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Renewal Process (renewal + process)

Distribution by Scientific Domains

Mathematics and Statistics	71%

Selected Abstracts

Long-Range Dependence of Markov Renewal Processes

AUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 1 2004
R.A. Vesilo
Summary This paper examines long-range dependence (LRD) and asymptotic properties of Markov renewal processes generalizing results of Daley for renewal processes. The Hurst index and discrepancy function, which is the difference between the expected number of arrivals in (0, t] given a point at 0 and the number of arrivals in (0, t] in the time stationary version, are examined in terms of the moment index. The moment index is the supremum of the set of r > 0 such that the rth moment of the first return time to a state is finite, employing the solidarity results of Sgibnev. The results are derived for irreducible, regular Markov renewal processes on countable state spaces. The paper also derives conditions to determine the moment index of the first return times in terms of the Markov renewal kernel distribution functions of the process. [source]

Cardiomyocyte precursors and telocytes in epicardial stem cell niche: electron microscope images

JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2010
Mihaela Gherghiceanu
Abstract A highly heterogeneous population of stem and progenitor cells has been described by light immunohistochemistry in the mammalian adult heart, but the ultrastructural identity of cardiac stem cells remains unknown. Using electron microscopy, we demonstrate the presence of cells with stem features in the adult mouse heart. These putative cardiac stem cells are small (6,10 ,m), round cells, with an irregular shaped nucleus, large nucleolus, few endoplasmic reticulum cisternae and mitochondria, but numerous ribosomes. Stem cells located in the epicardial stem cell niche undergo mitosis and apoptosis. Cells with intermediate features between stem cells and cardiomyocyte progenitors have also been seen. Moreover, electron microscopy showed that cardiomyocyte progenitors were added to the peripheral working cardiomyocytes. Telocytes make a supportive interstitial network for stem cells and progenitors in the stem cell niche. This study enhances the hypothesis of a unique type of cardiac stem cell and progenitors in different stages of differentiation. In our opinion, stem cells, cardiomyocyte progenitors and telocytes sustain a continuous cardiac renewal process in the adult mammalian heart. [source]

Pseudomartingale estimating equations for modulated renewal process models

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 1 2009
Fengchang Lin
Summary., We adapt martingale estimating equations based on gap time information to a general intensity model for a single realization of a modulated renewal process. The consistency and asymptotic normality of the estimators is proved under ergodicity conditions. Previous work has considered either parametric likelihood analysis or semiparametric multiplicative models using partial likelihood. The framework is generally applicable to semiparametric and parametric models, including additive and multiplicative specifications, and periodic models. It facilitates a semiparametric extension of a popular parametric earthquake model. Simulations and empirical analyses of Taiwanese earthquake sequences illustrate the methodology's practical utility. [source]

Steward Organization in a Professional Union: The Case of The Royal College of Nursing

BRITISH JOURNAL OF INDUSTRIAL RELATIONS, Issue 3 2001
Ian Kessler
This article examines notions of renewal in a professional union by exploring the developing role of the steward in the Royal College of Nursing. Drawing on survey and other data, it assesses different dimensions of the union renewal process linked to workplace activities, issues and relations. The findings suggest that the process of renewal has been based primarily upon member rather than management-facing activities, although there is strong evidence to suggest variation in the activities carried out by the RCN's ordinary and senior stewards. [source]

On the availability of R out of N repairable systems

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 5 2002
Esther Frostig
Abstract An R out of N repairable system consisting of N components and operates if at least R components are functioning. Repairable means that failed components are repaired, and upon repair completion they are as good as new. We derive formulas for the expected up-time, expected down-time, and the availability of the system, using Markov renewal processes. We assume that either the repair times of the components are generally distributed and the components' lifetimes are exponential or vice versa. The analysis is done for systems with either cold or warm stand-by. Numerical examples are given for several life time and repair time distributions. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 483,498, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10025 [source]