15,801 research outputs found
Spherically symmetric solutions of a boundary value problem for monopoles
In this paper we study spherically symmetric monopoles, which are critical
points for the Yang-Mills-Higgs functional over a disk in 3 dimensions, with
prescribed degree and covariant constant at the boundary. This is a
3-dimensional gauge-theory generalization of the Ginzburg-Landau model in 2
dimensions.Comment: 15 pages, 2 figures, LaTe
The value of a new idea: knowledge transmission, workers' mobility and market structure
We model the process of knowledge transmission among ïŹrms via workers mobility as a multi-stage game. In our setup an idea to be realized needs that the agent informed about the idea recruits another agent from a pool of uninformed people. This constraint generates a recursive eïŹect of knowledge transmission via players mobility across ïŹrms which aïŹects simultaneously the players payoïŹs and the number of active players engaged in market competition. We provide suïŹcient conditions for the game to possess a unique symmetric subgame perfect equilibrium in which all incumbent players deter the exit of their collaborators. The equilibrium outcome is shown to depend upon the success of the idea over time, expressed by the behaviour of the market demand and on playerstime preferences. A few other intuitions are provided on the interplay between technology, market structure and the market value of an innovative idea.Innovation; Workersâ Mobility; Knowledge Transmission; Subgame Perfect Nash Equilibrium; Recursive Games
Cooling of a lattice granular fluid as an ordering process
We present a new microscopic model of granular medium to study the role of
dynamical correlations and the onset of spatial order induced by the
inelasticity of the interactions. In spite of its simplicity, it features
several different aspects of the rich phenomenology observed in granular
materials and allows to make contact with other topics of statistical mechanics
such as diffusion processes, domain growth, persistence, aging phenomena.
Interestingly, while local observables being controlled by the largest
wavelength fluctuations seem to suggest a purely diffusive behavior, the
formation of spatially extended structures and topological defects, such as
vortices and shocks, reveals a more complex scenario.Comment: 4 pages, 4 figure
A sequential approach to the characteristic function and the core in games with externalities
This paper proposes a formulation of coalitional payoff possibilities in games with externalities, based on the assumption that forming coalitions can exploit a âfirst mover advantageâ. We derive a characteristic function and show that when outside players play their best response noncooperatively, the core is nonempty in games with strategic complements. We apply this result to Cournot and Bertrand games and to public goods economies.Core; cooperative games; externalities
Road pricing as a citizen-candidate game
We construct a political economy model to analyze the political acceptability of road pricing policies.
We use a citizen-candidate framework with a population composed by three groups differing for their income level. We show that road pricing policies are never applied when there is no redistribution of the resources in favour of other modes of transport or when the congestion of these types of transport is relatively high. The results suggest that the efficiency of the redistribution of resources from road to the alternative types of transport as well as the fraction of the population that uses the road transport are key factors in explaining the adoption of road pricing schemes
Driven granular gases with gravity
We study fluidized granular gases in a stationary state determined by the
balance between an external driving and the bulk dissipation. The two
considered situations are inspired by recent experiments, where the gravity
plays a major role as a driving mechanism: in the first case gravity acts only
in one direction and the bottom wall is vibrated, in the second case gravity
acts in both directions and no vibrating walls are present. Simulations
performed under the molecular chaos assumption show averaged profiles of
density, velocity and granular temperature which are in good agreement with the
experiments. Moreover we measure the velocity distributions which show strong
non-Gaussian behavior, as experiments pointed out, but also density
correlations accounting for clustering, at odds with the experimental results.
The hydrodynamics of the first model is discussed and an exact solution is
found for the density and granular temperature as functions of the distance
from the vibrating wall. The limitations of such a solution, in particular in a
broad layer near the wall injecting energy, are discussed.Comment: Revised version accepted for publication. New results added and
discussions considering tangential forces. 27 pages (19 figures included), to
appear in Phys.Rev.
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