Université de Sherbrooke

About: Université de Sherbrooke is a education organization based out in Sherbrooke, Quebec, Canada. It is known for research contribution in the topics: Population & Receptor. The organization has 14922 authors who have published 28783 publications receiving 792511 citations. The organization is also known as: Universite de Sherbrooke & Sherbrooke University.

High aerosol optical depth biomass burning events: A comparison of optical properties for different source regions

Abstract: Received 29 May 2003; revised 8 September 2003; accepted 17 September 2003; published 21 October 2003. [1] The optical properties of aerosols such as smoke from biomass burning vary due to aging processes and these particles reach larger sizes at high concentrations. We compare the spectra of aerosol optical depth (ta), columnintegrated volume size distributions, refractive indices, and single scattering albedo retrieved from AERONET observations for four selected events of very high smoke optical depth (ta � 2 at 500 nm). Two case studies are from tropical biomass burning regions (Brazil and Zambia) and two are cases of boreal forest and peat fire smoke transported long distances to sites in the US and Moldova. Smoke properties for these extreme events can be significantly different from those reported in more typical plumes. In particular, large differences in smoke fine mode particle radius (� 0.17 to 0.25 mm) and single scattering albedo (� 0.88 to 0.99 at 440 nm) were observed as a result of differences in fuels burned, combustion phase, and aging. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation. Citation: Eck, T. F., B. N. Holben, J. S. Reid, N. T. O’Neill, J. S. Schafer, O. Dubovik, A. Smirnov, M. A. Yamasoe, and P. Artaxo, High aerosol optical depth biomass burning events: A comparison of optical properties for different source regions, Geophys. Res. Lett., 30(20), 2035, doi:10.1029/ 2003GL017861, 2003.

Linear temperature dependence of resistivity and change in the Fermi surface at the pseudogap critical point of|[nbsp]|a|[nbsp]|high-Tc superconductor

Abstract: Transport measurements in a high-temperature superconductor provide evidence that the so-called pseudogap phase ends at a quantum critical point located inside the superconducting dome in the phase diagram of cuprates.

Small Fermi surface pockets in underdoped high temperature superconductors: observation of Shubnikov-de Haas oscillations in YBa2Cu4O8.

Abstract: We report the observation of Shubnikov--de Haas oscillations in the underdoped cuprate superconductor ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{4}{\mathrm{O}}_{8}$ (Y124). For fields aligned along the $c$ axis, the frequency of the oscillations is $660\ifmmode\pm\else\textpm\fi{}30\text{ }\text{ }\mathrm{T}$, which corresponds to $\ensuremath{\sim}2.4%$ of the total area of the first Brillouin zone. The effective mass of the quasiparticles on this orbit is measured to be $2.7\ifmmode\pm\else\textpm\fi{}0.3$ times the free electron mass. Both the frequency and mass are comparable to those recently observed for ortho-II ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.5}$ (Y123-II). We show that although small Fermi surface pockets may be expected from band-structure calculations in Y123-II, no such pockets are predicted for Y124. Our results therefore imply that these small pockets are a generic feature of the copper oxide plane in underdoped cuprates.

Construct Validity of the Multidimensional Structure of Bullying and Victimization: An Application of Exploratory Structural Equation Modeling.

Abstract: Existing research posits multiple dimensions of bullying and victimization but has not identified well-differentiated facets of these constructs that meet standards of good measurement: goodness of fit, measurement invariance, lack of differential item functioning, and well-differentiated factors that are not so highly correlated as to detract from their discriminant validity and substantive usefulness in school settings. Here we demonstrate exploratory structural equation modeling, an integration of confirmatory factor analysis and exploratory factor analysis. On the basis of responses to the 6-factor Adolescent Peer Relations Instrument (verbal, social, physical facets of bullying and victimization), we tested invariance of factor loadings, factor variances--covariances, item uniquenesses, item intercepts (a lack of differential item functioning), and latent means across gender, year in school, and time. Using a combination of relations with student characteristics and a multitrait--multimethod analysis, we showed that the 6 bully/victim factors have discriminant validity over time and in relation to gender, year in school, and relevant psychosocial correlates (e.g., depression, 11 components of academic and nonacademic self-concept, locus of control, attitudes toward bullies and victims). However, bullies and victims are similar in many ways, and longitudinal panel models of the positive correlations between bully and victim factors suggest reciprocal effects such that each is a cause and an effect of the other