3,863 research outputs found

    Ill-posedness of degenerate dispersive equations

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    In this article we provide numerical and analytical evidence that some degenerate dispersive partial differential equations are ill-posed. Specifically we study the K(2,2) equation ut=(u2)xxx+(u2)xu_t = (u^2)_{xxx} + (u^2)_{x} and the "degenerate Airy" equation ut=2uuxxxu_t = 2 u u_{xxx}. For K(2,2) our results are computational in nature: we conduct a series of numerical simulations which demonstrate that data which is very small in H2H^2 can be of unit size at a fixed time which is independent of the data's size. For the degenerate Airy equation, our results are fully rigorous: we prove the existence of a compactly supported self-similar solution which, when combined with certain scaling invariances, implies ill-posedness (also in H2H^2)

    On Unitarity Based Relations Between Various Lepton Family Violating Processes

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    Simple "unitarity inspired" relations between two- and three-body lepton flavor violating decays are noted and discussed. In the absence of cancellations, the existing strong bounds on μ3e\mu \to 3e and μeγγ \mu\to e\gamma\gamma severly constrain two-body lepton flavor violating decays.Comment: 5 pages, 3 figure

    Pollen dimorphism and dioecy in Vitis aestivalis

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    Problems of low production and sterile pollen in varieties of Vitis vinifera may be tracable to their ancestral relations with dioecious wild grapes.Like V. riparia, the wild summer grape V. aestivalis has dimorphic male and female flowers; but unlike V. riparia it also has dimorphic pollen grains with the pollen from the female flower being significantly smaller.It seems fairly certain that V. aestivalis is truly dioecious

    Monte Carlo simulations of ordering in ferromagnetic-antiferromagnetic bilayers

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    Monte Carlo simulations have been used to study phase transitions on coupled anisotropic ferro/antiferromagnetic (FM/AFM) films of classical Heisenberg spins. We consider films of different thicknesses, with fully compensated exchange across the FM/AFM interface. We find indications of a phase transition on each film, occuring at different temperatures. It appears that both transition temperatures depend on the film thickness.Comment: Revtex, 4 pages, 4 figure

    Response of selected plant and insect species to simulated solid rocket exhaust mixtures and to exhaust components from solid rocket fuels

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    The effects of solid rocket fuel (SRF) exhaust on selected plant and and insect species in the Merritt Island, Florida area was investigated in order to determine if the exhaust clouds generated by shuttle launches would adversely affect the native, plants of the Merritt Island Wildlife Refuge, the citrus production, or the beekeeping industry of the island. Conditions were simulated in greenhouse exposure chambers and field chambers constructed to model the ideal continuous stirred tank reactor. A plant exposure system was developed for dispensing and monitoring the two major chemicals in SRF exhaust, HCl and Al203, and for dispensing and monitoring SRF exhaust (controlled fuel burns). Plants native to Merritt Island, Florida were grown and used as test species. Dose-response relationships were determined for short term exposure of selected plant species to HCl, Al203, and mixtures of the two to SRF exhaust
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