# University of St Andrews

• Saint Andrews, Scotland, United Kingdom
Recent publications
This paper examines consumers' intra-operator mobile phone plan switching in Ireland. It models the factors associated with switching outcomes, including the direction of change in expenditure and whether those who are observed to switch plans tend to arrive at more or less optimal plans given their usage. A dataset is employed that combines survey responses from mobile consumers with the same consumers' actual usage data in the period 2017–2019; this was collected by Ireland's national regulatory authority. The cost each consumer would have incurred on every plan offered in the market based on their observed usage is estimated. Using models that allow for selection into switching, associations between switching outcomes and demographic and user characteristics are modelled. Controls are included for plan and user attributes, including demographics and proxies for user sophistication and access to alternative communication options. A substantial proportion of intra-operator switchers in the sample increase expenditures when they switch plan. While many switchers move to plans that are more optimal given their usage, a slight majority move to plans that charge a higher price premium over the best available plan (based on observables) than the consumer's previous plan did. Few observable characteristics of consumers or plans seem to be significantly associated with which switches achieve greater optimality, although fixed operator effects are large and significant. These findings add to the weight of evidence which finds that many consumers fail to arrive at the best price even after switching.
Farmland birds are declining globally due to anthropogenic activities, with particularly few studies in Asian agricultural landscapes. Various studies have examined the impacts of landscape heterogeneity on farmland bird composition, but few have considered seasonal changes in bird diversity and examined functional feeding guild assemblages. Here, we disentangle the impact of seasonal variation (summer, monsoon, and winter), cropping practice (mixed crop, monocultural-crop, and fallow land), crop type (rice, wheat, maize, sugarcane, and other crops), landscape heterogeneity, and the number of houses and trees on the richness and abundance of farmland birds and their feeding guilds conducted within human-dominated agricultural landscapes of lowland Nepal. We established 116 transects (farmland = 100, forest = 8, and river = 8), and each transect was visited nine times from April 2018 to December 2019, with forests and river transect to test the dissimilarities in bird composition between those habitats and farmlands. We recorded 201 bird species in farmland, 133 in the forest, and 131 in river habitats. Bird composition on farmlands showed more dissimilarity with forest than river transects. We recorded nine globally, and 26 nationally threatened birds in farmlands. Seasonal variation and cropping practice significantly influenced the richness of all farmland birds and resident birds only, whereas species abundances vary by season only. We recorded higher species richness in the winter season and mixed crop fields but greater abundance in the monsoon and monoculture crop fields. Farmland bird richness increased with increasing tree numbers but decreased with increasing house numbers. Sugarcane fields had the highest bird richness within crop species, whereas rice fields had the greatest abundance. Seasons and cropping practice also shaped the assemblages of feeding guilds differently. In the context of increasing crop intensification globally, our study suggests that the governments in this region should encourage farmers to cultivate mixed crops and simultaneously restrict the urbanization of farmlands to protect bird diversity. Seasonality should be factored into analyses aimed at understanding bird diversity in agricultural landscapes.
Twenty-four composite samples of the fine-grained matrix of glacial diamictites deposited from the Mesoarchaean to Palaeozoic have been analysed for their silicon isotope composition and used to establish, for the first time, the long-term secular Si isotope record of the compositional evolution of upper continental crust (UCC). Diamictites with Archaean and Palaeoproterozoic Nd model ages show greater silicon isotope heterogeneity than those with younger model ages (irrespective of depositional age). We attribute the anomalously light Si isotope compositions of some diamictites with Archaean model ages to the presence of glacially milled banded iron formation (BIF), substantiated by the high iron content and Ge/Si in these samples. We infer that relatively heavy Si isotope signatures in some Palaeoproterozoic diamictites (all of which have Archaean Nd model ages) are due to contribution from tonalite-trondhjemite-granodiorites (TTGs), evidenced by the abundance of TTG clasts. By the Neoproterozoic (with model ages ranging from 2.3 to 1.8 Ga), diamictite Si isotope compositions exhibit a range comparable to modern UCC. This reduced variability through time is interpreted as reflecting the decreasing importance of BIF and TTG in post-Archaean continental crust. The secular evolution of Si isotopes in the diamictites offers an independent test of models for the emergence of stable cratons and the onset of horizontal mobile-lid tectonism. The early Archaean UCC was heterogeneous and incorporated significant amounts of isotopically light BIF, but following the late Archaean stabilisation of cratons, coupled with the oxygenation of the atmosphere that led to the reduced neoformation of BIF and diminishing quantities of TTGs, the UCC became increasingly homogeneous. This homogenisation likely occurred via reworking of preexisting crust, as evidenced by Archaean Nd model ages recorded in younger diamictites.
Animal learning theory has been enormously influential in setting up laws of how individuals gradually learn associations and instrumentation by reinforcement. Yet, the theory rests on data collected from socially isolated laboratory animals, exposed to artificial cause–effect relations without visible agents. We review the primate vocal learning literature and find that animal learning theory performs poorly in accounting for real-life learning and evolutionarily relevant problem-solving. Instead, learning occurs when conspecifics act as event-causing agents, often without direct consequences for learners. We illustrate this with recent field studies, which suggest that the default mode of learning may not be through reinforcement and repeated trials but by acquiring scripts — mental representations of how events typically unfold. Becoming communicatively competent may be more about learning how events unfold than becoming conditioned to stimuli and responses.
In this paper we study ergodic theory of countable Markov shifts. These are dynamical systems defined over non-compact spaces. Our main result relates the escape of mass, the measure theoretic entropy, and the entropy at infinity of the system. This relation has several consequences. For example we obtain that the entropy map is upper semi-continuous and that the ergodic measures form an entropy dense subset. Our results also provide new proofs of results describing the existence and stability of the measure of maximal entropy. We relate the entropy at infinity with the Hausdorff dimension of the set of recurrent points that escape on average. Of independent interest, we prove a version of Katok's entropy formula in this non-compact setting.
Background Neuro-oncology patients make decisions over their disease course that range in complexity. Clinicians must ensure patients have the decision-making capacity for specific decisions. One decision (in some jurisdictions) is whether to pursue physician-assisted suicide, or medical assistance in dying (MAiD). This is increasingly important as more jurisdictions legalize MAiD. The aim of this scoping review was to explore patient decision-making capacity in neuro-oncology, including measures of capacity and predictors of incapacity for end-of-life decision-making. Methodology We conducted two literature searches (“decision making capacity and neuro-oncology” and “MAiD and neuro-oncology”) in five databases. Objective We aimed to review the existing literature around capacity assessment in neuro-oncology, the prevalence of incapacity in this patient population, and factors that might predict incapacity. We also aimed to highlight gaps in the literature around MAiD in neuro-oncology. Results Standardized tools are available that can supplement clinical capacity assessment. Specific cognitive tests can suggest which domain of capacity is likely to be affected and can guide subsequent intervention. Clinical factors such as tumor grade and various treatments may impact capacity and cognition. In a brain cancer population, the prevalence of incapacity for healthcare decisions is 50-61%. Very little has been published about MAiD in neuro-oncology patients. Conclusions There is an established understanding of tools to assess decision-making capacity, but ultimately clinical gestalt is still important. More research is needed to understand whether specific tumor features (e.g., location, size) are implicated in incapacity in general, and specifically in decision-making capacity for end-of-life treatment options, including MAiD.
Audience effects are key in studies of animal social cognition and are typically investigated during directed social interactions. Male chimpanzees, Pan troglodytes, regularly perform aggressive displays in the presence of others, often targeting a specific group member, and combine this agonistic behaviour with acoustic signals. Here, we were interested in whether the production and structure of pant hoots, a long-distance signal, were influenced by audience composition (i.e. presence and absence of specific individuals). We investigated pant hoots produced during displays by adult and subadult males of Budongo Forest, Uganda. We found that males overall called more often when their preferred social partners and females were absent from the party, as well as when more dominant males were present. We then separately analysed the four phases of pant hoots, introduction, build-up, climax and let-down, and found that audience composition and social context could often explain the presence or absence of each phase. In addition, displays were often accompanied by drumming, especially by older males and when male audiences were small. Our study adds to the growing body of literature on audience effects and other social factors and shows their impact on the structure of a sophisticated vocal sequence, which enhances the communicative capacity in a species with limited vocal control.
Anointing is a behaviour in which animals apply pungent-smelling materials over their bodies. It can be done individually or socially in contact with others. Social anointing can provide coverage of body parts inaccessible to the individual, consistent with hypotheses that propose medicinal benefits. However, in highly social capuchin monkeys, Sapajus and Cebus spp., anointing has been suggested to also benefit group members through ‘social bonding’. To test this, we used social network analysis to measure changes in proximity patterns during and shortly after anointing compared to a baseline condition. We presented two capuchin groups with varying quantities of onion, which reliably induces anointing, to create ‘rare resource’ and ‘abundant resource’ conditions. We examined the immediate and overall effects of anointing behaviour on the monkeys' social networks, using patterns of proximity as a measure of social bonds. For one group, proximity increased significantly after anointing over baseline values for both rare and abundant resource conditions, but for the other group proximity only increased following the rare resource condition, suggesting a role in mediating social relationships. Social interactions were affected differently in the two groups, reflecting the complex nature of capuchin social organization. Although peripheral males anointed in proximity to other group members, the weak centrality only changed in one group following anointing bouts, indicating variable social responses to anointing. We suggest in part that anointing in capuchins is analogous to social grooming: both behaviours have an antiparasitic function and can be done individually or socially requiring contact between two or more individuals. We propose that they have evolved a social function within complex repertoires of social behaviours. Our alternative perspective avoids treating medicinal and social explanations as alternative hypotheses and, along with increasing support for the medical explanations for anointing, allows us to conceptualize social anointing in capuchins as ‘social medication’.
We introduce a definition of thickness in $${\mathbb {R}}^d$$ R d and obtain a lower bound for the Hausdorff dimension of the intersection of finitely or countably many thick compact sets using a variant of Schmidt’s game. As an application we prove that given any compact set in $${\mathbb {R}}^d$$ R d with thickness $$\tau$$ τ , there is a number $$N(\tau )$$ N ( τ ) such that the set contains a translate of all sufficiently small similar copies of every set in $${\mathbb {R}}^d$$ R d with at most $$N(\tau )$$ N ( τ ) elements; indeed the set of such translations has positive Hausdorff dimension. We also prove a gap lemma and bounds relating Hausdorff dimension and thickness.
A ( d , k )-set is a subset of $$\mathbb {R}^d$$ R d containing a k -dimensional unit ball of all possible orientations. Using an approach of D. Oberlin we prove various Fourier dimension estimates for compact ( d , k )-sets. Our main interest is in restricted ( d , k )-sets, where the set only contains unit balls with a restricted set of possible orientations $$\Gamma$$ Γ . In this setting our estimates depend on the Hausdorff dimension of $$\Gamma$$ Γ and can sometimes be improved if additional geometric properties of $$\Gamma$$ Γ are assumed. We are led to consider cones and prove that the cone in $$\mathbb {R}^{d+1}$$ R d + 1 has Fourier dimension $$d-1$$ d - 1 , which may be of interest in its own right.
Previous research has tested whether culture moderates the relationship between head tilt and perceptions of a cooperation-relevant construct. In this paper, we replicated the effects of head posture on perceived traits and compared Chinese and American participants to explore whether difference in cultural background (collectivist and individualist) affects perceptual attribution. Specifically, we investigated how head posture (level, up or down) affects perceptions of cooperativeness. In Experiment 1, Chinese and American participants rated Asian and Caucasian faces in three postures for perceived cooperativeness on a seven-point Likert scale. In Experiment 2, participants ranked the cooperativeness of the three postures of the same faces. In Experiment 3, participants scrolled through face images and manually manipulated vertical head angle to maximise apparent cooperativeness. We found that for both Chinese and American participants a neutral head level posture was perceived as more cooperative than head up and down postures. The optimal head posture for maximised apparent cooperativeness was close to level but with a slight downward rotation. While there was cross-cultural consistency in perceptions, Chinese participants exhibited greater sensitivity to postural cues in their judgments of cooperation compared to American participants. Our results suggest a profound effect of posture on the perception of cooperativeness that is common across cultures and that there are additional subtle cross-cultural differences in the cues to cooperativeness.
A fundamental aspect of human communication is our ability to refer to external objects and events through both words and gestures (such as pointing), yet the evolutionary origins of such signals remain obscure. Apes, living in their natural environments, rarely or never point, but it has been claimed that male chimpanzees, Pan troglodytes schweinfurthii, from the Ngogo community, Uganda, habitually use exaggerated loud scratches (ELSs) to refer to specific body locations where they wish to be groomed (Pika & Mitani, 2006, Current Biology, 16(6), 191–192). This study suggested continuity between referential abilities in humans and our closest living relatives, making it an important finding to replicate in other populations. Hence here, we compared whether ELSs are used in a referential manner across four wild communities of eastern chimpanzees (Ngogo, Kanyawara, Sonso and Waibira). Our data show that scratchers were significantly more likely to receive grooming in the scratched location at Ngogo compared to the other three sites. At the latter sites this response occurred at low rates and signallers did not seem to pursue this goal. This suggests that ELSs do not function referentially at these sites, and the published findings from Ngogo were not replicated. Further exploration into alternative functions of ELSs in the Kanyawara community revealed that, in this community, this signal functions to initiate grooming bouts and to reengage partners during grooming pauses. Individuals who produced the signal to initiate grooming were likely to offer grooming. In contrast, during grooming bouts, groomers produced ELSs to request reciprocation of grooming from their partner. Our study demonstrates that chimpanzees do not ubiquitously use the ELS in a referential manner, but that they can use this gesture in a highly flexible fashion, with signal function depending on the intricate details of the social contexts in which they are produced.
Multi-species indices (MSI) are widely used as ecological indicators and as instruments to inform environmental policies. Many of these indices combine species-specific estimates of relative population sizes using the geometric mean. Because the geometric mean is not defined when values of zero occur, usually only commoner species are included in MSIs and zero values are replaced by a small non-zero value. The latter can exhibit an arbitrary influence on the geometric mean MSI. Here, we show how the compound Poisson and the negative binomial model can be used in such cases to obtain an MSI that has similar features to the geometric mean, including weighting halving and doubling of a species’ population equally. In contrast to the geometric mean, these two statistical models can handle zero values in population sizes and thus accommodate newly occurring and temporarily or permanently disappearing species in the MSI. We compare the MSIs obtained by the two statistical models with the geometric mean MSI and measure sensitivity to changes in evenness and to population trends in rare and abundant species. Additionally, we outline sources of uncertainty and discuss how to measure them. We found that, in contrast to the geometric mean and the negative binomial MSI, the compound Poisson MSI is less sensitive to changes in evenness when total abundance is constant. Further, we found that the compound Poisson model can be influenced more than the other two methods by trends of species showing a low interannual variance. The negative binomial MSI is less sensitive to trends in rare species compared with the other two methods, and similarly sensitive to trends in abundant species as the geometric mean. While the two new MSIs have the advantage that they are not arbitrarily influenced by rare, newly appearing and disappearing species, both do not weight all species equally. We recommend replacing the geometric mean MSI with either compound Poisson or negative binomial when there are species with a population size of zero in some years having a strong influence on the geometric mean MSI. Further, we recommend providing additional information alongside the MSIs. For example, it is particularly important to give an evenness index in addition to the compound Poisson MSI and to indicate the number of disappearing and newly occurring species alongside the negative binomial MSI.
This study examines the effect of environmental, social and governance risks on firm value. We analyze the extent to which environmental, social and governance related news affect tourism firms' abnormal returns using event study methodology. The results show that environmental, social and governance related news releases do not significantly affect firm value in the short-term. We further investigate the effect of environmental, social and governance risks on the value of tourism firms during the recent pandemic utilizing difference-in-differences analysis. The results provide robust evidence that sustainable business practices provide higher resilience to pandemic-like external shocks. Also, the presence of a sustainability committee mitigates the adverse effects of environmental, social and governance risks on firm value. Theoretical and practical implications are discussed.
Languages tend to encode events from the perspective of agents, placing them first and in simpler forms than patients. This agent bias is mirrored by cognition: Agents are more quickly recognized than patients and generally attract more attention. This leads to the hypothesis that key aspects of language structure are fundamentally rooted in a cognition that decomposes events into agents, actions, and patients, privileging agents. Although this type of event representation is almost certainly universal across languages, it remains unclear whether the underlying cognition is uniquely human or more widespread in animals. Here, we review a range of evidence from primates and other animals, which suggests that agent-based event decomposition is phylogenetically older than humans. We propose a research program to test this hypothesis in great apes and human infants, with the goal to resolve one of the major questions in the evolution of language, the origins of syntax.
Background Over five million joint replacements are performed across the world each year. Cobalt chrome (CoCr) components are used in most of these procedures. Some patients develop delayed-type hypersensitivity (DTH) responses to CoCr implants, resulting in tissue damage and revision surgery. DTH is unpredictable and genetic links have yet to be definitively established. Methods At a single site, we carried out an initial investigation to identify HLA alleles associated with development of DTH following metal-on-metal hip arthroplasty. We then recruited patients from other centres to train and validate an algorithm incorporating patient age, gender, HLA genotype, and blood metal concentrations to predict the development of DTH. Accuracy of the modelling was assessed using performance metrics including time-dependent receiver operator curves. Results Using next-generation sequencing, here we determine the HLA genotypes of 606 patients. 176 of these patients had experienced failure of their prostheses; the remaining 430 remain asymptomatic at a mean follow up of twelve years. We demonstrate that the development of DTH is associated with patient age, gender, the magnitude of metal exposure, and the presence of certain HLA class II alleles. We show that the predictive algorithm developed from this investigation performs to an accuracy suitable for clinical use, with weighted mean survival probability errors of 1.8% and 3.1% for pre-operative and post-operative models respectively. Conclusions The development of DTH following joint replacement appears to be determined by the interaction between implant wear and a patient’s genotype. The algorithm described in this paper may improve implant selection and help direct patient surveillance following surgery. Further consideration should be given towards understanding patient-specific responses to different biomaterials.
Almost all animals navigate their environment to find food, shelter, and mates. Spatial cognition of nonhuman primates in large-scale environments is notoriously difficult to study. Field research is ecologically valid, but controlling confounding variables can be difficult. Captive research enables experimental control, but space restrictions can limit generalizability. Virtual reality technology combines the best of both worlds by creating large-scale, controllable environments. We presented six chimpanzees with a seminaturalistic virtual environment, using a custom touch screen application. The chimpanzees exhibited signature behaviors reminiscent of real-life navigation: They learned to approach a landmark associated with the presence of fruit, improving efficiency over time; they located this landmark from novel starting locations and approached a different landmark when necessary. We conclude that virtual environments can allow for standardized testing with higher ecological validity than traditional tests in captivity and harbor great potential to contribute to longstanding questions in primate navigation, e.g., the use of landmarks, Euclidean maps, or spatial frames of reference.
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