El contrato de alimentos a favor de tercero: particularidades de su configuración a la luz del Derecho Europeo de Contratos

La sociedad actual se enfrenta con problemas hasta ahora desconocidos que necesitan una rápida y efectiva solución. El progresivo aumento de la esperanza de vida ha dado lugar a que hoy en día nos encontremos con sociedades envejecidas y necesitadas de protección. Se habla incluso de la «cuarta edad» y de la aparición de un nuevo fenómeno demográfico denominado «envejecimiento del envejecimiento», esto es, el aumento de la población con edad superior a ochenta años. A demás, aunque la vejez no implica necesariamente enfermedad, la tasa de discapacidad crece con la edad. A lo que se debe añadir que muchas de estas personas tienen hijos discapacitados que, con toda probabilidad y debido a los avances médicos, sobrevivirán a sus ancianos padres y necesitarán medios materiales y/o personales para continuar con sus vidas. Para paliar estos problemas existe, entre otras medidas, el denominado contrato de alimentos; y especialmente útil para alcanzar este cometido resulta su configuración a favor de terceras personas. Pero su régimen jurídico cuando se celebra para beneficiar a una persona que no es parte contractual presenta importantes peculiaridades derivadas de la especial relación generada entre alimentista y alimentante. Estas particularidades serán objeto de análisis en este trabajo.

Optical control of the spin state of two Mn atoms in a quantum dot

We report on the optical spectroscopy of the spin of two magnetic atoms (Mn) embedded in an individual quantum dot interacting with a single electron, a single exciton, or a single trion. As a result of their interaction to a common entity, the Mn spins become correlated. The dynamics of this process is probed by time-resolved spectroscopy, which permits us to determine an optical orientation time in the range of a few tens of nanoseconds. In addition, we show that the energy of the collective spin states of the two Mn atoms can be tuned through the optical Stark effect induced by a resonant laser field.

Luminosity dependent accretion state change in GRO J1008–57

In a former publication, we have analyzed the transient neutron star X-ray binary GRO J1008–57 using all available RXTE-, Swift-, and Suzaku-data. As we have found, the source’s spectral components, i.e., a power-law with high exponential cutoff and a black-body, are strongly correlated with the hard X-ray flux (15–50 keV). We update the analytical description of these dependence, including a change in the photon index behaviour from a flat to a logarithmic function. The flux, where the change occurs, is consistent with the onset of the black-body emission. Thus, a change of the accretion state always occurs in GRO J1008–57 at a particular flux level.

Polarized–unpolarized ground state of small polycyclic aromatic hydrocarbons

Do polyacenes, circumacenes, periacenes, nanographenes, and graphene nanoribbons show a spin polarized ground state? In this work, we present monodeterminantal (Hartree–Fock (HF) and density functional theory (DFT) types), and multideterminantal calculations (Møller–Plesset and Coupled Cluster), for several families of unsaturated organic molecules (n-Acenes, n-Periacenes and n-Circumacenes). All HF calculations and many DFT show a spin-polarized (antiferromagnetic) ground state, in agreement with previous calculations. Nevertheless, the multideterminantal calculations, carried out with perturbative and variational wavefunctions, show that the more stable state is obtained starting from the unpolarized HF wavefunction. The trend of the stabilization of wavefunctions (polarized or unpolarized) with respect to exchange and correlation potentials, and to the number of benzene rings, has been analyzed. A study of the spin (〈Ŝ2〉) and the spin density on the carbon atoms has also been carried out.