6,431 research outputs found

    Quantiles for Counts

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    This paper studies the estimation of conditional quantiles of counts. Given the discreteness of the data, some smoothness has to be artificially imposed on the problem. The methods currently available to estimate quantiles of count data either assume that the counts result from the discretization of a continuous process, or are based on a smoothed objective function. However, these methods have several drawbacks. We show that it is possible to smooth the data in a way that allows inference to be performed using standard quantile regression techniques. The performance and implementation of the estimator are illustrated by simulations and an application.Asymmetric maximum likelihood, Jittering, Maximum score estimator, Quantile regression, Smoothing.

    Quantiles for Fractions and Other Mixed Data

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    This paper studies the estimation of quantile regression for fractional data, focusing on the case where there are mass-points at zero or/and one. More generally, we propose a simple strategy for the estimation of the conditional quantiles of data from mixed distributions, which combines standard results on the estimation of censored and Box-Cox quantile regressions. The implementation of the proposed method is illustrated using a well-known dataset.

    Macroecology of parental care in arthropods: higher mortality risk leads to higher benefits of offspring protection in tropical climates

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    The intensity of biotic interactions varies around the world, in such a way that mortality risk imposed by natural enemies is usually higher in the tropics. A major role of offspring attendance is protection against natural enemies, so the benefits of this behaviour should be higher in tropical regions. We tested this macroecological prediction with a meta-regression of field experiments in which the mortality of guarded and unguarded broods was compared in arthropods. Mortality of unguarded broods was higher, and parental care was more beneficial, in warmer, less seasonal environments. Moreover, in these same environments, additional lines of defence further reduced offspring mortality, implying that offspring attendance alone is not enough to deter natural enemies in tropical regions. These results help to explain the high frequency of parental care among tropical species and how biotic interactions influence the occurrence of parental care over large geographic scales. Finally, our findings reveal that additional lines of defences – an oftentimes neglected component of parental care – have an important effect on the covariation between the benefits of parental care and the climate-mediated mortality risk imposed by natural enemies

    ANCA-positive vasculitis: Clinical implications of ANCA types and titers

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    INTRODUCTION: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is an autoimmune disease that can affect multiple organs, the kidney being one of the most affected. Apart from the diagnostics value of ANCA, they have also been advocated as biomarkers of the disease activity. Recently, the genetic changes found in polyangiitis associated with serine-protease proteinase 3 (PR3)-ANCA or myeloperoxidase (MPO)-ANCA raised the possibility of immune-pathogenic and therapeutic differences. OBJECTIVE: To identify differences in the number of relapses, inflammatory markers, outcomes and renal histology related to the types of ANCA. To analyze the implications of ANCA titers in prognosis. METHOD: A retrospective observational study in a Portuguese tertiary hospital. RESULTS: There were no differences in the progression of renal function, histological pattern and initial treatment with regard to ANCA subtypes. As for the evaluated parameters, there were no significant differences according to the types of ANCA, except for mean CRP values within the normal range, which was 6.3±1.3 mg/L for MPO-ANCA and 12.4±10.14 mg/L for PR3-ANCA (p=0.04). We found that 66.7% of the MPO-ANCA-positive showed no relapses versus 40% in the case of PR3-ANCA-positive. There was no correlation between the ANCA titers at presentation, during remission, and in the last evaluation, and the number of relapses. CONCLUSION: PR3-ANCA patients have a mean CRP value within the normal range significantly higher than that of MPO-ANCA patients (p=0.04), which seems to reveal greater inflammatory activity in the first.info:eu-repo/semantics/publishedVersio

    On the derivation of class diagrams from use cases and logical software architectures

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    The transformation of user requirements into system requirements models can be achieved using the 4-Step Rule Set (4SRS) method that transforms UML use case diagrams into system-level object diagrams. These diagrams represent the logical architecture of the system, integrating the system-level entities, their responsibilities and the relationships among them. The logical architecture captures the system functional requirements and its nonfunctional intentionalities. Although contributing to the formalization of the design of software architectures, the 4SRS method needs to be extended in order to support the design of the database subsystems that may be considered pertinent within the specified logical architecture. This paper presents the extension of the 4SRS method to support the construction of the class diagram that complements the logical architecture, and shows, through the presentation of a demonstration case, the applicability of the proposed approach.(undefined

    Smart and sustainable cities in the Mediterranean region: The contribution of short supply chains of food

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    The cities around the world in general, and in the Mediterranean area in particular, are facing tremendous challenges at the environmental, social, economic, and institutional levels, due to the urbanization trend, environmental climatic changes and challenges due to the ongoing COVID-19 pandemic. Therefore, cities need to be sustainable and smart in the future. An economically important and innovative sector in urban areas is food security. Nowadays, most of the literature explores the concept of smart cities from the point of view of information and communications technology, indeed, the connection with the sustainability aspects of the food supply chain and the ways to operationalize that, remains unsolved. This paper tries to overcome this gap in the literature. The main aim is to analyze the contribution of the short supply chain of food in terms of sustainability in smart cities, regarding current urban trends in cities in general and in Mediterranean areas in particular. The methodology was based on a literature review and includes quantitative and qualitative analysis. The results confirm the existence of positive impacts in the short supply chains of food in urban areas in terms of sustainability. Despite the existence of a considerable number of papers about smart cities and ICT-related topics, the benefits from society of short supply chains of food, and the linkage among the topics and subjects, remain unreferred to or with a limited knowledge exchange. The conclusions of this paper will be helpful for public decision makers to implement policies in order to promote the sustainability of Mediterranean cities.info:eu-repo/semantics/publishedVersio

    A UML-based approach for modeling industrial control applications

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    The main purpose of the poster is to present how the Unified Modeling Language (UML) can be used for diagnosing and optimizing real industrial production systems. By using a car radios production line as a case study, the poster shows the modeling process that can be followed during the analysis phase of complex control applications. In order to guarantee the continuity mapping of the models, the authors propose some guidelines to transform the use cases diagrams into a single object diagram, which is the main diagram for the next phases of the development.This work has been partially funded by the Portuguese Science & Technology Foundation project PRAXIS/P/EEI/10155/1998, Recon gurable Embedded Systems: Development Methodologies for Real-Time Application
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