https://hdl.handle.net/10481/31018 2026-04-04T05:40:33Z https://hdl.handle.net/10481/111942 Convergent Power Series for Anharmonic Chain with Periodic Forcing Garrido, Pedro L.; Komorowski, Tomasz; Lebowitz, Joel L.; Olla, Stefano We study the propagation of energy in one-dimensional anharmonic chains subject to a periodic, localized forcing. For the purely harmonic case, forcing frequencies outside the linear spectrum produce exponentially localized responses, preventing equi-distribution of energy per degree of freedom. We extend this result to anharmonic perturbations with bounded second derivatives and boundary dissipation, proving that for small perturbations and non-resonant forcing, the dynamics converges to a periodic stationary state with energy exponentially localized uniformly in the system size. The perturbed periodic state is described by a convergent power type expansion in the strength of the anharmonicity. This excludes chaoticity induced by anharmonicity, independently of the size of the system. Our perturbative scheme can also be applied in higher dimensions. https://hdl.handle.net/10481/111593 Emergence of chimeras states in one-dimensional Ising model with long-range diffusion Haro García, Alejandro de; Torres Agudo, Joaquín In this work, we examine the conditions for the emergence of chimera-like states in Ising systems. We study an Ising chain with periodic boundaries in contact with a thermal bath at temperature T, that induces stochastic changes in spin variables. To capture the non-locality needed for chimera formation, we introduce a model setup with non-local diffusion of spin values through the whole system. More precisely, diffusion is modeled through spin-exchange interactions between units up to a distance R, using Kawasaki dynamics. This setup mimics, e.g., neural media, as the brain, in the presence of electrical (diffusive) interactions. We explored the influence of such non-local dynamics on the emergence of complex spatiotemporal synchronization patterns of activity. Depending on system parameters we report here for the first time chimera-like states in the Ising model, characterized by relatively stable moving domains of spins with different local magnetization. We analyzed the system at T = 0, both analytically and via simulations and computed the system’s phase diagram, revealing rich behavior: regions with only chimeras, coexistence of chimeras and stable domains, and metastable chimeras that decay into uniform stable domains. This study offers fundamental insights into how coherent and incoherent synchronization patterns can arise in complex networked systems as it is, e.g., the brain. https://hdl.handle.net/10481/110527 Schumann resonance and cardiovascular hospital admission in the area of Granada, Spain: An event coincidence analysis approach Fernandez Arroyabe, Pablo; Fornieles Callejón, Jesús Francisco; Santurtún, Ana; Szangolies, Leonna; V. Donner, Reik The study of bio-effects of Schumann resonances is a very complex issue. There is a need to identifymechanisms and pathways that explain how Extremely Low Frequency magnetic fields affect biology or human health. This particular study tries to identify statistical associations between ELF magnetic fields in the province of Granada (Spain) and cardiovascular related hospital admission in the same province for the period April, 1st 2013 to March, 31st 2014. Research is developed under an epidemiological approach based on an Event Coincidence Analysis statistical method. Clustered events, statistically significant (ECA shuffle-surrogate test p = .01 and p b .01), were found for the minimum values of the first and the third Schuman resonances frequency on eastwest and north-south directions, and for the amplitude parameter of the second resonance and the total signal energy in the north-south direction. Empirical measurements of SR parameters were recorded at the Sierra Nevada Mountain in Granada province (Spain). Results show a clear coincidence of the events for the minima amplitudes of Shuman resonances and energy in the north-south orientation and the number of the cardiovascular related hospital admissions. Further research is neededwith longer temporal series and a new approach based on gender seems to be also interesting for future studies. This paper is based upon work from COST Action “Atmospheric Electricity Network: coupling with the Earth System, climate and biological systems (ELECTRONET)”, supported by COST (European Cooperation in Science and Technology). Also authors acknowledge Cost Action 15211, Atmospheric Electricity Network: coupling with the Earth System, climate and biological systems, for funding the COST Training School on “Advanced Data Analysis Methods for Identifying and Characterizing Atmospheric Electricity Variations, their Causes and Impacts” developed at Potsdam Institute for Climate Impact Research from February, 25th to March, 1st 2019. Authors would like to thank the Spanish Ministry of Health, Consumer Affairs and Social Welfare CMBD for facilitating access to the data the Minimum Basic Data Set of the Hospital Discharges (CMBD-H) from all the Hospitals of the National Health Service. Also, authors would like to thank the support from the Spanish National Research Agency - Project CSO2016-75154-R and the European Funds for Regional Development (FEDER). Authors would like to thank the support by the investigation research project FIS2017-90102-R, of the Ministry of Economy and Competitiveness (MINECO) cofinanced by the European Regional Development Fund (FEDER), and we are grateful to Parque Nacional Sierra Nevada for providing support for the ELF measurement station. The Event Coincidence Analysis has been performed using the R package CoinCalc (Siegmund et al., 2017). LS and RVD gratefully acknowledge financial support by the German Federal Ministry of Science and Education under grant nos. 01LN1306A and 01LP1611A. https://hdl.handle.net/10481/109392 Analysis and Mitigation of Discretization Errors in the Orthogonalized Integral-Based Subgridding FDTD Algorithm Martín Valverde, Antonio Jesús; Teixeira, Fernando L.; Ruiz-Cabello Núñez, Miguel David Accuracy is a key aspect to be considered when assessing results from subgridding algorithms in the finitedifference time-domain (FDTD) method. This work focuses on the accuracy of a newly developed orthogonalized integralbased subgridding (OI-SG) algorithm and is divided into two main parts. First, we identify and quantify spurious reflections present in OI-SG by considering a set of free-space simulations containing a subgridded region illuminated by a plane wave and measuring the (spurious) far-field scattering. We find that the most relevant parameter of merit in these cases is the points-perwavelength (PPW) criterion used for the spatial discretization. Second, we study near-field effects produced by the interaction between material objects and subgridding interlevel boundaries. We observe that the PPW criterion is not sufficient to determine accuracy in these cases. We find out that an important role is also played by the buffering distance between the subgrid boundaries and the material objects. We consider a variety of application examples in our analysis: a frequency selective surface (FSS), an all-angle negative refraction (AANR) metasurface, a conducting sphere, and a NASA almond. In all cases, we measure the error as a function of the spacing between the objects and the lowest level subgridding boundary (buffering distance). We observe significant accuracy improvements in all cases https://hdl.handle.net/10481/107233 Topological protection breakdown: A route to frustrated ferroelectricity Falsi, Ludovica; Villegas Góngora, Pablo; Gili, Tommaso; Agranat, A. J.; DelRe, Eugenio Phases manifesting topological patterns in functional systems, like ferroelectric and ferromagnetic vortex superlattices, can manifest intricate and apparently ungovernable behavior, typical of frustrated nonergodic states with high-dimensional energy landscapes. This is also the case for potassium-tantalate-niobate (KTN) crystals. These transparent ferroelectrics manifest remarkable but little understood metastable domain patterns at optical (micrometer and above) scales near the cubic-to-tetragonal structural phase transition. Here, we formulate the topological breakdown model based on the competition between intrinsic scales of domain-domain collinear and noncollinear interactions associated with polarization-charge screening. The model is able to explain observed KTN mesoscopic domain patterns and phase diagram as a function of temperature and external electric field. Findings include a precise set of sharp and broad percolative transitions that are experimentally verified, validating our model. Our study identifies the central role played by competing topologically protected states, identifying a fundamental link between topological protection and frustration that supports a hitherto unexplored functional nonergodic arena.