Like-charge attraction through hydrodynamic interaction

We demonstrate that the attractive interaction measured between like-charged colloidal spheres near a wall can be accounted for by a nonequilibrium hydrodynamic effect. We present both analytical results and Brownian dynamics simulations which quantitatively capture the one-wall experiments of Larsen and Grier (Nature 385, p. 230, 1997).Comment: 10 pages, 4 figure

A Police Officer’s Tacit Knowledge Inventory (POTKI): Establishing Construct Validity and Exploring Applications

Research summarizes the construction of a Police Officer’s Tacit Knowledge Inventory (Inventory), a situational judgment test comprised of knowledge gained on-the-job by experienced police officers, and examines if it can play a role in the development of expertise. Correlation and regression analysis was done to establish the Inventory’s ability to predict post-Academy graduation performance. Results show that Inventory response patterns correlate with Supervisor ratings; and the Inventory responses correctly predict significant differences between novice patrol officers and experienced police officers

On the nature of long-range contributions to pair interactions between charged colloids in two dimensions

We perform a detailed analysis of solutions of the inverse problem applied to experimentally measured two-dimensional radial distribution functions for highly charged latex dispersions. The experiments are carried out at high colloidal densities and under low-salt conditions. At the highest studied densities, the extracted effective pair potentials contain long-range attractive part. At the same time, we find that for the best distribution functions available the range of stability of the solutions is limited by the nearest neighbour distance between the colloidal particles. Moreover, the measured pair distribution functions can be explained by purely repulsive pair potentials contained in the stable part of the solution.Comment: 6 pages, 5 figure

Partially coherent surface plasmon modes

Elementary long-range plasmon modes are described assuming an exponential dependence of the refractive index in the neighbourhood of the interface dielectric-metal thin film. The study is performed using coupling mode theory. The interference between two long-range plasmon modes generated that way allows the synthesis of surface sinusoidal plasmon modes, which can be considered as completely coherent generalized plasmon modes. These sinusoidal plasmon modes are used for the synthesis of new partially coherent surface plasmon modes, which are obtained by means of an incoherent superposition of sinusoidal plasmon modes where the period of each one is considered as a random variable. The kinds of surface modes generated have an easily tuneable profile controlled by means of the probability density function associated to the period. We show that partially coherent plasmon modes have the remarkable property to control the length of propagation which is a notable feature respect to the completely coherent surface plasmon mode. The numerical simulation for sinusoidal, Bessel, Gaussian and Dark Hollow plasmon modes are presente

Caso único: el efecto Ringelmann en un bote de remo de elite = Unique case: The Ringelmann effect on a rowboat elite

Objetivo: Analizar si en la tripulación del cuatro sin timonel español seleccionada para el preolímpico de Río de Janeiro 2016 presenta el efecto Ringelmann, consistente en que conforme aumenta el número de componentes de un grupo, la aportación individual, al resultado final, va disminuyendo. Método: La muestra la componen los cuatro remeros de la tripulación del citado bote con una experiencia de 13, 16, 10 y 13 años respectivamente, y una edad media de 24.25 ± 0.5 años. Resultados: En la totalidad de los casos se produce un aumento sistemático en la condición del equipo respecto de la individual, con una media de metros recorridos en esta de 1029.25 metros, mientras que en la grupal fue de 1036.75. El número de vatios generados también fue superior en la ejecución colectiva (535.25w. frente a los 524.25w.). Sin embargo, la media de paladas en la condición individual fue inferior (35.5) a la de grupo (37.25). En cuanto a la percepción de esfuerzo (escala de Borg), los remeros puntuaban más bajo individualmente (7.75) que en grupo (8.75). Conclusiones: Nuestros datos parecen mostrar que el nivel competitivo, la fuerte convicción de equipo y la alta motivación pueden no solo paliar, sino hacer desaparecer el efecto Ringelmann en un bote de cuatro sin timonel. A pesar de que la percepción de esfuerzo es mayor en equipo. ABSTRACT Objective: Try to know if the crew of the Spanish boat Coxless four selected for the pre-Olympic 2016 Rio de Janeiro shows the Ringelmann effect, which is that as the number of components of a group, the individual contribution decreases. Method: The sample is composed of four rowers crew of that boat with an experience of 13, 16, 10 and 13 years, respectively, and an average age of 24.25 years ([DT] = 0.5). Results: In all cases a systematic increase occurs in the equipment condition regarding individual, with an average of meters traveled in this of 1029.25 meters, while the group was 1036.75. The number of watts generated was also higher in the collective execution (535.25w. versus 524.25w.). However, the average of strokes in the individual condition was lower (35.5) to the group (37.25). As for the perception of effort (Borg scale), the rowers individually scored lower (7.75) than in group (8.75)

Caso único: el efecto Ringelmann en un bote de remo de elite

Objetivo: Analizar si en la tripulación del cuatro sin timonel espanol ˜ seleccionada para el preolímpico de Río de Janeiro 2016 presenta el efecto Ringelmann, consistente en que conforme aumenta el número de componentes de un grupo, la aportación individual, al resultado final, va disminuyendo. Método: La muestra la componen los cuatro remeros de la tripulación del citado bote con una experiencia de 13, 16, 10 y 13 anos ˜ respectivamente, y una edad media de 24.25 ± 0.5 anos. ˜ Resultados: En la totalidad de los casos se produce un aumento sistemático en la condición del equipo respecto de la individual, con una media de metros recorridos en esta de 1029.25 metros, mientras que en la grupal fue de 1036.75. El número de vatios generados también fue superior en la ejecución colectiva (535.25w. frente a los 524.25w.). Sin embargo, la media de paladas en la condición individual fue inferior (35.5) a la de grupo (37.25). En cuanto a la percepción de esfuerzo (escala de Borg), los remeros puntuaban más bajo individualmente (7.75) que en grupo (8.75). Conclusiones: Nuestros datos parecen mostrar que el nivel competitivo, la fuerte convicción de equipo y la alta motivación pueden no solo paliar, sino hacer desaparecer el efecto Ringelmann en un bote de cuatro sin timonel. A pesar de que la percepción de esfuerzo es mayor en equipo

The present and future status of heavy neutral leptons

The existence of nonzero neutrino masses points to the likely existence of multiple Standard Model neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as heavy neutral leptons (HNLs). In this white paper, we discuss the present experimental status of HNLs including colliders, beta decay, accelerators, as well as astrophysical and cosmological impacts. We discuss the importance of continuing to search for HNLs, and its potential impact on our understanding of key fundamental questions, and additionally we outline the future prospects for next-generation future experiments or upcoming accelerator run scenarios

Shrike predation on the lizard Mesalina adramitana in Qatar; a review of reported reptile and amphibian prey

We report, for the first time, evidence of predation by a shrike (Lanius sp.) on the lizard Mesalina adramitana. This is the first record of predation by shrikes on lizards in Qatar. Whilst we did not directly observe the event, the presence of shrikes in the area and the method of impalement indicate shrikes as the predator. The lizard was found freshly impaled on a palm tree (Phoenix dactylifera), at 150 cm above ground. Bird species of the genus Lanius are well-known predators of lizards, and in arid environments reptiles are likely common prey for these birds. We provide a review of literature concerning predatory events by shrikes on reptiles and amphibians. We suggest inspection of shrubs for animals impaled by shrikes can improve biodiversity inventories, complementing other commonly used methods