Turbulence investigation in the roughness sub-layer of a near wall flow

The turbulence behaviour along a wall roughened by pyramidal elements was analysed in the region extending from the apex of the roughness elements up to the external limit of the roughness sub-layer. The data used for the analysis were obtained by particle image velocimetry technique. The rough wall turbulent boundary layer flow is characterized by a relatively low Reynolds number. All the results on the rough wall were compared with data referring to the canonical flow on a smooth wall turbulent boundary layer. Mean values and turbulence quantities for the two flows collapse when approaching the external limit of the roughness sublayer. The quadrant analysis of the Reynolds shear stress, in the region near the surface, shows that the contribution of the sweep motions is about equivalent for the two flows (except for wall distances lower than 40 viscous units). The contribution of the ejection motions appears to be more important over the smooth wall than over the rough wall with increasing differences approaching the wall. The probability density functions of the streamwise fluctuating velocity field for the rough wall case appear to be positively skewed in the zone very close to the pyramid apex, in contrast with the behavior observed for the smooth wall case at corresponding distances from the wall. The integral and Taylor scales for the rough wall case appear to be strongly reduced by the presence of the roughness, while the Kolmogorov microscale shows higher values.     

Mechanical properties of Municipal Solid Waste by SDMT

In the paper the results of a geotechnical investigation carried on Municipal Solid Waste (MSW) materials retrieved from the “Cozzo Vuturo” landfill in the Enna area (Sicily, Italy) are reported and analyzed. Mechanical properties were determined both by in situ and laboratory large-scale one dimensional compression tests.While among in situ tests, Dilatomer Marchetti Tests (DMT) is used widely in measuring soil properties, the adoption of the DMT for the measurements of MSW properties has not often been documented in literature. To validate its applicability for the estimation of MSW properties, a comparison between the seismic dilatometer (SDMT) results and the waste properties evaluated by laboratory tests was carried out.Parameters for “fresh” and “degraded waste” have been evaluated. These preliminary results seems to be promising as concerns the assessment of the friction angle of waste and the evaluation of the S-wave in terms of shear wave velocity. Further studies are certainly required to obtain more representative values of the elastic parameters according to the SDMT measurements.     

Markets and the crowding out of conservation-relevant behavior

Markets are increasingly being incorporated into many aspects of daily life and are becoming an important part of the conservation solution space. Although market-based solutions to environmental problems can result in improvements to conservation, a body of social science research highlights how markets may also have unforeseen consequences by crowding out or displacing 3 key types of behaviors potentially relevant to conservation, including people's willingness to engage in collective action and civic duty; tolerance for inflicting harm on others (third-party externalities); and desire for equity. Better understanding of the contexts and mechanisms through which this crowding out occurs and whether specific market-based instruments are more prone to different types of crowding out will be crucial to developing novel conservation initiatives that can reduce or prevent crowding out.     

Mercury removal, methylmercury formation, and sulfate-reducing bacteria profiles in wetland mesocosms

A pilot-scale model was constructed to determine if a wetland treatment system (WTS) could effectively remove low-level mercury from an outfall located at the Department of Energy's Savannah River Site. Site-specific hydrosoil was planted with giant bulrush, Scirpus californicus, and surface amended with gypsum (CaSO4) prior to investigating the biogeochemical dynamics of sediment-based sulfur and mercury speciation. On average, the pilot WTS decreased total mercury concentrations in the outfall stream by 50%. Transformation of mercury to a more "bioavailable" species, methylmercury, was also observed in the wetland treatment system. Methylmercury formation in the wetland was ascertained with respect to sediment biogeochemistry and S. californicus influences. Differences in sulfate-reduction rates (SRRs) were observed between mesocosms that received additional decomposing Scirpus matter and mesocosms that were permitted growth of the submerged macrophyte, Potamogeton pusillus. Relative abundance measurements of sulfate-reducing bacteria (SRB) as characterized using oligonucleotide probes were also noticeably different between the two mesocosms. A positive correlation between increased sulfide, dissolved total mercury, and dissolved methylmercury concentrations was also observed in porewater. The data suggest that soluble mercury-sulfide complexes were formed and contributed, in part, to a slight increase in mercury solubility. Observed increases in methylmercury concentration also suggest that soluble mercury-sulfide complexes represent a significant source of mercury that is "available" for methylation. Finally, a volunteer macrophyte, Potamogeton pusillus, is implicated as having contributed additional suspended particulate matter in surface water that subsequently reduced the pool of dissolved mercury while also providing an environment suitable for demethylation.     

An examination of the curvilinear relationship between leader–member exchange and intent to turnover

Based on the theoretical identification of three different motivational forces for voluntary turnover—affective, calculative, and alternative—we hypothesize that the relationship between supervisor–subordinate relationship quality (i.e., leader–member exchange) and turnover intentions is best represented as curvilinear as opposed to linear. We test this hypothesis in two organizational samples consisting of 402 employees from a water management district and 183 employees from a distribution services organization. We found support for the hypothesis in both samples. We offer directions for future research. Copyright © 2005 John Wiley & Sons, Ltd.     

USING UNCENSORED TRACE-LEVEL MEASUREMENTS TO DETECT TRENDS IN GROUND WATER CONTAMINATION1

ABSTRACT: Environmental decision making involving trace-levels of contaminants can be complicated by censoring, the practice of reporting concentrations either as less than the limit of detection (LOD) or as not detected (ND) when a test result is less than the LOD. Censoring can result in data series that are difficult to meaningfully summarize, graph, and analyze through traditional statistical methods. In spite of the relatively large measurement errors associated with test results below the LOD, simple and meaningful analyses can be carried out that provide valuable information not available if data are censored. For example, an indication of increasing levels of contamination at the fringe of a plume can act as an early warning signal to trigger further study, an increased sampling frequency, or a higher level of remediation at the source. This paper involves the application of nonparametric trend analyses to uncensored trace-level groundwater monitoring data collected between March 1991 and August 1994 on dissolved arsenic and chromium for seven wells at an industrial site in New York.     

Communication at inactive hazardous waste sites

The remediation of inactive hazardous waste sites frequently involves a protracted negotiation with the respective state or federal agency and the entity responsible for creating the site and paying the costs. At orphaned sites, decisions are made almost exclusively by agency staff. Most of remedial decisions are made with little input or participation by the interested public. The public usually receives information in a highly technical and difficult-to-understand format after decisions are made. This ineffective form of communication can lead to mistrust and delays or changes in the remediation process. Effective public participation requires multidirectional modes of communication that provide for active and full involvement by all interested parties. At the present time, most agencies pay minimal attention to the needs of the interested public, often leaving area residents suspicious and dissatisfied with the overall program. There is an opportunity to significantly improve the public participation component of the federal Super-fund program through reauthorization. Subtle changes in the program can result in a significant increase of the public's sense of participation and overall satisfaction.     

Interactive effects of impression management and organizational politics on job performance

The purpose of this research was to explore the interactive effect of organizational politics and impression management on supervisor ratings of employee performance. We hypothesized that the negative relationship between organizational politics and supervisor‐rated performance is weaker among employees who are high in impression management than among those low in impression management. Data were collected from a matched sample of 112 white‐collar employees and their supervisors. Results indicated that the interaction of organizational politics and impression management explained a significant incremental amount of variance in supervisor ratings of employee performance. These findings demonstrated that the extent to which an individual engaged in impression management in a non‐political atmosphere may have been a key component to receiving favorable performance ratings. Copyright © 2004 John Wiley & Sons, Ltd.