Other People\u27s Money: The Effects of Ownership on Compensation Strategy and Executive Pay

In this paper we develop and test hypotheses based on agency theory and managerial capitalism to address the question of whether firms\u27 compensation strategies are designed to motivate actions in the interests of equity holders or those of management. We examined differences in the organizational incentive structure of lower-level executives in management-controlled, owner controlled, and owner-managed firms. We found that when managers controlled the firm, there was pervasively weak incentive alignment for managers within the hierarchy and that, beyond base pay, they were able to extract compensation premiums through bonuses and long-term incentives, in spite of the fact that their firms did not demonstrate better economic performance than other types of firms. We were also able to demonstrate that equity holders pay substantial agency costs in management-controlled firms compared with owner-controlled firms. We end with a discussion of the organizational context for rationalizing executive compensation and the role of compensation consultants

Time-Dependent Density-Functional Theory for Superfluids

A density-functional theory is established for inhomogeneous superfluids at finite temperature, subject to time-dependent external fields in isothermal conditions. After outlining parallelisms between a neutral superfluid and a charged superconductor, Hohenberg-Kohn-Sham-type theorems are proved for gauge-invariant densities and a set of Bogolubov-Popov equations including exchange and correlation is set up. Earlier results applying in the linear response regime are recovered.Comment: 12 pages. Europhysics Letters, in pres

Nonequilibrium transport through magnetic vibrating molecules

We calculate the nonequilibrium conductance through a molecule or a quantum dot in which the occupation of the relevant electronic level is coupled with intensity $\lambda$ to a phonon mode, and also to two conducting leads. The system is described by the Anderson-Holstein Hamiltonian. We solve the problem using the Keldysh formalism and the non-crossing approximation (NCA) for both, the electron-electron and the electron-phonon interactions. We obtain a moderate decrease of the Kondo temperature $T_K$ with $\lambda$ for fixed renormalized energy of the localized level $\tilde{E_d}$. The meaning and value of $\tilde{E_d}$ are discussed. The spectral density of localized electrons shows in addition to the Kondo peak of width $2 T_K$, satellites of this peak shifted by multiples of the phonon frequency $\omega_0$. The nonequilibrium conductance as a function of bias voltage $V_b$ at small temperatures, also displays peaks at multiples of $\omega_0$ in addition to the central dominant Kondo peak near $V_b=0$.Comment: 11 pages, 13 figures, accepted in Phys. Rev.

Collective excitations of a periodic Bose condensate in the Wannier representation

We study the dispersion relation of the excitations of a dilute Bose-Einstein condensate confined in a periodic optical potential and its Bloch oscillations in an accelerated frame. The problem is reduced to one-dimensionality through a renormalization of the s-wave scattering length and the solution of the Bogolubov - de Gennes equations is formulated in terms of the appropriate Wannier functions. Some exact properties of a periodic one-dimensional condensate are easily demonstrated: (i) the lowest band at positive energy refers to phase modulations of the condensate and has a linear dispersion relation near the Brillouin zone centre; (ii) the higher bands arise from the superposition of localized excitations with definite phase relationships; and (iii) the wavenumber-dependent current under a constant force in the semiclassical transport regime vanishes at the zone boundaries. Early results by J. C. Slater [Phys. Rev. 87, 807 (1952)] on a soluble problem in electron energy bands are used to specify the conditions under which the Wannier functions may be approximated by on-site tight-binding orbitals of harmonic- oscillator form. In this approximation the connections between the low-lying excitations in a lattice and those in a harmonic well are easily visualized. Analytic results are obtained in the tight-binding scheme and are illustrated with simple numerical calculations for the dispersion relation and semiclassical transport in the lowest energy band, at values of the system parameters which are relevant to experiment.Comment: 20 pages, 2 figures, 22 reference

Replicas of the Kondo peak due to electron-vibration interaction in molecular transport properties

The low temperature properties of single level molecular quantum dots including both, electron-electron and electron-vibration interactions, are theoretically investigated. The calculated differential conductance in the Kondo regime exhibits not only the zero bias anomaly but also side peaks located at bias voltages which coincide with multiples of the energy of vibronic mode $V \sim \hbar\Omega/e$. We obtain that the evolution with temperature of the two main satellite conductance peaks follows the corresponding one of the Kondo peak when $\hbar\Omega \gg k_B T_K$, being $T_K$ the Kondo temperature, in agreement with recent transport measurements in molecular junctions. However, we find that this is no longer valid when $\hbar\Omega$ is of the order of a few times $k_B T_K$.Comment: 6 pages, 4 figures. Accepted for publication in Physical Review

Orbital Kondo spectroscopy in a double quantum dot system

We calculate the nonequilibrium conductance of a system of two capacitively coupled quantum dots, each one connected to its own pair of conducting leads. The system has been used recently to perform pseudospin spectroscopy by controlling independently the voltages of the four leads. The pseudospin is defined by the orbital occupation of one or the other dot. Starting from the SU(4) symmetric point of spin and pseudospin degeneracy in the Kondo regime, for an odd number of electrons in the system, we show how the conductance through each dot varies as the symmetry is reduced to SU(2) by a pseudo-Zeeman splitting, and as bias voltages are applied to any of the dots. We analize the expected behavior of the system in general, and predict characteristic fingerprint features of the SU(4) to SU(2) crossover that have not been observed so far.Comment: 5 pages, 6 figures, submitted to Phys. Rev.

Restoring the SU(4) Kondo regime in a double quantum dot system

We calculate the spectral density and occupations of a system of two capacitively coupled quantum dots, each one connected to its own pair of conducting leads, in a regime of parameters in which the total coupling to the leads for each dot $\Gamma_i$ are different. The system has been used recently to perform pseudospin spectroscopy by controlling independently the voltages of the four leads. For an odd number of electrons in the system, $\Gamma_1=\Gamma_2$, equal dot levels $E_1=E_2$ and sufficiently large interdot repulsion $U_{12}$ the system lies in the SU(4) symmetric point of spin and pseudospin degeneracy in the Kondo regime. In the more realistic case $\Gamma_1 \neq \Gamma_2$, pseudospin degeneracy is broken and the symmetry is reduced to SU(2). Nevertheless we find that the essential features of the SU(4) symmetric case are recovered by appropriately tuning the level difference $\delta=E_2-E_1$. The system behaves as an SU(4) Kondo one at low energies. Our results are relevant for experiments which look for signatures of SU(4) symmetry in the Kondo regime of similar systems.Comment: 9 pages, 10 figure

I sedimenti tardo-quaternari dell'area litorale veneziana: analisi delle caratteristiche fisico-meccaniche

Abstract: This paper describes the geotechnical properties of the Venetian littoral. Analyses of 110 cohesive soil samples and 338 granular, taken from 30 cores, 25-30 meters in depth, were considered. The classical geotechnical classification supported by statistical analysis has pointed out that the compression index presents the best correlations with void ratio index and natural water content. Moreover, this paper shows the importance of the Atterberg limits to distinguish the cohesive soils of the late Pleistocene from those of the Holocene. Granular sediments have shown a zonation of both the grain size distribution and permeability coefficient. Resumé: Pour l'analyse des caractéristiques géotecniques du littoral venitien, qui est le sujet de ce travail, on a étudié 110 échantillons de terrains cohérents et 338 de terrains granulaires. Ces échantillons ont été prélevés de 30 carottages efféctués à la profondité moyenne de 25-30 m., et ils représentent les dernières 25.000-30.000 années de sèdiments quaternaires. En considérant la masse des donneés disponibles pour l'elaboration traditionnelle des propriétés géotechniques, une élaboration statistique a été utilisée pour obtenir des meilleures rélations de synthèse. En particulier, on a vu l'importance des limites de Attemberg pour effectuer la distinction entre les terrains cohérents du Pleistocene tardif et ceux de l'Olocene. En plus, la correlation du plus haut niveau de l'indice de compression est celle avec le pourcentage naturel d'eau et l'indice des vides. En ce qui concerne les terrains granulaires, on a verifié qu'il existe des zonations de la distribution granulometrique et du coeficient de perméabilité. Riassunto: Per l'analisi delle caratteristiche geotecniche del litorale veneziano, argomento di questo lavoro, sono stati studiati 110 campioni di terreni coesivi e 338 di terreni granulari prelevati da 30 sondaggi terebrati lungo il cordone litoraneo a profondità medie di 25-30 metri che rappresentano gli ultimi 25.000-30.000 anni di sedimentazione quaternaria. In considerazione della massa di dati disponibili all'elaborazione tradizionale delle proprietà geotecniche si è affiancata un'elaborazione statistica (analisi discriminante) che ha permesso di fornire relazioni di sintesi maggiormente interpretative. In particolare è emerso il potere selettivo dei limiti di Atterberg per distinguere i terreni coesivi tardo-pleistocenici da quelli olocenici. Inoltre si è visto che l'indice di compressione presenta le correlazioni più elevate con il contenuto naturale d'acqua e l'indice dei vuoti. Per quanto concerne i terreni granulari si sono riscontrate zonazioni della distribuzione granulometrica e del coefficiente di permeabilità