DEFM - Artículoshttp://hdl.handle.net/10481/310192019-12-15T12:38:16Z2019-12-15T12:38:16ZLimited role of spatial selfstructuring in emergent trade-offs during pathogen evolutionBuendía, VictorMuñoz, MiguelManrubia, Susannahttp://hdl.handle.net/10481/580792019-11-26T12:13:10ZLimited role of spatial selfstructuring in emergent trade-offs during pathogen evolution
Buendía, Victor; Muñoz, Miguel; Manrubia, Susanna
Pathogen transmission and virulence are main evolutionary variables broadly assumed to be linked
through trade-offs. In well-mixed populations, these trade-offs are often ascribed to physiological
restrictions, while populations with spatial self-structuring might evolve emergent trade-offs. Here,
we reexamine a spatially-explicit, SIR model of the latter kind proposed by Ballegooijen and Boerlijst
with the aim of characterising the mechanisms causing the emergence of the trade-off and its structural
robustness. Using invadability criteria, we establish the conditions under which an evolutionary
feedback between transmission and virulence mediated by pattern formation can poise the system to
a critical boundary separating a disordered state (without emergent trade-off) from a self-structured
phase (where the trade-off emerges), and analytically calculate the functional shape of the boundary
in a certain approximation. Beyond evolutionary parameters, the success of an invasion depends
on the size and spatial structure of the invading and invaded populations. Spatial self-structuring is
often destroyed when hosts are mobile, changing the evolutionary dynamics to those of a well-mixed
population. In a metapopulation scenario, the systematic extinction of the pathogen in the disordered
phase may counteract the disruptive effect of host mobility, favour pattern formation and therefore
recover the emergent trade-off.
Sampling rare events across dynamical phase transitionsPérez Espigares, CarlosHurtado Fernández, Pablo Ignaciohttp://hdl.handle.net/10481/567912019-11-27T10:34:06ZSampling rare events across dynamical phase transitions
Pérez Espigares, Carlos; Hurtado Fernández, Pablo Ignacio
Interacting particle systems with many degrees of freedom may undergo phase transitions to sustain atypical fluctuations of dynamical observables such as the current or the activity. In some cases, this leads to symmetry-broken space-time trajectories which enhance the probability of such events due to the emergence of ordered structures. Despite their conceptual and practical importance, these dynamical phase transitions (DPTs) at the trajectory level are difficult to characterize due to the low probability of their occurrence. However, during the last decade, advanced computational techniques have been developed to measure rare events in simulations of many-particle systems that allow the direct observation and characterization of these DPTs. Here we review the application of a particular rare-event simulation technique, based on cloning Monte Carlo methods, to characterize DPTs in paradigmatic stochastic lattice gases. In particular, we describe in detail some tricks and tips of the trade, paying special attention to the measurement of order parameters capturing the physics of the different DPTs, as well as to the finite-size effects (both in the system size and in the number of clones) that affect the measurements. Overall, we provide a consistent picture of the phenomenology associated with DPTs and their measurement.
Complex Network Geometry and Frustrated SynchronizationMillán Vidal, Ana PaulaTorres Agudo, Joaquín J.Bianconi, Ginestrahttp://hdl.handle.net/10481/566342019-08-14T09:17:18ZComplex Network Geometry and Frustrated Synchronization
Millán Vidal, Ana Paula; Torres Agudo, Joaquín J.; Bianconi, Ginestra
The dynamics of networks of neuronal cultures has been recently shown to be strongly dependent on
the network geometry and in particular on their dimensionality. However, this phenomenon has been
so far mostly unexplored from the theoretical point of view. Here we reveal the rich interplay between
network geometry and synchronization of coupled oscillators in the context of a simplicial complex
model of manifolds called Complex Network Manifold. The networks generated by this model combine
small world properties (infinite Hausdorff dimension) and a high modular structure with finite and
tunable spectral dimension. We show that the networks display frustrated synchronization for a wide
range of the coupling strength of the oscillators, and that the synchronization properties are directly
affected by the spectral dimension of the network.
Dynamical criticality in open systems: non-perturbative physics, microscopic origin and direct observationPérez Espigares, CarlosCarollo, FedericoGarrahan, Juan P.Hurtado Fernández, Pablo Ignaciohttp://hdl.handle.net/10481/544662019-01-11T13:31:49ZDynamical criticality in open systems: non-perturbative physics, microscopic origin and direct observation
Pérez Espigares, Carlos; Carollo, Federico; Garrahan, Juan P.; Hurtado Fernández, Pablo Ignacio
Driven diffusive systems may undergo phase transitions to sustain atypical values of the current. This leads in some cases to symmetry-broken space-time trajectories which enhance the probability of such fluctuations. Here we shed light on both the macroscopic large deviation properties and the microscopic origin of such spontaneous symmetry breaking in the open weakly asymmetric exclusion process. By studying the joint fluctuations of the current and a collective order parameter, we uncover the full dynamical phase diagram for arbitrary boundary driving, which is reminiscent of a Z2 symmetry-breaking transition. The associated joint large deviation function becomes non-convex below the critical point, where a Maxwell-like violation of the additivity principle is observed. At the microscopic level, the dynamical phase transition is linked to an emerging degeneracy of the ground state of the microscopic generator, from which the optimal trajectories in the symmetry- broken phase follow. In addition, we observe this new symmetry-breaking phenomenon in extensive rare-event simulations, confirming our macroscopic and microscopic results.
An Explicit Nodal Space-Time Discontinuous Galerkin Method for Maxwell’s EquationsAlvarez Gonzalez, JesusFernandez Pantoja, MarioGonzalez Garcia, SalvadorDiaz Angulo, Luishttp://hdl.handle.net/10481/501572018-09-08T07:43:48ZAn Explicit Nodal Space-Time Discontinuous Galerkin Method for Maxwell’s Equations
Alvarez Gonzalez, Jesus; Fernandez Pantoja, Mario; Gonzalez Garcia, Salvador; Diaz Angulo, Luis
A novel implicit nodal Space-Time Discontinuous
Galerkin (STDG) method is proposed in this paper. An eigenvalue
analysis is performed and compared with that for a DG scheme
solved with a 4th-Order Runge-Kutta time integrator. We show
that STDG offers a significant improvement of dissipative and
dispersive properties and allows larger time steps, regardless of
the spatial hp-refinement. A domain-decomposition technique is
used to introduce an explicit formulation of the method in order
to render it computationally efficient.