Jornada de Ciencias Básicas Médicas. Girón 2006

A los lectores de la Revista Habanera de Ciencias Médicas:  Con motivo de celebrarse en la Ciudad de La Habana, del 21 al 23 de diciembre del 2006, la Jornada Nacional de Ciencias Médicas Girón 2006, incluimos en este Número resúmenes de trabajos presentados, analizados y discutidos en este Evento

Adolescents’ risky decision-making activates neural networks related to social cognition and cognitive control processes

This study examines by means of functional magnetic resonance imaging the neural mechanisms underlying adolescents’ risk decision-making in social contexts. We hypothesize that the social context could engage brain regions associated with social cognition processes and developmental changes are also expected. Sixty participants (adolescents: 17–18, and young adults: 21–22 years old) read narratives describing typical situations of decision-making in the presence of peers. They were asked to make choices in risky situations (e.g., taking or refusing a drug) or ambiguous situations (e.g., eating a hamburger or a hotdog). Risky as compared to ambiguous scenarios activated bilateral temporoparietal junction (TPJ), bilateral middle temporal gyrus (MTG), right medial prefrontal cortex, and the precuneus bilaterally; i.e., brain regions related to social cognition processes, such as self-reflection and theory of mind (ToM). In addition, brain structures related to cognitive control were active [right anterior cingulate cortex (ACC), bilateral dorsolateral prefrontal cortex (DLPFC), bilateral orbitofrontal cortex], whereas no significant clusters were obtained in the reward system (ventral striatum). Choosing the dangerous option involved a further activation of control areas (ACC) and emotional and social cognition areas (temporal pole). Adolescents employed more neural resources than young adults in the right DLPFC and the right TPJ in risk situations. When choosing the dangerous option, young adults showed a further engagement in ToM related regions (bilateral MTG) and in motor control regions related to the planning of actions (pre-supplementary motor area). Finally, the right insula and the right superior temporal gyrus were more activated in women than in men, suggesting more emotional involvement and more intensive modeling of the others’ perspective in the risky conditions. These findings call for more comprehensive developmental accounts of decision-making in social contexts that incorporate the role of emotional and social cognition processes

Raúl Roa y las batallas en la OEA. Un análisis de su comportamiento político desde una Ciencia Política con enfoque Sur

Through several of the epic battles waged in the OAS, the contributions of Raúl Roa are examined from the perspective of Political Science. From his youth, Roa was a professional with a vast culture and solid knowledge of history, philosophy and the social sciences in general. His status as an outstanding university professor validates the broad theoretical mastery that he had on each of these specialties. His performance as Minister of Foreign Affairs after the revolutionary triumph allowed him to carry out analyses based on these spheres in the international forums in which he intervened on behalf of his people. Roa, a Marxist of the highest caliber, endowed this practice the creative spirit that was nourished by the richness of the nations of the South, such as ours.Se examinan, a través de varias de las épicas batallas libradas en la OEA, las contribuciones de Raúl Roa García desde la perspectiva de la Ciencia Política. Roa, desde su juventud, fue un profesional de vasta cultura y sólidos conocimientos de la historia, la filosofía y las ciencias sociales en general. Su condición de destacado docente universitario valida el amplio dominio que poseía, desde el punto de vista teórico, sobre cada una de estas especialidades. Su desempeño como Ministro de Relaciones Exteriores, tras eltriunfo revolucionario, le permitió realizar análisis desde la apoyatura de estas esferas en los foros internacionales en los que intervino, a nombre de su pueblo. Roa, marxista de altos quilates, desde la más acabada organicidad, le insufló a dicha práctica el espíritu creador, que se nutría con las riquezas de las naciones del Sur como la nuestra

The RoPES project with HARPS and HARPS-N. I. A system of super-Earths orbiting the moderately active K-dwarf HD 176986

We report the discovery of a system of two super-Earths orbiting the moderately active K-dwarf HD 176986. This work is part of the RoPES RV program of G- and K-type stars, which combines radial velocities (RVs) from the HARPS and HARPS-N spectrographs to search for short-period terrestrial planets. HD 176986 b and c are super-Earth planets with masses of 5.74 and 9.18 M$_{\oplus}$, orbital periods of 6.49 and 16.82 days, and distances of 0.063 and 0.119 AU in orbits that are consistent with circular. The host star is a K2.5 dwarf, and despite its modest level of chromospheric activity (log(R'hk) = - 4.90 +- 0.04), it shows a complex activity pattern. Along with the discovery of the planets, we study the magnetic cycle and rotation of the star. HD 176986 proves to be suitable for testing the available RV analysis technique and further our understanding of stellar activity.Comment: 21 pages, 24 figures, 7 table

Unimodularity and invariant volume forms for Hamiltonian dynamics on Poisson-Lie groups

In this paper, we discuss several relations between the existence of invariant volume forms for Hamiltonian systems on Poisson-Lie groups and the unimodularity of the Poisson-Lie structure. In particular, we prove that Hamiltonian vector fields on a Lie group endowed with a unimodular Poisson-Lie structure preserve a multiple of any left-invariant volume on the group. Conversely, we also prove that if there exists a Hamiltonian function such that the identity element of the Lie group is a nondegenerate singularity and the associated Hamiltonian vector field preserves a volume form, then the Poisson-Lie structure is necessarily unimodular. Furthermore, we illustrate our theory with different interesting examples, both on semisimple and unimodular Poisson-Lie groups.Comment: 17 page