On pricing of perishable assets with menu costs

Cataloged from PDF version of article.We consider dynamic pricing of perishable assets in the presence of price-sensitive renewal demand processes. Unlike the existing works in the literature, we explicitly incorporate non-negligible price change costs which reflects the revenue management practice more realistically. These costs are also known as menu costs in the economic literature. The objective is to maximize the discounted expected profit for an initial inventory of Q items by determining the selling prices dynamically. We employ a dynamic programming approach and formulate a model that captures the price– demand relationship. We establish some theoretical results on the properties of the problem at hand. Specifically, we establish the sufficient conditions under which the within-period profit is concave in the selling price and in the remaining shelf life and, furthermore, show the structure of the myopically and asymptotically optimal pricing policy. In a numerical study, we investigate the impact of various system parameters and, in particular, the existence of menu costs, on pricing decisions. We observe that ignoring menu costs may be significantly misleading for the implementation of revenue management. We also propose four implementable policy heuristics and examine their performances. Our findings support some results previously obtained in settings with continuous pricing and negligible price change costs; and, contradict some others. & 2009 Published by Elsevier B.V

A prospective cohort study of postoperative complications in the management of perforated peptic ulcer

BACKGROUND: With dwindling rates of postoperative mortality in perforated peptic ulcer that is attributable to H(2)-receptor blocker usage, there is a need to shift the focus towards the prevention of postoperative morbidity. Further, the simultaneous contribution of several putative clinical predictors to this postoperative morbidity is not fully appreciated. Our objective was to assess the predictors of the risk, rate and number of postoperative complications in surgically treated patients of perforated peptic ulcer. METHODS: In a prospective cohort study of 96 subjects presenting as perforated peptic ulcer and treated using Graham's omentoplatsy patch or gastrojejunostomy (with total truncal vagotomy), we assessed the association of clinical predictors with three domains of postoperative complications: the risk of developing a complication, the rate of developing the first complication and the risk of developing higher number of complications. We used multiple regression methods – logistic regression, Cox proportional hazards regression and Poisson regression, respectively – to examine the association of the predictors with these three domains. RESULTS: We observed that the risk of developing a postoperative complication was significantly influenced by the presence of a concomitant medical illness [odds ratio (OR) = 8.9, p = 0.001], abdominal distension (3.8, 0.048) and a need of blood transfusion (OR = 8.2, p = 0.027). Using Poisson regression, it was observed that the risk for a higher number of complications was influenced by the same three factors [relative risk (RR) = 2.6, p = 0.015; RR = 4.6, p < 0.001; and RR = 2.4, p = 0.002; respectively]. However, the rate of development of complications was influenced by a history suggestive of shock [relative hazards (RH) = 3.4, p = 0.002] and A(- )blood group (RH = 4.7, p = 0.04). CONCLUSION: Abdominal distension, presence of a concomitant medical illness and a history suggestive of shock at the time of admission warrant a closer and alacritous postoperative management in patients of perforated peptic ulcer

RAC1B function is essential for breast cancer stem cell maintenance and chemoresistance of breast tumor cells

Breast cancer stem cells (BCSC) are presumed to be responsible for treatment resistance, tumor recurrence and metastasis of breast tumors. However, development of BCSC-targeting therapies has been held back by their heterogeneity and the lack of BCSC-selective molecular targets. Here, we demonstrate that RAC1B, the only known alternatively spliced variant of the small GTPase RAC1, is expressed in a subset of BCSCs in vivo and its function is required for the maintenance of BCSCs and their chemoresistance to doxorubicin. In human breast cancer cell line MCF7, RAC1B is required for BCSC plasticity and chemoresistance to doxorubicin in vitro and for tumor-initiating abilities in vivo. Unlike Rac1, Rac1b function is dispensable for normal mammary gland development and mammary epithelial stem cell (MaSC) activity. In contrast, loss of Rac1b function in a mouse model of breast cancer hampers the BCSC activity and increases their chemosensitivity to doxorubicin treatment. Collectively, our data suggest that RAC1B is a clinically relevant molecular target for the development of BCSC-targeting therapies that may improve the effectiveness of doxorubicin-mediated chemotherapy

Conservative Surgical Treatment of the Jaw Cysts in Children: Case Study of Five Patients

Aims: Conservative treatment of jaw cysts establishes low surgical complication risk and protects vital anatomical structures such as inferior alveolar nerve, maxillary sinus and permanent tooth germs. Marsupialization and decompression have been widely used in children. The aim of this study was to evaluate the results of the conservative treatment of jaw cysts in five children. Materials and Methods: This article presents case series of marsupialization in jaw cysts associated with impacted teeth in five children. A total of nine impacted teeth within the cystic lesions were observed. Results: Complete resolution of all cystic lesions and simultaneous eruption of six impacted teeth within the cyst were managed. The other two teeth were erupted orthodontically and one had to be extracted. Conclusions: Marsupialization is effective for the treatment of cystic lesions in growing patients as it preserves vital anatomical structures and enables eruption of the impacted teeth within the cyst.Keywords: Children, conservative treatment, cyst treatment, marsupializatio