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.

Rhodococcus equi: an animal and human pathogen.

Abstract: Recent isolations of Rhodococcus equi from cavitatory pulmonary disease in patients with AIDS have aroused interest among medical microbiologists in this unusual organism. Earlier isolations from humans had also been in immunosuppressed patients following hemolymphatic tumors or renal transplantation. This organism has been recognized for many years as a cause of a serious pyogranulomatous pneumonia of young foals and is occasionally isolated from granulomatous lesions in several other species, in some cases following immunosuppression. The last decade has seen many advances in understanding of the epidemiology, pathogenesis, diagnosis, treatment, and immunity to infection in foals. The particular susceptibility of the foal is not understood but can be explained in part by a combination of heavy challenge through the respiratory route coinciding with declining maternally derived antibody in the absence of fully competent foal cellular immune mechanisms. R. equi is largely a soil organism but is widespread in the feces of herbivores. Its growth in soil is considerably improved by simple nutrients it obtains from herbivore manure. About one-third of human patients who have developed R. equi infections had contact in some way with herbivores or their manure. Others may have acquired infection from contact with soil or wild bird manure. R. equi is an intracellular parasite, which explains the typical pyogranulomatous nature of R. equi infections, the predisposition to infection in human patients with defective cell-mediated immune mechanisms, and the efficacy of antimicrobial drugs that penetrate phagocytic cells.

Upscaling sparse ground‐based soil moisture observations for the validation of coarse‐resolution satellite soil moisture products

Abstract: [1] The contrast between the point-scale nature of current ground-based soil moisture instrumentation and the ground resolution (typically >102 km2) of satellites used to retrieve soil moisture poses a significant challenge for the validation of data products from current and upcoming soil moisture satellite missions. Given typical levels of observed spatial variability in soil moisture fields, this mismatch confounds mission validation goals by introducing significant sampling uncertainty in footprint-scale soil moisture estimates obtained from sparse ground-based observations. During validation activities based on comparisons between ground observations and satellite retrievals, this sampling error can be misattributed to retrieval uncertainty and spuriously degrade the perceived accuracy of satellite soil moisture products. This review paper describes the magnitude of the soil moisture upscaling problem and measurement density requirements for ground-based soil moisture networks. Since many large-scale networks do not meet these requirements, it also summarizes a number of existing soil moisture upscaling strategies which may reduce the detrimental impact of spatial sampling errors on the reliability of satellite soil moisture validation using spatially sparse ground-based observations.

Extending Fitts' law to two-dimensional tasks

Abstract: Fitts' law, a one-dimensional model of human movement, is commonly applied to two-dimensional target acquisition tasks on interactive computing systems. For rectangular targets, such as words, it is demonstrated that the model can break down and yield unrealistically low (even negative!) ratings for a task's index of difficulty (ID). The Shannon formulation is shown to partially correct this problem, since ID is always ≥ 0 bits. As well, two alternative interpretations “target width” are introduced that accommodate the two-dimensional nature of tasks. Results of an experiment are presented that show a significant improvement in the model's performance using the suggested changes.

Minimum information about a marker gene sequence (MIMARKS) and minimum information about any (x) sequence (MIxS) specifications.

Abstract: Here we present a standard developed by the Genomic Standards Consortium (GSC) for reporting marker gene sequences—the minimum information about a marker gene sequence (MIMARKS). We also introduce a system for describing the environment from which a biological sample originates. The ‘environmental packages’ apply to any genome sequence of known origin and can be used in combination with MIMARKS and other GSC checklists. Finally, to establish a unified standard for describing sequence data and to provide a single point of entry for the scientific community to access and learn about GSC checklists, we present the minimum information about any (x) sequence (MIxS). Adoption of MIxS will enhance our ability to analyze natural genetic diversity documented by massive DNA sequencing efforts from myriad ecosystems in our ever-changing biosphere.

Taxonomic basis for variation in the colonization strategy of arbuscular mycorrhizal fungi

Abstract: Summary • Arbuscular mycorrhizal fungi (AMF) are important components of terrestrial communities but the basic ecology of individual AMF, including their colonization strategy, remains unclear. The colonizing behaviours of 21 AMF isolates from three families (Acaulosporaceae, Gigasporaceae and Glomaceae) were compared to test for a relationship between AMF taxonomy and colonization strategy. • Both the rate and extent of colonization were considered by measuring percentage root colonization, root fungal biomass, soil hyphal length and soil fungal biomass over 12 wk. • Most Glomaceae isolates colonized roots before Acaulosporaceae and Gigasporaceae isolates. The fastest colonizers were also often the most extensive. Taxonomic differences were apparent in the amount and proportion of fungal biomass found in roots vs in soil. Glomaceae isolates had high root colonization but low soil colonization, Gigasporaceae isolates showed the opposite trend whereas Acaulosporaceae isolates had low root and soil colonization. These results were similar for four different host plants. • The results indicate that the colonizing strategies of AM fungi differ considerably and that this variation is taxonomically based at the family level. Arbuscular mycorrhizal fungal taxonomy therefore has a functional basis.