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31.
Despite the rapid uptake of multi‐source multi‐rater (MSMR) feedback systems by UK organizations, comparatively little research exists describing the actual impact on participant managers, in terms of changes in management competence. Ratings of 104 target managers (by self assessments, bosses‐, first‐ and second‐level subordinates) were investigated within the context of a developmental feedback programme in operation within an organization. The study compared ratings over two administrations (with two years between administrations) to determine: (1) changes in co‐workers' perceptions of their target manager's competence, (2) changes in target managers' development needs over time, (3) factors influencing a target manager's revised self‐assessment and co‐workers ratings, (4) changes in congruence between self and co‐workers ratings and (5) the relationship of feedback to the organization's formal performance appraisal process. Significant increases in managers' competence were perceived by the managers' themselves and by their subordinates, development needs were seen to reduce and self and co‐workers ratings were largely seen to become more congruent. However, polynomial regression analyses revealed co‐workers feedback at Time One was not predictive of targets' self‐assessments at Time Two. The implications of these findings with regard to the utility of MSMR feedback as a tool for management development are discussed. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
32.
The development of the escape response of walleye pollock (Theragra chalcogramma) larvae from attacks by macrozooplanktonic and small-fish predators was quantified in laboratory experiments. Behavior was recorded using video cameras with silhouette illumination from infrared-emitting diodes and by visual observation. Laboratory-reared larvae of 1, 3, 8, 10, 12, 18, 22, 27, 42 days post-hatching, ranging in size from 4 mm to 10 mm total length, were used in the experiments. Even the youngest larvae were observed to exhibit a fast startle response. The percentage of successful larval escapes from the different predators increased as the larvae developed. Euphausiids (Thysanoessa raschii) and amphipods (Calliopiella pratti) often touched larvae but the larvae were usually able to escape and no successful captures of larvae over 22 days old were observed. Although successful escape from initial attacks by three-spine sticklebacks (Gasterosteus aculeatus) increased ontogenetically, sticklebacks were able to consume most larvae, even of the oldest age group, by repeated attacks. Day-old larvae had the lowest percent of escapes after encounters with jellyfish (Sarsia sp.), but the percentage of escapes increased dramatically for 3-day-old larvae. Escape speeds after an attack also increased with age, and tended to be higher after stickleback attacks and lower after jellyfish attacks. This study revealed that the escape response of larval pollock to attack by predators improves rapidly with development during the early larval stage.  相似文献   
33.
Bailey JS  Wang K  Jordan C  Higgins A 《Chemosphere》2001,42(2):131-140
Spatial variability in N uptake and utilisation by swards within uniformly managed field units could be responsible for a significant proportion of the NH3, N2O, NO3- and NOx (NO and NO2) 'pollutants' generated by agriculture and released to the environment. An investigation was commenced, therefore, to quantify, map and explain the spatial variability in sward N yield in a 'large' silage field and to assess the potential for managing this variability using some of the latest precision agriculture technology. Sward dry matter (DM) and N yields were predicted from the results of plant tissue analyses using mathematical models. Sward N yields were found to vary greatly across the field seemingly because of differences in net soil N mineralisation, but the pattern of variability appeared to remain constant with time. Conventional soil analysis of a range of soil chemical and physical properties, however, failed to explain this variability. It was concluded that the N-yield distribution map might be used in place of soil analysis as the basis for varying the rates of N application to different parts of the field with the twin objectives of maximising fertiliser use efficiency and minimising N emissions to air and water.  相似文献   
34.
Habitat restoration at a landscape scale is becoming increasingly important in environmental management. In this context, geographical information systems are well suited as they can store and integrate many of the abiotic and biotic criteria used to assess the ecological worth of a site. However, this capacity can be limited by the availability or suitability of spatial data sets. A classic example of the latter case is the National Soil Map of England and Wales, which groups soils of a varied nature into associations. Consequently the national soil map has proved to be a poor predictor of habitat suitability. Using polytomous logistic regression we put forward a method for separating soil associations into their constituent soils within the Chilterns Natural Area. This approach used soil association, aspect, slope and relative height as variables for this analysis. Whilst the model's performance is likely to have been limited by the accuracy of the soil association data set, a predictive accuracy of between 47 and 65% is sufficient to facilitate better targeting of habitat restoration when combined with other abiotic factors such as climate and topography.  相似文献   
35.
36.
An upward trend in soluble reactive phosphorus (SRP) concentrations in Northern Ireland rivers leading to increased eutrophication has been reported for the last two decades. To identify if a similar trend could be observed in land drainage waters SRP and other P fractions were measured weekly from 1989 to 1997 in land drainage from a 9-ha grassland catchment in Northern Ireland that had a mean P surplus applied of 23.4 kg P ha(-1) yr(-1). Regressions of annual median concentrations of P fractions in land drainage waters against time for 1989 through to 1997 showed significant increases of SRP and soluble unreactive phosphorus (SUP) of 2.4 and 1.2 microg P L(-1) yr(-1), respectively. However, the annual flow-weighted concentrations and loads of all P fractions did not show significant increases with time. During the period 1998-2000 a change of management was introduced when only maintenance dressings of P were applied to the catchment according to Ministry of Agriculture, Fisheries and Food guidelines. This resulted in significant reductions in SRP concentrations in 2000 compared with 1997.  相似文献   
37.

Selenium (Se) biofortification of staple cereal crops can improve the Se nutritional status of populations. A field trial employing an enriched stable isotope of Se (77Se) was undertaken over three consecutive cropping seasons in a coarse-textured, calcareous soil in Gilgit-Baltistan, Pakistan. The objectives were to (1) assess the feasibility and efficiency of Se biofortification, (2) determine the fate of residual Se, and (3) assess the consequences for dietary Se intake. Isotopically enriched 77Se (77SeFert) was applied, either as selenate or as selenite, at three levels (0, 10, and 20 g ha?1) to a wheat crop. Residual 77SeFert availability was assessed in subsequent crops of maize and wheat without further 77SeFert addition. Loss of 77SeFert was c.35% by the first (wheat) harvest, for both selenium species, attributable to the practice of flood irrigation and low adsorption capacity of the soil. No 77SeFert was detectable in subsequent maize or wheat crops. The remaining 77SeFert in soil was almost entirely organically bound and diminished with time following a reversible (pseudo-)first-order trend. Thus, repeat applications of Se would be required to adequately biofortify grain each year. In contrast to native soil Se, there was no transfer of 77SeFert to a recalcitrant form. Grain from control plots would provide only 0.5 µg person?1 day?1 of Se. By contrast, a single application of 20 g ha?1 SeVI could provide c. 47 µg person?1 day?1 Se in wheat, sufficient to avoid deficiency when combined with dietary Se intake from other sources (c. 25 µg day?1).

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38.
A range of waste products and natural materials including chitin, fly ash, clay soil, cocoa shell, calcified seaweed and the natural zeolite clinoptilolite were tested in batch experiments to assess their ability to remove metals from a synthetic groundwater containing 10 mg l–1 Cu, Pb and Zn and 1 mg l–1 Cd. All had the ability to remove more than 70% of the metals from solution with fly ash being the most efficient, then chitin, clinoptilolite, calcified seaweed, clay soil and cocoa shell. After consideration of geochemical and morphological properties, calcified seaweed and clinoptilolite were shown to have potential as barrier materials. Given current issues with regard to the longevity of zero-valent iron barriers alternative materials could be the key to the future adoption of this remediation technology.  相似文献   
39.
Little is known about the importance of landscape and land cover to the implementation and performance of agricultural conservation projects designed to improve stream quality. In our study, we addressed the potential importance of landscape and land cover to conservation projects by measuring variation across 191 μ-basins (100–2400 ha) and integrating the observed variation into a study design aimed at determining the effectiveness of conservation projects. Our findings indicate that there are strong gradients across which landscape and land cover attributes vary. Land cover varied along a gradient of agricultural intensity, basin morphometry across gradients of stream closure and basin size, basin substrate was described by variation in drumlin formation, glacial landform type, and soil drainage, while agricultural conservation projects varied according to the level of project implementation. Correlation of these gradients found several associations between landscape and land cover, indicating that agricultural intensity was being constrained predominantly by drumlin formation and glacial landform type. Landscape and land cover did not appear to be determining factors in the implementation of conservation projects by land owners. Based on these findings we chose 32 μ-basins which represented the variability along each of the defined gradients for further study. We conclude that landscape scale variables demonstrate important variation and covariation that can and should be integrated into study designs for the assessment of streams and human activities affecting streams.  相似文献   
40.
Abstract

This work presents a three-stage treatment system to process halogenated organic vent streams for compliance with the Hazardous Organic NESHAP (HON) Rule. The three stages are incineration, energy recovery, and wet scrubbing. In particular, this work concentrates on the design of the scrubber, which the HON Rule states must remove at least 99% of any halogens or hydrogen halides generated during the combustion step. Computerized process simulation was found to be ineffective in designing a scrubber for this application, so laboratory data on the partial pressure of the hydrogen halide species over aqueous solutions was employed. The number of overall gas transfer units required for 99% removal was found to be slightly less than 5, and the overall gas transfer unit height was found to be approximately 0.5 m.  相似文献   
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