Performance of Optimum Combining in a Poisson Field of Interferers and Rayleigh Fading Channels

This paper studies the performance of antenna array processing in distributed multiple access networks without power control. The interference is represented as a Poisson point process. Desired and interfering signals are subject to both path-loss fading (with an exponent greater than 2) and to independent Rayleigh fading. Using these assumptions, we derive the exact closed form expression for the cumulative distribution function of the output signal-to-interference-plus-noise ratio when optimum combining is applied. This results in a pertinent measure of the network performance in terms of the outage probability, which in turn provides insights into the network capacity gain that could be achieved with antenna array processing. We present and discuss examples of applications, as well as some numerical results.Comment: Submitted to IEEE Trans. on Wireless Communication (Jan. 2009

Rôle des colloïdes dans la spéciation physique des métaux dans un panache majeur de dispersion d’eaux usées municipales

La spéciation physique des métaux rejetés par les effluents d’eaux usées municipales est fortement influencée par les conditions physico-chimiques des eaux réceptrices. Les zones de rejet d’effluents municipaux sont des milieux riches en matières organiques où les métaux sont susceptibles d’être fortement complexés et où la présence de colloïdes peut modifier la bioaccumulation et la biodisponibilité des métaux. La distribution de métaux (Al, Cd, Cu, Fe, Mn, Ag et Zn) a été déterminée dans les fractions dissoute ( 10 kDa) et perméable (ultrafiltrée  10 kDa) and permeable fractions (ultrafiltered < 10 kDa) at different points within the dispersion plume of the major effluent from the Montreal treatment plant. Concentrations of colloidal and permeable metals were typically high near the effluent outfall. Because of the treatment process used by the City of Montreal, this effluent is a major source of Fe and more than 70% of dissolved Fe is present in colloidal form. Of the metals studied, Ag was most associated with colloids near the outfall, followed by Cu. Colloids found in the so-called dissolved or filterable phase can influence the transport and fate of discharged metals in different ways. The colloidal proportion, however, declines rapidly during the mixing of wastewater with receiving water, which seems to suggest that this fraction, by its lower abundance, could have limited influence on the long-range transport of metals released by the effluent. Our results provide information on the role of colloids in determining the geochemical fate of metals contained in wastewater once they are released to the receiving environment. The study highlights the importance of physical speciation in the assessment of the environmental impact of urban effluents on discharge areas

Deoxynivalenol (DON) naturally contaminated feed impairs the immune response induced by porcine reproductive and respiratory syndrome virus (PRRSV) live attenuated vaccine

Cereal commodities are frequently contaminated with mycotoxins produced by the secondary metabolism of fungal infection. Among these contaminants, deoxynivalenol (DON), also known as vomitoxin, is the most prevalent type B trichothecene mycotoxin worldwide. Pigs are very sensitive to the toxic effects of DON and are frequently exposed to naturally contaminated feed. Recently, DON naturally contaminated feed has been shown to decrease porcine reproductive and respiratory syndrome virus (PRRSV) specific antibody responses following experimental infection. The objective of this study was to determine the impact of DON naturally contaminated feed on the immune response generated following vaccination with PRRSV live attenuated vaccine. Eighteen pigs were randomly divided into three experimental groups of 6 animals based on DON content of the diets (0, 2.5 and 3.5 mg DON/kg). They were fed these rations one week prior to the vaccination and for all the duration of the immune response evaluation. All pigs were vaccinated intra-muscularly with one dose of Ingelvac® PRRSV modified live vaccine (MLV). Blood samples were collected at day −1, 6, 13, 20, 27 and 35 post vaccination (pv) and tested for PRRSV RNA by RT-qPCR and for virus specific antibodies by ELISA. Results showed that ingestion of DON-contaminated diets significantly decreased PRRSV viremia. All pigs fed control diet were viremic while only 1 (17%) and 3 (50%) out of 6 pigs were viremic in the groups receiving 3.5 and 2.5 mg of DON/kg, respectively. Subsequently, all pigs fed control diet developed PRRSV specific antibodies while only viremic pigs that were fed contaminated diets have developed PRRSV specific antibodies. These results suggest that feeding pigs with DON-contaminated diet could inhibit vaccination efficiency of PRRSV MLV by severely impairing viral replication

Fire performance of self-tapping screws in tall mass-timber buildings

Building elements are required to provide sufficient fire resistance based on requirements set forth in the National Building Code of Canada (NBCC). Annex B of the Canadian standard for wood engineering design (CSA O86-19) provides a design methodology to calculate the structural fireresistance of large cross-section timber elements. However, it lacks at providing design provisions for connections. The objectives of this study are to understand the fire performance of modern mass timber fasteners such as self-tapping screws, namely to evaluate their thermo-mechanical behavior and to predict their structural fire-resistance for standard fire exposure up to 2 h, as would be required for tall buildings in Canada. The results present the great fire performance of using self-tapping screws under a long time exposure on connections in mass timber construction. The smaller heated area of the exposed surface has limited thermal conduction along the fastener’s shanks and maintained their temperature profiles relatively low for two hours of exposure. Based on the heat-affected area, the study presents new design principles to determine the residual length of penetration that would provide adequate load-capacity of the fastener under fire conditions. It also allows determining safe fire-resistance values for unprotected fasteners in mass timber construction exposed up to two hours of standard fire exposure

Whole genome sequencing of porcine reproductive and respiratory syndrome virus 2 (PRRSV) from field clinical samples improves the genomic surveillance of the virus

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major economic concern worldwide. There are currently large data sets available about the ORF5 gene of the virus, with thousands of sequences available, but little data are currently available on the full-length genome of PRRSV. We hypothesized that whole-genome sequencing (WGS) of the PRRSV genome would allow better epidemiological monitoring than ORF5 gene sequencing. PRRSV PCR-positive serum, oral fluid, and tissue clinical samples submitted to the diagnostic laboratory for routine surveillance or diagnosis of PRRSV infection in Québec, Canada, swine herds were used. The PRRSV reverse transcription-quantitative PCR Cq values of the processed samples varied between 11.5 and 34.34. PRRSV strain genomes were isolated using a poly (A)-tail method and were sequenced with a MiSeq Illumina sequencer. Ninetytwo full-length PRRSV genomes were obtained from 88 clinical samples out of 132 tested samples, resulting in a PRRSV WGS success rate of 66.67%. Three important deletions in ORF1a were found in most wild-type (i.e., not vaccine-like) strains. The importance of these deletions remains undetermined. Two different full-length PRRSV genomes were found in four different samples (three serum samples and one pool of tissues), suggesting a 4.55% PRRSV strain coinfection prevalence in swine. Moreover, six PRRSV whole genomes (6.52% of PRRSV strains) were found to cluster differently than they did under the ORF5 classification method. Overall, WGS of PRRSV enables better strain classification and/or interpretation of results in 9.10% of clinical samples than ORF5 sequencing, as well as allowing interesting research avenues

Porcine reproductive and respiratory syndrome virus whole-genome sequencing efficacy with field clinical samples using a poly(A)-tail viral genome purification method

The genomic surveillance of porcine reproductive and respiratory syndrome virus (PRRSV) is based on sequencing of the ORF5 gene of the virus, which covers only 4% of the entire viral genome. It is expected that PRRSV whole-genome sequencing (WGS) will improve PRRSV genomic data and allow better understanding of clinical discrepancies observed in the field when using ORF5 sequencing. Our main objective was to implement an efficient method for WGS of PRRSV from clinical samples. The viral genome was purified using a poly(A)-tail viral genome purification method and sequenced using Illumina technology. We tested 149 PRRSV-positive samples: 80 sera, 33 lungs, 33 pools of tissues, 2 oral fluids, and 1 processing fluid (i.e., castration liquid). Overall, WGS of 67.1% of PRRSV-positive cases was successful. The viral load, in particular for tissues, had a major impact on the PRRSV WGS success rate. Serum was the most efficient type of sample to conduct PRRSV WGS poly(A)-tail assays, with a success rate of 76.3%, and this result can be explained by improved sequencing reads dispersion matching throughout the entire viral genome. WGS was unsuccessful for all pools of tissue and lung samples with Cq values > 26.5, whereas it could still be successful with sera at Cq ≤ 34.1. Evaluation of results of highly qualified personnel confirmed that laboratory skills could affect PRRSV WGS efficiency. Oral fluid samples seem very promising and merit further investigation because, with only 2 samples of low viral load (Cq = 28.8, 32.8), PRRSV WGS was successful

La présentation de la commémoration du 11 novembre dans la presse au Canada et en France : une étude comparative (1919-1999)

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

A shade tolerance index for common understory species of northeastern North America

Since Baker's [Baker, F.S., 1949. A revised tolerance table. J. For. 47, 179-181] classic contribution, shade tolerance indices have not been much modified for North American plant species. While many common tree and shrub species are included in the shade tolerance index, much less is known about this characteristic for the abundant and rich understory vascular and nonvascular plant layers. The classification of the shade tolerance is widely used to compare relative growth and survival among plant species under closed canopies and is also fundamental to an understanding of stand development following small and large scale disturbances. Although qualitative, it is frequently used both in research and management implications. Here we provide a significant revision to Baker's shade tolerance table to include the most common forest understory plant species found in northeastern North America forests. Our index is based on: (1) the compilation of the opinions of five experts, (2) a comparison with Ellenberg's index from Europe as well as, (3) information from current literature. For most of the 347 plant species investigated, a consistent and robust shade tolerance index, ranging between 1 (very tolerant) and 9 (very intolerant), was found. Here we present revised shade indices for 71 tree and shrub species, 185 herbaceous species, and 91 bryophyte and lichen species