21 research outputs found
Multiscale analysis for traveling-pulse solutions to the stochastic FitzHugh-Nagumo equations
We investigate the stability of traveling-pulse solutions to the stochastic
FitzHughNagumo equations with additive noise. Special attention is given to the
effect of small noise on the classical deterministically stable fast traveling
pulse. Our method is based on adapting the velocity of the traveling wave by
solving a scalar stochastic ordinary differential equation (SODE) and tracking
perturbations to the wave meeting a system of a scalar stochastic partial
differential equation (SPDE) coupled to a scalar ordinary differential equation
(ODE). This approach has been recently employed by Kr\"uger and Stannat for
scalar stochastic bistable reaction-diffusion equations such as the Nagumo
equation. A main difference in our situation of an SPDE coupled to an ODE is
that the linearization has essential spectrum parallel to the imaginary axis
and thus only generates a strongly continuous semigroup. Furthermore, the
linearization around the traveling wave is not self-adjoint anymore, so that
fluctuations around the wave cannot be expected to be orthogonal in a
corresponding inner product. We demonstrate that this problem can be overcome
by making use of Riesz instead of orthogonal spectral projections as recently
employed in a series of papers by Hamster and Hupkes in case of analytic
semigroups. We expect that our approach can also be applied to traveling waves
and other patterns in more general situations such as systems of SPDEs with
linearizations only generating a strongly continuous semigroup. This provides a
relevant generalization as these systems are prevalent in many applications.Comment: 45 pages, revised version, extended literature discussion,
Proposition 3.6 adde
Multiscale analysis for traveling-pulse solutions to the stochastic fitzhugh–nagumo equations
We investigate the stability of traveling-pulse solutions to the stochastic FitzHugh–Nagumo equations with additive noise. Special attention is given to the effect of small noise on the classical deterministically stable fast traveling pulse. Our method is based on adapting the velocity of the traveling wave by solving a scalar stochastic ordinary differential equation (SODE) and tracking perturbations to the wave meeting a system of a scalar stochastic partial differential equation (SPDE) coupled to a scalar ordinary differential equation (ODE). This approach has been recently employed by Krüger and Stannat (Nonlinear Anal. 162 (2017) 197–223) for scalar stochastic bistable reaction–diffusion equations such as the Nagumo equation. A main difference in our situation of an SPDE coupled to an ODE is that the linearization has essential spectrum parallel to the imaginary axis and thus only generates a strongly continuous semigroup. Furthermore, the linearization around the traveling wave is not self-adjoint anymore, so that fluctuations around the wave cannot be expected to be orthogonal in a corresponding inner product. We demonstrate that this problem can be overcome by making use of Riesz instead of orthogonal spectral projections as recently employed in a series of papers by Hamster and Hupkes in case of analytic semigroups. We expect that our approach can also be applied to traveling waves and other patterns in more general situations such as systems of SPDEs with linearizations only generating a strongly continuous semigroup. This provides a relevant generalization as these systems are prevalent in many applications.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Analysi
Mapping the nucleolar proteome reveals a spatiotemporal organization related to intrinsic protein disorder
Abstract The nucleolus is essential for ribosome biogenesis and is involved in many other cellular functions. We performed a systematic spatiotemporal dissection of the human nucleolar proteome using confocal microscopy. In total, 1,318 nucleolar proteins were identified; 287 were localized to fibrillar components, and 157 were enriched along the nucleoplasmic border, indicating a potential fourth nucleolar subcompartment: the nucleoli rim. We found 65 nucleolar proteins (36 uncharacterized) to relocate to the chromosomal periphery during mitosis. Interestingly, we observed temporal partitioning into two recruitment phenotypes: early (prometaphase) and late (after metaphase), suggesting phase‐specific functions. We further show that the expression of MKI67 is critical for this temporal partitioning. We provide the first proteome‐wide analysis of intrinsic protein disorder for the human nucleolus and show that nucleolar proteins in general, and mitotic chromosome proteins in particular, have significantly higher intrinsic disorder level compared to cytosolic proteins. In summary, this study provides a comprehensive and essential resource of spatiotemporal expression data for the nucleolar proteome as part of the Human Protein Atlas