Analytical theory for the crossover from retarded to non-retarded interactions between metal plates

This is the Accepted Manuscript version of an article accepted for publication in Journal of Physics Condensed Matter. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-648X/ac6720The van der Waals force established between two surfaces plays a central role in many phenomena, such as adhesion or friction. However, the dependence of this forces on the distance of separation between plates is very complex. Two widely different non-retarded and retarded regimes are well known, but these have been traditionally studied separately. Much less is known about the important experimentally accessible cross-over regime. In this study, we provide analytical approximations for the van der Waals forces between two plates that interpolates exactly between the short distance and long distance behavior, and provides new insight into the crossover from London to Casimir forces at finite temperature. At short distance, where the behavior is dominated by non-retarded interactions, we work out a very accurate simplified approximation for the Hamaker constant which adopts analytical form for both the Drude and Lorentz models of dielectric response. We apply our analytical expressions for the study of forces between metallic plates, and observe very good agreement with exact results from numerical calculations. Our results show that contributions of interband transitions remain important in the experimentally accessible regime of decades nm for several metals, including gol

Soluções simples para armazenar hortaliças nos pontos de venda.

bitstream/item/103086/1/cot-38.pd

Debates electorales en televisión: una aproximación preliminar a sus efectos inmediatos

El estudio que se presenta es fruto de un proyecto de investigación realizado en la Universidad de Granada.Hasta ahora la investigación sobre los debates electorales se ha centrado mayoritariamente en calibrar elimpacto de los debates después de éstos. Sin embargo, no demasiadas investigaciones le han prestado unaatención especial a los procesos que ocurren durante los debates, tanto al principio como en la mitad o alfinal de los mismos, que pudieran identificar otros aspectos importantes más allá de la influencia de losdebates en el voto, como determinar las estrategias discursivas que mejor llegaron al público.Usando el debate electoral que enfrentó a José Luis Rodríguez Zapatero y a Mariano Rajoy el 3 de marzode 2008, el segundo de los celebrados en esta pasada campaña, y ayudados por un sistema informático diseñadoal efecto —Continuous Response Measurement (CRM)—, se pudieron comprobar las impresiones delos ciudadanos en tiempo real sobre la actuación de los dos candidatos, pretendiendo contribuir a darrespuesta a las cuestiones más comunes sobre las cuales no se han acumulado aún muchas explicaciones.Para ello se combinaron varias estrategias de investigación. Se aplicó un sistema de respuesta en tiempo realque, junto al análisis de contenido y a las técnicas de análisis de encuesta, permitió controlar un gran númerode aspectos intervinientes en la compleja interacción objeto de estudio, como la predisposición ideológica olas expectativas manejadas sobre los resultados del debate. Se insistió en el análisis a nivel micro y en queel estudio se basa en el análisis verbal, aunque somos conscientes de la importancia también de los aspectosmás visuales sobre los que también se ha discutido.Los resultados permitirán saber cuáles fueron los aspectos que determinaron las percepciones inmediatas delos ciudadanos durante el evento, cuál fue el papel jugado por los medios de comunicación, o las estrategiasdiscursivas más eficaces a la hora de seducir a los telespectadores durante el evento mencionado

Crowdsourcing malaria parasite quantification: an online game for analyzing images of infected thick blood smears

Background: There are 600,000 new malaria cases daily worldwide. The gold standard for estimating the parasite burden and the corresponding severity of the disease consists in manually counting the number of parasites in blood smears through a microscope, a process that can take more than 20 minutes of an expert microscopist’s time. Objective: This research tests the feasibility of a crowdsourced approach to malaria image analysis. In particular, we investigated whether anonymous volunteers with no prior experience would be able to count malaria parasites in digitized images of thick blood smears by playing a Web-based game. Methods: The experimental system consisted of a Web-based game where online volunteers were tasked with detecting parasites in digitized blood sample images coupled with a decision algorithm that combined the analyses from several players to produce an improved collective detection outcome. Data were collected through the MalariaSpot website. Random images of thick blood films containing Plasmodium falciparum at medium to low parasitemias, acquired by conventional optical microscopy, were presented to players. In the game, players had to find and tag as many parasites as possible in 1 minute. In the event that players found all the parasites present in the image, they were presented with a new image. In order to combine the choices of different players into a single crowd decision, we implemented an image processing pipeline and a quorum algorithm that judged a parasite tagged when a group of players agreed on its position. Results: Over 1 month, anonymous players from 95 countries played more than 12,000 games and generated a database of more than 270,000 clicks on the test images. Results revealed that combining 22 games from nonexpert players achieved a parasite counting accuracy higher than 99%. This performance could be obtained also by combining 13 games from players trained for 1 minute. Exhaustive computations measured the parasite counting accuracy for all players as a function of the number of games considered and the experience of the players. In addition, we propose a mathematical equation that accurately models the collective parasite counting performance. Conclusions: This research validates the online gaming approach for crowdsourced counting of malaria parasites in images of thick blood films. The findings support the conclusion that nonexperts are able to rapidly learn how to identify the typical features of malaria parasites in digitized thick blood samples and that combining the analyses of several users provides similar parasite counting accuracy rates as those of expert microscopists. This experiment illustrates the potential of the crowdsourced gaming approach for performing routine malaria parasite quantification, and more generally for solving biomedical image analysis problems, with future potential for telediagnosis related to global health challenges

Tomato (Lycopersicon esculentum P. Miller) compression due to "K" wood box closing.

Wood boxes kind ?k? are the most used in table tomato (Lycopersicon esculentum P. Miller) commercialization in Brazil. Dueto the fruit accommodation process that occurs during the transport from the production place to the commercialization point, producers fill tomato boxes a little bit over its physical capacity, and they close it with wood strips fixed with nails. In order to prevent strips from cracking, it is common to keep them inside water before using, to increase flexibility