9,029 research outputs found
Modelling and experimental investigation of carangiform locomotion for control
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.
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
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
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Architecture of the Short External Rotator Muscles of the Hip.
BackgroundMuscle architecture, or the arrangement of sarcomeres and fibers within muscles, defines functional capacity. There are limited data that provide an understanding of hip short external rotator muscle architecture. The purpose of this study was thus to characterize the architecture of these small hip muscles.MethodsEight muscles from 10 independent human cadaver hips were used in this study (n = 80 muscles). Architectural measurements were made on pectineus, piriformis, gemelli, obturators, quadratus femoris, and gluteus minimus. Muscle mass, fiber length, sarcomere length, and pennation angle were used to calculate the normalized muscle fiber length, which defines excursion, and physiological cross-sectional area (PCSA), which defines force-producing capacity.ResultsGluteus minimus had the largest PCSA (8.29 cm2) followed by obturator externus (4.54 cm2), whereas superior gemellus had the smallest PCSA (0.68 cm2). Fiber lengths clustered into long (pectineus - 10.38 cm and gluteus minimus - 10.30 cm), moderate (obturator internus - 8.77 cm and externus - 8.04 cm), or short (inferior gemellus - 5.64 and superior gemellus - 4.85). There were no significant differences among muscles in pennation angle which were all nearly zero. When the gemelli and obturators were considered as a single functional unit, their collective PCSA (10.00 cm2) exceeded that of gluteus minimus as a substantial force-producing group.ConclusionsThe key findings are that these muscles have relatively small individual PCSAs, short fiber lengths, and low pennation angles. The large collective PCSA and short fiber lengths of the gemelli and obturators suggest that they primarily play a stabilizing role rather than a joint rotating role
Reliability Evidence for the NC Teacher Evaluation Process Using a Variety of Indicators of Inter-Rater Agreement
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
R & D: Allocation: Reliability Vs. Customer Cost
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
On the cross-section of Dark Matter using substructure infall into galaxy clusters
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
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