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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.
671

Reconnaissance des visages et des voix émotionnels dans une population adulte avec gliome et après accident vasculaire cérébral / Recognition of emotional faces and voices in adults with glioma and post-stroke adults

Luherne, Viviane 23 June 2015 (has links)
Après avoir longtemps ignoré le domaine des émotions, la neuropsychologie clinique reconnait aujourd’hui son intrication avec le domaine cognitif et son importance dans le suivi des patients cérébrolésés, chez lesquels des difficultés à reconnaître les émotions perturbent la qualité des échanges interpersonnels et la cognition sociale. Cette thèse porte sur la reconnaissance de cinq émotions de base (joie, peur, colère, tristesse, dégoût) et d’une expression neutre dans deux groupes de patients, avec gliome de bas grade et après accident vasculaire cérébral. L’évaluation recourt à deux modalités non verbales visuelles et auditives et une condition intermodale. Pour mieux comprendre le fonctionnement émotionnel des patients avec gliome, nous avons analysé les compétences émotionnelles de trois d’entre eux. Les résultats de nos recherches objectivent des difficultés modérées de reconnaissance des émotions en modalités visuelle et auditive pour les deux populations avec des déficits plus discrets chez les patients avec gliome de bas grade que chez les patients après accident vasculaire cérébral. Ces résultats confirment la pertinence de la théorie d’organisation hodotopique du cerveau pour les processus émotionnels comme pour les autres domaines cognitifs. Le bénéfice comportemental constaté pour les deux groupes en présentation intermodale ne suffit cependant pas toujours à normaliser les résultats, ce qui implique de probables répercussions quotidiennes. Ce travail souligne l’importance de l’évaluation des émotions non seulement reconnues, mais aussi ressenties, dans le suivi des patients cérébrolésés, notamment ceux qui souffrent de tumeurs d’évolution lente. / Emotional domain was ignored for a long time, but today clinical neuropsychology acknowledges its overlapping with the cognitive domain and its importance in the follow-up of brain-damage patients, where difficulties in emotion recognition reduce the quality of interpersonal interactions and social cognition. The present thesis focuses on the recognition of five basic emotions (happiness, fear, anger, sadness, disgust) and of a neutral expression in two groups of patients with low-grade gliomas and post-stroke. The experimental protocol, which requires visual and auditory non-verbal processing, also includes a crossmodal condition. Three case studies of patients with gliomas allow us to refine our understanding of their emotional functioning. Our results show moderate visual and auditory difficulties in emotion recognition for both groups, with lower deficits in the glioma group than in the post-stroke group. These results confirm the relevance of a hodotopical view of the brain for emotional processes as in other cognitive domains. However, the behavioral benefit of crossmodal presentation observed in both groups is not sufficient to sustain normal results, which is likely to impact daily life. We highlight the necessity of evaluating emotion recognition as well as emotion experience in brain damage patients, in particular when they suffer from slowly infiltrating tumours.
672

Gliomes diffus de bas grade : données épidémiologiques et hypothèses étiologiques. / Diffuse low-grade gliomas : epidemiology and etiologic hypotheses.

Darlix, Amélie 16 September 2016 (has links)
L’épidémiologie et les facteurs de risque des gliomes diffus de bas grade (GDBG, ou gliomes diffus de grade II OMS) sont à ce jour mal connus. Ce travail de thèse s’est intéressé à décrire les caractéristiques épidémiologiques (taux d’incidence, données démographiques) et à rechercher, dans la littérature et par nos travaux, des arguments en faveur de facteurs de risque environnementaux, fonctionnels et moléculaires. Epidémiologie descriptive : l’analyse d’une série exhaustive de cas incidents de GDBG diagnostiqués entre 2006 et 2011, à l’échelle nationale, a permis de déterminer l’incidence des GDBG dans leur ensemble (incidence standardisée sur la population française : 0,775/105 personnes-années) et pour chacun de leurs sous-types histologiques définis par la classification 2007 de l’OMS. Facteurs de risque environnementaux : nous avons pu mettre en évidence des différences significatives dans la distribution géographique des gliomes diffus de grade II et III OMS en France métropolitaine, avec une incidence plus élevée dans le Nord-Est et le centre de la France. Cette hétérogénéité semble en faveur de facteurs de risque environnementaux, même s’il n’existe à ce jour aucun facteur de risque environnemental démontré dans les GDBG. Facteurs de risque biologiques : notre travail a permis de démontrer l’existence d’une dichotomie sur le plan moléculaire entre les GDBG de topographie frontale, plus fréquemment mutés IDH et codélétés 1p19q, et les GDBG temporo-insulaires, moins fréquemment mutés IDH et codélétés 1p19q, suggérant des voies de gliomagénèse différentes pour ces deux patterns tumoraux. Facteurs de risque fonctionnels : enfin, comme le montrent les données de la littérature, il existe deux arguments principaux en faveur de facteurs de risque fonctionnels dans les GDBG. D’une part, ces tumeurs présentent des localisations intracérébrales spécifiques et distinctes des autres gliomes, et impliquent préférentiellement les zones dites « fonctionnelles ». D’autre part, des modifications macroscopiques cérébrales ont été rapportées en lien avec l’apprentissage d’une tâche ou une expertise particulière. Les mécanismes microscopiques qui sous-tendent ces modifications sont encore incertains mais une implication (directe ou indirecte) des cellules gliales, semble probable, ce qui pourrait faire le lit de la gliomagénèse. Peu d’études se sont intéressées jusqu’à présent aux corrélations entre les activités du sujet et le risque de GDBG, et nous proposons donc, dans les suites de ce travail de thèse, une étude cas-témoins en ce sens. En conclusion, même s’il n’existe à ce jour aucun facteur de risque démontré de GDBG, certains éléments bibliographiques, et les travaux de cette thèse, suggèrent l’implication de facteurs environnementaux, fonctionnels et biologiques dans la genèse des GDBG. / The epidemiology and risks factors of diffuse low-grade gliomas (DLGG, or WHO grade II diffuse gliomas) are yet poorly known. This thesis aimed at describing the epidemiology (incidence rates, demographic data) and at looking for arguments in favor of environmental, functional and molecular risk factors, in the literature and by our works. Descriptive epidemiology: The analysis of an exhaustive series of incident cases of DLGG diagnosed between 2006 and 2011 allowed the determination of DLGG incidence (incidence rate standardized on the French population: 0,775/105 person-years) as well as that of each histological subtype described by the 2007 WHO classification. Environmental risk factors: We were able to demonstrate significant differences in the geographical distribution of WHO grade II and III diffuse gliomas in metropolitan France, with higher incidence rates in the North-East and Center regions. This heterogeneity stands in favor of environmental risk factors, even though there is to date no proven environmental risk factor for DLGG. Biological risk factors: Our work demonstrated the existence of a clear dichotomy, regarding molecular biology, between frontal DLGG, more frequently IDH-mutated and 1p19q codeleted, and temporo-insular tumors, less frequently IDH-mutated and 1p19q codeleted, suggesting different gliomagenesis pathways for these two patterns of tumors. Functional risk factors: Finally, data from the literature provide two main arguments in favor of the existence of functional risk factors in DLGG. First, the intra-cerebral location of these tumors is specific and distinct from that of other gliomas, with a preferential implication of “functional” areas. Second, macroscopic intra-cerebral changes have been reported following training on specific tasks, or in relation with a specific expertise. The microscopic mechanisms that underlie these modifications are uncertain but an implication (direct or indirect) of glial cells seems probable, and could favor gliomagenesis. To date, only few studies have investigated the correlation between the subject’s activity and the risk of DLGG. We thus propose, following this thesis, a case-control study to further investigate this issue. In conclusion, even though there is no demonstrated risk factor for DLGG, data from the literature, and conclusions from the present work, suggest the implication of environmental, functional and biological factors in DLGG genesis.
673

Práticas pedagógicas de professoras em classes multisseriadas : uma contribuição para a atuação docente no ciclos de alfabetização /

Araújo, Nilza Cristina Gomes de. January 2010 (has links)
Orientador: Maria Regina Guarnieri / Banca: Dirce Charara Monteiro / Banca: Silvia Regina Ricco Lucato Sigolo / Banca: Dimair de Souza França / Banca: Luciana Maria Giovanni / Resumo: A partir do contexto de Ciclo Básico de Alfabetização Cidadã - CBAC para as escolas municipais de Várzea Grande, em que se inserem tanto as professoras de classes multisseriadas como as de classes seriadas, a presente pesquisa teve a intenção de investigar como as práticas pedagógicas dessas docentes são construídas, e em que medida as práticas pedagógicas das professoras de classes multisseriadas poderiam contribuir com a dinâmica de trabalho das professoras de classes cicladas. A investigação pode ser considerada de natureza empírica. Os dados foram obtidos por meio da técnica de grupo focal no mês de dezembro de 2006, entrevistas semiestruturadas com oito professoras (quatro professoras de classes multisseriadas com turmas de alunos das quatro séries iniciais do ensino fundamental e quatro professoras com classes cicladas) e observações pontuais em uma classe multisseriada e uma classe ciclada. A hipótese foi a de que a experiência de trabalho no universo de classes multisseriadas imprime uma rotina de trabalho que obriga os professores a desenvolverem uma dinâmica polivalente de ação, pois atendem diferenciadamente aos alunos, adotam um fazer pedagógico ativo, elaboram um planejamento diário incluindo a aplicação de várias atividades diferenciadas. Suas práticas docentes tornam-se mais adequadas ao que o CBAC propõe. Como referencial teórico, utilizaram-se autores como Nagel; Galvanin ; Souza e Farias; Shiroma, Moraes Evangelista, para apresentar como as práticas pedagógicas docentes tentam se estruturar em face de um contexto em constante mudança. Para discorrer sobre quando as práticas pedagógicas dos professores são adequadas em face de uma nova proposta pedagógica em uma sociedade dinâmica, buscou-se respaldo em autores como Roldão, sobre a definição dos papéis e das funções que os docentes devem desempenhar no contexto escolar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Considering the Basic Cycle of Citizen Literacy (Ciclo Básico de Alfabetização Cidadã - CBAC), applied in municipal schools in Várzea Grande (MT/Brazil), both in multi-grade and single-grade class teachers, the research intended to investigate how the teaching practices of multi-grade class teachers are constructed and how they could contribute to the dynamics of single-grade classes. The empirical data were obtained by means of focal groups in December 2006, semi-structured interviews with eight teachers (four multi-grade class teachers and four single-grade class teachers) and observations in one multi-grade class and one single-grade class). The hypothesis was that the work experience of multi-grade class teachers would be more versatile and more appropriate than what is proposed by CBAC. To enable a differentiated service to pupils, the daily work of multi-grade class teachers favors versatile and dynamic actions, involving the implementation of several different activities. The research used authors such as Nagel; Galvanini; Souza and Farias; Shiroma, Moraes Evangelista, to show how the pedagogical practices are structured in a changeable context. The argument of the importance of teachers' practices in face of a new pedagogical proposal in a changing society was founded in Roland (2007), who brings elements to define the roles and functions of teachers in schools, Villa Sánches, who suggests a model of teacher behavior to cope with the changes imposed by the educational proposals, and Gimeno, who defines the concept of teaching practices. The results showed that teachers of multi-grade classes submitted to the implementation of the Active School Program (Programa da Escola Ativa), from the CBAC proposal, presented changes in their behaviors and their teaching practices. Such changes were observed when the teachers saw positive results in their pupils' learning progress... (Complete abstract click electronic access below) / Doutor
674

Temperature measurement technique in fiber Bragg gratings networks using optical feedback = Nova técnica para medida de temperatura em redes de sensores de grades de Bragg em fibras ópticas usando realimentação óptica / Nova técnica para medida de temperatura em redes de sensores de grades de Bragg em fibras ópticas usando realimentação óptica

Pfrimer, Felipe Walter Dafico, 1984- 10 January 2013 (has links)
Orientador: Jose Antonio Siqueira Dias / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-24T00:41:09Z (GMT). No. of bitstreams: 1 Pfrimer_FelipeWalterDafico_D.pdf: 3374919 bytes, checksum: aa34af0e6bc2013297d4bd53c2901a20 (MD5) Previous issue date: 2013 / Resumo: O crescente interesse na utilização de Grades de Bragg (FBG) em sistemas sensores pode ser explicado por algumas de suas características, que são: imunidade à interferência eletromagnética (EMI), isolamento elétrico, baixo peso, flexibilidade, e transmissão de informações a longa distância. Este trabalho apresenta uma nova técnica de interrogação capaz de medir a temperatura de uma rede de sensores de grades de Bragg em fibras ópticas, onde um circuito eletrônico realiza rotinas de controle possibilitando a implementação de uma realimentação óptica. O esquema optoeletrônico empregado é capaz de realizar a interrogação de todos os sensores da rede de maneira quase instantânea, além de permitir que novos sensores possam ser facilmente acrescentados. Um protótipo contendo dois sensores foi construído e testado para validar a técnica obtendo-se uma alta resolução de ± 1 mºC na medida de temperatura em uma faixa de 72ºC / Abstract: The increasing interest in the use of fiber Bragg gratings (FBG) in sensing systems can be explained by some of its features, which are immunity to electromagnetic interference (EMI), electrical insulation, low weight, flexibility, and long distance data transmission capability. This work presents a new interrogation technique capable of measuring temperature of Bragg gratings sensor networks in optical fibers, where an electronic circuit, capable to perform control routines, allows the implementation of an optical feedback. The optoelectronic scheme used is capable of performing the interrogation of all the sensors of the network almost instantly, and allows new sensors to be easily added. A prototype containing two channels was built and tested to validate the technique achieving a high resolution of ± 1 mºC in temperature measurements in a range of 72º C. / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica
675

Caractérisation métallurgique et modélisation de la tenue en fluage à 550°C des liaisons soudées en acier Grade 92 / Experimental characterization and modeling of the creep strength at 550°C of ASME Grade 92 steel welded joints

Kalck, Charlotte 06 December 2012 (has links)
Ce projet de thèse s'inscrit dans le cadre du développement de la future génération de réacteurs nucléaires, la génération IV. L'acier Grade 92, appartenant à la famille des aciers à 9-12% de chrome, est un candidat potentiel pour des composants de cette future génération de centrales. Ces structures sont assemblées par soudage.L'objectif de ce projet est de caractériser expérimentalement et de modéliser le comportement en fluage à 550°C de ces joints soudés en acier Grade 92 (9Cr-0,5Mo-1,8W-V-Nb).L'une des grandes problématiques des soudures en acier à 9 % de chrome est leur sensibilité à la rupture de type IV (rupture en zone intercritique (ICHAZ) ou dans la zone à petits grains (FGHAZ)) qui se produit généralement lors de sollicitations en fluage à basses contraintes et à hautes températures.Deux produits d'apports sont utilisés pour l'étude. Les soudures sont issues de l'assemblage par procédés TIG de deux tubes en position bout à bout. Une campagne d'essais de fluage à 550 °C sur éprouvettes travers joint en acier Grade 92 a été menée. Les expertises réalisées sur les éprouvettes de fluage indiquent que la rupture se produit en ICHAZ y compris pour les essais de fluage les plus courts (moins de 1000h).La modélisation du comportement en fluage du joint soudé complet a nécessité au préalable d'obtenir un modèle de comportement de chaque zone, en particulier de l'ICHAZ et de la zone fondue.Des essais de fluage sur des éprouvettes entaillées prélevées dans le joint ont permis d'accéder au comportement en fluage de ces deux zones. Une méthode complémentaire a été utilisée afin d'obtenir le comportement en fluage de l'ICHAZ. Cette méthode consiste à réaliser des essais de fluage sur des éprouvettes en microstructure de synthèse de la zone intercritique.Une caractérisation microstructurale fine de différentes zones de la soudure a été entreprise. Afin de comprendre les raisons de la faible résistance mécanique en fluage de l'ICHAZ, les microstructures de l'ICHAZ et du métal de base ont comparées à différentes échelles (MEB, EBSD, MET). Cette comparaison a également permis de valider la microstructure de synthèse. La caractérisation microstructurale des deux zones ne révèle pas de différences significatives ni sur la matrice de martensite revenu, ni en termes de précipitation. L'origine de sa moindre résistance à l'écoulement viscoplastique n'est donc pas résolue.Un effet de structure lié aux différences de propriétés mécaniques des zones de la soudure, est quantitativement étudié par modélisation des essais de fluage sur joint complet. / In the framework of the development of Generation IV nuclear power plants, ASME Grade 92 ferritic-martensitic steel is a candidate material for components subjected to long-term creep at high temperature. The aim of this study is to characterize the microstructure of Grade 92 butt welded joints and to model their creep behavior at 550 °C. Two filler rods were used for this study.The microstructure of the different weld regions was quantitatively characterized. In order to understand the weaker mechanical properties of the ICHAZ compared to the other regions of the welded joint, the microstructures of the base metal and the ICHAZ were compared at different scales (SEM, EBSD, TEM on thin foils and extractive replicas). No significant difference regarding microtexture, sub-structure and precipitation state was highlighted between both microstructures. The origin of the weaker resistance of the ICHAZ to viscoplastic flow is still not fully understood. A softer zone was found in the base metal close to the ICHAZ, yet with finer subgrains than the base metal,. It was supposed to be a thermomechanically-affected zone (TMAZ).At high temperatures and low stress levels, Grade 92 welded joints may be sensitive to type IV cracking, which occurs in the intercritical heat affected zone (ICHAZ). Creep tests conducted at 550 °C on cross-weld specimens revealed that fracture takes place in the ICHAZ, even for short-term creep tests (i.e., lifetime lower than 1000h).In order to model the creep behavior of the welded joint, viscoplastic constitutive equations for the different regions of the weld assembly were required. The viscoplastic behavior of the base metal, weld metal and of the ICHAZ were modeled using a phenomenological approach. The viscoplastic flow behavior of the weld metal and of the ICHAZ was experimentally determined (i) from tensile tests with displacement field measurements and (ii) from creep tests on tensile bars notched in the region of interest. An alternative method was also used to determine the creep behavior of the ICHAZ. It consists in reproducing the microstructure of this region by a thermal treatment and in carrying out creep tests on notched specimens cut from the heat-treated blanks. The parameters of constitutive equations (power-law flow rule together with a von Mises equivalent stress formulation and isotropic hardening according to a Voce-type evolutionary equation) were then fitted separately for the different zones of the welded joint.Constraint effects related to differences in mechanical properties between the different regions were quantitatively studied trough modeling of creep tests on the cross-weld specimens. For the stress levels experimentally considered, the contrast in strength between the different regions induces an increase in stress triaxiality in the softer zone (i.e. the ICHAZ) together with strain localization.Keywords: Creep, welded joint, Grade 92 steel.
676

Metaphoric Competence of Learning Disabled and Normally Achieving Children

Stimson, Wanda Fields 08 1900 (has links)
Metaphorlc competence of learning disabled and normally achieving fifth and seventh grade male children was Investigated. Four measures were made of metaphorlc abilities. The first task was a multiple choice written test to determine the rate of metaphorlc preference. Part two consisted of children developing metaphors. Part three and four required explanations of the meaning of preferred metaphors and produced metaphors.
677

Recherche d’alternatives thérapeutiques aux taxanes dans les cancers de la prostate de hauts grades : identification d’une signature prédictive de la réponse à l’oxaliplatine / Research of therapeutic alternatives to taxanes for high grade prostate cancers : identification of a gene expression signature predicting response to oxaliplatin

Puyo, Stéphane 16 December 2011 (has links)
Les cancers de la prostate sont classés en deux catégories. Les cancers de haut grade se distinguent des cancers de bas grade par une plus forte agressivité et un pronostic plus mauvais. Lorsqu’ils deviennent résistants à l’hormonothérapie, les cancers de haut grade sont traités par une chimiothérapie basée sur les taxanes. Néanmoins, les taux de réponse restent faibles. Il existe donc un réel besoin quant à l'identification d'alternatives thérapeutiques qui soient spécifiques de ce type de tumeur. Dans cette optique, notre travail a été de proposer une telle alternative par une approche qui prenne en compte la génétique spécifique des cancers de haut grade. Nous avons exploité une signature de 86 gènes dont le niveau d’expression permet de discriminer entre les tumeurs de haut et de bas grade. Par une approche in silico originale utilisant la banque de données du NCI, nous avons identifié 382 corrélations entre le niveau d’expression de 50 gènes et la sensibilité à 139 agents antiprolifératifs. Parmi ces corrélations, nous avons identifié une signature de 9 gènes qui est spécifique de la réponse à l’oxaliplatine. Cette signature a été confirmée sur le plan fonctionnel dans les lignées cancéreuses prostatiques DU145 et LNCaP. Nous avons donc fourni la preuve de concept que notre approche permet d’identifier de nouvelles molécules pouvant être utilisées en alternative aux taxanes pour traiter spécifiquement les cancers de haut grade. Cette stratégie permet aussi d’identifier de nouveaux marqueurs (gènes) régulant la sensibilité à certains médicaments. Nos résultats démontrent par exemple le rôle des gènes SHMT, impliqués dans la régulation du métabolisme monocarboné, dans la sensibilité spécifique à l’oxaliplatine par un mécanisme qui fait intervenir, du moins en partie, une dérégulation du niveau de méthylation global de l’ADN. / Prostate cancers are classified in two categories. High grade cancers are distinguished from low grade cancers by their higher agressivity and worse prognostic. When they become refractory to hormone therapy, high grade cancers are treated with a taxane-based chemotherapy. However, response rates remain low. Therefore, there is a real need for the discovery of new therapeutic alternatives which are specific for this type of tumors. For that purpose, our work aimed at proposing such an alternative with a strategy that took into account the high grade genetic background. We exploited a signature of 86 genes for which expression level could distinguish between low grade and high grade tumours. With an original in silico approach, we searched the NCI databases and identified 382 correlations between 50 genes and the sensitivity to 139 antiproliferative agents. Among these, a signature of 9 genes was able to specifically predict cell response to oxaliplatin. This signature was validated at the functional level in two prostate cancer cell lines, DU145 and LNCaP. We have thus provided the proof-of-concept that our approach allows the identification of new drugs that can be used alternatively to taxanes in order to specifically treat high grade prostate cancers. This strategy also allows the identification of new markers (genes) regulating the sensitivity to various drugs. Our results demonstrate for example the implication of SHMT genes, which are involved in the regulation of the one-carbon metabolism, in the specific sensitivity to oxaliplatin, by a mechanism which involves, at least in part, the deregulation of the global level of DNA methylation.
678

The Relationship of Video Games and Physical Activity to Homework Performance in Fourth and Fifth Grade Students

Malkus, Amy J., Edmonds, K., Leitnaker, S., Lutz, S., Moore, Janese, Rose, J. 01 July 2006 (has links)
No description available.
679

High school string orchestra teacher as a career choice: A survey of 11th- and 12th-grade high school string orchestra students in Texas.

Brumbaugh, Sherron M. 12 1900 (has links)
The purpose of this study was to describe 11th- and 12th-grade high school string orchestra students in Texas public schools in terms of their decision to enter the field of string orchestra teaching as a possible career choice or to pursue another field of study. Convenience sampling techniques were used to secure a study population of 1,683 high school string orchestra students. The Junior and Senior High School String Orchestra Student Survey (researcher designed) was used to gather demographic characteristics, students' perceptions on selected intrinsic/extrinsic work values, tangible elements of teaching, intrinsic characteristics of string orchestra teaching, and individuals assisting in students' career choices. Selected elements of teaching cited by students for their lack of interest in string orchestra teaching were also reviewed. Analysis procedures for descriptive statistics included measures of central tendency, crosstabulation, frequencies and percentages. Consistent with prior research, it was found that a larger number of female students over male students were interested in string orchestra teaching. Students interested in fields outside of string orchestra teaching reported higher class grades, more honors and advanced classes and higher SAT/ACT mean scores. Students interested in string orchestra teaching reported a higher percentage of brothers/sisters, mothers and fathers who played instruments and relatives who were teachers. These students also reported a greater importance of a career that was self-rewarding, that would be directly helpful to society and where they could help contribute to the welfare of society. Students interested in string orchestra teaching expressed the great importance of their deep devotion to music and their desire to be a positive role model for children. Students interested in string orchestra teaching reported the great importance of their high school orchestra director as one of the individuals assisting them in their career decisions. Also consistent with prior research, the number one cited reason for a lack of interest in string orchestra teaching was found to be that teacher's salaries were perceived as too low. Examinations of ethnic group differences relative to the characteristics under investigation were also explored.
680

The use of higher steel grades in building elements

Berggren, Hampus January 2021 (has links)
Structural steel is one of the main building materials used commercial. Its strength is its formality and high yield strength which allows less material overall. Steel is often divided into steel grades such as S275, S355, S420 and so forth. The purpose of this thesis is to look at the strength and weaknesses of the different steel grades and how the area gets effected by higher steel grades. This is done by looking at a real life project where only S355 is used and optimizing for S355, S420 and S460. This is done to shred some light on how much of an improvement the upgrade of steel grade may allow. For each steel grade an optimized cross section is created with the goal of having the lowest area possible. The difference in area for the optimized beams will act as the benchmarking for projected reductions. This optimization is done with the help of Python and follows Eurocode. When looking at the case study, the projected weight reduction is 4,2% for S420 and 7,2% for S460 compared to S355. This reduction is higher on some beams and lower on others. The main driving force for the higher reduced beams is the possibility to utilize more than one type of load condition, example both momentand shear force. Out of the 12 beams, beam 10 have the highest reduction between S355 and S420 which land around 10%. Between S355 and S460 Beam 12 comesin at a area reduction of 14%. As the higher steel grades have a higher equivalent CO2 emission the reduction of equivalent CO2 is lower than the area reduction. The projected reduction of equivalent CO2 for a switch from S355 to S420 is 3,3% and the reduction between S355 and S460 are 5,0%

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