Hausdorff dimension in RR-analytic profinite groups

We study the Hausdorff dimension of R-analytic subgroups in an R-analytic profinite group, where R is a pro-p ring whose asso- ciated graded ring is an integral domain. In particular, we prove that the set of such Hausdorff dimensions is a finite subset of the rational numbers.Comment: 7 page

Air Pollution Convergente and Economic Growth across European Countries

This paper analyses the role of macroeconomic performance in shaping the evolution of air pollutants in a panel of European countries from 1990 to 2000. The analysis is addressed in connection with EU environmental regulation and taking into account macroeconomic performance. We start by documenting the patterns of crosscountry differences among different pollutants. We then interpret these differences within a neoclassical growth model with pollution. Three main pieces of evidence are presented. First, we analyze the existence of convergence of pollution levels within European economies. Second, we rank countries according to its performance in terms of emissions and growth. Third, we evaluate the evolution of emissions in terms of the targets signed for 2010.Economic Growth, Air Pollution, Convergence

Initial Teacher Training and Education for Citizenship: Social Representations, Design of Classes and Teaching Practices

El presente trabajo muestra los hallazgos de una investigación cualitativa sobre las representaciones sociales que acerca de la educación para la ciudadanía tenían un grupo de profesores de ciencias sociales en formación (que cursaban el último año al tiempo en que realizaban el prácticum). El trabajo desveló las representaciones, indagó en la manera en que se reflejaban en el diseño de las clases y de las prácticas de enseñanza. La investigación fue realizada con 50 estudiantes en una titulación de una universidad pública de Colombia. En el proceso se realizó una propuesta de formación en temas de educación para la ciudadanía. La investigación muestra que las representaciones sociales son heterogéneas y que se reflejan de manera diferente en el diseño y las prácticas de enseñanza, y muestra en algunos casos la existencia de contradicciones, continuidades y rupturas. El artículo finaliza haciendo algunas sugerencias y proponiendo ideas para el debateThis paper presents the findings of a qualitative research on social representations about citizenship education in a group of students teacher of social studies who were in the final year of training, time in doing the practicum. The work revealed the representations and tracked as they are reflected in the design of the classes and teaching practices. The research was conducted with 50 students in a degree in a public university in Colombia. In the process there was a proposal for training in education for citizenship. Research shows that social representations are heterogeneous and reflected differently in the design and teaching practices, and in some cases show the existence of contradictions, continuities and ruptures. The article concludes with some suggestions and proposing ideas for discussio

Modular analysis of the control of flagellar Ca2+-spike trains produced by CatSper and CaV channels in sea urchin sperm

Intracellular calcium ([Ca2+]i) is a basic and ubiquitous cellular signal controlling a wide variety of biological processes. A remarkable example is the steering of sea urchin spermatozoa towards the conspecific egg by a spatially and temporally orchestrated series of [Ca2+]i spikes. Although this process has been an experimental paradigm for reproduction and sperm chemotaxis studies, the composition and regulation of the signalling network underlying the cytosolic calcium fluctuations are hitherto not fully understood. Here, we used a differential equations model of the signalling network to assess which set of channels can explain the characteristic envelope and temporal organisation of the [Ca2+]i-spike trains. The signalling network comprises an initial membrane hyperpolarisation produced by an Upstream module triggered by the egg-released chemoattractant peptide, via receptor activation, cGMP synthesis and decay. Followed by downstream modules leading to intraflagellar pH (pHi), voltage and [Ca2+]i fluctuations. The Upstream module outputs were fitted to kinetic data on cGMP activity and early membrane potential changes measured in bulk cell populations. Two candidate modules featuring voltage-dependent Ca2+-channels link these outputs to the downstream dynamics and can independently explain the typical decaying envelope and the progressive spacing of the spikes. In the first module, [Ca2+]i-spike trains require the concerted action of a classical CaV-like channel and a potassium channel, BK (Slo1), whereas the second module relies on pHi-dependent CatSper dynamics articulated with voltage-dependent neutral sodium-proton exchanger (NHE). We analysed the dynamics of these two modules alone and in mixed scenarios. We show that the [Ca2+]i dynamics observed experimentally after sustained alkalinisation can be reproduced by a model featuring the CatSper and NHE module but not by those including the pH-independent CaV and BK module or proportionate mixed scenarios. We conclude in favour of the module containing CatSper and NHE and highlight experimentally testable predictions that would corroborate this conclusion

How the values of travel time change when a panel data around a new tram implementation is used

Using a dataset with transport choices of the same set of individuals (college students from University of La Laguna), we built a novel three waves panel data around a tramline implementation in the Santa Cruz-La Laguna corridor in Tenerife, Spain. The first two waves were conducted in 2007, just before the tram implementation. They collect information about Revealed Preferences (RP) of actual transport mode choices (car, bus and walk) and about Stated Preferences (SP) in a simulated scenario considering a hypothetical binary choice between the tram and the transport mode currently chosen by the students. The third wave gathers information about RP in 2009, two years after the tram started operating. With this information, we estimate several multinomial logit models and panel mixed logit models with error components. The aim of this paper is to evaluate how the estimation of the Values of Travel Time Savings (VTTS) changes when comparing the results obtained with models that only consider information before or after the tram implementation with that obtained with a panel data approach using the three waves simultaneously (RP/SP in 2007 and RP in 2009). We obtain a better statistical fit to data and, according to our study context, more reasonable VTTS using a panel data approach combining before and after information and both revealed and stated preferences. Our results suggest that when a new transport mode is implemented, the VTTS obtained with models than only consider prior or later periods of time can be underestimated and hence lead to wrong valuations of the benefits associated with the new alternative, even when stated preferences are used to anticipate the change in the transport system