The theses platform Utrecht University Student Theses Repository gives access to Open Access theses that have been published in the past fifteen years by students from Utrecht University and the University Medical Center Utrecht. The theses can also be found in international search engines such as WorldCat and Google (Scholar).
Theses will remain publicly available for a fifteen-year period. Please note: this is also true for theses which were publicly available before September 2021. After fifteen years they are automatically taken offline.
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Item type:Item, Test release 26.18(2026) Agasi, Jurriën; Externe beoordelaar - External assesor,Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 bla bla Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 bla bla Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18 Test release 26.18Item type:Item, Item type:Item, Effect of in ovo inoculation of 18 day incubated embryonated broiler eggs with Escherichia coli and Enterococcus faecalis on hatchability, chick quality and first week performance(2026) Beek, Marijke van de; Manders, ThijsA relative new technique in prevention of infectious diseases in poultry is in ovo vaccination, which has been used in the poultry industry since 1992. When injecting a vaccine in ovo, there are several factors which can alter the impact on the hatchability of the eggs. These factors include the characteristics of the vaccine, the injection technique and the overall hygiene of the hatchery. Bacterial contamination of embryonated eggs can impair hatchability and chick quality and lead to a higher first week mortality. The aim of this study was to discover which bacterial strains (mildly and very virulent strains of Escherichia coli and Enterococcus faecalis), in which dose (10^2, 10^4 or 10^6 colony forming units [cfu]/egg) and via which inoculation route (amniotic cavity or embryo) affected hatchability, chick quality and first week performance most. Hereto, 18 day incubated embryonated broiler eggs were inoculated with 0.1 ml bacterial suspension. Hatching rate, time of hatch, chick length, Pasgar score, mortality, time of death and weight at the end of the experiment were used as parameters. The results showed that hatch and first week mortality is affected by different bacteria and combinations, in all inoculated doses and by both inoculation routes. There was, however, no difference observed between inoculation routes. Chick quality did not seem to differ with the control groups, nor between the groups inoculated with bacteria. Strict aseptic measures should therefore be taken in hatcheries to avoid contamination of eggs with very virulent bacteria, such as Escherichia coli and Enterococcus faecalis, in low doses (10^2 cfu/egg).Item type:Item, Enhanced ikaite precipitation by bentonite fertilisation in the Fur formation, northern Denmark.(2026) Carmiggelt, Jeroen; King, HelenGlendonites are calcite pseudomorphs after the mineral ikaite. Because ikaite typically forms at low temperature, glendonite occurrences in deep time have been interpreted as indication for cold environmental conditions, even when found in sediments associated with greenhouse climates (Vickers et al., 2020). However, the exact conditions that control glendonite formation are not well constrained, and their occurrences often contradict other temperature proxies (Price et al., 2013). Ikaite nucleation experiments have shown that the temperature stability range of ikaite can be extended under the influence of certain chemical compounds (e.g. Mg2+, PO43-) and foreign minerals (e.g. Tollefsen et al., 2018; Strohm et al., 2022). Several prominent glendonite intervals worldwide are found in close association with bentonites. Therefore, by using a combination of microscopic and spectroscopic techniques, this study sets out to investigate the ways in which bentonites affect ikaite crystallisation. The investigated bentonite samples were extracted from the early Eocene Fur formation that crops out at the islands Mors and Fur in northern Denmark. This formation is also known to contain some of the largest glendonite crystals recorded to date. We followed the method from Tollefsen et al., (2018) to synthesise ikaite and added Fur-formation bentonite and/or solutions that had reacted with this bentonite prior to ikaite synthesis. Laboratory observations combined with ATR-FTIR, Raman spectroscopy and optical microscopy suggest that ikaite precipitation occurred via a dissolution-reprecipitation process. An ikaite nucleation experiment at high Mg-concentrations, reproduced from Tollefsen et al., (2018), yielded 30% ikaite precipitation with 70% co-precipitating nesquehonite. When leachate was used in these experiments, we still observed ikaite precipitation while co-precipitating nesquehonite was almost absent. Crystal agglomeration appeared to occur faster in reactive solution in direct contact with bentonites. When experimental solutions were reacting with (exchanging) bentonite, additional calcium and phosphate release was observed by ICP-OES. Calcium and phosphate contents increased in the solution from about 350 ppm to 700 ppm and about 0.1 ppm to 7.6 ppm, respectively. This fertilisation process is suggested to favour ikaite precipitation over co-precipitating nesquehonite. The effect of element release from the bentonite on the resulting ikaite pseudomorph morphologies appears limited. Natural glendonite morphologies (in the Fur formation) are therefore more likely controlled by the nature of the storage medium and the temperature differential between the crystallisation and transformation process.Item type:Item, A systematic review and risk assessment of zoonotic pathogens carried by the red fox (Vulpes vulpes) in Europe.(2026) Tiel, Robert van; Asjee, DamayThe red fox (Vulpes vulpes) is a well-known host of several zoonotic pathogens and can play a role in their transmission to humans. Red foxes are widely distributed and live in various habitats. Over the last decades they have become common habitants of urban environments in Europe. This development is potentially enhancing the risk of zoonotic pathogen transmission from foxes to humans. However, an overview of carriership of zoonotic pathogens by the red fox, as well as a risk assessment are still lacking. In this study scientific literature was systematically collected and reviewed in order to provide a complete overview of the zoonotic pathogens carried by the red fox in Europe. Also, a risk assessment of these pathogens was performed to estimate their risk for public health in the Netherlands. Furthermore, the prevalence of the zoonotic pathogens in red foxes sampled in different area types in Europe were compared. A total of 364 scientific papers were included in the review. In all, 171 zoonotic pathogen species and genera were described in red foxes. The risk assessment resulted in a risk score ranking of these pathogens. First in this ranking, with by far the highest risk score, was Echinococcus multilocularis. Comparison of prevalence for different area types proved to be possible for only 12 pathogens, due to the lack of adequate data for the vast majority of pathogens; definitive conclusions are therefore difficult to draw. In conclusion, the red fox can carry a broad variety of zoonotic pathogens. The risk assessment can be used to prioritize pathogens for future research and surveillance programs. To improve public health, future research and surveillance will provide high quality data, better the risk assessment and enable a valid estimate of prevalence for different area types.