2,150 research outputs found

    Does European Monetary Union make inflation dynamics more uniform?

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    Using a nonparametric method to characterize Markovian operators, we describe the evolution of the short-run inflation processes among the EMU countries between 1996 and 2012. While a progressive clustering pattern can be outlined in the first half of the period - showing that the monetary union makes price dynamics more homogeneous - starting from 2004 an increase in price volatility makes the clustering pattern unstable, as the analysis of the changing points of the inflation processes confirms

    Invariant and metric free proximities for data matching: an R package

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    Data matching is a typical statistical problem in non experimental and/or observa- tional studies or, more generally, in cross-sectional studies in which one or more data sets are to be compared. Several methods are available in the literature, most of which based on a particular metric or on statistical models, either parametric or nonparametric. In this paper we present two methods to calculate a proximity which have the property of being invariant under monotonic transformations. These methods require at most the notion of ordering. An open-source software in the form of a R package is also presented

    A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

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    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high speed flow fields

    cem: Software for Coarsened Exact Matching

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    This program is designed to improve causal inference via a method of matching that is widely applicable in observational data and easy to understand and use (if you understand how to draw a histogram, you will understand this method). The program implements the coarsened exact matching (CEM) algorithm, described below. CEM may be used alone or in combination with any existing matching method. This algorithm, and its statistical properties, are described in Iacus, King, and Porro (2008)

    Análise de relevância da agricultura familiar no estado do Pará.

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    Este trabalho identificou municípios paraenses nos quais a agricultura familiar apresenta-se com relevância e potencial de desenvolvimento contrastante. Examinando-se as 12 Regiões de Integração (RI) definidas pelo governo do Estado do Pará, foram gerados rankings dos municípios em cada RI para a relevância da agricultura familiar conforme duas variáveis: a porcentagem da área municipal em estabelecimentos da agricultura familiar, e a produção da cultura da mandioca. Constatou-se que a importância da agricultura familiar não deve ser definida apenas a partir de uma variável. Utilizando-se estas duas variáveis para analisar a relevância do segmento, em 24 possíveis situações (12 RI, municípios com maior e menor índice para cada variável) houve coincidência entre rankings de municípios em apenas uma das situações

    Controlling for Selection Bias in Social Media Indicators through Official Statistics: a Proposal

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    With the increase of social media usage, a huge new source of data has become available. Despite the enthusiasm linked to this revolution, one of the main outstanding criticisms in using these data is selection bias. Indeed, the reference population is unknown. Nevertheless, many studies show evidence that these data constitute a valuable source because they are more timely and possess higher space granularity. We propose to adjust statistics based on Twitter data by anchoring them to reliable official statistics through a weighted, space-time, small area estimation model. As a by-product, the proposed method also stabilizes the social media indicators, which is a welcome property required for official statistics. The method can be adapted anytime official statistics exists at the proper level of granularity and for which social media usage within the population is known. As an example, we adjust a subjective wellbeing indicator of \u201cworking conditions\u201d in Italy, and combine it with relevant official statistics. The weights depend on broadband coverage and the Twitter rate at province level, while the analysis is performed at regional level. The resulting statistics are then compared with survey statistics on the \u201cquality of job\u201d at macro-economic regional level, showing evidence of similar paths

    Development of a laser-induced heat flux technique for measurement of convective heat transfer coefficients in a supersonic flowfield

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    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the load surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimental results agreed reasonably well with theoretical predictions of convective heat transfer of flat plate laminar boundary layers. The results indicate that this non-intrusive optical measurement technique has the potential to obtain high quality surface convective heat transfer measurements in high speed flowfields

    An ASP-Based Approach to Scheduling Pre-operative Assessment Clinic

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    The problem of scheduling Pre-Operative Assessment Clinic (PAC) consists of assigning patients to a day for the exams needed before a surgical procedure, taking into account patients with different priority levels, due dates, and operators availability. Realizing a satisfying schedule is of upmost importance for a clinic, since delay in PAC can cause delay in the subsequent phases, causing a decrease in patients’ satisfaction. In this paper, we divide the problem in two sub-problems: In the first sub-problem patients are assigned to a day taking into account a default list of exams; then, in the second sub-problem, having the actual list of exams needed by each patient, we use the results of the first sub-problem to assign a starting time to each exam. We first present a mathematical formulation for both problems. Then, we present solutions based on Answer Set Programming (ASP): The first solution is a genuine ASP encoding of the sub-problems, while the second introduces domain-specific optimizations. Experiments show that both solutions provide satisfying results in short time, while the second is able to prove optimality faster

    Invariant and metric free proximities for data matching : an R package

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    Data matching is a typical statistical problem in non experimental and/or observational studies or, more generally, in cross-sectional studies in which one or more data sets are to be compared. Several methods are available in the literature, most of which based on a particular metric or on statistical models, either parametric or nonparametric. In this paper we present two methods to calculate a proximity which have the property of being invariant under monotonic transformations. These methods require at most the notion of ordering. An open-source software in the form of a R package is also presented
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