QuickCSG: Fast Arbitrary Boolean Combinations of N Solids

QuickCSG computes the result for general N-polyhedron boolean expressions without an intermediate tree of solids. We propose a vertex-centric view of the problem, which simplifies the identification of final geometric contributions, and facilitates its spatial decomposition. The problem is then cast in a single KD-tree exploration, geared toward the result by early pruning of any region of space not contributing to the final surface. We assume strong regularity properties on the input meshes and that they are in general position. This simplifying assumption, in combination with our vertex-centric approach, improves the speed of the approach. Complemented with a task-stealing parallelization, the algorithm achieves breakthrough performance, one to two orders of magnitude speedups with respect to state-of-the-art CPU algorithms, on boolean operations over two to dozens of polyhedra. The algorithm also outperforms GPU implementations with approximate discretizations, while producing an output without redundant facets. Despite the restrictive assumptions on the input, we show the usefulness of QuickCSG for applications with large CSG problems and strong temporal constraints, e.g. modeling for 3D printers, reconstruction from visual hulls and collision detection

Present and future Greenland ice sheet surface energy balances with the help of the regional climate MAR model

See enclosed abstract-and-contents.pdfThe Greenland ice sheet (GrIS) surface mass balance (SMB) was modelled at different spatial resolutions (15-50 km), using the regional climate model MAR (Modèle Atmosphérique Régional) forced by the ERA-INTERIM reanalysis over the 1990-2010 period. The comparison of these simulations revealed that (i) the inter-annual variability of the SMB components is consistent within the different resolutions investigated when they are integrated over the whole ice sheet, (ii) the MAR model simulates heavier precipitation on average over the GrIS with decreasing resolution, and (iii) the SMB components (except precipitation) can be derived from a lower-resolution simulation with an enhanced interpolation. This interpolation can also be used to approximate the SMB components over another topography/ice sheet mask of the GrIS. These results are valuable for the forcing of an ice dynamical model, needed to enable full projections of the GrIS mass balance contribution to sea-level rise (SLR) over the coming centuries. Moreover, this work showed that 25 km-resolution MAR simulation is a good compromise between computing time and results precision in the aim to perform afterwards 21st-century projections of the GrIS melt. The most suited atmosphere-ocean general circulation models (AOGCMs) for the GrIS current climate modelling were selected on the basis of comparison between the 1970-1999 outputs and reanalyses, showing that the representation quality of surface parameters (temperature, precipitation) are highly correlated to the atmospheric circulation and its inter-annual variability (North Atlantic oscillation). Future atmospheric circulation changes according to greenhouse gas (GHG) emissions scenarios were projected to dampen the zonal flow, enhance the meridional fluxes and provide additional heat and moisture to the GrIS, increasing temperature over the whole ice sheet and precipitation over its northeastern area. Moreover, future projections performed with the selected AOGCMs showed consistent anomalies to the present-day climate. The GrIS SMB anomalies from the A1B scenario amount to -300 Gt/yr with respect to 1970-1999, leading to a SLR of 5 cm by the end of the 21st century. This work helped to select the AOGCMs used as forcing fields in the MAR model to carry out future projections of the GrIS. 20th and 21st centuries MAR simulations at 25km resolution forced by previously selected GCMs according to GHG scenarios were performed over the GrIS in order to investigate the projected changes of the surface energy balance (SEB) components driving the surface melt. Analysis of 2000-2100 melt anomalies to 1980–1999 results revealed an exponential relationship of the surface melt to the near-surface temperature anomalies, mainly due to the surface albedo positive feedback associated with the extension of bare ice areas in summer. On the GrIS margins, the future melt anomalies are driven by stronger sensible heat fluxes, induced by enhanced warm air advections. Over the central dry snow zone, the increase of melt surpasses the negative feedback from heavier snowfall inducing a decrease of the summer surface albedo. In addition to the incoming longwave flux increase associated to the atmosphere warming, MAR projected an increase of the cloud cover decreasing the ratio of the incoming shortwave versus longwave radiation and dampening the albedo feedback. This trend of cloud cover is contrary to that simulated by reanalyses-forced MAR over current climate, where the observed melt increase since the 1990’s is rather a consequence of more anticyclonic atmospheric conditions. No significant change was projected in the length of the melt season, highlighting the importance of solar radiation in the melt SEB

QuickCSG: Fast Arbitrary Boolean Combinations of N Solids

QuickCSG computes the result for general N-polyhedron boolean expressions without an intermediate tree of solids. We propose a vertex-centric view of the problem, which simplifies the identification of final geometric contributions, and facilitates its spatial decomposition. The problem is then cast in a single KD-tree exploration, geared toward the result by early pruning of any region of space not contributing to the final surface. We assume strong regularity properties on the input meshes and that they are in general position. This simplifying assumption, in combination with our vertex-centric approach, improves the speed of the approach. Complemented with a task-stealing parallelization, the algorithm achieves breakthrough performance, one to two orders of magnitude speedups with respect to state-of-the-art CPU algorithms, on boolean operations over two to dozens of polyhedra. The algorithm also outperforms GPU implementations with approximate discretizations, while producing an output without redundant facets. Despite the restrictive assumptions on the input, we show the usefulness of QuickCSG for applications with large CSG problems and strong temporal constraints, e.g. modeling for 3D printers, reconstruction from visual hulls and collision detection

What the eyes can’t see: the future according to Monteiro Lobato

Over the last years, Monteiro Lobato has been rightfully accused by Brazilian and Latin American scholars of expressing racist and eugenic ideas in his body of work. In this article, we take a step further and add to this traditional portrait of his literary production an analysis of the impact of a new set of technological media during the first decades of the twentieth century on his writings. We discuss how these two main issues – i.e., technology and race – played out in Lobato’s historical representation of Brazil’s past and future and the influence that the United States could play in it. We show how a revisionary and racist version of the United States’ history and the ideal of an American technological prosperity in the 1920s inspired one of Lobato’s most contentious novels, the technological dystopia O Presidente Negro, ou O Choque das Raças, published in 1926.   &nbsp

Political news and future markets returns

Brazilian media repeatedly claims that political news do affect financial markets returns, yet such belief goes against the Efficient Market Hypothesis (EMH) on its semi-strong form. This paper explores the impacts of political news in Brazilian future markets returns, more specifically in U.S. Dollar Futures (DOL), BOVESPA Index Futures (IND) and 1-Day Interbank Deposits Futures (DI1), over the period from July 2019 to March 2022. In order to achieve that objective we performed two methods to gather the days of abnormal volatility from the data sample: a parametric and a non parametric method. A GARCH, and its variations, were applied to filter the volatility from the data. To get political news data we implemented the web scraping technique, for two purposes: to gather the news headlines and links, as well as to assemble the news volume series over time. Afterwards, a Granger causality test was used, to check if the news volume series over time Granger-causes the volatility series. Our results suggest no significant impact of political news on the volatility series for all three assets, and hence no significant impact in their respective returns.A mídia brasileira repetidas vezes afirma que notícias políticas afetam os retornos dos mercados financeiros, porém essa crença vai de encontro à Hipótese dos Mercados Eficientes (EMH) na sua forma semi forte. Esse artigo explora os impactos de notícias políticas nos retornos do mercado de futuros brasileiro, mais especificamente no Futuro de Taxa de Câmbio de Reais por Dólar Comercial (DOL), Futuro de Ibovespa (IND) e Futuro de Taxa Média de Depósitos Interfinanceiros de Um Dia (DI1), durante o período de julho de 2019 até março de 2022. Para atingir esse objetivo, dois métodos foram implementados para obter os dias de volatilidade anormal da amostra: um paramétrico e outro não paramétrico. Um modelo GARCH, e suas variações, foram aplicadas para filtrar a volatilidade dos dados. Para coletar as notícias políticas a técnica de web scraping foi utilizada, com dois propósitos: reunir os links e manchetes das notícias, além de agrupar a série do volume de notícias ao longo do tempo. Posteriormente, o teste de Granger causalidade foi usado, para checar se a série do volume de notícias Granger-causa a série da volatilidade. Os resultados obtidos não sugerem impacto significativo de notícias políticas na série de volatilidade para os três ativos, e portanto, nenhum impacto significativo nos seus respectivos retornos

The role of income inequality on fiscal multipliers

A Work Project, presented as part of the requirements for the Award of a Masters Double Degree in Economics from the Nova School of Business and Economics and University of MaastrichtThis paper investigates the role of income inequality on the size of fiscal multipliers during the recent crisis. Using various measures of income inequality, the empirical strategy developed suggests a positive and statistically significant impact of inequality on the size of fiscal multipliers of European economies during 2010-11. The results are robust after controlling for the role of outliers, by adding controls that could be driving the results, testing for different forecast vintages, and using a different source of standardized income inequality data. Theoretical arguments that may explain the results are presented. Namely the existence of credit constraints to relatively poor households, and the lower propensity to consume of relatively wealthier households

Does the issuance of Green Bonds provide a cheaper source of capital to firms?

Climate change is a human-induced problem and, as such, it falls upon us to deal with it through mitigation and adaptation strategies, if we are to secure a clean, liveable World for current and future generations. However, to implement and follow these plans, there are substantial costs that surpass the public budget. Hence, finance plays a key role in developing financial instruments that can involve the private sector in advancing sustainability. Green Bonds are one of these innovations, requiring the issuer, with its Use of Proceeds clause, to allocate all its proceeds towards environmentally friendly projects. This dissertation tries to answer the following question: “Do Green Bonds have lower yields than Conventional Bonds?”. Using different matching methods and regression models, we did not find proof of the Green Bond premium, suggesting that investors are not willing to trade return for the support of greener projects. Determining if there is a difference in the pricing of Green and Conventional Bonds is key in the development and implementation of policies and initiatives to help the Green Bond Market unlock its full potential. Looking at our results, to further the green agenda, governments and policymakers should prioritise Green Bonds, increasing their attractiveness and differentiating them from their counterpart, by introducing, for instance, compensation or tax deduction policies.As mudanças climáticas são consequência da atividade humana e, como tal, temos a responsabilidade de as solucionar através de estratégias de mitigação e adaptação, se queremos assegurar um Mundo limpo e sustentável para as gerações corrente e futura. No entanto, para implementar e seguir tais planos, existem custos substanciais envolvidos que ultrapassam o orçamento público. Como tal, as finanças desempenham um papel fundamental no desenvolvimento de instrumentos financeiros capazes de envolver o setor privado em avançar a sustentabilidade. As Obrigações Verdes são uma destas inovações, exigindo que as empresas emissoras, com a sua cláusula de Uso dos Rendimentos, apliquem todos os rendimentos em projetos amigos do ambiente. Esta dissertação pretende responder à seguinte questão: “As Obrigações Verdes têm taxas de juro inferiores às Obrigações Convencionais?”. Através do uso de diferentes métodos de correspondência e modelos de regressão, não encontrámos prova que as Obrigações Verdes têm um premium, sugerindo que os investidores não estão dispostos a trocar rendimento pelo apoio de projetos sustentáveis. Determinar se existe uma diferença nas taxas de juro entre Obrigações Verdes e Convencionais é essencial para o desenvolvimento e implementação de iniciativas destinadas a ajudar o Mercado das Obrigações Verdes a atingir o seu potencial. Focando-nos nos resultados, de forma a elevar a agenda sustentável, governos e outras entidades responsáveis devem dar prioridade às Obrigações Verdes, melhorando a sua atratividade e diferenciando-as das Obrigações Convencionais, através da introdução de, por exemplo, políticas de compensação ou dedução de impostos

Distributed correlations and information flows within a hybrid multipartite quantum-classical system

Understanding the non-Markovian mechanisms underlying the revivals of quantum entanglement in the presence of classical environments is central in the theory of quantum information. Tentative interpretations have been given by either the role of the environment as a control device or the concept of hidden entanglement. We address this issue from an information-theoretic point of view. To this aim, we consider a paradigmatic tripartite system, already realized in the laboratory, made of two independent qubits and a random classical field locally interacting with one qubit alone. We study the dynamical relationship between the two-qubit entanglement and the genuine tripartite correlations of the overall system, finding that collapse and revivals of entanglement correspond, respectively, to raise and fall of the overall tripartite correlations. Interestingly, entanglement dark periods can enable plateaux of nonzero tripartite correlations. We then explain this behavior in terms of information flows among the different parties of the system. Besides showcasing the phenomenon of the freezing of overall correlations, our results provide new insights on the origin of retrieval of entanglement within a hybrid quantum-classical system.Comment: 9 pages, 5 figures. To appear on Phys. Rev.

A fluorometric method for the assay of protein kinase activity

Protein kinases constitute one of the largest protein families in nature. Current methods to assay their activity involve the use of radioactive ATP or very expensive reagents. In this work, we developed a highly sensitive, cost-effective and straightforward protocol to measure protein kinase activity using a microplate layout. Released ADP is converted into NAD+, which is quantified by its fluorescent properties after alkaline treatment (linear range 0–10 nmol ADP). To validate our protocol, we characterized a recombinant calcium-dependent protein kinase from potato. Overall, this tool represents a critical step forward in the functional characterization of protein kinases.Fil: Rojas, Bruno Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Santin, Franco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Ulloa, Rita Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Iglesias, Alberto Alvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Figueroa, Carlos Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

Two-qubit entanglement dynamics for two different non-Markovian environments

We study the time behavior of entanglement between two noninteracting qubits each immersed in its own environment for two different non-Markovian conditions: a high-$Q$ cavity slightly off-resonant with the qubit transition frequency and a nonperfect photonic band-gap, respectively. We find that revivals and retardation of entanglement loss may occur by adjusting the cavity-qubit detuning, in the first case, while partial entanglement trapping occurs in non-ideal photonic-band gap.Comment: 8 pages, 2 figure