Examining the relationships among cognitive processing, physical function, and disability in older adults

Age-related declines in cognitive processing are well documented and may contribute to limitations performing daily living tasks as people age. The purpose of this dissertation was to examine the relationships among cognitive processing, physical function, and disability in older adults. Three studies were organized into three distinct manuscripts. In this dissertation, we use the term cognitive processing to refer to performance on measures of attention and processing speed. The objective of the first study was to examine the direct and indirect effects of cognitive processing on physical function and disability. The second study examined: (1) the predictive relationship of cognitive processing to changes in physical function and disability, and (2) the association of change in cognitive processing to change in physical function and disability. The purpose of the third was to explore the relationship of cognitive processing to self-reported disability measured as dependence and measured as difficulty. The combined results of all three experiments confirmed that cognitive processing is associated with both concurrent and future levels of physical function and disability in older adults. The relationship between cognitive processing and disability is primarily mediated by physical function, such that poor cognitive processing is associated with lower levels of physical function and indirectly with higher levels of disability. Poor baseline cognitive processing is also predictive of decreased balance and disability one year later. The relationship of cognitive processing with disability appears to be most robust when iv disability is defined as dependence. These results illustrate the complex relationship of cognitive processing to physical function and disability in older adults

Cluster-based early warning indicators for political change in the contemporary levant

We we cluster analysis to develop a model of political change in the Levant as reflected in the World Event Interaction Survey coded event data generated from Reuters between 1979 and 1998. A new statistical algorithm that uses the correlation between dyadic behaviors at two times identities clusters of political activity. The transition to a new cluster occurs when a point is closer in distance to subsequent points than to preceding ones. These clusters begin to "stretch" before breaking apart, which served as an early warning indicator. The clusters correspond well with phases of political behavior identified a priori. A Monte Carlo analysis shows that the clustering and early waltzing measures are not random; they perform very differently in simulated data: sets with similar statistical characteristics. Our study demonstrates that the statistical analysis of newswire reports can yield systematic early warning indicators, and it provides empirical supper? for the theoretical concept of distinct behavioral phases in political activity

The shape of things to come? Expanding the inequality and grievance model for civil war forecasts with event data

© The Author(s) 2017. We examine if dynamic information from event data can help improve on a model attempting to forecast civil war using measures reflecting plausible motivation and grievances. Buhaug, Cederman, and Gleditsch predict the risk of civil war using a horizontal inequality model with measures reflecting motivation and relevant group characteristics at the country level. The predictions from their model outperform in an out-of-sample forecast conventional countrylevel models of civil war, emphasizing vertical inequality and country characteristics. However, most grievance measures change little over time. We surmise that a model reflecting potential motivation for conflict can be improved with more dynamic information on mobilization and the behavior of actors. Our conjecture receives some support in the empirical analysis, where we consider both conflict onset and termination over territorial and governmental incompatibilities in the Uppsala/PRIO Armed Conflict Data, and find some evidence that event data can help improve forecasts. Moreover, models with the original grievance measures do better than purely event based models, supporting our claim that both structure and event based components can add value to conflict prediction models. However, the contribution of events to improving predictive power is modest and not entirely consistent, and some types of conflict events seem easier to forecast than others

An Effective Community–Academic Partnership to Extend the Reach of Screenings for Fall Risk

Older adults should be screened for fall risk annually. Community providers (people without formal medical training who work with older adults in senior centers or aging services) may be a viable group to expand the reach of screenings. Our community–academic partnership developed a program to increase and assess fall risk screenings by community providers. Community sites hosted training workshops and screening events. Community screenings were well attended and received by providers and older adults. With administrative support from the regional fall prevention coalition and technical support from academia, community providers screened 161 older adults from a broad geographic area. Twenty-one community providers completed the training. Knowledge and confidence surveys demonstrated improvements before and after training (P < .001). Skills assessments demonstrated mastery of most skills, but some providers required additional training. Provider feedback indicated screening procedures were complex. Future projects will examine this model using simplified screening procedures

Leaf reflectance spectra capture the evolutionary history of seed plants

Leaf reflection spectra have been increasingly used to assess plant diversity. However, we do not yet understand how spectra vary across the tree of life or how the evolution of leaf traits affects the differentiation of spectra among species and lineages. Here we describe a framework that integrates spectra with phylogenies and apply it to aglobal dataset of over 16 000 leaf-level spectra (400–2400 nm) for 544 seed plant species. We test for phylogenetic signal in spectra, evaluate their ability to classify lineages, and characterize their evolutionary dynamics. We show that phylogenetic signal is present in leaf spectra but that the spectral regions most strongly associated with the phylogeny vary among lineages. Despite among-lineage heterogeneity, broad plant groups, orders, and families can be identified from reflectance spectra. Evolutionary models also reveal that different spectral regions evolve at different rates and under different constraint levels, mirroring the evolution of their underlying traits. Leaf spectra capture the phylogenetic history of seed plants and the evolutionary dynamics of leaf chemistry and structure. Consequently, spectra have the potential to provide breakthrough assessments of leaf evolution and plant phylogenetic diversity at global scales

The influence of C3 and C4 vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C/ N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk δ 13C and sand content explaining 0.63 of the observed variability. The variation of δ 13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times (τ ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter τ in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in δ 13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations. However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. This study shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of Published by Copernicus Publications on behalf of the European Geosciences Union. 5042 G. Saiz et al.: Influence of C3/C4 on SOM in tropical biomes C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM.UK National Environment Research CouncilAustralian Institute of Nuclear Science and Engineering (AINSE Ltd

Leaf economics and plant hydraulics drive leaf : wood area ratios

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordData accessibility: All data are archived and are available from the TRY plant trait data base: www.try-db.org (https://doi.org/10.1111/j.1365-2486.2011.02451.x).Biomass and area ratios between leaves, stems and roots regulate many physiological and ecological processes. The Huber value Hv (sapwood area/leaf area ratio) is central to plant water balance and drought responses. However, its coordination with key plant functional traits is poorly understood, which prevents developing trait-based prediction models. Based on theoretical arguments, we hypothesise that global patterns in Hv of terminal woody branches can be predicted from variables related to plant trait spectra, i.e., plant hydraulics and size and leaf economics. Using a global compilation of 1135 species-averaged Hv , we show that Hv varies over 3 orders of magnitude. Higher Hv are seen in short small-leaved low-SLA shrubs with low Ks in arid relative to tall large-leaved high-SLA trees with high Ks in moist environments. All traits depend on climate but climatic correlations are stronger for explanatory traits than Hv . Negative isometry is found between Hv and Ks , suggesting a compensation to maintain hydraulic supply to leaves across species. This work identifies the major global drivers of branch sapwood/leaf area ratios. Our approach based on widely available traits facilitates the development of accurate models of aboveground biomass allocation and helps predict vegetation responses to drought.Spanish Ministry of Economy and Competitiveness (MINECO)University of NottinghamSwedish Research Council Forma

The influence of C3 and C4 vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C=N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk 13C and sand content explaining 0.63 of the observed variability. The variation of 13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times ( ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in 13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations.However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. Thisstudy shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM. © 2015, Copernicus Publications