Random boundaries: quantifying segmentation uncertainty in solutions to boundary-value problems

Engineering simulations using boundary-value partial differential equations often implicitly assume that the uncertainty in the location of the boundary has a negligible impact on the output of the simulation. In this work, we develop a novel method for describing the geometric uncertainty in image-derived models and use a naive method for subsequently quantifying a simulation's sensitivity to that uncertainty. A Gaussian random field is constructed to represent the space of possible geometries, based on image-derived quantities such as pixel size, which can then be used to probe the simulation's output space. The algorithm is demonstrated with examples from biomechanics where patient-specific geometries are often segmented from low-resolution, three-dimensional images. These examples show the method's wide applicability with examples using linear elasticity and fluid dynamics. We show that important biomechanical outputs of these example simulations, namely maximum principal stress and wall shear stress, can be highly sensitive to realistic uncertainties in geometry

A randomised controlled trial of three pragmatic approaches to initiate increased physical activity in sedentary patients with risk factors for cardiovascular disease

Background: physical activity is a major modifiable risk factor for cardiovascular disease, but it is unclear what combination of feasible approaches, using existing resources in primary care, work best to initiate increased physical activity.Aim: to assess three approaches to initiate increased physical activity.Design of study: randomised controlled (2 X 2 X 2) factorial trial.Setting: four general practices.Method: one hundred and fifty-one sedentary patients with computer documented risk factors for cardiovascular disease were randomised to eight groups defined by three factors: prescription by general practitioners (GPs) for brisk exercise not requiring a leisure facility (for example, walking) 30 minutes per day, 5 days per week; counselling by practice nurses, based on psychological theory to modify intentions and perceived control of behaviour, and using behavioural implementation techniques (for example, contracting, 'rehearsal'); use of the Health Education Authority booklet 'Getting active, feeling fit'.Results: single interventions had modest effects. There was a trend from the least intensive interventions (control +/- booklet) to the more intensive interventions (prescription and counselling combined +/- booklet) for both increased physical activity and fitness (test for trend, P = 0.02 and P = 0.05, respectively). Only with the most intense intervention (prescription and counselling combined) were there significant increases in both physical activity and fitness from baseline (Godin score = 14.4, 95% confidence interval [CI] = 7.8 to 21, which was equivalent to three 15-minute sessions of brisk exercise and a 6-minute walking distance = 28.5 m, respectively, 95% CI = 11.1 to 45.8). Counselling only made a difference among those individuals with lower intention at baseline.Conclusion: feasible interventions using available staff, which combine exercise prescription and counselling explicitly based on psychological theory, can probably initiate important increases in physical activity

Engagement of Families in the Care of Hospitalized Pediatric Patients: A Scoping Review

This scoping review was conducted to examine the range, nature, and extent of the published family engagement literature specific to the pediatric acute care setting to highlight future research and practice development opportunities. Included studies (N = 247) revealed global relevance. Engagement strategies ranged from more passive such as allowing/encouraging families to be present at the bedside to more active strategies aimed at promoting mutual and reciprocal nurse–patient interactions. Family engagement is distinguished by a mutually beneficial partnership of families with health care team members and care organizations. Future research in the area of family engagement in pediatric nursing should focus on determining the core engaging health professional behaviors and engaged parent outcomes; extending the knowledge base related to mutually beneficial partnerships between families and health care teams; developing effectiveness studies to determine the optimal engaging actions by teams to achieve parent engagement; and measuring the influence of engagement on parent and infant/child outcomes

Characteristics of exhaled particle production in healthy volunteers: possible implications for infectious disease transmission.

The size and concentration of exhaled particles may influence respiratory infection transmission risk. We assessed variation in exhaled particle production between individuals, factors associated with high production and stability over time. We measured exhaled particle production during tidal breathing in a sample of 79 healthy volunteers, using optical particle counter technology. Repeat measurements (several months after baseline) were obtained for 37 of the 79 participants.   Multilevel linear regression models of log transformed particle production measures were used to assess risk factors for high production.  Stability between measurements over time was assessed using Lin's correlation coefficients. Ninety-nine percent of expired particles were <1μm in diameter. Considerable variation in exhaled particle production was observed between individuals and within individuals over time. Distribution of particle production was right skewed.  Approximately 90% of individuals produce <150 particles per litre in normal breathing.  A few individuals had measurements of over 1000 particles per litre (maximum 1456). Particle production increased with age (p<0.001) and was associated with high tree pollen counts. Particle production levels did not remain stable over time [rho 0.14 (95%CI -0.10, 0.38, p=0.238)]. Sub-micron particles conducive to airborne rather than droplet transmission form the great majority of exhaled particles in tidal breathing. There is a high level of variability between subjects but measurements are not stable over time. Production increases with age and may be influenced by airway inflammation caused by environmental irritants. Further research is needed to determine whether the observed variations in exhaled particle production affect transmission of respiratory infection