Visualizing the electron's quantization with a ruler.

More than 100 years ago, Robert Millikan demonstrated the quantization of the electron using charged, falling droplets, but the statistical analysis on many falling droplets did not allow a direct visualization of the quantization of charge. Instead of letting the droplets fall, we have used optical levitation to create a single droplet version of Millikan's experiment where the effects of a single electron removal can be observed by the naked eye and measured with a ruler. As we added charges to the levitated droplet, we observed that its equilibrium position jumped vertically in quantized steps.

Visualization of spherical aberration using an optically levitated droplet as a light source.

Optical aberrations can greatly distort the image created by an optical element. Several aberrations can affect the image simultaneously and discerning or visualizing specific aberrations can be difficult. By making use of an optically levitated droplet as a light source, we have visualized the spherical aberration and coma of a lens.

The effect of a terrorist attack on emergency department inflow: an observation study using difference-in-differences methodology.

Study Objective: The objective of this study was to investigate how the terrorist attack in Stockholm, Sweden affected patient inflow to the general emergency departments (EDs) in close proximity of the attack. The study analyzed if, and to what extent, the attack impacted ED inflow during the following days and weeks.

Methods: In a retrospective observational study, anonymized aggregated data on ED arrivals (inflow of patients) to all seven of the EDs in the Stockholm County was analyzed using the Difference-in-Differences (DiD) estimator.

Safe Experimentation in Optical Levitation of Charged Droplets Using Remote Labs.

The work presents an experiment that allows the study of many fundamental physical processes, such as photon pressure, diffraction of light or the motion of charged particles in electrical fields. In this experiment, a focused laser beam pointing upwards levitate liquid droplets. The droplets are levitated by the photon pressure of the focused laser beam which balances the gravitational force.