1,885 research outputs found

    Yield Of Beet Cultivars Under Fertigation Management And Salinity Control In A Protected Environment

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    Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In a protected environment, applying excess fertilizer and using water with soluble salts cause soil salinization due to the absence of lixiviation by precipitation. Among commercial vegetables, beets (Beta vulgaris L.) have good tolerance to soil salinity, being a good option for growth under these conditions. An experimental study was carried out in the municipality of Botucatu, São Paulo, Brazil. The treatment consisted of a combination of the following factors: initial soil salinity (1, 3, 6, 9, and 12 dS m-1), fertigation management (traditional vs. control of ion concentration of the soil solution) and two beet cultivars (‘Early Wonder’ and ‘Itapuã’) in a 5 × 2 × 2 factorial design. A randomized block design with four replicates was adopted, totaling 80 experimental plots. The total fresh weight of aerial part and root, total dry weight of aerial part and root, and water use efficiency (WUE) were assessed. Significant differences were found between fertigation management practices and salinity levels proposed. ‘Itapuã’ showed better yield and WUE for electrical conductivity (EC) below 6 dS m-1. Under traditional fertigation, root yield response fits a linear model with a decrease of 11.365 g (‘Early Wonder’) and 11.025 g (‘Itapuã’) for each unit increase in EC. Under controlled fertigation, the best-fit model was quadratic, with maximum estimates of 248.83 g for ‘Early Wonder’ and 258.52 g for ‘Itapuã’. Controlling EC of the soil solution had a positive effect, while salinity levels above 6 dS m-1 must be avoided. © 2016, Instituto de Investigaciones Agropecuarias, INIA. All rights reserved.764463470CAPES, Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

    ENSINO DE GEOMORFOLOGIA A DISTÂNCIA: ESTRATÉGIAS ADOTADAS NA LICENCIATURA EM GEOGRAFIA DO CEDERJ/UERJ

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    O ensino a distância (EAD) vem se consolidando como modo de ampliar o acesso à formação profissional no Brasil. A organização da disciplina Geomorfologia Geral para a Licenciatura EAD em Geografia do consórcio CEDERJ/UERJ partiu de pressupostos que reconheciam as limitações e possibilidades desta modalidade acadêmica. Serão aqui apresentadas estratégias usadas na produção de material didático consideradas bem sucedidas pela equipe profissional e pelos discentes ao longo de 2013 e 2014

    Effect of the North Equatorial Counter Current on the Generation and Propagation of Internal Solitary Waves Off the Amazon Shelf (SAR Observations)

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    . Synthetic aperture radar (SAR) imagery from the Amazon shelf break region in the tropical west Atlantic reveals for the first time the two-dimensional horizontal structure of an intense Internal Solitary Wave (ISW) field, whose first surface manifestations are detected several hundred kilometres away from the nearest forcing bathymetry. Composite maps and an energy budget analysis (provided from the Hybrid Coordinate Ocean Model – HYCOM) help to identify two major ISW pathways emanating from the steep slopes of a small promontory (or headland) near 44◦ W and 0 ◦ N, which are seen to extend for over 500 km into the open ocean. Further analysis in the SAR reveals propagation speeds above 3 m s−1 , which are amongst the fastest ever recorded. The main characteristics of the ISWs are further discussed based on a statistical analysis, and seasonal variability is found for one of the ISW sources. This seasonal variability is discussed in light of the North Equatorial Counter Current. The remote appearance of the ISW sea surface manifestations is explained by a late disintegration of the internal tide (IT), which is further investigated based on the SAR data and climatological monthly means (for stratification and currents). Acknowledging the possibility of a late disintegration of the IT may help explain the remote-sensing views of other ISWs in the world’s oceans

    Numerical simulation of boiling during the quenching process

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    National audienceDuring the thermal modelling of the quenching process, different stages of boiling need to be treated, from nucleate boiling to generation and growth of a vapour film. The interface between each phase flow is determined using a level set method. Surface tension is evaluated using the continuum surface force. The proposed approach demonstrates the capability of the model to simulate detachment of a single bubble and the generation of film vapour from a heated source. A comparison between numerical and experimental results shows a good agreement.br/>See http://hal.archives-ouvertes.fr/docs/00/59/26/76/ANNEX/r_71D43983.pd

    How to determine the parameters of polymer crystallization for modeling the injection-molding process?

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    International audienceTo understand the relationship between 'polymers-processing conditions-structures-properties', crystallization is one of the major concerned phenomena. A general crystallization model derived from Avrami's work has been developed at CEMEF and implemented into a 3D finite element code for injection-molding named Rem3D®. It gives a precise description of the crystallization event, allows the determination of morphological features, but it requires a reliable determination of the crystallization parameters. The experimental procedures adopted to capture relevant experimental parameters are presented. The determination of overall kinetics, density of potential nuclei with activation frequency of nuclei into crystalline entities, and growth rate is carried out with polarized optical microscopy (POM) and is supplemented by small angle light scattering (SALS). The treatment of data is performed by a classical method or using an inverse genetic algorithm method to extract the parameters necessary to our model. The 2D simulation of the crystallization, illustrated with Rem3D®, reproduces the experimental reality quite accurately, in the case of an isothermal and static crystallization. This is applied to two polymers, an isotactic homopolymer polypropylene iPP and a polyether-block amide PEBAX®

    The role of natural regeneration to ecosystem services provision and habitat availability: a case study in the Brazilian Atlantic Forest

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    Natural regeneration provides multiple benefits to nature and human societies, and can play a major role in global and national restoration targets. However, these benefits are context specific and impacted by both biophysical and socioeconomic heterogeneity across landscapes. Here we investigate the benefits of natural regeneration for climate change mitigation, sediment retention and biodiversity conservation in a spatially explicit way at very high resolution for a region within the global biodiversity hotspot of the Atlantic Forest. We classified current land-use cover in the region and simulated a natural regeneration scenario in abandoned pasturelands, areas where potential conflicts with agricultural production would be minimized and where some early stage regeneration is already occurring. We then modelled changes in biophysical functions for climate change mitigation and sediment retention, and performed an economic valuation of both ecosystem services. We also modelled how land-use changes affect habitat availability for species. We found that natural regeneration can provide significant ecological and social benefits. Economic values of climate change mitigation and sediment retention alone could completely compensate for the opportunity costs of agricultural production over 20 years. Habitat availability is improved for three species with different dispersal abilities, although by different magnitudes. Improving the understanding of how costs and benefits of natural regeneration are distributed can be useful to design incentive structures that bring farmers’ decision making more in line with societal benefits. This alignment is crucial for natural regeneration to fulfil its potential as a large-scale solution for pressing local and global environmental challenges

    How the Charge Can Affect the Formation of Gravastars

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    In recent work we physically interpreted a special gravastar solution characterized by a zero Schwarzschild mass. In fact, in that case, none gravastar was formed and the shell expanded, leaving behind a de Sitter or a Minkowski spacetime, or collapsed without forming an event horizon, originating what we called a massive non-gravitational object. This object has two components of non zero mass but the exterior spacetime is Minkowski or de Sitter. One of the component is a massive thin shell and the other one is de Sitter spacetime inside. The total mass of this object is zero Schwarzschild mass, which characterizes an exterior vacuum spacetime. Here, we extend this study to the case where we have a charged shell. Now, the exterior is a Reissner-Nordstr\"om spacetime and, depending on the parameter ω=1−γ\omega=1-\gamma of the equation of state of the shell, and the charge, a gravastar structure can be formed. We have found that the presence of the charge contributes to the stability of the gravastar, if the charge is greater than a critical value. Otherwise, a massive non-gravitational object is formed for small charges.Comment: 17 pages and 7 figures, several typos corrected, accepted for publication in JCA

    Thermofield Dynamics and Casimir Effect for Fermions

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    A generalization of the Bogoliubov transformation is developed to describe a space compactified fermionic field. The method is the fermionic counterpart of the formalism introduced earlier for bosons (J. C. da Silva, A. Matos Neto, F. C. Khanna and A. E. Santana, Phys. Rev. A 66 (2002) 052101), and is based on the thermofield dynamics approach. We analyse the energy-momentum tensor for the Casimir effect of a free massless fermion field in a dd-dimensional box at finite temperature. As a particular case the Casimir energy and pressure for the field confined in a 3-dimensional parallelepiped box are calculated. It is found that the attractive or repulsive nature of the Casimir pressure on opposite faces changes depending on the relative magnitude of the edges. We also determine the temperature at which the Casimir pressure in a cubic boc changes sign and estimate its value when the edge of the cybe is of the order of confining lengths for baryons.Comment: 21 pages, 3 figures, to appear in Annals of Physic

    Getting beta-alpha without penguins

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    Oscillation effects in B0 -> Ks D0 and related processes are considered to determine delta=beta-alpha+pi. We suggest that D0 decays to CP eigenstates used in concert with inclusive D0 decays provide a powerful method for determining delta cleanly i.e. without any complication from penguin processes. The CP asymmetry is expected to be <=40% for D0 decays to non-CP eigenstates and <=80% for decays to CP eigenstates. This method can lead to a fairly accurate determination of delta with O(10^8-10^9) B-mesons.Comment: 4 pages 1 figure; Version 2: minor changes; references added; Some changes in response to Referee Comment

    Non-linear Liouville and Shr\"odinger equations in phase space

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    Unitary representations of the Galilei group are studied in phase space, in order to describe classical and quantum systems. Conditions to write in general form the generator of time translation and Lagrangians in phase space are then established. In the classical case, Galilean invariance provides conditions for writing the Liouville operator and Lagrangian for non-linear systems. We analyze, as an example, a generalized kinetic equation where the collision term is local and non-linear. The quantum counter-part of such unitary representations are developed by using the Moyal (or star) product. Then a non-linear Schr\"odinger equation in phase space is derived and analyzed. In this case, an association with the Wigner formalism is established, which provides a physical interpretation for the formalism
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