A large neighbourhood based heuristic for two-echelon routing problems

In this paper, we address two optimisation problems arising in the context of city logistics and two-level transportation systems. The two-echelon vehicle routing problem and the two-echelon location routing problem seek to produce vehicle itineraries to deliver goods to customers, with transits through intermediate facilities. To efficiently solve these problems, we propose a hybrid metaheuristic which combines enumerative local searches with destroy-and-repair principles, as well as some tailored operators to optimise the selections of intermediate facilities. We conduct extensive computational experiments to investigate the contribution of these operators to the search performance, and measure the performance of the method on both problem classes. The proposed algorithm finds the current best known solutions, or better ones, for 95% of the two-echelon vehicle routing problem benchmark instances. Overall, for both problems, it achieves high-quality solutions within short computing times. Finally, for future reference, we resolve inconsistencies between different versions of benchmark instances, document their differences, and provide them all online in a unified format

An annotated pist of Trichoptera collected on Southern Vancouver Island

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Technology integration in postsecondary education: A summary of findings from a set of related meta-analyses

Although the overall research literature on the application of educational technologies to classroom instruction tends to favor their use over their non-use, these results vary considerably depending on what kind of technology is used, who it is used with and, more importantly, under what circumstances and for what instructional purposes it is used. Relatively recent, but well-developed and powerful methodology of systematic reviews, particularly quantitative syntheses (also known as meta-analyses) is especially suitable for addressing questions of that type by systematically summarizing research evidence in given areas of interest in social sciences.This meta-analysis summarizes data from 674 independent primary studies that compared higher degrees of technology use in the experimental condition with less technology in the control condition, in terms of their effects on student learning outcomes in postsecondary education. The result was an overall average weighted effect size of = 0.27 (k = 879, p \u3c .01), indicating low but significant positive effect of technology integration on learning. The follow-up analyses revealed the influence of educational technology used for cognitive support and blended learning instructional settings designed interaction treatments, and technology integration in teacher training, especially when student-centered pedagogical frameworks are used. These findings are of potentially high interest and applied value for educational practitioners, including teachers and school administrators, as well as for instructional designers and developers of educational software

A Meta-Analysis of Teacher and Student-Centered Practices and Processes in Undergraduate Science Education

This meta-analysis investigates the effects of four instructional dimensions rated on a scale from more Teacher-centered (T-C) to more Student-centered (S-C) plus several coded moderator variables on the achievement of undergraduate students in science education courses. More student-centered conditions served as the ‘treatment’ while more teacher-centered conditions were considered the ‘control.’ Hedges’ g, operationalized as the adjusted standardized differences between treatment and control means, served as the outcome measure. The weighted average difference between groups was g̅ = 0.34, k = 140 (random effects analysis), indicating an overall difference in favor of student-centered instruction. Out of four rated dimensions (Pacing, Teacher’s Role, Flexibility, and Adaptation) only Flexibility was significant in metaregression as a negative predictor of effect size. Two demographic variables (i.e., class size & subject matter), and one instructional moderator variables (i.e., technology use) were also significant when added to Flexibility, producing a model that accounted for 36% of total variation in effect size

An exploration of bias in meta-analysis: the case of technology integration research in higher education

© 2014, Springer Science+Business Media New York. This article contains a second-order meta-analysis and an exploration of bias in the technology integration literature in higher education. Thirteen meta-analyses, dated from 2000 to 2014 were selected to be included based on the questions asked and the presence of adequate statistical information to conduct a quantitative synthesis. The weighted random effects average was g++ = 0.393, p \u3c .000. The article goes on to report an assessment of the methodological quality of the thirteen studies based on Cooper’s (Research synthesis and meta-analysis: a step-by-step approach. Sage, Thousand Oaks, 2010) seven stages in the development of a meta-analysis. Two meta-analyses were found to have five out of seven stages where methodological flaws could potentially create biased results. Five meta-analyses contained two flawed stages and one contained one flawed stage. Four of the stages where methodological flaws can create bias are described in detail. The final section attempts to determine how much influence the methodological flaws exerted on the results of the second-order meta-analysis

CCL5 Neutralization Restricts Cancer Growth and Potentiates the Targeting of PDGFRβ in Colorectal Carcinoma

Increased CCL5 levels are markers of an unfavourable outcome in patients with melanoma, breast, cervical, prostate, gastric or pancreatic cancer. Here, we have assessed the role played by CCL5/CCR5 interactions in the development of colon cancer. To do so, we have examined a number of human colorectal carcinoma clinical specimens and found CCL5 and its receptors over-expressed within primary as well as liver and pulmonary metastases of patients compared to healthy tissues. In vitro, CCL5 increased the growth and migratory responses of colon cancer cells from both human and mouse origins. In addition, systemic treatment of mice with CCL5-directed antibodies reduced the extent of development of subcutaneous colon tumors, of liver metastases and of peritoneal carcinosis. Consistently, we found increased numbers of CD45-immunoreactive cells within the stroma of the remaining lesions as well as at the interface with the healthy tissue. In contrast, selective targeting of CCR5 through administration of TAK-779, a CCR5 antagonist, only partially compromised colon cancer progression. Furthermore, CCL5 neutralization rendered the tumors more sensitive to a PDGFRβ-directed strategy in mice, this combination regimen offering the greatest protection against liver metastases and suppressing macroscopic peritoneal carcinosis. Collectively, our data demonstrate the involvement of CCL5 in the pathogenesis of colorectal carcinoma and point to its potential value as a therapeutic target

A meta-analysis of blended learning and technology use in higher education: From the general to the applied

This paper serves several purposes. First and foremost, it is devoted to developing a better understanding of the effectiveness of blended learning (BL) in higher education. This is achieved through a meta-analysis of a sub-collection of comparative studies of BL and classroom instruction (CI) from a larger systematic review of technology integration (Schmid et al. in Comput Educ 72:271-291, 2014). In addition, the methodology of meta-analysis is described and illustrated by examples from the current study. The paper begins with a summary of the experimental research on distance education (DE) and online learning (OL), encapsulated in meta-analyses that have been conducted since 1990. Then it introduces the Bernard et al. (Rev Educ Res 74(3):379-439, 2009) meta-analysis, which attempted to alter the DE research culture of always comparing DE/OL with CI by examining three forms of interaction treatments (i.e., student-student, student-teacher, student-content) within DE, using the theoretical framework of Moore (Am J Distance Educ 3(2):1-6, 1989) and Anderson (Rev Res Open Distance Learn 4(2):9-14, 2003). The rest of the paper revolves around the general steps and procedures (Cooper in Research synthesis and meta-analysis: a step-by-step approach, 4th edn, SAGE, Los Angeles, CA, 2010) involved in conducting a meta-analysis. This section is included to provide researchers with an overview of precisely how meta-analyses can be used to respond to more nuanced questions that speak to underlying theory and inform practice-in other words, not just answers to the big questions. In this instance, we know that technology has an overall positive impact on learning (g+ = +0.35, p \u3c.01, Tamim et al. in Rev Educ Res 81(3):4-28, 2011), but the sub-questions addressed here concern BL interacting with technology in higher education. The results indicate that, in terms of achievement outcomes, BL conditions exceed CI conditions by about one-third of a standard deviation (g+ = 0.334, k = 117, p \u3c.001) and that the kind of computer support used (i.e., cognitive support vs. content/presentational support) and the presence of one or more interaction treatments (e.g., student-student/-teacher/-content interaction) serve to enhance student achievement. We examine the empirical studies that yielded these outcomes, work through the methodology that enables evidence-based decision-making, and explore how this line of research can improve pedagogy and student achievement. © 2014 Springer Science+Business Media New York