This thesis is concerned with the technical, physical and computational challenges regarding
the incorporation of microwave tomography in hyperthermia treatments. Hyperthermia is a
clinical technique in which tumorous tissue is heated to gain therapeutic effect for concurrent
radiotherapy. Hyperthermia by microwaves, as performed at the Erasmus Medical Center,
suffers from uncertainties and lacking control. To relieve the burden of uncertainties regarding
dielectric properties and patient positioning, microwave tomography can be used in hyperthermia systems. This could also improve treatments, as it would offer more possibilities for
controlling the delivery. This work is focused on relieving several practical limitations to the
integration of tomography, rather than researching its possibilities. This thesis is accompanied by the literature research “Advancements in Microwave Tomography and Hyperthermia
Treatments” by the same author.

Ever since their discovery, the Trojans have raised many questions among astrophysicists. In 1989 it was found that there were more L4 than L5 Trojans and the current L4:L5 ratio value is estimated to be 1.6. However, this asymmetry could not be explained by Jupiter’s current orbit and must therefore have arisen during the early development of the Solar System. It was suggested that an outward migration as described by the Nice model could cause the asymmetry. To investigate this, we extended a recent research by modelling an outward migration of Jupiter on the actual Trojans and their symmetric copies. In this manner, we had a broad initial Trojan distribution, which allowed us to investigate several effects of initial values like the Trojan inclinations and maximum angular deviations from the Lagrange point. The simulations used a recently found midpoint Yoshida integrator, which allowed fourth order symplectic simulations for our non-separable Hamiltonian problem. From the simulations it followed that the ratio could only be explained if the Trojans initially had large angular deviations from the Lagrange point, which is possible if they later lost energy due to for example mutual collisions. Also the small initial inclinations as predicted for the early Trojans would in general have risen due to the migration, but it could not explain the the inclinations up to 40 degrees for today Trojans, implying that the increase in inclination must have been caused by other reasons. We found that not only the total migration distance and duration are important, but also the function that describes the evolution of Jupiter’s semi-major axis and the eccentricity of Jupiter’s orbit. For further research we suggest to use data sets on those quantities from simulations with the Nice model, to investigate these related problems together. We believe that our model and code is of great advantage for such a research, because of its optimisations and it allows to implement the data on the distance and eccentricity directly into the model without having to alter the equations of motion.

Academic research is inherently cooperative, with researchers exchanging information through formal publications as well as direct messaging. Academia are, however, becoming increasingly competitive: limited financial resources and research spots, among other things, may now affect how researchers cooperate and interact in general. In the current study, the congruence of cooperative and competitive interactions in academia was investigated. To this end, the existing knowledge on the competition and cooperation amalgamation "coopetition", coined for industry relationships, was used. A theoretical framework on coopetition and related theories relavant to academic relationships was constructed. This framework was used to conduct an online survey on academic coopetition among academic microscopy researchers in the Netherlands. The results suggested that competition and cooperation in academia are related yet separate, so that an increase in one does not necessitate a decrease in the other and vice versa. Additionally, the survey responses suggested a discrepancy between the respondents' reported competitive sentiments and those apparent from their other answers. To address this discrepancy, and help academic researchers reflect on what competition and cooperation mean to them, the interactive Guide for Introspection on Competition and Cooperation (GICCo) was developed.

Gravitational waves predicted by Einstein have been measured in a few observatories worldwide. These detectors are complex interferometers with sizes of kilometers. Misalignments and aberrations in their optical set-up can create higher-order modes in the laser beam. These higher-order mode effects should be compensated to improve the sensitivity of the interferometer. Such a compensating control system requires a real-time wavefront sensor. The phase cameras developed for the Virgo gravitational wave detector can simultaneously create intensity and phase images of the laser wavefront at 11 demodulation frequencies. Currently, the phase images are not used due to difficulties in the interpretation. Therefore, the goal of this research is to improve the understanding of the phase images of a phase camera for the Virgo gravitational wave detector.

A prototype set-up of the phase camera was built at Nikhef. The beam is modulated and sidebands are created such that a beat signal of 80 MHz and the first upper and lower sidebands at 75 and 85 MHz are measured. Images are created by scanning the laser beam across a pinhole diode and digital demodulation. In the chosen optical set-up only one of the two beams that give the measurable beat signal is scanned. This leads to systematic phase effects caused by length differences in the optical path as a function of the scanning angle. To predict the phase images, the interference of two Gaussian beams with a scanning mirror is mathematically derived. Phase images are created with a simulation, which matches within 10 to 20% compared to measurements. To improve the results, the input parameters of the simulation should be measured more accurately and the optical set-up layout should be checked. Also, the phase stability of the prototype set-up is measured. Due to the high sensitivity of the phase camera, very small optical path length differences, for example caused by airflow or temperature differences, lead to significant phase offsets. The long timescale fluctuations in the phase measurements can be reduced by covering the optical set-up. The measured high-frequency phase resolution is Δ𝜙 = 7.1 ± 0.4 mrad and behaves as a function of power as expected.