Flux-corrected dispersion-improved CABARET schemes for linear and nonlinear wave propagation problems

The new two-time-level dispersion improved CABARET scheme is developed as an upgrade of the original CABARET for improved wave propagation modelling in multiple dimensions and for nonlinear conservation laws including gas dynamics. The new upgrade retains many attractive features of the original CABARET scheme such as shock-capturing and low dissipation. It is simple for implementation in the existing CABARET codes and leads to a greater accuracy for solving linear wave propagation problems. A non-linear version of the dispersion-improved CABARET scheme is introduced to efficiently deal with contact discontinuities and shocks. The properties of the new linear and nonlinear CABARET schemes are analysed for numerical dissipation and dispersion error based on Von Neumann analysis and Pirrozolli's method. Numerical examples for one-dimensional and two-dimensional linear advection, the one-dimensional inviscid Burger's equation, and the isothermal gas dynamics problems in one and two dimensions are presented

Zonal jets in the Southern Ocean: a semi-analytical model based on scale separation

A reduced-order semi-analytic model of multiple zonal jets in the Southern Ocean is proposed based on the statistical approach and scale decomposition. By introducing two dominant scales in the vorticity equation, the model describes the large-scale and mesoscale dynamics using the explicit momentum dissipation in the horizontal and vertical directions. For validation and physical insights, the results of the reduced-order model are compared with solutions of two eddy-resolving ocean models: i) a realistic primitive-equation HYCOM (HYbrid Coordinate Ocean Model) simulation of the Southern Ocean and ii) an idealized quasi-geostrophic model of a shear-driven channel flow

Excitation of the Earth's Chandler wobble by a turbulent oceanic double-gyre

We develop a layer-averaged, multiple-scale spectral ocean model and show how an oceanic double-gyre can communicate with the Earth's Chandler wobble. The overall transfers of energy and angular momentum from the double-gyre to the Chandler wobble are used to calibrate the turbulence parameters of the layer-averaged model. Our model is tested against a multilayer quasi-geostrophic ocean model in turbulent regime, and base states used in parameter identification are obtained from mesoscale eddy resolving numerical simulations. The Chandler wobble excitation function obtained from the model predicts a small role of North Atlantic ocean region on the wobble dynamics as compared to all oceans, in agreement with the existing observations

Fast spectral solutions of the double-gyre problem in a turbulent flow regime

Several semi-analytical models are considered for a double-gyre problem in a turbulent flow regime for which a reference fully numerical eddy-resolving solution is obtained. The semi-analytical models correspond to solving the depth-averaged Navier–Stokes equations using the spectral Galerkin approach. The robustness of the linear and Smagorinsky eddy-viscosity models for turbulent diffusion approximation is investigated. To capture essential properties of the double-gyre configuration, such as the integral kinetic energy, the integral angular momentum, and the jet mean-flow distribution, an improved semi-analytical model is suggested that is inspired by the idea of scale decomposition between the jet and the surrounding flow

Statistical analysis of high-speed jet flows

The spatiotemporal dynamics of pressure fluctuations of a turbulent jet flow is examined from the viewpoints of symbolic permutations theory and Kolmogorov-Smirnov statistics. The methods are applied to unveil hidden structures in the near-field of the two jets corresponding to the NASA SHJAR SP3 and SP7 experiments. Large Eddy Simulations (LES) are performed using the high-resolution Compact Accurately Boundary-Adjusting high-REsolution Technique (CABARET) accelerated on Graphics Processing Units (GPUs). It is demonstrated that the decomposition of the LES pressure solutions into symbolic patterns of simpler temporal structure reveals the existence of some orderly structures in the jet flows. To separate the non-linear dynamics of the revealed structures from the linear part, the results based on the pressure signals obtained from LES are compared with the surrogate dataset constructed from the original data

Application of Genetic Programming and Artificial Neural Network Approaches for Reconstruction of Turbulent Jet Flow Fields

Two Machine Learning (ML) methods are considered for reconstruction of turbulet signals corresponding to the Large Eddy Simulation database obtained by application of the high-resolution CABARET method accelerated on GPU cards for flow solutions of NASA Small Hot Jet Acoustic Rig (SHJAR) jets. The first method is the Feedforward Neural Networks technique, which was successfully implemented for a turbulent flow over a plunging aerofoil in (Lui and Wolf, 2019). The second method is based on the application of Genetic Programming, which is well-known in optimisation research, but has not been applied for turbulent flow reconstruction before. The reconstruction of local flow velocity and pressure signals as well as timedependent principle coefficients of the Spectral Proper Orthogonal Decomposition of turbulent pressure fluctuations are considered. Stability and dependency of the ML algorithms on the smoothness property and the sampling rate of the underlying turbulent flow signals are discussed

Usefulness of nabilone as an antiemetic in persistent vomiting due to refractory gastrointestinal disorders

Nabilone, a synthetic analogue of delta-9-Tetrahydrocannabinol, is an agonist of cannabinoid receptors (CB-1 and CB-2) approved to treat chemotherapy-induced vomiting refractory to antiemetics. Its use in patients with refractory vomiting due to gastrointestinal dysmotility (GID) has not been reported. Our study aims are to assess nabilone usefulness and side-effects in patients with refractory vomiting due to GID. Patients prescribed nabilone at St. Mark's intestinal rehabilitation unit (January 2017 to September 2022) due to GID vomiting have been retrospectively reviewed. Descriptive analysis has been done. Variables measured: age, sex, comorbidities, antiemetics/prokinetics, enteral or parenteral nutrition, nabilone prescription, subjective symptom improvement and side-effects. Seven patients received nabilone. 5/7 (72%) were females. Median age:25 years (23-37). 3/7 (43%) had gastroparesis (1/3 related to postural orthostatic tachycardia syndrome -POTS- , 1/3 to Ehlers-Danlos' Syndrome, POTS, Crohn's Disease and adrenal insufficiency -AI- and 1/3 to sinus node ablation and AI), 2/7 (29%) had gastroparesis and intestinal dysmotility (1/2 related to POTS and 1/2 related to EDS and other connective tissue diseases) and 2/7 (29%) had intestinal dysmotility (1/2 because of polyglucosan body visceral myopathy and 1/2 to intestinal surgery). All patients had received antiemetics or prokinetics before (median of 5 drugs; 2-11). 1/7 (14%) received enteral supplements, 5/7 (72%) enteral nutrition through enteral tubes and 4/7 (57%) parenteral nutrition. 5/7 (72%) patients received 1mg of nabilone bd orally, 1/7 (14%) 2 mg bd through jejunostomy and 1/7 (14%) started nabilone at 2 mg bd orally, but had to be switched to 1 mg bd because of side-effects. The median treatment's duration was 9 days (7-35). Regarding the efficacy of nabilone, 3/7 (43%) had symptomatic improvement. In terms of side-effects 4/7 (57%) patients reported some incidence under the treatment such as headache, light-headedness, drowsiness, dizziness or hallucinations. Patients with refractory GID vomiting despite multiple anti-sickness are difficult to treat. Nabilone improved symptoms in almost half of the patients although adverse effects appeared in more than 50%. Doses higher than 1 mg bd po did not show benefit. Although our study has important limitations, nabilone might be a temporary measure in these patients. Side-effects should be taken into consideration

A randomized controlled multimodal behavioral intervention trial for improving antiepileptic drug adherence

Purpose: Medication nonadherence is one of the most important reasons for treatment failure in patients with epilepsy. The present study investigated the effectiveness of a multicomponent intervention to improve adherence to antiepileptic drug (AED) medication in patients with epilepsy. Methods: In a prospective, randomizedmulticenter trial, three sessions of face-to-facemotivational interviewing (MI) in combination with complementary behavior change techniques were compared with standard care.Motivational interviewing prompted change talk and self-motivated statements from the patients, planning their own medication intake regimen and also identifying and overcoming barriers thatmay prevent adherence. Participants were provided with calendars to self-monitor their medication taking behavior. A family member and the health-care teamwere invited to attend the last session ofMI in order to improve the collaboration and communication between patients, their caregiver or family member, and their health-care provider. At baseline and 6-month follow-up, psychosocial variables and medical adherence were assessed. Results: In total, 275 participantswere included in the study. Comparedwith the active control group, patients in the intervention group reported significantly highermedication adherence, aswell as stronger intention and perceptions of control for taking medication regularly. The intervention group also reported higher levels of action planning, coping planning, self-monitoring, and lower medication concerns. Conclusions: This study shows that MI can be effective in clinical practice to improvemedication adherence in patientswith epilepsy. It also provides evidence that combining volitional interventions, including action planning, coping planning, and self-monitoring withmotivational interviewing can promote the effectiveness of the medical treatments for epilepsy by improving adherenc