On the notion "strength" of coarticulation

No abstrac

Hard-core Yukawa model for two-dimensional charge stabilized colloids

The hyper-netted chain (HNC) and Percus-Yevick (PY) approximations are used to study the phase diagram of a simple hard-core Yukawa model of charge-stabilized colloidal particles in a two-dimensional system. We calculate the static structure factor and the pair distribution function over a wide range of parameters. Using the statics correlation functions we present an estimate for the liquid-solid phase diagram for the wide range of the parameters.Comment: 7 pages, 9figure

Entropy-induced smectic phases in rod-coil copolymers

We present a self-consistent field theory (SCFT) of semiflexible (wormlike) diblock copolymers, each consisting of a rigid and a flexible part. The segments of the polymers are otherwise identical, in particular with regard to their interactions, which are taken to be of an Onsager excluded-volume type. The theory is developed in a general three-dimensional form, as well as in a simpler one-dimensional version. Using the latter, we demonstrate that the theory predicts the formation of a partial-bilayer smectic-A phase in this system, as shown by profiles of the local density and orientational distribution functions. The phase diagram of the system, which includes the isotropic and nematic phases, is obtained in terms of the mean density and rigid-rod fraction of each molecule. The nematic-smectic transition is found to be second order. Since the smectic phase is induced solely by the difference in the rigidities, the onset of smectic ordering is shown to be an entropic effect and therefore does not have to rely on additional Flory-Huggins-type repulsive interactions between unlike chain segments. These findings are compared with other recent SCFT studies of similar copolymer models and with computer simulations of several molecular models.Comment: 13 pages, 8 figure

3D Spinodal Decomposition in the Inertial Regime

We simulate late-stage coarsening of a 3D symmetric binary fluid using a lattice Boltzmann method. With reduced lengths and times l and t respectively (scales set by viscosity, density and surface tension) our data sets cover 1 < l 100 we find clear evidence of Furukawa's inertial scaling (l ~ t^{2/3}), although the crossover from the viscous regime (l ~ t) is very broad. Though it cannot be ruled out, we find no indication that Re is self-limiting (l ~ t^{1/2}) as proposed by M. Grant and K. R. Elder [Phys. Rev. Lett. 82, 14 (1999)].Comment: 4 pages, 3 eps figures, RevTex, minor changes to bring in line with published version. Mobility values added to Table

Tests of Dynamical Scaling in 3-D Spinodal Decomposition

We simulate late-stage coarsening of a 3-D symmetric binary fluid. With reduced units l,t (with scales set by viscosity, density and surface tension) our data extends two decades in t beyond earlier work. Across at least four decades, our own and others' individual datasets (< 1 decade each) show viscous hydrodynamic scaling (l ~ a + b t), but b is not constant between runs as this scaling demands. This betrays either the unexpected intrusion of a discretization (or molecular) lengthscale, or an exceptionally slow crossover between viscous and inertial regimes.Comment: Submitted to Phys. Rev.

Analysis of a spatial Lotka-Volterra model with a finite range predator-prey interaction

We perform an analysis of a recent spatial version of the classical Lotka-Volterra model, where a finite scale controls individuals' interaction. We study the behavior of the predator-prey dynamics in physical spaces higher than one, showing how spatial patterns can emerge for some values of the interaction range and of the diffusion parameter.Comment: 7 pages, 7 figure

Consistent oviposition preferences of the Duke of Burgundy butterfly over 14 years on a chalk grassland reserve in Bedfordshire, UK

Funder: Christ's College, University of Cambridge (GB)Funder: Isaac Newton Trust; doi: http://dx.doi.org/10.13039/501100004815Funder: Museums Association and Esmée Fairbairn Collections Fund (GB)Abstract: The Duke of Burgundy butterfly (Hamearis lucina) is known to have specific habitat requirements for its larval foodplants. However, no studies have yet investigated whether these preferences vary over time or in relation to climate, and there is a paucity of data on whether management on reserves can replicate preferred conditions. Here, we build upon existing research to confirm which characteristics Duke of Burgundy prefer for their larval foodplants, whether preferences remain consistent across years, and whether conservation management on reserves can replicate these conditions. Fieldwork was carried out at Totternhoe Quarry Reserve, a chalk grassland site in Bedfordshire, UK. Confirming previous research, we found that large Primula plants in dense patches were chosen for oviposition, but that once chosen there was no preference to lay eggs on a plant’s largest leaf. Chosen foodplants were also more sheltered and in closer proximity to scrub than their controls. However, at a finer scale, we found little evidence for any preference based on differences in microclimate, or vegetation height immediately surrounding the plants. This suggests features that alter microclimatic conditions at a larger scale are relatively more important for determining the suitability of oviposition sites. Nearly all preferences remained consistent over time and did not vary between years. Management of scrub on the reserve was able to reproduce some preferred habitat features (high plant density), but not others (large plant size). Implications for insect conservation: The consistency of findings across years, despite inter-annual variation in temperature, rainfall and number of adults, indicates that the Duke of Burgundy is conservative in its foodplant choice, highlighting its need for specific habitat management. Targeted management for foodplants could form part of a tractable set of tools to support Duke of Burgundy numbers on reserves, but a careful balance is needed to avoid scrub clearance leaving plants in sub-optimal conditions

Effects of noise on convergent game learning dynamics

We study stochastic effects on the lagging anchor dynamics, a reinforcement learning algorithm used to learn successful strategies in iterated games, which is known to converge to Nash points in the absence of noise. The dynamics is stochastic when players only have limited information about their opponents' strategic propensities. The effects of this noise are studied analytically in the case where it is small but finite, and we show that the statistics and correlation properties of fluctuations can be computed to a high accuracy. We find that the system can exhibit quasicycles, driven by intrinsic noise. If players are asymmetric and use different parameters for their learning, a net payoff advantage can be achieved due to these stochastic oscillations around the deterministic equilibrium.Comment: 17 pages, 8 figure