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Substantial Period (substantial + period)
Selected AbstractsProportional Intensity Models Robustness with Overhaul IntervalsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 3 2006Shwu-Tzy Jiang Abstract The class of semi-parametric proportional intensity (PI) models applies to recurrent failure event modeling for a repairable system with explanatory variables (covariates). Certain repairable systems (e.g. aircraft and electrical power generating plants) experience a substantial period of downtime due to performing maintenance (i.e. major overhaul) at scheduled intervals or following a major failure. Other systems (e.g. emergency power units) experience extended periods of non-operating dormancy. These discontinuities in observation time have potential effects on the accuracy of estimation for covariate effects, particularly where calendar time is the life metric. This paper examines the robustness of two PI methods (Prentice,Williams,Peterson gap time (PWP-GT) and Andersen,Gill (AG)) as a function of the overhaul or dormancy duration. The PWP-GT model proves to perform well for sample size of 60 (30 per level of a class covariate), constant or moderately decreasing/increasing rate of occurrence of failures, and relative overhaul (dormancy) durations less than half of the immediately preceding interval between failures. The AG model performs consistently well for a small sample size of 20 (10 per level of a class covariate) for homogeneous Poisson processes, regardless of the relative overhaul (dormancy) duration. Copyright © 2005 John Wiley & Sons, Ltd. [source] Prolonged Survival of Allogeneic Islets in Cynomolgus Monkeys After Short-Term Anti-CD154-Based Therapy: Nonimmunologic Graft Failure?AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2006M. Koulmanda Conventional drug therapy and several anti-CD154 mAb-based regimens were tested in the nonhuman primate (NHP) islet allograft model and found to be inadequate because islets were lost to rejection. Short-term therapy with an optimized donor-specific transfusion (DST) + rapamycin (RPM) + anti-CD154 mAb regimen enables immunosuppression drug-free islet allograft function for months following cessation of therapy in the NHP islet allograft model. After a substantial period of drug-free graft function, these allografts slowly and progressively lost function. Pathologic studies failed to identify islet allograft rejection as a destructive islet invasive lymphocytic infiltration of the allograft was not detected. To evaluate the mechanism, immunologic versus nonimmunologic, of the late islet allograft loss in hosts receiving the optimized therapeutic regimen, we performed experiments with islet autografts and studied islet function in NHPs with partial pancreatectomy. The results in both experiments utilizing autologous islet allografts and partially pancreatectomized hosts reinforce the view that the presence of a marginal islet mass leads to slowly progressive nonimmunological islet loss. Long-term clinically successful islet cell transplantation cannot be realized in the absence of parallel improvements in tolerizing regimens and in the preparation of adequate numbers of islets. [source] The Story of Istanbul's ModernisationARCHITECTURAL DESIGN, Issue 1 2010lhan Tekeli Abstract Since reform started under Ottoman rule in the early 19th century, Istanbul has undergone a substantial period of modernisation that has spanned more than 150 years. ,lhan Tekeli outlines the metropolis' enduring development, characterising Istanbul's transformation into a modern city into four distinct periods. It is a story that bridges the collapse of the Ottoman Empire and the reconstruction of the Turkish Republic as a nation-state, with the initial demise of the city in favour of Ankara; and continues with Istanbul regaining its status as a world city; as it evolves from a monstrous industrial city to an urban region and global centre. Copyright © 2010 John Wiley & Sons, Ltd. [source] A new paradigm for operative dentistryAUSTRALIAN DENTAL JOURNAL, Issue 4 2007GJ Mount Abstract It is over 100 years since GV Black gathered together most of the knowledge then current on the caries process and set clear parameters for the discipline of operative dentistry. His four-volume treatise set standards that were relevant for the times and, in fact, were so well described that they remained dominant in this discipline until quite recently. However, over the last 50 years there has been great progress in scientific method and in knowledge of the common diseases of the oral environment, including the caries process, so maybe it is time for change. The term "paradigm" describes a philosophy of science, a generally accepted model of how ideas relate to one another, forming a conceptual framework within which scientific research is carried out. Black defined the paradigm within which further research was to be conducted during the following years and the profession accepted his lead. However, it is not expected that the parameters of a profession should remain unchanged over a substantial period so it is suggested that the dental profession should, at this time, recognize a new paradigm. Improvements in scientific method have led to a better understanding of the oral environment, resulting in extensive changes for this profession. It is suggested that the standards set by Black should be now consigned to history and an entirely new paradigm adopted. First, the profession must recognize that dental caries is a bacterial disease and its primary efforts should be directed towards identification and elimination of the disease prior to initiating repair of the damage that it has caused. Preservation of natural tooth structure is then the next responsibility. There should be maximum use made of preventive strategies, including remineralization, followed by minimal intervention cavity designs and the use of bioactive restorative materials to restore the lesions. The profession should be prepared to move on. [source] Biological bases of face preference in 6-week-old infantsDEVELOPMENTAL SCIENCE, Issue 5 2003Elliott M. Blass Six-week-old infants (N =40) who started the experiment in either a calm or crying state, received sucrose from an experimenter, while in eye contact with her. Sucrose was delivered either by syringe or on a pacifier. After 3.5 min., the experimenter retired, the mother came into the test room and placed her infant over her shoulder en face with a video camera. The experimenter and a confederate, both dressed identically, sat in front of and slightly to either side of the infant and the infant could choose to look at either experimenter. To minimize position bias, experimenters switched sides every 30 sec. To maintain a stable level of infant attention, they simultaneously called the baby's name at 10 sec. intervals. When an infant looked at one or the other experimenters, she raised her thumb in camera view. Only crying infants who sucked a sweet pacifier showed a preference for their experimenter. As a group none of the other infants did so. However, there was a wide distribution of sucking times in calm week 6 infants. Choice was linearly related to sucking duration. Infants who sucked for substantial periods of time, showed a strong preference for the experimenter. Those who sucked for minimal periods of time strongly preferred the confederate. Based on these findings and ones from 9- and 12-week-old infants, a model is presented in which preference in this experimental paradigm is determined by idealized levels of central activation. These levels may be inferred from the normal crying function at a particular age. [source] Public Pension Reform in the United Kingdom: What Effect on the Financial Well-Being of Current and Future Pensioners?,FISCAL STUDIES, Issue 1 2005Richard Disney Abstract Unlike many tax and benefit changes, reforms to public pension programmes take many years to have their full effect. This paper examines the effect of reforms to the public pension programme in the United Kingdom on the state retirement incomes of current generations of pensioners and on the prospective state incomes of future generations of pensioners. We show that, for an individual with lifetime earnings close to male average earnings, the UK pension system is at its most generous to those reaching the state pension age around the year 2000, but that the introduction of the state second pension and the pension credit postpones this peak for individuals on lower incomes and for those with substantial periods out of paid employment spent with caring responsibilities. We also consider how the ,mix' of benefits, particularly between the contributory and income-tested sectors, could change over time, and the impact that this would have on incentives to save for retirement. [source] The lawsonite paradox: a comparison of field evidence and mineral equilibria modellingJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2006G. L. CLARKE Abstract Lawsonite equilibria are predicted to occur over a broad P,T spectrum developed during subduction, yet lawsonite-bearing assemblages are rare. In the context of mafic mineral equilibria modelled for the range of common crustal metamorphism (4,23 kbar, 400,750 °C) using the system Na2O-CaO-K2O-FeO-MgO-Al2O3 -SiO2 -H2O and the software thermocalc, unusually high water contents are demanded by lawsonite assemblages. As a consequence, lawsonite assemblages are predicted to have difficulty forming and lawsonite equilibria to be uncommon. Metabasalt undergoing cooler subduction may experience substantial periods involving the metastable persistence of mineral assemblages because of water under-saturation with non-occurrence of recrystallization. If formed, lawsonite-bearing assemblages are observed to be highly unstable; their preservation requires that exhumation be accompanied by substantial cooling. The amount of structurally bound H2O in minerals plays a critical role in the formation and preservation of mineral assemblages, controlling key changes in rocks undergoing subduction. [source] GETTING THE BALANCE RIGHT?AUSTRALIAN JOURNAL OF RURAL HEALTH, Issue 4 2003GPS WHO CHOSE TO STAY IN RURAL PRACTICE ABSTRACT Background: Despite major challenges to the retention of rural GPs in Australia, little is known about why some rural GPs stay long-term within their communities. Method: A group of rural GPs interviewed as part of another study about 10 years ago were re-interviewed to explore their attitudes to their reasons for staying. Results: Eighteen of the original group of 23 could be contacted and 13 were interviewed. Factors that appeared to promote staying in rural practice were: strong attachment to the community; and practice arrangements that allow for adequate time off-call and for holidays. However, several GPs were stressed and some had considered leaving. The stressors were similar to those identified in earlier research, including overwork and having to send children to boarding school. Conclusion: Personal and professional support arrangements within the community appear to be associated with decisions by rural GPs to remain in practice for substantial periods of time. Retention strategies should focus on facilitation of local integration. [source] | |||||||||||||