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We present experiments to study the relaxation of a nanoscale cylindrical perturbation at one of the two interfaces of a thin viscous freestanding polymeric film. Driven by capillarity, the film flows and evolves toward equilibrium by first symmetrizing the perturbation between the two interfaces and eventually broadening the perturbation. A full-Stokes hydrodynamic model is presented, which accounts for both the vertical and lateral flows and which highlights the symmetry in the system. The symmetrization time is found to depend on the membrane thickness, surface tension, and viscosity.
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Periodic wrinkling of a rigid capping layer on a deformable substrate provides a useful method for templating surface topography for a variety of novel applications. Many experiments have studied wrinkle formation during the compression of a rigid film on a relatively soft pre-strained elastic substrate, and most have focused on the regime where the substrate thickness can be considered semi-infinite relative to that of the film. As the relative thickness of the substrate is decreased, the bending stiffness of the film dominates, causing the bilayer to transition to either local wrinkling or a global buckling instability. In this work optical microscopy was used to study the critical parameters that determine the emergence of local wrinkling or global buckling of freestanding bilayer films consisting of a thin rigid polymer capping layer on a pre-strained elastomeric substrate. The thickness ratio of the film and substrate as well as the pre-strain were controlled and used to create a buckling phase diagram which describes the behaviour of the system as the ratio of the thickness of the substrate is decreased. A simple force balance model was developed to understand the thickness and strain dependences of the wrinkling and buckling modes, with excellent quantitative agreement being obtained with experiments using only independently measured material parameters.
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We study the dewetting of liquid films capped by a thin elastomeric layer. When the tension in the elastomer is isotropic, circular holes grow at a rate which decreases with increasing tension. The morphology of holes and rim stability can be controlled by changing the boundary conditions and tension in the capping film. When the capping film is prepared with a biaxial tension, holes form with a non-circular shape elongated along the high tension axis. With suitable choice of elastic boundary conditions, samples can even be designed such that square holes appear.
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Introduction: Multidomain interventions to address modifiable risk factors for dementia are promising, but require more cost-effective, scalable delivery. This study investigated the feasibility of the "Active Brains" digital behavior change intervention and its trial procedures. Materials and methods: Active Brains aims to reduce cognitive decline by promoting physical activity, healthy eating, and online cognitive training. We conducted 12-month parallel-design randomized controlled feasibility trials of "Active Brains" amongst "lower cognitive scoring" (n = 180) and "higher cognitive scoring" (n = 180) adults aged 60-85. Results: We collected 67.2 and 76.1% of our 12-month primary outcome (Baddeley verbal reasoning task) data for the "lower cognitive score" and "higher cognitive score" groups, respectively. Usage of "Active Brains" indicated overall feasibility and satisfactory engagement with the physical activity intervention content (which did not require sustained online engagement), but engagement with online cognitive training was limited. Uptake of the additional brief telephone support appeared to be higher in the "lower cognitive score" trial. Preliminary descriptive trends in the primary outcome data might indicate a protective effect of Active Brains against cognitive decline, but further investigation in fully-powered trials is required to answer this definitively. Discussion: Whilst initial uptake and engagement with the online intervention was modest, it was in line with typical usage of other digital behavior change interventions, and early indications from the descriptive analysis of the primary outcome and behavioral data suggest that further exploration of the potential protective benefits of Active Brains are warranted. The study also identified minor modifications to procedures, particularly to improve online primary-outcome completion. Further investigation of Active Brains will now seek to determine its efficacy in protecting cognitive performance amongst adults aged 60-85 with varied levels of existing cognitive performance.
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Disfunción Cognitiva , Encéfalo , Cognición , Disfunción Cognitiva/prevención & control , Disfunción Cognitiva/psicología , Ejercicio Físico , Estudios de Factibilidad , HumanosRESUMEN
INTRODUCTION: Cardiothoracic surgical outcomes are poorer in people with diabetes compared with those without diabetes. There are two important uncertainties in the management of people with diabetes undergoing major surgery: (1) how to improve diabetes management in the weeks leading up to an elective procedure and (2) whether that improved management leads to better postoperative outcomes. We previously demonstrated the feasibility of delivering the Optimising Cardiac Surgery ouTcOmes in People with diabeteS (OCTOPuS) intervention, an outpatient intervention delivered by diabetes healthcare professionals for people with suboptimally managed diabetes over 8-12 weeks before elective cardiac surgery. The present study will assess the clinical and cost-effectiveness of the intervention in cardiothoracic centres across the UK. METHODS AND ANALYSIS: A multicentre, parallel group, single-blinded 1:1 individually randomised trial comparing time from surgery until clinically fit for discharge in adults with suboptimally managed type 1 diabetes or type 2 diabetes undergoing elective surgery between the OCTOPuS intervention and usual care (primary endpoint). Secondary endpoints will include actual time from surgery to discharge from hospital; days alive and either out of hospital or judged as clinically fit for discharge; mortality; time on intensive therapy unit (ITU)/ventilator; infections; acute myocardial infarction; change in weight; effect on postoperative renal function and incidence of acute kidney injury; change in HbA1c; frequency and severity of self-reported hypoglycaemia; operations permanently cancelled for suboptimal glycaemic levels; cost-effectiveness; psychosocial questionnaires. The target sample size will be 426 recruited across approximately 15 sites. The primary analysis will be conducted on an intention-to-treat population. A two-sided p value of 0.05 or less will be used to declare statistical significance for all analyses and results will be presented with 95% CIs. ETHICS AND DISSEMINATION: The trial was approved by the South Central-Hampshire A Research Ethics Committee (20/SC/0271). Results will be disseminated through conferences, scientific journals, newsletters, magazines and social media. TRIAL REGISTRATION NUMBER: ISRCTN10170306.
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Procedimientos Quirúrgicos Cardíacos , Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Octopodiformes , Adulto , Animales , Humanos , Estudios Multicéntricos como Asunto , Pacientes Ambulatorios , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
BACKGROUND: Cardiothoracic surgical outcomes are poorer in people with diabetes compared with those without diabetes. There are two important uncertainties in the management of people with diabetes undergoing major surgery: (1) how to improve diabetes management in the weeks leading up to an elective procedure and (2) whether that improved management leads to improved postoperative outcomes. The aim of this study was to develop and pilot a specialist diabetes team-led intervention to improve surgical outcomes in people with diabetes. DESIGN: Open pilot feasibility study SETTING: Diabetes and cardiothoracic surgery departments, University Hospital Southampton NHS Foundation Trust PARTICIPANTS: Seventeen people with diabetes undergoing cardiothoracic surgery INTERVENTION: Following two rapid literature reviews, a prototype intervention was developed based on a previously used nurse-led outpatient intervention and tested. PRIMARY OUTCOME: Feasibility and acceptability of delivering the intervention SECONDARY OUTCOMES: Biomedical data were collected at baseline and prior to surgery. We assessed how the intervention was used. In depth qualitative interviews with participants and healthcare professionals were used to explore perceptions and experiences of the intervention and how it might be improved. RESULTS: Thirteen of the 17 people recruited completed the study and underwent cardiothoracic surgery. All components of the OCTOPuS intervention were used, but not all parts were used for all participants. Minor changes were made to the intervention as a result of feedback from the participants and healthcare professionals. Median (IQR) HbA1c was 10 mmol/mol (3, 13) lower prior to surgery than at baseline. CONCLUSION: This study has shown that it is possible to develop a clinical pathway to improve diabetes management prior to admission. The clinical and cost-effectiveness of this intervention will now be tested in a multicentre randomised controlled trial in cardiothoracic centres across the UK. TRIAL REGISTRATION: ISRCTN; ISRCTN10170306 . Registered 10 May 2018.
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BACKGROUND: By 2050, worldwide dementia prevalence is expected to triple. Affordable, scalable interventions are required to support protective behaviours such as physical activity, cognitive training and healthy eating. This paper outlines the theory-, evidence- and person-based development of 'Active Brains': a multi-domain digital behaviour change intervention to reduce cognitive decline amongst older adults. METHODS: During the initial planning phase, scoping reviews, consultation with PPI contributors and expert co-investigators and behavioural analysis collated and recorded evidence that was triangulated to inform provisional 'guiding principles' and an intervention logic model. The following optimisation phase involved qualitative think aloud and semi-structured interviews with 52 older adults with higher and lower cognitive performance scores. Data were analysed thematically and informed changes and additions to guiding principles, the behavioural analysis and the logic model which, in turn, informed changes to intervention content. RESULTS: Scoping reviews and qualitative interviews suggested that the same intervention content may be suitable for individuals with higher and lower cognitive performance. Qualitative findings revealed that maintaining independence and enjoyment motivated engagement in intervention-targeted behaviours, whereas managing ill health was a potential barrier. Social support for engaging in such activities could provide motivation, but was not desirable for all. These findings informed development of intervention content and functionality that appeared highly acceptable amongst a sample of target users. CONCLUSIONS: A digitally delivered intervention with minimal support appears acceptable and potentially engaging to older adults with higher and lower levels of cognitive performance. As well as informing our own intervention development, insights obtained through this process may be useful for others working with, and developing interventions for, older adults and/or those with cognitive impairment.
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BACKGROUND: Increasing physical activity, improving diet, and performing brain training exercises are associated with reduced cognitive decline in older adults. OBJECTIVE: In this paper, we describe a feasibility trial of the Active Brains intervention, a web-based digital intervention developed to support older adults to make these 3 healthy behavior changes associated with improved cognitive health. The Active Brains trial is a randomized feasibility trial that will test how accessible, acceptable, and feasible the Active Brains intervention is and the effectiveness of the study procedures that we intend to use in the larger, main trial. METHODS: In the randomized controlled trial (RCT), we use a parallel design. We will be conducting the intervention with 2 populations recruited through GP practices (family practices) in England from 2018 to 2019: older adults with signs of cognitive decline and older adults without any cognitive decline. Trial participants were randomly allocated to 1 of 3 study groups: usual care, the Active Brains intervention, or the Active Brains website plus brief support from a trained coach (over the phone or by email). The main outcomes are performance on cognitive tasks, quality of life (using EuroQol-5D 5 level), Instrumental Activities of Daily Living, and diagnoses of dementia. Secondary outcomes (including depression, enablement, and health care costs) and process measures (including qualitative interviews with participants and supporters) will also be collected. The trial has been approved by the National Health Service Research Ethics Committee (reference 17/SC/0463). RESULTS: Results will be published in peer-reviewed journals, presented at conferences, and shared at public engagement events. Data collection was completed in May 2020, and the results will be reported in 2021. CONCLUSIONS: The findings of this study will help us to identify and make important changes to the website, the support received, or the study procedures before we progress to our main randomized phase III trial. TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number 23758980; http://www.isrctn.com/ISRCTN23758980. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/18929.
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We present the results of experimental determination of the heat capacity of the pyrochlore Er2Ti2O7 as a function of temperature (0.35-300 K) and magnetic field (up to 9 T), and for magnetically diluted solid solutions of the general formula (Er1-x Y x )2Ti2O7 (x≤0.471). On either doping or increase of magnetic field, or both, the Néel temperature first shifts to lower temperature until a critical point above which there is no well-defined transition but a Schottky-like anomaly associated with the splitting of the ground state Kramers doublet. By taking into account details of the lattice contribution to the heat capacity, we accurately isolate the magnetic contribution to the heat capacity and hence to the entropy. For pure Er2Ti2O7 and for (Er1-x Y x )2Ti2O7, the magnetic entropy as a function of temperature evolves with two plateaus: the first at [Formula: see text], and the other at [Formula: see text]. When a very high magnetic field is applied, the first plateau is washed out. The influence of dilution at low values is similar to the increase of magnetic field, as we show by examination of the critical temperature versus critical field curve in reduced terms.
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Thermal properties of a series of type II clathrates of the formula NaxSi136 with 0 < x < 24 and Na guests occupying the Si cages have been investigated over the temperature range from 2 to 300 K. Heat capacity and thermal conductivity results show that the structure is remarkably responsive to the loading of Na guests. The response is phononic: the host lattice expands in a non-monotonic way, and first stiffens, then relaxes at low loading into the larger Si28 cages (x < 9), then stiffens again as the Na concentration increases further. The response is also electronic, through changes in electronic properties as additional Na is loaded into the smaller Si20 cages at high loading (x > 9). In total, the influence of the guest loading illustrates the complexities of structure-property relations in a guest-host system.