A mathematical formalization of the parallel replica dynamics

The purpose of this article is to lay the mathematical foundations of a well known numerical approach in computational statistical physics and molecular dynamics, namely the parallel replica dynamics introduced by A.F. Voter. The aim of the approach is to efficiently generate a coarse-grained evolution (in terms of state-to-state dynamics) of a given stochastic process. The approach formally consists in concurrently considering several realizations of the stochastic process, and tracking among the realizations that which, the soonest, undergoes an important transition. Using specific properties of the dynamics generated, a computational speed-up is obtained. In the best cases, this speed-up approaches the number of realizations considered. By drawing connections with the theory of Markov processes and, in particular, exploiting the notion of quasi-stationary distribution, we provide a mathematical setting appropriate for assessing theoretically the performance of the approach, and possibly improving it

Cohomological Finiteness Conditions in Bredon Cohomology

We show that any soluble group $G$ of type Bredon-\FP_{\infty} with respect to the family of all virtually cyclic subgroups such that centralizers of infinite order elements are of type \FP_{\infty} must be virtually cyclic. To prove this, we first reduce the problem to the case of polycyclic groups and then we show that a polycyclic-by-finite group with finitely many conjugacy classes of maximal virtually cyclic subgroups is virtually cyclic. Finally we discuss refinements of this result: we only impose the property Bredon-\FP_n for some $n \leq 3$ and restrict to abelian-by-nilpotent, abelian-by-polycyclic or (nilpotent of class 2)-by-abelian groups.Comment: Corrected a mistake in Lemma 2.4 of the previous version, which had an effect on the results in Section 5 (the condition that all centralisers of infinite order elements are of type $FP_\infty$ was added

Modelling the exposure to Cronobacter sakazakii by consumption of a cocoa-milk-based beverage processed by pulsed electric fields

peer-reviewedM.C. Pina-Pérez is grateful to CSIC for providing a DOCTOR contract linked to the INNPACTO project IPT-2011-1724-060000. This study was carried out with funds from BISOSTAD project PSE-060000-2009-003, Generalitat Valenciana I+D+I emergent research groups GV/2010/064 and CYCIT project AGL2010-22206-C02-01.Infants’ exposure (Nf ) to Cronobacter sakazakii via the consumption of infant-rich-inpolyphenols cocoa-milk-based beverages (CCX-M) treated with high-intensity pulsed electric fields (PEF) was evaluated. Monte Carlo simulation enabled the prediction of the variability in C. sakazakii load in beverages at the time of consumption to be estimated. Different scenarios (initial contamination levels; PEF treatment conditions; and time-temperature combinations of CCX-M beverages storage after treatment) were simulated. Cocoa addition and PEF treatment resulted in the most influential input factors to control bacterial final load. Cronobacter spp. exposure risk was reduced by a maximum of 100 times at 95% of iterations due to addition of cocoa at 5 g/100 mL, corresponding to scenario 3 (PEF: 15 kV/cm–3,000 μs; storage 120 h at 8 °C). Moreover, the probability of illness for a healthy population was reduced from 2.15 × 10-8, in the baseline scenario, to 4.78 × 10-10 due to cocoa addition and application of 15 kV/cm–3,000 μs PEF treatment.BISOSTAD projec

Co-located wave and offshore wind farms: A preliminary approach to the shadow effect

In recent years, with the consolidation of offshore wind technology and the progress carried out for wave energy technology, the option of combine both technologies has arisen. This combination rest mainly in two main reasons: in one hand, to increase the sustainability of both energies by means of a more rational harnessing of the natural resources; in the other hand, to reduce the costs of both technologies by sharing some of the most important costs of an offshore project. In addition to these two powerful reasons there are a number of technology synergies between wave and wind systems which makes their combination even more suitable. Co-located projects are one of the alternatives to combine wave-wind systems, and it is specially for these project were so-called shadow effect synergy becomes meaningful. In particular, this paper deals with the co-location of Wave Energy Conversion (WEC) technologies into a conventional offshore wind farm. More specifically, an overtopping type of WEC technology was considered in this work to study the effects of its co-location with a conventional offshore wind park. This study aims to give a preliminary approach to the shadow effect and its implications for both wave and offshore wind energies