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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.
1

Effect of Scanning Conditions on Cone Beam Computed Tomography Gray Value

England, Gregory Miles 12 September 2016 (has links)
No description available.
2

Avaliação endoscopica, laboratorial e tomografica das vias aereas superiores de pacientes com fibrose cistica e sua correlação com genotipo e a gravidade da doença / Nasal paranasal sinus endoscopy, computed tomography and laboratorial aspects of upper airways and the correlations with genotype and severity of cystic fibrosis

Sakano, Eulalia, 1950- 28 July 2006 (has links)
Orientador: Jose Dirceu Ribeiro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T02:23:41Z (GMT). No. of bitstreams: 1 Sakano_Eulalia_D.pdf: 4393830 bytes, checksum: 9f6f7365bd3d89dbba87535f36bbc052 (MD5) Previous issue date: 2006 / Resumo: Muitos estudos têm avaliado os aspectos clínicos e funcionais do comprometimento das vias aéreas inferiores na fibrose cística (FC). Entretanto, poucos estudos têm sido realizados para avaliar as alterações clínicas e funcionais das vias aéreas superiores. O objetivo do presente trabalho foi correlacionar variáveis obtidas por endoscopia nasossinusal, laboratoriais e tomográficas dos seios paranasais e, verificar a associação com a gravidade e o genótipo de pacientes com fibrose cística, de um centro universitário de referência em tratamento de FC no Brasil. Realizou-se um estudo clínico, laboratorial com 50 fibrocísticos. Todos foram submetidos a tomografia computadorizada dos seios paranasais, estudo genético das mutações da FC, endoscopia nasossinusal e bacterioscopia dos seios maxilares, orofaringe e traquéia. A gravidade da FC foi avaliada pelo escore de Shwachman. A prevalência de polipose na população estudada foi de 36% e maior entre homozigotos para ?F508. O escore de Shwachman correlacionou-se com a idade. Não houve correlação do genótipo e do grau de gravidade com as outras variáveis estudadas. Os sujeitos apresentaram alta prevalência de colonização precoce para P. aeruginosa. Concluiu-se que a doença sinusal em pacientes fibrocísticos é muito freqüente, apresenta alterações nasofibroscópicas, tomográficas e clínicas, embora a maioria das variáveis estudadas, não apresenta correlação com a gravidade e o genótipo da doença / Abstract: Many studies have assessed clinical and functional aspects of lower airway affections in cystic fibrosis. Conversely, few studies have been performed to assess the clinical and functional affections of upper airways. The objective of the present study was to correlate the variables obtained by nasal and paranasal sinuses endoscopy, paranasal sinus laboratory and computed tomography (CT) scan findings, and to check the association with severity and genotype of cystic fibrosis patients. Clinical and laboratory study of 50 patients with cystic fibrosis at a university center. All patients were submitted to CT scan, nasal and paranasal endoscopy and bacterioscopy of maxillary sinus, trachea and oropharynx secretion. Severity of cystic fibrosis was assessed by Shwachman score and the most frequent genetic mutations were identified. The prevalence of polyposis in the studied population was 36% and it was greater among homozygote for ?F 508. Shwachman score was correlated with age (p=0,003). The genotype was correlated with nasal polyposis (p=0,006). There was no association between affections in CT scan and severity of cystic fibrosis (CF). Patients presented high prevalence of early colonization of Pseudomonas aeruginosa. Sinus disease in CF patients are very frequent and presents several clinical, endoscopic and tomographic affections and most of them are not correlated with severity and disease genotype / Doutorado / Otorrinolaringologia / Doutor em Ciências Médicas
3

Acurácia de dois tomógrafos na detecção de fraturas radiculares verticais em dentes com retentores metálicos intracanais / Accuracy of two cone beam computed tomography systems for the detection of vertical root fractures

Siqueira, Claudeir Felipe de Oliveira 10 March 2017 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-19T12:09:37Z No. of bitstreams: 2 Dissertação - Claudeir Felipe de Oliveira Siqueira - 2017.pdf: 2068338 bytes, checksum: b1222b1c483b31d5a02f7ca3259bb2aa (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-19T12:13:10Z (GMT) No. of bitstreams: 2 Dissertação - Claudeir Felipe de Oliveira Siqueira - 2017.pdf: 2068338 bytes, checksum: b1222b1c483b31d5a02f7ca3259bb2aa (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-04-19T12:13:10Z (GMT). No. of bitstreams: 2 Dissertação - Claudeir Felipe de Oliveira Siqueira - 2017.pdf: 2068338 bytes, checksum: b1222b1c483b31d5a02f7ca3259bb2aa (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-03-10 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Vertical root fracture (VRF) is a dental lesion with worse prognosis in dentistry, the diagnosis is made from clinical evaluation, and image exams, clinically the symptoms are signaled and not pathognomonic and even with the introduction of cone beam computed tomography, the metallic artifacts resulting from the images obtained still make it difficult to detect VRF. The aim of this study was to evaluate the accumulation of Eagle 3D and i-Cat tomography in the detection of VRF in endodontically treated single-root teeth with post metallic intracanal. This study was approved by the Research Ethics Committee of UFG under the number 477.315. 30 single-root teeth were endodontically treated and prepared with metal pins. The sample was divided randomly in Control Group (CTL) and Fractured Group (FRT). The fractures were made only in FRT Group by the Universal Test machine, with load cell 500N and speed of 1mm/ min. The teeth were placed in dry jaw and placed in a vessel with distilled water to be purchased as TCFC images by Eagle 3D tomographs (protocol 1: FOV 5X5 cm and voxel: 0.1 mm - protocol 2: FOV 6X8 cm and voxel: 0.16 mm) and i-CAT (protocol 3: FOV 8 × 8 cm and voxel: 0.125 mm - protocol 4: FOV 8 × 8 cm and voxel: 0.2 mm). Two experienced evaluators classified as composite images by absence of fracture or by subjective revisions of an interference of the formation of non-diagnostic artefacts and reconstruction type and efficient in the detection of VRF. The inter-examiner agreement was verified by kappa test. Measurements of sensitivity, specificity and accuracy were adopted for each device. The area under the ROC curve was also calculated and compared using the ANOVA. The results indicated that protocols 1 and 3 were more accurate (AUC protocol 1: 0.784 - p <0.05 and AUC protocol 2: 0.729 - p <0.05). According to the subjective evaluation of the examiners, in protocols 1 and 4 of greater interference of the formation of artifacts without diagnosis of VRF and a parasagittal reconstruction was the most efficient for a detection of the fracture line. It is concluded that protocols 1 and 3 highlight a better performance in the detection of VRF and that the size of voxel is a factor that directly influences the accuracy. / Resumo: A fratura radicular vertical (FRV) é a lesão dentária com o pior prognóstico na Odontologia. O diagnóstico é um desafio, pois clinicamente os pacientes apresentam sinais e sintomas não patognomônicos e apesar da introdução da tomografia computadorizada de feixe cônico (TCFC) como ferramenta de diagnóstico , os artefatos metálicos resultantes das imagens obtidas tornam difícil a detecção da FRV. Vários fatores de digitalização e reconstrução incluindo FOV (Field of view), tamanho do voxel, o número de projeções base (aquisições) para a reconstrução e a formação de artefatos na imagem tem influência significativa na acurácia do exame. O objetivo deste trabalho foi avaliar a acurácia dos tomógrafos Eagle 3D e i-Cat na detecção de FRV em dentes unirradiculares tratados endodonticamente com retentor metálico intracanal. Foram tratados endodonticamente e confeccionados pinos metálicos em 30 dentes unirradiculares. A amostra foi randomicamente dividida em dois grupos: Grupo Controle (CTL) e Grupo Fraturado (FRT). As fraturas foram confeccionadas somente no Grupo FRT pela Máquina de Ensaios Universal, com célula de carga 500N e velocidade de 1mm/min. Os dentes foram posicionados em mandíbula seca e colocados em um recipiente com água destilada para serem adquiridas as imagens de TCFC pelos tomógrafos Eagle 3D (protocolo 1: FOV 5X5 cm e voxel: 0,1 mm - protocolo 2: FOV 6X8 cm e voxel: 0,16 mm) e i-CAT (protocolo 3: FOV 8X8 cm e voxel: 0,125 mm - protocolo 4: FOV 8X8 cm e voxel: 0,2 mm). Dois avaliadores experientes classificaram as imagens conforme a presença ou ausência de fratura e avaliaram a interferência dos artefatos e do tipo de reconstrução na detecção de FRV. A concordância interexaminador foi verificada pelo teste kappa. As medidas de sensibilidade, especificidade e acurácia foram medidas para cada aparelho. Também foi calculada a área sob a curva (AUC) ROC, e os resultados comparados utilizando o modelo de análise variância (ANOVA). Os resultados indicaram que os protocolos 1 e 3 foram mais acurados (AUC protocolo 1: 0,784 – p<0,05 e AUC protocolo 2: 0,729 – p<0,05). Segundo avaliação subjetiva dos examinadores, nos protocolos 1 e 4 há maior interferência da formação de artefatos no diagnóstico de FRV e a reconstrução transversal se mostrou mais eficiente para a detecção da linha de fratura. Conclui-se que os protocolos 1 (Eagle 3D: FOV 5X5 cm e voxel: 0,1 mm) e 3 (i-CAT: FOV 8X8 cm e voxel: 0,125 mm) apresentam melhor acurácia na detecção de FRV e que o tamanho do voxel é um fator que influência diretamente na acurácia
4

Study of process parameters in laser beam welding of copper hairpins

Lönn, Dan, Spångberg, David January 2022 (has links)
This study had the purpose to further the use of industrial lasers in the manufacturing of hairpin electric motors by optimizing the process of contacting the hairpins. A problem with laser beam welding of copper is the porosity created in the process which can lead to increased resistance of the welded region along with degraded mechanical properties. By experiment this study aimed to find the optimal parameters to reduce the porosity while maintaining all other requirements for the weld. The track of achieving a satisfactory simulation was done to minimize the need of physical experiments which can be argued as a sustainable development aspect. A set of parameters was found that achieved a low volume of pores, a sufficient weld depth and a desirable bead geometry. Some pores still remained, mostly at the endpoint of the laser path which could be caused by the laser shut-off leading to a keyhole collapse enclosing some pores in that region. The simulation showed promising results in welding depth and melt region. Further work on ramping the laser power at the endpoint could be beneficial for eliminating the remaining porosity as well as refining the simulation in terms of porosity.
5

Αθηρωμάτωση του συστήματος των βρογχικών αρτηριών και πιθανός συσχετισμός με την στεφανιαία κυκλοφορία

Κωτούλας, Χριστόφορος 22 December 2008 (has links)
Σκοπός: Διεξάγαμε την παρούσα μελέτη για να καταδείξουμε την ύπαρξη των βρογχικο-στεφανιαίων αναστομώσεων στο πειραματικό μοντέλο του χοίρου. Επιπλέον διερευνήσαμε την επίπτωση της αρτηριοσκλήρυνσης στις βρογχικές αρτηρίες. Υλικό – Μέθοδος: Χρησιμοποιήθηκαν τα παρασκευάσματα καρδιάς και πνευμόνων από 6 χοίρους. Επιπλέον, δείγματα βρογχικών αρτηριών ελήφθησαν από 40 ασθενείς που υποβάλλονταν σε θωρακοτομή. Σημειώθηκαν αναλυτικά οι κλινικοί και εργαστηριακοί παράγοντες κινδύνου για ανάπτυξη αρτηριοσκλήρυνσης. Αποτελέσματα: Με υπολογιστική τομογραφία, ψηφιακή αγγειογραφία και χορήγηση χρωστικής ρητίνης καταδείξαμε το αναστομωτικό δίκτυο μεταξύ των βρογχικών και κυρίως των αριστερών στεφανιαίων αρτηριών σε 5 από τα 6 παρασκευάσματα. Η μικροσκοπική εξέταση των δειγμάτων δεν στοιχειοθέτησε ύπαρξη αθηροσκλήρυνσης, παρά μόνο ύπαρξη ασβεστοποιού σκλήρυνσης του μέσου χιτώνα σε ποσοστό 2.5%, που δεν συσχετίστηκε με τους παράγοντες κινδύνου αρτηριοσκλήρυνσης. Συμπεράσματα: Με δεδομένο ότι βρογχικές αρτηρίες παρουσιάζουν ελάχιστο βαθμό ασβεστοποιού σκλήρυνσης του μέσου χιτώνα., υποθέτουμε ότι θα μπορούσαν να συνδράμουν στη στεφανιαία κυκλοφορία μέσω των προαναφερθεισών αναστομώσεων σε καταστάσεις εκσεσημασμένης στεφανιαίας νόσου. Η μελέτη μας υπογραμμίζει την σπουδαιότητα των βρογχικών αρτηριών και των βρογχικο-στεφανιαίων αναστομώσεων σε περιπτώσεις εμβολισμού των βρογχικών αρτηριών, μεταμοσχεύσεων καρδιάς-πνευμόνων και αντιμετώπισης ανευρυσμάτων θωρακικής αορτής. / Aim of the study: We conducted this study to demonstrate the coronary-bronchial anastomotic routes in a porcine model. Additionally, we estimated the incidence of bronchial arteries arteriosclerosis. Material and Methods: Six heart-lung porcine blocks were used. Furthermore, 40 bronchial arteries were obtained from patients who underwent thoracotomy. Detailed clinical and laboratory atherosclerotic risk factors of the patients were documented. Results: Using CT-scan, Digital Subtraction Angiography and colored latex, we demonstrated communications between the bronchial and coronary circulation in 5 of 6 subjects. Histology revealed no established atherosclerotic lesion and narrowing of the lumen, but medial calcific sclerosis in 2.5%, that was independent from the arteriosclerotic risk factors. Conclusions: As evidence suggests that bronchial arteries only exhibit medial calcific sclerosis, we hypothesize that bronchial arteries can contribute to the coronary flow through the broncho-coronary anastomoses in cases of severe coronary artery disease. Our study emphasizes their importance and their anastomoses to coronaries in cases of embolization, heart-lung transplantation and thoracic aorta aneurysms repair.

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