Evaluation of the Abel inversion integral in O-mode plasma reflectometry using Chebyshev-Gauss quadrature

The Abel transform is often used to reconstruct plasma density profiles from O-Mode polarized reflectometry diagnostics. However, standard numerical trapezoidal evaluation of the Abel inversion integral can be computationally expensive for a large number of evaluation points, and an endpoint singularity exists on the upper-bound of the integral, which can result in an increased error. In this work, Chebyshev-Gauss quadrature is introduced as a new method to evaluate the Abel inversion integral for the problem of O-Mode plasma reflectometry. The method does not require numerical evaluation of an integral singularity and is shown to have similar accuracy compared to existing methods while being computationally efficient.

Obesity and gambling: neurocognitive and clinical associations

OBJECTIVE

Research on health correlates in gamblers has found an association between gambling and obesity. The neurocognitive underpinnings of impulsivity may be useful targets for understanding and ultimately treating individuals with both gambling and obesity problems.

METHOD

207 non-treatment seeking young adults (18-29 years) with subsyndromal gambling disorder were recruited from the community. Subjects were grouped according to weight ('normal weight' BMI<25, 'overweight' BMI≥25; or 'obese' BMI≥30). Measures relating to gambling behaviour and objective computerized neurocognitive measures were collected.

RESULTS

Of the 207 subjects, 22 (10.6%) were obese and 49 (23.7%) were overweight. The obese gamblers consumed more nicotine (packs per day equivalent) and reported losing more money per week to gambling. Obese gamblers exhibited significant impairments in terms of reaction times for go trials on the stop-signal test (SST), quality of decision making and risk adjustment on the Cambridge Gamble Test (CGT), and sustained attention on the rapid visual information processing task (RVP).

CONCLUSION

Obesity was associated with decision making and sustained attention impairments in gamblers, along with greater monetary loss due to gambling. Future work should use longitudinal designs to examine the temporal relationship between these deficits, weight, other impulsive behaviour, and functional impairment.