Learning to live with ghosts:The practice of research

This research engages with the age-old existential questions that have preoccupied philosophy from its beginning: How to live? How to die? In dialogue with, first and foremost, the work of Jacques Derrida, I attempt to describe the tension that arises when, becoming ill, these general questions become particular and come to matter personally. Parallel to this research, I was diagnosed with an incurable auto-immune disorder, which required me to prepare for death, or a lung transplant—which I received in 2017. How to continue practicing philosophical thought while ill, when the body is foregrounded by continuous practical concerns? Using a phenomenological approach and deviating from the norms and conventions of academic discourse, this research makes a hauntological intervention into philosophy, from its spectral margins, from my sick-bed. As such, it looks at what thinking as a practice and experience entails, and under what conditions it is made possible. With texts by Virginia Woolf, Mary Wollstonecraft Shelley, Edgar Allan Poe, Annie Ernaux, M. NourbeSe Philip, and others, it argues for the presence of literature and poetry in and as philosophical thinking—as an alternative method to engage in the questions of life (and death), always as lived experiences, rather than as object of knowledge. This research concludes with On Wards, an experimental work of autobiographical fiction about the experience of having survived, thanks to organ donation

BCS-BEC crossover in a strongly correlated Fermi gas

We study the BCS-BEC crossover in the strongly correlated regime of an ultra-cold rotating two component Fermi gas. Strong correlations are shown to generate an additional long-range interaction which results in a modified crossover region compared to the non-rotating situation. The two-particle correlation function reveals a smooth crossover between the s-wave paired fermionic fractional quantum Hall state and the bosonic Laughlin state.Comment: 4 pages, 3 figure

Feshbach resonances in 3He*-4He* mixtures

We discuss the stability of homonuclear and heteronuclear mixtures of 3He and 4He atoms in the metastable 2^3S_1 state (He*) and predict positions and widths of Feshbach resonances by using the Asymptotic Bound-state Model (ABM). All calculations are performed without fit parameters, using \emph{ab-initio} calculations of molecular potentials. One promising very broad Feshbach resonance (\Delta B=72.9^{+18.3}_{-19.3} mT) is found that allows for tuning of the inter-isotope scattering length.Comment: 12 pages, 7 figure

Asymptotic Bound-state Model for Feshbach Resonances

We present an Asymptotic Bound-state Model which can be used to accurately describe all Feshbach resonance positions and widths in a two-body system. With this model we determine the coupled bound states of a particular two-body system. The model is based on analytic properties of the two-body Hamiltonian, and on asymptotic properties of uncoupled bound states in the interaction potentials. In its most simple version, the only necessary parameters are the least bound state energies and actual potentials are not used. The complexity of the model can be stepwise increased by introducing threshold effects, multiple vibrational levels and additional potential parameters. The model is extensively tested on the 6Li-40K system and additional calculations on the 40K-87Rb system are presented.Comment: 13 pages, 8 figure

Pertussis in children in Bloemfontein, South Africa: A 7-year retrospective review

Background. Pertussis vaccination in the 1950s was associated with a decrease in the incidence of pertussis. A resurgence of pertussis has been documented, mainly in well-resourced countries since the 1990s. The burden of pertussis has not been well described in South Africa (SA). Epidemiological data are important for rational implementation of vaccination strategies.Objective. To describe the morbidity and mortality of children with pertussis admitted to public sector hospitals in Bloemfontein, SA.Methods. A retrospective descriptive hospital-based study of children diagnosed with pertussis by polymerase chain reaction testing from April 2008 to March 2015.Results. One hundred and eighty-three laboratory results confirmed pertussis; 105/183 children (57.4%) were <18 weeks old. Clinical data, available for 154/183 cases (84.2%), showed that 141/154 children (91.6%) were admitted to hospital, of whom one-third required intensive care. Hospital admission was associated with young age (p<0.001). The median hospital stay was 9.0 days (interquartile range 6 - 14.5), and hospital stay was longer for children aged <18 weeks than for those aged ≥18 weeks (p=0.006; 95% confidence interval 1 - 5 days). Of the 154 children, 139 (90.3%) had a cough, which lasted ≤7 days in 110/137 cases (80.3%). The total white cell count was ≥20.0 × 109/L in 58/144 cases (40.3%). Eight children (5.2%) died.Conclusions. This case series highlights the importance of pertussis as a problem in children. Most children had a history of cough lasting ≤7 days. Young infants were most severely affected, requiring prolonged hospital stay, often with admission to a paediatric intensive care unit.

Hotspot Zuidplaspolder: Climate adaptation in the Zuidplaspolder

Building at the lowest point in the Netherlands, in the Zuidplaspolder, is viewed as a challenge and not something that is impossible. The Xplorelab approach in the Hotspot Zuidplaspolder project is a combination of research, implementation of ideas into inspiring examples and evaluation

Pertussis in children in Bloemfontein, South Africa: A 7-year retrospective review

Background. Pertussis vaccination in the 1950s was associated with a decrease in the incidence of pertussis. A resurgence of pertussis has been documented, mainly in well-resourced countries since the 1990s. The burden of pertussis has not been well described in South Africa (SA). Epidemiological data are important for rational implementation of vaccination strategies.Objective. To describe the morbidity and mortality of children with pertussis admitted to public sector hospitals in Bloemfontein, SA.Methods. A retrospective descriptive hospital-based study of children diagnosed with pertussis by polymerase chain reaction testing from April 2008 to March 2015.Results. One hundred and eighty-three laboratory results confirmed pertussis; 105/183 children (57.4%) were <18 weeks old. Clinical data, available for 154/183 cases (84.2%), showed that 141/154 children (91.6%) were admitted to hospital, of whom one-third required intensive care. Hospital admission was associated with young age (p<0.001). The median hospital stay was 9.0 days (interquartile range 6 - 14.5), and hospital stay was longer for children aged <18 weeks than for those aged ≥18 weeks (p=0.006; 95% confidence interval 1 - 5 days). Of the 154 children, 139 (90.3%) had a cough, which lasted ≤7 days in 110/137 cases (80.3%). The total white cell count was ≥20.0 × 109/L in 58/144 cases (40.3%). Eight children (5.2%) died.Conclusions. This case series highlights the importance of pertussis as a problem in children. Most children had a history of cough lasting ≤7 days. Young infants were most severely affected, requiring prolonged hospital stay, often with admission to a paediatric intensive care unit

Feshbach spectroscopy and scattering properties of ultracold Li+Na mixtures

We have observed 26 interspecies Feshbach resonances at fields up to 2050 G in ultracold $^6$Li+$^{23}$Na mixtures for different spin-state combinations. Applying the asymptotic bound-state model to assign the resonances, we have found that most resonances have d-wave character. This analysis serves as guidance for a coupled-channel calculation, which uses modified interaction potentials to describe the positions of the Feshbach resonances well within the experimental uncertainty and to calculate their widths. The scattering length derived from the improved interaction potentials is experimentally confirmed and deviates from previously reported values in sign and magnitude. We give prospects for $^7$Li+$^{23}$Na and predict broad Feshbach resonances suitable for tuning.Comment: 8 pages, 4 figures, version as published in PR

Broad Feshbach resonance in the 6Li-40K mixture

We study the widths of interspecies Feshbach resonances in a mixture of the fermionic quantum gases 6Li and 40K. We develop a model to calculate the width and position of all available Feshbach resonances for a system. Using the model we select the optimal resonance to study the 6Li/40K mixture. Experimentally, we obtain the asymmetric Fano lineshape of the interspecies elastic cross section by measuring the distillation rate of 6Li atoms from a potassium-rich 6Li/40K mixture as a function of magnetic field. This provides us with the first experimental determination of the width of a resonance in this mixture, Delta B=1.5(5) G. Our results offer good perspectives for the observation of universal crossover physics using this mass-imbalanced fermionic mixture.Comment: 4 pages, 2 figure