29,659 research outputs found
Luminosity segregation versus fractal scaling in the galaxy distribution
In this letter I present results from a correlation analysis of three galaxy
redshift catalogs: the SSRS2, the CfA2 and the PSCz. I will focus on the
observation that the amplitude of the two--point correlation function rises if
the depth of the sample is increased. There are two competing explanations for
this observation, one in terms of a fractal scaling, the other based on
luminosity segregation. I will show that there is strong evidence that the
observed growth is due to a luminosity dependent clustering of the galaxies.Comment: 7 pages, EPL in pres
Revolving rivers in sandpiles: from continuous to intermittent flows
In a previous paper [Phys. Rev. Lett. 91, 014501 (2003)], the mechanism of
"revolving rivers" for sandpile formation is reported: as a steady stream of
dry sand is poured onto a horizontal surface, a pile forms which has a river of
sand on one side owing from the apex of the pile to the edge of the base. For
small piles the river is steady, or continuous. For larger piles, it becomes
intermittent. In this paper we establish experimentally the "dynamical phase
diagram" of the continuous and intermittent regimes, and give further details
of the piles topography, improving the previous kinematic model to describe it
and shedding further light on the mechanisms of river formation. Based on
experiments in Hele-Shaw cells, we also propose that a simple dimensionality
reduction argument can explain the transition between the continuous and
intermittent dynamics.Comment: 8 pages, 11 figures, submitted to Phys Rev
The Berwald-type linearisation of generalised connections
We study the existence of a natural `linearisation' process for generalised
connections on an affine bundle. It is shown that this leads to an affine
generalised connection over a prolonged bundle, which is the analogue of what
is called a connection of Berwald type in the standard theory of connections.
Various new insights are being obtained in the fine structure of affine bundles
over an anchored vector bundle and affineness of generalised connections on
such bundles.Comment: 25 page
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