The intracluster medium (ICM) is a hot, tenuous and X-ray emitting gas that pervades galaxy clusters. Meanwhile, extended synchrotron sources, i.e., radio relics and radio halos are frequently... Show moreThe intracluster medium (ICM) is a hot, tenuous and X-ray emitting gas that pervades galaxy clusters. Meanwhile, extended synchrotron sources, i.e., radio relics and radio halos are frequently observed in galaxy cluster, for which the two widely accepted particle acceleration are shock acceleration and turbulent acceleration, respectively. Both of these scenarios are due to ICM motions, which means that X-ray observations of the ICM are fundamental for quantifying shock wave and turbulence properties to test the acceleration models. This thesis focuses on X-ray observations of galaxy clusters, and covers topics from ICM shock - radio relic connection to turbulence - radio halo connection. The new observational evidences further support the two acceleration scenario. Show less
The research project focuses on teachers’ learning motivation and learning performance in professional learning activities. Three assumptions as follows: (1) the quality of teaching has been... Show moreThe research project focuses on teachers’ learning motivation and learning performance in professional learning activities. Three assumptions as follows: (1) the quality of teaching has been significantly improved after a period of study in professional learning activities (2) teachers’ teaching quality and their learning motivation are interrelated, (3) teacher personal characteristics and school working conditions are important for their learning motivation. To explore these topics, students and supervisors from professional learning activities are invited to evaluate teaching quality, teachers who differed in the experience with the programme from primary education participated in this project to explore their perceptions of learning motivation. The final results indicated that teachers' learning motivation is not related to teachers' teaching quality. Show less
The main goal of this thesis is to further improve the ASL methodology for cerebral perfusion imaging by means of technological development. In this thesis, several new ASL techniques are... Show moreThe main goal of this thesis is to further improve the ASL methodology for cerebral perfusion imaging by means of technological development. In this thesis, several new ASL techniques are proposed, which cover the full breath of ASL-methodology, thereby enabling or improving the detection of different aspects of cerebral hemodynamics. VE-DASL is proposed to achieve fast cerebral flow territory mapping within 30 seconds. Time-encoded pCASL with a single voxel PRESS spectroscopic readout was implemented to detect multi-phase white matter perfusion in a highly time efficient manner. To better understand the signal generation mechanisms of IVIM, an ASL-preparation module was employed before an IVIM read-out, the diffusion properties of the blood pool were exclusively measured and the perfusion contribution was isolated. A novel method was proposed, optimized and validated to measure the labeling efficiency of pCASL directly by performing multi-phase pCASL imaging distal to the labeling plane. The longitudinal relaxation times of blood at different magnetic field strengths were measured and the expected gain in SNR by performing ASL at ultra-high magnetic field was quantified. Show less
The Gram-negative soil bacterium Agrobacterium tumefaciens is capable of infecting a large number of dicotyledonous plants, causing crown gall disease. During infection, a small DNA segment (T-DNA... Show moreThe Gram-negative soil bacterium Agrobacterium tumefaciens is capable of infecting a large number of dicotyledonous plants, causing crown gall disease. During infection, a small DNA segment (T-DNA) from the tumor-inducing (Ti) plasmid of the bacterium is delivered via a VirB/D4 Type Four Secretion System (TFSS) into plant cells where it is integrated into the genome. The expression of genes on the T-DNA in transformed plant cells leads to uncontrolled cell division, and ultimately triggers plant tumor formation. Agrobacterium also transfers several virulence (vir) proteins (VirD2, VirD3, VirD5, VirE2, VirE3 and VirF) encoded by genes present in the vir region of the Ti plasmid to host cells via the same TFSS apparatus independently of the T-DNA. In this thesis, I mainly focused on the biological functions of one of these translocated virulence proteins called VirD5. Show less
