Quantum singularities in FRW universe revisited

The components of the Riemann tensor in the tetrad basis are quantized and, through the Einstein equation, we find the local expectation value in the ontological interpretation of quantum mechanics of the energy density and pressure of a perfect fluid with equation of state $p=\frac{1}{3}\rho$ in the flat Friedmann-Robertson-Walker quantum cosmological model. The quantum behavior of the equation of state and energy conditions are then studied and it is shown that the later is violated since the singularity is removed with the introduction of quantum cosmology, but in the classical limit both the equation of state and the energy conditions behave as in the classical model. We also calculate the expectation value of the scale factor for several wave packets in the many-worlds interpretation in order to show the independence of the non singular character of the quantum cosmological model with respect to the wave packet representing the wave function of the Universe. It is also shown that, with the introduction of non-normalizable wave packets, solutions of the Wheeler-DeWitt equation, the singular character of the scale factor, can be recovered in the ontological interpretation.Comment: 15 pages, revtex, accepted for publication in PR

Interacting Quintessence

We demonstrate that a suitable coupling between a quintessence scalar field and a pressureless cold dark matter (CDM) fluid leads to a constant ratio of the energy densities of both components which is compatible with an accelerated expansion of the Universe.Comment: 12 pages, LaTeX; new material on the stability analysis and on the interaction potential added, reference list enlarged and updated; to be published in PL

Synergistic warm inflation

We consider an alternative warm inflationary scenario in which $n$ scalar fields coupled to a dissipative matter fluid cooperate to produce power--law inflation. The scalar fields are driven by an exponential potential and the bulk dissipative pressure coefficient is linear in the expansion rate. We find that the entropy of the fluid attains its asymptotic value in a characteristic time proportional to the square of the number of fields. This scenario remains nearly isothermal along the inflationary stage. The perturbations in energy density and entropy are studied in the long--wavelength regime and seen to grow roughly as the square of the scale factor. They are shown to be compatible with COBE measurements of the fluctuations in temperature of the CMB.Comment: 13 pages, Revtex 3 To be published in Physical Review

Empowering the Citizen-Consumer: Re-Regulating Consumer Information to Support the Transition to Sustainable and Health Promoting Food Systems in Canada

Both health and sustainability are stated public policy objectives in Canada, but food information rules and practices may not be optimal to support their achievement. In the absence of a stated consensus on the purposes of public information about food, the information provided is frequently determined by the marketers of product. No institution or agency has responsibility for determining the overall coherence of consumer food messages relative to these broader social goals of health and sustainability. Individual firms provide information that shows their products to best advantage, which may contradict what is provided about the product by another firm or government agency. Individual consumers do not have the resources to determine easily the completeness of any firm\u27s messages, particularly in light of the size of food industry advertising budgets. Government rules confound this problem because there is also little coherence between the parts of government that have responsibility for point of purchase, advertising rules, and labelling. The healthy eating messages of health departments are often competing with contradictory messages permitted by the regulatory framework of other arms of government. Investments in programs that successfully promote environmental stewardship in agriculture are undercut in the market because consumers cannot support those efforts with their dollars. This problem exists despite the emergence of “citizen-consumers” who have a broader approach to food purchasing than individual maximization. Only recently have some health professionals and sustainable agriculture proponents turned their attention to these factors and designed interventions that take them into account. In this paper, which builds upon earlier work by MacRae [1], we outline key short, medium and long term initiatives to facilitate the citizen-consumer phenomenon and better support consumers in their efforts to promote health and sustainability in the Canadian food system

Deliberation, Unjust Exclusion, and the Rhetorical Turn

Theories of deliberative democracy have faced the charge of leading to the unjust exclusion of voices from public deliberation. The recent rhetorical turn in deliberative theory aims to respond to this charge. I distinguish between two variants of this response: the supplementing approach and the systemic approach. On the supplementing approach, rhetorical modes of political speech may legitimately supplement the deliberative process, for the sake of those excluded from the latter. On the systemic approach, rhetorical modes of political speech are legitimate within public deliberation, just so long as they result in net benefits to the deliberative system. I argue that neither of these two approaches adequately meets the unjust exclusion charge. Whereas the supplementing approach does not go far enough to incorporate rhetorical speech into public deliberation, the systemic approach goes too far by legitimizing forms of rhetoric that risk only exacerbating the problem of unjust exclusion. More constructively, I draw on Aristotle’s conception of rhetoric, as an art (technē) that is a counterpart to dialectic, to argue for a constitutive approach to rhetoric. I show how this approach provides a more expansive notion of deliberation that remains normatively orientated