This special issue of the Journal of Demographic Economics contains 10 contributions to the academic literature all dealing with longevity risk and capital markets. Draft versions of the papers were presented at Longevity 16: The Sixteenth International Longevity Risk and Capital Markets Solutions Conference that was held in Helsingør near Copenhagen on 13–14 August 2021. It was hosted by PerCent at Copenhagen Business School and the Pensions Institute at City, University of London.

It is well-known that marital status is an important predictor for life expectancy. However, non-married individuals are often misclassified as singles which ignores the heterogeneity within the group. This paper shows the importance of distinguishing between types of singles, and in particular whether they are cohabiting, when predicting life expectancies. We use unique and detailed longitudinal register data to track marital status throughout the individual's lifetime. We find that all types of singles consistently benefit from living with a spouse, i.e., after divorce, becoming widower or being never married. This result holds for both men and women. For certain types of cohabiting singles we reject significant differences in life expectancy compared to married individuals. Finally, we use a case study to show that, like married individuals, all types of singles that cohabit also serve as informal caregivers and have the potential to limit the end-of-life long-term care expenditure levels.

Numerical simulations of the interaction of internal solitary waves (ISWs) of opposite polarity are conducted by solving the incompressible Euler equations under the Boussinesq approximation. A double-pycnocline stratification is used. A method to determine when ISWs of both polarities exist is also presented. The simulations confirm previous work that the interaction of waves of the same polarity are soliton-like; however, here it is shown that when a fast ISW with the same polarity as a Korteweg–de Vries (KdV) solitary wave catches up and interacts with a slower ISW of opposite polarity, the interaction can be far from soliton-like. The energy in the fast KdV-polarity wave can increase by more than a factor of 5 while the energy in the slower negative-KdV-polarity wave can decrease by 50 %. Large trailing wave trains may be generated and in some cases multiple ISWs with KdV polarity may be formed by the interaction.

Research into the responses of hens on perches is important in order to assess the welfare impact of alternative systems for egg production which incorporate perches in their design. Previous studies suggest that many flight and landing accidents occur in such systems as birds attempt to move between perches and facilities, resulting in a high incidence of bone breakage. In this study three horizontal perches were set with a gradient between them of 0, 30, 45 or 60 degrees according to treatment. Four groups of 15 ISABrown laying hens were individually exposed to each treatment, being placed on the uppermost perch (Perch 1) with a food reward available at the lowest perch (Perch 3). Behaviours performed before reaching Perch 3 were recorded over time. More birds failed to move to Perch 3 in 10 minutes when perches were separated by 45 or 60 degrees. In birds which stayed on the perches for the full 10 minutes, without reaching Perch 3, downward head movements, calling, intended jump behaviours, side-stepping and wing-flapping decreased significantly with time spent on the perches. Motivation to complete the task, in order to gain the food reward, was high in all treatments. However, when birds found perches difficult to negotiate, behaviours indicating intention to move to the food decreased with time and the incidence of behaviours indicating frustration and thwarting increased. In non-cage systems such frustration could reduce bird welfare.

Non-cage systems for housing laying hens often incorporate a framework of perches, allowing birds to move in three dimensions. Wood is predominantly used for perch construction, because it is relatively cheap and easy to work with. However, wooden perches are difficult to clean and disinfect, which could lead to disease and discomfort for the birds using them. The objectives of this study were to identify which characteristics of perch design are preferred by laying hens; and to test whether birds would use perches of alternative materials for a comparable amount of time as they use wooden perches. Six laying hens were housed individually in litter-floored pens and were offered a choice of three pairs of contrasting perch types (experiments 1-3): a rectangular, wooden perch (‘control’) versus two, thin, parallel, rectangular wooden perches; ‘control’ versus a similar perch covered with foam and fabric; and ‘control’ versus a round, wooden perch. Birds were given each pair of perches twice, controlling for perch position in the pen. Time spent on each perch in a 48h period was determined from video records. Preferences were then tested in consecutive trials (experiments 4-5) between perches of the following materials: wood versus plastic versus steel; and wood versus textured aluminium. There were no significant differences in time spent on different perches, suggesting that birds had no preferences between perch types. The implications of these results could be important for the design of alternative systems for laying hens. Birds may be content to perch on artificial materials which could be more hygienic than wood and easier to maintain in a commercial system.

The effects of along-shelf barotropic geostrophic currents on internal wave generation by the $K_1$ tide interacting with a shelf at near-critical latitudes are investigated. The horizontal shear of the background current results in a spatially varying effective Coriolis frequency which modifies the slope criticality and potentially creates blocking regions where freely propagating internal tides cannot exist. This paper is focused on the barotropic to baroclinic energy conversion rate, which is affected by a combination of three factors: slope criticality, size and location of the blocking region where the conversion rate is extremely small and the internal tide (IT) beam patterns. All of these are sensitive to the current parameters. In our parameter space, the current can increase the conversion rate up to 10 times.

For temperatures near the temperature of maximum density, 3.98 $^{\circ }$C for freshwater, the nonlinearity of the equation of state plays an important role in the density driven dynamics. In this study, we demonstrate that the nonlinear equation of state can lead to large scale differences in the spatial and temporal evolution of freshwater gravity currents when intruding and ambient temperatures are below the temperature of maximum density. The results of this study show that when the temperature of the intruding fluid decreases throughout the evolution of the gravity current, the density difference between the intrusion and the ambient decreases rapidly. When the temperature of intruding fluid increases throughout the evolution of the gravity current, the density difference decreases at a slower rate. The differing rates at which the density difference decreases lead to asymmetries in head location, and vertical extent of intruding fluid, and may have implications for larger scale flows in this temperature regime. These results are robust across the Grashof numbers studied.

In a three-layer system, weakly nonlinear theory predicts that breathers exist under certain conditions which, under the Boussinesq approximation, include symmetric stratifications in which the density jump across each interface is the same and the upper and lower layer thicknesses are equal and less than 9/26 of the total water depth. The existence and characteristics of fully nonlinear breathers in this symmetric stratification are poorly understood. Therefore, this study investigates fully nonlinear breathers in a three-layer symmetric stratification in order to clarify their characteristics by making direct comparisons between numerical simulation results and theoretical solutions. A normalization of the breather profiles is introduced using theoretical solutions of a breather and a new energy scale is proposed to evaluate their potential and kinetic energy. We apply fully nonlinear and strongly dispersive internal wave equations in a three-layer system using a variational principle. The computational results show that the larger the amplitude, the shorter the length of the envelope of breathers, which agrees with the theoretical solution. However, breathers based on the theoretical solutions cannot progress without deformation and decay due to the emission of short small-amplitude internal waves. Furthermore we demonstrate that the shedding of larger amplitude waves occurs, and the amplitude of the envelope decays more strongly when the density interface crosses the critical depth where the ratio of the upper layer thickness and the total water depth is 9/26 suggesting a limiting amplitude for fully nonlinear breathers.

This paper examines the velocity distribution function and cyclotron resonance conditions for a beam of electrons moving in a magnetic field which gradually changes with time. A spatial gradient of magnetic field is known to result in an unstable horseshoe distribution of electrons. The field gradient in time adds additional effects due to an induced electric field. The resultant anisotropic velocity distribution function, which we call a Luvdisk distribution, has some distinctive properties when compared to the horseshoe. Fitting the cyclotron resonance condition circle shows that the frequency of the resultant emission is under the local cyclotron frequency. While the spatial gradient results in the emission coming almost perpendicularly to the field, the direction of the radiation under a time-changing field has more variability. The Luvdisk distribution also arises when the magnetic field has a gradient both in space and time. The beam can be unstable if those gradients are added or subtracted from each other (if the gradients are of equal or different sign), which occurs even when the total change of magnetic field is negative. While the frequency of the emission is related to the final magnetic field value, its direction is indicative of the field’s history which produced the instability.

The Danish and the Dutch pension systems are often referred to as “among the best in the world”. We compare pension systems and pension products in Denmark and The Netherlands. We focus on the shifts that have taken place in both countries, from pension products with relatively low levels of risk for the participant to pension products with more risk but also higher expected return. We end by drawing lessons that are relevant for discussions in many countries.

Large internal solitary waves with subsurface cores have recently been observed in the South China Sea. Here fully nonlinear solutions of the Dubreil–Jacotin–Long equation are used to study the conditions under which such cores exist. We find that the location of the cores, either at the surface or below the surface, is largely determined by the sign of the vorticity of the near-surface background current. The results of a numerical simulation of a two-dimensional shoaling internal solitary wave are presented which illustrate the formation of a subsurface core.

This paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 625, 51 (2005)] who argued that the cyclotron-maser instability occurs in localized magnetized collisionless shocks such as those expected in blazar jets. We report on recent research carried out to investigate electron acceleration at collisionless shocks and maser radiation associated with the accelerated electrons. We describe how electrons accelerated by lower-hybrid waves at collisionless shocks generate cyclotron-maser radiation when the accelerated electrons move into regions of stronger magnetic fields. The electrons are accelerated along the magnetic field and magnetically compressed leading to the formation of an electron velocity distribution having a horseshoe shape due to conservation of the electron magnetic moment. Under certain conditions the horseshoe electron velocity distribution function is unstable to the cyclotron-maser instability [Bingham and Cairns, Phys. Plasmas 7, 3089 (2000); Melrose, Rev. Mod. Plasma Phys. 1, 5 (2017)].

Objective: The objective of this study was to evaluate the impact of directed and sustained attention on the allocation of visuospatial attention. Healthy people often have left lateral and upward vertical spatial attentional biases. However, it is not known whether there will be an increase in bias toward the attended portion of the stimulus when volitional spatial attention is allocated to a portion of a stimulus, whether there are asymmetrical spatial alterations of these biases, and how sustained attention influences these biases. Methods: We assessed spatial bias in 36 healthy, right-handed participants using a variant of horizontal and vertical line bisections. Participants were asked to focus on one or the other end of vertical or horizontal lines or entire vertical or horizontal lines, and then to bisect the line either immediately or after a 20 second delay. Results: We found a significant main effect of attentional focus and an interaction between attentional focus and prolonged viewing with delayed bisection. Focusing on a certain portion of the line resulting in a significant deviation toward the attended portion and prolonged viewing of the line prior to bisection significantly enhanced the degree of deviation toward the attended portion. Conclusions: The enhanced bias with directed and sustained attention may be useful modifications of the line bisection test, particularly in clinical populations. Thus, future studies should determine whether prolonged viewing with delayed bisection and spatially focused attention reveals attentional biases in patients with hemispheric lesions who perform normally on the traditional line bisection test. (JINS, 2019, 25, 65–71)

Magnetic field measurements in turbulent plasmas are often difficult to perform. Here we show that for ${\geqslant}$kG magnetic fields, a time-resolved Faraday rotation measurement can be made at the OMEGA laser facility. This diagnostic has been implemented using the Thomson scattering probe beam and the resultant path-integrated magnetic field has been compared with that of proton radiography. Accurate measurement of magnetic fields is essential for satisfying the scientific goals of many current laser–plasma experiments.

The Dakota skipper, Hesperia dacotae (Skinner, 1911) (Lepidoptera: Hesperiidae), is an at-risk butterfly that inhabits mesic mixed-grass prairie. Loss of native prairie is the main factor driving declines in Dakota skipper abundance. Currently, there is little knowledge on the environmental and habitat requirements of Saskatchewan, Canada populations. Our objective was to determine environmental associations of Dakota skipper in Saskatchewan through landscape, vegetation, soil, climate, microclimate, and Hesperiidae butterfly occupancy. Data collection was conducted in 2015 and 2016; a total of 46 sites were surveyed; nine of these were Dakota skipper positive (i.e., present) sites and 37 were negative (i.e., non-detected) sites. Results indicate that plant composition is not a significant predictor of Dakota skipper presence, but three plant species are significantly associated with the species; Pediomelum argophyllum (Pursh) Grimes (Fabaceae), Zizia aptera (Gray) Fernald (Apiaceae), and Schizachyrium scoparium (Michaux) Nash (Poaceae). No soil or climate variables were significant predictors of Dakota skipper presence; however it is significantly associated with steep slopes. Warmer maximum and average ground-level temperatures are also associated with Dakota skipper presence. Findings indicate that additional Dakota skipper populations are likely in Saskatchewan and future targeted surveys will allow for a full evaluation of the distribution of this species and conservation status.

The physics of compressible turbulence in high energy density (HED) plasmas is an unchartered experimental area. Simulations of compressible and radiative flows relevant for astrophysics rely mainly on subscale parameters. Therefore, we plan to perform turbulent hydrodynamics experiments in HED plasmas (TurboHEDP) in order to improve our understanding of such important phenomena for interest in both communities: laser plasma physics and astrophysics. We will focus on the physics of supernovae remnants which are complex structures subject to fluid instabilities such as the Rayleigh–Taylor and Kelvin–Helmholtz instabilities. The advent of megajoule laser facilities, like the National Ignition Facility and the Laser Megajoule, creates novel opportunities in laboratory astrophysics, as it provides unique platforms to study turbulent mixing flows in HED plasmas. Indeed, the physics requires accelerating targets over larger distances and longer time periods than previously achieved. In a preparatory phase, scaling from experiments at lower laser energies is used to guarantee the performance of future MJ experiments. This subscale experiments allow us to develop experimental skills and numerical tools in this new field of research, and are stepping stones to achieve our objectives on larger laser facilities. We review first in this paper recent advances in high energy density experiments devoted to laboratory astrophysics. Then we describe the necessary steps forward to commission an experimental platform devoted to turbulent hydrodynamics on a megajoule laser facility. Recent novel experimental results acquired on LULI2000, as well as supporting radiative hydrodynamics simulations, are presented. Together with the development of LiF detectors as transformative X-ray diagnostics, these preliminary results are promising on the way to achieve micrometric spatial resolution in turbulent HED physics experiments in the near future.