The present thesis is devoted to an analysis of the possibility of Bose condensates supporting persistent currents in the ring geometry. Our analysis is based on an approach developed by F. Bloch which focuses on the ground state energy of the condensate as a function of its angular momentum L. According to this approach, persistent currents are stable if the energy exhibits a local minimum at some nonzero angular momentum. We have used this approach for a single-species gas within a mean- eld approximation to show that persistent currents are stable at integral multiples of N*hbar, where N is the number of atoms in the system, provided a certain interaction parameter exceeds some critical value. These results are extended to a binary mixture of bosonic atoms and we show that the system is still capable of supporting persistent currents under certain conditions. Some of our conclusions contradict those appearing in the earlier literature. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-03-27 10:05:21.831

ABSTRACT Adenovirus Death Protein (ADP) expression during late stages of a lytic infection releases mature virions to promote viral spread, thus leading to death of the host cell. We sought to investigate ADP expression patterns in persistently infected human lymphocytes cells. We hypothesized that low expression of ADP allows the virus to persist while high expression would promote lytic infection in lymphocytes. Accordingly, we found ADP expressed in low amount in BJAB and KE37 cells, while lytically infected Jurkat cells demonstrated higher ADP expression in both protein and transcript levels. ADP overexpression in persistently infected lymphocytes did not alter the viability of these cells, or their level of ADP expression. In contrast, Jurkat cells infected with an ADP-deleted virus had increased survival and maintained viral DNA for greater than 1-month, suggesting conversion to a persistent infection. Also manipulating ADP expression had minimal impact on the total virus yield from infected lymphocytes.

Thesis (Ph. D.)--University of Toronto, 2004. / Adviser: Frank Wania. Includes bibliographical references (p. 154-163).

Univ., Diss.--Hamburg, 2006. / Literaturverz. S. [123] - 129.

The theory of persistent homology (PH), introduced by Edelsbrunner, Letscher, and Zomorodian in [1], provides a framework for extracting topological information from experimental data. This framework was then expanded by Carlsson and Zomorodian in [2] to allow for multiple parameters of analysis with the theory of multidimensional persistent homology (MPH). This particular generalization is considerably more difficult to compute and to apply than its predecessor. We introduce an intermediate theory, coordinated persistent homology (CPH), that allows for multiple parameters while still preserving the clarity and coherence of PH. In addition to introducing the basic theory, we provide a polynomial time algorithm to compute CPH for time series and prove several important theorems about the nature of CPH. We also describe an application of the theory to a problem in seismology.

Robot swarms are envisioned in applications such as surveillance, agriculture, search-and-rescue operations, and construction. The decentralized nature of swarm intelligence has three key advantages over traditional multi-robot control algorithms: it is scalable, it is fault tolerant, and it is not susceptible to a single point of failure. These advantages are critical to the task of persistent surveillance - where a number of target locations need to be visited as frequently as possible. Unfortunately, in the real world, the autonomous robots that can be used for persistent surveillance have a limited battery life (or fuel capacity). Thus, they need to abandon their surveillance duties to visit a battery swapping station (or refueling depot) a.k.a. €˜depots€™. This €˜down time€™ reduces the frequency of visitation. This problem can be eliminated if the depots themselves were autonomous vehicles that could meet the (surveillance) robots at some point along their path from one target to another. Thus, the robots would spend less time on the 'charging' (or refueling) task. In this thesis we present decentralized control algorithms, and their results, for three stages of the persistent surveillance problem. First, we consider the case where the robots have no energy constraints, and use a decentralized approach to allow the robots choose the €˜best€™ target that they should visit next. While the selection process is decentralized, the robots can communicate with all the other robots in the swarm, and let them know which is their chosen target. We then consider the energy constraints of the robots, and slightly modify the algorithm, so that the robots visit a depot before they run out of energy. Lastly, we consider the case where the depots themselves can move, and communicate with the robots to pick a location and time to meet, to be able to swap the empty battery of a robot, with a fresh one. The goal of persistent surveillance is to visit target locations as frequently as possible, and thus, the performance measurement parameter is chosen to be the median frequency of visitation for all target locations. We evaluate the performance of the three algorithms in an extensive set of simulated experiments.

One goal of persistent homology is to recover meaningful information from point-cloud data by examining long-lived topological features of filtered simplicial complexes built over the point-cloud. Motivated by real-world applications, the classic setting for this approach has been on finite metric spaces where many suitable complexes can be defined, and a natural filtration exists via sublevel sets of the metric. We consider the extension of persistent homology to dissimilarity networks equipped with a relaxed metric that does not assume symmetry nor the triangle inequality, by computing persistent homology on the directed clique complex defined over weighted directed graphs induced from a dissimilarity network and filtered by an adapted Rips filtration. We characterize digraph maps that induce maps on homology, describe a procedure to lift any digraph map to one that does induce maps on homology, and present a homotopy classification that provides a condition for two such digraph maps to induce the same map at the homology level. We also prove functoriality of directed clique homology and describe filtrations of digraphs induced by digraph maps. We then prove stability of persistent directed clique homology by showing that the persistence modules of a digraph and that of an admissible perturbation are interleaved. These admissible perturbations include perturbing dissimilarity measures in the network that either preserve the digraph structure or collapse series of arrows. We also explore similar constructions for maps between digraphs that allow reversal of arrows and show that while such maps, in general, produce unstable persistence barcodes, one can recover stability by inducing a reverse filtration and truncating at an appropriate threshold. Finally, we present an application of persistent directed clique homology to trace patterns and shapes embedded in migration and remittance networks.

An understanding of pain presupposes that the sufferer is able to use a language which is understood by all. Pain is always described in the language of experience and this experience, encountered by all, is nevertheless lived alone. The interpretive process provides the framework for this study which explores the experiences of five persistent pain sufferers. They have not had their pain validated by diagnosis and persistent pain has become the centrepiece of their existence. The use of epiphany moments illuminates an understanding of the essence of persistent pain experiences, and sufferers are provided with a voice to tell their own stories as their experiences unfold through events in time. These stories are then deconstructed and analysed in order to bring meaning to the lives described. This study found that the communal folklore of pain remains underpinned by dominant ideological forces and discursive practices which sustain the powerlessness of persistent pain sufferers. The sufferer is rendered powerless through medical technologies including the medical interview. Through language the perception of pain is understood and translated in such a way as to cause the sufferer to question the validity of their experience while accepting blame for the persistence of their pain and the need to have it stop. It was postulated that resistance to this process provides the mechanism through which persistent pain sufferers are able to surrender previously held notions of self to alternate identities, which encapsulate the embodied experience of pain. The sufferer can then move to a position where their persistent pain experience is validated. / Doctor of Philosophy (PhD)

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