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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.
711

Integrated Mobility and Service Management for Future All-IP Based Wireless Networks

He, Weiping 24 April 2009 (has links)
Mobility management addresses the issues of how to track and locate a mobile node (MN) efficiently. Service management addresses the issues of how to efficiently deliver services to MNs. This dissertation aims to design and analyze integrated mobility and service management schemes for future all-IP based wireless systems. We propose and analyze per-user regional registration schemes extending from Mobile IP Regional Registration and Hierarchical Mobile IPv6 for integrated mobility and service management with the goal to minimize the network signaling and packet delivery cost in future all-IP based wireless networks. If access routers in future all-IP based wireless networks are restricted to perform network layer functions only, we investigate the design of intelligent routers, called dynamic mobility anchor points (DMAPs), to implement per-user regional management in IP wireless networks. These DMAPs are access routers (ARs) chosen by individual MNs to act as regional routers to reduce the signaling overhead for intra-regional movements. The DMAP domain size is based on a MN's mobility and service characteristics. A MN optimally determines when and where to launch a DMAP to minimize the network cost in serving the user's mobility and service management operations. We show that there exists an optimal DMAP domain size for each individual MN. We also demonstrate that the DMAP design can easily support failure recovery because of the flexibility of allowing a MN to choose any AR to be the DMAP for mobility and service management. If access routers are powerful and flexible in future all-IP based networks to perform network-layer and application-layer functions, we propose the use of per-user proxies that can run on access routers. The user proxies can carry service context information such as cached data items and Web processing objects, and perform context-aware functions such as content adaptation for services engaged by the MN to help application executions. We investigate a proxy-based integrated mobility and service management architecture (IMSA) under which a client-side proxy is created on a per-user basis to serve as a gateway between a MN and all services engaged by the MN. Leveraging Mobile IP with route optimization, the proxy runs on an access router and cooperates with the home agent and foreign agent of the MN to maintain the location information of the MN to facilitate data delivery by services engaged by the MN. Further, the proxy optimally determines when to move with the MN so as to minimize the network cost associated with the user's mobility and service management operations. Finally we investigate a proxy-based integrated cache consistency and mobility management scheme called PICMM to support client-server query-based mobile applications, to improve query performance, the MN stores frequently used data in its cache. The MN's proxy receives invalidation reports or updated data objects from application servers, i.e., corresponding nodes (Cans) for cached data objects stored in the MN. If the MN is connected, the proxy will forward invalidation reports or fresh data objects to the MN. If the MN is disconnected, the proxy will store the invalidation reports or fresh data objects, and, once the MN is reconnected, the proxy will forward the latest cache invalidation report or data objects to the MN. We show that there is an optimal ``service area'' under which the overall cost due to query processing, cache consistency management and mobility management is minimized. To further reduce network traffic, we develop a threshold-based hybrid cache consistency management policy such that whenever a data object is updated at the server, the server sends an invalidation report to the MN through the proxy to invalidate the cached data object only if the size of the data object exceeds the given threshold. Otherwise, the server sends a fresh copy of the data object through the proxy to the MN. We identify the best ``threshold'' value that would minimize the overall network cost. We develop mathematical models to analyze performance characteristics of DMAP, IMSA and PICMM developed in the dissertation research and demonstrate that they outperform existing schemes that do not consider integrated mobility and service management or that use static regional routers to serve all MNs in the system. The analytical results obtained are validated through extensive simulation. We conclude that integrated mobility and service management can greatly reduce the overall network cost for mobile multimedia and database applications, especially when the application's data service rate is high compared with the MN's mobility rate. / Ph. D.
712

<b>Using Minimally-Invasive </b><b><i>In vivo </i></b><b>Imaging to Map the Genomic Heterogeneity of Human Brain Tumors</b>

Mahsa Servati (18406212) 18 April 2024 (has links)
<p dir="ltr">Human brain tumors present significant challenges due to their heterogeneous nature, known as intra-tumoral heterogeneity (ITH), which evolves over space and time, leading to treatment resistance and poor patient outcomes. Current diagnostic methods rely on pre-surgical imaging and single biopsy samples, providing only a partial understanding of the tumor microenvironment (TME) and often resulting in incomplete targeting of tumor mutations, leaving residual disease vulnerable to recurrence. Our hypothesis proposes a novel approach: utilizing multimodal and multiparametric <i>in vivo</i> imaging to map the cellular and molecular characteristics of the TME. By correlating imaging signatures with underlying somatic and genomic aberrations, we aim to develop a predictive model guiding personalized targeted therapies to effectively address the heterogeneity of brain tumors.</p><p dir="ltr">To achieve this goal, we designed, tested, and validated a predictive model through a pilot study using clinical MRI scans and one stereotactic biopsy sample. Subsequently, we optimized a multimodal and multiparametric imaging protocol including MRI and PET scans, to acquire comprehensive morphological, functional, and molecular data from the TME. Additionally, we established a detailed pipeline for subject recruitment, data collection, and post-processing to ensure the robustness and reliability of our model.</p><p dir="ltr">This innovative approach has the potential to overcome the limitations of current diagnostic methods by providing a comprehensive understanding of the TME using minimally-invasive imaging techniques. By correlating imaging data with ground truth pathology and genomics, this model will enhance brain tumor diagnosis and facilitate the implementation of targeted therapies, ultimately improving treatment response and patient outcomes.</p>
713

Automatic Point Cloud Registration for Mobile Mapping LiDAR Data : Developing an Automated Method for Registration of Light Rail Environment / Automatisk registrering av punktmoln från Mobile Mapping LiDAR data : Framställning av en automatisk metod för registrering i spårvägsmiljö

Larsson, Milton, Wardman, Ellinor January 2024 (has links)
Maintaining an inventory of transportation infrastructure assets is vital for effective management and maintenance. LiDAR (Light Detection and Ranging) can be a useful resource for this purpose by collecting detailed 3D information. Mobile Mapping Systems (MMS) refers to collecting geospatial data by mounting laser scanners on top of a moving vehicle, e.g. a car. The LiDAR collects XYZ-coordinates of the environment by emitting laser pulses toward the surveyed objects. This enables an effective way to store and survey built-up urban areas that otherwise would need an on-site presence. WSP uses Mobile Mapping (MM) to capture and visualize infrastructure, primarily for inventory purposes. Currently, the point cloud registration in the MM-process is labor-intensive, so the company is looking to automate it. This thesis aims to investigate methods to automate the process of point cloud registration that eliminates manual labor. The proposed method was evaluated with regards to its accuracy, advantages and disadvantages. The study area of the thesis was a light rail facility with surrounding residential buildings and vegetation. The proposed method was implemented in Python and utilizes open source libraries. The registration uses Fast Global Registration (FGR) for coarse alignment with Iterative Closest Point (ICP) for fine refinement. The FGR algorithm finds a rigid transformation between a pair of point clouds by establishing a feature correspondence set between the point clouds. The algorithm utilizes Fast Point Feature Histograms (FPFH) that simplifies the description of 3D point relationships as the feature descriptors. The object used for registration is the general area around catenary poles. The segments between poles is adjusted by linear interpolation of the obtained transformation matrices from the registration. The results of this thesis show that automatic point cloud registration is feasible. However, while the proposed method improves registration over raw data, it does not fully replace WSP's current procedure.  The advantages of the proposed method are that it does not require classified data and is open source. The main source of error in the method is the presence of vegetation, and an experiment was conducted to support this hypothesis. The experiment shows that dense vegetation skews the registration, and generates an incorrect transformation matrix. Furthermore, the proposed method is only semi-automated, as it still needs manual post-processing. Accuracy assessment showed that removing outlier, presumably caused by vegetation, improved the planar offsets. Further studies to improve the result could utilize machine learning which could identify and extract poles for registration or remove surrounding vegetation. / Att upprätthålla inventering av tillgångar av transportinfrastruktur är avgörande för effektiv förvaltning och underhåll samt för att tillhandahålla korrekta data och underlätta beslutsfattande. LiDAR-data (Light Detection and Ranging) kan vara ett användbart verktyg för detta ändamål genom att samla in detaljerad 3D-information. Mobile Mapping Systems (MMS) refererar till att samla geospatial data genom att montera laserskannrar ovanpå taket på ett rörligt fordon, exempelvis en bil. LiDAR samlar XYZ-koordinater av kringliggande miljö genom att sända ut laserpulser mot de undersökta objekten. Detta möjliggör ett effektivt sätt att förvara och undersöka bebyggda stadsmiljöer som annars skulle behöva fysisk närvaro. WSP använder Mobile Mapping (MM) för att samla och visualisera infrastruktur, främst för inventeringsändamål. För närvarande är punktmolnregistreringen i MM-processen manuellt arbetskrävande, och därför vill WSP se en automatisering av processen. Detta examensarbete syftar till att undersöka metoder för att automatisera processen för registrering av punktmoln som eliminerar manuellt arbete. Den utvecklade metoden kommer att utvärderas med avseende på dess noggrannhet, för- och nackdelar. Arbetets studieområde är en järnvägsanläggninng med omgivande av bostadshus och vegetation. Den föreslagna metoden implementerades i Python och använder sig av open source-bibliotek. Registeringen tillämpar Fast Global Registration (FGR) för grov justering av punktmolnen, och Iterative Closest Point (ICP) för finjustering. FGR-algoritmen hittar en stel transformation mellan två punktmoln genom att etablera ett set av korresponderande attribut. Algoritmen använder Fast Point Feature Histograms (FPFH) som förenklar euklidiska förhållanden till attributbaserade förhållanden. Objekt som används för registrering är det generella området kring kontaktledningsstolpar. Segmenten mellan stolpar justeras genom linjär interpolation av de erhållna transformationsmatriserna från registreringen. Resultaten av detta arbete visar att automatisk registrering av punktmoln är genomförbar, och att metoden förbättrar registreringen jämfört med den råa datan. Den är dock inte tillräckligt bra för att helt ersätta den nuvarande proceduren som används av WSP. Fördelarna med den föreslagna metoden är att den inte kräver klassificerad data och är open source. Den huvudsakliga felkällan i metoden är förekomsten av vegetation, och ett experiment utfördes för att stödja denna hypotes. Experimentet visar att tät vegetation snedvrider registreringen och genererar en felaktig transformationsmatris. Vidare, är den föreslagna metoden endast semi-automatiserad, eftersom den fortfarande kräver manuell efterbearbetning. Noggrannhetsbedömningn visade att borttagningen av avvikande värden, förmodligen orsakade av vegetation, förbättrade den plana förskjutningen. Vidare studier för att ge ett mer tillfredsställande resultatet kan möjligen vara att använda maskininlärning för att identifiera och extrahera stolpar för matching, samtidigt som växtligheten kan elimineras.
714

Le rattachement des engins à l'Etat en droit international public (navires, aéronefs, objets spatiaux) / The connection between craft / vessels and States in public international law (ships, aircraft, space objects)

Aloupi, Niki 27 April 2011 (has links)
Contrairement aux autres biens meubles, les navires, les aéronefs et les objets spatiaux affectés à la navigation internationale sont rattachés à un Etat. Le lien de droit public établi entre ces engins et l’Etat est communément appelé « nationalité ». Mais ce terme n’exprime pas à leur propos une institution à tous égards identique à la nationalité des personnes. Le rattachement examiné ne repose en effet pas sur des éléments de fait (naissance, ascendance etc.), mais uniquement sur un acte administratif interne, l’immatriculation. L’étude de la pratique, notamment des conventions internationales et des législations nationales, montre clairement que – contrairement à ce qu’on soutient souvent – il n’y a pas lieu de subordonner ce rattachement à un lien effectif. Ce qui importe, compte tenu notamment du fait que ces engins évoluent dans des espaces soustraits à toute compétence territoriale, est d’identifier l’Etat qui est seul compétent à l’égard de l’« ensemble organisé » formé par le véhicule, les personnes et la cargaison à bord, et qui est responsable de ses activités. Le droit international interdit dès lors la double immatriculation, mais il laisse aux Etats le pouvoir discrétionnaire de déterminer les conditions d’attribution de leur « nationalité », sans subordonner l’opposabilité internationale de celle-ci à quelque autre exigence que ce soit. Le danger est toutefois que cela favorise un certain laxisme de l’Etat d’immatriculation, ce qui exposerait au risque que des dommages graves soient causés aux personnes impliquées dans les activités de ces engins et – surtout – aux tiers. Mais ce sont les obligations internationales imposées et les droits corrélatifs reconnus dans le chef de l’Etat d’immatriculation qui sont déterminants à cet égard et non quelque mystérieuse « effectivité » du rattachement. Autrement dit, s’il n’est pas nécessaire d’imposer à l’Etat d’immatriculation des conditions internationales limitant sa liberté dans l’attribution de sa « nationalité » aux engins, il est indispensable d’exiger que celui-ci respecte ses obligations, c’est-à-dire exerce effectivement son contrôle et sa juridiction. Cette constatation se vérifie quel que soit l’engin en cause. Le rattachement créé par l’immatriculation constitue donc une institution "sui generis", commune aux navires, aéronefs et objets spatiaux et dont le régime juridique est encadré par le droit international. / Unlike any other movable property, ships, aircraft and space objects that are engaged in international navigation are linked to a State. The legal connection established between these craft/vessels and the State is commonly referred to as “nationality”. However, in this case the term does not represent an institution identical in all respects to the nationality of persons. With regard to vessels, the legal connection to a State is not based on factual elements (such as birth, descent etc.), but merely on the internal administrative act of registration. The study of State practice, notably international conventions and national laws, clearly shows that – contrary to what is often argued – there is no need to make this connection dependent on a pre-existing effective link. What matters most, given that these craft navigate in international space beyond the territorial jurisdiction of sovereign States, is to identify the State that holds sole jurisdiction over said “organized entity” consisting of the vehicle, the persons and the cargo on board and that is responsible for its activities. Public international law therefore prohibits dual registration, but leaves States free to determine the conditions under which they will confer their “nationality”, without imposing any other requirement for the opposability of this legal bond to third States. The danger is that this situation encourages laxity on the part of the States of registry and therefore creates the potential for serious damage incurred by persons involved in these vessels’ activities and – mostly – by third persons. In this regard, it is the international obligations and corresponding rights of the States of registry which are critical, and not a mysterious “effectiveness” of the legal bond. In other words, it is not necessary to impose on the State of registry any international conditions which would limit its freedom with regard to the conferral of its “nationality” upon vessels. It is however indispensable to require that said State complies with its obligations, meaning that it has to effectively exercise its jurisdiction and control over those craft. This statement holds true regardless of the craft concerned. The legal bond created by the registration therefore constitutes a "sui generis" institution, common to ships, aircraft and space objects, and whose legal regime is governed by international law.
715

Automatic student attendance registration using radio frequency identification (RFID)

Kuriakose, Rengith Baby 03 1900 (has links)
Thesis (M. Tech.) - Central University of Technology, Free State, 2010 / The main aim of this research was to automate student attendance registration, thereby reducing human involvement in the whole process. This was made possible using Radio Frequency Identification (RFID) technology. The Central University of Technology uses student cards that are compatible for use with RFID technology. As a result, no initial investment (except for the existing personal computer’s and the constructed RFID reader) in infrastructure was required for this project. The basic working of the project was as follows. The students belonging to a specific class had their vital educational data (Student number, Name) entered into a database table at the time of registration. A student card containing a serial number, with reference to the data contained in the database table, was given to the students after registration. The students walk into their respective classes and scan their student cards with the RFID reader. The serial number stored in the student card is transferred to the reader and from there wirelessly to the main server using ZigBee technology. In the main server, using Java programming language, the card serial number is sent to the Integrated Development Environment (IDE). In this project the Netbeans IDE (Java platform) was used. The Netbeans IDE is connected to the Apache Derby database using Java Database Connector (JDBC), so the serial number (which is referenced to the educational data of the students) from the student card is automatically compared with the original database created at the time of registration. Once a match is confirmed between the two entries, the data is entered into a separate database table which serves as the basic attendance sheet for a specific day.
716

ISO 9001 Registration for the Electronic Hardware Fabrication Process at the Jet Propulsion Laboratory

Bonner, J. K. “Kirk”, de Silveira, Carl 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / More and more companies and organizations are recognizing the benefits to be gained by achieving ISO 9000 registration. An effort is underway at JPL to become ISO 9001 registered. To facilitate this activity, the entire laboratory has been divided into processes, each one having a designated process owner. This paper concentrates more specifically on one of these processes, namely, the Packaging and Fabrication of Electronic Hardware (PAFEH), and the effort being undertaken to ensure that this process will successfully pass registration. A comprehensive approach is being utilized by the Electronic Packaging and Fabrication Section to bring this about.
717

Analysis of the policy and process of voter registration in South Africa in the 1999 general elections

Mlitwa, Nhlanhla Boyfriend Wilton 04 1900 (has links)
Thesis (M.Phil.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The democratic order is still in its early evolutionary stages in South Africa. Although the success of the 1994 democratic elections kindled hope for a promising future, democracy needs to be safeguarded if it is to develop in South Africa. Safeguarding a democracy requires a constant scrutiny of governing policies and procedures to ensure that they remain conducive to its positive development. Of fundamental importance to the transmission of democracy is an electoral system and its policies. Any electiongoverning policy that reduces public confidence in the electoral system is not conducive to the development of a democracy. This study analyses the policy of voter registration as it directly impacts on the format of an election. Since this policy is being applied for the first time in the short history legitimate democratic elections in South Africa, the study looks beyond the noble objectives as given by the policymakers. The lEC and the Government argue that the policy is aimed at improving the legitimacy of the electoral system by eliminating the ID related forms of electoral fraud. The significance of the study lies in its critical analysis of the actual policymaking process of this legislation, as well as its implementation. In order to assess the democratic legitimacy of the policymaking stage, the study takes a closer look at the roles of all the stakeholders in the policymaking process. Further, the study describes the constitutional controversies of the provisions of the policy, as well as its actual registration process. The understanding behind the latter description is that a policy is of no use if it cannot be implemented. In short, by describing, explaining and analysing the policy from its historical, legislative, and implementation phases, the study gives an insight into how this new policy relates to the development of the South African democracy. Although this study found no conclusive evidence of the negative impact of the policy on the outcome of the election, the nature of debates, the practical difficulties of implementation by the IEC, as well as the Court debates have all raised new questions that could require further analysis. / AFRIKAANSE OPSOMMING: Die demokratiese bewind in Suid-Afrika is tans nog in die vroeë stadia van ontwikkeling. Hoewel die sukses van die demokratiese verkiesings in 1994 die vertroue in die moontlikheid van 'n belowende toekoms laat styg het, moet voortdurend gewaak word teen afbreek van die demokrasie in Suid-Afrika, en ruimte gemaak word vir die verdere ontwikkeling daarvan. Die beveiliging van 'n demokrasie verg aanhoudende noukeurige beskouing van die regering se beleid, en die uitvoer daarvan, om te verseker dat dit die positiewe ontwikkeling van die demokrasie bevorder. Die verkiesingstelsel en beleid is van fundamentele belang vir die vestiging van demokrasie. 'n Beleid wat die algemene vertroue in die verkiesingstelsel benadeel, sal nie die ontwikkeling van enige demokrasie bevorder nie. Hierdie studie ontleed die direkte invloed van die kieserregistrasie-beleid op die formaat van die 1999 verkiesing. Aangesien hierdie beleid vir die eerste keer in die kort geskiedenis van Suid-Afrikaanse verkiesings toegepas word, kyk die studie verder as die edele doel beoog deur die skeppers van die beleid. Die OVK en die Regering beweer dat die beleid gerig is daarop om die regverdigheid van die verkiesingstelsel te verbeter deur die uitskakeling van ID-verbonde verkiesingsbedrog. Die studie is veral belangrik in die kritiese ontleding van die skeppingsproses van die beleid self, sowel as die implementering daarvan. Om die demokratiese regverdigheid van die skeppingstadium van die beleid te kan beoordeel, val die soeklig veralop die rol van alle deelnemers aan hierdie proses. Die grondwetlike probleme met dele van die beleid sowel as die registrasieproses word beskryf. Hierdie beskrywing word gedoen vanuit die oogpunt dat 'n beleid geen doel kan dien tensy dit geïmplementeer kan word nie. Kortliks, deur die beleid te beskryf, te verduidelik en te ontleed in sy historiese, wetgewende en implementeringsfases, gee die studie 'n insig in die verhouding van hierdie nuwe beleid tot die ontwikkeling van die Suid-Afrikaanse demokrasie. Hoewel geen afdoende bewyse van 'n negatiewe invloed van die beleid op die uitkoms van die verkiesing deur hierdie studie bewys is nie, is sake wat verdere ontleding kan verg geopper in verband met die aard van die besprekings om die beleid, die praktiese moeilikhede van implementering deur die OVK, asook die besprekings in die hof.
718

Depth-registration of 9-component 3-dimensional seismic data in Stephens County, Oklahoma

Al-Waily, Mustafa Badieh 04 September 2014 (has links)
Multicomponent seismic imaging techniques improve geological interpretation by providing crucial information about subsurface characteristics. These techniques deliver different images of the same subsurface using multiple waveforms. Compressional (P) and shear (S) waves respond to lithology and fluid variations differently, providing independent measurements of rock and fluid properties. Joint interpretation of multicomponent images requires P-wave and S-wave events to be aligned in depth. The process of identifying P and S events from the same reflector is called depth-registration. The purpose of this investigation is to illustrate procedures for depth-registering P and S seismic data when the most fundamental information needed for depth-registration – reliable velocity data – are not available. This work will focus on the depth-registration of a 9-component 3-dimensional seismic dataset targeting the Sycamore formation in Stephens County, Oklahoma. The survey area – 16 square miles – is located in Sho-Vel-Tum oilfield. Processed P-P, SV-SV, and SH-SH wave data are available for post-stack analysis. However, the SV-data volume will not be interpreted because of its inferior data-quality compared to the SH-data volume. Velocity data are essential in most depth-registration techniques: they can be used to convert the seismic data from the time domain to the depth domain. However, velocity data are not available within the boundaries of the 9C/3D seismic survey. The data are located in a complex area that is folded and faulted in the northwest part of the Ardmore basin, between the eastern Arbuckle Mountains and the western Wichita Mountains. Large hydrocarbon volumes are produced from stratigraphic traps, fault closures, anticlines, and combination traps. Sho-Vel-Tum was ranked 31st in terms of proved oil reserves among U.S. oil fields by a 2009 survey. I will interpret different depth-registered horizons on the P-wave and S-wave seismic data volumes. Then, I will present several methods to verify the accuracy of event-registration. Seven depth-registered horizons are mapped through the P-P and SH-SH seismic data. These horizons show the structural complexity that imposes serious challenges on well drilling within the Sho-Vel-Tum oil field. Interval Vp/Vs – a seismic attribute often used as lithological indicator – was mapped to constrain horizon picking and to characterize lateral stratigraphic variations. / text
719

A county level analysis of the jury source lists in the state of Georgia and the effects of the National Voter Registration Act on source list composition

Rackley, David R. January 1997 (has links)
This study assesses the levels of diversity in the jury source lists in the State of Georgia utilizing voter registration data as of February 1997, and the effects of the National Voter Registration Act (NVRA) on diversity levels. The data indicates that, while the NVRA has increased registration rates, the rates for blacks has been only slightly higher than that of whites. Thus, the problems of diversity have not been significantly effected by the NVRA.This paper discusses the issue of cognizable class, and reiterates arguments supporting the recognition of young persons and non-voters as cognizable. Also assessed are the methods of measuring source list disparity, with attention given to problems associated with the absolute disparity test, and argues for the use of the Chi-Square "Goodness of Fit" test to measure source list disparity.Current levels of disparity are calculated using both absolute disparity and ChiSquare. These are found in the appendix. Analysis is done by assessing the percentage of source lists (for which there is data) that should be presumed invalid using the five percent criterion for absolute disparity and the fifty percent criterion for Chi-Square.Analysis using both absolute disparity and Chi-Square indicates that many source lists in the State of Georgia are not representative of the population. While absolute disparity invalidates only few source lists, the Chi-Square statistic indicates that the problem is much more widespread.Both absolute disparity and Chi-Square results indicate that age is the most important variable with regard to under-representation. Young persons (18-29) are found to be under-represented more often than any other group regardless of race and/or sex. This is particularly evident when looking at the Chi-square results. While blacks are generally found to be under-represented more often when compared to similar sex and age aggregates for whites, the levels of under-representation of race and sex aggregates remain closely related to age. / Department of Political Science
720

Efficient processing of corneal confocal microscopy images : development of a computer system for the pre-processing, feature extraction, classification, enhancement and registration of a sequence of corneal images

Elbita, Abdulhakim Mehemed January 2013 (has links)
Corneal diseases are one of the major causes of visual impairment and blindness worldwide. Used for diagnoses, a laser confocal microscope provides a sequence of images, at incremental depths, of the various corneal layers and structures. From these, ophthalmologists can extract clinical information on the state of health of a patient’s cornea. However, many factors impede ophthalmologists in forming diagnoses starting with the large number and variable quality of the individual images (blurring, non-uniform illumination within images, variable illumination between images and noise), and there are also difficulties posed for automatic processing caused by eye movements in both lateral and axial directions during the scanning process. Aiding ophthalmologists working with long sequences of corneal image requires the development of new algorithms which enhance, correctly order and register the corneal images within a sequence. The novel algorithms devised for this purpose and presented in this thesis are divided into four main categories. The first is enhancement to reduce the problems within individual images. The second is automatic image classification to identify which part of the cornea each image belongs to, when they may not be in the correct sequence. The third is automatic reordering of the images to place the images in the right sequence. The fourth is automatic registration of the images with each other. A flexible application called CORNEASYS has been developed and implemented using MATLAB and the C language to provide and run all the algorithms and methods presented in this thesis. CORNEASYS offers users a collection of all the proposed approaches and algorithms in this thesis in one platform package. CORNEASYS also provides a facility to help the research team and Ophthalmologists, who are in discussions to determine future system requirements which meet clinicians’ needs.

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