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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.
51

Advanced imaging biomarkers for the characterisation of glioma

Thompson, Gerard January 2013 (has links)
Glioblastoma multiform (GBM) is an aggressive primary brain tumour. Despite treatment advances in recent years, outcomes remain poor. Disease progression tends to occur adjacent to the original tumour or surgical resection bed, usually within the radiotherapy planning field. This local recurrence and progression is believed to be the result of invasive disease in the surrounding tissue at the time of diagnosis and treatment, which is not currently detectable by conventional non-invasive methods. A number of novel therapies are currently under development which target specific aspects of the tumour behaviour, to try and improve outcomes from this devastating disease. Imaging biomarkers are under development, therefore, in order to provide a non-invasive assessment of tumour extent and behaviour, to provide bespoke image-guided therapies, and detect recurrence or treatment failure at the earliest opportunity. These are also of value in the context of novel therapeutics, which may have a very specific affect on an aspect of tumour behaviour that is not readily apparent on standard clinical imaging. Key to the progression of GBM is the invasion into surrounding white matter. This is followed by a period of tumour growth and subsequent angiogenesis in which microvasculature is produce that is distinct from the highly regulated blood-brain barrier. This thesis covers the development of suite of advanced magnetic resonance imaging (MRI) techniques aimed at characterising those very traits of GBM responsible for the aggressiveness and treatment resistance. Repeatability studies are undertaken to determine the performance of the biomarkers in healthy tissues, and also in a range of gliomas. Dynamic Contrast Enhanced (DCE-) and dynamic susceptibility-enhanced (DSC-)MRI are used to provide estimates of perfusion and permeability in the tumour. In order to address the reasons behind preferential invasion of the corpus callosum, they are used in conjunction with ASL to non-invasively map perfusion territories and watershed regions in the brain through perfusion timing parameters. Diffusion Tensor Imaging (DTI) and quantitative magnetisation transfer (qMT) are used to provide complementary information about white matter integrity, in order to identify changes occurring with glioma invasion as early as possible and direct image-guided treatments at presentation. Their complementary nature is assessed by comparing the two parameters simultaneously in white matter. Additionally, one of the qMT parameters which may be related to tissue pH is shown to be sensitive and specific for the detection of high-grade tumour tissue. Finally, a novel multiparametric imaging biomarker is introduced. Tumour surface mapping assesses the boundary between the solid tumour and surrounding tissue in order to identify areas of potential aggressiveness and invasion. Multiple imaging parameters can be combined to improve specificity and sensitivity. Using the diffusion-weighted imaging parameter, mean diffusivity (MD - also referred to as the apparent diffusion coefficient (ADC)), it is shown to be predictive of clinical outcome in a retrospective and prospective study, while a multiparametric example is given indicating the utility as a predicative biomarker for regions of progression and recurrence, and as potential spatial discriminator for image-guided therapies.
52

Návrh laboratorních úloh pro výuku síťových technologií a protokolů / Laboratory exercises explaining network technologies and protocols

Coufal, Tomáš January 2019 (has links)
Diploma thesis deals with creation of laboratory exercises in ns-3 environment. Each one of three exercises consists of theoretical introduction and instructions to carry out the simulation. The first exercise´s topic is routing protocol BGP. The second exercise is focused on transport protocols TCP, UDP, SCTP. In the last exercise, the basic network devices and topologies are simulated. The ARP and RIPv2 protocols are simulated as well.
53

Akvizice MRI obrazových sekvencí pro preklinické perfusní zobrazování / MRI Acquisition of Image Sequences for Preclinical Perfusion Imaging

Krátká, Lucie January 2012 (has links)
The task of this thesis is to study methods for the acquisition perfusní imaging based on dynamic MR imaging with T1 contrast. It describes methods of measurement of T1 relaxation time and the possibility of evaluating the results. It further describes the phantoms and their use. And it is here mentioned for the dynamic acquisition protocol perfusní imaging. There is also described in detail created a program for automatic control of the NMR system. In the experimental measurements are performed on static and dynamic phantom, are also evaluated perfusion parameters from the Flash sequence.
54

Simulácia dátových sietí s využitím priameho vykonávania kódu / Data network simulation using direct code execution

Trávníček, Michal January 2013 (has links)
Purpose of this master thesis was to explain simulation of real network, point to the imperfection during these simulations and try to find out technologies and solutions that could improve credibility of simulation. For this purpose, network simulator ns-3 has been chosen which supports direct code execution together with Quagga software suite. Master thesis describes internet protocol IPv4, UDP protocol, basics of routing and detailed explanation of OSPF routing protocol. Focus in this thesis is also on general description of simulation, its kinds and detail explanation of discrete simulation that is used by ns-3 simulator. Next chapter explains theory of ns-3 simulator, its development, conceptual overview and objects. Direct code execution and Quagga that both help improve credibility of simulation, are described in last chapter of theoretical part of thesis. In practical part of thesis is explained how to install and configure all three implemantaions of ns-3 simulator on Ubuntu, linux distribution. On the basis of obtained knowledge, the simulation model has been designed, also there has been given detailed explanation of how to create new model of simulation and how to analyze its results for all implementation.
55

Dávkové zpracování perfusometrických MRI dat / Batch processing of perfusometric MRI data

Filipová, Petra January 2016 (has links)
This diploma thesis deals with the DCE – MRI method (Dynamic contrast enhanced magnetic resonance imaging). Basic principle of magnetic resonance and pulse sequence is described. The diploma thesis focuses on the DCE method, especially on the description of the processing procedure by this method. Description of selected pharmacokinetic models is the part of this diploma thesis as well. Furthermore, description and realization of batch processing by PerfLab system is presented. For verifying purposes of the batch processing functionality real data were measured using created acquisition protocol, which is also part of the diploma thesis.
56

Développement d’un indice biotique basé sur les foraminifères benthiques ; : application sur la façade méditerranéenne française / Development of a biotic index based on benthic foraminifera; : application in the French Mediterranean coastal waters

Parent, Briz 11 September 2019 (has links)
Les milieux côtiers subissent de fortes pressions dues aux activités anthropiques. Ces pressions vont parfois impacter les écosystèmes benthiques. En Europe, des réglementations internationales, telle que la Directive Cadre sur l’Eau (DCE), ont vu le jour. La DCE a fixé un cadre pour obtenir le retour et le maintien d’un bon état écologique pour les masses d’eau côtières, jusqu’à un mile de la côte. Pour vérifier si ce bon état écologique est atteint, des outils de mesure adaptés et performants sont nécessaires. L’utilisation d’indices biotiques basés sur les faunes de foraminifères benthiques est un des moyens pour mesurer l’état des écosystèmes. Ces indices basés sur les faunes de foraminifères sont en pleine expansion, notamment en Méditerranée. En termes de méthodologie, nous avons pu améliorer une technique de concentration des foraminifères benthiques par séparation par densité, qui accélère le traitement des échantillons. L’indice TSI-Med a la particularité d’apporter une correction pour l’état trophique naturel, c’est-à-dire le taux d’enrichissement naturel en matière organique, sur la base de la granulométrie du sédiment. Nos données suggèrent néanmoins que cette correction est encore insuffisante. Nous avons également comparé plusieurs indices biotiques basés sur les faunes de foraminifères benthiques le long des côtes méditerranéennes françaises. Les indices basés sur la diversité, notamment l’exp(H’bc), ne sont pas adaptés à notre zone d’étude oligotrophe. Les indices basés sur les groupes écologiques d’espèces que nous avons testés (TSI-Med, Foram-AMBI et FSI) sont plutôt bien corrélés. Le principal facteur qui va induire des différences entre ces indices est la liste d’assignation écologique des espèces. Trop d’espèces n’ont pas encore été assignées et l’assignation de plusieurs espèces majeures est problématique. Néanmoins, nous avons montré que ces indices sont efficaces à détecter l’impact d’un enrichissement en matière organique diffus et/ou provenant de source ponctuelle, telle que les rejets de stations d’épuration (côte israélienne). Pour perfectionner ces indices, des efforts de caractérisation écologique des espèces doivent être poursuivis. / Coastal environments suffer from anthropogenic activities. Various types of pressure can have large impacts on benthic ecosystems. In Europe, international regulations, such as the Water Framework Directive (WFD), have been implemented. The WFD aims to attain and sustain a good ecological status for all coastal waters, up to one mile from the coast. To verify whether this good status has been reached, adapted and efficient measuring tools are needed. The use of biotic indices based on foraminiferal faunas are a mean to assess the ecosystem status. The use of indices based on foraminiferal faunas rapidly increases, especially in the Mediterranean. In terms of methodology, we were able to improve a method to concentrate benthic foraminifera by density separation, which accelerates the sample treatment. The TSI-Med index includes a correction to take into account the natural trophic state, i.e., the natural enrichment rate in organic matter, on the basis of sediment grain size. However, our data suggest that the applied correction is still insufficient. We also compared several biotic indices based on benthic foraminiferal faunas along the French Mediterranean coast. Indices based on diversity, such as the exp(H’bc), are not suited for our oligotrophic study area. The results of three tested indices based on ecological groups (TSI-Med, Foram-AMBI, FSI) are well correlated. The main factor inducing differences between the indices is the list of ecological assignments for the various species. In general, too many species have not yet been assigned to ecological categories and the assignment of several major species is problematic. Nevertheless, we show that the indices are already efficient in detecting the impact of diffusive organic matter enrichment or enrichment from point sources, such as sewage outlets (Israelian coast). To further perfection the foraminiferal indices, the efforts of ecological assignments of species have to be continued
57

Ablaufszenarien fuer Client-Server Anwendungen mit CORBA 2.0

Falk, Edelmann 12 November 1997 (has links)
Die Common Object Request Broker Architecture (CORBA) der Object Management Group (OMG) bietet die Chance, nicht nur eine Plattform fuer neue verteilte Anwendungen zu sein, sondern erlaubt es auch, bestehende Anwendungen und Altsoftware hersteller- und systemuebergreifend zu integrieren. Diese Eigenschaft hebt CORBA von anderen Programmierplattformen ab und gibt CORBA das Potential, eine aussichtsreiche Basis fuer kuenftige Anwendungssysteme zu sein. Das Ziel dieser Studienarbeit besteht darin, die Umsetzbarkeit verschiedener Interaktionsarten in CORBA zu untersuchen und an Beispielen praktisch auszuprobieren. Moegliche Ablaufformen aus der Literatur, aus den Systemen DCE und MPI und anhand eigener Ueberlegungen werden im ersten Teil dieser Arbeit systematisch zusammengefasst. Danach folgt eine ausfuerliche Behandlung der Architektur von CORBA und der hier moeglichen Ablaufformen und Interaktionsszenarien. Abschliessend werden acht verschiedene Versionen eines einfachen verteilten Woerterbuches vorgestellt, um einige der in CORBA realisierten Konzepte am praktischen Beispiel zu verdeutlichen. Als CORBA-Plattform stand Orbix-MT 2.0.1 (multi-threaded) der Firma IONA Technologies Ltd. unter Solaris 2.x zur Verfuegung.
58

The influence of neural network-based image enhancements on object detection

Pettersson, Eric, Al Khayyat, Muhammed January 2023 (has links)
This thesis investigates the impact of image enhancement techniques on object detection for carsin real-world traffic scenarios. The study focuses on upscaling and light correction treatments andtheir effects on detecting cars in challenging conditions. Initially, a YOLOv8x model is trained on clear static car images. The model is then evaluated on a test dataset captured in real-world driving with images from a front-mounted camera on a car, incorporating various lighting conditions and challenges. The images are then enhanced with said treatments and then evaluated again. The results in this experiment with its specific context show that upscaling seems to decreasemAP performance while lighting correction slightly improves accuracy. Additional training on acomplex image dataset outperforms all other approaches, highlighting the importance of diverse and realistic training data. These findings contribute to advancing computer vision research for object detection models.
59

PHARMACOKINETIC MODELING OF DYNAMIC MR IMAGING IN THE KNEE OF CHILDREN WITH JUVENILE RHEUMATOID ARTHRITIS

WORKIE, DAGNACHEW WALELIGN 14 July 2005 (has links)
No description available.
60

Patient and health care professional views of re-designing services in primary care

Mayes, Nicola January 2011 (has links)
Background: Increased pressure, rising demand and cost constraints have driven a need for radical service re-design in the NHS. To deliver re-design objectives it is necessary to understand how they are perceived by service users and providers. Aim: To investigate the views of patients and health care professionals (HCP) on aspects of health policy and service re-design affecting primary care. Setting: Patients and HCPs from one geographical area in England. Method: Themes from phase one qualitative interviews were explored quantitatively using a questionnaire in phase two and a discrete choice experiment (DCE) in phase three. Factor analysis was used to explore HCP responses in phase two. In phase three the DCE was administered to explore patients‟ relative priorities of a range of attributes. Results: HCPs had concerns that the Quality Outcomes Framework (QOF) detracted from the patient‟s agenda and did not improve health outcomes. GPs felt continuity of care was important Monday through Friday but were not keen on its provision out of hours. Neither did they feel nurses could run chronic disease management clinics without a GP present. Patients felt continuity could be provided by different HCPs for different conditionsPatients stated continuity of care and consultation duration were the most important attributes in a primary care service. However, in the DCE they prioritised both being seen on the day and by a GP over longer appointments. Patient preference to be seen by a GP may reflect the low uptake of non-medical prescribing in the area. Conclusion: Continuity of care, while remarked as being important to both HCPs and patients, appears less important when weighted against other primary care service attributes. HCPs appear to want longer consultations whereas patients saw time as encompassing both the time to wait for an appointment and consultation length. For patients, the quality of the time with a HCP may be more important than its duration, additionally patients appear to want choice but not necessarily to choose.

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