Splitting of the Zero-Energy Landau Level and Universal Dissipative Conductivity at Critical Points in Disordered Graphene

We report on robust features of the longitudinal conductivity ($\sigma_{xx}$) of the graphene zero-energy Landau level in presence of disorder and varying magnetic fields. By mixing an Anderson disorder potential with a low density of sublattice impurities, the transition from metallic to insulating states is theoretically explored as a function of Landau-level splitting, using highly efficient real-space methods to compute the Kubo conductivities (both $\sigma_{xx}$ and Hall $\sigma_{xy}$). As long as valley-degeneracy is maintained, the obtained critical conductivity $\sigma_{xx}\simeq 1.4 e^{2}/h$ is robust upon disorder increase (by almost one order of magnitude) and magnetic fields ranging from about 2 to 200 Tesla. When the sublattice symmetry is broken, $\sigma_{xx}$ eventually vanishes at the Dirac point owing to localization effects, whereas the critical conductivities of pseudospin-split states (dictating the width of a $\sigma_{xy}=0$ plateau) change to $\sigma_{xx}\simeq e^{2}/h$, regardless of the splitting strength, superimposed disorder, or magnetic strength. These findings point towards the non dissipative nature of the quantum Hall effect in disordered graphene in presence of Landau level splitting

Use of information technology in South African agriculture

Rapid developments in information technology have exposed South African farmers to the potential benefits of using these technologies in farm decision-making. Use of computers on South African commercial farms is increasing, with three studies showing adoption rates of 48 percent (1993), 64 percent (1996) and 72 percent (1998). About 38 percent of computer users in a 1998 survey of commercial maize farmers had access to the Internet. Spreadsheets and financial management software are popular amongst commercial farmers, while use of Global Positioning Systems (GPS) and Geographic Information Systems (GIS) are being used more widely in South African agriculture. Small-scale farmers in developing areas rely mainly on government and private industry extension services for farm information.Farm Management, Research and Development/Tech Change/Emerging Technologies,

Analytical approximations for the higher energy structure in strong field ionization with inhomogeneous electric fields

Recently, the emergence of a higher energy structure (HES) due to a spatial inhomogeneity in the laser electric field, as is typically found close to a nano tip, was reported in Phys.~Rev. Letter {\bf 119}, 053204 (2017). For practical applications, such as the characterization of near-fields or the creation of localized sources of monoenergetic electron beams with tunable energies, further insight into the nature of this higher energy structure is needed. Here, we give a closed form analytical approximation to describe the movement of the electron in the inhomogeneous electric field. In particular, we derive a simple scaling law for the location of the HES peak and give a scheme to analytically tune the width of the peak, both of which will prove useful in optimizing the nanostructure size or geometry for creating the HES in experimental settings

The Costs of Deception: Evidence From Psychology

Recently, it has been argued that the evidence in social science research suggests that deceiving subjects in an experiment does not lead to a significant loss of experimental control. Based on this assessment, experimental economists were counseled to lift their de facto prohibition against deception to capture its potential benefits. To the extent that this recommendation is derived from empirical studies, we argue that it draws on a selective sample of the available evidence. Building on a systematic review of relevant research in psychology, we present two major results: First, the evidence suggests that the experience of having been deceived generates suspicion which in turn is likely to affect judgment and decision making of a non-negligible number of participants. Second, we find little evidence for reputational spillover effects that have been hypothesized by a number of authors in psychology and economics (e.g., Kelman, 1967; Davis and Holt, 1993). Based on a discussion of the methodological costs and benefits of deception, we conclude that experimental economists' prohibition of deception is a sensible convention that economists should not abandon.experimental economics; deception; reputational spillover effects

Exact formulas for random growth with half-flat initial data

We obtain exact formulas for moments and generating functions of the height function of the asymmetric simple exclusion process at one spatial point, starting from special initial data in which every positive even site is initially occupied. These complement earlier formulas of E. Lee [J. Stat. Phys. 140 (2010) 635-647] but, unlike those formulas, ours are suitable in principle for asymptotics. We also explain how our formulas are related to divergent series formulas for half-flat KPZ of Le Doussal and Calabrese [J. Stat. Mech. 2012 (2012) P06001], which we also recover using the methods of this paper. These generating functions are given as a series without any apparent Fredholm determinant or Pfaffian structure. In the long time limit, formal asymptotics show that the fluctuations are given by the Airy$_{2\to1}$ marginals.Comment: Published at http://dx.doi.org/10.1214/15-AAP1099 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Classic coordination failures revisited: the effects of deviation costs and loss avoidance

Are communication failures common? We revisit a classic example of experimental coordination failure and explore, in a 2x2 design, the effects of deviation costs and loss avoidance. Our results provide additional insights into the parametric determinants of laboratory coordination failures, and successes.coordination games, Pareto-ranked equilibria, payoff-asymmetric equilibria, optimization incentives, robustness, coordination failure