Robust Optimization for Multiobjective Programming Problems with Imprecise Information

AbstractA robust optimization approach is proposed for generating nondominated robust solutions for multiobjective linear programming problems with imprecise coefficients in the objective functions and constraints. Robust optimization is used in dealing with impreciseness while an interactive procedure is used in eliciting preference information from the decision maker and in making tradeoffs among the multiple objectives. Robust augmented weighted Tchebycheff programs are formulated from the multiobjective linear programming model using the concept of budget of uncertainty. A linear counterpart of the robust augmented weighted Tchebycheff program is derived. Robust nondominated solutions are generated by solving the linearized counterpart of the robust augmented weighted Tchebycheff programs

Comparison of Serum Levels of Vitamin D in Patients With and Without Acute Coronary Syndrome

Introduction: Coronary artery disease is one of the most common causes of mortality around the world. The association between vitamin D deficiency and the incidence  of diseases, such as hypertension, diabetes, and metabolic syndrome, has been demonstrated previously. There have been studies concerning the relationship between vitamin D deficiency and cardiovascular diseases, which have shown different results. Therefore, this study aimed at determining the association between serum levels of vitamin D and acute coronary syndrome.Methods: In this case-control study, serum levels of vitamin D were compared between 50 patients with acute coronary syndrome and 50 individuals without this syndrome. A checklist, including demographic data of patients, comorbidities, vitamin D levels, lipid profiles, Electrocardiogram (ECG) changes and echocardiography results, was completed during hospitalization.Results: Mean age in the case and control group was 63.26 ± 10.76 and 61.22 ± 10.71 years, respectively. The prevalence of diabetes and high blood pressure in the case group was 32% and 54% versus 10% and 8% in the control group, respectively. Overall, 70% and 18% of subjects were smokers in the control and case groups, respectively. Mean concentration of vitamin D in serum was 20.63 ± 13.90 ng/mL, which was significantly lower than the control group with a mean concentration of 29.54 ± 16.8 ng/mL (P-Value = 0.002). Finally, it was shown that for every one unit increase in vitamin D levels, the risk of acute coronary syndrome was reduced by 7% (P-Value = 0.005).Conclusions: The results of this study showed that the serum levels of vitamin D were significantly lower in patients with acute coronary syndrome compared to those without this disease

Explainable Offline-Online Training of Neural Networks for Parameterizations: A 1D Gravity Wave-QBO Testbed in the Small-data Regime

There are different strategies for training neural networks (NNs) as subgrid-scale parameterizations. Here, we use a 1D model of the quasi-biennial oscillation (QBO) and gravity wave (GW) parameterizations as testbeds. A 12-layer convolutional NN that predicts GW forcings for given wind profiles, when trained offline in a big-data regime (100-years), produces realistic QBOs once coupled to the 1D model. In contrast, offline training of this NN in a small-data regime (18-months) yields unrealistic QBOs. However, online re-training of just two layers of this NN using ensemble Kalman inversion and only time-averaged QBO statistics leads to parameterizations that yield realistic QBOs. Fourier analysis of these three NNs' kernels suggests why/how re-training works and reveals that these NNs primarily learn low-pass, high-pass, and a combination of band-pass filters, consistent with the importance of both local and non-local dynamics in GW propagation/dissipation. These findings/strategies apply to data-driven parameterizations of other climate processes generally

The Reduced Profiteering Quality as a Cause of Sanction in the Airline Companies of Iran (The Case of Zagros Airline Company)

AbstractThe main purpose of the current study was to investigate the factors effective in the service quality of airline companies ba sed on the SERVQUAL Scale. Further, the relationships among service quality, satisfaction, trust and loyalty will be also studied. To achieve the purposes of the research, a field study was conducted on 259 passengers of Zagros Airline Company. The convenience-sampling plan was used to collect the data. The descriptive statistics, the confirmatory factor analysis, Pearson's correlation test and the structural equation modeling were used for data analysis. SPSS and AMOS Software were used for data analysis. The findings show that the service quality has a significant effect on the customer's satisfaction. Customer's satisfaction has also a significant effect on customer's trust, word of mouth (WOM) and the retention intention. In addition, WOM has a positive significant effect on the retention intention of the customers. However, no significant relationship was observed between the trust and the retention intention of the customers

A comparative study on visual and optical performance of Akreos AO and Kontur AB IOLs after phacoemulsification cataract surgery

AbstractPurposeAkreos AO and Kontur AB are two commonly used intraocular lenses (IOLs) in Iran. This study was designed to evaluate the visual performance of these lenses.MethodsIn a comparative interventional study, 35 patients (70 eyes) were recruited, and each IOL was implanted in one eye of the patients, randomly. Best corrected visual acuity (BCVA), contrast sensitivity, aberrometric analysis, and depth of focus were evaluated 1 month and 3 months postoperatively. A visual quality questionnaire was also filled for each eye, and the results were compared.ResultsMean age of the patients was 60.97 ± 7.00 years. BCVA was not significantly different between the two eyes, before, 1 month, and 3 months postoperatively (p > 0.05 for all). Photopic and mesopic contrast sensitivity was not different between the two lenses instead of photopic 18 cycles per degree, 3 months postoperatively and in mesopic 6 cycles per degree 1 month postoperatively (p = 0.034 and p = 0.002, respectively). Aberrometric factors including HoRMS, Total RMS, and Higher order without Z(4,0) were not significantly different between the two lenses (p > 0.05 for all), but they were slightly lower for Akreos AO. Post-operative distance-corrected visual acuity for intermediate and near vision were not different between the two groups (p > 0.05, respectively).ConclusionVisual performance of Akreos AO and Kontur AB is similar. However, contrast sensitivity and aberrometric parameters are slightly better for Akreos AO IOL