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Institution

University of Waterloo

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


Papers
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Journal ArticleDOI
TL;DR: Application of a method of spectral analysis suitable for selectively extracting very-low-frequency components to HRV spectral analyses indicated that it might enable one to observe more clearly the low- and high- frequencies characteristic of autonomic control of heart rate.
Abstract: Heart rate variability (HRV) spectra are typically analyzed for the components related to low- (less than 0.15 Hz) and high- (greater than 0.15 Hz) frequency variations. However, there are very-low...

362 citations

Journal ArticleDOI
TL;DR: In this paper, a method for treating fluid-structure interaction of fracturing structures under impulsive loads is described, which does not require any modifications when the structure fails and allows fluid to flow through openings between crack surfaces.
Abstract: A method for treating fluid-structure interaction of fracturing structures under impulsive loads is described. The coupling method is simple and does not require any modifications when the structure fails and allows fluid to flow through openings between crack surfaces. Both the fluid and the structure are treated by meshfree methods. For the structure, a Kirchhoff-Love shell theory is adopted and the cracks are treated by introducing either discrete (cracking particle method) or continuous (partition of unity-based method) discontinuities into the approximation. Coupling is realized by a master-slave scheme where the structure is slave to the fluid. The method is aimed at problems with high-pressure and low-velocity fluids, and is illustrated by the simulation of three problems involving fracturing cylindrical shells coupled with fluids.

362 citations

Journal ArticleDOI
TL;DR: While vitamins B1 and B12 did not affect growth significantly, EPA yield was increased by 65% by B12 supplementation, and the EPA content of total fatty acids increased with increasing concentrations of nitrate and urea.
Abstract: Detailed studies were carried out on the effects of nitrogen source, phosphate, sodium chloride, growth factors, precursors, CO2, temperature, initial pH, and inoculum size on biomass and eicosapentaenoic acid (EPA) production by Phaeodactylum tricornutum. The EPA content of total fatty acids increased with increasing concentrations of nitrate and urea. Sodium chloride was not required for growth or EPA production. While vitamins B1 and B12 did not affect growth significantly, EPA yield was increased by 65% by B12 supplementation. Maximum EPA production occurred when the air gassing supply was supplemented with 1% CO2. Optimum culture temperature and initial pH for EPA production were 21.5 to 23 degrees C and 7.6, respectively. EPA yields of up to 133 mg/liter of culture were observed. EPA constituted up to 30 to 40% of total fatty acids.

362 citations

Journal ArticleDOI
TL;DR: A series of normalized and generalized metrics based on the important ingredients of SSIM are constructed and it is shown that such modified measures are valid distance metrics and have many useful properties, among which the most significant ones include quasi-convexity, a region of convexity around the minimizer, and distance preservation under orthogonal or unitary transformations.
Abstract: Since its introduction in 2004, the structural similarity (SSIM) index has gained widespread popularity as a tool to assess the quality of images and to evaluate the performance of image processing algorithms and systems. There has been also a growing interest of using SSIM as an objective function in optimization problems in a variety of image processing applications. One major issue that could strongly impede the progress of such efforts is the lack of understanding of the mathematical properties of the SSIM measure. For example, some highly desirable properties such as convexity and triangular inequality that are possessed by the mean squared error may not hold. In this paper, we first construct a series of normalized and generalized (vector-valued) metrics based on the important ingredients of SSIM. We then show that such modified measures are valid distance metrics and have many useful properties, among which the most significant ones include quasi-convexity, a region of convexity around the minimizer, and distance preservation under orthogonal or unitary transformations. The groundwork laid here extends the potentials of SSIM in both theoretical development and practical applications.

362 citations

Journal ArticleDOI
TL;DR: FOF was significantly associated with a qualitative estimate of postural control in PD; individuals with PD who had a greater degree of posture impairment reported greater FOF, and an estimate of FOF may help to explain quantitative postural instability in PD.
Abstract: This study investigated the relationship between fear of falling (FOF) and qualitative and quantitative postural control in Parkinson's disease (PD). Fifty-eight nondemented PD patients were studied along with age-matched healthy controls. The degree of FOF was estimated using the Activities-specific Balance Confidence scale. Qualitative postural control was evaluated using a component of the Unified Parkinson Disease Rating Scale. Postural control was quantified, using centre of pressure measures obtained from a force plate, for eight standing balance tests of different challenges. The results showed that FOF was more evident for PD patients when compared with healthy individuals of similar age. Furthermore, FOF was significantly associated with a qualitative estimate of postural control in PD; individuals with PD who had a greater degree of posture impairment reported greater FOF. The results also showed that an estimate of FOF may help to explain quantitative postural instability in PD. FOF, when coupled with a qualitative estimate of postural control, was able to explain a greater amount of variation in quantitative balance performance for five of the eight balance tests. When considered independently, the qualitative measure of postural control, in general, could not well predict quantitative balance performance. The greater degree of FOF and its possible association with altered postural control suggests that FOF should be considered as an important, independent risk factor in the assessment and treatment of postural instability in patients with PD.

362 citations


Authors

Showing all 36498 results

NameH-indexPapersCitations
John J.V. McMurray1781389184502
David A. Weitz1781038114182
David Taylor131246993220
Lei Zhang130231286950
Will J. Percival12947387752
Trevor Hastie124412202592
Stephen Mann12066955008
Xuan Zhang119153065398
Mark A. Tarnopolsky11564442501
Qiang Yang112111771540
Wei Zhang112118993641
Hans-Peter Seidel112121351080
Theodore S. Rappaport11249068853
Robert C. Haddon11257752712
David Zhang111102755118
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20241
2023213
2022701
20215,359
20205,388
20195,200