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SAT-779 Monte Carlo resampling validates use of bone mineral density as surrogate to replace fracture in future randomized trials of osteoporosis treatments: results from SABRE
Get PDFPrehabilitation for lumbar spinal stenosis: understanding mechanisms and contexts for enhanced engagement—a realist review
Get PDFBackground
Neurogenic claudication (NC) due to lumbar spinal stenosis is the most common reason for spinal surgery in older adults. Prehabilitation may improve outcomes and reduce costs, but current evidence is conflicting. It remains unclear who benefits most, which mechanisms optimise outcomes and what outcomes matter to patients. This review aimed to develop a programme theory explaining what works, for whom, how and in what contexts for prehabilitation of NC surgical candidates.
Methods
An initial programme theory, comprising context-mechanism-outcome configurations (CMOCs), was developed through iterative mapping and consultation with experts (n = 6) and patients (n = 7). This theory was refined via two systematic literature searches and further stakeholder feedback. Studies were assessed for relevance, richness and rigour. Data were holistically coded using abductive and retroductive reasoning to create causal maps, which informed CMOC refinement.
Results
From 1422 records, 67 papers were included. The final programme theory included 14 CMOCs focused on patient engagement, a priority identified through patient consultation. Engagement was contingent on clear, consistent communication and addressing misconceptions among both patients and professionals. A shared understanding increased perceived value and avoided missed opportunities for preparation. Personalisation and collaborative goal-setting enhanced ownership and motivation. Ongoing support—via healthcare professional contact and peer input—helped counteract anxiety and feelings of abandonment during the surgical wait.
Conclusions
Engagement with prehabilitation for NC can be improved through clear communication, tailored interventions and sustained support. Further research is needed to test whether theory-informed programmes improve outcomes in this population
Daily evolution of VOCs in Beijing: chemistry, emissions, transport, and policy implications
No full textVolatile organic compounds (VOCs) are important precursors to the formation of ozone (O3) and secondary organic aerosols (SOA) and can also have direct human health impacts. The emissions of VOCs remain poorly characterized due to the complexity and variability of their sources. The VOC levels in Beijing during the winter campaign (APHH) were investigated using a dispersion model (NAME), and a chemical box model (AtChem2) in order to understand how chemistry and transport affect the VOC concentrations in Beijing. Emissions of VOCs in Beijing and contributions from outside Beijing were modelled using the NAME dispersion model combined with the emission inventories and were used to initialize the AtChem2 box model. The modelled concentrations of VOCs from the NAME-AtChem2 combination were then compared to the output of a chemical transport model (GEOS-Chem). The results from the emission inventories and the NAME air mass pathways suggest that industrial sources to the south of Beijing and within Beijing during the winter campaign are very important in controlling the VOC levels in Beijing. A number of scenarios with different nitrogen oxides to ozone ratios (NOx/O3) and hydroxyl (OH) levels were simulated to determine the changes in VOC levels. In Beijing over 80 % of VOC are emitted locally during winter. Most scenarios are in good agreement with daily GEOS-Chem simulations, with the best agreements seen for the modelled concentrations of ethanol, benzene and propane with correlation coefficients of 0.67, 0.63 and 0.64 respectively. Furthermore, the production of formaldehyde in an air mass within 24 h of travel from Beijing was investigated, and it was estimated that 90 % of formaldehyde in Beijing is secondary, produced from oxidation of non-methane volatile organic compounds (NMVOCs). The benzene/CO and toluene/CO ratios during the campaign are very similar to the ratio derived from literature for 2014 in Beijing, however more data are needed to enable investigation of more species over longer timeframes to determine whether this ratio can be applied to predicting VOCs in Beijing. The results suggest that VOC concentrations in Beijing are driven predominantly by sources within Beijing and by local atmospheric chemistry during the winter. Moreover, the relationship of the NOx/VOC and O3 shows that the VOCs during the winter campaign are possibly emitted from similar sources as NOx
Calculation of minimum energy pathways in transport proteins
No full textAlthough static structures of protein metastable states are well-studied, the fleeting transitions between these states are difficult to experimentally observe or predict. We present a computationally inexpensive algorithm, “cold-inbetweening”, which generates trajectories between experimentally determined end-states. Here we apply cold-inbetweening to provide mechanistic insight into the ubiquitous alternate access model of operation in three membrane transporter superfamilies. Here, we study DraNramp from Deinococcus radiodurans, MalT from Bacillus cereus, and MATE from Pyrococcus furiosus. In MalT, the trajectory demonstrates elevator transport through unwinding of a supporter arm helix, maintaining adequate space to transport maltose. In DraNramp, outward-gate closure occurs prior to inward-gate opening, in accordance with the alternate access hypothesis. In the MATE transporter, switching conformation involves obligatory rewinding of the N-terminal helix to avoid steric backbone clashes. This concurrently plugs the cavernous ligand-binding site mid-conformational change. Cold-inbetweening can generate hypotheses about large functionally relevant protein conformational changes
Discrete Integrable Principal Chiral Field Model and Its Involutive Reduction
Get PDFWe discuss an integrable discretization of the principal chiral field models equations and its involutive reduction. We present a Darboux transformation and general construction of soliton solutions for these discrete equations
Inter-turbine modelling of wind-farm power using multi-task learning
Get PDFBecause of the global need to increase power production from renewable energy resources, developments in the online monitoring of the associated infrastructure is of interest to reduce operation and maintenance costs. However, challenges exist for data-driven approaches to this problem, such as incomplete or limited histories of labelled damage-state data, operational and environmental variability, or the desire for the quantification of uncertainty to support risk management. This work first introduces a probabilistic regression model for predicting wind-turbine power, which adjusts for wake-effects learned from data. Spatial correlations in the learned model parameters for different tasks (turbines) are then leveraged in a hierarchical Bayesian model (an approach to multi-task learning) to develop a “metamodel”, which can be used to make power-predictions which adjust for turbine location—including on previously unobserved turbines not included in the training data. The results show that the metamodel is able to outperform a series of benchmark models, while demonstrating a novel strategy for making efficient use of data for inference in populations of structures, in particular where correlations exist in the variable(s) of interest (such as those from wind-turbine wake-effects)
Industry 5.0 and the Future of Sustainable Manufacturing:Human-centric Innovation, Circularity and Resilience
No full textGlycerol oleate tribofilms: Relationships between chemical composition and tribological performance
Get PDFGlycerol oleates (GO) are organic friction modifiers (OFMs) with lower toxicity than traditional P- and S-containing friction modifiers. They are increasingly used in lubricant formulations but the mechanisms by which they lower friction and protect surfaces in the boundary lubrication regime are still not well understood. We have determined tribological performance and the chemical nature of tribofilms formed on steel for model formulations of glycerol monooleate, trioleate (GMO, triolein) and their mixture with glycerol dioleate (GDO) as a function of sliding-rolling ratio (% SRR) and temperature. Formulations of GMO, triolein and the mixed GOs in PAO4 base oil were tested at a low entrainment speed of 0.02 m/s and two different temperatures, 60°C and 100°C, in a mini traction machine (MTM) tribometer, with SRRs from pure sliding to pure rolling conditions. The thickness of tribofilms formed was tracked by spacer layer image mapping (SLIM), and their chemical composition was examined using ToF-SIMS. Temperature is correlated with film thickness, which subsequently influences the frictional performance of additives. Higher temperatures promote the formation of thicker films, resulting in lower friction for all additives. ToF-SIMS analysis identified a transition from physisorption at low temperatures and SRRs to chemisorption-dominated friction reduction at higher temperatures and SRRs
Role of structural changes at vitrification and glass–liquid transition
Get PDFStructural rearrangements at calorimetric glass transition are behind drastic changes of material characteristics, causing differences between glasses and melts. Structural description of materials includes both species (atoms, molecules) and connecting bonds, which are directly affected by changing conditions such as the increase of temperature. At and above the glass transition a macroscopic percolation cluster made up of configurons (broken bonds) is formed, an account of which enables unambiguous structural differentiation of glasses from melts. Connection of transition caused by configuron percolation is also discussed in relation to the Noether theorem, Anderson localisation, and melting criteria of condensed matter
Cortical morphology changes in default mode network regions as predictors of cognitive decline in relation to amyloid and tau deposits
Get PDFAlzheimer’s disease can be classified based on amyloid, tau and neurodegeneration status. The Default Mode Network is notably vulnerable to these processes, making early structural alterations in this network of particular interest for identifying prodromal biomarkers. In this longitudinal cross-sectional study, we analysed data from 279 participants in the Alzheimer’s Disease Neuroimaging Initiative (mean age = 73.7 ± 9 years, 53.2% males). Structural measures—sulcal depth, gyrification and cortical thickness—were extracted for all Default Mode Network regions. Their ability to predict memory performance (encoding, retrieval and recall) was tested at baseline and 2-year follow-up by means of multiple linear regression models, which were all corrected for the risk of multiple comparisons. Covariates included Mini Mental State Examination scores, amyloid status and regional tau burden, to examine interactions with structural changes. Our results showed distinct Default Mode Network alteration patterns based on tau burden and amyloid status, highlighting patterns of morphological features with different susceptibility to proteinopathy. In individuals with concordant (both positive or both negative) amyloid and tau status, preserved structural integrity and complexity were linked to better cognitive performance and appeared protective against decline. However, mainly negative associations were instead observed in individuals with discordant amyloid or tau status (i.e. positive for only either amyloid or tau accumulation). We discuss these findings as a possible reflection of a mismatch between abnormal protein accumulation and structural damage in these populations. The multimodal nature of this study helps clarifying the heterogeneous findings reported in existing literature regarding structural integrity and cognitive outcomes in Alzheimer’s disease
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