6,385 research outputs found
Grip strength from midlife as an indicator of later-life brain health and cognition: evidence from a British birth cohort
Background: Grip strength is an indicator of physical function with potential predictive value for health in ageing populations. We assessed whether trends in grip strength from midlife predicted later-life brain health and cognition. Methods: 446 participants in an ongoing British birth cohort study, the National Survey of Health and Development (NSHD), had their maximum grip strength measured at ages 53, 60â64, and 69, and subsequently underwent neuroimaging as part of a neuroscience sub-study, referred to as âInsight 46â, at age 69â71. A group-based trajectory model identified latent groups of individuals in the whole NSHD cohort with below- or above-average grip strength over time, plus a reference group. Group assignment, plus standardised grip strength levels and change from midlife were each related to measures of whole-brain volume (WBV) and white matter hyperintensity volume (WMHV), plus several cognitive tests. Models were adjusted for sex, body size, head size (where appropriate), sociodemographics, and behavioural and vascular risk factors. Results: Lower grip strength from midlife was associated with smaller WBV and lower matrix reasoning scores at age 69â71, with findings consistent between analysis of individual time points and analysis of trajectory groups. There was little evidence of an association between grip strength and other cognitive test scores. Although greater declines in grip strength showed a weak association with higher WMHV at age 69â71, trends in the opposite direction were seen at individual time points with higher grip strength at ages 60â64, and 69 associated with higher WMHV. Conclusions: This study provides preliminary evidence that maximum grip strength may have value in predicting brain health. Future work should assess to what extent age-related declines in grip strength from midlife reflect concurrent changes in brain structure
Mild Parkinsonian Signs: A Systematic Review of Clinical, Imaging, and Pathological Associations
Mild parkinsonian signs (MPS) have been widely studied during the past 3 decades and proposed as a risk marker for neurodegenerative disease. This systematic review explores the epidemiology, clinical and prognostic associations, radiological features, and pathological findings associated with MPS in older adults free from neurodegenerative disease. We find that MPS as currently defined are strongly associated with increasing age and increased risk of development of Parkinson's disease (PD), all-cause dementia, disability, and death. Positive associations with later PD are found mainly in younger populations and those with other features of prodromal PD. There are currently no consistent radiological findings for MPS, and pathological studies have shown that MPS, at least in the oldest old, are often underpinned by mixed neuropathologies, including those associated with Alzheimer's disease, cerebrovascular disease, nigral neuronal loss, and Lewy bodies. Different subcategories of MPS appear to convey varying risk and specificity for PD and other outcomes. MPS overall are not specific for parkinsonian disorders and, although associated with increased risk of PD, can reflect multiple pathologies, particularly in older individuals. âMild motor signsâ appears a more appropriate term to avoid prognostic and pathological implications, and larger future studies to prospectively examine outcomes and associations of specific MPS subcategories are required
China's energy-water nexus - assessment of the energy sector's compliance with the "3 Red Lines" industrial water policy
Increasing population and economic growth continue to drive China's demand for energy and water resources. The interaction of these resources is particularly important in China, where water resources are unevenly distributed, with limited availability in coal-rich regions. The â3 Red Linesâ water policies were introduced in 2011; one of their aims is to reduce industrial water use, of which the energy sector is a part. This paper analyses current water withdrawals and consumption for all energy processes and assesses the sector's compliance with the industrial water policy under different scenarios, considering potential future policy and technological changes. The results show that future energy plans could conflict with the industrial water policy, but the amount of water used in the energy sector is highly dependant on technology choices, especially for power plant cooling. High electricity demand in the future is expected to be met mainly by coal and nuclear power, and planned inland development of nuclear power presents a new source of freshwater demand. Taking a holistic view of energy and water-for-energy enables the identification of co-benefits and trade-offs between energy and water policies that can facilitate the development of more compatible and sustainable energy and water plans.The authors would like to thank EPSRC and BP (Grant no. RG60538) for their funding support.This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0301421515001196#
Distributed model predictive control of linear systems with persistent disturbances
This article presents a new form of robust distributed model predictive control (MPC) for multiple dynamically decoupled subsystems, in which distributed control agents exchange plans to achieve satisfaction of coupling constraints. The new method offers greater flexibility in communications than existing robust methods, and relaxes restrictions on the order in which distributed computations are performed. The local controllers use the concept of tube MPC â in which an optimisation designs a tube for the system to follow rather than a trajectory â to achieve robust feasibility and stability despite the presence of persistent, bounded disturbances. A methodical exploration of the trades between performance and communication is provided by numerical simulations of an example scenario. It is shown that at low levels of inter-agent communication, distributed MPC can obtain a lower closed-loop cost than that obtained by a centralised implementation. A further example shows that the flexibility in communications means the new algorithm has a relatively low susceptibility to the adverse effects of delays in computation and communication
Not all low-carbon energy pathways are environmentally "no-regrets" options
Energy system pathways which are projected to deliver minimum possible deployment cost, combined with low Greenhouse Gas (GHG) emissions, are usually considered as âno-regretsâ options. However, the question remains whether such energy pathways present âno-regretsâ when also considering the wider environmental resource impacts, in particular those on land and water resources. This paper aims to determine whether the energy pathways of the UKâs Carbon Plan are environmental âno-regretsâ options, defined in this study as simultaneously exhibiting low impact on land and water services resulting from resource appropriation for energy provision. This is accomplished by estimating the land area and water abstraction required by 2050 under the four pathways of the Carbon Plan with different scenarios for energy crop composition, yield, and power station locations. The outcomes are compared with defined limits for sustainable land appropriation and water abstraction.
The results show that of the four Carbon Plan pathways, only the âHigher Renewables, more energy efficiencyâ pathway is an environmental âno-regretsâ option, and that is only if deployment of power stations inland is limited. The study shows that policies for future low-carbon energy systems should be developed with awareness of wider environmental impacts. Failing to do this could lead to a setback in achieving GHG emission reductions goals, because of unforeseen additional competition between the energy sector and demand for land and water services in other sectors.This work has been funded by Engineering and Physical Sciences Research Council (EPSRC) through the Whole System Energy Modelling (wholeSEM) consortium. EPSRC Grant number EP/K039326/1This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.gloenvcha.2015.10.00
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Importance of food-demand management for climate mitigation
Recent studies show that current trends in yield improvement will not be sufficient to meet projected global food demand in 2050, and suggest that a further expansion of agricultural area will be required. However, agriculture is the main driver of losses of biodiversity and a major contributor to climate change and pollution, and so further expansion is undesirable. The usual proposed alternative - intensification with increased resource use - also has negative effects. It is therefore imperative to find ways to achieve global food security without expanding crop or pastureland and without increasing greenhouse gas emissions. Some authors have emphasised a role for sustainable intensification in closing global 'yield gaps' between the currently realised and potentially achievable yields. However, in this paper we use a transparent, data-driven model, to show that even if yield gaps are closed, the projected demand will drive further agricultural expansion. There are, however, options for reduction on the demand side that are rarely considered. In the second part of this paper we quantify the potential for demand-side mitigation options, and show that improved diets and decreases in food waste are essential to deliver emissions reductions, and to provide global food security in 2050.This work was funded by a grant to the University of Cambridge from BP as part of their Energy Sustainability Challenge.This is the accepted manuscript version. The final version is available from Nature Climate Change at http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2353.html
Land use implications of future energy system trajectories-The case of the UK 2050 Carbon Plan
The UK's 2008 Climate Change Act sets a legally binding target for reducing territorial greenhouse gas emissions by 80% by 2050, relative to 1990 levels. Four pathways to achieve this target have been developed by the Department of Energy and Climate Change, with all pathways requiring increased us of bioenergy. A significant amount of this could be indigenously sourced from crops, but will increased domestic production of energy crops conflict with other agricultural priorities? To address this question, a coupled analysis of the UK energy system and land use has been developed. The two systems are connected by the production of bioenergy, and are projected forwards in time under the energy pathways, accounting for various constraints on land use for agriculture and ecosystem services. The results show different combinations of crop yield and compositions for the pathways lead to the appropriation of between 7 and 61% of UK's agricultural land for bioenergy production. This could result in competition for land for food production and other land uses, as well as indirect land use change in other countries due to an increase in bioenergy imports. Consequently, the potential role of bioenergy in achieving UK emissions reduction targets may face significant deployment challenges.This work has been funded by ESPRC through the Whole System Energy Modelling (wholeSEM) consortium. EPSRC Grant number EP/K039326/1.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.enpol.2015.07.00
Size and shape constancy in consumer virtual reality
With the increase in popularity of consumer virtual reality headsets, for research and other applications, it is important to understand the accuracy of 3D perception in VR. We investigated the perceptual accuracy of near-field virtual distances using a size and shape constancy task, in two commercially available devices. Participants wore either the HTC Vive or the Oculus Rift and adjusted the size of a virtual stimulus to match the geometric qualities (size and depth) of a physical stimulus they were able to refer to haptically. The judgments participants made allowed for an indirect measure of their perception of the egocentric, virtual distance to the stimuli. The data show under-constancy and are consistent with research from carefully calibrated psychophysical techniques. There was no difference in the degree of constancy found in the two headsets. We conclude that consumer virtual reality headsets provide a sufficiently high degree of accuracy in distance perception, to allow them to be used confidently in future experimental vision science, and other research applications in psychology
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Re-framing the threat of global warming: an empirical causal loop diagram of climate change, food insecurity and societal collapse
Funder: The General Sir John Monash FoundationFunder: The Cambridge TrustAbstractThere is increasing concern that climate change poses an existential risk to humanity. Understanding these worst-case scenarios is essential for good risk management. However, our knowledge of the causal pathways through which climate change could cause societal collapse is underdeveloped. This paper aims to identify and structure an empirical evidence base of the climate change, food insecurity and societal collapse pathway. We first review the societal collapse and existential risk literature and define a set of determinants of societal collapse. We develop an original methodology, using these determinants as societal collapse proxies, to identify an empirical evidence base of climate change, food insecurity and societal collapse in contemporary society and then structure it using a novel-format causal loop diagram (CLD) defined at global scale and national granularity. The resulting evidence base varies in temporal and spatial distribution of study and in the type of data-driven methods used. The resulting CLD documents the spread of the evidence base, using line thickness and colour to depict density and type of data-driven method respectively. It enables exploration of how the effects of climate change may undermine agricultural systems and disrupt food supply, which can lead to economic shocks, socio-political instability as well as starvation, migration and conflict. Suggestions are made for future work that could build on this paper to further develop our qualitative understanding of, and quantitative complex systems modelling capabilities for analysing, the causal pathways between climate change and societal collapse.</jats:p
Performance optimization of a leagility inspired supply chain model: a CFGTSA algorithm based approach
Lean and agile principles have attracted considerable interest in the past few decades. Industrial sectors throughout the world are upgrading to these principles to enhance their performance, since they have been proven to be efficient in handling supply chains. However, the present market trend demands a more robust strategy incorporating the salient features of both lean and agile principles. Inspired by these, the leagility principle has emerged, encapsulating both lean and agile features. The present work proposes a leagile supply chain based model for manufacturing industries. The paper emphasizes the various aspects of leagile supply chain modeling and implementation and proposes a new Hybrid Chaos-based Fast Genetic Tabu Simulated Annealing (CFGTSA) algorithm to solve the complex scheduling problem prevailing in the leagile environment. The proposed CFGTSA algorithm is compared with the GA, SA, TS and Hybrid Tabu SA algorithms to demonstrate its efficacy in handling complex scheduling problems
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