Search results for "Dominance"
showing 10 items of 360 documents
The orophilous communities of the Pino-Juniperetea class in the Central and Eastern Mediterranean area
2001
Orophilous plant communities of the Pino-Juniperetea class, occurring in the Central and Eastern Mediterranean area, are examined. This vegetation is characterized by the dominance of trees and shrubs, mostly represented by conifers belonging to the genera Juniperus, Abies and Pinus. These communities are nowadays relegated to the supra- and oromediterranean belt, and show a fragmentary distribution, which is an evident proof of their relict connotation. The comparison among these communities, based on original and literature data, has highlighted a remarkable floristic and structural homogeneity, together with a series of geographical vicariances. From the phytosociological point of view, …
<strong>Microhabitat preference of caddisfly (Trichoptera) communities in a medium-sized lowland stream in Latvia</strong>
2011
The microhabitat preference of caddisfly (Trichoptera) communities was studied in 8 types of microhabitats in a fast-flowing, medium-sized, lowland stream in Latvia. A total 36 caddisfly taxa belonging to 14 families were recorded in microhabitat samples. A PCA biplot of caddisfly taxa abundance in microhabitats showed 3 distinct caddisfly taxa groups: depositional [Limnephilidae Gen. sp., Anabolia laevis (Zetterstedt) and Lasiocephala basalis (Kolenati)], lithal [ Agapetus ochripes Curtis and Psychomyia pusilla (Fabricius)], and submerged macrophyte and water moss caddisfly microhabitat communities ( Ithytrichia lamellaris Eaton, Hydropsyche siltalai Dohler and Hydropsyche spp. juv.). The …
Changes in community composition determine recovery trajectories from multiple agricultural stressors in freshwater ecosystems
2020
AbstractPesticides have been identified worldwide as a threat for aquatic biodiversity due to their widespread use in agriculture and their capacity to reach freshwater ecosystems. Very little is known about the consequences of pesticide mixtures targeting different organism groups on community dynamics. Especially, how horizontal changes within one trophic level are propagated vertically across the food web has been rarely investigated. To get insight on the effects of pesticide mixtures on community dynamics, we performed a mesocosm experiment manipulating three common agricultural stressors: chlorpyrifos (an insecticide), diuron (an herbicide) and nutrients. The results of this study sho…
The fall and the fragmentation of national clusters: Cluster evolution in the paper and pulp industry
2012
Abstract A common expectation in evolutionary cluster studies is that national clusters engage in competitive interactions that lead to a continuous stream of changes in global dominance. Our fuzzy-set analysis on the evolution of the paper and pulp industry demonstrates that globalization has dramatically changed this situation. National clusters have largely faded away; the value chain dominance is now held by technology suppliers who are global hubs in majority of identifiable business activities in the focal industry. Our results imply that when industrial decline is accentuated by industrial concentration in some part of the value chain the national clusters may lose their importance.
Rising Educational Attainment and Opportunity Equalization: Evidence from France
2020
Educational policies are widely recognized as the means par excellence to equalize opportunities among children with different social and family backgrounds and to promote intergenerational mobility. In this chapter, we focus on the French case and we apply the opportunity equalization criterion proposed by Andreoli, Havnes, and Lefranc (2019) for evaluating the effect of rising compulsory schooling requirements in secondary education. Our results show that such education expansion has a limited redistributive effect on students’ earnings distribution. Nonetheless, we provide evidence of opportunity equalization among groups of students defined by family background circumstances.
Weak versus strong dominance of shrinkage estimators
2021
We consider the estimation of the mean of a multivariate normal distribution with known variance. Most studies consider the risk of competing estimators, that is the trace of the mean squared error matrix. In contrast we consider the whole mean squared error matrix, in particular its eigenvalues. We prove that there are only two distinct eigenvalues and apply our findings to the James–Stein and the Thompson class of estimators. It turns out that the famous Stein paradox is no longer a paradox when we consider the whole mean squared error matrix rather than only its trace.
Region vs. Industry Effects and Volatility Transmission
2006
This article presents an analysis of the relative importance of region versus industry effects in stock returns, as opposed to the extensively analyzed country versus industry effects. The sample includes the period after the bursting of the technology bubble. Moreover, volatility transmission patterns are analyzed within an industry across regions to assess whether the same international links found in aggregate stock market indices exist at the industry level. The results confirm the dominance of region effects over industry effects, except during the bubble period. The results of the volatility transmission analysis suggest that the importance of spillovers depends on the industry.
Measuring the presence of organized crime across Italian provinces: a sensitivity analysis
2020
AbstractThe existing literature identifies different indicators to construct organized crime indices and places equal importance to different concepts of organized crime. This paper examines the sensitivity of organized crime across Italian provinces when different set of indicators and weights are used to combine crime indicators. Our findings suggest that there is a remarkable variation in the distribution of organized crime across Italian provinces based on the choice of indicators and the importance given to different crime indicators. It is also found that the relationship of organized crime with socioeconomic and political factors varies depending on the normative choices made in the …
Does Firm Size Affect Self-selection and Learning-by-Exporting?
2010
The trade literature has long discussed the existence of some benefits attributed to exporting, among others, the improvement of firm productivity. This paper examines whether firm size plays a role in this supposedly favourable relationship between exporting and total factor productivity (TFP). To examine this, we investigate, separately for large and small firms, whether firms starting to export perform better ex ante (self-selection) than non-exporting firms and, conditional on this fact, if they are also more productive ex post (learning-by-exporting). With this purpose, we use both stochastic dominance and matching techniques. The dataset is a representative sample of Spanish manufactu…
Integration and competition in the European financial markets
2007
Financial integration in Europe should affect the competition between markets and intermediaries and generate a convergence of both interest rates and margins among the different countries. This paper analyses the evolution of the convergence in interest rates and the level of competition and its inequalities among the European banking systems for the period 1993 to 2001. The inequality index used ?the Theil index- allows us to break down the inequalities so that the importance of either a country effect or a specialization effect is quantified. If the former effect dominates it would mean that the national banking markets are segmented as a consequence of the existence of obstacles or barr…