Motivating consumers to make better financial decisions through behavioural economics

To celebrate 10 years of the Department of Management, we explore how our research is making a difference. David De-Meza and Diane Reyniers’ study into the mis-selling of financial products contributed to a shift in the way the UK’s financial regulator protects consumers

Evidence that waste aversion begets insurance aversion

Paying an insurance premium but not needing to claim is sometimes viewed as pouring money down the drain. Aversion to the perceived waste may lead to the rejection of fair insurance. Although policies paying rebates if no claim is made are not attractive to expected utility maximisers, this paper finds strong evidence they appeal to waste averters.

Two sets of bias-corrected regional UK Climate Projections 2018 (UKCP18) of temperature, precipitation and potential evapotranspiration for Great Britain

The United Kingdom Climate Projections 2018 (UKCP18) regional climate model (RCM) 12 km regional perturbed physics ensemble (UKCP18-RCM-PPE) is one of the three strands of the latest set of UK national climate projections produced by the UK Met Office. It has been widely adopted in climate impact assessment. In this study, we report biases in the raw UKCP18-RCM simulations that are significant and are likely to deteriorate impact assessments if they are not adjusted. Two methods were used to bias-correct UKCP18-RCM: non-parametric quantile mapping using empirical quantiles and a variant developed for the third phase of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) designed to preserve the climate change signal. Specifically, daily temperature and precipitation simulations for 1981 to 2080 were adjusted for the 12 ensemble members. Potential evapotranspiration was also estimated over the same period using the Penman-Monteith formulation and then bias-corrected using the latter method. Both methods successfully corrected biases in a range of daily temperature, precipitation and potential evapotranspiration metrics, and reduced biases in multi-day precipitation metrics to a lesser degree. An exploratory analysis of the projected future changes confirms the expectation of wetter, warmer winters and hotter, drier summers, and shows uneven changes in different parts of the distributions of both temperature and precipitation. Both bias-correction methods preserved the climate change signal almost equally well, as well as the spread among the projected changes. The change factor method was used as a benchmark for precipitation, and we show that it fails to capture changes in a range of variables, making it inadequate for most impact assessments. By comparing the differences between the two bias-correction methods and within the 12 ensemble members, we show that the uncertainty in future precipitation and temperature changes stemming from the climate model parameterisation far outweighs the uncertainty introduced by selecting one of these two bias-correction methods. We conclude by providing guidance on the use of the bias-corrected data sets. The data sets bias adjusted with ISIMIP3BA are publicly available in the following repositories: https://doi.org/10.5281/zenodo.6337381 for precipitation and temperature (Reyniers et al., 2022a) and https://doi.org/10.5281/zenodo.6320707 for potential evapotranspiration (Reyniers et al., 2022b) . The datasets bias-corrected using the quantile mapping method are available at https://doi.org/10.5281/zenodo.8223024 (Zha et al., 2023)

A Spectroscopic and Photometric Study of the Metal-Poor, Pulsating, Post-AGB Binary HD 46703

The metal-poor post-AGB star HD 46703 is shown to be a single-line spectroscopic binary with a period of 600 days, a high velocity of -94 km/s, and an orbital eccentricity of 0.3. Light curve studies show that it also pulsates with a period of 29 days. High-resolution, high signal-to-noise spectra were used for a new abundance study. The atmospheric model determined is T(eff) = 6250 K, log(g) = 1.0, V(t) = 3.0 km/s, and a metal abundance of [M/H] = -1.5. A low carbon abundance and lack of s-process element enhancement indicate that the star has not experienced third dredge-up on the AGB. The sulfur and zinc abundances are high compared with iron, and the chemical abundances show a clear anti-correlation with condensation temperature. The abundance depletion pattern is similar to that seen in other post-AGB binaries, and, like them, is attributed to the chemical fractionation of refractory elements onto dust stored in a circumbinary disk and the re-accretion of volatiles in the stellar atmosphere. The infrared excess is small but the excess energy distribution is very similar to what can expected from a disk. HD 46703 joins the growing list of depleted, post-AGB stars which are likely surrounded by a dusty and stable circumbinary disk.Comment: Machine readable files not include

Projected changes in droughts and extreme droughts in Great Britain strongly influenced by the choice of drought index

Droughts cause enormous ecological, economical and societal damage, and they are already undergoing changes due to anthropogenic climate change. The issue of defining and quantifying droughts has long been a substantial source of uncertainty in understanding observed and projected trends. Atmosphere-based drought indicators, such as the Standardised Precipitation Index (SPI) and the Standardised Precipitation Evapotranspiration Index (SPEI), are often used to quantify drought characteristics and their changes, sometimes as the sole metric representing drought. This study presents a detailed systematic analysis of SPI- and SPEI-based drought projections and their differences for Great Britain (GB), derived from the most recent set of regional climate projections for the United Kingdom (UK). We show that the choice of drought indicator has a decisive influence on the resulting projected changes in drought frequency, extent, duration and seasonality using scenarios that are 2 and 4 ∘C above pre-industrial levels. The projected increases in drought frequency and extent are far greater based on the SPEI than based on the SPI. Importantly, compared with droughts of all intensities, isolated extreme droughts are projected to increase far more with respect to frequency and extent and are also expected to show more pronounced changes in the distribution of their event durations. Further, projected intensification of the seasonal cycle is reflected in an increasing occurrence of years with (extremely) dry summers combined with wetter-than-average winters. Increasing summer droughts also form the main contribution to increases in annual droughts, especially using the SPEI. These results show that the choice of atmospheric drought index strongly influences the drought characteristics inferred from climate change projections, with a comparable impact to the uncertainty from the climate model parameters or the warming level; therefore, potential users of these indices should carefully consider the importance of potential evapotranspiration in their intended context. The stark differences between SPI- and SPEI-based projections highlight the need to better understand the interplay between increasing atmospheric evaporative demand, moisture availability and drought impacts under a changing climate. The region-dependent projected changes in drought characteristics by two warming levels have important implications for adaptation efforts in GB, and they further stress the need for rapid mitigation

IRAS\,11472-0800: an extremely depleted pulsating binary post-AGB star

We focus here on one particular and poorly studied object, IRAS11472-0800. It is a highly evolved post-Asymptotic Giant Branch (post-AGB) star of spectral type F, with a large infrared excess produced by thermal emission of circumstellar dust. We deploy a multi-wavelength study which includes the analyses of optical and IR spectra as well as a variability study based on photometric and spectroscopic time-series. The spectral energy distribution (SED) properties as well as the highly processed silicate N-band emission show that the dust in IRAS11472-0800 is likely trapped in a stable disc. The energetics of the SED and the colour variability show that our viewing angle is close to edge-on and that the optical flux is dominated by scattered light. With photospheric abundances of [Fe/H] = -2.7 and [Sc/H]=-4.2, we discovered that IRAS11472-0800 is one of the most chemically-depleted objects known to date. Moreover, IRAS11472-0800 is a pulsating star with a period of 31.16 days and a peak-to-peak amplitude of 0.6 mag in V. The radial velocity variability is strongly influenced by the pulsations, but the significant cycle-to-cycle variability is systematic on a longer time scale, which we interpret as evidence for binary motion. We conclude that IRAS11472-0800 is a pulsating binary star surrounded by a circumbinary disc. The line-of-sight towards the object lies close the the orbital plane making that the optical light is dominated by scattered light. IRAS11472-0800 is one of the most chemically-depleted objects known so far and links the dusty RV\,Tauri stars to the non-pulsating class of strongly depleted objects.Comment: 12 pages, 14 figures Accepted for publication in A&A Main Journa

Post-AGB stars with hot circumstellar dust: binarity of the low-amplitude pulsators

While the first binary post-AGB stars were serendipitously discovered, the distinct characteristics of their Spectral Energy Distribution (SED) allowed us to launch a more systematic search for binaries. We selected post-AGB objects which show a broad dust excess often starting already at H or K, pointing to the presence of a gravitationally bound dusty disc in the system. We started a very extensive multi-wavelength study of those systems and here we report on our radial velocity and photometric monitoring results for six stars of early F type, which are pulsators of small amplitude. To determine the radial velocity of low signal-to-noise time-series, we constructed dedicated auto-correlation masks. The radial velocity variations were subjected to detailed analysis to differentiate between pulsational variability and variability due to orbital motion. Finally orbital minimalisation was performed to constrain the orbital elements. All of the six objects are binaries, with orbital periods ranging from 120 to 1800 days. Five systems have non-circular orbits. The mass functions range from 0.004 to 0.57 solar mass and the companions are likely unevolved objects of (very) low initial mass. We argue that these binaries must have been subject to severe binary interaction when the primary was a cool supergiant. Although the origin of the circumstellar disc is not well understood, the disc is generally believed to be formed during this strong interaction phase. The eccentric orbits of these highly evolved objects remain poorly understood. With the measured orbits and mass functions we conclude that the circumbinary discs seem to have a major impact on the evolution of a significant fraction of binary systems.Comment: 13 pages, 15 figures, accepted for Astronomy and Astrophysic