This paper considers the issue of optimal subcarrier allocation in OFDMA. We show, via a counter example, that water-filling based subcarrier allocation policies, contrary to conventional wisdom, fail to provide rate-stability for an otherwise stabilizable OFDMA system. Water-filling is too myopic when considering longtime average performance, e.g. delay, queue lengths, and even long-run throug...

We study the employee staffing problem in a service organization that uses employee service capacity to meet random, nonstationary service requirements. The employees experience learning and turnover on the job, and we develop a Markov Decision Process (MDP) model which explicitly represents the stochastic nature of these effects. Theoretical results show that the optimal hiring policy is of a ...

We propose a sequential learning policy for ranking and selection problems, where we use a non-parametric procedure for estimating the value of a policy. Our estimation approach aggregates over a set of kernel functions in order to achieve a more consistent estimator. Each element in the kernel estimation set uses a di erent bandwidth to achieve better aggregation. The nal estimate uses a weigh...

We study a problem of information gathering in a social network with dynamically available sources and time varying quality of information. We formulate this problem as a restless multi-armed bandit (RMAB). In this problem, information quality of a source corresponds to the state of an arm in RMAB. The decision making agent does not know the quality of information from sources a priori. But the...

AIM To examine the refractive prediction error in high myopic eyes after phacovitrectomy. METHODS This retrospective comparative case series included 91 eyes (18 high myopic eyes and 73 non-high myopic eyes) of 91 patients who underwent successful phacovitrectomy (phacoemulsification, intraocular lens implantation, and pars plana vitrectomy). The high myopic eyes were defined as the eye with ...

We study optimal pricing in a single server queue when the customers valuation of service depends on their waiting time. In particular, we consider very general model, where customer valuations are random and sampled from distribution that length. The goal provider is to set dynamic state dependent prices order maximize its revenue, while also managing congestion. model problem as Markov decisi...

PURPOSE To evaluate the spatial relationships of the intraocular space, the cerebrospinal fluid space, and the lamina cribrosa in highly myopic eyes. METHODS The study included 36 human globes with an axial length of more than 26.5 mm that showed marked glaucomatous optic nerve damage (n = 29; highly myopic glaucomatous group) or in which the optic nerve was affected by neither glaucoma nor a...