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Non-competes, business dynamism, and concentration: Evidence from a Florida case study
Most research on non-competes has focused on employees; here we study how non-competes affect firm location choice, growth, and consequent regional concentration, using Florida's 1996 legislative change that eased restrictions on their enforcement. Difference-in-differences models show that following the change, establishments of large firms were more likely to enter Florida; they also created a greater proportion of jobs and increased their share of employment in the state. Entrepreneurs or establishments of small firms, in contrast, were less likely to enter Florida following the law change; they also created a smaller proportion of new jobs and decreased their share of employment. Consistent with these location and job creation dynamics, regional business concentration increased following the law change in Florida. Nationwide cross-sections demonstrate consistent correlations between state-level non-compete enforcement and the location, employment, and concentration dynamics illustrated in Florida
Weak-localization and rectification current in non-diffusive quantum wires
We show that electron transport in disordered quantum wires can be described
by a modified Cooperon equation, which coincides in form with the Dirac
equation for the massive fermions in a 1+1 dimensional system. In this new
formalism, we calculate the DC electric current induced by electromagnetic
fields in quasi-one-dimensional rings. This current changes sign, from
diamagnetic to paramagnetic, depending on the amplitude and frequency of the
time-dependent external electromagnetic field.Comment: changed title, added more detail, to appear in J. Phys.: Condens.
Matte
Continuous Multipartite Entangled State in Wigner Representation and the Violation of Zukowski-Brukner Inequality
We construct an explicit Wigner function for N-mode squeezed state. Based on
a previous observation that the Wigner function describes correlations in the
joint measurement of the phase-space displaced parity operator, we investigate
the non-locality of multipartite entangled state by the violation of
Zukowski-Brukner N-qubit Bell inequality. We find that quantum predictions for
such squeezed state violate these inequalities by an amount that grows with the
number N.Comment: 5 pages, rewritten version, accepted by Phys. Rev.
Diffusion-Limited Aggregation Processes with 3-Particle Elementary Reactions
A diffusion-limited aggregation process, in which clusters coalesce by means
of 3-particle reaction, A+A+A->A, is investigated. In one dimension we give a
heuristic argument that predicts logarithmic corrections to the mean-field
asymptotic behavior for the concentration of clusters of mass at time ,
, for . The total
concentration of clusters, , decays as at . We also investigate the problem with a localized steady source of
monomers and find that the steady-state concentration scales as
, , and , respectively,
for the spatial dimension equal to 1, 2, and 3. The total number of
clusters, , grows with time as , , and
for = 1, 2, and 3. Furthermore, in three dimensions we
obtain an asymptotic solution for the steady state cluster-mass distribution:
, with the scaling function
and the scaling variable .Comment: 12 pages, plain Te
Efficiency of Nonlinear Particle Acceleration at Cosmic Structure Shocks
We have calculated the evolution of cosmic ray (CR) modified astrophysical
shocks for a wide range of shock Mach numbers and shock speeds through
numerical simulations of diffusive shock acceleration (DSA) in 1D quasi-
parallel plane shocks. The simulations include thermal leakage injection of
seed CRs, as well as pre-existing, upstream CR populations. Bohm-like diffusion
is assumed. We model shocks similar to those expected around cosmic structure
pancakes as well as other accretion shocks driven by flows with upstream gas
temperatures in the range K and shock Mach numbers spanning
. We show that CR modified shocks evolve to time-asymptotic states
by the time injected particles are accelerated to moderately relativistic
energies (p/mc \gsim 1), and that two shocks with the same Mach number, but
with different shock speeds, evolve qualitatively similarly when the results
are presented in terms of a characteristic diffusion length and diffusion time.
For these models the time asymptotic value for the CR acceleration efficiency
is controlled mainly by shock Mach number. The modeled high Mach number shocks
all evolve towards efficiencies %, regardless of the upstream CR
pressure. On the other hand, the upstream CR pressure increases the overall CR
energy in moderate strength shocks (). (abridged)Comment: 23 pages, 12 ps figures, accepted for Astrophysical Journal (Feb. 10,
2005
Bogoliubov Hamiltonian as Derivative of Dirac Hamiltonian via Braid Relation
In this paper we discuss a new type of 4-dimensional representation of the
braid group. The matrices of braid operations are constructed by q-deformation
of Hamiltonians. One is the Dirac Hamiltonian for free electron with mass m,
the other, which we find, is related to the Bogoliubov Hamiltonian for
quasiparticles in He-B with the same free energy and mass being m/2. In the
process, we choose the free q-deformation parameter as a special value in order
to be consistent with the anyon description for fractional quantum Hall effect
with .Comment: 3 pages, 5 figure
An alternative formulation of classical electromagnetic duality
By introducing a doublet of electromagnetic four dimensional vector
potentials, we set up a manifestly Lorentz covariant and SO(2) duality
invariant classical field theory of electric and magnetic charges. In our
formulation one does not need to introduce the concept of Dirac string.Comment: 14 pages, no figures, Latex, minor corrections, references and
acknowledgements adde
Asymptotic behavior of A + B --> inert for particles with a drift
We consider the asymptotic behavior of the (one dimensional) two-species
annihilation reaction A + B --> 0, where both species have a uniform drift in
the same direction and like species have a hard core exclusion. Extensive
numerical simulations show that starting with an initially random distribution
of A's and B's at equal concentration the density decays like t^{-1/3} for long
times. This process is thus in a different universality class from the cases
without drift or with drift in different directions for the different species.Comment: LaTeX, 6pp including 3 figures in LaTeX picture mod
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