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In this paper, we present an algorithm for clustering multidimensional data, which we named TreeKDE. It is based on a tree structure decision associated with the optimization of the one-dimensional kernel density estimator function constructed from the orthogonal projections of the data on the coordinate axes. Among the main features of the proposed algorithm, we highlight the automatic determination of the number of clusters and their insertion in a rectangular region. Comparative numerical experiments are presented to illustrate the performance of the proposed algorithm and the results indicate that the TreeKDE is efficient and competitive when compared to other algorithms from the literature. Features such as simplicity and efficiency make the proposed algorithm an attractive and promising research field, which can be used as a basis for its improvement, and also for the development of new clustering algorithms based on the association between decision tree and kernel density estimator.

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This paper presents an innovative method of constructing energy absorbers, whose primary function is to effectively transform kinetic energy into strain energy in events with high deformation rates. Hybrid specimens are proposed considering thin-walled windowed metallic tubes filled with 3D-printed hexagonal honeycombs made of PET-G and ABS thermoplastic. The patterned windows dimensions vary from 20 × 20, 20 × 30, 15 × 20 and 15 × 30 mm2. Although using polymers in engineering and thin-walled sections is not new, their combination has not been explored in this type of structure designed to withstand impacts. Specimens resist out-of-plane quasi-static axial loading, and test results are analyzed, demonstrating that polymer core gives the samples better performance parameters than unfilled samples regarding energy absorption (Ea), load rate (LR), and structural effectiveness (η). An optimization procedure using specialized software was applied to evaluate experimental results, which led to identifying the optimal window geometry (16.4 × 20 mm2, in case) and polymer to be used (ABS). The optimized sample was constructed and tested for axial compression to validate the optimization outcomes. The results reveal that the optimal sample performed similarly to the estimated parameters, making this geometry the best choice under the test conditions.

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Polycyclic aromatic sulfur heterocycles (PASHs), such as benzothiophenes (BT), dibenzothiophenes (DBT) and benzonapthothiophenes (BNT), can be emitted from vehicular traffic and deposited in fine particles matter (PM2.5). The presence of these compounds in PM2.5 is an environmental concern due to air pollution and its toxic properties. In this study, a green microscale solid-liquid extraction method was developed to determine twenty-three PASHs in PM2.5. A simplex-centroid mixture design was applied to optimize the extraction solvent. A full factorial design was used for preliminary evaluation of the factors that influence the extraction process (extraction time, sample size, and solvent volume) and then a Doehlert design for the significant parameters. The optimal extraction conditions based on the experimental design were: sample size, 4.15 cm2; 450 µL of toluene:dichloromethane (80:20,v/v); and extraction duration, 24 min. High sensitivity (LOD < 0.66pg m-3 and LOQ < 2.21 pg m-3) and acceptable recovery (82.8-120 %), and precision (RSD 3.6-14.0 %) were obtained. The greenness of the method was demonstrated using the Analytical GREEnness (AGREE) tool. The method was applied for analyzing PASHs in PM2.5 samples collected in three time intervals per day from years with different sulfur contents in the diesel: S-500 (≤500 ppm sulfur) and S-50 (≤50 ppm sulfur). Fourteen PASHs were quantified with the highest concentrations observed for 2,8-DMDBT and 4,6-DMDBT, which are recalcitrant compounds. The ANOVA test indicated significant differences between sampling periods during the day. The reduction of diesel S-500 to S-50 corresponded to a 28 % decrease in the total sum of PASHs (∑PASHs) evaluated. Spearman's rank correlations allowed for verifying that BTs and DBTs were highly correlated, suggesting that they were derived from similar sources. A weak correlation of 2,1-BNT and 2,3-BNT with BTs and DBTs indicates that these compounds are a chemical proxy for the emission of diesel engines during the combustion process.

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In this paper, we propose the MulticlusterKDE algorithm applied to classify elements of a database into categories based on their similarity. MulticlusterKDE is centered on the multiple optimization of the kernel density estimator function with multivariate Gaussian kernel. One of the main features of the proposed algorithm is that the number of clusters is an optional input parameter. Furthermore, it is very simple, easy to implement, well defined and stops at a finite number of steps and it always converges regardless of the data set. We illustrate our findings by implementing the algorithm in R software. The results indicate that the MulticlusterKDE algorithm is competitive when compared to K-means, K-medoids, CLARA, DBSCAN and PdfCluster algorithms. Features such as simplicity and efficiency make the proposed algorithm an attractive and promising research field that can be used as basis for its improvement and also for the development of new density-based clustering algorithms.

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The objective of this work was to describe morphology and grouping of Paspalum notatum accessions, based on multicategorical data which discards the redundant variables for quantification of genetic diversity. We also tested the hypothesis that geographical distance was correlated with morphological divergence. In our study, multivariate analyzes successfully demonstrated the geographic and morphological variability of the P. notatum accessions characterized. Many of these evaluated accessions can be included in future genetic improvement programs. Based on two methodologies for discarding variables, it was possible to identify the potentially important morphological characteristics from genetic diversity studies and characterize new accessions aimed at improving forage and seed production. The methodologies used to discard variables are biometric tools that can be used successfully in future plant breeding programs, especially when a large number of traits and accessions are being evaluated. Although significant, geographic distance had a low association with morphological traits. This indicated the need to use other characteristics, such as forage and seed yield, in addition to molecular analysis. Our analyzes showed genetic variability in P. notatum for all the characteristics studied.(AU)

Assuntos

RESUMO

Introduction: One of the fundamental structural elements of the cell is the cytoskeleton. Along with myosin, actin microfilaments are responsible for cellular contractions, and their organization may be related to pathological changes in myocardial tissue. Due to the complexity of factors involved, numerical modeling of the cytoskeleton has the potential to contribute to a better understanding of mechanical cues in cellular activities. In this work, a systematic method was developed for the reconstruction of an actomyosin topology based on the displacement exerted by the cell on a flexible substrate. It is an inverse problem which could be considered a phenomenological approach to traction force microscopy (TFM). Methods An actomyosin distribution was found with a topology optimization method (TOM), varying the material density and angle of contraction of each element of the actomyosin domain. The routine was implemented with a linear material model for the bidimensional actomyosin elements and tridimensional substrate. The topology generated minimizes the nodal displacement squared differences between the generated topology and experimental displacement fields obtained by TFM. The structure resulting from TOM was compared to the actin structures observed experimentally with a GFP-attached actin marker. Results The optimized topology reproduced the main features of the experimental actin and its squared displacement differences were 11.24 µm2, 27.5% of the sum of experimental squared nodal displacements (40.87 µm2). Conclusion This approach extends the literature with a model for the actomyosin structure capable of distributing anisotropic material freely, allowing heterogeneous contraction over the cell extension.

RESUMO

Cluster analysis was used to investigate the genetic divergence among five lines of laying hens. The following traits were evaluated: body weight at 40, 48 and 56 weeks of age; egg weight at 40, 44, 52 and 60 weeks of age; and laying rate from 40 to 60 weeks of age. Three groups were formed when data were analyzed by the single-linkage hierarchical method using squared Mahalanobis distance (D²) as dissimilarity measures: one group comprised lines 3 and 5, the second group line 1, and the third group comprised lines 2 and 4. Using Tocher's optimization method, only two groups were formed: one group comprised lines 3, 5 and 1, and the second comprised lines 2 and 4. This evidences the disagreement between the methods over the evaluation of genetic divergence. The trait that contributed mostly to the genetic divergence was body weight at 48 weeks of age.

RESUMO

Cluster analysis was used to investigate the genetic divergence among five lines of laying hens. The following traits were evaluated: body weight at 40, 48 and 56 weeks of age; egg weight at 40, 44, 52 and 60 weeks of age; and laying rate from 40 to 60 weeks of age. Three groups were formed when data were analyzed by the single-linkage hierarchical method using squared Mahalanobis distance (D²) as dissimilarity measures: one group comprised lines 3 and 5, the second group line 1, and the third group comprised lines 2 and 4. Using Tocher's optimization method, only two groups were formed: one group comprised lines 3, 5 and 1, and the second comprised lines 2 and 4. This evidences the disagreement between the methods over the evaluation of genetic divergence. The trait that contributed mostly to the genetic divergence was body weight at 48 weeks of age.

RESUMO

Elephantgrass (Pennisetum purpureum Schum.) is native to regions of tropical Africa and was introduced in Brazil around 1920 through plantings imported from Cuba. It is currently one of the most widespread forage plants throughout the country. At first, there were two cultivars, Napier and Mercker, with well defined characteristics. New genotypes arose and it is believed that the large number of cultivars existing today in germplasm bank is due to duplicates. DNA markers for cultivar characterization are a very valuable tool, especially in situations where morphological and isoenzymatic markers have already been used as in the case of elephantgrass. Thus RAPD markers were used to estimate the genetic divergence among the Napier group elephantgrass cultivars from the elephantgrass Active Germplasm Bank at EMBRAPA Dairy Cattle. The polymerase chain reaction with 37 arbitrary primers from the OPERON Technologies series supplied 94 polymorphic and 73 monomorphic bands. From the matrix of complement of the Nei index, cluster analysis by the Tocher optimization method formed three clusters. Pearson correlation among genetic distance estimates obtained from the DNA markers and the isoenzymatic markers showed the consistency of both the methods in assessing genetic divergence among elephantgrass cultivars. No duplicates were found in the treatments assessed.

O capim-elefante (Pennisetum purpureum Schum.) é nativo de regiões da África Tropical e foi introduzido no Brasil por volta de 1920, por meio de mudas provenientes de Cuba, e é, atualmente, uma das forrageiras mais difundidas em todo o país. No início de sua utilização, existiam praticamente dois cultivares com características bem definidas, Napier e Mercker. Com o decorrer do tempo, surgiram novos genótipos e acredita-se que o grande número de cultivares existentes atualmente no Banco de Germoplasma da espécie se deva à ocorrência de duplicatas. O uso de marcadores de DNA na caracterização de cultivares constitui uma ferramenta de grande valor, principalmente em situações em que marcadores morfológicos e isoenzimáticos já foram empregados, caso do capim-elefante. Em vista disso, objetivou-se estimar a divergência genética entre cultivares de capim-elefante do grupo "Napier" provenientes do Banco Ativo de Germoplasma de capim-elefante da EMBRAPA Gado de Leite, por meio de marcadores RAPD. As reações de polimerase em cadeia com 37 iniciadores arbitrários da série OPERON Technologies proporcionaram 94 bandas polimórficas e 73 monomórficas. Por meio da matriz do complemento do índice de Nei, a análise de agrupamento pelo método de otimização de Tocher indicou a formação de três grupos. Correlação de Pearson entre estimativas de distância genética obtidas a partir dos marcadores de DNA e dos marcadores isoenzimáticos indicaram a consistência de ambos os métodos para a avaliação da divergência genética entre cultivares de capim-elefante. Não foram encontradas duplicatas nos tratamentos avaliados.

RESUMO

Elephantgrass (Pennisetum purpureum Schum.) is native to regions of tropical Africa and was introduced in Brazil around 1920 through plantings imported from Cuba. It is currently one of the most widespread forage plants throughout the country. At first, there were two cultivars, Napier and Mercker, with well defined characteristics. New genotypes arose and it is believed that the large number of cultivars existing today in germplasm bank is due to duplicates. DNA markers for cultivar characterization are a very valuable tool, especially in situations where morphological and isoenzymatic markers have already been used as in the case of elephantgrass. Thus RAPD markers were used to estimate the genetic divergence among the Napier group elephantgrass cultivars from the elephantgrass Active Germplasm Bank at EMBRAPA Dairy Cattle. The polymerase chain reaction with 37 arbitrary primers from the OPERON Technologies series supplied 94 polymorphic and 73 monomorphic bands. From the matrix of complement of the Nei index, cluster analysis by the Tocher optimization method formed three clusters. Pearson correlation among genetic distance estimates obtained from the DNA markers and the isoenzymatic markers showed the consistency of both the methods in assessing genetic divergence among elephantgrass cultivars. No duplicates were found in the treatments assessed.

O capim-elefante (Pennisetum purpureum Schum.) é nativo de regiões da África Tropical e foi introduzido no Brasil por volta de 1920, por meio de mudas provenientes de Cuba, e é, atualmente, uma das forrageiras mais difundidas em todo o país. No início de sua utilização, existiam praticamente dois cultivares com características bem definidas, Napier e Mercker. Com o decorrer do tempo, surgiram novos genótipos e acredita-se que o grande número de cultivares existentes atualmente no Banco de Germoplasma da espécie se deva à ocorrência de duplicatas. O uso de marcadores de DNA na caracterização de cultivares constitui uma ferramenta de grande valor, principalmente em situações em que marcadores morfológicos e isoenzimáticos já foram empregados, caso do capim-elefante. Em vista disso, objetivou-se estimar a divergência genética entre cultivares de capim-elefante do grupo "Napier" provenientes do Banco Ativo de Germoplasma de capim-elefante da EMBRAPA Gado de Leite, por meio de marcadores RAPD. As reações de polimerase em cadeia com 37 iniciadores arbitrários da série OPERON Technologies proporcionaram 94 bandas polimórficas e 73 monomórficas. Por meio da matriz do complemento do índice de Nei, a análise de agrupamento pelo método de otimização de Tocher indicou a formação de três grupos. Correlação de Pearson entre estimativas de distância genética obtidas a partir dos marcadores de DNA e dos marcadores isoenzimáticos indicaram a consistência de ambos os métodos para a avaliação da divergência genética entre cultivares de capim-elefante. Não foram encontradas duplicatas nos tratamentos avaliados.