1,978 research outputs found
The Quantum Stress-Tensor in Self-Similar Spherical Dust Collapse
We calculate the quantum stress tensor for a massless scalar field in the 2-d
self-similar spherical dust collapse model which admits a naked singularity. We
find that the outgoing radiation flux diverges on the Cauchy horizon. This may
have two consequences. The resultant back reaction may prevent the naked
singularity from forming, thus preserving cosmic censorship through quantum
effects. The divergent flux may lead to an observable signature differentiating
naked singularities from black holes in astrophysical observations.Comment: Latex File, 19 page
Penetrômetro Combinado com Sensor de Umidade por TDR para Estudo da Compactação dos Solos.
bitstream/CNPDIA/10486/1/CT41_2000.pd
Gamma-Ray Bursts and Quantum Cosmic Censorship
Gamma-ray bursts are believed to result from the coalescence of binary
neutron stars. However, the standard proposals for conversion of the
gravitational energy to thermal energy have difficulties. We show that if the
merger of the two neutron stars results in a naked singularity, instead of a
black hole, the ensuing quantum particle creation can provide the requisite
thermal energy in a straightforward way. The back-reaction of the created
particles can avoid the formation of the naked singularity predicted by the
classical theory. Hence cosmic censorship holds in the quantum theory, even if
it were to be violated in classical general relativity.Comment: Latex File, 6 pages. This essay received the third award from the
Gravity Research Foundation for the year 199
Uso de microeletrodos interligados de ouro revestidos com filmes poliméricos para a detecção de pesticidas em água por espectroscopia de impedância.
bitstream/CNPDIA-2009-09/11853/1/DOC25_2006.pd
Calibração e uso de uma sonda combinada tensiômetro/TDR.
A curva de retenção da água no solo é uma relação entre a umidade volumétrica e a tensão matricial do solo. Essa relação varia amplamente de solo para solo e tal variação depende fatores ligados aos valores de tensão superficial. Para baixos valores (0 a 1 bar) a dependência maior é em relação à capilaridade e à distribuição dos tamanhos de poros, portanto, fortemente da estrutura do solo.bitstream/CNPDIA/9714/1/CT39_2000.pd
Aplicação da Espectroscopia Fotoacústica nos estudos de solos intactos.
bitstream/CNPDIA-2009-09/12000/1/CT101_2008.pd
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