Magister Artium - MA / A favourable school atmosphere, in which adolescents behave positively, is one of the greatest concerns for teachers, administrators and parents. Although there are several different pressures leading to adolescent misbehaviour at school, the most contributing factors are peer pressure and the socio-economic status of the school. As adolescents enter the school, the peer group then functions as an important socializing agent for them. As peers socialize within their different school environments, individuals are forced to conform to the practices and opinions of the group. Usually this conformity is unconstructive and clashes with the parents' and teachers' expectations. The aim of this study was to examine the influence of peer pressure on adolescent misbehaviour in advantaged and disadvantaged schools. A quantitative methodological approach was used to conduct the study. The study was conducted with adolescents aged from 13 to 17 years in both advantaged and disadvantaged secondary (high) schools in Windhoek, Namibia. A sample of 300 participants was randomly stratified across the schools. The Exposure to Peer Pressure Control Scale (Allen & Yen, 2002) a) and Child Behaviour Checklist questionnaires (Achenbach & Edelbrock, 1987) were used to collect the data. Ethical considerations were carefully considered before and during the research procedure of data collection. The reliability of the instruments was checked by means of a pilot study. The data was analysed by means of the Statistical Package for Social Sciences (SPSS) version 18 to reveal descriptive and inferential statistics. Results showed a significant positive relationship between peer pressure and adolescent misbehaviour in schools. In addition, misbehaviour was also positively predicted in both advantaged and disadvantaged schools, with disadvantaged schools being significantly more influential. When comparing peer pressure and adolescent misbehaviours in both advantaged and disadvantaged schools, adolescents in advantaged schools engaged significantly more in misbehaviour activities and also responded positively more to peer pressure than their counterparts in advantaged schools. Implications for further research were suggested. / South Africa

Heat generation during the FTSW process plays and important role in determining the characteristics of the weld. In order to obtain temperature fields, a transient temperature heat analysis is required. An area is the maximum temperatures reached within the base material during the FTSW process. These temperatures will be measured during experimentation, and compared to the welding simulation done using FEA. From the literature search it appeared that no heat transfer analysis had been done using finite element methods.

During the past two summers at the Institute of Oceanography of the University of British Columbia a research group has been involved in an experimental programme studying the interaction between the air and the sea close to the ocean surface. To date instruments have been developed and used to measure the vertical flux of momentum and the waves on the water surface. The observational site is situated on the tidal flat, Spanish Banks, in Burrard Inlet. Though the fetch is limited measurements are considered to be representative of the air flow close to the sea surface. The most important influence driving the ocean circulation is thought to be the momentum transferred through the atmospheric boundary layer. Although quantities such as heat and water vapour are also transferred, this thesis concerns only the transport of momentum. From profiles of wind speed measured over the sea at six heights up to five meters the downward transport of momentum is deduced. Whenever possible this momentum transport is compared to other estimations of this quantity, obtained by means of the hot wire anemometer. The various conditions of atmospheric stability are recorded and used in association with wind profile studies. Another important aspect of the wind profile study of this thesis is to determine the optimum averaging time for wind speeds in order that they may give meaningful estimates of the vertical transport of momentum. Furthermore, wind profiles are compared critically for fluctuating winds of approximately ten minute duration with the hope of discovering the influence of waves on the air flow close to the surface. The surface drag coefficients are inferred from the wind profiles and results are compared to those of other workers. The influence of the other measured variables on drag coefficients, such as wind speed, stability, and fetch, is studied. Several spectra of the low frequency downwind velocity fluctuations are computed and these results are compared with the spectra obtained by other workers and in addition with a hot wire anemometer spectrum. For one run enough 10 second-averaged velocities are available to calculate, with a reasonable degree of certainty, the statistics of the distribution of the downwind velocity components. The results from the past two summers presented in this thesis should be regarded as a preliminary investigation of some of the physical processes of air-sea interaction. By no means all the determining factors as yet have been successfully measured. At this stage a more thorough understanding of the behaviour of the instruments for measuring the transfer of momentum and a preliminary understanding of the physical processes involved has been gained. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The use of the photoelastic coating method in determining the stresses in the torispherical head of a pressure vessel was investigated. It was found that the method is valuable to obtain the distribution, direction, and magnitude of stresses on the surface of any structure. The results obtained with the method showed close agreement with the theoretical investigations. The maximum stresses in a torispherical head of a pressure vessel occur in the torus. The same conclusion was drawn from the results obtained with the method. It also revealed, that these stresses were compressive on the outer surface. The mobility of the instruments, the relatively simple way of coating the surface of the structure are other features of the method. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

This thesis work presents the analysis of Oscillometric blood pressure pulse waveform under different pressure points (Systolic, Mean Arterial, and Diastolic Pressures). Pulse waveforms' characteristics were determined from the waveforms at three different pressures and are compared for subjects at three different age groups. Estimation of blood pressure using a morphology based approach was done by using the change of pulse waveform characteristics at different pressure points. Pulse waveforms' characteristics that were obtained from pulse waveforms are utilized to estimate SBP, MAP, and DBP. The estimates obtained with pulse morphology based technique are compared with a BP measurement device and Maximum Amplitude Algorithm. Maximum slope of the pulse was also used for blood pressure estimation. The effect of movement and breathing on proposed method and MAA were compared and it was observed that breathing artifacts affect less the proposed method.

The Full-Displacement Pressuremeter (FDPM) Test is one in which a pressuremeter is installed in the soil by pushing it behind a conical tip. Earlier work had indicated that the unload-reload modulus measured with the FDPM was very similar to that obtained from self-boring pressuremeter (SBPM) testing. It had also been suggested that if the pressuremeter was capable of sufficient expansion, the interpreted soil properties would be those of the soil beyond the zone of disturbance. This study examined the factors affecting the measurement, analysis and interpretation of soil properties from FDPM pressure-expansion curves in sands with emphasis on the unload-reload modulus. The effects of equipment design and dimensions, installation method and of test procedure on the analysis and interpretation of lateral stress, shear strength and stiffness were studied during laboratory and field evaluation of two prototype FDPMs. The overwhelming importance of instrument dimensions and tolerances on the test results was clearly shown. Movements of a fraction of a millimetre can have a large effect on the measured lateral stress and stiffness. Test procedures were also shown to have a large effect on the data obtained. It was demonstrated that rate effects became important in pressuremeter tests involving expansion to large strains and a stress-strain strain rate concept was proposed to aid in the understanding of these effects. Theories developed for the interpretation of shear strength of sands from SBPM tests were shown to be inapplicable to the interpretation of FDPM test results. The unload-reload modulus was shown to be an indicator of soil stiffness but the effects of stress level and degree of unloading have to be considered when attempting to derive a stiffness for design. A rational approach to the interpretation of modulus was presented and it was shown that unload-reload moduli from both SBPM and FDPM could be interpreted using the same approach. The need for standardising the equipment design, testing procedures and methods of analysis and interpretation was shown. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The purpose of this study was to examine the types of pressures adolescents experience. The factors of age and/or gender were also investigated in order to determine any possible effects upon adolescent experienced pressures. The researcher believed that findings from such a study could be useful to high school counsellors in both planning future Guidance programs for adolescents as well as aiding in individual counselling sessions with their adolescent clients. Using a cluster-sampling technique, 505 adolescents were selected from a Vancouver high school. Subjects were chosen with consideration to the factors of age and gender. The researcher designed an open-form measurement instrument intended to gather adolescent responses to the three greatest pressures they had experienced during the previous four months. Following a pilot of the instrument, which was to aid in determining construct validity, the survey was administered to the sample over an eight day testing period. With the initial help of an assistant, responses were content analyzed and initial categories constructed. All responses were coded and assigned a frequency score to one of eleven mutually exclusive categories. The chi-square "Goodness of Fit" test for significant difference between or among groups was then applied. Results of the statistical analysis indicated that the factors of age and/or gender are related to certain types of pressures experienced by adolescents. Future Pressure was found to be a significant pressure experienced by older age adolescents. Regardless of gender, age appears to be an important factor related to who will experience Future Pressure. Female adolescents experience greater Family Pressure than do males. Whether within the same age group or within a total female and. a total male population comparison, this result remains consistent. Younger age adolescents also indicate greater gender differences compared with older age adolescents. Younger age female adolescents are more likely to experience greater Family Pressure and Peer Pressure while young male adolescents are more likely to experience greater Situational Pressure. In conclusion, it appears that significant gender differences found in this study tend to support the notion that differences in the rate of physical growth as well as learned sexual stereotypes are significant factors in determining such differences. / Education, Faculty of / Educational and Counselling Psychology, and Special Education (ECPS), Department of / Graduate

The response of a polyatomic gas to microwave radiation including both steady state (pressure broadening) and time dependent (coherence transients) effects - is described theoretically. The treatment is based on solutions of a quantum mechanical Boltzmahn equation and employs kinetic theory methods which have previously been used in the explanation of the field dependence of transport phenomena (Senftleben-Beenakker effects). Much of the recent theoretical work of pressure broadening and coherence transient phenomena is based on a two (energy) state model for the gas molecules. This model, when developed from a density operator point of view, results in a coupled set of three equations which are mathematically equivalent to the Bloch equations of NMR. The present work reexamines this description, and replaces it with a two level model for the gas system. Here, the term "level" implies explicit consideration of the rotational (magnetic) degeneracy associated with each energy state. This model gives a more appropriate representation of the interaction of microwave radiation with a real molecular system. In particular, a more complete set of coupled equations result from this description and involve quantities in addition to the three moments used in a two state approach. The most important of these latter effects are represented by spherical harmonics Ƴ(q) (J) in he angular momentum J of the relevant energy levels. An analogous treatment of rotational effects has previously been used in Senftleben-Beenakker studies. Specific molecular types of interest in microwave spectroscopy -diamagnetic diatonics and linear polyatomics, symmetric tops, and inverting symmetric tops - are treated separately by this two level approach. The vector (and tensor) nature of the motions are emphasized throughout. The number of rotational polarizations that arise in the general two level case is often quite large. The simplest example of a two level system is the j=0 to j=l transition of a diamagnetic diatomic. This is studied in some detail. Here, the scalar component Ƴ⁽²⁾⁰(J) is the only rotational polarization affected by linearly polarized radiation in the usual experiments. The effect of this quantity on both steady state and transient phenomena is described, and a new "combination" experiment is suggested as the best way to detect the presence of this additional polarization. The Doppler effect is treated by appropriately including the effects of translational motion in the quantum Boltzmann equation. A more general set of coupled moment equations then results, and the manner in which the macroscopic velocity polarizations arise is thereby established. A model method solution of the quantum Boltzmann equation, emphasizing the parity invariance of the collision super-operator, is given for a steady state absorption experiment in the absence of saturation but including Doppler effects. Throughout this thesis, the relaxation rates, are related to kinetic theory collision cross sections by solving the quantum Boltzmann equation. Extensive use is made of rotational invariance to reduce the number of independent collision integrals, and their approximate evaluation is accomplished within the context of the distorted wave Born approximation. All collision integrals for the pure internal state polarizations are found to-be expressible in terms of one translational factor, which is itself further approximated by a modified Born approximation. Correspondingly, the translational factor which arises in the relaxation of macroscopic velocity polarizations is completely specified by relating it to the Ω(ℓ,s) integrals of traditional kinetic theory. / Science, Faculty of / Chemistry, Department of / Graduate

MPH / Department of Public Health

Blood pressure is one of the most important indicators of human health. The symptoms of many cardiovascular diseases like stroke, atrial fibrillation, and acute myocardial infarction are usually indicated by the abnormal variation of blood pressure. Severe symptoms of diseases like coronary syndrome, rheumatic heart disease, arterial aneurysm, and endocarditis also usually appear along with the variation of blood pressure. Most of the current blood pressure measurements rely on the Korotkoff sounds method that focuses on one-time blood pressure measuring but cannot supervise blood pressure continuously, which cannot effectively detect diseases or alert patients. Previous researches indicating the relationship between photoplethysmogram (PPG) signal and blood pressure brought up the new research direction of blood pressure measurement method. Ideally, with the continuous supervision of the PPG signal, the blood pressure of the subject could be measured longitudinally, which matches the current requirements of blood pressure measurement better as an indicator of human health. However, the relationship between blood pressure and PPG signal is very comprehensive that is related to personal and environmental status, which leads to the research challenge for many previous works that tried to find the mapping from PPG signal to blood pressure without considering other factors. In this thesis, we propose two statistical methods modeling the comprehensive relationships among blood pressure, PPG signals, and other factors for blood pressure prediction. We also express the modeling and predicting process for the real data set and provide accurate prediction results that achieve the international blood pressure measurement standard. In the first part, we propose the Independent Variance Components Mixed- model (IVCM) that introduces the variance components to describe the relationship among observations. The relationship indicators are collected as information to divide observations into different groups. The latent impacts from the properties of groups are estimated and used for predicting the multiple responses. The Stochastic Approximation Minorization-maximization (SAM) algorithm is used for IVCM model parameter estimation. As the expansion of Minorization-maximization (MM) algorithm, the SAM algorithm could provide comparable-level estimations as MM algorithm but with faster computing speed and less computational cost. We also provide the subsampling prediction method for IVCM model prediction that could predict multiple responses variables with the conditional expectation of the model random effects. The prediction speed of the subsampling method is as fast as the SAM algorithm for parameter estimation with very small accuracy loss. Because the SAM algorithm and subsampling prediction method requires assigning tuning parameters, a great amount of simulation results are provided for the tuning parameter selection. In the second part, we propose the Groupwise Reweighted Mixed-model (GRM) to describe the variation of random effects as well as the potential components of mixture distributions. In the model, we combine the properties of mixed-model and mixture model for modeling the comprehensive relationship among observations as well as between the predictive variables and the response variables. We bring up the Groupwise Expectation Minorization-maximization (GEM) algorithm for the model parameter estimation. Developed from MM algorithm and Expectation Maximization (EM) algorithm, the algorithm estimates parameters fast and accurate with adopting the properties of the diagonal blocked matrix. The corresponding prediction method for GRM model is provided as well as the simulations for the number of components selection. In the third part, we apply the IVCM model and the GRM model in modeling real data and predicting blood pressure. We establish the database for modeling blood pressure with PPG signals and personal characteristics, extract PPG features from PPG signal waves, and analyze the comprehensive relationship between PPG signal and blood pressure with the IVCM model and the GRM model. The blood pressure prediction results from different models are provided and compared. The best prediction results not only achieve the international blood pressure measurement standard but also show great performance in high blood pressure prediction