Splittings and the asymptotic topology of the lamplighter group

It is known that splittings of finitely presented groups over 2-ended groups can be characterized geometrically. We show that this characterization does not extend to all finitely generated groups. Answering a question of Kleiner we show that the Cayley graph of the lamplighter group is coarsely separated by quasi-circles.Comment: 11 page

First results on the event-by-event fluctuations and correlations in Pb-Pb collisions at sNN=2.76\sqrt{s_{NN}} = 2.76 TeV

Fluctuations of thermodynamic quantities are fundamental for the study of the QGP phase transition. Among several observables calculated on an event-by-event basis, the different measures of the charge and mean transverse momentum fluctuations are of particular interest since they are considered to be indicators of the existence and of the order of this transition as well as of the thermalization in heavy--ion collisions. In this article, we review the first results from the event-by-event physics program of the ALICE experiment at the LHC in Pb--Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV. The experimental results will be compared to previously published data and available model predictions.Comment: 4 pages, 4 figure

Cheeger constants of surfaces and isoperimetric inequalities

We show that the Cheeger constant of compact surfaces is bounded by a function of the area. We apply this to isoperimetric profiles of bounded genus non-compact surfaces, to show that if their isoperimetric profile grows faster than $\sqrt t$, then it grows at least as fast as a linear function. This generalizes a result of Gromov for simply connected surfaces. We study the isoperimetric problem in dimension 3. We show that if the filling volume function in dimension 2 is Euclidean, while in dimension 3 is sub-Euclidean and there is a $g$ such that minimizers in dimension 3 have genus at most $g$, then the filling function in dimension 3 is `almost' linear.Comment: 28 page

The Impact of Work-Related Training on Employee Earnings: Evidence from Great Britain.

Using data from the British Household Panel Survey for the years 1998-2005, this study estimates the impact of work-related training on earnings levels. Different measures for general and specific training are constructed from available information. The analysis diverges from the standard fixed effects framework for earnings determination modelling and presents evidence in support of the predictions of the standard human capital theory with regards to training sponsoring using a random effects formulation for the earnings equation suggested by Nijman and Verbeek (1992) for controlling for attrition bias in unbalanced panels

Results on angular correlations with ALICE

Angular correlations are a sensitive probe of the transport properties of the system produced in nucleus-nucleus collisions. Similar studies performed in p-Pb collisions have recently revealed intriguing features as well. In this article, we review the latest results on charged and identified particle correlations obtained with the ALICE detector at the LHC in both Pb-Pb and p-Pb events.Comment: 5 pages, 8 figure

Group splittings and asymptotic topology

It is a consequence of the theorem of Stallings on groups with many ends that splittings over finite groups are preserved by quasi-isometries. In this paper we use asymptotic topology to show that group splittings are preserved by quasi-isometries in many cases. Roughly speaking we show that splittings are preserved under quasi-isometries when the vertex groups are fundamental groups of aspherical manifolds (or more generally `coarse PD(n)-groups') and the edge groups are `smaller' than the vertex groups.Comment: 14 page