Meta-learning recommendation of default hyper-parameter values for SVMs in classifications tasks

Machine learning algorithms have been investigated in several scenarios, one of them is the data classification. The predictive performance of the models induced by these algorithms is usually strongly affected by the values used for their hyper-parameters. Different approaches to define these values have been proposed, like the use of default values and optimization techniques. Although default values can result in models with good predictive performance, different implementations of the same machine learning algorithms use different default values, leading to models with clearly different predictive performance for the same dataset. Optimization techniques have been used to search for hyper-parameter values able to maximize the predictive performance of induced models for a given dataset, but with the drawback of a high computational cost. A compromise is to use an optimization technique to search for values that are suitable for a wide spectrum of datasets. This paper investigates the use of meta-learning to recommend default values for the induction of Support Vector Machine models for a new classification dataset. We compare the default values suggested by the Weka and LibSVM tools with default values optimized by meta-heuristics on a large range of datasets. This study covers only classification task, but we believe that similar ideas could be used in other related tasks. According to the experimental results, meta-models can accurately predict whether tool suggested or optimized default values should be used.CAPESCNPqSão Paulo Research Foundation (FAPESP) (grant#2012/23114-9

ANOMALIAS GEOQUÍMICAS DE U E DE TH, SOLOS RESIDUAIS E GEOFORMAS EM PAISAGENS TROPICAIS ÚMIDAS SOBRE GRANITO

O comportamento do U e do Th foi analisado durante a evolução pedogeoquímica e morfogenética de paisagens tropicais úmidas, sobre rocha granítica com teores normais desses elementos, visando estabelecer relações entre rocha-mãe e anomalias de U e de Th, tipos de solos residuais e geoformas resultantes dessa evolução. Em uma vertente caracterizada pelo sistema de transformação Latossolo-Solo Podzólico, anomalias de U e de Th de grande expressão geográfica e intensidade ocorrem na paisagem eluvial, parte superior da vertente onde se verificam declividades entre 0 e 8%. Tais radioanomalias são de natureza relativa/residual predominante e com baixa proporção de U adsorvido, e situam-se no topo do horizonte B dos Latossolos. As anomalias radioativas mais intensas, porém de menor expressão geográfica, localizam-se na paisagem transeluvial, parte mediana das vertentes com declividades entre 8 e 45%. São em parte residuais e em parte absolutas, resultantes da podzolização dos Latossolos, e associam-se ao topo do horizonte B textural dos Solos Podzólicos. Radioanomalias de menor intensidade, e essencialmente uraníferas, situam-se na paisagem supraqual, parte inferior e com baixas declividades da vertente. São de caráter absoluto, com o U fixado principalmente por adsorção às fases argilo-orgânica e óxido dos horizontes A0 e A1 dos Solos Hidromórficos. Nessa paisagem, em áreas de influência da atual rede de drenagem, pode existir desequilíbrio radioativo entre os radionuclídeos da série do 238 U, com reflexos negativos nas intensidades das radiações gama emitidas. Isto se deve à pouca idade de deposição do U nesses locais durante a podzolização, entre 100.000 e 500.000 anos. Então, no contexto enfocado, a transformação de rochas com teores normais em U e em Th pode resultar em materiais secundários, com concentrações nesses radionuclídeos mais elevadas que as existentes nas rochas inalteradas. A atuação dos processos geoquímicos responsáveis pela redistribuição do U e do Th ocorreu concorrentemente com a dos processos pedogenéticos, morfogenéticos e hidrogeológicos, durante a evolução das paisagens. Os principais tipos de anomalias de U e de Th, paisagens geoquímicas elementares, tipos e horizontes de solos residuais e geoformas estão cronológica e espacialmente relacionados. GEOCHEMICAL ANOMALIES OF U AND TH, RESIDUAL SOILS AND GEOFORMS IN HUMID TROPICAL LANDSCAPES OVER GRANITE Extended Abstract The geochemical behavior of U and Th during the evolution of humid tropical landscapes was analysed, with the objective to establishing relationships between parent rock, and the resulting U and Th anomalies, types of residual soils and geoforms. In one slope over granite with normal contents of U and Th, and characterized by the soil association Latosol-Podzolic, the pedologic horizons providers and receivers of these radionuclides during the processes of latolization and podzolization were evaluated. Studies were carried out on the main characteristics of the radioanomalies that took place in each landscape, mainly the concentration levels and the secondary hosting phases of U and Th, and their impact on the ratio Th/U and Us/Ut (soluble uranium/total uranium), and on their relative gammaradiometric intensities. Multi and interdisciplinary studies were done, making use of the various data and concepts from worldwide scientific literature, specifically in the fields of geochemistry and pedology. In the first case, emphasis was placed on the characteristics of the primary concentrations of U and Th (table 1), and on the geochemical concepts of element abundance, gradients, migration, flows and geochemical barriers, and of elementary landscape geochemistry (figure 1). In the field of pedology, the concept of transformational pedologic system and the cronology of the main pedogenetic phases were addressed. Moreover, concepts and elements of the areas of geomorphology, hydrogeology of the phreatic aquifer system and the nuclear physics of the series of 238 U and 232 Th were used and approached from a tridimensional and systemic perspective. The analyses were carried out in short space-temporal limits, according to the dimensions of the slopes and, regarding time specifics, the pedologic scale was found to be the most relevant. In the context studied, the Latosols occur in the eluvial landscape, associated to older, more stable and higher surfaces of the slope, where declivities between 0 and 8% can be observed. In this landscape, the geochemical environment is oxidizing and the pH is acid. The main concentrations of U and Th are due to resistant minerals containing U and Th, insoluble compounds of Th, and U and Th fixed to Fe and Al oxyhydroxides and clays by adsorption. These anomalies are characterized by low Us/Ut and high Th/U ratios, and intense gamma countings (table 2 and 3). They are relative and residual in nature, and are located on the top of latosolic B horizon (figure 2). The Podzolic Soils are of lesser geographic occurrence than the Latosols. Found in the transeluvial landscape, they are related to younger surfaces in intermediate altitudes of the slope, where the declivities are between 8 and 45 %. In this landscape, a strong control of the local parameters of the environment over the configuration and spacial distribution of the soil profiles and their physical properties has been observed. The geochemical environment is oxidizing and the pH is acid on the superficial horizons, changing to reducing toward the B textural horizon (Bt), where the pH levels are higher. The main concentrations of U and Th, being the result of the reworking of those associated with the Latosols, by podzolization, and located on the top of horizon Bt (figure 2 and table 4), present higher levels and higher proportions of soluble U in relation to the total contents. These anomalies show higher Us/Ut and lower Th/U ratios compared to the same ratios in the Latosols and more intense gamma manifestations (table 2). They are partially relative and partially absolute, depending on the migration of radionuclides, inclusively in colloidal solution, due to the eluviation-illuviation processes which take place during podzolization. The Hydromorphic Soils predominate in superaqual landscape, where the aeration zone of the aquifer is either thinner or inexistent, and the water-table outcrops or is present at a shallow depth. The geochemical environment works as a reducing agent due to the frequent saturation of the soils and the presence of organic matter (OM), and the pH , in general, ranges from neutral to alkaline. Besides OM, clay phases and Fe compounds with a high cationic exchange capacity are frequently encountered, making up favorable factors for the fixation by adsorption of U originated from eluvial and transeluvial landscapes during latolization and podzolization. The main concentrations are uraniferous and absolute, associated to horizons A0 and A1 of the soils (figure 2), resulting in high ratios Us/Ut, and decreases in Th/U. The gamma radiation emissions are moderate in intensity (table 2). In this landscape, radioactive disequilibrium in the decay series of 238 U, with a negative impact for the gamma radiation intensity, may occur in places near the drainage system. This happens due to the young age of 238 U deposition in these areas, mainly during the podzolization of the Latosols, between 100,000 and 500,000 years, insufficient time for the re-establishment of the secular radioactive equilibrium in the referred series. Hence, the transformation by the action of supergenic processes, mainly the pedogeochemical ones, of rocks with normal contents of U and Th, may result in materials with different distributions and concentrations of these radionuclides, considerably higher than the ones in unaffected rocks (table 3). Even the intensively leached soils, such as the ones of the association Latosol-Podzolic, present a relative increase in the U and Th values, due to the concentration of resistant minerals and their association with oxide, clay and carbon phases of the soils. U and Th distribution and levels of concentration reveal the nature of fixation of these radionuclides in their original hosting phases and their real mobilities in the different geochemical landscapes along the slope. In conclusion, in the present study, the landscapes which show the highest probability of containing high anomalies of U and Th are the transeluvial landscape, on the top of the textural B horizon of the Podzolic Soils, and the eluvial, on the top of the latosolic B horizon of the Latosols. In the superaqual landscape, the anomalies are uraniferous and associated with horizons A0 and A1 of the Hydromorphic Soils (figure 2 and table 2). Consequently, in the referred climatic environment, the action of the geochemical processes which lead to the re-distribution of U and Th, took place concomitantly with the pedogenetic, morphogenetic and hydrogeological ones, throughout the evolution of the landscapes. The main types of U and Th anomalies, types and horizons of the residual soils, elementary geochemical landscapes and geoforms are cronologically and spatially related

MODELOS DE EXALAÇÃO DE RADÔNIO EM PAISAGENS TROPICAIS ÚMIDAS SOBRE GRANITO

Foram estabelecidas e analisadas as principais relações entre intensidades de exalação de radônio ( 222Rn e 220Rn) e os elementos morfológicos e dinâmicos de paisagens tropicais úmidas, com o objetivo de elaborar modelos de exalação de Rn adaptados a este tipo de paisagens, e aplicáveis na escala de pequenos núcleos habitacionais. Em uma vertente sobre rocha granítica com teores normais em U e Th, e caracterizada pela associação Latossolo-Solo Podzólico, os produtos de atuação dos processos supergênicos, com destaque para a transição de latolização em podzolização, e o atual regime hídrico do aqüífero freático, foram relacionados aos processos radioativos de geração, emanação e migração de Rn, verificando-se como tais inter-relações afetam a sua exalação nas paisagens. Tal abordagem foi fundamentada nos conceitos de sistema pedológico de transformação e de geoquímica de paisagens, além de conceitos da física e geologia nucleares e elementos climatológicos e hidrogeológicos do macroambiente, num enfoque interdisciplinar, tridimensional e sistêmico. Às vertentes configuradas em paisagens elementares; eluvial, transeluvial e supraqual associam-se diferentes geoformas, tipos e espessuras de solos residuais e radioanomalias com diferentes intensidades e formas de hospedagem de U e de Th. Com base em tais elementos, suas relações espaciais com o sistema freático, e considerando a umidade dos solos na capacidade de campo, as possibilidades de maiores taxas de exalação de Rn, sobretudo 222Rn, são nas paisagens supraqual e transeluvial. Na paisagem eluvial, a despeito da existência de intensas anomalias gama, devido principalmente ao acúmulo de minerais resistatos com U e Th e compostos de Th, os fluxos de Rn são menos significativos. Assim, no contexto enfocado, os produtos da alteração supergênica, organizados num sistema vertente, são materiais em que as taxas de exalação de radônio são mais elevadas do que as medidas na rocha inalterada subjacente. O entendimento do comportamento do U, Th, Ra e Rn no ambiente superficial tornou possível estabelecer modelos previsionais de exalação de Rn adaptados às paisagens elementares, em escalas compatíveis com pequenos núcleos habitacionais ou em unidades residenciais. RADON EXHALATION MODELS IN HUMID TROPICAL LANDSCAPES OVER GRANITE Extended Abstract The main relationships between radon ( 222 Rn and 220 Rn) exhalation intensities and the morpho-dynamic elements of humid tropical landscapes have been established and analyzed, aiming at elaborating Rn exhalation models adapted to this type of landscapes, to be used in the scale of small habitational nuclei. The present research revolved around the understanding of two distinct phases, each one presenting their own processes and time durations. The first one covers the modelling and internal constitution of a drainage basin slopes, during the geologic and pedologic times. The second one refers to the slope morphological system, structure of which is the result of previous processes, allowing for the current radioactive processes of Rn generation, emanation (figure 1), migration and exhalation, some of which affected by rain, temperature, pressure and winds. Such elements have proven to be relevant in the water regimen of the phreatic aquifer. Multi and interdisciplinary studies about the different areas approached were done, making use of several data, information and concepts from worldwide scientific literature. The focus of the study has been a slope over granite containing normal levels of U and Th, and characterized by the soil association Latosol-Podzolic (figure 2). The analyses were carried out in short spatial-temporal limits, according to the dimensions of the slopes, and, regarding time specifics, the pedologic scale was found to be the most relevant. Several aspects have been evaluated, namely the role of the supergenic processes on the evolution of the landscapes, the impact of this evolution on the efficiency of the radioactive processes mentioned, on the different soils and under different aquifer hydric regimens in these landscapes. In the studied soil, emphasis was placed on the concept of the transformation pedologic system and on the relative cronology of the main pedogenetic phases involved, namely latolization and podzolization. In the dispersion of radionuclides, fundamental concepts of surface geochemistry have been used, main emphasis on the ones of elementary landscape geochemistry (figure 2), and of element abundance, migration, flows, and geochemical barriers, backed up by the use of Th/U and Us/Ut (exchageable U/total U) ratios. Moreover, several concepts of nuclear physics, main focus on the 238 U and 232 Th decay series, and hydrogeologic and climatological elements of the environment have been addressed. In regard to the spatial-temporal dimensions stressed in this study, the chronology of the main pedogeochemical processes responsible for the re-distribution of U and Th, and the nature of their secondary hosting phases, it was assumed that the radionuclides of the series mentioned are in secular radioactive equilibrium. Such an approach allowed for the use of U and Th as indicators of the distribution of Ra, Rn precursor, which, in this study, is symbolized by the notation U and Th (Ra). In the models presented, the supergenic processes configurate the slopes in the eluvial, transeluvial, superaqual and aqual landscapes, this last one not considered in this study. Each of these landscapes is characterized by different geoforms, types and thickness of the residual soils and their permea-porosities, and associated to different radionuclides U and Th (Ra) concentrations and their respective hosting phases, as well as different water regimens of the phreatic aquifer (figure 2). The eluvial landscape is the place where Latosols mostly occur. In this case, the main U and Th (Ra) anomalies are located on the top of latosolic B horizon, and they are due to the relative accumulation of resistate minerals, insoluble Th compounds, and U and Th fixed to Fe and Al oxihydroxides and clays by adsorption. In this landscape, the aeration zone of the aquifer presents its maximum thickness, and the groundwater flows are vertical downward. In the transeluvial landscape, the dominant soils are the Podzolic, originated from the podzolization of the pre-existant Latosols. Moreover, the Latosol-Podzolic transformation system comprises a second generation of radioanomalies, more intense and with higher proportions of adsorbed U, and resultant from the reworking of the anomalies associated with the Latosols. Such a transforming phase is also responsible for the change in the existant versant slope angle and “permea-porosities”, forming a perched sub-system phreatic aquifer in this landscape (figure 2). The main concentrations of U and Th (Ra) are partly relative and partly absolute, and are located on the top of textural B horizon of the Podzoloic Soils, in hosting phases similar to the ones from the previous landscape, and containing organic matter as well. The groundwater flows are essentially lateral, the most superficial ones canalized through the A and E pedologic horizons of the perched sub-system aquifer. In the superaqual landscape, the radioanomalies are primarily uraniferous and absolute in nature, with U adsorbed to clays, organic matter and oxides of A0 and A1 horizons of the Hydromorphic Soils (figure 2), the migration of uraniferous solutions occurring in two principal phases. The first one, longer and older than 1 My, took place during latolization. The second phase, younger and affecting more limited geographic areas, occurred during the Latosols podzolization, between 100,000 and 500,000 years, having part of the solutions drained into the current drainage system. In this landscape, the groundwater flows are predominantly lateral during the rainy seasons, and vertical upward during dry seasons. Hence, the supergenic alteration products, organized on a slope system, are materials in which the rates of radon exhalation are higher than the ones measured on unaffected subjacent rock. Based on the secondary concentrations and hosting phases of U and Th (Ra), on the “permea-porosities” of the soils and their spatial relationships with the phreatic system, and considering the soil moisture content near the field capacity, the higher rates of Rn exhalation, mainly 222 Rn, are likely to happen in Hydromorphic Soils in the superaqual landscape and in Podzolic Soils in transeluvial landscape (table 1 and 2 and figure 2). This Rn exhalation rates are conditioned by a positive combination between Rn generation and emanation. Exceptions occur in areas under the influence of the current drainage system of the superaqual landscape, where 238 U younger than 1 My is in radioactive disequilibrium with their daughters, which causes a negative impact on Rn generation. In the eluvial landscape, despite the existance of high content of U and Th (Ra) associated with the Latosols, due to the accumulation of resistates with U and Th, Th compounds, and U and Th adsorbed in oxihydroxides and clays, the Rn fluxes are less important, and are controlled by the low emanation of most of the hosting phases mentioned (table 1). It is important to note that other soil moisture contents may affect the intensities of Rn fluxes significantly (table 2). At last the approach which has been used has led to an evaluation of Rn exhalation conditioning factors while referring to humid tropical landscapes. All kinds of parameters, climatic, geochemical, weathering, pedogenetic, morphogenetic and hydrogeologic parameters could be integrated into the scale of elementary landscape slope, and they all can be integrated among themselves and also to the radioactive processes of Rn generation, emanation, migration and exhalation, by means of an interdisciplinary, tridimensional and systemic viewpoint. U, Th, Ra and Rn behaviors have been fully investigated, making it possible to establish previsional models of Rn exhalation in scales compatible to dimensions of small habitational nuclei or even unitary dwellings

In vitro schistosomicidal effects of the essential oil of Tagetes erecta

The in vitro schistosomicidal effects of the essential oil obtained from Tagetes erecta L. Asteraceae, leaves (TE-EO) collected in Brazil against Schistosoma mansoni worms are reported in this paper. The oil caused a significant decrease in the motor activity at 50 µg/mL as minimal concentration after 24 h. This oil also caused death of all the parasites and the separation of coupled pairs into individual male and female at 100 µg/mL after 24 h. The viability of adult worm groups treated with the TE-EO at 100 µg/mL was similar to that of groups treated with praziquantel (positive control). In addition, the oil promoted the inhibition of eggs development at all the tested concentrations. These data indicate that the TE-EO could be considered as a promising source for the development of new schistosomicidal agents

A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000

Deficient CD40-TRAF6 signaling in leukocytes prevents atherosclerosis by skewing the immune response toward an antiinflammatory profile

The CD40–CD40 ligand (CD40L) signaling axis plays an important role in immunological pathways. Consequently, this dyad is involved in chronic inflammatory diseases, including atherosclerosis. Inhibition of CD40L in apolipoprotein E (Apoe)–deficient (Apoe−/−) mice not only reduced atherosclerosis but also conferred a clinically favorable plaque phenotype that was low in inflammation and high in fibrosis. Blockade of CD40L may not be therapeutically feasible, as long-term inhibition will compromise systemic immune responses. Conceivably, more targeted intervention strategies in CD40 signaling will have less deleterious side effects. We report that deficiency in hematopoietic CD40 reduces atherosclerosis and induces features of plaque stability. To elucidate the role of CD40–tumor necrosis factor receptor-associated factor (TRAF) signaling in atherosclerosis, we examined disease progression in mice deficient in CD40 and its associated signaling intermediates. Absence of CD40-TRAF6 but not CD40-TRAF2/3/5 signaling abolishes atherosclerosis and confers plaque fibrosis in Apoe−/− mice. Mice with defective CD40-TRAF6 signaling display a reduced blood count of Ly6Chigh monocytes, an impaired recruitment of Ly6C+ monocytes to the arterial wall, and polarization of macrophages toward an antiinflammatory regulatory M2 signature. These data unveil a role for CD40–TRAF6, but not CD40–TRAF2/3/5, interactions in atherosclerosis and establish that targeting specific components of the CD40–CD40L pathway harbors the potential to achieve therapeutic effects in atherosclerosis