470 research outputs found
MAT-762: BUILDING SUSTAINABLE CONTINUOUSLY REINFORCED CONCRETE PAVEMENT USING GFRP BARS: CASE STUDY-HIGHWAY 40 WEST-MONTREAL, CANADA
Continuously reinforced concrete pavement designs (CRCP) are premium pavement designs that are often used on heavily-trafficked roadways and urban corridors. Although CRCP typically is an effective, long-lasting pavement design, it can develop performance problems when the aggregate-interlock load transfer at the transverse cracks is degraded. The prevalence of wide cracks in CRCP has frequently been associated with ruptured steel and significant levels of corrosion. Because of that, there has been recent interest in identifying new reinforcing materials that can prevent or minimize corrosion-related issues in CRCP. Glass fibre-reinforced polymer (GFRP) bars are one product being investigated for use in CRCP in place of traditional steel bars. This paper summarizes the construction details, material properties, early-age behaviour, and preliminary monitoring results of GFRP CRCP after 12 months in service. The project is located westbound HW-40 in Montreal, Qc, Canada, and presents a collaboration between the Ministry of Transportation of Quebec (MTQ) and the University of Sherbrooke. Varieties of sensors were installed in this project in order to monitor the early-age behaviour and the effects of repeated traffic loads and environmental conditions on the performance of CRCP slabs
Effect of resonances on the transport properties of two-dimensional disordered systems
We study both analytically and numerically how the electronic structure and
the transport properties of a two-dimensional disordered system are modified in
the presence of resonances. The energy dependence of the density of states and
the localization length at different resonance energies and strengths of
coupling between resonances and random states are determined. The results show,
that at energy equals to the resonance energy there is an enhancement in the
density of states. In contrast, the localization length remains unaffected from
the presence of the resonances and is similar to the one of the standard
Anderson model. Finally, we calculate the diffusion constant as a function of
energy and we reveal interesting analogies with experimental results on light
scattering in the presence of Mie resonances.Comment: 4 pages, 4 figures, accepted in Phys. Rev. B (2000
Inflammatory response in induced sputum mononuclear cells from patients with acute exacerbation of asthma.
Examination of sputum provides a direct method to investigate airway inflammation non-invasively in particular Th1 (IL-2, IFN-gamma) and Th2 (IL-4, IL-10) cytokine production. IL-2, IL-4, IL-10 and IFN-gamma cytokine were studied in induced sputum mononuclear cells of asthmatic patients. Sputum induction was performed on 10 patients and 10 normal controls. Basal and mitogen-stimulated cytokine production was determined in induced sputum T-cell culture. Supernatants were collected and assayed not only with specific ELISA but also with polymerase chain reaction (PCR) techniques. Data showed a significantly higher production of IL-10 by both the ELISA and the RT-PCR techniques in asthmatic patients compared with sputum mononuclear cells from healthy controls. IL-4 production was detected at a low level using the ELISA method in asthmatic patients. The RT-PCR analysis detected a significantly IL-4-mRNA expression in all asthmatic patients, compared with controls. Results of IL-10 and IL-4 mRNA expression were reproducible. We did not find any alteration in the expression of the type 1 derived cytokines (IL-2 and IFN-gamma) in asthmatic patients or in healthy controls. Our study showed a tendency of induced sputum mononuclear cells to express a Th2-like cytokine pattern in acute exacerbation of asthmatic patients, where IL-10 and IL-4 are synthesized in larger amounts. The combination of sputum induction as a non-invasive tool to explore the lung and the identification of disease-associated cytokine expression and of specific cytokine mRNA should help elucidate mechanisms of the immunologically mediated inflammatory responses in asthma
Effect of the measurement on the decay rate of a quantum system
We investigated the electron tunneling out of a quantum dot in the presence
of a continuous monitoring by a detector. It is shown that the Schr\"odinger
equation for the whole system can be reduced to new Bloch-type rate equations
describing the time-development of the detector and the measured system at
once. Using these equations we find that the continuous measurement of the
unstable system does not affect its exponential decay, ,
contrary to expectations based on the Quantum Zeno effect . However, the width
of the energy distribution of the tunneling electron is no more , but
increases due to the decoherence, generated by the detector.Comment: Additional explanations are added. Accepted for publications in Phys.
Rev. Let
All-optical trion generation in single walled carbon nanotubes
We present evidence of all optical trion generation and emission in undoped
single walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on
individual SWCNTs over a large CW excitation intensity range, show trion
emission peaks red-shifted with respect to the bright exciton peak. Clear
chirality dependence is observed for 22 separate SWCNT species, allowing for
determination of electron-hole exchange interaction and trion binding energy
contributions. Luminescence data together with ultrafast pump probe experiments
on chirality sorted bulk samples suggest that exciton-exciton annihilation
processes generate dissociated carriers that allow for trion creation upon a
subsequent photon absorption event.Comment: 13 pages, 4 figure
Influence of measurement on the life-time and the line-width of unstable systems
We investigate the quantum Zeno effect in the case of electron tunneling out
of a quantum dot in the presence of continuous monitoring by a detector. It is
shown that the Schr\"odinger equation for the whole system can be reduced to
Bloch-type rate equations describing the combined time-development of the
detector and the measured system. Using these equations we find that continuous
measurement of the unstable system does not affect its exponential decay to a
reservoir with a constant density of states. The width of the energy
distribution of the tunneling electron, however, is not equal to the inverse
life-time -- it increases due to the decoherence generated by the detector. We
extend the analysis to the case of a reservoir described by an energy dependent
density of states, and we show that continuous measurement of such quantum
systems affects both the exponential decay rate and the energy distribution.
The decay does not always slow down, but might be accelerated. The energy
distribution of the tunneling electron may reveal the lines invisible before
the measurement.Comment: 13 pages, 8 figures, comments and references added; to appear in
Phys. Rev.
Comparison of the shear behaviour of geopolymer concrete beams with GFRP and steel transverse reinforcements
This study presents a comparison of the shear behaviour of geopolymer concrete beams transversely reinforced with glass fiber-reinforced polymer (GFRP) and steel bars. Two full-scale beams with GFRP and steel stirrups spaced at 150 mm on-center were fabricated and tested up to failure using the four-point static bending test. Another beam without web reinforcements was also cast to determine the shear contribution of the geopolymer concrete. All the beams were provided with the same amount of flexural reinforcements. The beams were supported over a 1200 mm clear span with 450 mm shear span on each side. The shear span-to-depth ratio of the beams was 1.8. Based on the test results, the provision of GFRP stirrups almost doubled the shear capacity of the beam without web reinforcements. Comparable load-deflection response, shear strength, deflection capacity, and strain readings were observed between the beams with GFRP and steel stirrups. The two beams yielded similar crack pattern; however, wider cracks were developed in the former beam owing to the lower elastic modulus of GFRP bar compared with steel bar. Furthermore, both beams failed in shear, classified as a diagonal strut compression failure; however, the failure of the beam with GFRP stirrups was induced by the stirrup’s lap splice failure while steel yielding caused the failure of beam with steel stirrups. This had led to a more brittle final failure of the former beam compared with the latter beam
Developing a Wellbeing Framework for Aboriginal and Torres Strait Islander Peoples Living with Chronic Disease (Wellbeing Study)
Addressing a need identified by Aboriginal and Torres Strait Islander peoples and their primary
healthcare providers, this study developed a Wellbeing Framework for managing chronic disease in
a manner that also supports wellbeing.
Chronic care models that are currently in use usually focus upon the systems, resources and
policies that are required to deliver care. The important roles of culture, spirituality, Country and
family in maintaining health and wellbeing are notably absent from such models.
Re-defining the way in which care is delivered to reflect Aboriginal and Torres Strait Islander
peoples’ needs and values is essential for improving the accessibility and acceptability of primary
healthcare services.The research reported in this paper is a project of the Australian Primary Health Care Research Institute which is supported by a grant from the Australian Government Department of Health and Ageing under the Primary Health Care Research Evaluation and Development Strategy
Homogenized dynamics of stochastic partial differential equations with dynamical boundary conditions
A microscopic heterogeneous system under random influence is considered. The
randomness enters the system at physical boundary of small scale obstacles as
well as at the interior of the physical medium. This system is modeled by a
stochastic partial differential equation defined on a domain perforated with
small holes (obstacles or heterogeneities), together with random dynamical
boundary conditions on the boundaries of these small holes.
A homogenized macroscopic model for this microscopic heterogeneous stochastic
system is derived. This homogenized effective model is a new stochastic partial
differential equation defined on a unified domain without small holes, with
static boundary condition only. In fact, the random dynamical boundary
conditions are homogenized out, but the impact of random forces on the small
holes' boundaries is quantified as an extra stochastic term in the homogenized
stochastic partial differential equation. Moreover, the validity of the
homogenized model is justified by showing that the solutions of the microscopic
model converge to those of the effective macroscopic model in probability
distribution, as the size of small holes diminishes to zero.Comment: Communications in Mathematical Physics, to appear, 200
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