14,452 research outputs found
Impurity and Trace Tritium Transport in Tokamak Edge Turbulence
The turbulent transport of impurity or minority species, as for example
Tritium, is investigated in drift-Alfv\'en edge turbulence. The full effects of
perpendicular and parallel convection are kept for the impurity species. The
impurity density develops a granular structure with steep gradients and locally
exceeds its initial values due to the compressibility of the flow. An
approximate decomposition of the impurity flux into a diffusive part and an
effective convective part (characterized by a pinch velocity) is performed and
a net inward pinch effect is recovered. The pinch velocity is explained in
terms of Turbulent Equipartition and is found to vary poloidally. The results
show that impurity transport modeling needs to be two-dimensional, considering
besides the radial direction also the strong poloidal variation in the
transport coefficients.Comment: 12 Pages, 5 Figure
Discovery of near-Earth asteroids by CCD scanning
The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented
Immunohistochemical localization of a macrophage-specific antigen in developing mouse retina:phagocytosis of dying neurons and differentiation of microglial cells to form a regular array in the plexiform layers
In the developing mouse retina degenerating neurons can be observed initially in the ganglion cell layer followed by a phase of cell death in the inner nuclear layer. Using an immunohistochemical method to localize the mouse macrophage specific antigen F4/80, we show that macrophages migrate from the vascular supply overlying the developing retina and phagocytose the degenerating neurons. The macrophages subsequently differentiate to become the microglia of the retina and form a regularly spaced distribution across the retina in the inner and outer plexiform layers. These experiments provide strong evidence for the mesodermal origin of central nervous system microglia.</p
Experimental test for extra dimensions in Kaluza-Klein gravity
5D Kaluza-Klein gravity has several nonasymptotically flat solutions which
generally, possessed both electric and magnetic charges. In this paper we
suggest that these solutions can act as quantum virtual handles (wormholes) in
spacetime foam models. By applying a sufficently large, external electric
and/or magnetic field it may be possible to ``inflate'' these solutions from a
quantum to a classical state. This effect would lead to a possible experimental
signal for higher dimensions in multidimensional gravity.Comment: 11 pages, 3 PS.figures, REVTEX, the quality of the figures are
improve
Nonperturbative renormalization in a scalar model within Light-Front Dynamics
Within the covariant formulation of Light-Front Dynamics, in a scalar model
with the interaction Hamiltonian , we calculate
nonperturbatively the renormalized state vector of a scalar "nucleon" in a
truncated Fock space containing the , and sectors. The
model gives a simple example of non-perturbative renormalization which is
carried out numerically. Though the mass renormalization diverges
logarithmically with the cutoff , the Fock components of the "physical"
nucleon are stable when .Comment: 22 pages, 5 figure
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