Early evolution of electron cyclotron driven current during suppression of tearing modes in a circular tokamak

When electron cyclotron (EC) driven current is first applied to the inside of a magnetic island, the current spreads throughout the island and after a short period achieves a steady level. Using a two equation fluid model for the EC current that allows us to examine this early evolution in detail, we analyze high-resolution simulations of a 2/1 classical tearing mode in a low-beta large aspect-ratio circular tokamak. These simulations use a nonlinear 3D reduced-MHD fluid model and the JOREK code. During the initial period where the EC driven current grows and spreads throughout the magnetic island, it is not a function of the magnetic flux. However, once it has reached a steady-state, it should be a flux function. We demonstrate numerically that if sufficiently resolved toroidally, the steady-state EC driven current becomes approximately a flux function. We discuss the physics of this early period of EC evolution and its impact on the size of the magnetic island.Comment: 12 pages, 7 figure

Non-existence of normal tokamak equilibria with negative central current

Recent tokamak experiments employing off-axis, non-inductive current drive have found that a large central current hole can be produced. The current density is measured to be approximately zero in this region, though in principle there was sufficient current drive power for the central current density to have gone significantly negative. Recent papers have used a large aspect-ratio expansion to show that normal MHD equilibria (with axisymmetric nested flux surfaces, non-singular fields, and monotonic peaked pressure profiles) can not exist with negative central current. We extend that proof here to arbitrary aspect ratio, using a variant of the virial theorem to derive a relatively simple integral constraint on the equilibrium. However, this constraint does not, by itself, exclude equilibria with non-nested flux surfaces, or equilibria with singular fields and/or hollow pressure profiles that may be spontaneously generated.Comment: 5 pages, 3 figures. Submitted to Physics of Plasmas, Feb. 14, 2003. Revised Feb. 24, 2003. Vers. 2: revised May 29 to clarify points raised by referee, add references to recent work. July 18, accepted for publicatio

Differential relationships in the association of the Big Five personality traits with positive mental health and psychopathology

According to the two continua model of mental health, psychopathology and positive mental health (emotional, psychological, and social well-being) are related but distinct continua. This study investigates the two continua model by examining whether psychopathology and positive mental health show differential associations with the Big Five personality traits. The paper draws on data of the representative LISS panel (CentERdata). Participants (N = 1161; age 18–88) filled out questionnaires on personality, psychopathology, and positive mental health. Personality traits were differentially related to psychopathology and positive mental health, supporting the two continua model. Emotional stability (reversed neuroticism) is the main correlate of psychopathology, whereas the personality traits extraversion and agreeableness are uniquely associated with positive mental health

From time-series to complex networks: Application to the cerebrovascular flow patterns in atrial fibrillation

A network-based approach is presented to investigate the cerebrovascular flow patterns during atrial fibrillation (AF) with respect to normal sinus rhythm (NSR). AF, the most common cardiac arrhythmia with faster and irregular beating, has been recently and independently associated with the increased risk of dementia. However, the underlying hemodynamic mechanisms relating the two pathologies remain mainly undetermined so far; thus the contribution of modeling and refined statistical tools is valuable. Pressure and flow rate temporal series in NSR and AF are here evaluated along representative cerebral sites (from carotid arteries to capillary brain circulation), exploiting reliable artificially built signals recently obtained from an in silico approach. The complex network analysis evidences, in a synthetic and original way, a dramatic signal variation towards the distal/capillary cerebral regions during AF, which has no counterpart in NSR conditions. At the large artery level, networks obtained from both AF and NSR hemodynamic signals exhibit elongated and chained features, which are typical of pseudo-periodic series. These aspects are almost completely lost towards the microcirculation during AF, where the networks are topologically more circular and present random-like characteristics. As a consequence, all the physiological phenomena at microcerebral level ruled by periodicity - such as regular perfusion, mean pressure per beat, and average nutrient supply at cellular level - can be strongly compromised, since the AF hemodynamic signals assume irregular behaviour and random-like features. Through a powerful approach which is complementary to the classical statistical tools, the present findings further strengthen the potential link between AF hemodynamic and cognitive decline.Comment: 12 pages, 10 figure

Exploring facilitators and barriers to using a person centered care intervention in a nursing home setting

Person-centered care (PCC) interventions have the potential to improve resident well-being in nursing homes, but can be difficult to implement. This study investigates perceived facilitators and barriers reported by nursing staff to using a PCC intervention consisting of three components: assessment of resident well-being, planning of well-being support, and behavioral changes in care to support resident well-being. Our explorative mixed method study combined interviews (n = 11) with a longitudinal survey (n = 132) to examine which determinants were most prevalent and predictive for intention to use the intervention and actual implementation 3 months later (n = 63). Results showed that perceived barriers and facilitators were dependent on the components of the intervention. Assessment of resident well-being required a stable nursing home context and a detailed implementation plan, while planning of well-being support was impeded by knowledge. Behavioral changes in nursing care required easy integration in daily caring tasks and social support

Verkennen en toepassen van besluitvormingsmodellen in de uitvoering van natuurbeleid

In dit werkdocument is een literatuurverkenning uitgevoerd van verschillende bestuurskundige analysemethoden en besluitvormingsmodellen. Daarnaast zijn twee casussen onderzocht om te verkennen of dergelijke casussen toepasbaar zijn om besluitvormingsmodellen in het natuurbeleid te simuleren. Uit de verkenningen is een prototype besluitvormingsmodel ontwikkeld en is de besluitvorming van een casus gesimuleerd. De voorlopige resultaten van deze simulaties geven aanleiding om het besluitvormingsmodel verder te ontwikkelen