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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

Application of the mechanical of the damage in the analysis of the behavior of polymer composites recycled reinforced by coconut fiber / AplicaÃÃo da mecÃnica da danificaÃÃo na anÃlise do comportamento de materiais compÃsitos polimÃricos reciclados reforÃados por fibras de coco

Luiz Carlos GonÃalves Pennafort Junior 27 March 2015 (has links)
Com os crescentes movimentos ecolÃgicos em todo o mundo, onde o objetivo principal visa conscientizar e estimular a populaÃÃo mundial a poupar os recursos naturais, aliado a necessidade de se desviar os resÃduos aterrados (sanitÃrios ou industriais), de forma a reduzir os problemas ambientais e de saÃde pÃblica, decorrentes da disposiÃÃo inadequada de resÃduos sÃlidos, surgem os incentivos a reciclagem de materiais, bem como o desenvolvimento de materiais biodegradÃveis. Diante deste contexto, os materiais compÃsitos reforÃados com fibras naturais ganham destaque no meio cientÃfico. No entanto, seu uso ainda à tido com desconfianÃa, devido ao pouco ou nenhum conhecimento desses promissores materiais. Perante essa problemÃtica, surgiu a proposta deste trabalho de carÃter investigativo, em que foi pesquisado e desenvolvido um compÃsito totalmente reciclado, de matriz termoplÃstica (PVC reciclado) reforÃado, com fibras obtidas da casca de cocos verdes descartados. Para esse objetivo foram utilizadas diversas ferramentas de caracterizaÃÃo fÃsica, quÃmica, tÃrmica e mecÃnica, sendo os valores dos campos de deformaÃÃo obtidos pela CorrelaÃÃo de Imagem Digital (CID), comparando a imagem do corpo nÃo deformado com imagens do corpo deformado. E finalmente, avaliou-se os processos de danificaÃÃo do compÃsito, atravÃs da caracterizaÃÃo experimental da evoluÃÃo do dano isotrÃpico pelos mÃtodosda variaÃÃo do MÃdulo de Elasticidade efetivo (ensaio de traÃÃo com carga e descarga) e pelo Ãndice de Tsai-Wu com os parÃmetros constitutivos da funÃÃo tangente hiperbÃlica, onde os valores encontrados, em ambos os mÃtodos, mantiveram-se dentro da faixa esperada para compÃsitos, 0,20 â 0,50. / With increasing the ecological movements around the world, whose the main objective aims to raise awareness and encourage the world's population to save natural resources, coupled with the need to divert grounded waste (sanitary or industrial) in order to reduce environmental problems and public health, arising f rom the improper disposal of solid waste, emerge incentives for recy cling, and the development of biodegradable materials. Given this context, the composites reinforced with natural fibers began to be highlighted in the scientific community. However, its utilization is still seen with suspicion due to little or no knowledge of these pr omising materials. Faced with this problem, arose the proposal of this investigative character work, in with it was researched and devel oped a fully recycled composite, of thermoplastic matrix (recycl ed PVC) reinforced with fibers obtained from the bark of green coconut s discarded. For this objective were used various tools of physical, chemical, thermal and mechanical characterization, whose amounts of d eformation fields were obtained by Digital Image Correlation (DIC), c omparing the image of the body not deformed with images of the deforme d body. Finally, we assessed the processes of damage of the composite, through experimental characterization of the evolution of t he isotropic damage by the methods of varying the effective elastic mod ulus (tensile test with loading and unloading) and by Tsai-Wu index wi th the parameters constitutive of hyperbolic tangent function, where the values found, in both methods, were within the expected range for composite, from 0.20 to 0.50.
52

Comparison of the South African Spondaic and the CID W-1 wordlists for measuring speech recognition threshold

Hanekom, Tanya Heather January 2014 (has links)
INTRODUCTION. The Central Institute for the Deaf published Auditory Tests W-1 (CID W-1) spondaic wordlist was developed in the USA in 1947 and 1952. Certain American-English words contained in the wordlist are unfamiliar to many South Africans, even English first language (EFL) speakers, but particularly those who use English as a second language (ESL). Familiarity with spondaic words is one of the most important qualities of the test items used to determine Speech Recognition Threshold (SRT). OBJECTIVES. The aim of this study was to compare the SRT results obtained with the English South African Spondaic (SAS) wordlist developed by Durrant (2006) and the English CID W-1 spondaic wordlist when measuring the SRT of adult ESL speakers in South Africa. Method. Audiometric Pure Tone Average (PTA) and SRT measurements were obtained for 101 (197 ears) ESL participants with normal hearing or a minimal hearing loss <26 dBHL (mean age 33.3). PTA/SRT correlations were compared when using the SAS wordlist (groups one and two), as well as either the ‘less familiar’ CID W-1 (group one) or ‘more familiar’ CID W-1 (group two), in a mixed matched group design. RESULTS. A Pearson correlation analysis revealed a significant and positive correlation for all three wordlists. The Pearson correlation analysis revealed a strong PTA/SRT correlation when using the South African Spondaic (SAS) wordlist (right ear: 0.65; left ear 0.58) and the ‘more familiar’ words from the CID W-1 wordlist (right ear: 0.63; left ear: 0.56). The use of the ‘less familiar’ words from the CID W-1 wordlist revealed weak correlations (right ear: 0.30; left ear: 0.32). Paired sample T-tests indicated a statistically significantly stronger PTA/SRT correlation when the SAS wordlist was used, rather than either of the CID W-1 wordlists, at a 95% level of confidence. CONCLUSIONS. The use of the SAS wordlist yields a stronger PTA/SRT correlation than the use of the CID W-1 wordlist, when performing SRT testing as part of the speech audiometry battery on South African ESL speakers with normal hearing, or minimal hearing loss <26 dBHL. / Dissertation (MA)--University of Pretoria, 2014. / lk2014 / Speech-Language Pathology and Audiology / MA / Unrestricted
53

Aufbau und Anwendung einer Methode zur Identifizierung und Quantifizierung von Giften und deren Metaboliten in Blut und Haaren in der Systematischen Toxikologischen Analyse mittels Flüssigchromatographie-Quadrupol-Flugzeitmassenspektrometrie-Kopplung (LC-QTOF-MS)

Broecker, Sebastian 15 February 2012 (has links)
Die Systematische Toxikologische Analyse (STA) stellt auf Grund der großen Vielfalt und der ständigen Zunahme an toxikologisch relevanten Substanzen eine der größten Herausforderungen in der chemischen Analyse dar. In der vorliegenden Arbeit wurde daher die Eignung der Flüssigchromatographie in Kombination mit der Hybrid-Quadrupol-Flugzeitmassenspektrometrie (LC-QTOF-MS) für diesen Zweck untersucht. Dazu wurden eine Datenbank mit über 7360 und eine CID-Spektrenbibliothek mit mehr als 2720 toxikologisch relevanten Substanzen erstellt und geeignete Probenvorbereitungsmethoden entwickelt. Die Erprobung der Methoden erfolgte an dotierten Blut- und Haarproben. Hierbei zeigte sich, dass die Analyse im Auto-MS/MS-Modus (Messzyklen von MS- und MS/MS-Spektren) eine Identifizierung basischer Substanzen mittels CID-Spektren zwischen 0,5 und 2 ng/ml im Blut ermöglichte. Die Nachweisgrenzen der für 24 Wirkstoffe validierten Methode in Haaren lagen bei 3 bis 15 pg/mg. Die Eignung der LC-QTOF-MS zur STA von Haarproben wurde an 30 Drogentodesfällen und 60 Todesfällen mit bekannter chronischer Medikamenteneinnahme zu Lebzeiten sowie an 77 Blutproben nachgewiesen. Für die Suche nach Metaboliten wurde ein Metaboliten-Tool entwickelt. In der praktischen Anwendung auf Datenfiles von Blut- und Haarproben erwies sich das Tool als wertvolles Hilfsmittel zur Identifizierung unbekannter Peaks und zur Bestätigung von Suchergebnissen in der Datenbank. Zur automatischen Konzentrationsabschätzung identifizierter Substanzen wurde ein Tool „Estimate Concentration“ geschaffen. Die Überprüfung des Verfahrens an realen Blut- und Haarproben durch Vergleich mit HPLC-DAD- und GC-MS-Ergebnissen wies eine gute Übereinstimmung der Konzentrationen auf. Insgesamt zeigten die Untersuchungen, dass die LC-QTOF-MS zurzeit die am besten geeignete Methode für die STA darstellt. Auch bei einem erst später aufkommenden Verdacht kann eine gezielte Suche in dem bereits gemessenen Datenfile durchgeführt werden. / Due to the large variety and the steady increase of toxicologically relevant substances, systematic toxicological analysis (STA) is one of the most difficult tasks in analytical chemistry and, therefore, a steady topic of research and methodical improvement. For this reason, the suitability of liquid chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) for STA was investigated. For this purpose, a database of more than 7360 and a CID spectra library of more than 2720 toxicologically relevant substances and suitable methods for sample preparation were developed. The application was evaluated at spiked blood and hair samples. It was found that the analysis in Auto-MS/MS mode (alternating measurement cycles of MS and MS/MS spectra) allowed substance identification in blood using CID spectra between 0.5 and 2 ng/ml for basic substances. The detection limits of the validated method in hair ranged from 3 to 15 pg/mg for 24 drugs. The suitability of LC-QTOF-MS for STA was tested for hair samples from 30 drug-related death cases and from 60 death cases with known chronic medication as well as for 77 blood samples. For the search of metabolites, a metabolite tool was developed. In the practical application to data files from blood and hair samples, the tool proved to be very helpful for identification of unknown peaks and for confirmation of results obtained only from the database without CID spectra. A tool "Estimate Concentration" was created for automatic estimation of concentrations of identified substances. The application to real blood and hair samples and the comparison of the concentrations with results from HPLC-DAD and GC-MS showed good agreement. Overall, these investigations showed that LC-QTOF-MS is currently the most favorable method for STA. Because of the comprehensive registration of all substances in a sample, the data files can be checked for the presence of certain poisons even later without new measurements.
54

Do cantar de Mio Cid ao El Cid em quadrinhos: as representações do cavaleiro medieval em sala de aula

ALBARRAL, Érica Viana 25 September 2017 (has links)
Atualmente, é notável o interesse de um grande público pelas produções que evocam o passado medieval. Também em sala de aula, encontramos alunos que se deixam envolver pelos cenários, literaturas, histórias em quadrinhos, jogos, séries e filmes que tratam o período como algo fantástico, por isso, como um momento em que tudo é possível. O presente trabalho, objetiva analisar as representações do cavaleiro medieval, utilizando como elemento principal o Poema de Mio Cid. Por se tratar de uma pesquisa que visa a aplicabilidade do objeto estudado, utilizaremos em sala de aula as representações presentes no poema medieval e compararemos com os alunos o conceito de cavalaria incorporado por eles e pelas mídias de entretenimento. Como produto final, os alunos desenvolverão uma história em quadrinhos através da plataforma on-line Pixton. A criticidade dos alunos surge do confronto entre aquilo que se apresenta como ideal e provável, a partir da conceituação do professor. Esta interpretação dará aos alunos o desenvolvimento de sua autonomia em relação às visões dos autores de livros ou artigos, auxiliando-os a tornar a aprendizagem mais significativa. / Currently, it is remarkable the interest of a large audience for productions that evoke the medieval past. Also in the classroom, we found students who let themselves get involved by scenarios, literature, comics, games, series and movies that deal with the period as something fantastic, so, as a moment when everything is possible. The present study aims to analyze the representations of the medieval knight, using as main element the Poema de Mio Cid. Because it is a survey that seeks the applicability of object studied, we will use in class representations present in the medieval poem and compare with students the concept of chivalry incorporated by them and by the entertainment media. As final product, students will develop a comic book via the online platform Pixton. The criticality of the students comes from the confrontation between what is ideal and likely, from the conceptualization of the teacher. This interpretation will give the students the development of your autonomy in relation to visions of authors of books or articles, helping them to make learning more meaningful.
55

Analyse d'oligonucléotides par bombardement d'électrons rapides

Nguyen, Viet Hung 27 March 2012 (has links) (PDF)
L'objectif de ma thèse est d'étudier des oligonucléotides et mononucléotides par de nouvelles techniques de fragmentation comme l'EDD (Electron-Detachment-Dissociation) et l'EID (Electron-Induced-Dissociation) qui font intervenir un bombardement d'électrons. Les échantillons sont d'abord ionisés par une source electrospray (ESI) qui permet une ionisation douce. Au cours de mon travail de thèse, je me suis intéressé à l'étude de petits oligonucléotides (ADN et ARN simples brins) et de mononucléotides par EDD et EID. Tout d'abord nous optimisons les différents paramètres qui ont permis d'obtenir en ESI les espèces multichargées pour étudier les processus EDD, EID d'oligonucléotides à des états de charge différents, afin d'obtenir le maximum d'ions fragments. Ces spectres seront comparés avec les spectres SORI-CID (Collision-Induced-Dissociation) et IRMPD (Infrared-Multiphoton-Dissociation) pour mettre en évidence les spécificités de l'EDD et EID par rapport au SORI-CID. Les spectres EDD et EID montrent quelques ions fragments qui ne sont pas observés dans les spectres SORI-CID et IRMPD parce que ces derniers ne conduisent pas aux ions radicalaires. Grâce aux ions fragments radicalaires obtenus en EDD et en EID, nous avons pu accéder au séquençage d'oligonucléotides riches en thymine pour lesquels il est difficile d'obtenir des informations par les méthodes conventionnelles. Enfin nous avons utilisé des techniques particulières de la technologie ICR et qui seront présentées dans ce manuscrit
56

Primary T cell immunodeficiencies associated with disturbed proximal T cell receptor signalling caused by human autosomal recessive LCK, ZAP-70 and ITK-mutations

Hauck, Fabian 12 November 2013 (has links) (PDF)
T lymphocytes express either a preTCR, or a clonotyoic γδ TCR or αβ TCR together with the CD3-complex and the associated ζ-chain. TCR:CD3:ζ-signalling is crucial for T cell development and antigen-specific activation including proliferation, differentiation, effector functions and apoptosis of mature T cells. Protein tyrosine kinase (PTK) cascades lie at the heart of proximal TCR:CD3:ζ-signalling. The CSK-, SRC-, SYK- and TEC-family members C-terminal SRC kinase (CSK), lymphocyte-specific protein tyrosine kinase (LCK), ζ-chain associated protein tyrosine kinase of 70 kDa (ZAP-70) and interleukin-2-inducible T cell kinase (ITK), respectively, are the major T cell players. After TCR:CD3:ζ-complex triggering, activation of PTKs result in tyrosine phosphorylation signals. These include phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) of the CD3 and ζ-chains, adaptor proteins that nucleate the proximal LAT:SLP-76-signalosome controlling almost all TCR:CD3:ζ-induced signalling events. These events initiate Ca2+-flux, activation of mitogen-activated protein kinases (MAPKs), activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB), activation of nuclear factor of activated T cells (NFAT) and activator protein 1 (AP-1) as well as actin reorganization, cell-adhesion and motility.Througout the last five decades, the immune system has been extensively investigated in vitro and in animal models such as the murine system. Additionally, studying and taking care of human primary immunodeficiency diseases (PIDs) has been seminal for our understanding of the human immune system as animal models not always recapitulates the subtleties found in men.In my doctoral thesis I report the first case of autosomal recessive human LCK-deficiency, a novel autosomal recessive mutation leading to human ZAP-70-deficiency and a novel autosomal recessive mutation leading to human ITK-deficiency. I provide detailed clinical, immunological and biochemical analyses especially of TCR:CD3:ζ-signalling and compare my findings to the well-established Lck-/-, Zap-70-/- and Itk-/- murine models.
57

Flexibilités et hétérogéneités structurelles de biomolécules impliquées dans la transcription inverse du virus de l'immunodéficience humaine

Gelot, Thomas 22 October 2012 (has links) (PDF)
Le but de cette thèse est de sonder la flexibilité de NCp7 et de Δ(-)PBS, deux bio-molécules impliquées dans le second saut de brin de la transcription inverse du VIH. Deux stratégies expérimentales ont été mises en place. Un nouveau montage de spectroscopie ultra-rapide de fluorescence par down-conversion a été construit. Les dynamiques de quenching de la 2-aminopurine (2Ap), insérée en position 6, 8 et 10 de la boucle Δ(-)PBS ont pu être entièrement résolues à une résolution sub-ps. Pour chaque position, 4 temps de vie ont été révélés. Des mesures d'anisotropie confirment que les deux composantes < 5 ps sont liées à un empilement de la 2Ap avec les Guanines avoisinantes. Cet empilement est site-spécifique, prouvé par l'augmentation significative de leurs amplitudes lorsque la 2Ap est située près de la tige (position 10). La faible proportion de conformations reliées à un quenching collisionnel est significative de la faible exposition des 2Ap au solvant et de l'encombrement général de la boucle. La seconde approche avait pour but d'étudier l'effet du repliement du squelette protéique de [35-50] NCp7 autour de son atome de zinc par CID et par LID. Les spectres CID de la protéine nue sont expliqués par le modèle du proton mobile et une description détaillée d'un schéma de fragmentation spécifique autour du Tryptophane (Trp) a été soulignée, attribué une Lysine voisine. Un seul fragment issu de l'excitation à 266 nm a été identifié, son apparition entre en compétition avec les fragments CID du Trp. L'effet général du repliement autour du Zinc se traduit par une augmentation du taux de fragmentation autour du Trp et par une perte de spécificité pour le reste du spectre.Les flexibilités de Δ(-)PBS et NCp7 ont été respectivement évaluées par spectroscopie ultra-rapide de type down-conversion et par spectrométrie en phase gazeuse. La première méthode nécessite l'utilisation d'une sonde fluorescente non invasive, la 2-aminopurine (2Ap), placée en position 6, 8 et 10 de la boucle Δ(-)PBS. Notre résolution temporelle permet de résoudre entièrement les dynamiques locales de quenching et d'anisotropie de la 2Ap. Les composantes liées au quenching statique et quenching collisionnel ont été discriminées et révèlent les degrés d'empilement / encombrement locaux de la boucle. L'effet du repliement de [35-50] NCp7 autour de son atome de zinc a été étudié par CID et par LID à 266 nm. La protéine nue présente un interessant shéma de fragmentation autour du Tryptophane (Trp), exalté par la complexation avec le zinc, au prix une perte de spécificité pour le reste du spectre. Un seul fragment LID a été identifié, un mécanisme de sa formation est proposé.
58

Primary T cell immunodeficiencies associated with disturbed proximal T cell receptor signalling caused by human autosomal recessive LCK, ZAP-70 and ITK-mutations

Hauck, Fabian 12 November 2013 (has links) (PDF)
T lymphocytes express either a preTCR, or a clonotypic γδ TCR or αβ TCR together with the CD3-complex and the associated ζ-chain. TCR:CD3:ζ-signalling is crucial for T cell development and antigen-specific activation including proliferation, differentiation, effector functions and apoptosis of mature T cells. Protein tyrosine kinase (PTK) cascades lie at the heart of proximal TCR:CD3:ζ-signalling. The CSK-, SRC-, SYK- and TEC-family members C-terminal SRC kinase (CSK), lymphocyte-specific protein tyrosine kinase (LCK), ζ-chain associated protein tyrosine kinase of 70 kDa (ZAP-70) and interleukin-2-inducible T cell kinase (ITK), respectively, are the major T cell players. After TCR:CD3:ζ-complex triggering, activation of PTKs results in tyrosine phosphorylation signals. These include phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) of the CD3 and ζ-chains, and adaptor proteins that nucleate the proximal LAT:SLP-76-signalosome controlling almost all TCR:CD3:ζ-induced signalling events. These events initiate Ca2+-flux, activation of mitogen-activated protein kinases (MAPKs), activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB), activation of nuclear factor of activated T cells (NFAT) and activator protein 1 (AP-1) as well as actin reorganization, cell-adhesion and motility. Throughout the last five decades, the immune system has been extensively investigated in vitro and in animal models such as the murine system. Additionally, studying and taking care of human primary immunodeficiency diseases (PIDs) has been seminal for our understanding of the human immune system as animal models not always recapitulate the subtleties found in men. In my doctoral thesis I report the first case of autosomal recessive human LCK-deficiency, a novel autosomal recessive mutation leading to human ZAP-70-deficiency and a novel autosomal recessive mutation leading to human ITK-deficiency. I provide detailed clinical, immunological and biochemical analyses especially of TCR:CD3:ζ-signalling and compare my findings to the well-established Lck-/-, Zap-70-/- and Itk-/- murine models.
59

Hypervisor-based cloud anomaly detection using supervised learning techniques

Nwamuo, Onyekachi 23 January 2020 (has links)
Although cloud network flows are similar to conventional network flows in many ways, there are some major differences in their statistical characteristics. However, due to the lack of adequate public datasets, the proponents of many existing cloud intrusion detection systems (IDS) have relied on the DARPA dataset which was obtained by simulating a conventional network environment. In the current thesis, we show empirically that the DARPA dataset by failing to meet important statistical characteristics of real-world cloud traffic data centers is inadequate for evaluating cloud IDS. We analyze, as an alternative, a new public dataset collected through cooperation between our lab and a non-profit cloud service provider, which contains benign data and a wide variety of attack data. Furthermore, we present a new hypervisor-based cloud IDS using an instance-oriented feature model and supervised machine learning techniques. We investigate 3 different classifiers: Logistic Regression (LR), Random Forest (RF), and Support Vector Machine (SVM) algorithms. Experimental evaluation on a diversified dataset yields a detection rate of 92.08% and a false-positive rate of 1.49% for the random forest, the best performing of the three classifiers. / Graduate
60

Studium využití derivatizačních reakcí pro ESI-MS analýzu obtížně ionizovatelných aryl chlorokomplexů rhenia / Study of derivatization reactions for ESI-MS analysis of hardly ionizable rhenium aryl chlorocomplexes

Vlk, Mikuláš January 2020 (has links)
Mass spectrometry with electrospray ionization is an excellent method for structural analysis of coordination compounds with outstanding sensitivity and selectivity. However, it fails to detect some low-polar rhenium complexes. This master thesis describes derivatization method of non-ionizable rhenium complexes with 1,2-dihydroxybenzene and 2,3- dihydroxytoluenene. Fragmentation mechanisms and structure of prepared complexes was studied using high resolution mass spectrometry and collision-induced dissociation (CID). Furthermore, density functional theory (DFT) computational method was used for prediction of bond cleavage based on bond lengthening.

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