The higher derivatives of motion are rarely discussed in the teaching of classical mechanics of rigid bodies; nevertheless, we experience the effect not only of acceleration, but also of jerk and snap. In this paper we will discuss the third and higher order derivatives of displacement with respect to time, using the trampolines and theme park roller coasters to illustrate this concept. We will also discuss the effects on the human body of different types of acceleration, jerk, snap and higher derivatives, and how they can be used in physics education to further enhance the learning and thus the understanding of classical mechanics concepts.

Lifetime measurements, based on the method of beam-foil spectroscopy, together with careful corrections for cascade effects, have in recent years yielded the line strength of the 2$s^2$ ${\mathrm{}}^1$S–2s2p ${\mathrm{}}^1$P° transition in Be-like ions with uncertainties ranging from 3.4% to 8.1% in Bei–O. By applying a method of isoelectronic smoothing of line strengths, similar to those earlier used for excitation energies and transition wavelengths, we have reduced the experimental uncertainties by about a factor of 2, to 1.9–3.6 % for these transitions. The fitted results are in excellent agreement with the best theoretical data. The applicability of this method to other isoelectronic sequences is briefly discussed.

We have used the beam-foil technique to measure the decay of the 3p ²P_1/2, ²P_3/2 and 3d²D_3/2, ²D_5/2 levels in Ar VIII and the 3s3p ¹P, 3s3d ¹D, 3p^{2 1}S, and ¹D levels in Ar VII. Applying the ANDC method of analysis, accurate lifetimes for the 3p ²P_1/2, ²P_3/2 and 3s3p ¹P levels have been determined. The corresponding oscillator strengths are found to be in very good agreement with theoretical values. A comparison between theoretical and experimental f-values for the resonance transitions in the Na I isoelectronic sequence is also presented.

Photoacoustic imaging (PAI) is a novel hybrid imaging technique that combines the advantages of optical and ultrasound imaging to produce hyperspectral images of the tissue. The feasibility of measuring oxygen saturation (sO₂) with PAI has been demonstrated pre-clinically, but has limited use in humans under conditions of ischemia and reperfusion. As an important step towards making PAI clinically available, we present a study in which PAI was used to estimate the spatial distribution of sO₂ in vivo during and after occlusion of the finger of eight healthy volunteers. The results were compared with a commercial oxygen saturation monitor based on diffuse reflectance spectroscopy. We here describe the capability of PAI to provide spatially resolved picture of the evolution of sO₂ during ischemia following vascular occlusion of a finger, demonstrating the clinical viability of PAI as a non-invasive diagnostic tool for diseases indicated by impaired microvascularization.