Wind-Driven Gas Networks and Star Formation in Galaxies: Reaction-Advection Hydrodynamic Simulations

The effects of wind-driven star formation feedback on the spatio-temporal organization of stars and gas in galaxies is studied using two-dimensional intermediate-representational quasi-hydrodynamical simulations. The model retains only a reduced subset of the physics, including mass and momentum conservation, fully nonlinear fluid advection, inelastic macroscopic interactions, threshold star formation, and momentum forcing by winds from young star clusters on the surrounding gas. Expanding shells of swept-up gas evolve through the action of fluid advection to form a ``turbulent'' network of interacting shell fragments whose overall appearance is a web of filaments (in two dimensions). A new star cluster is formed whenever the column density through a filament exceeds a critical threshold based on the gravitational instability criterion for an expanding shell, which then generates a new expanding shell after some time delay. A filament- finding algorithm is developed to locate the potential sites of new star formation. The major result is the dominance of multiple interactions between advectively-distorted shells in controlling the gas and star morphology, gas velocity distribution and mass spectrum of high mass density peaks, and the global star formation history. The gas morphology observations of gas in the LMC and in local molecular clouds. The frequency distribution of present-to-past average global star formation rate, the distribution of gas velocities in filaments (found to be exponential), and the cloud mass spectra (estimated using a structure tree method), are discussed in detail.Comment: 40 pp, 15 eps figs, mnras style, accepted for publication in MNRAS, abstract abridged, revisions in response to referee's comment

The use of a formal sensitivity analysis on epidemic models with immune protection from maternally acquired antibodies

This paper considers the outcome of a formal sensitivity analysis on a series of epidemic model structures developed to study the population level effects of maternal antibodies. The analysis is used to compare the potential influence of maternally acquired immunity on various age and time domain observations of infection and serology, with and without seasonality. The results of the analysis indicate that time series observations are largely insensitive to variations in the average duration of this protection, and that age related empirical data are likely to be most appropriate for estimating these characteristics

A boundary integral formalism for stochastic ray tracing in billiards

Determining the flow of rays or non-interacting particles driven by a force or velocity field is fundamental to modelling many physical processes. These include particle flows arising in fluid mechanics and ray flows arising in the geometrical optics limit of linear wave equations. In many practical applications, the driving field is not known exactly and the dynamics are determined only up to a degree of uncertainty. This paper presents a boundary integral framework for propagating flows including uncertainties, which is shown to systematically interpolate between a deterministic and a completely random description of the trajectory propagation. A simple but efficient discretisation approach is applied to model uncertain billiard dynamics in an integrable rectangular domain

Media and Fraud - Accounting and Accountability

Media can play a huge role in the decisions of individuals. However, how media coverage impacts individuals’ decisions in an accounting setting has not been addressed in the literature. My research question is: does media coverage directly influence an individual’s likelihood to commit fraud? In my study, “committing fraud� is defined as making an overly aggressive accounting choice. This study was conducted using the MBA and MSA students. After administering the survey face-to-face, I gathered 96 responses to be used for analysis. findings show that individuals are more likely to report aggressively in the control condition, where their company has a neutral portrayal in the media in comparison to a company that has either a strong positive or strong negative portrayal in the media. My study finds that positive and negative media coverage made people more likely to report less revenue, which in my scenario, represents a less aggressive accounting choice. This demonstrates the significance of media on an individual’s actions, which hasn’t been tested previously in the accounting field

Cognitive Performance as A Function of Right-Sided, Low-Frequency rTMS Administration Using CNS Vital Signs

Major Depressive Disorder (MDD) is a complex, widespread, and recurrent psychiatric disorder. Although the majority of affected individuals respond adequately to pharmacotherapy and/or psychotherapy, there persists a sub-population of affected individuals who do not improve despite these interventions. Electric convulsive therapy has been described in the research as the most efficacious options for treatment resistant depression. However, due to the neurocognitive deficits associated with ECT, interest in transcranial magnetic stimulation (TMS), a non-invasive approach that stimulates the cerebral cortex, as an alternative to ECT has become a major research focus. The efficacy of both high-frequency and low-frequency rTMS for depression have been well documented although the impact on neurocognitive functioning is not completely understood. Research to date has demonstrated neurocognitive improvement following rTMS to the left dorsolateral prefrontal cortex only. Therefore, this study focused on the neurocognitive changes associated with rTMS when administered to the right dorsolateral prefrontal cortex and the supplementary motor area, utilizing data from the existing EVMS registry for patients receiving TMS. Measures assessed depression (Beck Depression Inventory-II), anxiety (Beck Anxiety Inventory), and neurocognitive functioning (CNS-Vital Signs tests of executive function, cognitive flexibility, and complex attention). A series of ANOVAs were conducted to examine: a) whether statistically significant differences exist in neurocognitive scores following 2 and/or 6 weeks of rTMS treatment as compared to pre-treatment; and b) whether any significant improvements in neurocognitive scores occur independent of a reduction in depression and anxiety scores. As expected, results revealed statistically significant improvements for all three neurocognitive domains across all three time points with the greatest improvement taking place during the first two weeks of treatment with a stabilizing effect thereafter. Results also revealed changes in depression and anxiety scores that were not significantly correlated with Executive Functioning, Complex Attention, and Cognitive Flexibility change scores. Therefore this study substantiates the use of right-sided, low-frequency rTMS as a treatment alternative to ECT as it provides support for improved cognitive functions that occur independent of mood improvements

Counting Cards: Combinatorics, Group Theory, and Probability in War

My project involved taking a look at the card game War, searching for patterns which develop in the game, and then looking for Mathematical explanations for those patterns. The project began when my advisor, Professor Marc Brodie, was playing War with his children and began to notice patterns and ask questions about them. The questions I set out to answer were: What is the probability of playing a game of war in which a loop develops? If we know the size of the deck we are using, can we determine what loop lengths are possible? How are cards cycling between players within a loop? What patterns of winning occur within a loop? What effect does changing the number of suits in the deck or the number of players have on the cycling of cards within a loop and the loop length? We found at least partial answers to all of these questions and more using Mathematica programs of simulated games along with basic theory from Combinatorics, Group Theory, and Probability

A microcontroller system for investigating the catch effect: Functional electrical stimulation of the common peroneal nerve

Correction of drop foot in hemiplegic gait is achieved by electrical stimulation of the common peroneal nerve with a series of pulses at a fixed frequency. However, during normal gait, the electromyographic signals from the tibialis anterior muscle indicate that muscle force is not constant but varies during the swing phase. The application of double pulses for the correction of drop foot may enhance the gait by generating greater torque at the ankle and thereby increase the efficiency of the stimulation with reduced fatigue. A flexible controller has been designed around the Odstock Drop Foot Stimulator to deliver different profiles of pulses implementing doublets and optimum series. A peripheral interface controller (PIC) microcontroller with some external circuits has been designed and tested to accommodate six profiles. Preliminary results of the measurements from a normal subject seated in a multi-moment chair (an isometric torque measurement device) indicate that profiles containing doublets and optimum spaced pulses look favourable for clinical use

LTV beta-bremsstrahlung spectrometer for Gemini 12 Final report

Design and operation of combination bremsstrahlung spectrometer and data processor for radiation monitoring during Gemini 7 fligh