4,905 research outputs found
Dual Labor Market and Endogenous Fluctuations
We study the influence of wage differential on the emergence of endogenous fluctuations. In this way, we introduce a dual labor market, based on the Shapiro-Stiglitz efficiency wage theory in an overlapping generations model. We show that wage inequality is a source of endogenous fluctuations. Indeed, a sufficiently strong wage differentialleads to the occurrence of cycles of period two and local indeterminacy. Moreover, in contrast to several existing contributions, these results depend neither on increasing returns to scale, nor on the degree of capital-labor substitution.Endogenous fluctuations ; dual labor market ; wage inequality ; efficiency wage
Composite quantum collision models
A collision model (CM) is a framework to describe open quantum dynamics. In
its {\it memoryless} version, it models the reservoir as
consisting of a large collection of elementary ancillas: the dynamics of the
open system results from successive "collisions" of
with the ancillas of . Here, we present a general formulation of
memoryless {\it composite} CMs, where is partitioned into the very
open system under study coupled to one or more auxiliary systems .
Their composite dynamics occurs through internal - collisions
interspersed with external ones involving and the reservoir . We show that important known instances of quantum {\it non-Markovian}
dynamics of -- such as the emission of an atom into a reservoir featuring a
Lorentzian, or multi-Lorentzian, spectral density or a qubit subject to random
telegraph noise -- can be mapped on to such {\it memoryless} composite CMs.Comment: 12 pages, 4 figure
Class of exact memory-kernel master equations
A well-known situation in which a non-Markovian dynamics of an open quantum
system arises is when this is coherently coupled to an auxiliary system
in contact with a Markovian bath. In such cases, while the joint dynamics of
- is Markovian and obeys a standard (bipartite) Lindblad-type master
equation (ME), this is in general not true for the reduced dynamics of .
Furthermore, there are several instances (\eg the dissipative Jaynes-Cummings
model) in which a {\it closed} ME for the 's state {\it cannot} even be
worked out. Here, we find a class of bipartite Lindblad-type MEs such that the
reduced ME of can be derived exactly and in a closed form for any initial
product state of -. We provide a detailed microscopic derivation of our
result in terms of a mapping between two collision modelsComment: 9 pages, 1 figur
Photon localization versus population trapping in a coupled-cavity array
We consider a coupled-cavity array (CCA), where one cavity interacts with a
two-level atom under the rotating-wave approximation. We investigate the
excitation transport dynamics across the array, which arises in the atom's
emission process into the CCA vacuum. Due to the known formation of atom-photon
bound states, partial field localization and atomic population trapping in
general take place. We study the functional dependance on the coupling strength
of these two phenomena and show that the threshold values beyond which they
become significant are different. As the coupling strength grows from zero,
field localization is exhibited first.Comment: 9 pages, 5 figures. Replaced one plot in Fig.
Quantum non-Markovian piecewise dynamics from collision models
Recently, a large class of quantum non-Markovian piecewise dynamics for an
open quantum system obeying closed evolution equations has been introduced [B.
Vacchini, Phys. Rev. Lett. 117, 230401 (2016)]. These dynamics have been
defined in terms of a waiting-time distribution between quantum jumps, along
with quantum maps describing the effect of jumps and the system's evolution
between them. Here, we present a quantum collision model with memory, whose
reduced dynamics in the continuous-time limit reproduces the above class of
non-Markovian piecewise dynamics, thus providing an explicit microscopic
realization.Comment: 18 pages, 1 figures. Submitted to "Open Systems and Information
Dynamics" as a contribution to the upcoming special issue titled "40 years of
the GKLS equation
Conformational changes in the adenine riboswitch
Riboswitches are cis-acting genetic control elements that have been found in the un- traslated region of some mRNAs in bacteria and plants. Riboswitches are known to regulate the genetic expression by means of conformational changes triggered by highly specific interactions of the aptamer with the sensed metabolite. The non-coding sequence in the mRNA of add gene from V. vulnificus contains an adenine responsive riboswitch. Classical molecular dynamics simulations of its aptamer have been performed, both in presence and absence of its physiological ligand starting from the experimental crystal structure. We first use steered MD to induce the opening of the P1 stem and investigate its stability. Our results show that the ligand directly stabilizes the P1 stem by means of stacking interactions quantitatively consistent with thermodynamic data. Then, using both umbrella sampling and a combination of metadynamics and hamiltonian replica exchange, we show that the formation of L2-L3 kissing complex cooperates with ligand binding and we quantify the ligand-induced stabilization. In this context also the influ- ence given by either the monovalent cations or divalent cations was evaluated. Confor- mational changes at pairings detailed level are characterized using a recently introduced technique that is able to distinguish and classify each interaction (i.e. Watson-Crick base pair, non-canonical bp, stacking). Results are compatible with known experimental measurements and shed a new light on the ligand-dependent folding mechanism of the adenine riboswitch
Faschismusbild und Faschismusinterpretationen:: Die Sopade und die Giustizia e Libertà im Vergleich
This article argues that the Sopade, the exil executive of the German Socialdemocratic Party, and Giustizia e Libertà, the Italian socialist group founded in Paris in 1929, elaborated similar interpretations of fascism out of common theoretical impulses from for instance the French or Belgian socialist avant-garde. Their most influential leaders, e.g. Rudolf Hilferding and Friedrich Stampfer on the one hand, Carlo Rosselli and Gaetano Salvemini on the other, believed in the momentous character of fascism in Europe. They considered it a barbaric, civilisation-breaking regime, and at the same time stressed the unique chance for humanist and social rebirth antifascism offered. Being in control of large portions of the respective socialdemocratic press, they were, despite organisational and political setbacks in exile, able to strongly influence the German and Italian antifascism by pleading for the assimilation of an antidogmatic and antireformist, liberal and federalist socialism
Heterogeneous Workers, Dualism and Efficiency Wage
We consider a segmented labor market characterized by a Shapiro-Stiglitz efficiency wage setting in both sectors. However, the primary sector and the secondary sector differ in the firing cost which induces a wage diffential. We suppose also a heterogeneous labor force characterized by the presence of > and > workers. Only controlled non-shirking workers of the secondary sector can enter in the primary one. This flow of these ones is assimilated to promoted workers. We show that involuntary unemployment emerges at the equilibrium because of efficiency wage setting in both sectors. We argue also that a reduction of the firing cost in the primary sector leads to a lower unemployment of both worker types and raises wage discrimination.labor turnover, efficiency wage, primary and secondary sectors
Dynamical decoupling efficiency versus quantum non-Markovianity
We investigate the relationship between non-Markovianity and the
effectiveness of a dynamical decoupling protocol for qubits undergoing pure
dephasing. We consider an exact model in which dephasing arises due to a
bosonic environment with a spectral density of the Ohmic class. This is
parametrised by an Ohmicity parameter by changing which we can model both
Markovian and non-Markovian environments. Interestingly, we find that
engineering a non-Markovian environment is detrimental to the efficiency of the
dynamical decoupling scheme, leading to a worse coherence preservation. We show
that each dynamical decoupling pulse reverses the flow of quantum information
and, on this basis, we investigate the connection between dynamical decoupling
efficiency and the reservoir spectral density. Finally, in the spirit of
reservoir engineering, we investigate the optimum system-reservoir parameters
for achieving maximum stationary coherences.Comment: 6 pages, 4 figure
Heat flux dynamics in dissipative cascaded systems
We study the dynamics of heat flux in the thermalization process of a pair of
identical quantum system that interact dissipatively with a reservoir in a {\it
cascaded} fashion. Despite the open dynamics of the bipartite system S is
globally Lindbladian, one of the subsystems "sees" the reservoir in a state
modified by the interaction with the other subsystem and hence it undergoes a
non-Markovian dynamics. As a consequence, the heat flow exhibits a
non-exponential time behaviour which can greatly deviate from the case where
each party is independently coupled to the reservoir. We investigate both
thermal and correlated initial states of and show that the presence of
correlations at the beginning can considerably affect the heat flux rate. We
carry out our study in two paradigmatic cases -- a pair of harmonic oscillators
with a reservoir of bosonic modes and two qubits with a reservoir of fermionic
modes -- and compare the corresponding behaviours. In the case of qubits and
for initial thermal states, we find that the trace distance discord is at any
time interpretable as the correlated contribution to the total heat flux.Comment: Final accepted versio
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