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AbstractA survey of the literature on the economics of natural resources. Extractive resources are classified as renewable or non-renewable, depending on whether they exhibit economically significant rates of regeneration. A unified model of optimal extraction over time is developed, drawing on a number of contributions to the literature. Special features are developed for the renewable and non-renewable cases, and extensions and applications are noted, as well as needs for further research. Policy issues are treated, chief among these being the extent to which the market can be trusted to generate the right rate of extraction. Finally the empirical evidence is reviewed on whether we are running out of extractive resources.

The objective of this article is to offer critical reflective analysis of the notion of violence from the point of view of ethology and evolutionary psychology. The authors define violence as a value judgment of aggression in which aggression, operationally defined by any oriented (physical, gestural, verbal, etc.), non-playful behavior that may potentially cause harm to the physical or psychological integrity of another person, is deemed to be an abuse of power. Thus, they adopt a position contrary to that of researchers who consider parental neglect, play-fighting and war games among children to be violent. They also respond to the tendency to consider parental corporal punishment as necessarily violent. They then examine the adaptive biological functions of different types of aggression as well as several of the natural regulating mechanisms governing them. They consider the question of violence from two angles: is violence typical of the entire human species, and are men more violent than women? The authors then propose a model for family power relationships (marital, parent-child, child-child) which may provide a better understanding of family conflict and its possible influence on the development not only of child aggression towards peers but also of children's competitive skills for gaining access to environmental resources. Finally, they conclude that morality is arbitrary and it is therefore important not to attempt to use science to justify it.

Keywords: agression, compétition, éthologie, punition physique, psychologie évolutionniste, rapport de pouvoir, relation d'activation, violence conjugale, activation relationship, aggression, competition, ethology, evolutionary psychology, physical punishment, power relationship, conjugal violence

The accumulation and (acute) toxicity of dissolved metals in many aquatic organisms are normally well predicted with the biotic ligand model (BLM), although some exceptions have been reported. In long-term chronic metal exposures, complex physiological interactions with essential and non-essential metals may modulate metal uptake rates and toxicity. The present literature review discusses recent advances in environmental chemistry, molecular biology, and physiology related to the regulatory mechanisms of membrane transport of essential metals in eukaryotic phytoplankton and to their impacts on the accumulation and toxicity of cadmium, a usually non-essential metal. This literature review finally evaluates the possibility of including elements of algal physiology in the current version of the BLM in order to enhance the potential of this model to predict metal uptake and toxicity in chronic exposures. The available results in the literature suggest that the inclusion of negative and positive feedback interactions of metals on the kinetic parameters (Vmax: maximal uptake rate; KM: metal affinity of the transport sites) of multiple metal transport systems shows promise for better predicting the long-term accumulation and toxicity of metals in phytoplankton. The development of a BLM able to predict the chronic toxicity of metals under various physicochemical conditions representative of those found in the environment will benefit from recent and future advances in toxicology, biology and environmental chemistry. The knowledge gained will aid in achieving the ambitious goal of developing an extended BLM that reliably predicts metal toxicity in complex natural aquatic environments.

Keywords: Modèle du ligand biotique, toxicité des métaux, phytoplancton, physiologie algale, transport membranaire des métaux, Biotic ligand model, metal toxicity, phytoplankton, algal physiology, metal transport systems

AbstractIn the Great Lakes region, the vertical motion of crustal rebound since the last glaciation has decelerated with time, and is described by exponential decay constrained by observed warping of strandlines of former lakes. A composite isostatic response surface relative to an area southwest of Lake Michigan beyond the limit of the last glacial maximum was prepared for the complete Great Lakes watershed at 10.6 ka BP (12.6 cal ka BP). Uplift of sites computed using values from the response surface facilitated the transformation of a digital elevation model of the present Great Lakes basins to represent the paleogeography of the watershed at selected times. Similarly, the original elevations of radiocarbon-dated geomorphic and stratigraphic indicators of former lake levels were reconstructed and plotted against age to define lake level history. A comparison with the independently computed basin outlet paleo-elevations reveals a phase of severely reduced water levels and hydrologically-closed lakes below overflow outlets between 7.9 and 7.0 ka BP (8.7 and 7.8 cal ka BP) in the Huron-Michigan basin. Severe evaporative draw-down is postulated to result from the early Holocene dry climate when inflows of meltwater from the upstream Agassiz basin began to bypass the upper Great Lakes basin.

In the United States, "Health Maintenance Organisations" (HMO) undertookto master the growth of the costs of the health. Numerous patients complainedabout the quality of the care under this regime and about limitations that HMOimposed on them, in particular in access to care. To the quality care issues underthis regime added the anxieties conceming patients' satisfaction. Has the formerdegraded under the regime HMO? On this subject, numerous studies compare thesatisfaction of the patients under the regime HMO to that of the patients in thetraditional System with "Fee-For-Service payment" (FFS). They also concern thevulnerable patients, such as the old or deprived persons, illustrating how difficultit is to measure of quality.

Keywords: Managed Care, HMO, patients, satisfaction, assurance, Managed Care, HMO, patients, satisfaction, insurance