Transnational corporations and oral health: examples from the sugar industry

This paper seeks to describe the political behavior of transnational corporations (TNCs) related to sugars and dental caries. The paper begins by exploring dental caries as a political issue. It then provides a brief overview of key actors (expanders--e.g. public health advocates working to make policy action on sugar likely, and containers--e.g. TNC’s working to prevent policy action on sugar) and the importance of problem defi nition in public policy making. The paper then compares how expanders and containers frame the problem of sugars and dental caries. Based upon a policy analysis framework, categories used to frame problems include incidence, causality, severity, crisis, characteristics of the problem population, values, and solutions. These categories are discussed with application to debates about public policy solutions to the problem of dental caries. It then concludes by highlighting some tensions that remain in tackling dental caries through legislation and regulation

Faster-than-c signals, special relativity, and causality

Motivated by the recent attention on superluminal phenomena, we investigate the compatibility between faster-than-c propagation and the fundamental principles of relativity and causality. We first argue that special relativity can easily accommodate -- indeed, does not exclude -- faster-than-c signalling at the kinematical level. As far as causality is concerned, it is impossible to make statements of general validity, without specifying at least some features of the tachyonic propagation. We thus focus on the Scharnhorst effect (faster-than-c photon propagation in the Casimir vacuum), which is perhaps the most plausible candidate for a physically sound realization of these phenomena. We demonstrate that in this case the faster-than-c aspects are ``benign'' and constrained in such a manner as to not automatically lead to causality violations.Comment: Plain LaTeX2E; 25 pages; 4 embedded figures (LaTeX pictures). V2: Some discussion clarified, minor rearrangements, references updated, no change in physics conclusions. To appear in Annals of Physic

Causality and the speed of sound

A usual causal requirement on a viable theory of matter is that the speed of sound be at most the speed of light. In view of various recent papers querying this limit, the question is revisited here. We point to various issues confronting theories that violate the usual constraint.Comment: v2: additional discussion on models that appear to have superluminal signal speeds; version to appear in GR