8,316 research outputs found
Urban crime and labor mobility
We present a model of crime where two municipalities exist within a metro area (MSA). Consistent with the literature, local law enforcement has a crime reduction effect and a crime diversion effect. The former confers a spillover benefit to the other municipality, while the latter a spillover cost. If the net spillovers are positive (negative), then the respective Nash enforcement levels are too low (high) from the perspective of the MSA. When we allow for Tiebout type mobility, labor will move to the location offering lower disutility crime (including the tax burden). To attract labor both jurisdictions would like to raise the relative crime that exists in the competing region. Interestingly, this could raise or reduce enforcement compared to the immobility case. If it was too high (low) under immobility, it will be raised (reduced) further under mobility. In the symmetric case, neither can gain any labor, but the competition for it pushes the jurisdictions further away from the efficient (cooperative) outcome. Thus, mobility must be welfare reducing. We also consider asymmetry in the context of differences in efficiency of enforcement. The low cost municipality has the lower crime damage (inclusive of the tax burden) and attracts labor. Mobility is necessarily welfare reducing for the high cost municipality and for the MSA, but it has an ambiguous effect on the low cost municipality.Crime - Economic aspects ; Labor mobility - United States
Quantum heat transfer in harmonic chains with self consistent reservoirs: Exact numerical simulations
We describe a numerical scheme for exactly simulating the heat current
behavior in a quantum harmonic chain with self-consistent reservoirs.
Numerically-exact results are compared to classical simulations and to the
quantum behavior under the linear response approximation. In the classical
limit or for small temperature biases our results coincide with previous
calculations. At large bias and for low temperatures the quantum dynamics of
the system fundamentally differs from the close-to-equilibrium behavior,
revealing in particular the effect of thermal rectification for asymmetric
chains. Since this effect is absent in the classical analog of our model, we
conclude that in the quantum model studied here thermal rectification is a
purely quantum phenomenon, rooted in the quantum statistics
Charge and Statistics of Quasiparticles in Fractional Quantum Hall Effec
We have studied here the charge and statistics of quasiparticle excitations
in FQH states on the basis of the Berry phase approach incorporating the fact
that even number of flux quanta can be gauged away when the Berry phase is
removed to the dynamical phase. It is observed that the charge and
statistical parameter of a quasiparticle at filling factor
are given by and
, with the fact that the charge of the quasihole is
opposite to that of the quasielectron. Using Laughlin wave function for
quasiparticles, numerical studies have been done following the work of
Kj{\o}nsberg and Myrheim \cite{KM} for FQH states at and it is
pointed out that as in case of quasiholes, the statistics parameter can be well
defined for quasielectrons having the value .Comment: 12 pages, 4 figure
Single spin universal Boolean logic
Recent advances in manipulating single electron spins in quantum dots have
brought us close to the realization of classical logic gates based on
representing binary bits in spin polarizations of single electrons. Here, we
show that a linear array of three quantum dots, each containing a single spin
polarized electron, and with nearest neighbor exchange coupling, acts as the
universal NAND gate. The energy dissipated during switching this gate is the
Landauer-Shannon limit of kTln(1/p) [T = ambient temperature and p = intrinsic
gate error probability]. With present day technology, p = 1E-9 is achievable
above 1 K temperature. Even with this small intrinsic error probability, the
energy dissipated during switching the NAND gate is only ~ 21 kT, while today's
nanoscale transistors dissipate about 40,000 - 50,000 kT when they switch
Quantum thermodynamics of a charged magneto-oscillator coupled to a heat bath
Explicit results for various quantum thermodynamic function (QTF) of a
charged magneto-oscillator coupled to a heat bath at arbitrary temperature are
demonstrated in this paper. Discernible expressions for different QTF in the
two limits of very low and very high temperatures are presented for three
popular heat bath models : Ohmic, single relaxation time and blackbody
radiation. The central result is that the effect of magnetic field turns out to
be important at low temperatures yet crucial at high temperatures. It is
observed that the dissipation parameter, , and the cyclotron frequency,
, affect the decaying or rising behaviour of various QTF in just the
opposite way to each other at low temperatures. In the high temperature regime,
the effect of is much pronounced than that of .Comment: 26 Pages, 18 Figure
Infrared Spectroscopy of GX 1+4/V2116 Oph: Evidence for a Fast Red Giant Wind?
We present infrared spectroscopy of the low-mass X-ray binary GX 1+4/V2116
Oph. This symbiotic binary consists of a 2-min accretion-powered pulsar and an
M5 III red giant. A strong He I 1.083 micron emission line with a pronounced P
Cygni profile was observed. From the blue edge of this feature, we infer an
outflow velocity of 250(50) km/s. This is an order of magnitude faster than a
typical red giant wind, and we suggest that radiation from the accretion disk
or the neutron star may contribute to the acceleration of the outflow. We infer
a wind mass loss rate of around 10^-6 Msun/yr. Accretion from such a strong
stellar wind provides a plausible alternative to Roche lobe overflow for
supplying the accretion disk which powers the X-ray source. The H I Paschen
beta and He I 1.083 micron lines showed no evidence for the dramatic changes
previously reported in some optical lines, and no evidence for pulsations at
the 2-min pulsar period.Comment: 11 pages including 2 PS figures. To appear in ApJ Letter
Study of electron spin dynamics in grain aligned LaCoPO: an itinerant ferromagnet
139La NMR study was performed in grain aligned (c|| H0) sample of LaCoPO and
polycrystalline LaFePO. Knight shift is isotropic and temperature independent
in LaFePO. It is strongly temperature dependent and anisotropic in LaCoPO. The
spin-lattice relaxation rate in LaCoPO clearly reveals the existence of 3D spin
fluctuations both in the paramagnetic and ferromagnetic state over and above
the dominant 2D spin fluctuations in the paramagnetic state, observed earlier
from 31P NMR measurements in the same oriented sample. The spin fluctuation
parameters in LaCoPO determined from 139La NMR relaxation and magnetization
data, using the self consistent renormalization (SCR) theory, are in close
agreement and follow the universal Rhodes-Wohlfarth curve.Comment: Accepted in PR
Entanglement production in Quantized Chaotic Systems
Quantum chaos is a subject whose major goal is to identify and to investigate
different quantum signatures of classical chaos. Here we study entanglement
production in coupled chaotic systems as a possible quantum indicator of
classical chaos. We use coupled kicked tops as a model for our extensive
numerical studies. We find that, in general, presence of chaos in the system
produces more entanglement. However, coupling strength between two subsystems
is also very important parameter for the entanglement production. Here we show
how chaos can lead to large entanglement which is universal and describable by
random matrix theory (RMT). We also explain entanglement production in coupled
strongly chaotic systems by deriving a formula based on RMT. This formula is
valid for arbitrary coupling strengths, as well as for sufficiently long time.
Here we investigate also the effect of chaos on the entanglement production for
the mixed initial state. We find that many properties of the mixed state
entanglement production are qualitatively similar to the pure state
entanglement production. We however still lack an analytical understanding of
the mixed state entanglement production in chaotic systems.Comment: 16 pages, 5 figures. To appear in Pramana:Journal of Physic
Abatement of particulate-laden SO2 in tapered bubble column with internals
The performance of particulate-laden SO2 scrubbing in a modified tapered bubble column with internals is reported in this article. The presence of particles improved the particulate-laden SO2 removal efficiency to about 15% that was elucidated by the facilitated adsorptive mass transport. Experimentation revealed that nearly 100% removal efficiency of particulate-laden SO2 was achievable without any additives or pretreatment under certain operating condition of the scrubber. An empirical correlation was developed to predict the performance of the modified tapered scrubber. Experimental values fitted excellently well with the predicted values through the correlation (within ±5% deviation). The performance of the modified tapered bubble scrubber with column internals has been found to be better than a tapered bubble column without any internals
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