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

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    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

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    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 +iϵ+i\epsilon 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 ΣI\Sigma_I and ΣF\Sigma_F; both are diffeomorphic to R3{\Bbb R}^3. Denote by TT the (real) Lorentzian proper-time interval between the surfaces, as measured at spatial infinity. Then rotate: TTexp(iθ),0<θπ/2T\to{\mid}T{\mid}\exp(-i\theta),0<\theta\leq \pi/2. The {\it classical} boundary-value problem is expected to be well-posed on a region of topology I×R3I\times{\Bbb R}^3, where II is a closed interval. For a locally-supersymmetric theory, the quantum amplitude should be dominated by the semi-classical expression exp(iSclass)\exp(iS_{\rm class}), where SclassS_{\rm class} is the classical action. One finds the Lorentzian quantum amplitude from the limit θ0+\theta\to 0_+. 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 ΣF\Sigma_F, provided that it has the correct mass MM -- 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

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    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

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    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

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    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

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    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 (gμν)(g_{\mu \nu}), while the (3+1) spacelike slicing approach involves restrictions on (gμν)(g^{\mu \nu}). 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 η>0\eta > 0 and λ>0\lambda > 0 such that for η1\eta 1) 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

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    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.

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    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

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    Quantum amplitudes for s=1s=1 at Maxwell fields and for s=2s=2 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 s=0s=0 scalar-field perturbations of gravitational collapse at late times. In both the s=1s=1 and s=2s=2 cases, we isolate suitable 'co-ordinate' variables which can be taken as boundary data on a final space-like hypersurface ΣF\Sigma_F. For simplicity, we take the data on an initial pre-collapse surface ΣI\Sigma_I to be exactly spherically symmetric. The (large) Lorentzian proper-time interval between ΣI,ΣF\Sigma_{I}, \Sigma_{F}, measured at spatial infinity, is denoted by TT. The complexified classical boundary-value problem is expected to be well-posed, provide that the time interval TT has been rotated into the complex: TTexp(iθ)T\to{\mid}T{\mid}\exp(-i\theta), for 0<θπ/20<\theta\leq{\pi}/2. We calculate the second-variation classical Lorenztian action Sclass(2)S ^{(2)}_{\rm class}. Following Feynman, we recover the Lorentzian quantum amplitude by taking the limit as θ0+\theta\to 0_+ of the semi-classical amplitude exp(iSclass(2))\exp(iS^{(2)}_{\rm class}). The boundary data for s=1 s=1 involve the Maxwell magnetic field; the data for s=2s=2 involve the magnetic part of the Weyl curvature tensor. The magnetic boundary conditions are related to each other and to the natural s=12s={1 \over 2} boundary conditions by supersymmetry

    Inferring black hole charge from backscattered electromagnetic radiation

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    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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