Identifying seasonal variations in store‐level visitor grocery demand

Purpose: The purpose of this paper is to understand the contribution of visitor demand to the seasonal sales variations experienced at grocery retailers in Cornwall, South West England. Design/methodology/approach: Working collaboratively with a major UK retailer provides access to store trading information and customer data from a popular loyalty card scheme. The authors use spatial analysis to identify revenue originating from outside the store catchment, and explore the spatial and temporal nature of the visitor demand recorded in‐store. Findings: The paper demonstrates the significant degree of seasonality experienced around stores in terms of their revenue generated from out‐of‐catchment visitors, and highlights implications for store location planning. Most notably, visitor expenditure tends to demonstrate far more spatial and temporal clustering than residential demand. The authors argue that it is essential for retailers to ensure that their location planning makes full use of all available consumer data to understand the local nature of demand, including the impact of visitor expenditure. Research limitations/implications: The authors aim to use this insight to develop a spatial decision support system (SDSS) for use within site location planning in the retail sector. This would incorporate a spatial interaction model to estimate and account for variation in local demand generated by seasonal tourist visits. Originality/value: Customer level loyalty card data are rarely available for academic investigations and the authors are able to provide a unique insight into customer expenditure in tourist locations. There has been little exploration of seasonal tourist demand in store location planning, and this study addresses an identified academic and commercial need

Constraining protoplanetary disc evolution using accretion rate and disc mass measurements: the usefulness of the dimensionless accretion parameter

We explore how measurements of protoplanetary disc masses and accretion rates provided by surveys of star-forming regions can be analysed via the $\textit{dimensionless accretion parameter}$, which we define as the product of the accretion rate and stellar age divided by the disc mass. By extending and generalizing the study of Jones et al., we demonstrate that this parameter should be less than or of order unity for a wide range of evolutionary scenarios, rising above unity only during the final stages of outside-in clearing by external photoevaporation. We use this result to assess the reliability of disc mass estimates derived from CO isotopologues and sub-mm continuum emission by examining the distribution of accretion efficiencies in regions that are not subject to external photoevaporation. We find that while dust-based mass estimates produce results compatible with theoretical expectations assuming a canonical dust-to-gas ratio, the systematically lower CO-based estimates yield accretion efficiencies significantly above unity in contrast with the theory. This finding provides additional evidence that CO-based disc masses are an underestimate, in line with arguments that have been made on the basis of chemical modelling of relatively small samples. On the other hand, we demonstrate that dust-based mass estimates are sufficiently accurate to reveal distinctly higher accretion efficiencies in the Trapezium cluster, where this result is expected, given the evident importance of external photoevaporation. We therefore propose the dimensionless accretion parameter as a new diagnostic of external photoevaporation in other star-forming regions.This work has been supported by the DISCSIM project, grant agreement 341137, funded by the European Research Council under ERC-2013-ADG. CFM gratefully acknowledges an ESA Research Fellowship

Forming short-period substellar companions in 47 Tucanae - I. Dynamical model and brown dwarf tidal capture rates

ABSTRACT Stars in globular clusters formed and evolved in the most extreme environment: high density and low metallicity. If the formation of stars and planets is at all sensitive to environmental conditions, this should therefore be evident in globular clusters. Observations have indicated that hot Jupiters are at least an order of magnitude less prevalent in the central region of the globular cluster 47 Tucanae (Tuc) than in the field. In this work, we explore the claims in the literature for additional consequences for the low-mass stellar initial mass function. Tidal capture, the mechanism that produces X-ray binaries in globular clusters, applies also to brown dwarfs (BDs). This process produces tight stellar–BD binaries that would be detectable by transit surveys. Applying a Monte Carlo dynamical evolution model, we compute the overall BD capture rates. We find that the number of captures is lower than previous estimates. Capture efficiency increases steeply with stellar mass, which means that mass segregation reduces capture efficiency as BDs and low-mass stars occupy the same regions. The result of this effect is that the current constraints on the short-period companion fraction remain marginally consistent with initially equal numbers of BDs and stars. However, our findings suggest that expanding the sample in 47 Tuc or surveying other globular clusters for close substellar companions can yield constraints on the substellar initial mass function in these environments. We estimate the capture rates in other globular clusters and suggest that 47 Tuc remains a promising target for future transit surveys.</jats:p

Geography of Diet in the UK Women’s Cohort Study: A Cross-Sectional Analysis

Diet can influence health outcomes and chronic disease risk, therefore a better understanding of factors influencing diet is important in promotion of healthier dietary choices. Many factors influence food choice, including the environment in which we live. This study aims to explore differences in dietary pattern consumption by two spatial measures: Government Office Region (a large regional unit of geography) and Output Area Classification (a small area geography combined with demographic characteristics). A cross-sectional analysis using data from the UK Women’s Cohort Study was carried out. This cohort included ~35000 middle aged women recruited between 1995 and 1999. Dietary patterns were derived using a k-means cluster analysis from diet data collected using a validated 217 item Food Frequency Questionnaire. Multinomial logit regression was used to test whether the area in which the women live, predicts their dietary pattern consumption. Results show that dietary patterns vary significantly by both spatial measures. The Government Office Region, the North West of England has the highest proportion of individuals consuming the least healthy, monotonous diets, while Greater London has the highest proportion of vegetarian diets. Individuals living in Supergroups ‘Countryside’ and ‘Prospering Suburbs’ consume healthier, more diverse diets. Those in ‘Constrained by Circumstance’ and ‘Blue Collar Communities’ consume monotonous, less healthy diets. Using a combination of spatial scales such as Government Office Region and Output Area Classification Supergroup could have a beneficial impact on targeting of public health dietary interventions and subsequent health

A super-resolution analysis of the DSHARP survey: Substructure is common in the inner 30 au

The DSHARP survey evidenced the ubiquity of substructure in the mm dust distribution of large, bright protoplanetary discs. Intriguingly, these datasets have yet higher resolution information that is not recovered in a CLEAN image. We first show that the intrinsic performance of the CLEAN algorithm is resolution-limited. Then analyzing all 20 DSHARP sources using the 1D, super-resolution code Frankenstein (frank), we accurately fit the 1D visibilities to a mean factor of 4.3 longer baseline than the Fourier transform of the CLEAN images and a factor of 3.0 longer baseline than the transform of the CLEAN component models. This yields a higher resolution brightness profile for each source, identifying new substructure interior to 30 au in multiple discs; resolving known gaps to be deeper, wider, and more structured; and known rings to be narrower and brighter. Across the survey, high contrast gaps are an average 14% wider and 44% deeper in the frank profiles relative to CLEAN, and high contrast rings are an average 26% narrower. Categorizing the frank brightness profiles into trends, we find that the relative scarcity of features interior to 30 au in the survey's CLEAN images is an artifact of resolving power, rather than an intrinsic rarity of inner disc (or compact disc) substructure. Finally the rings in the frank profiles are narrower than the previously inferred deconvolved widths, indicating smaller alpha / St ratios in the local gas disc

Open all hours: Spatiotemporal fluctuations in UK grocery store sales and catchment area demand

Conventional population estimates do not account for spatiotemporal fluctuations in populations over a diurnal timescale at the level of retail store catchments. This presents challenges for the retail location-based decision making process which seeks to predict sales volumes and their temporal characteristics prior to new store construction. We present a novel analysis of the temporal fluctuations of store sales, evidencing links between the spatiotemporal distribution of specific population subgroups and temporal store sales. Previous research linking spatiotemporal populations and store sales is limited owing to the fact that commercial data are not openly available to academic research. However, this research has unprecedented access to store level temporal sales data and an established loyalty card scheme from a major UK grocery retailer making these analyses possible for the first time. Additionally, we demonstrate that current store classifications were inadequate for grouping stores with similar sales profiles and propose four new clusters of stores based on the times of the day that they generate revenues. This development has clear academic and commercial benefits, aiding our understanding of consumer behaviours and a novel solution for improved location modelling. We lay the foundations for further research building spatiotemporal demand fluctuations into retail location models

The origin of the eccentricity of the hot Jupiter in CI Tau

Following the recent discovery of the first radial velocity planet in a star still possessing a protoplanetary disc (CI Tau), we examine the origin of the planet's eccentricity (e $\sim 0.3$). We show through long timescale ($10^5$ orbits) simulations that the planetary eccentricity can be pumped by the disc, even when its local surface density is well below the threshold previously derived from short timescale integrations. We show that the disc may be able to excite the planet's orbital eccentricity in $<$ a Myr for the system parameters of CI Tau. We also perform two planet scattering experiments and show that alternatively the observed planet may plausibly have acquired its eccentricity through dynamical scattering of a migrating lower mass planet, which has either been ejected from the system or swallowed by the central star. In the latter case the present location and eccentricity of the observed planet can be recovered if it was previously stalled within the disc's magnetospheric cavity.This work has been supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG, and from STFC through grant ST/L000636/1. This work used the DIRAC Shared Memory Processing and Data Analytic systems, both at the University of Cambridge and operated, respectively, by the COSMOS Project at the Department of Applied Mathematics and Theoretical Physics and the Cambridge High Performance Computing Service, on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment was funded by BIS National E-infrastructure capital grants ST/J005673/1 and ST/K001590/1, STFC capital grants ST/H008586/1, ST/H008861/1 and ST/H00887X/1, STFC DiRAC Operations grant ST/K00333X/1, and STFC DiRAC Operations grant ST/K00333X/1. DiRAC is part of the National E-Infrastructure.This is the final version of the article. It first appeared from Oxford University Press via https://doi.org/10.1093/mnrasl/slw18

On the millimetre continuum flux–radius correlation of proto-planetary discs

A correlation between proto-planetary disc radii and sub-mm fluxes has been recently reported. In this Letter we show that the correlation is a sensitive probe of grain growth processes. Using models of grain growth and drift, we have shown in a companion paper that the observed disc radii trace where the dust grains are large enough to have a significant sub-mm opacity. We show that the observed correlation emerges naturally if the maximum grain size is set by radial drift, implying relatively low values of the viscous $\alpha$ parameter $\lesssim 0.001$. In this case the relation has an almost universal normalisation, while if the grain size is set by fragmentation the flux at a given radius depends on the dust-to-gas ratio. We highlight two observational consequences of the fact that radial drift limits the grain size. The first is that the dust masses measured from the sub-mm could be overestimated by a factor of a few. The second is that the correlation should be present also at longer wavelengths (e.g. 3mm), with a normalisation factor that scales as the square of the observing frequency as in the optically thick case

On the Origin of the Spiral Morphology in the Elias 2-27 Circumstellar Disk

The young star Elias 2-27 has recently been observed to posses a massive circumstellar disk with two prominent large-scale spiral arms. In this Letter, we perform three-dimensional Smoothed Particle Hydrodynamics simulations, radiative transfer modeling, synthetic ALMA imaging, and an unsharped masking technique to explore three possibilities for the origin of the observed structures - an undetected companion either internal or external to the spirals, and a self-gravitating disk. We find that a gravitationally unstable disk and a disk with an external companion can produce morphology that is consistent with the observations. In addition, for the latter, we find that the companion could be a relatively massive planetary-mass companion (≲10-13 M Jup ) and located at large radial distances (between ≈300-700 au). We therefore suggest that Elias 2-27 may be one of the first detections of a disk undergoing gravitational instabilities, or a disk that has recently undergone fragmentation to produce a massive companion.We acknowledge support from the DISCSIM project, grant agreement 341137 under ERC-2013-ADG. F.M. acknowledges support from The Leverhulme Trust. This Letter uses the following ALMA data: ADS/JAO.ALMA# 2013.1.00498.S. This work used the Darwin DiRAC HPC cluster at the University of Cambridge and was undertaken on the Cambridge COSMOS SMP system, part of the STFC DiRAC HPC Facility supported by BIS NeI capital grant ST/J005673/1 and STFC grants ST/H008586/1, ST/K00333X/1