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51.
The ability of an organisation to recognise the value of new external information, acquire it, assimilate it, transform, and
exploit it, namely its absorptive capacity (AC), has been much researched in the context of commercial organisations and even
applied to national innovation. This paper considers four key AC-related concepts and their relevance to public sector organisations
with mandates to manage and conserve freshwater ecosystems for the common good. The concepts are the importance of in-house
prior related knowledge, the importance of informal knowledge transfer, the need for motivation and intensity of effort, and
the importance of gatekeepers. These concepts are used to synthesise guidance for a way forward in respect of such freshwater
management and conservation, using the imminent release of a specific scientific conservation planning and management tool
in South Africa as a case study. The tool comprises a comprehensive series of maps that depict national freshwater ecosystem
priority areas for South Africa. Insights for implementing agencies relate to maintaining an internal science, rather than
research capacity; making unpublished and especially tacit knowledge available through informal knowledge transfer; not underestimating
the importance of intensity of effort required to create AC, driven by focussed motivation; and the potential use of a gatekeeper
at national level (external to the implementing organisations), possibly playing a more general ‘bridging’ role, and multiple
internal (organisational) gatekeepers playing the more limited role of ‘knowledge translators’. The role of AC as a unifying
framework is also proposed. 相似文献
52.
53.
Hot water flushing for immiscible displacement of a viscous NAPL 总被引:2,自引:0,他引:2
Thermal remediation techniques, such as hot water flooding, are emerging technologies that have been proposed for the removal of nonaqueous phase liquids (NAPLs) from the subsurface. In this study a combined laboratory and modeling investigation was conducted to determine if hot water flooding techniques would improve NAPL mass removal compared to ambient temperature water flushing. Two experiments were conducted in a bench scale two-dimensional sandbox (55 cmx45 cmx1.3 cm) and NAPL saturations were quantified using a light transmission apparatus. In these immiscible displacement experiments the aqueous phase, at 22 degrees C and 50 degrees C, displaced a zone with initial NAPL saturations on the order of 85%. The interfacial tension and viscosity of the selected light NAPL, Voltesso 35, are strongly temperature-dependent. Experimental results suggest that hot water flooding reduced the size of the high NAPL saturation zone, in comparison to the cold water flood, and yielded greater NAPL mass recovery (75% NAPL removal vs. 64%). Hot water flooding did not, however, result in lower residual NAPL saturations. A numerical simulator was modified to include simultaneous flow of water and organic phases, energy transport, temperature and pressure. Model predictions of mass removal and NAPL saturation profiles compared well with observed behavior. A sensitivity analysis indicates that the utility of hot water flooding improves with the increasing temperature dependence of NAPL hydraulic properties. 相似文献
54.
C. Verlingue A. David M. P. Audrezet M. G. Le Roux B. Mercier J. P. Moisan C. Ferec MD Ph.D. 《黑龙江环境通报》1993,13(12):1143-1148
The cystic fibrosis (CF) gene has been observed to have the highest frequency of mutations in the Caucasian population. Prenatal diagnosis can now be performed with a high degree of accuracy since the identification of most of the gene's mutations, as well as the characterization of intragenic markers. However, the observation of a distribution of clinical phenotypes increases the need to identify a mild phenotype and avoid false-negative diagnosis. By screening most of the exons of the CFTR gene, we showed that a supposed obligate carrier of CF was in fact an asymptomatic affected woman. 相似文献
55.
A. Merino A. De Perdigo F. Nombalais M. Yvinec M. G. Le Roux V. Bellec 《黑龙江环境通报》1993,13(10):1001-1007
We present two prenatal cases of trisomy 9 mosaicism, both of which presented intrauterine growth retardation (IUGR) and other abnormal ultrasound findings. In case A, mosaicism was found in amniotic fluid cell cultures, of which 65 per cent were trisomic cells, on average. In case B, trisomic cells were present in amniotic fluid cell cultures (12 per cent) but none were found in fetal cord blood. After autopsy, cytogenetic findings were confirmed in different tissue cultures. It is concluded that echographic indicators are a very useful tool for a correct prenatal diagnostic interpretation of trisomy 9. Suspected trisomy 9 mosaicism always requires further investigation and fetal cord blood cytogenetic analysis may not be considered as providing an accurate diagnosis of fetal trisomy 9. 相似文献
56.
Deleterious Effects of Restricted Gene Flow in Fragmented Populations 总被引:10,自引:1,他引:10
Denis Couvet 《Conservation biology》2002,16(2):369-376
57.
Biofiltration of a mixture of volatile organic emissions 总被引:9,自引:0,他引:9
Aizpuru A Malhautier L Roux JC Fanlo JL 《Journal of the Air & Waste Management Association (1995)》2001,51(12):1662-1670
Air biofiltration is now under active consideration for the removal of the volatile organic compounds (VOCs) from polluted airstreams. To optimize this emerging environmental technology and to understand compound removal mechanisms, a biofilter packed with peat was developed to treat a complex mixture of VOCs: oxygenated, aromatic, and chlorinated compounds. The removal efficiency of this process was high. The maximum elimination capacity (ECmax) obtained was approximately 120 g VOCs/m3 peat/hr. Referring to each of the mixture's components, the ECmax showed the limits in terms of biodegradability of VOCs, especially for the halogenated compounds and xylene. A stratification of biodegradation was observed in the reactor. The oxygenated compounds were metabolized before the aromatic and halogenated ones. Two assumptions are suggested. There was a competition between bacterial communities. Different communities colonized the peat-based biofilter, one specialized for the elimination of oxygenated compounds, the others more specialized for elimination of aromatic and halogenated compounds. There was also substrate competition. Bacterial communities were the same over the height of the column, but the more easily biodegradable compounds were used first for the microorganism metabolism when they were present in the gaseous effluent. 相似文献
58.
Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glucoside produced by Bracken in amounts up to at least 500 mg m(-2). The toxin is transferred from Bracken to the underlying soil from where it may leach to surface and groundwater's impairing the quality of drinking water. The objectives of the present study were to characterize the solubility, degradation and retention of PTA in soils in order to evaluate the risk for groundwater contamination. PTA was isolated from Bracken. The logarithmic octanol-water and ethyl acetate-water partitioning coefficients for PTA were -0.63 and -0.88, respectively, in agreement with the high water solubility of the compound. PTA hydrolysed rapidly in aqueous solution at pH 4 or lower, but was stable above pH 4. Incubation of PTA with 10 different soils at 25 degrees C showed three different first order degradation patterns: (i) rapid degradation observed for acid sandy soils with half life's ranging between 8 and 30 h decreasing with the soil content of organic matter, (ii) slow degradation in less acid sandy soils with half-lives of several days, and (iii) fast initial degradation with a concurrent solid phase-water partitioning reaction observed for non-acid, mostly clayey soils. The presence of clay silicates appears to retard the degradation of PTA, possibly through sorption. Degradation at 4 degrees C was generally of type (iii) and degradation rates were up to 800 times lower than at 25 degrees C. Sorption isotherms for the same set of soils were almost linear and generally showed very low sorption affinity with distribution coefficients in the range 0.01-0.22 l kg(-1) at a solution concentration of 1 mg l(-1) except for the most acid soil; Freundlich affinity coefficients increased linearly with clay and organic matter contents. Negligible sorption was also observed in column studies where PTA and a non-sorbing tracer showed almost coincident break-through. Leaching of PTA to the aqueous environment will be most extensive on sandy soils, having pH >4 and poor in organic matter which are exposed to high precipitation rates during cold seasons. 相似文献
59.
Joy RW Heirigs PL Torgerson GD St Denis M Austin TC Gordon J Tefft B Lindner J 《Journal of the Air & Waste Management Association (1995)》2004,54(3):269-285
A series of studies was performed to develop an alternative to the U.S. Environmental Protection Agency's gold standard IM240 mass-based emission test. The new IM147 test was based on the second phase of the IM240 that consists of 147 sec of transient vehicle operation. Paired IM240/IM147 tests were conducted on vehicles ranging from 1981 to 1996 to determine IM147 cutpoints and excess emissions were identified. Additionally, an optimized test procedure was developed that combined possible triplicate IM147s with improved drive trace quality control, fast-pass, and retest methods. The optimized procedure was found to provide improved vehicle preconditioning with a relatively minor decrease in excess emissions identification. Resulting identification rates ranged from 96 to 100% for hydrocarbons (HC), 93-100% for CO, and 93-100% for NOx, depending on cutpoint selection, while false failures caused by lack of vehicle preconditioning were reduced to essentially zero. Significant vehicle throughput improvements were achieved through the development of software algorithms involving modal fast-pass and retest procedures. Modal drive trace variation limits also were developed to improve test accuracy. The combination of the algorithms reduced average IM147 test times by nearly 60%. 相似文献