88,377 research outputs found
Empirical analysis of the ship-transport network of China
Structural properties of the ship-transport network of China (STNC) are
studied in the light of recent investigations of complex networks. STNC is
composed of a set of routes and ports located along the sea or river. Network
properties including the degree distribution, degree correlations, clustering,
shortest path length, centrality and betweenness are studied in different
definition of network topology. It is found that geographical constraint plays
an important role in the network topology of STNC. We also study the traffic
flow of STNC based on the weighted network representation, and demonstrate the
weight distribution can be described by power law or exponential function
depending on the assumed definition of network topology. Other features related
to STNC are also investigated.Comment: 20 pages, 7 figures, 1 tabl
Leggett mode in a strong-coupling model of iron arsenide superconductors
Using a two-orbital model of the superconducting phase of the pnictides, we
compute the spectrum of the Leggett mode -- a collective excitation of the
phase of the superconducting gap known to exist in multi-gap superconductors --
for different possible symmetries of the superconducting order parameter.
Specifically, we identify the small regions of parameter space where the
Leggett mode lies below the two-particle continuum, and hence should be visible
as a sharp resonance peak. We discuss the possible utility of the Leggett mode
in distinguishing different momentum dependencies of the superconducting gap.
We argue that the observation of a sharp Leggett mode would be consistent with
the presence of strong electron-electron correlations in iron-based
superconductors. We also emphasize the importance of the orbital character of
the Leggett mode, which can result in an experimental observation of the mode
in channels other than
Electrical Characterization of PbZr0.4Ti0.6O3 Capacitors
We have conducted a careful study of current-voltage (I-V) characteristics in
fully integrated commercial PbZr0.4Ti0.6O3 thin film capacitors with Pt bottom
and Ir/IrO2 top electrodes. Highly reproducible steady state I-V were obtained
at various temperatures over two decades in voltage from current-time data and
analyzed in terms of several common transport models including space charge
limited conduction, Schottky thermionic emission under full and partial
depletion and Poole-Frenkel conduction, showing that the later is the most
plausible leakage mechanism in these high quality films. In addition,
ferroelectric hysteresis loops and capacitance-voltage data were obtained over
a large range of temperatures and discussed in terms of a modified
Landau-Ginzburg-Devonshire theory accounting for space charge effects.Comment: 17 pages, 7 figure
Lensing effect on the relative orientation between the Cosmic Microwave Background ellipticities and the distant galaxies
The low redshift structures of the Universe act as lenses in a similar way on
the Cosmic Microwave Background light and on the distant galaxies (say at
redshift about unity). As a consequence, the CMB temperature distortions are
expected to be statistically correlated with the galaxy shear, exhibiting a
non-uniform distribution of the relative angle between the CMB and the galactic
ellipticities. Investigating this effect we find that its amplitude is as high
as a 10% excess of alignement between CMB and the galactic ellipticities
relative to the uniform distribution. The relatively high signal-to-noise ratio
we found should makes possible a detection with the planned CMB data sets,
provided that a galaxy survey follow up can be done on a sufficiently large
area. It would provide a complementary bias-independent constraint on the
cosmological parameters.Comment: 7 pages, 3 figures; uses emulateapj.sty; submitted to Ap
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