Model formulations for pickup and delivery problems in designated driver services

Designated driver services use company vehicles to deliver drivers to customers. The drivers then drive the customers from their origins to their destinations in the customers’ own cars; at the destinations, the drivers are picked up by a company vehicle. We typically see teams of drivers assigned to company vehicles serving customers. However, when the drivers may be dropped off by one vehicle and picked up by another, a challenging pick-up and delivery problem arises. In this paper, we study the structural properties of the designated driver problem focusing on the synchronization between company vehicles and drivers. We present a two-index formulations to generate optimal, least-cost routes using a general-purpose solver. We benchmark the two-index formulations against a 3-index formulation and a path enumeration strategy. Based on a set of experiments, we find that the two-index formulation performs well, both in terms of quality and solution time, especially on the formulations with more flexibility in the pairing of drivers to company vehicles. Our computational experiments show that up to 75% cost savings are possible from using a flexible operating strategy as compared to a strategy in which drivers and company vehicles stay together throughout a shift

Model formulations for pickup and delivery problems in designated driver services

Designated driver services use company vehicles to deliver drivers to customers. The drivers then drive the customers from their origins to their destinations in the customers’ own cars; at the destinations, the drivers are picked up by a company vehicle. We typically see teams of drivers assigned to company vehicles serving customers. However, when the drivers may be dropped off by one vehicle and picked up by another, a challenging pick-up and delivery problem arises. In this paper, we study the structural properties of the designated driver problem focusing on the synchronization between company vehicles and drivers. We present a two-index formulations to generate optimal, least-cost routes using a general-purpose solver. We benchmark the two-index formulations against a 3-index formulation and a path enumeration strategy. Based on a set of experiments, we find that the two-index formulation performs well, both in terms of quality and solution time, especially on the formulations with more flexibility in the pairing of drivers to company vehicles. Our computational experiments show that up to 75% cost savings are possible from using a flexible operating strategy as compared to a strategy in which drivers and company vehicles stay together throughout a shift

Integrating Data Collection Optimization into Pavement Management Systems

This paper describes a method for using location data to optimize the routing of pavement data collection vehicles. In much of the developed world, pavement testing is performed on a regular basis; the pavement testing data, in turn, serves as input to Pavement Management Systems. Currently, in the United States of America, state departments of transportation plan this data collection work by providing the list of roads that must be tested and then leave the routing of the vehicles to the equipment operators who typically execute the work in an ad hoc manner. This study presents the processes required to code the list of roads for testing, select appropriate hotels in the region of testing, and apply a Traveling Salesman Problem with Hotel Stops model to derive a route. Applying the processes to a case study shows significant cost savings associated with this method of roadway testing, as opposed to the current ad hoc methods

Emergency Management System Design for Accurate Data: A Case Study

In any city – smart or not – emergency response is a critical service. In smart cities, the use of technology to manage access to and dispatching of emergency vehicles is particularly important. However, when a system must manage processes spanning multiple computers, clock drift becomes a prominent issue. We show the impact that clock drift can have in a prototype emergency management dispatch system along with a case-study illustrating design techniques that can remedy this issue

SLUG/SNAI2 and Tumor Necrosis Factor Generate Breast Cells With CD44+/CD24- Phenotype

<p>Abstract</p> <p>Background</p> <p>Breast cancer cells with CD44+/CD24- cell surface marker expression profile are proposed as cancer stem cells (CSCs). Normal breast epithelial cells that are CD44+/CD24- express higher levels of stem/progenitor cell associated genes. We, amongst others, have shown that cancer cells that have undergone epithelial to mesenchymal transition (EMT) display the CD44+/CD24- phenotype. However, whether all genes that induce EMT confer the CD44+/CD24- phenotype is unknown. We hypothesized that only a subset of genes associated with EMT generates CD44+/CD24- cells.</p> <p>Methods</p> <p>MCF-10A breast epithelial cells, a subpopulation of which spontaneously acquire the CD44+/CD24- phenotype, were used to identify genes that are differentially expressed in CD44+/CD24- and CD44-/CD24+ cells. Ingenuity pathway analysis was performed to identify signaling networks that linked differentially expressed genes. Two EMT-associated genes elevated in CD44+/CD24- cells, SLUG and Gli-2, were overexpressed in the CD44-/CD24+ subpopulation of MCF-10A cells and MCF-7 cells, which are CD44-/CD24+. Flow cytometry and mammosphere assays were used to assess cell surface markers and stem cell-like properties, respectively.</p> <p>Results</p> <p>Two thousand thirty five genes were differentially expressed (p < 0.001, fold change ≥ 2) between the CD44+/CD24- and CD44-/CD24+ subpopulations of MCF-10A. Thirty-two EMT-associated genes including SLUG, Gli-2, ZEB-1, and ZEB-2 were expressed at higher levels in CD44+/CD24- cells. These EMT-associated genes participate in signaling networks comprising TGFβ, NF-κB, and human chorionic gonadotropin. Treatment with tumor necrosis factor (TNF), which induces NF-κB and represses E-cadherin, or overexpression of SLUG in CD44-/CD24+ MCF-10A cells, gave rise to a subpopulation of CD44+/CD24- cells. Overexpression of constitutively active p65 subunit of NF-κB in MCF-10A resulted in a dramatic shift to the CD44+/CD24+ phenotype. SLUG overexpression in MCF-7 cells generated CD44+/CD24+ cells with enhanced mammosphere forming ability. In contrast, Gli-2 failed to alter CD44 and CD24 expression.</p> <p>Conclusions</p> <p>EMT-mediated generation of CD44+/CD24- or CD44+/CD24+ cells depends on the genes that induce or are associated with EMT. Our studies reveal a role for TNF in altering the phenotype of breast CSC. Additionally, the CD44+/CD24+ phenotype, in the context of SLUG overexpression, can be associated with breast CSC "stemness" behavior based on mammosphere forming ability.</p

Further phenotypic characterization of the primitive lineage− CD34+CD38−CD90+CD45RA− hematopoietic stem cell/progenitor cell sub-population isolated from cord blood, mobilized peripheral blood and patients with chronic myelogenous leukemia

The most primitive hematopoietic stem cell (HSC)/progenitor cell (PC) population reported to date is characterized as being Lin−CD34+CD38−CD90+CD45R. We have a long-standing interest in comparing the characteristics of hematopoietic progenitor cell populations enriched from normal subjects and patients with chronic myelogenous leukemia (CML). In order to investigate further purification of HSCs and for potential targetable differences between the very primitive normal and CML stem/PCs, we have phenotypically compared the normal and CML Lin−CD34+CD38−CD90+CD45RA− HSC/PC populations. The additional antigens analyzed were HLA-DR, the receptor tyrosine kinases c-kit and Tie2, the interleukin-3 cytokine receptor, CD33 and the activation antigen CD69, the latter of which was recently reported to be selectively elevated in cell lines expressing the Bcr-Abl tyrosine kinase. Notably, we found a strikingly low percentage of cells from the HSC/PC sub-population isolated from CML patients that were found to express the c-kit receptor (<1%) compared with the percentages of HSC/PCs expressing the c-kitR isolated from umbilical cord blood (50%) and mobilized peripheral blood (10%). Surprisingly, Tie2 receptor expression within the HSC/PC subset was extremely low from both normal and CML samples. Using in vivo transplantation studies, we provide evidence that HLA-DR, c-kitR, Tie2 and IL-3R may not be suitable markers for further partitioning of HSCs from the Lin−CD34+CD38−CD90+CD45RA− sub-population

On Collusion and Coercion: Agent Interconnectedness and In-Group Behaviour

The interconnectedness of actors is an antecedent for collective corruption, which in turn can lead to endemic corruption in a society. As a testbed for studying the effects of social interconnectedness on corrupt behaviours, we examine the domain of maritime customs. We add to our existing agent-based simulation a nuanced model of actor relatedness, consisting of clan, in-group (sect), and place of origin, and encode associated behavioural norms. We examine in simulation the effects of social interconnectedness on domain performance metrics such as container outcomes, delay, revenue, collusion, and coercive demands. Results confirm that, when corruption is widespread, localized punitive- or incentive-based policies are weakened, and that the effect of process re-engineering is frustrated when interconnectedness increases beyond a critical point, for two out of three forms of homophily connections. Our work connects with and provides a complementary methodology to works in the political economy literature.</p

On Collusion and Coercion: Agent Interconnectedness and In-Group Behaviour

The interconnectedness of actors is an antecedent for collective corruption, which in turn can lead to endemic corruption in a society. As a testbed for studying the effects of social interconnectedness on corrupt behaviours, we examine the domain of maritime customs. We add to our existing agent-based simulation a nuanced model of actor relatedness, consisting of clan, in-group (sect), and place of origin, and encode associated behavioural norms. We examine in simulation the effects of social interconnectedness on domain performance metrics such as container outcomes, delay, revenue, collusion, and coercive demands. Results confirm that, when corruption is widespread, localized punitive- or incentive-based policies are weakened, and that the effect of process re-engineering is frustrated when interconnectedness increases beyond a critical point, for two out of three forms of homophily connections. Our work connects with and provides a complementary methodology to works in the political economy literature.Algorithmic