Metropolis-Hastings prefetching algorithms

Prefetching is a simple and general method for single-chain parallelisation of the Metropolis-Hastings algorithm based on the idea of evaluating the posterior in parallel and ahead of time. In this paper improved Metropolis-Hastings prefetching algorithms are presented and evaluated. It is shown how to use available information to make better predictions of the future states of the chain and increase the efficiency of prefetching considerably. The optimal acceptance rate for the prefetching random walk Metropolis-Hastings algorithm is obtained for a special case and it is shown to decrease in the number of processors employed. The performance of the algorithms is illustrated using a well-known macroeconomic model. Bayesian estimation of DSGE models, linearly or nonlinearly approximated, is identified as a potential area of application for prefetching methods. The generality of the proposed method, however, suggests that it could be applied in many other contexts as well.Prefetching; Metropolis-Hastings; Parallel Computing; DSGE models; Optimal acceptance rate

Pattern as an Ontological Category

The paper argues that causal systems and spatial patterns are species of the same genus, namely pattern, and that a clear view of spatial patterns throws light on some aspects of the ontological nature of causal systems. In particular, it is argued that all patterns (and systems) depend on a fiat delimitation of something which in itself is a unity without borders. Pattern realism is true

Literacy: A cultural influence on functional left-right differences in the inferior parietal cortex

The current understanding of hemispheric interaction is limited. Functional hemispheric specialization is likely to depend on both genetic and environmental factors. In the present study we investigated the importance of one factor, literacy, for the functional lateralization in the inferior parietal cortex in two independent samples of literate and illiterate subjects. The results show that the illiterate group are consistently more right-lateralized than their literate controls. In contrast, the two groups showed a similar degree of left-right differences in early speech-related regions of the superior temporal cortex. These results provide evidence suggesting that a cultural factor, literacy, influences the functional hemispheric balance in reading and verbal working memory-related regions. In a third sample, we investigated grey and white matter with voxel-based morphometry. The results showed differences between literacy groups in white matter intensities related to the mid-body region of the corpus callosum and the inferior parietal and parietotemporal regions (literate > illiterate). There were no corresponding differences in the grey matter. This suggests that the influence of literacy on brain structure related to reading and verbal working memory is affecting large-scale brain connectivity more than grey matter per se

We can do better to prevent head injuries[Editorial].

Efst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkin

(Di)lepton physics with ALICE

Physics perspectives with(di)lepton measurements with the ALICE detector at the LHC are reviewed. Special emphasis is placed on heavy flavor physics.Comment: 4 pages, 1 figure, 18th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions : Quark Matter 2005, Budapest, Hongrie, Ao\^{u}t 2005, submitted to Nuclear Physic