Closure of the single fluid magnetohydrodynamic equations in presence of electron cyclotron current drive

In the presence of electron cyclotron current drive (ECCD), the Ohm's law of single fluid magnetohydrodynamics (MHD) is modified as ${\bf E} + {\bf v} \times {\bf B} = \eta( {\bf J} - {\bf J}_{\rm EC} )$. This paper presents a new closure relation for the EC driven current density appearing in this modified Ohm's law. The new relation faithfully represents the nonlocal character of the EC driven current and its main origin in the Fisch-Boozer effect. The closure relation is validated on both an analytical solution of an approximated Fokker-Planck equation as well as on full bounce-averaged, quasi-linear Fokker-Planck code simulations of ECCD inside rotating magnetic islands. The new model contains the model put forward by Giruzzi et al., Nucl. Fusion 39 (1999) 107, in one of its limits

Life Stories and Mental Health: The Role of Identification Processes in Theory and Interventions

The goal of this article is to explore the relations between narratives and mental health from a psychological perspective. We argue that a process of identification with personal experiences underlies narrative structures that are known to be related to mental health. Overidentification and underidentification are described as general processes underlying mental health problems. Gerontological insights in reminiscence and life review and cognitive psychological studies on autobiographical memories validate this claim. Practical applications in mental health care provide even further evidence for the role of identification processes in mental health and how they can be targeted in intervention

Non-linear effects in electron cyclotron current drive applied for the stabilization of neoclassical tearing modes

Due to the smallness of the volumes associated with the flux surfaces around the O-point of a magnetic island, the electron cyclotron power density applied inside the island for the stabilization of neoclassical tearing modes (NTMs) can exceed the threshold for non-linear effects as derived previously by Harvey et al, Phys. Rev. Lett. 62 (1989) 426. We study the non-linear electron cyclotron current drive (ECCD) efficiency through bounce-averaged, quasi-linear Fokker-Planck calculations in the magnetic geometry as created by the islands. The calculations are performed for the parameters of a typical NTM stabilization experiment on ASDEX Upgrade. A particular feature of these experiments is that the rays of the EC wave beam propagate tangential to the flux surfaces in the power deposition region. The calculations show significant non-linear effects on the ECCD efficiency, when the ECCD power is increased from its experimental value of 1 MW to a larger value of 4 MW. The nonlinear effects are largest in case of locked islands or when the magnetic island rotation period is longer than the collisional time scale. The non-linear effects result in an overall reduction of the current drive efficiency for this case with absorption of the EC power on the low field side of the electron cyclotron resonance layer. As a consequence of the non-linear effects, also the stabilizing effect of the ECCD on the island is reduced from linear expectations

The arterial Windkessel

Frank’s Windkessel model described the hemodynamics of the arterial system in terms of resistance and compliance. It explained aortic pressure decay in diastole, but fell short in systole. Therefore characteristic impedance was introduced as a third element of the Windkessel model. Characteristic impedance links the lumped Windkessel to transmission phenomena (e.g., wave travel). Windkessels are used as hydraulic load for isolated hearts and in studies of the entire circulation. Furthermore, they are used to estimate total arterial compliance from pressure and flow; several of these methods are reviewed. Windkessels describe the general features of the input impedance, with physiologically interpretable parameters. Since it is a lumped model it is not suitable for the assessment of spatially distributed phenomena and aspects of wave travel, but it is a simple and fairly accurate approximation of ventricular afterload

The roles of resident, central and effector memory CD4 T cells in protective immunity following infection or vaccination

Immunological memory provides rapid protection to pathogens previously encountered through infection or vaccination. CD4 T cells play a central role in all adaptive immune responses. Vaccines must, therefore, activate CD4 T cells if they are to generate protective immunity. For many diseases, we do not have effective vaccines. These include HIV, tuberculosis and malaria, which are responsible for many millions of deaths each year across the globe. CD4 T cells play many different roles during the immune response coordinating the actions of many other cells. In order to harness the diverse protective effects of memory CD4 T cells we need to understand how memory CD4 T cells are generated and how they protect the host. Here we review recent findings on the location of different subsets of memory CD4 T cells that are found in peripheral tissues (tissue resident memory T cells) and in the circulation (central and effector memory T cells). We discuss the generation of these cells and the evidence that demonstrates how they provide immune protection in animal and human challenge models

Application of mixed integer programming to a large scale logistics problem

Integer Programming;Logistics;production

Resilience in rural common-pool resource management systems: towards enhancing landscape amenities using a multi-agent approach

Rural areas are continuously subject to changing circumstances, varying from changes in ecosystem conditions to socio-economic changes like food- and financial crises. Within Europe, the Common Agricultural Policy (CAP) reform is driver as well for change of rural common pool resources (CPR). Rural CPRs are defined as rural social-ecological systems which provide landscapes with high agricultural, ecological and cultural-historical values. The conservation of these systems is treated as the enhancement of these values through the protection of rare plant species. Analyzing resilience of rural CPRs offers a framework to emphasize dynamics and interdependencies across time, space and between social, economic and ecological domains. This paper provides insight into the effects of CAP reforms on rural CPRs and its resilience, through the use of a multi-agent simulation approach. The advantage of such a multi-agent approach is that it allows to capture interactions of heterogeneous agents in a landscape that provides space for both agriculture and rare plant species. The simulation model is applied for Winterswijk, which is a rural region in eastern part of the Netherlands. This CPR is characterized by a small scale landscape with high biodiversity. Transferring insights from resilience thinking to rural development strategies would lead to a focus on the factors that build the ability of the rural area to respond to policy changes. The strength of multi-agent models is illustrated and their potential for the analysis of different policy options and implications in rural areas is shown