In this Ph.D. thesis we study the interaction of low energy electrons with thin materials, namely layered materials (graphene, hexagonal boron nitride, molybdenum disulfide) and organic films. At... Show moreIn this Ph.D. thesis we study the interaction of low energy electrons with thin materials, namely layered materials (graphene, hexagonal boron nitride, molybdenum disulfide) and organic films. At these low energies the quantum mechanical wavelength of the electron wave function is in the order of a few Angstroms, thus comparable to the interlayer distance in layered materials. This leads to resonances in the electron reflection/transmission spectrum, comparable to the interference of light when it is reflected from a thin film. We use low energy electron microscopy (LEEM) and electron Volt transmission electron microscopy (eV-TEM) to determine the energy dependent electron mean free path (MFP) and identify resonant transmission/reflection states related to the unoccupied band structure. Furthermore, we use photoemission electron microscopy (PEEM) to image low energy electrons from a gold surface covered with a film of chiral organic molecules. We image the photoexcited electrons and compare the intensity of photoemission caused by different (circular) polarizations of light. Show less
The research developed in this doctoral dissertation contributes to Sasanian studies in particular, and to ancient Iranian studies more generally, in three main ways. First, it offers a critical... Show moreThe research developed in this doctoral dissertation contributes to Sasanian studies in particular, and to ancient Iranian studies more generally, in three main ways. First, it offers a critical study of the history of research surrounding the decipherment of the Middle Persian script, to define the contribution of Sasanian epigraphy to the broader historiographical debates concerning the study of Late Antiquity. Then, through the palaeographic analysis of the earliest pre-Sasanian and Sasanian Middle Persian written vestiges, it highlights the existence of a lively scribal tradition that was local to Persis in the Seleucid and Parthian periods. Finally, it investigates a possible model for the study of Sasanian inscriptions which takes into account the references made in these monumental texts to (now lost) manuscript documents, as well as to key features of their natural and built environment; this helps bring into sharp focus the often overlooked legal, administrative and religious functions of Sasanian rock-cut texts. Show less
The marine shipping industry is one of the strongest emitters of nitrogen oxides (NOx), a pollutant detrimental to ecology and human health. Over the last 20 years, the pollution produced by power... Show moreThe marine shipping industry is one of the strongest emitters of nitrogen oxides (NOx), a pollutant detrimental to ecology and human health. Over the last 20 years, the pollution produced by power plants, the industry sector, and cars has been decreasing. In contrast, the pollution impact of maritime transport continues to increase. This generates a big societal pressure, resulting in regulations proposed by the International Maritime Organization (IMO). These regulations impose restrictions on emission levels from ships. While various methods are used to assess the emission from ships in ports and off-coastal areas, monitoring over the open sea has been infeasible. The game-changer is the TROPOMI instrument on board the Sentinel 5 Precursor Satellite – studies show that NO2 plumes from some individual seagoing ships can be distinguished on TROPOMI images. The objective of this thesis is to pave the way toward the application of the TROPOMI instrument for the monitoring of compliance of seagoing ships. This is achieved through the fusion of machine learning, feature engineering, and data integration. Each chapter builds upon the findings of its predecessor, as a whole, representing state-of-the-art knowledge in the application of TROPOMI data for the monitoring of NO2 emissions from individual seagoing ships. Show less
What physics controls the properties of quantum matter, such as how electrons flow inside high-temperature superconductors? This question has captivated the physics community and industry for... Show moreWhat physics controls the properties of quantum matter, such as how electrons flow inside high-temperature superconductors? This question has captivated the physics community and industry for decades, in part due to the great technological potential such materials have, but also because they have resisted all traditional methods of understanding. It calls for a complete change in paradigm. An unexpected venue for progress was found in the study of gravity. By studying special gravitational solutions such as black holes and stars made of electrons, it turns out to be possible to shed some light on the physics and transport properties of quantum matter. This analysis relies on the use of high-performance computations to obtain these gravitational solutions, but the payoff is access to uncharted areas of physics. So far, such methods have successfully brought some insight into the flow of energy in such systems, but the flow of electric charge or the quantum information patterns remain shrouded in mystery. The findings of this thesis address key parts of these questions, particularly in the context of black holes as models of exotic quantum metals. Show less
More than 5,000 exoplanets have been found over the past couple of decades. These exoplanets show a tremendous diversity, ranging from scorching hot Jupiters, common super-Earths, to widely... Show moreMore than 5,000 exoplanets have been found over the past couple of decades. These exoplanets show a tremendous diversity, ranging from scorching hot Jupiters, common super-Earths, to widely separated super-Jupiters on the planet/brown dwarf boundary. We have now moved into the era of exoplanet atmospheric characterisation. Two crucial techniques for characterizing these exoplanets from the ground are high-contrast imaging and high-resolution spectroscopy. In the first part of the thesis, existing facilities are used to characterize the atmospheres of two of the most accessible types of planets: An ultra-hot Jupiter (WASP-76b) and a young supter-Jupiter (beta Pictoris b). The second part of the thesis develops instrumental concepts that are required to push exoplanet characterization towards smaller and closer-in planets. It shows how we can choose between spectral resolution, bandwidth, and field-of-view in developing an instrument for exoplanet detection, and how one can design an nearly optimal wavefront sensor for adaptive optics. Finally, it is demonstrated how machine learning techniques can help us improve the performance of these adaptive optics systems such that we can reach deeper contrasts for exoplanet imaging and characterization. Show less
In this thesis, topics relating to the optimization of high-throughput pipelines used for imaging are discussed. In particular, different levels of implementation, i.e., conceptual, software, and... Show moreIn this thesis, topics relating to the optimization of high-throughput pipelines used for imaging are discussed. In particular, different levels of implementation, i.e., conceptual, software, and hardware, are discussed and the thesis outlines how advances on each level need to be made to make gains in computationally demanding imaging applications. Chapter 2 concerns the implementation of real-time segmentation of X-ray computed tomography (CT). Chapter 3 concerns the end-to-end optimization of various CT workflows by using auto-differentiation frameworks. Chapter 4 concerns a novel pruning method for neural network to significantly increase the speed of convolutional neural networks (CNNs). Chapter 5 comprises a benchmark study of optimization algorithms for tuning GPU kernels, and introduces a novel graph-based approach to quantify search space difficulty. Chapter 6 introduces a novel model to improve the energy efficiency of GPUs. Show less
The aim of this thesis was to gain a better understanding of the deleterious effects of Neonatal Brachial Plexus Palsy (NBPP) on central development by analyzing sensory and motor function.The... Show moreThe aim of this thesis was to gain a better understanding of the deleterious effects of Neonatal Brachial Plexus Palsy (NBPP) on central development by analyzing sensory and motor function.The explanation for problems with hand function was not clear in children who had an upper NBPP where only the C5 and C6 spinal nerves are affected, which predominantly innervate the shoulder and elbow flexion. The main findings of this thesis: Children with an upper NBPP have a diminished sensibility of the thumb and index finger which correlates with diminished dexterity. The ability to localize stimuli to the thumb, index, third and fourth fingers is disturbed in children with an upper NBPP. Most children with an upper NBPP are not aware of the diminished sensibility in their affected hand. Also Grip force of the hand is reduced in children with an upper NBPP lesion. NBPP is a peripheral nervous lesion, which affects the development of the central nervous system as well. The age at which children with NBPP can walk independently is delayed, which does not depend on the severity of the lesion. Treatment of children with a NBPP had to focus on the total development of the child. Show less
Oratie uitgesproken door Prof.dr. Maaike M. Kempes bij de aanvaarding van het ambt van bijzonder hoogleraar forensische neuropedagogiek aan de Universiteit Leiden op maandag 10 juni 2024
Oratie uitgesproken door Prof. dr. Ivo van Vulpen bij de aanvaarding van het ambt van bijzonder hoogleraar Wetenschapscommunicatie, in het bijzonder betreffende de natuurkunde aan de Universiteit... Show moreOratie uitgesproken door Prof. dr. Ivo van Vulpen bij de aanvaarding van het ambt van bijzonder hoogleraar Wetenschapscommunicatie, in het bijzonder betreffende de natuurkunde aan de Universiteit Leiden op vrijdag 7 juni 2024 Show less
International trade has played a major role in defining the modern global economy. Trade, however, entangles the environmental pressures of economic sectors, giving the illusion of environmental... Show moreInternational trade has played a major role in defining the modern global economy. Trade, however, entangles the environmental pressures of economic sectors, giving the illusion of environmental improvements, while the opposite may be occurring. This dissertation explores the role of international trade on the environmental impacts of two sectors: the food system and the plastic waste system. For each system, this work finds that international trade leads to unwelcomed tradeoffs. Within the food system, in the form of consumption patterns that have been able to shift towards more land intensive diets. Adopting more autarkic food policies may help shift food consumption back towards diets that are more in line with planetary boundaries while also improving the efficiency of currently underdeveloped food supply chains. Within the plastic waste system, international trade has been detrimental by increasing plastic waste leaking to the aquatic environment, particularly from high-income countries. Recycling policies within these countries have amplified the quantities of plastic waste being exported to reach recycling metrics, ultimately highlighting the need for improved metrics to evaluate the environmental tradeoffs of plastic waste disposal. Show less
The mid-sixteenth century was a time of rapidly intensifying interest in the study of living nature. Networks of experts described a rapidly growing number of species, complementing descriptions... Show moreThe mid-sixteenth century was a time of rapidly intensifying interest in the study of living nature. Networks of experts described a rapidly growing number of species, complementing descriptions with ad vivum depictions. Since the increase in the number of known species soon called for an organisation of this information, to keep this accessible and navigable, naturalists experimented with classifications and the presentation of information in text and image. This dissertation explores questions about the management of knowledge and information specifically in the context of natural history, looking at a subfield of zoology, the study of fishes and other aquatic animals, as an example, taking as a point of departure the works published by the naturalist Conrad Gessner (1516-1565). Gessner aimed to incorporate into his works an overview of the state of knowledge. As a result his work presents an ideal case study from which to approach questions such as: What happens when a field of knowledge experiences a sudden influx of information? How is information made accessible, how do researchers keep the overview of an increasing quantity of information? How is rudimentary and incomplete information processed and presented, how does it affect established interpretations and methods of working? Show less
Political theological explorations of the international have mounted an important challenge to standard secularization narratives by drawing attention to the manner in which modern international... Show morePolitical theological explorations of the international have mounted an important challenge to standard secularization narratives by drawing attention to the manner in which modern international political thought has taken up and refashioned theological notions. However, there exists a certain danger of reducing the political theological move to the level of intellectualism. Explorations would benefit from attention to theology understood as an embodied form of understanding, as a way of life, and more specifically to the manner in which desire shapes understanding of and action within the world of international politics. This chapter details the intellectualist danger in two prominent, recent interjections regarding the political theology of the international, those of Seán Molloy and William Bain. Next it flags how two key critics of the political theological move, Mark Lilla and Hans Blumenberg, actually recognize the centrality of desire in human thought and action, while also noting the inadequacies of their accounts. It then highlights how the work of Charles Taylor and Talal Asad might inspire a political theology of the international that avoids the intellectualist danger by giving attention to desire. Show less
This thesis described the further development of the controlled human hookworm model and several applications of this model. First, the hookworm egg excretion is modelled over time using Bayesian... Show moreThis thesis described the further development of the controlled human hookworm model and several applications of this model. First, the hookworm egg excretion is modelled over time using Bayesian statistics, resulting in the description of a plateau phase in egg output. Repeated infections a re then investigated as a means to improve the accuracy and statistical power of this output as an outcome measure. The hereby established model is then applied in an immunization study, which shows that it is possible to develop a protective response against short-term larval infection. The skin phase and IgG1 seem to play a role in the development of this protection. Furthermore, gut microbiome changes during controlled hookworm infection are described. Also, volunteers’ motivations and decision making process are investigated, resulting in the characterization of controlled human infection participants as ‘deliberate decision-makers’ and not ‘money-oriented risk-takers’. Following up on the findings in the study described, the importance of a multidisciplinary approach for the improvement of controlled human infection trials is argued in the discussion, with several recommendations made for further collaborative efforts in order to maximise social and scientific output of these studies. Show less
Earlier detection of pancreatic cancer is necessary to improve its poor prognosis. Currently, screening of the general population is not feasible due to the relatively low lifetime risk. However,... Show moreEarlier detection of pancreatic cancer is necessary to improve its poor prognosis. Currently, screening of the general population is not feasible due to the relatively low lifetime risk. However, up to one in ten cases occur in individuals with a strong family history of germline mutation carriers, known as high-risk individuals (HRIs). For these HRIs, pancreatic cancer surveillance in expert centers is recommended. The first part of this thesis focuses on evaluating the effectiveness of pancreatic cancer surveillance in carriers of a germline CD2KNA/p16 mutation who have a very high lifetime risk of developing pancreatic cancer. The second part focuses on various aspects to improve pancreatic cancer surveillance programs, including the study of biomarkers, risk stratification, and assessment of psychosocial aspects. Finally, attention is given to the identification of individuals at increased risk from the general population. Show less
Colorectal cancer (CRC) screening programs have been established worldwide to prevent the development of CRC and to detect it early. CRC screening can be targeted at average- or high-risk... Show moreColorectal cancer (CRC) screening programs have been established worldwide to prevent the development of CRC and to detect it early. CRC screening can be targeted at average- or high-risk individuals. For average-risk individuals, the Dutch fecal immunochemical testing (FIT)-based CRC screening program was introduced in 2014, inviting all individuals aged 55-75 biennially. In Part I of this thesis, outcomes of the CRC screening program in the Netherlands are analyzed (i.e., CRC incidence, mortality, stage distribution, treatment). To optimize the balance between benefits and harms of CRC screening, risk stratification based on fecal hemoglobin concentrations after negative FIT could be the way forward. Part II describes the study protocol of a randomized controlled trail on personalized CRC screening and evaluates the information needs of the target population for personalized CRC screening strategies. For high-risk individuals, intensified CRC screening and surveillance may be needed, given these individuals have higher risk of developing CRC during their lifetime. Testicular cancer survivors treated with platinum-based chemotherapy can be considered high-risk individuals, as they have an increased risk of developing second primary gastrointestinal malignancies. Part III of this thesis explores the carcinogenesis of CRC and the yield of colonoscopy in these individuals. Show less
This thesis has found a balance between individual data protection rights and the free flow of data. On the one hand, this balance serves to protect the individual and his data. On the other hand,... Show moreThis thesis has found a balance between individual data protection rights and the free flow of data. On the one hand, this balance serves to protect the individual and his data. On the other hand, health care and health research must take place using personal data.A balanced approach can be found in the following four ways. Firstly, a broad(-er) interpretation of the lawful basis of consent can facilitate secondary health research. Secondly, the use of other lawful bases can be a solution for the legitimation of secondary health research. Furthermore, a separate legal ground for secondary research can be a solution to resolve the issue of a lawful basis for health research.Thirdly, a balance can be found in the individual’s autonomy vis-à-vis the accountability of the health institution and the attention drawn to the free flow of data. The focus is shifted from the individual’s control over his data towards the health institution with other lawful bases than consent and a fair balance between data protection rights and the free flow of data.Fourthly, a risk-based approach to monitoring compliance contributes to balancing the rights and interests of individuals with data sharing for health care and research. Show less
