84,141 research outputs found
Gauge invariant investigation of the nature of Confinement
We observe a strong correlation between the decrease in the number of action
density peaks in SU(2) Yang-Mills configurations with cooling and that of the
string tension. The nature and distribution of these peaks is investigated. The
relationship with monopole currents after the abelian projection is also
considered.Comment: uuencoded and Z-compressed file of the Postcript version of our
contribution to LATTICE 95. 4 pages of text and 4 figure
Evolutionary constraints on the complexity of genetic regulatory networks allow predictions of the total number of genetic interactions
Genetic regulatory networks (GRNs) have been widely studied, yet there is a
lack of understanding with regards to the final size and properties of these
networks, mainly due to no network currently being complete. In this study, we
analyzed the distribution of GRN structural properties across a large set of
distinct prokaryotic organisms and found a set of constrained characteristics
such as network density and number of regulators. Our results allowed us to
estimate the number of interactions that complete networks would have, a
valuable insight that could aid in the daunting task of network curation,
prediction, and validation. Using state-of-the-art statistical approaches, we
also provided new evidence to settle a previously stated controversy that
raised the possibility of complete biological networks being random and
therefore attributing the observed scale-free properties to an artifact
emerging from the sampling process during network discovery. Furthermore, we
identified a set of properties that enabled us to assess the consistency of the
connectivity distribution for various GRNs against different alternative
statistical distributions. Our results favor the hypothesis that highly
connected nodes (hubs) are not a consequence of network incompleteness.
Finally, an interaction coverage computed for the GRNs as a proxy for
completeness revealed that high-throughput based reconstructions of GRNs could
yield biased networks with a low average clustering coefficient, showing that
classical targeted discovery of interactions is still needed.Comment: 28 pages, 5 figures, 12 pages supplementary informatio
Geometrical resonance in spatiotemporal systems
We generalize the concept of geometrical resonance to perturbed sine-Gordon,
Nonlinear Schrödinger and Complex Ginzburg-Landau equations. Using this
theory we can control different dynamical patterns. For instance, we can
stabilize breathers and oscillatory patterns of large amplitudes successfully
avoiding chaos. On the other hand, this method can be used to suppress
spatiotemporal chaos and turbulence in systems where these phenomena are
already present. This method can be generalized to even more general
spatiotemporal systems.Comment: 2 .epl files. Accepted for publication in Europhysics Letter
X-ray/gamma-ray flux correlations in the BL Lacs Mrk 421 and 501 using HAWC data
The HAWC gamma ray observatory is located at the Sierra Negra Volcano in
Puebla, Mexico, at an altitude of 4,100 meters. HAWC is a wide field of view
array of 300 water Cherenkov detectors that are continuously surveying ~ 2sr of
the sky, operating since March 2015. The large collected data sample allows
HAWC to perform an unbiased monitoring of the BL Lac Mrk 421. This is the
closest and brightest known extragalactic high-synchrotron-peaked BL Lac in the
gamma-ray/X- ray bands and is extensively monitored by the Large Area Telescope
(LAT) on-board the Fermi satellite, and the BAT and XRT instruments of the
Swift satellite. In this work, we use 25 months of HAWC data together with
Swift-XRT data to characterize potential correlations between both wavelengths.
This analysis shows that HAWC and Swift-XRT data are correlated even stronger
than expected for quasi-simultaneous observations.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017),
Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution
Self-dual vortex-like configurations in SU(2) Yang-Mills Theory
We show that there are solutions of the SU(2) Yang-Mills classical equations
of motion in R^4, which are self-dual and vortex-like(fluxons). The action
density is concentrated along a thick two-dimensional wall (the world sheet of
a straight infinite vortex line). The configurations are constructed from
self-dual R^2 x T^2 configurations.Comment: latex2e file. 10 pages 2 figure
Interplay of Coulomb and electron-phonon interactions in graphene
We consider mutual effect of the electron-phonon and strong Coulomb
interactions on each other by summing up leading logarithmic corrections via
the renormalization group approach. We find that the Coulomb interaction
enhances electron coupling to the intervalley A1 optical phonons, but not to
the intravalley E2 phonons
Lubrication of DLC Coatings with Two Tris(pentafluoroethyl)trifluorophosphate Anion-Based Ionic Liquids
The lubrication of a Cr-DLC coating with ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluoropho-sphate [(NEMM)MOE][FAP] and 1-butyl-1-methylpyrro-lidinium tris(pentafluoroethyl)trifluorophosphate [BMP] [FAP] ionic liquids (ILs) as 1 wt% additives to a polyalphaolefin (PAO 6) was studied. Zinc dialkyldithiophosphate (ZDDP) was also used as reference in order to evaluate the effectiveness of the ILs. Reciprocating ball-on-plate tribological tests at loads of 20 and 40 N were performed. The results showed that both ILs exhibited a friction reduction, especially at the lowest load tested. Antiwear properties were also improved; the PAO 6 + 1% [BMP][FAP] mixture was slightly better, close to the values for PAO 6 + 1% ZDDP. Scanning electron microscopy (SEM) images and X-ray photoelectron spectroscopy (XPS) analysis indicated that the additiveâsurface interaction was responsible for the tribological improvement
Cooper-pair propagation and superconducting correlations in graphene
We investigate the Cooper-pair propagation and the proximity effect in
graphene under conditions in which the distance L between superconducting
electrodes is much larger than the width W of the contacts. In the case of
undoped graphene, supercurrents may exist with a spatial decay proportional to
W^2/L^3. This changes upon doping into a 1/L^2 behavior, opening the
possibility to observe a supercurrent over length scales above 1 micron at
suitable doping levels. We also show that there is in general a crossover
temperature T ~ v_F/k_B L that marks the onset of the strong decay of the
supercurrent, and that corresponds to the scale below which the Cooper pairs
are not disrupted by thermal effects during their propagation.Comment: 5 pages, 2 figures; corrected discussio
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