Optimal control of a revenue management system with dynamic pricing facing linear demand

This paper considers a dynamic pricing problem over a finite horizon where demand for a product is a time‐varying linear function of price. It is assumed that at the start of the horizon there is a fixed amount of the product available. The decision problem is to determine the optimal price at each time period in order to maximize the total revenue generated from the sale of the product. In order to obtain structural results we formulate the decision problem as an optimal control problem and solve it using Pontryagin's principle. For those problems which are not easily solvable when formulated as an optimal control problem, we present a simple convergent algorithm based on Pontryagin's principle that involves solving a sequence of very small quadratic programming (QP) problems. We also consider the case where the initial inventory of the product is a decision variable. We then analyse the two‐product version of the problem where the linear demand functions are defined in the sense of Bertrand and we again solve the problem using Pontryagin's principle. A special case of the optimal control problem is solved by transforming it into a linear complementarity problem. For the two‐product problem we again present a simple algorithm that involves solving a sequence of small QP problems and also consider the case where the initial inventory levels are decision variables. Copyright © 2006 John Wiley & Sons, Ltd.     

Stroke Unit care in Italy. Results from PROSIT (Project on Stroke Services in Italy). A nationwide study

Abstract The future challenge for improving stroke patients’ outcome will be to implement new Stroke Units (SUs) worldwide. However the best SU model remains uncertain. The aim of this study was to evaluate the number of SUs and the quality characteristics of acute stroke care in Italy. We conducted a SU survey in Italy, interviewing the directors of the hospital wards that discharged at least 50 acute stroke patients a year. A SU was defined as an acute ward area with stroke-dedicated beds and staff. To compare the quality of care provided in SUs with that in general wards (GWs) we investigated the characteristics of five domains: hospital setting, unit setting, staffing, process of care and diagnostic investigations. We identified 68 SUs and 677 GWs. Multivariate logistic regression analyses demonstrated that SUs compared to GWs had higher quality scores in unit setting (ROC area=0.9721), staffing (ROC area=0.8760) and care organisation (ROC area=0.7984). The hospital setting (ROC area=0.7033) and the availability of rapid diagnostic investigations (ROC area=0.7164) had lower power in discriminating SU from GW. In Italy in 2003/04 only 9% of the hospital services had organised SU care. The study demonstrated that SUs admitted more than 100 patients per year, had more monitoring equipment and staffing time, and practised multidisciplinary meetings and early mobilisation. The utility of these structural and performance characteristics needs validation from outcome studies.     

头皮冠状切口的并发症及其防治

目的：对采用头皮冠状切口所引发的并发症进行分析，探讨防治策略。方法：对我科2003-01～2006—07应用头皮冠状切口行颅颌面骨折修复重建、颌面部肿瘤切除与缺损修复、先天性颅颌面畸形矫正的221例中发生并发症的40例进行分析总结。结果：18例出现头皮麻木及感觉异常，9例有较宽切口瘢痕，6例出现脱发，4例发生颞窝凹陷，2例发生头皮下血肿，2例出现单侧面神经颞支损伤，1例发生鼻眶区肥厚。结论：头皮冠状切口具有切口隐蔽、面部疤痕不明显，显露充分的优点，但对其并发症也不容忽视。应根据具体情况选择合适的切口类型，术中精细的解剖、神经血管的良好保护以及正确的缝合方法可减少并发症的发生。     

Discrete time optimal control of linear time-delay systems

A discrete time optimal control for linear time-delay systems is developed to ensure that all closed-loop eigenvalues will lie inside a circular region centred at (β;, 0) with radius α. It is shown that by suitable manipulations the problem can be reduced to a standard discrete time quadratic regulator problem. An illustrative example is included to demonstrate the applicability of the proposed method.     

大脑后动脉交通前段及其内穿支研究

本文介绍Willis动脉环后半环大脑后动脉及其内穿支的显微解剖,大脑后动脉交通前段内穿支是脑深部的重要供血血管之一,100％的病例双侧具有该血管。     

Dorsal and ventral dopaminergic innervation of the spinal cord: Functional implications

Several studies have demonstrated that a descending dopaminergic pathway innervates the dorsal and the intermediate gray matter of the spinal cord and have suggested that this pathway is involved in pain modulation and in the control of autonomie functions. Other studies have also demonstrated the presence of dopamine (DA) and DA metabolites as well as of DA receptors in the ventral cord. There is also evidence for the implication of DA in the control of motor functions at the spinal level. The occurrence of a dopaminergic innervation in the ventral horn has been, however, disputed until recently. But recent work has demonstrated that the motoneural cell groups in the ventral horn (lamina IX) are a target for descending dopaminergic fibers. In addition, the possibility that DA is a mediator of primary afferent fibers has also been postulated. Finally, the occurrence of dopaminergic cell bodies has been suggested in the spinal cord. This indicates that DA is probably implicated in a complex manner in spinal functions. In the present paper the possible involvement of DA in sensory and in motor functions at spinal level will be discussed in view of neurochemical observations made in polyarthritic rats, in which pain-related behavior and reduction of locomotor activity associated with a marked decrease in mobility, are observed.     

Evaluation of bedside blood glucose monitoring by the phlebotomy team in an acute general care hospital

A feasibility study was undertaken to evaluate laboratory phlebotomists performing bedside glucose monitoring (BGM) over a 3-month period on a medical and surgical floor. Specific questions included: feasibility of providing testing on a 24-h basis, accuracy, appropriate utilization, effect on patient care, and an analysis of cost. In all, 1975 tests were performed on 114 patients. BGM results were within 15% of the laboratory's result 97% of the time. Patient and physician satisfaction was high. Although the cost of BGM is slightly higher than a laboratory glucose test, its use appeared to reduce the length of hospital stay by 0.47 days. Practical information on initiating a highly successful BGM program is provided.     

Alcohol controls and Aboriginal society: The effects of the Northern Territory restricted areas legislation

The “restricted areas” provisions of the Northern Territory Liquor Act constitute a preventative policy aimed at reducing the effects of alcohol abuse, particularly on Aboriginal communities. Under the provisions, communities can apply to be declared “dry” or semi-restricted with respect to liquor. Since their inception in 1979, the provisions have given rise to continuing controversy. This paper addresses some of the issues associated with the controversy. Patterns of alcohol consumption on “dry”, semi-restricted and unrestricted communities are compared, and the incidence of apprehension for public drunkenness before and after restricted area declarations is examined. The paper also discusses the provisions under which vehicles implicated in acts of illicit “grog-running” are forfeited to the NT Government. It is concluded that the restricted area provisions are associated with reduced levels of alcohol consumption and apprehensions for drunkenness, and are therefore beneficial in outcome. However, it is also argued that at present the provisions are flawed in that, while some aspects serve to promote community control over alcohol consumption, other elements have the effect of undermining community control and responsibility.