736 research outputs found

    Gravitational wave recoils in non-axisymmetric Robinson-Trautman spacetimes

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    We examine the gravitational wave recoil waves and the associated net kick velocities in non-axisymmetric Robinson-Trautman spacetimes. We use characteristic initial data for the dynamics corresponding to non-head-on collisions of black holes. We make a parameter study of the kick distributions, corresponding to an extended range of the incidence angle ρ0\rho_0 in the initial data. For the range of ρ0\rho_0 examined (3ρ01103^{\circ} \leq \rho_0 \leq 110^{\circ}) the kick distributions as a function of the symmetric mass parameter η\eta satisfy a law obtained from an empirical modification of the Fitchett law, with a parameter CC that accounts for the non-zero net gravitational momentum wave fluxes for the equal mass case. The law fits accurately the kick distributions for the range of ρ0\rho_0 examined, with a rms normalized error of the order of 5%5 \%. For the equal mass case the nonzero net gravitational wave momentum flux increases as ρ0\rho_0 increases, up to ρ055\rho_0 \simeq 55^{\circ} beyond which it decreases. The maximum net kick velocity is about 190km/s190 {\rm km/s} for for the boost parameter considered. For ρ050\rho_0 \geq 50^{\circ} the distribution is a monotonous function of η\eta. The angular patterns of the gravitational waves emitted are examined. Our analysis includes the two polarization modes present in wave zone curvature.Comment: 10 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1403.4581, arXiv:1202.1271, arXiv:1111.122

    Effectiveness and management of Conservation Units in the west and northwest regions of Paraná (Brazil)

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    The implementation of conservation units is an important strategy to conserve biodiversity, however, their consolidation as an effective mechanism for protecting natural resources faces several challenges. Therefore, the objective of this work was to evaluate the effectiveness and management of nine conservation units in the west and northwest regions of the state of Paraná, Brazil, by application of questionnaires, and interviews with managers in these areas. All evaluated conservation units had insufficient number of employees to meet their demand, and the management plan of 56% of the 89% units that had a management plan were outdated. According to the adopted criteria to evaluate the effectiveness of these conservation units, 67% of them presented satisfactory implementation effectiveness, and management conditions, because they have minimally fulfilled their objectives, despite the several economic, political and social barriers.The implementation of conservation units is an important strategy to conserve biodiversity, however, their consolidation as an effective mechanism for protecting natural resources faces several challenges. Therefore, the objective of this work was to evaluate the effectiveness and management of nine conservation units in the west and northwest regions of the state of Paraná, Brazil, by application of questionnaires, and interviews with managers in these areas. All evaluated conservation units had insufficient number of employees to meet their demand, and the management plan of 56% of the 89% units that had a management plan were outdated. According to the adopted criteria to evaluate the effectiveness of these conservation units, 67% of them presented satisfactory implementation effectiveness, and management conditions, because they have minimally fulfilled their objectives, despite the several economic, political and social barriers

    Homeopatia e fitoterapia: crenças e consumo dos estudantes da Escola Superior de Tecnologia da Saúde de Lisboa

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    Medicinas complementares e alternativas (MCA): cada vez mais utilizadas, em paralelo com a medicina convencional (MC) e 80% das pessoas no mundo já usaram alguma terapia das MCA. Insatisfação relativa à MC: preço elevado da assistência médica privada; alto custo dos medicamentos; precariedade da assistência prestada pelos serviços públicos. Crenças positivas sobre MCA: tão eficazes como a MC; se correctamente utilizadas, não ocasionam efeitos colaterais prejudiciais; mais compatíveis com valores pessoais e filosofias religiosas do que MC. Utilização das MCA: mais utilizadas (homeopatia e fitoterapia); tratamento e controlo de doenças crónicas. Objectivo do estudo: caracterizar as crenças sobre homeopatia e fitoterapia e os comportamentos de consumo dos estudantes da ESTeSL, enquanto consumidores e futuros profissionais de saúde
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