1,070 research outputs found
Anpassung von Gebäuden
Dies ist ein Faktenblatt aus dem REGKLAM-Vorhaben zum Thema "Anpassung von Gebäuden"
Self-stabilizing processes: uniqueness problem for stationary measures and convergence rate in the small noise limit
In the context of self-stabilizing processes, that is processes attracted by their own law, leaving in some potential landscape, we investigate different properties of the invariant measures. The interaction between the process and its law leads to nonlinear stochastic differential equations. In some previous work, the authors proved that, for linear interaction and under suitable conditions, there exist some unique symmetric limit measure associated to the set of invariant measures in the small noise limit. The aim of this study is essentially to point out that this statement leads to the existence, as the noise intensity is small, of one unique symmetric invariant measure for the self-stabilizing process. Informations about the asymmetric measures shall be presented too. The main key consists in estimating the convergence rate for sequences of stationary measures using generalized Laplace's method approximations
Non uniqueness of stationary measures for self-stabilizing diffusions
International audienceWe investigate the existence of invariant measures for self-stabilizing diffusions. These stochastic processes represent roughly the behavior of some Brownian particle moving in a double-well landscape and attracted by its own law. This specific self-interaction leads to nonlinear stochastic differential equations and permits to point out singular phenomenons like non uniqueness of associated stationary measures. The existence of several invariant measures is essentially based on the non convex environment and requires generalized Laplace's method approximations
Stationary measures for self-stabilizing processes: asymptotic analysis in the small noise limit
International audienceSelf-stabilizing diffusions are stochastic processes, solutions of nonlinear stochastic differential equation, which are attracted by their own law. This specific self-interaction leads to singular phenomenons like non uniqueness of associated stationary measures when the diffusion leaves in some non convex environment. The aim of this paper is to describe these invariant measures and especially their asymptotic behavior as the noise intensity in the nonlinear SDE becomes small. We prove in particular that the limit measures are discrete measures and point out some properties of their support which permit in several situations to describe explicitly the whole set of limit measures. This study requires essentially generalized Laplace's method approximations
Self-stabilizing processes: uniqueness problem for stationary measures and convergence rate in the small-noise limit
Second versionIn the context of self-stabilizing processes, that is processes attracted by their own law, living in a potential landscape, we investigate different properties of the invariant measures. The interaction between the process and its law leads to nonlinear stochastic differential equations. In some previous work, the authors proved that, for linear interaction and under suitable conditions, there exists a unique symmetric limit measure associated to the set of invariant measures in the small-noise limit. The aim of this study is essentially to point out that this statement leads to the existence, as the noise intensity is small, of one unique symmetric invariant measure for the self-stabilizing process. Informations about the asymmetric measures shall be presented too. The main key consists in estimating the convergence rate for sequences of stationary measures using generalized Laplace's method approximations
Watersheds in disordered media
This is the final published version. It first appeared at http://journal.frontiersin.org/article/10.3389/fphy.2015.00005/full#h11.What is the best way to divide a rugged landscape? Since ancient times, watersheds
separating adjacent water systems that flow, for example, toward different seas, have
been used to delimit boundaries. Interestingly, serious and even tense border disputes
between countries have relied on the subtle geometrical properties of these tortuous
lines. For instance, slight and even anthropogenic modifications of landscapes can produce
large changes in a watershed, and the effects can be highly nonlocal. Although the
watershed concept arises naturally in geomorphology, where it plays a fundamental role
in water management, landslide, and flood prevention, it also has important applications
in seemingly unrelated fields such as image processing and medicine. Despite the
far-reaching consequences of the scaling properties on watershed-related hydrological and
political issues, it was only recently that a more profound and revealing connection has
been disclosed between the concept of watershed and statistical physics of disordered
systems. This review initially surveys the origin and definition of a watershed line in a
geomorphological framework to subsequently introduce its basic geometrical and physical
properties. Results on statistical properties of watersheds obtained from artificial model
landscapes generated with long-range correlations are presented and shown to be in good
qualitative and quantitative agreement with real landscapes.We acknowledge financial support from the European Research Council (ERC) Advanced Grant 319968-FlowCCS, the Brazilian Agencies CNPq, CAPES, FUNCAP and FINEP, the FUNCAP/CNPq Pronex grant, the National Institute of Science and Technology for Complex Systems in Brazil, the Portuguese Foundation for Science and Technology (FCT) under contracts no. IF/00255/2013, PEst-OE/FIS/UI0618/2014, and EXCL/FIS-NAN/0083/2012, and the Swiss National Science Foundation under Grant No. P2EZP2-152188
SUPPORTING SYSTEMS ENGINEERING ACTIVITIES BY ARTIFACT-ORIENTED DESCRIPTION AND SELECTION OF METHODS
Systems Engineering (SE) is becoming increasingly relevant in industrial application since more stakeholders are involved in engineering activities. To implement SE, companies have to adapt existing engineering processes and methods. This adaption requires knowledge about new methods as well as their integration into the engineering activities. In order to ensure goal-oriented identification of methods for different SE activities in this contribution an action field profile and the Systems Engineering Method Matrix are proposed. The development of both tools is driven by the assumption that most SE activities and methods can be described based on the artefacts the deliver. In order to get feedback about the proposed tools, semi-structured interviews with two industry partners were conducted, focussing on the tool\u27s usability. These interviews underline the basic usability of the tools and their support to identify SE activities to be supported by (new) methods. Moreover, requirements for further development and adaption are derived from the interviews
Circumbinary MHD Accretion into Inspiraling Binary Black Holes
As 2 black holes bound to each other in a close binary approach merger their
inspiral time becomes shorter than the characteristic inflow time of
surrounding orbiting matter. Using an innovative technique in which we
represent the changing spacetime in the region occupied by the orbiting matter
with a 2.5PN approximation and the binary orbital evolution with 3.5PN, we have
simulated the MHD evolution of a circumbinary disk surrounding an equal-mass
non-spinning binary. Prior to the beginning of the inspiral, the structure of
the circumbinary disk is predicted well by extrapolation from Newtonian
results. The binary opens a low-density gap whose radius is roughly two binary
separations, and matter piles up at the outer edge of this gap as inflow is
retarded by torques exerted by the binary; nonetheless, the accretion rate is
diminished relative to its value at larger radius by only about a factor of 2.
During inspiral, the inner edge of the disk at first moves inward in
coordination with the shrinking binary, but as the orbital evolution
accelerates, the rate at which the inner edge moves toward smaller radii falls
behind the rate of binary compression. In this stage, the rate of angular
momentum transfer from the binary to the disk slows substantially, but the net
accretion rate decreases by only 10-20%. When the binary separation is tens of
gravitational radii, the rest-mass efficiency of disk radiation is a few
percent, suggesting that supermassive binary black holes in galactic nuclei
could be very luminous at this stage of their evolution. If the luminosity were
optically thin, it would be modulated at a frequency that is a beat between the
orbital frequency of the disk's surface density maximum and the binary orbital
frequency. However, a disk with sufficient surface density to be luminous
should also be optically thick; as a result, the periodic modulation may be
suppressed.Comment: 54 pages, color figures, submitted to the Astrophysical Journal, a
high resolution version and movies can be found at
http://ccrg.rit.edu/~scn/cmhdaiibh
Mitochondria Permeability Transition versus Necroptosis in Oxalate-Induced AKI
Serum oxalate levels suddenly increase with certain dietary exposures or ethylene glycol poisoning and are a well known cause of AKI. Established contributors to oxalate crystal-induced renal necroinflammation include the NACHT, LRR and PYD domains-containing protein-3 (NLRP3) inflammasome and mixed lineage kinase domain-like (MLKL) protein-dependent tubule necroptosis. These studies examined the role of a novel form of necrosis triggered by altered mitochondrial function. METHODS: To better understand the molecular pathophysiology of oxalate-induced AIK, we conducted in vitro studies in mouse and human kidney cells and in vivo studies in mice, including wild-type mice and knockout mice deficient in peptidylprolyl isomerase F (Ppif) or deficient in both Ppif and Mlkl. RESULTS: Crystals of calcium oxalate, monosodium urate, or calcium pyrophosphate dihydrate, as well as silica microparticles, triggered cell necrosis involving PPIF-dependent mitochondrial permeability transition. This process involves crystal phagocytosis, lysosomal cathepsin leakage, and increased release of reactive oxygen species. Mice with acute oxalosis displayed calcium oxalate crystals inside distal tubular epithelial cells associated with mitochondrial changes characteristic of mitochondrial permeability transition. Mice lacking Ppif or Mlkl or given an inhibitor of mitochondrial permeability transition displayed attenuated oxalate-induced AKI. Dual genetic deletion of Ppif and Mlkl or pharmaceutical inhibition of necroptosis was partially redundant, implying interlinked roles of these two pathways of regulated necrosis in acute oxalosis. Similarly, inhibition of mitochondrial permeability transition suppressed crystal-induced cell death in primary human tubular epithelial cells. PPIF and phosphorylated MLKL localized to injured tubules in diagnostic human kidney biopsies of oxalosis-related AKI. CONCLUSIONS: Mitochondrial permeability transition-related regulated necrosis and necroptosis both contribute to oxalate-induced AKI, identifying PPIF as a potential molecular target for renoprotective intervention.Peer reviewe
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