Parameter Uncertainty in the Kalman--Bucy Filter

In standard treatments of stochastic filtering one first has to estimate the parameters of the model. Simply running the filter without considering the reliability of this estimate does not take into account this additional source of statistical uncertainty. We propose an approach to address this problem when working with the continuous time Kalman--Bucy filter, by making evaluations via a nonlinear expectation. We show how our approach may be reformulated as an optimal control problem, and proceed to analyze the corresponding value function. In particular we present a novel uniqueness result for the associated Hamilton--Jacobi--Bellman equation

Pathwise stochastic control with applications to robust filtering

We study the problem of pathwise stochastic optimal control, where the optimization is performed for each fixed realisation of the driving noise, by phrasing the problem in terms of the optimal control of rough differential equations. We investigate the degeneracy phenomenon induced by directly controlling the coefficient of the noise term, and propose a simple procedure to resolve this degeneracy whilst retaining dynamic programming. As an application, we use pathwise stochastic control in the context of stochastic filtering to construct filters which are robust to parameter uncertainty, demonstrating an original application of rough path theory to statistics

Ergodic backward stochastic difference equations

We consider ergodic backward stochastic differential equations in a discrete time setting, where noise is generated by a finite state Markov chain. We show existence and uniqueness of solutions, along with a comparison theorem. To obtain this result, we use a Nummelin splitting argument to obtain ergodicity estimates for a discrete time Markov chain which hold uniformly under suitable perturbations of its transition matrix. We conclude with an application of this theory to a treatment of an ergodic control problem

Bulk and surface energetics of lithium hydride crystal: benchmarks from quantum Monte Carlo and quantum chemistry

We show how accurate benchmark values of the surface formation energy of crystalline lithium hydride can be computed by the complementary techniques of quantum Monte Carlo (QMC) and wavefunction-based molecular quantum chemistry. To demonstrate the high accuracy of the QMC techniques, we present a detailed study of the energetics of the bulk LiH crystal, using both pseudopotential and all-electron approaches. We show that the equilibrium lattice parameter agrees with experiment to within 0.03 %, which is around the experimental uncertainty, and the cohesive energy agrees to within around 10 meV per formula unit. QMC in periodic slab geometry is used to compute the formation energy of the LiH (001) surface, and we show that the value can be accurately converged with respect to slab thickness and other technical parameters. The quantum chemistry calculations build on the recently developed hierarchical scheme for computing the correlation energy of a crystal to high precision. We show that the hierarchical scheme allows the accurate calculation of the surface formation energy, and we present results that are well converged with respect to basis set and with respect to the level of correlation treatment. The QMC and hierarchical results for the surface formation energy agree to within about 1 %.Comment: 16 pages, 4 figure

FLORIDA\u27S NUISANCE ALLIGATOR CONTROL PROGRAM

The recovery of alligators from centuries of exploitation, coupled with a burgeoning human population in Florida has resulted in an increasing number of problem animals and alligator attacks. In response to this problem, the Florida Game and Fresh Water Fish Commission implemented a nuisance alligator control program in 1978. A mean of 2513 nuisance alligators per year was harvested during the period 1978 to 1988. The number of alligator complaints, nuisance alligators harvested, and alligator attacks increased significantly over the period (P=0.0003, P=0.0001, and P=0.04). The value of alligator meat remained stable at about $5.00/pound over the same period, while the price paid for alligator hides has varied from$8.52 to $42.72/linear foot. The high economic value of this resource coupled with a commensurate license and tag fee structure has resulted in a program for removal of nuisance alligators that is relatively self-sufficient

Cephalosporin-3’-diazeniumdiolate NO-donor prodrug PYRRO-C3D enhances azithromycin susceptibility of non-typeable Haemophilus influenzae biofilms

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Objectives: PYRRO-C3D is a cephalosporin-3-diazeniumdiolate nitric oxide (NO)-donor prodrug designed to selectively deliver NO to bacterial infection sites. The objective of this study was to assess the activity of PYRRO-C3D against non-typeable Haemophilus influenzae (NTHi) biofilms and examine the role of NO in reducing biofilm-associated antibiotic tolerance. Methods: The activity of PYRRO-C3D on in vitro NTHi biofilms was assessed through CFU enumeration and confocal microscopy. NO release measurements were performed using an ISO-NO probe. NTHi biofilms grown on primary ciliated respiratory epithelia at an air-liquid interface were used to investigate the effects of PYRRO-C3D in the presence of host tissue. Label-free LC/MS proteomic analyses were performed to identify differentially expressed proteins following NO treatment. Results: PYRRO-C3D specifically released NO in the presence of NTHi, while no evidence of spontaneous NO release was observed when the compound was exposed to primary epithelial cells. NTHi lacking β-lactamase activity failed to trigger NO release. Treatment significantly increased the susceptibility of in vitro NTHi biofilms to azithromycin, causing a log-fold reduction in viability (p<0.05) relative to azithromycin alone. The response was more pronounced for biofilms grown on primary respiratory epithelia, where a 2-log reduction was observed (p<0.01). Label-free proteomics showed that NO increased expression of sixteen proteins involved in metabolic and transcriptional/translational functions. Conclusions: NO release from PYRRO-C3D enhances the efficacy of azithromycin against NTHi biofilms, putatively via modulation of NTHi metabolic activity. Adjunctive therapy with NO mediated through PYRRO-C3D represents a promising approach for reducing biofilm associated antibiotic tolerance

Obesity-Related Hormones and Metabolic Risk Factors: A Randomized Trial of Diet Plus Either Strength or Aerobic Training versus Diet Alone in Overweight Participants

There is debate about the additive effects of exercise in conjunction with diet to treat obesity, and not much is known about the differential effects of strength versus aerobic training. This randomized controlled trial examined the effects of diet plus strength training, diet plus aerobic training, or diet only on metabolic risk factors associated with obesity. Eighty-one overweight and obese participants completed the 8-week intervention. All participants received an energy-restrictive formula diet with an energy content based on 70% of measured resting metabolic rate (RMR). Participants assigned to an exercise group trained 3 days/week under supervision. Anthropometrics and fasting hormones were assessed pre- and post-intervention. Mean weight loss (8.5 ± 4.3kg SD) did not differ between groups nor did reductions in BMI or body fat, although the diet plus strength training group showed marginally greater lean mass retention. There were significant improvements in the values and number of metabolic syndrome risk factors, and decreases in insulin concentrations and insulin resistance, which did not vary between groups. For men, testosterone increased significantly more in the diet plus aerobic training as compared to the other groups. As compared to diet alone, the addition of strength or aerobic training did not improve changes in BMI, body fat, or metabolic risk factors although the diet plus strength training group showed a trend toward preservation of lean mass, and the diet plus aerobic group in men resulted in increased testosterone