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11.
The primary targets of steroid hormones are genes. For the ecdysone-controlled genes of Drosophila larval glue proteins proximal and distal control elements were identified by mutagenesis and sequence comparison. Their presence is required for the correct stage- and tissue-specific expression of these genes. The supposed function of these elements is described in a working model.  相似文献   
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13.
In this study, we followed the chemical changes occurring in coal ash exposed to prolonged (300 days), large scale, contact with running seawater. Four major components (Al, Ca, Mg, Fe) and seven minor and trace elements (Cd, Cr, Cu, Mn, Zn, Pb, Hg) were measured in four coal ash types: fly and bottom ash freshly obtained from coal-fired power plant, and old ash (crushed and blocks) recovered from the sea after 3-5 years contact with seawater. Changes occurred in the chemical composition of the coal ash along the experiment: Fe increased in fresh ash, Al increased in old ash and Ca increased in all ash types except old ash blocks. Cu and Hg decreased in fresh fly ash while Cr increased, Cd decreased in all ash types except bottom ash, and Mn decreased in bottom ash. Most of the changes occurred in the fresh fly ash, and not in the old ash, indicating equilibrium after prior exposure to seawater. In addition, more changes occurred in fresh fly ash than in bottom ash, emphasizing the differences between the two ash types. While the changes in the concentrations of the major elements may be an indication of the integrity of the ash matrix, the only elements of environmental significance released to the environment were Hg and Cd. However, calculated seawater concentrations were much lower than seawater quality criteria and therefore the coal ash was considered suitable for marine applications concerning seawater quality.  相似文献   
14.
ABSTRACT: Cowpies molded to a standard configuration and size were subjected to simulated rainfall, and the fecal coliform counts were determined using the most probable number (MPN) method of enumeration. The standard cowpie deposits were exposed to simulated rainfall once at ages 2 through 100 days. The effects of rainfall intensity and recurrent rainfall were also tested. Naturally-occurring fecal deposits were also tested to compare their results with those from the standard cowpies. A log-log regression was found to describe the decline in peak fecal coliform release with fecal deposit age. The 100-day-old fecal deposits produced peak counts of 4,200 fecal coliform per 100 milliliters of water. This quantity of release is minimal compared to the release from fresher fecal material. Rainfall intensity had little effect on peak fecal coliform release from fecal deposits that were 2 or 10 days old. At age 20 days the effect of rainfall intensity was significant; the highest intensity gave the lowest peak counts, and the lowest intensity gave the highest peak counts. The effect of rainfall intensity appears to be related to the dryness of the fecal deposits. Peak fecal coliform counts were significantly lowered when the fecal deposits were rained on more than once. This decline was thought to be produced by the loss of bacteria from the fecal deposits during the previous wettings. Standard cowpies produced a peak release regression that was not significantly different from the regression for the natural fecal deposits. Apparently, grossly manipulating the fecal deposits did not significantly change the release patterns.  相似文献   
15.
Coal fly ash (CFA) is dumped at a deep sea disposal site (1,500m water depth) in the eastern Mediterranean, ca. 70km off the Israeli shore. Since 1989, about one million tons of CFA were dumped at the 200km2 allocated area. Six years of monitoring at the dump-site shows that the CFA is heterogeneously distributed; there are areas where CFA covers about 1.3cm depth of the sea floor while at others no CFA is found. CFA is present as a fine powder, small aggregates and even as large blocks both in the dump-site as well as at its peripheries. Cadmium, copper and zinc concentrations in the CFA decreased as a result of the prolonged contact with sea water at in situ conditions while inconclusive changes in mercury, iron and manganese were detected. No changes were observed for lead, iron and aluminium concentrations. A controlled long term field experiment, now in progress at the site, is expected to clarify further chemical changes occurring in the CFA.  相似文献   
16.
ABSTRACT: A stage-activated triggering device was developed for automatic pumping samplers. The device consists of a proximity switch and ten magnets mounted radially at equal intervals on a plexiglass disk. The triggering device allows discrete sampling of stream water at 3.0 cm intervals of stage. The trigger proved dependable during two years of use at three headwater streams in the Ouachita Mountains of southeastern Oklahoma.  相似文献   
17.
Coal fly ash (CFA) is dumped at a deep sea disposal site (1,500m water depth) in the eastern Mediterranean, ca. 70km off the Israeli shore. Since 1989, about one million tons of CFA were dumped at the 200km2 allocated area. Six years of monitoring at the dump-site shows that the CFA is heterogeneously distributed; there are areas where CFA covers about 1.3cm depth of the sea floor while at others no CFA is found. CFA is present as a fine powder, small aggregates and even as large blocks both in the dump-site as well as at its peripheries. Cadmium, copper and zinc concentrations in the CFA decreased as a result of the prolonged contact with sea water at in situ conditions while inconclusive changes in mercury, iron and manganese were detected. No changes were observed for lead, iron and aluminium concentrations. A controlled long term field experiment, now in progress at the site, is expected to clarify further chemical changes occurring in the CFA.  相似文献   
18.
The degree to which turnover in biological communities is structured by deterministic or stochastic factors and the identities of influential deterministic factors are fundamental, yet unresolved, questions in ecology. Answers to these questions are particularly important for projecting the fate of forests with diverse disturbance histories worldwide. To uncover the processes governing turnover we use species-level molecular phylogenies and functional trait data sets for two long-term tropical forest plots with contrasting disturbance histories: one forest is older-growth, and one was recently disturbed. Having both phylogenetic and functional information further allows us to parse out the deterministic influences of different ecological filters. With the use of null models we find that compositional turnover was random with respect to phylogeny on average, but highly nonrandom with respect to measured functional traits. Furthermore, as predicted by a deterministic assembly process, the older-growth and disturbed forests were characterized by less than and greater than expected functional turnover, respectively. These results suggest that the abiotic environment, which changes due to succession in the disturbed forest, strongly governs the temporal dynamics of disturbed and undisturbed tropical forests. Predicting future changes in the composition of disturbed and undisturbed forests may therefore be tractable when using a functional-trait-based approach.  相似文献   
19.
Urbanization dynamics are commonly subjected to powerful market forces, only partly managed by land-use plans. The density, location and pattern of urbanized areas affect rainfall-runoff relations. Consequently, it is essential to understand future impacts of urbanization on runoff and produce focused regulation. The goal was to analyze land-cover scenarios and their impact on runoff in an urbanized watershed in Israel. Present and predicted land-cover scenarios in a densely populated watershed were produced. The runoff response to rainfall was then simulated using a hydrological model. The impact of implementing afforestation and quarrying national outline plans was considered. By the year 2050, 50% of the watershed will be urbanized with a linear increase in runoff response. Afforestation and quarrying plans show little effect on runoff, although quarries may decrease runoff through percolation. As urbanization is expected to continue spreading in adjacent watersheds, statutory measures should be applied to mitigating runoff.  相似文献   
20.
Using questionnaire and interview data, this study attempted to find out whether the organizational loose (participative) and tight (directive) practices are compatible with or contradict each other. Using the theoretical framework of Sagie's ( 1997 ) loose–tight leadership approach, our hypotheses concerned the effects of both practices on the employee's work‐related attitudes, and the mediating role of two variables, cognitive (information sharing) and motivational (exerting effort), in these effects. Data were analysed using two methodological approaches, quantitative and qualitative. Based on a quantitative analysis of the questionnaires given to 101 professional employees of a textile company, partial support was provided for the study hypotheses. A qualitative analysis of in‐depth, semi‐structured interviews with all the employees (n = 20) in one of the company divisions led to similar conclusions. Specifically, we found that although the loose and tight practices affected work attitudes, the interviewees attributed more impact to the tight practice. In addition, none of the study variables mediated the loose impact on attitudes, whereas information sharing (but not exerting effort) mediated the influence of tight practice. Finally, the qualitative analysis revealed a deeper insight into the nature of both leader practices and their possible integration in the decision‐making processes in organizations. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
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