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Given an n × n symmetric positive definite matrix A and a vector c, two numerical methods for approximating A 1/2 c are developed, analyzed, and computationally tested. The first method applies a Newton iteration to a specific nonlinear system to approximate A 1/2 c while the second method applies a step-control method to numerically solve a specific(More)
The use of high resolution peripheral quantitative computed tomography (HR-pQCT) and in vivo micro-CT for studies of bone disease and treatment has become increasingly common, and with these methods comes large quantities of data requiring analysis. A simple, robust, and fully-automated segmentation algorithm is presented that efficiently segments bone(More)
Cleft lip and palate (CL/P), as is true of many craniofacial malformations in humans, is etiologically complex and highly variable in expression. A/WySn mice are an intriguing model for human CL/P because they develop this dysmorphology with a variable expression pattern, incomplete penetrance and frequent unilateral expression on a homogeneous genetic(More)
Lysyl oxidase (LOX), an extracellular matrix remodeling enzyme, appears to have a role in promoting breast cancer cell motility and invasiveness. In addition, increased LOX expression has been correlated with decreases in both metastases-free, and overall survival in breast cancer patients. With this background, we studied the ability of(More)
Quantitative cortical microarchitectural end points are important for understanding structure-function relations in the context of fracture risk and therapeutic efficacy. This technique study details new image-processing methods to automatically segment and directly quantify cortical density, geometry, and microarchitecture from HR-pQCT images of the distal(More)
Vertebral fractures may result in pain, loss of height, spinal instability, kyphotic deformity and ultimately increased morbidity. Fracture risk can be estimated by vertebral bone mineral density (BMD). However, vertebral fractures may be better defined by more selective methods that account for micro-architecture. Our aim was to quantify regional(More)
A new approach for the study of geometric morphometrics is presented based on well-established image processing techniques in a novel combination to support high-throughput analysis necessary for large-scale determination of genotype-phenotype relationships. The method retains full 3-D data, and avoids manual landmark selection. Micro-computed tomography(More)
Bone structure is an integral determinant of bone strength. The availability of high resolution peripheral quantitative computed tomography (HR-pQCT) has made it possible to measure three-dimensional bone microarchitecture and volumetric bone mineral density in vivo, with accuracy previously unachievable and with relatively low-dose radiation. Recent(More)
High-frequency, low-magnitude vibration enhances bone formation ostensibly by mimicking normal postural muscle activity. We tested this hypothesis by examining whether daily exposure to low-magnitude vibration (VIB) would maintain bone in a muscle disuse model with botulinum toxin type A (BTX). Female 16-18 wk old BALB/c mice (N = 36) were assigned to(More)
In vivo micro-computed tomography (microCT) is a new method to monitor longitudinal changes of bone micro-architecture. Common animal models of bone diseases are mice and rats, and it is important to know the reproducibility of the bone measurements in order to correctly interpret results. When performing baseline and follow-up acquisitions, variation in(More)