Universidade Estadual de Londrina

About: Universidade Estadual de Londrina is a education organization based out in Londrina, Brazil. It is known for research contribution in the topics: Population & Toxoplasma gondii. The organization has 13052 authors who have published 19291 publications receiving 212123 citations.

Evidence of neoproterozoic backarc basin development in the central ribeira belt, southeastern brazil: new geochronological and geochemical constraints from the são roque - açungui groups

Abstract: The Ribeira Belt (RB) of southeastern Brazil represents an important manifestation of the Brasiliano Orogeny formed during the assembly of West Gondwana. Contemporaneous sedimentation and volcanism within the RB provide a basis for helping understand its tectonic evolution and paleogeography. U-Pb monazite data from the basal metavolcanic rocks of the Sao Roque Group indicate a crystallization age of 628 Ma and the upper sequence is cut by a 605 Ma (U-Pb zircon) rhyolite intrusion. Zircon and monazite analyses of metavolcanic (mafic) rocks and from metagabbros of the lower Acungui Supergroup yield crystallization ages of 614 and 617 Ma, respectively. This supergroup is intruded by a 607 Ma granite. Geochemical signatures of basal mafic units in both sequences are characteristic of E-MORB subalkaline tholeitic basaltic rocks. Nd isotopic signatures of the metamafic rocks indicate that they were derived in part from the asthenospheric mantle (consistent with emplacement in an extensional setting), whereas the felsic bodies appear to have come from the melting of Paleoproterozoic lithosphere. The paleogeographic reconstruction of part of the RB suggests that the Sao Roque/Acungui groups represent extensional sequences, with features of backarc basins, which evolved during the syn-collisional phase of the Brasiliano Orogeny. These data support the hypothesis that we have a rapid evolution (10-20 Ma) between extensional and compressional tectonics during the geological history of the Sao Roque/Acungui Backarc.

Polyphasic characterization of Brazilian Rhizobium tropici strains effective in fixing N2 with common bean (Phaseolus vulgaris L.)

Abstract: Common bean (Phaseolus vulgaris) is native to the Americas, and Rhizobium etli is the dominant microsymbiont in both the Mesoamerican and the Andean centers of genetic diversification. Wild common beans are not found in Brazil, although the legume has been cropped in the country throughout time and all but one of the rhizobial species that nodulate it (Rhizobium gallicum) have been broadly detected in Brazilian soils. However, the majority of the effective rhizobial strains isolated so far from field-grown plants belong to R. tropici. This study describes the analysis of symbiotic and non-symbiotic genes of 15 effective R. tropici strains, isolated from four geographically distant regions in Brazil. With RFLP-PCR of the 16S and 23S rRNA genes and sequence analysis of 16S rRNA, two clusters were observed, one related to R. tropici type A and another to type B strains. Diversity in ribosomal genes was high, indicating that type A strains might represent a new species. High intraspecies diversity was also observed in the rep-PCR analysis with BOX, ERIC and REP primers. However, in the RFLP-PCR analysis of nifH and nodC genes, all R. tropici showed unique combinations of profiles, which might reflect an evolutionary strategy to maximize N2 fixation.

Impact of the habitual physical activity on lipid profile in adults

Abstract: O objetivo do estudo foi analisar o impacto da pratica habitual de atividade fisica, mediante informacoes reunidas por intermedio do International Physical Activity Questionnaire (IPAQ), no perfil lipidico em amostra representativa de sujeitos adultos. A amostra foi constituida por 361 sujeitos (196 mulheres e 165 homens) com idades entre 20 e 60 anos. As concentracoes de lipideos plasmaticos foram estabelecidas mediante procedimentos laboratoriais. Os achados revelaram que, em ambos os sexos, os niveis plasmaticos de HDL-colesterol e VLDL-colesterol nao apresentaram diferencas significativas entre os grupos de pratica habitual de atividade fisica. Os valores de triglicerideos, colesterol serico total e LDL-colesterol foram significativamente diferentes em mulheres e homens, porem o comportamento de variacao foi diferente nos dois sexos. As informacoes da analise de regressao logistica indicaram que as odds ratios para menores valores de lipideos plasmaticos foram significativas somente nos sujeitos classificados como muito-ativos em comparacao com os sedentarios. Como conclusao, os resultados sugerem que mais elevada pratica habitual de atividade fisica determinada pelo IPAQ apresenta significativo impacto no perfil lipidico em adultos de ambos os sexos, independentemente da idade e das variacoes do peso corporal.

Machine learning hyperparameter selection for Contrast Limited Adaptive Histogram Equalization

Abstract: Contrast enhancement algorithms have been evolved through last decades to meet the requirement of its objectives. Actually, there are two main objectives while enhancing the contrast of an image: (i) improve its appearance for visual interpretation and (ii) facilitate/increase the performance of subsequent tasks (e.g., image analysis, object detection, and image segmentation). Most of the contrast enhancement techniques are based on histogram modifications, which can be performed globally or locally. The Contrast Limited Adaptive Histogram Equalization (CLAHE) is a method which can overcome the limitations of global approaches by performing local contrast enhancement. However, this method relies on two essential hyperparameters: the number of tiles and the clip limit. An improper hyperparameter selection may heavily decrease the image quality toward its degradation. Considering the lack of methods to efficiently determine these hyperparameters, this article presents a learning-based hyperparameter selection method for the CLAHE technique. The proposed supervised method was built and evaluated using contrast distortions from well-known image quality assessment datasets. Also, we introduce a more challenging dataset containing over 6200 images with a large range of contrast and intensity variations. The results show the efficiency of the proposed approach in predicting CLAHE hyperparameters with up to 0.014 RMSE and 0.935 R2 values. Also, our method overcomes both experimented baselines by enhancing image contrast while keeping its natural aspect.