Local roughness exponent in the nonlinear molecular-beam-epitaxy universality class in one-dimension

We report local roughness exponents, $\alpha_{\text{loc}}$, for three interface growth models in one dimension which are believed to belong the non-linear molecular-beam-epitaxy (nMBE) universality class represented by the Villain-Lais-Das Sarma (VLDS) stochastic equation. We applied an optimum detrended fluctuation analysis (ODFA) [Luis et al., Phys. Rev. E 95, 042801 (2017)] and compared the outcomes with standard detrending methods. We observe in all investigated models that ODFA outperforms the standard methods providing exponents in the narrow interval $\alpha_{\text{loc}}\in[0.96,0.98]$ consistent with renormalization group predictions for the VLDS equation. In particular, these exponent values are calculated for the Clarke-Vvdensky and Das Sarma-Tamborenea models characterized by very strong corrections to the scaling, for which large deviations of these values had been reported. Our results strongly support the absence of anomalous scaling in the nMBE universality class and the existence of corrections in the form $\alpha_{\text{loc}}=1-\epsilon$ of the one-loop renormalization group analysis of the VLDS equation

Stable isotopic analysis of atmospheric methane by infrared spectroscopy by use of diode laser difference-frequency generation

An infrared absorption spectrometer has been constructed to measure the stable isotopic composition of atmospheric methane samples. The spectrometer employs periodically poled lithium niobate to generate 15 μW of tunable difference-frequency radiation from two near-infrared diode lasers that probe the ν3 rotational-vibrational band of methane at 3.4 μm. To enhance the signal, methane is extracted from 25 l of air by use of a cryogenic chromatographic column and is expanded into the multipass cell for analysis. A measurement precision of 12‰ is demonstrated for both δ13C and δD

Vozes sociais, educação do campo e projetos de vida: Uma análise dialógica sobre as práticas no SERTA (Serviço de Tecnologia Alternativa)

ABSTRACT. The main objective of this article is to understand the educational practices of Alternative Technology Service (SERTA), through the contributions of the Educational Support Program for Sustainable Development (PEADS) for the construction of students' Life Projects. Based on the Dialogic Discourse Analysis (DDA) of the Bakhtinian circle, it is intended to analyze, in what way and to what extent, the social voices that permeate the experienced activities are perceived in the statements of the subjects that permeate this educational space and contribute to your Life Projects. The results point to the PEADS methodology and Pedagogy of Alternation experienced in SERTA, as possibilities for individual and collective growth and contribute to the protagonism of the subjects, the awakening of the feeling of belonging to a social group, the motivation to learn, research and share the diverse knowledge that is learned in the course, either during the moments of immersion of school time (ST), or in the activities of community time (CT), by providing the opportunity for individual and collective listening and appreciation of the subjects throughout the entire educational process experienced in the Technical Course in Agroecology.ABSTRACT. The main objective of this article is to understand the educational practices of Alternative Technology Service (SERTA), through the contributions of the Educational Support Program for Sustainable Development (PEADS) for the construction of students' Life Projects. Based on the Dialogic Discourse Analysis (DDA) of the Bakhtinian circle, it is intended to analyze, in what way and to what extent, the social voices that permeate the experienced activities are perceived in the statements of the subjects that permeate this educational space and contribute to your Life Projects. The results point to the PEADS methodology and Pedagogy of Alternation experienced in SERTA, as possibilities for individual and collective growth and contribute to the protagonism of the subjects, the awakening of the feeling of belonging to a social group, the motivation to learn, research and share the diverse knowledge that is learned in the course, either during the moments of immersion of school time (ST), or in the activities of community time (CT), by providing the opportunity for individual and collective listening and appreciation of the subjects throughout the entire educational process experienced in the Technical Course in Agroecology.RESUMEN. El principal objetivo de este artículo es comprender las prácticas educativas de Servicio de Tecnología Alternativa (SERTA), a través de aportes del Programa Educativo de Apoyo al Desarrollo Sostenible (HDPE) para la construcción de Proyectos de Vida de los estudiantes. Basado en el análisis del discurso dialógico (ADD) del círculo bakhtiniano, se pretende analizar, de qué manera y en qué proporción, las voces sociales que impregnan las actividades vividas, se perciben en los enunciados de los sujetos que permean este espacio educativo y aportan a sus Proyectos de Vida. Los resultados apuntan a la metodología HDPE y Pedagogía de la Alternación vivida en SERTA, como posibilidades de crecimiento individual y colectivo y contribuyen al protagonismo de los sujetos, el despertar del sentimiento de pertenencia a un grupo social, la motivación para aprender, investigar y compartir el conocimientos diversos que se aprenden en el curso, ya sea durante los momentos de inmersión (TE), o en las actividades de Tempo Comunidad (TC), brindando la oportunidad de escucha y apreciación individual y colectiva de las materias a lo largo de todo el proceso educativo vivido desde el inicio de la primera semana de inmersión en el Curso Técnico en Agroecología.ABSTRACT. The main objective of this article is to understand the educational practices of Alternative Technology Service (SERTA), through the contributions of the Educational Support Program for Sustainable Development (PEADS) for the construction of students' Life Projects. Based on the Dialogic Discourse Analysis (DDA) of the Bakhtinian circle, it is intended to analyze, in what way and to what extent, the social voices that permeate the experienced activities are perceived in the statements of the subjects that permeate this educational space and contribute to your Life Projects. The results point to the PEADS methodology and Pedagogy of Alternation experienced in SERTA, as possibilities for individual and collective growth and contribute to the protagonism of the subjects, the awakening of the feeling of belonging to a social group, the motivation to learn, research and share the diverse knowledge that is learned in the course, either during the moments of immersion of school time (ST), or in the activities of community time (CT), by providing the opportunity for individual and collective listening and appreciation of the subjects throughout the entire educational process experienced in the Technical Course in Agroecology.O presente artigo tem como objetivo central compreender aspectos das práticas educativas do Serviço de Tecnologia Alternativa (SERTA), em Pernambuco, como contribuições de sua metodologia, ancorada no Programa Educacional de Apoio ao Desenvolvimento Sustentável (PEADS), para a construção dos Projetos de Vida dos estudantes. Com base na Análise Dialógica do Discurso (ADD) do círculo bakhtiniano, pretendeu-se analisar de que maneira, e em que proporção, as vozes sociais que perpassam as atividades vivenciadas aparecem nos enunciados dos sujeitos, neste espaço educativo, e contribuem para os seus projetos de vida. Os resultados apontaram para a metodologia PEADS e a Pedagogia da Alternância como possibilidades de crescimento individual e coletivo, contribuindo para o protagonismo dos sujeitos, o despertar do sentimento de pertencimento a um grupo social, a motivação para aprender, pesquisar e compartilhar saberes diversos apreendidos no Curso Técnico em Agroecologia, seja nos momentos de imersão no Tempo Escola (TE), seja nas atividades do Tempo Comunidade (TC). O curso proporcionou oportunidades de escuta, fala e valorização individual e coletiva dos sujeitos, ao longo do processo educativo vivenciado. Palavras-chave: educação do campo, projetos de vida, SERTA.   Social voices, rural education and life projects: A dialogical analysis of practices at SERTA (Alternative Technology Service) ABSTRACT. The main objective of this article is to understand the educational practices of Alternative Technology Service (SERTA), through the contributions of the Educational Support Program for Sustainable Development (PEADS) for the construction of students' Life Projects. Based on the Dialogic Discourse Analysis (DDA) of the Bakhtinian circle, it is intended to analyze, in what way and to what extent, the social voices that permeate the experienced activities are perceived in the statements of the subjects that permeate this educational space and contribute to your Life Projects. The results point to the PEADS methodology and Pedagogy of Alternation experienced in SERTA, as possibilities for individual and collective growth and contribute to the protagonism of the subjects, the awakening of the feeling of belonging to a social group, the motivation to learn, research and share the diverse knowledge that is learned in the course, either during the moments of immersion of school time (ST), or in the activities of community time (CT), by providing the opportunity for individual and collective listening and appreciation of the subjects throughout the entire educational process experienced in the Technical Course in Agroecology. Keywords:  rural education, life projects, SERTA.   Voces sociales, educación rural y proyectos de vida: un análisis dialógico de las prácticas en SERTA (Servicio de Tecnología Alternativa) RESUMEN. El principal objetivo de este artículo es comprender las prácticas educativas de Servicio de Tecnología Alternativa (SERTA), a través de aportes del Programa Educativo de Apoyo al Desarrollo Sostenible (HDPE) para la construcción de Proyectos de Vida de los estudiantes. Basado en el análisis del discurso dialógico (ADD) del círculo bakhtiniano, se pretende analizar, de qué manera y en qué proporción, las voces sociales que impregnan las actividades vividas, se perciben en los enunciados de los sujetos que permean este espacio educativo y aportan a sus Proyectos de Vida. Los resultados apuntan a la metodología HDPE y Pedagogía de la Alternación vivida en SERTA, como posibilidades de crecimiento individual y colectivo y contribuyen al protagonismo de los sujetos, el despertar del sentimiento de pertenencia a un grupo social, la motivación para aprender, investigar y compartir el conocimientos diversos que se aprenden en el curso, ya sea durante los momentos de inmersión (TE), o en las actividades de Tempo Comunidad (TC), brindando la oportunidad de escucha y apreciación individual y colectiva de las materias a lo largo de todo el proceso educativo vivido desde el inicio de la primera semana de inmersión en el Curso Técnico en Agroecología. Palabras clave: educación rural, proyectos de vida, SERTA

Momentum strategies using option-implied correlations

Em geral, o perfil risco-retorno da estratégia de momentum é como uma ‘faca’ de dois gumes. Por um lado, a estratégia oferece elevados retornos ajustados ao risco que superam os proporcionados pelas estratégias assentes nos fatores de mercado, value ou size. Mas, por outro lado, este notável desempenho é condicionado por uma elevada exposição ao risco de ‘crash’. i.e., risco de perdas muito elevadas apesar de pouco frequentes. Nesta dissertação pretendemos otimizar a implementação de uma estratégia de momentum no mercado acionista americano (NYSE, NASDAQ e AMEX). Para o efeito utilizamos, pela primeira vez na literatura, informação implícita nos preços de opções sobre um índice acionista de referência (S&P500) acerca da correlação esperada de retornos dos constituintes desse índice. Concluímos que utilizando a média móvel de 2 meses de uma proxy da estrutura temporal dessas expectativas para ajustar a exposição ao fator momentum, é possível melhorar significativamente o desempenho do momentum. Denominamos esta estratégia como Dinâmica. Esta estratégia melhora o potencial de ganho do momentum, mas mantém uma elevada exposição ao risco de ‘crash’ do momentum. Para ultrapassar este facto, propomos uma estratégia alternativa, que denominamos de Híbrida, a qual combina a estratégia Dinâmica com a estratégia ‘Risk-managed’, proposta por Barroso e Santa-Clara (2015). A estratégia Híbrida pode ser implementada em tempo real (i.e., apenas utiliza informação disponível até ao momento presente), apresenta retornos com ‘skewness’ positiva, e um ‘Sharpe ratio’ que mais do que triplica face ao da estratégia simples de momentum.Generically, the risk-return profile of momentum strategies is a double-edged sword. On one hand, the strategy offers very attractive risk-adjusted returns, frequently outperforming those of strategies based on the market, value, or size factors. However, momentum strategies are highly exposed to the ‘crash’ risk, i.e., severe downside risk in rare occasions. In this dissertation, we aim to improve the implementation of a momentum strategy in the U.S. equity market (NYSE, NASDAQ and AMEX). With that purpose, and for the first time in the literature, we make use of information on the S&P500 index option-implied correlation of the index constituents returns. We conclude that by using the 2-month moving average of a proxy for the term structure of expected correlations across the S&P500 index constituents, implied in their option prices, it is possible to improve significantly the performance of momentum strategies. We denominate this strategy as Dynamic momentum strategy. It optimises the exposure to the upside potential of the momentum factor but continues to be exposed to the momentum’s crash risk. In order to manage this risk exposure, we propose another momentum strategy which we denominate by Hybrid momentum strategy, which combines the Dynamic momentum strategy and the Risk-managed momentum strategy, as proposed by Barroso and Santa-Clara (2015). This Hybrid momentum strategy can be implemented on real-time (i.e. only uses information available to the trader), generating returns with positive skewness and a Sharpe ratio that more than triples versus that of the plain-vanilla momentum strategy

Evaluation of the quality of resin/dentin bonds obtained by using techniques/materiais that intent to minimize the effect of dentin wetness on the longevity of adhesive restorations

Orientador: Marcela Rocha de Oliveira CarrilhoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo geral desta pesquisa foi avaliar materiais e procedimentos empreendidos para incrementar a durabilidade das restaurações adesivas. Os objetivos específicos foram: 1) avaliar o efeito da aplicação de uma camada adicional de adesivo e de um agente de união com característica hidrofóbica e livre de solventes na permeabilidade da dentina hibridizada com adesivos convencionais de 2 passos; 2) avaliar os efeitos decorrentes da aplicação do oxalato de potássio na durabilidade da interface de união obtida com adesivos convencionais e 3) determinar se a aplicação prévia do oxalato de potássio na dentina condicionada interfere na dureza Knoop dos adesivos. No primeiro estudo, a permeabilidade dentinária foi mensurada utilizando-se um medidor automático de fluxo, antes e após a aplicação dos sistemas adesivos nas condições experimentais citadas. Os resultados mostraram que nenhum dos adesivos foi capaz de prevenir a passagem de fluidos através da sua estrutura polimerizada. Porém, a aplicação de uma camada de um agente de união hidrofobico e livre de solventes reduziu significantemente a permeabilidade da dentina hibridizada com adesivos convencionais de 2 passos. Já no segundo estudo, testes de resistência adesiva (RA) foram realizados 24 horas após o procedimento adesivo ou após 12 meses de armazenagem em água. Os espécimes foram preparados para observação em microscopia eletrônica de varredura para avaliação do modo de fratura. Os resultados mostraram que a associação do oxalato de potássio aos sistemas adesivos reduziu significantemente a RA dos mesmos. Após o período de armazenagem, a RA foi significantemente reduzida em todos os grupos. No entanto, esta queda foi significantemente menor para os grupos tratados com oxalato. Finalmente, no terceiro estudo, testes de dureza foram realizados em microdurômetro e expressos como dureza Knoop (KHN). Os resultados mostraram que a associação do oxalato de potássio aos sistemas adesivos convencionais reduziu a KHN inicial dos mesmos.Abstract: The general aim of this study was to evaluate materials and techniques that are thought to increase the longevity of adhesive restorations. The specific aims of this study were: 1) to test whether the application of an extra layer of the respective adhesive or the application of a hydrophobic, non-solvated bonding agent would interfere on the permeability of dentin hybridized with two-step etch-and-rinse adhesives; 2) to test whether the pretreatment of acid-etched dentin with potassium oxalate gel has an effect on the durability of resin-dentin interface created with etch-and-rinse adhesives; and 3) to determine whether the hardness of etch-and-rinse adhesives is affected by the pretreatment of acid-etched dentin with potassium oxalate gel. In the first study, dentin permeability was measured with an automatic record device, before and after dentin surfaces were bonded with the adhesives in the cited experimental conditions. The results showed that none of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin; however, the application of the hydrophobic nonsolvated bonding agent resulted in significant reductions in the fluid flow rate. In the second study, the resin-dentin bond strength of the adhesives was tested immediately (i.e. 24 hours) and after 12 months of storage. The results showed that the pretreatment of dentin with potassium oxalate affect negatively the baseline resin-dentin bond strength of dentin specimens. After storage, the bond strength of resin-bonded interfaces was significantly reduced for all tested groups. Nevertheless, the decrease in bond strength values was significantly lower for oxalate-treated specimens than for controls. Finally, in the third study, the specimens' hardness was determined with a hardness tester and express as Knoop Hardness (KHN). The results showed that the baseline KHN of the adhesives applied to acid-etched dentin pretreated with potassium oxalate was significantly lower than that exhibited by their respective controls.DoutoradoMateriais DentariosDoutor em Materiais Dentário

Teleparallel Equivalent of Non-Abelian Kaluza-Klein Theory

Based on the equivalence between a gauge theory for the translation group and general relativity, a teleparallel version of the non-abelian Kaluza-Klein theory is constructed. In this theory, only the fiber-space turns out to be higher-dimensional, spacetime being kept always four-dimensional. The resulting model is a gauge theory that unifies, in the Kaluza-Klein sense, gravitational and gauge fields. In contrast to the ordinary Kaluza-Klein models, this theory defines a natural length-scale for the compact sub-manifold of the fiber space, which is shown to be of the order of the Planck length.Comment: Revtex4, 7 pages, no figures, to appear in Phys. Rev.

Online tracking of a drifting parameter of a time series

We propose an online algorithm for tracking a multivariate time-varying parameter of a time series. The algorithm is driven by a gain function. Under assumptions on the gain function, we derive uniform error bounds on the tracking algorithm in terms of chosen step size for the algorithm and on the variation of the parameter of interest. We give examples of a number of different variational setups for the parameter where our result can be applied, and we also outline how appropriate gain functions can be constructed. We treat in some detail the tracking of time varying parameters of an AR($d$) model as a particular application of our method