Plastic deformation mediated by collective dislocation dynamics is investigated in the two-dimensional phase-field crystal model of sheared single crystals. We find that intermittent fluctuations in the dislocation population number accompany bursts in the plastic strain-rate fluctuations. Dislocation number fluctuations exhibit a power-law spectral density 1/f2 at high frequencies f. The proba...

The population demography of the northern short-tailed shrew, Blarina brevicauda (Say, 1823), was studied for 25 years in bluegrass, alfalfa, and tallgrass habitats in east-central Illinois. The population in bluegrass had higher over-winter population density, began increasing earlier in the year, peaked earlier in the year, had higher mean monthly densities and amplitudes of fluctuation, and ...

Molecular evolution is a stochastic process governed by fitness, mutations, and reproductive fluctuations in a population. Here, we study evolution where fitness itself is stochastic, with random switches in the direction of selection at individual genomic loci. As the correlation time of these fluctuations becomes larger than the diffusion time of mutations within the population, fitness chang...

Evaluating the relative importance of ecological drivers responsible for natural population fluctuations in size is challenging. Longitudinal studies where most individuals are monitored from birth to death and where environmental conditions are known provide a valuable resource to characterize complex ecological interactions. We used a recently developed approach to decompose the observed fluc...

We investigate the dependence of solar wind fluctuations measured by the Wind spacecraft on scale and on the degree of alignment between oppositely directed Elsasser fields. This alignment controls the strength of the nonlinear interactions and, therefore, the turbulence. We find that at scales larger than the outer scale of the turbulence the Elsasser fluctuations become on average more antial...

Numerous studies have shown that neuronal responses are modulated by stimulus properties and also by the state of the local network. However, little is known about how activity fluctuations of neuronal populations modulate the sensory tuning of cells and affect their encoded information. We found that fluctuations in ongoing and stimulus-evoked population activity in primate visual cortex modul...

We study the effects of demographic stochasticity on the long-term dynamics of biological coevolution models of community assembly. The noise is induced in order to check the validity of deterministic population dynamics. While mutualistic communities show little dependence on the stochastic population fluctuations, predator-prey models show strong dependence on the stochasticity, indicating th...

The population of the brown planthopper Nilaparvata lugens (Stål) in temperate regions is characterized by discrete periods of seasonal appearance, low initial density, steep and steady growth, clumped spatial distribution, and violent fluctuations from year to year. N. lugens, a temporary inhabitant, arrives from long distances barely in the ricegrowing season. Its high potential fecundity, hi...

We propose a general model to study the interplay between spatial dispersal and environment spatiotemporal fluctuations in metapopulation dynamics. An ecological landscape of favorable patches is generated like a Lévy dust, which allows to build a range of patterns, from dispersed to clustered ones. Locally, the dynamics is driven by a canonical model for the time evolution of the population de...

Abstract Environmental fluctuations can create population-depleted areas and even extinct for the population. This effect is more severe in presence of Allee (decreasing growth rate at low population densities). Dispersal inside habitat provides a rescue on areas, enhancing resilience to environmental fluctuations. Habitat reduction decreases effectiveness dispersal mechanism. We report here ho...