[pt] Arcos abatidos são usados com frequência para vencer grandes vãos. Exemplos incluem pontes em arco e coberturas de grandes espaços como galpões industriais e estádios. Em muitos casos empregam-se arcos atirantados ou apoiados em estruturas flexíveis, fazendo com que os apoios se movam quando o arco é carregado. Isto aumenta a flexibilidade do sistema e a probabilidade de perda de estabilidade na presença de cargas estáticas e dinâmicas. Em muitos casos estas estruturas podem ser modeladas como arcos com apoios elásticos. No presente trabalho resolve-se o problema de estabilidade estática de forma analítica e através de uma aproximação usando o método de Ritz, servindo a solução analítica para aferir a precisão do modelo numérico. A seguir, com base neste estudo, desenvolve-se, usando o método de Ritz, a formulação para análise das vibrações não lineares do arco com apoios elásticos, assunto inédito na literatura. Os resultados mostram a grande influência dos apoios nas vibrações não lineares e na estabilidade do arco sob cargas estáticas e dinâmicas. / [en] Shallow arches are often used to overcome large spans, for example, arch bridges or steel roofs to cover large spaces such as industrial sheds and stadiums. In many cases the arches are tied or are supported by a flexibility structure, causing that supports to move when the arch has been loaded. This increases the flexibility of the system and the probability of loss of stability in the presence of static and dynamic loads. In many cases, these structures can be modeled as arches with elastic supports. In the present work the static stability has been solved analytically and through the Ritz method, serving the analytical solution to assess the accuracy of the numerical model. Then, based on this study, the analysis of nonlinear vibrations of shallow arches with elastic supports is developed, using the Ritz method, a subject not yet studied in the literature. The results show the noticeable influence of the supports on the nonlinear vibration and stability of shallow arches under static and dynamic loads.

[pt] Dentro do campo dos controladores passivos, um dos dispositivos usados pelas suas propriedades de amortecimento são os Apoios Elásticos, que constituem uma solução econômica e efetiva na supressão ou atenuação das vibrações em sistemas dinâmicos com problemas de ressonância ou instabilidade, freqüentemente pela falta de amortecimento suficiente. Este trabalho envolve o estudo de um rotor horizontal com apoios elásticos (silicone), adaptado a partir de um rotor existente, o estudo de diversos efeitos sobre a sua operação, a medição de seu movimento, a identificação dos parâmetros do problema, a medição e validação a partir de resultados simulados em um modelo numérico. Os fenômenos incluídos no estudo são o efeito giroscópio (rotor descentrado com respeito do vão), desbalanceamento do rotor e empenamento do eixo. Neste trabalho os parâmetros do sistema foram determinados usando técnicas de identificação, análise modal e otimização não linear devido à anisotropia do sistema. / [en] Viscoelastic Passive Controllers are an important field of technological research due to the development of new materials and design techniques. Damping properties allow an easy retrofit of existing machines with excessive vibration problems, developing Elastomeric Bearing Supports. They are an economic and effective solution in the suppression or attenuation of vibrations in dynamic systems suffering from instability or resonance problems, which often lack of sufficient damping. This work involves the study of an horizontal rotor with elastomeric bearing supports, adapted of another one, the study of several effects on his operation, the measurement of his motion, the identification of the problems parameters, the measurement and validation from the simulated results in a numeric model. Phenomena included in the study are the gyroscopic effect (rotor out of the middle), rotor unbalance and shaft bow. In this work the systems parameters were determined using identification, modal analysis and nonlinear optimization techniques due to the anisotropy of the system.

"Catalytic growth of Carbon Nanotubes (CNT) provides important advantages of controlling their diameters and possibly chirality. Our work involved growing CNT on model and supported catalyst by catalytic decomposition of carbon source such as benzene, methane and propylene. On supported catalyst, iron nitrate was deposited on alumina and reduced to form metallic iron clusters. These were reacted at 700 - 950 C under varying benzene concentrations. Multi Walled CNT (MWNT) grew below 800 C and Single Wall CNT (SWNT) are observed at 850 C and above as confirmed by TEM and Raman. Model catalysts were studied by producing CNT from ferrocene which acted as the carbon and catalyst source on Silica/Si (100). Large yield of MWNT was observed at 900 C. MWNT grew perpendicular to the model support as seen by SEM. In another model catalyst study, iron salt clusters were deposited on silica/Si (100) by spin coating, controlling their diameters by solution concentration and speed of spinning. Agglomeration of clusters at high temperatures produces only MWNT on silica/Si (100). Cluster agglomeration can be reduced with strong support metal interaction such as with alumina. We deposited alumina on silica/Si (100) by atomic layer deposition, with conformal coatings on surface and low relative roughness. Alumina film was stable under reaction temperatures of 900 C. Cluster deposition on alumina by spin coating was difficult because of different surface acidity compared to silica. Clusters on alumina did not agglomerate at high reaction temperatures. We report effect of parameters such as the temperature of reaction, conditions of pretreatment such as reduction and oxidation of catalyst precursor, type of precursor, type of carbon source, and type of support material on growth of CNT. The role of spin coating in controlling the diameter of salt clusters deposited is discussed. We also report deposition of alumina on top of silica/Si (100) by atomic layer deposition and the effect of deposition and calcination temperatures on the alumina film integrity."

This study evaluated the predictive and concurrent validity of the Tiered Fidelity Inventory (TFI). Structural equation modeling was applied to test the associations between the TFI and student outcomes. First, a total of 1,691 schools with TFI Tier 1 in 2016-17 and school-wide discipline outcomes in 2015-16 and 2016-17 were targeted, finding a negative association between TFI Tier 1 and differences between African American and non-African American students in major office discipline referrals (ODR) per 100 students per day in elementary schools. A sensitivity test with schools with TFI Tier 1, 2, and 3 was conducted, showing a negative association between TFI Tier 1 and the square root of major ODR rates in elementary schools. Second, TFI Tier 1 was positively related to the proportions of students meeting or exceeding state-wide standards in reading from 1,361 schools with TFI Tier 1 and academic outcomes in 2014-15 and 2015-16. Also, the association between TFI Tier 1 and academic outcomes was found to be stronger when schools implemented SWPBIS for 6 or more years. A sensitivity test with schools with TFI Tier 1, 2, and 3 indicated positive associations between TFI Tier 1 and the proportions of students meeting or exceeding state-wide standards in both subjects. Third, TFI Tier2 was positively associated with the logit of proportions of students with CICO daily points from 570 schools with TFI Tier 2 in 2016-17 and CICO outcomes in 2015-16 and 2016-17. Fourth, correlations between the Evaluation subscale of TFI Tier 1 or 2 and relevant measures in 2016-17 were tested from 2,379 schools. TFI Tier 1 Evaluation was positively correlated with counts of TFI administrations, number of fidelity measures, and counts of viewing SWIS Reports. These correlations were significant except for ODRs by staff. Also, TFI Tier 2 Evaluation was significantly positively correlated with years of SWPBIS implementation, years of CICO-SWIS implementation, and counts of viewing CICO Reports except student period, and negatively with counts of viewing student single period. These findings were discussed by comparing them with previous research findings, suggesting implications for future research and practice, and addressing research limitations.

School-Wide Positive Behavioral Interventions and Supports (SWPBIS) is a school disciplinary framework seen as an effective tool to replace school disciplinary practices that contribute to the school to prison pipeline (STPP). While evidence suggests that SWPBIS can help improve school discipline and lower suspension/expulsion rates, it has not been shown to consistently decrease racial disciplinary disparities. This study thematically analyzed semi-structured interviews of educational staff at one high school at the outset of SWPBIS implementation to understand their perceptions of school discipline and the potential for SWPBIS to address root causes of racial disciplinary disproportionality. Using a critical race theory analytical lens to center issues of race and racism, the findings revealed a school that is deeply structured in Whiteness. Participants described the school as “two schools in one”—one that is largely White, affluent, and high-achieving and another that is predominantly Black, economically disadvantaged, and achieving at lower levels. Educators were open to key elements of SWPBIS, such as positive discipline and school-wide consistency in disciplinary practices. And while many participants identified systemic barriers to achieving equity, they simultaneously relied on discursive strategies that upheld Whiteness. These findings suggest that SWPBIS has the potential to be an alternative to punitive school discipline, but faces multiple barriers in addressing disciplinary disproportionality. The segregated and stratified school structure raises questions about whom SWPBIS is for and who will bear the burden of implementation.

This study evaluated Social StoriesTM (SS) with three at-risk preschool children in a high- need public elementary school. Specifically, this study examined the use of a multimedia SS designed to decrease problem behavior and increase prosocial behavior. A multiple baseline design across participants with an ABC sequence was used to assess the impact of the standard SS and multimedia SS on the children's target behaviors. The results of the study indicated that the standard SS was successful in reducing problem behavior and increasing prosocial behavior for all three participating children. The results also indicated that the multimedia SS had positive effects on the children, further increasing prosocial behavior during intervention. Although the problem behavior did not further decrease when the multimedia SS was introduced, the low levels of problem behavior were maintained at a 3-week follow-up for all three children. All three children demonstrated maintenance of improved prosocial behavior during follow-up. Overall, the multimedia SS demonstrated high levels of social validity.

L'adhérence cellulaire est un processus vital impliqué dans de nombreux phénomènes biologiques fondamentaux comme la diérenciation, la réparation tissulaire ou encore le développement cellulaire. Cette thèse porte sur une étude alliant expériences et modélisation de cellules uniques en adhérence sur des supports micro-structurés Les résultats montrent que la contrainte géomé- trique imposée par les supports à contraste adhésif limite l'adhérence. Au-delà de cette limitation, une organisation reproductible du cytosquelette d'actine est observée cela suggère l'existence de lois physiques simples régissant ce processus. Nous avons développé une méthode de classication des formes géométriques élémentaires observées expérimentalement nous permettant d'obtenir des statistiques robustes. En nous basant sur le modèle de Potts Cellulaire, nous avons pu reproduire les résultats expérimentaux. Ce modèle énergétique démontre que les formes élémentaires sont des états métastables utilisés par les cellules au cours de l'adhérence. Les paramètres du modèle sont reliés aux paramètres biologiques pertinents. Nous présentons des résultats qui relient la courbure des interfaces aux paramètres biologiques. Nous montrons que la mesure expérimentale de cette courbure est une représentation de la compétition entre la contractilité des bres de stress et l'élasticité du gel d'actine. Une correspondance entre les propriétés physiques issues du modèle et les processus biochimiques régulant et organisant l'adhérence cellulaire est ainsi possible.

<p>Let $\mathbf{G}$ be a connected reductive algebraic group defined over an algebraic closure of the finite field of prime order $p>0$, which we assume to be good for $\mathbf{G}$. We denote by $F : \mathbf{G} \to \mathbf{G}$ a Frobenius endomorphism of $\mathbf{G}$ and by $G$ the corresponding $\mathbb{F}_q$-rational structure. If $\operatorname{Irr}(G)$ denotes the set of ordinary irreducible characters of $G$ then by work of Lusztig and Geck we have a well defined map $\Phi_{\mathbf{G}} : \operatorname{Irr}(G) \to \{F\text{-stable unipotent conjugacy classes of }\mathbf{G}\}$ where $\Phi_{\mathbf{G}}(\chi)$ is the unipotent support of $\chi$.</p> <p>Lusztig has given a classification of the irreducible characters of $G$ and obtained their degrees. In particular he has shown that for each $\chi \in \operatorname{Irr}(G)$ there exists an integer $n_{\chi}$ such that $n_{\chi}\cdot\chi(1)$ is a monic polynomial in $q$. Given a unipotent class $\mathcal{O}$ of $\mathbf{G}$ with representative $u \in \mathbf{G}$ we may define $A_{\mathbf{G}}(u)$ to be the finite quotient group $C_{\mathbf{G}}(u)/C_{\mathbf{G}}(u)^{\circ}$. If the centre $Z(\mathbf{G})$ is connected and $\mathbf{G}/Z(\mathbf{G})$ is simple then Lusztig and H\'zard have independently shown that for each $F$-stable unipotent class $\mathcal$ of $\mathbf$ there exists $\chi \in \operatorname(G)$ such that $\Phi_(\chi)=\mathcal$ and $n_ = |A_(u)|$, (in particular the map $\Phi_$ is surjective).</p> <p>The main result of this thesis extends this result to the case where $\mathbf$ is any simple algebraic group, (hence removing the assumption that $Z(\mathbf)$ is connected). In particular if $\mathbf$ is simple we show that for each $F$-stable unipotent class $\mathcal$ of $\mathbf$ there exists $\chi \in \operatorname(G)$ such that $\Phi_(\chi) = \mathcal$ and $n_ = |A_(u)^F|$ where $u \in \mathcal^F$ is a well-chosen representative. We then apply this result to prove, (for most simple groups), a conjecture of Kawanaka's on generalised Gelfand--Graev representations (GGGRs). Namely that the GGGRs of $G$ form a $\mathbf{Z}$-basis for the $\mathbf{Z}$-module of all unipotently supported class functions of $G$. Finally we obtain an expression for a certain fourth root of unity associated to GGGRs in the case where $\mathbf{G}$ is a symplectic or special orthogonal group.</p>

Reproduction de : Thèse de doctorat : Structure et dynamique des systèmes réactifs : Lille 1 : 2005. Reproduction de : Tesis doctoral : Química : Universidad Central de Venezuela, Facultad de Ciencias : 2005. / Thèse en cotutelle. N° d'ordre (Lille 1) : 3605. Texte en espagnol, introduction en français. Résumé en français, espagnol et anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. à la suite de chaque chapitre.

The purpose of this study was to identify school-based practices that lesbian, gay, bisexual, transgender, and questioning (LGBTQ) youth endorse as ways for high schools to provide social, emotional, and academic support to LGBTQ youth. A diverse sample of LGBTQ high school students (N = 18) from one large urban school district in a southeastern state participated in individual semi-structured interviews and/or small group brainstorming sessions. Eleven individual interviews were conducted to gather detailed accounts of a) supportive behaviors and policies that youth had experienced in their schools, as well as b) supportive behaviors and policies that were suggested as desired supports that had not actually been experienced. Participants' sentiments were coded based on the source of support (i.e., teachers, school mental health providers, administrators, policies, resources), nature of support (i.e., proactive, reactive), and social context of the support (i.e., impacting single students through one-on-one setting, impacting more than one student or groups of students). Three brainstorming sessions that included a total of 13 students were conducted to gather additional ideas from youth on ways for schools and school staff to provide support. Frequency counts of individual interview data indicated that teachers provided more experienced and desired supports than any other school-based source of support. Of the desired supports that participants had not actually experienced, Proactive Supports Impacting Groups were the most frequently described Support Type for teachers, school mental health providers, and administrators. Content Themes emerged within Support Types (e.g., Proactive Support Impacting Individuals, Reactive Support Impacting Groups) capture sentiments that were shared across multiple participants' responses. Data from interviews and brainstorming sessions were also analyzed together through a constant-comparative reduction process, resulting in 162 Specific Educator Behaviors/Policies corresponding to 8 Big Ideas of school-based supports for LGBTQ high school students: (1) Using Respectful Language and Interactions with Students; (2) Providing Comfort, Assistance, and Advice Matched to Student Needs; (3) Facilitating Connections with Community Supports; (4) Providing LGBTQ-Related Materials and Information; (5) Allowing and Supporting School-Based GSA and Pride Activities; (6) Addressing Professional Development, Human Resources, and School Culture Related Issues; (7) Implementing Policies that Address Bullying and Harassment of LGBTQ Students; and (8) Implementing Policies that Respectfully Account for Students' Diversity.) Pragmatic implications for teachers, school mental health providers, and administrators are discussed.