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

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

A análise econômico-ecológica de um agroecossistema no município de Paraty-RJ como ferramenta de planejamento e apoio à transição agroecológica.

A Metodologia de Análise Econômico-Ecológica de Agroecossistemas considera estratégias singulares nas dinâmicas socioecológicas de gestão na agricultura familiar invisibilizadas nos métodos convencionais de agricultura. A metodologia foi aplicada em um sistema agroecológico na região costa verde, estado do Rio de Janeiro, com objetivo realizar uma análise para viabilizar e fortalecer a produção na perspectiva da agroecologia. As etapas do método são: visita ao agroecossistema, entrevista semiestruturada, elaboração da linha do tempo e da modelização e análise econômica-ecológica. A família aposta na diversificação da produção como estratégia de comercialização. Identificou-se que maior parte dos insumos foi produzida internamente diminuindo custo e aumentando rentabilidade. Pode-se inferir que a estratégia de produção e de organização social adotada pela família permitiu a interação da produção econômica e reprodução ecológica do agroecossistema viabilizando a permanência da família na propriedade.Edição dos Anais do VI Congresso Latino-americano de Agroecologia; X Congresso Brasileiro de Agroecologia; V Seminário de Agroecologia do Distrito Federal e Entorno, Brasília, DF, set. 2017

Correlations between climate network and relief data

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Correlations between climate network and relief data

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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

Measuring the evolution of contemporary western popular music

Popular music is a key cultural expression that has captured listeners' attention for ages. Many of the structural regularities underlying musical discourse are yet to be discovered and, accordingly, their historical evolution remains formally unknown. Here we unveil a number of patterns and metrics characterizing the generic usage of primary musical facets such as pitch, timbre, and loudness in contemporary western popular music. Many of these patterns and metrics have been consistently stable for a period of more than fifty years, thus pointing towards a great degree of conventionalism. Nonetheless, we prove important changes or trends related to the restriction of pitch transitions, the homogenization of the timbral palette, and the growing loudness levels. This suggests that our perception of the new would be rooted on these changing characteristics. Hence, an old tune could perfectly sound novel and fashionable, provided that it consisted of common harmonic progressions, changed the instrumentation, and increased the average loudness.Comment: Supplementary materials not included. Please see the journal reference or contact the author

On the concepts of complex networks to quantify the difficulty in finding the way out of labyrinths

Labyrinths have been a tradition and part of the imagination of the human kind for centuries, and were probably built either as a challenge to make it difficult for someone to find the way out, or for aesthetic purposes. They are conventionally classified according to the country they were built, to the style (Roman, classic and contemporary) or to the construction site. In this study, we show that labyrinths can be modeled as complex networks, whose metrics can be used to classify them in terms of their difficulty to find the way out. This is performed by calculating the absorption time, defined as the time it takes for a particle on an internal node to reach an output node through a random walk. The absorption time correlates well with the shortest paths and length of the networks, as expected, and has a very high correlation (Pearson coefficient of 0.97) with the betweenness, therefore allowing one to quantify the level of complexity of any labyrinth. It is shown that the conventional classification is inappropriate to distinguish between labyrinths, because some with very similar properties exist in different countries or were built in distinct time periods. A refined analysis in 77 famous labyrinths indicated that the majority were built for aesthetic purposes, with relatively small absorption times. Furthermore, with the expectation maximization algorithm, we could combine the complex network metrics to identify four clusters of labyrinths that differ in terms of density and shape.FAPESP (10/00927-9, 05/00587-5)CNPq (301303/06-1

Predicting language diversity with complex network

Evolution and propagation of the world's languages is a complex phenomenon, driven, to a large extent, by social interactions. Multilingual society can be seen as a system of interacting agents, where the interaction leads to a modification of the language spoken by the individuals. Two people can reach the state of full linguistic compatibility due to the positive interactions, like transfer of loanwords. But, on the other hand, if they speak entirely different languages, they will separate from each other. These simple observations make the network science the most suitable framework to describe and analyze dynamics of language change. Although many mechanisms have been explained, we lack a qualitative description of the scaling behavior for different sizes of a population. Here we address the issue of the language diversity in societies of different sizes, and we show that local interactions are crucial to capture characteristics of the empirical data. We propose a model of social interactions, extending the idea from, that explains the growth of the language diversity with the size of a population of country or society. We argue that high clustering and network disintegration are the most important characteristics of models properly describing empirical data. Furthermore, we cancel the contradiction between previous models and the Solomon Islands case. Our results demonstrate the importance of the topology of the network, and the rewiring mechanism in the process of language change

Evaluación de la calidad y el impacto del ambiente acuático del río higueras en la provincia de Huánuco – 2014

Natural surface water is one of the most widespread, abundant substances on Earth. It is an integralpart of most living things and is present in allowable amount. The naturally pure drinking water isessential for life; the great civilizations have flourished near adequate supplies of the liquid of life.Riparian vegetation plays Higueras river habitat and ecosystem functions. Influences on hydrology,soil science, physicochemical, chemical and microbiological water, so it is relevant in productivity andperformance, regulates temperature, filtering, retaining nutrients and providing habitat for aquatic communities. The study made some approaches on quality and perceived negative impact on waterquality conditions by measuring various physical, chemical and microbiological parameters. Gradientas described sampling stations throughout the course of the channels. The results indicate highpollution and high negative impacts, with the highest incidence in sites close proximity to coastalsettlements channels. The variables which show excessively high values such sites are the accountof bacteria, coliforms and detergent concentrations, physico-chemical parameters. The temporarynature of the water increases the severity of concentration of some contaminants. It is also remarkablethe impact of the deterioration of the natural quality of the physical environment all the way fromsurface waters of the river, mainly due to agricultural activities, extraction of construction materialsand domestic wastewater discharges affecting the biota aquatic. The results indicate that since thewater stations up even still have low impact on quality, while at stations downstream (Season 4, 5, 6,7, 8, 9, 10) are at high risk for contamination, which is confirms strong electric conductivity, turbidity,eutrophication and disappearance of aquatic life becoming to be a dead river, organoleptic, physicalchemical parameters, microbiological very high concentrations and the presence of ammonia andmineral salts that characterize hard water inadmissible for loved alive and human consumption.Las aguas superficiales naturales es una de las sustancias más difundidas, abundantes en PlanetaTierra. Es parte integrante de la mayoría de los seres vivientes y está presente en cantidadpermisibles. El agua natural pura y potable es fundamental para la vida; las grandes civilizaciones hanflorecido cerca de abastecimientos adecuados de ese líquido de la vida. La vegetación ribereña delrío Higueras desempeña funciones de hábitat y ecosistemas. Influye sobre la hidrología, edafología,físico- químico, químico y microbiológico de las aguas, por lo que es relevante en productividad yfuncionamiento, regula la temperatura, filtrando, reteniendo nutrientes y otorgando hábitat a lascomunidades acuáticas. El estudio realizó unas aproximaciones sobre la calidad y su impacto negativopercibidas sobre condiciones de calidad del agua mediante la determinación de varios parámetrosfísico-químicos y microbiológicos. El gradiente de muestreos en estaciones ya descritos por todo elcurso de los cauces. Los resultados indican grado alto de contaminación e impactos negativos altos,con mayor incidencia en los sitios de asentamientos humanos muy próximos a los cauces ribereños.Las variables analizadas las que muestran valores excesivamente elevadas en dichos sitios, son lacuenta de bacterias, coliformes y las concentraciones de detergentes, parámetros físico- químicos. Elcarácter temporal de las aguas incrementa la gravedad de concentración de algunos contaminantes.Asimismo, es notable el impacto del deterioro de la calidad natural del medio físico en todo eltrayecto de las aguas superficiales del río debido, principalmente, a las actividades agropecuarias,extracción de materiales de construcción y vertidos de aguas servidas domesticas que afectan a labiota acuática. Los resultados indican que desde las estaciones aguas arriba aun todavía presentanbajo impacto en calidad, mientras en las estaciones aguas abajo (estación 4, 5, 6, 7, 8, 9, 10) sonde alto riesgo por la contaminación, lo cual se ratifica con fuerte conductividad eléctrica, turbidez,eutrofización y desaparición de seres vivos acuáticos tornándose a ser un río muerto, parámetrosorganolépticos, físico-químicos, microbiológicos muy altos y la presencia de concentraciones deamoníaco y sales minerales que caracterizan agua dura inadmisibles para los seres vivos y consumohumano