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Search Results: 1 - 10 of 141289 matches for " Jo?o Paulo;Xavier "
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Robust Simultaneous Localization of Nodes and Targets in Sensor Networks Using Range-Only Measurements
P\inar O\uguz-Ekim,Joo Gomes,Joo Xavier,Paulo Oliveira
Mathematics , 2010,
Abstract: Simultaneous localization and tracking (SLAT) in sensor networks aims to determine the positions of sensor nodes and a moving target in a network, given incomplete and inaccurate range measurements between the target and each of the sensors. One of the established methods for achieving this is to iteratively maximize a likelihood function (ML), which requires initialization with an approximate solution to avoid convergence towards local extrema. This paper develops methods for handling both Gaussian and Laplacian noise, the latter modeling the presence of outliers in some practical ranging systems that adversely affect the performance of localization algorithms designed for Gaussian noise. A modified Euclidean Distance Matrix (EDM) completion problem is solved for a block of target range measurements to approximately set up initial sensor/target positions, and the likelihood function is then iteratively refined through Majorization-Minimization (MM). To avoid the computational burden of repeatedly solving increasingly large EDM problems in time-recursive operation an incremental scheme is exploited whereby a new target/node position is estimated from previously available node/target locations to set up the iterative ML initial point for the full spatial configuration. The above methods are first derived under Gaussian noise assumptions, and modifications for Laplacian noise are then considered. Analytically, the main challenges to be overcome in the Laplacian case stem from the non-differentiability of $\ell_1$ norms that arise in the various cost functions. Simulation results confirm that the proposed algorithms significantly outperform existing methods for SLAT in the presence of outliers, while offering comparable performance for Gaussian noise.
Approximate Maximum Likelihood Source Localization from Range Measurements Through Convex Relaxation
P?nar O?uz-Ekim,Joo Gomes,Joo Xavier,Marko Sto?i?,Paulo Oliveira
Mathematics , 2011,
Abstract: This work considers the problem of locating a single source from noisy range measurements to a set of nodes in a wireless sensor network. We propose two new techniques that we designate as Source Localization with Nuclear Norm (SLNN) and Source Localization with l1-norm (SL-l1), which extend to arbitrary real dimensions, including 3D, our prior work on 2D source localization formulated in the complex plane. Broadly, our approach is based on formulating a Maximum-Likelihood (ML) estimation problem for the source position, and then using convex relaxation techniques to obtain a semidefinite program (SDP) that can be globally and efficiently solved. SLNN directly approximates the Gaussian ML solution, and the relaxation is shown to be tighter than in other methods in the same class. We present an analysis of the convexity properties of the constraint set for the 2D complex version of SLNN (SLCP) to justify the observed tightness of the relaxation. In terms of global accuracy of localization, SLNN outperforms state-of-the-art optimization-based methods with either iterative or closed-form formulations. We propose the SL-l1 algorithm to address the Laplacian noise case, which models the presence of outliers in range measurements. We overcome the nondifferentiability of the Laplacian likelihood function by rewriting the ML problem as an exact weighted version of the Gaussian case, and compare two solution strategies. One of them is iterative, based on block coordinate descent, and uses SLNN as a subprocessing block. The other, attaining only slightly worse performance, is noniterative and based on an SDP relaxation of the weighted ML problem.
Resposta inflamatória causada pelas fra??es do adesivo de gelatina-resorcina e formaldeído (Colagel?) em camundongos
Campos, Andressa Gianotti;Ferrigno, Cássio Ricardo Auada;Boccia, Joo Paulo;Xavier, José Guilhherme;
Ciência Rural , 2000, DOI: 10.1590/S0103-84782000000500016
Abstract: the use of glue for biological purposes has been under study for a long time, an example is the adhesive composed of gelatin-resorcine and formaldehyde (colagel?). the inflammatory reaction produced by the application of the adhesive on organic tissues encouraged the search for the component of the glue responsible for this reaction. thus, the application of several fractions of the referred adhesive (gelatin-resorcine, formaldehyde, polymerized glue in situ and polymerized glue before the application) was accomplished in different groups of mice in the following periods: 2, 10, 30 and 60 days after surgery. through the evaluation of histological sections, it was observed that all the groups presented, with different degrees of intensity, inflammatory polimorfonuclear infiltrate with a predominance of neutrophils. the group which received only the formaldehyde was the one that expressed a greater tissue reaction with a great amount of inflammatory infiltrate, dissociation of muscle fibers, angiogenesis and fibrosi. there was also great amount of infiltrate as a reaction to the polymerization in situ, adding to it intense fibrogenesis of the deep dermis and hypoderm, together with the degeneration of miocites and extensive areas of tissue necrosis. the group that received only the gelatin-resorcine reveled discrete polimorfonuclear infiltration, the same results occurred after the use of the glue previously polymerized. therefore, the fraction of the colagel? responsible for the greater inflammatory reaction was the polymerizing formaldehyde when it was applied to the tissue alone or polymerized in situ. the polymerization before the application turns the colagel? less irritating to the tissue, therefore, this is the most convenient way of utilization.
Likely Rainfall for Alegre-ES by the Gamma Probability Distribution
Joo Paulo Bestete de Oliveira,Roberto Avelino Cecílio,Alexandre Candido Xavier,Andrea Pinheiro dos Santos Jasper
Engenharia Ambiental : Pesquisa e Tecnologia , 2010,
Abstract: The objective of this study was to estimate rainfall expected for Alegre-ES by the gamma distribution. We used rainfall data covering the period from 1940 to 2007. The parameters α and β of the gamma distribution were obtained by the method of maximum likelihood. Probable rainfall were obtained by the inverse function. We used the test of Kolmogorov-Smirnov test to check the fit of estimated to observed data. The results indicated that the gamma distribution provided a good fit to the data of rain to Alegre-ES can therefore be used to estimate the likely monthly rainfall.
Produ??o e comportamento reológico de exopolissacarídeos sintetizados por rizóbios isolados de guandu
Fernandes Júnior, Paulo Ivan;Almeida, Joo Pedro da Silva;Passos, Samuel Ribeiro;Oliveira, Paulo Jansen de;Rumjanek, Norma Gouvêa;Xavier, Gustavo Ribeiro;
Pesquisa Agropecuária Brasileira , 2010, DOI: 10.1590/S0100-204X2010001200018
Abstract: the objective of this work was to evaluate the production and the rheological behavior of exopolysaccharides (eps) produced by pigeonpea [cajanus cajan (l.) millsp.] rhizobia isolates, as well as to evaluate the similarity of these isolates through amplified ribosomal dna restriction analysis technique. the bacteria were cultured in ym liquid media and the eps were precipited with cold ethanol from culture broth. after that, they were vacuum dried, weighted, stored and resuspended in water to rheological evaluations. the three evaluated isolates showed differences on the production and productivity of eps, and the isolate 8.1c stood out, with higher relative efficiency. the evaluated eps showed non-newtonian and pseudoplastic behavior, however they also presented differences as to the apparent viscosity at the same shear rate. at the shear rate of 1 s-1 all isolates were different, while at the shear rate of 40 s-1 the isolates 53.5 and 30.6a2 were the same, differing from the isolate 8.1c. genetic similarity of the isolates was in agreement with the rheology results, where bacteria that synthesized eps with lower apparent viscosity presented the higher similarity
Estimativa de ocorrência de precipita??o em áreas agrícolas utilizando floresta de caminhos ótimos
Freitas, Greice Martins de;Papa, Joo Paulo;Avila, Ana Maria Heuminski de;Pinto, Alexandre Xavier Falc?o Hilton Silveira;Pinto, Hilton Silveira;
Revista Brasileira de Meteorologia , 2010, DOI: 10.1590/S0102-77862010000100002
Abstract: meteorological conditions are determinant for the agricultural production; in particular, rainfall may be cited as the most important because having direct relation with water balance. to estimate agricultural production, agrometeorological models based on the cultures behavior under meteorological conditions, have been used. since it is difficult to obtain the required data to these models, rainfall estimation techniques using meteorological satellites images from spectral channels have been used. the objective of the present work is to apply the optimum-path forest pattern classifier to the agrometeorological research field in order to correlate the available information from goes-12 satellite infrared spectral channel images, to the reflectivity data obtained by the ipmet/unesp radar located at bauru, aiming to develop a model for precipitation occurrence identification. in the experiments we compared four classification algorithms: artificial neural networks (ann), k-nearest neighbors (k-nn), support vector machines (svm) and optimum-path forest (opf). this last one shows the best results in terms of accuracy rate and running time.
Experimental canine model for sentinel lymph node biopsy in the vulva using technetium and patent blue dye
Aquino, José Ulcijara;Pinheiro, Luiz Gonzaga Porto;Vasques, Paulo Henrique Diógenes;Rocha, Joo Ivo Xavier;Cruz, Diego Alves;Beserra, Hugo Enrique Orsini;Cavalcante, Raissa Vasconcelos;
Acta Cirurgica Brasileira , 2012, DOI: 10.1590/S0102-86502012000200002
Abstract: purpose: this paper aims to study and define the experimental model of sentinel lymph node biopsy of the vulva in bitches. methods: 0.2 ml of 99mtc phytate was injected intradermally, using a fine gauge insulin needle in the anterior commissure of the vulva. thirty minutes after 99mtc injection, the inguinal mapping was performed using a gamma probe. after this, 0.5 ml of blue dye (bleu patenté v guerbet 2.5%) was injected in the same place. after 15 minutes, a 3 cm long inguinal incision was made at point maximum uptake followed by careful dissection, guided by visualization of a bluish afferent lymphatic system that points to the sentinel lymph node (sln). results: it was observed that 88% of sln were identified. it wasn′t found a significant difference among the presence or not of sentinel lymph node in the sides, which is an indication of a good consistency. it was observed a high (88%) and significant (χ2=12.89 and p=0.0003) intercession between both methods (blue dye and radiation). conclusion: the experimental model adopted is feasible, becoming advantageous in applying the association of patent blue and 99mtc.
Avalia??o e tratamento fisioterápico na doen?a arterial obstrutiva periférica de membro superior: um estudo de caso
Pereira, Danielle Aparecida Gomes;Custódio, Marcelle Xavier;Carvalho, Joo Paulo Ferreira de;Carvalho, André Maurício Borges de;Cunha-Filho, Inácio Teixeira da;
Jornal Vascular Brasileiro , 2008, DOI: 10.1590/S1677-54492008000100013
Abstract: the aim of this paper was to present a case study proposing a protocol for assessment and rehabilitation of a patient with upper limb intermittent claudication. case description: 50-year-old woman with obstruction of the left brachial artery secondary to catheterization performed 4 months ago. monophasic sound was observed during continuous doppler ultrasound assessment of both the radial and ulnar arteries. during the arm crank test, ischemic pain started at 2 minutes and 30 seconds of cranking, while maximal pain was reached at 9 minutes and 26 seconds. the patient was treated by arm cranking exercises performed three times a week for 8 weeks. after the treatment, arm crank time increased: ischemic pain onset was at 5 minutes and 7 seconds and maximal pain was reached at 18 minutes. the patient reported disappearance of cyanosis and improvement in performance of daily activities. the assessment protocol comprehended both subjective (validated brazilian portuguese version of sf-36 questionnaire) and objective (arm crank) measurements and was well tolerated, besides being able to detect changes in the patient's functional capacity. changes detected at pain onset and at maximal pain may have occurred spontaneously, but it cannot be ruled out that this intervention can be potentially beneficial for individuals with upper limb claudication. the results observed in this case study warrant further studies involving larger sample size.
The impact of previous para-areolar incision in the upper outer quadrant of the breast on the localization of the sentinel lymph node in a canine model
Vasques, Paulo Henrique Diógenes;Pinheiro, Luiz Gonzaga Porto;Silva, Joo Marcos de Meneses e;Torres-de-Melo, José Ricardo de Moura;Pinheiro, Karine Bessa Porto;Rocha, Joo Ivo Xavier;
Clinics , 2011, DOI: 10.1590/S1807-59322011000800018
Abstract: objectives: this paper discusses the influence of a para-areolar incision in the upper outer quadrant of the breast on the location of the sentinel lymph node in a canine model. methods: the sentinel lymph node was marked with technetium-99, which was injected into the subareolar skin of the cranial breast. after the marker had migrated to the axilla, an arcuate para-areolar incision was performed 2 cm from the nipple in the upper outer quadrant. patent blue dye was then injected above the upper border of the incision. at the marked site, an axillary incision was made, and the sentinel lymph node was identified by gamma probe and/or by direct visualization of the dye. the agreement between the two injection sites and the two sentinel lymph node identification methods was determined. our sample group consisted of 40 cranial breasts of 23 adult females of the species canis familiaris. the data were analyzed by using the mcnemar test and by determining the kappa agreement coefficient. result: our findings showed that in 95% of the breasts, the sentinel lymph node was identified by the injection of technetium-99 m into the subareolar region, and in 82% of the cases, the sentinel lymph node was identified by the injection of patent blue dye above the upper border of the incision. the methods agreed 82% of the time. conclusions: previous para-areolar incisions in the upper outer quadrant did not interfere significantly with the biopsy when the dye was injected above the upper border of the incision.
Mortality of Plutella xylostella larvae treated with Aspidosperma pyrifolium ethanol extracts
Trindade, Roseane Cristina Prédes;Silva, Paulo Pedro da;Araújo-Júnior, Joo Xavier de;Lima, Ivanildo Soares de;Paula, José Elias de;Sant'Ana, Ant?nio Euzébio Goulart;
Pesquisa Agropecuária Brasileira , 2008, DOI: 10.1590/S0100-204X2008001200024
Abstract: the objective of this work was to assess the effects of aspidosperma pyrifolium ethanol extracts on cabbage moth (plutella xylostella) larvae. the ethanol extracts of the stem bark, fruits and roots of a. pyrifolium were obtained by classical phytochemical methods, and the resulting subfractions were tested on p. xylostella, using 4 and 5 mg l-1. the crude ethanol extract of the stem bark was more lethal. the alkaloid-rich aqueous subfraction derived from the stem bark extract caused 100% larval mortality at 4 mg l-1. insecticidal activity was associated with the presence of the monoterpenoid indole alkaloids aspidofractinine, 15-demethoxypyrifoline, and n-formylaspidofractinine. these alkaloids presented excellent insecticidal properties against p. xylostella.
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