We explored how to morphologically classify well-resolved jetted radio-loud active galactic nuclei (RLAGN) in the LOw Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS) using machine learning.We... Show moreWe explored how to morphologically classify well-resolved jetted radio-loud active galactic nuclei (RLAGN) in the LOw Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS) using machine learning.We investigated what morphology in total radio intensity maps can tell us about observed radio sources without complementary wavelength information and with limited visual inspection. We used a self-organising map (SOM) to model common radio morphologies and to reveal the rarest morphologies in LoTSS.Furthermore, we turned the radio source-component association problem into an object detection problem and trained an adapted Fast region convolutional neural network to mimic the grouping of source components into unique sources as performed by astronomers for LoTSS data.We also reduced the visual inspection required to find RLAGN remnant candidates based on their morphology, by using SOM-based features as input for a random forest classifier.Finally, we created a machine learning pipeline to identify giant radio galaxy (GRG) candidates and created a sample that contains more than ten thousand GRG. We then quantified the intrinsic GRG proper length distribution, the comoving GRG number density, and a current-day GRG lobe volume-filling fraction in clusters and filaments of the Cosmic Web. Show less
The Bibliotheca Enchusana or Librije of Enkhuizen is one of the oldest libraries that are still preserved in situ in the Netherlands and can rightfully be called a unique book historical monument.... Show moreThe Bibliotheca Enchusana or Librije of Enkhuizen is one of the oldest libraries that are still preserved in situ in the Netherlands and can rightfully be called a unique book historical monument. In this dissertation the history of the Librije is reconstructed through a new scholarly catalogue, which is based on a hands-on examination of all the books from the library’s holdings. The catalogue contains extensive bibliographical descriptions as well as information about the physical evidence of every book’s unique history, such as inscriptions of former owners, binding details, and manuscript annotations. Together with information from archival documents, the new catalogue helps to better understand the holdings of the Librije, their origin and history, as well as the use and function of the library since its foundation. Subsequently, this dissertation explores how the specific character of Enkhuizen influenced the Librije and how the role of the library changed throughout history. Show less
The library which Leiden University bought in 1690 from the heirs of Isaac Vossius (1618-1689) had a reputation with his contemporaries to be the best and most complete private library of its time.... Show moreThe library which Leiden University bought in 1690 from the heirs of Isaac Vossius (1618-1689) had a reputation with his contemporaries to be the best and most complete private library of its time. This acquisition of more than 700 manuscripts and about 4,000 printed books doubled the Academy’s collections at one stroke and made an architectural extension for the library necessary. The private collector Isaac Vossius had more means and resources at his disposal to keep up with the scientific developments of his time than the librarian of the institutional library of the university. Books by Galilei, Descartes and Newton became available in the Leiden University Library for the first time in 1690. Reconstructing the medical, philosophical and mathematical sections of Vossius’s library provides insight in the sources he may have used for his own scholarly production, which he wrote during the second half of his life. A careful analysis of the printed books reveals many provenances of contemporary scholars and earlier bookcollectors. It shows to what extent Isaac Vossius stood on the shoulders of men like Joseph Scaliger, Hugo Grotius, his own father Gerardus Johannes Vossius and many others of which he owned books and manuscripts. Show less
