A systematic comparison of supervised classifiers

Pattern recognition techniques have been employed in a myriad of industrial, medical, commercial and academic applications. To tackle such a diversity of data, many techniques have been devised. However, despite the long tradition of pattern recognition research, there is no technique that yields the best classification in all scenarios. Therefore, the consideration of as many as possible techniques presents itself as an fundamental practice in applications aiming at high accuracy. Typical works comparing methods either emphasize the performance of a given algorithm in validation tests or systematically compare various algorithms, assuming that the practical use of these methods is done by experts. In many occasions, however, researchers have to deal with their practical classification tasks without an in-depth knowledge about the underlying mechanisms behind parameters. Actually, the adequate choice of classifiers and parameters alike in such practical circumstances constitutes a long-standing problem and is the subject of the current paper. We carried out a study on the performance of nine well-known classifiers implemented by the Weka framework and compared the dependence of the accuracy with their configuration parameter configurations. The analysis of performance with default parameters revealed that the k-nearest neighbors method exceeds by a large margin the other methods when high dimensional datasets are considered. When other configuration of parameters were allowed, we found that it is possible to improve the quality of SVM in more than 20% even if parameters are set randomly. Taken together, the investigation conducted in this paper suggests that, apart from the SVM implementation, Weka's default configuration of parameters provides an performance close the one achieved with the optimal configuration

Probing the Statistical Properties of Unknown Texts: Application to the Voynich Manuscript

While the use of statistical physics methods to analyze large corpora has been useful to unveil many patterns in texts, no comprehensive investigation has been performed on the interdependence between syntactic and semantic factors. In this study we propose a framework for determining whether a text (e.g., written in an unknown alphabet) is compatible with a natural language and to which language it could belong. The approach is based on three types of statistical measurements, i.e. obtained from first-order statistics of word properties in a text, from the topology of complex networks representing texts, and from intermittency concepts where text is treated as a time series. Comparative experiments were performed with the New Testament in 15 different languages and with distinct books in English and Portuguese in order to quantify the dependency of the different measurements on the language and on the story being told in the book. The metrics found to be informative in distinguishing real texts from their shuffled versions include assortativity, degree and selectivity of words. As an illustration, we analyze an undeciphered medieval manuscript known as the Voynich Manuscript. We show that it is mostly compatible with natural languages and incompatible with random texts. We also obtain candidates for keywords of the Voynich Manuscript which could be helpful in the effort of deciphering it. Because we were able to identify statistical measurements that are more dependent on the syntax than on the semantics, the framework may also serve for text analysis in language-dependent applications

Análise emergética dos sistemas de pesca no pantanal

Os sistemas de pesca (profissional-artesanal, subsistência e amadora) constituem atividades econômicas muito importantes no Pantanal. Por meio da análise emergética será avaliado seu desempenho. As primeiras análises revelam que a pesca profissional artesanal utiliza amplamente os recursos naturais, com pouca entrada de recursos econômicos externos, e o peixe é vendido para turistas e comunidade local; os fluxos são internos ao ecossistema e as externalidades são mínimas. A pesca de subsistência mostra ser auto-suficiente. A pesca amadora, por outro lado, requer maior infra-estrutura, as articulações com a economia local são limitadas e gera vários tipos de externalidades negativas. In the “Pantanal”, a very big Brazilian wetland, fishery is an important economic activity that is carried out under three modalities: professional-artisanal, subsistence and touristic. Their ecological and thermodynamic performance will be studied using the emergy methodology. As first stage of this analysis, it was realized an information recovery in order to prepare the systems diagrams. The diagrams revealed the dependence of each one of fishery systems with local and external resources. Subsistence fishery is sustainable but doesn’t have product for sale. Professional-artisanal fishery interacts with different markets and uses a small quantity of external inputs. Touristic fishery depends on infra-structure investments and do not interact in adequate form with local economy

Good practices for a literature survey are not followed by authors while preparing scientific manuscripts

The number of citations received by authors in scientific journals has become a major parameter to assess individual researchers and the journals themselves through the impact factor. A fair assessment therefore requires that the criteria for selecting references in a given manuscript should be unbiased with respect to the authors or the journals cited. In this paper, we advocate that authors should follow two mandatory principles to select papers (later reflected in the list of references) while studying the literature for a given research: i) consider similarity of content with the topics investigated, lest very related work should be reproduced or ignored; ii) perform a systematic search over the network of citations including seminal or very related papers. We use formalisms of complex networks for two datasets of papers from the arXiv repository to show that neither of these two criteria is fulfilled in practice

Caracterização socieconômica da comunidade do Amolar, sub-região do Paraguai, Corumbá, MS.

Este trabalho teve o objetivo de coletar informações qualitativas e quantitativas sobre as relações sociais e econômicas existentes entre os moradores do entorno da RPPN-EEB, comunidade do Amolar, sub-região do Rio Paraguai, Corumbá, MS.bitstream/item/161346/1/CT92.pd

Correlations between climate network and relief data

Peer reviewedPublisher PD

Correlations between climate network and relief data

Peer reviewedPublisher PD

Low-dietary fiber intake as a risk factor for recurrent abdominal pain in children

Objective: To evaluate dietary fiber intake in children with recurrent abdominal pain.Design: Cross-sectional study with control group.Setting: Outpatients of the Pediatric Gastroenterology public health clinic of the Darcy Vargas Children's Hospital, Brazil.Subjects: Forty-one patients with recurrent abdominal pain were evaluated and 41 children, as a control group.Interventions: Macronutrients and fiber intake evaluation by the Daily Food Intake method. Two tables of fiber composition in foods were used.Results: According to the Brazilian table the mean intake of fiber ( g/day) by the children of the recurrent abdominal pain groups with chronic constipation or not, and the control group was, respectively, 18.2, 16.6 and 23.7 for total fiber ( P 0.001), 7.5, 6.9 and 9.5 for soluble fiber ( P 0.001) and 10.7, 9.7 and 14.1 for insoluble fiber ( P 0.002). According to the AOAC table, the recurrent abdominal pain group with chronic constipation or not ( 10.6 and 9.9 g/day) also had lower intake of total fiber than the control group ( 13.4 g/day) ( P 0.008). the intake of fiber was lower than the minimum recommended value ( age+5g) and statistically associated ( P 0.021) with the recurrent abdominal pain group ( 78%) in comparison with the control one ( 51.2%). the odds ratio was 3.39 ( 95% CI, 1.18 - 9.95).Conclusion: fiber intake below the minimum recommended value is a risk factor for recurrent abdominal pain in children.Universidade Federal de São Paulo, Dept Pediat, Paulista Sch Med, BR-04023062 São Paulo, BrazilDarcy Vargas Childrens Hosp, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pediat, Paulista Sch Med, BR-04023062 São Paulo, BrazilWeb of Scienc