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Ammari M.L.,Laval University | Roy S.,University of Sherbrooke
2016 International Conference on Computing, Networking and Communications, ICNC 2016 | Year: 2016

This paper provides a performance analysis of communication systems over Rayleigh-product single-output multiple-output (SIMO) channels with maximal-ratio combining (MRC) and selection combining (SC). New closed-form expressions for the exact cumulative distribution function (CDF) and probability density function (PDF) of the post-combining signal-to-noise ratio (SNR) are derived. Then, the performance of MRC and SC techniques, in terms of outage probability and average symbol error rate (SER) is derived. Furthermore, we present new expressions for key metrics characterizing the system performance at the high and low signal-to-noise ratio (SNR) regimes. Monte-Carlo simulation results are presented and their results concur with the analytical results. © 2016 IEEE. Source

Jodoin P.-M.,University of Sherbrooke | Pinheiro F.,Plateforme dImagerie Preclinique | Oudot A.,Plateforme dImagerie Preclinique | Lalande A.,University of Burgundy
IEEE Transactions on Biomedical Engineering | Year: 2015

Single-photon emission computed tomography (SPECT) imaging of the heart is helpful to quantify the left-ventricular ejection fraction and study myocardial perfusion scans. However, these evaluations require a 3-D segmentation of the left-ventricular wall on each phase of the cardiac cycle. This paper presents a fast and interactive graph cut method for 3-D segmentation of the left ventricle (LV) of rats in SPECT images. The method is carried out in three steps. First, 3-D sampling of the LV cavity is made in a spherical-cylindrical coordinate system. Then, a graph-cut-based energy minimization procedure provides delineation of the myocardium centerline surface. From there, it is possible to outline the epicardial and endocardial boundaries by considering the second statistical moment of the SPECT images. An important aspect of our method is to always produce anatomically coherent U-shape results. It also relies on only two intuitive parameters regulating the smoothness and the thickness of the segmentation result. Results show not only that our method is statistically as accurate as human experts, but it is one order of magnitude faster than a state-of-the-art method with a processing time of at most 2 s on a 4-D cardiac image after having determined the LV orientation. © 1964-2012 IEEE. Source

Melancon M.O.,Universite de Sherbrooke | Melancon M.O.,University of Sherbrooke
Applied Physiology, Nutrition and Metabolism | Year: 2015

Normal aging entails significant changes in serotonergic activity and function. Noteworthy, these alterations might predispose older individuals to develop depressive symptoms and contribute to age-related changes in sleep. This study verified if exercise increases tryptophan (Trp) availability to the brain and affects sleep depth and architecture in older men. Nineteen men (aged 64 ± 3 years) undertook a series of 4 tests, which was repeated at follow-up (after 16 weeks of training) as follows: (i) dual-energy X-ray absorptiometry (body composition); (ii) peak O2 consumption, ventilatory threshold, and respiratory compensation point (cardiopulmonary testing); (iii) blood withdrawals immediately before, during, and after exercise for analysis of glucose, lactate, ammonia, free fatty acids (FFA), total proteins, albumin, prolactin, valine, leucine, isoleucine, adiponectin, leptin, free and total Trp, and calculated variable: branched-chain amino acids (BCAA); and (iv) sleep electrophysiology (wake, stage 1, stage 2, stages 3+4 or slow-wave sleep (SWS), stage 5 or rapid eye movements, movement time, leg movements during sleep, apneas, hypopneas, and derivative variables). The intervention consisted of supervised exercise (3× per week × 45 min, 65%–70% peak oxygen uptake (VO2peak) whereas experimental exercise consisted of 1 h of inclined treadmill (~68% VO2peak). Variations in serum prolactin and free Trp/BCAA served as proxies of 5-hydroxytryptamine activity and synthesis rate, respectively. A series of 3 nights was assessed before and after training using laboratory-based sleep electrophysiology (polysomnography: electroelectroencephalography and electromyography and electro-oculography) as follows: (i) familiarization, (ii) inactive trial, and (iii) exercise trial. Aerobic taining increased oxygen uptake at both ventilatory thresholds, whereas body mass decreased. Acute exercise increased free Trp/BCAA ratio by more than 100% of that at rest and remained elevated postexercise. This ratio shared a positive association with FFA levels. After 1 h of exercise, prolactin was higher than that at rest and was positively associated with free Trp/BCAA. However, the acute response to exercise was attenuated following training for many compounds, including free Trp/BCAA, prolactin, lactate, and FFA. Analyses revealed significant main effects of exercise on wake after sleep onset, rapid eye movement onset latency, and time awake overnight. As compared with the inactive trial at baseline, a higher proportion of SWS was observed during the night subsequent to exercise following training. In addition, we found a positive association between resting adiponectin and SWS. The results support the hypothesis that increases in serotonin synthesis and activity might be involved in the antidepressant outcome of exercise in older men. Inasmuch as training lowered the increase in Trp supply during exercise, Trp requirement by the brain in response to exercise might be attenuated by training. Despite gains in cardiorespiratory fitness after training, a day without exercise led to SWS values similar to those at baseline. However, exercise increased the proportion of SWS during subsequent sleep but this could only be found after training. These results provide evidence that not only sleep quantity (duration) but also quality (SWS) could affect circulating adiponectin levels. Finally, a positive correlation was found between sleep depth and circulating adiponectin levels. ©, 2006 National Research Council of Canada. All rights reserved. Source

Poder T.G.,UETMIS and CRCHUS | He J.,University of Sherbrooke | Simard C.,CH of Chicoutimi | Pasquier J.-C.,CHUS
Patient Preference and Adherence | Year: 2014

Objective: To measure the willingness to pay (WTP) of women aged 18–45 years to receive drug treatment for ovulation induction (ie, the social value of normal cycles of ovulation for a woman of childbearing age) in order to feed the debate about the funding of fertility cares.Setting: An anonymous questionnaire was used over the general population of Quebec.Participants: A total of 136 subjects were recruited in three medical clinics, and 191 subjects through an online questionnaire.Method: The questionnaire consisted of three parts: introduction to the problematic, socioeconomic data collection to determine factors influencing the formation of WTP, and a WTP question using the simple bid price dichotomous choice elicitation technique. The econometric estimation method is based on the “random utility theory.” Each subject responding to our questionnaire could express her uncertainty about the answer to our WTP question by choosing the answer “I do not know.”Outcome measure: The WTP in Canadian dollars of women aged 18–45 years to receive drug treatment for ovulation induction.Results: Results are positive and indicate an average WTP exceeding 4,800 CAD, which is much more than the drug treatment cost. There is no evidence of sample frame bias or avidity bias across the two survey modes that cannot be controlled in econometric estimates.Conclusion: Medical treatment for ovulation induction is highly socially desirable in Quebec. © 2014 Poder et al. Source

Panneton B.,Agriculture and Agri Food Canada | Bizeau A.,University of Sherbrooke
American Society of Agricultural and Biological Engineers Annual International Meeting 2014, ASABE 2014 | Year: 2014

In horticulture, it has been demonstrated that color, near infrared (NIR) imagery and plant height could all serve as inputs for algorithms aim at discriminating weeds from crop. Based on these results, we developed an image acquisition platform for use in the field based on two high resolution digital cameras. One is a standard (commercial grade) color camera and the other is a modified version of the same camera model where the infrared filter has been removed and a notch filter was installed to block red light. In the blue and green channels, this second camera captures the same information as the standard color camera but its "red" channel now acquires NIR signal only. The platform was set up to acquire images at a resolution of 0.2 mm/pixel. This opens the door to high definition stereo imaging. This was implemented and it was shown that 3D images of sufficient quality can be produced. The main challenge is dealing with noise when computing disparity maps. Adding the RGB and NIR signals to the 3D spatial data, a 7D data space can be assembled for building algorithms for the discrimination of weeds from crop, an essential building block for precision robotic weeding on the row. Source

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