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During slowwave sleep, neurons of the thalamocortical network are engaged in a slow oscillation (<1 Hz), which consists of an alternation between the active and the silent states. Several studies have provided insights on the transition from the silent, which are essentially periods of disfacilitation, to the active states. However, the conditions leading to the synchronous onset of the silent state remain elusive. We hypothesized that a synchronous input to local inhibitory neurons could contribute to the transition to the silent state in the cat suprasylvian gyrus during natural sleep and under ketamine-xylazine anesthesia. After partial and complete deafferentation of the cortex, we found that the silent state onset was more variable among remote sites. We found that the transition to the silent state was preceded by a reduction in excitatory postsynaptic potentials and firing probability in cortical neurons. We tested the impact of chloride-mediated inhibition in the silent-state onset. We uncovered a long-duration (100–300 ms) inhibitory barrage occurring about 250 ms before the silent state onset in 3–6% of neurons during anesthesia and in 12–15% of cases during natural sleep. These inhibitory activities caused a decrease in cortical firing that reduced the excitatory drive in the neocortical network. That chain reaction of disfacilitation ends up on the silent state. Electrical stimuli could trigger a network silent state with a maximal efficacy in deep cortical layers. We conclude that long-range afferents to the neocortex and chloride-mediated inhibition play a role in the initiation of the silent state. © 2015 the American Physiological Society. Source


Romero M.,University Laval
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

In this study, digital game design is analyzed as a team-based knowledge modelling process. In the context of a graduate seminar, the students were organized in teams and were asked to design a serious game. In the early stages of the process, each team had the possibility to engage in a topic suggested by the professor or decide their topic of interest. Half of the teams choose a suggested topic (herd immunity, intergenerational communication, active ageing); the other half proposed a topic of their choice (inuits and micmacs, banker-customer relationship, French as a Foreign Language). In both cases, the students should engage in a participative design process which requires a learner-centered analysis. We analyze both the digital game design process and outcomes of the game design from the perspective of social participation and the 4C competencies deployed in the game design process: communication, collaboration, creativity and critical thinking. © Springer International Publishing Switzerland 2016. Source


Arbour D.,University of Montreal | Tremblay E.,University of Montreal | Martineau E.,University of Montreal | Julien J.-P.,University Laval | Robitaille R.,University of Montreal
Journal of Neuroscience | Year: 2015

Amyotrophic lateral sclerosis (ALS) is a late-onset neuromuscular disease characterized by progressive loss of motor neurons (MNs) preceded by neuromuscular junction (NMJ) denervation. Despite the importance of NMJ denervation in ALS, the mechanisms involved remain unexplored and ill defined. The contribution of glial cells in the disease has been highlighted, including axonal Schwann cell activation that precedes the decline of motor function and the onset of hindlimb paralysis. Because NMJ denervation occurs early in the process and that perisynaptic Schwann cells (PSCs), glial cells at the NMJ, regulate morphological stability, integrity, and repair of the NMJ, one could predict that PSC functions would be altered even before denervation, contributing to NMJ malfunctions. We tested this possibility using a slowly progressive model of ALS (SOD1G37R mice).We observed a normal NMJ organization at a presymptomatic stage of ALS (120 d), but PSC detection of endogenous synaptic activity revealed by intracellular Ca2+ changes was enhanced compared with their wild-type littermates. This inappropriate PSC decoding ability was associated with an increased level of neurotransmitter release and dependent on intrinsic glial properties related to enhanced muscarinic receptor activation. The alteration of PSC muscarinic receptor functions also persists during the preonset stage of the disease and became dependent on MN vulnerability with age. Together, these results suggest that PSC properties are altered in the disease process in a manner that would be detrimental for NMJ repair. The impairments of PSC functions may contribute to NMJ dysfunction and ALS pathogenesis. © 2015 the authors. Source


Kolaei A.,Concordia University at Montreal | Rakheja S.,Concordia University at Montreal | Richard M.J.,University Laval
European Journal of Mechanics, B/Fluids | Year: 2015

Three-dimensional liquid slosh in a horizontal cylindrical tank is analyzed assuming inviscid, incompressible and irrotational flows under simultaneous application of longitudinal and lateral accelerations, idealizing a braking-in-a-turn maneuver in a road tanker. The spectral problem of liquid slosh within the partially-filled tank of arbitrary cross-section and finite length is initially formulated using the higher order boundary element method (BEM). The three-dimensional Laplace equation is subsequently reduced to a two-dimensional Helmholtz equation using the separation of variables, which significantly reduces the computing demand. The computing time is further reduced by reducing the generalized eigenvalue problem to a standard one considering only the velocity potential on the half free-surface length. The resulting natural slosh frequencies and modes are implemented in a linear multimodal method to obtain generalized coordinates of the free-surface in a partly-filled circular cross-section tank. The slosh forces and moments are subsequently formulated in terms of generalized coordinates and hydrodynamic coefficients considering the damping due to liquid viscosity in the boundary layer. It is shown that the proposed BEM integrating the multimodal method yields computationally efficient solution of the three-dimensional liquid slosh within moving horizontal tanks. The validity of the model is demonstrated using reported analytical and experimental results. The range of applicability of the linear theory for predicting three-dimensional transient slosh is further discussed through comparisons with nonlinear simulation results obtained from a commercial CFD code. The results suggest that the linear theory can predict the slosh forces and moments with reasonably good accuracy when the steady-magnitudes of the lateral and longitudinal accelerations are less than 0.3 g and 0.2 g, respectively, for a tank with aspect ratio in the order of 2.4. © 2015 Elsevier Masson SAS. All rights reserved. Source


Beaudreau B.C.,University Laval | Lightfoot H.D.,Quebecs Global Environmental and Climate Change Center 3
Energy | Year: 2015

For over three decades, worldwide R&D expenditure has risen steadily, reaching $1.3 trillion in 2011. Underlying this unprecedented growth is a deeply-held belief that R&D is a prime mover of economic growth. Ironically, despite three decades of massive R&D expenditure, growth levels have remained substantially lower than that of the immediate post World War II period. This raises important theoretical questions regarding R&D and its impact on growth per se. For example, R&D-growth has been modeled and continues to be modeled as an unbounded set. This has not been inconsequential because it has introduced an upward bias in growth projections as evidenced in the literature. More importantly, are there physically-determined upper limits to R&D-based growth and, if so, what are they? This paper uses the physical sciences to map the physical limits to R&D-based innovation. A consilient model of economic growth is presented and upper bounds for energy efficiency-based growth rates are provided, both for individual energy sectors and globally. We find that with economic growth by innovation limited by physical conditions, increasing the rate of economic growth can only come through increasing the rate of energy consumption. © 2015 Elsevier Ltd. Source

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