A Numerical Bubbly Flow Investigation of Drag Reduction for Underwater Vehicles

This paper discusses the numerical investigation of dispersed bubbly flow within the boundary layer of a fully submerged axisymmetric body in horizontal position. The aim is to analyse the influence of injection position and bubble parameters on the drag reduction behaviour. The numerical study is conducted with the commercial CFD package ANSYS Fluent using the Eulerian-Eulerian modelling approach. Several sets of simulations are carried out with air injection velocities in the rage of 1 m/s to 15 m/s, injection locations between 0 and 0.5 m, and bubble diameters from 0.1 mm to 2 mm. In order to obtain the percentage drag reduction the results are correlated with a model without air injection. The simulations demonstrate a different behaviour between small and large bubble diameters of 0.1 mm and 2 mm respectively. Small bubbles archive drag reduction rates around 10% almost independent from the injection velocity and position, while large bubbles are highly affected by those parameters. The maximum drag reduction of 20.67% is achieved by injecting bubbles of 2 mm diameter with a velocity of 12.5 m/s at the tip of the prow nose. It is presented that the drag reduction increases with increasing injection velocity and bubble diameter. These parameters enable the bubbles to build up a continuous film across large parts of the hull which is required for a sufficient drag reduction

Supporting automatic recovery in offloaded distributed programming models through MPI-3 techniques

In this paper we describe the design of fault tolerance capabilities for general-purpose offload semantics, based on the OmpSs programming model. Using ParaStation MPI, a production MPI-3.1 implementation, we explore the features that, being standard compliant, an MPI stack must support to provide the necessary fault tolerance guarantees, based on MPI's dynamic process management. Our results, including synthetic benchmarks and applications, reveal low runtime overhead and efficient recovery, demonstrating that the existing MPI standard provided us with sufficient mechanisms to implement an effective and efficient fault-tolerant solution.This research received funding from the European Community’s 7th Framework Programme via the DEEP-ER project under Grant Agreement no. 610476. This work has also been supported by the Spanish Ministry of Science and Innovation (contract TIN2012-34557) and by Generalitat de Catalunya (contracts 2014-SGR-1051 and 2014-SGR-1272). Antonio J. Peña is cofinanced by the Spanish Ministry of Economy and Competitiveness under Juan de la Cierva fellowship number IJCI-2015-23266. The authors thank Jorge Bell´on, from BSC, for his technical support with the Nanos++ internals.Peer ReviewedPostprint (author's final draft

Barriers to physical activity in older adults in Germany: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Data on barriers to physical activity in older adults in Germany are scarce. The aim of this study was to analyse barriers to physical activity in a cohort of older adults, allowing comparisons between men and women, and age groups.</p> <p>Methods</p> <p>1,937 older adults with a median age of 77 (range 72-93) years (53.3% female) took part in the 7-year follow-up telephone interviews of the getABI cohort. Participants who stated that they did not get enough physical activity were surveyed with respect to barriers to physical activity. Barriers were analysed for all respondents, as well as by sex and age group for cases with complete data. Multivariate logistic regression analysis was performed to evaluate differences between sexes and age groups. The level of significance (alpha < 0.05) was adjusted for multiple testing according to Bonferroni (p < .004).</p> <p>Results</p> <p>1,607 (83.0%) participants stated that they were sufficiently physically active. 286 participants rated their physical activity as insufficient and responded to questions on barriers to physical activity completely. The three most frequently cited barriers were poor health (57.7%), lack of company (43.0%), and lack of interest (36.7%). Lack of opportunities for sports or leisure activities (30.3% vs. 15.6%), and lack of transport (29.0% vs. 7.1%) were more frequently stated by female respondents than male respondents. These differences between men and women were significant (p = .003; p < .001) after adjustment for respondents' age. Analyses by age groups revealed that poor health was more frequently considered a barrier to physical activity by participants aged 80+ years compared to the younger age group (71.1% vs. 51.5%). This age-dependent difference was significant (p = .002) irrespective of the participants' sex.</p> <p>Conclusions</p> <p>The present study provides relevant data on barriers to physical activity in older adults. By revealing appreciable differences between men and women, and age groups, this study has implications for efforts to increase older adults' physical activity. Promotion and intervention strategies should consider the barriers and tailor measures to the specific needs of older adults in order to reduce their constraints to physical activity.</p

Effects of an exercise programme for chronically ill and mobility-restricted elderly with structured support by the general practitioner's practice (HOMEfit) - study protocol of a randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Exercise programmes can be administered successfully as therapeutic agents to patients with a number of chronic diseases and help to improve physical functioning in older adults. Usually, such programmes target either healthy and mobile community-dwelling seniors or elderly individuals living in nursing institutions or special residences. Chronically ill or mobility-restricted individuals, however, are difficult to reach when they live in their own homes.</p> <p>A pilot study has shown good feasibility of a home-based exercise programme that is delivered to this target group through cooperation between general practitioners and exercise therapists. A logical next step involves evaluation of the effects of the programme.</p> <p>Methods/design</p> <p>The study is designed as a randomised controlled trial. We plan to recruit 210 patients (≥ 70 years) in about 15 general practices.</p> <p>The experimental intervention (duration 12 weeks)-a multidimensional home-based exercise programme-is delivered to the participant by an exercise therapist in counselling sessions at the general practitioner's practice and on the telephone. It is based on methods and strategies for facilitating behaviour change according to the Health Action Process Approach (HAPA). The control intervention-baseline physical activities-differs from the experimental intervention with regard to content of the counselling sessions as well as to content and frequency of the promoted activities.</p> <p>Primary outcome is functional lower body strength measured by the "chair-rise" test. Secondary outcomes are: physical function (battery of motor tests), physical activity (step count), health-related quality of life (SF-8), fall-related self-efficacy (FES-I), and exercise self-efficacy (SSA-Scale).</p> <p>The hypothesis that there will be differences between the two groups (experimental/control) with respect to post-interventional chair-rise time will be tested using an ANCOVA with chair-rise time at baseline, treatment group, and study centre effects as explanatory variables. Analysis of the data will be undertaken using the principle of intention-to-treat.</p> <p>Trial registration</p> <p>Current Controlled Trials <a href="http://www.controlled-trials.com/ISRCTN17727272">ISRCTN17727272</a>.</p

Sport for Adults Aged 50+ Years: Participation Benefits and Barriers

Despite the health benefits of sport, the proportion of people participating in sport decreases with age. This qualitative study explored the benefits and barriers regarding older adult community sport participation, from the perspective of national sporting organizations, in addition to older adult sport club and nonsport club members, across eight focus group interviews (n = 49). Seven benefits were discussed, primarily social and physical health and intergenerational opportunities. Ten barriers were also discussed, including physical health, time constraints, and lack of appropriate playing opportunities. Ensuring access to activities that can benefit social health is of great importance to older adults. As sport can provide participation opportunities across generations, it can be an ideal physical activity option for this age group. However, a major barrier is that sport policy often prioritizes the participation for younger age groups. Policymakers should include a focus on older adults, to derive social health benefits.Peer reviewedFinal Accepted Versio

Recruiting Hard-to-Reach Subjects for Exercise Interventions: A Multi-Centre and Multi-Stage Approach Targeting General Practitioners and Their Community-Dwelling and Mobility-Limited Patients

The general practitioner (GP)’s practice appears to be an ideal venue for recruiting community-dwelling older adults with limited mobility. This study (Current Controlled Trials ISRCTN17727272) aimed at evaluating the recruiting process used for a multi-centre exercise intervention (HOMEfit). Each of six steps resulted in an absolute number of patients (N1–N6). Sex and age (for N4–N6) and reasons for dropping out were assessed. Patient database screening (N1–N3) at 15 GP practices yielded N1 = 5,990 patients aged 70 and above who had visited their GP within the past 6 months, N2 = 5,467 after exclusion of institutionalised patients, N3 = 1,545 patients eligible. Using a pre-defined limitation algorithm in order to conserve the practices’ resources resulted in N4 = 1,214 patients (80.3 ± 5.6 years, 68% female), who were then officially invited to the final assessment of eligibility at the GP’s practice. N5 = 434 patients (79.5 ± 5.4 years, 69% female) attended the practice screening (n = 13 of whom had not received an official invitation). Finally, N6 = 209 (79.8 ± 5.2 years, 74% female) were randomised after they were judged eligible and had given their written informed consent to participate in the randomised controlled trial (overall recruitment rate: 4.4%). The general strategy of utilising a GP’s practice to recruit the target group proved beneficial. The data and experiences presented here can help planners of future exercise-intervention studies

Participant and Public Involvement in Refining a Peer-Volunteering Active Aging Intervention: Project ACE (Active, Connected, Engaged)

© The Author(s) 2016. Background Evidence for the health benefits of a physically active lifestyle among older adults is strong, yet only a small proportion of older people meet physical activity recommendations. A synthesis of evidence identified "best bet" approaches, and this study sought guidance from end-user representatives and stakeholders to refine one of these, a peer-volunteering active aging intervention. Methods Focus groups with 28 older adults and four professional volunteer managers were conducted. Semi-structured interviews were conducted with 9 older volunteers. Framework analysis was used to gauge participants' views on the ACE intervention. Results Motives for engaging in community groups and activities were almost entirely social. Barriers to participation were lack of someone to attend with, lack of confidence, fear of exclusion or "cliquiness" in established groups, bad weather, transport issues, inaccessibility of activities, ambivalence, and older adults being "set in their ways". Motives for volunteering included "something to do," avoiding loneliness, the need to feel needed, enjoyment, and altruism. Challenges included negative events between volunteer and recipient of volunteering support, childcare commitments, and high volunteering workload. Conclusion Peer-volunteering approaches have great potential for promotion of active aging. The systematic multistakeholder approach adopted in this study led to important refinements of the original ACE intervention. The findings provide guidance for active aging community initiatives highlighting the importance of effective recruitment strategies and of tackling major barriers including lack of motivation, confidence, and readiness to change; transport issues; security concerns and cost; activity availability; and lack of social support

Improving Patients' Adherence to Physical Activity in Diabetes Mellitus: A Review

Regular physical activity (PA) is a key element in the prevention and management of type 2 diabetes mellitus (T2DM). Participation in regular PA improves blood glucose control and can prevent or delay T2DM and its complications, along with positively affecting lipids, blood pressure, cardiovascular events, mortality, and quality of life. However, most people with T2DM are not active and show poor adherence. This paper reviews the possible barriers to PA and strategies to improve the adherence to PA. Based on the currently available literature, it is concluded that self-efficacy and social support from family, friends, and health care providers play the important role in adoption and maintenance of regular PA. Here we also highlight some new modern and innovative interventions that facilitate exercise participation and improve the adherence

A Qualitative Investigation of Physical Activity Compensation Among Older Adults

ObjectivesThis study explored the mechanisms of physical activity (PA) compensation among older adults who recently reduced their non-exercise physical activity (NEPA) in response to a structured PA intervention.DesignA post-trial, retrospective qualitative process evaluation using interviews was employed.MethodsLevels of PA compensation were determined by comparing NEPA prior to and during the final week of a 4-week structured PA intervention. Those who reduced their NEPA by 10% or greater were considered as compensators. Interviews were conducted with older adult compensators (mean age = 58.56 ± 3.88 years; n = 9), employing thematic analysis to identify potential mechanisms of PA compensation.ResultsThe findings suggest that the majority of participants were unaware that they had compensated in their PA, suggesting that this may be a non-volitional process. Most participants perceived PA compensation to hold negative implications for health and well-being. Physiological processes of fatigue and delayed onset of muscle soreness were cited as the principal cause of PA compensation, whereas psychological processes including a drive to be inactive, fear of overexertion, deficient motivation, and perceived time constraints were cited to a lesser extent.ConclusionA range of physiological and psychological compensatory barriers were identified. Implications of and methods to overcome these compensatory barriers are discussed