70,365 research outputs found
Firm corruption in the presence of an auditor
This paper develops a framework to explore firm corruption taking account of interaction with an auditor. The basic idea is that an auditor can provide auditing and other (consultancy) services. The extent of the other services depends on firm profitability. Hence auditor profitability can increase with firm corruption that may provide an incentive to collude in corrupt practices. This basic idea is developed using a game theoretic framework. It is shown that a multiplicity of equilibria exist from stable corruption, through auditor controlled corruption, via multiple equilibria to honesty on behalf of both actors. Following the development of the model various policy options are highlighted that show the difficulty of completely removing corrupt practices
Reply on `comment on our paper `Single two-level ion in an anharmonic-oscillator trap: Time evolution of the Q function and population inversion ''
We show here that the model Hamiltonian used in our paper for ion vibrating
in a q-analog harmonic oscillator trap and interacting with a classical
single-mode light field is indeed obtained by replacing the usual bosonic
creation and annihilation operators of the harmonic trap model by their
q-deformed counterparts. The approximations made in our paper amount to using
for the ion-laser interaction in a q-analog harmonic oscillator trap, the
operator F_{q}=exp{-(|\epsilon|^2}/2)}exp{i\epsilon A^{\dagger}}exp{i\epsilon
A}, which is analogous to the corresponding operator for ion in a harmonic
oscillator trap that is . In our article we do not claim to have diagonalized the
operator, , for which the basis states
|g,m> and |e,m> are not analytic vectors.Comment: Revtex, 4pages. To be Published in Physical Review A59, NO.4(April
99
A critical layer model for turbulent pipe flow
A model-based description of the scaling and radial location of turbulent
fluctuations in turbulent pipe flow is presented and used to illuminate the
scaling behaviour of the very large scale motions. The model is derived by
treating the nonlinearity in the perturbation equation (involving the Reynolds
stress) as an unknown forcing, yielding a linear relationship between the
velocity field response and this nonlinearity. We do not assume small
perturbations. We examine propagating modes, permitting comparison of our
results to experimental data, and identify the steady component of the velocity
field that varies only in the wall-normal direction as the turbulent mean
profile. The "optimal" forcing shape, that gives the largest velocity response,
is assumed to lead to modes that will be dominant and hence observed in
turbulent pipe flow.
An investigation of the most amplified velocity response at a given
wavenumber-frequency combination reveals critical layer-like behaviour
reminiscent of the neutrally stable solutions of the Orr-Sommerfeld equation in
linearly unstable flow. Two distinct regions in the flow where the influence of
viscosity becomes important can be identified, namely a wall layer that scales
with and a critical layer, where the propagation velocity is equal
to the local mean velocity, that scales with in pipe flow. This
framework appears to be consistent with several scaling results in wall
turbulence and reveals a mechanism by which the effects of viscosity can extend
well beyond the immediate vicinity of the wall.Comment: Submitted to the Journal of Fluid Mechanics and currently under
revie
On the design of optimal compliant walls for turbulence control
This paper employs the theoretical framework developed by Luhar et al. (J.
Fluid Mech., 768, 415-441) to consider the design of compliant walls for
turbulent skin friction reduction. Specifically, the effects of simple
spring-damper walls are contrasted with the effects of more complex walls
incorporating tension, stiffness and anisotropy. In addition, varying mass
ratios are tested to provide insight into differences between aerodynamic and
hydrodynamic applications. Despite the differing physical responses, all the
walls tested exhibit some important common features. First, the effect of the
walls (positive or negative) is greatest at conditions close to resonance, with
sharp transitions in performance across the resonant frequency or phase speed.
Second, compliant walls are predicted to have a more pronounced effect on
slower-moving structures because such structures generally have larger
wall-pressure signatures. Third, two-dimensional (spanwise constant) structures
are particularly susceptible to further amplification. These features are
consistent with many previous experiments and simulations, suggesting that
mitigating the rise of such two-dimensional structures is essential to
designing performance-improving walls. For instance, it is shown that further
amplification of such large-scale two-dimensional structures explains why the
optimal anisotropic walls identified by Fukagata et al. via DNS (J. Turb., 9,
1-17) only led to drag reduction in very small domains. The above observations
are used to develop design and methodology guidelines for future research on
compliant walls
Production of nuclei and antinuclei in pp and Pb-Pb collisions with ALICE at the LHC
We present first results on the production of nuclei and antinuclei such as
(anti)deuterons, (anti)tritons, (anti)3He and (anti)4He in pp collisions at
\s = 7 TeV and Pb-Pb collisions at \sNN = 2.76 TeV. These particles are
identified using their energy loss (dE/dx) information in the Time Projection
Chamber of the ALICE experiment. The Inner Tracking System gives a precise
determination of the event vertex, by which primary and secondary particles are
separated. The high statistics of over 360 million events for pp and 16 million
events for Pb-Pb collisions give a significant number of light nuclei and
antinuclei (Pb-Pb collisions: \sim30,000 anti-deuterons() and \sim4
anti-alpha()). The predictions of various particle ratios from the
THERMUS model is also discussed.Comment: 4 pages, 5 figures, parallel talk at Quark Matter 2011, May 23rd-28th
2011, Annecy, Franc
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