1,326 research outputs found
Plasma transition at the flanks of the Venus ionosheath: Evidence from the Venus Express data
Intermittent turbulence, noisy fluctuations and wavy structures in the Venusian magnetosheath and wake
Recent research has shown that distinct physical regions in the Venusian
induced magnetosphere are recognizable from the variations of strength of the
magnetic field and its wave/fluctuation activity. In this paper the statistical
properties of magnetic fluctuations are investigated in the Venusian
magnetosheath and wake regions. The main goal is to identify the characteristic
scaling features of fluctuations along Venus Express (VEX) trajectory and to
understand the specific circumstances of the occurrence of different types of
scalings. For the latter task we also use the results of measurements from the
previous missions to Venus. Our main result is that the changing character of
physical interactions between the solar wind and the planetary obstacle is
leading to different types of spectral scaling in the near-Venusian space.
Noisy fluctuations are observed in the magnetosheath, wavy structures near the
terminator and in the nightside near-planet wake. Multi-scale turbulence is
observed at the magnetosheath boundary layer and near the quasi-parallel bow
shock. Magnetosheath boundary layer turbulence is associated with an average
magnetic field which is nearly aligned with the Sun-Venus line. Noisy magnetic
fluctuations are well described with the Gaussian statistics. Both
magnetosheath boundary layer and near shock turbulence statistics exhibit
non-Gaussian features and intermittency over small spatio-temporal scales. The
occurrence of turbulence near magnetosheath boundaries can be responsible for
the local heating of plasma observed by previous missions
Diabetes insípida central e hipotiroidismo secundario debidos a un macroadenoma hipofisario en un perro
Se expone el caso de una perra que presentaba inicialmente midriasis unilateral como único signo clínico. A los 12 meses apareció también midriasis en el otro ojo junto con poliuria, polidipsia, letargia y alopecia bilateral troncal. Tras distintas pruebas se diagnosticó diabetes insípida central e hipotiroidismo secundario, presuntamente debidos a un tumor hipofisario posteriormente confirmado mediante necropsia.
Normalization factors for magnetic relaxation of small particle systems in non-zero magnetic field
We critically discuss relaxation experiments in magnetic systems that can be
characterized in terms of an energy barrier distribution, showing that proper
normalization of the relaxation data is needed whenever curves corresponding to
different temperatures are to be compared. We show how these normalization
factors can be obtained from experimental data by using the
scaling method without making any assumptions about the nature of the energy
barrier distribution. The validity of the procedure is tested using a
ferrofluid of Fe_3O_4 particles.Comment: 5 pages, 6 eps figures added in April 22, to be published in Phys.
Rev. B 55 (1 April 1997
Millikelvin magnetic relaxation measurements of alpha-Fe2O3 antiferromagnetic particles
In this paper we report magnetic relaxation data for antiferromagnetic
alpha-Fe2O3 particles of 5 nm mean diameter in the temperature range 0.1 K to
25 K. The average spin value of these particles S=124 and the uniaxial
anisotropy constant D=1.6x10^-2 K have been estimated from the experimental
values of the blocking temperature and anisotropy field. The observed plateau
in the magnetic viscosity from 3 K down to 100 mK agrees with the occurrence of
spin tunneling from the ground state Sz = S. However, the scaling M vs Tln(nu
t) is broken below 5 K, suggesting the occurrence of tunneling from excited
states below this temperature.Comment: 4 pages (two columns), 4 figure
Exponential Decay of Correlations in a Model for Strongly Disordered 2D Nematic Elastomers
Lattice Monte-Carlo simulations were performed to study the equilibrium
ordering in a two-dimensional nematic system with quenched random disorder.
When the disordering field, which competes against the aligning effect of the
Frank elasticity, is sufficiently strong, the long-range correlation of the
director orientation is found to decay as a simple exponential, Exp[-r/x]. The
correlation length {x} itself also decays exponentially with increasing
strength of the disordering field. This result represents a new type of
behavior, distinct from the Gaussian and power-law decays predicted by some
theories.Comment: Latex file (4 pages) + 2 EPS figure
Digital filter implementation over FPGA platform with LINUX OS
AbstractThe embedded processors on FPGA's are a good tool to specific propose works. In this work we present how the FPGA is used to apply a Sobel filter to a set of images, also the step needed to set-up the entire system is described. An embedded processor, with a Linux distribution implemented is used to run a special compilation of C filter program, the filter is compared with the results obtained with a PC running the same filter, in the embedded system all the process runs in the FPGA and the exit file can be accessed by ftp or http server embedded into the Linux system
Generation and matching of ontology data for the semantic web in a peer-to-peer framework
The abundance of ontology data is very crucial to the emerging semantic web. This paper proposes a framework that supports the generation of ontology data in a peer-to-peer environment. It not only enables users to convert existing structured data to ontology data aligned with given ontology schemas, but also allows them to publish new ontology data with ease. Besides ontology data generation, the common issue of data overlapping over the peers is addressed by the process of ontology data matching in the framework. This process helps turn the implicitly related data among the peers caused by overlapping into explicitly interlinked ontology data, which increases the overall quality of the ontology data. To improve matching accuracy, we explore ontology related features in the matching process. Experiments show that adding these features achieves better overall performance than using traditional features only. © Springer-Verlag Berlin Heidelberg 2007
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