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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.
531

DIGITAL RECEIVER PERFORMANCE

Troublefield, Robert C. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Bit errors often occur in a wireless communications link when impairments alter the transmitted signal. It is advantageous to be able to predict how well a system will tolerate transmission problems. This paper details laboratory performance measurements and comparisons in terms of evaluating configurations of a digital receiver for Feher patented Quadrature Phase Shift Keying (FQPSK-B) demodulation. The transmitted signal is subjected to calibrated levels of impairments while the receiver performance is monitored in real-time.
532

On Enhancement and Quality Assessment of Audio and Video in Communication Systems

Rossholm, Andreas January 2014 (has links)
The use of audio and video communication has increased exponentially over the last decade and has gone from speech over GSM to HD resolution video conference between continents on mobile devices. As the use becomes more widespread the interest in delivering high quality media increases even on devices with limited resources. This includes both development and enhancement of the communication chain but also the topic of objective measurements of the perceived quality. The focus of this thesis work has been to perform enhancement within speech encoding and video decoding, to measure influence factors of audio and video performance, and to build methods to predict the perceived video quality. The audio enhancement part of this thesis addresses the well known problem in the GSM system with an interfering signal generated by the switching nature of TDMA cellular telephony. Two different solutions are given to suppress such interference internally in the mobile handset. The first method involves the use of subtractive noise cancellation employing correlators, the second uses a structure of IIR notch filters. Both solutions use control algorithms based on the state of the communication between the mobile handset and the base station. The video enhancement part presents two post-filters. These two filters are designed to improve visual quality of highly compressed video streams from standard, block-based video codecs by combating both blocking and ringing artifacts. The second post-filter also performs sharpening. The third part addresses the problem of measuring audio and video delay as well as skewness between these, also known as synchronization. This method is a black box technique which enables it to be applied on any audiovisual application, proprietary as well as open standards, and can be run on any platform and over any network connectivity. The last part addresses no-reference (NR) bitstream video quality prediction using features extracted from the coded video stream. Several methods have been used and evaluated: Multiple Linear Regression (MLR), Artificial Neural Network (ANN), and Least Square Support Vector Machines (LS-SVM), showing high correlation with both MOS and objective video assessment methods as PSNR and PEVQ. The impact from temporal, spatial and quantization variations on perceptual video quality has also been addressed, together with the trade off between these, and for this purpose a set of locally conducted subjective experiments were performed.
533

Perfil audiométrico de exames admissionais em trabalhadores da construção civil da Bahia / A study of the civil construction workers audiometric profile upon admission in the state of Bahia (Brazil)

Fonseca, Ana Maria Pimenta da 10 October 2007 (has links)
Made available in DSpace on 2016-04-27T18:12:24Z (GMT). No. of bitstreams: 1 Ana Maria Pimenta da Fonseca.pdf: 566657 bytes, checksum: 4943537ba9730854c7867eec02d30707 (MD5) Previous issue date: 2007-10-10 / The goal of this study was to investigate and analyze the civil construction workers audiometric profile upon admission in the State of Bahia (Brazil) from 1999 to 2005. Methods: Audiometric tests (n=5702) were carried out among male workers (age range: 18 to 72) upon admission when applying for several job positions in 43 civil construction companies. Audiograms was classified into three groups: normal , indicating noise-induced hearing loss (NIHL) and other causes , and were later rated as to the presence/absence of audiometric notches. Results: Normal hearing thresholds were found in 3949 (69.3%) workers, 920 (16.2%) of them showed audiograms indicating NIHL, and other alterations were found in 833 (14.6%) subjects. Although 980 (17.2%) workers did not report noise exposure, 4722 (82.8%) subjects reported at least one year of such exposure. The use of hearing protection devices was reported by 2483 (43.5%) subjects in contrast with 3219 (56.0%) workers who did not use it. Workers exposed to chemicals totaled 1084 (19%) against 4618 (81%) nonexposed ones. Audiometric notches were found in 1684 (29.5%) subjects in the normal group, 919 (16.1%) subjects in the NIHL group and 774 (13.4%) subjects in the other causes group. Conclusions: The prevalence of audiometric alterations was found to be 30.7%, among which 16.1% indicated NIHL and 14.6% were rated as other causes . Increased age, more than 5 years of noise exposure, lack of use of hearing protection devices and exposure to chemicals were associated to the hearing losses found in the sample. The prevalence of audiometric notches in this population was 59.3%, of which 30.9% were unilateral and 28.4% were bilateral. Besides being associated to age, exposure time and job position, notches were more prevalent in the NIHL group and in the other causes group / O presente estudo tem como objetivo investigar e analisar o perfil audiométrico nos exames admissionais em trabalhadores da construção civil na Bahia, no período de 1999 a 2005. Método: Foram avaliadas 5702 audiometria admissionais de trabalhadores do gênero masculino, que faziam processo seletivo em 43 empresas da construção civil. A faixa etária estava entre 18 e 72 anos. Os trabalhadores realizaram exames pré-admissonais para as mais diversas funções da construção civil. Os audiogramas foram classificados em três grupos: normais, sugestivos de PAIR e outras causas. Posteriormente, também foram classificados segundo presença ou ausência de entalhe audiométrico. Resultados: 3949 (69,3%) trabalhadores apresentaram limiares dentro da normalidade, 920 (16,2%) apresentaram alteração sugestiva de PAIR e 833 (14,6%) trabalhadores apresentaram outras alterações. Dentre esses, 980 (17,2%) trabalhadores não relataram exposição a ruído e 4722 (82,8%) tinham tempo de exposição a ruído de, no mínimo, um ano. Quanto ao uso de protetor auricular (EPI), 2483 (43,5%) faziam uso e 3219(56,%) não faziam uso. Em relação à exposição a produtos químicos, 1084(19%) estavam expostos e 4618 (81%) não estavam expostos. O entalhe audiométrico esteve presente em 1684 (29,5%) trabalhadores do Grupo Normal, 919 (16,1%) no Grupo PAIR e 774 (13,4%) no Grupo Outros. Conclusões: A prevalência de alterações audiométricas foi de 30,7%, sendo 16,1% sugestivas de PAIR e 14,6% de outras causas. O aumento da idade, tempo de exposição a ruído superior a cinco anos, não uso de protetores e exposição a produtos químicos foram associados às perdas auditivas encontradas na população. A prevalência de entalhe audiométrico na população foi de 59,3%, sendo 30,9% unilateral e 28,4% bilateral. Os entalhes foram associados à idade, tempo de exposição e função exercida; além de ocorrerem mais nos Grupos PAIR e Outros
534

An investigation into the weld integrity of the head–to–skirt junction on tall distillation columns / L. Brink

Brink, Lize January 2010 (has links)
This study addresses the fatigue life of the head–to–skirt welds of tall distillation columns. Fatigue tests were done on two types of weld geometries which approximate the head–toskirt configurations. From the fatigue tests it was determined that the fatigue life of the experimental samples can be substantially improved by applying weld build–up between the head and the skirt. The expected fatigue life of the test samples was determined by way of calculation employing the so called Nominal–Stress–Approach, the Effective–Notch–Stress–Approach and the Stress–Life–Approach. For both the Nominal–Stress–Approach and the Effective–Notch–Stress–Approach the predicted fatigue life was found to be overly conservative compared to the experimental results. The Stress–Life–Approach predicted the fatigue life to within a factor of 1.3 for both the geometries under investigation when displacements due to welding are taken into account. If displacements due to welding is omitted this factor is increased, for the geometry without weld build–up, to 2. For the geometry with weld build–up the factor remains 1.3. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.
535

An investigation into the weld integrity of the head–to–skirt junction on tall distillation columns / L. Brink

Brink, Lize January 2010 (has links)
This study addresses the fatigue life of the head–to–skirt welds of tall distillation columns. Fatigue tests were done on two types of weld geometries which approximate the head–toskirt configurations. From the fatigue tests it was determined that the fatigue life of the experimental samples can be substantially improved by applying weld build–up between the head and the skirt. The expected fatigue life of the test samples was determined by way of calculation employing the so called Nominal–Stress–Approach, the Effective–Notch–Stress–Approach and the Stress–Life–Approach. For both the Nominal–Stress–Approach and the Effective–Notch–Stress–Approach the predicted fatigue life was found to be overly conservative compared to the experimental results. The Stress–Life–Approach predicted the fatigue life to within a factor of 1.3 for both the geometries under investigation when displacements due to welding are taken into account. If displacements due to welding is omitted this factor is increased, for the geometry without weld build–up, to 2. For the geometry with weld build–up the factor remains 1.3. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.
536

The subnuclear localisation of Notch responsive genes

Jones, Matthew Leslie January 2018 (has links)
Title: The subnuclear localisation of Notch responsive genes. Candidate Name: Matthew Jones Notch signalling is a highly conserved cell-cell communication pathway with critical roles in metazoan development and mutations in Notch pathway components are implicated in many types of cancer. Notch is an excellent and well-studied model of biological signalling and gene regulation, with a single intracellular messenger, one receptor and two ligands in Drosophila. However, despite the limited number of chemical players involved, a striking number of different outcomes arise. Molecular studies have shown that Notch activates different targets in different cell types and it is well known that Notch is important for maintaining a stem cell fate in some situations and driving differentiation in others. Thus some of the factors affecting the regulation of Notch target genes are yet to be discovered. Previous studies in various organisms have found that the location of a gene within the nucleus is important for its regulation and genome reorganisation can occur following gene activation or during development. Therefore this project aimed to label individual Notch responsive loci and determine their subnuclear localisation. In order to tag loci of interest a CRISPR/Cas9 genome-editing method was established that enabled the insertion of locus tags at Notch targets, namely the well-characterized Enhancer of split locus and also dpn and Hey, two transcription factors involved in neural cell fate decisions. The ParB/Int system is a recently developed locus tagging system and is not well characterised in Drosophila. It has a number of advantages over the traditional LacO/LacI-GFP locus tagging system as it does not rely on binding site repeats for signal amplification and can label two loci simultaneously in different colours. This thesis characterised the ParB/Int system in the Drosophila salivary gland and larval L3 neuroblast. Using 3D image segmentation hundreds of nuclei were reconstructed and a volume based normalisation method was applied to determine the subnuclear localisation of several Notch targets with and without genetic manipulations of the Notch pathway.
537

Les matériaux d'obturation et de coiffage pulpaire des dents lactéales

Shayegan, Amir 17 September 2012 (has links)
Les soins pulpaires en denture lactéale sont les soins fréquemment réalisés en odontologie pédiatrique et la réaction pulpaire ainsi que les mécanismes de réparation tissulaire lors d’un traumatisme ne sont pas très bien connus ou investigués. En se référant à la littérature dentaire, on constate que les recherches sont souvent focalisées sur la denture définitive.<p>Objectifs<p>1) Etudier l’influence du traitement avec divers matériaux sur la formation dentinaire, la structure tissulaire et le degré d’inflammation.<p>2) Acquérir des connaissances sur l’interaction à l’interface matériau/tissu.<p>3) Etudier le rôle de la voie de signalisation Notch (1 et 2) dans le processus de remaniement et réparation du tissu pulpaire en cas de traumatisme.<p>Matériels et méthodes<p>Deux types de soins pulpaires, la pulpotomie et le coiffage direct, sont réalisés sur les dents lactéales porcines et les résultats sont étudiés après 3 périodes :7 jours, 21-28 jours et 90 jours.<p>La pulpotomie :8 matériaux, 10 dents par matériau, 2 matériaux par cochon et par période pour un total de 240 dents.<p>Le coiffage direct :10 matériaux, 10 dents par matériau, 2 matériaux par cochon et par période pour un total de 300 dents.<p>Par la suite, différentes techniques ont été utilisées :<p>1. La microscopie optique :étude des coupes histologiques après coloration.<p>2. La microscopie électronique à transmission :observer les caractéristiques morphologiques du tissu pulpaire et analyser les structures cellulaires en détail. L’objectif principal de cette recherche était centré sur les biomatériaux pour la période de 21-28 jours afin d’examiner l’interaction entre le biomatériau et le complexe dentino-pulpaire après leur placement.<p>12<p>3. La voie de signalisation Notch (1 et 2): investiguer l’intervention éventuelle de cette voie dans le processus de régénération tissulaire par différenciation des cellules pour les deux périodes de 7 et 21-28 jours pour tous les matériaux utilisés.<p>Résultats<p>A. Microscopie optique :<p>1. La pulpotomie :les biomatériaux provoquent moins d’infiltrat de cellules inflammatoires au niveau du tissu pulpaire et favorisent la déposition dentinaire.<p>2. Le coiffage direct :on obtient les mêmes résultats que dans le cadre de la pulpotomie.<p>B. Microscopie électronique en transmission :<p>1. L’induction du tissu calcifié ou la formation de néo-dentine s’est seulement produite au niveau du site de l’exposition après le placement des biomatériaux dans les 2 types du traitement (pulpotomie & coiffage direct). En revanche aucune formation du tissu calcifié n’a été observée dans le parenchyme pulpaire à distance du site de l’exposition.<p>2. Cet examen montre que les cellules en contact des biomatériaux ou même à proximité de ces derniers présentent un réticulum endoplasmique élargi parallèle à la longueur de la cellule. Des mitochondries, plusieurs appareils de Golgi et des éléments denses sont observés dans le cytoplasme cellulaire.<p>3. Cet examen a également montré que le MTA et le WPC, considérés par la littérature dentaire comme non-résorbables, sont phagocytés par les cellules histiocytaires.<p>C. Voie de signalisation de Notch :<p>Nos recherches n’ont pas montré de marquage concluant pour aucun de matériaux sauf dans le cadre de coiffage direct pour les dents traitées au MTA et Ca(OH)2 pour la période de 7 jours. Par contre, aucun marquage n’est observé après 21-28 jours. / Doctorat en Sciences dentaires / info:eu-repo/semantics/nonPublished
538

In-vitro Generation of potent T-lymphoid Progenitors in a feeder-cell-free DL-4 system / Génération des progéniteurs lymphoïdes T ex vivo par exposition brève au ligand de Notch DL-4

Reimann, Christian 19 November 2012 (has links)
L’allogreffe des cellules souches hématopoïétiques (CSH) dans les situations d’incompatibilité HLA partielle représente une option thérapeutique irremplaçable pour des patients nécessitant une greffe de cellules souches hématopoïétiques, en absence d’un donneur HLA-identique. Toutefois, le retard de la restauration du système immunitaire en particulier dans du compartiment lymphocytaire après greffe est l'une des complications majeures. Une nouvelle stratégie pour promouvoir la reprise de la thymopoïèse à partir des CSH provenant du donneur et d'accélérer la reconstitution cellulaire T chez des patients après greffe de CSH consiste en le transfert adoptif des progéniteurs T générés in vitro. L’identification de Notch1 comme le régulateur-clé du développement lymphocytaire T a permis l’établissement de systèmes de culture à base de ligands de Notch, qui permettent la génération efficace de progéniteurs lymphoïdes T in vitro. L'efficacité des progeniteurs T-lymphoïdes murins pour promouvoir la reconstitution des lymphocytes T a été bien démontrée dans des modèles de greffe chez la souris. De même, des progéniteurs T-lymphopoïétiques humains générés in vitro et greffés aux souris humanisées favorisent la reprise de la thymopoïèse. Pourtant, aucune donnée n’a encore démontré leur capacité à donner naissance à un compartiment lymphocytaire T périphérique. De plus, les systèmes de co-culture à base de ligand de Notch actuellement utilisés consistent en des lignées stromales murines génétiquement modifiées. Afin d'établir un système cliniquement applicable, il est donc indispensable d’établir des systèmes de culture qui soutiennent la génération de progéniteurs T en absence d’un support des cellules nourricières. Au cours de mon projet de thèse, j'ai développé un nouveau système de culture pour la génération des progéniteurs T-lymphopoïétiques humains T basé sur l’immobilisation du ligand de Notch Delta-like-4 (DL-4) sous sa forme protéique. La culture des progéniteurs hématopoïétiques CD34+ issue de sang en présence de DL-4 immobilisé permet la génération d’un grand nombre de cellules ayant un phénotype de progéniteurs thymiques précoces (early thymic progenitor: ETP) et de prothymocytes (proT). Les cellules ETP et ProT ainsi générées expriment à des niveaux élevés des gènes impliqués dans le développement lymphocytaire précoce (i.e. pTa, Rag1, IL7Ra et BCL11b). Elles montrent des signes de réarrangement du récepteur des cellules T (TCR) similaires à leurs homologues thymiques. Par des expériences de dilution limite sur une co-culture OP9/DL-1 secondaire, j’ai pu montrer que les progéniteurs générés sur DL-4 possédaient un potentiel lymphoïde T très augmenté, qui pourrait être entièrement attribué aux sous populations ETP et ProT. Suite à leur transfert dans des souris NOD/SCID/γc-/-, les progéniteurs lymphoïde T générés par exposition a DL-4 sont capable de migrer dans le thymus, d’y poursuivre des étapes ultérieures de leur développement et d’accélérer la différentiation T intra thymique ainsi que l’émergence des lymphocytes T mature, polyclonaux et fonctionnels en périphérie. Dans une approche de co-transplantation, qui se rapproche des conditions cliniques envisagées, j’ai simultanément injecté dans le même récipient des progéniteurs générées sur DL-4 et des cellules CD34+ non traitées (d’un 2èm donneur HLA-incompatible). Cette procédure a permis une reconstitution des lymphocytes T encore plus rapide et plus. Etant donné que les progéniteurs T générées sur DL-4 et les cellules CD34+ non-traitées étaient issue de deux donneurs avec un HLA différent, cette expérience a permis de montrer que les progéniteurs préalablement exposés à DL-4 reconstituaient spécifiquement les compartiments lymphoïdes T alors que les autres lignées hématopoïétiques provenaient des progéniteurs CD34+ non-traités... / Human leukocyte antigen (HLA)-mismatched haematopoietic stem cell transplantation (HSCT) represents an important therapeutic option for patients lacking suitable donors. Delayed posttransplant immune recovery constitutes one of its major complications and is most pronounced in the T cellular compartment. A novel strategy to promote de novo thymopoiesis from donor derived HSCs and to accelerate T cellular reconstitution in patients after HSCT consists in the adoptive transfer of in vitro generated T cell progenitor cells. Identification of Notch1 as the key regulator of early T-lineage development has allowed the generation of Notch ligand-based culture systems, which provide a powerful tool to generate T-lymphoid progenitors in vitro. The efficacy of murine T-lymphoid progenitors to promote T cell reconstitution has been well demonstrated in conventional mouse models. In consistency, in vitro-generated human T cell progenitors were demonstrated to promote thymic recovery in humanized mice. Yet, positive effects of in vitro generated human T cell precursors on peripheral T cell reconstitution have not been demonstrated. Moreover currently used Notch-based co-culture systems consist of genetically modified murine cell lines. With view to establishing a clinically applicable system, feeder-cell-free Notch-ligand culture systems for the generation of T-lymphopoietic progenitors are warranted. During my PhD project I developed a new culture system based on the immobilized Notch ligand Delta-like-4 (DL-4). Exposure of human CD34+ cord blood cells to immobilized DL-4 enabled the in vitro generation of high number of T cell progenitors, which harboured the phenotype of immature early thymic progenitor cells (ETP) and prothymocytes (proT). ETP and proT cell generated during DL-4 culture upregulated essential genes involved in early T-lymphoid development (i.e. IL7Rα, PTα, RAG1 and BCL11b) and had undergone stage-specific recombination of the T cell receptor (TCR) locus in a similar way as in native human thymopoiesis. In limiting dilution analysis after secondary OP9/DL-1 co-culture, DL-4 progenitors displayed a highly increased T-lymphoid potential, which could be entirely attributed to the ETP and proT subset. When transferred into NOD/SCID/γc-/- mice, DL-4 primed T cell progenitors migrated to the thymus and accelerated intrathymic T cell differentiation and emergence of functional, mature and polyclonal αβ T cells in the periphery. In a co-transplantation approach, which more closely mimics a clinical setting, DL-4 progenitors and untreated CD34+ cells from HLA-disparate donors were simultaneously injected in the same recipient. This procedure allowed even more rapid and more robust T cell reconstitution. HLA-tracking of the distinct graft sources further showed, that DL-4 progenitors specifically reconstituted the T-lymphoid compartments. This work provides further evidence for the ability of in vitro-generated human T cell progenitors to promote de novo thymopoiesis and shows for the first time, that these cells accelerate peripheral T cell reconstitution in humanized mice. The availability of the efficient feeder-cell-free DL-4 culture technique represents an important step towards the future clinical exploitation translation of in vitro generated T-lymphoid progenitor cells to improve posttransplant immune reconstitution / Die Wiederherstellung der T-lymphozytären Immunität nach T-Zell depletierter hämatopoetischer Stammzelltransplantation (HSZT) ist ein langwieriger Prozess. Eine potentielle Strategie zur Beschleunigung der Neubildung von T-Zellen aus den transplantierten Stammzellen besteht in der Gabe von T-lymphozytären Vorläuferzellen. Die Entdeckung von Notch1 als wichtigster Regulator der frühen T-Zell-Entwicklung hat zur Etablierung Notchligand-basierter Zellkulturen geführt, mit deren Hilfe T-lymphoide Vorläuferzellen aus hämatopoetischen Stammzellen in vitro gebildet werden können. Das therapeutische Potential dieses Zelltyps wurde eindrucksvoll in konventionellen, syngenen und allogenen Maustransplantationsmodellen belegt, in denen nach Injektion in vitro generierter, muriner T-Vorläuferzellen eine Verbesserung der Neubesiedlung des Thymus sowie eine beschleunigte Wiederherstellung der T-zellulären Immunität erreicht werden konnte. Notchbasierte Co-Kultursysteme wurden ebenfalls für die invitro Herstellung humaner T-lymphoider Vorläuferzellen verwendet. Das in-vivo Potential humaner T Vorläuferzellen ist bislang jedoch nur lückenhaft charakterisiert: Zwar konnte gezeigt werden, dass humane T-Vorläuferzellen den hypoplastischen Thymus von immundefizienten NOD/SCID/γc-/- Mäusen besiedeln können. Ihre Wirksamkeit, die Wiederherstellung eines funktionellen, peripheren T-Zellkompartiments zu beschleunigen, gelang bislang jedoch nicht. Darüber hinaus werden Notchliganden in derzeit verwendeten Kultursystemen von genetisch modifizierten, murinen Stromazellen präsentiert. Die Entwicklung stromazellfreier, proteinbasierter Notchligand-Kultursysteme ist daher von grosser Bedeutung für eine mögliche therapeutische Nutzung in vitro generierter T-Vorläuferzellen. Durch Immobilisierung von Notchligand Delta-like 4 (DL-4) habe ich im Rahmen meines PhD Projekts ein stromazellfreies Kultursystem zur Züchtung T-zellulärer Vorläuferzellen aus humanen CD34+ Nabelschnurblutzellen etabliert. In DL-4 Kultur generierte Zellen besitzen phänotypische und molekulare Eigenschaften von frühen thymischen Vorläuferzellen (ETP) und Prothymocyten (proT). ETP und proT Zellen aus DL-4 Kulturen exprimieren wesentliche Geneder frühen T-Zellentstehung (z.B. IL7Ra, PTa, RAG1 und BCL11b). Die entwicklungsstadiumspezifischen TCR-Rekombinationsprozesse in DL-4 Zellen erfolgen nach dem gleichen Muster wie in der nativen Thymusentstehung. Die in DL4 Kultur generierten T-Vorläuferzellen können sich in reife T-Zellen weiterentwickeln und durchlaufen die weitere T-Zelldifferenzierung innerhalb kürzerer Zeit als native CD34+ hämatopoetische Vorläuferzellen. 13 Darüber hinaus können DL-4 generierte T-Vorläuferzellen nach Xenotransplantation den hypoplastischen Thymus von immundefizienten NOD/SCID/γc-/- Mäusen besiedeln, intrathymische T-Zellentwicklung begünstigen und die Neubildung reifer und funktionaler TZellen in der Peripherie beschleunigen. Zur Simulation einer klinischen Anwendung führte ich weiterhin Co-Transplantationen mit DL-4 Vorläuferzellen und unbehandelten CD34+ Zellen in gleiche Empfänger durch und konnte hiermit eine weitere Verbesserung der Immunrekonstitution erzielen. Durch Verwendung HLA-divergenter Spender in diesen Versuchen konnte ich zeigen, dass DL-4 Zellen sich vornehmlich in T-Zellen weiterentwickelten, während die restlichen Blutzellreihen von unbehandelten CD34-poitiven Zellen gebildet wurden. Im Rahmen dieses Projekts konnte ich mit einem für die klinische Anwendung geeigneten Kulturmodell wichtige präklinische Belege für das therapeutische Potential in vitro generierter TVorläuferzellen erbringen. Diese Arbeit bildet somit eine wichtige Grundlage für eine zukünftige klinische Anwendung von T-Vorläuferzellen zur Verbesserung der T-Zell-Immunität nach HSZT
539

Popis šíření trhlin v polích silně nehomogenních a reziduálních napětí / Description of Crack Propagation in the Fields of Strongly Non-Homogeneous and Residual Stresses

Štegnerová, Kateřina January 2019 (has links)
This Ph.D. thesis was written under the supervision of Assoc. Prof. Luboš Náhlík, Ph.D. and Assoc. Prof. Pavel Hutař, Ph.D. Thesis is focused mainly on application of generalized linear elastic fracture mechanics, which allows description of crack behaviour propagating from general singular stress concentrators, such as material interfaces or sharp V-notches, and verification of validity of used fracture criteria. The obtained results were used in the next part of the thesis, which deals with the issue of crack propagating in ceramic composites, where the stress distribution field is strongly influenced by the existence of material interface and presence of residual stresses, that arise during manufacturing process of composite.
540

Evaluation of Fracture Mechanical Parameters for Bi-Piezo-Material Notch / Evaluation of Fracture Mechanical Parameters for Bi-Piezo-Material Notch

Hrstka, Miroslav January 2019 (has links)
Předkládaná dizertační práce se zabývá stanovením hlavních členů Williamsova asymptotického rozvoje popisujícího rovinné elektro-elastické pole v okolí piezoelektrických bi-materiálových vrubů a trhlin na rozhraní za použití rozšířeného Lechnického-Eshelbyho-Strohova formalismu v návaznosti na čistě anizotropní pružnost. Je ukázáno, že rozšířený Lechnického-Eshelbyho-Strohův formalismus představuje spolu s moderními programovacími koncepty v jazyku Python efektivní a také praktický nástroj pro lomovou analýzu piezoelektrických bi-materiálů. Teoretická část práce popisuje aspekty anizotropní pružnosti a její návaznost na piezoelektrické materiály. Základní rovnice zaměřené na speciální typy monoklinických materiálů, které umožňují oddělení rovinného a anti-rovinného problému, jsou vyjádřeny pomocí komplexních potenciálů. V praktické části práce je sestaven problém vlastního hodnot pro bi-materiálový vrub, na jehož základě jsou stanoveny exponenty singularity a pomocí dvoustavového -integrálu také zobecněné faktory intenzity napětí. Veškeré vztahy a numerické procedury jsou následně rozšířeny na problém piezoelektrických bi-materiálových vrubů a podrobně prozkoumány v uvedených příkladech. Zvláštní pozornost je věnována přechodu asymptotického řešení téměř zavřených vrubů a trhlin na rozhraní. Vliv směru polarizace na asymptotické řešení je také zkoumán. Přesnost stanovení zobecněných faktorů intenzity napětí je testována srovnáním asymptotického řešení a řešení získaného pomocí metody konečných prvků s velmi jemnou sítí konečných prvků. Na závěr je formalismus modifikován pro nepiezoelektrické materiály.

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