University of Guelph

About: University of Guelph is a education organization based out in Guelph, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Testing pointing device performance and user assessment with the ISO 9241, Part 9 standard

Abstract: The IS0 9241, Part 9 Draft International Standard for testing computer pointing devices proposes an evaluation of performance and comfort. In this paper we evaluate the scientific validity and practicality of these dimensions for two pointing devices for laptop computers, a finger-controlled isometric joystick and a touchpad. Using a between-subjects design, evaluation of performance using the measure of throughput was done for one-direction and multi-directional pointing and selecting. Results show a significant difference in throughput for the multi-directional task, with the joystick 27% higher; results for the one-direction task were non-significant. After the experiment, participants rated the device for comfort, including operation, fatigue, and usability. The questionnaire showed no overall difference in the responses, and a significant statistical difference in only the question concerning force required to operate the device - the joystick requiring slightly more force. The paper concludes with a discussion of problems in implementing the IS0 standard and recommendations for improvement.

The Systematics of North American Daphnia (Crustacea: Anomopoda): A Molecular Phylogenetic Approach

Abstract: Despite extensive studies on the ecology and evolution of the freshwater microcrustacean Daphnia, there is little understanding of the evolutionary history of the genus. Past attempts at reconstructing phylogenetic relationships among Daphnia species have been highly controversial, mainly because of the poor taxonomy of the genus. However, following a revised taxonomy of the daphniid fauna of North America, we conducted a comprehensive appraisal of systematic relationships within the genus through the analysis of sequence diversity in 503 b.p. of the 12S rRNA gene of the mtDNA. The large sequence divergence among its 34 North American members indicates that the genus Daphnia originated during the Mesozoic, even though many lineages exhibit extreme morphological stasis. Results from both cladistic and phenetic analyses indicate the presence of three subgenera comprised of 15 species complexes. Only four of these lineages have shown active speciation over the past 3 Ma, suggesting that cladogenesis in the genus has been constrained. Our study also reveals that interspecific hybridization occurs between taxa which show very large sequence divergence (up to 14%), suggesting that reproductive isolation within the genus evolves slowly.

Synergy between sequence and size in Large-scale genomics

Abstract: Until recently the study of individual DNA sequences and of total DNA content (the C-value) sat at opposite ends of the spectrum in genome biology. For gene sequencers, the vast stretches of non-coding DNA found in eukaryotic genomes were largely considered to be an annoyance, whereas genome-size researchers attributed little relevance to specific nucleotide sequences. However, the dawn of comprehensive genome sequencing has allowed a new synergy between these fields, with sequence data providing novel insights into genome-size evolution, and with genome-size data being of both practical and theoretical significance for large-scale sequence analysis. In combination, these formerly disconnected disciplines are poised to deliver a greatly improved understanding of genome structure and evolution.

Acaricide mode of action

Abstract: The last few years have seen the introduction of an unprecedented number of new classes of acaricides with novel or under-exploited modes of action, discovered by traditional screening. Acaricide research has uncovered several unrelated compounds that possess improved properties. Pyridaben, acequinocyl, diafenthiuron, etoxazole, spirodiclofen and bifenazate, in particular, are acaricides that are safe to beneficials, have low mammalian toxicity and short environmental persistence. Many of the new acaricides appear to affect mitochondrial respiration, and previously unknown targets affecting mite growth and development have been identified, offering new opportunities for mite control.