Mobile learning: benefits of augmented reality in geometry teaching

As a consequence of the technological advances and the widespread use of mobile devices to access information and communication in the last decades, mobile learning has become a spontaneous learning model, providing a more flexible and collaborative technology-based learning. Thus, mobile technologies can create new opportunities for enhancing the pupils’ learning experiences. This paper presents the development of a game to assist teaching and learning, aiming to help students acquire knowledge in the field of geometry. The game was intended to develop the following competences in primary school learners (8-10 years): a better visualization of geometric objects on a plane and in space; understanding of the properties of geometric solids; and familiarization with the vocabulary of geometry. Findings show that by using the game, students have improved around 35% the hits of correct responses to the classification and differentiation between edge, vertex and face in 3D solids.This research was supported by the Arts and Humanities Research Council Design Star CDT (AH/L503770/1), the Portuguese Foundation for Science and Technology (FCT) projects LARSyS (UID/EEA/50009/2013) and CIAC-Research Centre for Arts and Communication.info:eu-repo/semantics/publishedVersio

Optimal control of a dengue epidemic model with vaccination

We present a SIR+ASI epidemic model to describe the interaction between human and dengue fever mosquito populations. A control strategy in the form of vaccination, to decrease the number of infected individuals, is used. An optimal control approach is applied in order to find the best way to fight the disease.Comment: This is a preprint of a paper accepted for presentation at ICNAAM 2011, Halkidiki, Greece, 19-25 September 2011, and to appear in AIP Conference Proceedings, volume 138

Quark-hybrid matter in the cores of massive neutron stars

Using a nonlocal extension of the SU(3) Nambu-Jona Lasinio model, which reproduces several of the key features of Quantum Chromodynamics, we show that mixed phases of deconfined quarks and confined hadrons (quark-hybrid matter) may exist in the cores of neutron stars as massive as around 2.1 M_Sun. The radii of these objects are found to be in the canonical range of $\sim 12-13$ km. According to our study, the transition to pure quark matter does not occur in stable neutron stars, but is shifted to neutron stars which are unstable against radial oscillations. The implications of our study for the recently discovered, massive neutron star PSR J1614-2230, whose gravitational mass is $1.97 \pm 0.04 M_Sun$, are that this neutron star may contain an extended region of quark-hybrid matter at it center, but no pure quark matter.Comment: 13 pages, 3 figure

Parametric identification of the dynamics of inter-sectoral balance: modelling and forecasting

This work is devoted to modelling and identification of the dynamics of the inter-sectoral balance of a macroeconomic system. An approach to the problem of specification and identification of a weakly formalized dynamical system is developed. A matching procedure for parameters of a linear stationary Cauchy problem with a decomposition of its upshot trend and a periodic component, is proposed. Moreover, an approach for detection of significant harmonic waves, which are inherent to real macroeconomic dynamical systems, is developed.Comment: This is a preprint of a paper accepted for publication 29-March-2019 as a book chapter in 'Advances in Intelligent Systems and Computing' [https://www.springer.com/series/11156], Springe

Quark deconfinement in high-mass neutron stars

In this paper, we explore whether or not quark deconfinement may occur in high-mass neutron stars such as J1614-2230 (1.97 \pm 0.04 M_Sun) and J0348+0432 (2.01 \pm 0.04 M_Sun). Our study is based on a non-local extension of the SU(3) Nambu Jona-Lasinio (n3NJL) model with repulsive vector interactions among the quarks. This model goes beyond the frequently used local version of the Nambu Jona-Lasinio (NJL) model by accounting for several key features of QCD which are not part of the local model. Confined hadronic matter is treated in the framework of non-linear relativistic mean field theory. We find that both the local as well as the non-local NJL model predict the existence of extended regions of mixed quark-hadron (quark-hybrid) matter in high-mass neutron stars with masses of 2.1 to 2.4 M_Sun. Pure quark matter in the cores of neutron stars is obtained for certain parametrizations of the hadronic lagrangian and choices of the vector repulsion among quarks. The radii of high-mass neutron stars with quark-hybrid matter and/or pure quark matter cores in their centers are found to lie in the canonical range of 12 to 13 km.Comment: 31 pages, 17 figures, PRC accepted versio