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São Cristóvão, Brazil

Ribeiro A.N.,Federal Institute of Sergipe | Macedo C.A.,Federal University of Sergipe
Journal of the Korean Physical Society | Year: 2013

The goal of this work is to examine the possibility of ferromagnetism in a three-dimensional lattice using the Hubbard model with only nearest-neighbor hopping and finite on-site Coulomb interaction (U) and temperature (T) when solved using the dynamical mean-field approximation (DMFA). We calculated the density of states for an fcc lattice with n = 0.6, 0.7 and 0.8, at T = 0.04 t/k B, and with U = 3W where W denotes the non-interacting energy bandwidth. The results reveal magnetization that is nearly saturated and indicate that these systems are metallic. In the particular case where n = 0.6, the magnetization, internal energy and specific-heat versus temperature curves were calculated. © 2013 The Korean Physical Society. Source


de Oliveira R.P.,Federal University of Bahia | de Oliveira R.P.,Federal Institute of Sergipe | de Almeida E.S.,Federal University of Bahia | da Silva Gomes G.S.,Federal University of Bahia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

The evolution of a single system is a task where we deal with the modification of a single product. Lehman’s laws of software evolution were broadly evaluated within this type of systems and the results shown that these single systems evolve according to his stated laws over time. However, when dealing with Software Product Lines (SPL), we need to deal with the modification of several products which include common, variable and product specific assets. Because of the several assets within SPL, each stated law may have a different behavior for each asset kind. Nonetheless, we do not know if the stated laws are still valid for SPL since they were not yet evaluated in this context. Thus, this paper details an empirical investigation where four of the Lehman’s Laws (LL) of Software Evolution were used in an SPL industrial project to understand how the SPL assets evolve over time. This project relates to an application in the medical domain developed in a medium-size company in Brazil. It contains 45 modules and a total of 70.652 bug requests in the tracking system, gathered along the past 10 years. We employed two techniques - the KPSS Test and linear regression analysis, to assess the relationship between LL and SPL assets. Finally, results showed that three laws were supported based on the data employed (continuous change, increasing complexity, and declining quality). The other law (continuing growth) was partly supported, depending on the SPL evaluated asset (common, variable or product-specific). © Springer International Publishing Switzerland 2014. Source


Silva R.A.L.,Federal University of Lavras | Pio L.A.S.,Federal University of Lavras | Pasqual M.,Federal University of Lavras | De Oliveira A.C.L.,Federal Institute of Sergipe | And 2 more authors.
Semina:Ciencias Agrarias | Year: 2014

Flow cytometry is a technique that yields rapid results in analyses of cell properties such as volume, morphological complexity and quantitative DNA content, and it is considered more convenient than other techniques. However, the analysis usually generates histograms marked by variations that can be produced by many factors, including differences between the software packages that capture the data generated by the flow cytometer. The objective of the present work was to evaluate the performance of four software products commonly used in flow cytometry based on quantifications of DNA content and analyses of the coefficients of variation associated with the software outputs. Readings were obtained from 25 'NBA' (AA) banana leaf samples using the FACSCalibur (BD) flow cytometer, and 25 histograms from each software product (CellQuest™, WinMDI™, FlowJo™ and FCS Express™) were analyzed to obtain the estimated DNA content and the coefficient of variation (CV) of the estimates. The values of DNA content obtained from the software did not differ significantly. However, the CV analysis showed that the precision of the WinMDI™ software was low and that the CV values were underestimated, whereas the remaining software showed CV values that were in relatively close agreement with those found in the literature. The CellQuest™ software is recommended because it was developed by the same company that produces the flow cytometer used in the present study. Source


Santos C.A.S.,Federal University of Espirito Santo | Neto A.N.R.,Federal Institute of Sergipe | Saleme E.B.,Federal University of Espirito Santo
Proceedings - 2015 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2015 | Year: 2015

The paper presents an event driven approach for building interactive environments with sensory effects (such as RGB color light, wind and vibration) described through MPEGV standard. The most important differences of this work from previous ones are: (1) it divides the design process into well defined stages, showing the behavior of the system under a new perspective and their interactions, (2) it follows an event driven paradigm instead of a timeline one to send commands to sensory devices and (3) it decouples rendering of MPEG-V effects from the presentation software component. The method to validate the proposed approach was a case study, which has integrated multiples sensory effects to an interactive environment based on gesture recognizing. © 2015 IEEE. Source


Teixeira V.C.,Federal University of Sergipe | Montes P.J.R.,Federal Institute of Sergipe | Valerio M.E.G.,Federal University of Sergipe
Optical Materials | Year: 2014

Pure, Ce3+ doped and Ce3+ and Mn2+ co-doped Ca2Al2SiO7 ceramic powders were prepared by two different methodologies which are the proteic sol-gel process and a new hybrid route combining the proteic sol-gel with solid state reaction processes. The second one is an eco-friendly method because it uses natural raw materials in replacement of the metal alkoxides used in the traditional sol-gel routes. X-ray diffraction showed that Ca2Al2SiO 7 crystalline phase was obtained for both preparations. Differential thermal analysis indicated that the exothermic event around 850°C, for sample produced by proteic sol-gel method, and around 927°C, for ceramics prepared by hybrid synthesis, can be associated to crystallization of Ca 2Al2SiO7. Transmission electron microscope indicates that regular and spherical nanoparticles were obtained with average sizes of about 12 nm. The Scherrer's method was used to determine the average crystallite sizes and it was shown that nanometric crystallites were obtained of about 74 nm for samples produced via hybrid route. For all the single phase samples, the crystallite sizes are about the same and that agrees with TEM results. Diffuse optical reflectance measurements were used to estimate the Ca2Al2SiO7 optical band gap and the obtained value is about 6 eV, photoluminescence (PL) spectra presented typical emissions of Ce3+ and Mn2+ ions. Upon excitation at 352 nm the emission spectra showed a broad band centered at 415 nm due to the Ce 3+ 4f1 → 5d1 typical transition. This emission is resonant with Mn2+ excitation and it transfers energy to Mn ions generating a second broad emission band centered at 620 nm due to the Mn2+. The PL results were used to obtain, as a fist approach, the Ce3+ energy levels diagram and, using the Tanabe-Sugano diagrams, the transitions due to the Mn2+ were calculated. X-ray excited optical luminescence measurements showed the same emission spectra as the PL emission spectra. Luminescence lifetime decay constants were measured for Ce and Mn co-doped and for Ce doped samples and the results indicate Ca2Al 2SiO7:Ce3+, Mn2+ showed quite fast responses with main time constants below 30 ns. © 2014 Elsevier B.V. All rights reserved. Source

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