6,652 research outputs found

    Tomato growth and dry matter partitioning as a function of the irrigation water quality.

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    Neste estudo, foram avaliados o crescimento e a partição de matéria seca do tomateiro industrial cv IPA 6, cultivado sob irrigação com águas de diferentes condutividades elétricas (ECw) e proporções de sódio, em um delineamento fatorial 5x2, inteiramente casualizado. As mudas foram transplantadas para rizotrons e irrigadas diariamente, sendo as matérias secas da haste, ramos, inflorescências e frutos determinadas no final do ciclo da cultura. O solo foi retirado dos rizotrons em intervalos de 15 cm de profundidade, lavado e peneirado para determinação da matéria seca das raízes em camada do solo. A matéria seca da parte aérea foi reduzida em 6,9% por incremento unitário da salinidade

    Determining R-parity violating parameters from neutrino and LHC data

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    In supersymmetric models neutrino data can be explained by R-parity violating operators which violate lepton number by one unit. The so called bilinear model can account for the observed neutrino data and predicts at the same time several decay properties of the lightest supersymmetric particle. In this paper we discuss the expected precision to determine these parameters by combining neutrino and LHC data and discuss the most important observables. We show that one can expect a rather accurate determination of the underlying R-parity parameters assuming mSUGRA relations between the R-parity conserving ones and discuss briefly also the general MSSM as well as the expected accuracies in case of a prospective e+ e- linear collider. An important observation is that several parameters can only be determined up to relative signs or more generally relative phases.Comment: 13 pages, 13 figure

    Quasispecies distribution of Eigen model

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    We study sharp peak landscapes (SPL) of Eigen model from a new perspective about how the quasispecies distribute in the sequence space. To analyze the distribution more carefully, we bring forth two tools. One tool is the variance of Hamming distance of the sequences at a given generation. It not only offers us a different avenue for accurately locating the error threshold and illustrates how the configuration of the distribution varies with copying fidelity qq in the sequence space, but also divides the copying fidelity into three distinct regimes. The other tool is the similarity network of a certain Hamming distance d0d_{0}, by which we can get a visual and in-depth result about how the sequences distribute. We find that there are several local optima around the center (global optimum) in the distribution of the sequences reproduced near the threshold. Furthermore, it is interesting that the distribution of clustering coefficient C(k)C(k) follows lognormal distribution and the curve of clustering coefficient CC of the network versus d0d_{0} appears as linear behavior near the threshold.Comment: 13 pages, 6 figure

    Four Poynting Theorems

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    The Poynting vector is an invaluable tool for analysing electromagnetic problems. However, even a rigorous stress-energy tensor approach can still leave us with the question: is it best defined as \Vec{E} \cross \Vec{H} or as \Vec{D} \cross \Vec{B}? Typical electromagnetic treatments provide yet another perspective: they regard \Vec{E} \cross \Vec{B} as the appropriate definition, because \Vec{E} and \Vec{B} are taken to be the fundamental electromagnetic fields. The astute reader will even notice the fourth possible combination of fields: i.e. \Vec{D} \cross \Vec{H}. Faced with this diverse selection, we have decided to treat each possible flux vector on its merits, deriving its associated energy continuity equation but applying minimal restrictions to the allowed host media. We then discuss each form, and how it represents the response of the medium. Finally, we derive a propagation equation for each flux vector using a directional fields approach; a useful result which enables further interpretation of each flux and its interaction with the medium.Comment: 8 pages. Updated slightly from EJP versio

    Stochastic semiclassical fluctuations in Minkowski spacetime

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    The semiclassical Einstein-Langevin equations which describe the dynamics of stochastic perturbations of the metric induced by quantum stress-energy fluctuations of matter fields in a given state are considered on the background of the ground state of semiclassical gravity, namely, Minkowski spacetime and a scalar field in its vacuum state. The relevant equations are explicitly derived for massless and massive fields arbitrarily coupled to the curvature. In doing so, some semiclassical results, such as the expectation value of the stress-energy tensor to linear order in the metric perturbations and particle creation effects, are obtained. We then solve the equations and compute the two-point correlation functions for the linearized Einstein tensor and for the metric perturbations. In the conformal field case, explicit results are obtained. These results hint that gravitational fluctuations in stochastic semiclassical gravity have a ``non-perturbative'' behavior in some characteristic correlation lengths.Comment: 28 pages, RevTeX, no figure

    Relative water content in two grass cultivars in crop-livestock system in the State of Tocantins, Brazil.

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    In this presentation, we report the results of two grasses on Integrated Crop-Livestock System in the Tocantins Cerrado

    Non-equilibrium dynamics of a thermal plasma in a gravitational field

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    We introduce functional methods to study the non-equilibrium dynamics of a quantum massless scalar field at finite temperature in a gravitational field. We calculate the Close Time Path (CTP) effective action and, using its formal equivalence with the influence functional, derive the noise and dissipation kernels of the quantum open system in terms of quantities in thermodynamical equilibrium. Using this fact, we formally prove the existence of a Fluctuation-Dissipation Relation (FDR) at all temperatures between the quantum fluctuations of the plasma in thermal equilibrium and the energy dissipated by the external gravitational field. What is new is the identification of a stochastic source (noise) term arising from the quantum and thermal fluctuations in the plasma field, and the derivation of a Langevin-type equation which describes the non-equilibrium dynamics of the gravitational field influenced by the plasma. The back reaction of the plasma on the gravitational field is embodied in the FDR. From the CTP effective action the contribution of the quantum scalar field to the thermal graviton polarization tensor can also be derived and it is shown to agree with other techniques, most notably, Linear Response Theory (LRT). We show the connection between the LRT, which is applicable for near-equilibrium conditions and the functional methods used in this work which are useful for fully non-equilibrium conditions.Comment: Final version published in Phys. Rev.

    EXPERIMENTAL ANALYSIS OF AN S809 AIRFOIL

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    This paper looks into the aerodynamic behavior of an S809 airfoil commonly utilized in wind turbines. Tests were carried out to measure drag coefficient profiles under high speed flows of up to 14 m/s, with Reynolds numbers ranging between approximately Re = 11,400 and Re = 135,400. The prototype was fabricated on a fused deposition modeling machine with ABS Plus thermoplastic. Several tests were carried out in a wind tunnel. Angles of attack ranging from 0° to 20° were tested in increments of two degrees in both the clockwise (leading edge above trailing edge) and counterclockwise directions (leading edge below trailing edge). Drag coefficient versus Reynolds number curves were obtained for the aforementioned angles. The airfoil drag coefficient was found to decrease as the Reynolds number increased for all the angles of attack analyzed. Airfoil dynamic stall was determined (maximum lift coefficient). In the tests, dynamic stall occurred at approximately 16° clockwise. This value is in agreement with the literature

    Input-Output Relations in Optical Cavities: a Simple Point of View

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    In this work we present a very simple approach to input-output relations in optical cavities, limiting ourselves to one- and two-photon states of the field. After field quantization, we derive the non-unitary transformation between {\em Inside} and {\em Outside} annihilation and creation operators. Then we express the most general two-photon state generated by {\em Inside} creation operators, through base states generated by {\em Outside} creation operators. After renormalization of coefficients of inside two-photon state, we calculate the outside photon-number probability distribution in a general case. Finally we treat with some detail the single mode and symmetrical cavity case.Comment: 34 pages, 5 figures jpg, LaTe
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