7 research outputs found
Influence of uncorrelated overlayers on the magnetism in thin itinerant-electron films
The influence of uncorrelated (nonmagnetic) overlayers on the magnetic
properties of thin itinerant-electron films is investigated within the
single-band Hubbard model. The Coulomb correlation between the electrons in the
ferromagnetic layers is treated by using the spectral density approach (SDA).
It is found that the presence of nonmagnetic layers has a strong effect on the
magnetic properties of thin films. The Curie temperatures of very thin films
are modified by the uncorrelated overlayers. The quasiparticle density of
states is used to analyze the results. In addition, the coupling between the
ferromagnetic layers and the nonmagnetic layers is discussed in detail. The
coupling depends on the band occupation of the nonmagnetic layers, while it is
almost independent of the number of the nonmagnetic layers. The induced
polarization in the nonmagnetic layers shows a long-range decreasing
oscillatory behavior and it depends on the coupling between ferromagnetic and
nonmagnetic layers.Comment: 9 pages, RevTex, 6 figures, for related work see:
http://orion.physik.hu-berlin.d
Comparação entre os métodos de referência e a análise eletrônica na determinação da composição do leite bovino
Heartwater : past, present and future : proceedings of a workshop held at Berg en Dal, Kruger National Park, on 8-16 September 1986
The efficacy of subcutaneous, intramuscular and intraperitoneal inoculation of heartwater infective blood or nymph suspensions was tested in 5 experiments involving a total of 199 sheep. The success rate of subcutaneous injections varied greatly (0-100 %) in the different groups. However, it was found that certain additives to the inoculum, such as dimethyl sulphoxide or uninfective brain tissue, increased the efficacy of the subcutaneous route. Indications are that the site of inoculation and especially the dose volume are important factors in the success rate of such inoculations. Intramuscular injection with infective nymph suspensions containing bradikynin or hyaluronidase produced heartwater reactions in 11 out of 14 sheep. In 2 experiments, involving 25 cattle, it was found that, although very few animals showed definite reactions after the subcutaneous or intramuscular injection of nymph suspension and additives, the majority were afterwards immune to challenge. This phenomenon, which was also present in some sheep, needs further investigation.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
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