Collisional transport across the magnetic field in drift-fluid models

Drift ordered fluid models are widely applied in studies of low-frequency turbulence in the edge and scrape-off layer regions of magnetically confined plasmas. Here, we show how collisional transport across the magnetic field is self-consistently incorporated into drift-fluid models without altering the drift-fluid energy integral. We demonstrate that the inclusion of collisional transport in drift-fluid models gives rise to diffusion of particle density, momentum and pressures in drift-fluid turbulence models and thereby obviate the customary use of artificial diffusion in turbulence simulations. We further derive a computationally efficient, two-dimensional model which can be time integrated for several turbulence de-correlation times using only limited computational resources. The model describes interchange turbulence in a two-dimensional plane perpendicular to the magnetic field located at the outboard midplane of a tokamak. The model domain has two regions modeling open and closed field lines. The model employs a computational expedient model for collisional transport. Numerical simulations show good agreement between the full and the simplified model for collisional transport

Shear Flow Generation and Energetics in Electromagnetic Turbulence

Zonal flows are recognised to play a crucial role for magnetised plasma confinement. The genesis of these flows out of turbulent fluctuations is therefore of significant interest. We investigate the relative importance of zonal flow generation mechanisms via the Reynolds stress, Maxwell stress, and geodesic acoustic mode (GAM) transfer in drift-Alfv\'en turbulence. By means of numerical computations we quantify the energy transfer into zonal flows owing to each of these effects. The importance of the three driving ingredients in electrostatic and electromagnetic turbulence for conditions relevant to the edge of fusion devices is revealed for a broad range of parameters. The Reynolds stress is found to provide a flow drive, while the electromagnetic Maxwell stress is in the cases considered a sink for the flow energy. In the limit of high plasma beta, where electromagnetic effects and Alfv\'en dynamics are important, the Maxwell stress is found to cancel the Reynolds stress to a high degree. The geodesic oscillations, related to equilibrium pressure profile modifications due to poloidally asymmetric transport, can act as both sinks as drive terms, depending on the parameter regime. For high beta cases the GAMs are the main drive of the flow. This is also reflected in the frequency dependence of the flow, showing a distinct peak at the GAM frequency in that regime.Comment: 16 pages, 12 Figure

Age at Puberty and the Emerging Obesity Epidemic

Background: Recent studies have shown that puberty starts at younger ages than previously. It has been hypothesized that the increasing prevalence of childhood obesity is contributing to this trend. The purpose of this study was to analyze the association between prepubertal body mass index (BMI) and pubertal timing, as assessed by age at onset of pubertal growth spurt (OGS) and at peak height velocity (PHV), and the secular trend of pubertal timing given the prepubertal BMI. Methodology/Principal Findings: Annual measurements of height and weight were available in all children born from 1930 to 1969 who attended primary school in the Copenhagen municipality; 156,835 children fulfilled the criteria for determining age at OGS and PHV. The effect of prepubertal BMI at age seven on these markers of pubertal development within and between birth cohorts was analyzed. BMI at seven years was significantly inversely associated with age at OGS and PHV. Dividing the children into five levels of prepubertal BMI, we found a similar secular trend toward earlier maturation in all BMI groups. Conclusion/Significance: The heavier both boys and girls were at age seven, the earlier they entered puberty. Irrespective of level of BMI at age seven, there was a downward trend in the age at attaining puberty in both boys and girls, whic

Clinical consequences of antibody formation, serum concentrations, and HLA-Cw6 status in psoriasis patients on Ustekinumab

Background: Ustekinumab for the treatment of psoriasis is currently administered in a standard dosing regimen. However, some patients tend to benefit from alternative dosing regimens, a step toward personalized medicine. Methods: To investigate the role of ustekinumab serum concentrations, anti-ustekinumab antibodies [AUA] and HLA-Cw6 status as tools for optimizing ustekinumab treatment, a multicenter prospective cohort study was conducted at an academic hospital with affiliated nonacademic hospitals in Belgium (cohort 1) and 2 academic hospitals in the Netherlands (cohort 2 and 3). Patients with plaque-type psoriasis were eligible if treated with ustekinumab for >16 weeks. Serum samples and Psoriasis Area and Severity Index scores were obtained at baseline, week 16, 28, 40, 52, and/or >64 of ustekinumab treatment. Results: A total of 137 patients with 229 observations for serum concentrations and AUA and 61 observations for HLA-Cw6 status were included. Presence of AUA (prevalence of 8.7%) was significantly associated with a diminished clinical response (P = 0.032). The median ustekinumab trough concentration was 0.3 mcg/mL (<0.02-3.80). No differences in serum concentrations were observed between moderate to good responders and nonresponders (P = 0.948). Serum trough concentrations were not affected by methotrexate comedication. Prevalence of HLA-Cw6 positivity was 41% with no statistically significant difference in clinical response between HLA-Cw6-positive and HLA-Cw6-negative patients (P = 0.164). Conclusions: The presence of AUA was associated with treatment failure in this patient population; measurement of AUA may therefore be a candidate marker for personalized pharmacotherapy. The clinical utility of ustekinumab serum trough concentrations or HLA-Cw6 status determination remains less clear. Further exploration on the potential of measuring ustekinumab serum concentrations and other biomarkers in predicting therapy outcomes should be encouraged

Self-trapping of impurities in Bose-Einstein condensates: Strong attractive and repulsive coupling

We study the interaction-induced localization -- the so-called self-trapping -- of a neutral impurity atom immersed in a homogeneous Bose-Einstein condensate (BEC). Based on a Hartree description of the BEC we show that -- unlike repulsive impurities -- attractive impurities have a singular ground state in 3d and shrink to a point-like state in 2d as the coupling approaches a critical value. Moreover, we find that the density of the BEC increases markedly in the vicinity of attractive impurities in 1d and 2d, which strongly enhances inelastic collisions between atoms in the BEC. These collisions result in a loss of BEC atoms and possibly of the localized impurity itself.Comment: 7 pages, 5 figure

Anomalous diffusion, clustering, and pinch of impurities in plasma edge turbulence

The turbulent transport of impurity particles in plasma edge turbulence is investigated. The impurities are modeled as a passive fluid advected by the electric and polarization drifts, while the ambient plasma turbulence is modeled using the two-dimensional Hasegawa--Wakatani paradigm for resistive drift-wave turbulence. The features of the turbulent transport of impurities are investigated by numerical simulations using a novel code that applies semi-Lagrangian pseudospectral schemes. The diffusive character of the turbulent transport of ideal impurities is demonstrated by relative-diffusion analysis of the evolution of impurity puffs. Additional effects appear for inertial impurities as a consequence of compressibility. First, the density of inertial impurities is found to correlate with the vorticity of the electric drift velocity, that is, impurities cluster in vortices of a precise orientation determined by the charge of the impurity particles. Second, a radial pinch scaling linearly with the mass--charge ratio of the impurities is discovered. Theoretical explanation for these observations is obtained by analysis of the model equations.Comment: This article has been submitted to Physics of Plasmas. After it is published, it will be found at http://pop.aip.org/pop

Gaming when things get tough? Examining how emotion regulation and coping self-efficacy influence gaming during difficult life situations

Research suggests that gaming can play an important role in dealing with life difficulties, but few studies have examined this directly. Building on recent research, the current study set out to develop a measure of gaming in difficult life situations (GDLS) and explored the role of emotion regulation and coping self-efficacy as predictors of this behaviour. A total of 667 gamers completed the online survey. Initial analyses demonstrated validity and reliability of the GDLS scale (α=.92), with players turning to gaming as a distraction from life difficulties, to feel a sense of achievement, to connect with others, and for in-game connection and simulation. Multiple regression analysis showed that younger age, more time spent gaming in general, and lower coping self-efficacy predicted gaming in difficult life situations, but emotion regulation was non-significant. The study presents novel insights and a new measure for future research in this area

The risks of adverse events with venlafaxine and mirtazapine versus 'active placebo', placebo, or no intervention for adults with major depressive disorder: a protocol for two separate systematic reviews with meta-analysis and Trial Sequential Analysis

BACKGROUND: Major depressive disorder causes a great burden on patients and societies. Venlafaxine and mirtazapine are commonly prescribed as second-line treatment for patients with major depressive disorder worldwide. Previous systematic reviews have concluded that venlafaxine and mirtazapine reduce depressive symptoms, but the effects seem small and may not be important to the average patient. Moreover, previous reviews have not systematically assessed the occurrence of adverse events. Therefore, we aim to investigate the risks of adverse events with venlafaxine or mirtazapine versus 'active placebo', placebo, or no intervention for adults with major depressive disorder in two separate systematic reviews. METHODS: This is a protocol for two systematic reviews with meta-analysis and Trial Sequential Analysis. The assessments of the effects of venlafaxine or mirtazapine will be reported in two separate reviews. The protocol is reported as recommended by Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols, risk of bias will be assessed with the Cochrane risk-of-bias tool version 2, clinical significance will be assessed using our eight-step procedure, and the certainty of the evidence will be assessed with the Grading of Recommendations Assessment, Development and Evaluation approach. We will search for published and unpublished trials in major medical databases and trial registers. Two review authors will independently screen the results from the literature searches, extract data, and assess risk of bias. We will include published or unpublished randomised clinical trial comparing venlafaxine or mirtazapine with 'active placebo', placebo, or no intervention for adults with major depressive disorder. The primary outcomes will be suicides or suicide attempts, serious adverse events, and non-serious adverse events. Exploratory outcomes will include depressive symptoms, quality of life, and individual adverse events. If feasible, we will assess the intervention effects using random-effects and fixed-effect meta-analyses. DISCUSSION: Venlafaxine and mirtazapine are frequently used as second-line treatment of major depressive disorder worldwide. There is a need for a thorough systematic review to provide the necessary background for weighing the benefits against the harms. This review will ultimately inform best practice in the treatment of major depressive disorder. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022315395