Persistence exponent for discrete-time, time-reversible processes

We study the persistence probability for some discrete-time, time-reversible processes. In particular, we deduce the persistence exponent in a number of examples: first, we deal with random walks in random sceneries (RWRS) in any dimension with Gaussian scenery. Second, we deal with sums of stationary Gaussian sequences with correlations exhibiting long-range dependence. Apart from the persistence probability we deal with the position of the maximum and the time spent on the positive half-axis by the process

Persistence probabilities for stationary increment processes

We study the persistence probability for processes with stationary increments. Our results apply to a number of examples: sums of stationary correlated random variables whose scaling limit is fractional Brownian motion, random walks in random sceneries, random processes in Brownian scenery, and the Matheron-de Marsily model in Z^2 with random orientations of the horizontal layers. Using a new approach, strongly related to the study of the range, we obtain an upper bound of optimal order in the general case and improved lower bounds (compared to previous literature) for many processes.Comment: This version corrects some mistakes from the printed version. In particular, the assumptions of Theorem 4 needed to be changed; Theorem 20 needed an extra assumption; the proof of Theorem 11 has been change

Random walks and branching processes in correlated Gaussian environment

We study persistence probabilities for random walks in correlated Gaussian random environment first studied by Oshanin, Rosso and Schehr. From the persistence results, we can deduce properties of critical branching processes with offspring sizes geometrically distributed with correlated random parameters. More precisely, we obtain estimates on the tail distribution of its total population size, of its maximum population, and of its extinction time

Tiotropium suppresses acetylcholine-induced release of chemotactic mediators in vitro

SummaryThe driving force in the progression of COPD is the development of exacerbations which are mostly the result of excessive inflammation. Bronchodilatators play an important role in the treatment of COPD. The reported reduction in exacerbation rates in COPD is due to the inhibition of vagal-mediated bronchoconstriction and mucus secretion. However, recent studies have highlighted the existence of muscarinic receptors on inflammatory cells and we have explored the possibility that tiotropium bromide might also inhibit neutrophil migration. We analysed the influence of tiotropium on the release of neutrophil chemotactic activity in response to acetylcholine (ACh) and the expression of muscarinic receptors on human alveolar macrophages (AM), A549 cells, MonoMac6 cells, and human lung fibroblasts. We found significant levels of all muscarinic receptor subtypes on all analysed cells except the fibroblasts. Fibroblasts expressed predominantly M2, receptors and did not release chemotactic activity. AM, A549 cells, and MonoMac6 cells released chemotactic active mediators after incubation with ACh. The secretion could be suppressed by more than 70% after coincubation with tiotropium. Tiotropium alone did not influence the granulocyte migration. Most of the chemotactic activity could be attributed to leukotriene B4 (LTB4). The release of interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) was not induced by ACh. From this, we suggest that the suppression of the Ach-mediated release of chemotactic substances like LTB4 modulates the inflammatory reaction. This may contribute to the decreased rate of exacerbations in COPD, which was observed in clinical trials

The ISAF withdrawal from Afghanistan: perceptions and reactions of regional powers

At a conference in Tokyo on 8 July 2012, Afghanistan's donors pledged 16 billion USD in reconstruction aid over the next four years. At the NATO Summit in Chicago in May 2012, a comparable sum had been committed to supporting the Afghanistan National Security Forces (ANSF). Analysis: The international community is anxious to reassure the Afghan government that it will not be left to fend for itself after the International Security Assistance Force (ISAF) troops are withdrawn at the end of 2014. Nevertheless, the fear remains that a power vacuum and another takeover by the Taliban could throw the country into turmoil once again. The destabilization of Afghanistan would most affect the neighboring countries. Yet despite sharing similar threat perceptions, these states are pursuing very different goals in Afghanistan that impede effective regional cooperation. The US, which would like to see its influence in Afghanistan maintained, curbs all initiatives that are not in line with its interests. The US is pursuing the vision of an economically integrated region in which Afghanistan will be the central stretch of a new “Silk Road” between Central and South Asia, and the Middle East and East Asia. The implicit notion is that economic integration will lead to increased stability in the security sector, but at best, that would only be attainable in the long term. In the short term, it is more likely that political differences between the regional states will hinder economic cooperation. China and India are aiming to more closely incorporate Afghanistan in regional organizations within their own spheres of influence. Both nations fear a post-2014 destabilization of Afghanistan that would directly affect their security – especially through the strengthening of Islamist terror groups. Other states are also concerned about the developments in Afghanistan. Iran, for example, is pursuing an ambivalent policy, fearing both the continuation of American influence after 2014 and a Taliban takeover

Benchmarking G2B eServices in the US: A Survey to Identify Maturity Levels Based on the Mystery User Approach

As public administrations are increasingly transforming towards customer-oriented service providers, the availability of municipal E-Services increases. Particularly, E-Services addressed to Small and Medium Sized Enterprises (SMEs) representing 90 % of all enterprises in the U.S. are of interest. While generic surveys on E-Government portals are conducted manifold, surveys dedicated to Government-to-Business (G2B) E-Services are neglected. Thus, the paper presents the status quo by illustrating the results of a benchmarking survey. The survey analyzes the offer of G2B E-Services in 50 U.S. large and capital cities. Furthermore, the identified criteria for the survey provide a basis for a maturity model. The study is accomplished according to the “Procedural model for the Benchmarking of Service” – DIN PAS 1014 and is conducted with the “Mystery User” approach. The findings of the survey address academic research as well as administration practice in the context of E-Government

Familienexterne Nachfolge im Freistaat Sachsen: Das Zusammenfinden von Übergebern und Übernehmern

Im Freistaat Sachsen stehen - je nach Schätzung - mit 1.700 bis 2.700 betroffenen Familienunternehmen pro Jahr die meisten Nachfolgeregelungen in den neuen Bundesländern an. Familienexterne Nachfolgelösungen gewinnen dabei in den letzten Jahren zunehmend an Bedeutung. Vor allem wegen des Bevölkerungsschwunds insbesondere qualifizierter junger Menschen in den 1990er Jahren ist zu erwarten, dass das Finden eines familienexternen Nachfolgers im Freistaat Sachsen ebenso wie in den übrigen neuen Bundesländern schwieriger ist als im Altbundesgebiet. Vor diesem Hintergrund hat das Sächsische Staatsministerium für Wirtschaft und Arbeit das IfM Bonn mit einem Gutachten beauftragt. Dieses liefert neben Befunden zu den Problemen beim Finden eines familienexternen Nachfolgers in Ostdeutschland und insbesondere im Freistaat Sachsen auch Erkenntnisse über den persönlichen und qualifikatorischen Hintergrund von Personen, die prinzipiell als Nachfolger in Frage kommen. --