Ensayo de marcado-recaptura para la estimación de tasas de crecimiento en peces arrecifales del género acanthurus en el caribe colombiano

Se empleó la técnica de marcado y recaptura en peces marinos para establecer tasas de crecimiento mensual y relaciones longitud- peso para las tres especies del género Acanthurus, durante las épocas de sequía (surgencia) y lluvias en el área de Punta de Betín, Santa Marta, Colombia.The mark and recapture technique was used with the three species of the genus Acanthurus in order to establish growth rates and length-weight relationships during the upwelling and rainy seasons in the area of Punta de Betín, Santa Marta, Colombia

Krill as a central node for iron cycling in the Southern Ocean

In order to establish the potential role of Antarctic krill (Euphausia superba) in the recycling of bioactive elements, we have quantified the release of iron, phosphate, and ammonia by these organisms along the Antarctic Peninsula sector of the Southern Ocean. The experimental results suggested that the presence of krill has a significant impact on ambient iron concentrations, as large amounts of this trace element were released by the krill (22-689 nmol Fe g Dry Weight-1 h-1, equivalent to 0.2 to 4.3 nmol Fe L-1 d-1). Half of this iron release occurred within the first hour of the experiment, and differences in iron and phosphate release rates (3.1 to 14.0 μmol PO4 3- g DW-1 h-1) seemed to reflect differences in food availability. These results identify krill as a major node in iron cycling in the Southern Ocean, potentially influencing iron residence time in the upper water column of this region. Copyright 2007 by the American Geophysical Union.Peer Reviewe

A methodology for shipping noise field calibration and excess noise estimation: the Azores case study

Economic globalization and the continuous search for food, energy and raw materials led to an estimated 3 dB/decade increase of ocean noise intensity. Determining the level of anthropogenic noise, the so-called excess noise, and building identifiable meaningful indicators for supporting marine management policies currently requires extensive observation data and computer modeling. For modeling purposes, in this study, anthropogenic noise was reduced to shipping traffic drawn from Automatic Identification System data, and environmental sound was attributed to surface wind only. Data-model comparison allowed introducing a methodology for simple model calibration and estimate excess noise. This methodology was tested on acoustic recordings performed in June 2018 at three locations to the southwest of Faial-Pico Islands in the Azores archipelago. The results show that field-calibrated excess noise sound maps are in line with the shipping distribution in the area, revealing a number of potentially marine life-threatening hotspots. Excess noise addresses the need for a quantifiable measure of ocean noise only and therefore offers a basis for building suitable continuous anthropogenic noise pollution indicators.info:eu-repo/semantics/publishedVersio

Measurement of 1323 and 1487 keV resonances in 15N({\alpha}, {\gamma})19F with the recoil separator ERNA

The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the {\alpha} and {\gamma} channels. We show that a direct measurement of the cross section of the ^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha} of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} . The revision of the widths of the two more relevant broad resonances in the 15N({\alpha},{\gamma})19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.Comment: 8 pages, 11 figures. Accepted for publication in PR

A unified power converter for solar PV and energy storage in dc microgrids

This paper deals with the development and experimental validation of a unified power converter for application in dc microgrids, contemplating the inclusion of solar photovoltaic (PV) panels and energy storage systems (ESS), namely batteries. Considering the limitations presented by the current structure of the power grid, mostly highlighted by the accentuated integration of emerging technologies (ESS, renewables, electric vehicles, and electrical appliances that natively operate in dc), it is extremely pertinent to adopt new topologies, architectures, and paradigms. In particular, decentralized power systems, unified topologies, and correspondent control algorithms are representative of a new trend towards a reduction in the number of power converters. Thus, the developed solution is designed to operaSAVE-15te at a nominal power of 3.6 kW, with a switching frequency of 100 kHz, and in four operation modes concerning power flow: (i) solar PV panels to batteries (PV2B); (ii) solar PV panels to dc grid (PV2G); (iii) batteries to dc grid (B2G); (iv) dc grid to batteries (G2B). Moreover, a dual active bridge converter guarantees galvanic isolation, while two back-end dc–dc converters are responsible for interfacing solar PV panels and batteries. The experimental validation of the proposed unified power converter proves its application value to self-consumption production units.This work has been supported by FCT—Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the MEGASOLAR Project POCI-01-0247-FEDER-047220

The Role of Oxidative Stress and Lipid Peroxidation in Ventricular Remodeling Induced by Tobacco Smoke Exposure after Myocardial Infarction

OBJECTIVE: To evaluate the roles of oxidative stress and lipid peroxidation in the ventricular remodeling that is induced by tobacco smoke exposure after myocardial infarction.METHODS: After induced myocardial infarction, rats were allocated into two groups: C (control, n=25) and ETS (exposed to tobacco smoke, n=24). After 6 months, survivors were submitted to echocardiogram and biochemical analyses.RESULTS: Rats in the ETS group showed higher diastolic (C = 1.52 +/- 0.4 mm(2), ETS = 1.95 +/- 0.4 mm(2); p=0.032) and systolic (C = 1.03 +/- 0.3, ETS = 1.36 +/- 0.4 mm(2)/g; p=0.049) ventricular areas, adjusted for body weight. The fractional area change was smaller in the ETS group (C = 30.3 +/- 10.1 %, ETS = 19.2 +/- 11.1 %; p=0.024) and E/A ratios were higher in ETS animals (C = 2.3 +/- 2.2, ETS = 5.1 +/- 2.5; p=0.037). ETS was also associated with a higher water percentage in the lung (C = 4.8 (4.3-4.8), ETS = 5.5 (5.3-5.6); p=0.013) as well as higher cardiac levels of reduced glutathione (C = 20.7 +/- 7.6 nmol/mg of protein, ETS = 40.7 +/- 12.7 nmol/mg of protein; p=0.037) and oxidized glutathione (C = 0.3 +/- 0.1 nmol/g of protein, ETS = 0.9 +/- 0.3 nmol/g of protein; p=0.008). No differences were observed in lipid hydroperoxide levels (C = 0.4 +/- 0.2 nmol/mg of tissue, ETS = 0.1 +/- 0.1 nmol/mg of tissue; p=0.08).CONCLUSION: In animals exposed to tobacco smoke, oxidative stress is associated with the intensification of ventricular re-remodeling after myocardial infarction