Virus-like particles (VLPs) are efficient tools for boosting mRNA-induced antibodies

mRNA based vaccines against COVID-19 have proven most successful at keeping the SARS-CoV-2 pandemic at bay in many countries. Recently, there is an increased interest in heterologous prime-boost vaccination strategies for COVID-19 to maintain antibody response for the control of continuously emerging SARS-CoV-2 variants of concern (VoCs) and to overcome other obstacles such as supply shortage, costs and reduced safety issues or inadequate induced immune-response. In this study, we investigate the antibody responses induced by heterologous prime-boost with vaccines based on mRNA and virus-like particles (VLPs). The VLP-based CuMV TT -RBM vaccine candidate and the approved mRNA-1273 vaccine were used for this purpose. We find that homologous prime boost regimens with either mRNA or VLP induced high levels of high avidity antibodies. Optimal antibody responses were, however, induced by heterologous regimens both for priming with mRNA and boosting with VLP and vice versa, priming with VLP and boosting with mRNA. Thus, heterologous prime boost strategies may be able to optimize efficacy and economics of novel vaccine strategies.

BI-LEVEL PROGRAMMING APPROACH TO OPTIMAL STRATEGY FOR VENDOR-MANAGED INVENTORY PROBLEMS UNDER RANDOM DEMAND

We present an extension of vendor-managed inventory (VMI) problems by considering advertising and pricing policies. Unlike the results available in the literature, the demand is supposed to depend on the retail price and advertising investment policies of the manufacturer and retailers, and is a random variable. Thus, the constructed optimization model for VMI supply chain management is a stochastic bi-level programming problem, where the manufacturer is the upper level decision-maker and the retailers are the lower-level ones. By the expectation method, we first convert the stochastic model into a deterministic mathematical program with complementarity constraints (MPCC). Then, using the partially smoothing technique, the MPCC is transformed into a series of standard smooth optimization subproblems. An algorithm based on gradient information is developed to solve the original model. A sensitivity analysis has been employed to reveal the managerial implications of the constructed model and algorithm: (1) the market parameters of the model generate significant effects on the decision-making of the manufacturer and the retailers, (2) in the VMI mode, much attention should be paid to the holding and shortage costs in the decision-making.

MATERIAL TRANSSHIPMENT FOR PRECAST FABRICATION

Materials required for precast fabrication are dissimilar to those cast at construction sites. Fabricators who lack materials must wait until specific suppliers deliver the required materials. The objective of this study is to reduce total material management costs in the supply chain system through the most advantageous transshipment strategies. A material supply chain framework that enables fabricators to implement lateral transshipment is first proposed. Transshipment strategies are then formulated into a mathematical model. The most advantageous transshipment strategies are analyzed using computer simulation. Diverse order lead times, demands, transportation costs, and shortage costs are simulated to approximate operational conditions encountered in supply chain systems. Through various experiments, the most advantageous strategy for precast fabrication industry can be found. In addition, four rules are developed based on simulation results to enhance transshipment decision making. This research is one of the pioneering studies applying lateral transshipment to precast production management.

An Integrated Vendor-Buyer Model with Uncertain Lead Time, Life Time under Inflation and Variable Holding Cost

This study considers the problem of a vendor which supplies an item to the buyer with imprecise partial backlogging rate of unsatisfied demand and non instantaneous deterioration rate considering variable holding cost, the effect of inflation and time value of money. The supplier’s lead time is a stochastic function of his managing cost. The extra costs incurred by the retailer due to the uncertain lead time in terms of shortage costs or lost sales costs should be owed by the supplier. A numerical example is cited to illustrate the results and its significant features. Finally, to study the effect of changes of demand parameters, deterioration, inflation and managing cost on supplier and the retailer’s profit, a sensitivity analysis is presented numerically.

Optimization of a warehouse layout used for storage of materials used in ship construction and repair

The paper shows the evaluation of applying models to improve efficiency in management of warehousesused in shipyards, focused on pick up, packing, and shipping activities, supported among others on theproposal by Rosenblatt and Roll (1984) to optimize the layout for storage and handling of materials neededfor ship construction and repair. Besides proposing the best physical layout for the storage of goods, themodel seeks to minimize three types of costs: costs related to the initial investment (construction andmaintenance), shortage costs, and costs associated with storage policies. The optimal design is foundthrough analytical optimization and simulation techniques.