Do female zebrafish withhold reproductive resources for future mating opportunities?

Because polyandry often confers substantial direct and indirect benefits, females might be advantaged if they limit their reproductive investment in a single male when additional partners are available. We tested whether females of the externally fertilizing zebrafish Danio rerio would withhold more of their clutch when immediate further matings were likely. We tested females in three treatments: overnight visual and olfactory exposure to either a single male, two males, or three males. Females were then allowed to mate with one of the males; in the two-male and three-male treatments, the additional males remained in visual and olfactory contact to simulate a high likelihood of additional mating. Available clutch was measured by leaving females to spawn with two novel males for an additional 60?min. In contrast to our expectations, females did not release a greater proportion of their clutch when only a single male was present. Instead, females in the single male treatment released significantly fewer eggs per spawning event and significantly fewer eggs over the full 70?min of the trial. The hypothesis that females adjust current reproductive investment support in relation to the likely availability of mating partners is not supported. Instead, females appear to lay fewer eggs when only one male is available, most likely as a result of physiological stimulation of oocyte maturation, or in response to the likely fertilization capacity of a single individual.     

Evaluating the implementation of cleaner production audit demonstration projects

Cleaner production audit demonstration projects were carried out in two Chinese case factories as part of a project co-sponsored by the Illinois Environmental Protection Agency and China's State Environmental Protection Administration. Audit results at both factories were characterized by implementation of predominantly low- or no-cost options, notable reductions in water pollution, and incomplete financial benefit analyses. Two reasons explain the financial benefit analyses' apparent weakness. First, factory audit teams were inexperienced in the techniques and procedures used to determine the economic benefits of cleaner production options. Second, motivations project personnel had for participating in the demonstration projects were not centered on attaining the monetary benefits of implementing cleaner production. Instead, other factors related to the international nature of the project, such as a high degree of state level oversight and prestige, were more influential in affecting the behavior of project personnel.     

Spiked sample standards; Their uses and disadvantages in analytical quality control

Standard samples, that is matrices containing precisely known concentrations of various radionuclides, are necessary adjuncts to any analytical quality control program. In general, we prefer the use of “natural matrix standards,” samples into which the radionuclides have become incorporated under natural conditions, and over as long a time span as possible. Under some circumstances, however, real advantages are offered by “spiked sample standards” samples to which the isotope of interest has been added in a precisely known amount, at the time of preparing the standard. It is our purpose to discuss the advantages and disadvantages of spiked standards and to contrast them with those of natural matrix standards, as well as to discuss the preparation of the former class of standards and the evidence supporting our recommendation of caution in their use.In general, spiked standards offer advantages of low cost of preparation, of advance assurance that the amount and chemical form of the radioisotopes added are known, and of the possibility of preparation of unnatural matrices, or of nuclides that are to be expected but not yet to be found in nature. The most salient disadvantages of spiked standards derive from the usual uncertainty concerning the concentration of any radionuclides in the matrix before spiking and from the difficulty of insuring that there will be no difference in analytical behavior between the spike and the same isotope that has become incorporated in the matrix under natural conditions. Consideration of these advantages and disadvantages leads to identification of a list of special problems for which spiked standards may be advantageous and of a list of precautions indicated in the interpretation of the resulting data. The argument against the general applicability of spiked standards appear overwhelming.     

The implications of model complexity for environmental management

The purpose of this paper is to consider the implicatons of model complexity for the quality of the information provided by models of production activities that account for the processes involved in residuals generation and treatment. Using each of the three primary technologies for iron and steel-making industry and models of varying detail for each, the paper compares the estimated levels of residuals generated and treatment costs for both atmospheric and waterborne effluents. The findings suggest that there are strategic details in model construction which have fundamental implications for the design of environmental policies. Moreover, preliminary estimates of the costs of model construction and operation suggest that policymakers may not be able to afford complexity for its own sake. Rather these costs will require the development of methods to isolate the strategic details in each technology that are potentially important to environmental policies.     

Recycling as a planned behavior: the moderating role of perceived behavioral control

Environment, Development and Sustainability - This study examines the effectiveness of a public service announcement (PSA) video designed based on the theory of planned behavior (TPB) in motivating...