Toeval en onvermijdelijkheid

Rede, in verkorte vorm, uitgesproken ter gelegenheid van het aanvaarden van het ambt van bijzonder hoogleraar met als leeropdracht Gentherapie van Hematopoietische Cellen aan het Erasmus MC, faculteit van de Erasmus Universiteit Rotterdam, op 11 april 200

Analysis of Data to Evaluate the Performance of Air Filters Used for Filtering Nanoscale Particles Generated by Smoke

The main goal of this research project is to determine the effectiveness of commercially available air filters and to compare different kinds of commercially available air filters in certain categories. With recent record-breaking wildfires and the Covid-19 pandemic, research on the effects and features of nanoparticles has become increasingly important. Inhalation of nanoparticles in smoke can result in severe health effects on humans, affecting especially the respiratory system. As nanoparticles can pass through cell membranes, absorption occurs rapidly and affects many different parts and functions of the human body. While air filters are an effective method of reducing small-sized particles in flowing air, current filtration standards only apply to larger scaled microparticles, and filtration efficiencies for nanoparticles are often unknown. A good understanding of the effectiveness of air filters and masks is crucial to prevent inhalation of nanoparticles. Using a wind tunnel and two different types of woodsmokes, the penetration rates of nanoparticles through air filters were determined. Tests were performed with four different air filters using woodsmoke from hickory and applewood pallets. Due to outliers affecting mean and standard deviation values, a JavaScript code was written to eliminate outliers from the data sets. Trials with hickory smoke provided more consistent results than with applewood smoke. Average filtration effectiveness using hickory smoke was relatively close for all air filters at around 50%. Results from applewood smoke were relatively inconsistent. Due to a wide range of data and high standard deviations, effectiveness could not be established precisely

On Tools for Completeness of Kleene Algebra with Hypotheses

In the literature on Kleene algebra, a number of variants have been proposed which impose additional structure specified by a theory, such as Kleene algebra with tests (KAT) and the recent Kleene algebra with observations (KAO), or make specific assumptions about certain constants, as for instance in NetKAT. Many of these variants fit within the unifying perspective offered by Kleene algebra with hypotheses, which comes with a canonical language model constructed from a given set of hypotheses. For the case of KAT, this model corresponds to the familiar interpretation of expressions as languages of guarded strings. A relevant question therefore is whether Kleene algebra together with a given set of hypotheses is complete with respect to its canonical language model. In this paper, we revisit, combine and extend existing results on this question to obtain tools for proving completeness in a modular way. We showcase these tools by giving new and modular proofs of completeness for KAT, KAO and NetKAT, and we prove completeness for new variants of KAT: KAT extended with a constant for the full relation, KAT extended with a converse operation, and a version of KAT where the collection of tests only forms a distributive lattice

Prosocial behavior in students with intellectual disabilities: Individual level predictors and the role of the classroom peer context

Prosocial behavior at school, such as helping and sharing, contributes to positive individual development, peer relations, and classroom climate. Students with intellectual disabilities (ID) may have difficulty to demonstrate prosocial behavior, but little is known about the levels of prosocial behavior and its predictors in this population. This study aims to describe the prosocial behavior of students with ID attending special needs schools and related individual (i.e., age, sex, and general functioning) and classroom level (i.e., classmates’ mean prosocial behavior) predictors. School staff members assessed prosocial behavior of 1022 students with ID (69.5% boys; Mage = 11.34 years, SD = 3.73, range: 4–19 years) at the beginning and the end of a schoolyear. We found that students with ID on average demonstrated moderate levels of prosocial behavior, this was lower compared to norms of typically developing students. Correlations within each timepoint proved that prosocial behavior was more present in older students, girls, and students with higher general functioning. Using a longitudinal multilevel model, we found that, prosocial behavior increased more over the schoolyear in older students and in students with higher general functioning. Classmates’ mean levels of prosocial behavior did not affect later individual prosocial behavior. We conclude that prosocial behavior in students with ID depends on several individual characteristics, but less on the levels of prosocial behaviors in their special needs classroom peer context