Dynamic Clustering of Histogram Data Based on Adaptive Squared Wasserstein Distances

This paper deals with clustering methods based on adaptive distances for histogram data using a dynamic clustering algorithm. Histogram data describes individuals in terms of empirical distributions. These kind of data can be considered as complex descriptions of phenomena observed on complex objects: images, groups of individuals, spatial or temporal variant data, results of queries, environmental data, and so on. The Wasserstein distance is used to compare two histograms. The Wasserstein distance between histograms is constituted by two components: the first based on the means, and the second, to internal dispersions (standard deviation, skewness, kurtosis, and so on) of the histograms. To cluster sets of histogram data, we propose to use Dynamic Clustering Algorithm, (based on adaptive squared Wasserstein distances) that is a k-means-like algorithm for clustering a set of individuals into $K$ classes that are apriori fixed. The main aim of this research is to provide a tool for clustering histograms, emphasizing the different contributions of the histogram variables, and their components, to the definition of the clusters. We demonstrate that this can be achieved using adaptive distances. Two kind of adaptive distances are considered: the first takes into account the variability of each component of each descriptor for the whole set of individuals; the second takes into account the variability of each component of each descriptor in each cluster. We furnish interpretative tools of the obtained partition based on an extension of the classical measures (indexes) to the use of adaptive distances in the clustering criterion function. Applications on synthetic and real-world data corroborate the proposed procedure

Influência do ângulo e do coeficiente de atrito nas tensões residuais geradas na trefilação de barras de aço AISI 1045

Wire Drawing is one of the most widely used metal forming processes in the manufacture of round steel bars and, of all, this process allows a high dimensional accuracy to the parts. To improve this process, it is necessary to know all the parameters and to identify their influence in the quality of the manufactured product. This study aims to evaluate the influence of friction and the die angle, by numerical simulation, in the residual stresses and distortions generated after heat treatment. Numerical simulations of the drawing process of round bars of AISI 1045 steel were carried out for a given diameter reduction aiming to evaluate the residual stresses in the center and on the surface of the bars. The simulations were performed considering an elastoplastic material from the Simufact.Forming- GP® database software, in which the die angle and the friction coefficient between the tool and the bars were varied. The validity of the simulations was evaluated by comparing the forces taken from simulation and the forces calculated by empirical equations found in the literature. The simulation results showed greater influence of friction and of the die angle in the residual stresses on the surface of the bar. In the center, the influence in the residual stresses is higher for small die angles. With the analysis of the comparison between the forces it may be assumed that the model has been reproduced correctly and that it can predict the force values of the process. Also, there was a greater influence of the die angle relative to the friction coefficient in the emergence of residual stresses.Key words: wire drawing, friction, die angle.Trefilação é um dos processos de conformação mecânica mais utilizados na fabricação de barras redondas de aço. Este processo permite alcançar grande precisão dimensional, ótimo acabamento final, além de melhorar a resistência mecânica do produto final. Para uma melhora do processo, é necessário ter conhecimento dos seus parâmetros, identificar a influência de cada um e controlá-los para manter a qualidade da peça acabada, para que se evitem distorções que acarretam em custos elevados na sua correção. Este trabalho tem por objetivo avaliar, através de simulação numérica computacional, a influência do coeficiente de atrito e do ângulo de fieira na geração das tensões residuais, comumente associadas às distorções finais de peças trefiladas após tratamento térmico. Foram realizadas simulações numéricas de um processo de trefilação de barras redondas de aço AISI 1045 para uma dada redução de diâmetro com o objetivo de se avaliar o gradiente das tensões residuais no centro e na superfície das barras. As simulações foram realizadas considerando um material em regime elastoplástico do banco de dados do software Simufact. FormingGP®, onde foram variados o ângulo da fieira e o coeficiente de atrito entre a ferramenta e a barra trefilada. Para a validação dessas simulações, foram comparadas as forças geradas pelo processo simulado e as forças calculadas por equações empíricas encontradas na literatura. Os resultados das simulações mostraram maior influência do atrito e do ângulo da fieira nas tensões residuais da superfície da barra. No centro, a influência das tensões residuais é maior para os ângulos menores de fieira. Com a análise da comparação entre as forças, pode-se considerar que o modelo foi reproduzido corretamente e pode prever os valores de força do processo. Evidenciou-se também maior influência do ângulo de fieira em relação ao atrito no surgimento das tensões residuais.Palavras-chave: trefilação, atrito, ângulo de fieira

Method for obtaining high-resolution proteomic analysis from pericarps of guarana

Guarana has great agricultural potential and is largely used therapeutically and in the production of non-alcoholic energy drinks. Genomic and proteomic studies are crucial to identify proteins that play central roles in the maintenance and viability of fruits, as well as to identify proteins related to the main metabolic pathways. However, the success of any protein analysis starts with the protein extract preparation, which needs to offer an extract that is free of contaminants. This study aimed to evaluate different extraction methods to obtain high-quantity and high-quality extracts that are compatible with analysis by 2-dimensional electrophoresis and tandem mass spectrometry protein identification. Three different methods were tested: trichloroacetic acid (TCA)/acetone, sodium dodecyl sulfate (SDS)/phenol, and polyvinylpolypyrrolidone (PVPP)/SDS/phenol. The extract obtained from the TCA/acetone precipitation presented low solubility and contamination with lipids and carbohydrates. On the other hand, the quality of the extract gradually improved after using phenol and PVPP/phenol, enabling a yield up to 2 mg/g macerated tissues and the detection of 457 spots by 2-dimensional electrophoresis. The effectiveness of the procedure used was validated by identification of 10 randomly selected proteins by mass spectrometry. The procedure described here can be a starting point for applications using tissues of other organs of guarana or tissues of species that are similar to guarana. © FUNPEC-RP

Electrophoresis and spectrometric analyses of adaptation-related proteins in thermally stressed Chromobacterium violaceum

Chromobacterium violaceum is a Gram-negative proteobacteria found in water and soil; it is widely distributed in tropical and subtropical regions, such as the Amazon rainforest. We examined protein expression changes that occur in C. violaceum at different growth temperatures using electrophoresis and mass spectrometry. The total number of spots detected was 1985; the number ranged from 99 to 380 in each assay. The proteins that were identified spectrometrically were categorized as chaperones, proteins expressed exclusively under heat stress, enzymes involved in the respiratory and fermentation cycles, ribosomal proteins, and proteins related to transport and secretion. Controlling inverted repeat of chaperone expression and inverted repeat DNA binding sequences, as well as regions recognized by sigma factor 32, elements involved in the genetic regulation of the bacterial stress response, were identified in the promoter regions of several of the genes coding proteins, involved in the C. violaceum stress response. We found that 30°C is the optimal growth temperature for C. violaceum, whereas 25, 35, and 40°C are stressful temperatures that trigger the expression of chaperones, superoxide dismutase, a probable small heat shock protein, a probable phasing, ferrichrome-iron receptor protein, elongation factor P, and an ornithine carbamoyltransferase catabolite. This information improves our comprehension of the mechanisms involved in stress adaptation by C. violaceum. © FUNPEC-RP

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters