Continuous and discontinuous absorbing-state phase transitions on Voronoi-Delaunay random lattices

We study absorbing-state phase transitions in two-dimensional Voronoi-Delaunay (VD) random lattices with quenched coordination disorder. Quenched randomness usually changes the criticality and destroys discontinuous transitions in low-dimensional nonequilibrium systems. We performed extensive simulations of the Ziff-Gulari-Barshad (ZGB) model, and verified that the VD disorder does not change the nature of its discontinuous transition. Our results corroborate recent findings of Barghatti and Vojta [Phys. Rev. Lett. {\bf 113}, 120602 (2014)] stating the irrelevance of topological disorder in a class of random lattices that includes VD and raise the interesting possibility that disorder in nonequilibrium APT may, under certain conditions, be irrelevant for the phase coexistence. We also verify that the VD disorder is irrelevant for the critical behavior of models belonging to the directed percolation and Manna universality classes.Comment: 7 pages, 6 figure

Contact process on a Voronoi triangulation

We study the continuous absorbing-state phase transition in the contact process on the Voronoi-Delaunay lattice. The Voronoi construction is a natural way to introduce quenched coordination disorder in lattice models. We simulate the disordered system using the quasistationary simulation method and determine its critical exponents and moment ratios. Our results suggest that the critical behavior of the disordered system is unchanged with respect to that on a regular lattice, i.e., that of directed percolation

Coxiella burnetii in Ticks, Argentina

The Gammaproteobacterium Coxiella burnetii is the causative agent of acute Q fever and chronic endocarditis in humans worldwide. It is transmitted primarily by aerosol route or by ingestion of fomites from infected animals, mostly from domestic ruminants.Fil: Pacheco, Richard C.. Universidade Federal de Mato Grosso Do Sul; Brasil;Fil: Echaide, Ignacio Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria, Rafaela; ArgentinaFil: Alves, Rosiane N.. Universidad Federal de Uberlândia; BrasilFil: Beletti, Marcelo E.. Universidad Federal de Uberlândia; BrasilFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria, Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Labruna, Marcelo B.. Universidade Do Sao Paulo; Brasil

Forecasting Large Realized Covariance Matrices: The Benefits of Factor Models and Shrinkage

We propose a model to forecast large realized covariance matrices of returns, applying it to the constituents of the S\&P 500 daily. To address the curse of dimensionality, we decompose the return covariance matrix using standard firm-level factors (e.g., size, value, and profitability) and use sectoral restrictions in the residual covariance matrix. This restricted model is then estimated using vector heterogeneous autoregressive (VHAR) models with the least absolute shrinkage and selection operator (LASSO). Our methodology improves forecasting precision relative to standard benchmarks and leads to better estimates of minimum variance portfolios

A relevância do trabalho em equipe num caso de uma equipe interdisciplinar de docentes de primeiro ano de um curso de engenharia

This paper presents part of a broader research and aims to identify and analyze the perceptions of teachers involved with active methodologies, relating to PBL - Project-Based Learning, and the relevance of teamwork in this context. The research presents an exploratory qualitative approach, with data collected through semi-structured interviews with teachers who applied active methodologies since 2004. The interview results showed that the implementation of interdisciplinary projects has proven an effective method for increasing student motivation and consequently to increase their commitment with the learning process, which results in an effective development of technical transversal competences. Collaborative teaching work was considered fundamental for achieving the learning goals defined in the process, and as an opportunity for students to realize the interaction between teachers, tutors and researchers of education, showing that PBL encompasses multiple areas and persons to interact in the project throughout the semester. The teamwork involved strengthens and enhances the results.Este artigo apresenta um recorte de uma investigação mais ampla e tem o objetivo de identificar e analisar a percepção de professores envolvidos com metodologias ativas quanto a relevância em trabalhar com metodologias de aprendizagem baseada em projetos interdisciplinares (PBL – Project-Based Learning) e a relevância em trabalhar em equipa neste contexto. A pesquisa apresentou uma abordagem qualitativa de caráter exploratório, com coleta de dados através de entrevistas semiestruturadas com professores que desde 2004 aplicavam metodologias ativas. Os resultados das entrevistas evidenciaram que a implementação de projetos interdisciplinares tem-se mostrado uma metodologia eficaz para ampliar a motivação dos alunos e o consequente aumento do compromisso com a aprendizagem, que resulta na eficácia do desenvolvimento de competências técnicas e competências transversais. O trabalho colaborativo docente foi apontado como de fundamental importância para atingir os objetivos e também como uma vivência para os alunos perceberem a interação entre professores, tutores e investigadores da educação, pois PBL abarca várias disciplinas a interatuar no projeto durante todo o semestre letivo. O trabalho em equipe fortalece os envolvidos e potencializa os resultados