Size-dependent structural evolution and chemical reactivity of gold clusters.

Ground-state structures and other experimentally relevant isomers of Au(15) (-) to Au(24) (-) clusters are determined through joint first-principles density functional theory and photoelectron spectroscopy measurements. Subsequent calculations of molecular O(2) adsorption to the optimal cluster structures reveal a size-dependent reactivity pattern that agrees well with earlier experiments. A detailed analysis of the underlying electronic structure shows that the chemical reactivity of the gold cluster anions can be elucidated in terms of a partial-jellium picture, where delocalized electrons occupying electronic shells move over the ionic skeleton, whose geometric structure is strongly influenced by the directional bonding associated with the highly localized "d-band" electrons.     

Effect of pH on growth and fatty acid composition ofLactobacillus büchneri andLactobacillus fermentum

Growth and fatty acid composition of two lactobacilli,Lactobacillus büchneri andLactobacillus fermentum, were studied at different pHs of the media in a small-scale fermenter with particular interest in lactobacillic acid production of the cultures. Generally, the total fatty acid content of the bacterial cells increased with increasing culture age. The production of lactobacillic acid was affected in the two lactobacilli by both culture age and pH of the media, but in a very different manner. In L.büchneri cultures, the relative proportion of lactobacillic acid was highest when the pH was lowest (pH 4.5), whereas inL. fermentum cultures, the proportion of lactobacillic acid was highest at pH 7.0. The pH of the medium affected not only the relative proportion of lactobacillic acid, but also biomass production and total fatty acid accumulation of the cultures. Thus, by controlling the pH of the cultures, the volumetric yield of lactobacillic acid could be improved considerably compared to cultures without pH control.     

Multivariate Gaussian criteria in SMAA

We consider stochastic multicriteria decision-making problems with multiple decision makers. In such problems, the uncertainty or inaccuracy of the criteria measurements and the partial or missing preference information can be represented through probability distributions. In many real-life problems the uncertainties of criteria measurements may be dependent. However, it is often difficult to quantify these dependencies. Also, most of the existing methods are unable to handle such dependency information.In this paper, we develop a method for handling dependent uncertainties in stochastic multicriteria group decision-making problems. We measure the criteria, their uncertainties and dependencies using a stochastic simulation model. The model is based on decision variables and stochastic parameters with given distributions. Based on the simulation results, we determine for the criteria measurements a joint probability distribution that quantifies the uncertainties and their dependencies. We then use the SMAA-2 stochastic multicriteria acceptability analysis method for comparing the alternatives based on the criteria distributions. We demonstrate the use of the method in the context of a strategic decision support model for a retailer operating in the liberated European electricity market.     

Molecular dynamics simulations of conserved Hox protein hexapeptides. I. Folding behavior in water solution

Molecular dynamics simulations of hexapeptides TFDWMK and LFPWMR; the highly conserved regions of Hox proteins Hox B1 and Hox B8, respectively, are carried out starting from extended structures to investigate their conformational space in water solution. In addition, we have studied TADWMK and TADAMK, where the aromatic residues Phenylalanine and Tryptophan were successively substituted for Alanine to investigate effects from the presence/absence of aromatic amino acids and interactions between them to folding behavior. The backbone of the hexapeptides in all simulations folds to a similar conformation found in experimental studies in solution. Intramolecular, hydrophobically driven interactions between the aromatic residues and internal hydrogen bonds are found to stabilize the conformations.     

Relativity and the lead-acid battery

The energies of the solid reactants in the lead-acid battery are calculated ab?initio using two different basis sets at nonrelativistic, scalar-relativistic, and fully relativistic levels, and using several exchange-correlation potentials. The average calculated standard voltage is 2.13?V, compared with the experimental value of 2.11?V. All calculations agree in that 1.7-1.8?V of this standard voltage arise from relativistic effects, mainly from PbO2 but also from PbSO4.     

The analytic hierarchy process with stochastic judgements

The analytic hierarchy process (AHP) is a widely-used method for multicriteria decision support based on the hierarchical decomposition of objectives, evaluation of preferences through pairwise comparisons, and a subsequent aggregation into global evaluations. The current paper integrates the AHP with stochastic multicriteria acceptability analysis (SMAA), an inverse-preference method, to allow the pairwise comparisons to be uncertain. A simulation experiment is used to assess how the consistency of judgements and the ability of the SMAA-AHP model to discern the best alternative deteriorates as uncertainty increases. Across a range of simulated problems results indicate that, according to conventional benchmarks, judgements are likely to remain consistent unless uncertainty is severe, but that the presence of uncertainty in almost any degree is sufficient to make the choice of best alternative unclear.     

On the notion of coexistence in quantum mechanics

The notion of coexistence of quantum observables was introduced to describe the possibility of measuring two or more observables together. Here we survey the various different formalisations of this notion and their connections. We review examples illustrating the necessary degrees of unsharpness for two noncommuting observables to be jointly measurable (in one sense of the phrase). We demonstrate the possibility of measuring together (in another sense of the phrase) noncoexistent observables. This leads us to a reconsideration of the connection between joint measurability and noncommutativity of observables and of the statistical and individual aspects of quantum measurements.