On the interpretation of dark matter self-interactions in Abell 3827

Self-interactions of dark matter particles can potentially lead to an observable separation between the dark matter halo and the stars of a galaxy moving through a region of large dark matter density. Such a separation has recently been observed in a galaxy falling into the core of the galaxy cluster Abell 3827. We estimated the DM self-interaction cross section needed to reproduce the observed effects and find that the sensitivity of Abell 3827 has been significantly overestimated in a previous study. Our corrected estimate is $\tilde{\sigma}/m_\text{DM} \sim 3\:\text{cm}^2\:\text{g}^{-1}$ when self-interactions result in an effective drag force and $\sigma/m_\text{DM} \sim 1.5\:\text{cm}^2\:\text{g}^{-1}$ for the case of contact interactions, in some tension with previous upper bounds.Comment: 5 pages, 3 figures; v2: matches published versio

Medium modification of pion production in low energy Au+Au collisions

There is a major mismatch between the charged pion yields in Au+Au collisions at low energies calculated by various transport models and the experimental measured values from the HADES collaboration. In this work, reasonable improvements on the equation of state, in-medium modification of cross sections, and the influence of the nuclear potential for Delta resonances will be investigated in the framework of the GiBUU transport model. As a result, we demonstrate that theoretical calculations can indeed describe the charged pion yields measured by HADES for Au+Au collisions rather well, but that a mismatch then remains between calculations and data for the yields of neutral pions extracted from dileptons within the same experiment.Comment: 14 pages, 16 figure

Simulations of core formation for frequent dark matter self-interactions

We present the first $N$-body simulations that adapt the equations of smoothed particle hydrodynamics to capture the effect of dark matter self-interactions which are too frequent to be resolved explicitly. The relevant energy transfer equations are derived, the appropriate thermal conductivity is determined and the effects of different smoothing kernels are studied. We apply our framework to simulate the formation of isothermal cores in isolated dark matter haloes and determine the core growth rate as a function of the self-scattering cross section. Our approach may be combined with explicit simulations of rare scatterings in order to simulate accurately the effects of arbitrary dark matter self-interactions in future cosmological simulations.Comment: 11 pages, 6 figures; v2: matches version published in MNRA

Conditioned place preference for social interaction in rats: contribution of sensory components

A main challenge in the therapy of drug dependent individuals is to help them reactivate interest in non-drug-associated activities. We previously developed a rat experimental model based on the conditioned place preference (CPP) paradigm in which only four 15-min episodes of social interaction with a gender- and weight-matched male Sprague Dawley rat (1) reversed CPP from cocaine to social interaction despite continuing cocaine training and (2) prevented the reinstatement of cocaine CPP. In the present study, we investigated which of the sensory modalities of the composite stimulus “social interaction” contributes most to the rats' preference for it. If touch was limited by steel bars spaced at a distance of 2 cm and running across the whole length of a partitioning, CPP was still acquired, albeit to a lesser degree. If both rats were placed on the same side of a partitioning, rats did not develop CPP for social interaction. Thus, decreasing the available area for social interaction from 750 to 375 cm2 prevented the acquisition of CPP to social interaction despite the fact that animals could touch each other more intensely than through the bars of the partitioning. When touch was fully restricted by a glass screen dividing the conditioning chambers, and the only sensory modalities left were visual and olfactory cues, place preference shifted to place aversion. Overall, our findings indicate that the major rewarding sensory component of the composite stimulus “social interaction” is touch (taction)

Social interaction reward decreases p38 activation in the nucleus accumbens shell of rats

AbstractWe have previously shown that animals acquired robust conditioned place preference (CPP) to either social interaction alone or cocaine alone. Recently it has been reported that drugs of abuse abnormally activated p38, a member of mitogen-activated protein kinase family, in the nucleus accumbens. In this study, we aimed to investigate the expression of the activated form of p38 (pp38) in the nucleus accumbens shell and core of rats expressing either cocaine CPP or social interaction CPP 1 h, 2 h and 24 h after the CPP test. We hypothesized that cocaine CPP will increase pp38 in the nucleus accumbens shell/core as compared to social interaction CPP. Surprisingly, we found that 24 h after social interaction CPP, pp38 neuronal levels were decreased in the nucleus accumbens shell to the level of naïve rats. Control saline rats that received saline in both compartments of the CPP apparatus and cocaine CPP rats showed similar enhanced p38 activation as compared to naïve and social interaction CPP rats. We also found that the percentage of neurons expressing dopaminergic receptor D2R and pp38 was also decreased in the shell of the nucleus accumbens of social interaction CPP rats as compared to controls. Given the emerging role of p38 in stress/anxiety behaviors, these results suggest that (1) social interaction reward has anti-stress effects; (2) cocaine conditioning per se does not affect p38 activation and that (3) marginal stress is sufficient to induce p38 activation in the shell of the nucleus accumbens

La NTE como agente de cambio ante problemas que agobian a la sociedad civil: un estudio de caso en la comunidad de Petaquillas, Guerrero, México

Ante la realidad agobiante que padece actualmente la gran mayoría de las naciones, como es el caso de México, donde se manifiesta una crisis socioeconómica desde diversas aristas, de manera oportuna y contestataria aparece la Nueva Teoría Estratégica (NTE) como respuesta a un reclamo multitudinario que aboga por encontrar soluciones ante la inoperancia de métodos empleados en circunstancias pasadas que hoy dejan de ser efectivos frente a una complejidad social sin precedentes. Desde esta visión enfocamos el presente trabajo a través de un estudio de caso en una comunidad mexicana, Petaquillas, ubicada en la periferia de Chilpancingo, capital del estado de Guerrero, donde sus habitantes acosados por el sistema de inseguridad prevaleciente, determinado por la presencia en su territorio de bandas del narcotráfico y ante el hartazgo por la respuesta ausente de las instancias gubernamentales y las fuerzas del orden establecidas, deciden organizarse como sociedad civil para encontrar solución a los graves problemas que les acechan y niegan el derecho a lograr una convivencia social en circunstancias seguras y en paz. El diseño de esta investigación se plantea desde el paradigma cualitativo basado en el enfoque de la Nueva Teoría Estratégica con rasgos de la Teoría Fundamentada desde donde se deriva un método apropiado a aplicar en una situación compleja en la que los actores sociales de una comunidad se integran en la búsqueda de estrategias novedosas, acordes al problema situacional complejo imperante. En este proceso, como lo establece la NTE, la comunicación asume un rol fundamental como recurso constituyente de la propia estrategia que permite el empleo de tácticas viables para, mediante la integración relacional mancomunada y consciente de los actores involucrados, resolver el problema socialmente afectivo

Barrier functions and paracellular integrity in human cell culture models of the proximal respiratory unit.

International audienceAirway epithelial cells provide a barrier to the translocation of inhaled materials. Tight (TJ) and adherens junctions (AJ) play a key role in maintaining barrier functions, and are responsible for the selective transport of various substances through the paracellular pathway. In this study we compared a bronchial cell line (16HBE14o-) and primary bronchial cells (HBEC), both cocultivated with the fibroblast cell line Wi-38, with respect to their structural differentiation and their reaction to cytokine stimulation. HBEC formed a pseudostratified epithelial layer and expressed TJ and AJ proteins after 2 weeks in coculture. Mucus-producing and ciliated cells were found within 24 days. Additionally, a beating activity of the ciliated HBEC (14-19 Hz) could be detected. 16HBE14o-in coculture showed a multilayered growth without differentiation to a pseudostratified airway epithelium. Simultaneous exposure to TNF-a-and IFN-c-induced significant changes in barrier function and paracellular permeability in the cocultures of HBEC/Wi-38 but not in the 16HBE14o-/Wi-38. In summary, HBEC in coculture mimic the structure of native polarized bronchial epithelium showing basal, mucus-producing and ciliated cells. Our system provides an opportunity to examine the factors that influence barrier and mucociliary function of bronchial epithelium within a time frame of 3 weeks up to 3 months in an in vivo-like differentiated model

A versatile functional interaction between electrically silent K V subunits and K V 7 potassium channels

Voltage-gated K+ (KV) channels govern K+ ion flux across cell membranes in response to changes in membrane potential. They are formed by the assembly of four subunits, typically from the same family. Electrically silent KV channels (KVS), however, are unable to conduct currents on their own. It has been assumed that these KVS must obligatorily assemble with subunits from the KV2 family into heterotetrameric channels, thereby giving rise to currents distinct from those of homomeric KV2 channels. Herein, we show that KVS subunits indeed also modulate the activity, biophysical properties and surface expression of recombinant KV7 isoforms in a subunit-specific manner. Employing co-immunoprecipitation, and proximity labelling, we unveil the spatial coexistence of KVS and KV7 within a single protein complex. Electrophysiological experiments further indicate functional interaction and probably heterotetramer formation. Finally, single-cell transcriptomic analyses identify native cell types in which this KVS and KV7 interaction may occur. Our findings demonstrate that KV cross-family interaction is much more versatile than previously thought—possibly serving nature to shape potassium conductance to the needs of individual cell types

Differential Effects of Accumbens Core vs. Shell Lesions in a Rat Concurrent Conditioned Place Preference Paradigm for Cocaine vs. Social Interaction

A main challenge in the therapy of drug dependent individuals is to help them reactivate interest in non-drug-associated activities. Among these activities, social interaction is doubly important because treatment adherence itself depends on it. We previously developed a rat experimental model based on the conditioned place preference (CPP) paradigm in which only four 15-min episodes of social interaction with a gender- and weight-matched male conspecific (i) reversed CPP from cocaine to social interaction despite continuing cocaine training and (ii) prevented the reinstatement of cocaine CPP. In the present study, we investigated if the two subregions of the nucleus accumbens (Acb), i.e., the core (AcbC) and the shell (AcbSh), would differentially affect CPP for cocaine vs social interaction.Animals were concurrently trained for CPP pairing cocaine with one compartment and social interaction with the other (i.e., mutually exclusive stimulus presentation during training). Excitotoxic lesioning of the AcbC or the BLA shifted CPP toward social interaction, whereas AcbSh inactivation shifted CPP toward cocaine.Overall, our findings suggest that inactivation of the AcbC or the BLA is sufficient to shift CPP away from a drug of abuse toward social interaction. Lesioning the AcbSh produced the opposite effect