This thesis belongs to the research line of Biomedical Imaging Tecnologies and proposes as main objective to develop and research spatio-temporal non-rigid registration methods to estimate and compesate motion in cardiac magnetic resonance sequences and to validate and verify the suitability of those techniques in the clinical environment. / -

MultiDetector-row Computed Tomography (MDCT) or MultiSlice Computed Tomography (MSCT) has undergone remarkable progress since its first introduction at the end of the 1990s. Given that CT examinations are generally recognized as a relatively high-dose procedure, concern has been expressed at the associated increase in doses. The International Committee on Radiation Protection (ICRP) noted in their report No.87 that absorbed doses in tissues from CT are among the highest observed in diagnostic radiology (i.e. 10–100 mGy). Therefore, the purpose of this thesis is to calculate the dosimetric quantities for brain, chest, and abdomen-pelvis examinations that were carried out using Philips Brilliance 16 and Brilliance 64 CT Scanners of the University General Hospital “Attikon”, as well as to perform their intercomparison. For brain examinations, axial technique was utilized. However, for chest and abdomen-pelvis examinations, spiral technique was applied. The effect of overranging (or overscanning) is connected with spiral mode and its contribution to patient dose is really important in case of MSCT scanners. Therefore, the contribution of the overrange effect for body examinations carried out was calculated. In the framework of this thesis, the contribution of overrange to the effective dose received by patients submitted to the forementioned examinations is calculated. Additionally, dose measurements were carried out in order to estimate the radiation burden to the eye lenses and the thyroid during the typical brain examination, both when eye lenses are inside and outside the irradiation field. / Οι Υπολογιστικοί Τομογράφοι (ΥΤ) πολλαπλών τομών έχουν σημειώσει μεγάλη πρόοδο από την κλινική εφαρμογή τους στις αρχές του 1990. Λαμβάνοντας υπ’ όψιν ότι οι εξετάσεις ΥΤ συνεπάγονται υψηλή ακτινική επιβάρυνση του ασθενή, η μελέτη τους έχει συγκεντρώσει το ερευνητικό ενδιαφέρον της επιστημονικής κοινότητας. Η Διεθνής Επιτροπή Ακτινοπροστασίας (ICRP) επισημαίνει στην αναφορά Νο 87 ότι η απορροφούμενη δόση στους ιστούς από εξετάσεις ΥΤ είναι από τις υψηλότερες στη διαγνωστική ακτινολογία (10-100 mGy). Συνεπώς, σκοπός της παρούσας διπλωματικής εργασίας είναι ο υπολογισμός των δοσιμετρικών μεγεθών για τις συνήθεις εξετάσεις εγκεφάλου, θώρακος και άνω-κάτω κοιλίας, οι οποίες πραγματοποιούνται με τους ΥΤ πολλαπλών τομών Brilliance 16 και Βrilliance 64 της Philips στο Π.Γ.Ν “ΑΤΤΙΚΟΝ ”,καθώς επίσης και η σύγκριση των αντίστοιχων δόσεων μεταξύ των συγκεκριμένων ΥΤ. Οι ασθενείς που υποβάλλονται σε εξετάσεις θώρακος και άνω-κάτω κοιλίας που πραγματοποιούνται με ελικοειδή τεχνική λαμβάνουν επιπλέον δόση (overscan) που οφείλεται στην τεχνική αυτή. Η συνεισφορά του “overscan” είναι ιδιαίτερα σημαντική στους ΥΤ πολλαπλών τομών, οπότε επιπλέον στόχος αυτής της διπλωματικής είναι ο υπολογισμός της. Τέλος, πραγματοποιήθηκαν μετρήσεις της δόσης του θυρεοειδή και των φακών των οφθαλμών κατά την υποβολή ασθενών στη συνήθη εξέταση εγκεφάλου, τόσο στην περίπτωση παρουσίας των οφθαλμών εντός όσο και εκτός πεδίου ακτινοβόλησης.

Σκοπός της παρούσας μεταπτυχιακής εργασίας ειδίκευσης είναι η πειραματική μελέτη και η θεωρητική πρόβλεψη των εναπομενουσών μηχανικών ιδιοτήτων, πολυμερών και πολυμερικών σύνθετων υλικών, μετά από χαμηλής ενέργειας επαναλαμβανόμενη κρουστική καταπόνηση. Στα πλαίσια της εργασίας μελετήθηκαν δύο διαφορετικά πολυμερικά υλικά (EP και PMMA) και δύο πολυμερικά σύνθετα υλικά (CFRP και GFRP). Τα δοκίμια από εποξειδική ρητίνη υποβλήθηκαν σε επαναλαμβανόμενη κρούση, με σταθερή ενέργεια κρούσης κάθε φορά, 1.25 Joule, ενώ τα υπόλοιπα δοκίμια σε επαναλαμβανόμενη κρούση, με σταθερή ενέργεια κρούσης 1 Joule. Μετά την κρούση, τα δοκίμια χαρακτηρίστηκαν μηχανικά με στατικά πειράματα κάμψης τριών σημείων, έτσι ώστε να μελετηθεί η υποβάθμιση, τόσο του μέτρου ελαστικότητας σε κάμψη, όσο και η μέγιστη αντοχή τους σε κάμψη, σαν συνάρτηση του αριθμού κρούσεων. Ανάλογα με το υλικό, παρατηρήθηκε και διαφορετικό μέγεθος υποβάθμισης, γεγονός που οφείλεται στη λειτουργία διαφορετικών μηχανισμών αστοχίας. Από θεωρητικής σκοπιάς, εφαρμόστηκαν δύο διαφορετικά μοντέλα πρόβλεψης των εναπομενουσών μηχανικών ιδιοτήτων. Το μοντέλο Παπανικολάου – Σταυρόπουλου και το μοντέλο Πρόβλεψης των Εναπομενουσών Ιδιοτήτων (Residual Property Model – R.P.M.) που εφαρμόστηκαν, έδωσαν αποτελέσματα άκρως ικανοποιητικά, με πολύ καλή σύγκλιση των πειραματικών αποτελεσμάτων με τις θεωρητικές προβλέψεις. / The purpose of the present work was to experimentally investigate the residual strength and stiffness of polymers and polymer-matrix composites and to theoretically predict the observed degradation by means, after low energy repeated impact. Two different types of composites (CFRP and GFRP) and two types of polymers (EP and PMMA), were examined. The plates of epoxy resin were repeatedly impacted with constant amount of impact energy on the order of 1.25 J and the rest of the above materials with constant impact energy on the order of 1.00 J. Afterwards the damaged specimens were tested under three-point bending conditions in order to investigate the degradation of both the bending modulus and strength as a function of the number of impacts. The results showed that there is a characteristic threshold of impact accumulated energy and/or number of repeated impacts, above which an abrupt degradation of the mechanical properties was observed. From theoretical point of view the measured variations were predicted by applying two different models. Namely, the Papanicolaou – Stavropoulos model and second the Residual Property Model (R.P.M.) have been applied in order to predict the observed degradations, using a minimum number of input data (one or two points only). A fair agreement between experimental results and theoretical predictions was found.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was to study the relationship between liquid discharge and suspended sediment discharge by various methods. The study was carried out at Menino Deus IV Fluviometric Station, located in Santa Maria/RS. It was relating to solid discharge in suspension, using all samples in full waves and without precipitation, with the liquid discharge using the integrated sampler USDH 48 and ISCO sampler punctual. The coefficient of determination of 93.4 % and 85.0 %, were obtained respectively, to the samplers USDH 48 and ISCO, can be considered a good correlation. Also were related the turbidity with the sediments concentration in suspension, obtaining the solid discharge calculated with the liquid discharge using the sampler integrator USDH 48. A correlation coefficient of 93.0 % with all samples and the ISCO 85.2 % were obtained. It was observed that the automatic measurements by turbidity become a viable alternative due to the easy to install and to possible a continuous monitoring and automatic, without the presence of a technician in place, further obtaining similar results to the traditional methods which is recommended in this study. To determine the liquid discharge, the hydrometric windlass traditional method and the acoustic method was used, using an Acoustic Doppler Profiler (ADP). It can be concluded that with the depths less than 0.28 m, the ADP did not execute the reading speed and the presented reading failures. Thus, for measurements in these conditions, it is suggested to use the hydrometric windlass, because it is a device that provides more detail and flexibility when handling. / O objetivo deste trabalho foi estudar as relações entre descarga líquida e descarga sólida em suspensão segundo diferentes métodos. O trabalho foi realizado na Estação Fluviométrica Menino Deus IV, localizada em Santa Maria/RS. Relacionou-se a descarga sólida em suspensão, utilizando todas as amostras em ondas de cheia e dias sem precipitação, com a descarga líquida utilizando o amostrador integrado USDH 48 e o amostrador pontual ISCO. Obteve-se coeficientes de determinação de 93,4% e 85,0%, respectivamente para os amostradores USDH 48 e ISCO, podendo ser considerada uma boa correlação. Relacionou-se também a turbidez com a concentração de sedimentos em suspensão, obtendo a descarga sólida calculada com a descarga líquida utilizando o amostrador integrador USDH 48. Obteve-se um coeficiente de correlação de 93,0% com todas as amostras e com o ISCO de 85,2%. Observou que as medições automáticas de turbidez tornam-se uma alternativa viável em função da facilidade de instalação e por possibilitar um monitoramento contínuo e automático, sem a presença de um técnico no local, além da obtenção de resultados próximos aos métodos tradicionais sendo este o recomendado neste estudo. Para a determinação da descarga líquida, utilizou-se o método tradicional do molinete hidrométrico e o método acústico, utilizando o Acoustic Doppler Profiler (ADP). Pode-se concluir que com as profundidades inferiores a 0,28 m, o ADP não apresentou falhas na leitura de velocidade. Assim, para medições nestas condições, sugere-se utilizar o molinete hidrométrico, pois é um equipamento que fornece mais detalhes e agilidade no momento de manuseio.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-20T21:00:39Z No. of bitstreams: 1 AlexsandraRodriguesDoNascimento_TESE.pdf: 3128857 bytes, checksum: db683b893d3db23b5af91852c4aed0e3 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-21T20:23:04Z (GMT) No. of bitstreams: 1 AlexsandraRodriguesDoNascimento_TESE.pdf: 3128857 bytes, checksum: db683b893d3db23b5af91852c4aed0e3 (MD5) / Made available in DSpace on 2016-01-21T20:23:04Z (GMT). No. of bitstreams: 1 AlexsandraRodriguesDoNascimento_TESE.pdf: 3128857 bytes, checksum: db683b893d3db23b5af91852c4aed0e3 (MD5) Previous issue date: 2014-09-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Diversos materiais est?o atualmente em estudo para o processo de captura de CO2, a exemplo dos ?xidos met?licos e ?xidos met?licos mistos, ze?litas, materiais carbon?ceos, estruturas metal-org?nicas (MOF?s), organos?lica e superf?cies de s?lica modificadas. Neste trabalho, analisou-se a capacidade de adsor??o de CO2 em materiais mesoporosos de diferentes estruturas, como o MCM-48 e SBA-15, sem impregna??o e impregnados com n?quel nas propor??es 5 %, 10 % e 20 % (m/m), denominados como 5Ni-MCM-48, 10NiMCM-48, 20Ni-MCM-48 e 5Ni-SBA-15, 10Ni-SBA-15, 20Ni-SBA-15. Os materiais foram caracterizados atrav?s das an?lises de difra??o de raios X (DRX), an?lise t?rmica (TG e DTG), espectroscopia na regi?o do infravermelho com transformada de Fourier (FT-IR), adsor??o e dessor??o de N2 (BET) e microscopia eletr?nica de varredura (MEV) com EDS. O processo de adsor??o foi realizado variando-se a press?o de 100 - 4000 kPa e mantendo-se a temperatura constante e igual a 298 K. Na press?o de 100 kPa, as maiores concentra??es de adsor??o ocorreram para os materiais 5Ni-MCM-48 (0,795 mmol g-1 ) e SBA-15 (0,914 mmol g -1 ) n?o impregnado, e, na press?o de 4000 kPa, para os materiais MCM-48 (14,89 mmol g-1 ) e SBA-15 (9,97 mmol g-1 ) n?o impregnados. Os resultados mostraram que a capacidade de adsor??o varia positivamente com a ?rea espec?fica, no entanto, apresenta uma depend?ncia direta com o tipo e geometria dos canais da estrutura porosa. Os dados obtidos foram ajustados atrav?s dos modelos de Langmuir e Freundlich e os par?metros termodin?micos avaliados foram energia livre de Gibbs e entropia do sistema de adsor??o / Several materials are currently under study for the CO2 capture process, like the metal oxides and mixed metal oxides, zeolites, carbonaceous materials, metal-organic frameworks (MOF's) organosilica and modified silica surfaces. In this work, evaluated the adsorption capacity of CO2 in mesoporous materials of different structures, such as MCM-48 and SBA- 15 without impregnating and impregnated with nickel in the proportions 5 %, 10 % and 20 % (m/m), known as 5Ni-MCM-48, 10Ni-MCM-48, 20Ni-MCM-48 and 5Ni-SBA-15, 10NiSBA-15, 20Ni-SBA-15. The materials were characterized by means of X-ray diffraction (XRD), thermal analysis (TG and DTG), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption and desorption (BET) and scanning electron microscopy (SEM) with EDS. The adsorption process was performed varying the pressure of 100 - 4000 kPa and keeping the temperature constant and equal to 298 K. At a pressure of 100 kPa, higher concentrations of adsorption occurred for the materials 5Ni-MCM-48 (0.795 mmol g-1 ) and SBA-15 (0.914 mmol g-1 ) is not impregnated, and at a pressure of 4000 kPa for MCM-48 materials (14.89 mmol g-1) and SBA-15 (9.97 mmol g-1) not impregnated. The results showed that the adsorption capacity varies positively with the specific area, however, has a direct dependency on the type and geometry of the porous structure of channels. The data were fitted using the Langmuir and Freundlich models and were evaluated thermodynamic parameters Gibbs free energy and entropy of the adsorption system

abstract: This study examines determinants of the length of conflict between firms and the Internal Revenue Service (IRS). I hand collect firm disclosures of the number of years open for federal tax purposes to create a proxy for IRS conflict length. Using this proxy, I find evidence that larger firms, firms with more book-tax differences, and firms facing higher IRS attention and audit probabilities are associated with lengthier IRS conflicts. In contrast, firms with higher deferred tax assets, intangibles, return on assets, and firms disclosing participation in the Compliance Assurance Process program are associated with shorter IRS conflicts. Additional analyses show IRS conflict length is positively associated with manager risk preferences and poor tax accounting quality. I also find lengthier IRS conflicts are associated with higher future tax risk and higher audit fees. Tax controversy is becoming increasingly important for firms but remains relatively understudied. I provide empirical evidence on cross-sectional variation in IRS conflict length. / Dissertation/Thesis / Doctoral Dissertation Accountancy 2020

L’Imagerie par Résonance Magnétique est une technique d’imagerie possédant une des plus hautes résolutions d’images, utilisée pour le diagnostic clinique et en recherche. Cependant cette technique souffre d’une faible sensibilité intrinsèque due au faible contraste naturel entre les différents tissus. Pour pallier à cette limitation, des agents de contraste, principalement des complexes de Gd(III), sont actuellement utilisés et continus d’être développés. Ce projet de thèse s’inscrit dans la volonté de concevoir de nouveaux agents de contrastes plus efficaces et plus stables en utilisant la β- et l’α-cyclodextrines (CD) comme plateforme capables d’intégrer trois ou quatre fonctions pyridine-carboxylates ou pyridine-phosphonates, connues pour leur pouvoir chélatant du Gd(III). La première partie des travaux concerne les aménagements fonctionnels des CDs afin de pouvoir les fonctionnaliser régiosélectivement avec des bras chélatants du Gd(III) de types pyridino-carboxylate et pyridino-phosphonate. La deuxième partie traite de la caractérisation physico-chimique des nouveaux systèmes complexes Gd-ligands synthétisés (Gd-Lα et Gd-Lβ). Les principales propriétés caractérisant les agents de contraste ont été mesurées. Ainsi, de très bonne relaxivités ont été obtenue (25 mM-1s-1 < r1 < 40 mM-1s-1). Cependant, les stabilités des complexes se sont avérées faibles (4,24 < log KGdL < 5,58). En perspectives, il est nécessaire d’obtenir un juste équilibre entre une forte relaxivité et une stabilité élevée pour assurer la non-libération du Gd(III) toxique. / Magnetic Resonance Imaging is one of the most important and non-invasive tools for clinical diagnostics and biomedical researches. Nevertheless, this modality suffers from intrinsic low sensitivity. To overcome this limitation, contrast agents, mostly based on polyaminocarboxylate complexes of gadolinium are used. The aim of this project was to design new Gd(III)-based contrast agents using β- and α-cyclodextrins (CD), known to generate high relaxivity, functionalized with pyridine-carboxylate and pyridine-phosphonate ligands, known for their good affinity with the lanthanide cations. Here we first investigated the regio-functionalization of the β-CD on the primary face to access to scaffold called Lβ with four pyridine-carboxylate ligands. To develop an efficient and reproducible synthesis, HPLC analysis was implemented. Then, using these conditions, carboxylate- and phosphonate-ester, precursors to access α-CD ligands Lα and Lα’, were synthesized. The carboxylate-ester deprotection step successfully afforded the ligand noted Lα contrary to the deprotection of phosphonate ester which still have to be explored. Characterizations of these complicated Gd-ligands systems (Gd-Lα et Gd-Lβ) were reported. Their stability and relaxivity were measured and very good relaxivities were obtained (25 mM-1s-1 < r1 < 40 mM-1s-1). These new structures open the way to an improvement in term of stability.

Abstract available through the Developmental Psychobiology.

No description available.

Master of Science / Department of Chemistry / Kenneth J. Klabunde / Although Degussia-Huls P-25 TiO[subscript]2 semiconductor photocatalyst has high photodegradation rate for organic molecules, it works only under ultra-violet (UV) light. Mesoporous metal doped V-MCM-48 silica was synthesized under ambient conditions for use as a visible-light photocatalyst to convert toxic probe molecules to innocuous products: CO[subscript]2 + H[subscript]2O. The synthesis employed a modified Stober metal doped MCM-48 silica method. Powder X-ray diffraction (XRD), diffuse-reflectance-ultra-violet-visible (DR-UV-vis) spectroscopy, and N[subscript]2 adsorption-desorpton analysis characterization methods were completed on V-MCM-48 mesoporous material. These characterization methods indicate V-MCM-48 structure had formed with visible light absorption and mesoporous properties. Photocatalysis studies were completed with V-MCM-48 under dark, visible, and UV-light illumination conditions for the following probe molecules: acetaldehyde, carbon monoxide, ethanol, acetone, 2-propanol, and acetonitrile. Acetaldehyde over V-MCM-48 was converted to CO[subscript]2 under dark, visible, and UV-light conditions. Carbon monoxide photooxidation occurred over V-MCM-48 under visible and UV-light. Ethanol and acetonitrile had smaller photodegradation activity over V-MCM-48. Acetone and 2-propanol had no activity photocatalytically. Under dark and visible light illumination, V-MCM-48 consumed approximately one-half acetaldehyde and produced one-third CO[subscript]2 concentration as compared with the P-25 TiO[subscript]2 under UV-light. V-MCM-48 produced two-thirds of the amount of CO[subscript]2 in comparison to nanoparticle Au/ZnO catalyst under UV-light. The results infer V-MCM-48 might be useful in gas and liquid phase photocatalysis including water-splitting due to a high oxidation state (V[superscript]5+), visible light absorption, and high surface area. In conclusion, an extended literature review has been completed and literature employed extensively throughout the thesis with potential methods to further the research on V-MCM-48/Si-MCM-48 in catalysis, chromatography, adsorption/gas separation, and solar collection/water-splitting.