3,890 research outputs found

    Pragas do melao e alternativas de controle.

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    Mosca branca; Brocas das cucurbitaceas; Pulgão; Moscas das frutas; Mosca minadora; Lagarta rosada; Vaquinha.bitstream/item/136248/1/ID-8813.pdfApostila do I Curso sobre o Cultivo do Melao, 2000, Petrolina

    A method to simulate inhomogeneously irradiated objects with a superposition of 1D models

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    In close binary systems the atmosphere of one or both components can be significantly influenced by irradiation from the companion. Often the irradiated atmosphere is simulated with a single-temperature approximation for the entire half-sphere. We present a scheme to take the varying irradiation angle into account by combining several separate 1D models. This is independent of the actual code which provides the separate stellar spectra. We calculate the projected area of zones with given irradiation angle and use this geometrical factor to scale separate 1D models. As an example we calculate two different irradiation scenarios with the PHOENIX code. The scheme to calculate the projected area is applicable independent of the physical mechanism that forms these zones. In the case of irradiation by a primary with T=125000 K, the secondary forms ions at different ionisation states for different irradiation angles. No single irradiation angle exists which provides an accurate description of the spectrum. We show a similar simulation for weaker irradiation, where the profile of the Hα\alpha line depends on the irradiation angle.Comment: published in A&

    Semiclassical asymptotic behavior of orthogonal polynomials

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    Our goal is to find asymptotic formulas for orthonormal polynomials Pn(z)P_{n}(z) with the recurrence coefficients slowly stabilizing as nn\to\infty. To that end, we develop spectral theory of Jacobi operators with long-range coefficients and study the corresponding second order difference equation. We suggest an Ansatz for its solutions playing the role of the semiclassical Green-Liouville Ansatz for solutions of the Schr\"odinger equation. The formulas obtained for Pn(z)P_{n}(z) as nn\to\infty generalize the classical Bernstein-Szeg\"o asymptotic formulas

    Object orientation without extending Z

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    The good news of this paper is that without extending Z, we can elegantly specify object-oriented systems, including encapsulation, inheritance and subtype polymorphism (dynamic dispatch). The bad news is that this specification style is rather different to normal Z specifications, more abstract and axiomatic, which means that it is not so well supported by current Z tools such as animators. It also enforces behavioural subtyping, unlike most object-oriented programming languages. This paper explains the proposed style, with examples, and discusses its advantages and disadvantages
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