A Scenario to the Anomalous Hall Effect in the Mixed State of Superconductors

We argue that the motion of vacancies in a pinned vortex lattice may dominate the contribution to the Hall effect in an appropriate parameter regime for a superconductor. Based on this consideration a model is constructed to explain the anomalous Hall effect without any modification of the basic vortex dynamic equation. Quantitative predictions are obtained. Present model can be directly tested by an observation of the vacancy motion.Comment: latex, 6 pages (Presented at the Miami High Tc Conf., Jan 5-11, 1995. To appear at J. Supercond.

Optimal Decentralized Investment Management

We study a decentralized investment problem in which a CIO employs multiple asset managers to implement and execute investment strategies in separate asset classes. The CIO allocates capital to the managers who, in turn, allocate these funds to the assets in their asset class. This two-step investment process causes several misalignments of objectives between the CIO and his managers and can lead to large utility costs on the part of the CIO. We focus on i) loss of diversification ii) different appetites for risk, iii) different investment horizons, and iv) the presence of liabilities. We derive an optimal unconditional linear performance benchmark and show that this benchmark can be used to better align incentives within the firm. The optimal benchmark substantially mitigates the utility costs of decentralized investment management. These costs can be further reduced when the CIO can screen asset managers on the basis of their risk appetites. Each manager%u2019s optimal level of risk aversion depends on the asset class he manages and can differ substantially from the CIO%u2019s level of risk aversion.

Comparison of Synovex-S® and steer-oid® in finishing yearling steers

Synovex-S (SS) and STEER-oid (SO) were compared in a 122-d finishing study. No differences were observed over the entire study for animal performance or carcass traits. However, in the final period (d 91-122), steers implanted with SO gained 8.4% faster (P=.17) and 8.7% more efficiently (P=.10) than steers implanted with SS, suggesting that estradiol payout in this period was less diminished for SO implants. The importance of this finding is unknown, because it is generally recommended that steers fed for longer periods of time be reimplanted midway through the finishing period to maintain maximal implant response

History effects and pinning regimes in solid vortex matter

We propose a phenomenological model that accounts for the history effects observed in ac susceptibility measurements in YBa2Cu3O7 single crystals [Phys. Rev. Lett. 84, 4200 (2000) and Phys. Rev. Lett. 86, 504 (2001)]. Central to the model is the assumption that the penetrating ac magnetic field modifies the vortex lattice mobility, trapping different robust dynamical states in different regions of the sample. We discuss in detail on the response of the superconductor to an ac magnetic field when the vortex lattice mobility is not uniform inside the sample. We begin with an analytical description for a simple geometry (slab) and then we perform numerical calculations for a strip in a transverse magnetic field which include relaxation effects. In calculations, the vortex system is assumed to coexist in different pinning regimes. The vortex behavior in the regions where the induced current density j has been always below a given threshold (j_c^>) is described by an elastic Campbell-like regime (or a critical state regime with local high critical current density, j_c^>). When the VS is shaken by symmetrical (e.g. sinusoidal) ac fields, the critical current density is modified to j_c^) at regions where vortices have been forced to oscillate by a current density larger than j_c^>. Experimentally, an initial state with high critical current density (j_c^>) can be obtained by zero field cooling, field cooling (with no applied ac field) or by shaking the vortex lattice with an asymmetrical (e.g. sawtooth) field. We compare our calculations with experimental ac susceptibility results in YBa2Cu3O7 single crystals.Comment: 11 pages, 7 figures. To be published in PR

On the Timing and Pricing of Dividends

We recover prices of dividend strips on the aggregate stock market using data from derivatives markets. The price of a k-year dividend strip is the present value of the dividend paid in k years. The value of the stock market is the sum of all dividend strip prices across maturities. We study the properties of strips and find that expected returns, Sharpe ratios, and volatilities on short-term strips are higher than on the aggregate stock market, while their CAPM betas are well below one. Short-term strip prices are more volatile than their realizations, leading to excess volatility and return predictability.

No evidence for retinal damage evolving from reduced retinal blood flow in carotid artery disease

Introduction. Carotid artery disease (CAD) comprising high-grade internal carotid artery stenosis (CAS) or carotid artery occlusion (CAO) may lead to ipsilateral impaired cerebral blood flow and reduced retinal blood supply. Objective. To examine the influence of chronic CAD on retinal blood flow, retinal morphology, and visual function. Methods. Patients with unilateral CAS ≥ 50% (ECST criteria) or CAO were grouped according to the grade of the stenosis and to the flow direction of the ophthalmic artery (OA). Retinal perfusion was measured by transorbital duplex ultrasound, assessing central retinal artery (CRA) blood flow velocities. In addition, optic nerve and optic nerve sheath diameter were measured. Optical coherence tomography (OCT) was performed to study retinal morphology. Visual function was assessed using high- and low-contrast visual paradigms. Results. Twenty-seven patients were enrolled. Eyes with CAS ≥ 80%/CAO and retrograde OA blood flow showed a significant reduction in CRA peak systolic velocity (no-CAD side: 0.130 ± 0.035 m/s, CAS/CAO side: 0.098 ± 0.028; p = 0.005; n = 12). OCT, optic nerve thicknesses, and visual functional parameters did not show a significant difference. Conclusion. Despite assessable hemodynamic effects, chronic high-grade CAD does not lead to gaugeable morphological or functional changes of the retina

A variational approach to the macroscopic electrodynamics of anisotropic hard superconductors

We consider the Bean's critical state model for anisotropic superconductors. A variational problem solved by the quasi--static evolution of the internal magnetic field is obtained as the $\Gamma$-limit of functionals arising from the Maxwell's equations combined with a power law for the dissipation. Moreover, the quasi--static approximation of the internal electric field is recovered, using a first order necessary condition. If the sample is a long cylinder subjected to an axial uniform external field, the macroscopic electrodynamics is explicitly determined.Comment: 24 pages, 15 figure

A Superspace Formulation for the Master Equation

It is shown that the quantum master equation of the Field Antifield quantization method at one loop order can be translated into the requirement of a superfield structure for the action. The Pauli Villars regularization is implemented in this BRST superspace and the case of anomalous gauge theories is investigated. The quantum action, including Wess Zumino terms, shows up as one of the components of a superfield that includes the BRST anomalies in the other component. The example of W2 quantum gravity is also discussed.Comment: The constrained nature of standard BRST superfields and the importance of using Alfaro and Damgaard's collective fields in the superspace approach to avoid undefined superfield derivatives was emphasized. To appear in Phys. Rev. D. Latex file, 20 page

Proposal of an experimental scheme for realising a translucent eavesdropping on a quantum cryptographic channel

Purpose of this paper is to suggest a scheme, which can be realised with today's technology and could be used for entangling a probe to a photon qubit based on polarisation. Using this probe a translucent or a coherent eavesdropping can be performed.Comment: in pres

Direct Extraction of QCD Lambda MS-bar from e+e- Jet Observables

We directly fit the QCD dimensional transmutation parameter, Lambda MS-bar, to experimental data on e+e- jet observables, making use of next-to-leading order (NLO) perturbative calculations. In this procedure there is no need to mention, let alone to arbitrarily vary, the unphysical renormalisation scale mu, and one avoids the spurious and meaningless ``theoretical error'' associated with standard alpha_s determinations. PETRA, SLD, and LEP data are considered in the analysis. An attempt is made to estimate the importance of uncalculated next-NLO and higher order perturbative corrections, and power corrections, by studying the scatter in the values of Lambda MS-bar obtained for different observables.Comment: 46 pages, 22 figure