The Université du Québec à Chicoutimi is a branch of the Université du Québec founded in 1969 and based in the Chicoutimi borough of Saguenay, Quebec. UQAC has secondary study centers in La Malbaie, Saint-Félicien, Alma and Sept-Îles. In 2003, 6583 students were registered and 209 professors worked for the university, making it the third largest of the ten Université du Québec branches, after UQAM and UQTR. Wikipedia.
Sawyer E.W.,University of Quebec at Chicoutimi
Journal of Metamorphic Geology | Year: 2014
The beginning stages of melt segregation and the formation of leucosomes are rarely preserved in migmatites. Most arrays of leucosomes record a more advanced stage where flow dominates over segregation. However, the early stages in the formation of leucosomes and the segregation of melt are preserved in a partially melted meta-argillite from the metatexite zone (>800 °C) of the contact aureole around the Duluth Complex, Minnesota. The rock contains 2.4 modal% leucosome in a matrix consisting of 40.5% in situ neosome and 57.1% cordierite + plagioclase framework. The domainal microstructure in the matrix is a pre-anatectic feature resulting from the bulk composition. Terminal chlorite reactions produced a large volume of cordierite which, with plagioclase, formed a framework that enclosed patches of biotite + quartz + plagioclase ± K-feldspar. Upon melting, these fertile domains became patches of in situ neosome. Plagioclase in the neosome is less sodic than in the leucosome, hence segregation of melt occurred during crystallization, not melting. Segregation was delayed because the cordierite + plagioclase framework was strong enough to resist dilatation and compaction until after crystallization started. The leucosomes are small (i.e. they are microleucosomes) and display a systematic progression in morphology as length and aspect ratio increase from ~1 to 19 mm and from ~2.5 to >30 respectively. Small equant micropores form first, and in places these coalesce into small (~1 mm, aspect ratio ~2.5), isolated, blunt-ended, elliptical microleucosomes. In the next stage, micropores develop ahead of, and at ~45° to the left and right of the blunt tip of a microleucosome; one of these develops into an elliptical leucosome and an en echelon array of either a left- or right-stepping elliptical microleucosome forms. Each elliptical microleucosome in the en echelon arrays is separated by a bridge of matrix. Next, microleucosomes of greater length (>4 mm) and aspect ratio (>5) form when the bridges of cordierite + plagioclase matrix rupture and the elliptical microleucosomes link together to form a zigzag-shaped microleucosome. Finally, still longer microleucosomes with greater aspect ratios (~30) are formed by the joining of zigzag arrays. Such a progression is characteristic of the way ductile fractures grow. The segregation of melt was driven by the pressure gradient between the dilatant fracture and an adjacent in situ neosome, which drew melt to the growing fracture, thereby creating a microleucosome. The microleucosomes are filled arrays of ductile fractures. Melt was contiguous only between microleucosomes and adjacent patches of in situ neosome. The length-scale of segregation was ~5 mm, the size of a typical patch of in situ neosome, and restricted by the surrounding impermeable cordierite + plagioclase framework. The melt in the microleucosome was the most fractionated and the last to crystallize. All microleucosomes contain entrained minerals as a consequence of their mechanism of growth. Rupture of the bridges resulted in the entrainment of pre-anatectic phases. However, microleucosomes that cross patches of in situ neosome are also contaminated with peritectic phases that were transported with the melt. © 2014 John Wiley & Sons Ltd.
Sawyer E.W.,University of Quebec at Chicoutimi
Lithos | Year: 2010
The Opatica Subprovince in the Canadian Shield is a late Archaean (2761-2702 Ma) plutonic arc formed above a north-dipping subduction zone. Anatexis (2690-2677 Ma) of leucogranodiorite and leucotonalite orthogneisses in the Opatica generated migmatites in an area of north-vergent back thrusts visible at the surface and in L. ithoprobe seismic profile 48. Schollen diatexite migmatites occur in the thrusts and metatexite migmatites between them.The modal mineralogy, microstructure, and whole rock major, trace and oxygen isotope compositions of the protolith and migmatites were investigated to; 1) determine the melting reaction, 2) find microstructural criteria for identifying residual rocks in leucocratic systems where there is no melanosome, and 3) to determine the source of the fluid involved in anatexis.Partial melting of the protolith did not change the mineral assemblage, but the abundance of quartz and microcline both declined and plagioclase and biotite increased in the residual rocks. Quartz, plagioclase and microcline show evidence for dissolution and biotite does not. Thus, water-fluxed melting of quartz. +. plagioclase. +. microcline occurred. A mass balance indicates 25-30% partial melting. The melting reaction consumed the microcline and created essentially monomineralic domains of plagioclase. Extraction of 80-90% of the melt left a thin film of melt on the grain boundaries, and crystallization of these in the plagioclase domains created diagnostic microstructures. Microcline fills the last remaining pore space and forms high-aspect ratio crystals between plagioclases or triangular crystals at grain junctions. Quartz shows a range of morphologies, from high-aspect ratio films through the "string of beads" to isolated rounded grains, as the microstructure progressively equilibrated after crystallisation.Most accessory phases, including zircon, remained in the residuum. However, almost all the schollen migmatites have high contents of Th, U, Nb, Ta and REE relative to the protolith, due to contamination by accessory phases derived from mafic rocks. Disaggregation of the mafic rocks may have been facilitated by the high strain in the back thrusts where the schollen diatexites formed.Average whole rock δ18O for the protolith and migmatites are similar (ca 8.2%), and the small difference between melt-rich (8.6%) and residuum-rich rocks (8.0%) is consistent with fractionation. Thus, the fluid that caused melting was probably of metamorphic origin with δ18O similar to the protolith. The seismic profile shows several reflectors extending to a present depth of 20 km (ca. 40 km in the late Archaean) under the migmatites; these are the paths along which the metamorphic fluid migrated and generated the migmatites now at the surface. A new type of neosome reported in this study may have formed along fractures that the fluids migrated along, however, these are peripheral pathways in the metatexites adjacent to the back thrusts and schollen diatexites. © 2009 Elsevier B.V.
Gaboury D.,University of Quebec at Chicoutimi
Geology | Year: 2013
The origin of volatiles in fluid inclusions was reviewed for testing the involvement at depth of carbonaceous-pyritic sedimentary rocks as the source for orogenic gold mineralization. Fluid inclusions from selected deposits were analyzed by solid-probe mass spectrometry. Fluids are mostly aqueous-carbonic, with variable amounts of N2, CH4, C2H6, Ar, H2S, H2 and He. For fluids with CH4 and C2H6, their ratios (C1/C2) range from 2.6 to 25.5, indicating that C2H6 is sourced from thermally degraded organic matter. Proportions of CO2, CH4, C2H6 and H2 are highly variable and can be explained by hydrothermal reactions where C2H6 is degraded to CO2 by water consumption. Such reactions may account for the problematic CO2-rich, H2O-poor fluids associated with some of the richest gold districts. Conditions needed for C2H6 degradation are also fundamental for forming gold deposits, such as HS--enriched fluids for carrying gold and local weakly oxidizing conditions for promoting gold precipitation. The C2H6 content is recorded in fluids from Mesoarchean to Cretaceous gold deposits, providing support for a general model where fluids and gold were sourced from deeply buried, carbonrich, and pyrite-gold-bearing sedimentary rocks. © 2013 Geological Society of America.
Legault J.,University of Quebec at Chicoutimi
Journal of medicinal food | Year: 2010
Antioxidant activity, inhibition of nitric oxide (NO) overproduction, and antiproliferative effect of ethyl acetate extracts of maple sap and syrup from 30 producers were evaluated in regard to the period of harvest in three different regions of Québec, Canada. Oxygen radical absorbance capacity (ORAC) values of maple sap and syrup extracts are, respectively, 12 +/- 6 and 15 +/- 5 micromol of Trolox equivalents (TE)/mg. The antioxidant activity was also confirmed by a cell-based assay. The period of harvest has no statistically significant incidence on the antioxidant activity of both extracts. The antioxidant activity of pure maple syrup was also determined using the ORAC assay. Results indicate that the ORAC value of pure maple syrup (8 +/- 2 micromol of TE/mL) is lower than the ORAC value of blueberry juice (24 +/- 1 micromol of TE/mL) but comparable to the ORAC values of strawberry (10.7 +/- 0.4 micromol of TE/mL) and orange (10.8 +/- 0.5 micromol of TE/mL) juices. Maple sap and syrup extracts showed to significantly inhibit lipopolysaccharide-induced NO overproduction in RAW264.7 murine macrophages. Maple syrup extract was significantly more active than maple sap extract, suggesting that the transformation of maple sap into syrup increases NO inhibition activity. The highest NO inhibition induced by the maple syrup extracts was observed at the end of the season. Moreover, darker maple syrup was found to be more active than clear maple syrup, suggesting that some colored oxidized compounds could be responsible in part for the activity. Finally, maple syrup extracts (50% inhibitory concentration = 42 +/- 6 microg/mL) and pure maple syrup possess a selective in vitro antiproliferative activity against cancer cells.
Dauvilliers Y.A.,French Institute of Health and Medical Research |
Laberge L.,University of Quebec at Chicoutimi
Sleep Medicine Reviews | Year: 2012
Myotonic dystrophy type 1 (DM1), or Steinert's disease, is the most common adult-onset form of muscular dystrophy. DM1 also constitutes the neuromuscular condition with the most significant sleep disorders including excessive daytime sleepiness (EDS), central and obstructive sleep apneas, restless legs syndrome (RLS), periodic leg movements in wake (PLMW) and periodic leg movements in sleep (PLMS) as well as nocturnal and diurnal rapid eye movement (REM) sleep dysregulation. EDS is the most frequent non-muscular complaint in DM1, being present in about 70-80% of patients. Different phenotypes of sleep-related problems may mimic several sleep disorders, including idiopathic hypersomnia, narcolepsy without cataplexy, sleep apnea syndrome, and periodic leg movement disorder. Subjective and objective daytime sleepiness may be associated with the degree of muscular impairment. However, available evidence suggests that DM1-related EDS is primarily caused by a central dysfunction of sleep regulation rather than by sleep fragmentation, sleep-related respiratory events or periodic leg movements. EDS also tends to persist despite successful treatment of sleep-disordered breathing in DM1 patients. As EDS clearly impacts on physical and social functioning of DM1 patients, studies are needed to identify the best appropriate tools to identify hypersomnia, and clarify the indications for polysomnography (PSG) and multiple sleep latency test (MSLT) in DM1. In addition, further structured trials of assisted nocturnal ventilation and randomized trials of central nervous system (CNS) stimulant drugs in large samples of DM1 patients are required to optimally treat patients affected by this progressive, incurable condition. © 2012 Elsevier Ltd.