Broadband shock-associated noise modelling for high-area-ratio under-expanded jets.

Broadband shock-associated noise (BBSAN) is an important component of supersonic jet noise for jets at off-design conditions when the pressure at the nozzle exit is different from the ambient. Two high-area-ratio under-expanded supersonic jets at nozzle pressure ratios (NPRs) 3.4 and 4.2 are considered. The jets correspond to conditions of the experiment in the Laboratory for Turbulence Research in Aerospace and Combustion (LTRAC) in the Supersonic Jet Facility of Monash University. Flow solutions are obtained by the large eddy simulation (LES) and Reynolds averaged Navier-Stokes (RANS) methods. The solutions are validated against the particle image velocimetry (PIV) data. For noise spectra predictions, the LES solution is combined with the time-domain Ffowcs Williams-Hawkings method. To probe the accuracy of the reduced-order method based on acoustic analogy, the RANS solutions are substituted in the Morris and Miller BBSAN method, where different options for modelling of the acoustic correlation scales are investigated. The noise spectra predictions are compared with the experimental data from the non-anechoic LTRAC facility and the NASA empirical sJet model. Apart from the low frequencies influenced by the jet mixing noise, the RANS-based acoustic predictions align with those from LES for most frequencies in the range of Strouhal numbers (St) 0.4 < St < 2 within 1-2 dB.

Clinical experience with a single-nucleotide polymorphism-based non-invasive prenatal test for five clinically significant microdeletions.

Single-nucleotide polymorphism (SNP)-based non-invasive prenatal testing (NIPT) can currently predict a subset of submicroscopic abnormalities associated with severe clinical manifestations. We retrospectively analyzed the performance of SNP-based NIPT in 80 449 referrals for 22q11.2 deletion syndrome and 42 326 referrals for 1p36, cri-du-chat, Prader-Willi, and Angelman microdeletion syndromes over a 1-year period, and compared the original screening protocol with a revision that reflexively sequenced high-risk calls at a higher depth of read. The prevalence of these microdeletion syndromes was also estimated in the referral population. The positive predictive value of the original test was 15.7% for 22q11.2 deletion syndrome, and 5.2% for the other 4 disorders combined. With the revised protocol, these values increased to 44.2% for 22q11.2 and 31.7% for the others. The 0.33% false-positive rate (FPR) for 22q11.2 deletion syndrome decreased to 0.07% with the revised protocol. Similarly, the FPR for the other 4 disorders combined decreased from 0.56% to 0.07%. Minimal prevalences were estimated to be 1 in 1255 for 22q11.2 deletion syndrome and 1 in 1464 for 1p36, cri-du-chat, and Angelman syndromes combined. Our results show that these microdeletions are relatively common in the referral population, and that the performance of SNP-based NIPT is improved with high-depth resequencing.

Denture identification marking should be standard practice.

The focus of this opinion article is to revisit whether denture identification marking should be routine and standard practice at manufacture in the United Kingdom. The benefits of denture identification marking are evident in the literature particularly for those who are in residential care or who will have to seek care due to dementia or physical frailty; however, within the UK it is not normally practised. Many patients would appear to be unaware of denture marking, but present positive attitudes towards it. Results of a survey of UK dental laboratories would indicate that the vast majority of them offer an inclusion denture marking service with a mean cost of £5 per denture. Is the lack of denture marking in the UK due to dental professionals having differences in opinion, lack of education of professionals in training or financial disincentives?