Efficient single-photon source based on a deterministically fabricated single quantum dot - microstructure with backside gold mirror

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 111, 011106 (2017) and may be found at https://doi.org/10.1063/1.4991389.We present an efficient broadband single-photon source which is fabricated by a flip-chip gold-bonding technique and in-situ electron beam lithography. The device comprises a single InGaAs quantum dot that is centered at the bottom of a monolithic mesa structure and located above a gold mirror for enhanced photon-extraction efficiency. We show a photon-extraction efficiency of ηext=(18±2) % into a numerical aperture of 0.4 and a high suppression of multi-photon events from this source with g(2)(0)=0.015±0.009. Our deterministic device with a backside gold mirror can be combined with electrical contacts and piezo-tuning capabilities in future refinements, which represents an important step towards a spectrally tunable plug-and-play quantum-light source with broadband enhancement for photonic quantum networks.DFG, SFB 787, Halbleiter - Nanophotonik: Materialien, Modelle, BauelementeBMBF, 03V0630TIB, Entwicklung einer Halbleiterbasierten Einzelphotonenquelle für die Quanteninformationstechnologi

Das Projekt Armenküche / Cantinea in Dorohoi, Rumänien

Die Autorinnen evaluieren das Entwicklungszusammenarbeitsprojekt Armenküche in Rumänien aus dem Blickwinkel der Sozialen Arbeit. Auf theoretischer Basis vergleichen sie die Grundsätze der Entwicklungszusammenarbeit mit der Sozialen Arbeit. Daraus wird ersichtlich, dass die beiden Professionen sehr viele Gemeinsamkeiten haben. Die Bewertung des Projektes Armenküche erfolgt unter Anbetracht der jüngsten geschichtlichen Ereignisse und der daraus folgenden schwierigen wirtschaftlichen Lage Rumäniens. Dazu verwenden die Autorinnen ein Forschungsdesign, das aus Ethnographie und quantitativer Forschung besteht. Grundlagen für die Forschung sind die Theorien, Grundsätze und Methoden der Sozialen Arbeit sowie der Entwicklungszusammenarbeit. Die Forschungsergebnisse belegen, dass die Armutsproblematik eine grosse Herausforderung für das Projekt darstellt, da die Menschen dadurch häufig resigniert sind und deswegen wenig Eigeninitiative zeigen. Die Projektziele werden weitgehend erreicht, unter Einbezug der Sozialen Arbeit ist aber durchaus Verbesserungspotenzial vorhanden. Dieses Verbesserungspotenzial nehmen die Autorinnen auf, indem sie konkrete Optimierungsvorschläge aus der Sicht der Sozialen Arbeit formulieren. Solche Veränderungsvorschläge sind von den Betroffenen gemäss Ergebnissen erwünscht. Diese zeigen ausserdem, dass das Projekt sehr gut funktioniert. Nennenswert ist, dass die im Projekt vorhandenen sozialarbeiterischen Aspekte allesamt als positive Faktoren gewertet werden, während die negativen Aspekte durch Interventionen der Sozialen Arbeit optimiert werden könnten. Die Empirie und die Theorie bestätigen, dass die Grundsätze, Theorien und Methoden der Sozialen Arbeit in Projekten der Entwicklungszusammenarbeit eine wichtige Rolle spielen können

Child maltreatment in Swiss welfare care until 1981: former caregivers’ perspectives on the welfare context

Caregivers can provide insight into the welfare aspects of institutional child maltreatment not apparent to children in care. This qualitative study investigated how socio-ecological and contextual aspects of the welfare system were linked to (quality of) care provision and the well-being of minors in care. Semi-structured interviews were conducted with 12 Swiss former caregivers. Welfare aspects included a shortage of resources, poor working conditions, and lack of oversight by the authorities. Social norms also contributed to stigmatization, discrimination, and the normalization of adverse care practices. Potential protective factors included external support and resource provision, caregiver resistance, and (later) social acknowledgment

Four decades of phenology in an alpine amphibian: trends, stasis, and climatic drivers

Strong phenological shifts in response to changes in climatic conditions have been reported for many species, including amphibians, which are expected to breed earlier. Phenological shifts in breeding are observed in a wide number of amphibian populations, but less is known about populations living at high elevations, which are predicted to be more sensitive to climate change than lowland populations. The goal of this study is to assess the main factors determining the timing of breeding in an alpine population of the common toad (Bufo bufo) and to describe the observed shifts in its breeding phenology. We modelled the effect of environmental variables on the start and peak dates of the breeding season using 39 years of individual-based data. In addition, we investigated the effect of the lunar cycle, as well as the individual variation in breeding phenology. Finally, to assess the individual heterogeneity in the timing of breeding, we calculated the repeatability of the timing of arrival at the breeding site. Breeding advanced to earlier dates in the first years of the study but the trend continued only until the mid 1990s, and stabilised afterwards. Overall, toads are now breeding on average around 30 days earlier than at the start of the study period. High temperatures and low snow cover in winter and spring, as well as reduced spring precipitation were all associated with earlier breeding. Additionally, we found evidence of males arriving on average before females at the breeding site but no clear and strong effect of the lunar cycle. We only found weak evidence of among-individual variation in shifts in the breeding phenology, as well as a low repeatability of arrival timing. Our findings show that the observed changes in breeding phenology are strongly associated with the environmental conditions. These results contribute to filling a knowledge gap on the effects of climate change on alpine amphibian populations. Moreover, we show that changes in phenology, especially in the mountains, can be hard to predict as local microclimatic conditions do not necessarily reflect the observed global climatic trends

Acupuncture in acute herpes zoster pain therapy (ACUZoster) - design and protocol of a randomised controlled trial

Background: Acute herpes zoster is a prevalent condition. One of its major symptoms is pain, which can highly influence patient's quality of life. Pain therapy is limited. Acupuncture is supposed to soften neuropathic pain conditions and might therefore act as a therapeutic alternative. Objective of the present study is to investigate whether a 4 week semi-standardised acupuncture is non-inferior to sham laser acupuncture and the anticonvulsive drug gabapentine in the treatment of pain associated with herpes zoster. Methods/Design: Three-armed, randomised, placebo-controlled trial with a total follow-up time of 6 months. Up to estimated 336 patients (interim analyses) with acute herpes zoster pain (VAS > 30 mm) will be randomised to one of three groups (a) semi-standardised acupuncture (168 patients); (b) gabapentine with individualised dosage between 900-3600 mg/d (84 patients); (c) sham laser acupuncture. Intervention takes place over 4 weeks, all patients will receive analgesic therapy (non-opioid analgesics: metamizol or paracetamol and opioids: tramadol or morphine). Therapy phase includes 4 weeks in which group (a) and (c) consist of 12 sessions per patient, (b) visits depend on patients needs. Main outcome measure is to assess the alteration of pain intensity before and 1 week after treatment sessions (visual analogue scale VAS 0-100 mm). Secondary outcome measure are: alteration of pain intensity and frequency of pain attacks; alteration of different aspects of pain evaluated by standardised pain questionnaires (NPI, PDI, SES); effects on quality of life (SF 36); analgesic demand; alteration of sensoric perception by systematic quantitative sensory testing (QST); incidence of postherpetic neuralgia; side effects and cost effectiveness. Credibility of treatments will be assessed. Discussion: This study is the first large-scale randomised placebo controlled trial to evaluate the efficacy of acupuncture compared to gabapentine and sham treatment and will provide valuable new information about the clinical and physiological effects of acupuncture and gabapentine in the treatment of acute herpes zoster pain. The study has been pragmatically designed to ensure that the study findings can be implemented into clinical practice if acupuncture can be shown to be an effective treatment strategy in acute herpes zoster pain

Agent-based simulations for protecting nursing homes with prevention and vaccination strategies

Due to its high lethality amongst the elderly, the safety of nursing homes has been of central importance during the COVID-19 pandemic. With test procedures becoming available at scale, such as antigen or RT-LAMP tests, and increasing availability of vaccinations, nursing homes might be able to safely relax prohibitory measures while controlling the spread of infections (meaning an average of one or less secondary infections per index case). Here, we develop a detailed agent-based epidemiological model for the spread of SARS-CoV-2 in nursing homes to identify optimal prevention strategies. The model is microscopically calibrated to high-resolution data from nursing homes in Austria, including detailed social contact networks and information on past outbreaks. We find that the effectiveness of mitigation testing depends critically on the timespan between test and test result, the detection threshold of the viral load for the test to give a positive result, and the screening frequencies of residents and employees. Under realistic conditions and in absence of an effective vaccine, we find that preventive screening of employees only might be sufficient to control outbreaks in nursing homes, provided that turnover times and detection thresholds of the tests are low enough. If vaccines that are moderately effective against infection and transmission are available, control is achieved if 80% or more of the inhabitants are vaccinated, even if no preventive testing is in place and residents are allowed to have visitors. Since these results strongly depend on vaccine efficacy against infection, retention of testing infrastructures, regular voluntary screening and sequencing of virus genomes is advised to enable early identification of new variants of concern.Comment: Supplementary material is included in the manuscript PD