Evaluation and development of non-reflective boundary conditions for aeroacoustic simulations

The performance of several non-reflective acoustic boundary conditions is quantitatively compared using a plane wave test configuration. The study uses a high-order linearized Euler equation solver to find a non-reflective boundary condition which gives good performance in a variety of cases. The performance for acoustic waves with varying frequency and incident angle is compared in flows with varying Mach number. The performance of buffer zone, far-field, and characteristic non-reflective methods is compared. Some non-reflective boundary methods, such as buffer zones, contain tuneable parameters that are optimized in the current work. This provides a more comprehensive evaluation than previous studies which used constant values of the tuneable parameters. A new generic non-reflective zonal characteristic boundary condition is proposed and is shown to give improved performance in comparison to other tested methods. The performance of the proposed boundary condition is also demonstrated in a two-dimensional airfoil turbulence-interaction case that includes vortical waves leaving the domain, and in a three-dimensional duct mode case

A Hybrid Sequencing Approach Completes the Genome Sequence of Thermoanaerobacter ethanolicus JW 200

Thermoanaerobacter ethanolicus JW 200 has been identified as a potential sustainable biofuel producer due to its ability to readily ferment carbohydrates to ethanol. A hybrid sequencing approach, combining Oxford Nanopore and Illumina DNA sequence reads, was applied to produce a single contiguous genome sequence of 2,911,280 bp

El Niño and the delayed action oscillator

We study the dynamics of the El Niño phenomenon using the mathematical model of delayedaction oscillator (DAO). Topics such as the influence of the annual cycle, global warming, stochastic influences due to weather conditions and even off-equatorial heat-sinks can all be discussed using only modest analytical and numerical resources. Thus the DAO allows for a pedagogical introduction to the science of El Niño and La Niña while at the same time avoiding the need for large-scale computing resources normally associated with much more sophisticated coupled atmosphere-ocean general circulation models. It is an approach which is ideally suited for student projects both at high school and undergraduate level

Self-consistent solutions of canonical proper self-gravitating quantum systems

Generic self-gravitating quantum solutions that are not critically dependent on the specifics of microscopic interactions are presented. The solutions incorporate curvature effects, are consistent with the universality of gravity, and have appropriate correspondence with Newtonian gravitation. The results are consistent with known experimental results that indicate the maintenance of the quantum coherence of gravitating systems, as expected through the equivalence principle.Comment: 13 pages, 7 figure

Balloon dilatation of the eustachian tube for obstructive eustachian tube dysfunction in adults

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To evaluate the effects of balloon dilatation of the Eustachian tube in adults with obstructive Eustachian tube dysfunction

Synthetic turbulence methods for leading edge noise predictions

An advanced digital filter method to generate synthetic turbulence is presented for efficient two- and three-dimensional leading edge noise predictions. The technique, which is based on the Random Particle-Mesh method, produces a turbulent inflow that matches a target isotropic energy spectrum. The discretized equations for the synthetic eddies, and the input parameters needed to recover the desired turbulence statistics, are presented. Moreover, a simple and fast implementation strategy, which does not require an additional boundary condition, is presented under the frozen turbulence assumption. The method is used in a linearized Euler solver to predict turbulence-airfoil interaction noise from a number of configurations, including variations in airfoil thickness, angle of attack and Mach number. For the first time, noise predictions from a digital filter method are directly compared to those provided by synthetic turbulence based on a summation of Fourier modes. The comparison indicates that the advanced digital filter method gives enhanced performance in terms of computational cost and simulation accuracy. In addition, initial tests show that this method is capable of reproducing experimental noise measurements within 3 dB accuracy

Non-locking screw insertion:No benefit seen if tightness exceeds 80% of the maximum torque

Screws are the most commonly used orthopaedic implant, however they are frequently overtightened when inserted. Using screw, bone and screw hole characteristics, maximum torque for a screw hole is predicted prior to insertion. Using this, optimum tightness as a percentage of the maximum torque is investigated as functions of compression and pullout forces. This data set provides the raw data for these investigations. The methodology is described in detail in the related manuscript: Fletcher, J., Ehrhardt, B., MacLeod, A., Whitehouse, M., Gill, H. & Preatoni, E. 2019. Non-locking screw insertion: No benefit seen if tightness exceeds 80% of the maximum torque. Clinical Biomechanics. https://doi.org/10.1016/j.clinbiomech.2019.07.009Biomechanical testing using juvenile bovine bone'R' software, v3.3.3 (R: A language and environment for statistical computing. R Foundation for Statistical Computing)

Design of optimal Earth pole-sitter transfers using low thrust propulsion

Recent studies have shown the feasibility of an Earth pole-sitter mission using low-thrust propulsion. This mission concept involves a spacecraft following the Earth's polar axis to have a continuous, hemispherical view of one of the Earth's poles. Such a view will enhance future Earth observation and telecommunications for high latitude and polar regions. To assess the accessibility of the pole-sitter orbit, this paper investigates optimum Earth pole-sitter transfers employing low-thrust propulsion. A launch from low Earth orbit (LEO) by a Soyuz Fregat upper stage is assumed after which a solar-electric-propulsion thruster transfers the spacecraft to the pole-sitter orbit. The objective is to minimise the mass in LEO for a given spacecraft mass to be inserted into the pole-sitter orbit. The results are compared with a ballistic transfer that exploits the manifolds winding off the pole-sitter orbit. It is shown that, with respect to the ballistic case, low-thrust propulsion can achieve significant mass savings in excess of 200 kg for a pole-sitter spacecraft of 1000 kg upon insertion. To finally obtain a full low-thrust transfer from LEO up to the pole-sitter orbit, the Fregat launch is replaced by a low-thrust, minimum time spiral through an orbital averaging technique, which provides further mass savings, but at the cost of an increased time of flight

A data-driven classification of outcome behaviors in those who cause concern to British public figures

Fixated individuals pose a significant threat to public figures. Previous research compares individuals labeled ‘approachers’ to those labeled ‘communicators.’ Typically, such studies compare a number of risk factors among the two groups to identify significant differences. This has impactful implications for the threat assessment and management of the pathologically fixated. The present study builds upon this established body of work by considering if more nuance can be disaggregated from a universe of cases referred to the Fixated Threat Assessment Center (FTAC). FTAC is a joint police and mental health unit in the U.K. which applies a public health approach to managing the pathologically fixated. The present study takes a deductive approach to detect profiles of cases from the data. First, we use cluster analysis to detect unmeasured subgroups of concerning behavior in the case files of 2,118 referrals to FTAC. We identify 5 patterns of concerning behavior: incoherent offline communicators, incoherent online communicators, angry/abusive communicators, concerning approachers, and problematic approachers. Second, we examine the rate of diagnosed mental disorder, the nature of concerns evoked, and case management actions taken among each of the five profiles identified. We conclude by highlighting how our results could inform triaging large volumes of cases, the allocation of limited resources, and more generally, how the success of the FTAC model has relevance across the management of grievance-fueled violence in general. (PsycInfo Database Record (c) 2021 APA, all rights reserved

Predictors of varying levels of risks posed by fixated individuals to British public figures

Concerning approaches and communications to the Royal Family and other British public figures are relatively numerous. This paper examines over 2000 such cases logged over a three-year period in the United Kingdom. Using police and health data, the paper conducts a series of bivariate and multivariate analyses to demonstrate the predictors of what types of risk are posed by an individual case (e.g., communicate only, approach, security breach). The results showed that (a) the rates of serious mental disorders are higher among this sample than the general population base rate, (b) approachers were significantly more likely than communicators to suffer from serious mental disorders, (c) approachers were significantly more likely than communicators to have a history of substance use and abuse problems, (d) approachers were significantly more likely than communicators to have a history of violent behavior against property and persons, and (e) the motivations of approachers and communicators significantly differ. The paper concludes with a consideration of the implications for threat assessment and management