The Effectiveness of State and Local Regulation of Handguns: A Statistical Analysis

One aspect of the continuing debate over weapons control, apart from Constitutional issues, is whether legislation is inherently capable of reducing crime and deaths by shooting. The opponents of increased control, tacitly admitting that empirical evidence is one means for measuring the effect of weapons regulation, have contended that [e]xpert opinion and compelling evidence seem to indicate that the amount or kind of crime in a community is not substantially affected by the relative ease with which a person can obtain a firearm. National Rifle Association of America, The Gun Law Problem 10. In the following study the authors employ data analysis techniques to examine the efficacy of state and municipal controls on handguns. They conclude that many lives would be saved if all states increased their level of control to that of New Jersey, the state having the most stringent gun control laws

The Effectiveness of State and Local Regulation of Handguns: A Statistical Analysis

One aspect of the continuing debate over weapons control, apart from Constitutional issues, is whether legislation is inherently capable of reducing crime and deaths by shooting. The opponents of increased control, tacitly admitting that empirical evidence is one means for measuring the effect of weapons regulation, have contended that [e]xpert opinion and compelling evidence seem to indicate that the amount or kind of crime in a community is not substantially affected by the relative ease with which a person can obtain a firearm. National Rifle Association of America, The Gun Law Problem 10. In the following study the authors employ data analysis techniques to examine the efficacy of state and municipal controls on handguns. They conclude that many lives would be saved if all states increased their level of control to that of New Jersey, the state having the most stringent gun control laws

Metal-insulator transitions in cyclotron resonance of periodic nanostructures due to avoided band crossings

A recently found metal-insulator transition in a model for cyclotron resonance in a two-dimensional periodic potential is investigated by means of spectral properties of the time evolution operator. The previously found dynamical signatures of the transition are explained in terms of avoided band crossings due to the change of the external electric field. The occurrence of a cross-like transport is predicted and numerically confirmed

Complexity in parametric Bose-Hubbard Hamiltonians and structural analysis of eigenstates

We consider a family of chaotic Bose-Hubbard Hamiltonians (BHH) parameterized by the coupling strength $k$ between neighboring sites. As $k$ increases the eigenstates undergo changes, reflected in the structure of the Local Density of States. We analyze these changes, both numerically and analytically, using perturbative and semiclassical methods. Although our focus is on the quantum trimer, the presented methodology is applicable for the analysis of longer lattices as well.Comment: 4 pages, 4 figure

Anomalous diffusion as a signature of collapsing phase in two dimensional self-gravitating systems

A two dimensional self-gravitating Hamiltonian model made by $N$ fully-coupled classical particles exhibits a transition from a collapsing phase (CP) at low energy to a homogeneous phase (HP) at high energy. From a dynamical point of view, the two phases are characterized by two distinct single-particle motions : namely, superdiffusive in the CP and ballistic in the HP. Anomalous diffusion is observed up to a time $\tau$ that increases linearly with $N$. Therefore, the finite particle number acts like a white noise source for the system, inhibiting anomalous transport at longer times.Comment: 10 pages, Revtex - 3 Figs - Submitted to Physical Review

Sequential Desynchronization in Networks of Spiking Neurons with Partial Reset

The response of a neuron to synaptic input strongly depends on whether or not it has just emitted a spike. We propose a neuron model that after spike emission exhibits a partial response to residual input charges and study its collective network dynamics analytically. We uncover a novel desynchronization mechanism that causes a sequential desynchronization transition: In globally coupled neurons an increase in the strength of the partial response induces a sequence of bifurcations from states with large clusters of synchronously firing neurons, through states with smaller clusters to completely asynchronous spiking. We briefly discuss key consequences of this mechanism for more general networks of biophysical neurons

What determines the spreading of a wave packet?

The multifractal dimensions D2^mu and D2^psi of the energy spectrum and eigenfunctions, resp., are shown to determine the asymptotic scaling of the width of a spreading wave packet. For systems where the shape of the wave packet is preserved the k-th moment increases as t^(k*beta) with beta=D2^mu/D2^psi, while in general t^(k*beta) is an optimal lower bound. Furthermore, we show that in d dimensions asymptotically in time the center of any wave packet decreases spatially as a power law with exponent D_2^psi - d and present numerical support for these results.Comment: Physical Review Letters to appear, 4 pages postscript with figure

Efficient Diagonalization of Kicked Quantum Systems

We show that the time evolution operator of kicked quantum systems, although a full matrix of size NxN, can be diagonalized with the help of a new method based on a suitable combination of fast Fourier transform and Lanczos algorithm in just N^2 ln(N) operations. It allows the diagonalization of matrizes of sizes up to N\approx 10^6 going far beyond the possibilities of standard diagonalization techniques which need O(N^3) operations. We have applied this method to the kicked Harper model revealing its intricate spectral properties.Comment: Text reorganized; part on the kicked Harper model extended. 13 pages RevTex, 1 figur