Scaling behavior of spin transport in hydrogenated graphene

We calculate the spin transport of hydrogenated graphene using the Landauer-B\"uttiker formalism with a spin-dependent tight-binding Hamiltonian. The advantages of using this method is that it simultaneously gives information on sheet resistance and localization length as well as spin relaxation length. Furthermore, the Landauer-B\"uttiker formula can be computed very efficiently using the recursive Green's function technique. Previous theoretical results on spin relaxation time in hydrogenated graphene have not been in agreement with experiments. Here, we study magnetic defects in graphene with randomly aligned magnetic moments, where interference between spin-channels is explicitly included. We show that the spin relaxation length and sheet resistance scale nearly linearly with the impurity concentration. Moreover, the spin relaxation mechanism in hydrogenated graphene is Markovian only near the charge neutrality point or in the highly dilute impurity limit

Radiation effects in MOS integrated circuits

High energy electron irradiation effects on field effect transistors in integrated circuit device

Dirac model of electronic transport in graphene antidot barriers

In order to use graphene for semiconductor applications, such as transistors with high on/off ratios, a band gap must be introduced into this otherwise semimetallic material. A promising method of achieving a band gap is by introducing nanoscale perforations (antidots) in a periodic pattern, known as a graphene antidot lattice (GAL). A graphene antidot barrier (GAB) can be made by introducing a 1D GAL strip in an otherwise pristine sheet of graphene. In this paper, we will use the Dirac equation (DE) with a spatially varying mass term to calculate the electronic transport through such structures. Our approach is much more general than previous attempts to use the Dirac equation to calculate scattering of Dirac electrons on antidots. The advantage of using the DE is that the computational time is scale invariant and our method may therefore be used to calculate properties of arbitrarily large structures. We show that the results of our Dirac model are in quantitative agreement with tight-binding for hexagonal antidots with armchair edges. Furthermore, for a wide range of structures, we verify that a relatively narrow GAB, with only a few antidots in the unit cell, is sufficient to give rise to a transport gap

Electronic and optical properties of graphene antidot lattices: Comparison of Dirac and tight-binding models

The electronic properties of graphene may be changed from semimetallic to semiconducting by introducing perforations (antidots) in a periodic pattern. The properties of such graphene antidot lattices (GALs) have previously been studied using atomistic models, which are very time consuming for large structures. We present a continuum model that uses the Dirac equation (DE) to describe the electronic and optical properties of GALs. The advantages of the Dirac model are that the calculation time does not depend on the size of the structures and that the results are scalable. In addition, an approximation of the band gap using the DE is presented. The Dirac model is compared with nearest-neighbour tight-binding (TB) in order to assess its accuracy. Extended zigzag regions give rise to localized edge states, whereas armchair edges do not. We find that the Dirac model is in quantitative agreement with TB for GALs without edge states, but deviates for antidots with large zigzag regions.Comment: 15 pages, 7 figures. Accepted by Journal of Physics: Condensed matte

Volatility Surface and Skewness in Live Cattle Futures Price Distributions with Application to North American BSE Announcements

options markets, live cattle, volatility, pricing density function, Financial Economics, Livestock Production/Industries, Risk and Uncertainty,

LL601 Contamination and Its Impact on U.S. Rice Prices

LL601 is a genetically modified rice variety and unapproved for commercial use. Its presence was found in commercial shipments of U.S. rice in 2006. This article explores its impact on prices and volume marketed for both the United States and Thailand, the major export competitor. The results show a significantly adverse but short duration effect on the U.S. rice market and little to no effect on the Thai rice market.cointegration, error correction model, event study analysis, GM contamination, LibertyLink Rice 601, U.S. rice exports, Agribusiness, Agricultural and Food Policy, Crop Production/Industries, Food Consumption/Nutrition/Food Safety, International Relations/Trade, Research and Development/Tech Change/Emerging Technologies, C10, C32, Q11, A52,

A legacy of solidaric critique and hope for a better world: A meditation on the scholarly contribution of Ronald Sultana

In this article, we reflect on the legacy of Ronald Sultana who died on Friday 24th November 2023. We argue that he was a major figure in the development of career guidance theory and practice of the late 20th and early 21st century. The article begins by reflecting on and summarising his contribution to the fields of education and career guidance. While we focus on his contribution in the field of career guidance, we also acknowledge that this work sits in a wider body of work in which Sultana’s sociological imagination addressed the operation of the education system around the Mediterranean, across Europe and in the Global South. We explore Sultana’s contribution to theory, policy and practice. We argue that in relation to theory he situated careers in context, carefully traced the range of political roles that career guidance could play and argued for career guidance as a force for social justice. In relation to policy, we highlight his role in international reviews and his critical commentary on this kind of policy borrowing and lending. In relation to practice, we focus on Sultana’s development of resources and study programmes promoting lifelong guidance, and the leveraging of networking to develop a united community of professionals. Finally, we consider the challenges that Ronald left for us and discuss what those who seek to build on his legacy could do