1,634 research outputs found
Evasion and Flowback in the Regulation S Era: Strengthening U.S. Investor Protection While Promoting U.S. Corporate Offshore Offerings
This Note examines whether the structure of Regulation S has caused increased flowback of unregistered securities into the United States. Part I discusses the development of the offshore capital markets and the registration requirements of the Securities Act. Part I also details the evolution of the SEC\u27s application of the Securities Act registration requirements to international securities sales, and summarizes Regulation S. Part II discusses the benefits to issuers of using Regulation S, and the effect that Regulation S has had on U.S. corporate participation in the offshore markets. Part II also analyzes the threat that flowback poses to the Securities Act disclosure requirements, and examines the mechanisms through which unregistered securities flow back into the United States. Part III argues that neither SEC enforcement efforts, nor the currently extant private remedy, can effectively curtail the flowback problem caused by Regulation S. In addition, Part III provides recommendations for amending Regulation S to ensure greater protection for U.S. investors and greater certainty for U.S. issuers in offshore transactions. This Note concludes that the SEC should revisit Regulation S in order achieve a workable balance between access for issuers and protection for investors
Bogoliubov transformations for amplitudes in black-hole evaporation
The familiar approach to quantum radiation following collapse to a black hole
proceeds via Bogoliubov transformations, and yields probabilities for final
outcomes. In our (complex) approach, we find quantum amplitudes, not just
probabilities, by following Feynman's prescription. Initial and
final data for Einstein gravity and (say) a massless scalar field are specified
on a pair of asymptotically-flat space-like hypersurfaces and
; both are diffeomorphic to . Denote by the (real)
Lorentzian proper-time interval between the surfaces, as measured at spatial
infinity. Then rotate: .
The {\it classical} boundary-value problem is expected to be well-posed on a
region of topology , where is a closed interval. For a
locally-supersymmetric theory, the quantum amplitude should be dominated by the
semi-classical expression , where is the
classical action. One finds the Lorentzian quantum amplitude from the limit
. In the usual approach, the only possible such final surfaces
are in the strong-field region shortly before the curvature singularity. In our
approach one can put arbitrary smooth gravitational data on ,
provided that it has the correct mass -- the singularity is by-passed in
the analytic continuation. Here, we consider Bogoliubov transformations and
their possible relation to the probability distribution and density matrix in
the traditional approach. We find that our probability distribution for
configurations of the final scalar field cannot be expressed in terms of the
diagonal elements of some non-trivial density-matrix distribution
Dynamics of electromagnetic waves in Kerr geometry
Here we are interested to study the spin-1 particle i.e., electro-magnetic
wave in curved space-time, say around black hole. After separating the
equations into radial and angular parts, writing them according to the black
hole geometry, say, Kerr black hole we solve them analytically. Finally we
produce complete solution of the spin-1 particles around a rotating black hole
namely in Kerr geometry. Obviously there is coupling between spin of the
electro-magnetic wave and that of black hole when particles propagate in that
space-time. So the solution will be depending on that coupling strength. This
solution may be useful to study different other problems where the analytical
results are needed. Also the results may be useful in some astrophysical
contexts.Comment: 15 Latex pages, 4 Figures; Accepted for publication in Classical and
Quantum Gravit
Fermion scattering by a Schwarzschild black hole
We study the scattering of massive spin-half waves by a Schwarzschild black
hole using analytical and numerical methods. We begin by extending a recent
perturbation theory calculation to next order to obtain Born series for the
differential cross section and Mott polarization, valid at small couplings. We
continue by deriving an approximation for glory scattering of massive spinor
particles by considering classical timelike geodesics and spin precession.
Next, we formulate the Dirac equation on a black hole background, and outline a
simple numerical method for finding partial wave series solutions. Finally, we
present our numerical calculations of absorption and scattering cross sections
and polarization, and compare with theoretical expectations.Comment: Minor changes, 1 figure added. Version to appear in Phys. Rev. D. 36
pages, 13 figure
Regularization of the Teukolsky Equation for Rotating Black Holes
We show that the radial Teukolsky equation (in the frequency domain) with
sources that extend to infinity has well-behaved solutions. To prove that, we
follow Poisson approach to regularize the non-rotating hole, and extend it to
the rotating case. To do so we use the Chandrasekhar transformation among the
Teukolsky and Regge-Wheeler-like equations, and express the integrals over the
source in terms of solutions to the homogeneous Regge-Wheeler-like equation, to
finally regularize the resulting integral. We then discuss the applicability of
these results.Comment: 14 pages, 1 Table, REVTE
Spacetime Splitting, Admissible Coordinates and Causality
To confront relativity theory with observation, it is necessary to split
spacetime into its temporal and spatial components. The (1+3) timelike
threading approach involves restrictions on the gravitational potentials
, while the (3+1) spacelike slicing approach involves
restrictions on . These latter coordinate conditions protect
chronology within any such coordinate patch. While the threading coordinate
conditions can be naturally integrated into the structure of Lorentzian
geometry and constitute the standard coordinate conditions in general
relativity, this circumstance does not extend to the slicing coordinate
conditions. We explore the influence of chronology violation on wave motion. In
particular, we consider the propagation of radiation parallel to the rotation
axis of stationary G\"odel-type universes characterized by parameters and such that for ) chronology is
protected (violated). We show that in the WKB approximation such waves can
freely propagate only when chronology is protected.Comment: 25 pages, 3 figures; v2: minor typos corrected, accepted for
publication in Phys. Rev.
What We Bring With Us and What We Leave Behind: Six Months in Post-Apartheid South Africa
The authors, a family, reflect on their experiences living, volunteering, and going to school in South Africa for six months. They sought to live in a society in which white people were not the majority and to experience the transformation of the new South Africa, not as tourists, but as participants
How a Supply Chain Stumble Changes a Company’s Policies and Progress 20 years Later: A Case Study of Gap Inc.
Gap Inc. is the third-largest American retailer. Founded in 1969, Gap Inc. holds four brands, Gap, Banana Republic, Old Navy and Athleta. In the late 1990s and early 2000s Gap Inc. made headlines for child labor abuses along with many other large brands. After this negative attention, Gap Inc. began developing policies and practices to combat ethical supply chain issues. These policies included a Human Rights Policy, a Code of Vendor Conduct, working conditions standards, and even capacity building programs that boarded company reaches into communities they touch. In conjunction with the policies Gap Inc. has published several social responsibility reports that have displayed the outcomes of their policies. Overall, this thesis explores how Gap Inc. policies and practices have developed since receiving negative media attention and how Gap Inc. compares in a fashion industry that does not play fair
Quantum amplitudes in black-hole evaporation: Spins 1 and 2
Quantum amplitudes for at Maxwell fields and for linearised
gravitational wave perturbations of a spherically symmetric Einstein/massless
scalar background, describing gravitational collapse to a black hole, are
treated by analogy with a previous treatment of scalar-field
perturbations of gravitational collapse at late times. In both the and
cases, we isolate suitable 'co-ordinate' variables which can be taken as
boundary data on a final space-like hypersurface . For simplicity, we
take the data on an initial pre-collapse surface to be exactly
spherically symmetric. The (large) Lorentzian proper-time interval between
, measured at spatial infinity, is denoted by . The
complexified classical boundary-value problem is expected to be well-posed,
provide that the time interval has been rotated into the complex:
, for . We calculate the
second-variation classical Lorenztian action . Following
Feynman, we recover the Lorentzian quantum amplitude by taking the limit as
of the semi-classical amplitude .
The boundary data for involve the Maxwell magnetic field; the data for
involve the magnetic part of the Weyl curvature tensor. The magnetic
boundary conditions are related to each other and to the natural boundary conditions by supersymmetry
Inferring black hole charge from backscattered electromagnetic radiation
We compute the scattering cross section of Reissner-Nordström black holes for the case of an incident electromagnetic wave. We describe how scattering is affected by both the conversion of electromagnetic to gravitational radiation, and the parity dependence of phase shifts induced by the black hole charge. The latter effect creates a helicity-reversed scattering amplitude that is nonzero in the backward direction. We show that from the character of the electromagnetic wave scattered in the backward direction it is possible, in principle, to infer if a static black hole is charged
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