A novel astronomical application for formation flying small satellites

OLFAR, Orbiting Low Frequency Antennas for Radio Astronomy, will be a space mission to observe the universe frequencies below 30 MHz, as it was never done before with an orbiting telescope. Because of the ionospheric scintillations below 30 MHz and the opaqueness of the ionosphere below 15 MHz, a space mission is the only opportunity for this as yet unexplored frequency range in radio astronomy. The frequency band is scientifically very interesting for exploring the early cosmos at high hydrogen redshifts, the so-called dark-ages and the epoch of reionization, the discovery of planetary and solar bursts in other solar systems, for obtaining a tomographic view of space weather, ultra-high energy cosmic rays and for many other astronomical areas of interest. Because of the low observing frequency the aperture size of the instrument must be in the order of 100 km. This requires a distributed space mission which is proposed to be implemented using formation flying of small satellites. The individual satellites are broken down in five major subsystems: the spacecraft bus, the antenna design, the frontend, backend and data transport. One of the largest challenges is the inter-satellite communication. In this paper the concept and design considerations of OLFAR are presented

Mechanical behaviour of the intervertebral disc under sustained compressive loading

Heethaar, R.M. [Promotor]Dieen, J.H. van [Promotor]Smit, T.H. [Copromotor]Mullender, M.G. [Copromotor

Making sense of interdisciplinarity in challenge-based learning:A two-step co-creation approach towards educational redesign

Challenge-based learning gains popularity in engineering education for allowing students to transcend academic and disciplinary boundaries and to fully engage in real-world problems, but it is largely underexplored how to improve specific designs of such educational practices to promote interdisciplinary learning experiences and competencies. This paper describes two studies that together in two steps make up an evidence-based redesign of a challenged-based course featuring group-work projects in an undergraduate program combining engineering with liberal arts and sciences. A first study based on observation and interviews collects different and varying learning experiences throughout students' learning activities. The results showed that interdisciplinary experiences are constructed in complex dynamics between students' disciplinary identity formation and the interdisciplinary and collaborative course configuration. Such dynamics may result in positive learning experiences (engagement and interdisciplinary enrichment) as well as negative ones (disengagement and frustration). Especially regarding the discrepancy between common experiences across the three phases of tackling the challenge (mapping, mitigating, integrating), representatives of parties important for the course were invited to a roundtable session in a second study to discuss and reflect on the first study's findings and what they can mean for the course design. Understandings achieved in the session are used as input for upcoming course redesign towards a more desirably organized challenge-based learning. The two-step approach towards redesign is an example of involving researchers and students in evidence-based educational redesign, exemplifying the value of naturalistic research and educational co-creation in understanding and optimizing students' learning experience to achieve fruitful challenge-based learning.</p

Oriënterend onderzoek naar de mogelijkheid om met behulp van NIRS het gehalte aan olie en y-linoleenzuur in teunisbloemzaad te bepalen

Nagaan of met behulp van NIRS het gehalte aan olie en y-linoleenzuur in teunisbloemzaad voldoende nauwkeurig te bepalen is. Van 21 monsters teunisbloemzaad zijn met behulp van verschillende rekenmethoden correlatieberekeningen uitgevoerd tussen de chemisch bepaalde gehalten aan olie en y-linoleenzuur en nabij- infarood reflectiewaarden van de monsters, gemeten bij 350 verschillende golflengten tussen 1100 en 2500 nm

Challenges in Clinicogenetic Correlations:One Phenotype – Many Genes

Background: In the field of movement disorders, what you see (phenotype) is seldom what you get (genotype). Whereas 1 phenotype was previously associated to 1 gene, the advent of next-generation sequencing (NGS) has facilitated an exponential increase in disease-causing genes and genotype-phenotype correlations, and the "one-phenotype-many-genes" paradigm has become prominent.Objectives: To highlight the "one-phenotype-many-genes" paradigm by discussing the main challenges, perspectives on how to address them, and future directions.Methods: We performed a scoping review of the various aspects involved in identifying the underlying molecular cause of a movement disorder phenotype.Results: The notable challenges are (1) the lack of gold standards, overlap in clinical spectrum of different movement disorders, and variability in the interpretation of classification systems; (2) selecting which patients benefit from genetic tests and the choice of genetic testing; (3) problems in the variant interpretation guidelines; (4) the filtering of variants associated with disease; and (5) the lack of standardized, complete, and up-to-date gene lists. Perspectives to address these include (1) deep phenotyping and genotype-phenotype integration, (2) adherence to phenotype-specific diagnostic algorithms, (3) implementation of current and complementary bioinformatic tools, (4) a clinical-molecular diagnosis through close collaboration between clinicians and genetic laboratories, and (5) ongoing curation of gene lists and periodic reanalysis of genetic sequencing data.Conclusions: Despite the rapidly emerging possibilities of NGS, there are still many steps to take to improve the genetic diagnostic yield. Future directions, including post-NGS phenotyping and cohort analyses enriched by genotype-phenotype integration and gene networks, ought to be pursued to accelerate identification of disease-causing genes and further improve our understanding of disease biology

The diagnostic value of clinical neurophysiology in hyperkinetic movement disorders:A systematic review

Introduction: To guide the neurologist and neurophysiologist with interpretation and implementation of clinical neurophysiological examinations, we aim to provide a systematic review on evidence of electrophysiological features used to differentiate between hyperkinetic movement disorders. Methods: A PRISMA systematic search and QUADAS quality evaluation has been performed in PubMed to identify diagnostic test accuracy studies comparing electromyography and accelerometer features. We included papers focusing on tremor, dystonia, myoclonus, chorea, tics and ataxia and their functional variant. The features were grouped as 1) basic features (e.g., amplitude, frequency), 2) the influence of tasks on basic features (e.g., entrainment, distraction), 3) advanced analyses of multiple signals, 4) and diagnostic tools combining features. Results: Thirty-eight cross-sectional articles were included discussing tremor (n = 28), myoclonus (n = 5), dystonia (n = 5) and tics (n = 1). Fifteen were rated as ‘high quality’. In tremor, the basic and task-related features showed great overlap between clinical tremor syndromes, apart from rubral and enhanced physiological tremor. Advanced signal analyses were best suited for essential, parkinsonian and functional tremor, and cortical, non-cortical and functional jerks. Combinations of electrodiagnostic features could identify essential, enhanced physiological and functional tremor. Conclusion: Studies into the diagnostic accuracy of electrophysiological examinations to differentiate between hyperkinetic movement disorders have predominantly been focused on clinical tremor syndromes. No single feature can differentiate between them all; however, a combination of analyses might improve diagnostic accuracy

Dutch nature conservation objectives from a European perspective

In Dutch policy the European importance of species and habitats is one of the reasons to decide if a species or habitat should become a target species for Dutch policy. This study reviews the different philosophies behind previous studies on the international or European importance of Dutch species and habitats. It furthermore analysis the consequences of changing the criteria or thresholds for determining species of European importance for the number and type of species selected