Optical matrix elements in tight-binding models with overlap

We investigate the effect of orbital overlap on optical matrix elements in empirical tight-binding models. Empirical tight-binding models assume an orthogonal basis of (atomiclike) states and a diagonal coordinate operator which neglects the intra-atomic part. It is shown that, starting with an atomic basis which is not orthogonal, the orthogonalization process induces intra-atomic matrix elements of the coordinate operator and extends the range of the effective Hamiltonian. We analyze simple tight-binding models and show that non-orthogonality plays an important role in optical matrix elements. In addition, the procedure gives formal justification to the nearest-neighbor spin-orbit interaction introduced by Boykin [Phys. Rev \textbf{B} 57, 1620 (1998)] in order to describe the Dresselahaus term which is neglected in empirical tight-binding models.Comment: 16 pages 6 figures, to appear in Phys. Rev.

Douglas Shoal preliminary site assessment report

Document R.1.59918002, Version 1.Report prepared by Cardno Ltd for the Great Barrier Reef Marine Park Authority

Social media adoption framework for aged care service providers in Australia

© 2017 IEEE. The aged care sector has been a late adopter of social media platforms for communicating, collaborating, marketing and creating brand awareness. There is little research that examines the adoption of social media by aged care service providers for these purposes. This paper reviews the status of social media adoption in the Australian aged care industry, to understand in what ways social media can serve older people's needs, and to develop recommendations for aged-care service providers to adopt social media applications to empower older people. Through a review of the literature and interviews with Australian experts, this paper suggests aged care providers use a three-phase framework when adopting social media in the aged care sector. The first phase is to adopt a popular public social media platform such as Facebook followed by Instagram and Twitter. The second phase supports interaction by encouraging posts and feedback by locally hosted member forums. The third phase is the adoption of specialised social applications for closed groups and specific functions. The paper concludes with a discussion on the implications of the framework and proposes directions for future research

Existence of the Stark-Wannier quantum resonances

In this paper we prove the existence of the Stark-Wannier quantum resonances for one-dimensional Schrodinger operators with smooth periodic potential and small external homogeneous electric field. Such a result extends the existence result previously obtained in the case of periodic potentials with a finite number of open gaps.Comment: 30 pages, 1 figur

Optical injection and terahertz detection of the macroscopic Berry curvature

We propose an experimental scheme to probe the Berry curvature of solids. Our method is sensitive to arbitrary regions of the Brillouin zone, and employs only basic optical and terahertz techniques to yield a background free signal. Using semiconductor quantum wells as a prototypical system, we discuss how to inject Berry curvature macroscopically, and probe it in a way that provides information about the underlying microscopic Berry curvature.Comment: 4 pages, accepted in Physical Review Letter

Longitudinal Changes in the Relationship between Money, Financial Responsibility and Mental Health in the UK:Are we Becoming Less Future Focused?

This paper investigated the changing relationship between socioeconomic factors and mental health over time. Data were analysed from the Understanding Society Database, a representative sample of the UK population consisting of a potential of 150,393 respondents. Multiple regression coefficients over 13 years were compared over time to analyse effects of various financial predictors on mental health. Data was then split according to who reported financial responsibility for the household to investigate the effect of financial responsibility. While analysis suggested a similar pattern of predictors for mental health from the range of socioeconomic variables selected relative to other studies, temporal analysis demonstrated that perception of one's future financial position diminished in influence on mental health over time, whereas financial variables which were grounded in one’s current situation increased in predictive power. The results suggest that individuals are more concerned with current financial pressures and are less affected by what may happen in the future. The results also suggested that financial responsibility was not a strong predictor of the influence of financial situation on mental health. This finding has potential implications for employers, policy makers and mental health practitioners

LIDAR DERIVED SALT MARSH TOPOGRAPHY AND BIOMASS: DEFINING ACCURACY AND SPATIAL PATTERNS OF UNCERTAINTY

As valuable and vulnerable blue carbon ecosystems, salt marshes require adaptable and robust monitoring methods that span a range of spatiotemporal scales. The application of unmanned aerial vehicle (UAV) based remote sensing is a key tool in achieving this goal. Due to the particular characteristics of tidal wetlands, however, there are challenges in obtaining research and management relevant data with the requisite level of accuracy. In this study, the spatial patterns in uncertainty stemming from scan angle, binning method, vegetation structure and platform surface morphology are examined in the context of UAV light detection and ranging (LiDAR) derived digital elevation models (DEM). The results demonstrate that overlapping the UAV flight paths sufficiently to avoid sole reliance on LIDAR data with scan angles exceeding 15 degrees is advisable. Furthermore, the spatial arrangement of halophyte species and marsh morphology has a clear influence on DEM accuracy. The largest errors were associated with sudden structural transitions at the marsh channel boundaries. The DEMmean was found to be the most accurate for bare ground, while the DEMmin was the most accurate for channels and the middle to high marsh vegetation (MAEs = −0.01m). For the low to middle vegetation, all the trialled DEMs returned a similar magnitude of mean error (MAE = ± 0.03m). The accuracy difference between the two vegetation associations examined appears to be connected to variations in coverage, height and biomass. Overall, these findings reinforce the link between salt marsh biogeomorphic complexity and the spatial distribution and magnitude of LiDAR DEM erro

Tissue Damage and Nutritive Value of Warm-Season Grasses Following a Freeze

Bahiagrass (Paspalum notatum Flugge) is a major forage for livestock in the subtropics of the U.S.A. However, it is subject to freeze damage with minimal winter regrowth, and is generally considered a poor grass for stockpiling due to poor quality of the residue. Bahiagrass genotypes have been found showing a range of leaf freezing tolerance in the in the field (-30 C) (Blount et al., 2001). Other C4 grasses have been reported to have genotype-specific tolerances to below-freezing temperatures ranging from -3 to -100 C (Sakai & Larcher, 1987). This research was begun to try to understand the processes that take place following freeze injury to bahiagrass. Three grasses native to the Midwest, big bluestem (Andropogon gerardii Vitman cv Alamo), Indiangrass (Sorghastrum nutans (L.) Nash cv Lometa), and switchgrass (Panicum virgatum L. cv Kaw) and commonly used for stockpiling were used for comparison

2D superconductivity with strong spin-orbit interaction

We consider superconductivity confined at a two-dimensional interface with a strong surface spin-orbit (Rashba) interaction. Some peculiar properties of this system are investigated. In particular, we show that an in-plane Zeeman field can induce a supercurrent flow.Comment: latex, 1 figure in ep