Studies were carried out in two mining pond complexes in an industrial landscape. The first complex (consisting of six ponds) was located in an urban area and the second one (consisting of six ponds) in a woodland area. The aims of the study were to assess the diversity of benthic oligochaetes and to evaluate which environmental variables are most important in determining variations in the community structure in ponds of varying location. In total, 21 oligochaete species were recorded (7–11 in the urban ponds, 11–15 in the woodland ponds). Aulodrilus pluriseta, Aulodrilus japonicus and Ophidonais serpentina were only found in the woodland ponds, while Potamothrix bavaricus only occurred in the urban ponds. Limnodrilus hoffmeisteri, Limnodrilus claparedeanus, Chaetogaster diaphanus and Ophidonais serpentina dominated in the woodland ponds, whereas Limnodrilus hoffmeisteri, Limnodrilus claparedeanus, Potamothrix bavaricus and Tubifex tubifex prevailed in the urban ponds. The total density of oligochaetes was higher in the urban ponds thought the values of the diversity indices were higher in the woodland ponds. The local diversity of the ponds was high, while the among-site diversity made only a small contribution to the regional diversity. Nonetheless, a cluster analysis divided all of the ponds into two distinct groups depending on their location. CCA analysis showed that conductivity, pH, total hardness, alkalinity, the concentration of chlorides and the content of organic matter in the bottom sediments were most associated with the distribution of some oligochaete species among the ponds studied. 相似文献
Water quality trading (WQT) is a market arrangement in which a point-source water polluter pays farmers to implement conservation practices and claims the resulting benefits as credits toward meeting a pollution permit. Success rates of WQT programs nationwide are highly variable. Most of the literature on WQT is from an economic perspective emphasizing property rights, transaction costs, and the role of the price signal, but this institutional approach cannot fully account for the differential success rates between and within WQT programs. In this paper I turn to the role of social embeddedness and trust in helping explain these variable outcomes. Using interview data from all WQT programs nationwide I demonstrate that differential success rates between, and particularly within programs is largely determined by the presence or absence of a trusted local intermediary with relationships to the farming community. Trust helps WQT programs succeed because it makes information more credible to farmers, makes outreach to farmers more efficient, and buffers the risk that farmers may perceive in participating in the trading scheme. 相似文献
Abstract. After an initial decline in the level of real minimum‐wage rates, there were series of unusually large increases in their levels — 70 and 50 per cent — during the years 1999–2002 in the Czech and Slovak Republics, respectively. Using information from matched employee–employer data sets, we look at the impact of minimum‐wage hikes on both wages and employment. Our results suggest that there are some, but not substantial, job losses in reaction to minimum‐wage hikes and that the impact on firm wages is rather large, implying that further increases of similar magnitude might very well have negative consequences for employment. 相似文献
AbstractThis study investigates three methods to handle dependency among effect size estimates in meta-analysis arising from studies reporting multiple outcome measures taken on the same sample. The three-level approach is compared with the method of robust variance estimation, and with averaging effects within studies. A simulation study is performed, and the fixed and random effect estimates of the three methods are compared with each other. Both the robust variance estimation and three-level approach result in unbiased estimates of the fixed effects, corresponding standard errors and variances. Averaging effect sizes results in overestimated standard errors when the effect sizes within studies are truly independent. Although the robust variance and three-level approach are more complicated to use, they have the advantage that they do not require an estimate of the correlation between outcomes, and they still result in unbiased parameter estimates. 相似文献
In this paper, we investigate the nexus between firm labor diversity and innovation by using data on patent applications filed by firms at the European Patent Office and a linked employer–employee database from Denmark. Exploiting the information retrieved from these comprehensive data sets and implementing proper instrumental variable strategies, we estimate the contribution of workers’ diversity in cultural background, education and demographic characteristics to valuable firm’s innovation activity. Specifically, we find evidence supporting the hypothesis that ethnic diversity may facilitate firms’ patenting activity in several ways by (a) increasing the propensity to (apply for a) patent, (b) increasing the overall number of patent applications, and (c) by enlarging the breadth of patenting technological fields, conditional on patenting. Several robustness checks corroborate the main findings. 相似文献
This paper examines the current youth transition system in Poland focusing on the role of industry partnerships with vocational upper secondary schools. On the example of the aviation cluster in the south-eastern Poland, this paper assesses the strong industry-led partnership established in 2007 with local schools and authorities in delivery of aviation-specific programmes, and its impact of local youth transitions to labour market. In contrast to Poland's national trend towards weak cooperation between industry and the vocational education sector, three major dynamics regarding the aviation cluster's influence on vocational education are observable. The region benefits from: strong leadership from local industry in influencing the supply of particular skills by local vocational education and training (VET) schools and universities; a high level of willingness of local government authorities at the mayor's and municipality's offices to support the aviation cluster's influence on VET; and a free-market model of student choice influencing the practice of local VET schools and training centres. Such cooperation is valuable for businesses and local institutes of education. However, these processes affect the equal chances of successful school-to-work transitions for graduates stratified in different educational pathways, and successful transitions are still constrained by the structure of Poland's system, which is increasingly assuming ‘education logic’. 相似文献
There is a growing interest in intergenerational connectivity through intergenerational programs. In this work, a review of intergenerational programs was performed, with focus on the program design and objectives as well as in their outcomes.
We used a systematic review method in which we screened 3,796 articles. After analyzing titles, abstracts, and full paper analysis, 16 articles were retained. Each study was reviewed, and data were extracted related to target population, study design, characteristics of intervention, outcomes, and effectiveness.
Intergenerational programs included educational programs and art, Information technology development, cultural heritage, health education, and therapeutic activities. Most of the programs collected both quantitative and/or qualitative data. Seven studies collected data in the beginning and at the end of the program. Significant diversity in sample size and intervention length was found. Measurement of outcomes was performed in both young and/or elderly group of participants. Programs impact evaluation varied between studies, including validated scales, interviews, observation, focus groups, and conversation analysis, narratives, videotaped sessions, and field notes.
Our study highlighted the diversity in the design of studies and in the program’s effectiveness evaluation. More randomized design studies are required to support researchers and practitioners in the development of future intergenerational programs. 相似文献
This paper contributes, with a dynamic approach, to the research on the creation of comparable composite indicators by presenting a proposal for an exploratory factor analysis protocol to enable a comparative trend analysis. The originality of the study lies in the three dimensions of information for analysis: observations, variables and units of time. The proposal involves various stages of analysis with the ultimate, albeit not exclusive, aim of obtaining what is known as a Global Dynamic Indicator. The analysis process begins by structuring the data into a three-dimensional global matrix, thereby conditioning, while also, and primarily, enriching the later stages. A combination of multiple factor analysis and a clustering technique is the selected approach for successfully meeting the challenges involved. The appropriateness and versatility of the proposal are validated through the analysis of the trends of the EU member states towards the targets set by the 2020 Strategy. The study period runs from 2009 to 2018. The empirical work enables the visualisation and quantification of trend differences and similarities across member states collectively and individually, and across all the variables and years selected for analysis. The relevant findings will be quantified by means of a synthetic indicator for each unit of time and a global indicator for the period as a whole. Some of the conclusions reached by this paper are consistent with those already published by various authors.