Performance evaluation of an auction based manufacturing system using generalized stochastic Petri nets.

Auction Based Manufacturing is a form of Heterarchical control. Such a system relies upon the intelligence of individual machining centres to allocate parts to prospective machining centres which can do the next stage of machining. This approach eliminates the requirement of a costly pre process scheduling run, which can prove to be inappropriate in the event of unforseen machine breakdowns or changes in machining capacities. One of the major drawbacks is the lack of predictability of the exact behaviour of the shop floor. It is perceived that a method by which an operator can predict the most likely behaviour of the system is highly desirable in order to fine tune the control algorithms or rules to achieve optimality and make the right resource available at the right time for the right amount of duration. This thesis deals with the modelling and the performance evaluation of an Auction Based Manufacturing system that has multiple machining stages, multiple part types and multiple parts. Each part type has a process plan with multiple stages, further each stage can have multiple alternatives available. Four different models have been analyzed to understand the impact of control heuristics, tie-breaking rules, number of parts and machining rates on the overall system behaviour. (Abstract shortened by UMI.)Dept. of Industrial and Manufacturing Systems Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1995 .B57. Source: Masters Abstracts International, Volume: 34-02, page: 0843. Adviser: S. P. Dutta. Thesis (M.A.Sc.)--University of Windsor (Canada), 1995

The long-term outcomes of epilepsy surgery

<div><p>Objective</p><p>Despite modern anti-epileptic drug treatment, approximately 30% of epilepsies remain medically refractory and for these patients, epilepsy surgery may be a treatment option. There have been numerous studies demonstrating good outcome of epilepsy surgery in the short to median term however, there are a limited number of studies looking at the long-term outcomes. The aim of this study was to ascertain the long-term outcome of resective epilepsy surgery in a large neurosurgery hospital in the U.K.</p><p>Methods</p><p>This a retrospective analysis of prospectively collected data. We used the 2001 International League Against Epilepsy (ILAE) classification system to classify seizure freedom and Kaplan-Meier survival analysis to estimate the probability of seizure freedom.</p><p>Results</p><p>We included 284 patients who underwent epilepsy surgery (178 anterior temporal lobe resections, 37 selective amygdalohippocampectomies, 33 temporal lesionectomies, 36 extratemporal lesionectomies), and had a prospective median follow-up of 5 years (range 1–27). Kaplan-Meier estimates showed that 47% (95% CI 40–58) remained seizure free (apart from simple partial seizures) at 5 years and 38% (95% CI 31–45) at 10 years after surgery. 74% (95% CI 69–80) had a greater than 50% seizure reduction at 5 years and 70% (95% CI 64–77) at 10 years. Patients who had an amygdalohippocampectomy were more likely to have seizure recurrence than patients who had an anterior temporal lobe resection (p = 0.006) and temporal lesionectomy (p = 0.029). There was no significant difference between extra temporal and temporal lesionectomies. Hippocampal sclerosis was associated with a good outcome but declined in relative frequency over the years.</p><p>Conclusion</p><p>The vast majority of patients who were not seizure free experienced at least a substantial and long-lasting reduction in seizure frequency. A positive long-term outcome after epilepsy surgery is possible for many patients and especially those with hippocampal sclerosis or those who had anterior temporal lobe resections.</p></div

Management of impacted primary maxillary central incisor: A report

Impaction of primary tooth is a rare and unusual finding, particularly in the maxillary anterior segment. A variety of reasons are listed in literature for such condition. Here is a case report of impacted primary maxillary left central incisor in a 4-year-old child. The condition was diagnosed with the help of clinical examination, intraoral periapical radiograph, and cone-beam computed tomography. The tooth was surgically removed, and the patient was asked for periodic check-up

Spinal Cord Herniation into a Pseudomeningocele—A Delayed Presentation following a Traumatic Cervical Root Avulsion Injury

Background Spinal cord herniation into a traumatic pseudomeningocele is a rare clinical entity. We present the sixth known case and describe surgical management. Case Presentation A 44-year-old male presented with Brown-Sequard syndrome three decades after a cervical nerve root avulsion injury. Imaging revealed hemicord herniation into a C7/T1 pseudomeningocele in addition to extra-axial cord compression from further pseudomeningoceles. Significant clinical improvement was achieved following surgical repair. The radiological findings and technique for operative repair are described. Conclusion The case highlights this rare pathology and presentation, describes the surgical measures for repair of cord herniation, and provides evidence for the favorable outcome that can be achieved by surgical intervention

Prevalence and type of mesiodens among 3–14-year-old children in West Bengal: An institutional study

Introduction: Mesiodens is a supernumerary tooth which is most commonly located in between or palatal to the two maxillary central incisors. It is a developmental anomaly and can be single or multiple in number. The overall prevalence is reported between 0.09% and 2.05%. Materials and Methods: This is a longitudinal prospective study which was conducted in the Department of Pedodontics and Preventive Dentistry of Dr. R Ahmed Dental College and Hospital of West Bengal among 6332 children between 3 and 14 years age group. Clinical and radiographic evaluation was done regarding position, morphology, malocclusion, and eruption status. Results: About 0.69% of prevalence was noted. Nearly 70.45% were found in mixed dentition, 27.27% were in permanent dentition, and 2.27% were in primary dentition. Regarding shape, 68.18% were conical, 25% were tuberculate, and 6.81% were supplemental. Regarding position, 52.27% mesiodens were found to be present palatal to maxillary dental arch, 38.63% were found on the arch, and 9.09% were found buccal to the maxillary dental arch. Malocclusion was also evaluated. Moreover, a male predominance regarding the occurrence of mesiodens was also noted. Conclusion: The present study not only depicts the prevalence of mesiodens among 3–14-year-old children in West Bengal but also it aimed to give an insight regarding their form, number, position, and axis of orientation. It also aimed to evaluate the presence of malocclusion due to mesiodens if any so that planning of treatment can be done accordingly and more effectively

Automated subcortical volume estimation from 2D MRI in epilepsy and implications for clinical trials

Abstract Purpose Most techniques used for automatic segmentation of subcortical brain regions are developed for three-dimensional (3D) MR images. MRIs obtained in non-specialist hospitals may be non-isotropic and two-dimensional (2D). Automatic segmentation of 2D images may be challenging and represents a lost opportunity to perform quantitative image analysis. We determine the performance of a modified subcortical segmentation technique applied to 2D images in patients with idiopathic generalised epilepsy (IGE). Methods Volume estimates were derived from 2D (0.4 × 0.4 × 3 mm) and 3D (1 × 1x1mm) T1-weighted acquisitions in 31 patients with IGE and 39 healthy controls. 2D image segmentation was performed using a modified FSL FIRST (FMRIB Integrated Registration and Segmentation Tool) pipeline requiring additional image reorientation, cropping, interpolation and brain extraction prior to conventional FIRST segmentation. Consistency between segmentations was assessed using Dice coefficients and volumes across both approaches were compared between patients and controls. The influence of slice thickness on consistency was further assessed using 2D images with slice thickness increased to 6 mm. Results All average Dice coefficients showed excellent agreement between 2 and 3D images across subcortical structures (0.86–0.96). Most 2D volumes were consistently slightly lower compared to 3D volumes. 2D images with increased slice thickness showed lower agreement with 3D images with lower Dice coefficients (0.55–0.83). Significant volume reduction of the left and right thalamus and putamen was observed in patients relative to controls across 2D and 3D images. Conclusion Automated subcortical volume estimation of 2D images with a resolution of 0.4 × 0.4x3mm using a modified FIRST pipeline is consistent with volumes derived from 3D images, although this consistency decreases with an increased slice thickness. Thalamic and putamen atrophy has previously been reported in patients with IGE. Automated subcortical volume estimation from 2D images is feasible and most reliable at using in-plane acquisitions greater than 1 mm x 1 mm and provides an opportunity to perform quantitative image analysis studies in clinical trials. </jats:sec