Composition and luminescence studies of InGaN epilayers grown at different hydrogen flow rates

Indium gallium nitride (In(x)Ga(1-x)N) is a technologically important material for many optoelectronic devices, including LEDs and solar cells, but it remains a challenge to incorporate high levels of InN into the alloy while maintaining sample quality. A series of InGaN epilayers was grown with different hydrogen flow rates (0-200 sccm) and growth temperatures (680-750 °C) to obtain various InN fractions and bright emission in the range 390-480 nm. These 160-nm thick epilayers were characterized through several compositional techniques (wavelength dispersive x-ray spectroscopy, x-ray diffraction, Rutherford backscattering spectrometry) and cathodoluminescence hyperspectral imaging. The compositional analysis with the different techniques shows good agreement when taking into account compositional gradients evidenced in these layers. The addition of small amounts of hydrogen to the gas flow at lower growth temperatures is shown to maintain a high surface quality and luminescence homogeneity. This allowed InN fractions of up to ~16% to be incorporated with minimal peak energy variations over a mapped area while keeping a high material quality

Changes in mortality patterns and place of death during the COVID-19 pandemic:A descriptive analysis of mortality data across four nations

Background: Understanding patterns of mortality and place of death during the COVID-19 pandemic is important to help provide appropriate services and resources. Aims: To analyse patterns of mortality including place of death in the United Kingdom (UK) (England, Wales, Scotland and Northern Ireland) during the COVID-19 pandemic to date. Design: Descriptive analysis of UK mortality data between March 2020 and March 2021. Weekly number of deaths was described by place of death, using the following definitions: (1) expected deaths: average expected deaths estimated using historical data (2015–19); (2) COVID-19 deaths: where COVID-19 is mentioned on the death certificate; (3) additional non-COVID-19 deaths: above expected but not attributed to COVID-19; (4) baseline deaths: up to and including expected deaths but excluding COVID-19 deaths. Results: During the analysis period, 798,643 deaths were registered in the UK, of which 147,282 were COVID-19 deaths and 17,672 were additional non-COVID-19 deaths. While numbers of people who died in care homes and hospitals increased above expected only during the pandemic waves, the numbers of people who died at home remained above expected both during and between the pandemic waves, with an overall increase of 41%. Conclusions: Where people died changed during the COVID-19 pandemic, with an increase in deaths at home during and between pandemic waves. This has implications for planning and organisation of palliative care and community services. The extent to which these changes will persist longer term remains unclear. Further research could investigate whether this is reflected in other countries with high COVID-19 mortality

A cluster randomised controlled trial of a web based decision aid to support parents' decisions about their child's Measles Mumps and Rubella (MMR) vaccination.

OBJECTIVE: To evaluate the effectiveness of a web based decision aid versus a leaflet versus, usual practice in reducing parents' decisional conflict for the first dose MMR vaccination decision. The, impact on MMR vaccine uptake was also explored. DESIGN: Three-arm cluster randomised controlled trial. SETTING: Fifty GP practices in the north of, England. PARTICIPANTS: 220 first time parents making a first dose MMR decision. INTERVENTIONS: Web, based MMR decision aid plus usual practice, MMR leaflet plus usual practice versus usual practice only, (control). MAIN OUTCOME MEASURES: Decisional conflict was the primary outcome and used as the, measure of parents' levels of informed decision-making. MMR uptake was a secondary outcome. RESULTS: Decisional conflict decreased post-intervention for both intervention arms to a level where, parents could make an informed MMR decision (decision aid: effect estimate=1.09, 95% CI -1.36 to -0.82; information leaflet: effect estimate=-0.67, 95% CI -0.88 to -0.46). Trial arm was significantly, associated (p<0.001) with decisional conflict at post-intervention. Vaccination uptake was 100%, 91%, and 99% in the decision aid, leaflet and control arms, respectively (χ(2) (1, N=203)=8.69; p=0.017). Post-hoc tests revealed a statistically significant difference in uptake between the information leaflet, and the usual practice arms (p=0.04), and a near statistically significant difference between the, decision aid and leaflet arms (p=0.05). CONCLUSIONS: Parents' decisional conflict was reduced in both, the decision aid and leaflet arms. The decision aid also prompted parents to act upon that decision and, vaccinate their child. Achieving both outcomes is fundamental to the integration of immunisation, decision aids within routine practice. TRIAL REGISTRATION: ISRCTN72521372

Post-mortem AT-8 reactive tau species correlate with non-plaque Aβ levels in the frontal cortex of non-AD and AD brains

The amyloid cascade hypothesis states that Aβ and its aggregates induce pathological changes in tau, leading to formation of neurofibrillary tangles (NFTs) and cell death. A caveat with this hypothesis is the temporo-spatial divide between plaques and NFTs. This has been addressed by the inclusion of soluble species of Aβ and tau in the revised amyloid cascade hypothesis, however, the demonstration of a correlative relationship between Aβ and tau burden in post-mortem human tissue has remained elusive. Employing frozen and fixed frontal cortex grey and associated white matter tissue from non-AD controls (Con; n=39) and Alzheimer’s diseases (AD) cases (n=21), biochemical and immunohistochemical measures of Aβ and AT-8 phosphorylated tau were assessed. Native-state dot-blot from crude tissue lysates demonstrated robust correlations between intraregional Aβ and AT-8 tau, such increases in Aβ immunoreactivity conferred increases in AT-8 immunoreactivity, both when considered across the entire cohort as well as separately in Con and AD cases. In contrast, no such association between Aβ plaques and AT-8 were reported when using immunohistochemical measurements. However, when using the non-amyloid precursor protein cross reactive MOAB-2, antibody to measure intracellular Aβ within a subset of cases, a similar correlative relationship with AT-8 tau as that observed in biochemical analysis was observed. Collectively our data suggests that accumulating intracellular Aβ may influence AT-8 pathology. Despite the markedly lower levels of phospho-tau in non-AD controls correlative relationships between AT-8 phospho-tau and Aβ as measured in both biochemical and immunohistochemical assays were more robust in non-AD controls, suggesting a physiological association of Aβ production and tau phosphorylation, at least within the frontal cortex. Such interactions between regional Aβ load and phospho-tau load may become modified with disease potentially, as a consequence of interregional tau seed propagation, and thus may diminish the linear relationship observed between Aβ and phospho-tau in non-AD controls. This study provides evidence supportive of the revised amyloid cascade hypothesis, and demonstrates an associative relationship between AT-8 tau pathology and intracellular Aβ but not extracellular Aβ plaques

Regional AT-8 reactive tau species correlate with intracellular Aβ levels in cases of low AD neuropathologic change

The amyloid cascade hypothesis states that Aβ aggregates induce pathological changes in tau, leading to neurofibrillary tangles (NFTs) and cell death. A caveat with this hypothesis is the spatio-temporal divide between plaques and NFTs. This has been addressed by the inclusion of soluble Aβ and tau species in the revised amyloid cascade hypothesis. Nevertheless, despite the potential for non-plaque Aβ to contribute to tau pathology, few studies have examined relative correlative strengths between total Aβ, plaque Aβ and intracellular Aβ with tau pathology within a single tissue cohort. Employing frozen and fixed frontal cortex grey and white matter tissue from non-AD controls (Con; n = 39) and Alzheimer’s disease (AD) cases (n = 21), biochemical and immunohistochemical (IHC) measures of Aβ and AT-8 phosphorylated tau were assessed. Biochemical native-state dot blots from crude tissue lysates demonstrated robust correlations between total Aβ and AT-8 tau, when considered as a combined cohort (Con and AD) and when as Con and AD cases, separately. In contrast, no associations between Aβ plaques and AT-8 were reported when using IHC measurements in either Con or AD cases. However, when intracellular Aβ was measured via the Aβ specific antibody MOAB-2, a correlative relationship with AT-8 tau was reported in non-AD controls but not in AD cases. Collectively the data suggests that accumulating intracellular Aβ may influence AT-8 pathology, early in AD-related neuropathological change. Despite the lower levels of phospho-tau and Aβ in controls, the robust correlative relationships observed suggest a physiological association of Aβ production and tau phosphorylation, which may be modified during disease. This study is supportive of a revised amyloid cascade hypothesis and demonstrates regional associative relationships between tau pathology and intracellular Aβ, but not extracellular Aβ plaques

Extravascular fibrinogen in the white matter of Alzheimer's disease and normal aged brains : implications for fibrinogen as a biomarker for Alzheimer's disease

The research was supported by the Alzheimer’s Society (grant numbers AS-PG-2013-011 and AS-JF-18-01). Tissue for this study was provided by the Newcastle Brain Tissue Resource, which is funded in part by a grant from the UK Medical Research Council (G0400074) and by Brains for Dementia research, a joint venture between Alzheimer’s Society and Alzheimer’s Research UK.The blood‐brain barrier (BBB) regulates cerebrovascular permeability and leakage of blood‐derived fibrinogen has been associated with cerebral arteriolosclerosis small vessel disease (SVD) and subsequent white matter lesions (WML). Furthermore, BBB‐dysfunction is associated with the pathogenesis of Alzheimer's disease (AD) with the presence of CSF plasma proteins suggested to be a potential biomarker of AD. We aimed to determine if extravascular fibrinogen in the white matter was associated with the development of AD hallmark pathologies, i.e., hyperphosphorylated tau (HPτ) and amyloid‐β (Aβ), SVD, cerebral amyloid angiopathy (CAA) and measures of white matter damage. Using human post‐mortem brains, parietal tissue from 20 AD and 22 non‐demented controls was quantitatively assessed for HPτ, Aβ, white matter damage severity, axonal density, demyelination and the burden of extravascular fibrinogen in both WML and normal appearing white matter (NAWM). SVD severity was determined by calculating sclerotic indices. WML‐ and NAWM fibrinogen burden was not significantly different between AD and controls nor was it associated with the burden of HPτ or Aβ pathology, or any measures of white matter damage. Increasing severity of SVD was associated with and a predictor (both p < 0.05) of both higher WML‐ and NAWM fibrinogen burden (both P<0.05) in controls only. In cases with minimal SVD NAWM fibrinogen burden was significantly higher in the AD cases (p<0.05). BBB dysfunction was present in both non‐demented and AD brains and was not associated with the burden of AD‐associated cortical pathologies. BBB dysfunction was strongly associated with SVD but only in the non‐demented controls. In cases with minimal SVD, BBB dysfunction was significantly worse in AD cases possibly indicating the influence of CAA. In conclusions, extravascular fibrinogen is not associated with AD hallmark pathologies but indicates SVD, suggesting that the presence of fibrinogen in the CSF is not a surrogate marker for AD pathology.PostprintPeer reviewe

Susceptibility of clinical isolates of frequently encountered bacterial species to tigecycline one year after the introduction of this new class of antibiotics: results of the second multicentre surveillance trial in Germany (G-TEST II, 2007)

Tigecycline, a broad-spectrum antibiotic for parenteral use, was introduced in Germany in May 2006. In the G-TEST-II trial, the susceptibility of isolates, recovered in 2007 from hospitalised patients in 15 centres, was assessed against tigecycline and comparators. Susceptibility tests were performed by the microdilution procedure. This study reports on the susceptibility of the isolates of 16 bacterial species and compares the results with those of a trial (G-TEST I) conducted prior to the introduction of tigecycline. Between 2005 and 2007, tigecycline retained activity against Gram-positive and Gram-negative organisms. By contrast, the rate of vancomycin-resistant strains among Enterococcus faecium isolates almost doubled. Moreover, an increase in resistance to broad-spectrum beta-lactams and fluoroquinolones was observed for members of the family Enterobacteriaceae. Against a background of a steadily rising number of pathogens that are resistant to various antibiotic classes, tigecycline represents an important treatment option

Optical and structural properties of dislocations in InGaN

Threading dislocations in thick layers of InxGa1−xN (5% &amp;lt; x &amp;lt; 15%) have been investigated by means of cathodoluminescence, time-resolved cathodoluminescence, and molecular dynamics. We show that indium atoms segregate near dislocations in all the samples. This promotes the formation of In-N-In chains and atomic condensates, which localize carriers and hinder nonradiative recombination at dislocations. We note, however, that the dark halo surrounding the dislocations in the cathodoluminescence image becomes increasingly pronounced as the indium fraction of the sample increases. Using transmission electron microscopy, we attribute the dark halo to a region of lower indium content formed below the facet of the V-shaped pit that terminates the dislocation in low composition samples (x &amp;lt; 12%). For x &amp;gt; 12%, the facets of the V-defect featured dislocation bundles instead of the low indium fraction region. In this sample, the origin of the dark halo may relate to a compound effect of the dislocation bundles, of a variation of surface potential, and perhaps, of an increase in carrier diffusion length.ER-C Lindemann Trust Fellowshi