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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

RAPID 3D TRACING OF THE MOUSE BRAIN NEUROVASCULATURE WITH LOCAL MAXIMUM INTENSITY PROJECTION AND MOVING WINDOWS

Han, Dong Hyeop 2009 August 1900 (has links)
Neurovascular models have played an important role in understanding neuronal function or medical conditions. In the past few decades, only small volumes of neurovascular data have been available. However, huge data sets are becoming available with high throughput instruments like the Knife-Edge Scanning Microscope (KESM). Therefore, fast and robust tracing methods become necessary for tracing such large data sets. However, most tracing methods are not effective in handling complex structures such as branches. Some methods can solve this issue, but they are not computationally efficient (i.e., slow). Motivated by the issue of speed and robustness, I introduce an effective and efficient fiber tracing algorithm for 2D and 3D data. In 2D tracing, I have implemented a Moving Window (MW) method which leads to a mathematical simplification and noise robustness in determining the trace direction. Moreover, it provides enhanced handling of branch points. During tracing, a Cubic Tangential Trace Spline (CTTS) is used as an accurate and fast nonlinear interpolation approach. For 3D tracing, I have designed a method based on local maximum intensity projection (MIP). MIP can utilize any existing 2D tracing algorithms for use in 3D tracing. It can also significantly reduce the search space. However, most neurovascular data are too complex to directly use MIP on a large scale. Therefore, we use MIP within a limited cube to get unambiguous projections, and repeat the MIP-based approach over the entire data set. For processing large amounts of data, we have to automate the tracing algorithms. Since the automated algorithms may not be 100 percent correct, validation is needed. I validated my approach by comparing the traced results to human labeled ground truth showing that the result of my approach is very similar to the ground truth. However, this validation is limited to small-scale real-world data due to the limitation of the manual labeling. Therefore, for large-scale data, I validated my approach using a model-based generator. The result suggests that my approach can also be used for large-scale real-world data. The main contributions of this research are as follows. My 2D tracing algorithm is fast enough to analyze, with linear processing time based on fiber length, large volumes of biological data and is good at handling branches. The new local MIP approach for 3D tracing provides significant performance improvement and it allows the reuse of any existing 2D tracing methods. The model-based generator enables tracing algorithms to be validated for large-scale real-world data. My approach is widely applicable for rapid and accurate tracing of large amounts of biomedical data.
82

Computer-Aided Diagnosis in Chest Radiographs

Kao, E-Fong 25 July 2006 (has links)
As computer technologies are developed rapidly in recent years, the ways to diagnose diseases also alter in clinical practice. Picture Archiving and Communication System (PACS) is an example that makes the diagnostic way for medical images change from view box to monitor. All types of medical images tend to be digitized and this makes it practical for helping doctor diagnose medical images via computer technologies. In this thesis, we propose a systemic approach to screen abnormalities in chest radiographs. First, a preprocess step identifying the view of chest radiographs is introduced. Second, a method is proposed for automated detection of gross abnormal opacity in chest radiographs. Third, computation time reduction is performed by subsampling. Finally, a computer-aided diagnosis system is implemented and evaluated in a clinical environment. Major technique used in this thesis is to analyze the projection profile obtained by projecting a chest image on to the mediolateral axis. The discriminant performance for each method is evaluated by using receiver operating characteristic (ROC) analysis. The results indicate that the proposed methods are potentially useful for screening abnormalities in chest radiographs.
83

Convergence Analysis for the Gradient-Projection Method with Different Choices of Stepsizes

Tsai, Jung-Jen 30 June 2009 (has links)
We consider the constrained convex minimization problem min x2C f(x) we will present gradient projection method which generates a sequence fxkg according to the formula xk+1 = PC(xk
84

Sur le développement des fonctions en séries ordonnées suivant les fonctions Xn et Yn suivi de Sur la théorie mathématique des cartes géographiques /

Bonnet, Ossian January 1900 (has links)
Thèse : Mécanique : Faculté des sciences de Paris : 1852. Thèse : Astronomie : Faculté des sciences de Paris : 1852. / Titre provenant de l'écran-titre.
85

Survivre au désespoir

Brolles, Lisbeth. Roussillon, René January 2002 (has links)
Reproduction de : Thèse de doctorat : Psychologie, mention Psychopathologie et psychologie cliniques : Lyon 2 : 2002. / Thèse : 2002LYO20063. Titre provenant de l'écran-titre. Bibliogr.. Index.
86

A guide to design and production for the video centric performance

Gazzillo, Eric 17 September 2013 (has links)
As modern technologies increase the capabilities of today’s stage, performances have grown to incorporate the use of video as a means to transform the stage in a way never seen before. Digital tools have unlocked designer’s ability to modify space and time in at the actual speed of light. While analogue film projections have been used on the stage for a number of years, it is the advent of digital video that has allowed performance art to develop a new interaction with a virtual world. I intend to explore and document the process behind a video centric performance. In this instance, I define video centric performance as an event in which the action on stage relies on the video content in some way to create a complete performance. Through this thesis I will focus on how the evolving definition of video has created particular workflows and methodologies to help adapt digital video techniques for the stage. Using several case studies, my workflows and methodologies will be developed and formed into a single written document. My written document is meant to be an all-encompassing guide. The goal in writing such a text is to provide single source education for artists looking to grow their understanding of video centric performances. Video production as well as stage production is a nuanced art, which can require years of practice to fully understand. Young artist may use higher education to grow their skills, or experienced professionals may use reading as a means of professional development. In both of these instances, members of the entertainment community are limited by the availability of a single source to bridge the gap between existing educational resources. Throughout the document, I avoid expanding on detailed topics that are covered by other professions, instead opting for an approach that weaves together the skills of performance artists, designers, technicians, cinematographers and animators in a way that focuses these talents towards the stage. / text
87

Imaging Profilometry For In Situ Measurement of Plasma Spray Coating Thickness

Trail, Nicholas January 2015 (has links)
Thermal Barrier Coatings (TBCs), and plasma spray coatings in general, require critical control over the deposited thickness to achieve reliable coating performance. Currently, the plasma spray industry quantifies thickness by sampling the part before and after TBC deposition. Approximate thickness is thus inferred from previous runs. However, process variability can allow errors to propagate in this result that leads to wasted time and resources, and can ultimately lead to non-reliant coatings. To this end, an in situ optical fringe profilometer is developed that enables coating thickness measurements across a 2-dimensional surface. The initial profilometer concept is explored through requirements and trade studies, leading to a hardware and algorithm design family and prototype build to capture and compare real-world data to simulation and model predictions. This initial result shows a viable path-forward and the ability to achieve micrometer-scale depth resolution. Modifications and alterations to the in situ profilometer are then explored to improve the performance limits achievable. In specific, industrial spray coatings operate by dropping fine-grain media into a high pressure gas line aimed through a plasma torch to impart enough thermal and kinetic energy to stick to the part surface. This presents a challenging operational environment for an optical depth measurement sensor, working with a variable high-temperature blackbody stray light source; constant part rotation and plasma gun movement; and a non-isolated vibration environment. As such, the concept of the profilometer is further adapted specific to this end-purpose, by developing and reviewing both dual-fringe projection and plenoptic imaging. These techniques allow an improvement to both the system micro- and macroscopic depth retrieval limits, allowing a method to solve for an extended range of phase ambiguities and relax object focus requirements (respectively). The end result is a system concept and algorithm design that presents a feasible manner for automated in situ geometry and depth measurements in the plasma spray industry. The in situ fringe profilometer work described herein allows a flexible path to recover object depth information remotely, and is especially relevant for asymmetric and complex non-planar geometries, which are experiencing renewed interest with additive manufacturing processes and generally quite common to the thermal spray industry.
88

Morphological Development of Uniglomerular Projection Neurons in the Olfactory Lobe of the Moth, Manduca sexta

Chandler, Larry January 2008 (has links)
The moth Manduca sexta has been a common model for the study of the insect olfactory systems. The neuronal architecture in the antennal lobes (ALs) of insects and in the olfactory lobes of vertebrates is similar in structure and development. In Manduca, as in other olfactory systems, sensory receptor neurons send axons into the AL where they form synapses with local interneurons (LNs) and projection neurons (PNs) within the structural units of glomeruli. Here, I present the morphological development of one type of interneuron, the uniglomerular projection neuron (uPN), in normal AL development and in AL development in the absence of olfactory receptor neurons (ORNs). Using fluorescent-dye labeling of uPNs and confocal microscopy, my results show that in the absence of ORNs, uPN dendritic arborization is uncharacteristic of that in normally developing ALs, reinforcing the concept that afferent input guides the development of architecture in sensory areas of the brain.
89

The design and construction of a projection device that will illustrate the various principles involved in orthographic projection and other pertinent principles related to drafting

Kindt, David John January 1965 (has links)
There is no abstract available for this thesis.
90

Out-of-body and near-death experiences : brain-state phenomena or glimpses of immortality?

Marsh, Michael N. January 2006 (has links)
What certainty is there for personal survival after death? Five key authors, critically analysed in this thesis, think that OB/ND experiences offer such assurances. Most OB/ND events follow severe clinical crises profoundly embarrassing cerebral function. At the nadir of brain function, invariably resulting in unconsciousness, authors aver that the escape of soul (Sabom), mind, or free consciousness (Moody, Ring, Grey, Fenwick), in providing glimpses of heaven, offers proof of immortality. I disagree. The semantic content of early-phase ND experiences reveals dream-like bizarreness and illogicality, consistent with de-activation of critical cortical controls. Conversely, late-phase experiences, tinged with 'moral' compulsions about earthly responsibilities, herald the progressive intrusion of conscious-awareness into that subconscious mentation. These experiences, abruptly terminating as conscious-awareness erupts, are transient - as demonstrated by narrative word counts - indicating origins from reawakening, not moribund, brains. My argument is underpinned by these latter crucial observations. Pain, intruding into ND phenomenology, is another occurrence hardly consistent with an escape of mind or 'free consciousness' into the hereafter. "Tunnel" phenomenology, a rapid movement from darkness into heavenly brightness, involves a retrospective synthesis of vestibular-generated rotation/accelerations, and a progressively enlarging and engulfing light, signalling re-establishment of an effective circulation to associative visual centres. The content of ND experiences, as with dreams, involves the temporo-parietal cortex. OB experiences derive from central vestibular activity (superior and inferior parietal lobules) in dormant, recumbent patients. Allied aberrations of allocentric space create bodily reduplications and sensed invisible presences. Thus, OB do not warrant "mystical" interpretations. The spiritual overtones accorded OB/ND experiences by authors are inconsistent with classical (Judaeo-Christian) accounts of divine disclosure. The eschatology adumbrated in published texts implies immortality, and seriously fails to embrace a preferred resurrectional eschatology as professed credally. I therefore conclude that OB/ND phenomenology, rather than offering alleged glimpses of eternity, reflects living, not dead, brains re-awakening to full conscious-awareness from antecedent metabolic insults.

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