1,090 research outputs found
Understanding China's Long-Run Growth Process and Its Implications for Canada
In the past 25 years, China has introduced numerous reforms, gradually moving from a centrally planned economy towards a socialist market economy capable of robust and sustainable economic growth. China's increasing integration into the global economy, which has been fuelled by this recent and rapid economic growth, has already begun to affect the economies of other countries and to present challenges for policy-makers, both in China and abroad. In addition to examining the determinants of China's past and current growth, the authors consider factors that are likely to support continued growth in the future and assess the implications for both the world and the Canadian economies.
NEBLINE, May 2015
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Investigation of the relation between substance use and cognitive performance and its mediating effect on psychopathology symptoms
Le projet de thèse porte sur la consommation de substances psychoactives chez les adolescents et le lien séquentiel entre la consommation de drogues, la performance cognitive, et la santé mentale des jeunes. Les objectifs de la thèse sont : 1) de tester la relation entre la prise de cannabis, ou d’alcool, et la performance cognitive, et d’en observer la séquence, 2) de vérifier si la relation entre la consommation et la performance cognitive permet, en partie, de comprendre l’apparition de symptômes de psychopathologie chez les jeunes, et 3) de définir les pratiques les mieux fondées empiriquement pour prévenir la consommation de substances chez les adolescents.
Le premier chapitre de la thèse évalue la relation et la séquence entre les habitudes de consommation d’environ 4000 jeunes de la région métropolitaine de Montréal (Qc, Canada) et la trajectoire de leur développement cognitif sur une période de quatre ans. Dans un deuxième chapitre, la thèse évalue comment la relation entre la consommation et la performance cognitive de ces mêmes jeunes peut expliquer, sur une période de cinq ans, une partie de la relation observée entre la consommation et l’apparition de symptômes de psychopathologie. Dans un dernier chapitre, la thèse fait la revue des données portant sur trois types d’interventions préventives afin d’identifier comment la recherche empirique peut bonifier les efforts de prévention de la toxicomanie chez les adolescents.
Les données ont été extraites d’une cohorte d’adolescents issus de la population générale, suivis longitudinalement, dans le cadre de l’étude Co-Venture (n = 3826, âgés de 12 ans à l’admission dans l’étude, suivis annuellement pendant 5 ans).
Les résultats ont démontré que, bien que certains facteurs semblent prédisposer un sous-groupe de jeunes à une consommation hâtive ainsi que des difficultés neuropsychologiques, la consommation de drogues, notamment de cannabis, semble liée, de façon à la fois ponctuelle et durable, à un délai du développement cognitif, plus particulièrement des fonctions exécutives. Cette association avec le cannabis semble, en faible partie, jouer un rôle médiateur dans la relation qui unit cette consommation et l’émergence de symptômes de psychopathologie chez les adolescents. Toutefois, des facteurs prédisposants semblent contribuer à l’association entre ces trois variables. Bien que la recherche identifie que plusieurs programmes de prévention peuvent être efficaces, la majorité d’entre eux présentent des effets modestes et ponctuels. Les programmes les plus probants semblent s’inscrire dans le registre des approches de prévention ciblées.
Pour bonifier nos méthodes de prévention de la toxicomanie chez les adolescents, nous pourrions tenir compte de certains facteurs prédisposants et les utiliser comme cible d’intervention; par exemple, le fonctionnement cognitif basal pourrait constituer une piste intéressante. De plus, le tempérament ou la personnalité semblent mieux établis pour prévenir la consommation de façon durable et pour aborder les enjeux cognitifs et psychologiques associés à la consommation abusive de substances.
Mots-clés : Alcool, cannabis, adolescence, fonctions cognitives, symptômes de psychopathologie, devis longitudinaux, médiation, préventionThis thesis project addresses adolescents’ substance misuse and the sequential link between drug use, cognitive performance, and mental health outcomes in youth. The objectives of this thesis are: 1) to test the relation and sequence between cannabis or alcohol use and cognitive outcomes, 2) to verify if the relation between substance use and cognitive outcomes could help understand, in part, why young substance users report psychopathology symptoms, and 3) to review evidence-based interventions to prevent adolescent substance misuse and to assess what contribution could stem from the collected empirical data.
The first chapter of this thesis assesses the relation and sequence between substance use behaviour of nearly 4000 youth from the Montreal metropolitan area (QC, Canada) and their cognitive development over four years. In a second chapter, this thesis analyzes how the association between substance use and cognitive outcomes could partially explain, over five years, the link observed between substance use and the appearance of psychopathology symptoms. In a final chapter, this thesis reviews data surrounding three types of preventative interventions to identify how empirical research could improve addiction prevention strategies.
The data was extracted from a group of adolescents issued from the general population followed longitudinally in the scope of the Co-Venture study (n = 3826, from 12 years of age upon admission to the study, followed up annually for a period of five years).
The results demonstrated that, although certain factors seem to predispose a sub-group of young people to early consumption and neuropsychological difficulties, drug consumption, especially cannabis consumption, seem to reliably predict a delay in the development of cognitive faculties, particularly the executive functions of the brain. This association with cannabis appears, to a small extent, to partially mediate the link already observed between said consumption and the emergence of psychopathology symptoms in adolescents. Still, predisposing factors seem to contribute to the association between these three variables. Although research would appear to show that several prevention strategies could be effective, most of them present modest and punctual results. The best-substantiated programs appeared to be those that adhered to a targeted prevention approach.
To improve our methods of substance use prevention, one could take predisposing factors into account and use them to inform specialized intervention. Baseline cognitive functioning could constitute a particularly promising avenue. All the same, certain predisposing factors such as temperament or personality seem better equipped to prevent early-onset substance misuse and to address the psychological and cognitive issues associated with adolescent substance intake.
To improve addiction prevention methods in adolescents, one could factor into account predisposing factors and use them to inform specialized intervention; for example, baseline cognitive functioning could constitute a promising avenue. In addition, temperament or personality traits seem better established to prevent early-onset substance use and to address the psychological and cognitive issues associated with adolescents’ substance misuse.
Key words: Alcohol, cannabis, adolescence, cognitive functions, psychopathology symptoms, longitudinal data, mediation, preventio
Commissioning and Evaluation of an Electronic Portal Imaging Device-Based In-Vivo Dosimetry Software.
This study reports on our experience with the in-vivo dose verification software, EPIgray® (DOSIsoft, Cachan, France). After the initial commissioning process, clinical experiments on phantom treatments were evaluated to assess the level of accuracy of the electronic portal imaging device (EPID) based in-vivo dose verification. EPIgray was commissioned based on the company's instructions. This involved ion chamber measurements and portal imaging of solid water blocks of various thicknesses between 5 and 35 cm. Field sizes varied between 2 x 2 cm2 and 20 x 20 cm2. The determined conversion factors were adjusted through an additional iterative process using treatment planning system calculations. Subsequently, evaluation was performed using treatment plans of single and opposed beams, as well as intensity modulated radiotherapy (IMRT) plans, based on recommendations from the task group report TG-119 to test for dose reconstruction accuracy. All tests were performed using blocks of solid water slabs as a phantom. For single square fields, the dose at isocenter was reconstructed within 3% accuracy in EPIgray compared to the treatment planning system dose. Similarly, the relative deviation of the total dose was accurately reconstructed within 3% for all IMRT plans with points placed inside a high-dose region near the isocenter. Predictions became less accurate than < 5% when the evaluation point was outside the treatment target. Dose at points 5 cm or more away from the isocenter or within an avoidance structure was reconstructed less reliably. EPIgray formalism accuracy is adequate for an efficient error detection system with verifications performed in high-dose volumes. It provides immediate intra-fractional feedback on the delivery of treatment plans without affecting the treatment beam. Besides the EPID, no additional hardware is required. The software evaluates local point dose measurements to verify treatment plan delivery and patient positioning within 5% accuracy, depending on the placement of evaluation points
The contribution of starspots to coronal structure
Significant progress has been made recently in our understanding of the
structure of stellar magnetic fields, thanks to advances in detection methods
such as Zeeman-Doppler Imaging. The extrapolation of this surface magnetic
field into the corona has provided 3D models of the coronal magnetic field and
plasma. This method is sensitive mainly to the magnetic field in the bright
regions of the stellar surface. The dark (spotted) regions are censored because
the Zeeman signature there is suppressed. By modelling the magnetic field that
might have been contained in these spots, we have studied the effect that this
loss of information might have on our understanding of the coronal structure.
As examples, we have chosen two stars (V374 peg and AB Dor) that have very
different magnetograms and patterns of spot coverage. We find that the effect
of the spot field depends not only on the relative amount of flux in the spots,
but also its distribution across the stellar surface. For a star such as AB Dor
with a high spot coverage and a large polar spot, at its greatest effect the
spot field may almost double the fraction of the flux that is open (hence
decreasing the spindown time) while at the same time increasing the X-ray
emission measure by two orders of magnitude and significantly affecting the
X-ray rotational modulation.Comment: 10 pages, 10 figure
The Capitalism of financial market and the control of cognitive (In French)
The aim of this paper is to question the cognitive capitalism hypothesis: are the major transformations of the wage labour nexus and regime of accumulation, created a new capitalism era? A positive answer to this question then relegates to a second rank the thesis of financial capitalism. For this last thesis, the financialisation of accumulation deeply transforms the firms. This paper develops this second point of view. Our conclusion is disappointing for the cognitive capitalism hypothesis. If the production of knowledge is important for the accumulation, nevertheless this production of knowledge is subordinated to the view of global finance. Indeed, it’s this global finance who decides which are new profitable activities.Cognitive capitalism, Capitalism of financial market, Firm, Production of knowledge, Financialisation
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Correction of megavoltage cone-beam CT images of the pelvic region based on phantom measurements for dose calculation purposes.
Megavoltage cone-beam CT (MVCBCT) is an imaging technology that provides a 3D representation of the patient in treatment position. Because it is a form of x-ray tomography, MVCBCT images give information about the attenuation coefficients of the imaged tissues, and thus could be used for dose calculation. However, the cupping and missing data artifacts seen on MVCBCT images can cause inaccuracies in dose calculations. To eliminate these inaccuracies, a correction method specific to pelvis imaging and based on phantom measurements has been devised. Pelvis-shaped water phantoms of three different sizes were designed and imaged with MVCBCT. Three sets of correction factors were created from the artifacts observed in these MVCBCT images by dividing the measured CT number by the predefined CT number for water. Linear interpolation is performed between the sets of correction factors to take into account the varying size of different patients. To compensate for the missing anatomy due to the limited field of view of the MVCBCT system, the MVCBCT image is complemented with the kilovoltage CT (kVCT) image acquired for treatment planning.When the correction method is applied to an anthropomorphic pelvis phantom, the standard deviation between dose calculations performed with kVCT and MVCBCT images is 0.6%, with 98% of the dose points agreeing within +/- 3%.With uncorrected MVCBCT images this percentage falls to 75%. An example of dose calculation performed with a corrected clinicalMVCBCT image of a prostate cancer patient shows that changes in anatomy of normal tissues result in variation of the dose distribution received by these tissues.This correction method enablesMVCBCT images to be used for the verification of the daily dose distribution for patients treated in the pelvis region
Photochemical synthesis of p-extended ullazine derivatives as new electron donor for efficient conjugated D–A polymers
We report the synthesis of π-extended ullazine derivatives annulated with either electron-poor pyridine or electron-rich thiophene units through a metal-free, photochemical cyclodehydrochlorination (CDHC) reaction. The strongest electron-donor derivative, 7-tetradecylthieno[3′,2′:7,8]indolizino[6,5,4,3-ija]thieno[2,3-c]quinolone, was copolymerized with electron-deficient thienopyrroledione (TPD), isoindigo (IID), and diketopyrrolopyrrole (DPP) derivatives to provide three donor–acceptor conjugated polymers (D–A CPs). Their photophysical, electrochemical and photovoltaic (PV) properties were investigated. The polymers showed broad UV-vis-NIR absorption bands with λmax values of 612 nm, 698 nm, 788 nm in chloroform and exhibited optical bandgap (Eoptg) of 1.58 eV, 1.41 eV, 1.24 eV measured as films. Inverted bulk heterojunction polymer solar cells (BHJ-PSCs) were fabricated using these polymers as host and light-harvesting materials. The device based on P3:PC70BM blends shows the best power conversion efficiency (PCE) of 2.23% (Voc = 0.55 V, Jsc = 7.86 mA cm−2, FF = 52%). These promising results demonstrate that π-extended ullazine derivatives can be used as electron-rich building blocks for the construction of D–A CPs for efficient PSCs applications
Recalage automatique de séquences vidéo infrarouge et visible basé sur les trajectoires des objets en mouvement
RÉSUMÉ
Le projet présenté dans ce document porte sur une nouvelle méthode pour effectuer le
recalage entre deux séquences vidéo de spectres différents soit l’une du spectre visible et
l’autre du spectre infrarouge. Un recalage consiste à retrouver la matrice de
transformation qui permet de passer d’un référentiel à un autre. Dans ce projet en
particulier, il s’agit de trouver la matrice de transformation affine qui permet de passer
du référentiel de la caméra infrarouge à celui de la caméra couleur. Ce recalage est
effectué pour chaque trame. Pour y arriver, la méthode proposée se base sur les
trajectoires des objets en mouvement ainsi que sur des combinaisons d’images d’avantplan
en recouvrement.
Plusieurs méthodes de recalage multispectral ont été proposées dans la littérature.
Cependant, il n’est pas toujours possible d’appliquer ces techniques dans le cas
spécifique d’un recalage entre des images couleur et infrarouge. Il existe cependant une
méthode qui semble avoir un bon potentiel. Il s’agit de la méthode de Caspi, Simakov,
& Irani (2006). Cette méthode utilise uniquement les trajectoires des objets en
mouvement pour retrouver la matrice de transformation entre les deux caméras. Cet
article fut la principale source d’inspiration de ce mémoire.----------ABSTRACT
This project is about a new registration method between a color video and an infrared
video. Registration is to find the transformation matrix from which you can pass from
one set of coordinates to another, for example, between two cameras. In this project, this
transformation matrix is an affine transformation matrix. This registration is done frame
by frame. It uses two kinds of information: the trajectories of moving objects and an
overlapped picture made from combinations of foreground pictures.
Multiple multispectral registration methods were found in the literature but not all of
these methods can be used for the specific case of an infrared-color registration. Even
so, a specific method (Caspi et al., 2006) seems promising to achieve this kind of
registration. This method uses only trajectories of moving objects to find the
transformation matrix. This article is the principal inspiration of this work
Planification collaborative dans l'environnement multiacteur public-privé des chaînes d'approvisionnement forestier du Québec : perspectives systémique, sociologique et informationnelle
La planification collaborative est perçue comme une composante fondamentale à la gestion de chaînes d’approvisionnement. Toutefois, l’hétérogénéité des peuplements forestiers et l’environnement distribué du secteur industriel forestier québécois complexifient la mise en oeuvre d’une planification collaborative performante. Dans ce contexte, les planificateurs forestiers ont à réaliser un double défi. D’une part, ils doivent mettre en oeuvre les orientations stratégiques et respecter les contraintes financières propres à leurs organisations. D’autre part, ils doivent se concerter afin de coordonner leurs approvisionnements avec les autres usines qui partagent un même territoire. La conciliation de ces deux éléments propres à la planification forestière rend cet exercice ardu. En effet, il s’avère complexe de concilier le désir d’autonomie propre à chaque organisation et la nécessité de coordonner de manière commune l’approvisionnement des usines. Pour répondre à cette problématique, nous avons exploré les bénéfices potentiels de l’intégration de systèmes pour le secteur forestier. La littérature qui porte sur ce concept d’organisation et de gestion de chaînes d’approvisionnement témoigne de bénéfices importants pour d’autres secteurs manufacturiers. Cependant, il y a peu d’indications dans la littérature sur les apports de l’intégration de systèmes pour le contexte particulier des chaînes d’approvisionnement forestier. Nous avons également mobilisé certains concepts provenant de la collaboration dans les chaînes d’approvisionnement. Ce domaine de recherche offre des pistes pertinentes afin de réfléchir sur un modèle de gouvernance multiorganisationnelle approprié qui permettrait de concilier la dichotomie entre « autonomie » et « interdépendance ». Pour y parvenir, nous avons réalisé une étude de cas multiple au moyen d’une méthode de recherche qualitative. Cinq cas d’étude ont été sélectionnés en se basant entre autres sur le niveau d’intégration de systèmes employé. Nous avons ainsi été en mesure de mieux comprendre de quelle manière une tierce partie de type intégrateur-système interagit avec les organisations d’une chaîne d’approvisionnement afin de faciliter la planification forestière collaborative. Parmi nos résultats, nous avons d’abord observé qu’une tierce partie de type intégrateur-système contribue à rendre le processus de la planification forestière opérationnelle plus performant lorsqu’il y a une bonne adéquation entre le niveau de complexité du contexte de coordination et le niveau observé d’intégration de systèmes. Nous avons ensuite constaté qu’une tierce partie de type intégrateursystème contribue à assurer et à maintenir une culture collaborative ainsi qu’à favoriser la confiance dans l’exercice de planification collaborative étudié. Finalement, une tierce partie de type intégrateursystème permet pour les chaînes d’approvisionnement forestier à l’étude d’améliorer la gestion du partage d’information en renforçant l’interopérabilité entre les organisations ministérielles et industrielles. Mots-clés : Planification collaborative, planification forestière, intégration de systèmes, collaboration dans les chaînes d’approvisionnement, chaîne d’approvisionnement forestier, étude de cas, recherche qualitative.Collaborative planning is seen as a fundamental component of supply chain management. However, forest stands heterogeneity and the distributed environment of Québec’s forestry industry make it difficult to implement effective collaborative planning. In this context, forest planners have to face a double challenge. On the one hand, they must implement strategic orientations and respect the financial constraints specific to their organizations. On the other hand, they must work together to coordinate their supplies with the other factories that share the same territory. Reconciling these two elements of forest planning makes this exercise difficult. It is complex to reconcile the desire for autonomy of each organization and the need to co-ordinate factories’ supply. To address this issue, we explored the potential benefits of systems integration for the forest sector. The literature on this concept of organization and management of supply chains shows significant benefits for other manufacturing sectors. However, there is little evidence in the literature of the contributions of systems integration to the particular context of forest supply chains. We also mobilized some concepts from the field of supply chain collaboration. This field of research offers relevant insights to reflect on an appropriate multi-organizational governance model that reconciles the dichotomy between "autonomy" and "interdependence". To achieve our goals, we conducted a multiple case study using a qualitative research method. Five case studies were selected based, among other things, on the level of systems integration employed. As a result, we have been able to better understand how a system-integrator third party interacts with supply chain organizations to facilitate collaborative forest planning. From our results, we first observed that a system-integrator third party helps to make the forest planning process more efficient when there is a good fit between the level of complexity in the coordination context and the observed level of systems integration. We then found that a system-integrator third party helps to ensure and maintain a collaborative culture and build trust in the collaborative planning exercise being studied. Finally, a system-integrator third party allows forest supply chains under study to improve the management of information sharing by enhancing interoperability between ministry and industry organizations. Key words: Collaborative planning, forest planning, systems integration, supply chain collaboration, forest supply chain, case study, qualitative research
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