A macroscopic model for sessile droplet evaporation on a flat surface

The evaporation of sessile droplets on a flat surface involves a complex interplay between phase change, diffusion, advection and surface forces. In an attempt to significantly reduce the complexity of the problem and to make it manageable, we propose a simple model hinged on a surface free energy-based relaxation dynamics of the droplet shape, a diffusive evaporation model and a contact line pinning mechanism governed by a yield stress. Our model reproduces the known dynamics of droplet shape relaxation and of droplet evaporation, both in the absence and in the presence of contact line pinning. We show that shape relaxation during evaporation significantly affects the lifetime of a drop. We find that the dependence of the evaporation time on the initial contact angle is a function of the competition between the shape relaxation and evaporation, and is strongly affected by any contact line pinning.Comment: 13 pages, 8 figure

The relevance of schizotypal traits for understanding interpersonal functioning in adolescents with psychiatric problems.

A

Compound redistribution due to droplet evaporation on a thin polymeric film: theory

A thin polymeric film in contact with a fluid body may leach low-molecular-weight compounds into the fluid. If this fluid is a small droplet, the compound concentration within the liquid increases due to ongoing leaching in combination with the evaporation of the droplet. This may eventually lead to an inversion of the transport process and a redistribution of the compounds within the thin film. In order to gain an understanding of the compound redistribution, we apply a macroscopic model for the evaporation of a droplet and combine that with a diffusion model for the compound transport. In the model, material deposition and the resulting contact line pinning are associated with the precipitation of a fraction of the dissolved material. We find three power law regimes for the size of the deposit area as a function of the initial droplet size, dictated by the competition between evaporation, diffusion and the initial compound concentrations in the droplet and the thin film. The strength of the contact line pinning determines the deposition profile of the precipitate, characterised by a pronounced edge and a linearly decaying profile towards the centre of the stain. Our predictions for the concentration profile within the solid substrate resemble patterns found experimentally.Comment: 12 pages, 10 figure

Time-of-flight estimation based on covariance models

We address the problem of estimating the time-of-flight (ToF) of a waveform that is disturbed heavily by additional reflections from nearby objects. These additional reflections cause interference patterns that are difficult to predict. The introduction of a model for the reflection in terms of a non-stationary auto-covariance function leads to a new estimator for the ToF of an acoustic tone burst. This estimator is a generalization of the well known matched filter. In many practical circumstances, for instance beacon-based position estimation in indoor situations, lack of knowledge of the additional reflections can lead to large estimation errors. Experiments show that the application of the new estimator can reduce these errors by a factor of about four. The cost of this improvement is an increase in computational complexity by a factor of about seven

Competitiveness at Leiden University

Proceeding of: Strategies for International Excellence of European Research Universities. Sharing best practices. April 16, 2010. Getafe, Madri

On estimating the size of overcoverage with the latent class model. A critique of the paper "Population Size Estimation Using Multiple Incomplete Lists with Overcoverage" by di Cecco, di Zio, Filipponi and Rocchetti (2018, JOS 34 557-572)

We read with interest the article by di Cecco et al. (2018), but have reservations about the usefulness of the latent class model specifically for estimating overcoverage. In particular, we question the interpretation of the parameters of the fitted latent class model.Comment: 5 page

Customization and personalization in clinical pathways using a modular perspective

C

On the use of positive test strategies when diagnosing mental disorders

Background: Despite the adverse impact diagnostic errors can have, clinical interviewing and decision-making in psychiatric practice have received relatively little empirical attention. When diagnosing patients, clinicians tend to fall back on a specific (heuristic) rule of thumb, the positive test strategy, a confirmatory approach that increases the risk of confirmation bias. Method and results: A group of 83 clinical psychologists and psychiatrists was asked to give their diagnostic hypotheses about two vignettes. We found them to self-generate significantly (i.e., p < .01; d = 1.57) more confirming than disconfirming questions to test their initial diagnostic impressions, with supervisors considering significantly more differential diagnoses than the less experienced post-grads/residents. When offered a list of 100 potentially relevant diagnostic queries, the supervisors selected fewer confirming and proportionally more disconfirming themes. Conclusions: Our results demonstrate that irrespective of clinical experience mental-health clinicians indeed tend to use a confirmatory thinking style that contrasts with the stricter principle of falsification. More field-based research on this topic is needed, as well as studies probing whether a systematized diagnostic approach is feasible in psychiatric practice and increases diagnostic accuracy and patient satisfaction