidaridad y Salud, en un periodo comprendido desde el 1 de mayo de 2020 hasta el 6 de septiembre del mismo año. La metodología seguida es un análisis exploratorio centrado en la solución del modelo SIR fraccionario a partir del método de la transformación fraccionaria, ajustado mediante un plan sofisticado de optimización llamado algoritmo BOBYQA. Los resultados presentados muestran que el porcentaje de error máximo para la evolución de la población susceptible, infectada y recuperada en Francia es de 0.05 %, 19 % y 6 %, respectivamente. Mientras tanto, en Colombia se tiene un valor correspondiente de 0.003 %, 19 %, 38 %, esto para datos en los que se inició la dispersión de la enfermedad, donde la intervención humana no tuvo un cambio contundente en la comunidad. &nbsp

The Cross-Cultural Invariance of the Servant Leadership Survey: A Comparative Study across Eight Countries

This paper tests and confirms the cross-cultural equivalence of the Servant Leadership Survey (SLS) in eight countries and languages: The Netherlands, Portugal, Germany, Iceland, Italy, Spain, Turkey and Finland. A composite sample consisting of 5201 respondents from eight countries that all filled out the SLS was used. A three-step approach was adopted to test configural invariance, measurement equivalence, and structural equivalence. For the full 30-item version of the SLS, configural invariance and partial measurement equivalence were confirmed. Implications of these results for the use of the SLS within cross-cultural studies are discussed

High-pressure synthesis of rock salt LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions

Metastable LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions with rock salt crystal structure have been synthesized by solid state reaction of ZnO with LiMeO2 complex oxides at 7.7 GPa and 1350-1450 K. Structure, phase composition, thermal stability and thermal expansion of the recovered samples have been studied by X-ray diffraction with synchrotron radiation. At ambient pressure rock salt LiMeO2-ZnO solid solutions are kinetically stable up to 670-800 K depending on the composition.Comment: 11 pages, 3 figures, 1 tabl

Improved prediction of the optical properties in pi-conjugated polymers: the case of benzochalcogenodiazole-based copolymers with different heteroatom substitution

Donor−acceptor (D−A) approach to conjugated polymer design has become a widely used method for preparing conjugated polymers with narrow band gaps.1 One outstanding D−A polymer is poly(cyclopentadithiophene)benzothiadiazole, PCPDTBT (P1 in Figure 1), for which power conversion efficiencies in solar cells of 4.5-5.5% are reported.2 In this work, we use resonance Raman (RR) and density functional theory (DFT) calculations to investigate the tuning of the electronic and structural properties of cyclopentadithiophene-benzochalcogenodiazole D−A polymers, wherein a single atom in the benzochalcogenodiazole unit is varied from sulfur to selenium to tellurium (Fig. 1).3 Sophisticated DFT calculations have been carried out using long-range corrected functionals, considering both tuned and default range-separation parameters, aiming at predicting their optical and charge transport properties. In addition, the nature of the electronic excitation is described by analyzing the enhancement pattern in the RR spectra using Raman excitation wavelengths coincident with the various transitions in the copolymers.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

TERC polymorphisms are associated both with susceptibility to colorectal cancer and with longer telomeres.

Shorter telomeres have been associated with increased risk of malignancy, including colorectal cancer (CRC). Telomere length is heritable and may be an intermediate phenotype linked to genetic susceptibility to CRC