9,561 research outputs found

    An early warning system for multivariate time series with sparse and non-uniform sampling

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    In this paper we propose a new early warning test statistic, the ratio of deviations (RoD), which is defined to be the root mean squared of successive differences divided by the standard deviation. We show that RoD and autocorrelation are asymptotically related, and this relationship motivates the use of RoD to predict Hopf bifurcations in multivariate systems before they occur. We validate the use of RoD on synthetic data in the novel situation where the data is sparse and non-uniformly sampled. Additionally, we adapt the method to be used on high-frequency time series by sampling, and demonstrate the proficiency of RoD as a classifier.Comment: 14 pages, 8 figure

    2009 Report on Chicago Region Poverty

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    In 2009, a family of four that is poor by the federal government's definition has an annual income below 22,050.Afamilythatisextremelypoorhasanincomelessthanhalfthepovertylinefortheirfamilysize−−under22,050. A family that is extremely poor has an income less than half the poverty line for their family size -- under 11,025 for a family of four. As discussions continue on the best way to help the nation weather and emerge from the recession, the focus must be on meaningful policy changes that truly lift all boats and make us collectively a much stronger nation. If solutions do not specifically address the needs of those whose lives and hardships are reflected in this report, millions will be left behind, and we will all be left weaker and more vulnerable

    When Should Sellers Use Auctions?

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    A bidding process can be organized so that offers are submitted simultaneously or sequentially. In the latter case, potential buyers can condition their behavior on previous entrants' decisions. The relative performance of these mechanisms is investigated when entry is costly and selective, meaning that potential buyers with higher values are more likely to participate. A simple sequential mechanism can give both buyers and sellers significantly higher payoffs than the commonly used simultaneous bid auction. The findings are illustrated with parameters estimated from simultaneous entry USFS timber auctions where our estimates predict that the sequential mechanism would increase revenue and efficiency.

    Eyewitness identification evidence: procedural developments and the ends of adjudicative accuracy

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    This article provides critical analysis of some of the more notable procedural developments relating to eyewitness identification evidence over the past decade

    Back Home Again: LaPorte County, Indiana, Plan to End Homelessness

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    The Social IMPACT Research Center (IMPACT), a program of Heartland Alliance, worked with leaders in LaPorte County, Indiana to create a Plan to End Homelessness for the county. Plans to End Homelessness help communities determine and implement key system improvements, build community and political will for addressing homelessness, align resources efficiently, and begin the important march toward ending homelessness.LaPorte County's Plan to End Homelessness harnesses best practices, local realities, and community input to solve a problem that affects far too many lives: those who are at risk of homelessness, those who are experiencing homelessness, and their children, neighbors, friends, and family.LaPorte County's Plan includes goals in three areas: prevention, housing, and income/services with a number of action steps established to reach each goal. The Plan is designed to serve those who have been identified as needing services in LaPorte County, to help service providers enhance and streamline services, and help funders of the homeless system target funding and community resources to prevent and end homelessness

    Intrinsic unpredictability of strong El Ni\~no events

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    The El Ni\~no-Southern Oscillation (ENSO) is a mode of interannual variability in the coupled equatorial ocean/atmosphere Pacific. El Ni\~no describes a state in which sea surface temperatures in the eastern Pacific increase and upwelling of colder, deep waters diminishes. El Ni\~no events typically peak in boreal winter, but their strength varies irregularly on decadal time scales. There were exceptionally strong El Ni\~no events in 1982-83, 1997-98 and 2015-16 that affected weather on a global scale. Widely publicized forecasts in 2014 predicted that the 2015-16 event would occur a year earlier. Predicting the strength of El Ni\~no is a matter of practical concern due to its effects on hydroclimate and agriculture around the world. This paper presents a new robust mechanism limiting the predictability of strong ENSO events: the existence of an irregular switching between an oscillatory state that has strong El Ni\~no events and a chaotic state that lacks strong events, which can be induced by very weak seasonal forcing or noise.Comment: 4 pages, 6 figure
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