Documents found
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3011.More information
Metallothionein (MT), an intracellular metal binding protein, is recognized for its role in the regulation of essential and non-essential trace metals. The mechanisms of synthesis of this protein have been studied in the laboratory but much less work has been carried out in the field, particularly in lotic environments. According to the literature, metallothionein protects tissues from metal damage, and may be used as a direct measure of the biochemical state of the affected tissue. Metallothionein shows high affinity for group IB and IIB metals ions (e.g. Cd, Cu, Zn), and consequently can sequester and detoxify metals. The use of MT as a biomarker for elevated levels of trace metals in aquatic environments has therefore been proposed as a tool in ecotoxicological studies. Changes at the biochemical level offer distinct advantages as biomarkers, since molecular alterations are normally the first detectable responses to environmental changes.The present study focused on two objectives, the first of which was to identify which trace metals (silver "Ag", cadmium "Cd", copper "Cu", nickel "Ni", lead "Pb" and zinc "Zn") may induce MT synthesis in three sentinel species collected in two northern Quebec rivers (Colombière River, close to Val d'Or, and Matagami River close to the town of Matagami) in a mining region (Abitibi, Québec). The three sentinel species were the adult bivalve Pyganodon grandis, the larval mayfly Hexagenia limbata, and the adult great northern pike Esox lucius. The second objective was to define variables that could influence the uptake of these trace metals and consequently the concentrations of MT in the sentinel species. The selection of these sentinel species was based on the following criteria: their relative abundance in the aquatic systems studied; their relative immobility; the ease of sampling; metal tolerance; metal bioaccumulation capacity; dynamics of metal accumulation; capacity to synthesize metallothionein; and availability of physiological and behavioural data.In 2001, physico-chemical conditions (e.g.: temperature, oxygen, transparency, phosphorus, chlorophyll a, etc.) were monitored during two sampling campaigns at 21 stations. Trace metals were measured in water and sediment in all stations, and in tissues of the sentinel species that were collected when present at the station (P. grandis - gills; H. limbata - whole body; E. lucius - kidney). Dialysis cells were used to collect water samples for the determination of concentrations of total dissolved metals, major anions and cations, humic and fulvic acids, and dissolved organic carbon. At each sampling site, divers collected three replicate sub-samples from two sediment cores for metal analyses. The cores were extruded in the boat and samples taken from the uppermost 0.5 cm, i.e. from the oxidized layer.The two rivers differ in their morphometry, their physico-chemistry, and their biology. The Allard River is larger (200 m vs. 7 m) and deeper (30 m vs. 3 m) than the Colombière River. The Colombière River is slightly more acid (pH: 6.2 - 6.7) and less productive (14 - 32 µg total P L-1) than the Allard River (pH: 6.7 - 7.4; 24 - 45 µg total P L-1). However, the rivers present some similarities such as slow current conditions and limited water transparencies. The range of Ag, Cu and Ni concentrations in water and sediment was greater in the Colombière River, whereas Pb concentrations were higher in the Allard River and Cd concentrations were similar in the two rivers. Zinc was the dominant metal in both rivers, but variations were more significant in water in the Colombière River. Although trace metal and MT concentrations were highly variable among species, stations and rivers, no consistent spatial gradients were detected in animals collected downstream from mining activities.As was the case for the ambient environment, Zn was also the dominant metal in organisms of both rivers. Zinc concentrations were similar in mayflies from the two rivers, but higher in molluscs and lower in pike collected from the Colombière River than in comparable animals from the Allard River. Following Zn, Cu was the second metal in importance in species from the two rivers, whereas the concentrations of Ag were low in all organisms and were undetectable in pike. Cadmium was more concentrated in mayflies and molluscs from the Colombière River than in those from Allard River, and also higher in the pike collected in the contaminated zone of the Colombière River. The concentrations of Ni in all species were comparable between rivers, but were more elevated in mayflies than in the other sentinel species.The range of Pb concentrations was comparable between rivers for all species, but concentrations were lower in the pike (kidney). The concentration of MT was higher in the pike than in the two other species. Mayflies had higher MT levels in the Allard River, while MT concentrations were higher in molluscs of the Colombière River. The relationships between metals and MT were very variable between rivers and species. Nevertheless, MT concentrations were most strongly related to those of accumulated Cd in the three sentinel species. The relationships between MT and Cd for all three species were stronger in the Allard River than in the Colombière River. In the case of P. grandis, because the number of stations where the bivalves could be collected from the Colombière River was low (n=4), no statistically significant relationship was observed between MT and Cd in the tissues, in spite of the high correlation coefficient (r=0.98). For the bivalves, manganese (Mn) concentrations in the sediment were negatively correlated with accumulated Cd concentrations and with MT levels. In H. limbata, in addition to Cd, other metals such as Cu (-) and Zn (+) also exhibited weak relationships with MT. Finally, in bivariate analyses, Pb concentrations in pike liver were significantly correlated with those of MT in this species, but based on multiple regression models, no variable other than Cd affected the level of MT in E. lucius.
Keywords: Métaux traces, cadmium, métallothionéine, éphémère, mollusque, bivalve, brochet, Trace metals, cadmium, metallothionein, mayfly, bivalve mollusc, pike
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3012.More information
Very few studies have ever focused on the thermal balance of a wastewater treatment process, despite its major impact on various aspects of sanitary engineering, such as biological growth, oxygen transfer and, most importantly, purification kinetics. This lack of knowledge is particularly worrying for the design of aerated lagoons and waste stabilization ponds, since these two extensive treatment technologies are extremely dependent on climatic conditions and subject to high thermal variations. In temperate regions, a pond annual temperature range can even exceed 20 °C, while a 10 °C variation will induce a more than 60% drop or increase in its removal yield. Our paper intends to present a comprehensive temperature prediction model which accounts for the main heat loss and gain terms exchanged through the pond surface and walls.Our approach includes six different energy inputs and outputs, namely: solar radiation, air-water surface convection, atmospheric radiation, back surface radiation, evaporation and ground-water-walls convection. Each of these components was described extensively by means of a literature review of all previous efforts made to predict equilibrium temperature in lakes, rivers, salt-gradient solar ponds, cooling tanks, even outdoor pools. The best aspects of each prediction model were then incorporated into a new computer model developed as two different but complementary variants: one for steady-state conditions and the other for continuous and therefore also transient simulations. The main difference between these two approaches is that the first one neglects enthalpy variation while the second one takes the form of a differential equation, with basin temperatures being estimated by an iterative calculation procedure and a numerical integration method, respectively.Two hypotheses were necessary to develop this model. The first one posits that pond hydrodynamics correspond to completely mixed conditions. Such hydraulic behavior is extremely frequent in aerated lagoons and waste stabilization ponds in temperate climates, but less so in tropical or Mediterranean regions, where thermal balances appear much more complex since stabilization ponds are often thermally stratified. The second hypothesis is that all radiation fluxes received by the ponds are completely absorbed by the pond's contents and are never reflected, even partially, by their bottoms or walls.This model, which is in fact the thermal balance of the basins, relies mainly on meteorological factors and pond characteristics. Only two out of the six estimated fluxes - evaporation rates and solar radiation - are measured directly in situ. It seemed too difficult to estimate them, since predictive equations found in literature constantly gave unsatisfactory results.To establish the validity of this model, experimental data were collected at a wastewater treatment plant located in the southern part of Belgium. This plant consists of a series of two aerated lagoons and four waste stabilization ponds, designed for a nominal capacity of 7,500 inhabitant-equivalents. Five rounds of measurements, each lasting from five to twenty days, were conducted at different periods of the year. Meteorological factors were continuously monitored by a data acquisition unit while the pond water temperatures and hydraulic flows were measured hourly. Evaporation rates were determined daily with several floating evaporation pans set at the pond surfaces. Vertical temperature and illumination profiles were also measured in order to verify the strict applicability of the two previous hypotheses.Ninety-three experimental data sets were collected on this particular facility. Predicted temperatures were compared with measured temperatures as well as with the results of three other models previously developed for waste stabilization ponds. Our new model systematically proved more reliable and accurate than previous approaches, since equilibrium temperatures were predicted with a mean absolute error of only 0.7 °C. More than 52% of the deviations between calculated and observed temperatures were even below 0.5 °C, which indicates their relatively low dispersion.Continuous simulations were also conducted during a one-day period to demonstrate the importance of the ponds' large thermal capacities. The steady-state approach, which does not account for this latter phenomenon, failed to give consistent results, unlike our dynamic heat balance approach, which yielded extremely good fits with experimental data.A sensitivity analysis allowed us to show the influence of the various meteorological factors on the basins' equilibrium temperatures. In decreasing order, the fits seemed particularly sensitive to inlet temperature, solar radiation, air temperature and evaporation. Surprisingly, wind speed made only a small contribution to the total heat balance. However, this must be seen as a direct consequence of the fact that in our model this latter parameter is no longer used to calculate the predominant evaporation rates but only to estimate the much smaller convection term.Whatever the season considered, more than 90% of the ponds' energy inputs come from solar radiation while the dominating loss mechanisms are represented by the balance of the two infrared radiation fluxes (46%) and evaporation (42%). The sign of the air-water convection term varies according to the period of the year but never accounts for more than 10% of the total heat balance. Heat losses or gains from basin walls always remain insignificant and could therefore easily be neglected in order to simplify our approach to basin equilibrium temperatures.
Keywords: Lagunage aéré, lagunage naturel, bilan thermique, température d'équilibre, transfert de chaleur, Aerated lagoon, waste stabilization pond, thermal balance, equilibrium temperature, heat transfer
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3013.More information
This article contributes to reflections on students' relationship to writing (RW) in the second-language context of Allophone immigrants, for which it proposes the designation RW+. The text is based on a Quebec study regarding the effects of producing plurilingual identity texts on the RW+ of eight Allophone immigrant students with severe educational delays in a secondary-school reception class (experimental group: n=4; control group: n=4). Individual interviews and participant observation are used to describe the participants' RW+ and to determine the effects of the new approach, which, in contrast with the traditional educational practices observed in the control group, is associated with the development of a more positively connoted RW+. This results, among other things, in the students' greater engagement.
Keywords: français langue seconde, élèves immigrants allophones, rapport à l'écrit, littératie, textes identitaires plurilingues, french as a second language, allophone immigrant students, relationship to writing, literacy, plurilingual identity texts, francés como segunda lengua, estudiantes inmigrantes alófonos, relación con la escritura, alfabetización, textos de identidad plurilingües
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3014.More information
In Quebec, school reforms instituted between 1986 and 2004 at the various levels of education are mainly aimed at developing competencies. Knowledge of instructional practices and, in fact, the practices of assessment of learning, could lead to a better understanding of the results of the reality in the classroom. Proposed by Raîche (2006), the PIEA framework sets out the following characteristics of classroom learning assessment practices: planning, integration, equity and authenticity. A sample of 1975 students enrolled in Quebec's technical and pre-university college programs responded to a questionnaire consisting of 24 items. The analyzes carried out to determine the number of dimensions to be retained and to explore the various factor solutions identified a four-factor model associated with the characteristics proposed by the PIEA model, but not exactly the same.
Keywords: évaluation des apprentissages, approche par compétences, analyse factorielle exploratoire, validation d'échelle, assessment of learning, competency-based approach, exploratory factor analysis, scale validation, evaluación de aprendizajes, enfoque por competencias, análisis factorial exploratorio, validación de escala
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3015.More information
SummaryThe article presents the results of a research on the trajectories of immigrant students' academic success in Montreal and Sherbrooke. The majority of these students attended a welcoming class. Using interviews as the chosen research method, case studies were conducted to analyze the point of view of the student, parent, and teacher on a student's school experiences. Thus, twenty-four cases emphasized various levels of mobilization contributing to each trajectory of academic success. Furthermore, a typology of success situations according to family profiles was modeled in three categories : success-continuity, success-promotion, family success. Transversal aspects of the typology are presented.
Keywords: immigration, réussite solaire, mobilisation, famille, trajectoire, immigration, academic success, mobilization, family, trajectory, inmigración, éxito escolar, movilización, familia, trayectoria
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3016.More information
The COVID‑19 pandemic has been particularly deadly for older people living in long-term care homes (LTC) and assisted living facilities (ALF) in Quebec. Consequently, many managers and front-line staff witnessed numerous resident deaths. Yet their experiences with end-of-life care and grief remain relatively unexplored. This qualitative study captures the experiences of three managers and four front-line staff working in LTCs or ALFs during the pandemic. Its findings illuminate the emotional challenges brought on by the pandemic due to changed end-of-life and bereavement practices. For some, the metaphor of war closely resembled their experiences. While feelings of helplessness and confusion were expressed, so too were experiences of cooperation and teamwork. Suggestions for practices to support staff and residents at the end of life and following death are explored.
Keywords: CHSLD, COVID‑19, deuil, fin de vie, personnel de la santé, résidences pour personnes âgées (RPA), assisted living facilities, COVID‑19, end-of-life, healthcare workers, grieving, long-term care, CHSLD, COVID-19, duelo, final de la vida, personal sanitario, residencias de ancianos (RPA)
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3017.More information
AbstractThe Montreal's Youth Centre intensive probation program for youth offenders was designed as an alternative for youth offender who would have normally been referred to a measure of open custody. In consideration of the scientific literature on the effectiveness of intensive supervision program, youth admitted to this program were high risk offenders (n = 99) who manifested receptivity for such an intervention in the community. The present study addresses the efficacy of the program in term of official recidivism. The results confirm the validity of the evaluation procedures for juvenile delinquents and their referral to the different programs (intensive probation, open custody, regular probation). Coherent with the intensity of the intensive probation program, subjects followed in this modality of treatment were more often the subject of reports identifying failure to comply with dispositions (e.g. breach of probation) of their sentences. At the one-year post-treatment follow-up, the non-recidivism rate of youth placed in intensive probation (76.2%) confirms that this measure can be seen as a valid alternative to open custody (47.4%). A logistic regression equation confirms that the two groups differed in their non-recidivism rate even when the initial characteristics of the youth were controlled for.
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3018.More information
The relationship between the entrepreneur and the investor is often viewed from a conflictual angle based on information asymmetry and on potential stakeholder opportunism. However, venture capital financing includes mixed relationships between venture capitalists and entrepreneurs. In this relationship, venture capitalists seek to orient the funded projects towards prospects of success while securing their investment funds through the negotiation of a set of legal agreements. On the other hand, the entrepreneurs strive to have some leeway to manoeuver while maintaining a certain degree of confidentiality. Our research question concerns the various governance mechanisms that surround the venture capitalist-entrepreneur relationship. Our theoretical framework is based on a double theoretical reading grid, by analyzing this relationship according to the two legal-financial and cognitive approaches of governance. Our results show that venture capitalists not only have a financial impact, but also organizational and cognitive impacts that can govern the internal organization of the venture capital-backed firm. The mode of governance employed can be influenced largely by the individual, organizational, institutional and economic characteristics of the venture capitalists. On the other hand, the managers of venture capital-backed firms may behave in ways that go beyond traditional opportunism, in which they conceal their personal interests, to generate cognitive resources and contribute to value creation.
Keywords: Governance, Gouvernance, venture-capital, capital-risque, cognitive approach, approche cognitive, legal-financial approach, approche juridico-financière, entrepreneurial finance, finance entrepreneuriale
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3019.More information
Keywords: développement professionnel, éducation physique et à la santé, pratiques inclusives, attitudes, croyances, contrôlabilité
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3020.More information
The Quebec region of Abitibi-Témiscamingue is greatly affected by the labour shortage. In a context where the mining industry offers highly competitive wages and benefits to its workers, the manufacturing industry, which covets a pool of workers similar to that of the mining industry, is struggling to keep its staff. In response to Rubenstein et al. (2018) and Hom et al. (2017) call to deepen and contextualize the phenomenon of staff retention, this research aims to explore, in the context of regional labour shortage, what are the configurations of the antecedents of the staff retention in factories of Abitibi-Témiscamingue using a cross-sectional configurational approach (Qualitative Comparative Analysis (QCA)). This research has identified different configurations explaining the intention to stay (or lack thereof) of manufacturing workers and illustrated that the intention to stay of these workers is mainly influenced by intra-organizational antecedents.
Keywords: Qualitative Comparative Analysis (QCA), Staff retention, Intention to stay, Rétention de personnel, Manufacturing sector, Intention de rester, Secteur manufacturier, Qualitative Comparative Analysis (QCA), Pénurie de main-d’oeuvre