A Coupled Equations Model for Epitaxial Growth on Textured Surfaces

We have developed a continuum model that explains the complex surface shapes observed in epitaxial regrowth on micron scale gratings. This model describes the dependence of the surface morphology on film thickness and growth temperature in terms of a few simple atomic scale processes including adatom diffusion, step-edge attachment and detachment, and a net downhill migration of surface adatoms. The continuum model reduces to the linear part of the Kardar-Parisi-Zhang equation with a flux dependent smoothing coefficient in the long wavelength limit.Comment: 11 pages, 4 figures. Submitted to the Journal of Crystal Growt

The motion of a ball moving down a circular path

The problem of a body slipping down a frictionless hemisphere is very common in physics and engineering textbooks. In this type of problem, students are normally asked to find the angle at which the body flies off the surface. In this work, we have constructed an apparatus to determine the angle at which a ball flies off a circular track, and to study the motion of the ball (rolling and slipping) along the surface. The apparatus is comprised of two parallel rails that form a quarter circle. The angular position and velocity of a steel ball are measured using a moveable arm equipped with a photodetector. Two methods are used to determine the angle the ball loses contact with the track. Both methods provide values in agreement with a model for rolling followed by slipping. (C) 2017 American Association of Physics Teachers.The problem of a body slipping down a frictionless hemisphere is very common in physics and engineering textbooks. In this type of problem, students are normally asked to find the angle at which the body flies off the surface. In this work, we have constr852124129sem informaçãosem informaçã

Entanglement and the nonlinear elastic behavior of forests of coiled carbon nanotubes

Helical or coiled nanostructures have been object of intense experimental and theoretical studies due to their special electronic and mechanical properties. Recently, it was experimentally reported that the dynamical response of foamlike forest of coiled carbon nanotubes under mechanical impact exhibits a nonlinear, non-Hertzian behavior, with no trace of plastic deformation. The physical origin of this unusual behavior is not yet fully understood. In this work, based on analytical models, we show that the entanglement among neighboring coils in the superior part of the forest surface must be taken into account for a full description of the strongly nonlinear behavior of the impact response of a drop-ball onto a forest of coiled carbon nanotubes.Comment: 4 pages, 3 figure

Prediction of giant electroactuation for papyruslike carbon nanoscroll structures: First-principles calculations

We study by first-principles calculations the electromechanical response of carbon nanoscroll structures. We show that although they present a very similar behavior to carbon nanotubes in their axial deformation sensitivity, they exhibit a radial response upon charge injection which is up to one order of magnitude larger. In association with their high stability, this behavior makes them a natural choice for a new class of very efficient nanoactuators.74

Cross-cultural adaptation and validation of the "Work related activities that may contribute to job-related pain and/or injury" to Brazilian-Portuguese language

Orientador: Neusa Maria Costa AlexandreDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias MedicasResumo: As desordens osteomusculares são as maiores causas de incapacidade e de ausência ao trabalho em muitos grupos ocupacionais e podem ser causadas por fatores ergonômicos relacionados ao trabalho. Questionários e escalas têm sido considerados como importantes estratégias para identificar esses fatores, possibilitando avaliar a efetividade de intervenções ergonômicas e prevenir sintomas osteomusculares. Porém, existe uma necessidade desses instrumentos voltados para a população brasileira. O objetivo desta pesquisa foi produzir uma versão traduzida e adaptada do questionário "Work-related activities that may contribute to job-related pain and/or injury", avaliar suas propriedades psicométricas e verificar sua praticabilidade. A adaptação cultural foi realizada de acordo com metodologias internacionalmente recomendadas, seguindo as etapas de tradução, síntese, retro-tradução, revisão por um comitê de especialistas e pré-teste. O questionário foi traduzido independentemente por dois tradutores, cuja língua materna era o português. Após, dois tradutores, que possuíam como língua nativa o inglês, realizaram as retro-traduções. Um comitê multidisciplinar composto por seis especialistas revisou e comparou as traduções, desenvolvendo uma versão final para aplicação no pré-teste. O pré-teste foi realizado com 40 trabalhadores. As propriedades psicométricas foram avaliadas por meio da administração do questionário para 148 trabalhadores de indústrias metalúrgicas. A confiabilidade foi verificada por meio da estabilidade teste-reteste. A validade de constructo foi avaliada utilizando a técnica dos grupos conhecidos, aplicando o questionário em trabalhadores das áreas de produção e administrativa. A validade também foi verificada comparando as respostas dos trabalhadores com os achados obtidos com os escores do Questionário Nórdico. A praticabilidade do instrumento foi verificada considerando-se o tempo e a facilidade de resposta em uma escala tipo Likert de cinco pontos. A confiabilidade foi obtida pelo procedimento de teste-reteste em um intervalo de sete dias, utilizando o Coeficiente de Correlação Intraclasse (CCI) em 142 trabalhadores. Os valores de CCI foram calculados para cada uma das 15 questões do questionário. Os valores CCI demonstraram uma boa concordância para 11 itens do instrumento, com valores variando de 0,61 a 0,73. Somente quatro itens apresentaram um CCI abaixo de 0,60 (0,54 - 0,58), indicando uma concordância moderada. Os valores mais altos encontrados eram os relacionados a trabalho estático (0,73), posições desconfortáveis (0,71), carregamento de materiais e equipamentos pesados (0,71), utilização de objetos pequenos (0,69), repetitividade (0,63) e trabalhar apresentando algum tipo de sintoma (0,63). Considerando a validade de constructo, houve uma diferença significativa (p < 0,02) entre as respostas dos dois grupos de trabalhadores em dez questões do questionário. O teste de validade demonstrou uma diferença significativa (p < 0,01) nos valores de cada item do questionário sobre percepção de fatores do trabalho que poderiam contribuir para o desenvolvimento de dor e/ou lesão entre os sujeitos que indicaram a presença de sintomas e aqueles que revelaram ausência deles, de acordo com o Questionário Nórdico. O instrumento mostrou-se fácil e de rápida aplicabilidade. Os resultados indicaram que o processo de adaptação cultural foi realizado com sucesso e a versão adaptada do questionário demonstrou possuir propriedades psicométricas adequadas, tornando-se confiável para ser aplicado na cultura brasileira.Abstract: Musculoskeletal disorders are the most important causes of work disability and absenteeism in many occupational groups and can be caused by work- related ergonomic factors. Questionnaires and scales have been considered as important strategies to identify these factors, allowing the evaluation of the effectiveness of ergonomic interventions and the prevention of musculoskeletal symptoms. However, these instruments should be adapted to meet the Brazilian population needs. The objective of the present research was to produce a translated and adapted version of the questionnaire "Work-related activities that may contribute to job-related pain and/or injury", to evaluate their psychometric properties and to verify its practicability. The cross-cultural adaptation was performed according to the internationally recommended methodology, using the following guidelines: translation, synthesis, back-translation, revision by an expert committee, and pretest. The questionnaire was independently translated by two bilingual translators, who had Portuguese as their mother tongue. Then, two other translators whose native language was English did the back-translation. A multidisciplinary committee composed of six experts revised and compared the translations, developing the final version for pretest application. The pretest was carried out with 40 workers. The psychometric properties were evaluated by administering the questionnaire to 148 employees of metallurgical industries. Reliability was found by assessing the test-retest stability. The construct validity was tested using the known-groups technique, administering the questionnaire to workers of the production and administrative areas. The validity was also established by comparing the workers' responses with findings from the Nordic Questionnaire scores. The instrument usability was verified considering the time and the easiness in answering through a five-point Likert scale. Reliability was assessed by a test-retest procedure at 7-day intervals, using the Intraclass Correlation Coefficient (ICC) in 142 workers. The ICC values were calculated for each one of the 15 questions of the questionnaire. The ICC values demonstrated a good agreement for 11 items of the instrument, with the ICC values ranging from 0.61 to 0.73. Only four items presented an ICC lower than 0.60 (0.54 - 0.58), indicating a moderate agreement. The greatest values found were related to static work (0.73), awkward positions (0.71), carrying heavy materials and equipments (0.71), using small objects (0.69), repetitiveness (0.63), and work presenting any kind of symptom (0.63). Concerning the construct validity, there was a significant difference (p < 0.02) between the answers of the two groups of employees in 10 questions of the questionnaire. The validity test showed a significant difference (p < 0.01) on the scores of each item of the employees' perceptions, when evaluating the 15 different job factors and their potential contribution to musculoskeletal disorders, between subjects who indicated the presence of symptoms and those who revealed absence of them, according to the Nordic Questionnaire. The instrument showed easy and fast applicability. The data showed that the cross-cultural adaptation process was successful, and the adapted version of the questionnaire demonstrated to have adequate psychometric properties, making it reliable to be applied to Brazilian culture.MestradoEnfermagem e TrabalhoMestre em Enfermage

Designing Conducting Polymers Using Bioinspired Ant Algorithms

Ant algorithms are inspired in real ants and the main idea is to create virtual ants that travel into the space of possible solution depositing virtual pheromone proportional to how good a specific solution is. This creates a autocatalytic (positive feedback) process that can be used to generate automatic solutions to very difficult problems. In the present work we show that these algorithms can be used coupled to tight-binding hamiltonians to design conducting polymers with pre-specified properties. The methodology is completely general and can be used for a large number of optimization problems in materials science

The Pain Disability Questionnaire: estudio de confiabilidad y validación

The goal of this study was to translate and adapt The Pain Disability Questionnaire (PDQ) to Brazilian Portuguese, as well as to assess its psychometric properties and practicability. The following methodological steps were followed: translation, synthesis, back-translation, expert committee assessment and pre-test. The psychometric properties were assessed through the application of a questionnaire to 119 patients with chronic musculoskeletal disorders. The results indicated the reliability of the instrument, with a Cronbach's alpha coefficient of 0.86, and high stability in the test-retest. A moderate correlation was found between the PDQ scores and the numerical pain scale. Negative correlations were found between the Spitzer Quality of Life Index and the functional condition, psychosocial component and total PDQ score. Construct validity demonstrated significant difference in PDQ scores between symptomatic and asymptomatic individuals. The PDQ revealed fast application and easy understanding. The results indicated a successful cultural adaptation and reliable psychometric properties.O objetivo deste estudo foi traduzir e adaptar The Pain Disability Questionnaire (PDQ) para o português do Brasil, avaliar suas propriedades psicométricas e praticabilidade. Os seguintes passos metodológicos foram seguidos: tradução, síntese, retrotradução, avaliação por comitê de especialistas e pré-teste. As propriedades psicométricas foram avaliadas pela aplicação do questionário a 119 pacientes com lesões musculoesqueléticas crônicas. Os resultados indicaram a confiabilidade do instrumento com o coeficiente alfa de Cronbach de 0,86, e alta estabilidade na aplicação do teste-reteste. Uma correlação moderada foi encontrada entre os escores do PDQ e a escala numérica de dor. Correlações negativas foram encontradas entre o Spitzer Quality of Life Index e a condição funcional, componente psicossocial e escore total do PDQ. A validade de construto demonstrou diferença significativa nos escores do PDQ entre indivíduos sintomáticos e assintomáticos. O PDQ mostrou aplicação rápida e fácil entendimento. Os resultados indicaram sucesso na adaptação cultural e propriedades psicométricas confiáveis.El objetivo de este estudio fue traducir y adaptar el Cuestionario The Pain Disability Questionnaire (PDQ) para el portugués de Brasil, evaluando sus propiedades psicométricas y la usabilidad. Fueron seguidos los siguientes pasos metodológicos: traducción, síntesis, retrotraducción, evaluación por un comité de expertos y realización de una prueba piloto. Las propiedades psicométricas fueron evaluadas por la aplicación del cuestionario en 119 pacientes con lesiones musculares. Los resultados indican la confiabilidad del instrumento con el coeficiente alfa de Cronbach de 0,86, y alta estabilidad en la prueba piloto. Una correlación moderada se encontró entre las puntuaciones de la PDQ y la escala numérica del dolor. Correlaciones negativas fueron observadas entre el Spitzer Quality of Life Index y la condición funcional, el componente psicosocial, y la puntuación total de la PDQ. La validez del constructo demostró una diferencia significativa en las puntuaciones del PDQ entre sujetos sintomáticos y asintomáticos. El PDQ demostró ser rápido y comprensible. Los resultados indicaron una exitosa adaptación cultural y propiedades psicométricas confiables.768