1,265 research outputs found
Liquidity Costs and Stock Price Response to Convertible Security Calls
Firms\u27 announcements to call in-the-money convertible securities for redemption essentially force their conversion into common stock, and such announcements are generally met with significant reductions in the calling firms\u27 equity values. An explanation based on liquidity costs is advanced and tested. The explanation implies that investors who choose to sell their shares early in the conversion period bear liquidity costs by selling at reduced prices. Consistent with the explanation, the average share price decline is short-lived, lasting most of the conversion period. Thus, a component of the call announcement effect appears to be due to liquidity costs
Preroughening, Diffusion, and Growth of An FCC(111) Surface
Preroughening of close-packed fcc(111) surfaces, found in rare gas solids, is
an interesting, but poorly characterized phase transition. We introduce a
restricted solid-on-solid model, named FCSOS, which describes it. Using mostly
Monte Carlo, we study both statics, including critical behavior and scattering
properties, and dynamics, including surface diffusion and growth. In antiphase
scattering, it is shown that preroughening will generally show up at most as a
dip. Surface growth is predicted to be continuous at preroughening, where
surface self-diffusion should also drop. The physical mechanism leading to
preroughening on rare gas surfaces is analysed, and identified in the step-step
elastic repulsion.Comment: Revtex + uuencoded figures, to appear in Physical Review Letter
Unique continuation results for Ricci curvature and applications
Unique continuation results are proved for metrics with prescribed Ricci
curvature in the setting of bounded metrics on compact manifolds with boundary,
and in the setting of complete, conformally compact metrics. Related to this
issue, an isometry extension property is proved: continuous groups of
isometries at conformal infinity extend into the bulk of any complete
conformally compact Einstein metric. Relations of this property with the
invariance of the Gauss-Codazzi constraint equations under deformations are
also discussed.Comment: 32 pages, supercedes math.DG/0501067; final published versio
On ``hyperboloidal'' Cauchy data for vacuum Einstein equations and obstructions to smoothness of ``null infinity''
Various works have suggested that the Bondi--Sachs--Penrose decay conditions
on the gravitational field at null infinity are not generally representative of
asymptotically flat space--times. We have made a detailed analysis of the
constraint equations for ``asymptotically hyperboloidal'' initial data and find
that log terms arise generically in asymptotic expansions. These terms are
absent in the corresponding Bondi--Sachs--Penrose expansions, and can be
related to explicit geometric quantities. We have nevertheless shown that there
exists a large class of ``non--generic'' solutions of the constraint equations,
the evolution of which leads to space--times satisfying the
Bondi--Sachs--Penrose smoothness conditions.Comment: 8 pages, revtex styl
Stability in Designer Gravity
We study the stability of designer gravity theories, in which one considers
gravity coupled to a tachyonic scalar with anti-de Sitter boundary conditions
defined by a smooth function W. We construct Hamiltonian generators of the
asymptotic symmetries using the covariant phase space method of Wald et al.and
find they differ from the spinor charges except when W=0. The positivity of the
spinor charge is used to establish a lower bound on the conserved energy of any
solution that satisfies boundary conditions for which has a global minimum.
A large class of designer gravity theories therefore have a stable ground
state, which the AdS/CFT correspondence indicates should be the lowest energy
soliton. We make progress towards proving this, by showing that minimum energy
solutions are static. The generalization of our results to designer gravity
theories in higher dimensions involving several tachyonic scalars is discussed.Comment: 29 page
Unique continuation and extensions of Killing vectors at boundaries for stationary vacuum space-times
Generalizing Riemannian theorems of Anderson-Herzlich and Biquard, we show
that two -dimensional stationary vacuum space-times (possibly with
cosmological constant ) that coincide up to order one along a
timelike hypersurface \mycal T are isometric in a neighbourhood of \mycal
T. We further prove that KIDS of extend to Killing vectors near
. In the AdS type setting, we show unique continuation near
conformal infinity if the metrics have the same conformal infinity and the same
undetermined term. Extension near of conformal Killing vectors of
conformal infinity which leave the undetermined Fefferman-Graham term invariant
is also established
On essential self-adjointness for magnetic Schroedinger and Pauli operators on the unit disc in R^2
We study the question of magnetic confinement of quantum particles on the
unit disk \ID in \IR^2, i.e. we wish to achieve confinement solely by means
of the growth of the magnetic field near the boundary of the disk.
In the spinless case we show that , for close to 1, insures the confinement provided we
assume that the non-radially symmetric part of the magnetic field is not very
singular near the boundary. Both constants and
are optimal. This answers, in this context, an open
question from Y. Colin de Verdi\`ere and F. Truc. We also derive growth
conditions for radially symmetric magnetic fields which lead to confinement of
spin 1/2 particles.Comment: 18 pages; the main theorem has been expanded and generalize
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