This study introduces a new problem for uncapacitated single allocation hub location in which pricing is taken into account. The objective is profit maximization by choosing the best hub and spoke topology and applying the optimal pricing, in the case of price-dependent demand. It is assumed that the source determining the number of hubs is endogenous. Two variants of the considered problem are addressed: deterministic and robust. For the initial non-linear model, we show how the deterministic variant can be reformulated as a mixedinteger linear program, excluding the price variables. In the robust counterpart case, the quantity of commodity flows between the pairs of customers is of stochastic nature. The goal of the robust variant is to design a hub and spoke network, together with the pricing structure, that would be immune to small perturbations of demand. Starting from the original model for the robust case, we have shown how to formulate an equivalent mixed-integer conic-quadratic program. In addition, we have proposed a 2-phase matheuristic approach for the robust variant. A computational study was conducted on the set of hub instances from the literature using the commercial state-of-the-art solver. The obtained computational results are thoroughly discussed, location patterns are analyzed and some managerial insights are provided. The experimental study also showed that the proposed matheuristic approach for the robust variant performs better compared to the commercial solver.
Noncommunicable diseases (NCDs) are the major cause of death worldwide, and they are attributable to genetic and physiological determinants, behavioral risk factors and environmental impacts. The aim of this study is to assess behavioral risk factors for metabolic disease using demographic and social–economic aspects of the population characterized by risk factors, and to investigate relations among lifestyle risk factors (alcohol consumption, tobacco use, physical inactivity, intake of vitamins, fruits and vegetables) that are responsible for the majority of NCD deaths in the Republic of Srpska’s (RS’s) population. This is a cross-sectional study based on the analysis of a survey conducted among 2311 adult (≥18 years) persons (54.0% women, and 46.0% men). The statistical analysis was carried out by using Cramer’s V values, clustering, logistic regression (binomial, multinomial and ordinal), a chi-square test and odds ratios. In the case of logistic regression, we provide the prediction accuracy in percentages. A significant statistical correlation between demographic characteristics (gender and age) and risk factors was observed. The highest difference according to gender was observed in alcohol consumption (odds ratio (OR) = 2.705, confidence interval (95% CI) = 2.206–3.317), particularly in frequent consumption (OR = 3.164, 95% CI = 2.664–3.758). The highest prevalence of high blood pressure was registered in the elderly (66.5%); the same holds for hypertension (44.3%). Additionally, physical inactivity was one of the most common risk factors (33.4% physically inactive respondents). A significant presence of risk factors was confirmed among the RS population, with higher involvement of metabolic risk factors among the older population, while the prevalence of behavioral factors was related to younger age groups, particularly in the case of alcohol consumption and smoking. A low level of preventive awareness was observed among the younger population. Therefore, prevention is one of the most important instruments related to decreasing NCD risk factors in the RS population.
Introduction/purpose: The purpose of group testing algorithms is to provide a more rational resource usage. Therefore, it is expected to improve the efficiency of large-scale COVID-19 screening as well. Methods: Two variants of non-adaptive group testing approaches are presented: Hwang's generalized binary-splitting algorithm and the matrix strategy. Results: The positive and negative sides of both approaches are discussed. Also, the estimations of the maximum number of tests are given. The matrix strategy is presented with a particular modification which reduces the corresponding estimation of the maximum number of tests and which does not affect the complexity of the procedure. This modification can be interesting from the applicability viewpoint. Conclusion: Taking into account the current situation, it makes sense to consider these methods in order to achieve some resource cuts in testing, thus making the epidemiological measures more efficient than they are now.
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