Queuing-Inventory Models with MAP Demands and Random Replenishment Opportunities

Combining the study of queuing with inventory is very common and such systems are referred to as queuing-inventory systems in the literature. These systems occur naturally in practice and have been studied extensively in the literature. The inventory systems considered in the literature generally include (s,S)-type. However, in this paper we look at opportunistic-type inventory replenishment in which there is an independent point process that is used to model events that are called opportunistic for replenishing inventory. When an opportunity (to replenish) occurs, a probabilistic rule that depends on the inventory level is used to determine whether to avail it or not. Assuming that the customers arrive according to a Markovian arrival process, the demands for inventory occur in batches of varying size, the demands require random service times that are modeled using a continuous-time phase-type distribution, and the point process for the opportunistic replenishment is a Poisson process, we apply matrix-analytic methods to study two of such models. In one of the models, the customers are lost when at arrivals there is no inventory and in the other model, the customers can enter into the system even if the inventory is zero but the server has to be busy at that moment. However, the customers are lost at arrivals when the server is idle with zero inventory or at service completion epochs that leave the inventory to be zero. Illustrative numerical examples are presented, and some possible future work is highlighted.

Zika virus lateral flow assays using reverse transcription-loop-mediated isothermal amplification

Our study suggest that ZIKV RT-LAMP combined with LFA could serve as a rapid, accurate, and independent point-of-care detection method for ZIKV outbreaks.

Analysis of antibiotic treatment of children in a Shanghai tertiary hospital based on point prevalence surveys

Background Misuse and overuse of antibiotics by physicians in the treatment of children is common in China. This study aimed to reveal the overall use of antibiotics to treat children hospitalized in four types of pediatric wards. Methods Seven independent point prevalence surveys (PPSs) were conducted in Shanghai Children’s Hospital of Shanghai Jiao Tong University over the period 2012 to 2018. Pediatric ward types were defined general pediatric medical, pediatric surgical, pediatric intensive care units (PICU), and neonatal. Results A total of 3975 pediatric patients were included in the study, of which 63.9% received at least one dose antibiotic. The top five classes of antibiotics administered were cephalosporins (43.8%, n = 1743), penicillins (13.2%, n = 526), carbapenems (8.7%, n = 347), nitroimidazoles (7.1%, n = 281) and macrolides (6.5%, n = 257). The five most commonly used generic antibiotics were cefuroxime (14.9%, n = 594), ceftriaxone (9.7%, n = 387), cefotaxime (9.0%, n = 358), meropenem (8.1%, n = 320) and ampicillin/sulbactam (6.0%, n = 239). Meropenem was among top five antibiotics prescribed in the general pediatric, PICU and neonatal wards and sixth in the pediatric surgical wards. Of all children on antibiotics, 23.4% received prophylactic treatment, and prophylaxis accounted for 68.1% of indications for treatment in the pediatric surgical wards. Conclusions Given that over-treatment with third-generation cephalosporins and carbapenems has been associated with treatment-resistant infections, the prescription of these drugs should be strictly controlled and monitored, and measures should be taken to improve the management of surgical prophylaxis in hospitalized children in China.

The Affective and the Political: Rousseau and Contemporary Kantianism

Jean-Jacques Rousseau is often associated with a certain political mode of relating to another, where a person (“a Citizen”) is a locus of enforceable demands. I claim that Rousseau also articulated an affective mode of relating to another, where a person is seen as the locus of a kind of value (expressive of their being an independent point of view) that cannot be demanded. These are not isolated sides of a distinction, for the political mode constitutes a solution to certain problems that the affective mode encounters in common social circumstances, allowing us to see how these modes might be distinct while the political nevertheless shapes the affective. I contrast this approach with that of some contemporary Kantian writers on affective phenomena (Sarah Buss on shame, and J. David Velleman on love) who, for reasons rooted in Kant’s moral philosophy, have modeled affective ways of relating to others on duty. I claim that Rousseau’s writing provides us with a way of capturing the correct insight of these accounts—that some of our emotional responses to others are ways of appreciating their personhood—while avoiding the characteristic implausibilities of their close association between the affective and the political.

A Probabilistic Derivation of LASSO and L12-Norm Feature Selections

LASSO and ℓ2,1-norm based feature selection had achieved success in many application areas. In this paper, we first derive LASSO and ℓ1,2-norm feature selection from a probabilistic framework, which provides an independent point of view from the usual sparse coding point of view. From here, we further propose a feature selection approach based on the probability-derived ℓ1,2-norm. We point out some inflexibility in the standard feature selection that the feature selected for all different classes are enforced to be exactly the same using the widely used ℓ2,1-norm, which enforces the joint sparsity across all the data instances. Using the probabilityderived ℓ1,2-norm feature selection, allowing certain flexibility that the selected features do not have to be exactly same for all classes, the resulting features lead to better classification on six benchmark datasets.

A Bayesian regression approach to handicapping tennis players based on a rating system

This paper builds on a recently developed Markov Decision Process-based (MDP) handicap system for tennis, which aims to make amateur matches more competitive. The system gives points to the weaker player based on skill difference, which is measured by the point-win probability. However, estimating point-win probabilities at the amateur level is challenging since point-level data is generally only available at the professional level. On the other hand, tennis rating systems are widely used and provide an estimate of the difference in ability between players, but a rigorous determination of handicap using rating systems is lacking. Therefore, our goal is to develop a mapping between the Universal Tennis Rating (UTR) system and the MDP-based handicaps, so that two amateur players can determine an appropriate handicap for their match based only on their UTRs. We first develop and validate an approach to extract server-independent point-win probabilities from match scores. Then, we show how to map server-independent point-win probabilities to server-specific point-win probabilities. Finally, we use the estimated probabilities to produce handicaps via the MDP model, which are regressed against UTR differences between pairs of players. We conclude with thoughts on how a handicap system could be implemented in practice.