da Silva A.I.,University Estadual Of Maring
International Journal of Morphology | Year: 2011
The aim of this study was to analyze the somatotype of assistant referees and examine its correlation with physical performance during FIFA physical tests. Study subjects were referees from the Brazilian Football Confederation (CBF) and Paranese Football Federation (FPF) who appeared before the Physical Evaluation Committee of the FPF in order to submit to the physical fitness tests. The sample was comprised of 11 referees from the CBF and considered the elite of Brazil, and 34 FPF referees who officiate at regional level in the state of Parana. In order to determine body composition nine skin folds, nine body circumferences and four bone diameter measures were used. To assess variables related to physical fitness a battery of the following FIFA physical tests were used: two runs of 50 meters and 12 minute running tests. Data analysis of body composition indicated fat percentage of assistant referees from the CBF was 16.74 ± 3.71%, and assistants of the FPF was 17.09 ± 4.38%. There were no statistically significant differences (p>0.05). With regard to somatotype, CBF assistants were classified as mesoendomorph and FPF assistants as endo-mesomorph, in other words, CBF assistants group showed a higher predominant muscular component over fat. The difference between somatotypes was statistically significant (DDS=2.22). In reference to the speed test the CBF assistant referees were faster than the FPF referees, the difference being statistically significant between results (p=0.0001). During a match, assistant referees perform a lesser physical effort than the main referee; their performance however was similar to the main referee in the physical tests.
Souza J.A.,University Estadual Of Maring
Systems and Control Letters | Year: 2012
In this paper, the notion of complete Lyapunov function of control systems is introduced. The purpose is to determine a continuous real-valued function that describes the global structure of the system. The existence of complete Lyapunov functions is proved for certain classes of affine control systems on compact manifolds. © 2011 Elsevier B.V. All rights reserved.
Martins V.M.,Federal University of Minas Gerais |
Messias D.N.,Federal University of Minas Gerais |
Dantas N.O.,Federal University of Minas Gerais |
Neto A.M.,University Estadual Of Maring
Journal of Luminescence | Year: 2010
In this work, we have studied the optical and thermal properties of Nd-doped phosphate glass matrix. The studied samples have concentration ranging from 0.5 to 5 wt% of Nd 2O 3. Here we report the measurements of fluorescence quantum efficiency, η, obtained through the thermal lens technique using a reference sample. Also, the refractive index, n, specific heat, c p, mass density, and the thermal diffusivity and conductivity measurements were performed. The knowledge of these characteristics as a function of neodymium concentration is very important to design optical devices, especially high power solid state lasers. © 2010 Elsevier B.V. All rights reserved.
Pastor J.M.,University of Navarra |
Perez-Landazbal J.I.,University of Navarra |
Gmez-Polo C.,University of Navarra |
Recarte V.,University of Navarra |
And 6 more authors.
Applied Physics Letters | Year: 2012
The most stable form of iron oxide is Hematite (α-Fe 2O 3), which has interesting electronic, catalytic, and magnetic properties showing size dependent characteristics. At room temperature, Hematite is weakly ferromagnetic with a rhombohedral corundum structure. Upon cooling, the structure undergoes a first order spin reorientation, in which the net magnetic moment is lost. This transition is called the Morin transition. In this work, the first order Morin transition has been analyzed as a function of the temperature and applied magnetic field in Hematite nanoparticles. The magnetization was measured in the temperature range of the transformation at different applied magnetic fields to evaluate the entropy change linked to the Morin transition. The magnetic field promotes a shift of the transformation temperature. The change of entropy has been estimated on the basis of Clausius-Clapeyron type equation. © 2012 American Institute of Physics.
Hoepfner M.P.,University of Michigan |
Boas Favero C.V.,University Estadual Of Maring |
Fogler H.S.,University of Michigan
11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings | Year: 2011
Asphaltenes are defined as the petroleum fraction that precipitates with the addition of a normal alkane; however, it was only recently discovered that there is a strong time-dependency for precipitation in oil/n-alkane mixtures. It was found that at low precipitant concentrations, asphaltenes would eventually precipitate if one simply waited, sometimes up to several months. Asphaltenes were also recently found to deposit before the precipitation could be detected by optical microscopy, further revealing asphaltene instability. Small-angle neutron scattering (SANS) was selected as a technique that could detect subtle changes in the asphaltene size and shape once a precipitant is added. Optical microscopy requires asphaltene aggregates to grow to ~0.5 μm before the precipitation can be detected. With SANS, changes in size or shape of a few nanometers can easily be measured. Experiments were performed on the CG-2 SANS instrument at Oak Ridge National Laboratory. Oil samples were diluted with heptane at various concentrations, and were allowed to mix for times ranging from less than 1 day and up to 6 months prior to performing the scattering experiments. The goal was to investigate the asphaltene stability over a wide range of precipitant concentrations and to monitor the aggregation process over time. If asphaltenes are found to be stable at low enough precipitant concentrations, the scattering results will indicate that there is no change in the morphology of an asphaltene nanoaggregate and that any change in the scattering would be due to dilution and scattering contrast effects. It was found that asphaltenes grew in size with the small addition of precipitant, as low as 10 vol. % heptane, for an oil with an instantaneous onset condition of 40 vol. % heptane. The asphaltenes continued to grow over time. Attempting to detect this instability with optical microscopy may not be possible due to the long-term precipitation/aggregation kinetics. Experiments were also performed on a second oil and a model oil consisting of 3 wt. % asphaltenes dispersed in d8-toluene. Additionally, the asphaltenes remaining in solution were much smaller than those that precipitated, suggesting that the largest of the asphaltene nanoaggregates are the most unstable and precipitate first. These findings question whether asphaltenes are ever truly stable and a small fraction of asphaltenes may precipitate with any slight perturbation. Future models to understand asphaltene stability need to consider this effect and the assumption of equilibrium may not be valid for a wide range of conditions.