Afterglows from precursors in Gamma Ray Bursts. Application to the optical afterglow of GRB 091024

About 15% of Gamma Ray Bursts have precursors, i.e. emission episodes preceding the main event, whose spectral and temporal properties are similar to the main emission. We propose that precursors have their own fireball, producing afterglow emission due to the dissipation of the kinetic energy via external shock. In the time lapse between the precursor and the main event, we assume that the central engine is not completely turned off, but it continues to eject relativistic material at a smaller rate, whose emission is below the background level. The precursor fireball generates a first afterglow by the interaction with the external circumburst medium. Matter injected by the central engine during the "quasi-quiescent" phase replenishes the external medium with material in relativistic motion. The fireball corresponding to the main prompt emission episode crashes with this moving material, producing a second afterglow, and finally catches up and merges with the first precursor fireball. We apply this new model to GRB 091024, an event with a precursor in the prompt light curve and two well defined bumps in the optical afterglow, obtaining an excellent agreement with the existing data.Comment: 11 pages, 6 figures, 3 tables. Accepted for publication in MNRAS, Main Journa

Ocorrência de tefritídeos em Passiflora caerulea em Pelotas e Capão do Leão, RS, Brasil.

O objetivo do estudo foi determinar a(s) espécie(s) de tefritídeo(s) coletado(s) em P. caerulea

Primeiro relato de Drosophila suzukii (Diptera: Drosophilidae) em frutos de araçá e pitanga em municípios da região sul do Rio Grande do Sul, Brasil.

O objetivo do estudo foi relatar a ocorrência de D. suzukii em frutíferas mirtáceas em municípios da região sul do Rio Grande do Sul, Brasil

Rate constant for the reaction of hydroxyl radical with formaldehyde over the temperature range 228-362 K

Absolute rate constants for the reaction OH ? H2CO measured over the temperature range 228-362 K using the flash photolysis-resonance fluorescence technique are given. The results are independent of variations in H2CO concentration, total pressure Ar concentration, and flash intensity (i.e., initial OH concentration). The rate constant is found to be invariant with temperature in this range, the best representation being k sub 1 = (1.05 ? or - 0.11) x 10 to the 11th power cu cm molecule(-1) s(-1) where the error is two standard deviations. This result is compared with previous absolute and relative determinations of k sub 1. The reaction is also discussed from a theoretical point of view

Equation of state of two--dimensional 3^3He at zero temperature

We have performed a Quantum Monte Carlo study of a two-dimensional bulk sample of interacting 1/2-spin structureless fermions, a model of $^3$He adsorbed on a variety of preplated graphite substrates. We have computed the equation of state and the polarization energy using both the standard fixed-node approximate technique and a formally exact methodology, relying on bosonic imaginary-time correlation functions of operators suitably chosen in order to extract fermionic energies. As the density increases, the fixed-node approximation predicts a transition to an itinerant ferromagnetic fluid, whereas the unbiased methodology indicates that the paramagnetic fluid is the stable phase until crystallization takes place. We find that two-dimensional $^3$He at zero temperature crystallizes from the paramagnetic fluid at a density of 0.061 \AA$^{-2}$ with a narrow coexistence region of about 0.002 \AA$^{-2}$. Remarkably, the spin susceptibility turns out in very good agreement with experiments.Comment: 7 pages, 7 figure

Upper atmosphere research: Reaction rate and optical measurements

The objective is to provide photochemical, kinetic, and spectroscopic information necessary for photochemical models of the Earth's upper atmosphere and to examine reactions or reactants not presently in the models to either confirm the correctness of their exclusion or provide evidence to justify future inclusion in the models. New initiatives are being taken in technique development (many of them laser based) and in the application of established techniques to address gaps in the photochemical/kinetic data base, as well as to provide increasingly reliable information

Towards an English-Spanish version of the Comprehensive Transboundary International Water Quality Management Agreement

The aim of this communication is to discuss strategies for, and progress achieved in transboundary water quality management. The Comprehensive Transboundary Water Quality Management Agreement with Guidelines for Development of a Management Plan, Standards, and Criteria. (ASCE/EWRI 33-09). The purpose of this Agreement is to provide a framework for governments to adopt or modify comprehensive water quality planning and management mechanisms of shared water resources. The Spanish version of the Agreement, completed by the ASCE/EWRI Border International Water Quality Standards Committee (BIWQ SC) Translation Ad Hoc Group, allows the scope of this Framework along and across Spanish speaking political boundaries. This version includes some updates balloted by the Committee to ensure that all factors involved in the sharing and management of water resources are considered in the development of the Agreement, so that it can accommodate the current realities of the boundary governments. The original version of the Agreement (ASCE/EWRI 33-09) is being revised and will be replaced in the coming months by the ASCE/EWRI 33-16. The ASCE/EWRI 33-16 contains the most current model for comprehensive water quality planning and management of shared water resources. It underlines the importance of governmental cooperation to alleviate causes of present and future disagreement and promotes the development of common strategies to use, manage and protect shared water resources. The ASCE/EWRI 33-16 is an agreement to be used, modified, and enhanced through every government on an international scale and in a variety of geopolitical settings

The reaction Cl + H2CO yields HCl + HCO: Decreased sensitivity of stratospheric ozone to chlorine perturbations

The absolute rate constant for the reaction Cl + H2CO yields HCl + HCO was determined by the flash-photolysis resonance fluorescence method to be 7.5 plus or minus 0.9 (2 sigma) times 10 to the minus 11th power cu cm/molecule sec at 298 K and to have a negligible temperature dependence. This rate which is more than 2000 times faster than the rate of Cl + CH4 indicates that formaldehyde (H2CO) will compete significantly with methane (CH4) for the conversion of active chlorine in the stratosphere to the inactive reservoir HCl. Chlorine will thus be a less efficient destroyer of stratosphere ozone than previously believed. Ambient stratospheric ozone will depend less on the ambient chlorine amount and the predicted response to chlorine perturbations will be lessened. One-dimensional eddy-diffusion photochemical model calculations indicate a factor of 1.1 less sensitivity to chlorine than recently reported. For a steady-state CFM release at 1975 rates (750,000 tons/year) the eventual ozone depletion is now calculated to be 14%

Predictive Maintenance of Floating Offshore Wind Turbine Mooring Lines using Deep Neural Networks

The recent massive deployment of onshore wind farms has caused controversy to arise mainly around the issues of land occupation, noise and visual pollution and impact on wildlife. Fixed offshore turbines, albeit beneficial in those aspects, become economically unfeasible when installed far away from coastlines. The possibility of installing floating offshore wind turbines is currently hindered by their excessive operation and maintenance costs. We have developed a comprehensive model to help companies plan their operations in advance by detecting failure in mooring lines in almost real time using supervised deep learning techniques. Given the lack of real data, we have coupled numerical methods and OpenFAST simulations to build a dataset containing the displacements and rotations of a turbine's floating platform across all directions. These time series and their corresponding frequency spectra are used to obtain a set of key statistical parameters, including means and standard deviations, peak frequencies, and several relevant momenta. We have designed and trained a Deep Neural Network to understand and distinguish amongst a series of common failure modes for mooring lines considering a range of metocean and structural conditions. We have obtained promising results when monitoring severe changes in the line's mass and damping using short time spans, achieving a 95.7% validation accuracy when detecting severe biofouling failure.N Gorostidi has received funding from the Spanish Ministry of Science and Innovation project DEEPINVERSE, with reference PID2019-108111RB-I00 (FEDER/AEI). V Nava has received funding from the project IA4TES - Inteligencia Artificial para la Transición Energética Sostenible funded by Ministry of Economic Affairs and Digital Transformation (MIA.2021.M04.0008); the “BCAM Severo Ochoa” accreditation of excellence (SEV-2017-0718); and the Basque Government through the BERC 2022-2025 program, the Elkartek project EXPERTIA (KK-2021/00048)