Search results for " network"
showing 10 items of 6428 documents
The consistency of individual centrality across time and networks in wild vervet monkeys
2021
Previous primate social network studies largely limited their focus to grooming and/or aggression networks, particularly among adult females. In addition, the consistency of individuals' network centrality across time and/or different networks has received little attention, despite this being critical for a global understanding of dynamic social structure. Here, we analyzed the grooming, aggression, and play social networks of a group of 26-28 wild vervet monkeys (Chlorocebus pygerythrus), including adults and juveniles, over two periods of 6 months. We collected data on grooming, play, and aggression using focal animal sampling with instantaneous recording and ad libitum sampling. We exami…
Identifying small pelagic Mediterranean fish schools from acoustic and environmental data using optimized artificial neural networks
2019
Abstract The Common Fisheries Policy of the European Union aims to exploit fish stocks at a level of Maximum Sustainable Yield by 2020 at the latest. At the Mediterranean level, the General Fisheries Commission for the Mediterranean (GFCM) has highlighted the importance of reversing the observed declining trend of fish stocks. In this complex context, it is important to obtain reliable biomass estimates to support scientifically sound advice for sustainable management of marine resources. This paper presents a machine learning methodology for the classification of pelagic species schools from acoustic and environmental data. In particular, the methodology was tuned for the recognition of an…
Novel Wood Resistance Measurement Method Reducing the Initial Transient Instabilities Arising in DC Methods Due to Polarization Effects
2019
A novel method for measuring the electrical resistance in wood is presented. It is based on applying an Alternating Current (AC) to two electrodes rammed into the wood. The method reduces the transient time for value stabilization. In case of Direct Current (DC) resistance measurement methods, typically used in wood measurement, an initial transient exists, invalidating the measured value during an initial transient period. This measurement method uses an electronic circuit based on a relaxation oscillator where the wood automatically sets the oscillation frequency depending on its electrical resistance. Compared to other AC methods, this circuit greatly simplifies the measurement process, …
Systematic analysis of specific and nonspecific auxin effects on endocytosis and trafficking.
2021
Abstract The phytohormone auxin and its directional transport through tissues are intensively studied. However, a mechanistic understanding of auxin-mediated feedback on endocytosis and polar distribution of PIN auxin transporters remains limited due to contradictory observations and interpretations. Here, we used state-of-the-art methods to reexamine the auxin effects on PIN endocytic trafficking. We used high auxin concentrations or longer treatments versus lower concentrations and shorter treatments of natural indole-3-acetic acid (IAA) and synthetic naphthalene acetic acid (NAA) auxins to distinguish between specific and nonspecific effects. Longer treatments of both auxins interfere wi…
Mycorrhizae differentially influence the transfer of nitrogen among associated plants and their competitive relationships
2021
Abstract The formation of a common mycorrhizal network among roots of different plant species growing close to each other can influence plant community dynamics, regulating plant relationships through the differential transfer of nutrients from one plant to another. However, knowledge of the mechanisms that regulate this process is poor. Here we quantify the contribution of arbuscular mycorrhizae to the transfer of N among heterospecific plants growing adjacent to each other and examine whether the differential transfer of N within the plant community via mycorrhizae can alter competitive relationships among plant species. Plants of four species (wheat, pea, flax, and chicory) were grown in…
The role of fish life histories in allometrically scaled food‐web dynamics
2019
Body size determines key ecological and evolutionary processes of organisms. Therefore, organisms undergo extensive shifts in resources, competitors, and predators as they grow in body size. While empirical and theoretical evidence show that these size‐dependent ontogenetic shifts vastly influence the structure and dynamics of populations, theory on how those ontogenetic shifts affect the structure and dynamics of ecological networks is still virtually absent. Here, we expand the Allometric Trophic Network (ATN) theory in the context of aquatic food webs to incorporate size‐structure in the population dynamics of fish species. We do this by modifying a food web generating algorithm, the nic…
An early Ca2+ influx is a prerequisite to thaxtomin A-induced cell death in Arabidopsis thaliana cells
2008
International audience; The pathogenicity of various Streptomyces scabies isolates involved in potato scab disease was correlated with the production of thaxtomin A. Since calcium is known as an essential second messenger associated with pathogen-induced plant responses and cell death, it was investigated whether thaxtomin A could induce a Ca 2+ influx related to cell death and to other putative plant responses using Arabidopsis thaliana suspension cells, which is a convenient model to study plant–microbe interactions. A. thaliana cells were treated with micromolar concentrations of thaxto-min A. Cell death was quantified and ion flux variations were analysed from electrophysiological measu…
Ecological dependencies make remote reef fish communities most vulnerable to coral loss
2021
Ecosystems face both local hazards, such as over-exploitation, and global hazards, such as climate change. Since the impact of local hazards attenuates with distance from humans, local extinction risk should decrease with remoteness, making faraway areas safe havens for biodiversity. However, isolation and reduced anthropogenic disturbance may increase ecological specialization in remote communities, and hence their vulnerability to secondary effects of diversity loss propagating through networks of interacting species. We show this to be true for reef fish communities across the globe. An increase in fish-coral dependency with the distance of coral reefs from human settlements, paired with…
A Network Model for the Correlation between Epistasis and Genomic Complexity
2008
The study of genetic interactions (epistasis) is central to the understanding of genome organization and evolution. A general correlation between epistasis and genomic complexity has been recently shown, such that in simpler genomes epistasis is antagonistic on average (mutational effects tend to cancel each other out), whereas a transition towards synergistic epistasis occurs in more complex genomes (mutational effects strengthen each other). Here, we use a simple network model to identify basic features explaining this correlation. We show that, in small networks with multifunctional nodes, lack of redundancy, and absence of alternative pathways, epistasis is antagonistic on average. In c…
Reconstruction and analysis of genome-scale metabolic model of a photosynthetic bacterium
2010
Abstract Background Synechocystis sp. PCC6803 is a cyanobacterium considered as a candidate photo-biological production platform - an attractive cell factory capable of using CO2 and light as carbon and energy source, respectively. In order to enable efficient use of metabolic potential of Synechocystis sp. PCC6803, it is of importance to develop tools for uncovering stoichiometric and regulatory principles in the Synechocystis metabolic network. Results We report the most comprehensive metabolic model of Synechocystis sp. PCC6803 available, iSyn669, which includes 882 reactions, associated with 669 genes, and 790 metabolites. The model includes a detailed biomass equation which encompasses…