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Suicide-related behaviours are common in schizophrenia and are significantly associated with premature death. The objective of this meta-analysis study was to estimate the pooled prevalence of suicide-related behaviours in schizophrenia patients in China.
The relevant literature was searched systematically via the relevant electronic databases (PubMed, Embase, PsycINFO, Chinese National Knowledge Infrastructure, Wanfang Databases and Chinese Biological Medical Literature Database) from their inception until 14 September 2016. Only original studies that reported the prevalence of suicide-related behaviours including suicidal ideation (SI), suicide plan, suicide attempt (SA) and completed suicide were selected.
Nineteen articles met the inclusion criteria and were analysed. The pooled lifetime prevalence of SI and SA were 25.8% (95% CI 14.7–41.1%) and 14.6% (95% CI 9.1–22.8%), respectively. The 1-month prevalence of SI was 22.0% (95% CI 18.2–26.4%). Subgroup analyses of lifetime SI and SA showed that gender, sample size, survey year, study location and source of patients have no significant mediating effects on the results.
Suicide-related behaviours are common in Chinese schizophrenia patients. Due to the high mortality risk, regular screening and effective suicide prevention programmes are warranted.
Dysfunction of N-methyl-D-aspartate receptor (NMDAR) is involved in the pathophysiology of schizophrenia. A meta-analysis of randomized controlled trials (RCTs) was conducted to examine the efficacy and safety of memantine, a non-competitive NMDAR antagonist, in the treatment of schizophrenia.
Standardized/weighted mean differences (SMDs/WMDs), risk ratio (RR), and their 95% confidence intervals (CIs) were calculated and analyzed.
Included in the meta-analysis were eight RCTs (n = 452) of 11.5 ± 2.6 weeks duration, with 229 patients on memantine (20 mg/day) and 223 patients on placebo. Adjunctive memantine outperformed placebo in the measures of Positive and Negative Syndrome Scale and Brief Psychiatric Rating Scale negative symptoms [SMD: −0.63 (95% CI −1.10 to −0.16), p = 0.009, I2 = 77%], but not in the total, positive and general symptoms [SMD: −0.46 to −0.08 (95% CI −0.93 to 0.22), p = 0.06–0.60, I2 = 0–74%] or the Clinical Global Impression Severity Scale [WMD: 0.04 (95% CI −0.24 to 0.32), p = 0.78]. The negative symptoms remained significant after excluding one outlying RCT [SMD: −0.41 (95% CI −0.72 to −0.11), p = 0.008, I2 = 47%]. Compared with the placebo group, adjunctive memantine was associated with significant improvement in neurocognitive function using the Mini-Mental State Examination (MMSE) [WMD: 3.09, (95% CI 1.77–4.42), p < 0.00001, I2 = 22%]. There was no significant difference in the discontinuation rate [RR: 1.34 (95% CI 0.76–2.37), p = 0.31, I2 = 0%] and adverse drug reactions between the two groups.
This meta-analysis showed that adjunctive memantine appears to be an efficacious and safe treatment for improving negative symptoms and neurocognitive performance in schizophrenia. Higher quality RCTs with larger samples are warranted to confirm these findings.
We describe the performance of the Boolardy Engineering Test Array, the prototype for the Australian Square Kilometre Array Pathfinder telescope. Boolardy Engineering Test Array is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarisation beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of Boolardy Engineering Test Array’s performance: sensitivity, beam characteristics, polarimetric properties, and image quality. We summarise the astronomical science that it has produced and draw lessons from operating Boolardy Engineering Test Array that will be relevant to the commissioning and operation of the final Australian Square Kilometre Array Path telescope.
This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.
Metal-assisted chemical etching (MACE) of silicon (Si) is a simple and low-cost process to fabricate Si nanostructures with varying aspect ratio and properties. In this work, we report on the structural and vibrational properties of Si nanostructures synthesized with varying metal catalyst. The morphology of the synthesized nanowires was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical and vibrational properties of the Si nanostructures were studied by photoluminescence and Raman spectroscopy using three different excitation sources (UV, visible and near-infrared) and are correlated to their microstructures. We propose that the excessive injection of holes into Si at the metal-Si interface and its diffusion to the nanowire surfaces facilitate the etching of Si on these surfaces, leading to a mesoporous network of Si nanocrystallites. When etched with catalytic Au nanoparticles, “hay-stacked” mesoporous Si nanowires were obtained. The straighter nanowires etched with Ag nanoparticles, consisted of a single crystalline core with a thin porous layer that decreased in thickness towards the base of the nanowire. This difference is due to the higher catalytic activity of Au compared to Ag for H2O2 decomposition. The SERRS observed during UV and visible Raman with Ag-etched Si nanowires and near-infrared Raman with Au-etched Si nanowires is due to the presence of the sunken metal nanoparticles. In addition, we explored the influence of varying H2O2 and HF concentration as well as the influence of increased etching temperature on the resultant nanostructured Si morphology. Such Si nanostructures may be useful for a wide range of applications such as photovoltaic and biological and chemical sensing.
As the remnant of Supernova (SN) 1987A has been getting brighter over time, new observations at high frequencies have allowed imaging of the radio emission at unprecedented detail. We present a new radio image at 44 GHz of the supernova remnant (SNR), derived from observations performed with the Australia Telescope Compact Array (ATCA) in 2011. The diffraction-limited image has a resolution of 349×225 mas, which is the highest achieved to date in high-dynamic range images of the SNR. We also present a new image at 18 GHz, also derived from ATCA observations performed in 2011, which is super-resolved to 0″.25. The new 44 and 18 GHz images yield the first high-resolution spectral index map of the remnant. The comparison of the 44 GHz image with contemporaneous X-ray and Hα observations allows further investigations of the nature of the remnant asymmetry and sheds more light into the progenitor hypotheses and SN explosion. In light of simple free-free absorption models, we discuss the likelihood of detecting at 44 GHz the possible emission originating from a pulsar wind nebula (PWN) or a compact source in the centre of the remnant.
Supernovae and their remnants are believed to be prodigious sources of Galactic cosmic rays and interstellar dust. Understanding the mechanisms behind their surprisingly high production rate is helped by the study of nearby young supernova remnants. There has been none better in modern times than SN1987A, for which radio observations have been made for over a quarter of a century. We review extensive observations made with the Australia Telescope Compact Array (ATCA) at centimetre wavelengths. Emission at frequencies from 1 to 100 GHz is dominated by synchrotron radiation from an outer shock front which has been growing exponentially in strength from day 3000, and is currently sweeping around the circumstellar ring at about 4000 km s−1. Three dimensional models of the propagation of the shock into the circumstellar medium are able to reproduce the main observational features of the remnant, and their evolution. We find that up to 4% of the electrons encountered by the shock are accelerated to relativistic energies. High-frequency ALMA observations will break new ground in the understanding of dust and molecule production.
Although usually thought of as external environmental stressors, a significant heritable component has been reported for measures of stressful life events (SLEs) in twin studies.
We examined the variance in SLEs captured by common genetic variants from a genome-wide association study (GWAS) of 2578 individuals. Genome-wide complex trait analysis (GCTA) was used to estimate the phenotypic variance tagged by single nucleotide polymorphisms (SNPs). We also performed a GWAS on the number of SLEs, and looked at correlations between siblings.
A significant proportion of variance in SLEs was captured by SNPs (30%, p = 0.04). When events were divided into those considered to be dependent or independent, an equal amount of variance was explained for both. This ‘heritability’ was in part confounded by personality measures of neuroticism and psychoticism. A GWAS for the total number of SLEs revealed one SNP that reached genome-wide significance (p = 4 × 10−8), although this association was not replicated in separate samples. Using available sibling data for 744 individuals, we also found a significant positive correlation of R2 = 0.08 in SLEs (p = 0.03).
These results provide independent validation from molecular data for the heritability of reporting environmental measures, and show that this heritability is in part due to both common variants and the confounding effect of personality.
The chemical stability of a GaAs layer structure consisting of a thin (10 nm) layer of low-temperature-grown GaAs (LTG:GaAs) on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, is described. Scanning tunneling spectroscopy and X-ray photoelectron spectroscopy performed after atmospheric exposure indicate that the LTG:GaAs surface layer oxidizes much less rapidly than comparable layers of stoichiometric GaAs. There is also evidence that the terminal oxide thickness is smaller than that of stoichiometric GaAs. The spectroscopy results are used to confirm a model for conduction in low resistance, nonalloyed contacts employing comparable layer structures. The inhibited surface oxidation rate is attributed to the bulk Fermi level pinning and the low minority carrier lifetime in unannealed LTG:GaAs. Device applications including low-resistance cap layers for field-effect transistors are described.
Light-emitting diodes (LEDs) based on p-GaN/ZnO heterojunction were fabricated. GaN was deposited on sapphire using metal-organic chemical vapor deposition (MOCVD), and two kinds of ZnO i.e. ZnO thin film deposited by sputtering and ZnO nanorods (NRs) grown by hydrothermal method were used as n-type layer respectively. MgO film with the thickness around 10 nm was deposited by electron-beam deposition to act as an interlayer between GaN and ZnO. Photoluminescence, electroluminescence and I-V curves were measured to compare the properties of GaN based heterojunction LEDs with different architectures. The existence of MgO interlayer as well as the morphology of ZnO obviously influenced the electrical and optical properties of GaN based LEDs. The effect of MgO interlayer on ZnO growth, properties and I-V curves and emission spectra of LEDs is discussed in detail.
While measurement of magnetostriction in bulk materials is readily accomplished using a strain gauge, measurement of this quantity for thin films presents a greater challenge, and typically involves measurement of the overall wafer curvature (for a film of uniform composition) as a function of field. In order to evaluate magnetostriction locally in composition-spread samples, we have developed a method using a dense array of pre-fabricated cantilever beams on a silicon substrate prepared using MEMS techniques. Differential strain in the thin film/cantilever system results in curvature which is detected using an optical (laser/position-sensitive-detector) system. A magnetic field is applied using two orthogonal Helmholtz coils, and the resulting deflection-field curves are used to determine the saturation magnetostriction λs as well as dλ/dH. Our composition-spread films are prepared using a three gun on-axis magnetron cosputtering system. The position-dependent composition is inferred using rate calibrations and verified with electron microprobe and Rutherford Backscattering Spectroscopy. Preliminary experiments have validated the technique and the system has been used to measure magnetostriction in the Ni-Fe system. Our approach can also be used to measure properties of giant magnetostrictive materials (e.g. TbFe/Fe multilayers) as a function of layer thicknesses, or thin film shape-memory alloys, including magnetic shape-memory alloys.
In-situ optical reflectance is used to monitor the morphological evolution of the two-step GaN growth on sapphire. The amount of H2 carrier gas used in the growth is observed to strongly influence the morphological evolution of the low temperature buffer layer and the subsequent high temperature nucleation behavior, which in turn affects the structural and electrical properties of the GaN epitaxial films. The optical reflectance transients correlate with the sizes and distributions of nuclei as observed by AFM.
Magnesium diboride (MgB2) was successfully produced in a pellet with sandwich-like structure. The sample was prepared by embedding a layer of Mg powder in between layers of boron powder before they were cold-pressed and sintered in argon atmosphere at different temperatures. After sintering, the interfacial regions between the Mg and B layers were examined and hexagonal platelets were observed lying along the interfacial regions in samples sintered at temperatures above 700°C. These hexagonal platelets were confirmed as MgB2. When samples were sintered at higher temperatures, the lateral size of the platelets increased. At 700°C, the average size of the platelets was 0.5 μgm, and it increased to 1.5 μgm in sample sintered at 900°C. In addition, the critical temperature (TC) and the magnetization (M) were also changed from 35.4 K to 37.1 K and −0.7 to −1.8 emu/g, respectively.
Growth conditions, structural and optical properties of GaN quantum dots (QDs) grown by plasma-assisted molecular beam epitaxy will be examined. It will be shown that, depending on the Ga/N ratio value and on growth temperature, the growth mode of GaN deposited on AlN can be either of the Stranski-Krastanow or of the Frank-Van der Merwe type. It will be shown that vertical correlation results in a red shift and in a narrowing of the photoluminescence spectra.
Growth of Eu-doped GaN quantum dots embedded in AlN will be described. Intense photoluminescence associated with Eu has been measured, with no GaN band-edge emission, as an evidence that carrier recombination mostly occurs through rare earth ion excitation. Persistent photoluminescence of Eu-doped GaN quantum dots as a function of temperature has been put in evidence, as a further confirmation of the recombination of confined carriers through Eu ion excitation.
Differences in the optical activity of Be in GaN epilayers grown on different surface polarities by rf-plasma molecular beam epitaxy are investigated. Nitrogen-polar GaN doped with Be exhibits a significantly higher intensity of donor-acceptor pair (DAP) photoluminescence (PL) than similarly doped Ga-polar GaN, indicating the Be is incorporating at microscopically different sites, or possibly is forming different compensating complexes. Highly Be-doped Ga-polar GaN apparently forms isolated polarity-inverted regions which then incorporate Be via the N-polar mechanism resulting in the DAP PL. High temperature annealing of the Ga-polar layers both under nitrogen/hydrogen mixtures and under pure nitrogen atmospheres activates the DAP PL.
GaN layers periodically-doped with arsenic were grown by plasma-assisted molecular beam epitaxy on sapphire substrates. Secondary ion mass spectroscopy studies using different secondary ions clearly confirmed the existence of As-modulation in the GaN/GaN:As periodically-doped structures, however, the degree of As-modulation is still under discussion. The use of modulation doping with As has a strong influence on the optical properties of GaN/GaN:As structures.
We report a comparative study of the exciton emission in free standing HVPE layer for all polarization configurations. A noticeable difference between the emission spectra polarized perpendicular and parallel to the c-axis of the crystal is observed. The spectra for E┴c and EIIc are found to be dominated by the emissions of the donor-bound exciton and exciton-polariton both arising from the A and B valence band, respectively, which clearly reveals the optical selection rules in wurtzite GaN. The temperature evolution of the emission spectra is also examined and the thermal redistribution of the excitons at different polarization is discussed.