Antioxidant activity and acute toxicity of Neoglaziovia variegata (Bromeliaceae)

Antioxidant activities of Neoglaziovia variegata were evaluated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and β-carotene-linoleic acid bleaching and was compared with ascorbic acid, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The total phenolics content of the extracts was determined by the Folin-Ciocalteu method. Total flavonoid was also determined. The most significant total phenolic content was of 543.50 ± 9.38 mg of gallic acid equivalent/g for ethyl acetate extract (AcOEt), which presented the best antioxidant activity (IC50 5.08 ± 0.20 μg/ml) for DPPH scavenging. The acute toxicity of Nv-EtOH was performed 2.0 g/kg intraperitoneally and 5.0 g/kg orally in mice. No mortality and no toxicity signs were observed, indicating low toxicity of the extract. Blood was removed after 14 days for laboratory analysis of hematological and biochemical parameters. Alterations of aspartate aminotransferase (AST) and creatinine were observed. The data obtained showed that the doses induced microscopic alterations in the liver and kidney. In conclusion, the Nv-EtOH can be considered of low toxicity.Keywords: Antioxidant activity, acute toxicity, Neoglaziovia variegata, Bromeliacea

Reverse and Forward Engineering of Local Voltage Control in Distribution Networks

The increasing penetration of renewable and distributed energy resources in distribution networks calls for real-time and distributed voltage control. In this paper we investigate local Volt/VAR control with a general class of control functions, and show that the power system dynamics with non-incremental local voltage control can be seen as distributed algorithm for solving a well-defined optimization problem (reverse engineering). The reverse engineering further reveals a fundamental limitation of the non-incremental voltage control: the convergence condition is restrictive and prevents better voltage regulation at equilibrium. This motivates us to design two incremental local voltage control schemes based on the subgradient and pseudo-gradient algorithms respectively for solving the same optimization problem (forward engineering). The new control schemes decouple the dynamical property from the equilibrium property, and have much less restrictive convergence conditions. This work presents another step towards developing a new foundation -- network dynamics as optimization algorithms -- for distributed realtime control and optimization of future power networks

Las comunidades profesionales de aprendizaje y su incidencia en el desempeño docente en la Institución Educativa Emblemática N° 1070 Melitón Carvajal, de la UGEL 03 - Lima

El estudio realizado, tiene como título: “Las comunidades profesionales de aprendizaje y su incidencia en el desempeño docente en la Institución Educativa Emblemática N° 1070 Melitón Carvajal de Lince, el problema general planteado fue, ¿Cuál es la incidencia de las comunidades profesionales de aprendizaje en el desempeño docente en la I.E.E. N° 1070 Melitón Carvajal?, y tuvo como objetivo: determinar el nivel de incidencia de las comunidades profesionales de aprendizaje en el desempeño docente en la I.E.E. N° 1070 Melitón Carvajal. La investigación obedece a un diseño no experimental de corte transeccional o transversal y correlacional/causal; asimismo, el método utilizado es hipotético deductivo, con una población compuesta por 60 docentes que constituye la muestra censal, a quienes se les aplicó dos cuestionarios para medir el nivel de desarrollo de las comunidades profesionales de aprendizaje y el nivel de desempeño docente. Luego de la recolección de los datos, el procesamiento de la información y el análisis de los datos descriptivos e inferenciales, mediante el Pseudo coeficiente de determinación de las variables se llegó a la siguiente conclusión: Existe una relación directa y significativa entre las comunidades profesionales de aprendizaje y el desempeño docente en la I.E.E. N° 1070 Melitón Carvajal del distrito de Lince, 2018, habiéndose obtenido un R-cuadrado de Nagelkerke igual a 0,762 y un p.valor igual a 0,000

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements