Snake States in Graphene p-n Junctions

We investigate transport in locally-gated graphene devices, where carriers are injected and collected along, rather than across, the gate edge. Tuning densities into the p-n regime significantly reduces resistance along the p-n interface, while resistance across the interface increases. This provides an experimental signature of snake states, which zig-zag along the p-n interface and remain stable as applied perpendicular magnetic field approaches zero. Snake states appear as a peak in transverse resistance measured along the p-n interface. The generic role of snake states disordered graphene is also discussed.Comment: supplemental material available at http://marcuslab.harvard.edu/papers/Williams_SnakesSupp.pd

Quantum Hall conductance of two-terminal graphene devices

Measurement and theory of the two-terminal conductance of monolayer and bilayer graphene in the quantum Hall regime are compared. We examine features of conductance as a function of gate voltage that allow monolayer, bilayer, and gapped samples to be distinguished, including N-shaped distortions of quantum Hall plateaus and conductance peaks and dips at the charge neutrality point. Generally good agreement is found between measurement and theory. Possible origins of discrepancies are discussed

Managing the Tensions at the Intersection of the Triple Bottom Line: A Paradox Theory Approach to Sustainability Management

Corporate sustainability management encompasses multiple dimensions: environmental, social, and economic. Companies are increasingly evaluated within the public sphere, and within their own organizations, according to the degree to which they are perceived to simultaneously promote this nexus of virtues. This article seeks to explore the tensions frequently faced by organizations that strive to manage these dimensions and the role of public policy in that pursuit. A multiple–case study approach is utilized in which the authors selected case organizations according to whether they were attempting to manage the three dimensions of sustainability. The authors utilize paradox theory and a typology provided by previous research to understand the nature of the tensions that emerge in the selected case study organizations. They extend this previous work by examining the role of public policy in providing the situational conditions to make these paradoxical tensions salient, and they examine organizational responses to these conditions. Directions for firms, policy makers, and future researchers are provided on the basis of this study’s findings

Managing the Tensions at the Intersection of the Triple Bottom Line: A Paradox Theory Approach to Sustainability Management

Corporate sustainability management encompasses multiple dimensions: environmental, social, and economic. Companies are increasingly evaluated within the public sphere, and within their own organizations, according to the degree to which they are perceived to simultaneously promote this nexus of virtues. This article seeks to explore the tensions frequently faced by organizations that strive to manage these dimensions and the role of public policy in that pursuit. A multiple–case study approach is utilized in which the authors selected case organizations according to whether they were attempting to manage the three dimensions of sustainability. The authors utilize paradox theory and a typology provided by previous research to understand the nature of the tensions that emerge in the selected case study organizations. They extend this previous work by examining the role of public policy in providing the situational conditions to make these paradoxical tensions salient, and they examine organizational responses to these conditions. Directions for firms, policy makers, and future researchers are provided on the basis of this study’s findings

Multiple prebiotic metals mediate translation.

Today, Mg2+ is an essential cofactor with diverse structural and functional roles in life's oldest macromolecular machine, the translation system. We tested whether ancient Earth conditions (low O2, high Fe2+, and high Mn2+) can revert the ribosome to a functional ancestral state. First, SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) was used to compare the effect of Mg2+, Fe2+, and Mn2+ on the tertiary structure of rRNA. Then, we used in vitro translation reactions to test whether Fe2+ or Mn2+ could mediate protein production, and quantified ribosomal metal content. We found that (i) Mg2+, Fe2+, and Mn2+ had strikingly similar effects on rRNA folding; (ii) Fe2+ and Mn2+ can replace Mg2+ as the dominant divalent cation during translation of mRNA to functional protein; and (iii) Fe and Mn associate extensively with the ribosome. Given that the translation system originated and matured when Fe2+ and Mn2+ were abundant, these findings suggest that Fe2+ and Mn2+ played a role in early ribosomal evolution

Shot Noise in Graphene

We report measurements of current noise in single- and multi-layer graphene devices. In four single-layer devices, including a p-n junction, the Fano factor remains constant to within +/-10% upon varying carrier type and density, and averages between 0.35 and 0.38. The Fano factor in a multi-layer device is found to decrease from a maximal value of 0.33 at the charge-neutrality point to 0.25 at high carrier density. These results are compared to theoretical predictions for shot noise in ballistic and disordered graphene.Comment: related papers available at http://marcuslab.harvard.ed

Resolution requirements for numerical simulations of transition

The resolution requirements for direct numerical simulations of transition to turbulence are investigated. A reliable resolution criterion is determined from the results of several detailed simulations of channel and boundary-layer transition

Status, taste and distinction in consumer culture: acknowledging the symbolic dimensions of inequality

The relationship between social position and health has been the focus of extensive public health debate. In the UK and elsewhere, most researchers have focused on physical aspects of health, using indicators such as mortality and morbidity to draw a picture of profound and widening social inequalities. This paper draws attention to the (neglected) influence of contemporary culture on wellbeing, arguing that the social meanings created within consumer culture possess symbolic force that can add to wider inequalities. The possession of greater material and cultural resources by people of higher social status enables them to label their preferred forms of consumption and lifestyle as desirable and legitimate, thus conveying messages about superior taste and social distinction. Symbolic rather than material forms of inequality are implicated here, with consequences for the psychological wellbeing of disadvantaged people. This paper argues that analyses of inequality need broadening to include such considerations. However, there are implications for efforts to address health inequalities because this analysis suggests that if some forms of social inequality are removed, elements within society would be motivated to invent new forms to replace them. Therefore, this article suggests processes whereby people can develop the self-awareness needed to resist the glossy illusions of the good life represented by modern consumer capitalism

Continuous infusion of an agonist of the tumor necrosis factor receptor 2 in the spinal cord improves recovery after traumatic contusive injury.

AimThe activation of the TNFR2 receptor is beneficial in several pathologies of the central nervous system, and this study examines whether it can ameliorate the recovery process following spinal cord injury.MethodsEHD2-sc-mTNFR2 , an agonist specific for TNFR2, was used to treat neurons exposed to high levels of glutamate in vitro. In vivo, it was infused directly to the spinal cord via osmotic pumps immediately after a contusion to the cord at the T9 level. Locomotion behavior was assessed for 6 weeks, and the tissue was analyzed (lesion size, RNA and protein expression, cell death) after injury. Somatosensory evoked potentials were also measured in response to hindlimb stimulation.ResultsThe activation of TNFR2 protected neurons from glutamate-mediated excitotoxicity through the activation of phosphoinositide-3 kinase gamma in vitro and improved the locomotion of animals following spinal cord injury. The extent of the injury was not affected by infusing EHD2-sc-mTNFR2 , but higher levels of neurofilament H and 2', 3'-cyclic-nucleotide 3'-phosphodiesterase were observed 6 weeks after the injury. Finally, the activation of TNFR2 after injury increased the neural response recorded in the cortex following hindlimb stimulation.ConclusionThe activation of TNFR2 in the spinal cord following contusive injury leads to enhanced locomotion and better cortical responses to hindlimb stimulation