12,050 research outputs found

    Tuta absoluta (Povolny, 1994), an important agricultural pest in Malta (Lepidoptera: Gelechiidae)

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    Tuta absoluta appeared for the first time in the Maltese Islands in April 2009. Details of the morphology and biology of this agricultural pest are provided. The damage caused on tomatoes and the possible impact on Maltese agriculture is discussed.peer-reviewe

    Dynamic Model Averaging for Practitioners in Economics and Finance: The eDMA Package

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    Raftery, Karny, and Ettler (2010) introduce an estimation technique, which they refer to as Dynamic Model Averaging (DMA). In their application, DMA is used to predict the output strip thickness for a cold rolling mill, where the output is measured with a time delay. Recently, DMA has also shown to be useful in macroeconomic and financial applications. In this paper, we present the eDMA package for DMA estimation implemented in R. The eDMA package is especially suited for practitioners in economics and finance, where typically a large number of predictors are available. Our implementation is up to 133 times faster then a standard implementation using a single-core CPU. Thus, with the help of this package, practitioners are able to perform DMA on a standard PC without resorting to large clusters, which are not easily available to all researchers. We demonstrate the usefulness of this package through simulation experiments and an empirical application using quarterly U.S. inflation data.Comment: 21 pages, 5 figures, 2 table

    Blow Up for the Semilinear Wave Equation in Schwarzschild Metric

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    We study the semilinear wave equation in Schwarzschild metric (3+1 dimensional space--time). First, we establish that the problem is locally well--posed in \cs H^\sigma for any σ1\sigma \geq 1; then we prove the blow up of the solution for every real p]1,1+2[p \in ]1,1+\sqrt{2}[ and non--negative non--trivial initial data.Comment: some typos are corrected and some references are adde

    Notes on two interesting specimens of Hippotion celerio (Linnaeus) (Lepidoptera, Sphingidae)

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    Moths of the genus Hippotion Hübner, 1822 (Family: Sphingidae) are distributed in Africa, Central and southern Asia and as migrants in southern Europe and Australia. Currently, around 30 species are accommodated in this genus. Hippotion celerio is a regular migrant to the Maltese Islands. On the onset of warmer weather conditions, colonies establish themselves in North Africa and Europe. It is a resident species in the Azores and the Atlantic coast of Morocco and most probably also in the Levant, the Arabian Peninsula and Egyptpeer-reviewe

    Introducing Dynamic Behavior in Amalgamated Knowledge Bases

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    The problem of integrating knowledge from multiple and heterogeneous sources is a fundamental issue in current information systems. In order to cope with this problem, the concept of mediator has been introduced as a software component providing intermediate services, linking data resources and application programs, and making transparent the heterogeneity of the underlying systems. In designing a mediator architecture, we believe that an important aspect is the definition of a formal framework by which one is able to model integration according to a declarative style. To this purpose, the use of a logical approach seems very promising. Another important aspect is the ability to model both static integration aspects, concerning query execution, and dynamic ones, concerning data updates and their propagation among the various data sources. Unfortunately, as far as we know, no formal proposals for logically modeling mediator architectures both from a static and dynamic point of view have already been developed. In this paper, we extend the framework for amalgamated knowledge bases, presented by Subrahmanian, to deal with dynamic aspects. The language we propose is based on the Active U-Datalog language, and extends it with annotated logic and amalgamation concepts. We model the sources of information and the mediator (also called supervisor) as Active U-Datalog deductive databases, thus modeling queries, transactions, and active rules, interpreted according to the PARK semantics. By using active rules, the system can efficiently perform update propagation among different databases. The result is a logical environment, integrating active and deductive rules, to perform queries and update propagation in an heterogeneous mediated framework.Comment: Other Keywords: Deductive databases; Heterogeneous databases; Active rules; Update
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