1,328 research outputs found
Interaction of Stern layer and domain structure on photochemistry of lead-zirconate-titanate.
No full textPerovskite ferroelectric materials such as PZT have long been known to have wideband semiconducting properties. It has also been found that they have interesting spatially controllable surface photochemical effects that are not seen in 'normal' semiconductors. This has led to their being studied as possible tools in areas such as metal salt reduction and oxidation for nanoparticle growth. This paper discusses the effects of incident photon energy on the reduction of Ag0 onto PZT(30/70) surfaces with particular emphasis on the part played by energy band bending and the Stern layer. It was found that for increasing photon energy between 4.4 and 5.0 eV both the [1 1 1] and the [1 0 0] orientations of PZT followed a similar trend in that the average Ag0 cluster cross-sectional area increased by a ratio of ca 1.6 to 1. This increase was put down to the higher energy photons exciting more electrons from deeper in the density of states for the material allowing a greater reduction rate of Ag+ at the surface
Worse than you think: Public debt forecast errors in advanced and developing economies
No full textWe compile a unique dataset of medium-term public debt forecasts for an unbalanced panel of 174 countries, based on International Monetary Fund (IMF) (for the period 1995-2020) and Economist Intelligence Unit (2007-2020) projections. We find that, on average, (i) there is a positive forecast error (FE) in the debt-to-gross domestic product (GDP) projections-that is, realized debt ratios are larger than forecasts; (ii) the FE increases with the projection horizon and is statistically significant and large-about 10% of GDP at the 5-year horizon; (iii) the magnitude is similar between advanced economies (AEs) and emerging markets and developing economies (EMDEs) and in EMDEs is present irrespective of recessions while for AEs is associated with surprise recessions in the forecast horizon; (iv) FEs are not statistically different between IMF program and non-program cases; and (v) positive FEs are only partly attributable to optimism about growth or the fiscal balance. Looking at the correlates of FEs, we find that FEs are larger during periods of recession, elections, fiscal stress, and high uncertainty and in countries with more economic volatility and public debt
Estrategias docentes en la construcción de un ambiente alfabetizador en primer ciclo del nivel primario, en la Institución Educativa Monseñor Miguel de Andrea, de la ciudad de Colón, Bs. As. año 2024
No full textLa escuela primaria es la institución responsable de promover el acercamiento de los niños/as al conocimiento. Del mismo modo, tiene el compromiso de posibilitar la constitución de este ambiente como una práctica social, garantizando la igualdad de condiciones de los estudiantes permitiendo el desarrollo de las habilidades y competencias comunicativas. El objetivo del presente trabajo de investigación reside en conocer las estrategias docentes que favorecen y enriquecen la construcción de un ambiente alfabetizador en primer ciclo de nivel primario en la escuela Monseñor Miguel de Andrea de la Localidad de Colón, Bs. As. Se plantea una investigación de enfoque cualitativo, empleando el método descriptivo, donde se utiliza como instrumento de recolección de datos la observación áulica del ambiente alfabetizador y entrevistas semiestructuradas a doce docentes de primer ciclo, así como también, a la bibliotecaria de la institución educativa. Según los resultados obtenidos en la investigación, se puede concluir que las docentes de primer ciclo efectúan diferentes estrategias para la conformación del ambiente alfabetizador, las cuales son trabajadas mediante situaciones habituales y prácticas sociales contextualizadas promoviendo los inicios de la cultura escrita de los estudiantes y aprendizajes significativos. Sin embargo, es necesario repensar estrategias que fortalezcan las prácticas docentes en la constitución del ambiente alfabetizador.Fil: D´Amelio, Antonela Estefania. Universidad de Flores; Argentina
Hotel Gondolín
No full textHotel Gondolin is a unique invitation to the South American trans world. This book portrays life in a boarding house where more than 100 transvestites and transsexuals coexist in the heart of the city of Buenos Aires. The hotel, whose history of struggle was forged in the 1990's is now a refuge for dozens of transvestites and transsexuals who come to the capital of Argentina. It is home. Itœs family. Through a work of more than 8 months, the editor and photographer Estefania dœEsperies visited weekly the inhabitants of this peculiar hotel, portraying their storie
Modelling the Effects of Crystalline-Stimulated Self-healing on Chloride Transportation into Cracked Concrete
No full textThe ingress of chloride ions in concrete induces the corrosion of reinforcement,
leading to a degradation of the mechanical performance of the intended
structural applications.The incorporation of crystallizing admixtures imparts autogenous
healing to conventional concrete, enabling cracks to seal by themselves and
thereby reducing the infiltration of chloride ions. Recognizing the inherent heterogeneity
of plain concrete, this study formulates a mesoscopic numerical model in
the framework of finite element method. The model conceptualizes concrete as a
three component structure: coarse aggregate, mortar matrix, and interfacial transition
zones (ITZs). To account for the influence of the self-healing phenomenon
in concrete, two further phases representing cracks and damage zones (DZs) are
introduced. The coarse aggregate phase is considered impermeable, with chloride
ion diffusion assumed to occur in the remaining four phases. The self-healing process
of cracks was simulated by using the moving mesh technique in COMSOL,
with reference to the method of establishing the kinetic lawof crack self-healing in
the follow-up of Horizon 2020 ReSHEALience project, undertaken in the project
MUSA, funded through the Italian National Resilience and Recover plan. Validated
against experimental data, the model not only reproduces the crack closure
process but also offers predictions on chloride transport. This simulation model
contributes to the exploration of concrete resistance to chloride permeability, elucidates
the transport mechanism of chloride ions within self-healing concrete,
and provides insights for designing durable concrete structures to mitigate the
corrosion of steel reinforcement or steel fibers
Are trade restrictions counter-cyclical? Evidence from a new aggregate measure
No full textWe present a new Measure of Aggregate Trade Restrictions (MATR) using data from the IMF's Annual Report on Exchange Arrangements and Exchange Restrictions. MATR is strongly correlated with existing measures of trade restrictiveness but more comprehensive in terms of country and time coverage. Our measure is available for an unbalanced sample of up to 157 countries during 1949-2019. We use our new MATR to re-examine how trade restrictiveness varies with the business cycle. Our results confirm that trade restrictions are typically a cyclical but there is an important difference across income groups: aggregate trade restrictions are a-cyclical in advanced economies but are counter-cyclical in EMDEs, especially in response to increases in unemployment.(c) 2023 The Society for Policy Modeling. Published by Elsevier Inc. All rights reserved
Energy inflation and consumption inequality
No full textThis paper examines the effects of higher energy prices on consumption inequality for a large panel of 129 advanced and developing economies during the period 1970–2013. The results suggest that energy inflation increases the Gini measure of consumption inequality and reduces (increases) the share of consumption of lower (higher) income deciles. These effects are larger in developing economies, in countries with limited access to finance, in those with weaker monetary policy frameworks, during periods of economic slack and in cases where government transfers do not compensate the poorer deciles during times of adverse income shocks
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