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Man Sang Wong - One of the best experts on this subject based on the ideXlab platform.
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a purpose design computational method for estimation of plane of Maximum Curvature in adolescent idiopathic scoliosis
Studies in health technology and informatics, 2021Co-Authors: Man Sang WongAbstract:Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional (3D) deformity, and the plane of Maximum Curvature (PMC) is proposed to reflect these clinical features, which refers to a vertical plane presenting the Maximum projected spinal Curvature and its parameters include the PMC Cobb and orientation (angle between PMC and sagittal planes). This study aimed to develop a computational method (CM) for PMC estimation. Twenty-nine patients with AIS and computed tomography (CT) images were recruited. For CT, PMC was determined by rotating a vertical plane about its vertical axis with 5° increment until the Maximum Cobb angle was measured. For CM, PMC was estimated via identifying the eight points (the corner points of the superior and inferior endplates of the upper and lower end-vertebrae respectively) in the coronal and lateral CT images. Two experienced raters repeated the PMC estimation three times with one-week interval. The intra-class correlation coefficient (ICC) and Bland-Altman method were used for statistical analysis. Twenty-seven right thoracic curves (RTs) (mean Cobb: 46.1°±12.4°) and 23 left thoracolumbar/lumbar (LTLs/LLs) (mean Cobb: 30.6°±11.1°) were analysed. The intra- and inter-rater ICC values were >0.91 and 0.84 in RTs and LTLs/LLs, respectively. The PMCs obtained from the CM and CT were showed good agreement was also observed between the PMCs obtained from the two methods according to ICC (>0.90) and Bland-Altman method assessments. This purpose-design computational method could provide reliable and valid estimation of PMCs for AIS, which has potential to be used as an alternative for 3D assessment.
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estimation of plane of Maximum Curvature for the patients with adolescent idiopathic scoliosis via a purpose design computational method
European Spine Journal, 2021Co-Authors: Winnie C W Chu, Man Sang WongAbstract:The coronal Cobb angle is commonly used for assessing the adolescent idiopathic scoliosis (AIS); however, it may underestimate the severity of AIS while the plane of Maximum Curvature (PMC) could be a promising descriptor for three-dimensional assessment of AIS. This study aimed to develop a computational method (CM) for estimating the PMC based on the coronal and sagittal images of the spine, and to verify the results with computed tomography (CT). Twenty-eight thoracic and 24 lumbar curves from 30 subjects with AIS were analysed. For the CM, PMC was estimated via identifying the two corner points at the superior endplate of upper-end vertebra and the inferior endplate of lower-end vertebra in the coronal and sagittal CT images separately (eight corner points in total). For the CT, PMC was determined through rotating the spine images axially until the Maximum Cobb angle was found. Intraclass correlation coefficient (ICC), Bland–Altman method and linear regression analysis were used for the statistical analyses. The high ICC values (intra- > 0.91; inter- > 0.84) suggested very good intra- and inter-rater reliability of the CM in PMC estimation. The high ICC values (> 0.91) and assessment of Bland–Altman method demonstrated a good agreement between the PMC acquired using the CM and CT. The generated linear regression equations (R2 > 0.69) could allow to estimate the PMC (originally measured through the CT) via the CM. The developed computational method could estimate reliable and valid PMC for the patients with AIS, and become feasible for three-dimensional assessment of AIS. III.
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assessment of the plane of Maximum Curvature for patients with adolescent idiopathic scoliosis via computed tomography
Prosthetics and Orthotics International, 2020Co-Authors: Winnie C W Chu, Man Sang WongAbstract:Background:In the assessment of three-dimensional features of adolescent idiopathic scoliosis, the plane of Maximum Curvature was compared with the coronal Cobb angle.Objectives:To investigate the ...
C Q Ru - One of the best experts on this subject based on the ideXlab platform.
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surface tension induced stress concentration around a nanosized hole of arbitrary shape in an elastic half plane
Meccanica, 2014Co-Authors: C Q RuAbstract:This paper studies surface tension-induced stress concentration around a nanosized hole of arbitrary shape inside an elastic half-plane. Of particular interest is the Maximum hoop stress on the hole’s boundary with relation to the point of Maximum Curvature and the distance between the hole and the free surface of the half-plane. The shape of the hole is characterized by a conformal mapping which maps the exterior of the hole onto the exterior of the unit circle in the image plane. On using the technique of conformal mapping and analytic continuation, the complex potentials of the half-plane are expressed in a series form with unknown coefficients to be determined by Fourier expansion method. Detailed numerical results are shown for elliptical, triangular, square and rectangular holes. Two basic conclusions are that the hoop stress increases with decreasing hole size and the Maximum hoop stress generally appears nearby but not exactly at the point of Maximum Curvature. In addition, it is shown that the hoop stress nearby the point of Maximum Curvature on the hole’s boundary increases rapidly with decreasing distance between the hole and the free surface of the half-plane. On the other hand, if the distance between the hole and the free surface is more than three times the hole size, the effect of the free surface on the stress concentration around the hole is ignorable and the elastic half-plane can be treated approximately as an elastic whole plane.
Winnie C W Chu - One of the best experts on this subject based on the ideXlab platform.
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estimation of plane of Maximum Curvature for the patients with adolescent idiopathic scoliosis via a purpose design computational method
European Spine Journal, 2021Co-Authors: Winnie C W Chu, Man Sang WongAbstract:The coronal Cobb angle is commonly used for assessing the adolescent idiopathic scoliosis (AIS); however, it may underestimate the severity of AIS while the plane of Maximum Curvature (PMC) could be a promising descriptor for three-dimensional assessment of AIS. This study aimed to develop a computational method (CM) for estimating the PMC based on the coronal and sagittal images of the spine, and to verify the results with computed tomography (CT). Twenty-eight thoracic and 24 lumbar curves from 30 subjects with AIS were analysed. For the CM, PMC was estimated via identifying the two corner points at the superior endplate of upper-end vertebra and the inferior endplate of lower-end vertebra in the coronal and sagittal CT images separately (eight corner points in total). For the CT, PMC was determined through rotating the spine images axially until the Maximum Cobb angle was found. Intraclass correlation coefficient (ICC), Bland–Altman method and linear regression analysis were used for the statistical analyses. The high ICC values (intra- > 0.91; inter- > 0.84) suggested very good intra- and inter-rater reliability of the CM in PMC estimation. The high ICC values (> 0.91) and assessment of Bland–Altman method demonstrated a good agreement between the PMC acquired using the CM and CT. The generated linear regression equations (R2 > 0.69) could allow to estimate the PMC (originally measured through the CT) via the CM. The developed computational method could estimate reliable and valid PMC for the patients with AIS, and become feasible for three-dimensional assessment of AIS. III.
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assessment of the plane of Maximum Curvature for patients with adolescent idiopathic scoliosis via computed tomography
Prosthetics and Orthotics International, 2020Co-Authors: Winnie C W Chu, Man Sang WongAbstract:Background:In the assessment of three-dimensional features of adolescent idiopathic scoliosis, the plane of Maximum Curvature was compared with the coronal Cobb angle.Objectives:To investigate the ...
Francisco Taboada - One of the best experts on this subject based on the ideXlab platform.
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inspiratory vs expiratory pressure volume curves to set end expiratory pressure in acute lung injury
Intensive Care Medicine, 2005Co-Authors: Guillermo M Albaiceta, Luis H Luyando, Diego Parra, Rafael Menendez, Juan Calvo, P R Pedreira, Francisco TaboadaAbstract:Objective To study the effects of two levels of positive end-expiratory pressure (PEEP), 2 cmH2O above the lower inflection point of the inspiratory limb and equal to the point of Maximum Curvature on the expiratory limb of the pressure-volume curve, in gas exchange, respiratory mechanics, and lung aeration.
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application of continuous positive airway pressure to trace static pressure volume curves of the respiratory system
Critical Care Medicine, 2003Co-Authors: Guillermo M Albaiceta, Ana Villagrá, Enrique Piacentini, Josefina Lopezaguilar, Francisco Taboada, Lluis BlanchAbstract:Objective: To evaluate a new technique for pressure-volume curve tracing. Design: Prospective experimental study. Setting: Animal research laboratory. Subjects: Six anesthetized rats. Interventions: Two pressure-volume curves were obtained by means of the super-syringe method (gold standard) and the continuous positive airway pressure (CPAP) method. For the CPAP method, the ventilator was switched to CPAP and the pressure level was raised from 0 to 50 cm H 2 O in 5 cm H 2 O steps and then decreased, while we measured lung volume using respiratory inductive plethysmography. Thereafter, lung injury was induced using very high-volume ventilation. Following injury, two further pressure-volume curves were traced. Pressure-volume pairs were fitted to a mathematical model. Measurements and Main Results: Pressure-volume curves were equivalent for each method, with intraclass correlation coefficients being higher than .75 for each pressure level measured. Bias and precision for volume values were 0.46 ± 0.875 mL in basal measurements and 0.31 ± 0.67 mL in postinjury conditions. Lower and upper inflection points on the inspiratory limb and Maximum Curvature point on the deflation limb obtained using both methods and measured by regression analysis also were correlated, with intraclass correlation coefficients (95% confidence interval) being .97 (.58, .99), .85 (.55, .95), and .94 (.81, .98) (p <.001 for each one). When inflection points were estimated by observers, the correlation coefficient between methods was.90 (.67,.98) for lower inflection points (p <.001). However, estimations for upper inflection points and Maximum Curvature point were significantly different. Conclusions: The CPAP method for tracing pressure-volume curves is equivalent to the super-syringe method. It is easily applicable at the bedside, avoids disconnection from the ventilator, and can be used to obtain both the inspiratory and the deflation limbs of the pressure-volume curve. Use of regression techniques improves determination of inflection points.
Elisabeth Smela - One of the best experts on this subject based on the ideXlab platform.
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bending actuators with Maximum Curvature and force and zero interfacial stress
Journal of Intelligent Material Systems and Structures, 2007Co-Authors: Benjamin Shapiro, Elisabeth SmelaAbstract:Stress at the interface of a bilayer actuator can lead to delamination, and this stress increases with the difference in the Young's moduli of the two layers. In this study, an actuator that includes a third 'buffer' layer is modeled, and it is shown how optimization of the thickness and modulus of this layer can reduce stress at that interface to zero, with no loss of Curvature and only a small loss in force. A polypyrrole (PPy)/conducting polymer/gold trilayer is used as a model system, with the aim of reducing stress at the weak polymer/gold interface. For a 450 nm thick PPy layer with a Young's modulus of 0.2 GPa, an intermediate layer of 150 nm thickness with a modulus of 5 GPa reduces the stress to zero with no loss of Curvature and only a 7% loss in force compared to the bilayer case.