1,428 research outputs found
Editors' Note / Note de la rédaction
It was with more than a little trepidation that I deposited my doctoral thesis at the University of Ottawa this past September.
These feelings were, of course, accompanied by a great deal of satisfaction and relief at having (nearly) completed a project that I
have been working on for years now, and for which I remain passionate. My trepidation stems from the usual feelings of
anxiety that come with submitting a thesis: I pray to Clio for a speedy administrative process and for a timely and successful
defence. I hope the readers are satisfied with the work, but I also look forward to discussing it in detail with five different people who have actually read it! /J’avais envoyé cet hiver les étudiants de mon cours de méthode historique à Bibliothèque et archives Canada. J’étais alors enthousiasmé par le succès de l’activité : les étudiants s’étaient lancés à la recherche de documents couvrant une période historique et un thème spécifique choisi en classe. La phase de recherche et de consultation des
documents archivistiques avait ravi les étudiants, qui étaient fascinés par le processus de recherche documentaire et la facilité relative avec laquelle ils
avaient eu accès aux documents
Static and dynamic pitching moment measurements on a family of elliptic cones at Mach number 11 in helium
Static and dynamic pitching moment measurements were made on a family of constant volume elliptic cones about two fixed axes of oscillation in the NAE helium hypersonic wind tunnel at a Mach number of 11 and at Reynolds numbers based on model length of up to 14 million. Viscous effects on the stability derivatives were investigated by varying the Reynolds number for certain models by a factor as large as 10. The models investigated comprised a 7.75 deg circular cone, elliptic cones of axis ratios 3 and 6, and an elliptic cone with conical protuberances
The Wisconsin magmatic terrane: An Early Proterozoic greenstone-granite terrane formed by plate tectonic processes
The Wisconsin magmatic terrane (WMT) is an east trending belt of dominantly volcanic-plutonic complexes of Early Proterozoic age (approx. 1850 m.y.) that lies to the south of the Archean rocks and Early Proterozoic epicratonic sequence (Marquette Range Supergroup) in Michigan. It is separated from the epicratonic Marquette Range Supergroup by the high-angle Niagara fault, is bounded on the south, in central Wisconsin, by Archean gneisses, is truncated on the west by rocks of the Midcontinent rift system, and is intruded on the east by the post-orogenic Wolf river batholith. The overall lithologic, geochemical, metallogenic, metamorphic, and deformational characteristics of the WMT are similar to those observed in recent volcanic arc terranes formed at sites of plate convergence. It is concluded that the WMT represents an evolved oceanic island-arc terrane accreated to the Superior craton in the Early Proterozoic. This conclusion is strengthened by the apparent absence of Archean basement from most of the WMT, and the recent recognition of the passive margin character of the epicratonic Marquette Range Supergroup
Analysis of three works for solo flute : Partita in A minor by J.S. Bach, Fantasie in A minor by G.P. Telemann, and Sonata in A minor by C.P.E. Bach
Not provided
Two-Speed Rotorcraft Research Transmission Power-Loss Associated with the Lubrication and Hydraulic Rotating Feed-Through Design Feature
An investigation was completed into the power loss associated with a rotating feed-through (RFT) design feature used to transfer lubrication and a hydraulic control signal from the static reference frame to a rotating reference frame in the NASA GRC two-speed transmission tests conducted in the Variable-Speed Drive Test Rig. The RFT feature, not commercially available, was created specifically for this research project and is integral to all two-speed transmission configurations tested, as well as a variant concept design for a geared variable-speed transmission presented at AHS Forum 71 in 2015. The experimental set-up and results from measurements in the isolated rotating-feed-through (RFT) experiments are presented. Results were used in an overall power loss assessment for a scaled conceptual 1,000 horsepower inline concentric two-speed transmission to support a NASA Revolutionary Vertical Lift Technologies (RVLT) Technical Challenge, demonstrating 50% speed change with less than 2% power loss while maintaining current power-to-weight ratios
Two-Speed Rotorcraft Research Transmission Power-Loss Associated with the Lubrication and Hydraulic Rotating Feed-Through Design Feature
An investigation was completed into the power loss associated with a rotating feed-through (RFT) design feature used to transfer lubrication and a hydraulic control signal from the static reference frame to a rotating reference frame in the NASA GRC two-speed transmission tests conducted in the Variable-Speed Drive Test Rig. The RFT feature, not commercially available, was created specifically for this research project and is integral to all two-speed transmission configurations tested, as well as a variant concept design for a geared variable-speed transmission presented at AHS Forum 71 in 2015. The experimental set-up and results from measurements in the isolated rotating-feed-through (RFT) experiments are presented. Results were used in an overall power loss assessment for a scaled conceptual 1,000 horsepower inline concentric two-speed transmission to support a NASA Revolutionary Vertical Lift Technologies (RVLT) Technical Challenge, demonstrating 50% speed change with less than 2% power loss while maintaining current power-to-weight ratios
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Corticocortical feedback increases the spatial extent of normalization
Normalization has been proposed as a canonical computation operating across different brain regions, sensory modalities, and species. It provides a good phenomenological description of non-linear response properties in primary visual cortex (V1), including the contrast response function and surround suppression. Despite its widespread application throughout the visual system, the underlying neural mechanisms remain largely unknown. We recently observed that corticocortical feedback contributes to surround suppression in V1, raising the possibility that feedback acts through normalization. To test this idea, we characterized area summation and contrast response properties in V1 with and without feedback from V2 and V3 in alert macaques and applied a standard normalization model to the data. Area summation properties were well explained by a form of divisive normalization, which computes the ratio between a neuron's driving input and the spatially integrated activity of a “normalization pool.” Feedback inactivation reduced surround suppression by shrinking the spatial extent of the normalization pool. This effect was independent of the gain modulation thought to mediate the influence of contrast on area summation, which remained intact during feedback inactivation. Contrast sensitivity within the receptive field center was also unaffected by feedback inactivation, providing further evidence that feedback participates in normalization independent of the circuit mechanisms involved in modulating contrast gain and saturation. These results suggest that corticocortical feedback contributes to surround suppression by increasing the visuotopic extent of normalization and, via this mechanism, feedback can play a critical role in contextual information processing
Stability of a Nonequilibrium Interface in a Driven Phase Segregating System
We investigate the dynamics of a nonequilibrium interface between coexisting
phases in a system described by a Cahn-Hilliard equation with an additional
driving term. By means of a matched asymptotic expansion we derive equations
for the interface motion. A linear stability analysis of these equations
results in a condition for the stability of a flat interface. We find that the
stability properties of a flat interface depend on the structure of the driving
term in the original equation.Comment: 14 pages Latex, 1 postscript-figur
Novel Quenched Disorder Fixed Point in a Two-Temperature Lattice Gas
We investigate the effects of quenched randomness on the universal properties
of a two-temperature lattice gas. The disorder modifies the dynamical
transition rates of the system in an anisotropic fashion, giving rise to a new
fixed point. We determine the associated scaling form of the structure factor,
quoting critical exponents to two-loop order in an expansion around the upper
critical dimension d. The close relationship with another quenched
disorder fixed point, discovered recently in this model, is discussed.Comment: 11 pages, no figures, RevTe
Susceptibility of blue-winged teal, gadwall, and lesser scaup ducklings to experimental infection with Streptocara crassicauda
Blue-winged teal, gadwall, and lesser scaup ducklings were exposed experimentally to identical doses of Streptocara crassicauda larvae. The heaviest infections developed in the teal. Gadwall were also highly susceptible and infection levels were generally similar to those in teal. Lesser scaup developed comparatively light infections. Lesions were restricted to the gizzard and occurred in the softer areas of the lining under the tendinous surfaces. Nematodes were generally confined to the lesions in scaup, but not in teal or gadwall. In these two species, they were also found elsewhere under the softer portions of the lining and, to a lesser extent, under the grinding plates. Teal and gadwall developed more and larger lesions because of the greater number of nematodes that established. When corrected for worm number, no difference in lesion size was found among the three species
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