The single-electron transport in a three-ion magnetic molecule modulated by a transverse field

We study single-electron transport in a three-ion molecule with strong uniaxial anisotropy and in the presence of a transverse magnetic field. Two magnetic ions are connected to each other through a third, nonmagnetic ion. The magnetic ions are coupled to ideal metallic leads and a back gate voltage is applied to the molecule, forming a field-effect transistor. The microscopic Hamiltonian describing this system includes inter-ion hopping, on-site repulsions, and magnetic anisotropies. For a range of values of the parameters of the Hamiltonian, we obtain an energy spectrum similar to that of single-molecule magnets in the giant-spin approximation where the two states with maximum spin projection along the uniaxial anisotropy axis are well separated from other states. In addition, upon applying an external in-plane magnetic field, the energy gap between the ground and first excited states of the molecule oscillates, going to zero at certain special values of the field, in analogy to the diabolical points resulting from Berry phase interference in the giant spin model. Thus, our microscopic model provides the same phenomenological behavior expected from the giant spin model of a single-molecule magnet but with direct access to the internal structure of the molecule, thus making it more appropriate for realistic electronic transport studies. To illustrate this point, the nonlinear electronic transport in the sequential tunneling regime is evaluated for values of the field near these degeneracy points. We show that the existence of these points has a clear signature in the I-V characteristics of the molecule, most notably the modulation of excitation lines in the differential conductance.Comment: 10 pages, 13 figure

Explaining computer predictions with augmented appraisal degrees

An augmented appraisal degree (AAD) has been conceived as a mathematical representation of the connotative meaning in an experience-based evaluation, which depends on a particular experience or knowledge. Aiming to improve the interpretability of computer predictions, we explore the use of AADs to represent evaluations that are per- formed by a machine to predict the class of a particular object. Hence, we propose a novel method whereby predictions made using a support vector machine classification process are augmented through AADs. An illustra- tive example, in which the classes of handwritten digits are predicted, shows how the augmentation of such predictions can favor their interpretability

Análisis territorial de la Romanización en las Sierras de Aroche y Aracena

Presentamos algunas consideraciones sobre el desarrollo del poblamiento durante la Romanización en las Sierras de Aroche y Aracena, basadas en un análisis empírico, a través de la metodología que nos brinda la Arqueología Territorial. Como resultado de este trabajo se cuenta con un registro de más amplitud, que viene a complementar las localizaciones, actualmente conocidas así como ha supuesto una revisión y sistematización de los yacimientos en relación al territorio que permita un análisis global._______________________We show here some considerations about the development of settlement during the Roman era in the "Sierras de Aroche-Aracena" area, based on an empirical analysis, through the methodology which Regional Archaeology offers us. As a result of this work, we have built up a wider database, which complements the presently known localisations and at the same time it has revised and systematised the archaeological deposits with respect to this area which allows us a global analysis

Primordial black hole evolution in two-fluid cosmology

Several processes in the early universe might lead to the formation of primordial black holes with different masses. These black holes would interact with the cosmic plasma through accretion and emission processes. Such interactions might have affected the dynamics of the universe and generated a considerable amount of entropy. In this paper we investigate the effects of the presence of primordial black holes on the evolution of the early universe. We adopt a two-fluid cosmological model with radiation and a primordial black hole gas. The latter is modelled with different initial mass functions taking into account the available constraints over the initial primordial black hole abundances. We find that certain populations with narrow initial mass functions are capable to produce significant changes in the scale factor and the entropy.Comment: 8 pages, 7 figures. Modified to match the published versio

Primordial black hole evolution in two-fluid cosmology

Several processes in the early Universe might lead to the formation of primordial black holes with different masses. These black holes would interact with the cosmic plasma through accretion and emission processes. Such interactions might have affected the dynamics of the Universe and generated a considerable amount of entropy. In this paper, we investigate the effects of the presence of primordial black holes on the evolution of the early Universe. We adopt a two-fluid cosmological model with radiation and a primordial black hole gas. The latter is modelled with different initial mass functions taking into account the available constraints over the initial primordial black hole abundances.We find that certain populations with narrow initial mass functions are capable to produce significant changes in the scalefactor and the entropy.Fil: Gutiérrez, Eduardo Mario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Vieyro, Florencia Laura. Universidad de Barcelona; España. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentin

The Medieval Settlement in the Western Sierra Morena (Spain-Portugal)

We analyze the medieval settlement in a rural and peripheral territory that was part of Garb- al-Andalus Sierra Morena Occidental The study is carried out on the basis of the archaeological record and covers from the late Roman period to the Christian conquest but especially the Andalusian period A historical stage that had little knowledg