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Modifications of 2:1 Clay Minerals in a Kaolinite-Dominated Ultisol under Changing Land-Use Regimes
- Jason C. Austin, Amelia Perry, Daniel D. Richter, Paul A. Schroeder
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- Journal:
- Clays and Clay Minerals / Volume 66 / Issue 1 / February 2018
- Published online by Cambridge University Press:
- 01 January 2024, pp. 61-73
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Chemical denudation and chemical weathering rates vary under climatic, bedrock, biotic, and topographic conditions. Constraints for landscape evolution models must consider changes in these factors on human and geologic time scales. Changes in nutrient dynamics, related to the storage and exchange of K+ in clay minerals as a response to land use change, can affect the rates of chemical weathering and denudation. Incorporation of these changes in landscape evolution models can add insight into how land use changes affect soil thickness and erodibility. In order to assess changes in soil clay mineralogy that result from land-use differences, the present study contrasts the clay mineral assemblages in three proximal sites that were managed differently over nearly the past two centuries where contemporary vegetation was dominated by old hardwood forest, old-field pine, and cultivated biomes. X-ray diffraction (XRD) of the oriented clay fraction using K-, Mg-, and Na-saturation treatments for the air-dried, ethylene glycol (Mg-EG and K-EG) solvated, and heated (100, 350, and 550°C) states were used to characterize the clay mineral assemblages. XRD patterns of degraded biotite (oxidized Fe and expelled charge-compensating interlayer K) exhibited coherent scattering characteristics similar to illite. XRD patterns of the Mg-EG samples were, therefore, accurately modeled using NEWMOD2® software by the use of mineral structure files for discrete illite, vermiculite, kaolinite, mixed-layer kaolinite-smectite, illite-vermiculite, kaolinite-illite, and hydroxy-interlayered vermiculite. The soil and upper saprolite profiles that formed on a Neoproterozoic gneiss in the Calhoun Experimental Forest in South Carolina, USA, revealed a depth-dependence for the deeply weathered kaolinitic to the shallowly weathered illitic/vermiculitic mineral assemblages that varied in the cultivated, pine, and hardwood sites, respectively. An analysis of archived samples that were collected over a five-decade growth period from the pine site suggests that the content of illite-like layers increased at the surface within 8 y. Historical management of the sites has resulted in different states of dynamic equilibrium, whereby deep rooting at the hardwood and pine sites promotes nutrient uplift of K from the weathering of orthoclase and micas. Differences in the denudation rates at the cultivated, pine, and hardwood sites through time were reflected by changes in the soil clay mineralogy. Specifically, an increased abundance of illite-like layers in the surface soils can serve as a reservoir of K+.
Assessing implementation fidelity in the First Episode Rapid Early Intervention for Eating Disorders service model
- Katie L. Richards, Michaela Flynn, Amelia Austin, Katie Lang, Karina L. Allen, Ranjeet Bassi, Gabrielle Brady, Amy Brown, Frances Connan, Mary Franklin-Smith, Danielle Glennon, Nina Grant, William Rhys Jones, Kuda Kali, Antonia Koskina, Kate Mahony, Victoria A. Mountford, Nicole Nunes, Monique Schelhase, Lucy Serpell, Ulrike Schmidt
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- Journal:
- BJPsych Open / Volume 7 / Issue 3 / May 2021
- Published online by Cambridge University Press:
- 07 May 2021, e98
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Background
The First Episode Rapid Early Intervention for Eating Disorders (FREED) service model is associated with significant reductions in wait times and improved clinical outcomes for emerging adults with recent-onset eating disorders. An understanding of how FREED is implemented is a necessary precondition to enable an attribution of these findings to key components of the model, namely the wait-time targets and care package.
AimsThis study evaluated fidelity to the FREED service model during the multicentre FREED-Up study.
MethodParticipants were 259 emerging adults (aged 16–25 years) with an eating disorder of <3 years duration, offered treatment through the FREED care pathway. Patient journey records documented patient care from screening to end of treatment. Adherence to wait-time targets (engagement call within 48 h, assessment within 2 weeks, treatment within 4 weeks) and care package, and differences in adherence across diagnosis and treatment group were examined.
ResultsThere were significant increases (16–40%) in adherence to the wait-time targets following the introduction of FREED, irrespective of diagnosis. Receiving FREED under optimal conditions also increased adherence to the targets. Care package use differed by component and diagnosis. The most used care package activities were psychoeducation and dietary change. Attention to transitions was less well used.
ConclusionsThis study provides an indication of adherence levels to key components of the FREED model. These adherence rates can tentatively be considered as clinically meaningful thresholds. Results highlight aspects of the model and its implementation that warrant future examination.