32,367 research outputs found
Professionalising policing: seeking viable and sustainable approaches to police education and learning
This paper will explore the ‘police professionalization agenda’ and provide a brief outline of the ‘Police Qualification Education Framework’ (PEQF) administered by the College of Policing (CoP) in the United Kingdom, discuss the art, craft and science as a platform for evolving professionalization in policing and finally consider the future of policing with advances in technology.
I will argue that the police service not only needs to consider how technology will affect the roles and activities of the police but also the impact on the communities that the police serve
Von Neumann entropy and localization-delocalization transition of electron states in quantum small-world networks
The von Neumann entropy for an electron in periodic, disorder and
quasiperiodic quantum small-world networks(QSWNs) are studied numerically. For
the disorder QSWNs, the derivative of the spectrum averaged von Neumann entropy
is maximal at a certain density of shortcut links p*, which can be as a
signature of the localization delocalization transition of electron states. The
transition point p* is agreement with that obtained by the level statistics
method. For the quasiperiodic QSWNs, it is found that there are two regions of
the potential parameter. The behaviors of electron states in different regions
are similar to that of periodic and disorder QSWNs, respectively.Comment: 6 pages, 13figure
Instanton Effects in Three-Dimensional Supersymmetric Gauge Theories with Matter
Using standard field theory techniques we compute perturbative and instanton
contributions to the Coulomb branch of three-dimensional supersymmetric QCD
with N=2 and N=4 supersymmetry and gauge group SU(2). For the N=4 theory with
one massless flavor, we confirm the proposal of Seiberg and Witten that the
Coulomb branch is the double-cover of the centered moduli space of two BPS
monopoles constructed by Atiyah and Hitchin. Introducing a hypermultiplet mass
term, we show that the asymptotic metric on the Coulomb branch coincides with
the metric on Dancer's deformation of the monopole moduli space. For the N=2
theory with flavors, we compute the one-loop corrections to the metric
and complex structure on the Coulomb branch. We then determine the
superpotential including one-loop effects around the instanton background.
These calculations provide an explicit check of several results previously
obtained by symmetry and holomorphy arguments.Comment: 24 pages, Late
von Neumann entropy and localization properties of two interacting particles in one-dimensional nonuniform systems
With the help of von Neumann entropy, we study numerically the localization
properties of two interacting particles (TIP) with on-site interactions in
one-dimensional disordered, quasiperiodic, and slowly varying potential
systems, respectively. We find that for TIP in disordered and slowly varying
potential systems, the spectrum-averaged von Neumann entropy first
increases with interaction U until its peak, then decreases as U gets larger.
For TIP in the Harper model[S. N. Evangelou and D. E. Katsanos, Phys. Rev. B
56, 12797(1997)], the functions of versus U are different for particles
in extended and localized regimes. Our numerical results indicate that for
these two-particle systems, the von Neumann entropy is a suitable quantity to
characterize the localization properties of particle states. Moreover, our
studies propose a consistent interpretation of the discrepancies between
previous numerical results.Comment: 7 pages,13 figure
Lunar landing module reflectivity model
Lunar landing module reflectivity model based on Surveyor and Orbiter photographs of lunar craters, hills, and boulder
Probable deviations in altitude reading given by the LM altimeter for the most rough surface along a certain given trajectory
Random noise calculations in altitude reading of lunar module altimeter for rough surfaces targe
Fidelity, fidelity susceptibility and von Neumann entropy to characterize the phase diagram of an extended Harper model
For an extended Harper model, the fidelity for two lowest band edge states
corresponding to different model parameters, the fidelity susceptibility and
the von Neumann entropy of the lowest band edge states, and the
spectrum-averaged von Neumann entropy are studied numerically, respectively.
The fidelity is near one when parameters are in the same phase or same phase
boundary; otherwise it is close to zero. There are drastic changes in fidelity
when one parameter is at phase boundaries. For fidelity susceptibility the
finite scaling analysis performed, the critical exponents , ,
and depend on system sizes for the metal-metal phase transition, while
not for the metal-insulator phase transition. For both phase transitions
. The von Neumann entropy is near one for the metallic
phase, while small for the insulating phase. There are sharp changes in von
Neumann entropy at phase boundaries. According to the variation of the
fidelity, fidelity susceptibility, and von Neumann entropy with model
parameters, the phase diagram, which including two metallic phases and one
insulating phase separated by three critical lines with one bicritical point,
can be completely characterized, respectively. These numerical results indicate
that the three quantities are suited for revealing all the critical phenomena
in the model.Comment: 9 pages, 12 figure
Strongly modulated transmissions in gapped armchair graphene nanoribbons with sidearm or on-site gate voltage
We propose two schemes of field-effect transistor based on gapped armchair
graphene nanoribbons connected to metal leads, by introducing sidearms or
on-site gate voltages. We make use of the band gap to reach excellent
switch-off character. By introducing one sidearm or on-site gate to the
graphene nanoribbon, conduction peaks appear inside the gap regime. By further
applying two sidearms or on-site gates, these peaks are broadened to conduction
plateaus with a wide energy window, thanks to the resonance from the dual
structure. The position of the conduction windows inside the gap can be fully
controlled by the length of the sidearms or the on-site gate voltages, which
allows "on" and "off" operations for a specific energy window inside the gap
regime. The high robustness of both the switch-off character and the conduction
windows is demonstrated and shows the feasibility of the proposed dual
structures for real applications.Comment: 6 pages, 6 figure
Gravitational Lensing by Dark Matter Halos with Non-universal Density Profiles
The statistics of gravitational lensing can provide us with a very powerful
probe of the mass distribution of matter in the universe. By comparing
predicted strong lensing probabilities with observations, we can test the mass
distribution of dark matter halos, in particular, the inner density slope. In
this letter, unlike previous work that directly models the density profiles of
dark matter halos semi-analytically, we generalize the density profiles of dark
matter halos from high-resolution N-body simulations by means of generalized
Navarro-Frenk-White (GNFW) models of three populations with slopes, ,
of about -1.5, -1.3 and -1.1 for galaxies, groups and clusters, respectively.
This approach is an alternative and independent way to examine the slopes of
mass density profiles of halos. We present calculations of lensing
probabilities using these GNFW profiles for three populations in various
spatially flat cosmological models with a cosmological constant . It
is shown that the compound model of density profiles does not match well with
the observed lensing probabilities derived from the Jodrell-Bank VLA
Astrometric Survey data in combination with the Cosmic Lens All-Sky Survey
data. Together with the previous work on lensing probability, our results
suggest that a singular isothermal sphere mass model of less than about
10^{13}h^{-1}M_{\sun} can predict strong lensing probabilities that are
consistent with observations of small splitting angles.Comment: 11 pages, 2 figures, Accepted by ApJL for publication (February 10
issue 2004
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