Symmetry as a sufficient condition for a finite flex

We show that if the joints of a bar and joint framework $(G,p)$ are positioned as `generically' as possible subject to given symmetry constraints and $(G,p)$ possesses a `fully-symmetric' infinitesimal flex (i.e., the velocity vectors of the infinitesimal flex remain unaltered under all symmetry operations of $(G,p)$), then $(G,p)$ also possesses a finite flex which preserves the symmetry of $(G,p)$ throughout the path. This and other related results are obtained by symmetrizing techniques described by L. Asimov and B. Roth in their paper `The Rigidity Of Graphs' from 1978 and by using the fact that the rigidity matrix of a symmetric framework can be transformed into a block-diagonalized form by means of group representation theory. The finite flexes that can be detected with these symmetry-based methods can in general not be found with the analogous non-symmetric methods.Comment: 26 pages, 10 figure

Derivation of diagnostic models based on formalized process knowledge

© IFAC.Industrial systems are vulnerable to faults. Early and accurate detection and diagnosis in production systems can minimize down-time, increase the safety of the plant operation, and reduce manufacturing costs. Knowledge- and model-based approaches to automated fault detection and diagnosis have been demonstrated to be suitable for fault cause analysis within a broad range of industrial processes and research case studies. However, the implementation of these methods demands a complex and error-prone development phase, especially due to the extensive efforts required during the derivation of models and their respective validation. In an effort to reduce such modeling complexity, this paper presents a structured causal modeling approach to supporting the derivation of diagnostic models based on formalized process knowledge. The method described herein exploits the Formalized Process Description Guideline VDI/VDE 3682 to establish causal relations among key-process variables, develops an extension of the Signed Digraph model combined with the use of fuzzy set theory to allow more accurate causality descriptions, and proposes a representation of the resulting diagnostic model in CAEX/AutomationML targeting dynamic data access, portability, and seamless information exchange

CAN HYPOTHETICAL, QUESTIONS PREDICT ACTUAL, PARTICIPATION IN PUBLIC PROGRAMS? A FIELD VALIDITY TEST USING A PROVISION POINT MECHANISM

Niagara Mohawk Power Corporation utilized a demand revealing public good mechanism to implement a green electricity program for provision of renewable energy and planting trees. This GreenChoiceTM program provided an opportunity to test the reliability of contingent valuation for predicting actual participation levels. In this study, participation levels predicted by hypothetical open-ended and dichotomous choice questions are compared to a reference level obtained from the actual GreenChoiceTM program. This approach represents an important improvement over past public goods contingent valuation validity tests which have relied on voluntary contribution mechanisms to elicit actual willingness to pay, and thus are likely to overestimate hypothetical bias because of free riding. Yet, even with a demand revealing mechanism and controlling for awareness, hypothetical participation levels obtained from dichotomous choice responses are found to significantly exceed actual contributions. In contrast, open-ended responses predict actual contribution levels, in that hypothetical open-ended responses are not significantly different from actual responses. Calibration of hypothetical responses is also explored.Public Economics, Resource /Energy Economics and Policy,

Course of neuromyelitis optica during inadvertent pregnancy in a patient treated with rituximab

In neuromyelitis optica (NMO), the monoclonal B-cell antibody rituximab is a therapeutic option. Little is known about the course of NMO and the safety of rituximab during pregnancy. In this study, we report the clinical course of a patient with NMO after application of rituximab 1 week before inadvertent conception. Mother and child did not experience any adverse event, and the postpartum development of the baby was completely normal up to 15 months. Clinical course of NMO was stable during the entire pregnancy. This case illustrates a favorable outcome in a pregnant NMO patient and her child after therapy with rituximab

VOLUNTARY REVELATION OF THE DEMAND FOR PUBLIC GOODS USING A PROVISION POINT MECHANISM

public goods, voluntary contributions, provision point, experiments, information, group size, Resource /Energy Economics and Policy, H41, C92,

The Value of Private Risk Versus the Value of Public Risk: An Experimental Analysis of the Johannesson et al. Conjecture

In 1996 Johannesson et al. published a paper in this journal entitled “The Value of Private Safety versus the Value of Public Safety.” Based on preliminary evidence from a hypothetical contingent valuation study, these authors argue that consumers behave as “pure altruists” and reject the notion of paternalistic preferences for safety in a coercive tax setting. These pure altruists consider the cost of a program that might be imposed on other voters when they decide whether to vote for or against public safety programs. The authors conclude that further empirical research in this area is warranted. This paper presents a set of laboratory economics experiments to test Johannesson et al.’s conjecture under controlled conditions in which participants face an actual risk of financial loss. The laboratory results extend those of Johannesson et al., providing strong evidence of pure altruism but limited support for paternalistic altruism for risk.Altruism, risk, voting, public goods, Research Methods/ Statistical Methods, Risk and Uncertainty, D81, D64, H41, C91, C92, D72,

Calvyn en die Akademie van Geneve

In this article Calvin's founding of the College and Academy of Geneva (1559) is discussed against the background of the medieval school system in order to appreciate his part in the renewal of education. Imbibing the humanism of his day, Calvin's engagagement with education reveals common ground with the humanist ideals of his limes. Yet there were fundamental differences: by combining the classical artes liberates with the study of God’s Word, his ideal was not the creation of better human beings through education (the ideal of humanism) but the formation of useful men and women in the kingdom of God, i.e in church and society. Some stipulations of his church order (1541) and Leges for the Academy are placed in the context of his theology. Finally, Calvin’s ideals and contribution to education challenge us to consider our choices for education in a 'new South Africa’