7,693 research outputs found
Predicting the critical density of topological defects in O(N) scalar field theories
O(N) symmetric field theories describe many critical
phenomena in the laboratory and in the early Universe. Given N and ,
the dimension of space, these models exhibit topological defect classical
solutions that in some cases fully determine their critical behavior. For N=2,
D=3 it has been observed that the defect density is seemingly a universal
quantity at T_c. We prove this conjecture and show how to predict its value
based on the universal critical exponents of the field theory. Analogously, for
general N and D we predict the universal critical densities of domain walls and
monopoles, for which no detailed thermodynamic study exists. This procedure can
also be inverted, producing an algorithm for generating typical defect networks
at criticality, in contrast to the canonical procedure, which applies only in
the unphysical limit of infinite temperature.Comment: 4 pages, 3 figures, uses RevTex, typos in Eq.(11) and (14) correcte
Aspectos técnicos da cultura da framboeseira.
bitstream/CPACT/9252/1/documento_120.pdf; bitstream/item/32425/1/documento-120.pd
Multi-band Superconductivity in the Chevrel Phases SnMo6S8 and PbMo6S8
Sub-Kelvin scanning tunnelling spectroscopy in the Chevrel Phases SnMo6S8 and
PbMo6S8 reveals two distinct superconducting gaps with Delta_1 = 3 meV, Delta_2
~ 1.0 meV and Delta_1 = 3.1 meV, Delta_2 ~ 1.4 meV respectively. The gap
distribution is strongly anisotropic, with Delta_2 predominantly seen when
scanning across unit-cell steps on the (001) sample surface. The spectra are
well-fitted by an anisotropic two-band BCS s-wave gap function. Our
spectroscopic data are confirmed by electronic heat capacity measurements which
also provide evidence for a twin-gap scenario.Comment: 5 pages, 4 figure
Economia da produção de morango: estudo de caso de transição para produção integrada.
bitstream/item/30384/1/boletim-53.pd
AnĂĄlise da interferĂȘncias no NDVI do AVHRR e conjunto de dados alternativo.
Dados do A VHRR tĂȘm sido muito usados para o acompanhamento das variaçÔes sazonais e interanuais da cobertura vegetal brasileira. Estes dados apresentam ruĂdos resultantes de interferĂȘncias do sensor e de condiçÔes atmosfĂ©ricas. O presente estudo relata estas interferĂȘncias, apresenta e avalia um novo conjunto de NOVI derivado daquele disponibilizado pela NASA/NOAA, o EFAI-NDVI ("European Fourier-Adjusted and Interpolated NDVY'), gerado por meio da anĂĄlise do comportamento da sĂ©rie temporal dos dados brutos. Os resultados mostram padrĂ”es de variaçÔes e comportamentos sazonais e interanuais da vegetação para vĂĄrias regiĂ”es do paĂs. As resoluçÔes temporal e espacial das imagens permitem mapear e acompanhar estas variaçÔes em pequena escala, indicando que os dados de refectĂąncia derivados dos satĂ©lites de Ăłrbita polar podem ser utilizados no monitoramento e gestĂŁo ambiental, mas devendo ser cuidadosamente prĂ©-processados para reduzir interferĂȘncias do sensor e da atmosfera
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