13,773 research outputs found
Convergence across countries and regions: theory and empirics
This paper surveys the recent literature on convergence across countries and regions. I discuss the main convergence and divergence mechanisms identified in the literature and develop a simple model that illustrates their implications for income dynamics. I then review the existing empirical evidence and discuss its theoretical implications. Early optimism concerning the ability of a human capital-augmented neoclassical model to explain productivity differences across economies has been questioned on the basis of more recent contributions that make use of panel data techniques and obtain theoretically implausible results. Some recent research in this area tries to reconcile these findings with sensible theoretical models by exploring the role of alternative convergence mechanisms and the possible shortcomings of panel data techniques for convergence analysis.convergence, growth
Testing, not modelling, the impact of Cohesion support: a theoretical framework and some preliminary results for the Spanish regions
This paper develops a simple model that can be used to estimate the effectiveness of Cohesion expenditure relative to similar but unsubsidized projects, thereby making it possible to explicitly test an important assumption that is often implicit in estimates of the impact of Cohesion policies. Some preliminary results are reported for the case of infrastructure investment in the Spanish regions.Cohesion policy effectiveness, Structural Fund evaluation
Testing, not Modelling, the Impact of Cohesion Support: A Theoretical Framework and some Preliminary Results for the Spanish Regions
This paper develops a simple model that can be used to estimate the effectiveness of Cohesion expenditure relative to similar but unsubsidized projects, thereby making it possible to explicitly test an important assumption that is often implicit in estimates of the impact of Cohesion policies. Some preliminary results are reported for the case of infrastructure investment in the Spanish regions.Cohesion policy effectiveness, structural fund evaluation
A simple model of aggregate pension expenditure
This paper develops a simple model that can be used to analyze the long-term sustainability of the contributive pension system and the steady-state response of pension expenditure to changes in some key demographic and economic variables, in the characteristics of the average pensioner and in the parameters that describe how pensions are calculated in Spain as a function of workers' Social Security contribution histories.pensions, sustainability, Spain
A first principles TDDFT framework for spin and time-resolved ARPES in periodic systems
We present a novel theoretical approach to simulate spin, time and
angular-resolved photoelectron spectroscopy (ARPES) from first principles that
is applicable to surfaces, thin films, few layer systems, and low-dimensional
nanostructures. The method is based on a general formulation in the framework
of time-dependent density functional theory (TDDFT) to describe the real
time-evolution of electrons escaping from a surface under the effect of any
external (arbitrary) laser field. By extending the so called t-SURFF method to
periodic systems one can calculate the final photoelectron spectrum by
collecting the flux of the ionization current trough an analysing surface. The
resulting approach, that we named t-SURFFP, allows to describe a wide range of
irradiation conditions without any assumption on the dynamics of the ionization
process allowing for pump-probe simulations on an equal footing. To illustrate
the wide scope of applicability of the method we present applications to
graphene, mono- and bi-layer WSe, and hexagonal BN under different laser
configurations
Phonon driven Floquet matter
A resonantly excited coherent phonon leads to a periodic oscillation of the
atomic lattice in a crystal structure bringing the material into a
non-equilibrium electronic configuration. Periodically oscillating quantum
systems can be understood in terms of Floquet theory and we show these concepts
can be applied to coherent lattice vibrations reflecting the underlying
coupling mechanism between electrons and bosonic modes. This coupling leads to
dressed quasi-particles imprinting specific signatures in the spectrum of the
electronic structure. Taking graphene as a paradigmatic material we show how
the phonon-dressed states display an intricate sideband structure revealing
electron-phonon coupling and topological ordering. This work establishes that
the recently demonstrated concept of light-induced non-equilibrium Floquet
phases can also be applied when using coherent phonon modes for the dynamical
control of material properties. The present results are generic for bosonic
time-dependent perturbations and similar phenomena can be observed for plasmon,
magnon or exciton driven materials
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