High-fidelity inference of local impurity profiles in C-2W using Bayesian tomography

In C-2W (also called "Norman") [1], beam-driven field reversed configuration plasmas embedded in a magnetic mirror are produced and sustained in a steady state. A multi-chord passive Doppler spectroscopy diagnostic provides line-integrated impurity emission measurements near the center plane of the confinement vessel with fast time resolution. The high degree of plasma non-uniformity across optical sightlines can preclude direct fitting of the measured line-integrated spectra. To overcome this challenge, local impurity profiles are inferred using Bayesian tomography, a superior analysis technique based on a complete forward model of the diagnostic. The measured emission of O⁴⁺ triplet lines near 278.4 nm is modeled assuming two independent populations: thermal and beam ions. Gaussian processes are used to generate and infer local profiles. The inference incorporates details of the geometrical arrangement of the diagnostic, instrument function, intensity calibration, and a noise model. Markov chain Monte Carlo (MCMC) sampling of the posterior distribution of solutions provides high-fidelity uncertainty estimates. The reconstructed O⁴⁺ impurity profiles are consistent with data from other diagnostics and show good agreement with expected physics based on previously developed models of biasing circuit and impurity transport.

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Measurements of impurity ion temperature and velocity distributions via active charge-exchange recombination spectroscopy in C-2W

In TAE Technologies' C-2W experiment, electrode biasing is utilized for boundary control of a field-reversed configuration (FRC) plasma embedded in a magnetic mirror. Understanding the underlying physics associated with FRC rotation, stabilization, and heating is crucial for improving machine performance. Impurity ion rotation and temperature are sensitive to biasing effects, and measurements of these quantities can provide insight into important plasma dynamics and overall effectiveness of the biasing system. To this end, a charge-exchange recombination spectroscopy (ChERS) diagnostic was developed and deployed to measure local impurity ion temperature and velocity in the confinement vessel of C-2W. The system utilizes a new diagnostic neutral beam (40 keV, 8.5 A) and a fiber-coupled spectrometer with an image-intensified high-speed camera to measure beam-induced spectral line emission at multiple lines-of-sight. Design details and the first experimental results obtained with this new diagnostic are presented and discussed.

Comprehensive imaging of C-2W plasmas: Instruments and applications

The C-2W device ("Norman") [Gota et al., Nucl. Fusion 59, 112009 (2019)] has produced and sustained beam-driven field-reversed configuration (FRC) plasmas embedded in a magnetic mirror geometry using neutral beams and end-bias electrodes located in expander divertors. Several discrete vessels comprise this device, and many imaging instruments are required in order to view the plasma throughout. To meet this need, a suite of spatially and radiometrically calibrated, high-speed camera systems have been deployed. Besides global visualization of the plasma evolution and macro-stability, this imaging suite has been used in a variety of applications. One example application is a tomographic reconstruction of passive impurity emission. Calculation of the magnetic field in the equilibrium vessel is complicated by eddy currents in conducting structures and internal currents in the high-β FRC plasma. In addition, thus far non-perturbative measurements of internal field have not been available. The tomographic reconstruction of O⁴⁺ impurity emission enables an independent visualization of the plasma geometry, serving as a check on magnetic modeling and indirect evidence for field reversal within the FRC. A second application uses the cameras to view the Balmer-α emission throughout the plasma in order to estimate the ionization rate in each region. These rates can then be incorporated into particle balance calculations and a circuit model for currents from the end-bias electrodes. Finally, arcing on the electrode surfaces is identified through automated image processing of carefully selected spectral line emission.

Prolonged oral coenzyme Q10-β-cyclodextrin supplementation increases skeletal muscle complex I+III activity in young Thoroughbreds

Coenzyme Q10 (CoQ10) is an essential component of the mitochondrial electron transport chain (ETC). Decreased skeletal muscle CoQ10 content may result in decreased ETC activity and energy production. This study tested the hypotheses that supplementation with oral CoQ10 will increase plasma CoQ10 concentrations and that prolonged supplementation will increase skeletal muscle CoQ10 content in young, healthy untrained Thoroughbreds. Nineteen Thoroughbreds (27.5±9.7 months old; 11 males, eight females) from one farm and maintained on a grass pasture with one grain meal per day were supplemented daily with 1.5 mg/kg body weight of an oral CoQ10-β-cyclodextrin inclusion complex. Whole-blood and skeletal muscle biopsies were collected before (T0) and after (T1) nine weeks of supplementation. Plasma CoQ10 concentrations were determined via high-performance liquid chromatography. Skeletal muscle mitochondrial ETC combined complex I+III enzyme activity (indirect measurement of CoQ10 content) was assessed spectrophotometrically and normalised to mitochondrial abundance. Horses accepted supplementation with no adverse effects. Plasma CoQ10 concentration increased in all horses following supplementation, with mean plasma CoQ10 concentration significantly increasing from T0 to T1 (0.13±0.02 vs 0.25±0.03 μg/ml; mean difference 0.12±0.03; P=0.004). However, variability in absorbance resulted in a 58% response rate (i.e. doubling of T1 above T0 values). The mean skeletal muscle complex I+III activity significantly increased from T0 to T1 (0.36±0.04 vs 0.59±0.05 pmol/min/mg of muscle, mean difference 0.23±0.05; P=0.0004), although T1 values for three out of 19 horses decreased on average by 23% below T0 values. In conclusion, oral supplementation with CoQ10 in the diet of young, healthy untrained Thoroughbreds increased mean plasma CoQ10 concentration by 99% with prolonged daily supplementation increasing mean skeletal muscle complex I+III activity by 65%. Additional research is warranted investigating training and exercise effects on skeletal muscle CoQ10 content in CoQ10 supplemented and un-supplemented Thoroughbreds.

P339 Gradient adjusted cardiac power index does not improve prediction of survival post transcatheter aortic valve replacement compared to cardiac power index alone

Funding Acknowledgements

None

Background

Cardiac Power Index (CPI) is an integrative hemodynamic measure of cardiac pumping capability and is the product of the simultaneously measured mean arterial pressure (MAP) and cardiac output (CO). In patients with aortic stenosis (AS), MAP is not reflective of mean systolic left ventricular (LV) pressure due to the transvalvular gradient. Non-invasive assessment of mean systolic LV pressure is challenging in severe aortic stenosis. CPI assessed using systemic MAP was previously shown to predict survival post transcatheter aortic valve replacement (TAVR).

Purpose

We evaluated the utility of a gradient adjusted CPI in predicting survival post TAVR compared to CPI alone

Methods

A retrospective study was performed including patients undergoing TAVR with 1 year follow-up. Baseline demographics, clinical, and echocardiographic data were abstracted from a cohort of 1,011 patients. CPI was calculated, (CO x MAP)/ (451 x BSA) Watts/m2. Gradient adjusted CPI was calculated using an augmented MAP i) adding aortic valve mean gradient(AVMG) to systolic blood pressure (CPI1); ii) adding aortic valve maximal instantaneous gradient to systolic blood pressure (CPI2) and iii) adding AVMG to MAP (CPI3). Patient survival score was calculated using a step up technique to identify the cut off value for CPI and gradient adjusted CPI to identify, where the maximum difference in mortality occurred. Multivariate cox-regression analysis was performed to adjust for baseline covariates. Receiver operator curves(ROC) for CPI and gradient adjusted CPI were calculated to predict survival post TAVR.

Results

The mortality rate at 1 yr was 16%. Mean age and AVMG of survivors was 81 +/- 9 yrs and 43 +/-14 mmHg vs 80 +/-9 yrs and 42 +/- 13 mmHg in the deceased group. Proportion of female patients was similar in both groups (p = 0.7). Patients in the deceased group at baseline had a higher prevalence of chronic lung disease, atrial fibrillation, heart failure within 2-weeks of procedure, higher STS-PROM score, lower serum albumin level, higher prevalence of moderate to severe tricuspid regurgitation, higher right ventricular systolic pressure and higher prevalence of dialysis. Both CPI and gradient adjusted CPI were independently associated with survival at 1 year. The area under ROC for CP, CP1, CP2 and CP3 were 0.67 (95% confidence interval [CI] 0.62 - 0.72), 0.65 (95% CI 0.60 – 0.70), 0.66 (95% CI 0.61 – 0.71) and 0.63 (95% CI 0.58 – 0.68) respectively.

Conclusion

Gradient adjusted CPI did not improve accuracy of predicting post TAVR survival at 1 year compared to CPI alone.

Abstract P339 Figure. Area under ROC

Impact of pharyngeal endoscopic tip placement and water flushing interval on upper respiratory tract disorders in horses undergoing overground endoscopy

BACKGROUND

Endoscopic tip placement in the pharynx and water flushing interval (FI) may affect exercising upper respiratory tract (URT) endoscopic results.

OBJECTIVES

To determine associations between the endoscopic tip position in the pharynx and automated FI with overground endoscopic (OGE) results.

STUDY DESIGN

Randomised balanced 2X5 factorial design.

METHODS

A total of n = 200 horses undergoing OGE were randomly assigned into 10 groups (n = 20/group) of different automated endoscopic FIs (no flushing, 60, 120, 180, 240 s) with the endoscope tip positioned either rostrally (position A) or caudally (position B) in the pharynx. Endoscopic videos were analysed and all URT abnormalities graded using published scales. Disorders with ≤10% prevalence were excluded from the final analysis with only arytenoid asymmetry at exercise (AAex), vocal fold collapse (VFC), palatal dysfunction (PD) and medial deviation of the aryepiglottic folds (MDAF) included. The association of endoscope position and FI with URT disorders was assessed using ordinal regression models with P≤0.05 significant.

RESULTS

Endoscope tip positioning was significantly associated with PD grading (P = 0.002), with 63/100 horses diagnosed with PD in position A and 45/100 in position B. No other significant direct associations between URT disease and endoscope tip position were identified, although interactions between exercise velocity and endoscope position affected MDAF grade. FI was not directly associated with alterations in disorder grading, although interactions between exercise velocity and FI appeared to affect MDAF grade.

MAIN LIMITATIONS

The same horse was not evaluated under each test condition potentially resulting in sample bias. Interactions between disorders were not evaluated. The sample size was insufficient to conclusively explore relationships between all factors and disorder grading.

CONCLUSIONS

Position of the endoscope tip within the pharynx appears to affect grading of PD during OGE examination. Exercise velocity may affect MDAF grade through interactions with endoscope position and FI.

Application of activated barrier hopping theory to viscoplastic modeling of glassy polymers

An established statistical mechanical theory of amorphous polymer deformation has been incorporated as a plastic mechanism into a constitutive model and applied to a range of polymer mechanical deformations. The temperature and rate dependence of the tensile yield of PVC, as reported in early studies, has been modeled to high levels of accuracy. Tensile experiments on PET reported here are analyzed similarly and good accuracy is also achieved. The frequently observed increase in the gradient of the plot of yield stress against logarithm of strain rate is an inherent feature of the constitutive model. The form of temperature dependence of the yield that is predicted by the model is found to give an accurate representation. The constitutive model is developed in two-dimensional form and implemented as a user-defined subroutine in the finite element package ABAQUS. This analysis is applied to the tensile experiments on PET, in some of which strain is localized in the form of shear bands and necks. These deformations are modeled with partial success, though adiabatic heating of the instability causes inaccuracies for this isothermal implementation of the model. The plastic mechanism has advantages over the Eyring process, is equally tractable, and presents no particular difficulties in implementation with finite elements.

The cost of systemic corticosteroid-induced morbidity in severe asthma: a health economic analysis

BACKGROUND

Treatment of severe asthma may include high dose systemic-steroid therapy which is associated with substantial additional morbidity. This study estimates the additional healthcare costs associated with steroid-induced morbidity by comparing three patients groups: those with severe asthma, moderate asthma and no asthma.

METHODS

Patients with severe asthma (n = 808, GINA step 5 treatment) were matched by age and gender with patients with mild/moderate asthma (n = 3,975, GINA step 2 and 3 treatment) and a non-asthma control cohort (with a diagnosis of rhinitis; n = 2,412) from the Optimum Patient Care Research Database (OPCRD), a nationally representative primary care database. Prescribed drugs and publicly funded healthcare activity were monetised and annual costs per patient estimated. Regression analyses were used to estimate the additional healthcare cost associated with steroid-induced morbidity.

RESULTS

Average healthcare costs per person per year range from £2603 - £4533 for the severe asthma cohort, to £978 - £2072 for the mild/moderate asthma cohort, to £560 - £1324 for the non-asthma control cohort, depending on the costing scenario. Differences in induced morbidity costs were evident between patients with asthma differentiated by steroid exposure. In relation to prescription drugs used to treat steroid-induced co-morbidities, females with severe asthma and high steroid exposure cost approximately £789 more per year than a corresponding female with no asthma, while males cost approximately £744 more than their counterparts with no asthma. Estimates were extrapolated to all healthcare costs.

CONCLUSIONS

This study provides the first robust estimates of the additional cost of healthcare related to steroid-induced morbidity relative to patients with no steroid exposure. The study will help inform use of steroid-sparing strategies in this patient group.

A Review of Potentially Inappropriate Prescribing in Over 65's in Livinghealth Clinic

Polypharmacy and potentially inappropriate prescribing (PIP) are areas of growing importance and concern. Optimising drug prescribing in older people is challenging and complex at,the individual GP level. At a national level it is an important public health issue for the care and management of the ageing Irish population. The aim of this study was to estimate the prevalence of PIP in Livinghealth Clinic using the STOPP (Screening Tool for Older Persons' Prescribing) criteria and to identify areas of PIP. LHC audits demonstrated PIP levels of between 16% and 29%. Our findings were similar to other studies in that proton pump inhibitors (PPIs) at maximum therapeutic dosage for >8 weeks, and long acting benzodiazepines prescribed for > 1 month, continue to be significant areas of PIP. However, not all identified PIP maybe inappropriate. The STOPP criteria are a useful screening tool for older persons' prescribing, but are best used together with clinical assessment and discretion.