Carnelossi Furlaneto D.,Federal University of Paraná |
Oliveira L.S.,Federal University of Paraná |
Menotti D.,Federal University of Paraná |
Cavalcanti G.D.C.,Cidade Universitria
Expert Systems with Applications | Year: 2017
Financial time series are notoriously difficult to analyze and predict, given their non-stationary, highly oscillatory nature. In this study, we evaluate the effectiveness of the Ensemble Empirical Mode Decomposition (EEMD), the ensemble version of Empirical Mode Decomposition (EMD), at generating a representation for market indexes that improves trend prediction. Our results suggest that the promising results reported using EEMD on financial time series were obtained by inadvertently adding look-ahead bias to the testing protocol via pre-processing the entire series with EMD, which affects predictive results. In contrast to conclusions found in the literature, our results indicate that the application of EMD and EEMD with the objective of generating a better representation for financial time series is not sufficient to improve the accuracy or cumulative return obtained by the models used in this study. © 2017 Elsevier Ltd
Lima E.P.,Federal University of Ceará |
Paiva M.H.S.,Cidade Universitria |
Paiva M.H.S.,Bairro Universitrio |
De Aruajo A.P.,Cidade Universitria |
And 10 more authors.
Parasites and Vectors | Year: 2011
Background: Organophosphates and pyrethroids are used widely in Brazil to control Aedes aegypti, the main vector of dengue viruses, under the auspices of the National Programme for Dengue Control. Resistance to these insecticides is widespread throughout Brazil. In Cear the vector is present in 98% of districts and resistance to temephos has been reported previously. Here we measure resistance to temephos and the pyrethroid cypermethrin in three populations from Cear and use biochemical and molecular assays to characterise resistance mechanisms. Results: Resistance to temephos varied widely across the three studied populations, with resistance ratios (RR95) ≥ of 7.2, 30 and 192.7 in Juazeiro do Norte, Barbalha and Crato respectively. The high levels of resistance detected in Barbalha and Crato (RR95 30) imply a reduction of temephos efficacy, and indeed in simulated field tests reduced effectiveness was observed for the Barbalha population. Two populations (Crato and Barbalha) were also resistant to cypermethrin, whilst Juazeiro do Norte showed only an altered susceptibility. The Ile1011Met kdr mutation was detected in all three populations and Val1016Ile in Crato and Juazeiro do Norte. 1011Met was significantly associated with resistance to cypermethrin in the Crato population. Biochemical tests showed that only the activity of esterases and GSTs, among the tested detoxification enzymes, was altered in these populations when compared with the Rockefeller strain. Conclusions: Our results demonstrate that two A. aegypti populations from Cear are under strong selection pressure by temephos, compromising the field effectiveness of this organophosphate. Our results also provide evidence that the process of reducing resistance to this larvicide in the field is difficult and slow and may require more than seven years for reversal. In addition, we show resistance to cypermethrin in two of the three populations studied, and for the first time the presence of the allele 1016Ile in mosquito populations from northeastern Brazil. A significant association between 1011Met and resistance was observed in one of the populations. Target-site mechanisms seem not to be implicated in temephos resistance, reinforcing the idea that for the studied populations, detoxification enzymes most likely play a major role in the resistance to this insecticide. © 2011 Lima et al; licensee BioMed Central Ltd.
Paulino-Lima I.G.,Cidade Universitria |
Pilling S.,Brazilian Synchrotron Light Laboratory (LNLS) |
Janot-Pacheco E.,Cidade Universitria |
De Brito A.N.,Brazilian Synchrotron Light Laboratory (LNLS) |
And 3 more authors.
Planetary and Space Science | Year: 2010
The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m-2, corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes. © 2010 Elsevier Ltd.
Guedes M.A.,University of Sao Paulo |
Paolini T.B.,University of Sao Paulo |
Felinto M.C.F.C.,Brazilian National Nuclear Energy Commission |
Kai J.,University of Sao Paulo |
And 4 more authors.
Journal of Luminescence | Year: 2011
In this work a series of tetrakis complexes C[Tm(acac)4], where C=Li, Na and K countercations and acac=acetylacetonate ligand, were synthesized and characterized for photoluminescence investigation. The relevant aspect is that these complexes are water-free in the first coordination sphere. The emission spectra of the tetrakis Tm3-complexes present narrow bands characteristic of the 1G4→3H6 (479 nm), 1G4→3F4 (650 nm) and 1G4→3H5 (779 nm) transitions of the Tm3 ion, with the blue emission color at 479 nm as the most prominent one. The lifetime values (τ) of the emitting 1G 4 level of the C[Tm(acac)4] complexes were 344, 360 and 400 ns for the Li, Na and K countercations, respectively, showing an increasing linear behavior versus the ionic radius of the alkaline ion. An efficient intramolecular energy transfer process from the triplet state (T) of the ligands to the emitting 1G4 state of the Tm3 ion is observed. This fact, together with the absence of water molecules in first coordination sphere, allows these tetrakis Tm3-complexes to act as efficient blue light conversion molecular devices. © 2010 Elsevier B.V.
Costa P.L.,Cidade Universitria |
Silva F.J.,Cidade Universitria |
Andrade Filho J.D.,Centro Of Referrncia Nacional E Internacional Para Flebotomineos |
Shaw J.J.,University of Sao Paulo |
Brando Filho S.P.,Cidade Universitria
Journal of the American Mosquito Control Association | Year: 2012
Approximately 800 species of phlebotomine sand flies, many of which are vectors of Leishmania, have been described. Besides morphological similarities within groups, the occurrence of anomalies within a species may lead to an erroneous description of new species. This paper describes one phlebotomine sand fly, Evandromyia evandroi, with a symmetrical bilateral anomaly in the number of spines on the gonostyle. In this specimen, the anomalous spine is located in the external region of gonostyle, inserted between the upper external and the lower external spines. It is important to document morphological anomalies, so as to avoid erroneous sand fly identifications. © 2012 by The American Mosquito Control Association, Inc.
Da Costa Mattos H.S.,Federal University of Fluminense |
Sampaio E.M.,State University of Rio de Janeiro |
Monteiro A.H.,Cidade Universitria
International Journal of Adhesion and Adhesives | Year: 2010
The present work is concerned with the study of the influence of adhesive layer thickness on the mechanical strength of axially loaded aluminiumepoxy butt joints. The main goal is to predict the rupture force using model equations that combine enough mathematical simplicity to allow their usage in engineering problems with the capability of describing a complex non-linear mechanical behaviour (three-dimensional state of stress; possibility of cohesive failure, of adhesive failure or mixed failure, depending on the geometry of the joint, on the adhesive strength and on the interaction between surfaces). The predicted values of the rupture force for different values of the thickness of the adhesive layer are compared with experimental data, showing a good agreement. © 2010 Elsevier Ltd.
Rocha A.B.,Cidade Universitria |
De Moura C.E.V.,Cidade Universitria
Journal of Chemical Physics | Year: 2011
Potential energy curves for inner-shell states of nitrogen and carbon dioxide molecules are calculated by inner-shell complete active space self-consistent field (CASSCF) method, which is a protocol, recently proposed, to obtain specifically converged inner-shell states at multiconfigurational level. This is possible since the collapse of the wave function to a low-lying state is avoided by a sequence of constrained optimization in the orbital mixing step. The problem of localization of K-shell states is revisited by calculating their energies at CASSCF level based on both localized and delocalized orbitals. The localized basis presents the best results at this level of calculation. Transition energies are also calculated by perturbation theory, by taking the above mentioned MCSCF function as zeroth order wave function. Values for transition energy are in fairly good agreement with experimental ones. Bond dissociation energies for N 2 are considerably high, which means that these states are strongly bound. Potential curves along ground state normal modes of CO 2 indicate the occurrence of Renner-Teller effect in inner-shell states. © 2011 American Institute of Physics.
De Oliveira R.L.,Cidade Universitria |
Carrasco E.R.,Gemini Observatory |
De Oliveira C.M.,Cidade Universitria |
Bortoletto D.R.,Cidade Universitria |
And 4 more authors.
Astronomical Journal | Year: 2010
We present a new insight on NGC 6034 and UGC 842, two groups of galaxies previously reported in the literature as being fossil groups. The study is based on optical photometry and spectroscopy obtained with the CTIO Blanco telescope and Sloan Digital Sky Survey archival data. We find that NGC 6034 is embedded in a large structure, dominated by three rich clusters and other small groups. Its first and next four ranked galaxies have magnitude differences in the r band and projected distances which violate the optical criteria to classify it as a fossil group. We confirm that the UGC 842 group is a fossil group, but with about half the velocity dispersion that is reported in previous works. The velocity distribution of its galaxies reveals the existence of two structures in its line of sight, one with σν ∼ 223 km s-1 and another with σν ∼ 235 km s-1, with a difference in velocity of ∼ 820 km s-1. The main structure is dominated by passive galaxies, while these represent ∼ 60% of the second structure. The X-ray temperature for the intragroup medium of a group with such a velocity dispersion is expected to be kT ∼ 0.5-1 keV, against the observed value of kT ∼ 1.9 keV reported in the literature. This result makes UGC 842 a special case among fossil groups because (1) it represents more likely the interaction between two small groups, which warms the intragroup medium and/or (2) it could constitute evidence that member galaxies lost energy in the process of spiraling toward the group center, and decreased the velocity dispersion of the system. As far as we know, UGC 842 is the first low-mass fossil group studied in detail. © 2010. The American Astronomical Society. All rights reserved.
Pianto D.M.,Campus Universitrio Darcy Ribeiro |
Cribari-Neto F.,Cidade Universitria
Computational Statistics and Data Analysis | Year: 2011
In this paper we study maximum likelihood estimation (MLE) of the roughness parameter of the GA0 distribution for speckled imagery (Frery et al., 1997). We discover that when a certain criterion is satisfied by the sample moments, the likelihood function is monotone and MLE estimates are infinite, implying an extremely homogeneous region. We implement three corrected estimators in an attempt to obtain finite parameter estimates. Two of the estimators are taken from the literature on monotone likelihood (Firth, 1993; Jeffreys, 1946) and one, based on resampling, is proposed by the authors. We perform Monte Carlo experiments to compare the three estimators. We find the estimator based on the Jeffreys prior to be the worst. The choice between Firth's estimator and the Bootstrap estimator depends on the value of the number of looks (which is given before estimation) and the specific needs of the user. We also apply the estimators to real data obtained from synthetic aperture radar (SAR). These results corroborate the Monte Carlo findings. Further clarification of the choice between the Firth and Bootstrap estimators will be obtained through future studies of the classification properties of these estimators. © 2010 Elsevier B.V. All rights reserved.
Franca B.W.,Cidade Universitria |
Aredes M.,Federal University of Rio de Janeiro
IECON Proceedings (Industrial Electronics Conference) | Year: 2011
In this paper the Unified Power Quality conditioner is studied with conventional operation mode (UPQC) and with its dual topology (iUPQC). The iUPQC is presented as solution to improve the dynamic response in power quality disturbance mitigation. Comparisons in steady-state and dynamic response are provided. Simulations and experimental results are shown to verify the iUPQC behavior for power quality safety and several load change issues. © 2011 IEEE.