In this paper two models for movement of respiratory gases in the insect trachea are presented. One model considers the tracheal system as a single flexible compartment while the other model considers the trachea as a single flexible compartment with gas exchange. This work represents an extension of Ben-Tal’s work on compartmental gas exchange in human lungs and is applied to the insect tracheal system. The purpose of the work is to study nonlinear phenomena seen in the insect respiratory system. (...) It is assumed that the flow inside the trachea is laminar, and that the air inside the chamber behaves as an ideal gas. Further, with the isothermal assumption, the expressions for the tracheal partial pressures of oxygen and carbon dioxide, rate of volume change, and the rates of change of oxygen concentration and carbon dioxide concentration are derived. The effects of some flow parameters such as diffusion capacities, reaction rates and air concentrations on net flow are studied. Numerical simulations of the tracheal flow characteristics are performed. The models developed provide a mathematical framework to further investigate gas exchange in insects. (shrink)

In this article, we provide a description of the good in health promotion based on an empirical study of health promotion practices in New South Wales, the most populous state in Australia. We found that practitioners were unified by a vision of the good in health promotion that had substantive and procedural dimensions. Substantively, the good in health promotion was teleological: it inhered in meliorism, an intention to promote health, which was understood holistically and situated in places and environments, a (...) commitment to primary rather than secondary prevention and engagement with communities more than individuals. Procedurally, the good in health promotion arose from qualities of practices that they developed over time in respectful relationships, were flexible and responsive to communities, built capabilities in communities and were sustainable. We discuss our findings with reference to Martha Nussbaum’s normative list of functional capabilities for a good human life, David Buchanan’s vision for health promotion ethics and common concerns in health promotion ethics regarding the relationship between paternalism and freedom. Our thick, vague conception of the good in health promotion, founded in the values and practical reason of people engaged daily in health promotion work, contributes to the development of a more complete theory of health promotion ethics. (shrink)

Plato is one of the key ancient authors studied by both classicists and philosophers. This long-awaited new edition contains seven of the dialogues of Plato, and is the first in the five-volume complete edition of his works in the Oxford Classical Texts series. The result of many years of painstaking scholarship, the new volume will replace the now nearly 100 year old original edition, and is destined to become just as long-lasting a classic.