Non-equilibrium breakdown of quantum Hall state in graphene

In this report we experimentally probe the non-equilibrium breakdown of the quantum Hall state in monolayer graphene by injecting a high current density ($\sim$1A/m). The measured critical currents for dissipationless transport in the vicinity of integer filling factors show a dependence on filling factor. The breakdown can be understood in terms of inter Landau level (LL) scattering resulting from mixing of wavefunctions of different LLs. To further study the effect of transverse electric field, we measured the transverse resistance between the $\nu=2$ to $\nu=6$ plateau transition for different bias currents and observed an invariant point.Comment: to appear in PRB Rapi

CEO overconfidence and dividend policy

We develop a model of the effect of CEO overconfidence on dividend policy and empirically examine many of its predictions. Consistent with our main prediction, we find that the level of dividend payout is lower in firms managed by overconfident CEOs. We document that this reduction in dividends associated with CEO overconfidence is greater in firms with lower growth opportunities, lower cash flow, and greater information asymmetry. We also show that the magnitude of the positive market reaction to a dividend-increase announcement is lower for firms managed by overconfident CEOs. Our overall results are consistent with the predictions of our model.Chief executive officers ; Dividends

Nanoscale electromechanical resonators as probes of the charge density wave transition in NbSe2_2

We study nanoelectromechanical resonators fabricated from suspended flakes of NbSe$_2$ (thickness$\sim$30-50 nm) to probe charge density wave (CDW) physics at nanoscale. Variation of elastic and electronic properties accompanying the CDW phase transition (around 30 K) are investigated simultaneously using the devices as self-sensing heterodyne mixers. Elastic modulus is observed to change by 10 per cent, an amount significantly larger than what had been reported earlier in the case of bulk crystals. We also study the modulation of conductance by electric field effect, and examine its relation to the order parameter and the CDW energy gap at the Fermi surface

Heat transfer in a membrane assisted fluidised bed with immersed horizontal tubes

The effect of gas permeation through horizontally immersed membrane tubes on the heat transfer characteristics in a membrane assisted fluidised bed was investigated experimentally. Local time-averaged heat transfer coefficients from copper tubes arranged in a staggered formation with the membrane tubes to the fluidised bed were measured in a square bed (0.15 m x 0.15 m x 0.95 m) containing glass particles (75-110 ¿m) fluidised with air distributed via a porous plate, where the ratio of gas fed or removed through the membrane bundles and the porous plate distributor was varied. The experimental results revealed that high gas permeation rates through the membranes strongly decreased the heat transfer coefficient at high superficial gas velocities for tubes at the top of the tube bundle, which was attributed to the reduced mobility and heat capacity (higher dilution) of the emulsion phase. However, the effect of gas permeation was much less pronounced for tubes lower in the tube bundle because of the lower local dilution of the emulsion phase

Fabrication of Asymmetric Electrode Pairs with Nanometer Separation Made of Two Distinct Metals

We report a simple and reproducible method to fabricate two metallic electrodes made of different metals with a nanometer-sized gap. These electrodes are fabricated by defining a pair of gold electrodes lithographically and electrodepositing a second metal onto one of them. The method enables the fabrication of pairs of metallic electrodes that exhibit distinct magnetic properties or work functions. The utility of this technique is demonstrated by making single-electron tunneling devices incorporating 2-nm gold nanocrystals.Comment: 3 figures, 1 colo