Heuristics and policies for online pickup and delivery problems

Master ThesisIn the last few decades, increased attention has been dedicated to a speci c subclass of Vehicle Routing Problems due to its signi cant importance in several transportation areas such as taxi companies, courier companies, transportation of people, organ transportation, etc. These problems are characterized by their dynamicity as the demands are, in general, unknown in advance and the corresponding locations are paired. This thesis addresses a version of such Dynamic Pickup and Delivery Problems, motivated by a problem arisen in an Australian courier company, which operates in Sydney, Melbourne and Brisbane, where almost every day more than a thousand transportation orders arrive and need to be accommodated. The rm has a eet of almost two hundred vehicles of various types, mostly operating within the city areas. Thus, whenever new orders arrive at the system the dispatchers face a complex decision regarding the allocation of the new customers within the distribution routes (already existing or new) taking into account a complex multi-level objective function. The thesis thus focuses on the process of learning simple dispatch heuristics, and lays the foundations of a recommendation system able to rank such heuristics. We implemented eight of these, observing di erent characteristics of the current eet and orders. It incorporates an arti cial neural network that is trained on two hundred days of past data, and is supervised by schedules produced by an oracle, Indigo, which is a system able to produce suboptimal solutions to problem instances. The system opens the possibility for many dispatch policies to be implemented that are based on this rule ranking, and helps dispatchers to manage the vehicles of the eet. It also provides results for the human resources required each single day and within the di erent periods of the day. We complement the quite promising results obtained with a discussion on future additions and improvements such as channel eet management, tra c consideration, and learning hyper-heuristics to control simple rule sequences.The thesis work was partially supported by the National ICT Australia according to the Visitor Research Agreement contract between NICTA and Martin Damyanov Aleksandro

A Qualitative Study of Rural Black Adolescents’ Perspectives on Primary STD Prevention Strategies

Primary STD prevention relies on five key strategies: practicing abstinence, choosing low-risk partners, discussing partners’ sexual history, using condoms consistently and not having multiple partners. Few studies have examined all of these strategies simultaneously, and few have focused on rural black adolescents, whose rates of early sexual initiation and STDs are among the highest in the nation

Variation in Sexual Behaviors in a Cohort of Adolescent Females: The Role of Personal, Perceived Peer, and Perceived Family Attitudes

Little is known about how adolescent sexual behaviors develop and the influence of personal or perceived social attitudes. We sought to describe how personal, perceived peer and perceived family attitudes towards adolescent sexual activity influences adolescent females’ sexual behaviors over time

A Quality Improvement Project to Improve Family Recognition of Medical Team Member Roles

OBJECTIVE: Previous studies have shown that inpatients and families in academic settings have a limited ability to recall either their medical team members or the roles of those members. This is an important issue for patient and family satisfaction as well as patient safety. The objective of this study was to increase families’ recognition of medical team members’ roles. METHODS: We established a multidisciplinary quality improvement leadership team, measured family recognition of medical team members and their roles, and conducted 2 PDSA (Plan-Do-Study-Act) cycles. The first intervention was standardization of the content and delivery of our verbal team introductions to ensure inclusion of essential elements and family engagement. The second intervention was addition of an informational white board in each patient room. The prospective study included 105 families in the preintervention phase, 103 post-PDSA cycle 1, and 92 post-PDSA cycle 2. RESULTS: After conduction of 2 PDSA cycles, the recognition of the attending role increased from 49% to 87% (P = .000), the resident role from 39% to 73% (P = .000), and the medical student from 75% to 89% (P = .038). CONCLUSIONS: The multidisciplinary quality improvement model was effective in improving family recognition of the roles of attending physicians, resident physicians, and medical students. Consistent attention to engaging the families and explaining our roles as well as providing informational white boards are effective interventions to facilitate this process

Flow condensation heat transfer enhancement in a mini-channel with hydrophobic and hydrophilic patterns

The study examined the enhancement of flow condensation of steam on hydrophobic and hydrophilic surfaces. Six 1.06 mm mini-gaps were tested at pressures of 350kPa to 400kPa, average qualities of 0.2 to 0.95 and mass fluxes of 50 to 200 kg/m²s. The surfaces included hydrophilic copper, hydrophobic Teflon AF™, and four surfaces with combined Teflon and hydrophilic patterns; pattern selection was guided by an analytical model. Condensing heat transfer coefficients on hydrophobic and hydrophobic/hydrophilic patterned surfaces reached a value of up to 425,000 W/m²K, surpassing the hydrophilic surface by an order of magnitude. Enhancement factors of 3.2 to 13.4 times that of the hydrophilic channel were found in the hydrophobic channel; combined with a lack of dependence on mass flux or quality, the data strongly suggested that dropwise condensation was promoted and sustained throughout the flow condensation process on hydrophobic and patterned surfaces. For the hydrophilic copper minigap, heat transfer coefficients were a strong function of quality, as well as a function of mass flux at higher qualities, which demonstrated the development and growth of a liquid film as quality decreased, and were well predicted by the Kim et al. (2013) correlation, with a mean average error of 8.9%

A novel mouse model of cerebral cavernous malformations based on the two-hit mutation hypothesis recapitulates the human disease

Cerebral cavernous malformations (CCMs) are vascular lesions of the central nervous system appearing as multicavernous, blood-filled capillaries, leading to headache, seizure and hemorrhagic stroke. CCM occurs either sporadically or as an autosomal dominant disorder caused by germline mutation of one of the three genes: CCM1/KRIT1, CCM2/MGC4607 and CCM3/PDCD10. Surgically resected human CCM lesions have provided molecular and immunohistochemical evidence for a two-hit (germline plus somatic) mutation mechanism. In contrast to the equivalent human genotype, mice heterozygous for a Ccm1- or Ccm2-null allele do not develop CCM lesions. Based on the two-hit hypothesis, we attempted to improve the penetrance of the model by crossing Ccm1 and Ccm2 heterozygotes into a mismatch repair-deficient Msh2−/− background. Ccm1+/−Msh2−/− mice exhibit CCM lesions with high penetrance as shown by magnetic resonance imaging and histology. Significantly, the CCM lesions range in size from early-stage, isolated caverns to large, multicavernous lesions. A subset of endothelial cells within the CCM lesions revealed somatic loss of CCM protein staining, supporting the two-hit mutation mechanism. The late-stage CCM lesions displayed many of the characteristics of human CCM lesions, including hemosiderin deposits, immune cell infiltration, increased endothelial cell proliferation and increased Rho-kinase activity. Some of these characteristics were also seen, but to a lesser extent, in early-stage lesions. Tight junctions were maintained between CCM lesion endothelial cells, but gaps were evident between endothelial cells and basement membrane was defective. In contrast, the Ccm2+/−Msh2−/− mice lacked cerebrovascular lesions. The CCM1 mouse model provides an in vivo tool to investigate CCM pathogenesis and new therapies