1,396 research outputs found

    Evidence for quantum confinement in the photoluminescence of porous Si and SiGe

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    We have used anodization techniques to process porous surface regions in p-type Czochralski Si and in p-type Si0.85Ge0.15 epitaxial layers grown by molecular beam epitaxy. The SiGe layers were unrelaxed before processing. We have observed strong near-infrared and visible light emission from both systems. Analysis of the radiative and nonradiative recombination processes indicate that the emission is consistent with the decay of excitons localized in structures of one or zero dimensions

    The risk of miscarriage following COVID-19 vaccination: a systematic review and meta-analysis

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    STUDY QUESTION: What is the risk of miscarriage among pregnant women who received any of the COVID-19 vaccines? SUMMARY ANSWER: There is no evidence that COVID-19 vaccines are associated with an increased risk of miscarriage. WHAT IS KNOWN ALREADY: In response to the COVID-19 pandemic, the mass roll-out of vaccines helped to boost herd immunity and reduced hospital admissions, morbidity and mortality. Still, many were concerned about the safety of vaccinesfor pregnancy, which may have limited their uptake among pregnant women and those planning a pregnancy. STUDY DESIGN, SIZE, DURATION: For this systematic review and meta-analysis, we searched MEDLINE, EMBASE and Cochrane CENTRAL from inception until June 2022 using a combination of keywords and MeSH terms. PARTICIPANTS/MATERIALS, SETTING, METHODS: We included observational and interventional studies that enrolled pregnant women and evaluated any of the available COVID-19 vaccines compared to placebo or no vaccination. We primarily reported on miscarriage in addition to ongoing pregnancy and/or live birth. MAIN RESULTS AND THE ROLE OF CHANCE: We included data from 21 studies (5 randomised trials and 16 observational studies) reporting on 149,685 women. The pooled rate of miscarriage among women who received a COVID-19 vaccine was 9% (n = 147,49/123,185, 95%CI 0.05-0.14). Compared to those who received a placebo or no vaccination, women who received a COVID-19 vaccine did not have a higher risk of miscarriage (RR 1.07, 95%CI 0.89-1.28, I2 35.8%) and had comparable rates for ongoing pregnancy or live birth (RR 1.00, 95%CI 0.97-1.03, I2 10.72%). LIMITATIONS, REASONS FOR CAUTION: Our analysis was limited to observational evidence with varied reporting, high heterogeneity and risk of bias across included studies, which may limit the generalisability and confidence in our findings. WIDER IMPLICATIONS OF THE FINDINGS: COVID-19 vaccines are not associated with an increase in the risk of miscarriage or reduced rates of ongoing pregnancy or live birth among women of reproductive age. The current evidence remains limited and larger population studies are needed to further evaluate the effectiveness and safety of COVID-19 in pregnancy. STUDY FUNDING/COMPETING INTEREST: No direct funding was provided to support this work. MPR is funded by the Medical Research Council Centre for Reproductive Heath Grant No: MR/N022556/1. BHA hold a personal development award from the National Institute of Health Research in the UK. All authors declare no conflict of interest. REGISTRATION NUMBER: CRD42021289098

    Preliminary laboratory studies of the optical scattering properties of the crystal clouds

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    A spectral survey of an ultra-hot Jupiter: Detection of metals in the transmission spectrum of KELT-9 b

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    Context: KELT-9 b exemplifies a newly emerging class of short-period gaseous exoplanets that tend to orbit hot, early type stars - termed ultra-hot Jupiters. The severe stellar irradiation heats their atmospheres to temperatures of 4,000\sim 4,000 K, similar to the photospheres of dwarf stars. Due to the absence of aerosols and complex molecular chemistry at such temperatures, these planets offer the potential of detailed chemical characterisation through transit and day-side spectroscopy. Studies of their chemical inventories may provide crucial constraints on their formation process and evolution history. Aims: To search the optical transmission spectrum of KELT-9 b for absorption lines by metals using the cross-correlation technique. Methods: We analyse 2 transits observed with the HARPS-N spectrograph. We use an isothermal equilibrium chemistry model to predict the transmission spectrum for each of the neutral and singly-ionized atoms with atomic numbers between 3 and 78. Of these, we identify the elements that are expected to have spectral lines in the visible wavelength range and use those as cross-correlation templates. Results: We detect absorption of Na I, Cr II, Sc II and Y II, and confirm previous detections of Mg I, Fe I, Fe II and Ti II. In addition, we find evidence of Ca I, Cr I, Co I, and Sr II that will require further observations to verify. The detected absorption lines are significantly deeper than model predictions, suggesting that material is transported to higher altitudes where the density is enhanced compared to a hydrostatic profile. There appears to be no significant blue-shift of the absorption spectrum due to a net day-to-night side wind. In particular, the strong Fe II feature is shifted by 0.18±0.270.18 \pm 0.27 km~s1^{-1}, consistent with zero. Using the orbital velocity of the planet we revise the steller and planetary masses and radii.Comment: Submitted to Astronomy and Astrophysics on January 18, 2019. Accepted on May 3, 2019. 26 pages, 11 figure

    Efficacy of virtual reality for pain relief in medical procedures: A systematic review and meta-analysis

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    BackgroundEffective pain control is crucial to optimise the success of medical procedures. Immersive virtual reality (VR) technology could offer an effective non-invasive, non-pharmacological option to distract patients and reduce their experience of pain. We aimed to evaluate the efficacy of Immersive virtual reality (VR) technology in reducing patient’s pain perception during various medical procedures by conducting a systematic review and meta-analysis.MethodsWe searched MEDLINE, EMBASE, CENTRAL, CINAHL, and SIGLE until December 2022 for all randomised clinical trials (RCT) evaluating any type of VR in patients undergoing any medical procedure. We conducted a random effect meta-analysis summarising standardised mean differences (SMD) with 95% confidence intervals (CI). We evaluated heterogeneity using I 2 and explored it using subgroup and meta-regression analyses.ResultsIn total, we included 92 RCTs (n = 7133 participants). There was a significant reduction in pain scores with VR across all medical procedures (n = 83, SMD − 0.78, 95% CI − 1.00 to − 0.57, I 2 = 93%, p = < 0.01). Subgroup analysis showed varied reduction in pain scores across trial designs [crossover (n = 13, SMD − 0.86, 95% CI − 1.23 to − 0.49, I 2 = 72%, p = < 0.01) vs parallel RCTs (n = 70, SMD − 0.77, 95% CI − 1.01 to − 0.52, I 2 = 90%, p = < 0.01)]; participant age groups [paediatric (n = 43, SMD − 0.91, 95% CI − 1.26 to − 0.56, I 2 = 87%, p = < 0.01) vs adults (n = 40, SMD − 0.66, 95% CI − 0.94 to − 0.39, I 2 = 89%, p = < 0.01)] or procedures [venepuncture (n = 32, SMD − 0.99, 95% CI − 1.52 to − 0.46, I 2 = 90%, p = < 0.01) vs childbirth (n = 7, SMD − 0.99, 95% CI − 1.59 to − 0.38, I 2 = 88%, p = < 0.01) vs minimally invasive medical procedures (n = 25, SMD − 0.51, 95% CI − 0.79 to − 0.23, I 2 = 85%, p = < 0.01) vs dressing changes in burn patients (n = 19, SMD − 0.8, 95% CI − 1.16 to − 0.45, I 2 = 87%, p = < 0.01)]. We explored heterogeneity using meta-regression which showed no significant impact of different covariates including crossover trials (p = 0.53), minimally invasive procedures (p = 0.37), and among paediatric participants (p = 0.27). Cumulative meta-analysis showed no change in overall effect estimates with the additional RCTs since 2018.ConclusionsImmersive VR technology offers effective pain control across various medical procedures, albeit statistical heterogeneity. Further research is needed to inform the safe adoption of this technology across different medical disciplines

    The effectiveness and satisfaction of web-based physiotherapy in people with spinal cord injury: a pilot randomised controlled trial

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    Study Design: Pilot randomised controlled trial. Objectives: The aims of this study were to evaluate the effectiveness and participant satisfaction of web-based physiotherapy for people with Spinal Cord Injury (SCI). Setting: Community patients of a national spinal injury unit in a university teaching hospital, Scotland, UK. Methods: Twenty-four participants were recruited and randomised to receive eight weeks of web-based physiotherapy (intervention), twice per week, or usual care (control). Individual exercise programmes were prescribed based upon participant’s abilities. The intervention was delivered via a website (www.webbasedphysio.com) and monitored and progressed remotely by the physiotherapist. Results: Participants logged on to the website an average of 1.4±0.8 times per week. Between-group differences, although not significant were more pronounced for the 6 minute walk test. Participants were positive about using web-based physiotherapy and stated they would be happy to use it again and would recommend it to others. Overall it was rated as either good or excellent. Conclusions: Web-based physiotherapy was feasible and acceptable for people with SCI. Participants achieved good compliance with the intervention, rated the programme highly and beneficial for health and well-being at various states post injury. The results of this study warrant further work with a more homogenous sample
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