13,903 research outputs found

    Gravitational waves from pulsars with measured braking index

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    We study the putative emission of gravitational waves (GWs) in particular for pulsars with measured braking index. We show that the appropriate combination of both GW emission and magnetic dipole brakes can naturally explain the measured braking index, when the surface magnetic field and the angle between the magnetic dipole and rotation axes are time dependent. Then we discuss the detectability of these very pulsars by aLIGO and the Einstein Telescope. We call attention to the realistic possibility that aLIGO can detect the GWs generated by at least some of these pulsars, such as Vela, for example.Comment: 6 pages and 4 figure

    Pinning of spiral fluxons by giant screw dislocations in YBa_2Cu_3O_7 single crystals: Josephson analog of the fishtail effect

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    By using a highly sensitive homemade AC magnetic susceptibility technique, the magnetic flux penetration has been measured in YBa_2Cu_3O_7 single crystals with giant screw dislocations (having the structure of the Archimedean spirals) exhibiting a=3 spiral turnings, the pitch b=18.7 microns and the step height c=1.2nm (the last parameter is responsible for creation of extended weak-link structure around the giant defects). The magnetic field applied parallel to the surface enters winding around the weak-link regions of the screw in the form of the so-called spiral Josephson fluxons characterized by the temperature dependent pitch b_f(T). For a given temperature, a stabilization of the fluxon structure occurs when b_f(T) matches b (meaning an optimal pinning by the screw dislocations) and manifests itself as a pronounced low-field peak in the dependence of the susceptibility on magnetic field (applied normally to the surface) in the form resembling the high-field (Abrikosov) fishtail effect.Comment: see also http://www.jetpletters.ac.ru/ps/1886/article_28701.shtm

    Modelo de agricultura familiar para o entorno da Central Geradora Termelétrica Fortaleza (CGTF) em Caucaia, CE.

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    No presente artigo será apresentado uma proposta de modelo de agricultura familiar, com base na caracterização socioambiental da área e na percepção dos agricultores.bitstream/item/24612/1/circtec44-2010-modelo-agricultura-familiar-ceara.pd
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