Impaired Health-Related Quality of Life in Adolescent Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: The Impact of Core Symptoms

Objective: The objectives of this study were to compare the health-related quality of life (HRQOL) of a North American population of adolescents and young adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to (1) healthy controls (HC), (2) adolescents with ME/CFS in other countries, and (3) other forms of pediatric chronic illness, and (4) to examine the influence of the core illness symptoms in the Institute of Medicine (IOM) case definition on impaired HRQOL.Study design: Cross-sectional study comparing individuals with ME/CFS referred to a tertiary care Chronic Fatigue clinic and HC. Eligible participants were age 10–30 years and met the Fukuda criteria for CFS. HC were eligible if they were age 10–30 years, with self-reported good, very good, or excellent general health. Pediatric HRQOL was measured using the PedsQL (Pediatric Quality of Life Inventory) and other validated instruments.Results: We enrolled 55 consecutive ME/CFS patients (46 F) aged 10–23 years. From a pool of 69 potential HC we selected 55 with similar age and gender distribution for comparison. The total and subscale scores on the PedsQL and on all other measures of HRQOL indicated significantly worse function among those with ME/CFS (all P < 0.001). The self-reported frequency of post-exertional malaise (PEM) was significantly associated with the severity of impaired HRQOL (P < 0.001). Cognitive impairment had a weaker association with the PedsQL score (P = 0.02). Orthostatic intolerance was present in 96% of the ME/CFS population. Of the 55 who satisfied the Fukuda criteria, 47 (85%) also satisfied the IOM criteria for the diagnosis. Those meeting the IOM criteria had worse PedsQL total scores than those meeting just the Fukuda criteria (P < 0.001).Conclusions: HRQOL was substantially lower in an ambulatory population of adolescents and young adults with ME/CFS than for healthy controls in North America, consistent with reports from other continents. HRQOL was also lower in ME/CFS than has been described in children with asthma, diabetes mellitus, epilepsy, eosinophilic gastroenteritis, and cystic fibrosis. The findings of this study lend further support to the inclusion of PEM, cognitive impairment, and orthostatic intolerance as core symptoms of pediatric ME/CFS

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Suitability of parameters and models in the discrete element method for simulation of mesoscale powder indentation experiments

The Discrete Element Method (DEM) has been shown in the literature to be able to match the resultsof certain experimental powder process such as shear cell and angle of repose tests. In this work wetry to discover which models and parameters are required by the DEM to simulate a mesoscale process.This work compares 2D and 3D simulations, linear and Hertzian stiffness models, friction and cohesionand several values of stiffness parameter. Using 3D models with friction and higher stiffness valuesproduced the most similar behavior to the experiments. Spectral results show the scales of the particlerearrangements were reproduced by the DEM and independent of parameters and models considered in this work

Performance of numerical integrators on tangential motion of DEM within implicit flow solvers

This study examines the behaviour of continuous time integration schemes over discontinuities in the tangential forces typical in an oblique impact within a Discrete Element Simulation (DEM). High order schemes are associated low error and efficient computation, however, for DEM this is not always the case. The simulations consist of a particle impacting tangentially with a plane and sliding along it, this makes the numerical integration independent of errors from the normal force integration. Three possible force regimes that occur in the tangential motion of an oblique impact are explored; frictional, elastic and elastic-to-frictional. Tests are conducted to explore the effects of the location of the discontinuity within the time step and to examine scheme order through varying time step resolution. For certain scenarios the tangential motion contains elastic and then frictional forces, this presents a second discontinuity between these force regimes. The effects of this second discontinuity are also presented. It was found that all schemes were limited to 1st order by at least one of the conditions tested. The Symplectic Euler is recommended as it is found to be of generally higher accuracy than other 1st order schemes in these tests, as was found in a similar study regarding normal impact

Tanacetum vulgare as a bioindicator of trace-metal contamination: A study of a naturally colonized open-pit lignite mine

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