Measurement of t¯t cross-section in single leptonand fully hadronic channels at the LHC

The most precise measurements of top quark pairs (t¯t) production cross-section in proton-proton collisions at a centre-of-mass energy √s = 7TeV at the LHC are described for the single lepton and fully hadronic decay channels

A perturbative approach to non-linearities in the information carried by a two layer neural network

We evaluate the mutual information between the input and the output of a two layer network in the case of a noisy and non-linear analogue channel. In the case where the non-linearity is small with respect to the variability in the noise, we derive an exact expression for the contribution to the mutual information given by the non-linear term in first order of perturbation theory. Finally we show how the calculation can be simplified by means of a diagrammatic expansion. Our results suggest that the use of perturbation theories applied to neural systems might give an insight on the contribution of non-linearities to the information transmission and in general to the neuronal dynamics.Comment: Accepted as a preprint of ICTP, Triest

Stability of the replica symmetric solution for the information conveyed by by a neural network

The information that a pattern of firing in the output layer of a feedforward network of threshold-linear neurons conveys about the network's inputs is considered. A replica-symmetric solution is found to be stable for all but small amounts of noise. The region of instability depends on the contribution of the threshold and the sparseness: for distributed pattern distributions, the unstable region extends to higher noise variances than for very sparse distributions, for which it is almost nonexistant.Comment: 19 pages, LaTeX, 5 figures. Also available at http://www.mrc-bbc.ox.ac.uk/~schultz/papers.html . Submitted to Phys. Rev. E Minor change

Modelling the location of self-employed workers in urban areas

In this article, we develop an urban model for self-employment where leisure and effort at work are complementary. Our model shows that unemployment tends to be concentrated far from business districts, in contrast to employment and self-employment. The self-employed tend to live closer to workplaces than do the employed, as commuting affects productivity and thus earnings. We use the American Time Use Survey to test the model and find that employment and self-employment are negatively related to commuting, in comparison to unemployment, while self-employment is associated with shorter commutes, giving support to the theoretical background