Ellipsometric measurements by use of photon pairs generated by spontaneous parametric down-conversion

We present a novel interferometric technique for performing ellipsometric measurements. This technique relies on the use of a non-classical optical source, namely, polarization-entangled twin photons generated by spontaneous parametric down-conversion from a nonlinear crystal, in conjunction with a coincidence-detection scheme. Ellipsometric measurements acquired with this scheme are absolute; i.e., they do not require source and detector calibration.Comment: 10 pages, accepted for publication in Optics Letter

Promoviendo la justicia social a través del aprendizaje-servicio en la formación de maestros de Educación Infantil

As early childhood teacher education programs have begun to place greater emphasis on standards and accountability, there has been less focus on working with the community, and especially working on important social justice issues (Kroll, 2013). In this paper we argue that integrating service-learning and teacher education is a strategy for increasing awareness of social justice issues for young children, age three to grade three. Through the use of questionnaires and interviews to collect our data, we found that implementing a cascading service-learning model in teacher education programs has a positive transformative effect on Pre-Service Teachers. Additionally, we examined the effects of social justice service-learning projects on young children. The results from the data indicated that implementing a social justice service-learning project with these participants had a great impact or transformation on them.Como en los programas de formación del profesorado para la primera infancia han empezado a poner mayor énfasis en los estándares y la rendición de cuentas, se está haciendo menos hincapié en el trabajo con la comunidad, y especialmente en trabajos centrados en temas relevantes de justicia social (Kroll, 2013). En este artículo se argumenta que la integración del aprendizaje-servicio y la formación del profesorado es una estrategia para aumentar la conciencia sobre temas de justicia social con los niños pequeños, desde los tres años hasta tercer grado. A través del uso de cuestionarios y entrevistas para la recolección de datos, se encontró que la implementación de un modelo de aprendizaje-servicio en cascada en los programas de formación del profesorado tiene un efecto transformador positivo en profesores en formación. Además, se examinaron los efectos de los proyectos de aprendizaje-servicio de justicia social con niños pequeños. Los resultados de los datos indican que la implementación de un proyecto de aprendizaje-servicio de justicia social con estos participantes tiene un gran impacto o transformación en ellos.Os programas de formação do professorado para a primeira infância começaram a pôr maior ênfase nos padrões e a prestação de contas, dando-se menos ênfase ao trabalho com a comunidade, e especialmente em trabalhos centrados em temas relevantes de justiça social (Kroll, 2013). Neste artigo se argumenta que a integração do aprendizagem-serviço e a formação do professorado é uma estratégia para aumentar a consciência sobre temas de justiça social com as crianças pequenas, desde os três anos até o terceiro grau. Através do uso de questionário e entrevistas para a coleta de dados, encontrou-se que a implementação de um modelo de aprendizagem-serviço em cascata nos programas de formação de professores tem um efeito transformador positivo em professores em formação. Ademais, examinaramse os efeitos dos projetos de aprendizagem-serviço de justiça social com crianças pequenas. Os resultados dos dados indicam que a implantação de um projeto de aprendizagem-serviço de justiça social com estes participantes causa neles um grande impacto ou transformação

A lattice model for the line tension of a sessile drop

Within a semi--infinite thre--dimensional lattice gas model describing the coexistence of two phases on a substrate, we study, by cluster expansion techniques, the free energy (line tension) associated with the contact line between the two phases and the substrate. We show that this line tension, is given at low temperature by a convergent series whose leading term is negative, and equals 0 at zero temperature

Growth, profits and technological choice: The case of the Lancashire cotton textile industry

Using Lancashire textile industry company case studies and financial records, mainly from the period just before the First World War, the processes of growth and decline are re-examined. These are considered by reference to the nature of Lancashire entrepreneurship and the impact on technological choice. Capital accumulation, associated wealth distributions and the character of Lancashire business organisation were sybiotically linked to the success of the industry before 1914. However, the legacy of that accumulation in later decades, chronic overcapacity, formed a barrier to reconstruction and enhanced the preciptious decline of a once great industry

Cracking of Bucket Lugs in Pelton Turbines a Corrosion Fatigue Phenomenon

In recent years the tendency to increased size of generating units has also led to the putting into service of Pelton turbines of increased size and power. Most of the Norwegian plants have used designs with buckets attached to the turbine disc with bolts, either three lug three bolt attachment of Norwegian design or two lug two bolt systems of foreign design. Recently, especially during the winter 1951-52 a number of fractures have occurred in buckets of very large units with two bolt type bucket attachment of foreign design. Following the adop-tion of more frequent and rigorous inspection a number of cracks have been discovered and the faulty buckets removes before serious damage occurred