1,631 research outputs found
Orbital frustration at the origin of the magnetic behavior in LiNiO2
We report on the ESR, magnetization and magnetic susceptibility measurements
performed over a large temperature range, from 1.5 to 750 K, on high-quality
stoichiometric LiNiO2. We find that this compound displays two distinct
temperature regions where its magnetic behavior is anomalous. With the help of
a statistical model based on the Kugel'-Khomskii Hamiltonian, we show that
below T_of ~ 400 K, an orbitally-frustrated state characteristic of the
triangular lattice is established. This then gives a solution to the
long-standing controversial problem of the magnetic behavior in LiNiO2.Comment: 5 pages, 5 figures, RevTex, accepted in PR
Mathematical formulation of a dynamical system with dry friction subjected to external forces
We consider the response of a one-dimensional system with friction. S.W. Shaw
(Journal of Sound and Vibration, 1986) introduced the set up of different
coefficients for the static and dynamic phases (also called stick and slip
phases). He constructs a step by step solution, corresponding to an harmonic
forcing. In this paper, we show that the theory of variational inequalities
provides an elegant and synthetic approach to obtain the existence and
uniqueness of the solution, avoiding the step by step construction. We then
apply the theory to a real structure with real data and show that the model is
quite accurate. In our case, the forcing motion comes from dilatation, due to
temperature
Twin polaritons in semiconductor microcavities
The quantum correlations between the beams generated by polariton pair
scattering in a semiconductor microcavity above the parametric oscillation
threshold are computed analytically. The influence of various parameters like
the cavity-exciton detuning, the intensity mismatch between the signal and
idler beams and the amount of spurious noise is analyzed. We show that very
strong quantum correlations between the signal and idler polaritons can be
achieved. The quantum effects on the outgoing light fields are strongly reduced
due to the large mismatch in the coupling of the signal and idler polaritons to
the external photons
Thematic Mapper image quality: Preliminary results
Based on images analyzed so far, the band to band registration accuracy of the thematic mapper is very good. For bands within the same focal plane, the mean misregistrations are well within the specification, 0.2 pixels. For bands between the cooled and uncooled focal planes, there is a consistent mean misregistration of 0.5 pixels along-scan and 0.2-0.3 pixels across-scan. It exceeds the permitted 0.3 pixels for registration of bands between focal planes. If the mean misregistrations were removed by the data processing software, an analysis of the standard deviation of the misregistration indicates all band combinations would meet the registration specifications except for those including the thermal band. Analysis of the periodic noise in one image indicates a noise component in band 1 with a spatial frequency equivalent to 3.2 pixels in the along-scan direction
The effects of exposure to a rotating environment /10 rpm/ on four aviators for a period of twelve days
Motion sickness studies of aviators exposed to rotating environment - Aerospace medicin
Susceptibility to weathering damage and oxidative stress on soybean seeds with different lignin contents in the seed coat.
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Respostas de enzimas antioxidantes a bioativador em plântulas de milho sob estresse hÃdrico.
Edição Especial contendo os Anais do XVIII Congresso Brasileiro de Sementes, Florianópolis, set. 2013
Cooling of a mirror by radiation pressure
We describe an experiment in which a mirror is cooled by the radiation
pressure of light. A high-finesse optical cavity with a mirror coated on a
mechanical resonator is used as an optomechanical sensor of the Brownian motion
of the mirror. A feedback mechanism controls this motion via the radiation
pressure of a laser beam reflected on the mirror. We have observed either a
cooling or a heating of the mirror, depending on the gain of the feedback loop.Comment: 4 pages, 6 figures, RevTe
Qualidade fisiológica de sementes de soja tratadas durante o armazenamento.
Edição Especial contendo os Anais do XVIII Congresso Brasileiro de Sementes, Florianópolis, set. 2013
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