Analyzing a fleet solution using scenarios

Transportation is one of the most important logistics activities, accounting for a significant part of the logistics costs and with high level of impact in terms of the service level provided to the customer. To counteract the upward trend in costs, it is fundamental to identify a transport strategy that can reduce costs and, at the same time, does not adversely affect the service levels agreed with customers. The main objective of this research is to propose a methodology for companies to identify, from a set of scenarios proposed and through a comparative analysis of scenarios, a new fleet solution, allowing the Company under study to reduce its transport costs without harming the current service level agreements with its customers. This research is grounded on a case study methodology. The case study used is of a small Portuguese company that produces, imports and distributes a wide range of products. The distribution is conducted based on both its own fleet and subcontracted transportation. The comparative analysis of scenarios allowed identifying the current transportation solution as the most advantageous one for the company. A roadmap to address fleet solution is provided.info:eu-repo/semantics/acceptedVersio

Association between perinatal depression in mothers and the risk of childhood infections in offspring: a population-based cohort study

<p>Abstract</p> <p>Background</p> <p>Previous studies have suggested that children of mothers who experience depression during the perinatal period may have more infections, but such studies are few in number and none have been carried out in the United Kingdom (UK) population. The aim of this study was to investigate the association between perinatal depression in mothers and the risk of childhood infections in offspring in the UK general population.</p> <p>Methods</p> <p>We used data from The Health Improvement Network (THIN), a large database of electronic primary care medical records to conduct a cohort study among all first-born singleton children born and enrolled in THIN between 1988 and 2004. We used Poisson regression to compare the incidence of gastrointestinal infections and lower respiratory tract infections reported between birth and age 4 years among children of mothers with a record of perinatal depression with those born to mothers with no such history.</p> <p>Results</p> <p>Children of mothers with perinatal depression had a 40% increased risk of gastrointestinal infections and a 27% increased risk of lower respiratory tract infections compared with children of mothers without perinatal depression (incidence rate ratios = 1.40 and 1.27; 95% confidence intervals 1.37-1.42 and 1.22-1.32, respectively). On restricting to antibiotic-treated infections there was a slight increase in the magnitude of association with gastrointestinal infections but a decrease in that with lower respiratory tract infections (incidence rate ratios = 1.47 and 1.19; 95% confidence intervals 1.34-1.61 and 1.11-1.27, respectively).</p> <p>Conclusions</p> <p>Maternal perinatal depression is associated with increased rates of childhood gastrointestinal infections, particularly more severe infections, and lower respiratory tract infections in the UK. Preventing maternal perinatal depression may avoid substantial morbidity among offspring, although further work is also needed to investigate the detailed reasons for these findings.</p

Postpartum-specific anxiety as a predictor of infant-feeding outcomes and perceptions of infant-feeding behaviours: new evidence for childbearing specific measures of mood

Studies of pregnancy-specific anxiety suggest that it is a distinct construct which predicts perinatal outcomes more effectively than other general measures of anxiety. In response, a novel measure of postpartum-specific anxiety (PSAS) has been developed and validated, but it is not yet clear whether it possesses the same predictive power as its pregnancy-specific counterparts. The aim of this short-term prospective study was to (a) test the predictive validity of the PSAS in the context of one specific perinatal outcome, infant-feeding, and (b) examine whether the PSAS may be more efficacious at predicting infant-feeding outcomes and behaviours than the more commonly used general measures. Eight hundred mothers of infants aged between 0 and 6 months completed the PSAS alongside general measures of anxiety and depression at baseline. A subsample (n = 261) returned to complete a follow-up questionnaire examining infant-feeding outcomes and behaviours two weeks later. Hierarchical regression models revealed that the PSAS was associated with lower odds of breastfeeding exclusively, and breastfeeding in any quantity in the first 6 months postpartum. PSAS scores were also significantly associated with infant-feeding behaviours including a lower perceived enjoyment of food, and greater perceived food responsiveness and satiety responsiveness in the infant. As hypothesised, the PSAS was a stronger predictor of infant-feeding outcomes and behaviours than general anxiety and depression. The findings provide evidence for the predictive validity of the PSAS and call for the use of childbearing specific measures of mood when attempting to predict perinatal outcomes. Replication of these findings across other indices of maternal and infant health is now necessary

Sex Differences in Self-Concept and Symptoms of Depression During the Transition to College

In an investigation of sex differences in adaptation to college, real and ideal self-concept and symptoms of depression were studied longitudinally in a sample of 287 students. Survey data were collected at a summer orientation and one semester into freshman year. No sex differences in self-concept were found before college, but males' real self-concept became more positive over the transition. Females were more depressed than males at both times, although depressive symptom scores increased in both sexes. Real self-concept scores were negatively correlated with depressive symptoms in both sexes at both times, while the discrepancy between real and ideal self-concepts was positively correlated with depressive symptoms among females before college and in both sexes midway through freshman year. A one-year follow-up revealed that females' real self-concept scores increased to match those of males by mid-sophomore year. These sex differences are discussed in relation to psychological development during adolescence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45284/1/10964_2004_Article_411446.pd

An ant colony-based matheuristic approach for solving a class of vehicle routing problems

We propose a matheuristic approach to solve several types of vehicle routing problems (VRP). In the VRP, a fleet of capacitated vehicles visits a set of customers exactly once to satisfy their demands while obeying problem specific characteristics and constraints such as homogeneous or heterogeneous fleet, customer service time windows, single or multiple depots. The proposed matheuristic is based on an ant colony optimization (ACO) algorithm which constructs good feasible solutions. The routes obtained in the ACO procedure are accumulated in a pool as columns which are then fed to an integer programming (IP) optimizer that solves the set-partitioning (-covering) formulation of the particular VRP. The (near-)optimal solution found by the solver is used to reinforce the pheromone trails in ACO. This feedback mechanism between the ACO and IP procedures helps the matheuristic better converge to high quality solutions. We test the performance of the proposed matheuristic on different VRP variants using the well-known benchmark instances from the literature. Our computational experiments reveal competitive results: we report 6 new best solutions and meet the best-known solution in 120 instances out of 193

An ant colony-based matheuristic approach for solving a class of vehicle routing problems

We propose a matheuristic approach to solve several types of vehicle routing problems (VRP). In the VRP, a fleet of capacitated vehicles visits a set of customers exactly once to satisfy their demands while obeying problem specific characteristics and constraints such as homogeneous or heterogeneous fleet, customer service time windows, single or multiple depots. The proposed matheuristic is based on an ant colony optimization (ACO) algorithm which constructs good feasible solutions. The routes obtained in the ACO procedure are accumulated in a pool as columns which are then fed to an integer programming (IP) optimizer that solves the set-partitioning (-covering) formulation of the particular VRP. The (near-)optimal solution found by the solver is used to reinforce the pheromone trails in ACO. This feedback mechanism between the ACO and IP procedures helps the matheuristic better converge to high quality solutions. We test the performance of the proposed matheuristic on different VRP variants using well-known benchmark instances from the literature. Our computational experiments reveal competitive results: we report six new best solutions and meet the best-known solution in 120 instances out of 193