I n the aftermath of a disaster, the relief items are transported from temporary warehouses (Staging Areas, SAs) to the Points of Distribution (PODs). Reducing the response time to provide relief items to disaster victims and cost minimization are two important objectives of this study. We propose an integrated optimization model for simultaneously determining (1) locations of staging areas, (2) inventory assignments to these SAs, (3) selecting sizes and numbers of trucks, and (4) routing of trucks from SAs to PODs. We also introduce another variable, a value function, which forces the model to reduce the logistics response time. We study the interactions among these variables through extensive sensitivity analysis. The time horizon for supply of relief items to disaster areas is usually limited to six days after the disaster occurs. Therefore, we use the proposed optimization model in a rolling-horizon manner, one day at a time. This reduces daily demand uncertainty. We analyze three disaster scenarios: (1) a low impact disaster, (2) a medium impact disaster, and (3) a high impact disaster. We conduct 720 experiments with different parameter values, and provide answers to the following questions that are useful for the logistic managers: (i) What are the right sizes (in terms of storage capacities) of SAs closer to the PODs? (ii) How should the budget be allocated in a disaster scenario? (iii) What mix of different types (in terms of sizes) of trucks should be selected in a given scenario? The most important managerial insights include: (i) operational budget beyond a limit does not improve the operational efficiency, (ii) when the budget is very low, it is essential to select smaller SAs close to the PODs in order to carry out operations in a feasible manner, (iii) when the impact of disaster is high, it is always beneficial to select larger SAs close to the PODs (as long as the budget is not very low), (iv) when the budget is high and the impact of disaster is not very high, the emergency management administrators need to select SAs prudently based on the tradeoff between the operational cost and the humanitarian value, and (v) the cost of operations is higher when all the trucks are of the same type compared to the case when there is a mix of different types of trucks. Also, we find that the optimal selection of SAs is not impacted by different combinations of the types of trucks. The focus of this study is on disasters that can be forecasted in advance and provide some lead time for preparations, for example, hurricanes. In order to understand the disaster management process of such disasters and develop our model, we (i) interviewed several emergency management administrators, and (ii) studied the disaster management processes available in documents released by various government agencies.
Hunger occurs in all locations around the globe, from developing to developed countries. In fact, there were over 37 million food insecure individuals (those without access to consistent nutritious food) in the United States in 2018, and this number increased in recent years due to the COVID pandemic. In many countries, food banks are used to consolidate food donations from individuals or government agencies and then provide that food to local partner agencies (such as food pantries and soup kitchens), who distribute it to food insecure individuals. As nonprofit humanitarian organizations, food banks strive to achieve geographic equity in their food distribution, so one area (or county) is not favored over others. However, food banks also want to maximize food distribution with their limited budgets. This equitable distribution versus cost balancing act is made even more challenging since food banks experience extreme variability in both the supply (donations) of food and partner agencies' capacity to deliver food to the food insecure. Our paper focuses on how mobile pantry programs, additional food bank storage capacity, and improved partner agency capacity can be utilized to address this supply and distribution capacity variability while considering food expiration times. Mobile pantry programs allow food banks to distribute food directly to the food insecure by sending their own trucks and employees to locations where food is most needed. Although all three of these approaches can be helpful, our results show that mobile pantries are a more effective approach to achieve high equity levels. This is especially true in the case of produce with relatively short expiration times. We also find that utilizing mobile pantry programs can increase equitable partner agency distribution considerably, because even small amounts of mobile pantry distribution in under-served areas allow for more equitable partner agency distribution in areas with available partner agency distribution capacity. Our research is based on data from our partner food bank, but our modeling and extensive sensitivity analysis should be applicable to many food banks with a similar collection and distribution structure.
This paper studies a two stage supply chain with a dominant upstream partner. Manufacturer is the dominant partner and operates in a Just-in-Time environment. Production is done in a single manufacturing line capable of producing two products without stopping the production for switching from one product to the other. The manufacturer imposes constraints on the distributor by adhering to his favorable production schedule which minimizes his manufacturing cost. Distributor on the other hand caters to retailers' orders without incurring any shortages and is responsible for managing the inventory of finished goods. Adhering to manufacturer's schedule may lead to high inventory carrying costs for the distributor. Distributor's problem, which is to find an optimal distribution sequence which minimizes the distributor's inventory cost under the constraint imposed by the manufacturer is proved NP-Hard by Manoj et al. (2008). Therefore, solving large size problems require efficient heuristics. We develop algorithms for the distribution problem by exploiting its structural properties. We propose two heuristics and use their solutions in the initial population of a genetic algorithm to arrive at solutions with an average deviation of less than 3.5% from the optimal solution for practical size problems.
Metabolites produced by both the microbial community and the host are present in the gastrointestinal tract environment. Several metabolites have been identified as important mediators of different physiological functions in the host. Small molecules and metabolites produced by commensal bacteria resident in the gastrointestinal tract can both promote and attenuate colonization of pathogens and inflammation. However, interactions between different metabolites in the GI tract and their net effect on the host are poorly understood. We hypothesized that NE promotes EHEC virulence by altering the microbial community structure and function to facilitate colonization. An in vitro anaerobic batch culture system was used to investigate the effect of NE on the microbial community structure and function. Cecal contents from 6–8 week‐old mice (n = 7) were both collected and cultured anaerobically in Gut Microbiota Medium (GMM) with or without NE (500μM) at 37°C for seven days. Exposure to NE increased the diversity of the bacterial community (p < 0.05, Mann‐Whitney test), as determined from 16S rRNA sequencing. Genera containing facultative pathogens and reported with pro‐inflammatory roles like Hathewaya, Clostridium and Streptococcus were highly abundant in the NE group while beneficial bacterial genera like Lactobacillus were decreased in abundance with NE treatment. Untargeted LC‐MS metabolomics showed significant changes in the levels of metabolites derived from aromatic amino acids. Targeted LC‐MS metabolomics analysis confirmed that the tryptophan metabolites indole and 5‐hydroxyindole were significantly decreased and tyramine was increased with NE treatment (p < 0.05, Wilcoxon test). Integration of metabolomic and metagenomic data using partial least squares regression (PLS‐R) showed correlation between the downregulation of indole and indole producing bacteria in the presence of NE. NE also down‐regulated the expression of the enzyme Tryptophanase A (TnaA) that is required for the conversion of dietary tryptophan to indole, in both nonpathogenic E. coli and EHEC. These results suggest that NE can modulate the microbial community composition and metabolite output to potentially increase pathogen colonization and infection.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.