2,792 research outputs found

    Contribution of primary producers to mercury trophic transfer in estuarine ecosystems: Possible effects of eutrophication

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    http://www.sciencedirect.com/science/article/B6V6N-4V2X6WR-2/2/583d9d39ab618163fcc19f359dde856

    Desempenho fisiológico de genótipos de mandioca submetidos a estresse hídrico.

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    A mandioca (Manihot esculenta Crantz) é um dos mais importantes alimentos na dieta humana dos trópicos, onde é a quarta fonte de energia, depois do arroz, cana-de-açúcar e milho. Ela é comumente cultivada em áreas consideradas marginais para a maioria dos outros cultivos, com solos de baixa fertilidade e precipitação anual em torno de 800 mm, com uma estação seca de 4 a 6 meses, como nas regiões semi-áridas do Nordeste brasileiro, onde a tolerância à seca é um importante atributo para sobrevivência. Devido a sua inerente tolerância a ambientes estressantes, a mandioca é considerada uma cultura de segurança alimentar contra a fome, requerendo mínima utilização de insumos, tornando-a um importante cultivo em áreas propensas à seca das regiões tropicais e subtropicais da América Latina, África e Ásia.Fisiologia da produção. Resumo 165

    Respostas fisiológicas de genótipos de mandioca (Manihot esculenta Crantz) submetidos à deficiência hídrica.

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    A mandioca (Manihot esculenta Crantz) é uma cultura perene nativa da América Tropical e tem como centro de origem o Brasil Central (ALLEN, 2002). E como a maioria da diversidade biológica do gênero Manihot ocorre próximo ao estado de Goiás, acredita-se que o progenitor selvagem de mandioca e espécies afins evoluíram nas florestas do Cerrado do Brasil Central (EL-SHARKAWY, 2004). Durante o período de crescimento e desenvolvimento, as plantas são frequentemente submetidas a condições externas adversas, o que resulta em estresses, e estes podem afetam de maneira desfavorável a produtividade das plantas. Tais estresses podem ser bióticos (resultante da ação de microorganismos) e abióticos (resultantes do excesso ou falta de algum fator físico ou químico do meio ambiente), e estes podem ocorrer de forma isolada ou conjunta (GONÇALVES, 2008). A salinidade, o estresse hídrico (deficiência ou excesso), nutrientes minerais (deficiência ou excesso) se destacam como estresses abióticos ( BARBOSA, 2010). O objetivo deste trabalho foi o de avaliar o crescimento inicial de seis genótipos mandioca, sob condições de deficiência hídrica

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

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    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

    Relevance of additive and non-additive genetic relatedness for genomic prediction in rice population under recurrent selection breeding

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    In genomic recurrent selection programs of self-pollinated crops, additive genetic effects (breeding values) are effectively relevant for selection of superior progenies as new parents. However, considering additive and nonadditive genetic effects can improve the prediction of genome-enhanced breeding values (GEBV) of progenies, for quantitative traits. In this study, we assessed the magnitude of additive and nonadditive genetic variances for eight key traits in a rice population under recurrent selection, using marker-based relationship matrices. We then assessed the goodness-to-fit, bias, stability and accuracy of prediction for breeding values and total (additive plus nonadditive) genetic values, in five genomic best linear unbiased prediction (GBLUP) models, ignoring or not nonadditive genetic effects. The models were compared using 6174 single nucleotide polymorphisms (SNP) markers from 174 S1:3 progenies evaluated in field yield trial. We found dominance effects accounting for a substantial proportion of the total genetic variance for the key traits in rice, especially for days to flowering. In average of the traits, the component of variance additive, dominance, and epistatic contributed to about 34%, 14% and 9% for phenotypic variance. Additive genomic models, ignoring nonadditive genetic effects, showed better fit to the data and lower bias, in addition to greater stability and accuracy for predict GEBV of progenies. These results improve our understanding of the genetic architecture of the key traits in rice, evaluated in early-generation testing. Clearly, this study highlighted the advantages of additive models using genome-wide information, for genomic prediction applied to recurrent selection in a self-pollinated crop

    Persistência de dois inseticidas ao parasitoide de moscas-dasfrutas, Diachasmimorpha longicaudata (Hymenoptera: Braconidae).

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    O presente trabalho objetivou avaliar a persistência de dois inseticidas utilizados para o controle de Ceratitis capitata, espinosade e etofenproxi, sobre adultos de Diachasmimorpha longicaudataSICONBIOL 2013

    J-PLUS: Identification of low-metallicity stars with artificial neural networks using SPHINX

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    We present a new methodology for the estimation of stellar atmospheric parameters from narrow- and intermediate-band photometry of the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a method for target pre-selection of low-metallicity stars for follow-up spectroscopic studies. Photometric metallicity estimates for stars in the globular cluster M15 are determined using this method. By development of a neural-network-based photometry pipeline, we aim to produce estimates of effective temperature, TeffT_{\rm eff}, and metallicity, [Fe/H], for a large subset of stars in the J-PLUS footprint. The Stellar Photometric Index Network Explorer, SPHINX, is developed to produce estimates of TeffT_{\rm eff} and [Fe/H], after training on a combination of J-PLUS photometric inputs and synthetic magnitudes computed for medium-resolution (R ~ 2000) spectra of the Sloan Digital Sky Survey. This methodology is applied to J-PLUS photometry of the globular cluster M15. Effective temperature estimates made with J-PLUS Early Data Release photometry exhibit low scatter, \sigma(TeffT_{\rm eff}) = 91 K, over the temperature range 4500 < TeffT_{\rm eff} (K) < 8500. For stars from the J-PLUS First Data Release with 4500 < TeffT_{\rm eff} (K) < 6200, 85 ±\pm 3% of stars known to have [Fe/H] <-2.0 are recovered by SPHINX. A mean metallicity of [Fe/H]=-2.32 ±\pm 0.01, with a residual spread of 0.3 dex, is determined for M15 using J-PLUS photometry of 664 likely cluster members. We confirm the performance of SPHINX within the ranges specified, and verify its utility as a stand-alone tool for photometric estimation of effective temperature and metallicity, and for pre-selection of metal-poor spectroscopic targets.Comment: 18 pages, 12 figure

    J-PLUS: analysis of the intracluster light in the Coma cluster

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    The intracluster light (ICL) is a luminous component of galaxy clusters composed of stars that are gravitationally bound to the cluster potential but do not belong to the individual galaxies. Previous studies of the ICL have shown that its formation and evolution are intimately linked to the evolutionary stage of the cluster. Thus, the analysis of the ICL in the Coma cluster will give insights into the main processes driving the dynamics in this highly complex system. Using a recently developed technique, we measure the ICL fraction in Coma at several wavelengths, using the J-PLUS unique filter system. The combination of narrow- and broadband filters provides valuable information on the dynamical state of the cluster, the ICL stellar types, and the morphology of the diffuse light. We use the Chebyshev-Fourier Intracluster Light Estimator (CICLE) to disentangle the ICL from the light of the galaxies, and to robustly measure the ICL fraction in seven J-PLUS filters. We obtain the ICL fraction distribution of the Coma cluster at different optical wavelengths, which varies from 7%21%\sim 7\%-21\%, showing the highest values in the narrowband filters J0395, J0410, and J0430. This ICL fraction excess is distinctive pattern recently observed in dynamically active clusters (mergers), indicating a higher amount of bluer stars in the ICL compared to the cluster galaxies. Both the high ICL fractions and the excess in the bluer filters are indicative of a merging state. The presence of younger/lower-metallicity stars the ICL suggests that the main mechanism of ICL formation for the Coma cluster is the stripping of the stars in the outskirts of infalling galaxies and, possibly, the disruption of dwarf galaxies during past/ongoing mergers.Comment: 10 pages, 3 figures, 1 table. Accepted for publication in A&

    Concurrent agreement between an anthropometric model to predict thigh volume and dual-energy X-Ray absorptiometry assessment in female volleyball players aged 14-18 years

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    A variety of performance outputs are strongly determined by lower limbs volume and composition in children and adolescents. The current study aimed to examine the validity of thigh volume (TV) estimated by anthropometry in late adolescent female volleyball players. Dual-energy X-ray absorptiometry (DXA) measures were used as the reference method. Total and regional body composition was assessed with a Lunar DPX NT/Pro/MD+/Duo/Bravo scanner in a cross-sectional sample of 42 Portuguese female volleyball players aged 14-18 years (165.2 ± 0.9 cm; 61.1 ± 1.4 kg). TV was estimated with the reference method (TV-DXA) and with the anthropometric method (TV-ANTH). Agreement between procedures was assessed with Deming regression. The analysis also considered a calibration of the anthropometric approach. The equation that best predicted TV-DXA was: -0.899 + 0.876 × log10 (body mass) + 0.113 × log10 (TV-ANTH). This new model (NM) was validated using the predicted residual sum of squares (PRESS) method (R2PRESS = 0.838). Correlation between the reference method and the NM was 0.934 (95%CI: 0.880-0.964, Sy∙x = 0.325 L). A new and accurate anthropometric method to estimate TV in adolescent female volleyball players was obtained from the equation of Jones and Pearson alongside with adjustments for body mass.info:eu-repo/semantics/publishedVersio
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