A new particle image velocimetry technique for three-dimensional flows.

A technique has been developed whereby the three-dimensional (3-D) motion of particles in a fluid flow is automatically analyzed. A CCD (Charge Coupled Device) camera was used in conjunction with a tri-split lens and a mirror arrangement to simultaneously record stereo and orthogonal views of the particle-seeded flow field. A two-stage calibration algorithm has been implemented to determine the coefficients for each view separately. The images were digitally enhanced to aid in separating the particles from the background. Algorithms were developed to match individual particles in the stereo and orthogonal views. The positional information obtained from the stereo views was used to match the particle images in orthogonal views. A 3-D cross-correlation algorithm has been implemented to follow the particles from frame to frame and compute the velocity vectors. Experiments have been carried out to obtain the velocity profiles in a cubical test section. The results obtained from the experimental investigation were compared with numerical simulation data obtained from FLUENT and STAR-CD.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1995 .K87. Source: Dissertation Abstracts International, Volume: 56-11, Section: B, page: 6349. Co-Advisers: K. Sridihar; G. W. Rankin. Thesis (Ph.D.)--University of Windsor (Canada), 1995

Study of surface texture using Fourier transform methods.

Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1989 .K873. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.Sc.)--University of Windsor (Canada), 1989

Efficacy of Endoscopic Dilation of Gastroduodenal Crohn's Disease Strictures: A Systematic Review and Meta-Analysis of Individual Patient Data

Background & Aims: Little is known about the effects of endoscopic balloon dilation (EBD) for strictures of the upper gastrointestinal (UGI) tract in patients with Crohn's disease (CD). We performed a pooled analysis of the efficacy and safety of EBD for UGI CD-associated strictures. Methods: We searched Embase, Medline, and the Cochrane library, as well as bibliographies of relevant articles, for cohort studies of adults with CD and strictures of the stomach or duodenum (up to the ligament of Treitz) who underwent EBD through December 2016. We obtained data from 7 international referral centers on 94 patients who underwent 141 EBDs. We performed a patient-level meta-analysis of data from published and unpublished cohort studies to determine mechanical and clinical success. We performed a time-to-event analysis to assess symptom recurrence and need for redilation or surgery. The patients analyzed had strictures of the duodenum (n = 107), stomach (n = 30), or spanning both (n = 4). Results: The rate of technical success for EBD was 100%, with 87% short-term clinical efficacy; major complications arose from 2.9% of all procedures. During a median follow-up period of 23.1 months, 70.5% of patients had a recurrence of symptoms, 59.6% required redilation, and 30.8% required surgical intervention. Patients whose disease was located in the small bowel had a higher risk for symptom recurrence (hazard ratio [HR], 2.1; P = .003). Asian race (HR, 2.8; P < .001) and location of disease in the small bowel (HR, 1.9; P = .004) increased the need for redilation. Prestenotic dilation was a risk factor for needing surgery earlier (HR, 1.9; P = .001). Conclusions: In a meta-analysis, we found EBD for CD-associated strictures of the UGI to be an effective alternative to surgery, with a high rate of short-term technical and clinical success, moderate long-term efficacy, and an acceptable rate of complications

Histopathology Scoring Systems of Stenosis Associated With Small Bowel Crohn's Disease: A Systematic Review

Background & Aims: Stenosis is a common complication of Crohn's disease (CD) that has no effective medical therapy. Development of antifibrotic agents will require testing in randomized controlled trials. Computed tomography enterography- and magnetic resonance enterography-based technologies might be used to measure outcomes in these trials. These approaches have been validated in studies of patients with symptomatic strictures who underwent imaging evaluations followed by resection with histopathologic grading of the intestinal tissue for inflammation and/or fibrosis (the reference standard). Imaging findings have correlated with findings from quantitative or semiquantitative histologic evaluation of the degree of fibromuscular stenosis and/or inflammation on the resection specimen. However, it is not clear whether histologic findings are an accurate reference standard. We performed a systematic review of all published histologic scoring systems used to assess stenosing CD. Methods: We performed a comprehensive search of Embase and MEDLINE of studies through March 13, 2019, that used a histologic scoring system to characterize small bowel CD and assessed inflammatory and fibrotic alterations within the same adult individual. All scores fitting the criteria were included in our analysis, independent of the presence of stricturing disease, as long as inflammation and fibrosis were evaluated separately but in the same scoring system. Results: We observed substantial heterogeneity among the scoring systems, which were not derived from modern principles for evaluative index development. None had undergone formal validity or reliability testing. None of the existing indices had been constructed according to accepted methods for the development of evaluative indices. Basic knowledge regarding their operating properties were lacking. Specific indices for evaluating the important pathologic component of myofibroblast hypertrophy or hyperplasia have not been proposed. Conclusions: In a systematic review of publications, we found a lack of validated histopathologic scoring systems for assessment of fibromuscular stenosis. Data that describe the operating properties of existing cross-sectional imaging techniques for stenosing CD should be questioned. Development and validation of a histopathology index is an important research priority