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In rational beliefs (RB) models there is an observed empirical distribution for the stochastic process of state variables. Many different weakly asymptotic mean stationary (WAMS) processes could have generated this empirical distribution, i.e. are consistent with it, and each of them are therefore called a rational belief.We provide a general framework for using RB in general equilibrium models. Individual rational beliefs are assumed correlated by means of sunspots which at the aggregate level lead to excess volatility.The application adapts the proof by Duffie et al (1994) of the existence of a stationary ergodic RE equilibrium to the case where agents hold rational beliefs.

Consider a rational expectations model that includes a relationship between variables xt and zt+1. To be useful as a guide to actual behavior, this model should specify whether xt is influenced by the expectation at t of zt+1 or, alternatively, that zt+1 is directly influenced by xt. For a broad class of multivariate linear RE models, distinct causal specifications involving both expectational and inertial influences will be uniquely associated with distinct solutions—operationally, different specifications of which variables are predetermined. With a natural continuity assumption, there is only one RE solution that is fully consistent with the model's specification.

We have studied the interaction between magnetism and superconductivity in a pseudo-spin-valve structure consisting of a Co/Cu/Py/Nb-layer sequence. We are able to control the magnetization reversal process and monitor it by means of the giant magnetoresistance effect during transport measurements. By placing the superconducting Nb-film on the top of the permalloy (Py) electrode instead of putting it in between the two ferromagnets, we minimize the influence of spin scattering or spin accumulation onto the transport properties of Nb. Magnetotransport data reveal clear evidence that the stray fields of domain walls (DWs) in the pseudo-spin valve influence the emerging superconductivity close to the transition temperature by the occurrence of peaklike features in the magneto-resistance characteristic. Direct comparison with magnetometry data shows that the resistance peaks occur exactly at the magnetization reversal fields of the Co and Py layers where DWs are generated. For temperatures near the superconducting transition the amplitude of the DW-induced magnetoresistance increases with decreasing temperature, reaching values far beyond the size of the giant magnetoresistive response of our structure in the normal state. 2012 American Physical Society. ; We acknowledge the Diputación Foral de Giupuzkoa Ref. 99/11, program Red Guipuzkoana de Ciencia Tecnologia e Innovacion, funding from the Basque Government under Program No. PI2009-17 and UPV/EHU Project IT-366-07, and the Spanish Ministry of Science and Innovation under Projects No. MAT2009-07980 and FIS2011-28851-C02-02. ; Peer Reviewed

In most theoretical descriptions of collective strong coupling of organic molecules to a cavity mode, the molecules are modeled as simple two-level systems. This picture fails to describe the rich structure provided by their internal rovibrational (nuclear) degrees of freedom. We investigate a first-principles model that fully takes into account both electronic and nuclear degrees of freedom, allowing an exploration of the phenomenon of strong coupling from an entirely new perspective. First, we demonstrate the limitations of applicability of the Born-Oppenheimer approximation in strongly coupled molecule-cavity structures. For the case of two molecules, we also show how dark states, which within the two-level picture are effectively decoupled from the cavity, are indeed affected by the formation of collective strong coupling. Finally, we discuss ground-state modifications in the ultrastrong-coupling regime and show that some molecular observables are affected by the collective coupling strength, while others depend only on the single-molecule coupling constant ; This work has been funded by the European Research Council (ERC-2011-AdG Proposal No. 290981), by the European Union Seventh Framework Programme under Grant Agreement FP7-PEOPLE-2013-CIG-618229, and the Spanish MINECO under Contracts No. MAT2011-28581-C02-01 and No. MAT2014-53432-C5-5-R

In this work we present the formation of laser induced periodic surface structures (LIPSS) on spin-coated thin films of several model aromatic polymers including poly(ethylene terephthalate), poly(trimethylene terephthalate) and poly carbonate bis-phenol A upon irradiation with femtosecond pulses of 795 and 265 nm at fluences well below the ablation threshold. LIPSS are formed with period lengths similar to the laser wavelength and parallel to the direction of the laser polarization vector. Formation of LIPSS upon IR irradiation at 795 nm, a wavelength at which the polymers absorb weakly, contrasts with the absence of LIPSS in this spectral range upon irradiation with nanosecond pulses. Real and reciprocal space characterization of LIPSS obtained by Atomic Force Microscopy (AFM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS), respectively, yields well correlated morphological information. Comparison of experimental and simulated GISAXS patterns suggests that LIPSS can be suitably described considering a quasi-one-dimensional paracrystalline lattice and that irradiation parameters have an influence on the order of such a lattice. Fluorescence measurements, after laser irradiation, provide indirect information about dynamics and structure of the polymer at the molecular level. Our results indicate that the LIPSS are formed by interference of the incident and surface scattered waves. As a result of this process, heating of the polymer surface above its glass transition temperature takes place enabling LIPSS formation. © 2013 the Owner Societies. ; Funding from MICINN, Spain (Projects CTQ2010-15680,FIS2009-09522, MAT2012-33517 and CSD2007-00013) and Junta de Castilla y León (Project SA086A12-2). The experiments performed at BW4 in HASYLAB (DESY,Germany) were supported by the European Union (Contract RII3-CT-2004-506008 (IA-SFS).MINECO (previous MICINN), Spain, Ramón y Cajal contract (RYC-2011-08069), FPI fellowship and PTA contract ; Peer Reviewed