Parabolic dunes in north-eastern Brazil

In this work we present measurements of vegetation cover over parabolic dunes with different degree of activation along the north-eastern Brazilian coast. We are able to extend the local values of the vegetation cover density to the whole dune by correlating measurements with the gray-scale levels of a high resolution satellite image of the dune field. The empirical vegetation distribution is finally used to validate the results of a recent continuous model of dune motion coupling sand erosion and vegetation growth.Comment: 18 pages, 14 figures, aubmitted to Geomorpholog

Regular string-like braneworlds

In this work, we propose a new class of smooth thick string-like braneworld in six dimensions. The brane exhibits a varying brane-tension and an $AdS$ asymptotic behavior. The brane-core geometry is parametrized by the Bulk cosmological constant, the brane width and by a geometrical deformation parameter. The source satisfies the dominant energy condition for the undeformed solution and has an exotic asymptotic regime for the deformed solution. This scenario provides a normalized massless Kaluza-Klein mode for the scalar, gravitational and gauge sectors. The near-brane geometry allows massive resonant modes at the brane for the $s$ state and nearby the brane for $l=1$.Comment: 14 pages, 12 figures. Some modifications to match the published version in EPJ

Computational Topology Techniques for Characterizing Time-Series Data

Topological data analysis (TDA), while abstract, allows a characterization of time-series data obtained from nonlinear and complex dynamical systems. Though it is surprising that such an abstract measure of structure - counting pieces and holes - could be useful for real-world data, TDA lets us compare different systems, and even do membership testing or change-point detection. However, TDA is computationally expensive and involves a number of free parameters. This complexity can be obviated by coarse-graining, using a construct called the witness complex. The parametric dependence gives rise to the concept of persistent homology: how shape changes with scale. Its results allow us to distinguish time-series data from different systems - e.g., the same note played on different musical instruments.Comment: 12 pages, 6 Figures, 1 Table, The Sixteenth International Symposium on Intelligent Data Analysis (IDA 2017

WebGIS Amazônia Legal: um sistema para integração de informações e suporte à tomada de decisão.

O presente trabalho teve, como objetivo, implementar um WebGIS que possibilitasse a manutenção e disponibilização do conteúdo gerado com a aquisição, a análise e a unificação dos dados da Amazônia Legal e que fosse capaz de oferecer subsídios para a tomada de decisão, especialmente em assuntos que dizem respeito à gestão ambiental

How does authentic leadership boost work engagement? Exploring the mediating role of work meaningfulness and work–family enrichment

Leadership is crucial in organizational life. Positive leadership is marked by transparent, trust-based leader–follower relationships that significantly boost employees’ dedication and engagement. Work engagement stems from a positive bond between workers, their job, and their organization. Authentic leadership, in particular, has been found to enhance work engagement, but this relationship is quite complex. Prior studies have explored the psychological processes linking organizational context and work-related attitudes and provided intriguing insights, such as that employees consider work to be part of their identity and that positive work experiences enrich family life. This research more closely examined authentic leadership’s impact on work engagement, including the mediating effect of meaningful work and work–family enrichment. A cross-sectional study was conducted with data from various organizations’ employees (number = 292). Multiple regression analyses’ results support the theoretical model, confirming a significant positive link between perceived authentic leadership and work engagement. These variables are directly and indirectly related through the proposed mediators. Implications for human resource management are discussed, especially strategies that increase work environments’ positive impacts on work engagement.info:eu-repo/semantics/publishedVersio

Temperature dependence of antiferromagnetic susceptibility in ferritin

We show that antiferromagnetic susceptibility in ferritin increases with temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when taken as the derivative of the magnetization at high fields ($30\times10^4$ Oe). This behavior contrasts with the decrease in temperature previously found, where the susceptibility was determined at lower fields ($5\times10^4$ Oe). At high fields (up to $50 \times10^4$ Oe) the temperature dependence of the antiferromagnetic susceptibility in ferritin nanoparticles approaches the normal behavior of bulk antiferromagnets and nanoparticles considering superantiferromagnetism, this latter leading to a better agreement at high field and low temperature. The contrast with the previous results is due to the insufficient field range used ($< 5 \times10^4$ Oe), not enough to saturate the ferritin uncompensated moment.Comment: 7 pages, 7 figures, accepted in Phys. Rev.