6,282 research outputs found
Zonal flow generation and its feedback on turbulence production in drift wave turbulence
Plasma turbulence described by the Hasegawa-Wakatani equations has been
simulated numerically for different models and values of the adiabaticity
parameter C. It is found that for low values of C turbulence remains isotropic,
zonal flows are not generated and there is no suppression of the meridional
drift waves and of the particle transport. For high values of C, turbulence
evolves toward highly anisotropic states with a dominant contribution of the
zonal sector to the kinetic energy. This anisotropic flow leads to a decrease
of a turbulence production in the meridional sector and limits the particle
transport across the mean isopycnal surfaces. This behavior allows to consider
the Hasegawa-Wakatani equations a minimal PDE model which contains the
drift-wave/zonal-flow feedback loop prototypical of the LH transition in plasma
devices.Comment: 14 pages, 7 figure
Ethnic Inequalities in Mortality in the Netherlands: and the role of socioeconomic status
Studies on the health of ethnic minority populations can provide clues about the aetiology
of diseases, can shed light on fundamental health inequalities that exist within one country
and may therefore be informative for people responsible for the provision and planning of
health care(1). For these reasons, a considerable number of studies on ethnic inequalities in
health have been performed during the last few decades(2-9).
Mortality figures are an interesting source of information on the health of ethnic
minorities because they are objective figures that can provide a broad image of the health
situation of group of interest. Surveys form an alternative source of information on the
health of ethnic minorities. These have, however, as a disadvantage that they are
susceptible to distortion due to cultural differences in reporting behaviour (10)
Large-scale bottleneck effect in two-dimensional turbulence
The bottleneck phenomenon in three-dimensional turbulence is generally
associated with the dissipation range of the energy spectrum. In the present
work, it is shown by using a two-point closure theory, that in two-dimensional
turbulence it is possible to observe a bottleneck at the large scales, due to
the effect of friction on the inverse energy cascade. This large-scale
bottleneck is directly related to the process of energy condensation, the
pile-up of energy at wavenumbers corresponding to the domain size. The link
between the use of friction and the creation of space-filling structures is
discussed and it is concluded that the careless use of hypofriction might
reduce the inertial range of the energy spectrum
U(1) Chern-Simons Theory and c=1 Conformal Blocks
The quantization of the U ( 1 ) Chern-Simons action in three dimensions is carried out in a coherent state representation. The wave functionals obtained are generating functionals for the current correlator blocks of two-dimensional c= 1 rational conformal field theories, explicitly realizing a connection found by Witten
Gender Expression and Mental Health in Black South African Men Who Have Sex with Men: Further Explorations of Unexpected Findings
Direct evidence for the magnetic ordering of Nd ions in NdFeAsO by high resolution inelastic neutron scattering
We investigated the low energy excitations in the parent compound NdFeAsO of
the Fe-pnictide superconductor in the eV range by a back scattering
neutron spectrometer. The energy scans on a powder NdFeAsO sample revealed
inelastic peaks at E = 1.600 eV at T = 0.055 K on both energy
gain and energy loss sides. The inelastic peaks move gradually towards lower
energy with increasing temperature and finally merge with the elastic peak at
about 6 K. We interpret the inelastic peaks to be due to the transition between
hyperfine-split nuclear level of the Nd and Nd isotopes with
spin . The hyperfine field is produced by the ordering of the
electronic magnetic moment of Nd at low temperature and thus the present
investigation gives direct evidence of the ordering of the Nd magnetic
sublattice of NdFeAsO at low temperature
Equivariant differential characters and symplectic reduction
We describe equivariant differential characters (classifying equivariant
circle bundles with connections), their prequantization, and reduction
Hydraulic Modeling of a Mixed Water Level Control Hydromechanical Gate
This article describes the hydraulic behavior of a mixed water level control hydromechanical gate present in several irrigation canals. The automatic gate is termed "mixed" because it can hold either the upstream water level or the downstream water level constant according to the flow conditions. Such a complex behavior is obtained through a series of side tanks linked by orifices and weirs. No energy supply is needed in this regulation process. The mixed flow gate is analyzed and a mathematical model for its function is proposed, assuming the system is at equilibrium. The goal of the modeling was to better understand the mixed gate function and to help adjust their characteristics in the field or in a design process. The proposed model is analyzed and evaluated using real data collected on a canal in the south of France. The results show the ability of the model to reproduce the function of this complex hydromechanical system. The mathematical model is also implemented in software dedicated to hydraulic modeling of irrigation canals, which can be used to design and evaluate management strategies
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