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The costs and benefits of secured creditor control in bankruptcy: evidence from the UK
The AF structure of non commutative toroidal Z/4Z orbifolds
For any irrational theta and rational number p/q such that q|qtheta-p|<1, a
projection e of trace q|qtheta-p| is constructed in the the irrational rotation
algebra A_theta that is invariant under the Fourier transform. (The latter is
the order four automorphism U mapped to V, V mapped to U^{-1}, where U, V are
the canonical unitaries generating A_theta.) Further, the projection e is
approximately central, the cut down algebra eA_theta e contains a Fourier
invariant q x q matrix algebra whose unit is e, and the cut downs eUe, eVe are
approximately inside the matrix algebra. (In particular, there are Fourier
invariant projections of trace k|qtheta-p| for k=1,...,q.) It is also shown
that for all theta the crossed product A_theta rtimes Z_4 satisfies the
Universal Coefficient Theorem. (Z_4 := Z/4Z.) As a consequence, using the
Classification Theorem of G. Elliott and G. Gong for AH-algebras, a theorem of
M. Rieffel, and by recent results of H. Lin, we show that A_theta rtimes Z_4 is
an AF-algebra for all irrational theta in a dense G_delta.Comment: 35 page
Photoluminescence quantum efficiency of dense silicon nanocrystal ensembles in SiO2
The photoluminescence decay characteristics of silicon nanocrystals in dense ensembles fabricated by ion implantation into silicon dioxide are observed to vary in proportion to the calculated local density of optical states. A comparison of the experimental 1/e photoluminescence decay rates to the expected spontaneous emission rate modification yields values for the internal quantum efficiency and the intrinsic radiative decay rate of silicon nanocrystals. A photoluminescence quantum efficiency as high as 59%±9% is found for nanocrystals emitting at 750 nm at low excitation power. A power dependent nonradiative decay mechanism reduces the quantum efficiency at high pump intensity
Universal optical transmission features in periodic and quasiperiodic hole arrays
We investigate the influence of array order in the optical transmission properties of subwavelength hole arrays, by comparing the experimental spectral transmittance of periodic and quasiperiodic hole arrays as a function of frequency. We find that periodicity and long-range order are not necessary requirements for obtaining enhanced and suppressed optical transmission, provided short-range order is maintained. Transmission maxima and minima are shown to result, respectively, from constructive and destructive interference at each hole, between the light incident upon and exiting from a given hole, and surface plasmon polaritons (SPPs) arriving from individual neighboring holes. These SPPs are launched along both illuminated and exit surfaces, by diffraction of the incident and emerging light at the neighboring individual subwavelength holes. By characterizing the optical transmission of a pair of subwavelength holes as a function of hole-hole distance, we demonstrate that a subwavelength hole can launch SPPs with an efficiency up to 35%, and with an experimentally determined launch phase Ï = Ï/2, for both input-side and exit-side SPPs. This characteristic phase has a crucial influence on the shape of the transmission spectra, determining transmission minima in periodic arrays at those frequencies where grating coupling arguments would instead predict maxima
Solidification in soft-core fluids: disordered solids from fast solidification fronts
Using dynamical density functional theory we calculate the speed of
solidification fronts advancing into a quenched two-dimensional model fluid of
soft-core particles. We find that solidification fronts can advance via two
different mechanisms, depending on the depth of the quench. For shallow
quenches, the front propagation is via a nonlinear mechanism. For deep
quenches, front propagation is governed by a linear mechanism and in this
regime we are able to determine the front speed via a marginal stability
analysis. We find that the density modulations generated behind the advancing
front have a characteristic scale that differs from the wavelength of the
density modulation in thermodynamic equilibrium, i.e., the spacing between the
crystal planes in an equilibrium crystal. This leads to the subsequent
development of disorder in the solids that are formed. For the one-component
fluid, the particles are able to rearrange to form a well-ordered crystal, with
few defects. However, solidification fronts in a binary mixture exhibiting
crystalline phases with square and hexagonal ordering generate solids that are
unable to rearrange after the passage of the solidification front and a
significant amount of disorder remains in the system.Comment: 18 pages, 14 fig
Cartesian Bicategories II
The notion of cartesian bicategory, introduced by Carboni and Walters for
locally ordered bicategories, is extended to general bicategories. It is shown
that a cartesian bicategory is a symmetric monoidal bicategory
The costs and benefits of secured creditor control in bankruptcy: evidence from the UK
Recent theoretical literature has debated the desirability of permitting debtors to contract with lenders over control rights in bankruptcy. Proponents point to the monitoring benefits brought from concentrating control rights in the hands of a single lender. Detractors point to the costs imposed on other creditors by a senior claimantâs inadequate incentives to maximise net recoveries. The UK provides the setting for a natural experiment regarding these theories. Until recently, UK bankruptcy law permitted firms to give complete ex post control to secured creditors, through a procedure known as Receivership. Receivership was replaced in 2003 by a new procedure, Administration, which was intended to introduce greater accountability to unsecured creditors to the governance of bankrupt firms, through a combination of voting rights and fiduciary duties. We present empirical findings from a hand-coded sample of 340 bankruptcies from both before and after the change in the law, supplemented with qualitative interview data. We find robust evidence that whilst gross realisations have increased following the change in the law, these have tended to be eaten up by concomitantly increased bankruptcy costs. The net result has been that creditor recoveries have remained unchanged. This implies that dispersed and concentrated creditor governance in bankruptcy may be functionally equivalent
Neutron spin-echo study of the critical dynamics of spin-5/2 antiferromagnets in two and three dimensions
We report a neutron spin-echo study of the critical dynamics in the
antiferromagnets MnF and RbMnF with three-dimensional (3D) and
two-dimensional (2D) spin systems, respectively, in zero external field. Both
compounds are Heisenberg antiferromagnets with a small uniaxial anisotropy
resulting from dipolar spin-spin interactions, which leads to a crossover in
the critical dynamics close to the N\'eel temperature, . By taking
advantage of the energy resolution of the spin-echo
spectrometer, we have determined the dynamical critical exponents for both
longitudinal and transverse fluctuations. In MnF, both the characteristic
temperature for crossover from 3D Heisenberg to 3D Ising behavior and the
exponents in both regimes are consistent with predictions from the
dynamical scaling theory. The amplitude ratio of longitudinal and transverse
fluctuations also agrees with predictions. In RbMnF, the critical
dynamics crosses over from the expected 2D Heisenberg behavior for
to a scaling regime with exponent , which has not been predicted
by theory and may indicate the influence of long-range dipolar interactions
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