Online pharmacies are an important part of the modern healthcare system. They interact with customers through well-designed web interfaces to deliver the healthcare customers need. In addition to well-designed web interfaces, online pharmacies rely on an effective supply chain system to provide medical supplies and services, and especially effective inventory management for supply systems. As green supply chain management (GSCM) becomes increasingly considered by countries, how to develop a sustainable inventory model that takes into account the revenue growth of an online pharmacy while preventing waste and reducing energy costs has become very important. In line with this trend, the study develops a sustainable inventory model that focuses on both economic aspect (profit) and environmental aspect (losses from excessive inventory) within a framework of a single period multi-product inventory model. Specifically, the sustainable inventory model applies the visual-attention-dependent demand (VADD) rate to characterize customer demand in an online trading environment, thereby seeking a profitable marketing strategy and reducing losses due to excessive inventory. Since the complexity of model optimization will drastically increase due to the inclusion of many products in the problem, a Genetic Algorithm (GA) based solution procedure is proposed to increase the feasibility of the proposed model in solving real problems. The sustainable inventory model and the solution procedure are illustrated, compared, and discussed with an online pharmacy example. Additionally, a sensitivity analysis is formulated to study the influence of model parameters on the model solution, the loss of unsold inventory that results in a waste of resources and energy, and the profit of online pharmacies.
Lower LVEF, larger scar and/or more dyssynchrony assessed by MPS were related to the development of ventricular arrhythmia for patients with CRT, and further defibrillator implantation may be considered for these patients.
For patients with coronary artery disease, larger scar burdens are associated with higher risk of ventricular arrhythmia. Left ventricular (LV) dyssynchrony is associated with increased risk of sudden cardiac death in patients with heart failure. The purpose of this study was to assess the values of LV dyssynchrony and myocardial scar assessed by myocardial perfusion SPECT (MPS) in predicting the development of ventricular arrhythmia in ischemic cardiomyopathy.Twenty-two patients (16 males, mean age: 66 ± 13) with irreversible ischemic cardiomyopathy received cardiac resynchronization therapy (CRT) for at least 12 months were enrolled for MPS. Quantitative parameters, including LV dyssynchrony with phase standard deviation (phase SD) and bandwidth, left ventricular ejection fraction (LVEF), and scar (% of total areas), were generated by Emory Cardiac Toolbox. Ventricular tachycardia (VT) and ventricular fibrillation (VF) recorded in the CRT device during follow-up were used as the reference standard of diagnosing ventricular arrhythmia. Stepwise logistic regression analysis was performed for determining the independent predictors of VT/VF and receiver operating characteristic (ROC) curve analysis was used for generating the optimal cut-off values for predicting VT/VF.Nine (41%) of the 22 patients developed VT/VF during the follow-up periods. Patients with VT/VF had significantly lower LVEF, larger scar, larger phase SD, and larger bandwidth (all P < 0.05). Logistic regression analysis showed LVEF and bandwidth were independent predictors of VT/VF. ROC curve analysis showed the areas under the curves were 0.71 and 0.83 for LVEF and bandwidth, respectively. The optimal cut-off values were <36% and > 139° for LVEF and bandwidth, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 39%, 53%, and 100%, respectively, for LVEF; and were 78%, 92%, 88%, and 86%, respectively, for bandwidth.LV dyssynchrony as assessed by phase analysis of MPS is helpful for predicting ventricular arrhythmia in ischemic cardiomyopathy after CRT. Further implantation of defibrillator may be considered for those patients with bandwidth >139°.
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