Phylogeographic study of the dwarf oyster, Ostreola stentina, from Morocco, Portugal and Tunisia: evidence of a geographic disjunction with the closely related taxa, Ostrea aupouria and Ostreola equestris

Despite the economic importance of oysters due to the high aquaculture production of several species, the current knowledge of oyster phylogeny and systematics is still fragmentary. In Europe, Ostrea edulis, the European flat oyster, and Ostreola stentina, the Provence oyster or dwarf oyster, are both present along the European and African, Atlantic and Mediterranean, coasts. In order to document the relationship not only between O. stentina and O. edulis, but also with the other Ostrea and Ostreola species, we performed a sequence analysis of the 16S mitochondrial fragment (16S rDNA: the large subunit rRNA-coding gene) and the COI fragment (COI: cytochrome oxidase subunit I). Oysters were sampled from populations in Portugal (two populations), Tunisia (two populations) and Morocco (one population), identified as O. stentina on the basis of shell morphological characters. Our data supported a high degree of differentiation between O. stentina and O. edulis and a close relationship between O. stentina and both Ostrea aupouria (from New Zealand) and Ostreola equestris (from Mexico Gulf/Atlantic). The status of this geographic disjunction between these closely related species is discussed. Furthermore, although identified in a separate genus Ostreola by Harry (Veliger 28:121–158, 1985), our molecular data on O. stentina, together with those available for the other two putative congeneric species, O. equestris and Ostreola conchaphila, would favour incorporation of Ostreola in Ostrea. Finally, a PCR-RFLP approach allowed the rapid identification of O. edulis and O. stentina.     

Modern energy region development and income distribution: An input-output analysis

This paper formulates an input-output method for determining the distributional consequences of energy development projects. The method is oriented to the conditions appearing in many contemporary development settings where large resident populations and other factors are likely to inhibit boomtown scenarios. An analysis of geothermal energy development in Imperial County, California, is presented. The results indicate that personal income inequality is likely to increase by several percentage points as measured by the Gini coefficient. The sensitivity of the results is examined with respect to important factors such as labor supply elasticities, preferential employment of local residents, and the concentration of land holdings.     

Determinants of vigilance behavior in the ring-tailed coati (Nasua nasua): the importance of within-group spatial position

Individuals living in social groups are predicted to live under unequal predation risk due to their spatial location within the group. Previous work has indicated that individuals located at the edge of groups have higher “domains of danger”, thus are more likely to engage in vigilance or antipredator behavior. We studied the determinants of vigilance behavior in two groups of ring-tailed coatis in Iguazu National Park, Argentina. In addition to the expected pattern that coatis were more vigilant at the edge of the group, we found that individuals were particularly vigilant at the front edge of the group. This pattern conforms to predictions of differing predation risk caused by sit-and-wait predators with respect to mobile animal groups. In addition, coatis exhibited less vigilance when the number of neighbors within 5 m and group size increased. Of the three spatial variables tested, within-group spatial position was the most important predictor variable determining vigilance levels. These results confirm that spatial position has major effects on vigilance behavior, and that group directionality is an important factor which should be taken into account when measuring vigilance behavior. Coatis were more vigilant when juveniles less than 6 months old were in the groups. The presence of these young juveniles also affected the relationship between alarm response and vigilance levels. Coatis were more vigilant after strong alarm reactions, but only when young juveniles were not present in the groups. This may indicate that coatis give differential responses to alarm calls depending on the age of the caller. A comparison of antipredator vigilance between coatis and sympatric capuchin monkeys is consistent with the hypothesis that terrestriality leads to higher perceive predation risk for coatis.     

Lanthanum fixation by Myxococcus xanthus: cellular location and extracellular polysaccharide observation

Myxococcus xanthus is a soil bacterium of the myxobacteria group and is abundant in almost all soils. Its role in soil ecology is considered significant. One noteworthy characteristic of the bacterium is that it produces large quantities of extracellular polymeric substances (EPS). It is also known that its biomass has the capacity to fix heavy metals. Here it is reported that M. xanthus was able to accumulate 0.6 mmol of La per g of wet biomass and/or 0.99 mmol per g of dry biomass. Transmission Electron Microscopy (TEM) observation of M. xanthus cells treated with La showed that a substantial amount of this cation was fixed in the EPS and in the cell wall. Smaller amounts were also observed in the cytoplasm. Fixed La appeared as phosphate in all cellular locations. The results given here also show that the use of La enables TEM observation of the M. xanthus EPS as a dense fibrillar net surrounding the cells. This technique is relatively easy and prevents EPS collapse, which occurs frequently during the fixation and dehydration procedures commonly used in preparations for TEM observations. Since antibodies are no longer required, the La stain can be carried out without delaying bacterial cell cultivation or isolation. In addition, the presence of La in cell cytoplasm without cell degeneration suggests that this microorganism could be used as a model in the study of bacteria-lanthanide interactions.     

Membrane-based wet electrostatic precipitation

Emissions of fine particulate matter, PM2.5, in both primary and secondary form, are difficult to capture in typical dry electrostatic precipitators (ESPs). Wet (or water-based) ESPs are well suited for collection of acid aerosols and fine particulates because of greater corona power and virtually no re-entrainment. However, field disruptions because of spraying (misting) of water, formation of dry spots (channeling), and collector surface corrosion limit the applicability of current wet ESPs in the control of secondary PM2.5. Researchers at Ohio University have patented novel membrane collection surfaces to address these problems. Water-based cleaning in membrane collectors made of corrosion-resistant fibers is facilitated by capillary action between the fibers, maintaining an even distribution of water. This paper presents collection efficiency results of lab-scale and pilot-scale testing at FirstEnergy's Bruce Mansfield Plant for the membrane-based wet ESP. The data indicate that a membrane wet ESP was more effective at collecting fine particulates, acid aerosols, and oxidized mercury than the metal-plate wet ESP, even with approximately 15% less collecting area.     

Bringing diverse knowledge sources together--a meta-model for supporting integrated catchment management

Integrated catchment management (ICM), as promoted by recent legislation such as the European Water Framework Directive, presents difficult challenges to planners and decision-makers. To support decision-making in the face of high complexity and uncertainty, tools are required that can integrate the evidence base required to evaluate alternative management scenarios and promote communication and social learning. In this paper we present a pragmatic approach for developing an integrated decision-support tool, where the available sources of information are very diverse and a tight model coupling is not possible. In the first instance, a loosely coupled model is developed which includes numerical sub-models and knowledge-based sub-models. However, such a model is not easy for decision-makers and stakeholders to operate without modelling skills. Therefore, we derive from it a meta-model based on a Bayesian Network approach which is a decision-support tool tailored to the needs of the decision-makers and is fast and easy to operate. The meta-model can be derived at different levels of detail and complexity according to the requirements of the decision-makers. In our case, the meta-model was designed for high-level decision-makers to explore conflicts and synergies between management actions at the catchment scale. As prediction uncertainties are propagated and explicitly represented in the model outcomes, important knowledge gaps can be identified and an evidence base for robust decision-making is provided. The framework seeks to promote the development of modelling tools that can support ICM both by providing an integrated scientific evidence base and by facilitating communication and learning processes.     

The Long Term Weathering of Water-in-Oil Emulsions

This paper summarizes studies to determine the long-term stability of water-in-oil emulsions in the laboratory and in large tanks. The long-term stability of emulsions was investigated in the laboratory for up to 9 years and by studying emulsion formation in a large test tank over a period of 2-10 days.Two stable emulsions, formed in the laboratory, had been preserved for 5 and 9 years and remained stable despite a small water loss. The long-term stability appears to be similar to that for the short-term stability. Stable emulsion breakdown processes remain poorly understood, because these emulsions do not generally breakdown, but the primary processes may be mechanical break-up and water evaporation.The water-in-oil states produced were found to have analogous properties between the laboratory and two sets of experiments at a large test tank. No fundamental differences in states or properties were observed over the time periods studied (up to 222 h). The state of the oil was found to correlate well with a stability index as defined by the complex modulus divided by the oil viscosity. It is shown that this stability index becomes more useful when the viscosity of the oil is taken at the same time as the complex modulus measurement.The studies show that meso-stable emulsions will break down within 3 days, generally within 1 day and that those emulsions classified as stable remain up to 9 years under laboratory conditions. These studies also show that meso-stable emulsions do not reform, once broken.