Search results for "Community structure"
showing 10 items of 163 documents
The rotifer community and its functional role in lakes of a neotropical floodplain
2014
Aquatic communities vary depending on local factors, such as environmental conditions and biological interactions and regional factors, such as the hydrological regime in floodplains. This study analyzed the community structure of rotifers and their secondary production in two lakes of an Upper Parana River floodplain (Brazil) differing in their hydrology: one connected to the river and the other isolated. Integrated samples of the water column were collected daily during 15 days in the low and high water periods. Three statistical methods, ANOVA, MRT, and IndVal were applied to distinguish the structure, biomass, and secondary production of their rotifer communities. The rotifer fauna was …
Investigating Centrality Measures in Social Networks with Community Structure
2021
Centrality measures are crucial in quantifying the influence of the members of a social network. Although there has been a great deal of work dealing with this issue, the vast majority of classical centrality measures are agnostic of the community structure characterizing many social networks. Recent works have developed community-aware centrality measures that exploit features of the community structure information encountered in most real-world complex networks. In this paper, we investigate the interactions between 5 popular classical centrality measures and 5 community-aware centrality measures using 8 real-world online networks. Correlation as well as similarity measures between both t…
The Community Structure of the Global Corporate Network
2013
We investigate the community structure of the global ownership network of transnational corporations. We find a pronounced organization in communities that cannot be explained by randomness. Despite the global character of this network, communities reflect first of all the geographical location of firms, while the industrial sector plays only a marginal role. We also analyze the network in which the nodes are the communities and the links are obtained by aggregating the links among firms belonging to pairs of communities. We analyze the network centrality of the top 50 communities and we provide the first quantitative assessment of the financial sector role in connecting the global economy.
Region Community in Communication Theory
2014
The aim of the report is to determine how local and regional newspapers represent local communities and how their communicative integration has been promoted. Mass media, establishing community cognition about its existence, involvement into the community, identification and belonging to the community, represent a perfect model of interaction between community and communication. During the content analysis of the press publications of local newspapers of Latgale region the typological characteristics and classification are emphasized, the role of the press in the development of the region inhabitants is defined, the direction and structure of the editorial board activities, newspapers’ cont…
Backbone Extraction of Weighted Modular Complex Networks based on their Component Structure
2023
This work introduces a generic backbone extraction framework exploiting the mesoscopic network structure. Indeed, numerous real-world networks are made of dense groups of nodes called communities, multi-core or local components. To deal with these groups' heterogeneity, we propose to extract the backbones independently from their various components and fuse them. Experimental investigations on real-world networks demonstrate the effectiveness of the proposed approach compared to the classical techniques' agnostic of the mesoscopic structure of real-world networks.
Extracting modular-based backbones in weighted networks
2021
Abstract Networks are an adequate representation for modeling and analyzing a great variety of complex systems. However, understanding networks with millions of nodes and billions of connections can be pretty challenging due to memory and time constraints. Therefore, selecting the relevant nodes and edges of these large-scale networks while preserving their core information is a major issue. In most cases, the so-called backbone extraction methods are based either on coarse-graining or filtering approaches. Coarse-graining techniques reduce the network size by gathering similar nodes into super-nodes, while filter-based methods eliminate nodes or edges according to a statistical property.In…
An Efficient Immunization Strategy Using Overlapping Nodes and Its Neighborhoods
2018
International audience; When an epidemic occurs, it is often impossible to vaccinate the entire population due to limited amount of resources. Therefore, it is of prime interest to identify the set of influential spreaders to immunize, in order to minimize both the cost of vaccine resource and the disease spreading. While various strategies based on the network topology have been introduced, few works consider the influence of the community structure in the epidemic spreading process. Nowadays, it is clear that many real-world networks exhibit an overlapping community structure, in which nodes are allowed to belong to more than one community. Previous work shows that the numbers of communit…
Community Turnover of Wood-Inhabiting Fungi across Hierarchical Spatial Scales
2014
For efficient use of conservation resources it is important to determine how species diversity changes across spatial scales. In many poorly known species groups little is known about at which spatial scales the conservation efforts should be focused. Here we examined how the community turnover of wood-inhabiting fungi is realised at three hierarchical levels, and how much of community variation is explained by variation in resource composition and spatial proximity. The hierarchical study design consisted of management type (fixed factor), forest site (random factor, nested within management type) and study plots (randomly placed plots within each study site). To examine how species richne…
Warmer climates boost cyanobacterial dominance in shallow lakes
2011
Dominance by cyanobacteria hampers human use of lakes and reservoirs worldwide. Previous studies indicate that excessive nutrient loading and warmer conditions promote dominance by cyanobacteria, but evidence from global scale field data has so far been scarce. Our analysis, based on a study of 143 lakes along a latitudinal transect ranging from subarctic Europe to southern South America, shows that although warmer climates do not result in higher overall phytoplankton biomass, the percentage of the total phytoplankton biovolume attributable to cyanobacteria increases steeply with temperature. Our results also reveal that the percent cyanobacteria is greater in lakes with high rates of ligh…
Spatial and temporal changes in Actinobacterial dominance in experimental artificial groundwater recharge.
2008
Abstract Artificial groundwater recharge (AGR) is used in the drinking water industry to supplement groundwater resources and to minimise the use of chemicals in water treatment. This study analysed the spatial and temporal changes of microbial communities in AGR using two test systems: a nutrient-amended fluidized-bed reactor (FBR) and a sand column. Structural changes in the feed lake water (Lake Roine), FBR, and sand column bacterial communities were determined by denaturing gradient gel electrophoresis (DGGE) and the length heterogeneity analysis of amplified 16S rRNA genes (LH-PCR). Two clone libraries were created to link the LH-PCR results to the dominant bacterial groups. The lake w…