Distance Geometric Analysis on Manifolds

2003 ◽  
pp. 1-54 ◽  
Author(s):  
Steen Markvorsen
Keyword(s):  
Geometric Analysis ◽  
Analysis On Manifolds

Liquid crystalline ordering of paired helical filaments in neurofibrillary tangles of Alzheimer's disease

1986 ◽  
Vol 44 ◽  
pp. 348-349
Author(s):  
D.F. Clapin ◽  
V.J.A. Montpetit
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Liquid Crystalline ◽  
Amyloid Fibrils ◽  
Geometric Analysis ◽  
Paired Helical Filaments ◽  
Microscopic Level ◽  
Light Microscopic Level ◽  
Regular Spacing

Alzheimer's disease is characterized by the accumulation of abnormal filamentous proteins. The most important of these are amyloid fibrils and paired helical filaments (PHF). PHF are located intraneuronally forming bundles called neurofibrillary tangles. The designation of these structures as "tangles" is appropriate at the light microscopic level. However, localized domains within individual tangles appear to demonstrate a regular spacing which may indicate a liquid crystalline phase. The purpose of this paper is to present a statistical geometric analysis of PHF packing.

Geometric analysis

1976 ◽  
Vol 55 (2) ◽  
pp. 67
Author(s):  
C.A. Gladman ◽  
R.A. Williams
Keyword(s):  
Geometric Analysis

Geometry and Physics: Volume II

2018 ◽  
Keyword(s):  
Moduli Spaces ◽  
Mirror Symmetry ◽  
Geometric Analysis ◽  
Mathematical Physics ◽  
Poisson Geometry ◽  
Special Holonomy ◽  
Low Dimensional Topology ◽  
Generalized Complex Structures ◽  
Wide Range ◽  
Low Dimensional

These volumes contain the proceedings of the conference held at Aarhus, Oxford and Madrid in September 2016 to mark the seventieth birthday of Nigel Hitchin, one of the world’s foremost geometers and Savilian Professor of Geometry at Oxford. The proceedings contain twenty-nine articles, including three by Fields medallists (Donaldson, Mori and Yau). The articles cover a wide range of topics in geometry and mathematical physics, including the following: Riemannian geometry, geometric analysis, special holonomy, integrable systems, dynamical systems, generalized complex structures, symplectic and Poisson geometry, low-dimensional topology, algebraic geometry, moduli spaces, Higgs bundles, geometric Langlands programme, mirror symmetry and string theory. These volumes will be of interest to researchers and graduate students both in geometry and mathematical physics.

scholarly journals Hip geometry in hip fracture patients in Greenland occurring over a 7.7-year period

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Inuuteq Fleischer ◽  
Mogens Laursen ◽  
Stig Andersen
Keyword(s):  
Hip Fracture ◽  
Femoral Neck ◽  
Fracture Risk ◽  
Cortical Thickness ◽  
Geometric Analysis ◽  
Osteoporotic Fractures ◽  
Premature Death ◽  
Neck Length ◽  
Hip Geometry ◽  
Lesser Trochanter

Abstract Background Hip geometry influences hip fracture risk. Hip fractures are common, and they are associated with pain, disability, premature death and marked costs on society. Osteoporotic fractures are frequent in Arctic populations and increase with advancing age in this society with a steep rise in life expectancy. Greenland Inuit is a distinct ethnic group, and data on hip geometry is missing. We thus aimed to describe hip geometry in 7.7 years of consecutive hip fracture patients in Greenland. Methods We evaluated collodiaphysial angle, femoral neck length, the outer and inner diameter of the femur at 2 and 5 centimetres below the centre of the lesser trochanter and the cortical thickness from pelvic and hip radiographs in all patients operated in Greenland over 7.7 years. We included all 84 patients with one non-fractured hip visible for geometric analysis. Analyses were conducted in duplicate. Results We found a collodiaphysial angle of 134.8/132.6o in men/women (p = 0.06) and a femoral neck length of 38.0/33.9 mm in men/women (p = 0.001). Cortical thickness was affected by sex in the adjusted analysis (p < 0.001). Cortical thickness index at 5 cm below the centre of the lesser trochanter decreased with age (p = 0.026) and may be influenced by height (2 cm below the centre of the lesser trochanter, p = 0.053). Conclusion Our findings differed from European data and suggest a delicate balance in hip geometry in Arctic populations. Ethnic peculiarities influence the structure of the hip and may influence fracture risk. A focus on hip geometry and risk factors for osteoporotic fractures in Arctic populations is warranted.

Semi-automated cerebral aneurysm segmentation and geometric analysis for WEB sizing utilizing a cloud-based computational platform

2021 ◽  
pp. 159101992110091
Author(s):  
Ansaar T Rai ◽  
Ryan G Brotman ◽  
Gerald R Hobbs ◽  
SoHyun Boo
Keyword(s):  
Geometric Analysis ◽  
Good Reliability ◽  
Moderate Agreement ◽  
Manual Methods ◽  
Web Device ◽  
Computational Platform ◽  
Neck Diameter ◽  
Aneurysm Diameter ◽  
Intra Class Correlation Coefficient ◽  
The Web

Background Accurate aneurysm measurements are important for selecting the WEB device. The objective was to validate a cloud-based platform, SurgicalPreview (SP) against manual measurements for aneurysm analysis. Methods Two sets of measurements each for SP and manual methods were obtained for 40 aneurysms. Reliability and agreement were assessed with intra-class correlation coefficient (ICC) and Bland-Altman plots respectively. Kappa coefficient was used to assess agreement for predicting WEB size. Results There was good reliability for repeat SP measurements: aneurysm diameter (ICC-1, 95%CI 0.98–1), height (ICC-1, 95%CI 0.99–1) and neck diameter (ICC-0.96, 95%CI 0.93–0.98). There was good reliability for the two manual diameter (ICC-0.97, 95%CI 0.9–0.97) and height (ICC-0.93, 95%CI 0.87–0.96) measurements and moderate for neck diameter (ICC-0.76, 95%CI 0.54–0.87). There was greater agreement for SP versus manual repeat measurements on Bland-Altman plots. Reliability between the SP and manual methods was good for aneurysm diameter (ICC-0.98, 95%CI 0.95–1) and height (ICC-0.96, 95%CI-0.93–0.98) and moderate for neck. (ICC-0.6, 95%CI -0.22–0.87). The Bland-Altman plots confirmed better agreement between the two methods for the aneurysm diameter and height than the neck. There was strong agreement between the methods for predicting the WEB diameter (Kappa-0.84, 95%CI 0.71–0.97) and moderate for predicting WEB height (Kappa-0.66, 95%CI 0.43–0.89). There was moderate agreement for predicted versus deployed WEB diameter: SP (Kappa-0.56, 95%CI 0.38–0.74), Manual (Kappa-0.53, 95%CI 0.34–0.71). Conclusion The SurgicalPreview® had greater agreement for repeat measurements. There was good reliability between the two methods for predicting WEB diameter and height and moderate agreement between predicted versus deployed WEB diameter.

Sign in / Sign up

Export Citation Format

Share Document