12,050 research outputs found
Tuta absoluta (Povolny, 1994), an important agricultural pest in Malta (Lepidoptera: Gelechiidae)
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
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
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 ; then we prove the blow
up of the solution for every real 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)
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
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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