Uniting Gross-Neveu and Massive Schwinger Models

We show that it is possible to obtain the Gross-Neveu model in 1+1 dimensions from gauge fields only. This is reminiscent of the fact that in 1+1 dimensions the gauge field tensor is essentially a pseudo-scalar. We also show that it is possible in this context to combine the Gross-Neveu model with the massive Schwinger model in the limit where the fermion mass is larger than the electric charge.Comment: Version to appear in Phys. Lett.

Doctor of Philosophy

dissertationElectrical and Magnetic Field Flow Fractionation (ElFFF, MFFF) methods are two rapidly developing separation and characterization techniques using electrical and magnetic fields that have not been regularly applied to nanoparticle fractionation, separation, and characterization. Currently, several limitations characteristic of both techniques prevent them from being widely used tools in the separation of nanoparticles. In this work, we address the main limitations of both techniques and develop methods to enhance their separation abilities, and particularly their application to nanoparticles. Specifically, one order of magnitude improvement is obtained in the separation capability of the Cyclical ElFFF systems. It is shown that high resolution separations of 15 and 40 nm gold nanoparticles can be achieved by Cyclical ElFFF, for which the separation of particles smaller than 100 nanometers was not demonstrated before. In addition, the first particle based modeling of Electrical Field Flow Fractionation (ElFFF) systems is demonstrated for the first time. The developed particle based simulation code allows visualization of individual particles inside the separation channel, which leads to a better understanding of ElFFF operation and mechanisms. The outputs of the simulation code show good agreement with the experimental results. We have also fabricated a new ElFFF system and tested it with four different channel heights to investigate the effect of channel height on the separation performance of the ElFFF systems. It is also shown for the first time that ElFFF can be used for the separation of magnetic nanoparticles. In previously reported studies, magnetic field driven techniques were used for the separation of magnetic particles. However, in this study, it is revealed that an electrical field driven technique can also be used for the separation of these nanoparticles. A new magnetic field flow fractionation (MFFF) system was designed and modeled using both finite element and particle based simulations. As a change from current magnetic FFF systems, which use static magnetic fields, the new system uses cyclical magnetic fields for the separation of the particles. Finally, a novel passive magnetic microfluidic mixer is designed and fabricated which produces high efficiency mixing at the microscale, without need of an active actuation mechanism

A taxonomy for emergency service station location problem

The emergency service station (ESS) location problem has been widely studied in the literature since 1970s. There has been a growing interest in the subject especially after 1990s. Various models with different objective functions and constraints have been proposed in the academic literature and efficient solution techniques have been developed to provide good solutions in reasonable times. However, there is not any study that systematically classifies different problem types and methodologies to address them. This paper presents a taxonomic framework for the ESS location problem using an operations research perspective. In this framework, we basically consider the type of the emergency, the objective function, constraints, model assumptions, modeling, and solution techniques. We also analyze a variety of papers related to the literature in order to demonstrate the effectiveness of the taxonomy and to get insights for possible research directions

Exact and heuristic approaches to detect failures in failed k-out-of-n systems

This paper considers a k-out-of-n system that has just failed. There is an associated cost of testing each component. In addition, we have apriori information regarding the probabilities that a certain set of components is the reason for the failure. The goal is to identify the subset of components that have caused the failure with the minimum expected cost. In this work, we provide exact and approximate policies that detects components’ states in a failed k-out-of-n system. We propose two integer programming (IP) formulations, two novel Markov decision process (MDP) based approaches, and two heuristic algorithms. We show the limitations of exact algorithms and effectiveness of proposed heuristic approaches on a set of randomly generated test instances. Despite longer CPU times, IP formulations are flexible in incorporating further restrictions such as test precedence relationships, if need be. Numerical results illustrate that dynamic programming for the proposed MDP model is the most effective exact method, solving up to 12 components within one hour. The heuristic algorithms’ performances are presented against exact approaches for small to medium sized instances and against a lower bound for larger instances

An ant colony algorithm for the sequential testing problem under precedence constraints.

We consider the problem of minimum cost sequential testing of a series (parallel) system under precedence constraints that can be modeled as a nonlinear integer program. We develop and implement an ant colony algorithm for the problem. We demonstrate the performance of this algorithm for special type of instances for which the optimal solutions can be found in polynomial time. In addition, we compare the performance of the algorithm with a special branch and bound algorithm for general instances. The ant colony algorithm is shown to be particularly effective for larger instances of the problem

INVESTIGATION OF APRAXIA IN PATIENTS WITH SCHIZOPHRENIA AND BIPOLAR DISORDER TYPE I

Background: Almost 50% of patients with schizophrenia experience problems in their praxia performance, whereas executive function losses can be seen in patients with bipolar disorder. Although schizophrenia and bipolar disorder can be categorized as different disorders, in patient groups with similar symptom clusters, we aimed to determine whether there are common or disorderspecific praxia defects and to investigate the relationship between the sociodemographic and clinical features with apraxia. Subjects and methods: 52 Schizophrenia and 77 Bipolar Disorder Type I outpatients in remission for at least 6 months were included in our study. Test of Upper Limb Apraxia (TULIA) and Mayo Clinic Praxia Assessment Test (MCPAT) were used to evaluate praxia performance. Results: Patients with Schizophrenia performed poorer on the TULIA and MCPAT than patients with Bipolar Disorder Type I. While impairment in personal and social functioning was higher in the apraxic schizophrenia group compared to the non-apraxic group, the mean age of disease onset was lower. Functioning in the Apraxic Bipolar Disorder Type I group was lower than in the group without apraxia; whereas the patient\u27s age, duration of disease and number of hospitalizations were higher. Conclusions: Although apraxia, which have an important effect on the functioning and quality of life of the patient by causing impairment in daily activities, are seen at higher rates in patients with schizophrenia, might be also seen in patients with bipolar disorder type I. Decreasing diagnostic confusion and developing appropriate treatment strategies, evaluation of apraxia seems to be clinically important in terms of prognosis of diseases and functioning of patients