4,771 research outputs found
Back to the future? Habits and rational addiction in UK tobacco and alcohol demand.
This paper develops a dynamic modeling approach for the Almost Ideal Demand System, which is consistent with the rational addiction theory. The forward-looking hypothesis is combined with that of convex adjustment costs in the presence of non-stationary cointegrated variables. Estimation is based on a two-step strategy based on cointegration and GMM techniques. Results on UK tobacco and alcohol demand support the adopted specifications and highlight the degree of complementarity between addictive goods.
On the Impact of Fair Best Response Dynamics
In this work we completely characterize how the frequency with which each
player participates in the game dynamics affects the possibility of reaching
efficient states, i.e., states with an approximation ratio within a constant
factor from the price of anarchy, within a polynomially bounded number of best
responses. We focus on the well known class of congestion games and we show
that, if each player is allowed to play at least once and at most times
any best responses, states with approximation ratio times the
price of anarchy are reached after best
responses, and that such a bound is essentially tight also after exponentially
many ones. One important consequence of our result is that the fairness among
players is a necessary and sufficient condition for guaranteeing a fast
convergence to efficient states. This answers the important question of the
maximum order of needed to fast obtain efficient states, left open by
[9,10] and [3], in which fast convergence for constant and very slow
convergence for have been shown, respectively. Finally, we show
that the structure of the game implicitly affects its performances. In
particular, we show that in the symmetric setting, in which all players share
the same set of strategies, the game always converges to an efficient state
after a polynomial number of best responses, regardless of the frequency each
player moves with
Time decay of scaling invariant Schroedinger equations on the plane
We prove the sharp L^1-L^{\infty} time-decay estimate for the 2D-Schroedinger
equation with a general family of scaling critical electromagnetic potentials.Comment: 26 page
Summary of DSN (Deep Space Network) reimbursable launch support
The Deep Space Network is providing ground support to space agencies of foreign governments as well as to NASA and other agencies of the Federal government which are involved in space activities. DSN funding for support of missions other than NASA are on either a cooperative or a reimbursable basis. Cooperative funding and support are accomplished in the same manner as NASA sponsored missions. Reimbursable launch funding and support methods are described
Chaotic dynamics in a storage-ring Free Electron Laser
The temporal dynamics of a storage-ring Free Electron Laser is here
investigated with particular attention to the case in which an external
modulation is applied to the laser-electron beam detuning. The system is shown
to produce bifurcations, multi-furcations as well as chaotic regimes. The
peculiarities of this phenomenon with respect to the analogous behavior
displayed by conventional laser sources are pointed out. Theoretical results,
obtained by means of a phenomenological model reproducing the evolution of the
main statistical parameters of the system, are shown to be in a good agreement
with experiments carried out on the Super-ACO Free Electron Laser.Comment: submitted to Europ Phys. Journ.
Pion Generalized Parton Distributions within a fully covariant constituent quark model
We extend the investigation of the Generalized Parton Distribution for a
charged pion within a fully covariant constituent quark model, in two respects:
(i) calculating the tensor distribution and (ii) adding the treatment of the
evolution, needed for achieving a meaningful comparison with both the
experimental parton distribution and the lattice evaluation of the so-called
generalized form factors. Distinct features of our phenomenological covariant
quark model are: (i) a 4D Ansatz for the pion Bethe-Salpeter amplitude, to be
used in the Mandelstam formula for matrix elements of the relevant current
operators, and (ii) only two parameters, namely a quark mass assumed to hold
MeV and a free parameter fixed through the value of the pion decay
constant. The possibility of increasing the dynamical content of our covariant
constituent quark model is briefly discussed in the context of the Nakanishi
integral representation of the Bethe-Salpeter amplitude.Comment: Pages 20, figure 11 and table 8. Minor changes. To be published in
EPJ
Pattern formation for reactive species undergoing anisotropic diffusion
Turing instabilities for a two species reaction-diffusion systems is studied
under anisotropic diffusion. More specifically, the diffusion constants which
characterize the ability of the species to relocate in space are direction
sensitive. Under this working hypothesis, the conditions for the onset of the
instability are mathematically derived and numerically validated. Patterns
which closely resemble those obtained in the classical context of isotropic
diffusion, develop when the usual Turing condition is violated, along one of
the two accessible directions of migration. Remarkably, the instability can
also set in when the activator diffuses faster than the inhibitor, along the
direction for which the usual Turing conditions are not matched
Turing patterns in multiplex networks
The theory of patterns formation for a reaction-diffusion system defined on a
multiplex is developed by means of a perturbative approach. The intra-layer
diffusion constants act as small parameter in the expansion and the unperturbed
state coincides with the limiting setting where the multiplex layers are
decoupled. The interaction between adjacent layers can seed the instability of
an homogeneous fixed point, yielding self-organized patterns which are instead
impeded in the limit of decoupled layers. Patterns on individual layers can
also fade away due to cross-talking between layers. Analytical results are
compared to direct simulations
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