VictorJuiz/thesis huggingface dataset:
A new method for the non-invasive measurement of cardiac output during spontaneous ventilation

Introduction. All respiratory-based methods of measuring cardiac output depend on imposing a step-change in alveolar ventilation (V˙ A) for a particular gas. For CO2, this can be accomplished by interposing respiratory deadspace in the breathing circuit, but therefore requires a uniform breathing pattern. I developed a method of reducing V˙ A that is independent of breathing pattern using a new breathing circuit. I evaluated this method's accuracy by comparing its measurements (QNI ) with those of thermodilution (QTD) on cardiac patients in the ICU, as well as its precision by performing repeated tests on subjects in a laboratory. Methods. I conducted 3 validation studies involving 89 post cardiac surgery patients in the ICU after extubation. The reduction in V˙A was induced by a step reduction in gas flow to the circuit. The balance of ventilation was composed of previously exhaled gas and no respiratory manoeuvre was required by the patient. QTD was measured simultaneously. I also conducted measurements to evaluate precision by performing 8 repeated tests on 24 subjects in a laboratory setting. Results. In my final validation study, QNI was highly correlated with QTD (R = 0.90) despite a wide range of breathing patterns. The bias and precision of the non-invasive method were 0.08 and 0.80 L/min, respectively. The repeatability of QNI, measured as the SD of repeated tests, was 0.73 L/min, which is slightly less that the repeatability of QTD, which is usually reported as 0.60 L/min. Conclusion. I have developed and tested a new method for measuring cardiac output noninvasively in spontaneously breathing subjects. Although measures to improve accuracy are still needed, our method correlated well with thermodilution and may eventually provide physicians with a new, clinically useful, non-invasive test.

Advisor: Fisher, Joseph
Parental Discipline and Child Abuse

This thesis demonstrates the explanatory benefits that derive from reconceptualising child abuse as a form of child discipline. By testing five theories of child discipline on data derived from a random sample of Toronto families, it is shown that various styles of child discipline--labelled violent, mixed and proactive-- are influenced to varying degrees by different subsets of causes, and that the importance of different subsets of causes varies by parent's gender. Methodological and practical issues pertaining to the study and prevention of child abuse are also discussed. Specifically, the thesis shows that: (1) The important factors determining the use of violent disciplining by mothers are belief in the efficacy of physical punishment and family income. Only employment status was able to explain variation in the fathers' use of a violent discipline style. (2) In the case of the proactive, positive discipline pattern, there is a strong social learning component. Childhood experience with proactive discipline is the single most important predictive factor for both mothers and fathers. Fathers who work fewer hours are also more likely to use a proactive discipline style. (3) The intergenerational transmission of discipline patterns further accounts for the greatest amount of variation in the fathers' use of the mixed style. Scores also increase according to the amount of time that fathers spend with their children. In the case of the mothers, the important factors were number of hours employed, belief in the efficacy of physical punishment, and whether the mother was raised with this style as a child.

Keywords: Social sciences
Personal relationships
Family
Sociology
Advisor: Eichler, Margrit
Stability of an equatorial jet and the formation of cyclone twins

It has been observed that equatorial cyclone twins (ECTs), which may be a triggering factor for El Nino events, are usually preceded by powerful jet-like westerly wind bursts. These bell-shaped profiles are usually modelled (in a rather arbitrary manner) as being Gaussian or sinusoidal in shape. These types of profiles are generally barotropically unstable to infinitesimal perturbations in the most common linearized geophysical models, be they quasigeostrophic, shallow water, or Boussinesq, but the structures of the instabilities are very different from what would be required to trigger an ECT. A more generalized wind flow, however, can lead to growing modes with symmetric lows across the equator that are similar to ECTs. The instabilities may be understood in term s of the wave resonance theory, in which neutral waves (which may be induced by shear, background vorticity, gravity, or some other restoring mechanism) can phase-lock and grow in order to destabilize the flow.

Keywords: Physics
Electroconvection in sheared annular fluid films

Annular electroconvection in freely suspended thin fluid films undergoing circular Couette flow is a novel nonlinear system which, in this thesis, conies under experimental and theoretical scrutiny. Its novel features, which stem from its geometry and its electrohydrodynamic character, include the superposition of an azimuthal shear flow with a radial electrically driven hydrodynamic instability in a two-dimensional, naturally periodic system. Concentric circular electrodes support a weakly conducting annular fluid film which electroconvects when a sufficiently large voltage V is applied between its inner and outer edges. Dyrotation of the inner edge, a Couette shear is imposed. The control parameters are a Rayleigh-like number R x V(2) and the Reynolds number Re of the azimuthal shear. The geometrical and material properties of the film are characterized by the radius ratio a = r1/r0, where r1(ro) is the radius of the inner (outer) electrode and a Prandtl-like number P. The electroconvective flow whose onset occurs when R = R c is described by a nonaxisym metric mode number mc and a traveling rate 7e. The dependence of Rc Mc, 7e c on a,V, R e has been investigated theoretically by linear stability analysis. Experimental measurements of current-voltage data were used to determine the onset of electroconvection over a broad range of a, P and Re.These are compared with the theoretical predictions. The current-voltage d a ta were used to infer the amplitude of convection in the weakly nonlinear regime by fitting to a steady-state amplitude equation with a lowest order cubic nonlinearity with coefficient g. Results for g as a function of a, P and Re are reported. Under various conditions, the primary bifurcation can be supercritical (g>0), tricritical (g=0) or subcritical(g<0). Above onset, numerous subcritical secondary bifurcations, that m ark transitions from one flow pattern to another, were encountered. A sampling of bifurcation scenarios is presented and their Re dependence is studied.

Keywords: Physics
Advisor: Deyirmenjian, Vatche
Photoproton Reactions In Medium-Weight Nuclei

The angular distributions, energy spectra and integrated yields of photoprotons were measured for nine medium-weight nuclei with atomic number between 28 and 50 in order to test the predictions of the Independent Particle Model of nuclear photodisintegration. Thin metallic foils of natural isotopic abundance were irradiated with a bremsstahlung spectrum of energy 22 MeV. The photoprotons emitted by the targets were detected at angles of 45, 60, 90, 120 and 145 degrees with respect to the direction of the photon beam by means of silicon surface barrier detectors. By using pulse amplitude discrimination, pulse heights from the intense electron background were kept below the level of a four MeV proton for most of the target elements. The detection system was calibrated for energy with the alpha particles from a Ra source. Photoproton energy spectra were thus obtained at each of the five angles of observation for each of the nine target elements. The results of the measurements are discussed in terms of the "resonance direct" interaction theory of Wilkinson. It is found that some extensions to this model are required to explain the experimental data.

Keywords: Physics
Advisor: Prentice, J.D.
Dynamic topography of continents and rotational stability of planets with lithospheres

This thesis examines two distinct topics related to the long-term evolution of terrestrial planets. The first, dynamic topography, is the vertical motion of the Earth’s tectonic plates in response to viscous stresses in the mantle driven by connective processes. Using mantle flow modelling, I show how dynamic topography linked to plate subduction can explain a long-wavelength component of sediment deposition in the Silurian Baltic Basin. Simulations constrain the paleo-dip angle of subuction to 40-60 degrees and show that the slab-induced mantle flow mechanism provides 40-85% of the near-field sediment deposition. In another regional study, I use convection simulations constrained by seisemic tomography to reconcile the observed broad tilting of the present-day Arabian platform that extends from the Red Sea to the Persian Gulf. This area has been cited as a classic example of rift-flank uplift; however the influence of the rift-flank processes is largely limited to uplift within a few hundred kilometers of the margin. Density heterogeneities linked to a megaplume, which are responsible for high topography in Southern Africa and rifting in East Africa, can reconcile the anomalous topography seen in Arabia. The second topic in this thesis deals with the rotational stability of planets with lithospheres. Using an equilibrium rotational theory suitable for a planet with a lithosphere characterized by long-term elastic strength, along with observational constraints on the figure of Mars, I show that the current rotation axis of Mars is stable. I also find that development of the massive Tharsis volcanic province cause a reorientation of the planet that was likely less than 15 degrees and that the thickness of the elastic lithosphere at the time of Tharsis formation was at least ~ 50km. Finally, I extend the equilibrium theory for a planet with an elastic lithosphere to consider the effect of a viscoelastic lithosphere on rotational stability. I find that the sufficiently high lithospheric viscosities (5x10(24) Pa-s of greater) a viscoelastic lithosphere can have a significant impact on reducing rates of true polar wander induced by an uncompensated load. These rates depend on the viscosity of the lithosphere and the size of the load.

Keywords: Physics
Advisor: Mitrovica, Jerry
From Wide Angle Reflection To Leaking Mode Seismograms - A Theoretical And Experimental Study

Seismograms observed by a detector in the wide angle reflection to leaking mode region, (the intermediate zone), exhibit a plethora of interesting features. Head waves form and interfere with directly reflected arrivals, supercritically reflected waves have unusually large amplitudes and the normal and leaking modes gradually become predominant with increasing source- receiver separation. This transition region from seismograms consisting mostly of directly reflected waves to seismograms where the total characteristics of the medium are integrated by the normal and leaking modes in therefore an important area of study. The eigenfunction expansion of an infinite medium elastic wave field in Cartesian co-ordinators is an infinite series of plane waves describing generalized rays with real and complex angles of propagation. The expansion can be modified for a place layered medium by assigning transmission factors to the rays at they encounter each interface producing further rays. The “Sherwood-Cagniard” technique, (Sherwood (1958 and 1960)), provides a methods of evaluating the eigenfunction solution for an impulsive line source. In this thesis it has been used in a modified form to give closed solution for rays which follow and ascribed sequence of transmissions and velocities in a two dimensional medium. Furthermore, this solution is shown to be easily related to cylindrically symmetric three dimensional wave propagation. The mathematical method is ideally suited to generating synthetic seismograms in the intermediate zone. The technique is developed and made systematic by a ray indexing methods for computer programming purposed. Theoretical seismograms thus computed are then compared with experimental seismograms observed on models. The transmission factor assigned to rays with a given angle of propagation are functions only of the angle between the rays’ wave-front and the interface. Thus the method is extended to plane dipping interfaces and the theoretical seismograms compared with experiment. Finally an attempt is made to generalize the technique to curved interfaces. Even here some agreement is obtained with the experimental seismograms. The experimental seismograms are measured on a calibrated two dimensional seismic model system. The system features a new construction technique with bongs glass to epoxy to form layer over a half space models with curved, dipping or horizontal interfaces.

Keywords: Physics
Advisor: Wilson, J.T.
A theoretical and experimental study of the polarization states of a Nd(3+):YAG laser

In this work, a model describing the polarization states of a Nd3+:YAG, single frequency laser is developed. Based on the symmetry of the Nd3+ site in the crystal, and the selection rules for electric dipole transitions in Kramers degenerate states, the phase relationships between the components of the electric dipole moment are found, without the use of the double group. Summing over the six sites of the crystal, the response of the gain material to an applied electric field is found, and the polarization behavior is determined to all orders in the electric field through a vector extension of the mean field model, similar to work done in gas lasers. The result is 16 coupled non-linear differential equations describing the polarization state of the laser. The predictions of the model are compared with results in the literature. While the model can explain most of these results, it is found that the effective output mirror model used to describe polarized feedback is inappropriate for a microchip laser with a long feedback path. New experiments are performed in the low birefringence regime, and for the case of elliptically polarized pump light. The predictions of the model are in semi-quantitative agreement with the low birefringence experiments, while for the case of circularly polarized pump fields, it is found that some of the approximations of the model become inappropriate. New experimental results on the bistability of the Nd:YAG microchip laser with polarized feedback are presented and briefly discussed. Suggestions for future experimental work and refinements to the model are presented.

Keywords: Physics
Group duality and its applications in nuclear physics

This thesis presents a physical perspective on group duality. We explain in detail some of the most important dualities that are of interest in nuclear physics, the relationships among these dualities, and how the theory of dual pairs facilitates relevant physical calculations in the context of nuclear physics. The dualities are classified according to whether they apply to fermion systems, boson systems, or both. The role of duality in the determination of tensor products, branching rules, and physically acceptable product wave functions — three fundamental operations in the physical application of symmetry analysis — is explained. We also explain the various conceptions of plethysm (one of which is the symmetrized product of representations), and how plethysm is related to duality. Applications of plethysm are discussed, primarily in the context of nuclear physics. A new method for the calculation of plethysms and the associated algorithm, are described. This new method has been implemented via a M A P LE program, so that plethysms (as well as the other standard operations involving Schur functions) can now be computed interactively in a MAPLE environment.

Keywords: Physics
Advisor: Rowe, David
Electromagnetic form factors and K-[pi] scattering

This thesis is divided into two parts — Part I: Discusses the theoretical aspects of pion and nucleon form factors. A phenomenological model is developed and found to be consistent with F1V= F π Part II: Describes a model proposed by J.W. Moffat for K-π and π-π scattering. This model is shown to satisfy the postulates of s-matrix theory, except for unitarity, and is found to be in reasonable agreement with experiment.

Keywords: Physics
Advisor: Moffat, J.W.
Picosecond infrared probing of II-VI semiconductors

High density (N > 1019cm-s) and high temperature (300 <Te < 3000K) electron-hole plasmas, have been generated in CdSe and CdSo.sSeo.5 by single 0.53 μm picosecond laser pulses. 1.9 and 2.8 μm picosecond probe pulses have been used to obtain time-resolved reflection and transmission characteristics of these samples and give information on the spatial and temporal evolution of the plasmas. Experiments carried out as a function of excitation intensity indicate a saturation of the carrier density at about 8±1 x 1019 cm-3 in both semiconductors and allowed for the first time the determination of the Auger recombination constant for these materials, which was found to be"'( = 3.7 ± 1.5 x 1029cm8 /sec. A simple model based on the Boltzmann transport equation, has also been developed and used to obtain the spatial and temporal evolution of the lattice temperature as well as the carrier density and temperature. Diffusion coefficients as high as 2000cm2 /sec, and corresponding plasma expansion velocities up to 107 cm/sec, are predicted and are in good agreement with the author's experimental data. Bleaching of the optically pumped states is also calculated and shown to be responsible for a 60% reduction of the absorption coefficient at > = 0.53μm. These bleaching effects, however, contribute little to the observed carrier density saturation as compared with diffusion effects. The model is also able to account for several features in experiments performed by others, namely those related to energy relaxation of carriers and the influence of non-equilibrium phonons on energy relaxation. Using the energy relaxation time T11& as a fitting parameter the model indicates an increase of Tl& as a function of excitation intensity, suggesting the existence of a phonon- bottleneck process.

Keywords: Physics
Advisor: van Driel, Henry
A Measurement of the Polarization of J/W Mesons Produced in High-Energy pp Collisions

This dissertation presents an analysis of the polarization of J/W mesons produced in pp collisions at a centre-of-mass energy 1.8 TeV. The collisions were produced by the Fermilab Tevatron collider, the world’s highest energy particle accelerator. The data were recorded by the Collider Detector at Fermilab during Run 1 of the Tevatron in 1992-1995. The J/W meson consists of a charm quark and its antiquark, and is the best-known type of quarkonium polarization of J/W mesons and other quarkonia provides a test of quakronium production models. The study of quarkonium production is important for understanding the strong nuclear force between quarks. The strong force is one of the four known fundamental forces, being responsible for binding quarks into hadrons and holding atomic nuclei together. The polarization of centrally produced J/W mesons has been measured over the transverse momentum range 4-20 GeV/c, using analysis of the angular distribution of their decays u+u-. Decay length measurements made by CDF’s silicon vertex detector allowed the promptly produced J/W mesons to be separated from those produced in B-hadon decays. The prompt and B-decay polarization parameters, ap and aB, have both been measured. The measured value of ap is positive at intermediate Pt, but this is consistent with zero above 12 GeV/c, in apparent disagreement with predictions of the NRQCD factorization formalism.

Keywords: Physics
Advisor: Trischuk, William
Hadronic energy distributions in deep-inelastic electron-proton scattering

An outline of QCD, the theory of strong interactions, is given and several QCD Monte Carlo models are described in detail. Energy distributions of the hadronic system produced in neutral current electron-proton deep-inelastic scattering at a centre of mass energy of 296 GeV are presented. Comparisons of the results with the models show that QCD radiation has a strong influence on the characteristics of the hadronic final state. The data is reasonably well produced by the Lund model based on a matrix element calculation in first order of the strong coupling, followed by appropriate parton showers. The colour dipole model also gives a reasonable representation of the data. Neither the first order matrix elements alone nor the Lund parton shower model, without the matrix element calculation, reproduce the data. The HERWIG parton shower model is also deficient. The data was taken with the ZEUS detector at the HERA accelerator in Hamburg, Germany. A general description of the detector design and principles of operation is provided. A three level trigger system is required to handle the high luminosity delivered by HER A. The first two levels involve the local processing of component data. The third level makes a decision based on the global information from an event. It accepts events at 100 Hz, or 20 MBytes/sec, at the design luminosity and reduces this to around 5 Hz. The architecture and implementation of the third level trigger system is discussed.

Keywords: Physics
Advisor: Orr, Robert S.