VictorJuiz/thesis huggingface dataset:
Parental Discipline and Child Abuse
Keywords: Social sciences
Personal relationships
Family
Sociology

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.
Stability of an equatorial jet and the formation of cyclone twins
Keywords: Physics

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.
Electroconvection in sheared annular fluid films
Keywords: Physics

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.
Photoproton Reactions In Medium-Weight Nuclei
Keywords: Physics

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.
Dynamic topography of continents and rotational stability of planets with lithospheres
Keywords: Physics

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.
From Wide Angle Reflection To Leaking Mode Seismograms - A Theoretical And Experimental Study
Keywords: Physics

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

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.
Group duality and its applications in nuclear physics
Keywords: 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.
Electromagnetic form factors and K-[pi] scattering
Keywords: Physics

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.
Picosecond infrared probing of II-VI semiconductors
Keywords: Physics

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.
A Measurement of the Polarization of J/W Mesons Produced in High-Energy pp Collisions
Keywords: Physics

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.
Hadronic energy distributions in deep-inelastic electron-proton scattering
Keywords: Physics

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.
Electromagnetic imaging of deep fluids in Archean crust
Keywords: Physics

Depth Image Processing (D IP) of transient electromagnetic data collected over layered structures such as sedimentary basins has proven to be an effective and cost efficient method of imaging the electrical conductivity variation in two dimensions. Data collected over the Kapuskasing Structural Zone (KSZ) of the Ardieun Superior Province in central Canada were D IP processed in an attempt to determine the structure associated with the resistive upper crust in the region. Two conductive horizons beneath the overburden are imaged a t 2 and 5 km depth with conductance of approximately 0.05 S and 0.15 S respectively. An increase in conductivity at mid-crustal depths is also observed. The shallower horizon is truncated in the vicinity of the Ivanhoe Lake Cataclastic Zone (ILCZ). Both conductive horizons are interpreted as saline fluids in a connected porosity. The saline waters are most likely a mixture of fluids with m any origins. The fluids m ay be genetically related to such phenomena as prograde metamorphic reactions during the creation of the extensive gneiss domains in the region as observed in the deep well of the Kola Peninsula, the uplift of the KSZ, infiltration from nearby sedimentary basins or meteoric influx. The conductive zones show some correlation with seismic reflections interpreted as “ramp and flat” style thrust planes. This correlation suggests the fluid-filled porosity m ay be controlled by structures associated with the uplift of the KSZ. The interruption in the continuity of the 5 km deep layer is possibly due to a high-angle fault, unseen by seismic methods, penetrating to m id-crustal depths in the region of the ILCZ. The data collected across the KSZ were strongly contaminated by local galvanic effects associated with an inhomogeneous overburden covering the region. To approximate the contaminated data, synthetic channeling responses, generated using inhomogeneous thin sheet algorithm s, were super imposed on a layered earth response. The layered earth response used was that indicated by the Depth Imaging and an inversion of the data to a layered earth structure. The synthetic responses were Depth Image Processed using single- and multi-fold geometries to investigate the reliability of the conductivity estimation from data strongly distorted by galvanic effects. The results of the modelling show the image of the layered earth structure may be distorted due to lateral variations in the conductance within the overburden that are com parable to cumulative conductance of the layered earth model. Although the drastic change in conductivity between the overburden and the gneiss (10-2 to 10-,6 S /m ) cause a certain amount of ringing in the numerical differentiation to derive the apparent conductivities, significant artifacts are not introduced into the imaged conductivities. These results demonstrate the imaged conductive horizons under the KSZ are the result of inductive effects in conductive layers at 2 and 5 km depth.
On the interaction of baroclinic instability and cumulus convection in polar air stream cyclones
Keywords: Physics

A linearized stability analysis of some idealized and observed atmospheric jet flows has been performed. The semigeostrophic approximation was used and a cumulus parameterization based on low-level moisture convergence included. Calculations using idealized basic states showed that the nature of the instability i.e. whether it is dominated by baroclinic instability or by release of latent heat through conditional instability of the second kind, is determined by the constant of proportionality between heating and convergence. For disturbances dominated by baroclinic processes, the effects of diabatic heating are equivalent to a reduction in static stability. It is possible for latent heat to be the dominant source of disturbance energy even when the structure is that of a baroclinic wave, although in this case the mode will have significant amplitude only in the region where heat is released. The effects of heating were found to be greater in regions where the background static stability was small. Thus the low vertical stability found on the cold-air side of the jets where comma clouds typically form gives an environment where heating is especially effective in producing small scale disturbances. Calculations of the instabilities of two observed jets showed similar behavior. The wavelength and structure of the modes agreed well with those of the comma clouds which were observed to form.