1,721,098 research outputs found
On large deviations for small noise Itô processes
No full textThe large deviation principle in the small noise limit is derived for solutions of possibly degenerate Itô stochastic differential equations with predictable coefficients, which may depend also on the large deviation parameter. The result is established under mild assumptions using the Dupuis-Ellis weak convergence approach. Applications to certain systems with memory and to positive diffusions with square-root-like dispersion coefficient are included
Phase transition for level-set percolation of the membrane model in dimensions
Full text linkWe consider level-set percolation for the Gaussian membrane model on
, with , and establish that as
varies, a non-trivial percolation phase transition for the level-set above
level occurs at some finite critical level , which we show to be
positive in high dimensions. Along , two further natural critical
levels and are introduced, and we establish that
, in all
dimensions. For , we find that the connectivity function of
the level-set above admits stretched exponential decay, whereas for , chemical distances in the (unique) infinite cluster of the
level-set are shown to be comparable to the Euclidean distance, by verifying
conditions identified by Drewitz, R\'ath and Sapozhnikov, see arXiv:1212.2885,
for general correlated percolation models. As a pivotal tool to study its
level-set, we prove novel decoupling inequalities for the membrane model.Comment: 29 pages, 1 figure, to appear in Journal of Statistical Physic
Neutral/negative α 1 -AR antagonists and calcium channel blockers at comparison in functional tests on guinea-pig smooth muscle and myocardium
No full textBackground: Constitutive (agonist-independent) activity is a prerogative of many G protein-coupled receptors (GPCRs) including α 1 -adrenoceptors (α 1 -ARs). Inhibition of such an activity at α 1 -AR subtypes by antagonists with negative efficacy is difficult to be adequately tested. Methods: In the present experimental approach, we compared the activity of three calcium channel blockers (nifedipine, diltiazem and verapamil) and of three potent benzodioxane-based α 1 -AR antagonists, differing for subtype selectivity and inverse agonist properties, in producing smooth muscle relaxation and negative inotropy under the same test conditions. We selected, as benzodioxane derivatives, (S)-WB4101, inverse agonist with slight α 1A /α 1B -α 1D AR selectivity, and two previously developed analogues. Both of these are potent antagonists at α 1D -AR, that is the α 1 - AR subtype suspected of the highest susceptibility to inverse agonists for its high degree of basal activity, but only one is inverse agonist. Results: We found that all the three benzodioxane-related α 1 -AR antagonists have significant intrinsic relaxant activity on non-vascular smooth muscle and moderate negative inotropic effect, while they do not relax aorta. Their potency is always lower than that of three calcium channel blockers. Conclusions: Intrinsic myorelaxant and negative inotropic activity of the three benzodioxane-based α 1 -AR antagonist is related neither to a particular profile of α 1 -AR subtype selectivity nor to whether or not being an inverse agonist, but it parallels the calcium antagonists effects indicating a direct interaction of the three α 1 -AR antagonists with L-type Ca 2+ channels
From quenched invariance principle to semigroup convergence with applications to exclusion processes
Full text linkConsider a random walk on Z(d) in a translation-invariant and ergodic random environment and starting from the origin. In this short note, assuming that a quenched invariance principle for the opportunely-rescaled walks holds, we show how to derive an L-1-convergence of the corresponding semigroups. We then apply this result to obtain a quenched pathwise hydrodynamic limit for the simple symmetric exclusion process on Z(d), d >= 2, with i.i.d. symmetric nearest-neighbors conductances omega(xy )is an element of [0,infinity) only satisfying Q(omega(xy)>0) > p(c), where p(c) is the critical value for bond percolation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
