University of Waterloo

About: University of Waterloo is a education organization based out in Waterloo, Ontario, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 36093 authors who have published 93906 publications receiving 2948139 citations. The organization is also known as: UW & uwaterloo.

Bayesian galaxy shape measurement for weak lensing surveys – III. Application to the Canada–France–Hawaii Telescope Lensing Survey

Abstract: A likelihood-based method for measuring weak gravitational lensing shear in deep galaxy surveys is described and applied to the Canada–France–Hawaii Telescope (CFHT) Lensing Survey (CFHTLenS) CFHTLenS comprises 154 deg^2 of multi-colour optical data from the CFHT Legacy Survey, with lensing measurements being made in the i′ band to a depth i′_(AB) < 247, for galaxies with signal-to-noise ratio ν_(SN) ≳ 10 The method is based on the lensfit algorithm described in earlier papers, but here we describe a full analysis pipeline that takes into account the properties of real surveys The method creates pixel-based models of the varying point spread function (PSF) in individual image exposures It fits PSF-convolved two-component (disc plus bulge) models to measure the ellipticity of each galaxy, with Bayesian marginalization over model nuisance parameters of galaxy position, size, brightness and bulge fraction The method allows optimal joint measurement of multiple, dithered image exposures, taking into account imaging distortion and the alignment of the multiple measurements We discuss the effects of noise bias on the likelihood distribution of galaxy ellipticity Two sets of image simulations that mirror the observed properties of CFHTLenS have been created to establish the method's accuracy and to derive an empirical correction for the effects of noise bias

A multigrid method based on the additive correction strategy

Abstract: The solution of large sets of equations is required when discrete methods are used to solve fluid flow and heat transfer problems The cost of the solution often becomes prohibitive when the coefficients of the algebraic equations become strongly anisotropic or when the number of equations in the set becomes large The present paper demonstrates how the additive correction method of Settari and Aziz can be used and extended to improve the convergence rate for two- and three-dimensional problems when the coefficients are anisotropic Such methods are interpreted as simple multigrid methods With this as the basis a new general multigrid method is developed that has attractive properties The efficiency of the new method is compared to that of a conventional multigrid method, and its performance is demonstrated on other problems

Aptamer-based biosensors for biomedical diagnostics.

Abstract: Aptamers are single-stranded nucleic acids that selectively bind to target molecules. Most aptamers are obtained through a combinatorial biology technique called SELEX. Since aptamers can be isolated to bind to almost any molecule of choice, can be readily modified at arbitrary positions and they possess predictable secondary structures, this platform technology shows great promise in biosensor development. Over the past two decades, more than one thousand papers have been published on aptamer-based biosensors. Given this progress, the application of aptamer technology in biomedical diagnosis is still in a quite preliminary stage. Most previous work involves only a few model aptamers to demonstrate the sensing concept with limited biomedical impact. This Critical Review aims to summarize progress that might enable practical applications of aptamers for biological samples. First, general sensing strategies based on the unique properties of aptamers are summarized. Each strategy can be coupled to various signaling methods. Among these, a few detection methods including fluorescence lifetime, flow cytometry, upconverting nanoparticles, nanoflare technology, magnetic resonance imaging, electronic aptamer-based sensors, and lateral flow devices have been discussed in more detail since they are more likely to work in a complex sample matrix. The current limitations of this field include the lack of high quality aptamers for clinically important targets. In addition, the aptamer technology has to be extensively tested in a clinical sample matrix to establish reliability and accuracy. Future directions are also speculated to overcome these challenges.