Browsing by Author "Costa, Pedro"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
- Exploring the Relationship Between Wall Drop Punt Kick and Catch (Tripela Sports) Performance and Manipulative Tests of the Motor Competence Assessment Battery in Early AdolescentsPublication . Matos, Rui; Amaro, Nuno; Lopes, Nataniel; Costa, Pedro; Jacinto, Miguel; Rodrigues, Filipe; Antunes, Raul; Coelho, Luís; Ibáñez, Sergio J.; Estevan, Isaac; Monteiro, DiogoOur aim in this study was to analyze associations between the two manipulative tests of the Motor Competence Assessment (MCA) battery and the Wall Drop Punt Kick & Catch (WDPK&C) motor task. One hundred and twelve early adolescents (60 boys; 52 girls; M age = 12.67, SD = 1.78 years) participated. Overall, strong correlations were found between the WDPK&C and the MCA manipulative tests, either separately (r = .802 for kicking, r = .762 for throwing) or collectively (r = .835). In boys, correlations between WDPK&C and MCA kicking (r = .722) and MCA throwing (r = .754) were similar. In girls, MCA kicking was more closely related to WDPK&C performance (r = .612) than MCA throwing (r = .330). These results reinforce the possible use of WDPK&C as a gross manipulative coordination test, either by itself or when integrated into motor competence batteries.
- Phase Diagram and Critical Properties within an Effective Model of QCD: The Nambu–Jona-Lasinio Model Coupled to the Polyakov LoopPublication . Costa, Pedro; Ruivo, Maria C.; Sousa, Célia A. de; Hansen, HubertWe investigate the phase diagram of the so-called Polyakov-Nambu-Jona-Lasinio model at finite temperature and non-zero chemical potential with three quark flavors. Chiral and deconfinement phase transitions are discussed and the relevant order-like parameters are analyzed. The results are compared with simple thermodynamic expectations and lattice data. We present the phase diagram in the (T, μB) plane, paying special attention to the critical end point: as the strength of the flavor-mixing interaction becomes weaker, the critical end point moves to low temperatures and can even disappear.
- Polymer Melt Stability Monitoring in Injection Moulding Using LSTM-Based Time-Series ModelsPublication . Costa, Pedro; Mendes, Sílvio Priem; Loureiro, PauloThis work presents a data-driven framework for early detection of polymer melt instability in industrial injection moulding using Long Short-Term Memory (LSTM) time-series models. The study uses six months of continuous production data comprising approximately 280,000 injection cycles collected from a fully operational thermoplastic injection line. Because melt behaviour evolves gradually and conventional threshold-based monitoring often fails to capture these transitions, the proposed approach models temporal patterns in torque, pressure, temperature, and rheology to identify drift conditions that precede quality degradation. A physically informed labelling strategy enables supervised learning even with sparse defect annotations by defining volatile zones as short time windows preceding operator-identified non-conforming parts, allowing the model to recognise instability windows minutes before defects emerge. The framework is designed for deployment on standard machine signals without requiring additional sensors, supporting proactive process adjustments, improved stability, and reduced scrap in injection moulding environments. These findings demonstrate the potential of temporal deep-learning models to enhance real-time monitoring and contribute to more robust and adaptive manufacturing operations.
- Scalar-pseudoscalar meson behavior and restoration of symmetries in SU(3) Polyakov–Nambu–Jona-Lasinio modelPublication . Costa, P.; Ruivo, M.C.; Sousa, C. A. de; Hansen, H.; Alberico, W.M.; Costa, PedroThe modification of mesonic observables in a hot medium is analyzed as a tool to investigate the restoration of chiral and axial symmetries in the context of the Polyakov-loop extended Nambu-Jona-Lasinio model. The results of the extended model lead to the conclusion that the effects of the Polyakov loop are fundamental for reproducing lattice findings. In particular, the partial restoration of the chiral symmetry is faster in the Polyakov-Nambu-Jona-Lasinio model than in the Nambu-Jona-Lasinio one, and it is responsible for several effects: the meson-quark coupling constants show a remarkable difference in both models, there is a faster tendency to recover the Okubo-Zweig-Iizuka rule, and finally the topological susceptibility nicely reproduces the lattice results around T/Tc 1.0.
- The QCD critical end point in the PNJL modelPublication . Costa, P.; Sousa, C. A. de; Ruivo, M. C.; Hansen, H.; Costa, PedroWe investigate the role played by the Polyakov loop in the dynamics of the chiral phase transition in the framework of the so-called PNJL model in the SU(2) sector. We present the phase diagram where the inclusion of the Polyakov loop moves the critical points to higher temperatures, compared with the NJL model results. The critical properties of physical observables, such as the baryon number susceptibility and the specific heat, are analyzed in the vicinity of the critical end point, with special focus on their critical exponents. The results with the PNJL model are closer to lattice results and we also recover the universal behavior of the critical exponents of both the baryon susceptibility and the specific heat.
- The Reliability of the Wall Drop Punt Kick and Catch TestPublication . Matos, Rui; Amaro, Nuno; Lopes, Nataniel; Costa, Pedro; Jacinto, Miguel; Rodrigues, Filipe; Antunes, Raul; Coelho, Luís Pedro Inácio; Ibáñez, Sergio J.; Monteiro, DiogoThis study aimed to evaluate the reliability of a manipulative eye–segmental (hand and foot) coordination task, namely the Wall Drop Punt Kick and Catch test (WDPK&C), over two weeks. Forty-one children and adolescents (18 boys, 23 girls) with a mean age of 10.2 (SD =1.62) years old were recruited for assessment. Subjects had 30 s to perform as many ball impacts as possible on a wall two meters away, following a drop punt kick, rebound on the wall, and catch sequence. The Intraclass Correlation Coefficient (ICC = 0.896) for unique measures, Cronbach Alpha (α = 0.945), and Lin’s Concordance Correlation Coefficient (CCC = 0.896) provide evidence of reliability considering two consecutive measurements. These results further support the reliability of the WDPK&C test in a sample of Portuguese children and adolescents. Thus, the WDPK&C test can be applied to Portuguese boy and girl children and adolescents. Forthcoming studies should test the reliability of this test across different age groups since it is intended to be a test with a wide lifespan coverage.
- What does low energy physics tell us about the zero momentum gluon propagatorPublication . Costa, Pedro; Oliveira, O.; Silva, P. J.The connection between QCD, a nonlocal Nambu–Jona-Lasinio type model and the Landau gauge gluon propagator is explored. This two point function is parameterized by a functional form which is compatible with Dyson–Schwinger and lattice QCD results. Demanding the nonlocal model to reproduce the experimental values for the pion mass, the pion decay constant, and the light quark condensate we conclude that low energy physics does not distinguish between the so-called decoupling and scaling solutions of the Dyson–Schwinger equations. This result means that, provided that the model parameters are chosen appropriately, one is free to choose any of the above scenarios. Furthermore, the nonlocal Nambu–Jona-Lasinio quark model considered here is chiral invariant and satisfies the GMOR relation at the 1% level of precision.