Comparative study of two atomic layer etching processes for GaN

International audienceAtomic layer etching (ALE) of Ga-polar GaN (0001) using a standard inductively coupled plasma-reactive ion etching system is achieved in this work. The sequential process is using Cl2 to modify the surface in the adsorption step. For the activation step, the authors compare two rare gas plasmas, namely, Ar and Kr, and show a much larger and well-defined ALE window for the latter. The ALE of GaN is demonstrated by etching mesa structures masked with a photoresist. A constant etching rate per cycle of two monolayers is obtained. The experimental conditions of this self-limited process are found by changing both the adsorption and activation times, together with the source power. This provides an atomic-scale process for nanofabrication, with significant improvements to the GaN surface

Effectiveness of human papillomavirus vaccination in young Japanese women: a retrospective multi-municipality study

In Japan, government support for human papillomavirus (HPV) vaccination began in November 2010. However, the mass media repeatedly reported on severe adverse events. The Japanese Ministry of Health, Labor and Welfare suspended proactive recommendations for HPV vaccines in June 2013. Japan’s HPV vaccination rate dropped from 70% to less than 1% in 2017. We examined cervical cancer screening results in terms of abnormal cytology, histology, and HPV vaccination status among 11,903 women aged 20 to 25 y in the fiscal year 2015. The overall rate of HPV vaccination was 26.1% (3,112/11,903). Regarding cytology, the rate of atypical squamous cells of undetermined significance (ASC-US) or worse was 3.3% (103/3,112) in women who received HPV vaccination (vaccine (+) women) and 5.6% (496/8,791) in women who did not (vaccine (-) women). The rate of high-grade squamous intraepithelial lesion (HSIL) or worse was 0.26% (8/3,112) in vaccine (+) women and 0.81% (72/8,791) in vaccine (-) women. Regarding histology, the rate of cervical intraepithelial neoplasia 1 or worse (CIN1+) was 1.4% (42/3,112) in vaccine (+) women and 2.1% (178/8,791) in vaccine (-) women. The rates of CIN2+ and CIN3+ were similar regardless of vaccination. We found a significantly lower incidence of CIN in vaccine (+) women. These results suggest that the resumption of recommending HPV vaccination as primary prevention for cervical cancer is needed in Japan

National trends in the outcomes of subarachnoid haemorrhage and the prognostic influence of stroke centre capability in Japan: retrospective cohort study

Objectives To examine the national, 6-year trends in in-hospital clinical outcomes of patients with subarachnoid haemorrhage (SAH) who underwent clipping or coiling and the prognostic influence of temporal trends in the Comprehensive Stroke Center (CSC) capabilities on patient outcomes in Japan.Design Retrospective study.Setting Six hundred and thirty-one primary care institutions in Japan.Participants Forty-five thousand and eleven patients with SAH who were urgently hospitalised, identified using the J-ASPECT Diagnosis Procedure Combination database.Primary and secondary outcome measures Annual number of patients with SAH who remained untreated, or who received clipping or coiling, in-hospital mortality and poor functional outcomes (modified Rankin Scale: 3–6) at discharge. Each CSC was assessed using a validated scoring system (CSC score: 1–25 points).Results In the overall cohort, in-hospital mortality decreased (year for trend, OR (95% CI): 0.97 (0.96 to 0.99)), while the proportion of poor functional outcomes remained unchanged (1.00 (0.98 to 1.02)). The proportion of patients who underwent clipping gradually decreased from 46.6% to 38.5%, while that of those who received coiling and those left untreated gradually increased from 16.9% to 22.6% and 35.4% to 38%, respectively. In-hospital mortality of coiled (0.94 (0.89 to 0.98)) and untreated (0.93 (0.90 to 0.96)) patients decreased, whereas that of clipped patients remained stable. CSC score improvement was associated with increased use of coiling (per 1-point increase, 1.14 (1.08 to 1.20)) but not with short-term patient outcomes regardless of treatment modality.Conclusions The 6-year trends indicated lower in-hospital mortality for patients with SAH (attributable to better outcomes), increased use of coiling and multidisciplinary care for untreated patients. Further increasing CSC capabilities may improve overall outcomes, mainly by increasing the use of coiling. Additional studies are necessary to determine the effect of confounders such as aneurysm complexity on outcomes of clipped patients in the modern endovascular era