13 research outputs found
Extreme-value statistics of work done in stretching a polymer in a gradient flow
We analyze the statistics of work generated by a gradient flow to stretch a nonlinear polymer. We obtain the large deviation function (LDF) of the work in the full range of appropriate parameters by combining analytical and numerical tools. The LDF shows two distinct asymptotes: “near tails” are linear in work and dominated by coiled polymer configurations, while “far tails” are quadratic in work and correspond to preferentially fully stretched polymers. We find the extreme value statistics of work for several singular elastic potentials, as well as the mean and the dispersion of work near the coil-stretch transition. The dispersion shows a maximum at the transition.United States-Israel Binational Science FoundationUnited States. National Nuclear Security Administration (Contract DE-AC52-06NA25396
Inertial particles driven by a telegraph noise
We present a model for the Lagrangian dynamics of inertial particles in a
compressible flow, where fluid velocity gradients are modelled by a telegraph
noise. The model allows for an analytic investigation of the role of time
correlation of the flow in the aggregation-disorder transition of inertial
particle. The dependence on Stokes and Kubo numbers of the Lyapunov exponent of
particle trajectories reveals the presence of a region in parameter space (St,
Ku) where the leading Lyapunov exponent changes sign, thus signaling the
transition. The asymptotics of short and long-correlated flows are discussed,
as well as the fluid-tracer limit.Comment: 8 pages, 6 figure
Hantavirus infections in forestry workers
Bjedov, L., Margaletić, J., Vucelja, M., Medved, M.M., Matijević, I., Krajinović, L.C., Markotic, A
Clustering of matter in waves and currents
The growth rate of small-scale density inhomogeneities (the entropy
production rate) is given by the sum of the Lyapunov exponents in a random
flow. We derive an analytic formula for the rate in a flow of weakly
interacting waves and show that in most cases it is zero up to the fourth order
in the wave amplitude. We then derive an analytic formula for the rate in a
flow of potential waves and solenoidal currents. Estimates of the rate and the
fractal dimension of the density distribution show that the interplay between
waves and currents is a realistic mechanism for providing patchiness of
pollutant distribution on the ocean surface.Comment: 4 pages, 1 figur
Emergence of clones in sexual populations
In sexual population, recombination reshuffles genetic variation and produces
novel combinations of existing alleles, while selection amplifies the fittest
genotypes in the population. If recombination is more rapid than selection,
populations consist of a diverse mixture of many genotypes, as is observed in
many populations. In the opposite regime, which is realized for example in the
facultatively sexual populations that outcross in only a fraction of
reproductive cycles, selection can amplify individual genotypes into large
clones. Such clones emerge when the fitness advantage of some of the genotypes
is large enough that they grow to a significant fraction of the population
despite being broken down by recombination. The occurrence of this "clonal
condensation" depends, in addition to the outcrossing rate, on the heritability
of fitness. Clonal condensation leads to a strong genetic heterogeneity of the
population which is not adequately described by traditional population genetics
measures, such as Linkage Disequilibrium. Here we point out the similarity
between clonal condensation and the freezing transition in the Random Energy
Model of spin glasses. Guided by this analogy we explicitly calculate the
probability, Y, that two individuals are genetically identical as a function of
the key parameters of the model. While Y is the analog of the spin-glass order
parameter, it is also closely related to rate of coalescence in population
genetics: Two individuals that are part of the same clone have a recent common
ancestor.Comment: revised versio