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Simple Conditions (simple + condition)
Selected AbstractsThe Reform of Pension Systems: Winners and Losers Across Generations in the United Kingdom and GermanyECONOMICA, Issue 266 2000David Miles In this paper we perform simulations with a stylized model of the United Kingdom and Germany to show which generations might be gainers, and which losers, from a transition from an unfunded to a funded state pension system. We show that it is likely that more than one generation will be direct losers as a result of a transition (especially in Germany). If more than one generation are direct losers, then, in order for those generations not to be net losers, the chain of bequests (in the initial equilibrium) needs to satisfy a simple condition, which we derive and analyse. [source] Spiral waves in bio-inspired oscillatory dissipative mediaINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5-6 2008Fernando Corinto Abstract Spiral waves are the most universal form of patterns arising in dissipative media of oscillatory and excitable nature. By focusing on oscillatory networks, whose cells admit of a Lur'e description and are linearly connected through weak couplings, the occurrence of spiral waves has been studied. In particular, the global dynamic behavior of such networks is investigated through the phase deviation equation obtained by the joint application of the harmonic balance method and Malkin's theorem. Furthermore, a simple condition for verifying the occurrence of spiral waves is provided. Copyright © 2008 John Wiley & Sons, Ltd. [source] Instability of finite-amplitude lower-neutral Eady wavesTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 620 2006M. Fantini Abstract The problem of the stability of the two-dimensional neutral Eady wave, studied numerically by Fantini and Davolio (2001) as a possible mechanism leading to strong orographic cyclogenesis, is re-examined. An approximate analytic solution is found, and a simple condition for the appearance of meridionally structured unstable secondary modes is proposed, based on the relative vorticity of the primary wave. The approximate analytic solution compares well with the numerical simulations and extends previous results. Copyright © 2006 Royal Meteorological Society [source] Preliminary evaluation of electroencephalographic entrainment using thalamocortical modellingEXPERT SYSTEMS, Issue 4 2009Dean Cvetkovic Abstract: The concept of linked oscillators in biological control systems has long been established. Frequency entrainment is a predominant explanation behind many biological rhythms. In this paper a preliminary examination of electroencephalographic entrainment is made to survey the possibility and methods of achieving signal entrainment at the highest level of neurological organization and function. A model of the thalamocortical system is employed to generate simulated electroencephalographic signals and is tested in various configurations in the search for entrainment under very simple conditions. Additionally, an analysis of the coupled Van der Pol model of the circadian rhythm controller is performed to identify the possibility of affecting that system with a drastically different coupling input signal. We were able to conclude that overall signal shape can have a significant impact on the entrainment characteristics of the system. Due to the nature of the underlying mathematical structure of the model, by examining the circadian rhythm controller, we found that it is unsuitable for entrainment to an incident entraining signal of much higher frequency. [source] Benefits and limitations of nurses taking on aspects of the clinical role of doctors in primary care: integrative literature reviewJOURNAL OF ADVANCED NURSING, Issue 8 2010Claire RashidArticle first published online: 2 JUL 2010 rashid c. (2010) Benefits and limitations of nurses taking on aspects of the clinical role of doctors in primary care: integrative literature review. Journal of Advanced Nursing,66(8), 1658,1670. Abstract Aim., This paper presents an integrative literature review of studies exploring the benefits and limitations of the recent expansion of the clinical role of nurses working in general practice in the United Kingdom. Background., Similar clinical outcomes and high levels of satisfaction with consultations undertaken by nurse practitioners compared to general practitioners in primary care have been reported in a Cochrane review [Cochrane Database of Systematic Reviews (2004) vol. 5, p. CD001271]. Since then, nurse consultations have increased considerably as general practitioners have delegated part of their clinical workload to other general practice nurses. However, whether all general practice nurses can fulfil this extended role remains open to question. Method., An integrative review was performed. Nine electronic databases were searched. UK studies were included if they were published after the previous Cochrane review, i.e. between 2004 and 2009. Results., Eight studies were identified, most using qualitative methodology. The evidence suggested that the changes in nurses' role have been predominantly driven by the perceived increase in workload arising from the new general practitioner contract. Delegating work to nurses provided a means of organizing workload within a practice without necessarily allowing patient choice. Patients generally thought that all general practice nurses would be able to deal with simple conditions, but they would prefer to consult with a general practitioner if they thought it necessary. There were concerns about nurses' knowledge base, particularly in diagnostics and therapeutics, and their levels of training and competence in roles formerly undertaken by general practitioners. Conclusion., There have been few studies in this key area of healthcare policy. There is a need for better training and support for nurses undertaking roles in consultation and for patients' views to be better represented. [source] A Note on Non-Negative Arma ProcessesJOURNAL OF TIME SERIES ANALYSIS, Issue 3 2007Henghsiu Tsai Abstract., Recently, there has been much research on developing models suitable for analysing the volatility of a discrete-time process. Since the volatility process, like many others, is necessarily non-negative, there is a need to construct models for stationary processes which are non-negative with probability one. Such models can be obtained by driving autoregressive moving average (ARMA) processes with non-negative kernel by non-negative white noise. This raises the problem of finding simple conditions under which an ARMA process with given coefficients has a non-negative kernel. In this article, we derive a necessary and sufficient condition. This condition is in terms of the generating function of the ARMA kernel which has a simple form. Moreover, we derive some readily verifiable necessary and sufficient conditions for some ARMA processes to be non-negative almost surely. [source] Approximation algorithms for general one-warehouse multi-retailer systemsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 7 2009Zuo-Jun Max Shen Abstract Logistical planning problems are complicated in practice because planners have to deal with the challenges of demand planning and supply replenishment, while taking into account the issues of (i) inventory perishability and storage charges, (ii) management of backlog and/or lost sales, and (iii) cost saving opportunities due to economies of scale in order replenishment and transportation. It is therefore not surprising that many logistical planning problems are computationally difficult, and finding a good solution to these problems necessitates the development of many ad hoc algorithmic procedures to address various features of the planning problems. In this article, we identify simple conditions and structural properties associated with these logistical planning problems in which the warehouse is managed as a cross-docking facility. Despite the nonlinear cost structures in the problems, we show that a solution that is within ,-optimality can be obtained by solving a related piece-wise linear concave cost multi-commodity network flow problem. An immediate consequence of this result is that certain classes of logistical planning problems can be approximated by a factor of (1 + ,) in polynomial time. This significantly improves upon the results found in literature for these classes of problems. We also show that the piece-wise linear concave cost network flow problem can be approximated to within a logarithmic factor via a large scale linear programming relaxation. We use polymatroidal constraints to capture the piece-wise concavity feature of the cost functions. This gives rise to a unified and generic LP-based approach for a large class of complicated logistical planning problems. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009 [source] Hitting time of large subsets of the hypercubeRANDOM STRUCTURES AND ALGORITHMS, Issue 2 2008ernư Abstract We study the simple random walk on the n -dimensional hypercube, in particular its hitting times of large (possibly random) sets. We give simple conditions on these sets ensuring that the properly rescaled hitting time is asymptotically exponentially distributed, uniformly in the starting position of the walk. These conditions are then verified for percolation clouds with densities that are much smaller than (n log n) -1. A main motivation behind this article is the study of the so-called aging phenomenon in the Random Energy Model, the simplest model of a mean-field spin glass. Our results allow us to prove aging in the REM for all temperatures, thereby extending earlier results to their optimal temperature domain. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008 [source] | |||||||||||||