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Traditionally, climate is defined by the properties of the averages of the meteorological fields over an appropriate time interval. In this paper the properties of the time-averaged observables of a red noise atmosphere and of a simplified model of thermal convection are investigated both analytically and numerically and are compared to those of the original finescale variables. It is shown that averaging tends to reduce the domain of variability and the attractor dimension favors persistence of initial correlations and enhances predictability. The implications of these findings in the real-world atmosphere are briefly assessed.

We study the early stages of self-assembly of elementary building blocks of nanophase materials, considering explicitly their structure and the symmetry and the dimensionality of the reaction space. Previous work [Kozak et al., J. Chem. Phys. 134, 154701 (2007)] focused on characterizing self-assembly on small square-planar templates. Here we consider larger lattices of square-planar symmetry having N = 255 sites, and both hexagonal and triangular lattices of N = 256 sites. Furthermore, to assess the consequences of a depletion zone above a basal layer (λ = 1), we study self-assembly on an augmented diffusion space defined by λ = 2 and λ = 5 stacked layers having the same characteristics as the basal plane. The effective decrease in the efficiency of self-assembly of individual nanophase units when the diffusion space is expanded, by increasing the template size and/or by enlarging the depletion zone, is then quantified. The results obtained reinforce our earlier conclusion that the most significant factor influencing the kinetics of formation of a final self-assembled unit is the number of reaction pathways from one or more precursor states. We draw attention to the relevance of these results to zeolite synthesis and reactions within pillared clays. [ABSTRACT FROM AUTHOR]

The early stages of self-assembly of the elementary building blocks of nanophase materials are studied. The relative roles of entropic and energetic factors in determining the relative abundance of the final products present is analyzed using both a kinetic mean field model and a mesoscopic approach in which self-assembly is viewed as an encounter-controlled process on a discrete lattice. The relevance of the results in zeolite synthesis in connection with the ordered liquid phases recently discovered in these materials is discussed. [ABSTRACT FROM AUTHOR]

A minimal model for the NO + H[SUB2] reaction on a Pt emitter tip is proposed, with emphasis placed on surface explosions observed in field ion microscopy experiments. The model is first studied in the mean-field approximation, where it is shown to exhibit bistability and associated explosive phenomena. Using kinetic Monte Carlo simulations, irreversible phase transitions, fluctuation-induced dynamics and reaction front propagation are observed, which are not predicted by the mean-field approach. This comparative study allows to shed some light on the origins of the surface explosions, and to investigate the influence of the discrete nature of the support on the dynamics. [ABSTRACT FROM AUTHOR]

Evaluates thermodynamic entropy production in different parts of the attractor of two representative reactive models giving rise to periodic and chaotic behavior. Variability patterns observed as the system runs over the attractor; Comparison with the variability of indicators of the intrinsic complexity of the dynamics such as the local Lyapunov exponents.

Studies the effects of low-dimensional supports on the steady state and dynamics of open reactive systems capable of giving rise to oscillatory behavior. Development of a lattice Lotka-Volterra model involving reaction, adsorption and desorption mechanisms for which mean-field behavior predicts a continuum of closed trajectories around a center.

Studies the Schlogl-1 and Schlogl-2 models in a spatially extended systems with the aid of a probabilistic cellular automation emulating chemical dynamics in a dispersed medium. Deviation of the steady-state behavior from the deterministic value for Schlogl-1 model; Bifurcations for Schlog1-2 model found under the conditions of intensive stirring and low rate constants.

The stochastic analysis of a chemical system obeying to mass-action kinetics and giving rise to deterministic chaos is carried out using the master equation approach. Quantitative comparison with the predictions of the deterministic description based on the rate equations shows that the system’s attractor and the probabilistic properties are robust toward fluctuations. [ABSTRACT FROM AUTHOR]

Isomerization kinetics is studied on a one-dimensional gas model with deterministic transitions involving an activation threshold. The one-particle functions are found to decay nearly exponentially and their decay is compared to that of phenomenological theories. In the long-time regime, higher correlations present long tails indicating a strongly non-Markovian behavior. The effect of the activation energy in the general behavior is discussed. [ABSTRACT FROM AUTHOR]

Self-avoiding walks in 2-d and 3-d lattices are implemented as models of polymer propagation in confined media like vesicle bilayers and micelles. Simulations conducted on such microreactors of various sizes (total number of monomers Ntot between 80 and 106) and shapes show that the propagation rate essentially depends on the ratio of the degree of polymerization (D.P.) and Ntot. A scaling function is proposed giving excellent agreement with the simulations: it features a decrease of the rate of propagation arising from a direct boundary effect, related to the contact between the radical and the impermeable boundaries of the lattice, and from an exponential factor, accounting for the confinement effect. Taking into account this rate dependence on the D.P., length and mass distributions are shown to be increasing functions of the D.P. when the rate of termination (by transfer) is small enough. In this limit, these distributions present a sharp increase in the vicinity of a D.P. about Ntot. This accumulation of polymers at a D.P. close to Ntot entails a significant decrease of the polydispersity. [ABSTRACT FROM AUTHOR]

The chlorite–thiosulfate reaction provides us with an example of isothermal chemical reaction giving rise to explosive-like behavior in batch condition. Experimental results show that this phenomenon is characterized by high sensitivity, reflected in particular by the fact that reaction times occur randomly despite the care taken to prepare initially the system in identical states. In the present paper a reaction scheme reproducing explosive dynamics analogous to the experimental data is proposed and the effects of fluctuations of different origins on the reaction time are examined. As it turns out, both internal and external fluctuations induce a significant broadening of the probability distribution of explosion times as well as an asymmetry in its shape. The effect of random initial conditions is also analyzed and shown to affect deeply the explosive behavior. [ABSTRACT FROM AUTHOR]