Multipole interaction between atoms and their photonic environment

Macroscopic field quantization is presented for a nondispersive photonic dielectric environment, both in the absence and presence of guest atoms. Starting with a minimal-coupling Lagrangian, a careful look at functional derivatives shows how to obtain Maxwell's equations before and after choosing a suitable gauge. A Hamiltonian is derived with a multipolar interaction between the guest atoms and the electromagnetic field. Canonical variables and fields are determined and in particular the field canonically conjugate to the vector potential is identified by functional differentiation as minus the full displacement field. An important result is that inside the dielectric a dipole couples to a field that is neither the (transverse) electric nor the macroscopic displacement field. The dielectric function is different from the bulk dielectric function at the position of the dipole, so that local-field effects must be taken into account.Comment: 17 pages, to be published in Physical Review

Return to sports after COVID-19: a position paper from the Dutch Sports Cardiology Section of the Netherlands Society of Cardiology

The coronavirus disease 2019 (COVID-19) pandemic has led to preventive measures worldwide. With the decline of infection rates, less stringent restrictions for sports and exercise are being implemented. COVID-19 is associated with significant cardiovascular complications; however there are limited data on cardiovascular complications and long-term outcomes in both competitive (elite) athletes and highly active individuals. Based on different categories of disease severity (asymptomatic, regional/systemic symptoms, hospitalisation, myocardial damage, and/or myocarditis), in this point-of-view article we offer the (sports) cardiologist or sports physician in the Netherlands a practical guide to pre-participation screening, and diagnostic and management strategies in all athletes >16 years of age after COVID-19 infection

Bemoeizorg in de jeugdgezondheidszorg: Een studie naar doelgroep, interventie-methoden en doelrealisatie

Bemoeizorg in de Jeugdgezondheidszorg (JGZ) is een interventie die zich richt op gezinnen die langdurig kampen met een combinatie van sociaal-economische en psycho-sociale problematiek en nog niet goed bereikt worden door de JGZ. Dit artikel beschrijft een studie met als doel de wetenschappelijke onderbouwing van de interventie te versterken. Doelgroepkenmerken, interventie-methoden en mate van doelrealisatie werden onderzocht. De bevindingen laten zien dat de JGZ via deze interventie in contact komt met zeer kwetsbare gezinnen die vergelijkbaar zijn met gezinnen die in aanmerking komen voor intensieve ambulante gezinsbehandeling. Met name de basiszorg, het ouderlijk functioneren en het sociale netwerk zijn zwak. Bij de kinderen komen aanmerkelijk meer psycho-sociale problemen voor dan gemiddeld. De doelen van de interventie worden bij de meeste gezinnen behaald. Hoewel het onderzoeksdesign niet geschikt is om definitieve uitspraken te doen over de effectieve elementen van de interventie, kunnen wel een aantal elementen worden genoemd die lijken bij te dragen aan de werkzaamheid. Dit zijn de outreachende werkwijze, het bieden van praktische ondersteuning, maximale participatie van het gezin, en het bouwen van bruggen tussen het gezin en hulpbronnen in de omgeving van het gezin (informele en formele zorg)

Plasma burn-through simulations using the DYON code and predictions for ITER

This paper will discuss simulations of the full ionization process (i.e. plasma burn-through), fundamental to creating high temperature plasma. By means of an applied electric field, the gas is partially ionized by the electron avalanche process. In order for the electron temperature to increase, the remaining neutrals need to be fully ionized in the plasma burn-through phase, as radiation is the main contribution to the electron power loss. The radiated power loss can be significantly affected by impurities resulting from interaction with the plasma facing components. The DYON code is a plasma burn-through simulator developed at Joint European Torus (JET) (Kim et al and EFDA-JET Contributors 2012 Nucl. Fusion 52 [http://dx.doi.org/10.1088/0029-5515/52/10/103016] 103016 , Kim, Sips and EFDA-JET Contributors 2013 Nucl. Fusion 53 [http://dx.doi.org/10.1088/0029-5515/53/8/083024] 083024 ). The dynamic evolution of the plasma temperature and plasma densities including the impurity content is calculated in a self-consistent way using plasma wall interaction models. The recent installation of a beryllium wall at JET enabled validation of the plasma burn-through model in the presence of new, metallic plasma facing components. The simulation results of the plasma burn-through phase show a consistent good agreement against experiments at JET, and explain differences observed during plasma initiation with the old carbon plasma facing components. In the International Thermonuclear Experimental Reactor (ITER), the allowable toroidal electric field is restricted to 0.35 (V m −1 ), which is significantly lower compared to the typical value (∼1 (V m −1 )) used in the present devices. The limitation on toroidal electric field also reduces the range of other operation parameters during plasma formation in ITER. Thus, predictive simulations of plasma burn-through in ITER using validated model is of crucial importance. This paper provides an overview of the DYON code and the validation, together with new predictive simulations for ITER using the DYON code