Atomic Effective Pseudopotentials for Semiconductors

We derive an analytic connection between the screened self-consistent effective potential from density functional theory (DFT) and atomic effective pseudopotentials (AEPs). The motivation to derive AEPs is to address structures with thousands to hundred thousand atoms, as given in most nanostructures. The use of AEPs allows to bypass a self-consistent procedure and to address eigenstates around a certain region of the spectrum (e.g., around the band gap). The bulk AEP construction requires two simple DFT calculations of slightly deformed elongated cells. The ensuing AEPs are given on a fine reciprocal space grid, including the small reciprocal vector components, are free of parameters, and involve no fitting procedure. We further show how to connect the AEPs of different bulk materials, which is necessary to obtain accurate band offsets. We derive a total of 20 AEPs for III-V, II-VI and group IV semiconductors and demonstrate their accuracy and transferability by comparison to DFT calculations of strained bulk structures, quantum wells with varying thickness, and semiconductor alloys.Comment: 10 pages, 5 figures, submitted to PR

Paediatric burns anaesthesia: the things that make a difference

Anaesthesia and pain management for paediatric burns continues to challenge and frustrate healthcare professionals in this field of medicine. This review aims to provide some practical management strategies to enable the improved care of burned children. The pathophysiology of burns, toxic shock syndrome, inhalational injuries and perioperative care of paediatric burns is addressed.Keywords: paediatric, burns, pathophysiology, anaesthesia, analgesia, inhalational injurie

Influence of the charge carrier tunneling processes on the recombination dynamics in single lateral quantum dot molecules

We report on the charge carrier dynamics in single lateral quantum dot molecules and the effect of an applied electric field on the molecular states. Controllable electron tunneling manifests itself in a deviation from the typical excitonic decay behavior which is strongly influenced by the tuning electric field and inter-molecular Coulomb energies. A rate equation model is developed to gain more insight into the charge transfer and tunneling mechanisms. Non-resonant (phonon-mediated) electron tunneling which changes the molecular exciton character from direct to indirect, and vice versa, is found to be the dominant tunable decay mechanism of excitons besides radiative recombination.Comment: 4 pages, 4 figure

A review of data on abundance, trends in abundance, habitat use and diet of ice-breeding seals in the Southern Ocean

The development of models of marine ecosystems in the Southern Ocean is becoming increasingly important as a means of understanding and managing impacts such as exploitation and climate change. Collating data from disparate sources, and understanding biases or uncertainties inherent in those data, are important first steps for improving ecosystem models. This review focuses on seals that breed in ice habitats of the Southern Ocean (i.e. crabeater seal, Lobodon carcinophaga; Ross seal, Ommatophoca rossii; leopard seal, Hydrurga leptonyx; and Weddell seal, Leptonychotes weddellii). Data on populations (abundance and trends in abundance), distribution and habitat use (movement, key habitat and environmental features) and foraging (diet) are summarised, and potential biases and uncertainties inherent in those data are identified and discussed. Spatial and temporal gaps in knowledge of the populations, habitats and diet of each species are also identified

Linkage study of the low-density lipoprotein-receptor gene and cholesterol levels in an Afrikaner family : quantitative genetics and identification of a minor founder effect

CITATION: Brink, P. A. et al. 1990. Linkage study of the low-density lipoprotein-receptor gene and cholesterol levels in an Afrikaner family : quantitative genetics and identification of a minor founder effect. South African Medical Journal, 77:292-296.The original publication is available at http://www.samj.org.zaOverlap of clinical and biochemical characteristics between hypercholesterolaemia in members of the general population and familial hypercholesterolaemic (FH) individuals may lead to misdiagnosis. Quantitative analyisis of family data may circumvent this problem. A way of looking for an association between plasma cholesterol levels and restriction fragment length polymorphism markers (RFLP) on the low-density lipoprotein (LDL) receptor gene by using reference cholesterol distributions was explored. Linkage, with a logarithm of the odds (LOD) score of 6,8 at θ 0, was detected between cholesterol levels and the LDL receptor in an extended Afrikaner family. Two RFLP-haplotypes, one previously found in a majority of Afrikaner FH homozygotes, and a second, Stu I -, BstE II +, Pvu II +, Nco I +, were associated with high cholesterol levels in this pedigree.Publisher’s versio

Tract-specific white matter correlates of fatigue and cognitive impairment in benign multiple sclerosis

Background: Although benign multiple sclerosis (BMS) is traditionally defined by the presence of mild motor involvement decades after disease onset, symptoms of fatigue and cognitive impairment are very common. Objective: To investigate the association between micro-structural damage in the anterior thalamic (AT) tracts and in the corpus callosum (CC), as measured by diffusion tensor imaging (DTI) tractography, and fatigue and cognitive deficits. Methods: DTI data were acquired from 26 BMS patients and 24 sex- and age-matched healthy controls. Results: General and mental fatigue scores were significantly impaired in patients compared with controls (p≤0.05 for both) and 38% of patients resulted cognitively impaired. Mean diffusivity (MD) of the AT and CC tracts was significantly higher and fractional anisotropy (FA) was lower in patients compared with controls (p<0.001 for all). Fatigue was associated with increased MD (p=0.01) of the AT tracts whereas deficit of executive functions and verbal learning were associated with decreased FA in the body (p=0.004) and genu (p=0.008) of the CC. Deficits in processing speed and attention were associated with the T2 lesion volume of the AT tracts (p<0.01 for all). Discussion: These findings suggest that fatigue and cognitive impairment are quite frequent in BMS patients and are, at least in part, related to micro-structural damage and T2LV of WM tracts connecting the brain cortical and sub-cortical regions of the two hemispheres

The lived experience of health sciences students’ participation in an interprofessional community-based stroke class

Background. Collaborative approaches in healthcare contexts may provide better care for patients. Interprofessional circuit-based group therapy could counter profession-specific tribalism. There is no evidence on interprofessional education (IPE) community-based interventions on student learning in the health professions. Objective. To explore undergraduate health sciences students’ experience of being involved in community-based interprofessional circuit-based group therapy. Methods. Semi-structured interviews were inductively analysed exploring undergraduate health sciences students’ experience of involvement in an IPE community-based stroke intervention. Results. A total of 12 final-year students participated, with representation from physiotherapy, occupational therapy and speech therapy. This IPE opportunity beneficially impacted students’ collaborative competencies in knowledge, attitudes, skills and behaviours. This community-based rotation immersed students in a service-delivery environment where patient management was co-ordinated by a multiprofessional rehabilitation team. The integrated stroke circuit group activity aimed to enhance further interconnectedness between student participants. Students who were exposed to this clinical activity reported an understanding of (i) patients’ unique contexts; (ii) role development and complementary overlap between health professions; and (iii) the value of joint interventions to both patients and rehabilitation teams in resource-constrained settings. Conclusion. These students have been primed in their practice-readiness as healthcare professionals for the 21st century who will promote quality care, and embrace collaborative professional practice and person-centredness

Collateral and Debt Maturity Choice. A Signaling Model

This paper derives optimal loan policies under asymmetric information where banks offer loan contracts of long and short duration, backed or unbacked with collateral. The main novelty of the paper is that it analyzes a setting in which high quality firms use collateral as a complementary device along with debt maturity to signal their superiority. The least-cost signaling equilibrium depends on the relative costs of the signaling devices, the difference in firm quality and the proportion of good firms in the market. Model simulations suggest a non-monotonic relationship between firm quality and debt maturity, in which high quality firms have both long-term secured debt and short-term secured or non-secured debt.

A Spectral Line Survey of Selected 3 mm Bands Toward Sagittarius B2(N-LMH) Using the NRAO 12 Meter Radio Telescope and the BIMA Array I. The Observational Data

We have initiated a spectral line survey, at a wavelength of 3 millimeters, toward the hot molecular core Sagittarius B2(N-LMH). This is the first spectral line survey of the Sgr B2(N) region utilizing data from both an interferometer (BIMA Array) and a single-element radio telescope (NRAO 12 meter). In this survey, covering 3.6 GHz in bandwidth, we detected 218 lines (97 identified molecular transitions, 1 recombination line, and 120 unidentified transitions). This yields a spectral line density (lines per 100 MHz) of 6.06, which is much larger than any previous 3 mm line survey. We also present maps from the BIMA Array that indicate that most highly saturated species (3 or more H atoms) are products of grain chemistry or warm gas phase chemistry. Due to the nature of this survey we are able to probe each spectral line on multiple spatial scales, yielding information that could not be obtained by either instrument alone.Comment: 35 pages, 15 figures, to be published in The Astrophysical Journa