Analytical study of tunneling times in flat histogram Monte Carlo

We present a model for the dynamics in energy space of multicanonical simulation methods that lends itself to a rather complete analytic characterization. The dynamics is completely determined by the density of states. In the \pm J 2D spin glass the transitions between the ground state level and the first excited one control the long time dynamics. We are able to calculate the distribution of tunneling times and relate it to the equilibration time of a starting probability distribution. In this model, and possibly in any model in which entering and exiting regions with low density of states are the slowest processes in the simulations, tunneling time can be much larger (by a factor of O(N)) than the equilibration time of the probability distribution. We find that these features also hold for the energy projection of single spin flip dynamics.Comment: 7 pages, 4 figures, published in Europhysics Letters (2005

Process transparency on construction sites : examples from construction companies in Brazil

Process transparency is the core concept in Visual Management (VM), which is one of the founding blocks of the Toyota Production System. This paper presents the preliminary results of a collaborative research conducted between Brazil and the UK, as part of a research effort focused on the application of Visual Management in construction. How process transparency is realized on construction sites is the main research question of the paper. The use of this concept and the implementation of the transparency theory were investigated through multiple case studies, carried out in nine different construction companies. The findings are explained through six theoretical transparency increasing approaches. The affecting parameters in the application of, the management’s perception of and several methods in process transparency in construction were identified. Further work, especially exploring the functions of process transparency on construction sites and reflecting the worker perception of the issue, is necessary to elaborate the process transparency concept

Early Enrichment of the Intergalactic Medium and its Feedback on Galaxy Formation

Supernova-driven outflows from early galaxies may have had a large impact on the kinetic and chemical structure of the intergalactic medium (IGM). We use three-dimensional Monte Carlo cosmological realizations of a simple linear peaks model to track the time evolution of such metal-enriched outflows and their feedback on galaxy formation. We find that at most 30% of the IGM by volume is enriched to values above 10^-3 solar in models that only include objects that cool by atomic transitions. The majority of enrichment occurs relatively early (5 < z < 12) and resulting in a mass-averaged cosmological metallicity between 10^-3 and 10^-1.5 solar. The inclusion of Population III objects that cool through H2 line emission has only a minor impact on these results: increasing the mean metallicity and filling factor by at most a factor of 1.4, and moving the dawn of the enrichment epoch to a redshift of approximately 14 at the earliest. Thus enrichment by outflowing galaxies is likely to have been incomplete and inhomogeneous, biased to the areas near the starbursting galaxies themselves. Models with a 10% star formation efficiency can satisfactorily reproduce the nearly constant (2 < z < 5, Z approximately 3.5 x 10^-4 solar) metallicity of the low column density Ly-alpha forest derived by Songaila (2001), an effect of the decreasing efficiency of metal loss from larger galaxies. Finally, we show that IGM enrichment is intimately tied to the ram-pressure stripping of baryons from neighboring perturbations. This results in the suppression of at least 20% of the dwarf galaxies in the mass range 10^8.5 to 10^9.5 solar, in all models with filling factors greater than 2%, and an overall suppression of approximately 50% of dwarf galaxies in the most observationally-favored model.Comment: 8 pages, 5 figures, accepted to Ap

Earnings management of brazilian firms in the IFRS era: The role of economic and institutional factors

This study investigates whether accounting quality – more specifically regarding the level of earnings management by accruals – is associated with a country’s economic and institutional factors that change over time in IFRS era. Based on a sample of 1,387 Brazilian firm-year observations and data regarding 2011 to 2018, econometric models are estimated considering the absolute amount of discretionary accruals as proxy for earnings management and different aspects related to economic and institutional factors of preeminent importance to an emerging economy. We show that in general, high inflation, stock market volatility, and policy uncertainty rates, as well as lower regulatory quality, on average, are associated with a higher level of earnings management in Brazil. This study contributes to the accounting literature in emerging economies discussing the role of economic and institutional factors on accounting quality in the IFRS era in one of the largest developing country in the world. Compared to developed countries or even to other developing economies, Brazil stands out as an emerging economy of considerable economic and political instability, making it a valuable setting for this analysisinfo:eu-repo/semantics/publishedVersio

Does national ethical judgment matter for earnings management?

This study analyses the effect of ethical judgment at country-level on earnings management. While previous literature document the role of ethical issues at personal- and organizational-level on earnings management practices, usually theoretically and through qualitative ways, we investigate that association in a large sample at international level taken a sample of 81,408 firm-year observations regarding 10,306 firms from 39 countries. Based on data from an international questionnaire developed by the World Values Survey, we construct a comprehensive index of ethical judgment of each country. Our empirical findings suggest that the level of ethical judgment of the countries are negative associated with accruals-based earnings management, suggesting that the manipulation of accounting amounts is lower in countries where ethically suspect behaviours are less acceptable. Additionally, we also provide empirical evidences that this phenomenon is verified both in developed and emerging countries, and that ethical judgment at country-level seem to moderate the association between IFRS adoption and earnings management practices.info:eu-repo/semantics/acceptedVersio

Capoeira : práticas culturais do recôncavo baiano e o processo pedagógico criativo inclusivo

Este tema enquadra-se no âmbito de um projeto de doutoramento, desenvolvido através do Centro de Formação de Professores da UFRB/Brasil, enquadrado na área temática - Educação, Desenvolvimento e Expressões Artísticas. Propõe atividades vinculadas ao estudo da Cultura corporal, a partir das práticas culturais do recôncavo baiano, na formação de pessoas com deficiência/doença mental e/ou em situação de risco social e pessoal, com intuito de responder às dificuldades e perspetivas da ação pedagógica, considerando o impacto educativo da musicalidade, movimento corporal e a dinamica das relações interpessoais. Explora uma educação inclusiva a partir da reflexão sobre alternativas no trato com a capoeira, samba, maculele, entre outras, para melhoria de questões que variam desde a cognição até de auto-estima e identitárias, consignadas numa proposta de implementação de uma atividade de enriquecimento curricular, em articulação com o currículo formal. Com este interesse foi traçada uma metodologia centrada numa perspectiva qualitativa, a partir de um estudo de caso, considerando a realidade de uma escola municipal. Assim, além de se observar significativos impactos na perspetiva de inclusão destas pessoas, promovem-se práticas culturais e articula-se pesquisa, ensino e extensão, garantindo o papel formativo e social da UFRB junto da comunidade da cidade de Amargosa e a possibilidade de experimentar uma intervenção pedagógica criativa inclusiva com estudantes de Educação.Fundação para a Ciência e a Tecnologia (FCT

White light tunable emissions from ZnS: Eu3+ nanophosphors over 330–465nm excitation range for white LED applications

(ZnS: Eu3+ -CMC) nanophosphors of cubic (zinc blende) structure were synthesized using a precipitation technique with doping concentrations of Eu3+ ions 1 mol% and 5 mol%. The crystal sizes were 2.56 nmand 2.91 nmrespectively. Annealing at 300 °Cin a sulfur-rich atmosphere altered the crystal size to 4.35 nmand 3.65 nmrespectively and the band gap from 4.2 eV to 3.76 eV and 3.81 eV respectively. The as-synthesized samples gave pure orange-red emission when excited at wavelengths of 394 nmand 465 nm. After thermal annealing of the samples, a broad emission band in the blue-green region assigned to defect related states emerged or were enhanced. Also enhanced were the emission lines of Eu3+ ions in the orange-red region. A combination of these two transitions gave white light of different shades (recorded on the CIE 1931 chromaticity diagram) from cool white through day-light to warm white light, depending on Eu3+ concentration and the excitation wavelengths (UV-330 to blue 465 nm), thus showing great potential of these nano-phosphors in the generation of high quality white light

Towards absolute calibration of optical tweezers

Aiming at absolute force calibration of optical tweezers, following a critical review of proposed theoretical models, we present and test the results of MDSA (Mie-Debye-Spherical Aberration) theory, an extension of a previous (MD) model, taking account of spherical aberration at the glass/water interface. This first-principles theory is formulated entirely in terms of experimentally accessible parameters (none adjustable). Careful experimental tests of the MDSA theory, undertaken at two laboratories, with very different setups, are described. A detailed description is given of the procedures employed to measure laser beam waist, local beam power at the transparent microspheres trapped by the tweezers, microsphere radius and the trap transverse stiffness, as a function of radius and height in the (inverted microscope) sample chamber. We find generally very good agreement with MDSA theory predictions, for a wide size range, from the Rayleigh domain to large radii, including the values most often employed in practice, and at different chamber heights, both with objective overfilling and underfilling. The results asymptotically approach geometrical optics in the mean over size intervals, as they should, and this already happens for size parameters not much larger than unity. MDSA predictions for the trapping threshold, position of stiffness peak, stiffness variation with height, multiple equilibrium points and `hopping' effects among them are verified. Remaining discrepancies are ascribed to focus degradation, possibly arising from objective aberrations in the infrared, not yet included in MDSA theory.Comment: 15 pages, 20 figure