Domain wall description of superconductivity

In the present work we shall address the issue of electrical conductivity in superconductors in the perspective of superconducting domain wall solutions in the realm of field theory. We take our set up made out of a dynamical complex scalar field coupled to gauge field to be responsible for superconductivity and an extra scalar real field that plays the role of superconducting domain walls. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath.Comment: 9 pages, 5 figures, Latex. Version to appear in PL

Why did people pay taxes? Fiscal innovation in Portugal and state making in times of political struggle (1500-1680)

This paper considers growing fiscal capacity of the European early modern states as contingent to taxpayer’s consent in higher tax loads. It puts forward the hypothesis that war damages were the main factor guiding the taxpayer’s cost-benefit assessment of consenting or violently resisting to a fiscal innovation. To test the hypotheses, we consider data on Portugal in times of political struggle against the Habsburgs to restore and keep the political autonomy after 1640. The war was financed by an entirely new, universal income tax, remaining in the Portuguese fiscal system well until the liberal revolution in 1820, although enforced by a decentralized and nonspecialized administration. A model derives the optimal tax rate from the standpoint of the taxpayer as a function of war intensity, risk aversion, and awareness that evasion would enhance war damages. Data on damages, contemporary assessments of the tax base, and amounts enforced allow the model’s calibration. Results suggest the accuracy of the hypothesis and draw the conclusion that taxpayers’ utility in paying the new tax determined the efective tax rate (tax enforced). This paper claims that ultimately improvements in the fiscal capacity of states needed taxpayer’s perception of high levels of destruction, hence any political regime in early modern Europe must have found in war damages a persuasive argument to make efective a fiscal innovation. The other contribution of this case study is pointing out the advantage of the assignment of the tax collection to local, non-professional administration, for the endurance of a fiscal system, which incorporated an income tax that withstood the liberal revolution. It enhanced the role of peer monitoring and turned out to be an efective way of instilling social norms contributing to build up the taxpayer’s liability, which somehow the liberal state in 19th century exploited within a different technological environment.info:eu-repo/semantics/publishedVersio

The alchemy of gold : interest rates, money stock, and credit in eighteenth-century Lisbon

This article addresses the partial equilibrium functioning of the short-term credit market in eighteenth-century Lisbon and its response to massive gold inflows from Brazil. Gold inflows were a colonial rent, and thus a source of income and a financial asset that increased the liquidity supply in a credit market populated by both (direct) participants and non-participants in the colonial trade or in mining. As a source of income it would induce a positive upward pressure on interest rates, while as a financial asset it would lead to the opposite. A method is developed to extract interest rates from notarized personal credit, unbundling the aggregate and the idiosyncratic components of risk pricing. The results show that interest rates in Lisbon did not differ critically from those observed in other cities at the core of the premodern European economy, which were spared from devastation by the earthquake that struck Lisbon in 1755. A simple model relating the market interest rate series to gold stock variations finds that the liquidity channel dominated over the endowment channel, which explains the downward trend in interest rates up until 1757 when the interest rates were freely settled. Mild credit rationing may have been introduced by a 5 per cent ceiling on interest rates that was imposed after 1757.info:eu-repo/semantics/publishedVersio

Notarial activity and credit demand in Lisbon during the eighteenth-century

The long-term financial effects of increased liquidity in the Portuguese economy in the 18th century are the subject of an ongoing study on the private credit market in Lisbon. The research project focuses interest rates variations and the 1755 earthquake’s impacts, integrating these topics into a broader approach on the Portuguese economy in a time when colonial Brazil contributed to gold money inflows. This article presents the methodological procedures followed to build up a representative sample of short-term loans that form the database for this project and describes the first results of the study considering the uses of credit. First results assure the minor role played by investment, whereas the main use of loans was personal credit for consumption. An extremely large proportion of this category, however, referred to contracts for the acquisition of durable goods (including the building of urban properties). The importance of rollover and restructuring of debts is the unanticipated information these short-term loans provided, and the earthquake did not show up as affecting particularly this feature of the structure of credit. The destruction of capital nevertheless accounted for the need of building and improving residential capital, and for that reason organisational investment to rebuild urban stores and rural equipment reached some representativeness among the overall uses of credit between 1756 and 1780

Money supply and the credit market in early modern economies : the case of eighteenth-century Lisbon

In this paper, we address the partial equilibrium functioning of the shortterm credit market in the Eighteenth-century Lisbon and its response to three major events: massive gold inflows from Brazil, a catastrophic destruction of capital caused by the 1755 earthquake and the enactment of a 5% legal ceiling on interest rates 1757. We build a time series for the market interest rate, and a regression shows money stock and real estates as two significant variables. Interest rates were affected negatively by the former and positively by the latter. We conclude that changes in the money stock tended to operate through the supply of loanable funds. The wealth effect, measured by the stock of real estate, operated over demand and tended to be the most significant effect among several other possible countervailing effects (e.g., the impact of wealth effects on supply, the informational effects of collaterals). The inflow of gold clearly generated a liquidity which by itself explained the downward trend in interest rates up until around 1780. However, the huge variations experienced by the stock of capital after the earthquake also explains the steadiness of interest rates in a period when the inflow of money started to recede. For the whole period during which the 5 % ceiling on interest rates was in force we do not find any evidence to confirm the existence of disequilibrium credit rationing: the notional interest rate predicted by our model was very close to the 5% legal ceiling

Confining potential in a color dielectric medium with parallel domain walls

We study quark confinement in a system of two parallel domain walls interpolating different color dielectric media. We use the phenomenological approach in which the confinement of quarks appears considering the QCD vacuum as a color dielectric medium. We explore this phenomenon in QCD_2, where the confinement of the color flux between the domain walls manifests, in a scenario where two 0-branes (representing external quark and antiquark) are connected by a QCD string. We obtain solutions of the equations of motion via first-order differential equations. We find a new color confining potential that increases monotonically with the distance between the domain walls.Comment: RevTex4, 5 pages, 1 figure; version to appear in Int. J. Mod. Phys.

Propuesta estratégica para el cultivo de uva en la cuenca baja del río Guayas

PROYECTO QUE CONSISTE EN ESTABLECER QUE EL CULTIVO DE UVA REPRESENTA UNA ALTERNATIVA COMPETITIVA EN EL MERCADO LOCAL CON POSIBILIDADES DE EXPORTACION Y GENERACION DE DIVISAS PARA EL PAIS. PARA DETERMINAR EL BENEFICIO FINANCIERO SE REALIZA UN ANALISIS DE LA TASA INTERNA DE RETORNO (TIRF) . ADEMAS ESTABLECE EL BENEFICIO SOCIAL DEL PROYECTO DETERMINANDO EL EFECTO QUE ESTE TENDRA SOBRE EL BIENESTAR DE LA SOCIEDAD, CUANDO EL BAJO COSTO DEL PRODUCTO SEA ACCESIBLE PARA LA CLASE DE ESCASOS RECURSOS ECONOMICOS. DETERMINA EL POSIBLE IMPACO AMBIENTAL QUE PODRIA GENERAR EL PROYECTO DE CUTIVO DE VIÑEDOS EN EL ZONA Y DESARROLLA UN PLAN DE MANEJO AMBIENTAL EN CASO DE EXISTIR EFECTOS NEGATIVOS

O lugar da cultura visual nas práticas artísticas do 1º ciclo do ensino básico em Portugal

Dissertação de Mestrado em Educação Artística apresentada na Escola Superior de Educação do Instituto Politécnico de Viana do CasteloEsta investigação centra-se na análise de actividades e estratégias relacionadas com leitura de imagens na área de Expressão Plástica, numa Escola Básica de 1.º Ciclo. Para tal optou-se pela abordagem qualitativa, nomeadamente o método de estudo de caso, onde colaborou uma professora generalista e dezasseis alunos do 1.º e 2.º ano, com idades entre 6/8 anos. A revisão de literatura de algumas teorias nacionais e internacionais relacionadas com o conceito de Cultura Visual, concepções de educação artística e formação de professores, permitiu o aprofundamento de conhecimentos que serviram de fundamentação teórica ao presente estudo. A observação in loco, assim como a análise de trabalhos das crianças, comentários da professora, reflexões da investigadora, fotografias dos espaços e actividades, serviram de base à recolha de dados deste estudo. Como resultados mais pertinentes salienta-se: a constatação da pouca valorização de uma educação para a cultura visual; a incapacidade das crianças e da professora de lerem as imagens que os rodeiam no seu quotidiano; o comprometimento de uma aprendizagem adequada, causada pela ausência de estratégias de alfabetização visual; o desconhecimento de estratégias e recursos adequados ao uso da imagem; necessidade de uma formação contínua de professores generalistas com a colaboração de professores especialistas no 1.º Ciclo do Ensino Básico como solução viável e prevista na lei; a constatação da interacção salutar entre alunos e professora; o entusiasmo com que os alunos realizam as suas actividades artísticas; o facto dos professores generalistas „verem‟ a Expressão Plástica como uma excelente ferramenta para reforçar a aprendizagem noutras áreas de conhecimento, ou como forma de promover o desenvolvimento pessoal e social das crianças. Outros estudos poderão ser realizados a partir destes dados preciosos, que merecem a maior atenção, sobretudo por parte de todos aqueles que têm responsabilidades na educação das crianças.This investigation is based on the analysis of activities and strategies related with the reading of images in Art Expression, in a Primary School. For that we had a qualitative approach, especially on the case study, where a teacher and a group of sixteen pupils of Year 1 and 2, with the ages of 6 and 8. The revision of literature in certain national and international theories related with the concept of the Visual Culture, artistic education concepts and teachers training, made possible the deepening of knowledge that were the basis to the theory of this study. The in loco observations, as well as the analysis of the pupils‟ work, the teacher‟s comments, the reflections of the investigator, pictures of the places and activities, were the basis to the data of this study. The most pertinent results were: the observation of the very low importance of an education to the visual culture; the incapacity of the teacher and the children to read images related with their daily routine; the commitment of a proper education, caused by the absence of strategies and resources connected with the use of images; the need of a continued Primary teachers‟ training, with the collaboration of specialized teachers for the first cycle of the Basic Education as a viable solution and provided for by law; the situation of an healthy trade of the teacher and the pupils; the enthusiasm of the pupils, when doing their artistic tasks; the fact that Primary teachers “see” Plastic Expression as an excellent tool to reinforce the pupils‟ skills in different areas of knowledge; or the way to promote the pupil‟s social and personal development. More studies can be promoted from these precious data, which deserve further attention, mainly by those who have responsibilities in children‟s education