GreenPhylDB v2.0: An improved database for plant functional genomics

Poster presented at 2009 Annual Research Meeting of the Generation Challenge Programme. Bamako (Mali), 20-23 September 200

Efficiency and Technological Change in Health Care Services in Ontario

This paper presents productivity measurement results for hospital services using panel data for Ontario hospitals between 2003 and 2006. The study uses the Malmquist Productivity index (MPI) obtained through the application of Data Envelopment Analysis (DEA) which is decomposed into efficiency change (ECH), i.e., movement towards the best practice frontier and technological change (TCH), i.e., movement of the frontier itself (Färe et al. [12]). The study also uses kernel density estimation techniques for analysis of efficiency distributions of the productivity scores and their components across different types of hospitals (e.g. small /large and rural /urban) and over time. Our results suggest that in addition to average productivity it is important to examine distributions of productivity and of its components which we find differs by hospital type and over time. We find that productivity growth occurred mostly through improvement in technology and in spite of declining efficiency. The results provide useful insight into the underlying mechanisms of observed changes in overall productivity, in technological change and in technical efficiency change in this vital sector of the health care market.

Locating Depots for Capacitated Vehicle Routing

We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost functions for the MST and k-median parts. We show that the locality gap for this problem is unbounded even under multi-swaps, which contrasts with the uniform case. Nevertheless, we obtain a constant-factor approximation algorithm, using an LP based approach.Comment: 12 pages, 1 figur

Adding a new station and a road link to a road-rail network in the presence of modal competition

In this paper we study the problem of locating a new station on an existing rail corridor and a new junction on an existing road network, and connecting them with a new road segment under a budget constraint. We consider three objective functions and the corresponding optimization problems, which are modeled by means of mixed integer non-linear programs. For small instances, the models can be solved directly by a standard solver. For large instances, an enumerative algorithm based on a discretization of the problem is proposed. Computational experiments show that the latter approach yields high quality solutions within short computing times.This research was done while one of the co-authors (Federico Perea) was enjoying a research stay funded by the Spanish Ministerio de Educacion y Ciencia, under program Jose Castillejo. This research was partially funded by the Canadian Natural Sciences and Engineering Research Council under grant 39682-10, by the Spanish Ministerio de Educacion, Ciencia e Innovacion/FEDER under grant MTM2009-14243, by the Spanish Ministerio de Economia y Competitividad/FEDER under grant MTM2012-37048, and by the Junta de Andalucia/FEDER under grants P09-TEP-5022 and FQM-5849. This support is gratefully acknowledged. Special thanks are due to the referees for their valuable comments and to Javier Fernandez and Lorenzo jaro, from the Spanish railway infrastructure management company ADIF, for providing some of the necessary data for the case study.Perea Rojas Marcos, F.; Mesa López-Colmenar, JA.; Laporte, G. (2014). Adding a new station and a road link to a road-rail network in the presence of modal competition. Transportation Research Part B: Methodological. 68:1-16. https://doi.org/10.1016/j.trb.2014.05.015S1166

A Content Analysis of AIAA/ITEA/ITEEA Conference Special Interest Sessions: 1978-2014

Associations routinely hold annual conferences to aid with professional development and actively promote the ideals of their membership and the profession they represent. The American Industrial Arts Association (AIAA) was created in 1939 and has held an annual conference the past 76 years to further these goals (Starkweather, 1995). Throughout this period, the profession has gone through significant changes that include a paradigm shift from a focus on the products and processes of industry to a broader focus on technological literacy. The AIAA reflected this shift by changing the association name to the International Technology Education Association (ITEA) in 1985. More recently, the association adapted to the increasing focus on engineering education and changed its name again in 2010 to the International Technology and Engineering Educators Association (ITEEA). The ITEEA conference has run consistently throughout this period and remains a cornerstone professional event. This article presents a content analysis of the ITEEA conference special interest sessions (N = 5,639) that took place between 1978-2014. The analysis is intended to highlight, among other topics, conference history, trends and issues, leadership, scholarly research, curriculum, and instructional methods