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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
511

Thousand Cankers Disease of Eastern Black Walnut: Ecological Interactions in the Holobiont of a Bark Beetle-Fungal Disease

Geoffrey M Williams (11186766) 27 July 2021 (has links)
<p>Eastern black walnut (<i>Juglans nigra</i> L.) ranks among the most highly valued timber species in the central hardwood forest and across the world. This valuable tree fills a critical role in native ecosystems as a mast bearing pioneer on mesic sites. Along with other <i>Juglans</i> spp. (Juglandaceae), <i>J. nigra</i> is threatened by thousand cankers disease (TCD), an insect-vectored disease first described in 2009. TCD is caused by the bark beetle <i>Pityophthorus juglandis</i> Blackman (Corthylini) and the phytopathogenic fungus <i>Geosmithia morbida</i> Kol. Free. Ut. & Tiss. (Bionectriaceae). Together, the <i>P. juglandis</i>-<i>G. morbida</i> complex has expanded from its historical range in southwest North America throughout the western United States (U.S.) and Europe. This range expansion has led to widespread mortality among naïve hosts <i>J. nigra</i> and <i>J. regia</i> planted outside their native distributions.</p> <p> The severity of TCD was previously observed to be highest in urban and plantation environments and outside of the host native range. Therefore, the objective of this work was to provide information on biotic and abiotic environmental factors that influence the severity and impact of TCD across the native and non-native range of <i>J. nigra</i> and across different climatic and management regimes. This knowledge would enable a better assessment of the risk posed by TCD and a basis for developing management activities that impart resilience to natural systems. Through a series of greenhouse-, laboratory- and field-based experiments, environmental factors that affect the pathogenicity and/or survival of <i>G. morbida</i> in <i>J. nigra</i> were identified, with a focus on the microbiome, climate, and opportunistic pathogens. A number of potentially important interactions among host, vector, pathogen and the rest of the holobiont of TCD were characterized. The <i>holobiont</i> is defined as the whole multitrophic community of organisms—including <i>J. nigra</i>, microinvertebrates, fungi and bacteria—that interact with one another and with the host.</p> <p>Our findings indicate that interactions among host, vector, pathogen, secondary pathogens, novel microbial communities, and novel abiotic environments modulate the severity of TCD in native, non-native, and managed and unmanaged contexts. Prevailing climatic conditions favor reproduction and spread of <i>G. morbida</i> in the western United States due to the effect of wood moisture content on fungal competition. The microbiome of soils, roots, and stems of trees and seedlings grown outside the host native range harbor distinct, lower-diversity communities of bacteria and fungi compared to the native range, including different communities of beneficial or pathogenic functional groups of fungi. The pathogen <i>G. morbida</i> was also associated with a distinct community of microbes in stems compared to <i>G. morbida</i>-negative trees. The soil microbiome from intensively-managed plantations facilitated positive feedback between <i>G. morbida</i> and a disease-promomting endophytic <i>Fusarium solani</i> species complex sp. in roots of <i>J. nigra</i> seedlings. Finally, the nematode species <i>Bursaphelenchus juglandis</i> associated with <i>P. juglandis</i> synergizes with <i>G. morbida</i> to cause foliar symptoms in seedlings in a shadehouse; conversely, experiments and observations indicated that the nematode species <i>Panagrolaimus</i> sp. and cf. <i>Ektaphelenchus</i> sp. could suppress WTB populations and/or TCD outbreaks.</p> <p>In conclusion, the composition, function, and interactions within the <i>P. juglandis</i> and <i>J. nigra</i> holobiont play important roles in the TCD pathosystem. Managers and conservationists should be aware that novel associations outside the host native range, or in monocultures, intensive nursery production, and urban and low-humidity environments may favor progression of the disease through the effects of associated phytobiomes, nematodes, and climatic conditions on disease etiology. Trees in higher diversity, less intensively managed growing environments within their native range may be more resilient to disease. Moreover, expatriated, susceptible host species (<i>i.e.</i>, <i>J. nigra</i>) growing in environments that are favorable to novel pests or pest complexes (<i>i.e.</i>, the western U.S.) may provide connectivity between emergent forest health threats (<i>i.e.</i>, TCD) and native host populations (<i>i.e.</i>, <i>J. nigra</i> in its native range).</p>
512

Cognitive, behavioral and familial associations of reading acquisition and academic achievement : a population-based longitudinal study from kindergarten to middle school / Facteurs cognitifs, comportementaux et familiaux associés à l'acquisition de la lecture et à la réussite scolaire : une étude longitudinale de la maternelle au collège dans la population générale

Costa, Hugo Câmara 28 November 2014 (has links)
Les études longitudinales en milieu scolaire débutant en maternelle permettent une analyse des facteurs propres à l'enfant et à son environnement impliqués dans le développement de la lecture et de la réussite scolaire. Cependant, les études visant à analyser l'influence longitudinale de ces facteurs dès l'école maternelle restent exceptionnelles en France. Une étude épidémiologique initiée en 2001 dans la Communauté Urbaine de Creusot Montceau (Saône-et-Loire, France) avait comme objectif l'examen des contributions des facteurs propres à l'enfant et des variables environnementales dans l'acquisition de la lecture et la réussite scolaire dès la maternelle (3-6 ans) jusqu'au milieu de l'école élémentaire (CE2, 8-9 ans). Le travail de thèse présenté a permis le prolongement de la période de recueil de donnés jusqu'à la fin du collège (3ème, 14-15 ans) représentant une période de suivi de 10 ans dans la population générale. L'objectif principal de ce travail est d'identifier les facteurs propres à l'enfant (cognitifs, académiques et comportementaux) et des variables environnementales (facteurs sociodémographiques et caractéristiques familiales) dans le développement de la lecture à la fin de l'école primaire (CM2) et la réussite scolaire à la fin du collège (3ème). Les échantillons comprenaient 829 enfant inscrits en Grande Section de Maternelle pendant l'année scolaire 2001-2001 (Cohorte 1, 90% de l'échantillon initial) suivis jusqu'à la fin du collège (année scolaire 2010-2011) et 812 enfants de Grande Section de Maternelle durant l'année 2003-2004 (Cohorte 3) suivis jusqu'à la fin de l'école élémentaire (Cours Moyen 2, année scolaire 2008-2009). En Grande Section de Maternelle, le recueil de données a compris l'évaluation des compétences cognitives, académiques et comportementales des enfants, ainsi que le recueil des informations concernant le contexte familial. Les mesures de réussite scolaire ont compris les résultats des enfants dans les évaluations nationales réalisées à la fin du collège pour la Cohorte 1, (Diplôme National du Brevet) et les performances des enfants dans une mesure standardisée de lecture de mots à la fin de l'école élémentaire pour la Cohorte 3 (ODEDYS, Jacquier-Roux, Valdois & Zorman, 2002). Les compétences de traitement phonologique, la connaissance de lettres et le comportement attentif étaient les prédicteurs le plus significatifs de la lecture de mots au Cours Moyen 2. Le signalement par les parents d'antécédents familiaux de difficultés de lecture était associé simultanément avec des difficultés de lecture et le comportement inattentif à la fin de l'école élémentaire. En 3ème année du collège, les compétences de langage oral, la connaissance de lettres, la mémoire verbal à court terme, le raisonnement perceptif (facteur non-verbal) et le comportement attentif des enfants en maternelle, ainsi que le niveau d'éducation des parents et le type de famille, ont prédit significativement la mesure de réussite scolaire générale à la fin du collège. En outre, les résultats ont montré l'influence de plusieurs caractéristiques familiales dont la nationalité du père, le mode de garde avant la scolarisation, les rituels d'endormissement et les antécédents familiaux de difficultés de lecture. Ces caractéristiques renvoient à des facteurs qui mettent un enfant en risque d'échec scolaire à la fin du collège. Ce travail contribue à la littérature scientifique existante concernant les facteurs propres à l'enfant et à son environnent familial liés à l'acquisition de la lecture et à la réussite scolaire. Les résultats permettent l'identification des facteurs familiaux mettant un enfant à risque d'échec scolaire. Il ont des importantes implications pour repérer le plus précocement possible les enfants à risque de développer des difficultés de lecture et d'échec scolaire et pour mettre en place des programmes d'intervention adéquats à ses difficultés dès le début des trajectoires académiques de l'enfant. / Longitudinal studies starting during kindergarten provide an appropriate method to investigate the child- and environmental-level factors that account for children's reading and academic achievement later in their educational trajectories. In France, studies designed to follow-up children longitudinally from kindergarten onwards remain scarce. An epidemiological study started in 2001 in the Urban Community of Creusot Montceau (Saône-et-Loire, France) sought initially to identify the factors associated with children's reading acquisition and academic achievement from preschool (3-6 years) to the middle of elementary school (Grade 3, 8-9 years). The PhD project reported here aimed to extend the original design of data collection to the end of middle school (Grade 9, 14-15 years) spanning a 10-year follow-up period in the general population. This work aimed to investigate the specific contributions of child-level factors (cognitive-academic skills, behavior problems) and environment-level factors (sociodemographic and family characteristics) for children's subsequent reading acquisition at the end of elementary school (Grade 5), as well as academic achievement at the end of middle school (Grade 9). The samples of analysis comprised 829 kindergarteners in the 2001-2002 school year (Cohort 1, 90% of the initial sample) followed through the end of middle school (Cohort 1, 2010-2011 school year) and 812 kindergarteners in the 2003-2004 school year (Cohort 3), from which a sub-sample of 154 participants was followed through the end of elementary school (2008-2009 school year). At kindergarten, assessment included measures of children's cognitive-academic and behavioral skills, as well as family background characteristics. Outcome measures were composed of children's results in the national evaluations performed at the end of middle school for Cohort 1 ("Diplôme National du Brevet") and of children's scores in standardized measures of word reading achievement at the end of elementary school for Cohort 3 (ODEDYS, Jacquier-Roux, Valdois & Zorman, 2002). The results indicated that children's phonological processing skills, letter knowledge and attentive behavior were the most robust predictors of word reading achievement at Grade 5. In addition, parental reports of familial antecedents of reading difficulties also contributed to predict word reading at Grade 5 and were specifically associated with both reading difficulties and inattention behavior at this grade level. At Grade 9, children's oral language skills, letter knowledge, short-term verbal memory, perceptual reasoning (non-verbal cognitive ability) and attentive behavior at kindergarten predicted significantly the outcome measure of general academic achievement at Grade 9, together with parental educational level and family structure. Moreover, results indicated the influence of several family characteristics referring to father's nationality, type of early childcare, language-based bedtime routines and familial antecedents of reading difficulties as risk factors for children's subsequent academic underachievement. The present work contributes to the extant literature regarding the child- and family-level factors associated with subsequent reading acquisition and academic achievement from kindergarten to elementary and middle school. Importantly, these results allowed the identification of novel familial risk factors that influence negatively children's subsequent academic trajectories. These findings have important implications regarding the child and family factors that should be targeted during kindergarten in order to prevent children's subsequent reading and academic difficulties and to promote adequate intervention strategies early in children's educational trajectories.
513

Le sens de l’expérience évaluative pour les adultes allophones peu ou pas scolarisés en cours de français langue seconde : la perspective des femmes et des mères de famille issues du Maghreb

Mahjoubi, Oumaima 08 1900 (has links)
Les adultes allophones peu ou pas scolarisés (AAPPS) rencontrent des défis pour effectuer des tâches essentielles dans la société québécoise en raison de leurs compétences langagières limitées. Leur intégration socioculturelle et professionnelle s’avère donc difficile et soulève des enjeux socioéconomiques tant pour les AAPPS que pour la société en pénurie de main-d’œuvre. En apprenant le français dans le contexte formel de scolarité, les AAPPS font face à d’autres défis d’acculturation aux conventions scolaires, notamment aux évaluations formelles des apprentissages. En étudiant les particularités des AAPPS, Abbott et al. (2021), de même que Gonzalves (2020) ont mis en question l’évaluation de ce public parce qu’elle est faite de l’angle des personnes scolarisées sans considérer la perspective des AAPPS. Quant à Altherr Flores (2020), elle a critiqué la tendance à supposer que les AAPPS comprenaient l’évaluation alors qu’ils ignoraient les attentes des évaluateurs et leur rôle comme évalué selon Simpson (2006). Ces préoccupations soulèvent des enjeux éthiques d’équité, de diversité et de différenciation pédagogique pour une évaluation adéquate, d’où l’intérêt au sens de l’expérience évaluative aux yeux des AAPPS en cours formelle de francisation. Pour ce faire, l’approche phénoménologique de Giorgi (1997) permet d’étudier l’expérience des phénomènes vécus telle que comprise par les acteurs sociaux. L’analyse de six entretiens individuels semi-dirigés menés en arabe maghrébin, auprès de six participantes issues du Maghreb, permet de comprendre l’expérience évaluative des AAPPS comme un processus dynamique et continu d’exploration, d’acculturation et de maturation. L’exploration met en relief les premières expériences évaluatives caractérisées par la confrontation à la nouveauté, la surprise, le stress et le choc de l’échec. En acculturation, les AAPPS approprient l’évaluation et développent des stratégies pour réussir et pour gérer le stress qui diminue, mais demeure présent. Et en maturation, elles et ils réfléchissent sur leur évaluation, échec et réussite en lien avec leur besoin et habileté à l’extérieur de la classe. Ces résultats contribuent à éclairer les angles morts de l’expérience évaluative des AAPPS et présentent un appui pour les conceptrices et concepteurs des évaluations visant ce public. / Allophone adults with little or no schooling (AAPPS) face challenges in performing essential tasks in Quebec because of their limited language skills. Their socio-cultural and professional integration is therefore difficult and raises socio-economic issues both for the AAPPS and for the society facing a labour shortage. Learning French in the context of formal schooling, AAPPS face challenges related to acculturation to school conventions, particularly those of formal learning assessment. Based on the particularities of AAPPS, Abbott et al. (2021) as well as Gonzalves (2020) have questioned the assessment of this audience because it is made from the angle of educated people without considering the perspective of AAPPS. As for Altherr Flores (2020), she criticized the tendency to assume that AAPPS understood the assessment while ignoring the fact that AAPPS might misunderstand the expectations of the evaluators and their role as evaluated according to Simpson (2006). These concerns raise ethical issues of equity, diversity, and pedagogical differentiation for an adequate assessment, hence the interest in the meaning that the AAPPS give to their assessment experience in the formal francization course. The phenomenological approach of Giorgi (1997) makes it possible to study the experience of lived phenomena as understood by social actors. The analysis of the six semi-directed individual interviews conducted with six participants from the Maghreb in Maghrebi Arabic, allows us to understand the evaluative experience of the AAPPS as a dynamic and continuous process of exploration, acculturation, and maturation. Exploration concerns the first evaluative experiences characterized by the confrontation with novelty, surprise, stress, and the shock of failure. In the acculturation phase, AAPPS appropriate assessment and develop strategies to succeed and manage stress that diminishes but remains present. And in maturation, they reflect on their assessment, failure, and success in relation to their needs and abilities outside the classroom. These results shed light on blind spots of the AAPPS assessment experience and provide support for designers of assessment aimed at this audience.
514

Achieving Complex Motion with Fundamental Components for Lamina Emergent Mechanisms

Winder, Brian Geoffrey 01 March 2008 (has links) (PDF)
Designing mechanical products in a competitive environment can present unique challenges, and designers constantly search for innovative ways to increase efficiency. One way to save space and reduce cost is to use ortho-planar compliant mechanisms which can be made from sheets of material, or lamina emergent mechanisms (LEMs). This thesis presents principles which can be used for designing LEMs. Pop-up paper mechanisms use topologies similar to LEMs, so it is advantageous to study their kinematics. This thesis outlines the use of planar and spherical kinematics to model commonly used pop-up paper mechanisms. A survey of common joint types is given, as well as an overview of common monolithic and layered mechanisms. In addition, it is shown that more complex mechanisms may be created by combining simple mechanisms in various ways. The principles presented are applied to the creation of new pop-up joints and mechanisms, which also may be used for lamina emergent mechanisms. Models of the paper mechanisms presented in Chapter 2 of the thesis are found in the appendix, and the reader is encouraged to print, cut out and assemble them. One challenge associated with spherical and spatial LEM design is creating joints with the desired motion characteristics, especially where complex spatial mechanism topologies are required. Hence, in addition to a study of paper mechanisms, some important considerations for designing joints for LEMs are presented. A technique commonly used in robotics, using serial chains of revolute and prismatic joints to approximate the motion of complex joints, is presented for use in LEMs. Important considerations such as linkage configuration and mechanism prototyping are also discussed. Another challenge in designing LEMs is creating multi-stable mechanisms with the ability to have coplanar links. A method is presented for offsetting the joint axes of a spatial compliant mechanism to introduce multi-stability. A new bistable spatial compliant linkage that uses that technique is introduced. In the interest of facilitating LEM design, the final chapter of this thesis presents a preliminary design method. While similar to traditional methods, this method includes considerations for translating the mechanism topology into a suitable configuration for use with planar layers of material.
515

The Incompatibility of Freedom of the Will and Anthropological Physicalism

Gonzalez, Ariel 01 May 2014 (has links)
Many contemporary naturalistic philosophers have taken it for granted that a robust theory of free will, one which would afford us with an agency substantial enough to render us morally responsible for our actions, is itself not conceptually compatible with the philosophical theory of naturalism. I attempt to account for why it is that free will (in its most substantial form) cannot be plausibly located within a naturalistic understanding of the world. I consider the issues surrounding an acceptance of a robust theory of free will within a naturalistic framework. Timothy O’Connor’s reconciliatory effort in maintaining both a scientifically naturalist understanding of the human person and a full-blooded theory of agent-causal libertarian free will is considered. I conclude that Timothy O’Connor’s reconciliatory model cannot be maintained and I reference several conceptual difficulties surrounding the reconciliation of agent-causal libertarian properties with physical properties that haunt the naturalistic libertarian.

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