Band anticrossing in GaNxSb1–x

Fourier transform infrared absorption measurements are presented from the dilute nitride semiconductor GaNSb with nitrogen incorporations between 0.2% and 1.0%. The divergence of transitions from the valence band to E– and E+ can be seen with increasing nitrogen incorporation, consistent with theoretical predictions. The GaNSb band structure has been modeled using a five-band k·p Hamiltonian and a band anticrossing fitting has been obtained using a nitrogen level of 0.78 eV above the valence band maximum and a coupling parameter of 2.6 eV

Zenker's Diverticulum: Can Protocolised Measurements with Barium SWALLOW Predict Severity and Treatment Outcomes? The "Zen-Rad" Study

Although barium swallow imaging is established in the investigation of Zenker's diverticulum (ZD), no agreed measurement protocol exists. We developed a protocol for measuring ZD dimensions and aimed to correlate measurements with symptoms and post-operative outcomes. This prospective study included patients with confirmed ZD who underwent flexible endoscopic septal division (FESD) between 2014 and 2018. ZD was confirmed on barium radiology with measurements reviewed by two consultant radiologists. Symptom severity pre- and post-FESD was measured using the Dysphagia, Regurgitation, Complications (DRC) scale. Regression analyses were conducted to identify dimensions associated with therapeutic success, defined as remission (DRC score ≤ 1) 6 months after index FESD. In total, 67 patients (mean age 74.3) were included. Interobserver reliability (intraclass correlation coefficients-ICCs) was greatest for pouch width (0.981) and pouch depth (0.934), but not oesophageal depth (0.018). Male gender (60.9%) was associated with larger pouch height (P = 0.008) and width (P = 0.004). A positive correlation was identified between baseline DRC score and pouch depth (ρ 0.326, P = 0.011), particularly the regurgitation subset score (ρ 0.330, P = 0.020). The index pouch depth was associated with FESD procedure time (rho 0.358, P = 0.041). Therapeutic success was achieved in 64.2% and was associated with shorter pouch height (median 14.5 mm vs. 19.0 mm, P = 0.030), pouch width (median 19.9 mm vs. 28.8 mm, P = 0.34) and cricopharyngeal length (median 20.2 mm vs. 26.3 mm, P = 0.036). ZD dimensions may be feasible and were evaluated using Barium radiology. Specific parameters appear to correlate with severity and post-FESD outcomes, which aid with pre-procedural planning

Zero-field spin-splitting and spin lifetime in n-InSb/In1-xAlxSb asymmetric quantum well heterostructures

The spin-orbit (SO) coupling parameters for lowest conduction subband due to structural (SIA) and bulk (BIA) inversion asymmetry are calculated for a range of carrier densities in [001]-grown delta-doped n-type InSb/In1-xAlxSb asymmetric quantum wells using the established 8 band k.p formalism [PRB 59,8 R5312 (1999)]. We present calculations for conditions of zero bias at 10 K. It is shown that both the SIA and BIA parameters scale approximately linearly with carrier density, and exhibit a marked dependence on well width when alloy composition is adjusted to allow maximum upper barrier height for a given well width. In contrast to other material systems the BIA contribution to spin splitting is found to be of significant and comparable value to the SIA mechanism in these structures. We calculate the spin lifetime for spins oriented along [11-0] based on D'yakonov-Perel mechanism using both the theory of Averkiev et al. [J. Phys.:Condens. Matter 14 (2002)] and also the rate of precession of spins about the effective magnetic field, taking into account all three SO couplings, showing good agreement.Spin lifeime for this direction is largest in the narrow wells over the range of moderate carrier densities considered, which is attributed to the reduced magnitude of the k-cubic BIA parameter in narrow wells. The inherently large BIA induced SO coupling in these systems is shown to have considerable effect on the spin lifetime, which exhibits significant reduction in the maximum spin lifetime compared to previous studies which consider systems with relatively weak BIA induced SO coupling. The relaxation rate of spins oriented in the [001] direction is dominated by the k-linear SIA and BIA coupling parameters and at least an order of magnitude greater than in the [11-0] direction.Comment: 18 pages 12 figure

Care homes’ use of medicines study: prevalence, causes and potential harm of medication errors in care homes for older people

Introduction: Care home residents are at particular risk from medication errors, and our objective was to determine the prevalence and potential harm of prescribing, monitoring, dispensing and administration errors in UK care homes, and to identify their causes. Methods: A prospective study of a random sample of residents within a purposive sample of homes in three areas. Errors were identified by patient interview, note review, observation of practice and examination of dispensed items. Causes were understood by observation and from theoretically framed interviews with home staff, doctors and pharmacists. Potential harm from errors was assessed by expert judgement. Results: The 256 residents recruited in 55 homes were taking a mean of 8.0 medicines. One hundred and seventy-eight (69.5%) of residents had one or more errors. The mean number per resident was 1.9 errors. The mean potential harm from prescribing, monitoring, administration and dispensing errors was 2.6, 3.7, 2.1 and 2.0 (0 = no harm, 10 = death), respectively. Contributing factors from the 89 interviews included doctors who were not accessible, did not know the residents and lacked information in homes when prescribing; home staff’s high workload, lack of medicines training and drug round interruptions; lack of team work among home, practice and pharmacy; inefficient ordering systems; inaccurate medicine records and prevalence of verbal communication; and difficult to fill (and check) medication administration systems. Conclusions: That two thirds of residents were exposed to one or more medication errors is of concern. The will to improve exists, but there is a lack of overall responsibility. Action is required from all concerned

HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope

This paper describes a new Heterodyne Array Receiver Programme (HARP) and Auto-Correlation Spectral Imaging System (ACSIS) that have recently been installed and commissioned on the James Clerk Maxwell Telescope (JCMT). The 16-element focal-plane array receiver, operating in the submillimetre from 325 to 375 GHz, offers high (three-dimensional) mapping speeds, along with significant improvements over single-detector counterparts in calibration and image quality. Receiver temperatures are $\sim$120 K across the whole band and system temperatures of $\sim$300K are reached routinely under good weather conditions. The system includes a single-sideband filter so these are SSB figures. Used in conjunction with ACSIS, the system can produce large-scale maps rapidly, in one or more frequency settings, at high spatial and spectral resolution. Fully-sampled maps of size 1 square degree can be observed in under 1 hour. The scientific need for array receivers arises from the requirement for programmes to study samples of objects of statistically significant size, in large-scale unbiased surveys of galactic and extra-galactic regions. Along with morphological information, the new spectral imaging system can be used to study the physical and chemical properties of regions of interest. Its three-dimensional imaging capabilities are critical for research into turbulence and dynamics. In addition, HARP/ACSIS will provide highly complementary science programmes to wide-field continuum studies, and produce the essential preparatory work for submillimetre interferometers such as the SMA and ALMA.Comment: MNRAS Accepted 2009 July 2. 18 pages, 25 figures and 6 table

Identifying Ligand Binding Conformations of the β2-Adrenergic Receptor by Using Its Agonists as Computational Probes

Recently available G-protein coupled receptor (GPCR) structures and biophysical studies suggest that the difference between the effects of various agonists and antagonists cannot be explained by single structures alone, but rather that the conformational ensembles of the proteins need to be considered. Here we use an elastic network model-guided molecular dynamics simulation protocol to generate an ensemble of conformers of a prototypical GPCR, β2-adrenergic receptor (β2AR). The resulting conformers are clustered into groups based on the conformations of the ligand binding site, and distinct conformers from each group are assessed for their binding to known agonists of β2AR. We show that the select ligands bind preferentially to different predicted conformers of β2AR, and identify a role of β2AR extracellular region as an allosteric binding site for larger drugs such as salmeterol. Thus, drugs and ligands can be used as "computational probes" to systematically identify protein conformers with likely biological significance. © 2012 Isin et al

Neocortical hyperexcitability in a genetic model of absence seizures and its reduction by levetiracetam

PURPOSE: To study the effect of the antiepileptic drug levetiracetam (LEV) on the patterns of intrinsic optical signals (IOSs) generated by slices of the somatosensory cortex obtained from 3- and 6-month-old WAG/Rij and age-matched, nonepileptic control (NEC) rats. METHODS: WAG/Rij and NEC animals were anesthetized with enfluorane and decapitated. Brains were quickly removed, and neocortical slices were cut coronally with a vibratome, transferred to a submerged tissue chamber, and superfused with oxygenated artificial cerebrospinal fluid (aCSF). Slices were illuminated with a dark-field condensor and examined with a x2.5 objective; images were processed with a real time digital video image-enhancement system. Images were acquired before (background) and during electrical stimulation with a temporal resolution of 10 images/s and were displayed in pseudocolors. Extracellular stimuli (200 micros; <4 V) were delivered through bipolar stainless steel electrodes placed in the white matter. RESULTS: IOSs recorded in NEC slices bathed in control aCSF became less intense and of reduced size with age (p < 0.05); this trend was not seen in WAG/Rij slices. Age-dependent decreases in IOS intensity and area size were also seen in NEC slices superfused with aCSF containing the convulsant 4-aminopyridine (4-AP, 5 microM); in contrast, significant increases in both parameters occurred with age in 4-AP-treated WAG/Rij slices (p < 0.05). Under any of these conditions, the IOS intensity and area size slices were larger in WAG/Rij than in NEC slices. LEV (50-500 microM) application to WAG/Rij slices caused dose-dependent IOS reductions that were evident both in control and in 4-AP-containing aCSF and were more pronounced in 6-month-old tissue. CONCLUSIONS: These data demonstrate age-dependent IOS modifications in NEC and WAG/Rij rat slices and identify a clear pattern of hyperexcitability that occurs in 6-month-old WAG/Rij neocortical tissue, an age when absence seizures occur in all animals. The ability of LEV to reduce these patterns of network hyperexcitability supports the potential use of this new antiepileptic drug in primary generalized epileptic disorders