Quantum Hall ferromagnetic phases in the Landau level N=0 of a graphene bilayer

In a Bernal-stacked graphene bilayer, an electronic state in Landau level $N=0$ is described by its guiding-center index $X$ (in the Landau gauge) and by its valley, spin, and orbital indices $\xi =\pm K,\sigma =\pm 1,$ and $n=0,1.$ When Coulomb interaction is taken into account, the chiral two-dimensional electron gas (C2DEG) in this system can support a variety of quantum Hall ferromagnetic (QHF)\ ground states where the spins and/or valley pseudospins and/or orbital pseudospins collectively align in space. In this work, we give a comprehensive account of the phase diagram of the C2DEG at integer filling factors $\nu \in [-3,3]$ in Landau level N=0 when an electrical potential difference $\Delta_{B}$ between the two layers is varied. We consider states with or without layer, spin, or orbital coherence. For each phase, we discuss the behavior of the transport gap as a function of $\Delta_{B},$ the spectrum of collective excitations and the optical absorption due to orbital pseudospin-wave modes. We also study the effect of an external in-plane electric field on a coherent state that has both valley and spin coherence and show that it is possible, in such a state, to control the spin polarization by varying the strength of the external in-plane electric field.Comment: 21 pages, 13 eps figure

Crossed conductance in FSF double junctions: role of out-of-equilibrium populations

We discuss a model of Ferromagnet / Superconductor / Ferromagnet (FSF) double junction in which the quasiparticles are not in equilibrium with the condensate in a region of the superconductor containing the two FS contacts. The role of geometry is discussed, as well as the role of a small residual density of states within the superconducting gap, that allows a sequential tunneling crossed current. With elastic quasiparticle transport and the geometry with lateral contacts, the crossed conductances in the sequential tunneling channel are almost equal in the normal and superconducting phases, if the distance between the FS interfaces is sufficiently small. The sequential tunneling and spatially separated processes (the so-called crossed Andreev reflection and elastic cotunneling processes) lead to different signs of the crossed current in the antiparallel alignment for tunnel interfaces.Comment: 8 pages, 4 figure

Price-setting behavior in the presence of social interactions

We argue in this paper that a more active market for corporate control may weaken the takeover threat. We show that an increase in the number of potential raiders tends to decrease the probability of a takeover. This in turn weakens managerial incentives. The lower managerial effort level that results in equilibrium negatively affects the ex ante value of the firm.

Entanglement in quantum catastrophes

We classify entanglement singularities for various two-mode bosonic systems in terms of catastrophe theory. Employing an abstract phase-space representation, we obtain exact results in limiting cases for the entropy in cusp, butterfly, and two-dimensional catastrophes. We furthermore use numerical results to extract the scaling of the entropy with the non-linearity parameter, and discuss the role of mixing entropies in more complex systems.Comment: 7 pages, 3 figure

Connected innovation: an international comparative study that identifies mixed modes of innovation

This paper offers a new angle on innovation modalities by adopting a recently emerging approach towards identifying innovation typologies via exploratory data analysis techniques with the aim to tease out some underlying latent variables that represent coherent innovation strategies for groups of firms. Mixed modes of innovation include aspects of both user and open innovation, and are employed to inform on such concepts. The modes of innovation are developed by exploring micro-level innovation survey data across 18 countries. The contributions of the paper lie in (a) the identification of five core innovation modes that are found in almost all countries; and (b) examining – via regression analysis – the role of different modes in firm performance

Price-setting behavior in the presence of social interactions

We argue in this paper that a more active market for corporate control may weaken the takeover threat. We show that an increase in the number of potential raiders tends to decrease the probability of a takeover. This in turn weakens managerial incentives. The lower managerial effort level that results in equilibrium negatively affects the ex ante value of the firm.

The effects of restraint on uptake of radioactive sulfate in the salivary and gastric secretions of rats with pyloric ligation

The effects of restraint on the amount of nondialysable radioactive sulfate in the gastric wall and the gastric juice and saliva were investigated. It was found that restraint provokes a significant decrease in salivary radioactive sulfate. This, in turn, is responsible for the decrease of sulfate in the gastric contents observed under these conditions in rats with pyloric ligation. Esophageal ligation associated with this prevents passage of saliva and lowers the amount of radioactive sulfate in the gastric juice. Restraint causes then an increase in the amount of sulfate in the gastric juice, the value observed being very much lower than that of rats with a free esophagus. At the level of the gastric wall, the change observed during restraint does not reach a significant threshold