Experimental approaches to predicting the future of tundra plant communities

(a) Background: Predicting the future of tundra plant communities is a major intellectual and practical challenge and it can only be successful if underpinned by an understanding of the evolutionary history and genetics of tundra plant species, their ecophysiology, and their responsiveness (both individually and as component parts of communities) to multiple environmental change drivers. (b) Aims: This paper considers the types of experimental approaches that have been used to understand and to predict the future of tundra plant communities and ecosystems. In particular, the use of ‘environmental manipulation’ experiments in the field is described, and the merits and limitations of this type of approach are considered with specific reference to the International Tundra Experiment (ITEX) as an example to indicate the key principles. The approach is compared with palaeoenvironmental investigations (using archives – or proxies – of past change) and the study of environmental gradients (so-called ‘space-for-time substitution’) to understand potential future change. (c) Conclusions: Environmental manipulation experiments have limitations associated with, for example, short timescales, treatment artefacts, and trade-offs between technical sophistication and breadth of deployment in heterogeneous landscapes/regions. They do, however, provide valuable information on seasonal through decadal phenological, growth, reproductive, and ecosystem responses which have a direct bearing on ecosystem-atmosphere coupling, species interactions and, potentially, trophic cascades. Designed appropriately, they enable researchers to test specific hypotheses and to record the dynamics of ecosystem responses to change directly, thus providing a robust complement to palaeoenvironmental investigations, gradient studies and ecosystem modelling

A systematic review of movement-oriented mind-body interventions and psychoneuroimmunological outcomes for psychological stress and trauma

Objective. The mind and body are inseparable and share bidirectional influences. Psychological stress and distress related to traumatic events are significant contributors to morbidity, mortality, and healthcare costs worldwide. Mind-body movement-oriented interventions have been found to benefit one\u27s physical and mental health via down-regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system. This systematic review aimed to identify and synthesize the research on movement-oriented mind-body interventions for trauma and stress as informed by psychoneuroimmunology. The review focused on exercise, yoga, tai chi, qi gong, and dance movement therapy that target the physiological systems impacted by psychological stress/trauma. Methods. Data was collected from four electronic databases (EBSCOHost, SCOPUS, Pubmed/Medline, Psychiatry online) between 2005-2021. All studies were required to include adult subjects exposed to psychological stress or trauma, a movement-oriented mind-body intervention, an objective physiologic psychoneuroimmunological outcome measure, and a self or clinician-reported psychological or psychosocial symptom measure. A Data Collection and Extraction form was used to record the variables for each study that met the inclusion criteria. Results. In total, 20 studies were included in the descriptive synthesis and summary of existing quantitative studies. The results found yoga to be the most researched movement-oriented mind-body intervention. Most included studies found mental health improvements alongside positive impacts on inflammatory and immune processes after yoga, tai-chi, qigong, or dance-movement therapy. Fourteen of the 20 selected studies indicated at least one significant finding for a physiological PNI-related outcome measure and psychosocial outcome measure. Conclusion. The findings of this systematic review suggest that movement-oriented mind-body interventions may be a promising approach for promoting mental and physical health in individuals with psychological stress and trauma. Future research in this field should include longitudinal studies, standardizing the movement-oriented mind-body interventions in research, operationally defining stress and trauma, increasing inclusion of diversity in participants, and increasing sample sizes

Representation discovery using a fixed basis in reinforcement learning

A thesis presented for the degree of Doctor of Philosophy, School of Computer Science and Applied Mathematics. University of the Witwatersrand, South Africa. 26 August 2016.In the reinforcement learning paradigm, an agent learns by interacting with its environment. At each state, the agent receives a numerical reward. Its goal is to maximise the discounted sum of future rewards. One way it can do this is through learning a value function; a function which maps states to the discounted sum of future rewards. With an accurate value function and a model of the environment, the agent can take the optimal action in each state. In practice, however, the value function is approximated, and performance depends on the quality of the approximation. Linear function approximation is a commonly used approximation scheme, where the value function is represented as a weighted sum of basis functions or features. In continuous state environments, there are infinitely many such features to choose from, introducing the new problem of feature selection. Existing algorithms such as OMP-TD are slow to converge, scale poorly to high dimensional spaces, and have not been generalised to the online learning case. We introduce heuristic methods for reducing the search space in high dimensions that significantly reduce computational costs and also act as regularisers. We extend these methods and introduce feature regularisation for incremental feature selection in the batch learning case, and show that introducing a smoothness prior is effective with our SSOMP-TD and STOMP-TD algorithms. Finally we generalise OMP-TD and our algorithms to the online case and evaluate them empirically.LG201

Promoting Sleep Hygiene for Individuals Diagnosed with Parkinson’s Disease: Occupational Therapy’s Distinct Role

Those diagnosed with Parkinson’s disease are more likely to experience sleep performance issues which significantly contribute to poorer health outcomes and earlier institutionalization (Bollu, 2017). Though the field of occupational therapy acknowledges the importance of sleep for overall health and wellbeing, the profession’s role in improving sleep outcomes is largely unexplored. The purpose of this 14-week capstone project was to promote better sleep hygiene practices for individuals with Parkinson’s disease. Additionally, this project sought to advocate for the profession of occupational therapy’s distinct role in sleep management. A variety of goals and objectives were achieved through completion of this project, such as development of advanced practice skills, education, and program development. Based on the findings of this project, the profession of occupational therapy may positively address the occupation of sleep for this population through behavioral and environmental interventions, leading to improved health, well-being, and overall quality of life

The Impact of Climate Change on Ecosystem Carbon Dynamics at the Scandinavian Mountain Birch Forest–Tundra Heath Ecotone

Changes in temperature and moisture resulting from climate change are likely to strongly modify the ecosystem carbon sequestration capacity in high-latitude areas, both through vegetation shifts and via direct warming effects on photosynthesis and decomposition. This paper offers a synthesis of research addressing the potential impacts of climate warming on soil processes and carbon fluxes at the forest–tundra ecotone in Scandinavia. Our results demonstrated higher rates of organic matter decomposition in mountain birch forest than in tundra heath soils, with markedly shallower organic matter horizons in the forest. Field and laboratory experiments suggest that increased temperatures are likely to increase CO2 efflux from both tundra and forest soil providing moisture availability does not become limiting for the decomposition process. Furthermore, colonization of tundra heath by mountain birch forest would increase rates of decomposition, and thus CO2 emissions, from the tundra heath soils, which currently store substantial amounts of potentially labile carbon. Mesic soils underlying both forest and tundra heath are currently weak sinks of atmospheric methane, but the strength of this sink could be increased with climate warming and/or drying

COMBINED USE OF OPEN-AIR AND INDOOR FUMIGATION SYSTEMS TO STUDY EFFECTS OF SO-2 ON LEACHING PROCESSES IN SCOTS PINE LITTER

Both an open-air fumigation system and a laboratory-based system were used to expose decomposing Scots pine (Pinus sylvestris L.) needles to controlled concentrations of SO2 (arithmetric mean less-than-or-equal-to 48 nl litre-1) during a period, in total, of 301 days. The experimental design involved reciprocal litter transplants from 'clean' to 'polluted' air and vice versa, using the two fumigation systems. The objectives were (1) to observe the effects of SO2 on leachate and litter chemistry, (2) to assess whether pollution-induced changes are reversible in clean air, and (3) to test the suitability of small-scale fumigation chambers (litter microcosms) compared with open-air systems in soil studies.Through the formation of SO4(2-) ions, dry-deposited SO2 exhibited a marked capacity to remove 'base' cations (Ca2+, Mg2+ and K+) from decomposing pine needles, and also to acidify litter leachates (as indicated by proton fluxes from the litter). When litter was transferred from polluted air (48 nl litre-1 SO2, in the open-air system) to either clean or polluted air in the laboratory, the effects of prior exposure to SO2 on leachate composition were still evident even after 86 days: the role of base cation depletion within the litter, caused by SO42- -induced leaching, is discussed.Data for SO42- fluxes in leachates collected from the small-scale chambers indicated that dry deposition velocities for SO2 were not anomalously high within this fumigation system. It is therefore concluded that microcosm studies can provide information complementary to the open-air fumigation approach in soils research.</p