937 research outputs found
From Regge Behavior to DGLAP Evolution
We study the interface between Regge behavior and DGLAP evolution in a
non-perturbative model for the nucleon structure function based on a multipole
pomeron exchange. This model provides the input for a subsequent DGLAP
evolution that we calculate numerically. The soft input and its evolution give
a good fit to the experimental data in the whole available range of x and Q^2.Comment: 7 pages, LaTeX, 4 figures. Text improved and reduced, figures
modified, references updated. To be published in Eur. Phys. J. C in the
present for
Turing Instability in a Boundary-fed System
The formation of localized structures in the chlorine dioxide-idodine-malonic
acid (CDIMA) reaction-diffusion system is investigated numerically using a
realistic model of this system. We analyze the one-dimensional patterns formed
along the gradients imposed by boundary feeds, and study their linear stability
to symmetry-breaking perturbations (Turing instability) in the plane transverse
to these gradients. We establish that an often-invoked simple local linear
analysis which neglects longitudinal diffusion is inappropriate for predicting
the linear stability of these patterns. Using a fully nonuniform analysis, we
investigate the structure of the patterns formed along the gradients and their
stability to transverse Turing pattern formation as a function of the values of
two control parameters: the malonic acid feed concentration and the size of the
reactor in the dimension along the gradients. The results from this
investigation are compared with existing experiments.Comment: 41 pages, 18 figures, to be published in Physical Review
A Population-Based Ultra-Widefield Digital Image Grading Study for Age-Related Macular Degeneration-Like Lesions at the Peripheral Retina.
Our understanding of the relevance of peripheral retinal abnormalities to disease in general and in age-related macular degeneration (AMD) in particular is limited by the lack of detailed peripheral imaging studies. The purpose of this study was to develop image grading protocols suited to ultra-widefield imaging (UWFI) in an aged population
Pressure-induced change of the pairing symmetry in superconducting CeCu2Si2
Low-temperature (T) heat-capacity measurements under hydrostatic pressure of
up to p=2.1 GPa have been performed on single-crystalline CeCu2Si2. A broad
superconducting (SC) region exists in the T-p phase diagram. In the
low-pressure region antiferromagnetic spin fluctuations and in the
high-pressure region valence fluctuations had previously been proposed to
mediate Cooper pairing. We could identify these two distinct SC regions. We
found different thermodynamic properties of the SC phase in both regions,
supporting the proposal that different mechanisms might be implied in the
formation of superconductivity.Comment: 4 pages, 5 figure
How fast do small x structure function rise ? A comparative analysis
We parametrize the small x, singlet component of the proton structure
function F_2 by powers and logarithms of 1/x for discrete values of Q^2 between
0.2 and 2000 GeV^2, and compare these parametrizations by applying the
criterion of minimal . The obtained values of the fitted parameters may
be used to study the evolution of F_2 in Q^2 and/or in discriminating between
dynamical models. A slowing-down in the increase of F_2 towards highest
available values of Q^2 is revealed. The effect is quantified in terms of the
derivative .Comment: 9 pages (LaTeX), including 4 figures (eps), condensed revised versio
Understanding European Integration with Bipartite Networks of Comparative Advantage
Core objectives of European common market integration are convergence and
economic growth, but these are hampered by redundancy, and value chain
asymmetries. The challenge is how to harmonize labor division to reach global
competitiveness, meanwhile bridging productivity differences across the EU. We
develop a bipartite network approach to trace pairwise co-specialization, by
applying the Revealed Comparative Advantage method, within and between EU15 and
Central and Eastern European (CEE). This approach assesses redundancies and
division of labor in the EU at the level of industries and countries. We find
significant co-specialization among CEE countries but a diverging
specialization between EU15 and CEE. Productivity increases in those CEE
industries that have co-specialized with other CEE countries after EU
accession, while co-specialization across CEE and EU15 countries is less
related to productivity growth. These results show that a division of sectoral
specialization can lead to productivity convergence between EU15 and CEE
countries.Comment: 17 pages, 4 figures, 6 table
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