The impact of sloshing on the intra-group medium and old radio lobe of NGC 5044

We present temperature and abundance maps of the central 125 kpc of the NGC 5044 galaxy group, based an a deep XMM-Newton observation. The abundance map reveals an asymmetrical abundance structure, with the centroid of the highest abundance gas offset ~22 kpc northwest of the galaxy centre, and moderate abundances extending almost twice as far to the southeast than in any other direction. The abundance distribution is closely correlated with two previously-identified cold fronts and an arc--shaped region of surface brightness excess, and it appears that sloshing, induced by a previous tidal encounter, has produced both the abundance and surface brightness features. Sloshing dominates the uplift of heavy elements from the group core on large scales, and we estimate that the southeast extension (the tail of the sloshing spiral) contains at least 1.2x10^5 solar masses more iron than would be expected of gas at its radius. Placing limits on the age of the encounter we find that if, as previously suggested, the disturbed spiral galaxy NGC 5054 was the perturber, it must have been moving supersonically when it transited the group core. We also examine the spectral properties of emission from the old, detached radio lobe southeast of NGC 5044, and find that they are consistent with a purely thermal origin, ruling out this structure as a significant source of spectrally hard inverse-Compton emission.Comment: 10 pages, 8 figures, 2 tables, accepted for publication in MNRAS; updated references and fixed typos identified at proof stag

Improving the quality of the personalized electronic program guide

As Digital TV subscribers are offered more and more channels, it is becoming increasingly difficult for them to locate the right programme information at the right time. The personalized Electronic Programme Guide (pEPG) is one solution to this problem; it leverages artificial intelligence and user profiling techniques to learn about the viewing preferences of individual users in order to compile personalized viewing guides that fit their individual preferences. Very often the limited availability of profiling information is a key limiting factor in such personalized recommender systems. For example, it is well known that collaborative filtering approaches suffer significantly from the sparsity problem, which exists because the expected item-overlap between profiles is usually very low. In this article we address the sparsity problem in the Digital TV domain. We propose the use of data mining techniques as a way of supplementing meagre ratings-based profile knowledge with additional item-similarity knowledge that can be automatically discovered by mining user profiles. We argue that this new similarity knowledge can significantly enhance the performance of a recommender system in even the sparsest of profile spaces. Moreover, we provide an extensive evaluation of our approach using two large-scale, state-of-the-art online systems—PTVPlus, a personalized TV listings portal and Físchlár, an online digital video library system

Quarterly Economic Commentary, Winter 2011/Spring 2012

The euro zone financial crisis remains unresolved. The euro zone economy is slipping into recession due to the impact of both the austerity measures and the effect of policy uncertainty in the euro zone on investment, consumer spending and employment. The euro zone banking system needs to be recapitalised, and account must be taken of the effect that the write‐down of Greek debt will have on this. The UK economy has been adversely affected by the euro zone crisis and is unlikely to meet its fiscal targets unless more restrictive measures are introduced, which in turn will worsen its economic performance. By contrast the US economy seems to be performing somewhat better than many had expected. Thus in the two regions that are of great importance in trade terms for Ireland – the euro zone and the UK – the country is facing weak or declining demand, while in the US, demand is growing modestly. The overall picture is weak

Quarterly Economic Commentary, Summer 2011

The international economy is in a period of great uncertainty. On both sides of the Atlantic, governments are faced with difficult choices regarding levels of debt. In the United States, this has led to the first ever downgrading of sovereign debt by a major ratings agency. In Europe, governments have agreed major changes to the mechanism for bailing out troubled eurozone countries, although financial markets are not convinced that this is enough. While this agreement has brought about improved terms for Ireland’s bailout, and thus made the road to fiscal sustainability easier, the issue of burden sharing remains to be addressed. At present the cost of the restructuring of the covered banking system has primarily been borne by Ireland, even though the benefits of this restructuring are shared throughout the eurozone