9,628 research outputs found
Combating corruption through employment law and whistleblower protection.
This article examines the extent to which employment law has the potential to fight corruption by imposing rights and duties on employers and workers and analyses the
extent to which the UN Convention on Corruption 2003 (UNCAC) protects those who speak out about malpractices within an organisation. Section 2 focuses on UNCAC while
Section 3 focuses on the extent to which employment law imposes obligations on those within the workplace to report corrupt activities and the circumstances in which those who speak out about corruption are protected under UK employment law. It is argued that because of the inadequacies of the existing legislation and the threat posed by disclosures via the Internet, organisations have much to gain from devising effective policies on both internal and external reporting that do not inhibit the exposure of corruption or unnecessarily curtail freedom of speech. The authors conclude by welcoming the draft
recommendations from the Council of Europe’s Parliamentary Assembly to draw up a set of guidelines for the protection of whistleblowers and consider drafting a framework
convention
Growth of primordial black holes in a universe containing a massless scalar field
The evolution of primordial black holes in a flat Friedmann universe with a
massless scalar field is investigated in fully general relativistic numerical
relativity. A primordial black hole is expected to form with a scale comparable
to the cosmological apparent horizon, in which case it may go through an
initial phase with significant accretion. However, if it is very close to the
cosmological apparent horizon size, the accretion is suppressed due to general
relativistic effects. In any case, it soon gets smaller than the cosmological
horizon and thereafter it can be approximated as an isolated vacuum solution
with decaying mass accretion. In this situation the dynamical and inhomogeneous
scalar field is typically equivalent to a perfect fluid with a stiff equation
of state . The black hole mass never increases by more than a factor of
two, despite recent claims that primordial black holes might grow substantially
through accreting quintessence. It is found that the gravitational memory
scenario, proposed for primordial black holes in Brans-Dicke and scalar-tensor
theories of gravity, is highly unphysical.Comment: 24 pages, accepted for publication in Physical Review
Accretion with back reaction
We calculate analytically a back reaction of the stationary spherical
accretion flow near the event horizon and near the inner Cauchy horizon of the
charged black hole. It is shown that corresponding back-reaction corrections to
the black hole metric depend only on the fluid accretion rate and diverge in
the case of an extremely charged black hole. In result, the test fluid
approximation for stationary accretion is violated for extreme black holes.
This behavior of the accreting black hole is in accordance with the third law
of black hole thermodynamics, forbidding the practical attainability of the
extreme state.Comment: 5 pages, 2 figures; new figure and references adde
Bose-Einstein condensates in standing waves: The cubic nonlinear Schroedinger equation with a periodic potential
We present a new family of stationary solutions to the cubic nonlinear
Schroedinger equation with a Jacobian elliptic function potential. In the limit
of a sinusoidal potential our solutions model a dilute gas Bose-Einstein
condensate trapped in a standing light wave. Provided the ratio of the height
of the variations of the condensate to its DC offset is small enough, both
trivial phase and nontrivial phase solutions are shown to be stable. Numerical
simulations suggest such stationary states are experimentally observable.Comment: 4 pages, 4 figure
Doppler cooling of gallium atoms: 2. Simulation in complex multilevel systems
This paper derives a general procedure for the numerical solution of the
Lindblad equations that govern the coherences arising from multicoloured light
interacting with a multilevel system. A systematic approach to finding the
conservative and dissipative terms is derived and applied to the laser cooling
of gallium. An improved numerical method is developed to solve the
time-dependent master equation and results are presented for transient cooling
processes. The method is significantly more robust, efficient and accurate than
the standard method and can be applied to a broad range of atomic and molecular
systems. Radiation pressure forces and the formation of dynamic dark-states are
studied in the gallium isotope 66Ga.Comment: 15 pages, 8 figure
Spontaneous soliton formation and modulational instability in Bose-Einstein condensates
The dynamics of an elongated attractive Bose-Einstein condensate in an
axisymmetric harmonic trap is studied. It is shown that density fringes caused
by self-interference of the condensate order parameter seed modulational
instability. The latter has novel features in contradistinction to the usual
homogeneous case known from nonlinear fiber optics. Several open questions in
the interpretation of the recent creation of the first matter-wave bright
soliton train [Strecker {\it et al.} Nature {\bf 417} 150 (2002)] are
addressed. It is shown that primary transverse collapse, followed by secondary
collapse induced by soliton--soliton interactions, produce bursts of hot atoms
at different time scales.Comment: 4 pages, 3 figures. Phys. Rev. Lett. in pres
Introduction - A synthesis of current understanding of the structural evolution of North Africa
Are black holes over-produced during preheating?
We provide a simple but robust argument that primordial black hole (PBH)
production generically does {\em not} exceed astrophysical bounds during the
resonant preheating phase after inflation. This conclusion is supported by
fully nonlinear lattice simulations of various models in two and three
dimensions which include rescattering but neglect metric perturbations. We
examine the degree to which preheating amplifies density perturbations at the
Hubble scale and show that at the end of the parametric resonance, power
spectra are universal, with no memory of the power spectrum at the end of
inflation. In addition we show how the probability distribution of density
perturbations changes from exponential on very small scales to Gaussian when
smoothed over the Hubble scale -- the crucial length for studies of primordial
black hole formation -- hence justifying the standard assumption of
Gaussianity.Comment: 12 pages, 8 figures, revtex, added references for section
The state space and physical interpretation of self-similar spherically symmetric perfect-fluid models
The purpose of this paper is to further investigate the solution space of
self-similar spherically symmetric perfect-fluid models and gain deeper
understanding of the physical aspects of these solutions. We achieve this by
combining the state space description of the homothetic approach with the use
of the physically interesting quantities arising in the comoving approach. We
focus on three types of models. First, we consider models that are natural
inhomogeneous generalizations of the Friedmann Universe; such models are
asymptotically Friedmann in their past and evolve fluctuations in the energy
density at later times. Second, we consider so-called quasi-static models. This
class includes models that undergo self-similar gravitational collapse and is
important for studying the formation of naked singularities. If naked
singularities do form, they have profound implications for the predictability
of general relativity as a theory. Third, we consider a new class of
asymptotically Minkowski self-similar spacetimes, emphasizing that some of them
are associated with the self-similar solutions associated with the critical
behaviour observed in recent gravitational collapse calculations.Comment: 24 pages, 12 figure
Semi-Static Hedging Based on a Generalized Reflection Principle on a Multi Dimensional Brownian Motion
On a multi-assets Black-Scholes economy, we introduce a class of barrier
options. In this model we apply a generalized reflection principle in a context
of the finite reflection group acting on a Euclidean space to give a valuation
formula and the semi-static hedge.Comment: Asia-Pacific Financial Markets, online firs
- …