1,014 research outputs found
Estabelecimento de leguminosas como cobertura verde de solo de café em produção na região do Cerrado.
WASP-33: The first delta Scuti exoplanet host star
We report the discovery of photometric oscillations in the host star of the
exoplanet WASP-33 b (HD 15082). The data were obtained in the R band in both
transit and out-of-transit phases from the 0.3-m telescope and the Montcabrer
Observatory and the 0.8-m telescope at the Montsec Astronomical Observatory.
Proper fitting and subsequent removal of the transit signal reveals stellar
photometric variations with a semi-amplitude of about 1 mmag. The detailed
analysis of the periodogram yields a structure of significant signals around a
frequency of 21 cyc per day, which is typical of delta Scuti-type variable
stars. An accurate study of the power spectrum reveals a possible
commensurability with the planet orbital motion with a factor of 26, but this
remains to be confirmed with additional time-series data that will permit the
identification of the significant frequencies. These findings make WASP-33 the
first transiting exoplanet host star with delta Sct variability and a very
interesting candidate to search for star-planet interactions.Comment: 5 pages, 6 figures. Revised version accepted for publication in A&A
Letter
Detec??o de descontinuidades no processo de soldagem por eletrodo revestido por meio de intelig?ncia computacional.
Programa de P?s-Gradua??o em Engenharia de Materiais. Departamento de Engenharia Metal?rgica, Escola de Minas, Universidade Federal de Ouro Preto.Prop?e-se neste trabalho uma nova metodologia para a detec??o de descontinuidades no cord?o
de solda aplicado em processos de soldagem por eletrodos revestidos (SMAW). Para a execu??o
dos experimentos e otimiza??o de par?metros do processo, foi desenvolvida uma esta??o de
soldagem robotizada. O sistema de detec??o baseia-se em dois sensores ? um microfone e um
cristal piezoel?trico ? que adquirem as emiss?es ac?sticas geradas durante a soldagem. Os
vetores de caracter?sticas extra?dos do conjunto de dados dos sensores s?o usados para construir
os modelos dos classificadores. As abordagens baseadas nos classificadores de Rede Neural
Artificial (RNA) e de M?quina de Vetor de Suporte (SVM) s?o capazes de identificar com alta
acur?cia as tr?s classes propostas de cord?es de solda: cord?o de solda normal, e
descontinuidades de cratera e de perfura??o. Os resultados experimentais ilustram a acur?cia
do sistema, superior a 83% para cada classe. Uma nova estrutura de m?quinas de suporte
hier?rquico (HSVM) ? proposta para viabilizar o uso deste sistema em ambientes industriais.
Esta abordagem apresentou 96,6% de acur?cia global. Este sistema pode ser aplicado nas
ind?strias metal-mec?nicas.One proposes in this work a new methodology for the detection of discontinuities in the weld
bead applied in Shielded Metal Arc Welding (SMAW) processes. A robotized welding station
was developed for the execution of the experiments and optimization of process parameters.
The detection system is based on two sensors ? a microphone and piezoelectric ? that acquire
acoustic emissions generated during the welding. The feature vectors extracted from the sensor
dataset are used to construct classifier models. The approaches based on Artificial Neural
Network (ANN) and Support Vector Machine (SVM) classifiers are able to identify with high
accuracy the three proposed weld bead classes: desirable weld bead, shrinkage cavity and burn
through discontinuities. Experimental results illustrate the system?s accuracy, greater than 83%
for each class. A novel Hierarchical Support Vector Machine (HSVM) structure is proposed to
make feasible the use of this system in industrial environments. This approach presented 96.6%
overall accuracy. This system can be applied in the metal-mechanical industries
Produção de frutos e caracterização de ambientes de ocorrência de plantas nativas de Araticum no Cerrado de Goiás.
Este estudo teve como objetivo avaliar a produção de frutos de araticum no Cerrado do Estado de Goiás. Foram selecionadas, para a realização do trabalho, 14 áreas de ocorrência natural do araticum no Estado de Goiás, de janeiro de 2000 a julho de 2002. Em cada área, foram selecionadas de 30 a 40 plantas adultas de araticum. O delineamento experimental adotado corresponde ao modelo hierárquico, para produção de frutos, sendo os dados obtidos submetidos à análise de variância. A estrutura espacial da variação fenotípica entre as populações das áreas analisadas foi investigada a partir do critério de ligação UPGMA. Os resultados demonstraram que a produção de frutos de araticum é baixa e variável entre as áreas e entre os anos, sendo a média de 2,97 aproveitáveis e de 1,37 frutos inaproveitáveis por planta. A variação fenotípica de caracteres morfológicos entre populações de araticum do Estado de Goiás não apresenta um padrão de estruturação espacial. A produção de frutos por planta é muito variável, sendo que algumas plantas apresentam características produtivas e de qualidade aparente de frutos que as credenciam com potencial para plantas-matrizes. As principais pragas que atacam os frutos de araticum são: Spermologus funereus, Cerconota anonella e Bephratelloides pomorum. A pressão antrópica sobre os ambientes naturais de produção de araticum tem reduzido a produção atual e pode inviabilizar as produções futuras
Recommended from our members
Assessment of inter-examiner agreement and variability in the manual classification of auditory brainstem response
Abstract
Background: The analysis of the Auditory Brainstem Response (ABR) is of
fundamental importance to the investigation of the auditory system behaviour,
though its interpretation has a subjective nature because of the manual process
employed in its study and the clinical experience required for its analysis. When
analysing the ABR, clinicians are often interested in the identification of ABR signal
components referred to as Jewett waves. In particular, the detection and study of
the time when these waves occur (i.e., the wave latency) is a practical tool for the
diagnosis of disorders affecting the auditory system. Significant differences in
inter-examiner results may lead to completely distinct clinical interpretations of the
state of the auditory system. In this context, the aim of this research was to evaluate
the inter-examiner agreement and variability in the manual classification of ABR.
Methods: A total of 160 ABR data samples were collected, for four different stimulus
intensity (80dBHL, 60dBHL, 40dBHL and 20dBHL), from 10 normal-hearing subjects
(5 men and 5 women, from 20 to 52 years). Four examiners with expertise in the
manual classification of ABR components participated in the study. The Bland-Altman
statistical method was employed for the assessment of inter-examiner agreement
and variability. The mean, standard deviation and error for the bias, which is the
difference between examiners’ annotations, were estimated for each pair of
examiners. Scatter plots and histograms were employed for data visualization and
analysis.
Results: In most comparisons the differences between examiner’s annotations were
below 0.1 ms, which is clinically acceptable. In four cases, it was found a large error
and standard deviation (>0.1 ms) that indicate the presence of outliers and thus,
discrepancies between examiners.
Conclusions: Our results quantify the inter-examiner agreement and variability of
the manual analysis of ABR data, and they also allows for the determination of
different patterns of manual ABR analysis
Is the β Pictoris member GJ 3039AB a physical binary? What the rotation periods tell us?
We have carried out a multi-band photometric monitoring of the close visual binary GJ 3039, consisting of a M4 primary and a fainter secondary component, and likely member of the young stellar association β Pictoris (24-Myr old). From our analysis we found that both components are photometric variables and, for the first time, we detected two micro-flare events. We measured from periodogram analysis of the photometric time series two rotation periods P = 3.355 d and P = 0.925 d, that we could attribute to the brighter GJ 3039A and the fainter GJ 3039B components, respectively. A comparison of these rotation periods with the period distribution of other β Pictoris members further supports that GJ 3039A is a member of this association. We find that also GJ 3039B could be a member, but the infrared magnitude differences between the two components taken from the literature and the photometric variability, which is found to be comparable in both stars, suggest that GJ 3039B could be a foreground star physically unbound to the primary A component
Rendimento industrial e composição química de milho de alta qualidade protéica em relação a híbridos comerciais.
A dureza do endosperma do milho é atributo essencial para produtores e indústrias que utilizam este cereal como matéria-prima. Porém, os milhos de alta qualidade protéica (Quality Protein Maize – QPM) apresentam alterações na textura do grão, dificultando seu uso comercial. Este trabalho avaliou o rendimento industrial na degerminação do grão e fracionamento do endosperma, e a composição química de uma variedade de milho QPM, em relação a híbridos comerciais de milho comum
- …