16,116 research outputs found

    Recent high resolution laboratory determinations of line broadening and intensity parameters: PH3, CH3D, and CO2

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    Recent unpublished laboratory work on rovibrational line strengths and broadening coefficients which is of interest in the study of planetary atmospheres was reviewed. The molecules discussed are PH3, CH3D and CO2

    Fast or Frugal, but not both: Decision Heuristics under Time Pressure

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    Heuristics are simple, yet effective, strategies that people use to make decisions. Because heuristics do not require all available information, they are thought to be easy to implement and to not tax limited cognitive resources, which has led heuristics to be characterized as fast-and-frugal. We question this monolithic conception of heuristics by contrasting the cognitive demands of two popular heuristics, Tallying and Take-the-Best. We contend that heuristics that are frugal in terms of information usage may not always be fast because of the attentional control required to implement this focus in certain contexts. In support of this hypothesis, we find that Take-the-Best, while being more frugal in terms of information usage, is slower to implement and fares worse under time pressure manipulations than Tallying. This effect is then reversed when search costs for Take-the-Best are reduced by changing the format of the stimuli. These findings suggest that heuristics are heterogeneous and should be unpacked according to their cognitive demands to determine the circumstances a heuristic best applies

    A Scoping Review of the Demographic and Contextual Factors in Canada’s Educational Opportunity Gaps

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    Despite widespread discussion in the United States, up until now there has not been a review of the demographic and contextual factors associated with Canadian academic achievement. Using Arksey and O’Malley’s (2005) framework, a scoping review was conducted to answer two questions: What demographic and contextual factors are most commonly used in K–12 academic achievement studies in Canada? What, if any,research gaps exist? Fifty-four studies were identified for review. The results reveal 40 demographic or contextual factors, with socio-economic status (SES), gender, language factors, immigrant status, family structure, and Indigenous status being the most commonly studied. Race, religion, and LGBTQ+ identity were understudied factors. The authors recommend the adoption of “educational opportunity gap” as a consistentresearch term, identify understudied factors, and outline several research design considerations

    Hydrodynamic propulsion of human sperm

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    The detailed fluid mechanics of sperm propulsion are fundamental to our understanding of reproduction. In this paper, we aim to model a human sperm swimming in a microscope slide chamber. We model the sperm itself by a distribution of regularized stokeslets over an ellipsoidal sperm head and along an infinitesimally thin flagellum. The slide chamber walls are modelled as parallel plates, also discretized by a distribution of regularized stokeslets. The sperm flagellar motion, used in our model, is obtained by digital microscopy of human sperm swimming in slide chambers. We compare the results of our simulation with previous numerical studies of flagellar propulsion, and compare our computations of sperm kinematics with those of the actual sperm measured by digital microscopy. We find that there is an excellent quantitative match of transverse and angular velocities between our simulations and experimental measurements of sperm. We also find a good qualitative match of longitudinal velocities and computed tracks with those measured in our experiment. Our computations of average sperm power consumption fall within the range obtained by other authors. We use the hydrodynamic model, and a prototype flagellar motion derived from experiment, as a predictive tool, and investigate how sperm kinematics are affected by changes to head morphology, as human sperm have large variability in head size and shape. Results are shown which indicate the increase in predicted straight-line velocity of the sperm as the head width is reduced and the increase in lateral movement as the head length is reduced. Predicted power consumption, however, shows a minimum close to the normal head aspect ratio

    Proyecto de un sistema mecanico para el transporte y alimentación al proceso de molienda de Carbon mineral usado como combustible industrial

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    OBJETIVO DE ESTA TESIS ES EL DESARROLLO DEL PROYECTO MECANICO DE SUN SISTEMA PARA LA TRANSPORTACION Y ALIMENTACION DEL CARBON DESDE LA SALA DE ALMACENAMIENTO HACIA LA MOLIENDA, CON UNA CAPACIDAD DE 100 TONELADAS POR HORA. TRATA ACERCA DEL CARBON VEGETAL COMO COMBUSTIBLE. SE TRATAN LOS SITEMAS DE TRANSPORTACION, ALIMENTACION Y EL ENSAMBLE DE ESTOS, EN CADA SISTEMA HUBO QUE DISEÑAR CIERTOS EQUIPO. SE CONSIDERARON CARACTERISTICAS DEL MATERIAL. SE DESCRIBE LOS REQUERIMIENTOS Y SISTEMAS PARA AUTOMATIZAR EL PROCESO DE TRANSPORTE Y ALIMENTACION. SE PRESENTA EL ANALISIS DE COSTO, COSTOS DE FABRICACION Y LA PUESTA EN MARCHA
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