Kelvin-Helmholtz versus Hall Magneto-shear instability in astrophysical flows

We study the stability of shear flows in a fully ionized plasma. Kelvin-Helmholtz is a well known, macroscopic and ideal shear-driven instability. In sufficiently low density plasmas, also the microscopic Hall magneto-shear instability can take place. We performed three-dimensional simulations of the Hall-MHD equations where these two instabilities are present, and carried out a comparative study. We find that when the shear flow is so intense that its vorticity surpasses the ion-cyclotron frequency of the plasma, the Hall magneto-shear instability is not only non-negligible, but it actually displays growth rates larger than those of the Kelvin-Helmholtz instability

Coordination and Miss-Coordination in Market Entry Games with an Application to Congestion Externalities

Marketing,

Do Natural Disasters Affect Trust/Trustworthiness? Evidence from the 2010 Chilean Earthquake

A series of trust games were conducted in Chile to analyze whether the past 2010 earthquake affected trust and trustworthiness in rural communities. Results show that trust levels are invariant between villages affected by the earthquake and villages not affected by this shock (control group). However, we find statistical evidence that trustworthiness has diminished in areas affected by the earthquake. Results are relevant for policy regarding aid and recovery of communities affected by these types of disasters.Trust games, natural disasters, trustworthiness, Community/Rural/Urban Development, International Development, C93, O13,

High-Resolution Dynamics of Hydrogen Peroxide on the Surface of Scleractinian Corals in Relation to Photosynthesis and Feeding

We developed and used a microsensor to measure fast (<1 s) dynamics of hydrogen peroxide (H2O2) on the polyp tissue of two scleractinian coral species (Stylophora pistillata and Pocillopora damicornis) under manipulations of illumination, photosynthesis, and feeding activity. Our real-time tracking of H2O2 concentrations on the coral tissue revealed rapid changes with peaks of up to 60 mu M. We observed bursts of H2O2 release, lasting seconds to minutes, with rapid increase and decrease of surficial H2O2 levels at rates up to 15 mu M s(-1). We found that the H2O2 levels on the polyp surface are enhanced by oxygenic photosynthesis and feeding, whereas H2O2 bursts occurred randomly, independently from photosynthesis. Feeding resulted in a threefold increase of baseline H2O2 levels and was accompanied by H2O2 bursts, suggesting that the coral host is the source of the bursts. Our study reveals that H2O2 levels at the surface of coral polyps are much higher and more dynamic than previously reported, and that bursts are a regular feature of the H2O2 dynamics in the coral holobiont

Thread Counting in Plain Weave for Old Paintings Using Semi-Supervised Regression Deep Learning Models

In this work, the authors develop regression approaches based on deep learning to perform thread density estimation for plain weave canvas analysis. Previous approaches were based on Fourier analysis, which is quite robust for some scenarios but fails in some others, in machine learning tools, that involve pre-labeling of the painting at hand, or the segmentation of thread crossing points, that provides good estimations in all scenarios with no need of pre-labeling. The segmentation approach is time-consuming as the estimation of the densities is performed after locating the crossing points. In this novel proposal, we avoid this step by computing the density of threads directly from the image with a regression deep learning model. We also incorporate some improvements in the initial preprocessing of the input image with an impact on the final error. Several models are proposed and analyzed to retain the best one. Furthermore, we further reduce the density estimation error by introducing a semi-supervised approach. The performance of our novel algorithm is analyzed with works by Ribera, Vel\'azquez, and Poussin where we compare our results to the ones of previous approaches. Finally, the method is put into practice to support the change of authorship or a masterpiece at the Museo del Prado.Comment: 21 page

Electrification of the boat fleet of the Albufera Natural Park of Valencia: methodology, economic and environmental assessments

[EN] This article presents a methodology for calculating the energy needs to propose the electrification of a fleet of small boats. A technical, economic and environmental analysis of the transition to electric mobility of the fleet of boats in the wetland of the Albufera Natural Park of Valencia (Spain) is presented and analysed. The environmental benefits of this transition are explored and an economic assessment is done, including the evaluation of the necessary public incentives to capture all the benefits related to this transition and make it feasible.This work was supported in part by the Spanish public administration under the grant FPU2016/00962 and by the Cátedra de Transición Energética Urbana (Las Naves-UPV).Bejarano-Cáceres, DS.; Ribó-Pérez, DG.; Alcázar-Ortega, M. (2020). Electrification of the boat fleet of the Albufera Natural Park of Valencia: methodology, economic and environmental assessments. Renewable Energy and Power Quality Journal. 18:144-149. https://doi.org/10.24084/repqj18.254S1441491

A computer aided approach for river styles-inspired characterization of large basins: The Magdalena river (Colombia)

This paper addresses the geomorphic characterization and classification of large rivers in a framework of scarce information. This is inspired by the River Styles Framework with some modifications that make the process more straightforward and accessible to practitioners and more applicable to large basins, while reducing the subjective, expert-based inputs, as the process is now more systematic. To this aim, it utilizes innovative criteria and some computer-aided procedures and tools based on GIS, Excel and Python. This approach sheds light on the character and the behavior of rivers, which is key to informing planning, management and restoration. The application to the Magdalena River (Colombia) illustrates the characterization and classification process and the type of results, which ultimately highlight the great geomorphic diversity of that river. The process is applicable to many other rivers worldwide

Resource Adequacy: Should Regulators Worry?

Regulators have proposed various institutional alternatives to secure network resource adequacy and reasonably priced electric power for consumers. These alternatives prompt many difficult questions: Does the development of Demand Response reduce the need for new capacity? How effectively can a government-mandated Capacity Market foster efficient investment? How does centralized generator commitment (with revenue guarantees) compare to a system in which Generators voluntarily commit themselves with no revenue guarantees? If exclusive distribution contracts were replaced by unregulated retail competition, what would be the effects on investment and market prices? We use laboratory experiments to address these questions