Éditorial: Enfin,une voix canadienne!

Abstract

This article investigates some of the specific features involved in accommodating the idea of actual infinity as it appears in set theory. It focuses on the conceptions of two individuals with sophisticated mathematics background, as manifested in their engagement with variations of a well-known paradox: the ping-pong ball conundrum. The APOS theory is used as a framework to interpret participants’ efforts to resolve the paradoxes. The cases discussed focus on how transfinite subtraction may be conceptualized, and they suggest that there is more to accommodating the idea of actual infinity than the ability to act on a completed object—rather, it is the manner in which objects are acted upon that is also significant.     

Politics,public servants,and profits: Institutional complexity and temporary hybridization in a public infrastructure alliance project

Public infrastructure projects must comply with the divergent and even conflicting demands of multiple institutional logics causing institutional complexity. Despite the increasing interest in different forms of complexities in projects, we lack empirical illustrations and rigorous theorizing of mechanisms for responding to institutional complexity. This paper demonstrates how public buyers of a tunnel construction project formed a hybrid organization of a multi-party project alliance to respond to institutional complexity. We delineate a process of temporary hybridization through which the competing logics of a bureaucratic state, corporate market, and multiple professions were combined within the temporary project alliance organization. Such temporary hybridization not only focused on selective coupling with external demands but also mitigated internal tensions. Our findings emphasize a blended organizational structure, jointly formed governance and incentive systems, and the facilitation of social interaction to build a temporary yet sustainable hybrid organization capable of combining conflicting institutional logics.     

Design and Analysis of Experiments on Nonconvex Regions

Modeling a response over a nonconvex design region is a common problem in diverse areas such as engineering and geophysics. The tools available to model and design for such responses are limited and have received little attention. We propose a new method for selecting design points over nonconvex regions that is based on the application of multidimensional scaling to the geodesic distance. Optimal designs for prediction are described, with special emphasis on Gaussian process models, followed by a simulation study and an application in glaciology. Supplementary materials for this article are available online.     

A Pilot Study of the VirtuSphere as a Virtual Reality Enhancement

This pilot study assessed the utility and acceptability of the VirtuSphere, a cutting edge navigation platform designed to enhance presence in virtual environments. The VirtuSphere includes a 12-ft hollow sphere within which the user stands, and it rolls within a wheeled platform, in any direction, according to the user's steps. The pilot was a within-subject crossover design comparing the VirtuSphere to standard game controller navigation. The comparison was based on locomotion in Virtual Iraq, a virtual world resembling Iraqi war zones. Participants were 10 active duty soldiers not suffering from posttraumatic stress disorder. Results indicated that there were negligible differences in sense of presence, simulator sickness, and satisfaction across the two navigation systems. Although the VirtuSphere may provide entertainment value, these results do not provide initial support for the use of the VirtuSphere to improve constructs thought to be important to behavioral health applications of virtual reality. Potential improvements to the design of the VirtuSphere are discussed.     

An opinion on imaging challenges in phenotyping field crops

Almost all the world’s food is grown in open fields, where plant phenotypes can be very different from those observed in greenhouses. Geneticists and agronomists studying food crops routinely detect, measure, and classify a wide variety of phenotypes in fields that contain many visually distinct types of a single crop. Augmenting humans in these tasks by automatically interpreting images raises some important and nontrivial challenges for research in computer vision. Nonetheless, the rewards for overcoming these obstacles could be exceptionally high for today’s 7 billion people, let alone the 9.6 billion projected by 2050 (United Nations Department of Economic and Social Affairs, Population Division, World Population Prospects: The 2012 Revision). To stimulate dialog between researchers in computer vision and those in genetics and agronomy, we offer our views on three computational challenges that are central to many phenotyping tasks. These are disambiguating one plant from another; assigning an individual plant’s organs to it; and identifying field phenotypes from those shown in archival images. We illustrate these challenges with annotated photographs of maize highlighting the regions of interest. We also describe some of the experimental, logistical, and photographic constraints on image collection and processing. While collecting the data sets needed for algorithmic experiments requires sustained collaboration and funding, the images we show and have posted should allow one to consider the problems, think of possible approaches, and decide on the next steps.     

Agriculture’s role in the Indian enigma: help or hindrance to the crisis of undernutrition?

In recent decades India has achieved one of the fastest economic growth rates in the world, yet its progress against both child and adult undernutrition has been sluggish at best. While this Indian variant of the so-called Asian enigma presents many puzzles, one of the puzzles pertains to agriculture’s role. Many researchers and policymakers have high expectations of agriculture’s potential to reduce undernutrition, despite a lack of substantive evidence. In this paper we assess this tenuous evidence base by exploring two key channels by which agricultural production conditions can influence nutritional outomes: a food consumption pathway and a maternal employment–time use pathway. We conclude with an appraisal of some possible entry points for pro-nutrition agricultural policies.     

The House Mouse (Mus musculus L.) Exerts Strong Differential Grain Consumption Preferences among Hard Red and White Spring Wheat (Triticum aestivum L.) Varieties in a Single‐Elimination Tournament Design

Wheat (Triticum aestivum L.) plays a central role in the health and nutrition of humans. Yet, little is known about possible flavor differences among different varieties. We have developed a model system using the house mouse (Mus musculus L.) to determine feeding preferences as a prelude to extending results to human sensory analysis. Here, we examine the application of a single‐elimination tournament design to the analysis of consumption preferences of a set of hard red and hard white spring wheat varieties. A single‐elimination tournament design in this case pairs 2 wheat varieties and only 1 of the 2 is advanced to further tests. Preferred varieties were advanced until an overall “winner” was identified; conversely, less desirable varieties were advanced such that an overall “loser” was identified. Hollis and IDO702 were the winner and loser, respectively, for the hard red varieties, and Clear White 515 and WA8123 were the winner and loser, respectively, for the hard white varieties. When using the more powerful protocol of 14 mice and a 4?d trial, differences in mean daily consumption preferences of 2 varieties were separated at P‐values as small as 2 × 10^?8. The single‐elimination tournament design is an efficient means of identifying the most and least desirable varieties among a larger set of samples. One application for identifying the 2 extremes in preference within a group of varieties would be to use them as parents of a population to identify quantitative trait loci for preference.