Dissertations / Theses on the topic 'Squint'

This thesis examines a new algorithm, to be called secondary range compression (SRC), for significantly improving the range resolution of the range/Doppler synthetic aperture radar (SAR) processing algorithm when the radar antenna is significantly squinted away from the zero Doppler direction. The algorithm was recently introduced by Jin and Wu [13] for application to the SEASAT SAR sensor. Significant extensions of their algorithm and models are presented. First the model of range broadening in the basic range/Doppler algorithm is extended by using a more general form for the range compressed profile. A mathematical theory is developed to examine more closely the approximations involved in both basic range/Doppler processing and SRC and to explore alternate SRC implementations. The theory is used to derive the SRC algorithm as a matched filter directly from the point target response model rather from the simplified range compressed response used by Jin and Wu. Two new discrete implementations (azimuth SRC and range SRC) are developed for both single-look and multilook processing. In addition two new alternate methods of multilook SRC are presented : fixed SRC and look-dependent SRC. The sensitivity of the SRC algorithms to parameter errors is investigated. Extensive simulations are developed to quantify the image quality produced by each algorithm for a variety of processing parameters. The simulation results with nominal RADARSAT parameters show that the SRC algorithms can significantly extend the range of squint angles which can be processed with the range/Doppler type of algorithm.<br>Applied Science, Faculty of<br>Electrical and Computer Engineering, Department of<br>Graduate

L’estrabisme és una patologia comú dintre de l’Oftalmologia que afecta als músculs extraoculares del globus ocular. Es caracteritza per la pèrdua espontània i permanent del paral·lelisme dels eixos visuals oculars. Pot ser unilateral o bilateral sense heterotròpia. A la pràctica clínica no sempre s’objectiva que un múscul hipofuncionant sigui atròfic, o que un múscul hiperfuncionant tingui augmentada la seva grandària, ja sigui per hipertrofia de les seves fibres o per augment del teixit connectiu Es por aquest motiu que l’objectiu d’aquesta investigació va ser estudiar si existia una correlació entre l’estructura i la funció dels músculs implicats als diferents tipus d’estrabisme descrivint la morfologia microscòpica de músculs extraoculares sans i de músculs procedents de pacients amb estrabismes primaris i secundaris, respecte al teixit muscular, al teixit connectiu i a la vascularització. Per allò es van analitzar i comparar les característiques microscòpiques dels músculs extraoculares d’un grup control i d’un grup de músculs amb patologia, mitjançant tècniques histològiques i histoquímiques. Com a grup control en van utilitzar 5 òrbites procedents de cossos donats a la ciència, de genero masculí amb un rang d’edat de 35 a 45 anys, que van ser congelades a -21ºC amb menys de 24h post-mortem per posteriorment, al moment de la dissecció, procedir a la descongelació i resecció en fresc. En cap cas hi havia un antecedent conegut de patologia ocular. A més, es va realitzar la dissecció de 20 òrbites procedents de cossos humans adults, d’entre 40 i 60 anys, amb l’objectiu d’estudiar i ponderar cada múscul extraocular mitjançant la mesura de la longitud, de l’amplada i del seu punt d’inserció, per poder definir la zona de miectomia en mostra cadavèrica i biòpsia clínica. Una vegada aïllat cadascun dels músculs es va procedir a la seva fixació en solució tamponada de formaldehid al 10% (pH 7,4) i posterior inclusió en parafina. D’acord amb el protocol estereològic, es van realitzar talls seriats de 5µm de gruix, que van ser muntats i tenyits amb hematoxilina-eosina, àcid periòdic de Shiff i Van Gieson. Es van analitzar un total de 125 camps d’estudi per múscul i per cada tècnica de tinció. Per el grup amb patologia es van prendre biòpsies musculars de 20 pacients diagnosticats d’estrabisme amb indicació quirúrgica, considerant 5 pacients per a cada patologia. Les patologies van ser: Parèsia del IV nervi cranial, Exotropia intermitent, Endotropia acomodativa i Endotropia Congènita o infantil. Totes les cirurgies van ser fetes pel mateix cirurgià oftalmòleg. L’anàlisi estadístic va consistir en un anàlisis descriptiu de les distintes variables i l’anàlisi de les variables en funció dels grups control i patològic, obtenint coeficients de relació entre ells. Entre els resultats es va obtenir que existia una correlació entre les alteracions clínic-funcionals observades en els músculs extraoculares dels pacients amb diferents tipus d’estrabisme i els canvis a nivell histològic del teixit muscular i connectiu; a més, en músculs extraoculares sense patologia és possible establir una correlació de l’existència de músculs equivalents i aparellats en la seva funció, demostrant que histològicament són semblants en els paràmetres estudiats. També s’aprecien diferencies estadísticament significatives entre músculs del grup control i del grup de músculs patològics, tant en densitat de volum muscular, de teixit connectiu i de vasos sanguinis, així com en el número de fibres musculars per àrea determinada, observant-se canvis qualitatius i quantitatius que alteren la distribució dels paràmetres de normalitat.<br>El Estrabismo es una patología común dentro de la Oftalmología que afecta a los músculos extraoculares del globo ocular. Se caracteriza por la pérdida espontánea y permanente del paralelismo de los ejes visuales oculares. Puede ser unilateral o bilateral sin heterotropía. En la práctica clínica no siempre se objetiva que un músculo hipofuncionante sea atrófico, o que un músculo hiperfuncionante tenga aumentado su tamaño, ya sea por hipertrofia de sus fibras o por aumento del tejido conectivo Es por este motivo que el objetivo de esta investigación fue estudiar si existe una correlación entre la estructura y la función de los músculos implicados en los diferentes tipos de estrabismo describiendo la morfología microscópica de músculos extraoculares sanos y de músculos procedentes de pacientes con estrabismos primarios y secundarios, respecto al tejido muscular, al tejido conectivo y a la vascularización. Para ello se analizaron y compararon las características microscópicas de los músculos extraoculares de un grupo control y un grupo de músculos con patología mediante técnicas histológicas e histoquímicas. Como grupo control se consideraron 5 órbitas procedentes de cadáveres donados a la ciencia de género masculina con un rango de edad entre 35 y 45 años, fueron congeladas a -21ºC con menos de 24 horas post-mortem para luego, al momento de su disección, proceder a su descongelación y resección en fresco. En ninguno de ellos había un antecedente conocido de patología ocular. Además se realizó la disección de 20 órbitas procedentes de cadáveres humanos adultos de edades entre los 40 y los 60 años con el objetivo de observar y ponderar cada músculo extraocular mediante la medición del largo, el ancho y su punto de inserción, para definir la zona de miectomía en muestra cadavérica y biopsia clínica. Una vez aislado cada uno de los músculos se procedió a su fijación en solución tamponada de formaldehído al 10% (pH 7,4), para luego ser incluidos en parafina. De acuerdo al protocolo estereológico, se efectuaron cortes seriados de 5µm de grosor, los cuales fueron montados y teñidos con hematoxilina-eosina, ácido Peryódico de Shiff y Van Gieson. Se analizaron un total de 125 campos de estudio por músculo y por cada técnica de tinción. Para el grupo con presencia de patología se tomaron biopsias musculares en 20 pacientes diagnosticados de estrabismo con indicación quirúrgica considerando 5 pacientes para cada patología. Estas patologías son: Paresia del IV nervio craneal, Exotropía intermitente, Endotropía acomodativa, Endotropía Congénita o infantil. Todas las cirugías fueron realizadas por el mismo cirujano-oftalmólogo. Para el análisis estadístico se usaron análisis descriptivo de las distintas variables y análisis de las variables en función a los grupos control y patológico obteniendo coeficientes de relación entre ellos. Entre los resultados se obtuvo que existe una correlación entre las alteraciones clínico-funcionales observadas en los músculos extraoculares de los pacientes con distintos tipos de estrabismo y los cambios a nivel histológico del tejido muscular y conectivo, además en músculos extraoculares sin patología es posible establecer una correlación sobre la existencia de músculos equivalentes y emparejados en su función, demostrando que histológicamente son semejantes en los parámetros estudiados. Se aprecia diferencias estadísticamente significativas entre músculos del grupo control y del grupo de músculos patológicos, tanto en densidad de volumen muscular, de tejido conectivo y de vasos, así como en el número de fibras musculares por área determinada, observándose cambios cualitativos y cuantitativos que alteran la distribución de los parámetros de normalidad.<br>Strabismus is a common pathology within Ophthalmology that affects the extraocular muscles of the eyeball. It is characterized by the spontaneous and permanent loss of parallelism of the ocular visual axes. It can be unilateral or bilateral without heterotropy. In clinical practice, it is not always observed that an underactive muscle is atrophic, or that a hyperfunctioning muscle has increased in size, either due to hypertrophy of its fibers or due to increased connective tissue For this reason, the objective of this research was to study whether there is a correlation between the structure and function of the muscles involved in the different types of strabismus, describing the microscopic morphology of healthy extraocular muscles and of muscles from patients with primary strabismus and secondary, regarding muscle tissue, connective tissue and vascularization. For this, the microscopic characteristics of the extraocular muscles of a control group and a group of muscles with pathology were analyzed and compared using histological and histochemical techniques. As a control group, 5 orbits from cadavers donated to science of the male gender with an age range between 35 and 45 years were considered, they were frozen at -21ºC with less than 24 hours post-mortem and then, at the time of their dissection, proceed to thawing and resection fresh. In none of them was there a known history of ocular pathology. In addition, 20 orbits were dissected from adult human cadavers aged between 40 and 60 years with the aim of observing and weighing each extraocular muscle by measuring the length, width and its insertion point, to define the area of myectomy in cadaveric sample and clinical biopsy. Once each of the muscles had been isolated, they were fixed in a 10% formaldehyde buffered solution (pH 7.4), to then be included in paraffin. According to the stereological protocol, 5 µm thick serial sections were made, which were mounted and stained with hematoxylin-eosin, Shiff and Van Gieson periodic acid. A total of 125 study fields were analyzed per muscle and for each staining technique. For the group with the presence of pathology, muscle biopsies were taken in 20 patients diagnosed with strabismus with surgical indication, considering 5 patients for each pathology. These pathologies are: paresis of the IV cranial nerve, intermittent exotropia, accommodative esotropia, congenital or infantile esotropia. All surgeries were performed by the same ophthalmologist-surgeon. For the statistical analysis, descriptive analysis of the different variables and analysis of the variables were used according to the control and pathological groups, obtaining relationship coefficients between them. Among the results, it was obtained that there is a correlation between the clinical-functional alterations observed in the extraocular muscles of patients with different types of strabismus and the histological changes of the muscular and connective tissue.In addition, in extraocular muscles without pathology it is possible to establish a correlation on the existence of equivalent and paired muscles in their function, showing that they are histologically similar in the parameters studied. Statistically significant differences are observed between muscles of the control group and the group of pathological muscles, both in density of muscle volume, connective tissue and vessels, as well as in the number of muscle fibers per determined area, observing qualitative and quantitative changes that alter the distribution of the normality parameters.<br>Universitat Autònoma de Barcelona. Programa de Doctorat en Cirurgia i Ciències Morfològiques

This thesis discusses early modern European perceptions of body and soul in association with the increasing stringency of civilized behaviour and state formation in an effort to provide motivation for the increased severity of the witch hunts of that time. Both secondary and primary sources have been used, in particular the contemporary demonologies by such authors as Bodin, and Kramer and Sprenger. The thesis is divided into five chapters, including an Introduction and Conclusion. The body of the thesis focuses on religious, scientific, and secular beliefs (Ch. 2), appearance and characteristics of witches (Ch. 3), and the activities and behaviours/actions of witches, (Ch. 4). This study concentrates on the similarities found across Europe, and, as the majority of witches persecuted were female, my thesis emphasizes women as victims of the witch hunts.

True time delay networks are one of the most critical structures of wideband phased-array antenna systems which are frequently used in self-protection and electronic warfare applications. In order to direct the main beam of a wideband phased-array antenna to the desired direction<br>phase values, which are linearly dependent to frequency, are essential. Due to the phase characteristics of the true-time delay networks, beam squint problems for broadband phased array systems are minimized. In this thesis, different types of true-time delay structures are investigated for wideband phased array applications and a tunable S-band true-time delay network having delay over 1ns with high resolution is developed, designed, fabricated and measured. Lower-cost, smaller occupied area, digital/analog control mechanism and ease of implementation are the other features of the developed network. High delay values with high resolutions for wideband operation are achieved through the combination of several techniques<br>therefore the desired S-band TTD network is constructed with the synthesis of switched-transmission lines, constant-R networks and periodically-loaded transmission lines. Higher delay states are realized by the switched-transmission lines technique, while the method of constant R-network is used for the intermediate delay states. To increase the tuning flexibility, smaller delay states are accomplished by analog-voltage controlled periodically loaded transmission lines. A step-by-step procedure is followed during the design process of the S-band true time delay network. Firstly, each method used in the TTD network is analyzed in detail and developed for PCB implementation and the use of COTS components. Then, the designed structures are verified via linear and EM simulations performed by ADS2011&reg<br>. After that, the effects of production tolerances are examined to optimize each design for S-band operations. Moreover, the designed structures are fabricated by using PCB technology and measured. Finally, a software code is developed in MATLAB to generate the overall cascaded network with the help of measured data.

Erratic and highly variable catches in the South African chokka squid Loligo vulgaris reynaudii fishery, cause socio-economic hardship for the industry and uncertainty for resource managers. Catch forecasting can reduce this problem as it is believed that catch variability is strongly influenced by environmental factors. In this study, data were collected at varying temporal and spatial scales. Data for the hourly time-scale study were collected from 1996-1998, aboard commercial vessels, whilst for the longer time-scales, data were extracted for Kromme Bay (a single fishing area) from existing databases (1991-1998) that were comprised of compulsory catch returns and oceanographic data. The environment-catch relationship for chokka squid on the inshore spawning grounds was then investigated using multiple correlation and regression analysis, analysis of variance, contingency table analysis and cross-correlation statistical techniques. This simple, direct, 'black box' statistical approach was relatively successful in developing a predictive capability. On a short time-scale (hourly), the regression model accounted for 32% of the variability in catch, with turbidity the main determinant (13%). On a daily monthly time-scale, the best prediction model was on a monthly scale, accounting for 40% of the variability in catch. The principal determinant, bottom temperature anomaly (11 %), was found to lag one month forward. Seasonal and diel catch variations induced changes in the relative importance of turbidity, water temperature and wind direction on catches. A strong, positive relationship was found between easterly winds (which cause upwelling) and catch, particularly in summer. Catch rates, however, decreased with an increase in turbidity. The correlation between temperature and catch was generally negative, however, higher catches were associated with a temperature range of 13-18°C. Highest catch rates were associated with easterly winds, zero turbidity conditions and sea surface temperatures from 15.0-16.9°C. Selected case studies (in situ observations) suggested that upwelling and turbidity events act as environmental triggers for the initiation or termination of the spawning process, respectively. A holistic approach is required to improve predictive capability of chokka squid abundance. Although short-term predictability remains essential (i.e. hourly-scale), future research should concentrate on long-term prediction models (e.g., monthly time-scales) involving greater spatial variation, which are the most important for management.

Nous proposons dans cette thèse de caractériser quantitativement la variabilité à différentes échelles au cours de l'embryogenèse. Pour ce faire, nous utilisons une combinaison de modèles mathématiques et de résultats expérimentaux. Dans la première partie, nous utilisons une petite cohorte d'oursins digitaux pour construire une représentation prototypique du lignage cellulaire, reliant les caractéristiques des cellules individuelles avec les dynamiques à l'échelle de l'embryon tout entier. Ce modèle probabiliste multi-niveau et empirique repose sur les symétries des embryons et sur les identités cellulaires; cela permet d'identifier un niveau de granularité générique pour observer les distributions de caractéristiques cellulaires individuelles. Le prototype est défini comme le barycentre de la cohorte dans la variété statistique correspondante. Parmi plusieurs résultats, nous montrons que la variabilité intra-individuelle est impliquée dans la reproductibilité du développement embryonnaire. Dans la seconde partie, nous considérons les mécanismes sources de variabilité au cours du développement et leurs relations à l'évolution. En nous appuyant sur des résultats expérimentaux montrant une pénétrance incomplète et une expressivité variable de phénotype dans une lignée mutante du poisson zèbre, nous proposons une clarification des différents niveaux de variabilité biologique reposant sur une analogie formelle avec le cadre mathématique de la mécanique quantique. Nous trouvons notamment une analogie formelle entre l'intrication quantique et le schéma Mendélien de transmission héréditaire. Dans la troisième partie, nous étudions l'organisation biologique et ses relations aux trajectoires développementales. En adaptant les outils de la topologie algébrique, nous caractérisons des invariants du réseaux de contacts cellulaires extrait d'images de microscopie confocale d'épithéliums de différentes espèces et de différents fonds génétiques. En particulier, nous montrons l'influence des histoires individuelles sur la distribution spatiales des cellules dans un tissu épithélial<br>We propose in this thesis to characterize variability quantitatively at various scales during embryogenesis. We use a combination of mathematical models and experimental results. In the first part, we use a small cohort of digital sea urchin embryos to construct a prototypical representation of the cell lineage, which relates individual cell features with embryo-level dynamics. This multi-level data-driven probabilistic model relies on symmetries of the embryo and known cell types, which provide a generic coarse-grained level of observation for distributions of individual cell features. The prototype is defined as the centroid of the cohort in the corresponding statistical manifold. Among several results, we show that intra-individual variability is involved in the reproducibility of the developmental process. In the second part, we consider the mechanisms sources of variability during development and their relations to evolution. Building on experimental results showing variable phenotypic expression and incomplete penetrance in a zebrafish mutant line, we propose a clarification of the various levels of biological variability using a formal analogy with quantum mechanics mathematical framework. Surprisingly, we find a formal analogy between quantum entanglement and Mendel’s idealized scheme of inheritance. In the third part, we study biological organization and its relations to developmental paths. By adapting the tools of algebraic topology, we compute invariants of the network of cellular contacts extracted from confocal microscopy images of epithelia from different species and genetic backgrounds. In particular, we show the influence of individual histories on the spatial distribution of cells in epithelial tissues

Les systèmes de télécommunication de type radio logicielle ou "Software Defined Radio" (SDR) exploitent les techniques numériques qui permettent leur reconfigurabilité, que ce soit en termes de fréquence, de bande passante utilisée, ou de méthode de modulation/démodulation des signaux. Ceux-ci nécessitent des architectures permettant la numérisation des signaux analogiques RF à des fréquences d'échantillonnage de plusieurs dizaines de GHz, avec des bandes passantes de plusieurs dizaines de MHz et une résolution supérieure à 10 bits. Ces objectifs sont très difficiles à atteindre avec la technologie actuelle des semi-conducteurs. La logique à quantum de flux magnétique ou logique "Rapid Single-Flux-Quantum" (RSFQ) se présente comme un candidat séduisant pour la conception de tels systèmes.En effet, celle-ci permet d'atteindre des fréquences d'horloge de plusieurs centaines de GHz pour une consommation d'environ 100 nW par porte logique. Le travail de thèse a consisté en la réalisation d'un prototype de chaîne de réception RF analogique-numérique en technologie RSFQ. L'étude et la conception des différents blocs la constituant comme le convertisseur analogique-numérique et ceux de traitement du signal numérisé en aval a été réalisée. Les premiers résultats expérimentaux confirment la fonctionnalité des cellules RSFQ de base constituant le bloc de traitement numérique. La difficulté à faire fonctionner expérimentalement les blocs plus complexes a soulevé la question de la sensibilité des cellules RSFQ aux perturbations magnétiques extérieures. Cette problématique a été étudiée sur des circuits RSFQ simples et a permis de conclure qu'un champ magnétique externe de quelques dizaines de $mu$T était suffisant pour dégrader le fonctionnement de tels circuits. Une solution de prise en compte des effets d'un champ magnétique externe dans le simulateur utilisé a été développée pour anticiper ces problèmes dès la conception. Celle-ci a été validée expérimentalement avec un Superconducting Quantum Interference Device (SQUID)<br>Information and telecommunication Software Defined Radio (SDR) systems are mainly based on digital techniques, which enable to easily reconfigure them, in terms of frequency, bandwidth and modulation techniques. They can process the information entirely in a digital way, by directly sampling the input RF signal and require analog-to-digital converters with strong performances. Indeed, SDR systems have to work at sampling frequencies of several tens of GHz, with large bandwidths and a suitable resolution ($geq$ 10 bits). Rapid-Single-Flux-Quantum logic (RSFQ) seems to be an interesting solution to design such systems. This technology can reach clock frequencies of several hundreds of GHz with a power consumption of only 100 nW per logic gate. This work deals with the design of a superconductive RF front-end receiver based on RSFQ technology. The study of the different parts of the chain was done, such as the analog-to-digital converter and the signal processing part of the digital signal. Experimental results confirm that all simple RSFQ cells work with correct margins. Complex circuits work with more difficulty, raising the issue of the sensitivity of RSFQ cells to external magnetic disturbances. This point was studied on basic RSFQ cicuits and shows that a magnetic field of about 10 $mu$T is sufficient to spoil the operation of the circuit. Moreover, a solution to take into account magnetic effects in the simulation of the circuits was developed and experimentally validated on a Superconducting Quantum Interference Device (SQUID)

Undoubtedly, spectrum scarcity constitutes the main bottleneck of current wireless networks. It is therefore imperative to move beyond the sub-6 GHz band in order to overcome this limitation. Toward this direction, terahertz (THz) communication is deemed a promising solution for future wireless systems owing to the abundant spectrum resources at these frequencies. Despite the prospect of terabit- per-second wireless links, THz signals suffer from severe propagation losses, which can undermine the communication range and performance of THz systems. In this dissertation, we tackle this challenge by putting forward two key physical layer technologies, namely massive multiple-input multiple-output (MIMO) and intelligent reflecting surfaces (IRSs). More particularly, this dissertation consists of two parts. In the first part, we thoroughly study the spatialwideband effect in THz massive MIMO. We commence by demonstrating that conventional narrowband beamforming/combining leads to substantial performance degradation for large antenna arrays and high transmission bandwidths. With this in mind, we propose a wideband array architecture based on true-timedelay and virtual subarrays. For the channel estimation problem, we introduce a wideband dictionary along with a novel variant of the orthogonal matching pursuit algorithm. Numerical simulations are provided showcasing that the proposed design enables: i) nearly squint-free beamforming/combining with a small number of true-time-delay elements; and ii) accurate channel acquisition with reduced pilot overhead even in the low signal-to-noise-ratio regime. In the second part, we focus on the fundamentals of IRSs at THz frequencies. Specifically, we show that an IRS has the potential to improve the energy efficiency of THz MIMO, when it is placed close to one of the link ends. As a result, electrically large IRSs are expected to operate in the radiating near-field zone, where the spherical wavefront of the emitted electromagnetic (EM) waves cannot be neglected. To this end, we introduce a spherical wave channel model by leveraging EM theory, which includes far-field as special case. Furthermore, we discuss the importance of using EM principles to characterize the path loss of IRS-aided links, as simplistic models may wrongly estimate the link budget and actual system performance. Our analysis reveals that: i) conventional far-field beamforming is highly suboptimal in terms of power gain, and hence beamfocusing is the optimal mode of operation for THz IRSs; and ii) frequencydependent beamfocusing is required in wideband THz transmissions, as beam squint can substantially reduce the achievable data rate.

This thesis describes the chemical investigations of several ascidian species collected from the Great Barrier Reef, Queensland, Australia. The thesis is divided into two separate components, Part A focuses on the isolation and structure elucidation of 11 previously undescribed ascidian metabolites. All structures were assigned using a combination of spectroscopic and/or chemical methods. Part B relates to the isolation and chemical conversion of a natural product to a combinatorial template. The natural product template was subsequently used in the generation of a solution-phase combinatorial chemistry library. A further two combinatorial libraries were generated from a synthesised model compound that was related to the natural product template. Part A. Investigation of Aplidium longithorax collected from the Swains Reefs resulted in the isolation of two new para-substituted cyclofarnesylated quinone derived compounds, longithorones J (30) and K (31). The former compound had its absolute stereochemistry determined by the advanced Mosher method. From an Aplidium longithorax collected from Heron Island, two new cyclofarnesylated hydroquinone compounds, longithorols C (46) and D (47) and a novel macrocyclic chromenol, longithorol E (48) were isolated. Longithorol C (46) had its absolute stereochemistry determined by the advanced Mosher method. Chemical investigation of the deep-purple colonial ascidian, Didemnum chartaceum collected from Swains Reefs led to the isolation of five new lamellarin alkaloids, which included the 20-sulfated derivatives of lamellarins B (94), C (95) and L (96), the 8-sulfated derivative of lamellarin G (97) and the non-sulfated compound, lamellarin Z (98). The known lamellarins A (63), B (80), C (64), E (65), G (67), and L (71) plus the triacetate derivatives of lamellarin D (82) and N (83) were also isolated. An aberration in the integration of signals in the 1H NMR spectra of the 20-sulfated derivatives (94-96) led to NMR relaxation studies. T1 values were calculated for all protons in the sulfated lamellarins (94-97) and their corresponding non-sulfated derivatives (80, 64, 71, 67). The protons ortho to the sulfate group in compounds (94-97) had T1 values up to five times larger than the corresponding protons in their non-sulfated derivatives (80, 64, 71, 67). A specimen of Eudistoma anaematum collected from Heron Island was shown to contain a new b-carboline alkaloid, eudistomin V (130), in addition to the two known metabolites, eudistomin H (105) and I (106). Part B. The known natural products, 1,3-diphenethylurea (29), 1,3-dimethylxanthine (30), 1,3-dimethylisoguanine (31) and the salts of tambjamine C (16), E (18) and F (19) were isolated from the ascidian, Sigillina signifera collected in Blue Lagoon, Lizard Island. Base hydrolysis on mixtures of the salts of tambjamine C (16), E (18) and F (19) resulted in the production of 4-methoxy-2,2-bipyrrole-5-carbaldehyde (26). This natural product template (26) was used in the generation of an enamine combinatorial chemistry library (98, 103-111) using solution-phase parallel synthesis. The biaryl compound, 4-(2-thienyl)-1H-pyrrole-2-carbaldehyde (59) was successfully synthesised using Suzuki-Miyaura coupling conditions and subsequently used as a template in the generation of an amine (67, 77, 80-87) and imine (78, 92-95) combinatorial library using solution-phase parallel synthesis.

La jonction Josephson (JJ) est le composé de base de nombreux circuits électroniques supraconducteurs (SQUID, détecteurs d’ondes millimétriques, logique RSFQ). Avec la découverte des supraconducteurs HTc (à haute température critique), d’intenses recherches ont été entreprises pour réaliser des JJ fonctionnant à la température de l’azote liquide (77 K) permettant l’utilisation d’une cryogénie compacte. Toutefois, la complexité de ces matériaux a longtemps rendu difficile le développement d’une technologie viable et simple à mettre en œuvre. Parmi les méthodes de fabrication de jonctions, celle utilisant l’irradiation par faisceau d’ions a atteint un niveau de maturité suffisamment important pour pouvoir envisager la production de circuits comportant plusieurs milliers de JJ à HTc.Le but de ma thèse repose sur la fabrication, la caractérisation et l’étude des propriétés électromagnétiques de réseaux de jonctions Josephson réalisés dans des films minces d’YBa2Cu3O7-d. par la méthode d’irradiation ionique<br>The Josephson junction (JJ) is the basis of many compound superconducting electronic circuits (SQUID detectors millimeter wave RSFQ logic). With the discovery of HTS superconductors (high critical temperature), intensive research has been undertaken to make JJ operating at the temperature of liquid nitrogen (77 K) allowing the use of a compact cryogenics. However, the complexity of these materials has long hampered the development of a viable technology and simple to implement. Among the junctions manufacturing methods, one using the ion beam irradiation has reached a sufficiently high degree of maturity to be able to envisage the production of circuits having thousands of JJ to HTS.The aim of my thesis is based on the fabrication, characterization and study of the electromagnetic properties of Josephson arrays achieved in thin films of YBa2Cu3O7-d. by the ion irradiation method

It is currently hypothesised that the chokka squid (Loligo reynaudi) consist of a single stock. This was tested through a spatial comparison of the morphology of this species. Forty three morphometric characters were measured from 1079 chokka squid collected from three regions: the south coast of South Africa, the west coast of South Africa, and southern Angola. While no significant differences were found for the hard body parts, results from discriminant function analyses showed the soft body morphometric characters from each of the three regions differed, with an overall correct classification rate of 100% for males and 99% for females in all three regions. Due to the existing model being used to assess the resource currently being updated it was not feasible to apply this model to the area-disaggregated data from this study. Rather, the CPUE trends and catches from the area-disaggregated data were compared against those of the area-aggregated data, as a first attempt to discern any appreciable differences which would suggest the use of disaggregated data in future assessments. Both the trawl and jig CPUE trends from the area-disaggregated analysis differed only slightly from those of the area-aggregated data. Similarly, the spring and autumn biomass trends for the main spawning area (east of 22°E) followed the same trends as for the full area. It is therefore concluded that there is currently no need to assess the resource on an area-disaggregated basis.

Thesis (MTech (Oceanography))Cape Peninsula University of Technology, 2010<br>The current dynamics along the Tsitsikamma coast is described from a combination of acoustic current measurements. satellite-tracked surface drifters and underwater temperature recordings made between November 2006 and March 2008. The Tsitsikamma coast is largely a Marine Protected Area (MPA) that protects a rich marine biodiversity. The nearshore currents are important in the dispersal of eggs and larvae of many marine species. including the paralarvae of the commercially caught chokka squid. LoNgo reynaudii. Changes in the environment, including the currents. can affect the successful recruitment of chokka squid, and can bring about large annual fluctuations in biomass that creates economic uncertainty in the squid fishery. Results confirm the existence of a predominantly alongshore current off the Tsitsikamma coast. At Middelbank eastward flow was slightly dominant, with a percentage occurrence of 58% vs. 41% westward flow near the surface. The percentage eastward flow decreased with depth, with 41% vs. 58% westward flow near the seabed. At Thyspunt westward and eastward flow occurred at near equal percentages. but westward flow was slightly dominant throughout the water column. The alongshore current was strongest near the surface during eastward flow (maximum = 141 crn.s1: average = 27 crn.s '). while westward surface currents were weaker (maximum velocity = 78 cm.s1: average = 19 crn.s1). Current speed generally decreased with depth and opposing surface and bottom currents, associated with a thermal stratified water column, were occasionally recorded. The nearshore flow regime was characterised by frequent barotropic alongshore reversals that occurred year round. An increase in strong eastward episodes, and opposing surface and bottom currents during spring and summer months have implications for the dispersal of squid paralarvae during the summer and winter spawning seasons. In summer, the combination of strong eastward pulses in the current and upwelling at the capes favoured dispersal onto the midshelf of the Agulhas Bank. In winter, alongshore oscillations without the offshore displacement associated with upwelling. restricted offshore dispersal which caused surface particles to be retained inshore. Drifter trajectories show that both the eastward and westward nearshore current can link the inshore spawning grounds with the nursery grounds, offshore on the central Agulhas Bank; and that passive, neutrally buoyant material in the surface layer can reach the vicinity of the cold ridge in as little as eight days. The wind-driven processes of upwelling and coastal trapped waves (CTWs). and the influence of the greater shelf circulation are discussed as possible driving forces of variability in the currents off the Tsitsikamma coast. The occurrence of coastal trapped waves during thermal stratification appears to drive the jet-like, eastward pulses in the current. and results suggest that the propagation of CTWs may regulate and even enhance upwelling and downwelling along the Tsitsikamma coast.

Thesis (MA)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Seeking to navigate and explore diasporic identity, as reflected in and by transatlantic narrative spaces, this thesis looks to three very different novels birthed out of the Atlantic context (at different points of the Atlantic triangle and at different moments in history): Our Sister Killjoy or Reflections from a Black-eyed Squint (1977) by Ama Ata Aidoo, The Chosen Place, The Timeless People (1969) by Paule Marshall and Crossing the River (1993) by Caryl Phillips. Recognising the weight of location – cultural, geographic, temporal – on the literary construction of transatlantic identity, this thesis traces the way in which Aidoo, Marshall and Phillips use fictional texts as tools for grappling with ideas of home and belonging in a world of displacement, fracture and (ex)change. Uncovering the impact of roots, as well as routes (rupta via) on the realisation of identity for the diasporic subject, this study reveals and wrestles with various narrative portrayals of the diasporic condition (a profoundly human condition). Our Sister Killjoy presents identity as inherently imbricated with nationalism and pan-Africanism, whereas The Chosen Place presents identity as tidalectic, caught in the interstices between western and African subjectivities. In Crossing the River on the other hand, diasporic identification is constructed as transnational, fractal and perpetually in-process. This study argues that in the absence of an established sense of terra firma the respective authors actively construct home through narrative, resulting in what Erica L. Johnson has described as terragraphica. In this way, each novel is perceived and explored as a particular terragraphica as well as a fictional lieux de mémoire (to borrow Pierre Nora’s conception of “sites of memory”). Using the memories of transatlantic characters as (broken) windows through which to view history, as well as filters through which the present can be understood (or refracted), are techniques that Aidoo, Marshall and Phillips employ (although, Aidoo’s use of memory is less obvious). Tapping into various sites of memory in the lives of the fictional characters, the novels themselves become mediums of remembering, not as a means of storing facts about the past, but for the ambivalent purpose of understanding the impact of the past on the present.<br>AFRIKAANSE OPSOMMING: In ’n poging om diasporiese identiteit te karteer en te ondersoek, betrek hierdie verhandeling drie uiteenlopende romans wat in die Atlantiese konteks, naamlik vanuit die verskillende hoeke van die Atlantiese driehoek en verskillende geskiedkundige Atlantiese momente, ontstaan het. Die drie romans sluit in: Our Sister Killjoy or Reflections from a Black-eyed Squint (1977) deur Ama Ata Aidoo, The Chosen Place, The Timeless People (1969) deur Paule Marshall en Crossing the River (1993) deur Caryl Phillips. Deur die belangrikheid van plek – kultureel, geografies en temporeel – in die literêre konstruksie van transatlantiese identiteit, te beklemtoon, spoor hierdie verhandeling die manier waarop Aidoo, Marshall en Phillips fiktiewe tekste aanwend na om sin te maak van idees oor tuiste en geborgenheid in ’n wêreld van verdringing, skeuring en (ver)wisseling. Deur die impak van die oorsprong op, asook die weg (rupta via) na, die verwesenliking van identiteit vir die diasporiese subjek te toon, onthul en worstel hierdie tesis met verskeie narratiewe uitbeeldings van die diasporiese toestand (’n toestand eie aan die mens). Our Sister Killjoy stel identiteit as inherent vermeng met nasionalisme en pan-Afrikanisme voor, terwyl The Chosen Place identiteit as tidalekties uitbeeld – vasgevang tussen westerse en Afrika-subjektiwiteite. In Crossing the River word diasporiese identifisering egter gekonstrueer as transnasionaal, fraktaal en ewigdurend in ’n proses van ontwikkeling. Hierdie studie voer verder aan dat die onderskeie skrywers tuiste aktief deur narratief konstrueer in die afwesigheid van ’n gevestigde bewustheid van terra firma, of onbekende land of plek. Die gevolg is ’n voortvloeiing van wat deur Erica L. Johnson beskryf word as terragraphica. Vervolgens word elk van die romans gesien en verken as ’n spesifieke terragraphica asook ’n fiktiewe lieux de mémoire, gegrond in Pierre Nora se konsep “sites of memory”. Die benutting van transatlantiese karakters se herhinneringe as (gebreekte) vensters waardeur die geskiedenis bespeur kan word en filters waardeur die hede verstaan (of gerefrakteer) kan word, is die tegnieke wat Aidoo, Marshall en Phillips aanwend – alhoewel Aidoo se gebruik van geheue minder ooglopend is. Deur verskeie terreine van geheue in die lewens van die fiktiewe karakters te betrek, ontwikkel die romans tot mediums van onthou, nie in die sin van feite van die verlede wat gestoor word nie, maar met die dubbelsinnige doel om die impak van die verlede op die hede te verstaan.

The objective of this thesis is to analyse the management and redistribution policies implemented in the South African squid industry. This is done within the broader context of fisheries policies that have been implemented within the South African fishing industry as the squid industry has developed. The study therefore has an institutional basis, which reviews the development of institutional mechanisms as they have evolved to deal fisheries management problems. These mechanisms (which can either be formal or informal) consist of committees, laws and constitutions that have developed as society has progressed. Probably the most prominent of these, in terms of current fisheries policy, is the Marine Living Resources Act (MLRA) of 1998. The broad policy prescription of the MLRA basically advocates the sustainable utilisation of marine resources while outlining the need to restructure the fishing industry to address historical imbalances and to achieve equity. It is this broad objective that this thesis applies to the squid fishery. The primary means of achieving the above objective, within the squid industry, has been through the reallocation of permit rights. These rights also provide the primary means by which effort is managed. A disruption in the rights allocation process therefore has implications for resource management as well. Permits rights can be described as a form of use right or propertY right. These rights are structured according to their operational-level characteristics, or rules. Changing these rules can thus affect the efficiency or flexibility of a rights based system. This is important because initial reallocation of rights, by the Department of Environmental Affairs and Tourism (DEAT), was based on an incomplete set of rights. This partly led to the failure of early redistribution attempts resulting in a "paper permit" market. Nevertheless, this thesis argues that redistribution attempts were based on ill-defined criteria that contributed to the failure described above. In addition to this the method through which redistribution was attempted is also questionable. This can be described as a weak redistribution strategy that did not account for all equity criteria (i.e. factors like capital ownership, employment or relative income levels). This thesis thus recommends, among other things, that an incentive based rights system be adopted and that the design of this system correctly caters of the operational-level rules mentioned above. In addition to this a strong redistribution, based on fishing capital, ownership, income and the transfer of skills, should be implemented.<br>KMBT_363<br>Adobe Acrobat 9.54 Paper Capture Plug-in

Le sujet de thèse concerne l'étude de réseaux réguliers de nanofils magnétiques auto-organisés. Deux approches ont été utilisées pour la fabrication : 1) Préparation de réseaux planaires de nanofils alternés (Fe,Ag) sur Mo(110). Ce mode de croissance est attribué au caractère non miscible des deux métaux et à un mécanisme modulé de relaxation des contraintes d'épitaxie. 2) Préparation de nanofils de Fer sur une surface déjà structurée en tranchées périodiques. Ces tranchées se forment spontanément lors de la croissance homoépitaxiale d'un métal cc de W(110) (ou Mo) à température modérée. La période de la structuration unidimensionnelle est contrôlable par la température de dépôt. La deuxième étape consiste à déposer le Fer sur ce gabarit. Pour une température définie, Fe croît au fond des tranchées pour former des fils régulièrement espacés. Des réseaux de fils en trois dimensions ont aussi été fabriqués. Du point de vue magnétique, les deux systèmes présentent une forte anisotropie uniaxiale avec l'axe de facile aimantation planaire, le long des fils. A température ambiante les systèmes sont superparamagnétiques. L'évolution de la coercitivité en fonction de la température s'interprète selon un processus de renversement d'aimantation thermiquement activé par nucléation/propagation. Le renversement met en jeu plusieurs fils couplés pour le premier système et s'effectue au sein des fils individuels dans le deuxième.

Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008.<br>This thesis relates to the analysis and design of a SQUID microscope. Superconductor theory is discussed in depth to provide a thorough understanding of Josephson junctions and of dc SQUID magnetometers. The behaviour and suitability of different types of single-layer dc SQUIDs are looked at. The quality of the superconducting material patterned onto a substrate and the Josephson junction design used affect the behaviour of a practical dc SQUID. Noise and cooling play an integral part in the design and operation of a dc SQUID. The source of noise is looked at in an effort to minimize its effect. Cryocooling is essential to real world operation so different cooling strategies and their consequences are analyzed. This thesis focuses on modeling the behaviour of the dc SQUID to creating a practical system for use inside a SQUID microscope. Operating the dc SQUID with the appropriate electronics will linearize the device, reduce the effect of noise, and create a device with wide bandwidth. Each step in creating a practical system is discussed in detail. Simulations are used to create models predicting the behaviour of the dc SQUID and the electronics. They are then used to design and create practical electronic systems. Measurements are performed on Josephson junctions and dc SQUID magnetometers using the designed electronics. The Josephson junctions behave as predicted and were successfully tested. The dc SQUIDs did not behave as predicted and were not successfully tested. The SQUIDs were damaged, either by a malfunction in the cryocooler or through age related deterioration. A full test of the flux-locked loop was not possible and the dc SQUID was not linearized.

Thesis (Ph. D.) -- University of Maryland, College Park, 2008.<br>Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.<br>In South Africa, squid fishing vessels need to find and then anchor above benthic squid egg beds to effect viable catches. However, waves acting on the vessel produce a dynamic response on the anchor line. These oscillatory motions produce impact forces of the chain striking the seabed. It is hypothesised that this causes damage to the squid egg bed beneath the vessels. Different mooring systems may cause more or less damage and this is what is investigated in this research. The effect of vessel mooring lines impact on the seabed during squid fishing is investigated using a specialised hydrodynamic tool commercial package ANSYS AQWA models. This study analysed the single-point versus the two-point mooring system’s impact on the seabed. The ANSYS AQWA models were developed for both mooring systems under the influence of the wave and current loads using the 14 and 22 m vessels anchored with various chain sizes. The effect of various wave conditions was investigated as well as the analysis of three mooring line configurations. The mooring chain contact pressure on the seabed is investigated beyond what is output from ANSYS AQWA using ABAQUS finite element analysis. The real-world velocity of the mooring chain underwater was obtained using video analysis. The ABAQUS model was built by varying chain sizes at different impact velocities. The impact pressure and force due to this velocity was related to mooring line impact velocity on the seabed in ANSYS AQWA. Results show the maximum impact pressure of 191 MPa when the 20 mm diameter chain impacts the seabed at the velocity of 8 m/s from video analysis. It was found that the mooring chain impact pressure on the seabed increased with an increase in the velocity of impact and chain size. The ANSYS AQWA impact pressure on the seabed was found to be 170.86 MPa at the impact velocity of 6.4 m/s. The two-point mooring system was found to double the seabed mooring chain contact length compared to the single-point mooring system. Both mooring systems showed that the 14 m vessel mooring line causes the least seabed footprint compared to the 22 m vessel.

Les circuits à base de jonctions Josephson comme les filtres à interférences quantiques, nommés SQIF (Superconducting Quantum Interference Filter), sont des capteurs très sensibles au champ magnétique. Les éléments de base d’un tel circuit sont les SQUID (Superconducting Quantum Interference Device). Aussi performants dans la détection de champ magnétique, ces derniers ne permettent pas de réaliser des mesures absolues. De plus, la nécessité d’un asservissement par une boucle à verrouillage de flux limite la bande de fréquence d’utilisation. Les SQIF n’ont pas cette limitation et permettent les mesures absolues de champ magnétique. Leur capacité à combiner une taille compacte, une très bonne sensibilité et une large bande fréquentielle d’utilisation fait de ces capteurs des sérieux concurrents aux antennes classiques. Des mesures expérimentales avec des SQIF HTS faits par la technologie de jonctions irradiées montrent qu’il est possible de réaliser la détection de signaux radiofréquence jusqu’au moins 5 GHz en configuration de champ proche et en environnement non magnétiquement blindé. Afin de réaliser l’adaptation d’impédance et améliorer les caractéristiques DC de ces capteurs, différentes géométries de réseau sont étudiées. L’étude permet de définir les paramètres d’importance dans la conception de circuits SQIF afin de réaliser des détecteurs radiofréquence performants<br>Superconducting Quantum Interference Filters (SQIF) are Josephson circuits very sensitive to magnetic field. They are made of arrays of SQUIDs (Superconducting QUantum Interference Devices). The latter, when operated alone, doesn’t allows absolute magnetic field measurements and have to be used with a flux locked loop, which limits the frequency band of operation. SQIFs doesn’t have such limitations and they offer the possibility to combine compactness, sensitivity and wide band of frequency at the same time. Because of this, SQIFs are serious concurrents to classical antennas in microwave applications. Experimental measurements made with HTS SQIFs and irradiated Josephson junctions shows that it is possible to detect microwave signals up to 5 GHz in an unshielded environment, and near field configuration. To perform better detection, it is important to match impedance of circuits. In the goal to do this and to improve DC characteristics, different network geometries are studied. At the end this study allows to define which parameters are important in the design of SQIF circuits for microwave detection

Thesis (Ph. D.) -- University of Maryland, College Park, 2006.<br>Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Thesis (Ph. D.) -- University of Maryland, College Park, 2004.<br>Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Une étude théorique que nous avons menée prédit qu'un SQUID-DC, ayant un facteur de qualité égal à 100 dans son régime d'effet tunnel macroscopique, permet une mesure quantique en un coup l'état de charge d'un qubit avec une erreur de l'ordre de 2%. Ce travail de thèse s'inscrit donc dans l'étude et le développement expérimental d'un système de mesure quantIque d'un SQUID. Nous avons étudié la dynamique d'échappement de l'état de tension nulle d'un SQUID-DC inductif en fonction du flux et de la température. Nous avons mis en évidence le régime d'effet tunnel macroscopique et d'activation thermique, dans le cadre de l'échappement d'une particule fictive métastable d'un potentiel bi-dimensionnel. Le temps de vie de l'état de tension nulle d'un SQUID dans son régime d'activation thermique a été mesuré dans la gamme des nano-secondes grâce à une technique d'impulsions en flux. L'utilisation d'impulsions micro-ondes a également permis de mesurer la fréquence plasma d'un SQUID par une technique d'activation résonante, et de mesurer un facteur de qualité de l'ordre de 100.

Nano-electromechanical systems (NEMS) are an important new class of device, with a growing range of applications, from tests of quantum mechanics through to nanoscale metrology and a vast number of different sensors. Cryogenic operation is also possible, and at low temperatures, nanoscale resonators exhibit quantum behaviour. NEMS resonators require readout of ultra-small, atomic scale displacements. To achieve this at low temperatures we have developed an ultrasensitive nanoSQUID readout of a coupled current-carrying NEMS resonator. The NanoSQUIDs are fabricated by gallium focussed ion beam milling and are based on niobium nanobridge weak links (Dayem bridges). The nanoSQUIDs have low loop inductance and low junction capacitance resulting in high flux and energy sensitivity. This work focusses on the characterisation of the resonator and nanoSQUID after they have been incorporated onto one chip. This is done through nanoindentation to characterise resonators and electronic measurements of the SQUID using a low-temperature preamplifier. It is found that the model used based upon an Euler-Bernoilli beam is correct close the centre of the sample but does not fit data points well close to the contacts. It is found the resonators have Young’s modulus in the range of 3GPa-241GPa. Both beam and paddle-shaped resonators are investigated and the models are made based upon the two different shapes. That for the paddle is based upon the same as the beam but uses a rectangular function to describe the changing area moment of inertia along the length of the resonator. The SQUID devices are characterised and found to have a typical noise floor of 0.2μ 0/pHz. Problems which have arisen due to the orientation of the two magnetic fields and their effect on the SQUID performance are discussed. We consider the geometry and optimum coupling of rectangular and square Si3N4 resonators to matching similar shaped nanoSQUID loops. We also discuss simulations of the nanoSQUID response versus resonator position for both symmetric and asymmetric configurations. It is found that optimal coupling is achieved in the asymmetric case due to the cancelling of the change in flux in the symmetric case. The use of a normal conducting or superconducting resonator is compared. It is found that a superconducting resonator provides a much larger SQUID response when actuated towards​ the device but cannot be used in the regime due to limitations of the superconducting transition temperature of Al (the resonator) being lower than the non-hysteretic operable temperature of the SQUID. Preliminary measurements are conducted on the coupled devices. It is noted that the signal from the device in the conducting case may be read out at 2! due to the sinusoidal change in flux through the SQUID loop and position of the resonator. The possibility of measuring such a signal is first investigated using a spectrum analyser but it is found the SQUID is pushed to nonlinear regions of its transfer curve. This results in a component of the signal at 2! due to the nonlinearity of the SQUID response. Conditions under which the SQUID is still operating in small signal mode (to preserve linearity of the SQUID response) are considered and from this we conclude there is a need to use phase sensitive detection to achieve optimum sensitivity. This technique is used to conduct the final measurement of the motion of the resonator by the SQUID and a preliminary result is found.

O objetivo desta tese foi o estudo da detecção de campos magnéticos fracos através da utilização de gradiômetros supercondutores acoplados à SQUIDs e sua aplicação ao biomagnetismo. Um novo modelo teórico para descrição do gradiômetro foi desenvolvido com a obtenção da sua função de transferência espacial. Através desta função de transferência a atuação do gradiômetro sobre os sinais detectados pode ser quantificada. Além disso, foi desenvolvido para a medida experimental da função de transferência, onde as imperfeições no processo de construção do sensor podem ser medidas e avaliadas. Foi proposta uma nova terminologia para descrição do gradiômetro ao invés de sua descrição física. Nesta terminologia, o gradiômetro ficará especificado pelo seu roll off, freqüência de corte espacial e ganho máximo. Também foi generalizado o método para projeto de gradiômetros onde novas configurações podem ser construídas e testadas. A partir da obtenção desta função de transferência um método para calibração tesla /volt do sistema foi desenvolvido, com uma precisão até então não alcançada por outros métodos e perfeitamente apropriado para utilização em sistemas multicanais. Finalmente foi desenvolvido um algorítimo de desconvolução para, a partir de sinais detectados com gradiômetros planares, recuperar o sinal original como ele tivesse sido detectado somente por uma bobina. Este algorítmo também pode ser utilizado para auxílio no projeto de arrays destes gradiômetros.<br>The objective of this thesis was to study the detection of weak magnetic fields through the use of superconducting gradiometers coupled to SQUIDs and its application to biomagnetism. A new theoretical model for the specification of the gradiometer was developed by obtaining its spatial transfer function. Through the transfer function the signal detected by the gradiometer can be quantified. Besides, a procedure was developed to experimentally measure the spatial transfer, where the imperfections in the construction process of the sensor can be measured and evaluated. A new terminology was proposed for specification of the gradiometer instead of his physical description. Using this terminology, the gradiometer will be specified by its roll off, spatial cutoff frequency and maximum gain. Also the method was generalized for design of gradiometers where new configurations can be built and tested. From the transfer function a method for tesla/volt calibration of the system was developed. Finally a deconvolution algorithm was developed, that from signals detected by the gradiometer the original signal can be recovered. This algorithm also can be used in the design of gradiometer arrays.

Abstract Background: The squat is one of the most used exercises in the field of strength and conditioning. It is included as a core exercise in many sports training programmes to enhance athletic performance due to its biomechanical and neuromuscular similarities of a wide range of athletic movements. The barbell squat commonly used by athletes participating in resistance training and it is generally performed using regular athletic shoes or specially designed weightlifting shoes. However it is now getting more common to perform the barbell back squat in barefoot or in barefoot-inspired foot wear. Weightlifting shoes may be well known to weightlifters but to the noncompetitive lifters and professional athletes they are in general unfamiliar. It is believed that the structure of the weightlifting shoe supports proper squat mechanism. There is however limited scientific data reporting on the use of weightlifting shoes and therefore, it may be needed to investigate how weightlifting shoes affects the lower body lifting kinematics in the back squat compared to other conditions. Aim: The aim of the study was to compare the kinematic differences that appears in the sagittal plane when performing a barbell back squat wearing weightlifting shoes and barefoot. Method: Fifteen healthy participants (n=15) completed the study. The study included the barbell back squat in three sets of three repetitions on 50, 60 and 70% of the participant’s 1RM. The participants performed the movement in both weightlifting shoes and barefoot in an order randomly chosen and all movements was recorded with a digital camera from the sagittal plane. Results: The results showed that the angles were greater in the weightlifting shoe condition on all percentage. The results showed that there was no statistical significance in the hip angle at 50% of 1RM (p= 0,370) or at 70% (p = 0,053) but a statistical significance in the hip angle at 60 % (p = 0,028). The results showed no statistical significance in the ankle angle at 50% of 1RM (p = 0,997), 60% (p = 0,182) or 70 % (p = 0,332). Conclusion: Findings from this study did not demonstrate that there was a significant difference between performing a barbell back squat in weightlifting shoes and barefoot. More research is needed to investigate and compare more variables in the difference between performing a barbell back squat wearing weightlifting shoes and barefoot.

Thesis (Ph. D.) -- University of Maryland, College Park, 2007.<br>Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

The information covered in this project is intended to give the physical educator and coach an easy-to-follow manual with illustrations to guide them through basic instructions on the parallel squat. This project will include biomechanical principles of the squat exercise.

Superconducting Quantum Interference Devices (SQUIDs) are the most sensitive magnetic flux sensors known. In order to achieve a high field resolution, an antenna is coupled to the bare SQUID. Flux focusing, direct and flux transformer coupling schemes were investigated. Off-axis pulsed laser deposited YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-δ</SUB> films with protective SrTiO<SUB>3</SUB> (STO) cap layers on 24° STO bicrystal substrates were patterned into SQUID structures. A multilayer technology with YBCO and STO layers was used to fabricate trilayer flux transformers. The flux transformers was then coupled inductively to the bare SQUID in a flip-chip arrangement. Characterisation equipment was developed to measure SQUID parameters. Noise measurements with a bias reversal technique were employed to reduce the 1/f component, which dominates the noise at low frequencies. All noise data were obtained at 77 K. For a flux focusing SQUID, a flux noise level of φ<SUB>n</SUB> = 2.8 μφ<SUB>0</SUB>Hz<SUP>-1/2</SUP> at 10 kHz and φ<SUB>n</SUB> = 11.5 μφ<SUB>0</SUB>Hz<SUP>-1/2</SUP> at 1 Hz with bias reversal was achieved. The field sensitivity of the flux focused SQUID was limited by the small effective area, A<SUB>eff </SUB>= 0.83 x 10<SUP>-3</SUP> mm<SUP>2</SUP>, but this type of device was successfully integrated into the IRC cold sample scanning SQUID microscope which was used to image currents in wires and ferromagnetic link samples. Direct and flux transformer coupling schemes increased the effective areas to 0.23 mm<SUP>2</SUP> and 1.08 mm<SUP>2</SUP> respectively. The best white field sensitivity measured corresponded to 105 fTHz<SUP>-1/2</SUP> for the directly coupled SQUID and 42 fTHz<SUP>-1/2</SUP> for the flux transformer coupled SQUID. Planar, first-order directly coupled gradiometers were investigated as part of the collaboration with Oxford Instruments plc and a white gradient field sensitivity of 2.1 pTcm<SUP>-1</SUP>Hz<SUP>-1/2<I> </I></SUP>in an unshielded environment was achieved.

Millimetre-wave radar in a missile seeker for the engagement of ground targets allows all-weather, day and night, surface imaging and has the ability to detect, classify and geolocate objects at long ranges. The use of a seeker allows intelligent target selection and removes inaccuracies in the target position. The selection of the correct target against a cluttered background in radar imagery is a challenging problem, which is further constrained by the seeker’s hardware and flight-path. This thesis examines how to make better use of the components of radar imagery that support target selection. Image formation for a squinted radar seeker is described, followed by an approach to automatic target recognition. Size and shape information is considered using a model-matching approach that is not reliant on extensive databases of templates, but a limited set of shape-only templates to reject clutter objects. The effects of radar sensitivity on size measurements are then explored to understand seeker operation in poor weather. Size measures cannot easily be used for moving targets, where the target signature is distorted and displaced. The ability to detect, segment and measure vehicle dimensions and velocity from the shadows of moving targets is tested using real and simulated data. The choice of polarisation can affect the quality of measurements and the ability to reject clutter. Data from three different radars is examined to help to understand the performance using linear and circular polarisations. For sensors operating at shorter ranges, the application of elevation monopulse to include target height as a discriminant is tested, showing good potential on simulated data. The combination of these studies offers an insight into the performance factors that influence the design and processing of a radar seeker. The use of shadow imagery on short-dwell radar seeker imagery is an area offering particular promise.