Atomistic study of two-level systems in amorphous silica

International audienceInternal friction is analyzed in an atomic-scale model of amorphous silica. The potential energy landscape of more than 100 glasses is explored to identify a sample of about 700 two-level systems (TLSs). We discuss the properties of TLSs, particularly their energy asymmetry and barrier as well as their deformation potential, computed as longitudinal and transverse averages of the full deformation potential tensors. The discrete sampling is used to predict dissipation in the classical regime. Comparison with experimental data shows a better agreement with poorly relaxed thin films than well relaxed vitreous silica, as expected from the large quench rates used to produce numerical glasses. The TLSs are categorized in three types that are shown to affect dissipation in different temperature ranges. The sampling is also used to discuss critically the usual approximations employed in the literature to represent the statistical properties of TLSs

A Multiple Criteria Sorting Methodology with Multiple Classification Criteria and an Application to Country Risk Evaluation

In this paper, we propose an extension of the standard UTADIS methodology, an approach that originates from multicriteria decision aid (MCDA) for sorting problems, such that it can handle more than one classification criteria simultaneously which possibly involves different predefined classes for alternatives. Moreover, we test the classification ability of the standard UTADIS methodology using the out-of-classification criterion approach, a new variant of the studies comprising out-of-time and out-of-sample testing methodologies. Results obtained in out-of-classification criterion testing are then compared with the classification ability of the Multiple Classification Criteria UTADIS (MCC UTADIS). Finally, an application to country risk evaluation is performed. In this application, classifications of two credit rating agencies, Standard & Poor's and Moody's, are taken as two different classification criteria. Moreover, robustness of MCC UTADIS method is tested through using several data sets. Results indicate that MCC UTADIS involving more than one classification criteria performs very close to standard UTADIS with single classification criterion and performs better than the out-of-classification criterion tests. These results emphasize both the sensitivity of UTADIS models to the classification criteria and the importance of using a multiple classification criteria approach.WoSScopu

Impact of cognitive style on group decision and negotiation

Numerous studies on group decision and negotiation have focused on the influence of the cognitive style of decision makers. Using number of instruments such as Kirton Adaption Innovation (KAI), Cognitive Style Index (CSI), Kolb Learning Style Inventory (KLS), Belbin team role self‐perception inventory, or the well-known Myers-Briggs Type Indicator (MBTI), studies explore relationships between different dimensions of the personality traits of the individuals and the performance of group decisions. The results are very heterogeneous and sometimes contradictory, depending in particular on the decision contexts explored (strategic decision or not, etc.) and the type of measurement and proxy used to identify the cognitive style. When cognitive diversity is the variable used in these researches, it is no longer the influence of an individual cognitive style on the decision that becomes the object of study but the fact that several styles are represented among the members of a group of decision makers. Looking for an integrative group of decision makers, as it is finally proposed in this chapter through a cognitive mapping-based method, is then a way to increase group decision performance