Research & Publications

Abstract Cognitive resilience (CR) describes the phenomenon of individuals evading cognitive decline despite prominent Alzheimer’s disease neuropathology. Operationalization and measurement of this latent construct is non-trivial as it cannot be directly observed. The residual approach has been widely applied to estimate CR, where the degree of resilience is estimated through a linear model’s residuals. We demonstrate that this approach makes specific, uncontrollable assumptions and likely leads to biased and erroneous resilience estimates. This is especially true when information about CR is contained in the data the linear model was fitted to, either through inclusion of CR-associated variables or due to correlation. We propose an alternative strategy which overcomes the standard approach’s limitations using machine learning principles. Our proposed approach makes fewer assumptions about the data and CR and achieves better estimation accuracy on simulated ground-truth data.

Abstract Roadkill is widely recognized as one of the primary negative effects of roads on many wildlife species and also has socioeconomic impacts when they result in accidents. A comprehensive dataset of roadkill locations is essential to evaluate the factors contributing to roadkill risk and to enhance our comprehension of its impact on wildlife populations and socioeconomic dimensions. We undertook a compilation of roadkill records, encompassing both published and unpublished data gathered from road surveys or opportunistic sources. GLOBAL ROADKILL DATA includes 208,570 roadkill records of terrestrial vertebrates from 54 countries across six continents, encompassing data collected between 1971 and 2024. This dataset serves to minimise the collection of redundant data and acts as a valuable resource for local and macro scale analysis regarding rates of roadkill, road- and landscape-related features associated with risk of roadkill, vulnerability of species to road traffic, and populations at risk of local extinction. The objective of this dataset is to promote scientific progress in infrastructure ecology and terrestrial vertebrate conservation while limiting the socio-economic costs.

Abstract US foreign policy observers have noted a decline in the frequency of expert witnesses appearing before congressional committees, while congressional scholars have documented changes in committee practices that have led to fewer and shorter hearings. These trends interact in systematic ways, although their relationship has never been tested empirically. Using original data and micro-level measures of individual hearings by the national security committees of the House and Senate, we demonstrate how time constraints and routine responsibilities limit the number of opportunities for ex- pert witnesses from 1995 to 2020. We find some influence for chamber polarization on witness totals but less impact on the type of experts. We uncover significant differences among individual committees in their use of academics and think tank representatives. Our study is unique in its focus on both chambers, inclusion of closed hearings, differentia- tion between academics and think tank representatives, and attention to the public salience of foreign affairs. Shrinkage in the official marketplace of foreign policy ideas warrants concern, highlighting the executive branch's increasing domi- nance over military and diplomatic decisions, diminished legislative capacity, and public disinterest in international affairs.

Abstract <jats:title>Abstract</jats:title>
<jats:p>This study demonstrates rigorously that an at-scale government training program for secondary teachers in Nepal had little or no impact on student learning. It then documents five sets of weaknesses related to training uptake, training-session management, teacher subject knowledge, teacher adoption of new classroom practices, and student knowledge of earlier-grade curriculum content, each of which plausibly explains some, but not all, of the program's failure. While weaknesses in trainer and teacher motivation may have contributed to the program's disappointing performance, the study argues that time, resource, and capacity constraints of both trainers and teachers, and a mismatch between policy design and student learning needs, also limited program success. These results highlight the need to broaden common accountability-focused conceptions of how to improve public service quality.</jats:p>

Abstract This study was conducted to clarify patterns of cortico-limbic volume abnormalities in late life depression (LLD) relative to non-depressed (ND) adults matched for amyloid β (Aβ) deposition and to evaluate the relationship of volume abnormalities with cognitive performance. Participants included 116 LLD and 226 ND. Classification accuracy of LLD status was estimated using area under the receiver operator characteristic curve. Twenty-one percent of LLD and ND participants were Aβ positive and the groups did not differ on white matter hyperintensity volume (WMH (logscale); β = 0.12, p = 0.28). Compared to ND, the LLD group exhibited significantly lower bilateral volume in the lateral orbitofrontal cortex, hippocampus, accumbens area, superior temporal lobe, temporal pole, and amygdala after multiple comparison correction (p < 0.009 for all). Cortico-limbic volumes significantly improved classification of LLD beyond demographic characteristics, Aβ status, and WMH (AUC<inf>Vol</inf> = 0.71, AUC<inf>WMH</inf>, <inf>Aβ</inf> = 0.62, AUC difference, 0.09 [0.03 to 0.15]). LLD exhibited poorer performance on measures of global cognition, set shifting, and verbal learning and memory relative to ND. Cognitive function was positively associated with cortico-limbic volumes and these relationships did not differ by group. Secondary analyses with an ND sample additionally matched for Mild Cognitive Impairment (MCI) diagnosis showed a similar but attenuated pattern of volume abnormalities. Overall, our results support LLD as being associated with cortico-limbic volume abnormalities that are distinct from Aβ and white matter pathologies and that these volume abnormalities are important factors associated with cognitive dysfunction in LLD.