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1
Haigh, Nicholas Jonathan. "Multiwaveband studies of be/xray binaries." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250032.
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Bertlin, Simon. "An examination of automated testing and Xray as a test management tool." Thesis, Mittuniversitetet, Institutionen för informationssystem och –teknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-39329.
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Automated testing is a fast-growing requirement for many IT companies. The idea of testing is to create a better product for both the company and the customer. The goal of this study is to examine different aspects of au- tomated testing and Xray as a test management tool. The literature study considers information from several different scientific reports. It shows that the benefits of automated testing include increased productivity and reliable software but also pitfalls like a high initial cost and a maintenance cost. Research suggests that automated testing is complementary to man- ual testing. Manual testing is more suited for exploratory testing, while automated testing is better for regression testing. Using historical data manual tests can be placed into prioritised clusters. The coverage of each test within a cluster determines its priority, where a test with high cover- age has a high priority. A near-optimal solution for prioritising automated tests is the combination of two well-known strategies, the additional cov- erage strategy and the total coverage strategy. Tests are prioritised based on how much of the code they uniquely cover. Code coverage is mea- sured using statements, methods or complexity. Furthermore, this thesis demonstrates a proof of concept for how the unified algorithm can pri- oritise Xray tests. Xray is evaluated according to the ISO/IEC 25010:2011 standard together with a survey done on Xray practitioners. The evalua- tion for Xray shows that Xray provides the necessary tools and functions to manage a testing suite successfully. However, no official encryption exist for the Jira server, and Xray lacks integrated documentation.
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Lhermitte, Julien. "Using coherent small angle xray scattering to measure velocity fields and random motion." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104825.
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The dynamics of cross-linked polymers under stress, such as those thatmake up rubber, are still not well understood. A combination of coherent xrayhomodyne and heterodyne techniques is used in order to measure fluctuations of the system when stretched. The combination of both techniques allows for the measurement of flow patterns, as well as the random nature of the system. After data analysis, the results show that the measurements successfully captured this flow information. The flow velocity was discovered to have a time-dependent nature similar to that of the stress-strain curve. After the flow velocity was extracted, the random nature of the system was analysed. This random motion was discovered not to be dominated by conventional diffusion, but some slower random process.La dynamique de polymères réticulés de stress, telles que celle qui compose le caoutchouc, n'est pas encore bien comprise. Une combinaison de techniques homodynes et hétérodynes de rayons x coherentes est utilisé pour mesurer les fluctuations du système, une fois étiré. La combinaison des deux techniques permet la mesure des régimes d'écoulement, ainsi que le caractère aléatoire du système. Après l'analyse des données, les résultats montrent que les mesures ont réussi à capturer cet information. La vitesse d'écoulement a été découverte de contenir une nature en fonction du temps semblable à celle de la courbe contrainte-déformation. Après la vitesse d'écoulement a été extraite, la nature aléatoire du système a été analysé. Cette motion a été découverte au hasard de ne pas être dominé par la diffusion classique, mais de certains processus aléatoires plus lents.
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Abdalla, Karim Yousif [Verfasser]. "Vergleich von Quantitativer Computertomographie und Dual-Energy XRay Absorptiometry bei postmenopausalen Frauen / Karim Yousif Abdalla." Ulm : Universität Ulm. Medizinische Fakultät, 2014. http://d-nb.info/1053705689/34.
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Baldoni, Riccardo. "Investigation of spectral stability of X-ray tubes by simulations and experimental spectrum measurements." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10574/.
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L'obiettivo di questo lavoro è quello di analizzare la stabilità di uno spettro raggi X emesso da un tubo usurato per analisi cardiovascolari, in modo da verificare il suo comportamento. Successivamente questo tipo di analisi sarà effettuata su tubi CT. Per raggiungere questo scopo è stato assemblato un particolare set-up con un rivelatore al germanio criogenico in modo da avere la miglior risoluzione energetica possibile ed alcuni particolari collimatori così da ridurre il flusso fotonico per evitare effetti di pile-up. Il set-up è stato costruito in modo da avere il miglior allineamento possibile nel modo più veloce possibile, e con l'obiettivo di rendere l'intero sistema portabile. Il tubo usato è un SRM Philips tube per analisi cardiovascolari; questa scelta è stata fatta in modo da ridurre al minimo i fattori esterni (ottica elettromagnetica, emettitori) e concentrare l'attenzione solo sugli effetti, causati dalle varie esposizioni, sull'anodo (roughness e bending) e sul comportamento di essi durante il surriscaldamento e successivo raffreddamento del tubo. I risultati mostrano come durante un'esposizione alcuni fattori di usura del tubo possono influire in maniera sostanziale sullo spettro ottenuto e quindi alterare il risultato. Successivamente, nell'elaborato, mediante il software Philips di ricostruzione e simulazione dello spettro si è cercato di riprodurre, variando alcuni parametri, la differenza riscontrata sperimentalmente in modo da poter simulare l'instabilità e correggere i fattori che la causano. I risultati sono interessanti non solo per questo esperimento ma anche in ottica futura, per lo sviluppo di applicazioni come la spectral CT. Il passo successivo sarà quello di spostare l'attenzione su un CT tube e verificare se l'instabilità riscontrata in questo lavoro è persiste anche in una analisi più complessa come quella CT.
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Amaro, Pedro Manuel Duarte Gonçalves. "Study of forbidden transitions in atomic systems." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6916.
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A Thesis submitted for the co-tutelle degree of Doctor in Physics at Universidade Nova de Lisboa and Université Pierre et Marie CurieOne active topic in Atomic Physics is the study of highly charged ions (HCI). These physical systems have a strong Coulomb field that provides a unique opportunity to investigate and validate relativistic, Quantum ElectroDynamics (QED), and many-body e ects. Moreover, fundamental test on symmetries and parity violation gives clues to the physics beyond the Standard Model. Thus, nowadays, a primary goal of Atomic Physics is the existence of precise experimental data and accurate theoretical calculations for these systems. In this thesis I focus on the investigation of forbidden radiative transitions in HCI. The main emphasis of this work is on atomic transitions, in which the selection rules forbids the emission of electric dipole photons. In this special type of radiative transition, the electron decays mainly through the emission of a single magnetic dipole photon, or two electric dipole photons. Both types of decay are investigated either experimentally or theoretically. The two-photon decay is only theoretically investigated, using a full relativistic formalism,in HCI with one or two electrons. Several physical e ects in the two photon decay, such as resonances, the Dirac’s negative continuum or angular correlations are considered. Related with the decay, two-photon excitation is also investigated. According to these evaluations, I stress the importance of relativistic and nondipolar e ects. Moreover, a new approach based on the B-polynomials basis set is employed on two-photon transitions. The second part of the work is devoted to the precise measurement of transitions in highly charged Ar with two to four electrons. For that matter, I describe the technical features of a double crystal spectrometer used to perform those measurements in HCI for the first time. This kind of spectrometer is able to perform absolute and precise measurements with an accuracy never achieved in these systems, which enables a comparison with recent QED calculations. I describe a Monte-Carlo code developed with the purpose of studying several systematic errors, as well as testing the various methods of retrieving physical quantities from raw data. Finally, I present the first absolute 2 ppm measurements on HCI with this spectrometer, paying special attention on the forbidden magnetic dipole transition in He-like Ar.
Accõess Integradas Luso-Alem˜as (Contract no A-19/09); Fundação de Ciências e Tecnologia (FCT)- contract SFRH/BD/37404/2007 ; Programa Operacional Potencial Humano (POPH/FSE) and European Union social fund
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Al-Kabir, Zul Waker Mohammad, and N/A. "A Knowledge Based System for Diagnosis of Lung Diseases from Chest X-Ray Images." University of Canberra. Information Sciences & Engineering, 2007. http://erl.canberra.edu.au./public/adt-AUC20070823.160921.
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The thesis develops a model (that includes a conceptual framework and an
implementation) for analysing and classifying traditional X-ray images (MACXI)
according to the severity of diseases as a Computer-Aided-Diagnosis tool with three
initial objectives.
� The first objective was to interpret X-ray images by transferring expert knowledge
into a knowledge base (CXKB): to help medical staff to concentrate only on the
interest areas of the images.
� The second objective was to analyse and classify X-ray images according to the
severity of diseases through the knowledge base equipped with an image
processor (CXIP).
� The third objective was to demonstrate the effectiveness and limitations of several
image-processing techniques for analysing traditional chest X-ray images.
A database was formed based on collection of expert diagnosis details for lung images.
Five important features from lung images, as well as diagnosis rules were identified and
simplified. The expert knowledge was transformed into a Knowledge base (KB) for
analysing and classifying traditional X-ray images according to the severity of diseases
(CXKB). Finally, an image processor named CXIP was developed to extract the features
of lung images features and image classification.
CXKB contains 63 distinct lung diseases with detailed descriptions. Some 80-chest X-ray
images with diagnosis details were collected for the database from different sources,
including online medical resources. A total of 61 images were used to determine the
important features; 19 chest X-ray images were not used because of low visibility or the
difficulty of diagnosis. Finally, only 12 images were selected after examining the
diagnosis details, image clarity, image completeness, and image orientation. The most
important features of lung diseases are a pattern of lesions with different levels of
intensity or brightness. The other major anatomical structures of the chest are the hilum
area, the rib area, the trachea area, and the heart area.
Seven different severity levels of diseases were determined. Development and
simplification of rules based on the image library were analysed, developed, and tested
against the 12 images. A level of severity was labelled for each image based on a
personal understanding of all the image and diagnosis details. Then, MACXI processed
the selected 12 images to determine the level of severity. These 12 images were fed into
the CXIP for recognition of the features and classification of the images to an accurate
level of severity. Currently, the processor has the ability to identify diseased lung areas
with approximately 80% success rate.
A step by step demonstration of several image processing techniques that were used to
build the processor is given to highlight the effectiveness and limitations of the
techniques for analysing traditional chest X-ray images is also presented.
8
Maria, de Carvalho Albuquerque Melo Ana. "Estudo comparativo da antropometria e do DXA: uma nova equação de predição para avaliação da gordura centralizada em homens adultos jovens." Universidade Federal de Pernambuco, 2006. https://repositorio.ufpe.br/handle/123456789/8835.
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Previous issue date: 2006A obesidade é uma excessiva acumulação de energia sob a forma de gordura corporal com prejuízos à saúde. O aumento da prevalência de obesidade em diferentes populações leva a acreditar que esta condição clínica caminha para ser a mais importante causa de doença crônica no mundo. O objetivo deste trabalho foi o de avaliar a importância da obesidade em especial a central e seus fatores de risco à saúde em homens adultos jovens por meio de revisão da literatura, bem como, realizar um estudo comparativo entre duas técnicas de avalição da composição corporal: a Antropometria e o Dual Energy X-ray absorptiometry (DXA). O delineamento do estudo foi do tipo transversal com seleção aleatória. Participaram 45 indivíduos com idades entre 20 e 30 anos, distribuídos em três grupos segundo o Índice de Massa Corporal (IMC), nas categorias peso normal, pré-obeso e obeso I. O referido estudo originou uma nova equação de predição para a gordura centralizada utilizando o perímetro abdominal (Pab) e a gordura do tronco medida pelo DXA em homens adultos jovens, permitindo ainda classificar os referidos indivíduos em risco à saúde de acordo com o Z-score usando a quantidade de gordura estimada pela referida equação
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Lodwick, Camille J. "Mathemeatical simulations of photon interactions using Monte Carlo analysis to evaluate the uncertainty associated with in vivo K xray fluorescence measurements of stabe lead in bone." Cincinnati, Ohio : University of Cincinnati, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1059400723.
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Pratsch, Christoph. "New methods for high resolution 3D imaging with X-rays." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19238.
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In der Arbeit haben wir die Grenzen der weit verbreiteten tomographischen
Rekonstruktion von 3D-Proben mittels Transmissionsröntgenmikroskopie charakterisiert.
Wir zeigen, dass die 3D-Auflösung mit diesem Ansatz durch die Schärfentiefe
begrenzt ist. Zur Untersuchung von Alternativen führten wir Simulationen
zur Bildentstehung in einem konfokalen Röntgenmikroskop und einem FIB-SXM
durch. Wir zeigen, dass FIB-SXM ein vielversprechender Ansatz ist, der eine isotrope
3D-Aulösung um die 10 nm erreichen kann und zusätzlich ein drastisch
verbessertes Signal-Rausch-Verhältnis bieten könnte. Wir stellen auch eine neue
Holographiemethode vor, die sich für Vollfeldabbildungen mit kurzen kohärenten
Röntgenpulsen als vorteilhaft erweisen und neue Einsichten in die ultraschnelle
Physik liefern könnte.We have characterized the limitations of the most powerful and widely used 3D X-ray imaging approach, transmission X-ray microscopy with tomographic reconstruction. We show that 3D resolution in this approach is limited by the depth of field. To investigate alternatives, we perform simulations of a confocal transmission X-ray microscope and a FIB-SXM. We show that FIB-SXM is a very promising approach that could o er 3D isotropic resolution at 10 nm with dramatically improved signal to noise. We also introduce a new holography method that could prove bene cial for full eld imaging with short coherent X-ray pulses and yield new insights into ultrafast physics.
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Santos, Felipe André dos [UNESP]. "Determinação de manganês e zinco em spots protéicos de plasma de tilápia do Nilo (Oreochromis niloticus) por SR-XRF e GFAAS após separação por 2D-PACE." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/95264.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Universidade Estadual Paulista (UNESP)
O presente trabalho teve como objetivo investigar a presença de manganês e zinco em “spots” protéicos de amostras de plasma de tilápia do Nilo (Oreochromis niloticus) obtidos após separação das proteínas por eletroforese em gel de poliacrilamida em segunda dimensão (2D-PAGE) para posterior avaliação qualitativa e quantitativa utilizando fluorescência de raios-X com radiação síncrotron (SR-XRF) e espectrometria de absorção atômica em chama e em forno de grafite (FAAS/GFAAS). As análises dos espectros de fluorescência indicaram a presença de manganês e zinco em quatro e seis “spots” protéicos de plasma, respectivamente. Observou-se que os íons metálicos estão ligados em proteínas com massa molar na faixa de 19 a 70 kDa e com pI na faixa de 4,7 a 6,30. A concentração de manganês e zinco ligados a essas proteínas foi determinada por GFAAS após a mineralização ácida dos spots protéicos, encontrandose concentrações na faixa de 3,40 a 4,20 mg g-1 e 2,30 a 13,90 mg g-1, respectivamente
The aim of the present study was to investigate the presence of manganese and zinc in protein spots in samples of Nile tilapia (Oreochromis niloticus) plasma obtained after protein separation by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and subsequent qualitative and quantitative determination by synchrotron radiation X-ray fluorescence (SRXRF) and graphite furnace atomic absorption spectrometry (GFAAS). An analysis of the fluorescence spectra indicated the presence of manganese and zinc in four and six plasma protein spots, respectively. It was observed that the metal ions are bound in proteins with molecular weight ranging from 19 to 70 kDa and pI ranging from 4.7 to 6.30. The manganese and zinc concentrations bound to these proteins were determined by GFAAS after acid digestion of protein spots, finding concentrations ranging from 3.40 to 4.20 mg g-1 and 2.30 to 13.90 mg g - 1, respectively
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Ianni, Andrea. "Applicazioni di realtà aumentata in ambito museale." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9679/.
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La realtà aumentata, unitamente a quella mista, stanno rapidamente prendendo pieno all'interno di molti aspetti della vita umana. Scopo di questo lavoro è di analizzare tecnologie e tecniche esistenti al fine di applicarle ad un caso reale, la rilevazione e la sovrapposizione di un oggetto digitale tridimensionale ad uno presente in un museo.
13
Dridi, Zrelli Yosra. "Électrochimie et spectroscopie Raman de matériaux d’électrode positive pour batteries Li-ion." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1126/document.
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Dans ce travail de thèse, la microspectrométrie Raman a été mise à profit pour décrire les changements structuraux induits par la réaction électrochimique d'insertion/désinsertion des ions lithium dans des composés de structure lamellaire LiCoO2 et cubique LiMn2O4 et LiNi0.4Mn1.6O4, utilisés comme électrodes positives dans les batteries Li-ion. L'étude du composé d'électrode LiCoO2 pendant le processus de charge permet de mettre en évidence une région biphasée où la phase initiale coexiste avec une nouvelle phase hexagonale caractérisée par une expansion du paramètre inter-feuillets de l'ordre de 3% et un affaiblissement de la liaison Co-O dans le plan des feuillets. Dans le cas de LiMn2O4, une nouvelle attribution du spectre Raman a pu être proposée. Pendant la charge à 4V, un mécanisme à trois phases (phase initiale LiMn2O4, phase intermédiaire, phase pauvre en lithium) est décrit par spectroscopie Raman alors que la diffraction des RX ne permet pas d'observer la phase intermédiaire dans nos conditions de mesure. L'étude de l'insertion électrochimique du lithium dans LiMn2O4 (région 3V), a permis de montrer pour la première fois par spectroscopie Raman la formation progressive d'une phase tétragonale de composition Li2Mn2O4 qui coexiste avec la phase cubique initiale et qui est pure en fin de décharge. La réversibilité de cette transition structurale a également été démontrée. Dans le cas du composé substitué au nickel, LiNi0.4Mn1.6O4, une attribution complète du spectre Raman est proposée pour la première fois. L'étude par diffraction des RX du matériau en fonction de l'état de charge et de décharge met en évidence une conservation de la structure cubique avec des variations modérées de paramètres de maille. Le spectre Raman présente quant à lui des variations très significatives qui rendent compte de la présence dans des proportions différentes des espèces redox impliquées dans le fonctionnement électrochimique (Mn4+, Mn3+, Ni2+, Ni3+, Ni4+). Une analyse spectrale par décompositions de bandes permet d'identifier et de quantifier les proportions relatives des différents couples redox du nickel. Une réversibilité complète de la signature Raman est observée en décharge. Une application concrète et originale de la spectroscopie Raman a consisté à étudier le mécanisme d'autodécharge qui est observé pour le matériau LiNi0.4Mn1.6O4 complètement chargé. L'évolution des spectres Raman permet de mettre en évidence une réduction rapide et quantitative des ions Ni4+ pendant les premières heures de séjour dans l'électrolyte, puis un processus plus lent de réduction des ions Ni3+. Enfin, pour la première fois également, l'insertion du lithium dans le composé LiNi0.4Mn1.6O4 a été explorée par microspectrométrie Raman et a permis notamment d'identifier l'empreinte Raman de la phase la plus réduite de symétrie tétragonale Li2Ni0.4Mn1.6O4. L'originalité de ce travail a été d'apporter un grand nombre de données Raman expérimentales sur des matériaux d'électrode performants fonctionnant à 4V. De nouvelles attributions ont pu être proposées pour les composés initiaux, et des données vibrationnelles inédites ont été fournies sur les composés formés en charge et en décharge. Dans certains cas, ces données ont permis, sur la base d'une analyse détaillée des spectres Raman par décompositions de bandes, de proposer un raisonnement quantitatif sur l'existence de phases ou d'espèces redox en mélange. Il conviendrait bien sûr de corroborer ces nouvelles données et attributions par des calculs théoriques ab initio capables de simuler les fréquences et les intensités des modes vibrationnels dans les structures hôtes et lithiéesIn this work, we show the relevance of Raman spectroscopy as a useful technique to investigate the local changes induced by the electrochemical reaction of intercalation/deintercalation of lithium in positive electrode materials for rechargeable lithium ion batteries.Raman investigations concern three types of high voltage cathode materials (4-5Volts) which are layered LiCoO2 and cubic LiMn2O4 and LiNi0.4Mn1.6O4.During electrochemical deintercalation of LiCoO2, we show the existence of a two phase region where the initial hexagonal phase coexist with a second hexagonal phase with a 3% expansion of the lattice parameter indicating a weakening of the Co-O bond in the Li1-xCoO2 material.On the other hand, a new assignment of LiMn2O4 Raman spectrum was proposed. During the charge in the 4V region, a three region phase (initial LiMn2O4 phase, intermediary phase and poor lithium phase) was described using Raman spectroscopy. RX measurements can not detect this intermediary phase. Lithiated phase Raman signature shows a specific local order: Fd3m for extreme phases and F43m for partially lithiated phase. A rich Raman band spectrum is attributed to this later phase in coherence with literature calculations. Structural changes reversibility is demonstrated. Identification of this intermediary phase as a major component of a cycled electrode, underline the incomplete reduction and explain the important loss of capacity observed during cycling. Raman study of LiMn2O4 electrochemical insertion in the 3V region, has demonstrated for the first time a progressive formation of tetragonal Li2Mn2O4 phase, which is in coexistence with initial cubic phase and is pure at the end of discharge. Structural transition reversibility was also demonstrated.In the case of LiNi0.4Mn1.6O4, the assignment of the Raman spectrum of LiNi0.4Mn1.6O4 is provided for the first time. DRX study in function of the state of charge and discharge, exhibit cubic structure conservation with moderate lattice parameters variations. The Raman spectrum of the spinel oxide exhibits drastic spectral changes during Li extraction. These changes have been directly related to the Mn and Ni oxidation states in the cathode material under operation. It comes out that electrochemical reactions of LiNi0.4Mn1.6O4 are reversible and based on three redox couples of Mn3+/Mn4+, Ni2+/Ni3+, and Ni3+/Ni4+. An original and concrete Raman spectroscopy application is the study of self discharge mechanism of completely charged LiNi0.4Mn1.6O4. Raman spectra evolution exhibits a quantitative Ni4+ reduction during the first hours, and then a slower Ni3+ reduction process. Finally, LiNi0.4Mn1.6O4 lithium insertion has been explored for the first time using Raman spectroscopy, and a tetragonal Li2Ni0.4Mn1.6O4 phase has been identified.The originality of this work is the important number of experimental Raman data of 4V electrode materials. New assignment of initial compound has been proposed and original vibrationnal data of compound during charge/discharge has been presented. These Raman data has permitted to propose a quantitative explanation which must be completed with ab initio calculations to simulate vibrationnal modes frequencies/ intensities
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Santos, Felipe André dos. "Determinação de manganês e zinco em spots protéicos de plasma de tilápia do Nilo (Oreochromis niloticus) por SR-XRF e GFAAS após separação por 2D-PACE /." Botucatu : [s.n.], 2010. http://hdl.handle.net/11449/95264.
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Orientador: Pedro de Magalhães PadilhaBanca: Gustavo Rocha de Castro
Banca: Eduardo José de Arruda
Resumo: O presente trabalho teve como objetivo investigar a presença de manganês e zinco em "spots" protéicos de amostras de plasma de tilápia do Nilo (Oreochromis niloticus) obtidos após separação das proteínas por eletroforese em gel de poliacrilamida em segunda dimensão (2D-PAGE) para posterior avaliação qualitativa e quantitativa utilizando fluorescência de raios-X com radiação síncrotron (SR-XRF) e espectrometria de absorção atômica em chama e em forno de grafite (FAAS/GFAAS). As análises dos espectros de fluorescência indicaram a presença de manganês e zinco em quatro e seis "spots" protéicos de plasma, respectivamente. Observou-se que os íons metálicos estão ligados em proteínas com massa molar na faixa de 19 a 70 kDa e com pI na faixa de 4,7 a 6,30. A concentração de manganês e zinco ligados a essas proteínas foi determinada por GFAAS após a mineralização ácida dos spots protéicos, encontrandose concentrações na faixa de 3,40 a 4,20 mg g-1 e 2,30 a 13,90 mg g-1, respectivamente
Abstract: The aim of the present study was to investigate the presence of manganese and zinc in protein spots in samples of Nile tilapia (Oreochromis niloticus) plasma obtained after protein separation by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and subsequent qualitative and quantitative determination by synchrotron radiation X-ray fluorescence (SRXRF) and graphite furnace atomic absorption spectrometry (GFAAS). An analysis of the fluorescence spectra indicated the presence of manganese and zinc in four and six plasma protein spots, respectively. It was observed that the metal ions are bound in proteins with molecular weight ranging from 19 to 70 kDa and pI ranging from 4.7 to 6.30. The manganese and zinc concentrations bound to these proteins were determined by GFAAS after acid digestion of protein spots, finding concentrations ranging from 3.40 to 4.20 mg g-1 and 2.30 to 13.90 mg g - 1, respectively
Mestre
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Quandalle, Grégoire. "Étude et modélisation mécanique de la cristallisation induite par la déformation des polymères : caoutchouc naturel réticulé et PET." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM033/document.
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L’objectif de cette thèse est de contribuer à la compréhension et à la modélisation de la cristallisation induite. Le phénomène est caractérisé pour deux matériaux : le PET et le caoutchouc naturel réticulé. Les conditions favorables au phénomène, de type caoutchoutique sont déterminées par analyses calorimétriques et spectroscopiques. La microstructure qui se développe au cours de la déformation est observée par diffraction des rayons X.Le PET est déformé en traction uni- et biaxiale. Une partie des étirages est suivie d’une relaxation des contraintes, une autre est suivie d’une trempe rapide. Il ressort de l’étude que l’étirage du PET dans ces conditions n’aboutit pas à l’obtention d’un cristal PET avec toutes les périodicités qui lui sont propres.Le caoutchouc naturel est déformé en traction uniaxiale et en cisaillement précédé d’un étirage uniaxial. En cisaillement, la phase cristalline obtenue au cours du pré-étirage ou du cisaillement tourne et tend à s’orienter comme les directions des déformations principales mais avec un retard angulaire. L’extension principale est utilisée pour étudier la phase cristalline obtenue pour les différents modes de sollicitation.Un modèle de comportement visco-hyperélastique, décrit dans le cadre de la thermodynamique des processus irréversibles, est étendu afin de reproduire le durcissement mécanique lié au développement d’une phase organisée/cristalline. Le modèle permet de reproduire les différents comportements mécaniques observés expérimentalementThe present PhD thesis aims at a better understanding and modeling of strain-induced-crystallization. The phenomenon is characterized for two polymers: PET and crosslinked natural rubber. Strain conditions leading to strain-induced-crystallization are determined by thermal and dynamic mechanical analysis. The developing microstructure is observed by X-ray scattering.The PET is stretched in uni- and biaxial tension. A part of samples is rapidly quenched after stretching and another is submitted to a stress relaxation after stretching. The studies demonstrate that the stretching of PET does not enable the formation of a complete PET crystal with all its own families of planes.The crosslinked natural rubber is stretched in uniaxial tension and in shear preceded by uniaxial stretching. In shear, the crystalline phase, appeared during the pre-stretching or during the shear rotates and has a tendency to orient as the directions of the principal strains. The principal elongation is used to compare the crystallization under the different stresses.A constitutive modeling for visco-hyperelastic behaviors, in a complete thermodynamics framework of irreversible processes, is extended in order to reproduce le mechanical hardening related to the development of an organized/crystalline phase. The modeling successes in reproducing the experimental behaviors in uploading/unloading for various strain conditions
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Rocha, Christiana Maia Nobre. "Traumatismo cranioencefálico: correlação entre dados demográficos, escala de Glasgow e tomografia computadorizada de crânio com a mortalidade em curto prazo na cidade de Maceió, Alagoas." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-21062007-145931/.
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O traumatismo cranioencefálico (TCE) constitui um dos principais problemas de saúde pública mundial e as suas características variam de acordo com a população envolvida, sendo de suma importância o conhecimento de dados demográficos da mesma para que sejam adotadas medidas de prevenção efetivas. Tivemos como objetivos a descrição de dados demográficos e tomográficos em pacientes vítimas de TCE e a correlação entre idade, sexo, escala de Glasgow e dados tomográficos com a mortalidade em curto prazo. Neste estudo transversal e prospectivo realizado em pacientes vítimas de TCE admitidos na Unidade de Emergência Dr. Armando Lages, Maceió, Alagoas, foram incluídos 623 pacientes para descrição dos dados demográficos e 451 pacientes, para a análise de correlação; realizada por meio da Análise de Correlação de Spearman e de análise multivariada através de regressão logística. Foi constatada uma razão masculino/feminino geral de 3,54: 1 e a faixa etária mais acometida foi a de 21 a 30 anos. Os principais mecanismos do trauma foram os acidentes relacionados com meio de transporte motorizado (35,15%), as quedas (32,59%) e as agressões com ou sem armas (22,79%). As alterações mais comuns no TCE leve foram o hematoma subgaleal e/ou palpebral (48,5%), as fraturas (28,3%) e as contusões cerebrais (12,2%). No TCE moderado, as alterações mais freqüentes foram o hematoma subgaleal/palpebral (68,9%), fraturas (43,2%), contusão cerebral (33,7%) e hemorragia subaracnóide (HSA) (28,4%). No TCE grave, as anormalidades mais comuns foram a a HSA (71,1%), o hematoma subgaleal e/ou palpebral (68,9%), as fraturas (64,4%), contusões cerebrais (53,3%) e edema difuso (53,3%). As variáveis relacionadas com a mortalidade, por meio da análise univariada, foram a pontuação 3 na escala de Glasgow, presença de anormalidades tomográficas, de hematoma subdural (HSD), de HSA, apagamento/assimetria de cisternas basais, desvio da linha média, edema difuso, hemorragia intraventricular (HIV), presença de projétil ou estilhaços de arma de fogo. As variáveis sexo, faixa etária e hematoma extradural não apresentaram correlação estatisticamente significante com mortalidade neste estudo. As variáveis preditoras de mortalidade, na análise multivariada, foram valores baixos na escala de Glasgow, presença de anormalidades tomográficas, desvio da linha média e edema difuso. Em conclusão, os pacientes vítimas de TCE apresentaram uma predominância do masculino, numa razão M/F média de 3,54: 1,da faixa etária entre 21 a 30 anos e as causas mais freqüentes de TCE foram a queda de altura, o atropelamento e a agressão física. As características tomográficas mais freqüentes nos grupos de TCE leve e moderado foram: o hematoma subgaleal e/ou palpebral, fratura óssea e contusão cerebral. No TCE grave as lesões mais freqüentes foram a HSA, o hematoma subgaleal e/ou palpebral, fratura óssea, contusão cerebral e edema difuso. Os fatores relacionados com maior mortalidade na análise univariada foram: baixa pontuação na escala de Glasgow, pontuação 3 na escala de Glasgow, presença de anormalidades tomográficas, presença de HSA, presença de HSD, apagamento/assimetria de cisternas basais, desvio linha média, edema difuso, HIV e presença de projétil ou estilhaços de arma de fogo. Na análise multivariada: baixa pontuação na escala de Glasgow, presença de anormalidades tomográficas, presença de desvio da linha média, presença de edema difuso.The traumatic brain injury (THI) is a major public health concern worldwide. Preventive measures to tackle the problem can be taken after analyzing demographic data and the types of injury affecting the population at hand. Our aim was to outline the demographic and tomographic data from THI victims and determine how tomography findings, age, gender, and Glasgow Coma Scale (GCS) are associated to short-term mortality. The THI patients in this cross-sectional and prospective study had been admitted to the Armando Lages Emergency Care Unit in Maceió, Alagoas. The study comprised 623 patients, who had been clinically diagnosed with THI. A total of 451 patients were included in the investigation into the correlation of computer tomography, age, gender, GCS, and mortality. Both the Spearman Correlation Analysis, and logistic regression multivariate analysis were used. The overall male:female ratio was 3.54, with 78.01% of the victims male and 21.99% female. Most patients fell within the 21 to 30 age bracket. Traffic accidents (35.15%) were the leading cause of head injury, followed by falls (32.59%), and physical assault (22.79%). Tomographic abnormalities were seen in 63.7% of victims of mild THI, the most common being subgaleal and eyelid hematoma (48.5%), skull fractures (28.3%), and cerebral contusion (12.2%). Moderate THI produced tomographic abnormalities in 83.4% of victims, the most frequent being subgaleal and eyelid hematoma (68.9%), fractures (43.2%), cerebral contusion (33.7%), and subarachnoid hemorrhage (SAH) (28.4%). Computer tomography of the skull showed alterations for all victims of severe THI, the most often being subgaleal and eyelid hematoma (68.9%), followed by SAH (71.1%), skull fractures (64.4%), cerebral contusion (53.3%), diffuse brain swelling (53.3%). Univariate analysis attested that a score 3 on the GCS, the presence of tomographic abnormalities, subdural hematoma (SDH), SAH, absent or compressed basal cisterns, midline shift, diffuse brain swelling, intraventricular hemorrhage (IVH), and the presence of a projectile or shell splinters had an statistically significant correlation with short-term mortality. In this study, gender, age group, and large extradural hematoma had no statistical significance as predictive factors for mortality. In a multivariate analysis, the variables that accounted for mortality were low GCS scores, the presence of tomographic abnormalities, midline shift, and diffuse brain swelling. It can be concluded that males were the predominant victims in THI cases, with the M:F ratio at 3.54. Most affected were individuals aged 21 to 30, and the most common causes of THI were falls, being run over by a vehicle, and physical assault. The most frequent tomographic characteristics in the mild and moderate THI cases were subgaleal and/or eyelid hematoma, skull fracture and cerebral contusion. The most common injuries in severe THI patients were subgaleal and/or eyelid hematoma, SAH, skull fracture, cerebral contusion, and diffuse brain swelling. The factors most closely linked to higher mortality after univariate analysis were low GCS scoring, a score 3 on the GCS, the presence of tomographic abnormalities, the presence of SAH, the presence of SDH, absent or compressed basal cisterns, midline shift, diffuse brain swelling, IVH, and the presence of a projectile or shell splinters. After multivariate analysis: low scoring on the GCS and the presence of tomographic abnormalities, midline shift, and diffuse brain swelling.
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Alzahrani, Nada. "An X-ray crystallographic study of SO3 containing compounds." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/an-xray-crystallographic-study-of-so3-containing-compounds(694ba749-91a1-44d6-86df-c0cd75ffbdd7).html.
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The introductory chapter covers a review of intermolecular interactions with examples of host-guest systems, including sulfonates. As X-ray crystallography is the main characterisation tool used in this thesis its theory and practice are described in Chapter 2. Chapter 3 presents a study of the geometry of RnSO3 molecules carried out using the Cambridge Crystallographic Database and associated software. An X-ray powder diffraction study of the crystallisation products obtained from aqueous solution containing guanidinium and sulfite ions is described in Chapter 4. The crystal structure of a novel sodium sulfate/chloride is also reported in this chapter. Chapter 5 presents the crystal structure of a novel sodium calcium chloride sulfate and a redetermination of sodium sulfite, both of which crystallised from deoxygenated aqueous solutions. Chapter 6 describes attempts at crystallising transition metal complexes with SO32-containing ligands which also participate in hydrogen bonding. Also, two novel crystal structures are reported in this chapter. Conclusions and suggestions for further work are presented in the final chapter and the structure of three copper (0) dipyridyl methanol complexes, two of them novel, are reported in Appendix 1.
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Panayiotou, Maria. "Motion gating for X-ray guided interventional electrophysiology procedures." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/motion-gating-for-xray-guided-interventional-electrophysiology-procedures(70729d75-40ba-4886-b333-f5b1c5bf3556).html.
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Atrial fibrillation (AF) is a common supraventricular arrhythmia, characterized by irregular and uncoordinated contraction of the atrium. Although AF itself is not lethal, it accounts for secondary diseases and morbidity and mortality. The minimally-invasive radiofrequency ablation (RFA) procedure is a commonly performed treatment option for AF, guided by Xray fluoroscopy. While it provides high temporal and spatial resolution, X-ray fluoroscopy has poor soft-tissue contrast. In order to enhance image guidance, volumetric roadmaps overlaid on live X-ray fluoroscopy may be used. However, these roadmaps are often static and do not reflect cardiorespiratorymotion. Real-time roadmap update is important to compensate for this motion and maintain the accuracy of the guidance information, thereby allowing accurate determination of catheter-based ablation treatment sites. Motion gating is crucial for achieving this accuracy. Four novel and clinically applicable robust-to-noise motion gating techniques are developed and presented in this thesis. The first proposed technique, Tracked-principal component analysis (PCA), is based on the formation of a novel statistical model of the motion of a coronary sinus (CS) catheter using PCA of tracked electrode locations from monoplane X-ray fluoroscopy images. Motion gating was later further extended to be applicable to more types of minimally invasive procedures, such as Cardiac resynchronisation therapy, where the CS catheter is not present in the X-ray images. This is achieved by the development of two robust to varying image-content techniques, the hierarchical manifold learning based and the Masked-PCA techniques. To avoid the limitation of the requirement to build a separate model for each X-ray view, an X-ray system View-angle independent technique was developed based on learning CS catheter motion using PCA and then applying the derived motion model to unseen images taken at arbitrary projections. Applications of the motion gating techniques spanning from basic research to clinical tasks are demonstrated. These include catheter reconstruction in 3D from catheter tracking in gated sequential biplane X-ray images that can effectively achieve 2D/3D registration of 3D cardiac data (CT or MRI) to X-ray fluoroscopy; motion gating of 3D rotational X-ray angiography sequences where the angulation of the scanner is changed between frames; and motion compensation on unseen images taken at any arbitrary projection, by integrating cardiorespiratory motion into MRI-derived roadmaps fused with live X-ray fluoroscopy. This thesis is devoted to the development of robust-to-noise motion gating techniques and their use for improved procedure guidance while at the same time minimising patient and staff exposure to radiation, by allowing the use of lower-dose fluoroscopy. Results indicate that, within the constraints of acceptable accuracy, the achievable dose reduction factor is 1/25 for the HML-based and Masked-PCA techniques, indicating a dose reduction of more than 25 times, between 1/10 and 1/25 for the Tracked-PCA technique and around 1/10 for the View-angle independent technique.
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Jansson, Anna M. "Targeting Infectious Disease : Structural and functional studies of proteins from two RNA viruses and Mycobacterium tuberculosis." Doctoral thesis, Uppsala universitet, Struktur- och molekylärbiologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196623.
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The recent emergence of a number of new viral diseases as well as the re-emergence of tuberculosis (TB), indicate an urgent need for new drugs against viral and bacterial infections. Coronavirus nsp1 has been shown to induce suppression of host gene expression and interfere with host immune response. However, the mechanism behind this is currently unknown. Here we present the first nsp1 structure from an alphacoronavirus, Transmissible gastroenteritis virus (TGEV) nsp1. Contrary to previous speculation, the TGEV nsp1 structure clearly shows that alpha- and betacoronavirus nsp1s have a common evolutionary origin. However, differences in conservation, shape and surface electrostatics indicate that the mechanism for nsp1-induced suppression of host mRNA translation is likely to be different in the alpha- and betacoronavirus genera. The Modoc virus is a neuroinvasive rodent virus with similar pathology as flavivirus encephalitis in humans. The flaviviral methyltransferase catalyses the two methylations required to complete 5´ mRNA capping, essential for mRNA stability and translation. The structure of the Modoc NS5 methyltransferase domain was determined in complex with its cofactor S-adenosyl-L-methionine. The observed methyltransferase conservation between Modoc and other flaviviral branches, indicates that it may be possible to identify drugs that target a range of flaviviruses and supports the use of Modoc virus as a model for general flaviviral studies. 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) is part of the methylerythritol phosphate (MEP) pathway that produces essential precursors for isoprenoid biosynthesis. This pathway is used by a number of pathogens, including Mycobacterium tuberculosis and Plasmodium falciparum, but it is not present in humans. Using a structure-based approach, we designed a number of MtDXR inhibitors, including a novel fosmidomycin-analogue that exhibited improved activity against P.falciparum in an in vitro blood cell growth assay. The approach also allowed the first design of an inhibitor that bridge both DXR substrate and co-factor binding sites, providing a stepping-stone for further optimization.
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Molefe, B. H. "Impact of preoperative chest X-rays on the surgery of patients at Dr George Mukhari Hospital." Thesis, University of Limpopo ( Medunsa Campus), 2010. http://hdl.handle.net/10386/410.
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Thesis(M. Med (Anaesthesiology)--University of Limpopo(Medunsa Campus), 2010.The purpose of this study was to interrogate the clinical relevance and cost effectiveness of the routine preoperative chest X-rays at DGMH. It was conducted as a descriptive cross-sectional prospective study of radiographic films in the Radiology department. A review of patients’ files and chest X-rays performed during a 6-month period from January to June 2008. Data from 100 patients’ files were included in the analysis. The age of patients ranged from 45 to 84years, the median age was 57years. The majority of patients younger than 50years were female, while the majority of male patients were over 50years. From a total of 100 patients only 8%(8 patients) were deemed unfit and consequently postponed or cancelled for further investigation and optimization. The cost for performing one routine chest X-ray was estimated to be R393 manpower, time and film inclusive, the total costs for the 100 patients included in this study being R39300. This study has provided some evidence that the routine preoperative chest X-rays can help in uncovering some abnormalities that were not apparent on clinical examination, it has pointed out that the impact of these uncovered abnormalities is very minimal on the planned surgery and that the costs associated with doing routine pre-operative chest X-rays can be substantial.
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Haji, Oussama. "Modèles de comportement de structures textiles : développement, identification, implémentation." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE3007.
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Les renforts fibreux subissent des mécanismes de déformations complexes lors du procédé de fabrication des pièces composites. Par conséquent, des défauts se produisent à différentes échelles du renfort qui peuvent affecter drastiquement la qualité de la pièce finale. Afin d’améliorer celle-ci, il serait judicieux de prévoir la faisabilité des pièces composite par la modélisation et la simulation du procédé de mise en forme. Cette tâche nécessite d’établir, tout d’abord, une loi de comportement du renfort fibreux par le biais de la modélisation du comportement des mèches, qui dépend lui-même du comportement des fibres et des interactions entre elles. D’où l’intérêt de commencer par l’étude d’un milieu fibreux modèle à l’échelle de la fibre. La présente étude s’inscrit dans cette approche en ayant comme objectif de développer un milieu modèle basé sur une géométrie réaliste d’un réseau de fibres faiblement enchevêtrées et quasiment unidirectionnelles. À l’issue de ce travail, deux éléments clés sont présentés : (i) des outils automatisés de reconstruction de la microstructure des milieux fibreux à partir des images de la tomographie à rayons X, jusqu’à son modèle CAO. (ii) une stratégie de simulation fiable,nourrie par des essais expérimentaux de compaction effectués sur un milieu fibreux modèle de 40 fibres de polyester. En utilisant ces outils, des simulations de compaction confinée, sur la même microstructure que celle de l’échantillon réel, ont été effectuées sur Abaqus®. Les fibres ont été modélisées par des éléments poutres 3D en prenant en compte le frottement entre elles. Un modèle numérique de contact, basé sur la loi de Hertz, est utilisé également. La confrontation des résultats numériques avec ceux des expériences montre une cohérence très encourageante qui permet de valider le modèle numérique d’une part, et de tester d’autres trajets de chargement en augmentant le nombre de fibres d’autre partThe fibrous textile undergoes different mechanical loads, which induce strains and damage to the fabric at different scales. As a result, the mechanical properties of the final parts are drastically impacted. It is therefore essential topredict the feasibility of composite parts by the modelization and the simulation of the fabric preforming process.This task requires an appropriate mechanical behaviour of the fibrous textile. This behaviour is mainly a structural effect that depends essentially on the yarn interlacing and secondly on the yarn behaviour. Each yarn is composedof thousands of fibers; therefore, the objective of the present thesis is to establish a reliable numerical model ofslightly entangled and quasi-parallel fibers. The present work presents mainly: (i) a realistic representation of the fiber network geometry and (ii) a reliable simulation strategy to model the main phenomena at the fiber scale. To feed this approach, compaction tests were conducted on fiber network specimens of 40 polyester fibres. The experiments were combined with X-ray tomography image analysis. Using these tools, simulations of confined compaction on the same microstructure of the used specimen were performed on Abaqus®/Explicit. Beam finite elements were chosen to model the fibers and optimise the calculation cost. The normal contact behaviour between the fibers were was accurately modelled using the contact stiffness scaling and referring to Hertz contact model. The simulation strategy has been validated by comparing the mechanical response of the compaction experiment with the numerical one. The proposed model offers encouraging results in accordance with the real compaction test. More loading trajectories will be performed on a bundle of hundreds of fibers to gather more information on the microscopic scale (fiber scale), and then formulate a mechanical behaviour at the mesoscopic scale (yarn scale)
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Szotten, David. "Limited data problems in X-ray and polarized light tomography." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/limited-data-problems-in-xray-and-polarized-light-tomography(5bc153b4-7344-4a62-9879-e23cc3d60b2d).html.
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We present new reconstruction results and methods for limited data problems in photoelastic tomography. We begin with a survey of the current state of x-ray tomography. Discussing the Radon transform and its inversion we also consider some stability results for reconstruction in Sobolev spaces. We describe certain limited data problems and ways to tackle these, in particular the Two Step Hilbert reconstruction method. We then move on to photoelastic tomography, where we make use of techniques from scalar tomography to develop new methods for photoelastic tomographic reconstruction. We present the main mathematical model used in photoelasticity, the Truncated Transverse Ray Transform (TTRT). After some initial numerical studies, we extend a recently presented reconstruction algorithm for the TTRT from the Schwartz class to certain Sobolev spaces. We also give some stability results for inversion in these spaces. Moving on from general reconstruction to focus on inversion of some special cases of tensors we consider solenoidal and potential tensor fields. We discuss existing reconstruction methods and present several novel reconstructions and discuss their advantages over using more general machinery. We also extend our new algorithms, as well as existing ones, to certain cases of data truncation. Finally, we present numerical studies of the general reconstruction method. We give the first published results of TTRT reconstruction and go into some detail describing the implementation before presenting our results.
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Malm, Alexander. "OCT velocimetry and X-ray scattering rheology of complex fluids." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/oct-velocimetry-and-xray-scattering-rheology-of-complex-fluids(6877cbc7-5919-4b36-8279-ea73604cb977).html.
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Optical Coherence Tomography Velocimetry (OCTV) is a technique based on principals developed for medical imaging and is used to measure the velocity as a function of sample depth for a range of complex fluid systems, revealing insight into rheological properties that are otherwise ignored by bulk rheometry methods. The technique fulfils the requirements needed to study a wide range of complex systems, being capable of measuring absolute velocity and velocity fluctuations with high spatial and temporal resolution, as well as in opaque materials. Improvements to the instrumentation behind OCTV are described in detail, with improvements to signal to noise being achieved through better detection and the use of modulation techniques. The technique is also demonstrated in a range of complex fluids including dense suspensions of hard spheres, DNA solutions, polyacrylamide solutions, bacteria and shampoo amongst others. Non-linear flow behaviour is revealed that includes shear banding, wall slip and elastic turbulence. X-ray scattering techniques are also discussed, with results from recent experiments at the Diamond synchrotron being presented. The commercial potential of OCTV is discussed in depth, with analysis of the market of scientific instruments for measuring flow, competitor analysis and a review of relevant intellectual property. Methods to commercialise OCTV are discussed, with licensing to an existing competitor being identified as the means with the least risk and greatest chance of success.
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Oliveira, Maria Angélica Hueb de Menezes. "Comparação dos aspectos morfológicos e químicos de esmalte e dentina de dentes decíduos e permanentes." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/58/58135/tde-30082010-093918/.
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O objetivo deste estudo in vitro foi avaliar e comparar a microestrutura e a composição mineral do esmalte e da dentina de dentes decíduos e permanentes. Terceiros molares hígidos e segundos molares decíduos foram selecionados e distribuídos aleatoriamente em grupos, de acordo com o método de análise dos substratos utilizado: Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Energia Dispersiva de Raio X (EDX), Difração de Raio X (DRX) e Microscopia Óptica (MO). Foi realizada comparação qualitativa e quantitativa da estrutura dental. As medidas de densidade numérica e diâmetro dos prismas de esmalte/túbulos dentinários e, de espessura do esmalte, dentina e dentina peritubular foram realizadas por meio de fotomicrografias obtidas pela MEV. Os resultados obtidos por meio da SEM foram analisados estatisticamente pelo teste não-paramétrico de Kruskal-Wallis. A quantidade relativa de íons cálcio (Ca) e fósforo (P) foram determinadas por meio de EDX e as fases químicas presentes em ambos os substratos, por análise de DRX. O valor das medidas de espessura observado para o esmalte e dentina dos dentes decíduos foi de 1.14 mm e 3.02 mm, respectivamente. Para os dentes permanentes, obtiveram-se valores de 2.58 mm para o esmalte e 5.95 mm para a dentina. Com relação ao diâmetro da cabeça dos prismas de esmalte, os resultados foram estatisticamente semelhantes para os dentes decíduos e permanentes, demonstrando uma ligeira diminuição do diâmetro da superfície externa para a região próxima a junção amelodentinária (JAD). A densidade numérica dos prismas foi maior nos dentes decíduos, principalmente próximo à JAD, sendo estatisticamente diferente dos valores observados nos dentes permanentes, independente da região analisada. Na análise do diâmetro e densidade numérica dos túbulos dentinários verificou-se semelhança estatística entre os dentes decíduos e permanentes, havendo aumento gradativo do número de túbulos a partir da JAD em direção a região próxima a polpa. A espessura da dentina peritubular, na região próxima a JAD e central foi, respectivamente, 0.91 e 0.59 mm nos dentes decíduos 1.16 e 0.98 mm nos dentes permanentes. A porcentagem de Ca e P foi maior nos dentes permanentes. Observou-se ainda, que a quantidade de colágeno nos dentes decíduos foi aparentemente menor quando analisados por meio da MO. De acordo com os resultados obtidos neste estudo, pode-se concluir que, de maneira geral, os dentes decíduos apresentam menor porcentagem de Ca e P, menor espessura de esmalte e dentina, maior densidade numérica de prismas e dentina peritubular mais delgada quando comparada aos dentes permanentes.This study evaluated in vitro the microstructure and mineral composition of dental enamel and dentin comparing the permanent teeth with the deciduous teeth. Sound third molars and second primary molars were selected and randomly assigned to the following groups, according to the analysis methods of the substrates performed: Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), Energy dispersive X-ray spectrometer (EDS) and Optical Microscopy (OP). A qualitative and quantitative comparison of the dental structure was done. The measurements of the number and diameter of prisms/tubules, thickness of enamel, dentin and peritubular dentin were done in SEM photomicrographs. The microscopic findings were analyzed statistically by a non-parametric test (Kruskal- Wallis). The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Phase present in both types of teeth were observed by the XRD analysis. The mean thickness measurements observed in the deciduous teeth enamel and dentin was, respectively, 1.14 mm and 3.02 mm and in the permanent teeth, 2.58 mm and 5.95 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enameldentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The mean tubules number and diameter in deciduous teeth were statistically similar to that of permanent teeth, and this numerical density increased from the EDJ to the region near the pulp. The mean thickness measurements of peritubular dentin observed in the regions near EDJ and central were, respectively, 0.91 and 0.59 mm for the primary teeth / 1.16 and 0.98 mm for the permanent teeth. The percentage of Ca and P was higher in the permanent teeth. The collagen level was apparently lower in deciduous teeth when analyzed by OP. The primary teeth structure showed a lower level of Ca and P and a thinner enamel and dentin thickness. The deciduous enamel presented higher numerical density of rods. The peritubular dentin was thicker in the permanent teeth.
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Hansson, Conny. "Development of a novel colour X-ray coherent scatter imaging system." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-novel-colour-xray-coherent-scatter-imaging-system(b8d3f9b0-60ea-48d1-9175-b8abc242a222).html.
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The field of X-ray imaging and X-ray diffraction have been combined in a new technique called Tomographic Energy Dispersive Diffraction Imaging (TEDDI). This diffraction imaging technique allows 3D sample images to be obtained, non-destructively, where each imaged point contains the atomic structural information associated with its diffraction pattern. The main drawback of the TEDDI technique is the long collection times needed to produce the images. In order to overcome this obstacle the rapid TEDDI (rTEDDI) system has been developed at the University of Manchester's Material Science Centre. The research and development of rTEDDI has been the focus of this PhD thesis. A proof of concept for the rTEDDI imaging technique was obtained using thin samples on station 7.6 SRS Daresbury. In this case a first generation array collimator was used in conjunction with an energy resolving Si pixelated detector. Structural information such as lattice parameters, crystal system and phase identiffcation were obtained for metal, polymer and deer antler bone samples. The use of high Z semiconductor detector material was investigated in order to increase the potential of TEDDI for larger and more dense samples. To enable penetration of larger samples high energy X-rays needed to be utilized. In order to detect these higher energies with a good efficiency the detector media was changed from Si to CdZnTe (CZT).The second generation rTEDDI, using CZT as the detection media, was intended to be used under high flux/high energy synchrotron radiation conditions. Testing of the system under these conditions on station 16.3 SRS Daresbury showed an inability to produce diffraction imaging. An in depth investigation into detector and collimator array performance showed a two fold cause. The ERD2004 detector was unable to handle the high countrates experienced during high flux/high energy synchrotron radiation conditions. The MK1.2 collimator array was found to become partially transparent to X-ray energies around the absorption edge of W resulting in the swamping of the diffraction signal under high flux/high energy synchrotron radiation conditions. A new detector Application Specific Integrated Circuit (ASIC) design, developed by the detector division and the Rutherford Appleton Laboratory, and Data Aquisition (DAQ) system, developed by Aspect Systems, as well as a number of new collimator array designs were developed and tested. Testing of the new collimator array structures have shown positive results and the new HEXITECdetector which was designed to be able to handle high countrates, have shown an unprecedented inter pixel uniformity and energy resolution which have been attributed to the ASIC performance and the use of better quality CZT material.
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Toivanen, Tommi. "Mobilt bredband till mobil röntgen : Förbättring av Region Skånes pilotprojekt med mobil röntgenverksamhet." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-21203.
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Detta arbete beskriver en examensuppsats i datateknik på Linnéuniversitetet. Röntgenavdelningen på SUS, Skånes Universitetssjukhus i Lund, använder en lättviktig flyttbar röntgenmaskin som väger endast cirka 90 kg, för röntgenundersökningar ute på äldreboenden. Bilderna överförs till sjukhusets PACS när maskinen är tillbaka på sjukhuset, genom att man kopplar in Dragon via kabel till sjukhusets nätverk. Målsättningen är att förbättra den trådlösa kommunikationen som för närvarande är för långsam och opålitlig, så att bilderna kan överföras till sjukhusets PACS direkt efter undersökningen. I detta arbete beskrivs vilka alternativ som kan användas. Samt om de mobila bredbandstjänster som finns tillgängliga i Region Skåne är bra nog för att kunna användas för uppgiften. Slutsatsen är att ett 3G HSDPA/HSUPA abonnemang kan vara tillförlitligt nog. Framför allt om extra redundans tillförs med dubbla SIM-kort som använder separata nät och att signalen förstärks med antenn placerad utomhus på transportfordonet. Transportfordonet används som brygga mellan Wifi och mobilt nätverk. Röntgenmaskinen kommunicerar med transportfordonet via Wifi. För de fall Wifi inte fungerar på grund av byggnader och omgivande miljö arbetades ett reservalternativ fram. Jag har också undersökt och jämfört DICOM protokollet mot FTP. Detta för att se om DICOM har en overhead som skulle motivera användet av FTP istället för sändning av bilder. Resultatet av jämförelsen visade att DICOM har 5-10 % overhead jämfört med FTP.This abstract describes a degree project in computer engineering at Linnaeus University. The Department of Radiology at SUS, Skåne University Hospital in Lund, is using a lightweight portable x-ray machine that weights about 90 kg, for radiography services in nursing homes for elders. The images are transferred to hospital PACS when the machine returns to the hospital, this is done with Dragon connecting to hospital network via wire. The goal is to improve the currently too slow and unreliable wireless communication, so the images can be transferred to hospital PACS directly after examination. This report describes what alternatives can be used and investigates whether the mobile broadband services currently available in Skåne County are good enough to be relied on for the task. The conclusion is that a 3G HSDPA/HSUPA subscription can be used reliably enough, if extra redundancy is added via dual SIM cards using separate mobile networks and the signal is strengthen by an antenna placed outdoors on the transport vehicle. The transport vehicle is used as a bridge between Wifi and mobile networks. The mobile x-ray machine communicates with the transport vehicle via Wifi. In those cases Wifi does not work due to difficult building environments, a backup solution was worked out to be used. I also investigated and compared the DICOM protocol against FTP. This was to find out if DICOM has an overhead that would motivate using FTP instead for the transmission of the images, the result of the comparison showed that DICOM has an 5-10 % overhead compared with FTP.
Mobil röntgen Skånes Universitetssjukhus Lund
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Lindström, Sofia, and Maja Becarevic. "Gadoliniumansamling hos patienter med multipel skleros samt implementering av artificiell intelligens vid magnetresonanstomografi." Thesis, Luleå tekniska universitet, Institutionen för hälsa, lärande och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-82796.
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Introduktion: Uppskattningsvis 40% av alla magnetresonanstomografiska (MRT) undersökningar som görs i Europa och USA utförs med gadoliniumbaserade kontrastmedel. Under det senaste decenniet har det i flera studier uppmärksammats att ansamling av gadolinium sker i olika strukturer i hjärnan. Patienter med multipel skleros följs regelbundet upp med MRT undersökningar och MRT med kontrastförstärkning är den vanligaste metoden för att urskilja nytillkomna patologiska förändringar. Utveckling inom teknologi och metoder inom artificiell intelligens har visat att det finns anledning att kartlägga om röntgensjuksköterskans arbete med undersökningar och läkemedel som administreras till patienter kan förändras så att det förebygger ansamling av gadolinium. Syfte: Syftet med denna litteraturöversikt var att kartlägga ansamlingen av gadoliniumkontrastmedel hos patienter med multipel skleros och hur artificiell intelligens kan tillämpas vid MRT för att minska användning av gadoliniumkontrast. Metod: Allmän litteraturöversikt där vetenskapliga artiklar av kvantitativ studiedesign har sökts fram genom databaserna CINAHL och PubMed. Resultat: Både makrocykliska och linjära gadoliniumbaserade kontrastmedel ansamlas i de basala ganglierna. Genom tillämpning av AI och CAD går det att framställa bilder med fullgod bildkvalitet och samtidigt reducera mängden kontrastmedel som administreras till patienten. Slutsats: Det behövs mer forskning om gadoliniumansamling för att nya rutiner och metoder ska kunna implementeras. Ansamling av gadolinium visar att det finns skäl att fortsätta utveckla nya metoder för uppföljning av sjukdomsförloppet hos MS-patienter. När det gäller AI inom medicinsk bilddiagnostik och magnetresonanstomografi finns många utvecklingsmöjligheter som kan bidra till minskning av gadoliniumbaserad kontrast i framtiden. Fortsatt forskning inom deep learning och CAD kan i framtiden utvecklas så att röntgensjuksköterskan får en mer självbestämmande funktion i bildframställning vid MRT, men även ett mer självständigt arbete i hanteringen av farmaka. Dessutom kan denna utveckling bidra till att röntgensjuksköterskans multidiciplinära samverkan med radiologer stärks och bidrar till en positiv utveckling med kortare granskningstider, bättre hantering av patienter, optimerade undersökningar, minskning av undersökningstider och kortare vårdköer.Introduction: Approximately 40% of all magnetic resonance imaging (MRI) scans performed in Europe and the United States are performed with gadolinium based contrast agents. Over the past decade, several studies have shown a gadolinium deposition in various structures in the brain. Patients with multiple sclerosis are regularly followed up with MRI with contrast enhancement is the most common method for distinguishing new pathological changes. Developments in technology and methods in artificial intelligence have shown that there is reason to map out whether the radiographers work with examinations and drugs administered to patients can be changed so that the accumulation of gadolinium is prevented. Aim: The purpose of this literature review was to examine the accumulation of gadolinium contrast agents in patients with multiple sclerosis of gadolinium contrast agents in patients with multiple sclerosis and how artificial intelligence can be applied in MRI to reduce the use of gadolinium based contrast agents. Methods: General literature review where scientific articles of a quantitative nature have been searched through the databases CINAHL and PubMed. Results: Both macrocyclic and linear gadolinium based contrast agents are retained in the basal ganglia. With artificial intelligence and CAD, it is possible to obtain data with good quality and at the same time reduce the amount of gadolinium based contrasts to patients. Conclusions: More research on gadolinium accumulation is needed for new routines and methods to be implemented. Accumulation of gadolinium shows that there is reason to continue to develop new methods for monitoring the course of the disease in MS patients. Concerning AI in medical imaging and magnetic resonance imaging, there are many development opportunities that can contribute to the reduction of gadolinium contrast in the future. Continued research in deep learning and CAD can be developed in the future so that the X-ray nurse has a more self-determining function in image production in MRI, but also a more independent work in the management of pharmacies. In addition, this development can contribute to the X - ray nurse's multidisciplinary collaboration with radiologists is strengthened and contributes to a positive development in shorter examination times, better management of patients, optimized examinations, reduction of examination times and shorter care queues.
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Pei, Ruizhi. "Self-healing behaviour of MAX phase ceramics studied by computed X-ray tomography." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/selfhealing-behaviour-of-max-phase-ceramics-studied-by-computed-xray-tomography(6950ce07-616b-4c0a-8ded-77d811735791).html.
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MAX phase ceramics are promising candidates as high temperature materials. The self-healing capabilities of these materials may further improve their reliability and reduce maintenance costs during service. However, previous two dimensional research on their healing behaviour is either inadequate or sometimes even biased, because crack healing is essentially a three dimensional process. In this study, the self-healing behaviour of two MAX phase ceramics: Ti2AlC and Cr2AlC were investigated in three dimensions using high resolution synchrotron and laboratory X-ray tomography. The Ti2AlC showed remarkable healing ability of repeatedly repairing cracks at 1150 °C for three healing cycles with each healing cycle lasting less than 66 minutes. The healing kinetics of Ti2AlC was revealed to have a strong dependence on crack location, which deviates from a previously proposed uniform healing model. The Ti2AlC maintains its healing kinetics when the post-healing crack propagation follows a different growth path to the original crack. While a decreased healing kinetics was observed if the crack grows through a previous healed zone. The strength recovery is closely related to the healing percentage, where a full strength recovery was achieved with a healing percentage of over 90 %. In comparison, the Cr2AlC showed a much slower healing kinetics, with a parabolic constant of 4.3×10-3 µm2•s-1. The healing process of Cr2AlC was revealed to be more or less independent of crack location, where crack tip is always healed first. The crack gap is filled by purely Al2O3 after healing without the formation of Cr2O3. The composition of the healed area varies along the crack. A Cr7C3 sublayer beneath the Al2O3 layer was found at the healed zone of crack root, while missing in the healed zone at crack tip. The influence of impurity Cr particles on healing kinetics was investigated through a correlative microscopy study, combining X-ray tomographic slices with SEM images. The existence of Cr particles was found to accelerate the healing rate. However, this was always accompanied by the formation of large pores, which may be detrimental to the strength recovery after healing.
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Slater, Thomas Jack Alfred. "Three dimensional chemical analysis of nanoparticles using energy dispersive X-ray spectroscopy." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/three-dimensional-chemical-analysis-of-nanoparticles-using-energy-dispersive-xray-spectroscopy(3eb607a2-eb03-4d45-b9eb-71b0ca45c2db).html.
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The aim of this thesis is to investigate the methodology of three dimensional chemical imaging of nanoparticles through the use of scanning transmission electron microscope (STEM) – energy dispersive X-ray (EDX) spectroscopy. In this thesis, an absorption correction factor is derived for spherical nanoparticles that can correct X-ray absorption effects. Quantification of EDX spectra of nanoparticles usually neglects X-ray absorption within the nanoparticle but may lead to erroneous results, thus an absorption correction is important for accurate compositional quantification. The absorption correction presented is verified through comparison with experimental data of Au X-ray peaks in spherical Au nanoparticles and is found to agree excellently. This absorption correction allows accurate compositional quantification of large ( > 100 nm) particles with STEM-EDX.Three dimensional chemical mapping is achievable through the use of EDX spectroscopy with electron tomography. Here, the methodology of STEM-EDX tomography is fully explored, with a focus on how to avoid artefacts introduced through detector shadowing and low counts per pixel. A varied-time acquisition scheme is proposed to correct for detector shadowing that is shown to provide a more constant intensity over a series of projections, allowing a higher fidelity reconstruction. The STEM-EDX tomography methodology presented is applied to the study of AgAu nanoparticles synthesized by the galvanic replacement reaction. The elemental distribution as a function of the composition of the as-synthesized nanoparticles is characterised and a reversal in the element segregated to the surface of the nanoparticles is found. The composition at which the reversal takes place is shown to correlate with a peak in the catalytic yield of a three component coupling reaction. It is hypothesized that a continuous Au surface results in the optimum catalytic conditions for the reaction studied, which guides the use of galvanically prepared AgAu nanoparticles as catalysts.
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Jiang, Hui. "Characteristics of multilayer mirrors in the X-ray and extreme ultraviolet radiation ranges." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/characteristics-of-multilayer-mirrors-in-the-xray-and-extreme-ultraviolet-radiation-ranges(8ef44408-8d96-48f9-8e61-83dbca281db2).html.
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This thesis comprehensively describes the computational design, fabrication and characterisation of multilayer mirrors intended as key reflective elements for the X-ray and extreme ultraviolet radiation ranges. The first central theme was to present various designs for the requirements of soft X-ray microprobes, EUVL lithography systems and high harmonic generation sources, i.e. monochromator, broad-angle supermirror, broadband intensity and polarising beamsplitters and order-selecting mirror. The particle swarm optimisation method was successfully applied in a global search of materials for the structure of mirrors. The robust designs made possible are considered to alleviate fabrication difficulties, such as control of layer thickness errors. The second important theme was to analyse the interfacial and surface imperfections in multilayer mirrors. This work is crucial in improving the fabrication technology and in : understanding the basic growth status at the interfaces. Transmission electron microscopy, X-ray diffraction and atomic force microscopy were used in these experiments. The analyses are based on innovative methods, namely time series analysis and wavelet analysis. The evolution tendencies of the layer thicknesses, interfacial roughness and interdiffusion were determined, as were correlated growth, structural uniformity, surface stress damage and surface roughness. The final theme was to test a multilayer monochromator for use in a soft X-ray microprobe for radiobiological studies on pathological cells and tissue. The source spectrum was determined using different incidence angles on multilayer mirrors and some suggestions for improvement were presented.
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Seymour, Thomas. "Synchrotron X-ray diffraction peak profile analysis of neutron- and proton-irradiated zirconium alloys." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/synchrotron-xray-diffraction-peak-profile-analysis-of-neutron-and-protonirradiated-zirconium-alloys(5765de34-361d-4a74-a9b0-22eb047dd6f3).html.
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One of the degradation processes of zirconium-based nuclear fuel assemblies is irradiation-induced growth, an anisotropic, stress-independent, macroscopic deformation mechanism that elongates fuel cladding tubes axially. Irradiation-induced growth is driven by the irradiation-induced formation of dislocation loops, where the evolution of the loop structure can be complex, with the initial formation of loop generating transient growth, while the later formation of component dislocation loops, or loops, leads to accelerated growth. A full mechanistic understanding of loop nucleation is as yet unforthcoming. This thesis utilizes the diffraction peak broadening analysis software, named extended Convolutional Multiple Whole Profile, to study the dislocation structure evolution of neutron- and proton-irradiated zirconium alloys in order to validate proton-irradiation as a effective tool for the study of irradiation damage in relation to irradiation-induced growth. The diffraction profiles obtained exhibit unexpected features present in the tails of the Bragg peaks, tentatively attributed here to either strained regions of matrix, or diffuse scattering from severely distorted regions around nucleating precipitates, both originating from an increased solute concentration. The diffraction results indicate that the proton-irradiated samples exhibit qualitatively similar behaviours as seen from neutron-irradiation, such as a threshold irradiation dose before the formation of loops, however, a continued increase of loop dislocation density determined from peak broadening analysis is not observed by transmission electron microscopy. It is also shown that the Nb-containing Low-Sn ZIRLO® alloy has a lower dislocation density than the Nb-free Zircaloy-2 after the formation of loops correlating well with the relative irradiation-induced growth behaviours observed in- reactor. A correlation between a reduction in the loop dislocation density and the formation of loops is observed in Low-Sn ZIRLO® and Zr-1.60Sn-0.033Fe, providing support for the hypothesis that vacancy loops transform into loops. Zr- 0.61Sn-0.024Fe and Zr-1.60Sn-0.033Fe alloys show a rapid increase in the loop dislocation density in the initial stages of proton-irradiation, likely due to the low irradiation-resistance of the precipitates present in these alloys.
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Sencu, Razvan. "Multiscale stochastic fracture mechanics of composites informed by in-situ X-ray CT tests." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/multiscale-stochastic-fracture-mechanics-of-composites-informed-by-insitu-xray-ct-tests(85a0be40-9e7a-4df3-a366-69ac6ce02e35).html.
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This thesis presents the development of a new multiscale stochastic fracture mechanics modelling framework informed by in-situ X-ray Computed Tomography (X-ray CT) tests, which can be used to enhance the quality of new designs and prognosis practices for fibre reinforced composites. To reduce the empiricism and conservatism of existing methods, this PhD research systematically has tackled several challenging tasks including: (i) extension of the cohesive interface crack model to multi-phase composites in both 2D and 3D, (ii) development of a new in-house loading rig to support in-situ X-ray CT tests, (iii) reconstruction of low phase-contrast X-ray CT datasets of carbon fibre composites, (iv) integration of X-ray CT image-based models into detailed crack propagation FE modelling and (v) validation of a partially informed multiscale stochastic modelling method by direct comparison with in-situ X-ray CT tensile test results.
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Polatidis, Efthymios. "Residual stress and phase characterisation on zirconium oxides using synchrotron X-ray diffraction." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/residual-stress-and-phase-characterisation-on-zirconium-oxides-using-synchrotron-xray-diffraction(b0bc325a-2a94-4323-8739-7ea9b04727f3).html.
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The present work was produced as part of the MUZIC consortium, a collaboration between a multi-university team from the UK and industrial partners working on the field of nuclear energy, fabrication of alloys and nuclear research. The aim of the project is to establish a multidiscipline mechanistic understanding of the corrosion and breakaway processes of zirconium alloys used as fuel cladding materials in the nuclear industry. A better understanding of the corrosion mechanism of zirconium alloys will not only aid the development of better performing alloys, but will also allow more accurate models to be developed to reliably predict the service life of existing alloys. This could lead to higher burn-up, increase of energy production and reduction of nuclear waste produced.This work seeks to provide a better understanding of the role of residual stresses in the oxide, which are produced during oxidation due to high Pilling-Bedworth ratio and their impact on oxide phase transformation and oxidation kinetics by employing high energy synchrotron X-ray diffraction techniques. This is achieved by observing how stresses change as oxide growth approaches and passes through transition of the corrosion kinetics, their evolution across the oxide thickness, in situ characterising stresses and phase growth early in oxidation process and how stress changes can affect corrosion properties.It was found that relatively high compressive stresses in the two oxide crystal structures are present. The stresses relax with time up to moments before transition where a possible threshold stress magnitude is reached to aid an extensive tetragonal to monoclinic phase transformation. This generalised tetragonal to monoclinic transformation is believed to produce highly stressed monoclinic crystal structure grains and cause defects in the oxide. The above observation is further supported by a decrease of the tetragonal zirconia content. This is the moment that the oxide looses its protective character and a transition of the corrosion kinetics occurs. By comparing different materials it was observed that the minimum magnitude of the tetragonal phase is lower in better performing alloys while the tetragonal content is some cases was relatively low. It is suggested that the amount of the tetragonal phase, in the oxide layer, is not as important as the rate of it transforming into monoclinic. The extent of tetragonal to monoclinic transformation, that introduces defects in the oxide, defines how protective an oxide layer is. The present work provides a contribution to the available knowledge of the importance of residual stresses in the oxide layer and metal substrate of zirconium alloys and how they can affect corrosion rates or act as a precursor to the corrosion transition.
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Penney, Graeme. "Registration of tomographic images to X-ray projections for use in image guided interventions." Thesis, King's College London (University of London), 2000. https://kclpure.kcl.ac.uk/portal/en/theses/registration-of-tomographic-images-to-xray-projections-for-use-in-image-guided-interventions(79e28525-ae06-4843-bd75-e1fab126e434).html.
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This thesis contributes to knowledge by describing a new method to allow information from a pre-operative 3D modality to be used during an intervention which is guided using 2D fluoroscopy images. An algorithm has been designed to obtain the pose of a CT volume with respect to a single fluoroscopy image. The registration algorithm is based on the production of digitally reconstructed radiographs from the CT volume, which are compared to the fluoroscopy image using a similarity measure. The novelty of the work described in this thesis is in both the design of the registration algorithm and also in investigating the specific requirements placed upon a similarity measure when attempting to register a pre-operative CT volume to an interventional fluoroscopy image. Seven similarity measures were investigated. Experiments were carried out to calculate the accuracy and robustness of the registration algorithm using each similarity measure. Initially fluoroscopy and CT images of a lumbar spine phantom were used. The accuracy of the registration algorithm was calculated by comparing the final registration positions with a ``gold-standard'' registration calculated using fiducial markers. More realistic datasets were simulated using the phantom fluoroscopy image with clinical image features overlaid. Results show that the introduction of soft-tissue structures and interventional instruments into the phantom image can have a large effect on the performance of some similarity measures previously applied to 2D-3D image registration. The similarity measures were also tested on clinical data from aortic stenting procedures, where k-fold cross validation was used to obtain an estimate of the registration accuracy. The results from these experiments showed that two measures were able to register accurately (RMS rotational error of 0.76 degrees and RMS in-plane translational error of 0.85mm) and robustly (10% failure rate) even when soft-tissue structures and interventional instruments were present as differences between the images. These two measures were pattern intensity and gradient difference. Finally the thesis describes a novel combination of the 2D-3D registration algorithm with a deformation algorithm. The registration algorithm was used to obtain information on the relative movement of the vertebrae between the pre-operative CT image and interventional fluoroscopy image. This information was then used to warp the pre-operative modality so that it more accurately represented the intra-operative scene.
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Ren, Wenyuan. "In-situ X-ray computed tomography characterisation and mesoscale image based fracture modelling of concrete." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/insitu-xray-computed-tomography-characterisation-and-mesoscale-image-based-fracture-modelling-of-concrete(3307ca0b-b492-4bfc-91f7-61c092b21707).html.
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This study develops a 3D meso-scale fracture characterisation and modelling framework for better understanding of the failure mechanisms in concrete, by combining in-situ micro-scale X-ray computed tomography (XCT) experiments and XCT image-based finite element (FE) simulations. Firstly, sophisticated in-situ XCT experiments are conducted on concrete cubes under Brazilian-like, uniaxial and cyclic compression. Proper procedures for XCT image reconstruction and multi-phasic segmentation are identified. The fracture evolution at different loading stages is characterised and visualised as well as the detailed distributions of aggregates and voids. The Young's moduli of aggregate and cement are obtained by micro-indentation tests and used in XCT-image based asymptotic homogenisation simulations to calculate effective elastic constants of concrete cubes. The XCT technique proves very powerful in characterising and visualising the complicated 3D fracture evolution in concrete. The material properties and the segmented 3D images from the experiments are then used for FE fracture simulations with realistic aggregates, cement and voids. Image-based mesh generation algorithms are developed for 2D in a MATLAB code and identified for 3D in Simpleware. Cohesive interface elements are embedded within cement and aggregate-cement interfaces to simulate the complex nonlinear fracture. Extensive simulations of 40mm and 20mm cubes under compression and tension are carried out. Good agreements are achieved between the load-displacement curves and final crack patterns from the simulations and those from the compressive in-situ XCT tests. The XCT image-based modelling proves very promising in elucidating fundamental mechanisms of complicated crack initiation and propagation in concrete.
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Evans, Llion Marc. "Thermal finite element analysis of ceramic/metal joining for fusion using X-ray tomography data." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/thermal-finite-element-analysis-of-ceramicmetal-joining-for-fusion-using-xray-tomography-data(5f06bb67-1c6c-4723-ae14-f03b84628610).html.
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A key challenge facing the nuclear fusion community is how to design a reactor that will operate in environmental conditions not easily reproducible in the laboratory for materials testing. Finite element analysis (FEA), commonly used to predict components’ performance, typically uses idealised geometries. An emerging technique shown to have improved accuracy is image based finite element modelling (IBFEM). This involves converting a three dimensional image (such as from X ray tomography) into an FEA mesh. A main advantage of IBFEM is that models include micro structural and non idealised manufacturing features. The aim of this work was to investigate the thermal performance of a CFC Cu divertor monoblock, a carbon fibre composite (CFC) tile joined through its centre to a CuCrZr pipe with a Cu interlayer. As a plasma facing component located where thermal flux in the reactor is at its highest, one of its primary functions is to extract heat by active cooling. Therefore, characterisation of its thermal performance is vital. Investigation of the thermal performance of CFC Cu joining methods by laser flash analysis and X ray tomography showed a strong correlation between micro structures at the material interface and a reduction in thermal conductivity. Therefore, this problem leant itself well to be investigated further by IBFEM. However, because these high resolution models require such large numbers of elements, commercial FEA software could not be used. This served as motivation to develop parallel software capable of performing the necessary transient thermal simulations. The resultant code was shown to scale well with increasing problem sizes and a simulation with 137 million elements was successfully completed using 4096 cores. In comparison with a low resolution IBFEM and traditional FEA simulations it was demonstrated to provide additional accuracy. IBFEM was used to simulate a divertor monoblock mock up, where it was found that a region of delamination existed on the CFC Cu interface. Predictions showed that if this was aligned unfavourably it would increase thermal gradients across the component thus reducing lifespan. As this was a feature introduced in manufacturing it would not have been accounted for without IBFEM.The technique developed in this work has broad engineering applications. It could be used similarly to accurately model components in conditions unfeasible to produce in the laboratory, to assist in research and development of component manufacturing or to verify commercial components against manufacturers’ claims.
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Amos, Mathew. "Advanced industrial X-ray computed tomography for defect detection and characterisation of composite structures." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/advanced-industrial-xray-computed-tomography-for-defect-detection-and-characterisation-of-composite-structures(7da52044-004e-4253-b1d2-0cb1e85ce28d).html.
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X-ray Computer Tomography (CT) is well suited to the inspection of Fibre-Reinforced-Plastic (FRP) composite materials. However, a range of limitations currently restrict its uptake. The aim of the present research was to develop advanced inspection procedures that overcome these limitations and increase the scope of composite structures that can be inspected by industrial cone beam CT. Region of Interest (ROI) CT inspection of FRP laminated panels was investigated and two data completion methods developed to overcome reconstruction errors caused by truncated projection data. These allow accurate, highly magnified regions to be reconstructed on objects that extend beyond the Field-of-View (FOV) of the detector. The first method extended the truncated projection data using a cosine signal tailing off to zero attenuation. This method removed the strong 'glowing' artefacts but an inherent error existed across the reconstructed ROI. This did not affect the defect detectability of the inspection but was viewed as problematic for applications requiring accurate density measurements. The second method used prior knowledge of the test object so that a model could be created to estimate the missing data. This technique removed errors associated with ROI reconstruction thus significantly improving the accuracy. Techniques for extending the FOV were developed and applied to the inspection of FRP wind turbine blades; over 1.5X larger than the conventional scanning FOV. Two data completion methods were developed requiring an asymmetrically positioned detector. The first was based on the cosine tailing technique and the second used fan beam ray redundancy properties to estimate the missing data. Both produced accurate reconstructions for the 'offset' projection data, demonstrating that it was possible to approximately double the FOV. The cosine tailing method was found to be the more reliable. A dual energy image CT technique was developed to extend the optimum dynamic range and improve defect detectability for multi-density objects. This was applied to FRP composite/Titanium lap joints showing improved detectability of both volumetric and planar defects within the low density FRP. The dual energy procedure was validated using statistical performance measures on a specially fabricated multi-density phantom. The results showed a significant improvement in the detail SNR when compared to conventional CT scans.
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Rouse, Jordan Elliott. "Characterisation of impact damage in carbon fibre reinforced plastics by 3D X-ray tomography." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-impact-damage-in-carbon-fibre-reinforced-plastics-by-3d-xray-tomography(8788b306-2811-4574-984a-eceae5ed31b0).html.
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Carbon fibre reinforced plastics (CFRP's) are finding increased used as structural materials in many transport applications, particularly next generation commercial aircraft. The impact damage tolerance of these materials is relatively poor compared to conventional aircraft materials such as aluminium. As a result there is a concerted research effort to improve the damage tolerance of these materials. Understanding the microstructural mechanisms of damage can help to design improved materials. Three-dimensional X-Ray computed tomography (CT) allows these damage mechanisms to be identified and quantified non-destructively. However, a lack of published work in the field means no consistent methodologies for imaging or quantifying damage in CFRP's using X-Ray tomography exist. This thesis provides several novel methodologies for imaging and quantifying impact damage using X-Ray CT. A dual energy imaging methodology was developed to overcome the reduction in CT image quality caused by the high aspect ratio of CFRP structures. This approach resulted in a 66% increase in signal-to-noise ratio, and a 109% increase in contrast-to-noise ratio. The development of a methodology for quantifying impact damage in CFRP based on thresholding the in-plane damage area showed good agreement with ultrasonic C-scan results, and allowed correlations between impact energy, damage area and compression-after-strength to be made. Region of interest (ROI) algorithms for high magnification imaging of impact damage in CFRP plates were investigated. These algorithms were not developed by the author, but further understanding of their effectiveness and practical applications is presented in this work. Finally, a novel X-Ray tomographic imaging technique using interferometry was applied to imaging impact damage in CFRP's. This method was developed by a research group in Switzerland at the \emph{Centre Suisse d'Electronique et de Microtechnique} (CSEM) in Zurich. The work in this thesis presents the first application of the technique to image impact damage in CFRP.
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Thomason, Matthew James. "Soft X-ray spectroscopy of molecular species in solution : studies of imidazole and imidazole/water systems." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/soft-xray-spectroscopy-of-molecular-species-in-solution-studies-of-imidazole-and-imidazolewater-systems(ae99d759-ca04-4e9a-b585-7a91b8aa2929).html.
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Soft X-ray near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy of liquids, an emerging synchrotron radiation technique, has been applied to characterise the local environment of imidazole in aqueous solution to elucidate the structural nature of the well known self-association effects in this system. Atomic core level spectroscopies such as NEXAFS are extremely sensitive to short range structure, including bond lengths and angles as well as coordination numbers, in condensed matter and in molecular systems.N K-edge NEXAFS data were successfully acquired for aqueous imidazole solutions were studied from low concentrations (10−2 mol L−1) to saturation (> 8 mol L−1). Previous UV/Vis studies had established that imidazole undergoes significant self-association already at concentration well below 1 mol L−1 while energy-dispersive X-ray diffraction studies indicated the formation of water mediated hydrogen-bonded self-associated structures of imidazole.NEXAFS revealed that in the concentration range from 0.50 (~100 H2O molecules per imidazole molecule) to the saturation concentration of 8.20 mol L−1 (~7 H2O molecules per imidazole molecule) no significant variation in the local coordination around imidazole molecules takes place. It appears that progressive self-association at higher concentration is not associated with local structural changes.Using ab initio calculations of N K-edge spectra for complex structure models that explicitly included the evaluation of imidazole gas phase data, the imidazole crystal structure as well as imidazole-imidazole and imidazole-solvent interactions in solution, it was possible to relate the observed imidazole spectra to structure models. Systematic calculations evaluating gas phase monomers and oligomers of pure imidazole, the solid state of imidazole, stacked self-associated imidazole clusters in solution, chained structures of self-associated clusters in solution, and explicitly including the water solvation shell were carried out. Comparative measurements in with chloroform solutions shed some light on the nature of the self-associates present at the lower concentrations investigated in this work.Examining also synergistic interactions between imidazole and water the view was obtained that increasing the concentration of imidazole solutions leads to the assembly of self-associated clusters of hydrated imidazole monomers, which are held together by secondary interactions that are weaker than the hydrogen bonding in the hydrate shell. This result demonstrates the suitability of soft X-ray spectroscopy measurements for the investigation of local structure in solutions of molecular organic solutes.
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Wadeson, Nicola Lisa. "Modelling and correction of scatter in a switched source multi-ring detector X-ray CT machine." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/modelling-and-correction-of-scatter-in-a-switched-source-multiring-detector-xray-ct-machine(a6700209-0eef-47d8-9ff0-1fa5e7bb67c5).html.
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The RTT80 cone beam x-ray computed tomography system, developed by Rapiscan Systems Ltd, uses switched x-ray sources and fixed offset detector rings to remove the time consuming mechanical rotations of earlier imaging systems. This system produces three-dimensional images in real time. A Geant4 Monte Carlo simulation has been developed to investigate scattered radiation in the uncollimated detector machine, showing high levels of scatter behind highly attenuating objects. A new scatter correction method is proposed which estimates scatter to each detector, in each projection, from 1cm³ voxels of the computerised object. The scatter distributions from different materials are pre-determined using a Geant4 Monte Carlo simulation. The intensity of scatter from each voxel is based on measured data. The method is applied to two simulated test objects, a water box simulated with a monoenergetic input spectrum and a test suitcase simulated with a polyenergetic spectrum. The test suitcase is broken down into separate components to analyse the method further. The results show that the method performs well for low attenuating objects, but the results are sensitive to the intensity values. However, the method provides a good basis for a scatter correction method.
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Forshaw, Roger. "The role of the lector (Xry-Hbt) in Ancient Egyptian society." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-role-of-the-lector-xryhbt-in-ancient-egyptian-society(e2aaafcd-c9b2-47cb-8094-b79f6dc31aa2).html.
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The lector priest (Xry-Hbt) - literally ‘he who carries the festival (papyrus) roll’- has been considered in previous studies to be one of several categories of the ancient Egyptian priesthood. There is a perception that he was responsible for the correct performance of rites, that he recited invocations during temple and state ritual, and that he carried out recitations and performed ritual actions during private apotropaic magic and funerary rites. Textual and iconographic evidence demonstrate his presence at rituals and frequently refer to the title of Xry-Hbt, but these sources do not provide an explicit explanation of his role. Previous treatments of the lector have rarely considered the full extent of his activities, either focusing on specific aspects of his work or making general comments about his role. This present study challenges this selective approach and explores his diverse functions in a wide ranging review of the relevant evidence. The lector is first attested during the 2nd Dynasty (c. 2890-2686 BC) and is predominately portrayed with an unrolled papyrus scroll in his hand, a broad strap from his shoulder across his chest, and is recognised throughout ancient Egypt history. The many titles that were appended to Xry-Hbt suggest a wide rang of functions and operating spheres from that of funerary workshop to particular temples and deities. The lector is closely associated with ‘magic’ where his knowledge of spells and performative ritual define him as a leading protagonist in this field. At funerary ceremonies his delivery of the ‘transfigurations’ enabled the deceased to become an akh, and in the Opening of the Mouth ceremony, along with the sem-priest, he would perform the rite of animation. In the temple he not only performed recitations and executed a variety of ritual actions but he directed ritual practices. He had a role in the royal palace as attested by titles such as ‘lector of the king’, and he is seldom absent from scenes representing the royal Sed-festival. The lector had an involvement in healing but less clear is the reason for his presence on the various mining expeditions that were a feature of Pharaonic Egypt. There is some limited evidence of his role sitting on legal assemblies, both temple-based and in the community. Much of the literature relating to ancient Egypt translates the Xry-Hbt title as ‘lector-priest’, but the evidence reviewed suggests him to be more of a ritualist rather than a ‘priest’. In contrast to the Hm-nTr and the wab-priest who served the gods and were associated primarily with temples - temple activity was merely one of the operating areas of the lector. Based upon a common definition of a priest as ‘one who is authorised or ordained to perform religious rites’, I suggest that the title of ‘lector priest’ incorrectly describes this officiant and a more appropriate definition would be limited to that of ‘lector’.
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Kepsutlu, Burcu. "Interaction of Biologically Relevant Nanoparticles with Cells Studied by Cryo Soft X-Ray Tomography." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19803.
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In dieser Arbeit, wurden Endozytose und intrazellulären Transportwegen für zwei verschiedene biologisch relevante Nanopartikel (dendritisch Polyglycerolsulfat (dPGS-np) und Polyethylenimin beschichtete Goldnanopartikel (PEI-np)) mit Kryo-Röntgentomographie untersucht. Diese Untersuchungen zeigten, beide Nanopartikeln über Makropinozytose endozytiert werden und dass die meisten Nanopartikel in Endosomen, multivesikulären Körpern und Lysosomen lokalisiert sind. Trotz dieser Ähnlichkeiten im Verhalten beider Partikel gab es auch Unterschiede die zeigten. Im Gegensatz zu PEI-np, wurden einige dPGS-np in Lipidtröpfchen gefunden. Weiterhin verursachen die PEI-np bei einer Konzentration von 0,13 nM ein Zerplatzen von Lysosomen in erheblichem Ausmaß wodurch die Nanopartikel in das Zytoplasma entweichen und teilweise in den Zellkern eindringen. Im Unterschied dazu konnte kein Nachweis für ein Zerplatzen von Lysosomen durch dPGS-np erbracht werde. Interessanterweise wurde ein Wechsel des Endocytose-Weges von der Makropinozytose zu einer mutmaßlichen Caveolae-vermittelten Endozytose beobachtet, wenn die PEI-np-Konzentration um das Zehnfache reduziert wurde. Unter diesen Bedingungen induzierten PEI-np kein Zerplatzen von Lysosomen mehr. Das Ausbleiben von zerplatzten Lysosomen bei dieser niedrigeren Konzentration korreliert mit einer verringerten Zellschädigung und hat somit wichtige Auswirkungen auf die Verwendung von PEI beim Gentransfer. Überraschenderweise stellte sich heraus, dass beide Nanopartikelarten eine bisher nicht beobachtete umfassende zytoplasmatische Veränderungen in den Zellen induzierten. Insbesondere wurden nach der Inkubation mit beiden Diese zytoplasmatischen Veränderungen könnten wichtige physiologische Veränderungen widerspiegeln, jedoch ist hierzu zusätzliche Forschung erforderlich. Diese Beobachtungen deuten darauf hin, dass das Verhalten biologisch relevanter Nanopartikel in Zukunft vorhersehbarer werden kann durch weitere systematische Studien.In this thesis, the endocytosis and trafficking pathways of two different biologically relevant nanoparticles, namely dendritic polyglycerol sulfate coated gold nanoparticles (dPGS-np) and polyethyleneimine coated gold nanoparticles (PEI-np) were investigated via cryo soft X-ray tomography. Both nanoparticles were found to be endocytosed predominantly via macropinocytosis, and most nanoparticles became localized to endosomes, multivesicular bodies and lysosomes. Despite these similarities in trafficking, there were also key differences. Some dPGS-np were found in lipid droplets but no PEI nanoparticles were found in this compartment. At a concentration of 0.13 nM, PEI-np were observed to induce extensive rupture of lysosomes, leading to significant levels of cytoplasmic escape and nuclear entry. In contrast, no evidence for lysosomal rupture with dPGS-np was detected, and concomitantly very low levels of cytoplasmic escape and no nuclear entry were found. Interestingly, when the PEI-np concentration was reduced by ten-fold, a switch in the endocytosis pathway from macropinocytosis to a putative caveolae-mediated endocytosis was observed. Importantly, under these conditions, PEI nanoparticles no longer induced lysosomal rupture. This lack of lysosomal rupture at the lower concentration was correlated with reduced cellular damage, and so has important implications for use of PEI in gene delivery. Most surprisingly, both nanoparticle types were found to induce similar global cytoplasmic alterations in the cells. These cytoplasmic alterations could reflect important physiological changes, but further work is required to determine this. Our observations suggest that the behavior of biologically relevant nanoparticles might become more predictable in the future by further application of systematic studies.
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Qsymah, Ansam. "In-situ X-ray computed tomography tests and numerical modelling of ultra high performance fibre reinforced concrete." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/insitu-xray-computed-tomography-tests-and-numerical-modelling-of-ultra-high-performance-fibre-reinforced-concrete(7c27ef36-afc8-4ea7-8c72-7d92eba924f9).html.
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Ultra high performance fibre reinforced concrete (UHPFRC) is a relatively new fibre reinforced cementitious composite and has become very popular in construction applications. Extensive experimental studies have been conducted, demonstrating its superior properties such as much higher strength, ductility and durability than conventional fibre reinforced concrete (FRC) and high performance concrete. However, the material's damage and fracture mechanisms at meso/micro scales are not well understood, limiting its wider applications considerably. This study aims at an in-depth understanding of the damage and fracture mechanisms of UHPFRC, combining microscale in-situ X-ray computed tomography (µXCT) experiments and mesoscale image-based numerical modelling. Firstly, in-situ µXCT tests of small-sized UHPFRC specimens under wedge splitting loading were carried out, probably for the first time in the world, using an in-house designed loading rig. With a voxel resolution of 16.9µm, the complicated fracture mechanisms are clearly visualised and characterised using both 2D images and 3D volumes at progressive loading stages, such as initiating of micro-cracks, arresting of cracks by fibres, bending and pulling out of fibres and spalling of mortar at the exit points of inclined fibres. Secondly, based on the statistics of pores in the µXCT images obtained for a 20mm cube specimen, an efficient two-scale analytical-numerical homogenisation method was developed to predict the effective elastic properties of the UHPFRC. The large number of small pores were first homogenised at microscale with sand and cement paste, using elastic moduli from micro-indentation tests. 3D mesoscale finite element models were built at the second scale by direct conversion of the µXCT images, with fibres and large pores were faithfully represented. The effects of the volume fraction and the orientation of steel fibres on the elastic modulus were investigated, indicating that this method can be used to optimise the material micro-structure. Thirdly, 3D mesoscale finite element models were built for the specimen used in the in-situ µXCT wedge splitting test, with embedded fibre elements directly converted from the µXCT images. The fracture behaviour in the mortar was simulated by the damage plasticity model available in ABAQUS. Finally, 2D mesoscale finite element models were developed to simulate the fracture behaviour of UHPFRC using cohesive interface elements to simulate cracks in the mortar, and randomly distributed two-noded 1D fibres and connector elements to simulate the pull-out behaviour of fibres. This approach offers a link between the fibres pull-out behaviour and the response of the whole composite at the macroscale, thus it can be used to conduct parametric studies to optimise the material properties.
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Nchari, Luanga Nforba. "Molecular mechanisms during amplification of chirality in organometallic systems : in situ studies by X-ray absorption spectroscopy." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/molecular-mechanisms-during-amplification-of-chirality-in-organometallic-systemsin-situ-studies-by-xray-absorption-spectroscopy(2eefeb4a-bde2-402d-b8a5-decc84ce63e1).html.
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The alkylation of pyrimidyl aldehyde by diisopropylzinc has received immense attention over the last decade. This is mainly because the reaction which was discovered by Soai and coworkers is capable of achieving a homochiral product from an essentially achiral precursor. The strong amplification of the enantiomeric excess occurs because of a transition state complex which is responsible for autocatalysis. Clarifying the structural nature of the organometallic species involved in the reaction is vital for understanding the mechanism of the chiral amplification process. Known mechanistic details are patchy and based on studies that address molecular level details by NMR, computational chemistry, calorimetric and kinetic studies. The studies reported in this thesis for the first time directly addressed the nature of the intermediate by structural analysis with X-ray Absorption Fine Structure (XAFS) Spectroscopy at the Zn K-edge. These measurements provide bond distances, local coordination numbers and the geometry of ligands in the local environment around the Zn centres. First, the molecular level origin of the solvent dependencies in the asymmetric amplification by the Soai process is elucidated. A rationale for the behaviour of dialkylzinc compounds in polar and non-polar solvents is reported. Structural causes for often observed chirality depletion in polar solvents are elucidated. Further studies then examined the nature of the products formed by the reaction of various chiral ligands and dialkylzinc compounds. Different chiral ligands are examined and the complex structure was determined.Finally, first results of in situ studies of the reaction progress in continuous flow channel cells are reported.
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Redtzer, Isabel, and Amanda Krohn. "The Effects of Fine-tuning Depth on a Pre-trained AlexNet Architecture Applied to Chest Xrays." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302527.
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There is a lack of radiologists in the world and due to the ongoing Covid- 19 pandemic, there is a greater need than usual to be able to diagnose chest x-rays. To be able to counteract this issue and to help create a tool for radiologists to aid in the diagnostic process, a Convolutional Neural Network (CNN) can be used. This thesis used a pre-trained AlexNet architecture and fine-tuning to teach the network to diagnose lung diseases from chest x-rays. This thesis aimed to determine what level of fine-tuning is needed to obtain the best model possible, in terms of accuracy, sensitivity and specificity. The network was split into five different blocks which resulted in five different fine- tuning depths. All the models yielded very good results; however, the model did not learn the intended features. The models used a type of shortcut learning to learn the image origin rather than differences in the lung. Due to this the research question of this thesis remains open.I dagens samhälle finns det en brist på radiologer och på grund av den pågående Covid-19 pandemin existerar ett större behov än vanligt att diagnostisera lungröntgenbilder. För att kunna motverka detta problem och skapa ett hjälpmedel för radiologer kan ett Convolutional Neural Network (CNN) användas. Denna rapport använder sig av av en förtränad version av arkitekturen AlexNet och av tekniken finjustering för att kunna lära modellen att diagnostisera lungröntgenbilderna. Syftet med denna rapport är att se vilket djup av finjustering som är effektivast när man tränar ett CNN för att få de högsta möjliga resultatet i noggrannhet, specificitet och känslighet. Arkitekturen delades upp i fem olika block som resulterade i 5 olika finjusteringsdjup. Alla tränade modeller resulterade i väldigt bra resultat, dock lärde sig modellen inte att avläsa de avsedda egenskaperna. Modellerna använde sig utav en typ av genvägsinlärning för att för att lära sig var bilderna härstammar från, istället för skillnaderna på lungorna. På grund av detta var det inte möjligt att besvara frågeställningen.
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Nervo, Laura. "Characterisation of the deformation mechanisms in HCP metals by combined use of X-ray imaging and diffraction techniques." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-the-deformation-mechanisms-in-hcp-metals-by-combined-use-of-xray-imaging-and-diffraction-techniques(50fe7be6-4fbf-48e3-86de-942589bb000d).html.
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We envisage a fundamental study of the physical mechanisms (dislocation slip versus deformation twinning) involved in plastic deformation of hexagonal close-packed (HCP) metals like titanium and magnesium. A novel combination of X-ray imaging and diffraction techniques, termed X-ray diffraction contrast tomography (DCT), will be used to investigate details of the deformation process in the bulk of polycrystalline specimen. DCT provides access to the position, 3D shape, (average) orientation and elastic strain tensor of grains in polycrystalline sample volumes containing up to 1000 grains and more. Ultimately, an extension of the X-ray DCT technique is associated with a section topography methodology on the same instrument. This combination enables the measurement of local orientation and elastic strain tensors inside selected bulk grains. A very preliminary study of this approach is carried out on a magnesium alloy, underlying the current limitations and possible improvements of such approach. In this thesis, the data acquisition and analysis procedures required for this type of combined characterisation approach have been developed. The work is supported by the use of neutron diffraction, for an in-situ loading experiments, and two-dimensional electron backscatter diffraction (EBSD), for the initial microstructure of the materials and cross-validation of the results obtained with the X-ray DCT technique.
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Rosenberg, Robin, and Erik Palmgren. "Mobilforensiska verktyg : Kontaminering i fokus." Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-26700.
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Den stigande populariteten av mobila enheter har inte bara lett till en smidigarevardag med snabb tillgang till e-post och sociala medier utan aven blivit ett allt mervanligt instrument anvant vid kriminella handlingar. Detta har medfort ett behov attkunna undersoka dessa enheter pa ett sakert satt utan att riskera att bevis blirkontaminerade. Det har arbetet har undersokt de mobilforensiska verktyg somanvands av Polisen och deras tillvagagangssatt vid utredning. Genom att anvanda ossutav Polisens tillvagagangssatt och deras verktyg sa har vi utfort experiment ochintervjuer for att undersoka om data forandras vid utvinning. Experimenten pavisaratt data forandras vid utvinning med ett givet verktyg medans intervjuerna visarskiftande asikter bland Poliser och utvecklare gallande kontaminering.Resultatet fran experimentet visade oss att verktyget UFED raderat bevisfiler frananvandardatan pa en enhet under utvinning. Polisens nonchalans gallandekontaminering bor uppmarksammas da en av deras anvanda verktyg visade ettresultat som kan ha en avgorande roll vid utredning.The rising popularity of mobile devices has not only led to a smoother way of livingwith quick access to email and social media, but has also become an increasinglycommon instrument used in criminal activity. This has led to a need to investigatethese devices safely without risking the integrity of the evidence. This paper hasexamined the mobile forensic tools used by the Swedish Police and their procedureused in investigations. By following the same procedures and using the same tools,we have conducted experiments and interviews to investigate if data changes duringthe extraction. The experiments demonstrate that the data changes duringextraction of a given tool, while the interviews shows diverse opinions among thePolice and developers behind these tools regarding contamination. The results fromthe experiments showed us that the tool UFED erased evidence files from theuserdata on a device during extraction. The Police negligence regardingcontamination should be attended to, since one of their used tools showed resultsthat could have had a critical impact in an investigation.
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Gill, Yasir Q. "Preparation and characterization of polyethylene based nanocomposites for potential applications in packaging." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18052.
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The objective of my work was to develop HDPE clay nanocomposites for packaging with superior barrier (gas and water) properties by economical processing technique. This work also represents a comparative study of thermoplastic nanocomposites for packaging based on linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon12. In this study properties and processing of a series of linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon 12 nanocomposites based on Na-MMT clay and two different aspect ratio grades of kaolinite clay are discussed.
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Blackmore, Paul David. "Degradation of polymeric outdoor high voltage insulation : surface discharge phenomena and condition assessment techniques." Thesis, Queensland University of Technology, 1997.
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Laponogov, Ivan. "X-ray and NMR spectroscopy applied to the structural analysis of S. pneumoniae ParC and human cardiac MLP protein." Thesis, King's College London (University of London), 2007. https://kclpure.kcl.ac.uk/portal/en/theses/xray-and-nmr-spectroscopy-applied-to-the-structural-analysis-of-s-pneumoniae-parc-and-human-cardiac-mlp-protein(a0bf705f-c64b-4a88-9abb-23900e08e33e).html.
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