State-of-the-art reconstruction algorithms for medical helical cone-beam Computed Tomography (CT) are of type non-exact Filtered Backprojection (FBP). They are attractive because of their simplicity and low computational cost, but they produce sub-optimal images with respect to artifacts, resolution, and noise. This thesis deals with possibilities to improve the image quality by means of iterative techniques. The first algorithm, Regularized Iterative Weighted Filtered Backprojection (RIWFBP), is an iterative algorithm employing the non-exact Weighted FilteredBackprojection (WFBP) algorithm [Stierstorfer et al., Phys. Med. Biol. 49, 2209-2218, 2004] in the update step. We have measured and compared artifact reduction as well as resolution and noise properties for RIWFBP and WFBP. The results show that artifacts originating in the non-exactness of the WFBP algorithm are suppressed within five iterations without notable degradation in terms of resolution versus noise. Our experiments also indicate that the number of required iterations can be reduced by employing a technique known as ordered subsets. A small modification of RIWFBP leads to a new algorithm, the Weighted Least Squares Iterative Filtered Backprojection (WLS-IFBP). This algorithm has a slightly lower rate of convergence than RIWFBP, but in return it has the attractive property of converging to a solution of a certain least squares minimization problem. Hereby, theory and algorithms from optimization theory become applicable. Besides linear regularization, we have examined edge-preserving non-linear regularization.In this case, resolution becomes contrast dependent, a fact that can be utilized for improving high contrast resolution without degrading the signal-to-noise ratio in low contrast regions. Resolution measurements at different contrast levels and anthropomorphic phantom studies confirm this property. Furthermore, an even morepronounced suppression of artifacts is observed. Iterative reconstruction opens for more realistic modeling of the input data acquisition process than what is possible with FBP. We have examined the possibility to improve the forward projection model by (i) multiple ray models, and (ii) calculating strip integrals instead of line integrals. In both cases, for linearregularization, the experiments indicate a trade off: the resolution is improved atthe price of increased noise levels. With non-linear regularization on the other hand, the degraded signal-to-noise ratio in low contrast regions can be avoided. Huge input data sizes make experiments on real medical CT data very demanding. To alleviate this problem, we have implemented the most time consuming parts of the algorithms on a Graphics Processing Unit (GPU). These implementations are described in some detail, and some specific problems regarding parallelism and memory access are discussed.

Dans ces travaux de thèse, nous avons étudié les propriétés dynamiques et spectrales d’une diode laser puissante à 980 nm qui est soumise à un retour optique provenant d’un réseau de Bragg fibré (FBG). Dans cette configuration, le FBG est un élément clé de la thèse d’une part il permet de former une cavité externe par réflexion comme un miroir et d’autre part il est un filtre qui fournit un retour optique sélectif en fréquence (FOF : Filtered Optical Feedback) aux alentours de 980 nm. Nous nous sommes intéressé à étudier cette configuration FOF dans le cadre d’un projet de collaboration entre la société 3S Photonics Group et le Laboratoire de Physique des Lasers. Il s’agit plus particulièrement d’étudier expérimentalement les séries temporelles par un oscilloscope, les spectres RF par un analyseur de spectre RF et les spectres optiques par un analyseur de spectre optique et par un interféromètre Fabry-Perot, afin d’observer, identifier et comprendre ses comportements dynamiques, notamment fluctuations basses fréquences (LFF). Ce système laser FOF est très peu étudié et ces travaux de thèse permettront de nouvelles connaissances techniques ou scientifiques dans un domaine d’application relativement récent, notamment pour l’application dans les systèmes EDFA (Erbium Doped Fiber Amplifier). / In this thesis, we have studied spectrums and the dynamics properties of a high-powerlaser diode emitting at 980 subject to optical feedback via a fibre Bragg grating (FBG). In such a configuration, FBG is a key element of this work because it establishes an ex-ternal cavity with a reflection like a mirror on one hand and it is a filter which provides frequency selective optical feedback (FOF : Filtered Optical Feedback) at around 980 nm on the other hand. We are interested in investigating this FOF configuration for a project in a collaboration between 3S Photonics Group and the Laboratoire de Physique des Lasers.In order to observe, identify and understand its dynamical behaviours, especially low frequency fluctuations (LFF), the experimental studies have been undertaken particularly with time series from an oscilloscope, RF spectra from an RF spectrum analyser and optical spectra from an optical spectrum analyser and Fabry-Perot interferometer. Onlyfew studies have been done with this FOF laser system and our thesis work may allow new technical and scientific understanding for recent application, particularly application to Erbium-doped fibre amplifier.

Devido à relevância de filmes finos, as técnicas que são utilizadas para produzi-los e também para caracteriza-los tem se tornado importante. Neste contexto, foram analisados filmes finos de até 100 nm, de duas ligas metálicas (cromel e alumel), obtidos a partir da deposição por plasma de Arco Catódico Filtrado em Vácuo (Filtered Cathodic Vacuum Arc - FCVA). O objetivo deste projeto foi avaliar a similaridade em composição elementar entre os materiais utilizados para deposição, que operam como cátodos, e os filmes finos depositados, a partir de medições obtidas pela técnica de microanálise quantitativa Energy Dispersive Spectroscopy (EDS). Para comparação entre resultados e apreciação de compatibilidade, foi realizada avaliação estatística considerando o Teste t, no qual a estatística do teste é dada pela Distribuição t de Student, adotando nível de significância de 5%. Os valores obtidos por EDS Quantitativo para os cátodos foram de (em wt%) (90,3 ± 0,5)% de Ni e (9,72 ± 0,19)% de Cr para o cromel e (95,1 ± 0,8)% de Ni, (2,02 ± 0,14)% de Mn, (1,65 ± 0,04)% de Si e (1,15 ± 0,05)% de Al para o alumel. Já para os filmes finos, foram de (90,2 ± 0,5)% de Ni e (9,8 ± 0,5)% de Cr para o cromel e (95,2 ± 0,4)% de Ni, (2,8 ± 0,4)% de Mn, (0,77 ± 0,17)% de Si e (1,08 ± 0,09)% de Al para o Alumel, ambos apresentando compatibilidade com as medidas por Rutherford Backscattering Spectrometry (RBS) - técnica comumente utilizada para este tipo de espécime. Verificou-se que a composição elementar do filme fino de cromel não apresentou diferença significativa com o cátodo da mesma liga. Entretanto, para o filme fino de alumel, houve evidências de diferença significativa com relação ao cátodo, apontada pelo elemento silício. / Due the relevance of thin films, the techniques used to produce and also to characterize them has become important. In this context, it was analyzed thin films up to 100 nm of two alloys (Chromel and Alumel) obtained by plasma deposition using Filtered Cathodic Vacuum Arc (FCVA). The objective of this project was to evaluate the similarity in elemental concentration of the materials used for deposition, which act as cathodes, and the deposited thin films, through measurements obtained by quantitative microanalysis technique Energy Dispersive Spectroscopy (EDS). In order to compare results and compatibility assessment was performed statistical analysis considering the t-test in which the test statistic is given by the Student\'s t - distribution, adopting a significance level of 5%. The values obtained by Quantitative EDS for the cathodes were (in wt%) (90.3 ± 0.5)% of Ni and (9.72 ± 0.19)% of Cr for the Chromel and (95.1 ± 0.8)% of Ni, (2.02 ± 0.14)% of Mn, (1.65 ± 0.04)% of Si and (1.15 ± 0.05)% of Al for the Alumel. As for the thin films, they were (90.2 ± 0.5)% of Ni and (9.8 ± 0.5)% of Cr for the Chromel and (95.2 ± 0.4)% of Ni, (2.8 ± 0.4)% of Mn, (0.77 ± 0.17)% of Si and (1.08 ± 0.09)% for Al Alumel, both featuring compatibility with the measures by Rutherford Backscattering Spectrometry (RBS) - technique commonly used for this type of specimen. It was verified that the elemental concentration of the thin film of Chromel presented no significant difference with the cathode of the same alloy. However, for the Alumel thin film, there was evidence of a significant difference with respect to the cathode, appointed by element Silicon.

Made available in DSpace on 2017-07-10T17:37:11Z (GMT). No. of bitstreams: 1 Vanessa_Felix_Vaz_Stefanello.pdf: 1562857 bytes, checksum: 9dcf0ad6ea4c077c5df3464b1076ce22 (MD5) Previous issue date: 2015-08-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of the work was to evaluate the action of Trichoderma spp. and its filtered as biocontrol agent of anthracnose and resistance inducer in beans. Were conducted two experiments in vitro, where were made a germination test of Colletotrichum lindemuthianum conidium after the treatment with Trichoderma spp. filtered, and the direct confrontation test of 21 cultures isolated from Trichoderma spp. agains this pathogen were also conducted two experiments in vivo: on the first imposed treatments in base of Trichoderma in the beans inoculated via seed; on the second experiment the treatments aplication were made through foliar spray of filtered medium of Trichoderma spp. For the experiments in vivo were realized sheets collects for biochemical analysis, in which there were two collects for the experimente that were treated via seed (15 days after the foliar emergency and three days after the pathogen inoculation). Whereas for the experiment which the treatments were via foliar spray of filtered medium of Trichoderma, were realized three collectings, (the first without the treatment aplication, the second three days after the filtered pulverization and the third collect realized three days after the pathogen inoculation). Were determined the polyphenoloxidase activity (PFO), peroxidase (POX) and phenylalanine ammonia lyase (FAL), and were evaluated the total protein content, total phenols, lignin and the severity of anthracnose after treatments in base of Trichoderma for both experiments. For the germination test of C. lindemuthianum, conidium the filtered from the isolated TM1, TI1 and TOD1 reduced the germination in, 33%, 38% and 61% respectivily. In direct confrontation were realized that the isolated inhibited pathogen growth. For the PFO activity in via seed treatment, the isolated TLB12, TOD1 and TOD2B caused an increase thereof after challenge with the pathogen, while the treatment via foliar spray of Trichoderma filtered were not observed significant difference. The POX activity in beans treated at sowing, for the time 1 weren‟t observed difference between the treatments, whereas in the time 2 some isolated tended to suppress the enzymatic activity, while for plants treated via foliar pulverization notes the tendency to enzymatic suppression of POX in time 2 caused by some filtered in relation to the positive control. The FAL enzymatic activity and the total soluble protein contents both in the aplication of the treatments via seed and via foliar pulverization in beans didn‟t result in significant difference. For the total phenol contents and lignin the treatments in base of Trichoderma via sowing and via foliar pulverization didn‟t promote an icrease of the same in beans. The severity in treated beans presented in general low, making these inaccurate data / O objetivo do trabalho foi avaliar a ação do Trichoderma spp. e seus filtrados como agente de biocontrole da antracnose e indutor de resistência em feijoeiro. Conduziram-se dois experimentos in vitro, onde foi realizado teste de germinação de conídios de Colletotrichum lindemuthianum após tratamento com filtrados de Trichoderma spp., e o teste de confronto direto de culturas de 21 isolados de Trichoderma spp. frente a esse patógeno também conduziu-se dois experimentos in vivo: no primeiro se impôs os tratamentos a base de Trichoderma no feijoeiro inoculado via semente; já no segundo experimento a aplicação dos tratamentos se deu por meio de pulverização foliar de filtrados de Trichoderma spp. Para os experimentos in vivo realizaram-se coletas de folhas para análises bioquímicas, no qual houve duas coletas para o experimento cujos tratamentos foram via semente (aos 15 dias após a emergência foliar e três dias após a inoculação do patógeno). Já para o experimento aos quais os tratamentos foram via pulverização foliar de filtrados de Trichoderma, realizaram-se três coletas, (a primeira sem a aplicação do tratamento, a segunda realizada três dias após a pulverização dos filtrados e a terceira coleta realizada três dias após a inoculação do patógeno). Determinou-se a atividade de polifenoloxidase (PFO), peroxidase (POX) e fenilalanina amônia-liase (FAL), e foram avaliados os teores de proteínas totais, fenóis totais, lignina e a severidade da antracnose após os tratamentos a base de Trichoderma para ambos os experimentos. Para o teste de germinação de conídios de C. lindemuthianum, os filtrados dos isolados TM1, TI1 e TOD1 reduziram a germinação em, 33%, 38% e 61% respectivamente. No confronto direto percebeu-se que os isolados inibiram o crescimento do patógeno. Para a atividade de PFO em tratamentos via semente, os isolados TLB12, TOD1 e TOD2B causaram aumento da mesma após o desafio com o patógeno, enquanto que no tratamento via pulverização foliar de filtrados de Trichoderma não foi observada diferença significativa. A atividade de POX em feijoeiro tratado na semeadura, para o tempo 1 não observou-se diferença entre os tratamentos, já no tempo 2 alguns isolados tenderam a suprimir a atividade enzimática, enquanto que para as plantas tratadas via pulverização foliar nota-se tendência de supressão enzimática da POX no tempo 2 ocasionada por alguns filtrados em relação ao controle positivo. A atividade enzimática de FAL e os teores de proteínas solúveis totais tanto na aplicação dos tratamentos via semente quanto via pulverização foliar em feijoeiro não acarretou em diferença significativa. Para os teores de fenóis totais e de lignina os tratamentos a base de Trichoderma via semeadura e via pulverização foliar não promoveram incremento dos mesmos em feijoeiro. Já a severidade em feijoeiro tratado apresentou-se no geral baixa, tornando estes dados imprecisos

The purpose of this thesis is to examine whether Swedish Equity L/S hedge funds present a lower market risk than the index S&P Europe 350 over our holding period using a GARCH/EGARCH Value-at-Risk model. The sample consists of 96 monthly observa- tions between March 2004 and February 2012. The examination shows that the hedge funds in general hold a lower market risk than the index for the next holding period and al- so present a lower estimated loss if our VaR loss is exceeded. This implies that hedge funds would be a good choice for investors to have in a portfolio to reduce the risk.

This research has successfully developed a multiple fluorescence detection method for high throughput capillary electrophoresis detection using a digitally-modulated light source and a spectrum detection system. A commercial available LCD (liquid crystal device) projector is adoped to replace the spacially-filttered light source (Hg lamp) in a conventional fluorescence microscopy. The LCD projector can be digitally controlled by a computer to create the three primary colors of RGB (red, green, and blue) for fluorescence excitation in the analytes. The emitted light from the fluorescent samples is then collected using a UV-VIS-NIR spectrometer through a ultimode fiber. Delicate optical components, such as filter wheel or acousto-optic filtering system, for filtering different excitation light sources can be excluded with this simple and novel approach. In addition, the desired wavelength for the excitation light can be selected quickly and smoothly without vibration problems come with the mechanical optical components. Three fluorescent dyes (Atto 647N, Rhodamine B, Fluorescein) with different excitation and emission wavelength has been used to demonstrate the proposed digitally-modulated light source system for high throughput CE system. The optimal operation conditions for obtaining best detection signal-to-noise ratio for different fluorescence dyes are firstly determined. In addition, the current study proposes a mixed-color light (visually in purple) composed of two specific primary lights (red and blue) to simultaneously excite a mixed sample composed of two fluorescent dyes (Atto 647N and FITC). Separation and detection of the mixed fluoresce samples using a single excitation illumination using the proposed digital-modulated CE system is successfully demonstrated. Finally, a single-strand DNA biosample is used to confirmed the proposed system is feasible of adopting in the bio-analytical applications. The technique proposed in this study has shown its potential to be a high throughput CE detection system.

The filtered cathodic vacuum arc (FCVA) technique is a well established deposition method for wear resistant mechanical coatings. More recently, this method has attracted attention for growing ZnO based transparent conducting films. However, the potential of FCVA deposition to prepare ZnO layers for electronic devices is largely unexplored. This thesis addresses the use of FCVA deposition for the fabrication of active ZnO based electronic devices. The structural, electrical and optical characteristics of unintentionally doped ZnO films grown on different sapphire substrates were systematically investigated. The potential of FCVA to grow both polar and non-polar ZnO films was demonstrated. The resulting films showed considerable promise for device applications with properties including high transparency(> 90%), moderate intrinsic carrier concentrations (10¹⁷ - 10¹⁹ cm⁻³), electron mobilities up to 110 cm⁻²/Vs, low surface roughness (< 5 nm) and well-structured photoluminescence. Post-growth annealing in oxygen at temperatures up to 800 C produced significant improvements in the electronic and optical properties of these films, due to the formation of larger grains with lower inter-grain potential barriers. Silver oxide (AgOᵪ ) and iridium oxide (IrOᵪ) Schottky diodes fabricated on annealed FCVA ZnO films showed ideality factors as low as 1.20, barrier heights up to 0.85 eV and high sensitivity to ultraviolet light (up to ̴ 10⁻⁵ at -2 V). Transparent and opaque MESFETs fabricated on these films showed well defined field effect characteristics, channel mobilities up to 70 cm⁻²/Vs and insensitivity to 1 mW/cm⁻² visible light. These devices were further subjected to extensive bias and temperature stress tests. MESFET stability appeared to be strongly dependent on Schottky gate type, bias conditions and ZnO film morphology. Positive bias stress of AgOᵪ gated devices resulted in irreversible damage, that is thought to be due to Ag electromigration across the gate interface. Mapping of the surface potential of the ZnO channel material with Kelvin probe force microscopy suggested a strong relationship between the defect density at grain boundaries and both channel mobility and current stability. Interval growth techniques were found to reduce the density of defects at grain boundaries and produced MESFETs with higher current stability. IrOᵪ gated devices showed superior bias stability and temperature resilience from 25 C-195 C.

In this dissertation, we study semi-stable representations of G(Q(p)) and their mod p-reductions, which is a part of the problem in which we construct deformation spaces whose characteristic 0 closed points are the semi-stable lifts with Hodge-Tate weights (0, 1, 2) of a fixed absolutely irreducible residual representation ρ : G(Q(p)) → GL₃(F(p)). We first classify the isomorphism classes of semi-stable representations of G(Q(p)) with regular Hodge-Tate weights, by classifying admissible filtered (phi,N)-modules with Hodge-Tate weights (0, r, s) for 0 < r < s. We also construct a Galois stable lattice in some irreducible semi-stable representations with Hodge-Tate weights (0, 1, 2), by constructing strongly divisible modules, which is an analogue of Galois stable lattices on the filtered (ɸ, N)-module side. We compute the reductions mod p of the corresponding Galois representations to the strongly divisible modules we have constructed, by computing Breuil modules, which is, roughly speaking, mod p-reduction of strongly divisible modules. We also determine which Breuil modules corresponds to irreducible mod p representations of G(Q(p)).

Auditory processing disorder (APD) is a label that describes a variable set of symptoms that share a common feature of difficulty listening to sounds in the absence of an actual audiological deficit (Moore, 2006). Clinical assessment of APD typically involves a test battery consisting of tests designed to examine the integrity of various auditory processes of the central auditory nervous system. Individuals with APD have difficulty recognising speech when parts of the signal are missing. One category of tests used to assess the extent to which this deficit is associated with reduced performance on the task is the low-pass filtered speech test. The University of Canterbury Adaptive Speech Test-Filtered Words (UCAST-FW) is a computer-based adaptive low-pass filtered speech test developed for the assessment of auditory processing skills in adults and children. Earlier studies with the UCAST-FW (McGaffin, 2007; Sincock, 2008; Heidtke, 2010; Abu-Hijleh, 2011) have produced encouraging results. However, there appear to be a number of confounding factors. The UCAST-FW is testing New Zealand listeners using an Australian recording of American test material. The purpose of the current study was to develop a new four-alternative forced choice test to replace the Northwestern University Children’s Perception of Speech (NU-CHIPS) stimuli the UCAST-FW currently utilises. The new test consists of 98 sets of four test items, (one target item and three foil alternatives) designed to be used in a four-alternative forced choice picture-pointing procedure. Phonemic analysis of the new word list and the NU-CHIPS word lists revealed a similar distribution of phonemes for target words of both word lists. The development of the new word list is described and the clinical applicability is explored.

Classical homological algebra is done in a category of modules beginning with the study of projective and injective modules. This dissertation investigates analogous notions of projectivity and injectivity in a category of filtered modules. This category is similar to one studied by Sjödin, Nǎstǎsescu, and Van Oystaeyen. In particular, projective and injective objects with respect to the restricted class of strict morphisms are defined and characterized. Additionally, an analogue to the injective envelope is discussed with examples showing how this differs from the usual notion of an injective envelope.