We review the most comprehensive metabolic theory of life existing to date. A special focus is given to the thermodynamic roots of this theory and to implications that the laws of physics-such as the conservation of mass and energy-have on all life. Both the theoretical foundations and biological applications are covered. Hitherto, the foundations were more accessible to physicists or mathematicians, and the applications to biologists, causing a dichotomy in what always should have been a single body of work. To bridge the gap between the two aspects of the same theory, we (i) adhere to the theoretical formalism, (ii) try to minimize the amount of information that a reader needs to process, but also (iii) invoke examples from biology to motivate the introduction of new concepts and to justify the assumptions made, and (iv) show how the careful formalism of the general theory enables modular, self-consistent extensions that capture important features of the species and the problem in question. Perhaps the most difficult among the introduced concepts, the utilization (or mobilization) energy flow, is given particular attention in the form of an original and considerably simplified derivation. Specific examples illustrate a range of possible applications-from energy budgets of individual organisms, to population dynamics, to ecotoxicology.

Although police officers are frequently exposed to potentially traumatic incidents, only a minority will develop chronic Posttraumatic Stress Disorder (PTSD). Identifying and understanding protective factors could inform the development of preventive interventions; however, few studies have examined this. In the present prospective study, 233 police officers were assessed during academy training and again following two years of police service. Caucasian race, less previous trauma exposure, and less critical incident exposure during police service as well as greater sense of self-worth, beliefs of greater benevolence of the world, greater social support and better social adjustment, all assessed during academy training, were associated with lower PTSD symptoms after two years of service. Positive personality attributes assessed during training with the NEO Five-Factor Personality Inventory were not associated with lower PTSD symptoms. In a hierarchical linear regression model, only Caucasian race, lower critical incident exposure during police service, greater assumptions of benevolence of the world and better social adjustment during training remained predictive of lower PTSD symptoms after two years of police service. These results suggest that positive world assumptions and better social functioning during training may protect police officers from critical incident related PTSD.