329 research outputs found

    Análise do Programa de regularização ambiental: desafios e oportunidades para restauração ecológica em pequenos imóveis rurais

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    Tese. ( Doutorado em em Ciências Ambientais e Florestais, Área de Concentração em Conservação da Natureza) - Universidade Federal Rural do Rio de Janeiro, Seropédica, 2020. Sob a Orientação do Professor Sergio Miana de Faria e Coorientação dos Professores Vanessa Maria Basso Jerônimo Boelsums Barreto Sansevero

    Induction and growth curve of calli from leaf and nodal explants of genipap.

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    The aim of this study was to determine the effect of the auxin 2,4-D (2,4-dichlorophenoxyacetic) in calli formation from leaf and nodal segments of genipap and to characterize its growth curve. Explants obtained from shoots previously established from in vitro seedlings were used for calli induction. The experimental design was completely randomized in a 3x5x2 factorial with three accessions (NB, SA, SAL), five concentrations of 2,4-D (0.0; 2.0; 4.0, 6.0 or 8.0 mg L-1) and two times of measurement for calli fresh weight (30 and 60 days). There was callus formation in all treatments tested. It was observed that the best response for callus induction from leaf segments was with 2.0 mg L-1 of 2,4-D. For the nodal segment, the response among the accessions was different due to 2,4-D concentrations. The growth curve was plotted according to the fresh weight of callus obtained at intervals of 10 days up to 60 days. Through the established growth curve, the nodal-derived calli from accession SA should be transferred to a new medium, after 40 days of culture

    The dust properties and physical conditions of the interstellar medium in the LMC massive star forming complex N11

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    We combine Spitzer and Herschel data of the star-forming region N11 in the Large Magellanic Cloud to produce detailed maps of the dust properties in the complex and study their variations with the ISM conditions. We also compare APEX/LABOCA 870um observations with our model predictions in order to decompose the 870um emission into dust and non-dust (free-free emission and CO(3-2) line) contributions. We find that in N11, the 870um can be fully accounted for by these 3 components. The dust surface density map of N11 is combined with HI and CO observations to study local variations in the gas-to-dust mass ratios. Our analysis leads to values lower than those expected from the LMC low-metallicity as well as to a decrease of the gas-to-dust mass ratio with the dust surface density. We explore potential hypotheses that could explain the low observed gas-to-dust mass ratios (variations in the XCO factor, presence of CO-dark gas or of optically thick HI or variations in the dust abundance in the dense regions). We finally decompose the local SEDs using a Principal Component Analysis (i.e. with no a priori assumption on the dust composition in the complex). Our results lead to a promising decomposition of the local SEDs in various dust components (hot, warm, cold) coherent with that expected for the region. Further analysis on a larger sample of galaxies will follow in order to understand how unique this decomposition is or how it evolves from one environment to another.Comment: 24 pages, 16 figures, accepted for publication in MNRA

    Seletividade de herbicidas para a cultura do tomate para processamento industrial híbrido BRS Sena.

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    Objetivou-se com este trabalho avaliar a seletividade de herbicidas para a cultura do tomate para processamentoindustrial híbrido BRS Sena.Trabalho 1

    The Power of Two Choices in Distributed Voting

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    Distributed voting is a fundamental topic in distributed computing. In pull voting, in each step every vertex chooses a neighbour uniformly at random, and adopts its opinion. The voting is completed when all vertices hold the same opinion. On many graph classes including regular graphs, pull voting requires Θ(n)\Theta(n) expected steps to complete, even if initially there are only two distinct opinions. In this paper we consider a related process which we call two-sample voting: every vertex chooses two random neighbours in each step. If the opinions of these neighbours coincide, then the vertex revises its opinion according to the chosen sample. Otherwise, it keeps its own opinion. We consider the performance of this process in the case where two different opinions reside on vertices of some (arbitrary) sets AA and BB, respectively. Here, A+B=n|A| + |B| = n is the number of vertices of the graph. We show that there is a constant KK such that if the initial imbalance between the two opinions is ?ν0=(AB)/nK(1/d)+(d/n)\nu_0 = (|A| - |B|)/n \geq K \sqrt{(1/d) + (d/n)}, then with high probability two sample voting completes in a random dd regular graph in O(logn)O(\log n) steps and the initial majority opinion wins. We also show the same performance for any regular graph, if ν0Kλ2\nu_0 \geq K \lambda_2 where λ2\lambda_2 is the second largest eigenvalue of the transition matrix. In the graphs we consider, standard pull voting requires Ω(n)\Omega(n) steps, and the minority can still win with probability B/n|B|/n.Comment: 22 page
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