Brazil: Oil and uncertainty

Oil spill disasters in the ocean often devastate marine and coastal ecosystems, profoundly affecting fisheries resources and fishing communities. Urgent and early-warning actions are needed to avoid a tragedy in biomes and communities when such accidents occur. In late-July 2019, Brazilian fishers alerted the first oil slick reaching the coast of Paraíba, weeks before the recognition of the biggest-ever oil spill disaster ever recorded in Brazil, extending across the entire North-eastern coast of the country. Their early voices were not properly heeded but those signals escalated into a gigantic spread of petroleum slicks. Almost 1,000 different localities were affected, including beaches, mangroves, rivers and “protected” areas. All the nine states of the region, encompassing a 2,300-km long shoreline, switched on a red light

Single-parameter spin-pumping in driven metallic rings with spin-orbit coupling

We consider the generation of a pure spin-current at zero bias voltage with a single time-dependent potential. To such end we study a device made of a mesoscopic ring connected to electrodes and clarify the interplay between a magnetic flux, spin-orbit coupling, and non-adiabatic driving in the production of a spin and electrical current. By using Floquet theory, we show that the generated spin to charge current ratio can be controlled by tuning the spin-orbit coupling.publishedVersionFil: Ramos Andrade, Juan Pablo. Universidad Católica del Norte. Departamento de Física; Chile.Fil: Foa Torres, Luis Eduardo Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Foa Torres, Luis Eduardo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Orellana, P. A. Universidad Técnica Federico Santa María. Departamento de Física; Chile.Fil: Apel, Víctor Marcelo. Universidad Católica del Norte. Departamento de Física; Chile.Física de los Materiales Condensado

Assessing the regional impacts of Mexico City emissions on air quality and chemistry

The impact of Mexico City (MCMA) emissions is examined by studying its effects on air quality, photochemistry, and on ozone production regimes by combining model products and aircraft observations from the MILAGRO experiment during March 2006. The modeled influence of MCMA emissions to enhancements in surface level NOx [NO subscript x], CO, and O3 [O subscript 3] concentrations (10–30% increase) are confined to distances <200 km, near surface. However, the extent of the influence is significantly larger at higher altitudes. Broader MCMA impacts (some 900 km Northeast of the city) are shown for specific outflow conditions in which enhanced ozone, NOy [NO subscript y], and MTBE mixing ratios over the Gulf of Mexico are linked to MCMA by source tagged tracers and sensitivity runs. This study shows that the "footprint" of MCMA on average is fairly local, with exception to reactive nitrogen, which can be transported long range in the form of PAN, acting as a reservoir and source of NOx [NO subscript x] with important regional ozone formation implications. The simulated effect of MCMA emissions of anthropogenic aerosol on photochemistry showed a maximum regional decrease of 40% in J[NO2→NO+O] [J [NO subscript 2 → NO + O]], and resulting in the reduction of ozone production by 5–10%. Observed ozone production efficiencies are evaluated as a function of distance from MCMA, and by modeled influence from MCMA. These tend to be much lower closer to MCMA, or in those points where modeled contribution from MCMA is large. This research shows that MCMA emissions do effect on regional air quality and photochemistry, both contributing large amounts of ozone and its precursors, but with caveat that aerosol concentrations hinder formation of ozone to its potential due to its reduction in photolysis rates.United States. National Aeronautics and Space AdministrationNational Science Foundation (U. S.) (ATM award 0528227

The role of ascorbate peroxidase, guaiacol peroxidase, and polysaccharides in cassava (Manihot esculenta Crantz) roots under postharvest physiological deterioration

Abstract This study aimed to investigate the role of ascorbate peroxidase (APX), guaiacol peroxidase (GPX), polysaccharides, and protein contents associated with the early events of postharvest physiological deterioration (PPD) in cassava roots. Increases in APX and GPX activity, as well as total protein contents occurred from 3 to 5 days of storage and were correlated with the delay of PPD. Cassava samples stained with periodic acid-Schiff (PAS) highlighted the presence of starch and cellulose. Degradation of starch granules during PPD was also detected. Slight metachromatic reaction with toluidine blue is indicative of increasing of acidic polysaccharides and may play an important role in PPD delay. Principal component analysis (PCA) classified samples according to their levels of enzymatic activity based on the decision tree model which showed GPX and total protein amounts to be correlated with PPD. The Oriental (ORI) cultivar was more susceptible to PPD.This work was supported by PEC-PG ("Programa de Estudantes Convenio de Pos-Graduacao") coordinated by CAPES ("Coorde nacao de Aperfeicoamento de Pessoal de Nivel Superior"). CNPq has provided a research fellowship to Marcelo Maraschin

Tunable Mode Entanglement: Topological Su–Schrieffer–Heeger (SSH) Chain with an Embedded Aharonov–Bohm Quantum Ring

A variant of the SSH model consisting of an SSH chain with an embedded Aharonov–Bohm quantum ring is investigated. The embedded ring gives rise to domain wall states whose energy levels are in the band gap. The dependence of some of the states on the ring's magnetic flux provides a mechanism to control the entanglement between the two SSH edge fermion modes. The concurrence between the edge modes depends periodically on the magnetic flux. In the deep topological zone, for appropriate values of the flux, the concurrence reaches the extreme values of 0 and 1, corresponding to vanishing entanglement and to maximum entanglement. Therefore, the QR-SSH system offers a tuning mechanism that can be used either as an entanglement modulator or as an entanglement switch.Fil: Garrido, Alejandro Patricio. Universidad Católica del Norte; Chile. Universidad Técnica Federico Santa María; ChileFil: Plastino, Ángel Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Ladrón de Guevara, María Loreto. Universidad Católica del Norte; ChileFil: Apel, Víctor Marcelo. Universidad Católica del Norte; Chil