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Full-Text Articles in Physics

Fractal Dimensions In Perceptual Color Space: A Comparison Study Using Jackson Pollock’S Art, Jonas R. Mureika Sep 2017

Fractal Dimensions In Perceptual Color Space: A Comparison Study Using Jackson Pollock’S Art, Jonas R. Mureika

Jonas Mureika

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process that models perceptual response to color differences (L*a*b* color space). The advantage of the L*a*b* space filtering method over traditional red-green-blue (RGB) spaces is that the former is a perceptually uniform (metric) space, leading to a more consistent definition of “perceptually different” colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter-colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to ...


Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich Aug 2016

Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich

Michael Schulz

We have performed experimental and theoretical studies of double ionization of helium by 6 MeV proton impact using a recently developed tool, four-particle Dalitz plots [Schulz et al., J. Phys. B 22, 3091 (2007)] which enable the representation of multiple differential cross sections as a function of all four fragments in a single spectrum without loss of any part of the total cross section. As a result, the relative importance of the various interactions between the fragments can be studied in great detail. Comparisons of experimental data with theoretical first-order calculations and simulations for the higher-order (TS-2) process show that ...


Triple Gamma Directional Correlations In The Decay Of Europium-154, Gary Lewis Dec 1980

Triple Gamma Directional Correlations In The Decay Of Europium-154, Gary Lewis

Gary C. Lewis

The ('154)Eu nucleus decays by beta emission to an excited state of the ('154)Gd nucleus. The resulting ('154)Gd nucleus decays to its ground state by emission of gamma rays. One series of gamma rays emitted in this process is a cascade of energies 723 keV, 873 keV, and 123 keV. The 873 keV gamma ray is a mixture of E2 and M1 radiation. The mixing ratio of this transition has been measured using the triple gamma directional correlation technique. The experiments used a planar geometry with one angle fixed at 90 degrees. Two Ge(Li) detectors and ...