8,452 research outputs found

    Modelling and experimental investigation of carangiform locomotion for control

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    We propose a model for planar carangiform swimming based on conservative equations for the interaction of a rigid body and an incompressible fluid. We account for the generation of thrust due to vortex shedding through controlled coupling terms. We investigate the correct form of this coupling experimentally with a robotic propulsor, comparing its observed behavior to that predicted by unsteady hydrodynamics. Our analysis of thrust generation by an oscillating hydrofoil allows us to characterize and evaluate certain families of gaits. Our final swimming model takes the form of a control-affine nonlinear system

    DNA methylation-based age prediction and telomere length in white blood cells and cumulus cells of infertile women with normal or poor response to ovarian stimulation.

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    An algorithm assessing the methylation levels of 353 informative CpG sites in the human genome permits accurate prediction of the chronologic age of a subject. Interestingly, when there is discrepancy between the predicted age and chronologic age (age acceleration or AgeAccel ), patients are at risk for morbidity and mortality. Identification of infertile patients at risk for accelerated reproductive senescence may permit preventative action. This study aimed to assess the accuracy of the epigenetic clock concept in reproductive age women undergoing fertility treatment by applying the age prediction algorithm in peripheral (white blood cells [WBCs]) and follicular somatic cells (cumulus cells [CCs]), and to identify whether women with premature reproductive aging (diminished ovarian reserve) were at risk of AgeAccel in their age prediction. Results indicated that the epigenetic algorithm accurately predicts age when applied to WBCs but not to CCs. The age prediction of CCs was substantially younger than chronologic age regardless of the patient\u27s age or response to stimulation. In addition, telomeres of CCs were significantly longer than that of WBCs. Our findings suggest that CCs do not demonstrate changes in methylome-predicted age or telomere-length in association with increasing female age or ovarian response to stimulation

    Classical and quantum fingerprinting with shared randomness and one-sided error

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    Within the simultaneous message passing model of communication complexity, under a public-coin assumption, we derive the minimum achievable worst-case error probability of a classical fingerprinting protocol with one-sided error. We then present entanglement-assisted quantum fingerprinting protocols attaining worst-case error probabilities that breach this bound.Comment: 10 pages, 1 figur

    Reliability Evidence for the NC Teacher Evaluation Process Using a Variety of Indicators of Inter-Rater Agreement

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    In this study, various statistical indexes of agreement were calculated using empirical data from a group of evaluators (n = 45) of early childhood teachers. The group of evaluators rated ten fictitious teacher profiles using the North Carolina Teacher Evaluation Process (NCTEP) rubric. The exact and adjacent agreement percentages were calculated for the group of evaluators. Kappa, weighted Kappa, Gwet’s AC1, Gwet’s AC2, and ICCs were used to interpret the level of agreement between the group of raters and a panel of expert raters. Similar to previous studies, Kappa statistics were low in the presence of high levels of agreement. Weighted Kappa and Gwet’s AC1 were less conservative than Kappa values. Gwet’s AC2 statistic was not defined for most evaluators, as there was an issue found with the statistic when raters do not use each category on the rating scale a minimum number of times. Overall, summary statistics for exact agreement were 68.7% and 87.6% for adjacent agreement across 2,250 ratings (45 evaluators ratings of ten profiles across five NCTEP Standards). Inter-rater agreement coefficients varied from .486 for Kappa, .563 for Gwet’s AC1, .667 for weighted Kappa, and .706 for Gwet’s AC2. While each statistic yielded different results for the same data, the inter-rater reliability of evaluators of early childhood teachers was acceptable or higher for the majority of this group of raters when described with summary statistics and using precise measures of inter-rater reliability

    On the cross-section of Dark Matter using substructure infall into galaxy clusters

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    We develop a statistical method to measure the interaction cross-section of Dark Matter, exploiting the continuous minor merger events in which small substructures fall into galaxy clusters. We find that by taking the ratio of the distances between the galaxies and Dark Matter, and galaxies and gas in accreting sub-halos, we form a quantity that can be statistically averaged over a large sample of systems whilst removing any inherent line-of-sight projections. In order to interpret this ratio as a cross-section of Dark Matter we derive an analytical description of sub-halo infall which encompasses; the force of the main cluster potential, the drag on a gas sub-halo, a model for Dark Matter self-interactions and the resulting sub-halo drag, the force on the gas and galaxies due to the Dark Matter sub-halo potential, and finally the buoyancy on the gas and Dark Matter. We create mock observations from cosmological simulations of structure formation and find that collisionless Dark Matter becomes physically separated from X-ray gas by up to 20h^-1 kpc. Adding realistic levels of noise, we are able to predict achievable constraints from observational data. Current archival data should be able to detect a difference in the dynamical behaviour of Dark Matter and standard model particles at 6 sigma, and measure the total interaction cross-section sigma/m with 68% confidence limits of +/- 1cm2g^-1. We note that this method is not restricted by the limited number of major merging events and is easily extended to large samples of clusters from future surveys which could potentially push statistical errors to 0.1cm^2g^-1.Comment: 14 pages, 11 figure

    R & D: Allocation: Reliability Vs. Customer Cost

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    The paper considers a monopoly firm with two possible R & D projects, one improving the product\u27s reliability and the second reducing the customers\u27 costs associated with product failure. The firm must choose one project or the other, and has a fixed budget for R & D expenditures. A condition on parameters is derived which indicates which project should be chosen. Monte Carlo analysis suggests that for the firm\u27s decision-making the most important parameter is a measure of the ambient level of technology. From society\u27s point of view, the most important parameter in determining the effect of the R & D choice on society is the size of the market being served by the firm
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