Alternative e‑commerce delivery policies

Contemporary shopping habits are undergoing rapid change, with more and more consumers purchasing goods online. The rapid growth of the online retail sector provides great opportunities for both wholesalers and transporters in servicing this newly emergent type of customer. With both consumers and corporations acutely aware of the environmental impact of business activities, one of the most relevant research questions is how to organize the operations of an e-commerce delivery business while simultaneously minimizing its environmental impact. The present paper addresses the e-commerce delivery problem, a mathematical formulation and fast heuristics which enable the simulation of various e-commerce delivery scenarios. The effects of the scenarios regarding more environmentally friendly e-commerce concerns are tested upon real-world data. In particular, the impact of new green(er) technology (such as electric bicycles and cars), aggregated collection points, carrier bundling, and changing delivery times is investigated. The obtained results are suitable for implementation at an organizational or operational level within both e-commerce delivery companies and transporters.status: Published onlin

Crane-operated warehouses: Integrating location assignment and crane scheduling

Crane-operated warehouses constitute an essential asset for the many industries which must temporarily store products on their way from manufacturers to consumers. Such warehouses are a practical necessity rather than an explicitly desired service and they introduce significant operational costs which should be minimized. The problem addressed by the current paper, the Crane-operated Warehouse Scheduling Problem (CWSP), concerns the location assignment of input products and the scheduling of cranes for product movement in such warehouses. Several constraints are associated with the problem, for example certain products should not be stored close to each other (due perhaps to a difference in temperature or aroma) and cranes must respect operational safety distances between each other in order to prevent dangerous collisions. The present paper explores a novel methodology which combines these two decisions – location assignment and crane scheduling - instead of solving them sequentially. In addition to mathematical formulations for location assignment and crane scheduling, both an integrated mathematical formulation and a fast heuristic are presented for the CWSP. The quality of the mathematical formulation and the heuristic are compared against the conventional sequential approaches. Experimentation upon an extensive range of instances show significantly improved results are attainable when integrating location assignment and crane scheduling, despite some (expected) increase in computational time.status: publishe

A continuous-time model for scheduling gantry cranes in storage yards

status: publishe

Crane-operated warehouses : integrating location assignment and crane scheduling.

Crane-operated warehouses constitute an essential asset for the many industries which must temporarily store products on their way from manufacturers to consumers. Such warehouses are a practical necessity rather than an explicitly desired service and they introduce significant operational costs which should be minimized. The problem addressed by the current paper, the Crane-operated Warehouse Scheduling Problem (CWSP), concerns the location assignment of input products and the scheduling of cranes for product movement in such warehouses. Several constraints are associated with the problem, for example certain products should not be stored close to each other (due perhaps to a difference in temperature or aroma) and cranes must respect operational safety distances between each other in order to prevent dangerous collisions. The present paper explores a novel methodology which combines these two decisions ? location assignment and crane scheduling - instead of solving them sequentially. In addition to mathematical formulations for location assignment and crane scheduling, both an integrated mathematical formulation and a fast heuristic are presented for the CWSP. The quality of the mathematical formulation and the heuristic are compared against the conventional sequential approaches. Experimentation upon an extensive range of instances show significantly improved results are attainable when integrating location assignment and crane scheduling, despite some (expected) increase in computational time

Social stress induces neurovascular pathology promoting depression

Studies suggest that heightened peripheral inflammation contributes to the pathogenesis of major depressive disorder. We investigated the effect of chronic social defeat stress, a mouse model of depression, on blood–brain barrier (BBB) permeability and infiltration of peripheral immune signals. We found reduced expression of the endothelial cell tight junction protein claudin-5 (Cldn5) and abnormal blood vessel morphology in nucleus accumbens (NAc) of stress-susceptible but not resilient mice. CLDN5 expression was also decreased in NAc of depressed patients. Cldn5 downregulation was sufficient to induce depression-like behaviors following subthreshold social stress whereas chronic antidepressant treatment rescued Cldn5 loss and promoted resilience. Reduced BBB integrity in NAc of stress-susceptible or mice injected with adeno-associated virus expressing shRNA against Cldn5 caused infiltration of the peripheral cytokine interleukin-6 (IL-6) into brain parenchyma and subsequent expression of depression-like behaviors. These findings suggest that chronic social stress alters BBB integrity through loss of tight junction protein Cldn5, promoting peripheral IL-6 passage across the BBB and depressio