18,070 research outputs found

    Income distribution patterns from a complete social security database

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    We analyze the income distribution of employees for 9 consecutive years (2001-2009) using a complete social security database for an economically important district of Romania. The database contains detailed information on more than half million taxpayers, including their monthly salaries from all employers where they worked. Besides studying the characteristic distribution functions in the high and low/medium income limits, the database allows us a detailed dynamical study by following the time-evolution of the taxpayers income. To our knowledge, this is the first extensive study of this kind (a previous japanese taxpayers survey was limited to two years). In the high income limit we prove once again the validity of Pareto's law, obtaining a perfect scaling on four orders of magnitude in the rank for all the studied years. The obtained Pareto exponents are quite stable with values around α2.5\alpha \approx 2.5, in spite of the fact that during this period the economy developed rapidly and also a financial-economic crisis hit Romania in 2007-2008. For the low and medium income category we confirmed the exponential-type income distribution. Following the income of employees in time, we have found that the top limit of the income distribution is a highly dynamical region with strong fluctuations in the rank. In this region, the observed dynamics is consistent with a multiplicative random growth hypothesis. Contrarily with previous results obtained for the japanese employees, we find that the logarithmic growth-rate is not independent of the income.Comment: 10 pages, 7 Figure

    The Promise of Health Information Technology: Ensuring that Florida's Children Benefit

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    Substantial policy interest in supporting the adoption of Health Information Technology (HIT) by the public and private sectors over the last 5 -- 7 years, was spurred in particular by the release of multiple Institute of Medicine reports documenting the widespread occurrence of medical errors and poor quality of care (Institute of Medicine, 1999 & 2001). However, efforts to focus on issues unique to children's health have been left out of many of initiatives. The purpose of this report is to identify strategies that can be taken by public and private entities to promote the use of HIT among providers who serve children in Florida

    When was Asymptotic Freedom discovered? or The Rehabilitation of Quantum Field Theory

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    We glance back at the short period of the great discoveries between 1970 and 1974 that led to the restablishment of Quantum Field Theory and the discovery of the Standard Model of Elementary Particles, in particular Quantum Chromodynamics, and ask ourselves where we stand now.Comment: small but important corrections were made as a response to several reactions. Minor typos corrected. 17 pages plain TeX, 4 figures PostScrip

    Almost as helpful as good theory: Some conceptual possibilities for the online classroom

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    Interest and activity in the use of C&IT in higher education is growing, and while there is effort to understand the complexity of the transition to virtual space, aspects of development, particularly clarity about the nature of the learning community, may only be lightly theorized. Based on an ongoing action research study involving postgraduate students studying in the UK and USA, this paper will identify some theoretical roots and derive from these six conceptual areas that seem to the authors to have relevance and significance for behaviour online. An exploration of these forms the basis for a two‐dimensional model which can account for what happens when groups come together to learn in cyberspace. In depicting this model, there is acknowledgement of the existence of third and fourth dimensions at work. However, the explanatory power of taking these extra dimensions into account is beyond the scope of the analysis thus far

    Are the Lebanese Firms Coping with the Global Pressure?

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    Almost all business activities in Lebanon take the form of family owned small business type. Lebanon took advanced steps on globalization issues and entered into open trading activities, which makes its firms subject to global competition. In developed nation, small businesses are facing these challenges by lowering their cost, improving quality and adopting sophisticated high technology. Logistic strategies are one way these firms are using to overcome these challenges. The purpose of this paper is to explore the use and the role of logistic strategies by small businesses in Lebanon. It will focus on the way these businesses are adopting with the global requirements. Results showed evidence that the Lebanese small businesses exhibited a little use logistic strategies, which put them on a competitive disadvantage in facing the global challenges

    Saints, Diamonds and Bears

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    A common complaint in academia goes something like this: If the essential work of education is that which occurs between student and faculty member, between students themselves, or between a student and a book, then why are so much money and so much energy spent in the nonessentials: athletics, dormitories, development and alumni offices, day-care centers, social activities-indeed , all the \u27support services\u27 of a university? Wouldn\u27t life on a campus be simpler and wouldn\u27t our work be more effective if we were to concentrate our efforts on the essentials? All of us, whether we\u27re administrators or faculty or board members, have to face this problemwhich may be more one of perception than of objective fact, but that does not make it any less real or any easier to solve

    How does interchange affect passengers' route choices in urban rail transit? - a case study of the Shanghai Metro

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    Interchange provides more flexibility in route choice, a key travel behaviour in urban rail transit, but its influence is usually simplified. This paper investigates how interchange affects route choice with passenger perception considered. At single-interchange level, perceived interchange time was proposed and modelled under three resolutions to capture passenger perception and its sensitivity. At route level, the influence of interchange was modeled by first comparing eight quantifications of interchange. Mixed logit models with the best interchange proxy were further developed to address the correlation among alternative routes and reveal the potential taste variations among passengers. Results based on Shanghai Metro data showed perceived interchange time, including passenger perception and interchange environment, better represents the influence of interchange in route choice, meanwhile the weights of interchanges on one route rise sequentially and non-linearly. The results can improve route choice prediction in demand modelling and route recommendation in advanced traveller information systems

    Large deviations analysis for the M/H2/n+MM/H_2/n + M queue in the Halfin-Whitt regime

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    We consider the FCFS M/H2/n+MM/H_2/n + M queue in the Halfin-Whitt heavy traffic regime. It is known that the normalized sequence of steady-state queue length distributions is tight and converges weakly to a limiting random variable W. However, those works only describe W implicitly as the invariant measure of a complicated diffusion. Although it was proven by Gamarnik and Stolyar that the tail of W is sub-Gaussian, the actual value of limxx2log(P(W>x))\lim_{x \rightarrow \infty}x^{-2}\log(P(W >x)) was left open. In subsequent work, Dai and He conjectured an explicit form for this exponent, which was insensitive to the higher moments of the service distribution. We explicitly compute the true large deviations exponent for W when the abandonment rate is less than the minimum service rate, the first such result for non-Markovian queues with abandonments. Interestingly, our results resolve the conjecture of Dai and He in the negative. Our main approach is to extend the stochastic comparison framework of Gamarnik and Goldberg to the setting of abandonments, requiring several novel and non-trivial contributions. Our approach sheds light on several novel ways to think about multi-server queues with abandonments in the Halfin-Whitt regime, which should hold in considerable generality and provide new tools for analyzing these systems
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