The ρ\rho-Geminid meteoroid stream: orbits, spectroscopic data and implications for its parent body

By using an array of high-sensitivity CCD video devices and spectrographs, the activity of meteor events from the poorly-known $\rho$-Geminid meteoroid stream has been monitored during January 2012 and 2013. As a result of this research, the atmospheric trajectory and radiant position of 10 of these events has been obtained, but also the orbital parameters of the progenitor meteoroids and the tensile strength of these particles. The data reveal that the progenitor of this stream must be a comet. In addition, the emission spectra produced by three $\rho$-Geminid meteors were also recorded. These are the first $\rho$-Geminid spectra discussed in the scientific literature, and have provided clues about the chemical nature of these meteoroids and their parent body.Comment: Accepted for publication on Monthly Notices of the Royal Astronomical Society on Jan. 20, 201

Physical Education Classes as a Precursor to the Mediterranean Diet and the Practice of Physical Activity

Physical activity and a healthy, balanced diet are remaining unresolved issues among young people. According to the World Health Organization, young people do not get enough exercise during the week, and physical education classes are the best way to promote healthy habits. This study aims to analyze how the role of the teacher influences the frustration of psychological needs, coping strategies, motivation, and the adoption of healthy eating habits through the Mediterranean diet and the regular practice of physical activity. The study involved 1031 boys and 910 girls between the ages of 13 and 18. To explain the relationships between the different variables included in this study, a model of structural equations has been developed. The results showed that autonomy support negatively predicted the frustration of four psychological needs. The failure to meet four psychological needs negatively predicted resilience. Likewise, resilience positively predicted autonomous motivation, and this positively predicted the Mediterranean diet and the practice of physical activity. Thus, the results obtained in the present study are in line with those of various studies wherein physical education classes were seen to help consolidate healthy living habits

Density Functional approach to Nonlinear Rheology

We present a density functional based closure of the pair Smoluchowski equation for Brownian particles under shear flow. Given an equilibrium free energy functional as input the theory provides first-principles predictions for the flow-distorted pair correlation function and associated rheological quantities over a wide range of volume fractions and flow rates. Taking two-dimensional hard-disks under shear flow as an illustrative model we calculate the pair correlation function, viscosity and normal stress difference under both steady and start-up shear

Representation of non-semibounded quadratic forms and orthogonal additivity

In this article we give a representation theorem for non-semibounded Hermitean quadratic forms in terms of a (non-semibounded) self-adjoint operator. The main assumptions are closability of the Hermitean quadratic form, the direct integral structure of the underlying Hilbert space and orthogonal additivity. We apply this result to several examples, including the position operator in quantum mechanics and quadratic forms invariant under a unitary representation of a separable locally compact group. The case of invariance under a compact group is also discussed in detail

Constant rate thermal analysis for thermal stability studies of polymers

This paper explores the relationship between the shapes of temperature-time curves obtained from experimental data recorded by means of constant rate thermal analysis (CRTA) and the kinetic model followed by the thermal degradation reaction. A detailed shape analysis of CRTA curves has been performed as a function of the most common kinetic models. The analysis has been validated with simulated data, and with experimental data recorded from the thermal degradation of polytetrafluoroethylene (PTFE), poly(1,4-butylene terephthalate) (PBT), polyethylene (PE) and poly(vinyl chloride) (PVC). The resulting temperature-time profiles indicate that the studied polymers decompose through phase boundary, random scission, diffusion and nucleation mechanisms respectively. The results here presented demonstrate that the strong dependence of the temperature-time profile on the reaction mechanism would allow the real kinetic model obeyed by a reaction to be discerned from a single CRTA curve.Junta de Andalucía TEP-03002Ministerio de Ciencia e Innovación MAT 2008-06619/MA

No More Bricks in the Wall: Adopting Healthy Lifestyles through Physical Education Classes

Despite the multiple benefits associated with practicing physical activity regularly, less than 20% of the population do it on a daily basis. Physical education classes could contribute, during childhood and adolescence, to consolidating adherence to healthy lifestyle habits. The present study involved 606 secondary school students between the ages of 13 and 19. We analysed the relationships between the perception of psychological control and support for autonomy, the satisfaction and frustration of psychological needs, mind-wandering and mindfulness, positive and negative emotions, motivation towards physical education classes, physical activity and the intention to be physically active—all through a structural equation model, which presented acceptable goodness-of-fit indices. The results showed that students who feel more autonomous see that their psychological needs are met and feel emotionally positive; this will result in the development of autonomous motivation towards physical education classes and physical activity that, in turn, could lead to a greater intention to be physically active