Exfoliated graphite flakes as soft-electrodes for precisely contacting nanoobjects

This is the post-peer reviewed version of the following article: P. ares et al. “Exfoliated graphite flakes as soft-electrodes for precisely contacting nanoobjects”. 2D Matererials, 2015, 2(3): 035008. Which has been published in final form at:http://dx.doi.org/10.1088/2053-1583/2/3/035008We introduce a simple, clean and reliable method to transfer exfoliated graphite flakes as soft-electrodes for the electrical contacts of nano-objects. The microelectrodes thus produced exhibit extremely well-defined and thin edges and can be placed at any sample location with sub-micrometer precision. The procedure is carried out under ambient conditions and does not require chemical agents. We present electrical characterization of relevant examples including carbon nanotubes, metal-organic MMX nanoribbons, reduced graphene sheets and damaged circuit repair. The quality of the electrical contacts thus obtained is as good as those fabricated with conventional techniques. This technique is particularly relevant for conductive atomic force microscopy (AFM) studiesThis work was supported by Consolider CSD2010-0024, MAD2D-CM, S2013/MIT-3007 and MAT2013-46753-C2-1 and

Effects of Non-Circular Motions on Azimuthal Color Gradients

Assuming that density waves trigger star formation, and that young stars preserve the velocity components of the molecular gas where they are born, we analyze the effects that non-circular gas orbits have on color gradients across spiral arms. We try two approaches, one involving semi-analytical solutions for spiral shocks, and another with magnetohydrodynamic (MHD) numerical simulation data. We find that, if non-circular motions are ignored, the comparison between observed color gradients and stellar population synthesis models would in principle yield pattern speed values that are systematically too high for regions inside corotation, with the difference between the real and the measured pattern speeds increasing with decreasing radius. On the other hand, image processing and pixel averaging result in systematically lower measured spiral pattern speed values, regardless of the kinematics of stellar orbits. The net effect is that roughly the correct pattern speeds are recovered, although the trend of higher measured $\Omega_p$ at lower radii (as expected when non-circular motions exist but are neglected) should still be observed. We examine the Martinez-Garcia et al. (2009) photometric data and confirm that this is indeed the case. The comparison of the size of the systematic pattern speed offset in the data with the predictions of the semi-analytical and MHD models corroborates that spirals are more likely to end at Outer Lindblad Resonance, as these authors had already found.Comment: 32 pages, 15 figures, accepted to Ap

Cuando la razón no lo explica todo: acciones de ciudadanías comunicativas en contextos de conflicto armado o violencia desde una mirada transnacional (When Reason Does Not Explain Everything: Communicative Citizenship Actions in Contexts of Armed Conflict or Violence from a Transnational Perspective)

El objetivo de este artículo es presentar los resultados de un análisis a tres movimientos de mujeres víctimas de conflictos armados y de contextos de violencia desde la perspectiva teórica de las ciudadanías comunicativas y el transnacionalismo. A partir del desarrollo de entrevistas a profundidad y estrategias metodológicas de observación-participación, se explora cómo el afecto y las emociones, en particular el dolor por la pérdida, se constituyen en una condición de identidad transnacional que cataliza acciones colectivas para reclamar derechos humanos en la esfera pública. A partir de los resultados arrojados, es posible establecer que las víctimas de conflictos armados o de cualquier contexto de violencia, al abordar e instrumentalizar las dimensiones expresivas de la acción colectiva, pueden restablecer los lazos sociales, políticos y culturales con sus comunidades locales y transformar su condición de víctima a una de ciudadanos. Así, este trabajo concluye que el desarrollo de la agencia de ciudadanía comunicativa genera procesos de construcción de memoria social, reconocimiento y solidaridad, desde una perspectiva subalterna-transnacional. Los grupos sociales de víctimas en los cuales se centra este estudio son Las Madres de la Candelaria (Colombia), Las Mujeres de Negro (Serbia) y Nuestras Hijas de Regreso a Casa (México). El aporte original del artículo es exponer las maneras particulares como surge una nueva subjetividad, la del ciudadano-víctima, quien deja de ser opacado y se empodera de su situación para emprender acciones de reclamación de derechos políticos, sociales, culturales y de reconocimiento en la esfera pública. (The objective of this article is to present the results of an analysis of three movements involving women victims of armed conflict and contexts of violence seen from the theoretical perspective of communicative citizenry and transnationalism. Based on the development of in-depth interviews and the use of observational-participation strategies, the authors explore how affection and emotions, particularly the pain of loss, become a condition of transnational identity that catalyzes collective action to claim human rights in the public sphere. Based on the results of the study, it is possible to establish that the victims of armed conflict or those in any context marked by violence can restore social, political and cultural ties with their local communities and transform their condition as victims into one of citizens by addressing and instrumentalizing the expressive dimensions of collective action. The conclusion is that the development of communicative agency on the part of citizens generates processes to construct memory, recognition and solidarity, from a subordinate-transnational perspective. The social groups of victims on which the study is focused include Las Madres de la Candelaria (Colombia), The Women in Black (Serbia) and Our Daughters Are Back Home (Mexico). The article makes an original contribution by revealing the particular ways a new subjectivity arises, that of the citizenvictim, who ceases to be overshadowed and is empowered by their situation to take action to claim political, social, cultural and recognition rights in the public sphere.

Anthropometric Characteristics, Body Composition and Somatotype of Elite Pan-American Race Walking 20K

The anthropometric and somatotype evaluation is an essential tool in the selection and control of high-performance athletes. The aim of this study was to describe the somatotype and body composition of male elite race walkers (20 k modality), and its relationship with athletic performance. Twenty-four race walkers participated in this study. The sample was divided into two groups: the race walkers with the best performance (upper 25 percentile; n=7) and the second group (n=17) that corresponds to the rest of the participants. Weight (kg), height (cm), seven skinfolds, two diameters and five perimeters were measured. Body fat percentage (BF%) were estimated with the Yuhasz formula, and the somatotype was used applying the Heath-Carter method. The best performing athletes were taller (178.3 +/- 4.4 cm vs. 173.7 +/- 5.6 cm, p<0.05) and showed a greater ectomorphic component (p<0.05) than the rest of the participants. The somatotype of the best performance athletes was 2.2-2.8-4.1 against the 2.5-3.8-2.9 of the lowest performing athletes. The average time (hours, minute, seconds) of execution of the race in athletes of better performances was 1: 22:40, in comparison with the athletes of lower performances with 1: 32: 41 (p<0.02). The ectomorphic component and height are morphological characteristics that can determine athletic performance of race walkers. It is suggested to consider these factors in the selection of the race walkers. La evaluación antropométrica y del somatotipo es una importante herramienta en la selección y control de los atletas de alto rendimiento. El objetivo de este estudio fue describir el somatotipo y composición corporal de hombres marchistas olímpicos, modalidad 20 k, y su relación con el rendimiento atlético. Veinticuatro atletas de marcha participaron en este estudio. La muestra fue dividida en dos grupos: los marchistas de mejores rendimientos p25 superior (n=7) y el segundo grupo (n=17) que corresponde al resto de los participantes. Se registró el peso (kg), talla (cm), siete pliegues cutáneos, dos diámetros y cinco perímetros. Se estimó el porcentaje de grasa corporal (%GC) con la fórmula de Yuhasz y se describió el somatotipo utilizando el método de Heath-Carter. Se reporta una mayor altura en los atletas de mejor rendimiento (178,3±4,4 cm vs. 173,7±5,6 cm; p<0,05) y mayor componente ectomorfico (p<0,05) que el resto de los participantes. El somatotipo de los atletas de mejor rendimiento fue de 2.2-2.8-4.1 frente al 2.5-3.8-2.9 de los atletas de menor rendimiento. El tiempo promedio (hora, minuto, segundo) de ejecución de la carrera en atletas de mejores rendimientos fue de 1:22:40, en comparación con los atletas de menores rendimientos con 1:32:41 (p <0,02). El componente ectomórfico y altura serian características morfológicas que pueden determinar el rendimiento deportivo de atletas de marcha. Se sugiere considerar estos factores en la selección de los marchistas olímpicos

Determinación de agua en alcoholes usando como reactivo un tiocianocomplejo del cobalto

En el presente trabajo se propone un método cuantitativopara la determinación de agua en etanol, basado en las variaciones de intensidad del color azul que presentan las soluciones hidroalcohólicas del complejo tetratiocianocobaltato(II) de potasio.El compuesto de coordinación se prepara triturando intimamente en un mortero cantidades estequiométricas desulfato de cobalto(II) y tiocianato de potasio. El complejoobtenido se extrae con etanol, y el sulfato de potasioremanente es insoluble en este medio. El extracto alcohólicofiltrado se evapora lentamente y los cristales azulesobtenidos se mantienen en desecador conteniendo ácido sulfúrico.El objetivo del presente trabajo es desarrollar un métodocuantitativo usando la espectrofotometría molecular, para determinar la concentración de agua en alcoholes hidratados.Esta técnica es de aplicación a limitadas cantidades de agua en alcohol etílico (3,6 -11,2 %) pues a mayores concentracionesde agua en la solución complejo-etanol, se descompone el complejo, liberando el ión cobalto(II) que colorea de rosado la solución

Event selection for dynamical downscaling: a neural network approach for physically-constrained precipitation events

This study presents a new dynamical downscaling strategy for extreme events. It is based on a combination of statistical downscaling of coarsely resolved global model simulations and dynamical downscaling of specific extreme events constrained by the statistical downscaling part. The method is applied to precipitation extremes over the upper Aare catchment, an area in Switzerland which is characterized by complex terrain. The statistical downscaling part consists of an Artificial Neural Network (ANN) framework trained in a reference period. Thereby, dynamically downscaled precipitation over the target area serve as predictands and large-scale variables, received from the global model simulation, as predictors. Applying the ANN to long term global simulations produces a precipitation series that acts as a surrogate of the dynamically downscaled precipitation for a longer climate period, and therefore are used in the selection of events. These events are then dynamically downscaled with a regional climate model to 2 km. The results show that this strategy is suitable to constraint extreme precipitation events, although some limitations remain, e.g., the method has lower efficiency in identifying extreme events in summer and the sensitivity of extreme events to climate change is underestimated