309 research outputs found
Increasing the Reliability of Adaptive Quadrature Using Explicit Interpolants
We present two new adaptive quadrature routines. Both routines differ from
previously published algorithms in many aspects, most significantly in how they
represent the integrand, how they treat non-numerical values of the integrand,
how they deal with improper divergent integrals and how they estimate the
integration error. The main focus of these improvements is to increase the
reliability of the algorithms without significantly impacting their efficiency.
Both algorithms are implemented in Matlab and tested using both the "families"
suggested by Lyness and Kaganove and the battery test used by Gander and
Gautschi and Kahaner. They are shown to be more reliable, albeit in some cases
less efficient, than other commonly-used adaptive integrators.Comment: 32 pages, submitted to ACM Transactions on Mathematical Softwar
Practical Evaluation of Lempel-Ziv-78 and Lempel-Ziv-Welch Tries
We present the first thorough practical study of the Lempel-Ziv-78 and the
Lempel-Ziv-Welch computation based on trie data structures. With a careful
selection of trie representations we can beat well-tuned popular trie data
structures like Judy, m-Bonsai or Cedar
Genus Hydrangea: diversity of pigments and phenolic compounds
The most important collection of Hydrangea in Europe is located in Angers (France). It consists of over 700 germplasm accessions distributed in 13 species. Originating from Asia and America, they were introduced in Europe in the 18th century for their ornamental interest but medicinal properties may also be found in this genus since extracts from H. macrophylla are already described as exhibiting anti-diabetic [1], lipid lowering and anti-oxidative [2], anti-allergic [3] and antimalarial activities [4]. Management of the collection requires botanical, genetic and biochemical studies allowing good, reliable characterization of species, subspecies and varieties. In this context, the biochemical characterization of the inflorescences was undertaken to evaluate the intra and interspecific diversities of pigments and other phenolic compounds. Inflorescences are generally white, except for three species: H. macrophylla, H. involucrata and H .aspera which exhibit rose or blue flowers. Among them only H. macrophylla was previously studied for sepal color variation [5]. In this study, 80 accessions were analyzed by means of HPLC/DAD, LC-MS/MS and NMR experiments: 46 H. macrophylla, 13 H. aspera, 6 H. involucrata, 5 H. paniculata, 3 H. quercifolia, 2 H. arborescens, 2 H. anomala, 2 H. heteromala, 1 H. scandens, 1 H. seemannii and 1 H. integrifolia. About 50 phenolic derivatives - essentially phenolic acids and flavonols (quercetin and kaempferol) - and 20 anthocyanins could be identified. The contents of pigments and other phenolic compounds appeared as very diverse both qualitatively and quantitatively and some compounds could be identified as chemospecific. On this basis, a statistical study using Principal Component Analysis allowed a clear distinction between both species and subspecies. Besides, different biological evaluations of crude extracts and secondary metabolites isolated from Hydrangea sp will also be discussed
Glutamine synthetase and glutamate synthase activities in relation to nitrogen fixation in Lotus spp.
Digital media in primary schools: literacy or technology? Analyzing government and media discourses
This article examines the political and the media discourses concerning the
Portuguese governmental program responsible for delivering a laptop named
“Magalhães” to all primary school children. The analysis is based on the
official documents related to the launch and development of the initiative as
well as the press coverage of this topic. The main purpose is to recognize
the dominant public discourses and to find out what the media select for
the debate in the public sphere. This analysis was done with a particular
focus on the critical media literacy framework. The results reveal that the
press highlighted the negative aspects of that program and that this framing
could have a strong impact on how it was accepted and understood by the
public opinion. Analysis also reveals that the governmental initiative was
predominantly driven by technological objectives, in particular the access to
technology, rather than media literacy objectives.The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This paper is part of a three years project named "Navigating with 'Magalhaes': Study on the Impact of Digital Media in Schoolchildren" funded by FCT - Fundacao para a Ciencia e a Tecnologia (Portuguese Foundation for Science and Technology) and co-funded by FEDER - Fundo Europeu de Desenvolvimento Regional (ERDF: European Regional Development Fund) through COMPETE - Programa Operacional Factores de Competitividade (Operational Competitiveness Programme)
- …