Vacuum fluctuations of a scalar field near a reflecting boundary and their effects on the motion of a test particle

The contribution from quantum vacuum fluctuations of a real massless scalar field to the motion of a test particle that interacts with the field in the presence of a perfectly reflecting flat boundary is here investigated. There is no quantum induced dispersions on the motion of the particle when it is alone in the empty space. However, when a reflecting wall is introduced, dispersions occur with magnitude dependent on how fast the system evolves between the two scenarios. A possible way of implementing this process would be by means of an idealized sudden switching, for which the transition occurs instantaneously. Although the sudden process is a simple and mathematically convenient idealization it brings some divergences to the results, particularly at a time corresponding to a round trip of a light signal between the particle and the wall. It is shown that the use of smooth switching functions, besides regularizing such divergences, enables us to better understand the behavior of the quantum dispersions induced on the motion of the particle. Furthermore, the action of modifying the vacuum state of the system leads to a change in the particle energy that depends on how fast the transition between these states is implemented. Possible implications of these results to the similar case of an electric charge near a perfectly conducting wall are discussed.Comment: 17 pages, 8 figure

Árvores de decisão induzidas pelo weka para alerta da ferrugem do cafeeiro em lavouras com alta carga pendente.

O objetivo deste trabalho foi desenvolver árvores de decisão com o software livre Weka para alerta da ferrugem do cafeeiro em lavouras com alta carga pendente de frutos e comparar esses modelos com as árvores de decisão induzidas por um software proprietário. Dados de incidência mensal da doença no campo coletados durante oito anos foram transformados em valores binários considerando limites de 5 e 10 pontos percentuais (p.p.) na taxa de infecção. Foi gerado um modelo para cada taxa de infecção binária, a partir de dados meteorológicos e do espaçamento entre plantas. O alerta é indicado quando a taxa de infecção, prevista para o prazo de um mês, atingir ou ultrapassar o respectivo limite. As árvores de decisão induzidas pelo Weka tiveram desempenho semelhante às induzidas pelo software proprietário. Os modelos de alerta para o limite de 5 p.p. induzidos pelas duas ferramentas são praticamente iguais. O modelo considerando o limite de 10 p.p. induzido pelo Weka é mais simples e compacto que o induzido pelo software proprietário.SBIAgro 2009

Árvores de decisão aplicadas na análise e no alerta da ferrugem do cafeeiro.

A ferrugem do cafeeiro é a principal doença da cultura do café. O conhecimento dos fatores que condicionam as epidemias de ferrugem e a sua previsão são importantes. Uma instância do processo de descoberta de conhecimento em bases de dados foi realizada para avaliar a aplicação de árvores de decisão na análise e no alerta da ferrugem. As classes do atributo meta foram definidas por intervalos da taxa de progresso da doença. Dados meteorológicos, a carga pendente de frutos e o espaçamento entre plantas serviram de atributos preditivos. As árvores de decisão obtidas auxiliaram na compreensão de quais variáveis, e como as interações dessas variáveis, conduziram a ferrugem no campo. O modelo de alerta para lavouras com alta carga pendente de frutos apresentou bom desempenho e pode ajudar na tomada de decisão referente ao controle da ferrugem do cafeeiro.bitstream/item/17768/1/cnptiabp_22-1.pd

Assessing consumer literacy on financial complex products

Consumer financial education has become an important research topic, due to the growth of a wide range of investment products available in online banking. The individuals are exposed to highly complex financial products without understanding the risk and what product is suitable for them. This study investigates and measured the financial education of individuals in complex financial products. A quiz game was developed for a bank website to measure 1597 bank clients in complex products literacy. The survey also enabled a comparison between the basic and advanced skills of financial literacy knowledge. The results highlight a satisfactory overall financial literacy level. While basic knowledge level between individuals has a higher degree, there are serious concerns in advanced skill level. This study contributes to an understanding of adults’ knowledge about the prediction of the risk of investments in complex financial products, as well as providing value to ongoing financial literacy research.info:eu-repo/semantics/acceptedVersio

Seismic behaviour characterization of reinforced concrete buildings

The seismic vulnerability assessment associated to existing reinforced concrete buildings, constructed until the late 70’s in many European countries with moderate to high seismic hazard, designed and constructed without considering adequately earthquake provisions, is of extreme importance. They constitute a significant source of risk for our cities. In this paper are presented the main results of research developed in the field of seismic assessment and retrofitting of existing RC buildings.Stanovení seismické zranitelnosti železobetonových budov postavených do konce sedmdesátých let v mnoha evropských zemích s mírným až vysokým seismickým nebezpečím, projektovaných a postavených bez přiměřených protiseismických opatření, má extrémní význam. Tyto budovy představují významný zdroj rizika pro naše města. V článku se uvádějí hlavní výsledky výzkumu na úseku stanovení seismické zranitelnosti a modernizace existujících železobetonových budov

Concrete-steel bond influence in the cyclic response of RC structural elements

Poor bond conditions are a frequent cause of damage of collapse of reinforced concrete structures under cyclic loading, such as the induced by earthquakes. Reinforced concrete elements built with smooth plain reinforcing bars are particularly sensitive to bond-slip and to its effects. A simplified numerical model to account for the bond-slip effects is proposed. A numerical analysis was performed with the objective of evaluating the bond-slip influence in the dynamic response of a reinforced concrete frame, representative of existing structures built in Europe in the 50’s~70’s with smooth plain reinforcing bars. Based on the available experimental results the proposed model was calibrated

Gamification to teach and assess financial education: a case study of self-directed bank investors

Financial education has become a popular research topic, due the growth of marketing financial services, and the wide range and complexity of investment products available online. To assess the investment risk, and decide what product is suitable for individuals, it becomes essential to use tools to improve financial education. An educational game may be a possible solution since is a serious game designed to teach adults about a specific subject and to teach them a skill. Games-based learning software are interactive play that helps to solve problems, teaches, and gives the fundamental needs of learning by providing – enjoyment and motivation. This study investigates the financial education of self-directed investors in complex financial products, and portfolio management to answer our research question – how well adult self-directed investors understand financial education about complex financial products and portfolio management – and evaluates the financial education level of self-directed bank investors in complex financial products with high risk. An online quiz game with multiple-choice questions was developed, and deployed on a bank website to assess knowledge across investment product literacy - in addition to sociodemographic characteristics – involving the participation of 1,597 self-directed adult investors. The survey also enabled a comparison between the core and advanced skills of financial education knowledge. To measure and assess the financial education, we calculate the individual score by the amount of correct answers from the three multiple answer quiz questions. The results highlight that participants have a satisfactory overall financial literacy level. While core competencies, knowledge among private investors have a higher degree of general financial education, there are particular areas in which they scored low in advanced skills (i.e., complex financial product questions). This result provides valuable insights, information for further investigation of distance education research through games, which can only continue to grow because of the increasing complexity and importance of financial education in modern societies. This study contributes to an understanding of adults’ knowledge regarding investments in complex financial products, as well as providing a valuable contribution to ongoing financial education research.info:eu-repo/semantics/acceptedVersio

Seismic behaviour and strengthening of existing reinforced concrete structures

The seismic vulnerability associated to existing reinforced concrete buildings, constructed until the late 1970’s, in urban areas of many European countries with moderate to high seismic hazard, is of extreme importance. In that period, reinforced concrete buildings were designed and constructed without considering adequately earthquake provisions, constituting therefore a significant source of risk for our cities. Recent major earthquakes around the world have evidenced that this type of existing buildings lacking appropriate seismic resisting characteristics are very vulnerable. The present paper focus in four important subjects regarding the seismic behaviour of reinforced concrete buildings, first the importance of the experimental studies on full-scale buildings in particular with two full-scale four-storey reinforced concrete frames tested, in these tests two problems were under study the presence on infill masonry panels in the structure and the use of smooth reinforcement bars, that induces a sudden loss of concrete-steel bond is one of the sources of brittle failure in RC elements. For the presence infill masonry panels it’s presented a simplified macro-model that is able of represents the global behaviour of infill masonry panels and its interaction with RC elements and its application to a case study. Regarding the study of RC buildings smooth reinforcement bars it’s presented the experimental campaign ongoing and the first results and conclusions. Another identified problem in the seismic behaviour of RC buildings is the behaviour of axially loaded reinforced concrete members under biaxial bending moment. It’s presented the actual lack of experimental studies and the nonexistence of simplified models able to represent these effects and the experimental study of RC columns under uniaxial and biaxial bending

Molecular Evaluation of exons 8 and 22 of the SHANK3 gene in Autism Spectrum Disorders

Autism spectrum disorders are a group of neurodevelopmental disorders with a complex and heterogeneous etiology. Studies have shown that genetic factors play an important role in the aetiology of these diseases. Recently, de novo mutations, frameshifts and deletions have been described in the SHANK3 gene, also known as ProSAP2 gene, which encodes a synaptic scaffolding protein. All the participants of this study had normal karyotypes and underwent screening for Fragile-X syndrome. Subsequently, they were analyzed by direct sequencing of different points of exons 8 and 22 of the SHANK3 gene. None of the study participants presented with changes in these regions. These findings may be due to the fact that mutations, deletions and duplications of the SHANK3 gene are rare