34,842 research outputs found
Comparison of the AIMS65 Score with Other Risk Stratification Scores in Upper Variceal and Nonvariceal Gastrointestinal Bleeding.
info:eu-repo/semantics/publishedVersio
Stabilising entanglement by quantum jump-based feedback
We show that direct feedback based on quantum jump detection can be used to
generate entangled steady states. We present a strategy that is insensitive to
detection inefficiencies and robust against errors in the control Hamiltonian.
This feedback procedure is also shown to overcome spontaneous emission effects
by stabilising states with high degree of entanglement.Comment: 5 pages, 4 figure
Inverted critical adsorption of polyelectrolytes in confinement
What are the fundamental laws for the adsorption of charged polymers onto
oppositely charged surfaces, for convex, planar, and concave geometries? This
question is at the heart of surface coating applications, various complex
formation phenomena, as well as in the context of cellular and viral
biophysics. It has been a long-standing challenge in theoretical polymer
physics; for realistic systems the quantitative understanding is however often
achievable only by computer simulations. In this study, we present the findings
of such extensive Monte-Carlo in silico experiments for polymer-surface
adsorption in confined domains. We study the inverted critical adsorption of
finite-length polyelectrolytes in three fundamental geometries: planar slit,
cylindrical pore, and spherical cavity. The scaling relations extracted from
simulations for the critical surface charge density -defining the
adsorption-desorption transition-are in excellent agreement with our analytical
calculations based on the ground-state analysis of the Edwards equation. In
particular, we confirm the magnitude and scaling of for the concave
interfaces versus the Debye screening length and the extent of
confinement for these three interfaces for small values. For
large the critical adsorption condition approaches the planar limit.
The transition between the two regimes takes place when the radius of surface
curvature or half of the slit thickness is of the order of . We
also rationalize how gets modified for semi-flexible versus
flexible chains under external confinement. We examine the implications of the
chain length onto critical adsorption-the effect often hard to tackle
theoretically-putting an emphasis on polymers inside attractive spherical
cavities.Comment: 12 pages, 10 figures, RevTe
Critical adsorption of polyelectrolytes onto charged Janus nanospheres
Based on extensive Monte Carlo simulations and analytical considerations we
study the electrostatically driven adsorption of flexible polyelectrolyte
chains onto charged Janus nanospheres. These net-neutral colloids are composed
of two equally but oppositely charged hemispheres. The critical binding
conditions for polyelectrolyte chains are analysed as function of the radius of
the Janus particle and its surface charge density, as well as the salt
concentration in the ambient solution. Specifically for the adsorption of
finite-length polyelectrolyte chains onto Janus nanoparticles, we demonstrate
that the critical adsorption conditions drastically differ when the size of the
Janus particle or the screening length of the electrolyte are varied. We
compare the scaling laws obtained for the adsorption-desorption threshold to
the known results for uniformly charged spherical particles, observing
significant disparities. We also contrast the changes to the polyelectrolyte
chain conformations and the binding energy distributions close to the
adsorption-desorption transition for Janus nanoparticles to those for simple
spherical particles. Finally, we discuss experimentally relevant
physico-chemical systems for which our simulations results may become
important. In particular, we observe similar trends with polyelectrolyte
complexation with oppositely but heterogeneously charged proteins.Comment: 13 pages, 11 figures, RevTeX
Cosmic homogeneity: a spectroscopic and model-independent measurement
Cosmology relies on the Cosmological Principle, i.e., the hypothesis that the
Universe is homogeneous and isotropic on large scales. This implies in
particular that the counts of galaxies should approach a homogeneous scaling
with volume at sufficiently large scales. Testing homogeneity is crucial to
obtain a correct interpretation of the physical assumptions underlying the
current cosmic acceleration and structure formation of the Universe. In this
Letter, we use the Baryon Oscillation Spectroscopic Survey to make the first
spectroscopic and model-independent measurements of the angular homogeneity
scale . Applying four statistical estimators, we show that the
angular distribution of galaxies in the range 0.46 < z < 0.62 is consistent
with homogeneity at large scales, and that varies with
redshift, indicating a smoother Universe in the past. These results are in
agreement with the foundations of the standard cosmological paradigm.Comment: 5 pages, 2 figures, Version accepted by MNRA
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