Workforce management in periodic delivery operations

Service quality and driver efficiency in the delivery industry may be enhanced by increasing the regularity with which a driver visits the same set of customers. However, effectively managing a workforce of drivers may increase travel distance, a traditional metric of the vehicle routing problem (VRP). This paper evaluates the effect that workforce management has on routing costs, providing insight for managerial decision making. The analysis is presented in the context of the period vehicle routing problem (PVRP), an extension of the VRP with vehicle routes constructed to service customers according to preset visit frequencies over an established period of time. We develop models to apply workforce management principles. We show that multi-objective PVRP models can achieve a balance between workforce management and travel distance goals, through a computational study with standard PVRP test cases and real-world delivery data. With the proper parameters in place, workforce management principles may be successfully applied without sacrificing other operational objectives

A Periodic Location Routing Problem for Collaborative Recycling

Motivated by collaborative recycling efforts for non-profit agencies, we study a variant of the periodic location routing problem, in which one decides the set of open depots from the customer set, the capacity of open depots, and the visit frequency to nodes, in an effort to design networks for collaborative pickup activities. We formulate this problem, highlighting the challenges introduced by these decisions. We examine the relative dfficulty introduced with each decision through exact solutions and a heuristic approach which can incorporate extensions of model constraints and solve larger instances. The work is motivated by a project with a network of hunger relief agencies (e.g., food pantries, soup kitchens and shelters) focusing on collaborative approaches to address their cardboard recycling challenges collectively. We present a case study based on data from the network. In this novel setting, we evaluate collaboration in terms of participation levels and cost impact. These insights can be generalized to other networks of organizations that may consider pooling resources

Flexibility and Complexity in Periodic Distribution Problems

In this paper, we explore trade-offs between operational flexibility and operational complexity in periodic distribution problems. We consider the gains from operational flexibility in terms of vehicle routing costs and customer service benefits, and the costs of operational complexity in terms of implementation difficulty. Periodic distribution problems arise in a number of industries, including food distribution, waste management and mail services. The period vehicle routing problem (PVRP) is a variation of the classic vehicle routing problem in which driver routes are constructed for a period of time; the PVRP with service choice (PVRP-SC) extends the PVRP to allow service (visit) frequency to become a decision of the model. While introducing operational flexibility in periodic distribution systems can increase efficiency, it poses three challenges: the difficulty of modeling this flexibility accurately; the computational effort required to solve the problem as modeled with such flexibility; and the complexity of operationally implementing the resulting solution. This paper considers these trade-offs between the system performance improvements due to operational flexibility and the resulting increases in operational and computational complexity as they relate to periodic vehicle routing problems. In particular, increasing the operational complexity of driver routes can be problematic in industries where some level of system regularity is required. As discussed in the paper, recent work in the literature suggests that dispatching drivers consistently to the same geographic areas results in driver familiarity and improved driver performance. Additionally, having the same driver visit a customer on a continual basis can foster critical relationships. According to UPS, such driver-customer relationships are a key competitive advantage in its package delivery operations, attributing 60 million packages a year to sales leads generated by drivers. In this paper, we develop a set of quantitative measures to evaluate the trade-offs between flexibility and complexity

Tolerability and safety of the intake of bovine milk oligosaccharides extracted from cheese whey in healthy human adults.

Mechanistic research suggests a unique evolutionary relationship between complex milk oligosaccharides and cognate bifidobacteria enriched in breast-fed infants. Bovine milk oligosaccharides (BMO) were recently identified as structurally and functionally similar to human milk oligosaccharides. The present single-blind three-way crossover study is the first to determine the safety and tolerability of BMO consumption by healthy human participants (n 12) and its effects on faecal microbiota and microbial metabolism. Participants consumed each supplement (placebo-control; low- and high-BMO doses) for eleven consecutive days, followed by a 2-week washout period prior to initiating the next supplement arm. Low and high BMO doses were consumed as 25 and 35 % of each individual's daily fibre intake, respectively. Safety and tolerability were measured using standardised questionnaires on gut and stomach discomfort and stool consistency. Faecal extracts were profiled for bacterial populations by next-generation sequencing (NGS) and bifidobacteria presence was confirmed using quantitative PCR. Urine was analysed for changes in microbial metabolism using nuclear magnetic resonance spectroscopy (1H-NMR). Consumption of both the low and high BMO doses was well tolerated and did not change stool consistency from baseline. Multivariate analysis of the NGS results demonstrated no change in faecal microbiota phyla among the placebo-control and BMO supplement groups. In conclusion, BMO supplementation was well tolerated in healthy adults and has the potential to shift faecal microbiota toward beneficial strains as part of a synbiotic treatment with probiotic cultures that selectively metabolise oligosaccharides

Effects of triclosan in breast milk on the infant fecal microbiome

Triclosan is frequently used for its antimicrobial properties and has been detected in human serum, urine, and breast milk. Animal and molecular studies have shown that triclosan exerts a wide range of adverse health effects at both high (ppm) and low (ppb) concentrations. Since triclosan is of growing concern to human and environmental health, there is a need to improve extraction procedures and to study additional effects from triclosan exposure. In this study, we have improved triclosan extraction from breast milk by using salt (MgSO4) to reduce emulsion formation and increase water polarity and water (~80%) to enhance the overall extraction efficiency (~3.5 fold). This extraction method was applied to breast milk samples collected from donors who i) recorded their use of triclosan-containing personal care products and ii) provided matching infant stool samples. Of the participants who had detectable amounts of triclosan in their breast milk, nine (75%) of them reported daily use of triclosan-containing personal care products. Levels of triclosan in breast milk were compared to the donor\u27s infant\u27s fecal microbiome. We found that the bacterial diversity in the fecal microbiome of the infants exposed to breast milk with detectable triclosan levels differed compared to their peers exposed to milk containing non-detectable amounts. This finding implies that exogenous chemicals are impacting microbiome diversity