Real-Time Equilibrium Reconstruction in a Tokamak

This paper deals with the numerical reconstruction of the plasma current density in a Tokamak and of its equilibrium. The problem consists in the identification of a non-linear source in the 2D Grad-Shafranov equation, which governs the axisymmetric equilibrium of a plasma in a Tokamak. The experimental measurements that enable this identification are the magnetics on the vacuum vessel, but also polarimetric and interferometric measures on several chords, as well as motional Stark effect or pressure measurements. The reconstruction can be obtained in real-time using a finite element method, a non-linear fixed-point algorithm and a least-square optimization procedure

Relation of Secondhand Smoking to Mild Cognitive Impairment in Older Inpatients

Up to now, controversy still exists regarding the role of secondhand smoking (SHS) in developing cognitive impairment. This study aimed to evaluate the prevalence of SHS in hospitalized older patients with cognitive deficit, particularly in those with mild cognitive impairment (MCI). Smoking history was classified into four groups: never smokers, former-active smokers/no SHS, active smokers, and secondhand smokers, and cognitive function into three levels: normal cognition (C), MCI, and dementia. A total of 933 older subjects with diagnoses of MCI (n = 98), dementia (n = 124), or C (n = 711) were enrolled in this cross-sectional study. As expected, patients with dementia had significantly higher frequency of former-active smokers than cognitively normal. Moreover, patients with MCI showed a significantly higher frequency of active and secondhand smokers than patients with dementia or C. A smoking history is very frequent in older patients with dementia. Patients with MCI had even higher rate of exposure to active or secondhand smoking

Clinical differences among the elderly admitted to the emergency department for accidental or unexplained falls and syncope

It is difficult to distinguish unexplained falls (UFs) from accidental falls (AFs) or syncope in older people. This study was designed to compare patients referred to the emergency department (ED) for AFs, UFs or syncope. Data from a longitudinal study on adverse drug events diagnosed at the ED (ANCESTRAL-ED) in older people were analyzed in order to select cases of AF, syncope, or UF. A total of 724 patients (median age: 81.0 [65–105] years, 66.3% female) were consecutively admitted to the ED (403 AF, 210 syncope, and 111 UF). The number of psychotropic drugs was the only significant difference in patients with AF versus those with UF (odds ratio [OR] 1.44; 95% confidence interval 1.17–1.77). When comparing AF with syncope, female gender, musculoskeletal diseases, dementia, and systolic blood pressure >110 mmHg emerged as significantly associated with AF (OR 0.40 [0.27–0.58], 0.40 [0.24–0.68], 0.35 [0.14–0.82], and 0.31 [0.20–0.49], respectively), while valvulopathy and the number of antihypertensive drugs were significantly related to syncope (OR 2.51 [1.07–5.90] and 1.24 [1.07–1.44], respectively). Upon comparison of UF and syncope, the number of central nervous system drugs, female gender, musculoskeletal diseases, and SBP >110 mmHg were associated with UF (OR 0.65 [0.50–0.84], 0.52 [0.30–0.89], 0.40 [0.20–0.77], and 0.26 [0.13–0.55]), respectively. These results indicate specific differences, in terms of demographics, medical/pharmacological history, and vital signs, among older patients admitted to the ED for AF and syncope. UF was associated with higher use of psychotropic drugs than AF. Our findings could be helpful in supporting a proper diagnostic process when evaluating older patients after a fall

Current drive at plasma densities required for thermonuclear reactors

Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors

Corrigendum: Current drive at plasma densities required for thermonuclear reactors

Nature Communications 1: Article number: 55 (2010); Published: 10 August 2010; Updated:19 September 2013. In Fig. 3 of this Article, the colours of the blue and green curves were accidentally interchanged while the manuscript was being revised. In addition, the x axis labels on Fig. 4 should have read 'Frequency (MHz)'

Correlation analysis for energy losses, waiting times and durations of type I edge-localized modes in the Joint European Torus

Several important ELM control techniques are in large part motivated by the empirically observed inverse relationship between average ELM energy loss and ELM frequency in a plasma. However, to ensure a reliable effect on the energy released by the ELMs, it is important that this relation is verified for individual ELM events. Therefore, in this work the relation between ELM energy loss (W-ELM) and waiting time (Delta t(ELM)) is investigated for individual ELMs in a set of ITER-like wall plasmas in JET. A comparison is made with the results from a set of carbon-wall and nitrogen-seeded ITER-like wall JET plasmas. It is found that the correlation between W-ELM and Delta t(ELM) for individual ELMs varies from strongly positive to zero. Furthermore, the effect of the extended collapse phase often accompanying ELMs from unseeded JET ILW plasmas and referred to as the slow transport event (STE) is studied on the distribution of ELM durations, and on the correlation between W-ELM and Delta t(ELM). A high correlation between W-ELM and Delta t(ELM), comparable to CW plasmas is only found in nitrogen-seeded ILW plasmas. Finally, a regression analysis is performed using plasma engineering parameters as predictors for determining the region of the plasma operational space with a high correlation between W-ELM and Delta t(ELM)

Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called relative shift has an impact on the pedestal magnetohydrodynamic (MHD) stability and hence on the pedestal height (Osborne et al 2015 Nucl. Fusion 55 063018). The present work studies the effect of the relative shift on pedestal stability of JET ITER-like wall (JET-ILW) baseline low triangularity (\u3b4) unseeded plasmas, and similar JET-C discharges. As shown in this paper, the increase of the pedestal relative shift is correlated with the reduction of the normalized pressure gradient, therefore playing a strong role in pedestal stability. Furthermore, JET-ILW tends to have a larger relative shift compared to JET carbon wall (JET-C), suggesting a possible role of the plasma facing materials in affecting the density profile location. Experimental results are then compared with stability analysis performed in terms of the peeling-ballooning model and with pedestal predictive model EUROPED (Saarelma et al 2017 Plasma Phys. Control. Fusion). Stability analysis is consistent with the experimental findings, showing an improvement of the pedestal stability, when the relative shift is reduced. This has been ascribed mainly to the increase of the edge bootstrap current, and to minor effects related to the increase of the pedestal pressure gradient and narrowing of the pedestal pressure width. Pedestal predictive model EUROPED shows a qualitative agreement with experiment, especially for low values of the relative shift

Treatment options for Helicobacter pylori infection in the elderly

Helicobacter pylori infection plays a key role in dyspepsia, peptic ulcer disease and gastric cancer, thus the eradication of the infection has become an important treatment goal in clinical practice. The aim of this review is to present indications and therapies that are relevant for the management of H. pylori infection in elderly patients. Effective antimicrobial therapy is available, although there is still no ideal treatment, and indications for therapy continue to evolve. One-week proton pump inhibitor-based triple therapies are very effective in elderly patients; moreover, low doses of antibiotics (clarithromycin) and proton pump inhibitors are probably sufficient to obtain excellent cure rates, reducing side effects and improving compliance in elderly subjects. In some elderly patients, 10-day sequential treatment may be considered. Prolonging triple therapies to 10-14 days or using bismuth-based quadruple therapies require further studies in elderly patients. Low compliance and antibiotic resistance are the main factors related to treatment failure in old age. Therapy for treatment failure may be improved by assessing antimicrobial sensitivity. New drugs and forms of administration have been reported, although their efficacy requires confirmation. © 2006 Future Medicine Ltd