Physical Sciences and Mathematics Commons^™

Descent Systems, Eulerian Polynomials And Toric Varieties, Letitia Mihaela Golubitsky

Electronic Thesis and Dissertation Repository

It is well-known that the Eulerian polynomials, which count permutations in S_n by their number of descents, give the h-polynomial/h-vector of the simple polytopes known as permutohedra, the convex hull of the Sn -orbit for a generic weight in the weight lattice of Sn . Therefore the Eulerian polynomials give the Betti numbers for certain smooth toric varieties associated with the permutohedra. In this thesis we derive recurrences for the h-vectors of a family of polytopes generalizing this. The simple polytopes we consider arise as the orbit of a non-generic weight, namely a weight fixed by only the simple reflections …

Thermodynamics, Hydrodynamics And Critical Phenomena In Strongly Coupled Gauge Theories, Christopher Pagnutti

Electronic Thesis and Dissertation Repository

The gauge theory / string theory correspondence has led to great progress in the study of strongly-coupled gauge theories. In this work, we start with a detailed treatment of some simple examples of this correspondence in order to establish some of the concepts and techniques are used on a more complicated system. We then consider a (3+1)-dimensional theory of gravity with a translationally invariant horizon, that is assumed to be dual to a (2+1)-dimensional non-conformal gauge theory at finite temperature. We study the thermodynamics of this model and find that there exists an exotic type of second-order phase transition wherein …

Confidence Interval Estimation For Continuous Outcomes In Cluster Randomization Trials, Julia Taleban

Electronic Thesis and Dissertation Repository

Cluster randomization trials are experiments where intact social units (e.g. hospitals, schools, communities, and families) are randomized to the arms of the trial rather than individuals. The popularity of this design among health researchers is partially due to reduced contamination of treatment effects and convenience. However, the advantages of cluster randomization trials come with a price. Due to the dependence of individuals within a cluster, cluster randomization trials suffer reduced statistical efficiency and often require a complex analysis of study outcomes.

The primary purpose of this thesis is to propose new confidence intervals for effect measures commonly of interest for …

Finding Faulty Functions From The Traces Of Field Failures, Syed Shariyar Murtaza

Electronic Thesis and Dissertation Repository

Corrective maintenance, which rectifies field faults, consumes 30-60% time of software maintenance. Literature indicates that 50% to 90% of the field failures are rediscoveries of previous faults, and that 20% of the code is responsible for 80% of the faults. Despite this, identification of the location of the field failures in system code remains challenging and consumes substantial (30-40%) time of corrective maintenance. Prior fault discovery techniques for field traces require many pass-fail traces, discover only crashing failures, or identify faulty coarse grain code such as files as the source of faults. This thesis (which is in the integrated article …

Pushing The Boundaries In Gradient And Shim Design For Mri, Parisa Hudson

Electronic Thesis and Dissertation Repository

High performance gradient and shim coils are highly interested for high-field magnetic resonance imaging and spectroscopy to correct for large B₀ inhomogeneities created by the magnetic susceptibility differences between tissues, bone, and air. In chapter two, complete sets of high-performance gradient and shim coils are designed using two different methods: the minimum inductance and the minimum power target field methods. A quantitative comparison of shim performance in terms of merit of inductance, ML, and merit of resistance, MR, is made for shim coils designed using the minimum inductance and the minimum power design algorithms. The coils designed …

Bulk Density Of Small Meteoroids, Jean-Baptiste Kikwaya Eluo

Electronic Thesis and Dissertation Repository

The purpose of our work is to determine the bulk density of meteoroids. Unlike previous works which focused either on the dynamical properties of the meteoroids (deceleration), ignoring fragmentation; or on fitting solely the lightcurves, neglecting the dynamics of the meteoroids, we use both the photometry and astrometry to constrain our model. Our model, based on the dustball model, considers the meteoroid to be a collection of grains held together by a lower boiling point 'glue'. It uses conservation of energy and momentum to model the change in velocity and the light production as a function of time. The free …

New Synthetic Methodologies Directed Toward Pharmacologically Active Compounds As Well As Silole Based Chromophores For Analytical And Optoelectronic Applications, Mahmoud M. Abd Rabo Moustafa

Electronic Thesis and Dissertation Repository

The development of new and efficient synthetic methodologies to prepare heterocyclic compounds has received great attention over the years due to their importance in the pharmaceuticals and fine chemicals industries. Described herein are several novel syntheses of a variety of heterocycles including siloles, azaindoles, piperideines, piperidines and tetrahydropyrans.

A one-pot, two-step methodology involving Tamao’s reductive cyclization followed by Negishi cross coupling was utilized to synthesize several new series of silole-based chromophores. The property studies revealed new electropolymerized poly(thienyl-silole)s with enhanced photoefficiency for all-polymer solar cells. In addition, a new procedure is developed for the synthesis of the first dissymmetric silole …

Hemodynamics In The Stenosed Carotid Bifurcation With Plaque Ulceration, Emily Y. Wong

Electronic Thesis and Dissertation Repository

The presence of irregular plaque surface morphology or ulceration of the atherosclerotic lesion has been identified as an independent risk factor for ischemic stroke. Doppler ultrasound (DUS) is the most commonly performed non-invasive technique used to assess patients suspected of having carotid artery disease, but currently does not incorporate the diagnosis of plaque ulceration. Advanced Doppler analyses incorporating quantitative estimates of flow disturbances may result in diagnostic indices that identify plaque ulcerative conditions. A technique for the fabrication of DUS-compatible flow phantoms was developed, using a direct-machining method that is amenable to comprehensive DUS investigations. In vitro flow studies in …

Architecture Supporting Computational Trust Formation, Chern Har Yew

Electronic Thesis and Dissertation Repository

Trust is a concept that has been used in computing to support better decision making. For example, trust can be used in access control. Trust can also be used to support service selection. Although certain elements of trust such as reputation has gained widespread acceptance, a general model of trust has so far not seen widespread usage. This is due to the challenges of implementing a general trust model. In this thesis, a middleware based approach is proposed to address the implementation challenges.

The thesis proposes a general trust model known as computational trust. Computational trust is based on research …

Algorithmic Contributions To The Theory Of Regular Chains, Wei Pan

Electronic Thesis and Dissertation Repository

Regular chains, introduced about twenty years ago, have emerged as one of the major

tools for solving polynomial systems symbolically. In this thesis, we focus on different

algorithmic aspects of the theory of regular chains, from theoretical questions to high-

performance implementation issues.

The inclusion test for saturated ideals is a fundamental problem in this theory.

By studying the primitivity of regular chains, we show that a regular chain generates

its saturated ideal if and only if it is primitive. As a result, a family of inclusion tests

can be detected very efficiently.

The algorithm to compute the regular GCDs …

The Impact Of Climate And Transport On The Compositions And Textures Of Heavy Minerals In Modern Rivers Of New Zealand, Alexandre Aubin

Electronic Thesis and Dissertation Repository

The types, abundances and textures of heavy minerals in the 63-125 μm fraction of modern river sands were investigated in order to assess the controls of climate, tectonic setting, source composition, recycling, transport and diagenesis on the nature of sedimentary systems. Two rivers on the South Island of New Zealand were selected for detailed study; the Haast is a high-flow river located in the high precipitation region near the west coast, whereas the Ahuriri River has lower flow rates and is located in a drier region in the central South Island. In both river systems, the Zircon-Tourmaline-Rutile (ZTR) index increases …