Giant Stark effect in the emission of single semiconductor quantum dots

We study the quantum-confined Stark effect in single InAs/GaAs quantum dots embedded within a AlGaAs/GaAs/AlGaAs quantum well. By significantly increasing the barrier height we can observe emission from a dot at electric fields of -500 kV/cm, leading to Stark shifts of up to 25 meV. Our results suggest this technique may enable future applications that require self-assembled dots with transitions at the same energy

Item 1. Apologies

Apologies were received from Stephen Burt & Dave Bullock. Item 2. Agreement of agenda The agenda was agreed. Item 3. Minutes of last meeting The minutes of the committee meeting & AGM held on 12 th September 2014 were agreed as being correct. Item 4. Items arising Actions from the previous committee meeting were considered and the following matters were discussed: Rain gauge raffle – At the 2013 RMetS Amateur Meteorologist Symposium, MD organised a SIG stand where he raffled an EML rain gauge, signed-up 29 new members & raised £145. MD was thanked for his hard work. New committee member – MD has contacted, but not yet had a reply from, Mark Wilkinson (James Hutton Institute, Aberdeen) to invite him to join the SIG committee. The SIG has offered to pay travel expenses for Mark for one trip/year to attend a SI

The heme-hemopexin scavenging system is active in the brain, and associates with outcome after subarachnoid hemorrhage

Background and Purpose – Long-term outcome after subarachnoid hemorrhage (SAH) is potentially linked to cytotoxic heme. Free heme is bound by hemopexin (Hpx) and rapidly scavenged by CD91. We hypothesized that heme scavenging in the brain would be associated with outcome after haemorrhage. Methods - Using cerebrospinal fluid (CSF) and tissue from SAH patients and control individuals, the activity of the intracranial CD91-Hpx system was examined using enzyme-linked immunoassays, ultra-high performance liquid chromatography and immunohistochemistry. Results - In control individuals, CSF Hpx was mainly synthesized intrathecally. After SAH, CSF Hpx was high in one-third of cases, and these patients had a higher probability of delayed cerebral ischaemia and poorer neurological outcome. The intracranial CD91-Hpx system was active after SAH since CD91 positively correlated with iron deposition in brain tissue. Heme-Hpx uptake saturated rapidly after SAH, since bound heme accumulated early in the CSF. When the blood-brain barrier was compromised following SAH, serum Hpx level was lower, suggesting heme transfer to the circulation for peripheral CD91 scavenging. Conclusions - The CD91-heme-Hpx scavenging system is important after SAH and merits further study as a potential prognostic marker and therapeutic target

Tunable Indistinguishable Photons From Remote Quantum Dots

Single semiconductor quantum dots have been widely studied within devices that can apply an electric field. In the most common system, the low energy offset between the InGaAs quantum dot and the surrounding GaAs material limits the magnitude of field that can be applied to tens of kVcm^-1, before carriers tunnel out of the dot. The Stark shift experienced by the emission line is typically 1 meV. We report that by embedding the quantum dots in a quantum well heterostructure the vertical field that can be applied is increased by over an order of magnitude whilst preserving the narrow linewidths, high internal quantum efficiencies and familiar emission spectra. Individual dots can then be continuously tuned to the same energy allowing for two-photon interference between remote, independent, quantum dots

Techniques to increase lumbar puncture success in newborn babies: the NeoCLEAR RCT

BackgroundLumbar puncture is an essential tool for diagnosing meningitis. Neonatal lumbar puncture, although frequently performed, has low success rates (50–60%). Standard technique includes lying infants on their side and removing the stylet ‘late’, that is, after the needle is thought to have entered the cerebrospinal fluid. Modifications to this technique include holding infants in the sitting position and removing the stylet ‘early’, that is, following transection of the skin. To the best of our knowledge, modified techniques have not previously been tested in adequately powered trials.ObjectivesThe aim of the Neonatal Champagne Lumbar punctures Every time – An RCT (NeoCLEAR) trial was to compare two modifications to standard lumbar puncture technique, that is, use of the lying position rather than the sitting position and of ‘early’ rather than ‘late’ stylet removal, in terms of success rates and short-term clinical, resource and safety outcomes.MethodsThis was a multicentre 2 × 2 factorial pragmatic non-blinded randomised controlled trial. Infants requiring lumbar puncture (with a working weight ≥ 1000 g and corrected gestational age from 27+0 to 44+0 weeks), and whose parents provided written consent, were randomised by web-based allocation to lumbar puncture (1) in the sitting or lying position and (2) with early or late stylet removal. The trial was powered to detect a 10% absolute risk difference in the primary outcome, that is, the percentage of infants with a successful lumbar puncture (cerebrospinal fluid containing 2.5 kg (971/1076, 90.2%). Baseline characteristics were balanced across groups. In terms of the primary outcome, the sitting position was significantly more successful than lying [346/543 (63.7%) vs. 307/533 (57.6%), adjusted risk ratio 1.10 (95% confidence interval 1.01 to 1.21); p = 0.029; number needed to treat = 16 (95% confidence interval 9 to 134)]. There was no significant difference in the primary outcome between early stylet removal and late stylet removal [338/545 (62.0%) vs. 315/531 (59.3%), adjusted risk ratio 1.04 (95% confidence interval 0.94 to 1.15); p = 0.447]. Resource consumption was similar in all groups, and all techniques were well tolerated and safe.LimitationsThis trial predominantly recruited term-born infants who were 2.5 kg. The impact of practitioners’ seniority and previous experience of different lumbar puncture techniques was not investigated. Limited data on resource use were captured, and parent/practitioner preferences were not assessed.ConclusionLumbar puncture success rate was higher with infants in the sitting position but was not affected by timing of stylet removal. Lumbar puncture is a safe, well-tolerated and simple technique without additional cost, and is easily learned and applied. The results support a paradigm shift towards sitting technique as the standard position for neonatal lumbar puncture, especially for term-born infants during the first 3 days of life.Future workThe superiority of the sitting lumbar puncture technique should be tested in larger populations of premature infants, in those aged > 3 days and outside neonatal care settings. The effect of operators’ previous practice and the impact on family experience also require further investigation, alongside in-depth analyses of healthcare resource utilisation. Future studies should also investigate other factors affecting lumbar puncture success, including further modifications to standard technique.Trial registrationThis trial is registered as ISRCTN14040914 and as Integrated Research Application System registration 223737.FundingThis award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 15/188/106) and is published in full in Health Technology Assessment; Vol. 27, No. 33. See the NIHR Funding and Awards website for further award information

Atmospheric electrification in dusty, reactive gases in the solar system and beyond

Detailed observations of the solar system planets reveal a wide variety of local atmospheric conditions. Astronomical observations have revealed a variety of extrasolar planets none of which resembles any of the solar system planets in full. Instead, the most massive amongst the extrasolar planets, the gas giants, appear very similar to the class of (young) Brown Dwarfs which are amongst the oldest objects in the universe. Despite of this diversity, solar system planets, extrasolar planets and Brown Dwarfs have broadly similar global temperatures between 300K and 2500K. In consequence, clouds of different chemical species form in their atmospheres. While the details of these clouds differ, the fundamental physical processes are the same. Further to this, all these objects were observed to produce radio and X-ray emission. While both kinds of radiation are well studied on Earth and to a lesser extent on the solar system planets, the occurrence of emission that potentially originate from accelerated electrons on Brown Dwarfs, extrasolar planets and protoplanetary disks is not well understood yet. This paper offers an interdisciplinary view on electrification processes and their feedback on their hosting environment in meteorology, volcanology, planetology and research on extrasolar planets and planet formation

The Dangerous Woman of Melvillean Melodrama

Almost in its death throes at the turn of the present century, sensational melodrama threw up a curious mutation at the hands of the prolific playwrights and managers, the brothers Walter and Frederick Melville. In numerous of their plays performed in the decade or so before the First World War, the ‘New Woman’, whose rights and rebellions were simultaneously the focus of debate in so-called ‘problem’ plays, took on a new and threatening aspect – as the eponymously ‘dangerous’ central character of The Worst Woman in London, A Disgrace to Her Sex, The Girl Who Wrecked His Home, and a score or so of similar titles. In the following article Elaine Aston and lan Clarke explore the nature of these ‘strong’ female roles, both as acting vehicles and as embodiments of male fears and fantasies, in a theatre which existed in large part to serve such needs and which, through such characters, at once fictionalized and affirmed the fears of ‘respectable’ society about the moral stature of the actress. The authors both teach in the Department of English and Drama at Loughborough University, where lan Clarke is Director of Drama, having previously published his own study of Edwardian Drama in 1989

Conodont biostratigraphic control on transitional marine to non-marine Permian-Triassic boundary sequences in Yunnan-Guizhou, China

The recovery of conodonts associated with ash beds and magnetostratigraphy in the key Zhongzhai Section, near Langdai, Liuzhi, Guizhou Province, provides precise and definitive control on the position of the Permian-Triassic boundary in the transition from marine to non-marine facies of western Guizhou and eastern Yunnan Provinces of southwestern China. In the Zhongzhai Section the boundary interval consists of a lower limestone, 20 cm thick, that contains fragments of Hindeodus sp. and Clarkina sp. This is overlain by a 50 cm thick black shale bed containing an abundant brachiopod fauna, but only a single conodont fragment. This bed is in turn overlain by a 23 cm thick limestone that contains Clarkina meishanensis, Merrillina ultima, Hindeodus changxingensis, H. praeparvus and H. eurypyge. Directly over this limestone is a 5 cm thick ash bed followed by a 10 cm thick black shale, which is overlain by a second, upper, ash bed that is 3 cm thick. On top of the upper ash bed is a 20 cm thick silty limestone containing an abundant dwarf conodont fauna, dominated by Hindeodus, and containing H. parvus but also including Clarkina tulongensis. The Permian-Triassic boundary is placed at the level of the black shale located between the two ash beds