Effects of fiscal policy on the durability of low inflation regimes

This paper deals with the interaction of fiscal and monetary policy when the central bank is pursuing a price stability-oriented monetary policy. In particular, we study the durability of the price stability regime when public debt accumulates as a result of ultimately unsustainable deficits. The growth of indebtedness causes the collapse of the price stability regime after a period of rising deficits. The budget deficit is endogenously determined in the model, as a result of government’s decisions on how to finance its expenditure. The alternative methods of finance are taxes, debt, and seigniorage. Under the price stability regime, only the first two methods are available, but in the long run taxes and seigniorage are the only alternatives. The price stability regime collapses when the public debt reaches an edogenously determined threshold, which makes reneging on price stability as attractive as accumulating more tax burden for the future. We are able to solve for the critical level of debt, the timing of the collapse, and the reaction of taxes to the collapse of the price stability regime. The critical level of debt depends, inter alia, on the level of government consumption, the real interest rate, the velocity of money, and the efficiency-effects of taxation. The results are illustrated by several numerical simulations.inflation; fiscal policy; fiscal theory of inflation; Stability and Growth Pact

Priorities Without Priorities: Representing Preemption in Psi-Calculi

Psi-calculi is a parametric framework for extensions of the pi-calculus with data terms and arbitrary logics. In this framework there is no direct way to represent action priorities, where an action can execute only if all other enabled actions have lower priority. We here demonstrate that the psi-calculi parameters can be chosen such that the effect of action priorities can be encoded. To accomplish this we define an extension of psi-calculi with action priorities, and show that for every calculus in the extended framework there is a corresponding ordinary psi-calculus, without priorities, and a translation between them that satisfies strong operational correspondence. This is a significantly stronger result than for most encodings between process calculi in the literature. We also formally prove in Nominal Isabelle that the standard congruence and structural laws about strong bisimulation hold in psi-calculi extended with priorities.Comment: In Proceedings EXPRESS/SOS 2014, arXiv:1408.127

Orbital and spin Kondo effects in a double quantum dot

Motivated by recent experiments, in which the Kondo effect has been observed for the first time in a double quantum-dot structure, we study electron transport through a system consisting of two ultrasmall, capacitively-coupled dots with large level spacing and charging energy. Due to strong interdot Coulomb correlations, the Kondo effect has two possible sources, the spin and orbital degeneracies, and it is maximized when both occur simultaneously. The large number of tunable parameters allows a range of manipulations of the Kondo physics -- in particular, the Kondo effect in each dot is sensitive to changes in the state of the other dot. For a thorough account of the system dynamics, the linear and nonlinear conductance is calculated in perturbative and non-perturbative approaches. In addition, the temperature dependence of the resonant peak heights is evaluated in the framework of a renormalization group analysis.Comment: 7 pages, 3 figures; submitted to Europhys. Let

Monotonicity and local uniqueness for the Helmholtz equation

This work extends monotonicity-based methods in inverse problems to the case of the Helmholtz (or stationary Schr\"odinger) equation $(\Delta + k^2 q) u = 0$ in a bounded domain for fixed non-resonance frequency $k>0$ and real-valued scattering coefficient function $q$. We show a monotonicity relation between the scattering coefficient $q$ and the local Neumann-Dirichlet operator that holds up to finitely many eigenvalues. Combining this with the method of localized potentials, or Runge approximation, adapted to the case where finitely many constraints are present, we derive a constructive monotonicity-based characterization of scatterers from partial boundary data. We also obtain the local uniqueness result that two coefficient functions $q_1$ and $q_2$ can be distinguished by partial boundary data if there is a neighborhood of the boundary where $q_1\geq q_2$ and $q_1\not\equiv q_2$

Differential games of capitalism: A survey

AbstractThis paper surveys some recent work done by the author and others on a differential game model of capitalism which was originally developed by Kelvin Lancaster. Economic growth and income distribution are here modelled as a game between workers, who may consume or save, and capitalists, who may consume or invest. The assumptions made and the results obtained are discussed with a view to pointing out possible avenues of future research

Dynamical properties of single-electron devices and molecular magnets

This doctoral dissertation consists of theoretical studies of a number of nanometer-scale structures. In papers [1]-[5], the emphasis is on tiny devices based on conducting materials, i.e., metals and doped semiconductors. Depending on the feature size, geometry, and the electronic density of states, charging effects and quantization of single-electron states may occur. These properties can be utilized to control charge and electric current with the precision of fractions of the electronic charge e - hence the name single-electron device. In paper [6] the focus is on the rich magnetization dynamics of the molecular magnet Mn acetate. At low temperature the molecules of this material acquire a magnetic single-spin ground state with S=10. Interestingly, the quantum tunneling of the molecular spins between the different spin states is manifest even in the magnetization relaxation of macroscopic samples. In order to study or utilize the quantized states in a given nanostructure, this needs to be coupled to some measuring device. The coupling always gives rise to exchange of particles and/or heat between the nanostructure and its environment and the stronger the coupling the more the environment affects the smaller system. This may lead to modifications in the quantized states, interference effects, and dissipation. In some cases, even completely new many-body states such as the Kondo resonances observed in ultrasmall quantum dots are found to emerge. All these effects are of great fundamental as well as of nanoengineering interest. In this thesis, a theoretical model applicable to all the above systems is developed and used. The real-time diagrammatic technique is well suited for describing the various strong-coupling effects between a set of localized states and its fermionic and/or bosonic environment. This approach also allows the description of the nonequilibrium conditions attained in single-electron devices.reviewe