Growth-optimal portfolios under transaction costs

This paper studies a portfolio optimization problem in a discrete-time Markovian model of a financial market, in which asset price dynamics depend on an external process of economic factors. There are transaction costs with a structure that covers, in particular, the case of fixed plus proportional costs. We prove that there exists a self-financing trading strategy maximizing the average growth rate of the portfolio wealth. We show that this strategy has a Markovian form. Our result is obtained by large deviations estimates on empirical measures of the price process and by a generalization of the vanishing discount method to discontinuous transition operators.Comment: 32 page

Impulse control maximising average cost per unit time: a non-uniformly ergodic case

This paper studies maximisation of an average-cost-per-unit-time ergodic functional over impulse strategies controlling a Feller-Markov process. The uncontrolled process is assumed to be ergodic but, unlike the extant literature, the convergence to invariant measure does not have to be uniformly geometric in total variation norm; in particular, we allow for non-uniform geometric or polynomial convergence. Cost of an impulse may be unbounded, e.g., proportional to the distance the process is shifted. We show that the optimal value does not depend on the initial state and provide optimal or \ve-optimal strategies.Comment: 25 pages; This is an updated version after spinning off two sections of the paper as a basis for arxiv:1607.0601

On utility maximization in discrete-time financial market models

We consider a discrete-time financial market model with finite time horizon and give conditions which guarantee the existence of an optimal strategy for the problem of maximizing expected terminal utility. Equivalent martingale measures are constructed using optimal strategies.Comment: Published at http://dx.doi.org/10.1214/105051605000000089 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

\u3ci\u3eGomphus Spicatus\u3c/i\u3e (Odonata: Gomphidae) Rediscovered in Illinois and \u3ci\u3eLibellula Semifasciata\u3c/i\u3e (Odonata: Libellulidae) Recorded Near Wisconsin

(excerpt) Gomphus spicatus Hagen (Odonata: Gomphidae), commonly called dusky clubtail, is a common and widely distributed dragonfly in a variety of ponds, lakes, and slow streams throughout its range in the north-eastern and northcentral United States and adjacent areas of southern Canada (Donnelly 2004)

Clearing the Path to Unemployment Insurance for Low-Wage Workers

Unemployment Insurance is a necessary and beneficial stimulus program for part-time workers. However, the current rules for eligibility often leave eligible workers behind. This study analyzes the alternative base period (ABP), a policy reform that makes it easier for low-wage workers to qualify for UI benefits.

“We Are Forced to Declare War”: Linkages between the 1970 Abortion Caravan and Women’s Anti-Vietnam War Activism

To date, studies of the Abortion Caravan have addressed it primarily within the context of the growth of women’s liberation. At the same time, while the contribution of women to the anti-Vietnam War effort in Canada has been gaining increased scholarly attention, no works have yet explored the links between women’s abortion rights activism and their anti-Vietnam activities. This article explores these linkages through the 1970 Abortion Caravan, using oral history interviews, movement and mainstream media coverage, and the archival files of the Vancouver Women’s Caucus. Connections can be found in the women’s adoption of a language of war, in tactics and strategies used by each movement’s activists, and in the conflict between their competing political interests. This broader contextualization helps to illuminate some of the complexities of women’s abortion rights activism.Jusqu’à maintenant, les études qui ont été réalisées sur la Caravane de l’avortement l’ont surtout été dans l’optique du mouvement croissant de libération des femmes. Or, s’il est vrai que les spécialistes s’intéressent de plus en plus à la contribution des femmes au mouvement contre la guerre du Vietnam au Canada, aucun ne s’est encore penché sur les liens entre le militantisme pour le droit des femmes à l’avortement et les activités de ce mouvement contre la guerre du Vietnam. Le présent article explore ces liens dans la perspective de la Caravane de l’avortement de 1970 en s’appuyant sur des interviews d’histoire orale, la couverture réalisée par les médias des mouvements et par la presse grand public ainsi que les dossiers d’archives du Caucus des femmes de Vancouver. Ces liens se voient dans l’adoption par les femmes d’un discours de guerre, dans les tactiques et les stratégies des activistes de chaque mouvement et dans la divergence de leurs intérêts politiques. Cette mise en contexte plus vaste nous aide à mieux comprendre certaines des complexités du militantisme en faveur du droit des femmes à l’avortement.

How evolutionary objectives and the intracellular environment shape metabolic fluxes

Genome-scale flux balance models of metabolism provide testable predictions of all metabolic rates in an organism, by assuming that the cell is optimizing a metabolic goal known as the objective function. In the first chapter of this dissertation, we introduce an efficient inverse flux balance analysis (invFBA) approach, based on linear programming duality, to characterize the space of possible objective functions compatible with measured fluxes. After testing our algorithm on simulated E. coli data and time-dependent S. oneidensis fluxes inferred from gene expression, we apply our inverse approach to flux measurements in long-term evolved E. coli strains, revealing objective functions that provide insight into metabolic adaptation trajectories. For over a hundred years, enzymes, or the proteins that catalyze metabolic reactions, have been characterized in vitro, even though the aqueous solution of a test tube little resembles the crowded intracellular milieu. Since few metabolites show unique fluorescent signatures, metabolism is all but invisible, greatly complicating efforts to describe fluxes in vivo. In the second chapter of this dissertation, we introduce a new technique called EIFFL (Estimation of Intracellular Flux through Fluorescence Loss) for visualizing the flux through a reaction inside single E. coli cells, using a substrate that undergoes an enzyme-catalyzed loss of fluorescence. EIFFL would not only further our quantitative understanding of metabolism, but enable us to promptly detect enzymes that confer clinically meaningful states, such as antibiotic resistance. We present a particular instance of EIFFL that couples nfsA, the major nitroreductase of E. coli responsible for its antibiotic sensitivity to nitrofurantoin, to 2-NBDG, a glucose derivative that loses fluorescence upon being reduced by nfsA with NADPH. We correlate the flux through the reaction with the concentration of a fluorescently tagged nfsA and measure the “flux noise” across a population of E. coli cells. Given that nfsA abolishes 2-NBDG fluorescence by the same molecular mechanism that it activates nitrofurantoin, EIFFL could serve as a means to rapidly infer the antibiotic resistance of single pathogenic E. coli cells directly from clinical samples.2020-02-20T00:00:00