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This dissertation consists of three essays on econometric analysis including both parametric and nonparametric econometrics. The first chapter outlines three topics involved and briefly discusses the motivations and methods, as well as some conclusions in each of the following chapters. Both chapter 2 and chapter 3 are in the field of kernel smoothed nonparametric econometrics. Chapter 2 conducts large volumes of simulations to explore the properties of various methods proposed in the literature to detect irrelevant variables in a fully nonparametric regression framework. We focus our attention to two broadly sets of methods, the least square cross-validated bandwidth selection procedure and the conventional nonparametric significance testing frameworks. In chapter 3, a bootstrap test statistic is proposed to test the validity of imposing some arbitrary restrictions on higher order derivatives of a regression function. We use data sharpening method to enforce the desired constraints on the shape of the conditional means and then measure the distance between the unrestricted and restricted models. The empirical distribution of the test statistic is generated by bootstrapping and the asymptotic distribution for the bootstrap test statistic is also provided. The last chapter examines the relationship between population health and income inequality in China. We use a multilevel dynamic panel model to test the absolute income hypothesis, various versions of relative income hypothesis, and health selection hypothesis empirically / Ph. D.

In this thesis we study Sobolev gradient flows for Perona-Malik style energy functionals and generalizations thereof. We begin with first order isotropic flows which are shown to be regularizations of the heat equation. We show that these flows are well-posed in the forward and reverse directions which yields an effective linear sharpening algorithm. We furthermore establish a number of maximum principles for the forward flow and show that edges are preserved for a finite period of time. We then go on to study isotropic Sobolev gradient flows with respect to higher order Sobolev metrics. As the Sobolev order is increased, we observe an increasing reluctance to destroy fine details and texture. We then consider Sobolev gradient flows for non-linear anisotropic diffusion functionals of arbitrary order. We establish existence, uniqueness and continuous dependence on initial data for a broad class of such equations. The well-posedness of these new anisotropic gradient flows opens the door to a wide variety of sharpening and diffusion techniques which were previously impossible under L2 gradient descent. We show how one can easily use this framework to design an anisotropic sharpening algorithm which can sharpen image features while suppressing noise. We compare our sharpening algorithm to the well-known shock filter and show that Sobolev sharpening produces natural looking images without the "staircasing" artifacts that plague the shock filter. / Thesis (Master, Mathematics & Statistics) -- Queen's University, 2010-08-25 10:44:12.23

Eleven official languages are spoken in South Africa. Misunderstandings during communication seems to be inevitable. The researcher or psychologist often does not speak or have full command of the language of the group that is being investigated, and therefore has to rely on interpreters to understand the internally experienced world of these persons. Trained interpreters are scarce and this study endeavours to determine the extent of the validity of translations done by the available interpreters. This is done by means of a psychological-systemic perspective. The nature of this study is qualitative. Fifteen interviews were conducted with trauma patients at the Maxilla- and Face Surgery Department of the Garankuwa Hospital. Only eleven of these were useable. Mouth injuries etc. affected the quality of the other interviews not used. Four nurses from this department interviewed the patients and wrote up the interpreted answers on a semi-structured interview schedule made available by the researcher. A verbatim translation of the interviews was made from the tape recordings. Units of meaning were assigned and a comparison of the interpreted and the verbatim translations were made. Three perceptual styles were used to identify how much of the meaning the interpreter included (sharpening), excluded (levelling) and changed (assimilation) during the translation. The translation-interpretation process is analysed against the contextual background and paradigms of the participants The results make it clear that South Africa indeed has a problem with the validity of the outputs of interpreters being used as well as the availability of interpreters and their subject-specific training. Copyright 2005, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Barsby, A 2005, Die rol van tolke in onderhoudvoering : ‘n sielkundig-sistemiese perspektief en geldigheidsbepaling (Afrikaans), MA dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10172005-152643 / > / Dissertation (MA (Research Psychology))--University of Pretoria, 2006. / Psychology / unrestricted

<p>Proteins have such structural features that they may interact with different types of surfaces by all possible forces, i.e., electrostatic, hydrogen bonding, hydrophobic. In this thesis two different types of coatings for fused silica capillaries aimed to eliminate such interactions have been studied. The first is a covalent, electroosmosis-free coating with polyacrylamide (PAA) and the second involves a non-covalent coating with the quaternary ammonium compound N, N-didodecyl –N, N- dimethylammonium bromide (DDAB) with a strong anodic electroosmosis. Optimal conditions regarding efficiency and resolution were established by variations of the composition and ionic strengths of buffers at pH below the isoelectric point of the proteins. To achieve high efficiency and resolution the choice of buffer constituents was extremely important. </p><p>The PAA coating was very stable at neutral and acidic conditions. Ammonium acetate (0.12 M) and ammonium hydroxyacetate (0.15 M) both at pH 4 provided the best separations with plate numbers up to 1 700 000 plate/m that is among the highest reported in the literature. Capillaries coated with DDAB were stable enough to, without recoating, permit consecutive separations of the proteins up to 9 hours (90 injections). High apparent efficiencies (over 1 million plates/m) were achieved with ammonium acetate (0.07 M), ammonium hydroxyacetate (0.08 M) and sodium phosphate (0.1 M) at pH 4. </p><p>Zone broadening was studied by determination of the variance contributions from all main parameters. Significant variances were contributions from longitudinal diffusion, capillary curvature, injection plug, detector time response and detector slit width while other variances, e.g., variances for Joule heat and vertical sedimentation were negligible. The remaining undetermined variance may have its origin in all types of relatively slow interactions including adsorption onto the capillary surfaces and protein-buffer component interactions. The results indicate that the latter is the main cause to zone broadening in protein separations.</p>

Proteins have such structural features that they may interact with different types of surfaces by all possible forces, i.e., electrostatic, hydrogen bonding, hydrophobic. In this thesis two different types of coatings for fused silica capillaries aimed to eliminate such interactions have been studied. The first is a covalent, electroosmosis-free coating with polyacrylamide (PAA) and the second involves a non-covalent coating with the quaternary ammonium compound N, N-didodecyl –N, N- dimethylammonium bromide (DDAB) with a strong anodic electroosmosis. Optimal conditions regarding efficiency and resolution were established by variations of the composition and ionic strengths of buffers at pH below the isoelectric point of the proteins. To achieve high efficiency and resolution the choice of buffer constituents was extremely important. The PAA coating was very stable at neutral and acidic conditions. Ammonium acetate (0.12 M) and ammonium hydroxyacetate (0.15 M) both at pH 4 provided the best separations with plate numbers up to 1 700 000 plate/m that is among the highest reported in the literature. Capillaries coated with DDAB were stable enough to, without recoating, permit consecutive separations of the proteins up to 9 hours (90 injections). High apparent efficiencies (over 1 million plates/m) were achieved with ammonium acetate (0.07 M), ammonium hydroxyacetate (0.08 M) and sodium phosphate (0.1 M) at pH 4. Zone broadening was studied by determination of the variance contributions from all main parameters. Significant variances were contributions from longitudinal diffusion, capillary curvature, injection plug, detector time response and detector slit width while other variances, e.g., variances for Joule heat and vertical sedimentation were negligible. The remaining undetermined variance may have its origin in all types of relatively slow interactions including adsorption onto the capillary surfaces and protein-buffer component interactions. The results indicate that the latter is the main cause to zone broadening in protein separations.

Diplomova praca sa zameriava na oblast zaostrovania obrazkov tvari. V teoretickej casti prace budu prezentovane moderne metody zaostrovania obrazkov pomocou jedineho obrazku a metody editacie obrazkov. Prakticka cast sa zameria na pristupy rekonstrukcie obrazkov zo sekvencie poskodenych obrazkov. Viacere modely neuronovych sieti so vstupom pre viacero obrazkov budu zhotovene a vyhodnotene. Alternativny pristup v podobe balika nastrojov na editaciu obrazkov bude taktiez predstaveny. Tieto nastroje budu vyuzivat najmodernejsie pristupy k editacii obrazkov s cielom spojit vizualne prvky tvari zo vstupnej sekvencie obrazkov do jedneho finalneho vystupu. V zavere prace budu vsetky metody navzajom porovnane.

Styckares arbete är fysiskt ansträngande och kännetecknas av att vara utpräglat manuellt där den handhållna kniven är det viktigaste verktyget. Arbetet innebär enligt arbetsskadestatistiken hög risk för arbetsrelaterade skador och sjukdomar. Syftet med avhandlingen är att identifiera och utvärdera arbetsmiljöförbättringar som styckningsföretag och anställda styckare i samverkan och under beaktande av systemeffektivitet kan vidta. Ett andra syfte är att ge ett kunskapsbidrag som branschen kan tillämpa i sin framtida arbetsmiljöutveckling. Avhandlingen baseras på det arbete som genomfördes i två forskningsprojekt (STAR respektive SKARP). Dessa bedrevs som en branschintervention, i en interaktiv ansats och med styrgrupper med deltagare från branschorganisationen Kött- och Charkföretagen samt representanter från styckningsföretag och livsmedelsarbetarnas fackförening. De studier som ingår i avhandlingen har huvudsakligen genomförts i reell miljö som kvasi-experimentella fallstudier. Styrgrupperna i projekten samt de aktuella företagen deltog i planering och utvärdering av dem. Resultaten visade att styckningsarbete är så fysiologiskt krävande att många styckare ingående i mätningarna låg över den nivå som rekommenderas för att arbetet skall vara hållbart. Avhandlingen rekommenderar därför att den fysiska arbetsbelastningen på individnivå i styckningsarbete inte ska överstiga 30 Relative Aerobic Strain (RAS), dvs. den andel av sin fysiska förmåga uttryckt i syreupptagning som individen använder i sitt arbete. Vidare visar resultaten att ökad arbetstakt försämrar kvalitet och utbyte samt företagens lönsamhet. En ökad arbetstakt upplevs dessutom negativt av styckarna. Polering av knivarna istället för att slipa dem innebär att kniven kan bli vassare, dess livslängd förlängs och därmed minskar kostnaderna för knivslitage samtidigt som risken för belastningsskador minskar. För den enskilde individens hållbara anställning i styckningsarbete föreslås flera åtgärder: bl.a. att införa ett system för förbättrad knivskärpa där utbildning och teknik för att hålla knivarna vassa ingår samt att organisera arbetet med en anpassning av teknik, arbetstakt och arbetstyngd som främjar styckarnas hälsa. Interaktiviteten i projekten resulterade i ökat samarbete om arbetsmiljön mellan styckningsföretagen och med Arbetsmiljöverket. För att arbetsmiljöförbättrande åtgärder ska bli hållbara samt även ge ett bidrag till företagets lönsamhet bör de ske i samverkan med samt engagera de anställda. / <p>QC 20150630</p>

The electronic control, instrumentation and communication hardware is becoming more and more compact and faster in operation due to the increased use of large scale integration of semiconductor devices operating at higher speeds. The use of VLSI circuit based systems in various industrial and defence sectors is also increasing continuously. Since the operating threshold voltages and currents of these devices are very small they are very prone to electrical disturbance in their operation by the Electromagnetic Interference (EMI) signals. Their proper functioning is very important particularly in the case of systems used in mission mode, critical defence/industrial platforms. EMI can be generated within the electronic system/equipment itself or may result due to some external electromagnetic source. The high power Ultra Wide Band system is one such kind of external High Power Electromagnetic (HPEM) interference source which may cause malfunctioning/physical damage to the sensitive electronic systems. Hence it is necessary to test the susceptibility of electronics to such high power UWB based intentional EMI or IEMI sources. The sources for generating these transient EM fields may also be used in impulse radars and offensive applications to mal-operate/damage non-friendly electronics. The UWB system consists of a high voltage pulsed power source called pulser along with a high bandwidth (Ultra Wide Band) antenna to radiate the UWB signal. The pulse fed by the pulser to the antenna through a switch is of high voltage type (amplitude of few 10s of kV to about a MV) and has a sub-nanosecond rise time. Most of the UWB systems developed over the world have the switch employing gaseous dielectric switching media used at pressures above the atmospheric level to generate such a fast rise time voltage pulse. Use of gaseous switching media at sub-atmospheric pressures to achieve sub-ns rise time, short duration high voltage pulses required for the high power UWB applications is another possibility. This possibility has not been exploited till date. Hence it was decided to develop a pulser switch with gaseous switching media at sub-atmospheric pressures (up to 50 mbar) and achieve sub-ns rise time voltage pulses of up to 50 kV. The energy delivered out by the UWB system depends upon the pulser output energy per switching shot and the repetitive switching rate of the pulser. To achieve maximum energy output it is required to maximize either the energy per switching shot or the pulse repetition rate (PRR) of the pulser switch. The optimization of the pulser operation to achieve maximum pulser energy output in every switching shot has not been tried so far. In this work it was decided to analyze the circuit so as to achieve maximum pulser output energy per switching shot. Another objective of the study was to systematically characterize the pulser switch using various gases and gas mixtures as the switching media to evaluate the switch performance as a function of gas pressure and switch breakdown voltage. The effect of pulser and antenna performance parameters on the UWB system performance was also decided to be evaluated. Hence the present thesis work deals with the design, development, evaluation and performance optimization of a 50 kV, 25 MW UWB system based on Half Impulse Radiating Antenna (HIRA) fed by a coaxial capacitive pulser. The spark gap type self triggered pulser switch is designed to have a fixed gap spacing and variable gas pressure in order to vary the switch breakdown voltage. The switch is designed for operation with dry air, nitrogen, sulphur hexafluoride (SF6) and a mixture of different gases as the dielectric switching media with pressures of up to 5 bar above the atmospheric level and up to 50 mbar below the atmospheric level. Physical placement of the switch just above the coaxial pulser capacitor terminal offered a low inductance geometry. The rise time estimation of the switch has been carried out as a function of gas pressure and the switch arc inductance. These rise time values have been compared with the measured ones and a good agreement was found between the two. The rise time values indicate that an inverse relationship exists between the gas pressure and the rise time. The rise time was found to decrease at increased pressures. SF6 gas offered the minimum rise time out of all the gases/mixtures studied. The pulse repetition rate (PRR) of the UWB system depends upon the dielectric recovery of the gaseous switch and the charging time of the pulser capacitor. To estimate the PRR a circuit model has been proposed based on these parameters. The model shows an inverse relationship between the switch breakdown voltage (BDV) and the gas pressure with the PRR. The estimated PRR values were found to vary between 800 Hz and 5 kHz in the experimented range of the switch breakdown voltage. The PRR values have also been experimentally measured. There is a good match between the measured and the estimated values up to the switch BDV of 12.5 kV after which the difference is increased to about 20 %. The feed for the reflector of the HIRA antenna consists of a pair of coplanar conical transverse electromagnetic (TEM) feed plates as they have a better antenna aperture blockage performance. The angles of the TEM feed plates have been chosen using stereographic projections of the feed plates into the HIRA reflector. Each TEM feed plate of 200  characteristic impedance has been terminated by matched resistor. An analytical expression has been derived to optimize the pulser output voltage at which the energy output per switching shot of the UWB system is maximum. It was found that when the pulser output voltage i.e. the switch breakdown voltage is 75 % of the dc source voltage the output energy delivered is maximum. It was possible to achieve a maximum output energy of 10 J per switching shot for the designed 25 MW high power UWB system. The HIRA antenna has been analysed for the impedance profile for frequencies up to 3.5 GHz and was found to maintain a reflection performance better than -10 dB over the frequency range. The radiated field analysis of the antenna was carried out using an analytical model and numerically by using a commercially available software. It was found that as per the analytical model, the Figure of Merit (FoM) of the designed UWB system is 1.41 V for a normalized excitation feed pulse of 1 V and the 3 dB spectral content of the radiated field is between 180 MHz-1.8 GHz. The corresponding results using computer simulations of the UWB system indicate a slightly lesser FoM of 1.1. Higher FoM obtained using the analytical model is due to ignoring the antenna aperture blockage and the field diffraction effects over the TEM feed arms as well as from the rim of the reflector of the antenna. The radiated field amplitude and gain of the HIRA antenna were found to be a direct function of the frequency of the radiated signal. Higher gains and narrower beam width for the radiated field were observed with an increase in the frequency. The radiated field spectral waveform in the near field region was observed to have a notch at a particular frequency and its harmonics. The notch frequency was found to be a function of the propagation time difference called clear time. The effect of pulser rise time, antenna feed arm impedance and position on the radiated far field amplitude and wave shape was analysed. It was observed that with decrease in the pulser rise time from 700 ps to 100 ps, the radiated field amplitude increases by about 600 %. A matched termination impedance with position of 30of the TEM feed arms with respect to the vertical symmetry axis of the antenna provides a higher radiated field amplitude and lower post pulse oscillations in the radiated field waveform. The pulser switch was evaluated systematically for various performance parameters such as BDV, rise time, PRR, voltage recovery and jitter characteristics as a function of switch gas pressure, type of gaseous switching media and breakdown voltage at pressures above and below the atmospheric level. The switch BDV was found to be a linear function of pressure of the gas used i.e. dry air, nitrogen, sulphur hexafluoride (SF6) and a mixture of air and SF6. The measured rise times of all the gases were found to be in inverse proportion to the switch gas pressure. SF6 gas offered the best rise time and hence was found to be a good contender for achieving higher radiated field amplitudes and bandwidth. The voltage recovery characteristics of SF6 gas and air were experimentally studied as a function of the recovery time. It is found that both the gases have similar recovery characteristics having a distinct saturation plateau region. It was found that for a given recovery time SF6 recovers to a higher voltage than air and the recovery further improves for SF6 at increased pressures (between 0.5-2 bar). The effect of the number of switching shots on the jitter in the switch rise time was measured by operating the switch continuously at a PRR of 1 kHz and for total number shots up to 10.8 M. It was observed that the jitter increases by an order of magnitude after 10.8 M shots. This indicates that for the present switch design, the switch electrodes require maintenance (buffing, polishing, etc.) after every 3.5 M shots to maintain a reasonably low jitter. SF6 gas was characterized for a fixed source voltage to determine the effect of pressure on rise time in the sub atmospheric regime (up to 50 mbar). It was found that the rise time vs. pressure characteristics follows the Paschen’s curve with a value of pressure at which rise time is the lowest for a given source voltage. With increase in the source voltage the rise time was found to decrease. The HIRA based UWB radiating system was evaluated for radiated fields in the near and far field region for the temporal and spectral characteristics. It was found that for the source voltage of 25 kV, the FoM in the near and far field region are 29.4 kV and 28.9 kV respectively. The fields in the distant far field region have more oscillatory post pulses due to the effect of ground reflections and the low frequency dipole moment mismatch of the antenna. Since SF6 gas offered the best rise time of 193 ps at a voltage of 46 kV than the other gases tried, the radiated field is the highest (5.3 kV/m) with SF6 at a distance of 10 m offering a gain factor of 1.15. Dry air offered a radiated field gain factor of 0.83 which got improved by 33 % by just 30 % addition of SF6 gas into the air. The field amplitudes measured were in good agreement with those computed using the analytical model and the computer simulations and they follow the 1/R rule as a function of the far field distance, R in the bore sight direction. The measured radiation pattern of the UWB system showed a focussed and narrow radiated field beam at higher frequencies with a half field beam width (HFBW) of 8 at 2 GHz. The UWB system was measured to have dominant highest cut off frequency of 1.79 GHz with a band ratio and percentage band width of 9.56 and 162.11 % respectively. This confirmed that the developed system is of sub-hyper band radiator type. The UWB system developed through this work is having a better performance than some of the other systems developed elsewhere in the world, in terms of FoM (53 kV) and the PRR (> 1 kHz). The system can be further improved in terms of consistency (jitter) and intensity by use of a triggered switch and hydrogen gas at 100 bar pressure as the switching medium respectively. The profile of the TEM feed plates of the HIRA antenna may be further improved to have a better antenna aperture fill factor. Such multiple systems in an arrayed manner may be used either for higher power output/better agility of the radiated field beam. This system will be fully exploited for the applications of susceptibility evaluation of electronic circuits, non-friendly applications as well as impulse radars

<p dir="ltr">X-ray computed tomography (CT) is one of the most widely used imaging modalities for medical diagnosis. Improving the quality of clinical CT images while keeping the X-ray dosage of patients low has been an active area of research. Recently, there have been two major technological advances in the commercial CT systems. The first is the use of Deep Neural Networks (DNN) to denoise and sharpen CT images, and the second is use of photon counting detectors (PCD) which provide higher spectral and spatial resolution compared to the conventional energy-integrating detectors. While both techniques have potential to improve the quality of CT images significantly, there are still challenges to improve the quality further.</p><p dir="ltr"><br></p><p dir="ltr">A denoising or sharpening algorithm for CT images must retain a favorable texture which is critically important for radiologists. However, commonly used methodologies in DNN training produce over-smooth images lacking texture. The lack of texture is a systematic error leading to a biased estimator.</p><p><br></p><p dir="ltr">In the first portion of this thesis, we propose three algorithms to reduce the bias, thereby to retain the favorable texture. The first method proposes a novel approach to designing a loss function that penalizes bias in the image more while training a DNN, producing more texture and detail in results. Our experiments verify that the proposed loss function outperforms the commonly used mean squared error loss function. The second algorithm proposes a novel approach to designing training pairs for a DNN-based sharpener. While conventional sharpeners employ noise-free ground truth producing over-smooth images, the proposed Noise Preserving Sharpening Filter (NPSF) adds appropriately scaled noise to both the input and the ground truth to keep the noise texture in the sharpened result similar to that of the input. Our evaluations show that the NPSF can sharpen noisy images while producing desired noise level and texture. The above two algorithms merely control the amount of texture retained and are not designed to produce texture that matches to a target texture. A Generative Adversarial Network (GAN) can produce the target texture. However, naive application of GANs can introduce inaccurate or even unreal image detail. Therefore, we propose a Texture Matching GAN (TMGAN) that uses parallel generators to separate anatomical features from the generated texture, which allows the GAN to be trained to match the target texture without directly affecting the underlying CT image. We demonstrate that TMGAN generates enhanced image quality while also producing texture that is desirable for clinical application.</p><p><br></p><p dir="ltr">In the second portion of this research, we propose a novel algorithm for the optimal statistical processing of photon-counting detector data for CT reconstruction. Current reconstruction and material decomposition algorithms for photon counting CT are not able to utilize simultaneously both the measured spectral information and advanced prior models. We propose a modular framework based on Multi-Agent Consensus Equilibrium (MACE) to obtain material decomposition and reconstructions using the PCD data. Our method employs a detector agent that uses PCD measurements to update an estimate along with a prior agent that enforces both physical and empirical knowledge about the material-decomposed sinograms. Importantly, the modular framework allows the two agents to be designed and optimized independently. Our evaluations on simulated data show promising results.</p>