A Simple Thermoelectric Droplet Generator

A new design for a droplet generator capable of producing single droplets is presented. The design relies on thermoelectric heating to vaporize water at the interface between a droplet and a blunt syringe tip. While other designs require careful tuning to produce drops of varying size, this technique enables the simple creation of droplets of any size within a range. The design is of simple construction and can be completed with off-the-shelf components, and relies on resistive heating to vaporize water at or near the droplet-nozzle interface and release the droplets. We demonstrated that the design can be used to produce droplets as small as 110 m or as large as 2 mm. Drop size is limited by the geometry of the nozzle since water must wet the tip of the nozzle and hang under gravity. Our experiments showed that released droplets have relatively small disturbances introduced by the release mechanism when compared to competing techniques. These disturbances were intermittently observed as the voltage, pulse width, and drop size were changed, and optimal settings were determined for the smallest drop sizes produced

Current Experimental Basis for Modeling Ice Accretions on Swept Wings

This work presents a review of the experimental basis for modeling ice accretions on swept wings. Experimental work related to ice accretion physics on swept wings conducted between 1954 and 2004 is reviewed. Proposed models or explanations of scallop formations are singled out and discussed. Special emphasis is placed on reviewing the work done to determine the basic macroscopic mechanisms of scallop formation. The role of feather growth and its connection to scallop growth is discussed. Conceptual steps in modeling scallop formations are presented. Research elements needed for modeling are discussed

Conocimiento, propiedad, participación y poder

La teoría organizacional ha atravesado un amplio espacio en la búsqueda de sus propias verdades apoyándose en este camino, en distintas metáforas, modelos y pensamientos. Este recorrido, o al menos un buen trecho del mismo, ha estado acompañado de reflexiones profundas y complejas en torno a cuatro palabras que se han articulado indistintamente y de dicha articulación se ha teorizado y se teorizará aún más: Conocimiento, Propiedad, Participación y Poder. Este escrito es un intento de conectar a través de un fino hilo, desde la pertinencia territorial, este eje sin ninguna pretensión adicional.The organizational theory has gone through huge space in search of his own truest supporting in this road in different metaphors, models and thoughts. This journey or at least a good part of has always been in company of deep and complex reflections around four words that have been articulated indinstinctively and of this articulation have been theorized and will be theorized even more: knowledge, property, participation and power. This writing is a purpose of connecting through a yarn edge, since territorial pertinence, this axle without an additional objective

Función exponencial. Resultados de investigaciones al servicio de la planeación y gestión del trabajo de aula

Se presenta un análisis de documentos que abordan la didáctica de la función exponencial. Si bien éstos poseen una riqueza inherente, se plantea la opción de indagar sobre los puntos centrales de estas propuestas, pensando en su planeación y gestión en el aula de clase. Se examina y argumenta con parámetros tomados desde la matemática, la historia y la epistemología de este concepto

Desafíos para asegurar la calidad del servicio de internet inalámbrico en la Universidad Francisco Gavidia

El proyecto “Aseguramiento de la conectividad de la red inalámbrica y calidad en el acceso al servicio de internet”, contempla el desarrollo de una solución a las necesidades de conectividad WiFi en la Universidad Francisco Gavidia. La UFG a partir del año 2008 instaló la primera infraestructura que permitió ofrecer el servicio de internet inalámbrico en su campus. Sin embargo, se tuvo que superar grandes desafíos para ofrecer un servicio que permita abarcar el mayor número de usuarios con un nivel aceptable de servicio y que contara con medidas de seguridad apropiadas para una institución de educación superior

Electromagnetic modeling and simulations of interest for low-level laser therapies or for problems involving moving objects

This work presents results on the computed electromagnetic field within isolated mitochondria when exposed to near-infrared illuminations concerning photobiomodulation experiments. The accuracy of the electromagnetic models implemented for dosimetry is important. The mechanism of interaction of light with these organelles is still unclear, so it is important to improve our knowledge with reliable simulations and experiments. To obtain such results, we present several models. Although they refer to a well-defined experimental setup, the different models must consider the different possible arrangements of the mitochondria and the differences in their dimensions and constitutive parameters. Different wavelengths and polarizations are considered too. The effects of all the parameters on the electromagnetic field inside the mitochondria and the internal morphology are studied. Computational techniques are also exploited to find reliable approximations of the solutions of problems involving moving objects. The effect of the motion of objects on the electromagnetic field is studied as well; for this type of problem, it is necessary to understand that the constitutive relations are modified because the movement makes any material to appear as a bianisotropic medium. In particular, the rotation movement of symmetrical bodies is studied, the electromagnetic field is calculated and an inversion algorithm for the estimate of the rotation speed is proposed

Joint diagnostic of the surface air temperature in southern South America and the Madden–Julian oscillation

The objective of this research is to explore the relationship between maximum and minimum temperatures, daily precipitation, and the Madden–Julian oscillation (MJO). It was found that the different phases of the MJO show a consistent signal on winter temperature variability and precipitation in southeastern South America. Additionally, this paper explores the spatial–temporal variations of mutual information and joint entropy between temperature and the MJO. A defined spatial pattern was observed with an increased signal in northeastern Argentina and southern Brazil. In the local mutual information analysis, periods in which the mutual information doubled the average values were observed over the entire region. These results indicate that these connections can be used to forecast winter temperatures with a better skill score in situations where both variables covary.Fil: Naumann, Gustavo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vargas, Walter Mario. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Genetically Depauperate in the Continent but Rich in Oceanic Islands: Cistus monspeliensis (Cistaceae) in the Canary Islands

BACKGROUND: Population genetic theory holds that oceanic island populations are expected to have lower levels of genetic variation than their mainland counterparts, due to founder effect after island colonization from the continent. Cistus monspeliensis (Cistaceae) is distributed in both the Canary Islands and the Mediterranean region. Numerous phylogenetic results obtained in the last years allow performing further phylogeographic analyses in Cistus. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed sequences from multiple plastid DNA regions in 47 populations of Cistus monspeliensis from the Canary Islands (21 populations) and the Mediterranean basin (26 populations). The time-calibrated phylogeny and phylogeographic analyses yielded the following results: (1) a single, ancestral haplotype is distributed across the Mediterranean, whereas 10 haplotypes in the Canary Islands; (2) four haplotype lineages are present in the Canarian Islands; (3) multiple colonization events across the archipelago are inferred; (4) the earliest split of intraspecific lineages occurred in the Early to Middle Pleistocene (<930,000 years BP). CONCLUSIONS/SIGNIFICANCE: The contrasting pattern of cpDNA variation is best explained by genetic bottlenecks in the Mediterranean during Quaternary glaciations, while the Canarian archipelago acted as a refugium of high levels of genetic diversity. Active colonization across the Canarian islands is supported not only by the distribution of C. monspeliensis in five of the seven islands, but also by our phylogeographic reconstruction in which unrelated haplotypes are present on the same island. Widespread distribution of thermophilous habitats on every island, as those found throughout the Mediterranean, has likely been responsible for the successful colonization of C. monspeliensis, despite the absence of a long-distance dispersal mechanism. This is the first example of a plant species with higher genetic variation among oceanic island populations than among those of the continent