2,227 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

    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

    Black string bounce to traversable wormhole

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    In this work, a regular black string solution will be presented from the method used by Simpson-Visser to regularize the Schwarzschild solution. As in the Simpson-Visser work, in this new black string solution, it is possible to represent both a regular black hole and a wormhole just by changing the value of a parameter "aa" used in its metric. Tensors and curvature invariants were analyzed to verify the regularity of the solution, as well as the energy conditions of the system. It was found that the null energy condition will always be violated for the entire space. The analysis of the thermodynamic properties of the regular black string was also carried out, in which the modifications generated about the original solution of the black string, were evaluated, specifically, the Hawking temperature, entropy, its thermal capacity, and the Helmholtz free energy. Finally, we investigate the possible stable or unstable circular orbits for photons and massive particles. The results were compared with those of the non-regular black string, seeking to make a parallel with the Simpson-Visser work.Comment: 8 pages, 6 figure

    On the Selection of Photometric Planetary Transits

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    We present a new method for differentiating between planetary transits and eclipsing binaries based on the presence of the ellipsoidal light variations. These variations can be used to detect stellar secondaries with masses ~0.2 M_sun orbiting sun-like stars at a photometric accuracy level which has already been achieved in transit surveys. By removing candidates exhibiting this effect it is possible to greatly reduce the number of objects requiring spectroscopic follow up with large telescopes. Unlike the usual candidate selection method, which are primarily based on the estimated radius of the orbiting object, this technique is not biased against bona-fide planets and brown dwarfs with large radii, because the amplitude of the effect depends on the transiting object's mass and orbital distance. In many binary systems, where a candidate planetary transit is actually due to the partial eclipse of two normal stars, the presence of flux variations due to the gravity darkening effect will show the true nature of these systems. We show that many of the recent OGLE-III photometric transit candidates exhibit the presence of significant variations in their light curves and are likely to be due to stellar secondaries. We find that the light curves of white dwarf transits will generally not mimic those of small planets because of significant gravitationally induced flux variations. We discuss the relative merits of methods used to detect transit candidates which are due to stellar blends rather than planets. We outline how photometric observations taken in two bands can be used to detect the presence of stellar blends.Comment: ApJ, 11 pages, 2 figures, 1 table, replaced with accepted versio
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