241 |
Latent variable modelling of personality-health associations : measures, models and extensionsHagger-Johnson, Gareth January 2008 (has links)
Functional health status, morbidity and mortality are determined partly by health behaviours (World Health Organization, 2002), which have determinants of their own. Personality traits, such as Conscientiousness, have a strong association with health behaviours (Bogg & Roberts, 2004). There is a less consistent and generally weaker association between traits and health outcomes (e.g. Neuroticism and mortality). The central problem in this thesis is how to measure, model, maximize, and extend trait-health associations. Conceptual issues associated with modelling traits and health are discussed in chapter one. The next three chapters concern such measurement issues about: personality traits (chapter two), health behaviours (chapter three) and health outcomes, with particular reference to functional health status (chapter four). These chapters are followed by a move to modelling (chapter five), with particular reference to the generalized latent variable modelling (LVM) framework (Muth´en & Muth´en, 1998–2007). The HAPPLE study is introduced (chapter six) which is used to model associations between Conscientiousness and health criteria within the LVMframework (chapter seven). Moving beyond self-reported outcomes, which are a mono-method approach, the role of multiple health behaviours in predicting cardiovascular mortality is considered (chapter eight). In a third section, cortisol is introduced, which is a biomarker of stress reactivity. The diurnal profile of cortisol output is described (chapter nine). Latent growth curve modelling is used to illustrate its association with Neuroticism, in a sample of student volunteers (chapter 10). Taken together, the results highlight the need for a general framework of modelling techniques, in personality-health research. I conclude that biopsychosocial models with excellent explanatory power, which are still parsimonious, can be achieved with LVM and its extensions. However, trait researchers will need to state more clearly the intended destinations of their work in order to attract contributions from, and share knowledge with, other disciplines.
|
242 |
Integrating Variable Rate Technologies for Soil-applied Herbicides in Arizona Vegetable ProductionNolte, Kurt, Siemens, Mark C., Andrade-Sanchez, Pedro 02 1900 (has links)
5 pp. / Precision herbicide application is an effective tool for placing soil incorporated herbicides which have a tendency for soil adherence. And while field implementation depends on previous knowledge of soil textural variability (soil test and texture evaluations), site-specific technologies show promise for Arizona vegetable producers in non-uniform soils. Regardless of the method used for textural characterization, growers should keep in mind that textural differences do not change in the short/medium term, so the costs associated with defining texture-based management zones can be spread over many years.
|
243 |
Modelling and Performance Evaluation of the Virtual Air Gap Variable ReactorDolan, Dale 24 September 2009 (has links)
This thesis describes a novel device, the Virtual Air Gap Variable Reactor (VAG-VR), which is capable of producing a continuously
variable reactance by locally saturating a small section of the reactor core via an embedded dc control winding. Variable Reactors have many applications in the power industry such as control of line power flow, voltage regulation, reactive line compensation and limiting inrush currents. A variable reactor is most commonly implemented as a thyristor controlled reactor (TCR) by switching in and out a constant reactance to achieve an averaged variable reactance. By using a virtual air gap, a continuously variable reactance is possible. The VAG-VR offers a better dynamic response, without introducing the harmonics created by the thyristor switching of a TCR. The VAG-VR gives low triplen harmonics and therefore allows control of reactive power in single phase or unbalanced three phase systems as would be required in the distribution system.
An experimental prototype VAG-VR was developed to investigate three main performance measures: steady state performance, dynamic response and harmonic performance. Over the operating range of the VAG-VR inductance was varied from 100% to 9% of its original value. The dynamic response of the VAG-VR is approximately one tenth of a cycle. This compares favorably to a TCR which responds in approximately half a cycle. Harmonics are also shown to be significantly reduced in the VAG-VR compared to the TCR.
A dynamic model of the VAG-VR, suitable for incorporation into power system simulations, was developed and validated. Parameters were determined both experimentally and through finite element method (FEM) simulations. Both experimental and simulation results indicate that the VAG-VR offers a technically viable alternative to the TCR.
|
244 |
Broadband Low-Noise CMOS Mixers For Wireless CommunicationsJiang, FAN 03 October 2013 (has links)
In this thesis, three broadband low-noise mixing circuits which use CMOS 130 nm technology are presented. As one of the first few stages in a receiving front-end, stringent requirements are posted on mixer performance. The Gilbert cell mixers have presented excellent properties and achieved wide applications. However, the noise of a conventional active Gilbert cell mixer is high. This thesis demonstrates both passive and active mixing circuits with improved noise performance while maintaining the advantages of the Gilbert cell-based mixing core. Furthermore, wide bandwidth and variable gain are implemented, making the designed mixers multi-functional, yet with compact sizes and low power consumptions.
The first circuit is a passive 2x subharmonic mixer that works from 4.5 GHz to 8.5 GHz. The subharmonic mixing core is a two-stage passive Gilbert cell driven by a quadrature LO signal. Together with a noise-cancelling transconductor and an inverter-based TIA, this subharmonic mixer possesses an excellent broadband conversion gain and a low noise figure. Measurement results show a high conversion gain of 16 dB and a low average DSB NF of 9 dB.
The second design is a broadband low-noise variable gain mixer which operates between 1 and 6 GHz. The transconductor stage is implemented with noise cancellation and current bleeding techniques. Series inductive peaking is used to extend the bandwidth. Gain variation is achieved by a current-steering IF stage. Measurements show a wide gain control range of 13 dB and a low noise performance over the entire frequency and gain range. The lowest DSB NF is 3.8 dB and the highest DSB NF is 14.2 dB.
The Third design is a broadband low-noise mixer with linear-in-dB gain control scheme. Using the same transconductance stage with the second circuit, this design also works from 1 to 6 GHz. A 10 dB linear-in-dB gain control range is achieved using an R-r load network with a linear-in-dB error less than $\pm$ 0.5 dB. Low noise performance is achieved. For different frequencies and conversion gains, the lowest DSB NF is 3.8 dB and the highest DSB NF is 12 dB. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-10-02 04:37:31.606
|
245 |
Spectroscopie de luminescence à température et pression variables pour des complexes des lanthanides et de l'orIntissar, Mourad 11 1900 (has links)
Ce travail est axé vers la compréhension détaillée des propriétés de luminescence de composés de certains métaux lourds. La première partie de ce mémoire décrit la caractérisation spectroscopique d'un radical de type nitronyle nitroxyde, 2-(2-pyridinyl)-4,4,5,5-tétraméthyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxyde, abrégé (NIT2-Py), et de ses complexes avec les cations Tb(III), [Tb(hfac)3NIT2-Py], et Y(III), [Y(hfac)3NIT2-Py]. La variation de la température affecte les spectres de luminescence qui montrent de la structure vibronique résolue. Les maxima de ces transitions vibroniques se rapprochent au fur et à mesure que la température augmente. Ces variations des maxima en fonction de la température ne correspondent pas à des variations de fréquences vibrationnelles et sont de l'ordre de 200 cm-1 entre 80 K et 240 K. La variation de la température n'a pas d'influence significative sur la structure moléculaire, comme atteste la variation mineure des maxima des spectres Raman entre 80 K et 300 K. La comparaison des spectres expérimentaux à des spectres calculés montre que ces variations peuvent être reproduites par l'utilisation d'une combinaison de fréquences vibrationnelles. Le paramètre dont la variation est très significative est la résolution du spectre de luminescence, représentée par la largeur à mi-hauteur des transitions vibroniques qui forment le spectre de luminescence. La deuxième partie de ce mémoire décrit les propriétés de luminescence d'une série de complexes d’or(I). Elles sont comparées aux changements structuraux à pression et température variable. Les interactions aurophiles ont une grande influence sur la luminescence. La variation de la température et de la pression est une approche efficace pour varier la luminescence. Les effets observés dans les spectres d'émission de ces complexes dépendent des changements de structure induits par variation de la température et de la pression. Ces petites variations structurales mènent à des changements importants, à titre d'exemple à un déplacement du maximum de la bande de luminescence de 60 cm-1/ kbar vers les faibles énergies pour un des complexes de l'or(I) étudiés au cours de ce projet. / The overall goal of this work is to contribute to the understanding of luminescence properties of transition metal compounds. The first part of this thesis describes the spectroscopic characterization of a pyridine-substituted nitronyl nitroxyde radical 2-(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-3-oxide-1-oxyl abbreviated (NIT2-Py) and its complexes with Tb(III) and Y(III), [Tb(hfac)3NIT2-Py] and [Y(hfac)3NIT2-Py], respectively. Their luminescence spectrum show resolved vibronic structure and variations with temperature The energy difference between vibronic luminescence maxima decreases with increasing temperature. This decrease is on the order of 200 cm-1 between 80 K and 240 K and is not due to decreasing Raman frequencies. The variations of temperature do not have a significant influence on the molecular structures, as illustrated by the very small variation of Raman maxima between 80 K and 300 K. Luminescence spectra were calculated using the time dependent theory of spectroscopy. Calculated luminescence spectra show that the variations with temperature are reproduced by using specific combinations of experimental frequencies and by adjusting the width of the vibronic transitions, determining the resolution of the luminescence spectrum. The second part of the thesis describes the luminescence spectroscopic properties of a series of trimetallic gold(I) complexes at variable temperature and pressure. Aurophilic interactions are very important for these compounds and influence the luminescence spectra. The spectroscopic features are compared to structural changes at variable temperature and pressure. Even small changes in structure lead to significant changes in luminescence, for example a shift of the maximum of the luminescence band by 60 cm-1/ kbar to lower energy for one of the gold(I) complexes studied.
|
246 |
An evaluation of ISISBodee, Bradley Robert 03 May 2014 (has links)
ISIS is a program that specializes in detecting variable stars within clusters, both open and
globular. ISIS has historically been used in surveys searching for variable stars. However,
recent work has identified new uses for ISIS, such as the detection of exoplanet transits in
clusters of stars. This thesis will evaluate ISIS, both how the program functions and for which
objects it is most efficient and appropriate. I examined five clusters: three open, and two
globular, for one night surveys. With this survey, I identified twenty-five variable stars.
Twenty-two variables were previously known, and three variable stars were previously
undiscovered. In total, from my short one night surveys, I confirmed twenty-five previously
known variable stars and four unknown variable stars. Furthermore, ISIS has detected several δ
Scuti stars whose amplitude of variation is on par with an exoplanet transit. These data suggest
that ISIS can be used for the detection of exoplanet transits. / Department of Physics and Astronomy
|
247 |
Les impacts de la satisfaction envers les régimes de rémunération variable sur l’engagement organisationnel des travailleursLavoie, Émilie 08 1900 (has links)
Ce mémoire a pour objectif de comprendre l’impact de la satisfaction envers les régimes de rémunération variable sur l’engagement organisationnel des travailleurs. Pour étudier cette question, nous avons utilisé trois hypothèses basées sur la théorie des attentes ainsi que sur la théorie de l’agence. La première hypothèse stipule que la satisfaction envers les régimes de bonis fait augmenter le niveau d’engagement organisationnel des travailleurs. La deuxième hypothèse est que la satisfaction envers les régimes de partage des bénéfices fait augmenter le niveau d’engagement organisationnel des travailleurs. La troisième hypothèse stipule que la satisfaction envers les régimes d’actionnariat fait augmenter le niveau d’engagement organisationnel des travailleurs.
Nous avons utilisé une base de données provenant d’une enquête plus large portant sur « les liens entre la rémunération, la formation et le développement des compétences et l’attraction et la rétention d’employés clés ». L’entreprise où les données ont été collectées œuvre dans le secteur des technologies de l’information et des communications (TIC). Les nouveaux employés embauchés dans cette entreprise établie à Montréal ont été interrogés.
Nos résultats nous permettent de confirmer deux de nos hypothèses, soit celle qui concerne les régimes de bonis et celle qui concerne les régimes d’actionnariat. Nos résultats indiquent que les individus satisfaits à l’égard des régimes de rémunération variable, plus précisément envers les régimes de bonis et les régimes d’actionnariat, présentent de plus hauts niveaux d’engagement organisationnel. Le soutien organisationnel perçu est également un facteur important dans le développement de l’engagement organisationnel.
Finalement, nous concluons ce mémoire avec l’implication de nos résultats pour les différents acteurs en relations industrielles. / The objective of this study is to understand the impact of the satisfaction with variable pay plans on organizational commitment of workers. To investigate this question, we used three hypotheses based on the theory of expectations and on the agency theory. The first hypothesis states that satisfaction with bonus plans increases the level of affective organizational commitment of workers. The second hypothesis is that satisfaction with profit-sharing plans increases the level of affective organizational commitment of workers. The third hypothesis states that satisfaction with stock ownership plans increases the level of affective organizational commitment of workers.
We used a database from a wider survey on "the links between compensation, training and skills development and attracting and retaining key employees." The company where the data was collected is in the field of information technology and communications. New employees hired in this company based in Montreal were interviewed.
Our results allow us to confirm two of our hypotheses. Our results indicate that individuals satisfied with variable pay plans, more precisely towards the bonus plans and stock ownership plans, have higher levels of organizational commitment. Perceived organizational support is also an important factor in the development of organizational commitment.
Finally, this study concludes with the implication of our results for the different actors in industrial relations.
|
248 |
La stratégie d'entreprise et la présence de rémunération variable dans le secteur syndiqué au QuébecGilbert, Guillaume January 2006 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
|
249 |
In vivo cytochrome P450 activity alterations in diabetic nonalcoholic steatohepatitis miceLi, Hui, Clarke, John D., Dzierlenga, Anika L., Bear, John, Goedken, Michael J., Cherrington, Nathan J. 02 1900 (has links)
Nonalcoholic steatohepatitis (NASH) has been identified as a source of significant inter individual variation in drug metabolism. A previous ex vivo study demonstrated significant changes in hepatic Cytochrome P450 (CYP) activity in human NASH. This study evaluated the in vivo activities of multiple CYP isoforms simultaneously in prominent diabetic NASH mouse models. The pharmacokinetics of CYP selective substrates: caffeine, losartan, and omeprazole changed significantly in a diabetic NASH mouse model, indicating attenuation of the activity of Cyp1a2 and Cyp2c29, respectively. Decreased mRNA expression of Cyp1a2 and Cyp2c29, as well as an overall decrease in CYP protein expression, was found in the diabetic NASH mice. Overall, these data suggest that the diabetic NASH model only partially recapitulates the human ex vivo CYP alteration pattern. Therefore, in vivo determination of the effects of NASH on CYP activity should be conducted in human, and more appropriate models are required for future drug metabolism studies in NASH.
|
250 |
Some statistical methods for dimension reductionAl-Kenani, Ali J. Kadhim January 2013 (has links)
The aim of the work in this thesis is to carry out dimension reduction (DR) for high dimensional (HD) data by using statistical methods for variable selection, feature extraction and a combination of the two. In Chapter 2, the DR is carried out through robust feature extraction. Robust canonical correlation (RCCA) methods have been proposed. In the correlation matrix of canonical correlation analysis (CCA), we suggest that the Pearson correlation should be substituted by robust correlation measures in order to obtain robust correlation matrices. These matrices have been employed for producing RCCA. Moreover, the classical covariance matrix has been substituted by robust estimators for multivariate location and dispersion in order to get RCCA. In Chapter 3 and 4, the DR is carried out by combining the ideas of variable selection using regularisation methods with feature extraction, through the minimum average variance estimator (MAVE) and single index quantile regression (SIQ) methods, respectively. In particular, we extend the sparse MAVE (SMAVE) reported in (Wang and Yin, 2008) by combining the MAVE loss function with different regularisation penalties in Chapter 3. An extension of the SIQ of Wu et al. (2010) by considering different regularisation penalties is proposed in Chapter 4. In Chapter 5, the DR is done through variable selection under Bayesian framework. A flexible Bayesian framework for regularisation in quantile regression (QR) model has been proposed. This work is different from Bayesian Lasso quantile regression (BLQR), employing the asymmetric Laplace error distribution (ALD). The error distribution is assumed to be an infinite mixture of Gaussian (IMG) densities.
|
Page generated in 0.0515 seconds