1,048 research outputs found

    Holding Ugandan Police to Account: Case study of the Police Accountability and Reform Project

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    This chapter focuses on police accountability in Uganda, and in particular a project aimed at enhancing accountability

    Improving Police Integrity in Uganda: Impact Assessment of the Police Accountability and Reform Project

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    Uganda and in particular the Ugandan police are perceived as highly corrupt. To address the integrity of police officers, an intervention called the Police Accountability and Reform Project (PARP) was implemented in selected police districts between 2010 and early 2013. This paper studies the impact of PARP for a sample of 600 police officers that were interviewed about police integrity by means of twelve hypothetical vignette cases depicting context-specific, undesirable behaviour of varying degrees of severity. The assessments of the cases by the police officers are analysed using propensity score matching, inverse probability weighting and seemingly unrelated regression techniques. We show that self-selection of police officers into the program is unlikely to drive the results. The results suggest that officers participating in PARP activities (i) judge the presented cases of misconduct more severely, (ii) are more inclined to report misconduct and (iii) also expect their colleagues to judge misbehaviour at the level of the police more critically although the latter two coefficient estimates are smaller in size. This suggests that PARP activities have affected the perception of police officers but only encouraged them moderately to actually take action against bad practices

    Competition between spin and charge polarized states in nanographene ribbons with zigzag edges

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    Effects of the nearest neighbor Coulomb interaction on nanographene ribbons with zigzag edges are investigated using the extended Hubbard model within the unrestricted Hartree-Fock approximation. The nearest Coulomb interaction stabilizes a novel electronic state with the opposite electric charges separated and localized along both edges, resulting in a finite electric dipole moment pointing from one edge to the other. This charge-polarized state competes with the peculiar spin-polarized state caused by the on-site Coulomb interaction and is stabilized by an external electric field.Comment: 4 pages; 4 figures; accepted for publication in Phys. Rev. B; related Web site: http://staff.aist.go.jp/k.harigaya/index_E.htm

    Rectangular quantum dots in high magnetic fields

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    We use density-functional methods to study the effects of an external magnetic field on two-dimensional quantum dots with a rectangular hard-wall confining potential. The increasing magnetic field leads to spin polarization and formation of a highly inhomogeneous maximum-density droplet at the predicted magnetic field strength. At higher fields, we find an oscillating behavior in the electron density and in the magnetization of the dot. We identify a rich variety of phenomena behind the periodicity and analyze the complicated many-electron dynamics, which is shown to be highly dependent on the shape of the quantum dot.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

    Quantum Pumping and Quantized Magnetoresistance in a Hall Bar

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    We show how a dc current can be generated in a Hall bar without applying a bias voltage. The Hall resistance RHR_H that corresponds to this pumped current is quantized, just as in the usual integer quantum Hall effect (IQHE). In contrast with the IQHE, however, the longitudinal resistance RxxR_{xx} does not vanish on the plateaus, but equals the Hall resistance. We propose an experimental geometry to measure the pumped current and verify the predicted behavior of RHR_H and RxxR_{xx}.Comment: RevTeX, 3 figure

    Composite Fermion Description of Correlated Electrons in Quantum Dots: Low Zeeman Energy Limit

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    We study the applicability of composite fermion theory to electrons in two-dimensional parabolically-confined quantum dots in a strong perpendicular magnetic field in the limit of low Zeeman energy. The non-interacting composite fermion spectrum correctly specifies the primary features of this system. Additional features are relatively small, indicating that the residual interaction between the composite fermions is weak. \footnote{Published in Phys. Rev. B {\bf 52}, 2798 (1995).}Comment: 15 pages, 7 postscript figure

    Exact spectra, spin susceptibilities and order parameter of the quantum Heisenberg antiferromagnet on the triangular lattice

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    Exact spectra of periodic samples are computed up to N=36 N=36 . Evidence of an extensive set of low lying levels, lower than the softest magnons, is exhibited. These low lying quantum states are degenerated in the thermodynamic limit; their symmetries and dynamics as well as their finite-size scaling are strong arguments in favor of N\'eel order. It is shown that the N\'eel order parameter agrees with first-order spin-wave calculations. A simple explanation of the low energy dynamics is given as well as the numerical determinations of the energies, order parameter and spin susceptibilities of the studied samples. It is shown how suitable boundary conditions, which do not frustrate N\'eel order, allow the study of samples with N=3p+1 N=3p+1 spins. A thorough study of these situations is done in parallel with the more conventional case N=3p N=3p .Comment: 36 pages, REVTeX 3.0, 13 figures available upon request, LPTL preprin

    The deep propagating gravity wave experiment (deepwave): an airborne and ground-based exploration of gravity wave propagation and effects from their sources throughout the lower and middle atmosphere

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    Abstract The Deep Propagating Gravity Wave Experiment (DEEPWAVE) was designed to quantify gravity wave (GW) dynamics and effects from orographic and other sources to regions of dissipation at high altitudes. The core DEEPWAVE field phase took place from May through July 2014 using a comprehensive suite of airborne and ground-based instruments providing measurements from Earth’s surface to ∌100 km. Austral winter was chosen to observe deep GW propagation to high altitudes. DEEPWAVE was based on South Island, New Zealand, to provide access to the New Zealand and Tasmanian “hotspots” of GW activity and additional GW sources over the Southern Ocean and Tasman Sea. To observe GWs up to ∌100 km, DEEPWAVE utilized three new instruments built specifically for the National Science Foundation (NSF)/National Center for Atmospheric Research (NCAR) Gulfstream V (GV): a Rayleigh lidar, a sodium resonance lidar, and an advanced mesosphere temperature mapper. These measurements were supplemented by in situ probes, dropsondes, and a microwave temperature profiler on the GV and by in situ probes and a Doppler lidar aboard the German DLR Falcon. Extensive ground-based instrumentation and radiosondes were deployed on South Island, Tasmania, and Southern Ocean islands. Deep orographic GWs were a primary target but multiple flights also observed deep GWs arising from deep convection, jet streams, and frontal systems. Highlights include the following: 1) strong orographic GW forcing accompanying strong cross-mountain flows, 2) strong high-altitude responses even when orographic forcing was weak, 3) large-scale GWs at high altitudes arising from jet stream sources, and 4) significant flight-level energy fluxes and often very large momentum fluxes at high altitudes.David C. Fritts, Ronald B. Smith, Michael J. Taylor, James D. Doyle, Stephen D. Eckermann, Andreas Dörnbrack, Markus Rapp, Bifffford P. Williams, P.-Dominique Pautet, Katrina Bossert, Neal R. Criddddle, Carolyn A. Reynolds, P. Alex Reinecke, Michael Uddddstrom, Michael J. Revell, Richard Turner, Bernd Kaifler, Johannes S. Wagner, Tyler Mixa, Christopher G. Kruse, Alison D. Nugent, Campbell D. Watson, Sonja Gisinger, Steven M. Smith, Ruth S. Lieberman, Brian Laughman, James J. Moore, William O. Brown, Julie A. Haggerty, Alison Rockwell, Gregory J. Stossmeister, Steven F. Williams, Gonzalo Hernandez, Damian J. Murphy, Andrew R. Klekociuk, Iain M. Reid, and Jun M
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