Ion heating in transitions to CERC in the stellarator TJ-II

In TJ-II stellarator plasmas, in the electron cyclotron heating regime, an increase in the ion temperature is observed, synchronized with that of the electron temperature, during the transition to the core electron-root confinement (CERC) regime. This rise in ion temperature should be attributed to the joint action of the electron–ion energy transfer (which changes slightly during the CERC formation) and an enhancement of the ion confinement. This improvement must be related to the increase in the positive electric field in the core region. In this paper, we confirm this hypothesis by estimating the ion collisional transport in TJ-II under the physical conditions established before and after the transition to CERC. We calculate a large number of ion orbits in the guiding-centre approximation considering the collisions with a background plasma composed of electrons and ions. The ion temperature profile and the thermal flux are calculated in a self-consistent way, so that the change in the ion heat transport can be assessed.

Representaciones y medidas de la desigualdad. Una reflexión teórico-metodológica

La preocupación por los procesos de estratificación social es una de las claves de la arquitectura de las teorías sociológicas clásicas. Hoy disponemos de metodologías sofisticadas para el análisis empírico de la desigualdad, pero rara vez desembocan en explicaciones causales ambiciosas de la morfología social. La desigualdad desempeña un papel crucial como variable independiente en la explicación de una amplia gama de fenómenos sociales que van desde la experiencia subjetiva postmoderna hasta graves conflictos relacionados con la división internacional del trabajo. Este artículo analiza las características que deberían tener los indicadores de la desigualdad capaces de nutrir las teorías de largo alcance, indicando las limitaciones de algunos de los indicadores más utilizados al día de hoy y sacando a la luz algunas propuestas intuitivas de conceptualización y representación de la estratificación social. En concreto, se valorará la contraposición entre salarios y patrimonio, la escala temporal en la que se analizan los indicadores y se planteará la utilidad de algunos métodos de representación tales como el desfile de los salarios (Income parade).

Synchronization of Heteroclinic Circuits Through Learning in Chains of Neural Motifs

The synchronization of oscillatory activity in networks of neural networks is usually implemented through coupling the state variables describing neuronal dynamics. In this study we discuss another but complementary mechanism based on a learning process with memory. A driver network motif, acting as a teacher, exhibits winner-less competition (WLC) dynamics, while a driven motif, a learner, tunes its internal couplings according to the oscillations observed in the teacher. We show that under appropriate training the learner motif can dynamically copy the coupling pattern of the teacher and thus synchronize oscillations with the teacher. Then, we demonstrate that the replication of the WLC dynamics occurs for intermediate memory lengths only. In a unidirectional chain of N motifs coupled through teacher-learner paradigm the time interval required for pattern replication grows linearly with the chain size, hence the learning process does not blow up and at the end we observe phase synchronized oscillations along the chain. We also show that in a learning chain closed into a ring the network motifs come to a consensus, i.e. to a state with the same connectivity pattern corresponding to the mean initial pattern averaged over all network motifs.