Magneto-optical conductivity in graphene including electron-phonon coupling

We show how coupling to an Einstein phonon $\omega_E$ affects the absorption peaks seen in the optical conductivity of graphene under a magnetic field $B$. The energies and widths of the various lines are shifted, and additional peaks arise in the spectrum. Some of these peaks are Holstein sidebands, resulting from the transfer of spectral weight in each Landau level (LL) into phonon-assisted peaks in the spectral function. Other additional absorption peaks result from transitions involving split LLs, which occur when a LL falls sufficiently close to a peak in the self-energy. We establish the selection rules for the additional transitions and characterize the additional absorption peaks. For finite chemical potential, spectral weight is asymmetrically distributed about the Dirac point; we discuss how this causes an asymmetry in the transitions due to left- and right-handed circularly polarized light and therefore oscillatory behavior in the imaginary part of the off-diagonal Hall conductivity. We also find that the semiclassical cyclotron resonance region is renormalized by an effective-mass factor but is not directly affected by the additional transitions. Last, we discuss how the additional transitions can manifest in broadened, rather than split, absorption peaks due to large scattering rates seen in experiment.Comment: 24 pages, 21 figure

AC impedance study of degradation of porous nickel battery electrodes

AC impedance spectra of porous nickel battery electrodes were recorded periodically during charge/discharge cycling in concentrated KOH solution at various temperatures. A transmission line model (TLM) was adopted to represent the impedance of the porous electrodes, and various model parameters were adjusted in a curve fitting routine to reproduce the experimental impedances. Degradation processes were deduced from changes in model parameters with electrode cycling time. In developing the TLM, impedance spectra of planar (nonporous) electrodes were used to represent the pore wall and backing plate interfacial impedances. These data were measured over a range of potentials and temperatures, and an equivalent circuit model was adopted to represent the planar electrode data. Cyclic voltammetry was used to study the characteristics of the oxygen evolution reaction on planar nickel electrodes during charging, since oxygen evolution can affect battery electrode charging efficiency and ultimately electrode cycle life if the overpotential for oxygen evolution is sufficiently low

Survey Evidence on Diffusion of Interest Among Institutional Investors

Contagion or epidemic models of financial markets are proposed in which interest in or attention to individual stocks is spread by word of mouth. The models give alternative interpretations of the random walk character of stock prices. A questionnaire survey of institutional investors was undertaken to ascertain the relevance of such models. Questions elicited what fraction of these investors were unsystematic and allowed themselves to be influenced by word-of-mouth communications or other salient stimuli. Rough indications of the infection rate and removal rate were produced. Investors in stocks whose price had recently increased dramatically to a high P/E ratio were contrasted with a control group of investors

Listening to young people’s views of the coast:Living Coast Youth Voice

We have summarised the knowledge that was co-created with young people here. However, we would like to encourage those adults who planned to read just this summary to also hear directly form the young people by reading Chapter 3. Introduction Living Coast was a national partnership pilot project developed by Natural England1 (an organisation that looks after nature and landscapes in England). Natural England wants to help people from all walks-of-life enjoy the benefits of a new long distance path around England: the England Coast Path. By 2020, the path will stretch for approximately 2,700 miles around our beautiful English coastline and open up new stretches of the coastline. Natural England wants to understand how and why young people already use and enjoy the coast, and why others do not (or cannot). They want to know what can be done to help as many young people as possible benefit from the spectacular views, sea air, exercise and nature that the path and surrounding areas offer. In this research, we worked with young people aged 11 – 18 to create new knowledge about what makes it easy or hard for them to make the most of the coast, and what they suggest would help. This is important because there is little other evidence about this, nationally. This research took place in Barrow-in-Furness in Cumbria – a place with a high quality natural environment and areas that fall in the bottom 10% and 3% nationally on measures of deprivation. Cumbria was one of three Living Coast pilot areas in 2018/19. The other two are on the Durham Heritage Coast and the Solent. All three will inform how Natural England and its partners develop work at the coast.2 Research focus The study asked the following research questions: Q What do you think of the coast? Q How do you use the coast? Q How do you benefit from the coast? Q What makes it easy to go to, and enjoy, the coast? Q What makes it hard to go to, and enjoy, the coast? Q What would help you to go more often? Q What suggestions would you make to Natural England about how they can help? Methods used Our methods mixed and blended methods, techniques and principles from participation practice and social science. To do this we: 2 1. In total, we met 59 young people from a mix of ages, genders, ethnicities, and distances from the coast, prioritising those who live in areas that fall in the lowest 3% or 10% in the Indices of Multiple Deprivation. 2. Set up a Participatory Advisory Group (PAG) of eight young people, aged 14, to be our research advisors, comment on our methods and help us interpret and analyse our findings. 3. Met with 47 young people in six groups, from a range of community and educational settings, for 90-minutes each. During these sessions, we worked with young people to create maps, discuss their good and bad experiences, ease of getting to the coast, and the influence of money, jobs, belonging and culture to their views of the coast. 4. Summarised what young people said in this first round in pictures. 5. Ran two ‘Creative Horizons’ events a fortnight later, in two sessions when 22 young people (of those who had taken part in the mapping sessions) were joined by 4 new young people. In these sessions young people took charge of which topics to explore and how to create new knowledge through art, story, rap, music, poems, drama, or discussion. 6. Faithfully reported what young people said in this report and in a film. Findings We found that young people have a mix of attitudes towards the coast, with some finding it a place of enjoyment, peace, and adventure and others finding it boring, uncomfortable and a place of natural and human dangers. Young people go to a mix of places. Some are familiar beaches, which are closer to home and easier to get to, and others are destinations young people enjoy with friends and family but require transport to get to. Walking and dog walking were most often mentioned as activities to do at the coast, with some saying they swam in the sea but many others not mentioning swimming at all or saying they couldn’t swim. For a few, cycling was a key part of enjoying the coast and a couple of young people mentioned anglin g and water sports. Young people in all groups described psychological, physical and social wellbeing benefits of being by the sea. They said that it helped them cope with stress, be fitter and enjoy time with family and friends. The things that made it easier to go included: their own attitudes and confidence, being able to get there, having someone available to go with, feeling safe and belonging and also the time of year and the weather. The barriers to going to the seaside were numerous and interconnected and particularly hard for young people living with multiple pressures and disadvantages. Negative personal attitudes and fears included boredom and anxiety, such as about risks or body shaming. A range of issues around social barriers included not feeling safe from attack, feeling they didn’t belong, that adults and peers were judging them badly as well as outright racism, sexism and homophobia. Young people also said they lacked information about where to go, how to get there, what to do once there, natural risks such as tides, quick sands and rock falls. Getting there and affording to go were practical barriers, as was having someone available to go with them. Litter and dirty beaches deter young people. At this exposed location, bad weather with fierce winds and driving rain can make it too unpleasant to go. Young peoples’ messages to the Natural England and its partners about enjoying the coast: Help make it safe (from attack and by changing adult attitudes toward us) 3 Help us get there Give us information Provide affordable events and activities Run nature trips Provide shelter

How the Proxy Rules Discourage Constructive Engagement: Regulatory Barriers to Electing a Minority of Directors

During the 1980s, both sides of the hostile takeover controversy viewed proxy contests in terms that bordered on the mythical. Those made uneasy by the takeover phenomenon, especially management, held out proxy contests as an alternative, almost utopian mechanism through which a civilized debate about corporate strategy and structure could be held. As the Delaware Supreme Court put it, [if the stockholders are displeased with the actions of their elected representatives [in blocking a hostile takeover], the powers of corporate democracy are at their disposal to turn the board out.” In contrast, those who believed that takeovers were necessary to displace inefficient management or otherwise change corporate policy dismissed the proxy contest as entirely ineffective. They argued that the costs of collective action arising from dispersed share ownership reduced to allegory the prospect that the proxy process could provide a viable means to correct management failure. With the benefit of a little hindsight, both views have turned out to be wrong. Takeover proponents\u27 dismissal of the proxy process ignored the dramatic growth in the holdings of institutional investors, and the resulting reduction in the costs associated with collective voting action. Moreover, takeover proponents\u27 dismissal of the proxy process seemed to stem from a preference (in the case of financial economists, often a purely intellectual preference) for market-based, price-driven mechanisms over ones that created a meaningful, substantive debate over corporate policy. Indeed, financial scholars often appeared to view the institutional complexity and substantive, process-driven dynamics associated with proxy contests with unease. The inefficiency of proxy contests was often assumed rather than treated as a hypothesis subject to empirical test

Second-order gravitational self-force

Using a rigorous method of matched asymptotic expansions, I derive the equation of motion of a small, compact body in an external vacuum spacetime through second order in the body's mass (neglecting effects of internal structure). The motion is found to be geodesic in a certain locally defined regular geometry satisfying Einstein's equation at second order. I outline a method of numerically obtaining both the metric of that regular geometry and the complete second-order metric perturbation produced by the body.Comment: 5 pages, added clarifications in response to referee comments, accepted for publication in PR

Principles and practical implementation of farming systems research and farmer participatory research. Including Vulindlela District and Sobantu Village case studies

This publication integrates theory and practical work arising from courses in Farming Systems and Farmer Participatory Research held at the Institute of Natural Resources and associated institutions in KwaZulu-Natal during 1996 and 1997. The courses were conducted as part of a project supported by the UK. Government's Department for International Development and managed by the UK Natural Resources Institute (NRI). Objectives of this publication are 1) to provide reference material in Farming Systems and Farmer Participatory Research for interested audiences in KwaZulu-Natal and elsewhere; 2) by integrating theory and practice, to demonstrate how the principles, approaches and methods of FSRJFPR can be applied to real situations; 3) to record the situation, suggestions and priorities of rural and peri-urban families in Vulindlela District, as recorded by course participants; 4) to provide a springboard of information for further development initiatives in Vulindlela and elsewhere in KwaZulu-Natal; 5) to present the Urban Agriculture workshop held in Sobantu Village as a case study of participatory workshop methods