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.     

存样食物在追查食物中毒源头中的作用

[目的]针对食物中毒事件追查源头的困难局面,探索1种新的食物中毒追查方法。[方法]通过分析各种常见类型食物中毒的潜伏期,结合各种实际情况,探讨存样食物保存的时间和方法。[结果]存样食物至少要保存24h。[结论]这种存样待检方法有其先进性,但仍存在不少问题,需进一步改进。     

The scope of the cataract problem in the Middle East and the Mediterranean

The region is characterized by diversity in cultural, political, economic and health conditions. Blindness in the region varies from 6.4% to 0.2% with cataract ranking highly as an underlying cause. There is a need to develop national policies to deliver affordable, technically suitable, and cost effective management plans to reduce cataract. Economic, demographic, health, and manpower statistics are essential information to be considered in formulating such policies.     

药用胶带纸层厚度检测系统

设计并试制了一种药用胶带纸层厚度在线检测系统．该系统将高精度电容传感器与计算机结合起来，同时配有丰富的外围器件，实现了多种实际生产中所需要的功能．它的出现，彻底解决了药用胶带纸胶层厚度在线检测这个难题，经过两年多的实际应用的检验，该系统实现了在线非接触测量，精度高，动态性能好，实现功能全面，价格合理，是药用胶带纸生产的必备检测仪器．由于该系统还可以很方便在纸张、塑料薄膜等其它生产线上进行推广，因而，其应用前景十分看好．     

小儿内伤头痛辨治

74例小儿慢性头痛经辨证治疗,显效80.95%,好转16.67%,无效2.38%。痰浊头痛二陈汤或半夏白术天麻汤加减;肾虚头痛,杞菊地黄汤加减;淤血头痛,补阳还五汤;气血虚头痛八珍汤加减。指出了小儿内伤头痛的病因病机,并指出脑电图,脑阻抗血流图、CT、甲皱微循环可做为此病的诊断及疗效指标。     

Gestion des risques et choix de maintenance à l'hôpitalRisks management and maintenance choices at the hospital

Regulations evolve and risks management becomes one of the biomedical engineers' preoccupations. Thus, risks are various, and consequently it is difficult to identify, to manage and to bring them under control. Furthermore, regulations exist for sectors like healthcare technology monitoring, but it is not the same thing for instance for the risks linked to the maintenance. Thus regulation in the sector of maintenance evolves and the decree of the 1^st July law of health safety is going to modify the biomedical environment. The goal of this work is to study the tools and the methods of risks management that have been used for several years in the industrial field and to use them for some biomedical equipment like monitors or IV pumps. These methods adapted to these equipment will allow us to determine some appropriate rules of maintenance.     

Comparison of yogurt, soybean, casein, and amino acid–based diets in children with persistent diarrhea

Although previous studies have shown successful treatment of persistent diarrhea (PD) with the use of yogurt-based diets, some recent ones speculate the need of special formulas for the nutritional management of PD complicated cases. In the present study, we tested the hypothesis that the consumption of 3 lactose-free diets, with different degrees of complexity, is associated with lower stool output and shorter duration of diarrhea when compared with the use of a yogurt-based one on the nutritional management of PD. A total of 154 male infants, aged between 1 and 30 months, with PD and with or without dehydration, were randomly assigned to 1 of 4 treatment groups. Throughout the study, the patients were placed in a metabolic unit; their body weights and intakes of oral rehydration solution, water, and formula diets, in addition to outputs of stool, urine, and vomit, were measured and recorded at 24-hour intervals. Four different diets were used in this study: diet 1, yogurt-based formula; diet 2, soy-based formula; diet 3, hydrolyzed protein-based formula; and diet 4, amino acid–based formula. Throughout the study, only these formula diets were fed to the children. The data showed that children fed the yogurt-based diet (diet 1) or the amino acid–based diet (diet 4) had a significant reduction in stool output and in the duration of diarrhea. The use of an inexpensive and worldwide-available yogurt-based diet is recommended as the first choice for the nutritional management of mild to moderate PD. For the few complicated PD cases, when available, a more complex amino acid–based diet should be reserved for the nutritional management of these unresponsive and severe presentations. Soy-based or casein-based diets do not offer any specific advantage or benefits and do not seem to have a place in the management of PD.     

Results of non-operative treatment following hip fracture compared to surgical intervention

We followed all consecutive hip fracture patients admitted between 2004 and 2006, identified cases in which the intention was to treat non-operative and compared their functional outcome and mortality with a similar cohort treated surgically over the same period. We recorded length of hospital stay, place of discharge, pre and post-fracture mobility and residence, 30 days and 1 year mortality, re-admission due to same fracture and delayed surgery. The group treated surgically was recruited and matched for age, gender, pre and post-fracture mobility, mental confusion and independence. 25 patients were treated non-operative. 22 patients treated surgically over the same time period matched the patient characteristics of the non-operative arm. The mean hospital stay was 13 days in both groups. There were 4 extra-capsular fractures (3 displaced) and 21 intra-capsular fractures (5 displaced) in the non-operative arm and 11 extra-capsular fractures and 9 intra-capsular fractures in the surgically treated arm. 4 patients from the non-operative treatment group underwent late surgery because of persisting hip pain 20 days-2 months after the index event (2 cannulated screws, 1 hemiarthroplasty, 1 total hip arthroplasty). 11 patients in the surgical treatment arm underwent dynamic screw fixation, 1 had cannulated screw, 1 had total hip replacement and 7 had hemiarthroplasty. 14 of the non-operative treated patients were mobile independently or with aid before fracture but only 9 patients retained their pre-fracture mobility following treatment, compared to 16 patients pre-fracture and 11 patients post-fracture after surgery. 16 patients treated non-operative were living independently prior to injury but only 7 went back to their own residence. Of the operatively treated patients 14 patients were living independently and 10 patients went back to their previous residence. 1 month and 1 year mortality in the non-operative treated group was 4/21 and 7/21 respectively compared to 1/20 and 5/20 in the operative fixation group. There was no statistically significant difference in mobility, residence or mortality between the two groups (Fisher exact test, p > 0.05). Non-operative management after hip fracture is suitable for medically unfit patients and does not result in statistically significant difference in functional outcome or mortality compared to patients treated surgically.