Platelets roll on stimulated endothelium in vivo: an interaction mediated by endothelial P-selectin.

P-selectin, found in storage granules of platelets and endothelial cells, can be rapidly expressed upon stimulation. Mice lacking this membrane receptor exhibit a severe impairment of leukocyte rolling. We observed that, in addition to leukocytes, platelets were rolling in mesenteric venules of wild-type mice. To investigate the role of P-selectin in this process, resting or activated platelets from wild-type or P-selectin-deficient mice were fluorescently labeled and transfused into recipients of either genotype. Platelet-endothelial interactions were monitored by intravital microscopy. We observed rolling of either wild-type or P-selectin-deficient resting platelets on wild-type endothelium. Endothelial stimulation with the calcium ionophore A23187 increased the number of platelets rolling 4-fold. Activated P-selectin-deficient platelets behaved similarly, whereas activated wild-type platelets bound to leukocytes and were seen rolling together. Platelets of either genotype, resting or activated, interacted minimally with mutant endothelium even after A23187 treatment. The velocity of platelet rolling was 6- to 9-fold greater than that of leukocytes. Our results demonstrate that (i) platelets roll on endothelium in vivo, (ii) this interaction requires endothelial but not platelet P-selectin, and (iii) platelet rolling appears to be independent of platelet activation, indicating constitutive expression of a P-selectin ligand(s) on platelets. We have therefore observed an interesting parallel between platelets and leukocytes in that both of these blood cell types roll on stimulated vessel wall and that this process is dependent on the expression of endothelial P-selectin.

Análisis de las propuestas de reforma del sistema electoral en España

En este estudio se analiza el sistema electoral español tratando de diagnosticar las causas de su falta de proporcionalidad entre votos y escaños. Se muestra que la causa principal de ello es la pequeña magnitud de las circunscripciones en España y se desmonta el mito de la barrera legal como impedimento para acceder al Congreso, señalando que es mucho más efectiva la barrera natural que aparece al tener España un número muy elevado de circunscripciones de baja magnitud. Posteriormente se analizan las distintas propuestas de reforma del sistema electoral encaminadas a aumentar su proporcionalidad extrapolándolas de los resultados electorales de las elecciones generales de 2015. También se analizan las dificultades para sacar adelante dichas propuestas, siendo la mayor de ellas que muchas de las propuestas exigen un cambio constitucional. Sin embargo, también se señala que algunas fórmulas que no exigen cambio constitucional pueden alcanzar incluso mayor proporcionalidad. Finalmente se comparan las distintas propuestas de reforma del sistema electoral y se advierte del peligro que conlleva una proporcionalidad muy elevada. Ésta, en general, da origen a un parlamento permanentemente fragmentado y puede generar una gran inestabilidad en los gobiernos.

Electoral Systems and Ethnic Conciliation: A Structured, Focused Analysis of Vote-Pooling in Northern Ireland Elections 1998-2011

This research project examines the role of electoral system rules in affecting the extent of conciliatory behavior and cross-ethnic coalition making in Northern Ireland. It focuses on the role of the Single Transferable Vote (STV) electoral system in shaping party and voter incentives in a post-conflict divided society. The research uses a structured, focused comparison of the four electoral cycles since the Belfast Agreement of 1998. This enables a systematic examination of each electoral cycle using a common set of criteria focused on conciliation and cross-ethnic coalition making. Whilst preference voting is assumed to benefit moderate candidates, in Northern Ireland centrist and multi-ethnic parties outside of the dominant ethnic communities have received little electoral success. In Northern Ireland the primary effect of STV has not been to encourage inter-communal voting but to facilitate intra-community and intra-party moderation. STV has encouraged the moderation of the historically extreme political parties in each of the ethnic bloc. Patterns across electoral cycles suggest that party elites from the Democratic Unionist Party (DUP) and Sinn Fein have moderated their policy positions due to the electoral system rules. Therefore they have pursued lower-preference votes from within their ethnic bloc but in doing so have marginalized parties of a multi-ethnic or non-ethnic orientation.

El movimiento #YoSoy132 y su intervención en el proceso electoral del 2012 en México

El movimiento mexicano #YoSoy132 ha supuesto un desafío para el sistema político mexicano y de esa misma manera ha sido abordado en este trabajo de investigación. Siendo el primer movimiento social que tiene como base la dinámica de la comunicación y redes digitales en México, ha presentado una serie de características estructurales que rompieron con las concepciones y los paradigmas preexistentes sobre movilización y participación ciudadana. México ha vivido desde hace 18 años1 un proceso de cambio acelerado en su sistema político. A la par, un cambio cultural se gestó a favor de una ciudadanía con un rol cada vez más significativo en el proceso político del país. Con la llegada del nuevo siglo y la emergencia de una conciencia ciudadana, más comprometida y activa, proliferan también las redes sociales digitales, que proporcionaban las bases para favorecer e impulsar la participación ciudadana en las diversas esferas de la vida pública del país. En este contexto surge el movimiento social #YoSoy132, en el marco de una campaña electoral protagonizada por el candidato del PRI, Enrique Peña Nieto y el oligopolio televisivo, quienes, en una suma de poder, habían edificado sobre la desilusión social, su estrategia para recuperar la presidencia de la república y la mayoría en el Congreso Federal; y que al mismo tiempo, se conjugaba con un contexto internacional protagonizado por movilizaciones y revueltas sociales juveniles en distintas partes del mundo, potenciadas sobre todo por el uso del Internet y las redes sociales...

Crisis política y juventud en España: el declive del bipartidismo electoral

This paper shows the increasing trend of Spanish young people towards non-conventional mechanisms of political expression, in a crisis context which has reduced its reliance on traditional political actors. As an alternative to bipartisanship, political participation moves towards increased interest and attention to new players, such as emergent political parties. Using a covariance structural model, factors such as political activism, awareness and understanding of country problems, and trust in the political system, are explored in order to explain an electoral behavior that is undergoing deep changes.

Party Members as an Electoral Linking Mechanism

While party membership figures are clearly in decline in several Western countries, different interpretations have been offered on the likely consequences of this trend. Some authors stress that members have lost most of their importance for political parties that increasingly rely on professionalized campaign techniques. Other scholars have expressed concern about the decline of party membership. They emphasize the fact that party members continue to function as an important linkage mechanism providing a structural alignment between the party and society (and thus also to potential voters). By means of an election forecasting model for Belgium, we test whether party membership figures still can be related to election results. Results show that party membership has a strong effect on election results, and furthermore, that this relation does not weaken during the period under investigation (1981-2010). The analysis also demonstrates that forecasting models can also be used in a complex multiparty system like Belgium.