Purpose:To demonstrate the feasibility of a four-dimensional phase contrast (PC) technique that permits spatial and temporal coverage of an entire three-dimensional volume, to quantitatively validate its accuracy against an established time resolved two-dimensional PC technique to explore advantages of the approach with regard to the fourdimensional nature of the data. Materials and Methods:Time-resolved, three-dimensional anatomical images were generated simultaneously with registered three-directional velocity vector fields. Improvements compared to prior methods include retrospectively gated and respiratory compensated image acquisition, interleaved flow encoding with freely selectable velocity encoding (venc) along each spatial direction, and flexible trade-off between temporal resolution and total acquisition time. Results:The implementation was validated against established two-dimensional PC techniques using a well-defined phantom, and successfully applied in volunteer and patient examinations. Human studies were performed after contrast administration in order to compensate for loss of inflow enhancement in the four-dimensional approach. Conclusion:Advantages of the four-dimensional approach include the complete spatial and temporal coverage of the cardiovascular region of interest and the ability to obtain high spatial resolution in all three dimensions with higher signal-to-noise ratio compared to two-dimensional methods at the same resolution. In addition, the four-dimensional nature of the data offers a variety of image processing options, such as magnitude and velocity multi-planar reformation, three-directional vector field plots, and velocity profiles mapped onto selected planes of interest.

Purpose -Many organisations are operating in a dynamic competitive environment and experiencing increasing competition. As a result organisations in the service sector are continually seeking opportunities to remove waste and improve performance. Six sigma has been embraced by the service sector and is receiving increasing attention within both academe and practice. The purpose of this paper is to evaluate lean six sigma from a middle managers' perspective. Design/methodology/approach -A mixed method approach was adopted involving a structured survey to 200 managers and semi-structured interviews with two of the management team. Findings -The paper highlights the importance of developing learning capabilities in the middle management team and the empowering of them. A greater role should be given to middle management in performance improvement and strategy formulation.Research limitations/implications -The research findings only apply to one case so it is difficult to make assumptions across different sectors. More research is required with regard to change management in lean six sigma implementations. Originality/value -This paper shows that developing dynamic capabilities in middle management along with a learning culture will facilitate participation in strategy formulation.

PurposeThis paper seeks to review the current literature in order to explore how performance of leadership in project management determines project outcomes. The specific causes of project success or failure have been an area of much debate in the project management literature. Performance of leadership has been cited as a critical success factor, determining either the success or failure of a project.Design/methodology/approachAn extensive literature review has been undertaken to explore our understanding of how project leadership performance impacts on project outcome.FindingsThe mechanisms through which leadership may impact on outcomes are considered. Implications include the need for project managers to prioritize training in leadership skills, and the need for continuous professional improvement to enhance leadership outcomes. No single leadership model is appropriate throughout the duration of the project. Performance, therefore, must be modified to align with the stages of the project duration.Research limitations/implicationsWhile the literature has given meaningful insights into leadership of projects, there has been little research into performance management of project leadership. The work is the basis of developing a research agenda and establishing a conceptual framework. The opportunity exists, based on this work, for carrying out research on project leadership performance and its effect on project outcomes.Practical implicationsInsightful learning has been achieved into project leadership and the failing of practitioners in appropriate training and development at various stages of the projects life cycle.Social implicationsProjects and project‐based management, delivered nationally and internationally, are of significant importance to organizations. Increasing understanding of the implications of leadership performance, therefore, is of critical importance.Originality/valueThe literature review has identified significant limitation in project leadership performance management. It is anticipated that this work will trigger further research.

Patient-specific computational models could aid in planning interventions to relieve pulmonary arterial stenoses common in many forms of congenital heart disease. We describe a new approach to simulate blood flow in subject-specific models of the pulmonary arteries that consists of a numerical model of the proximal pulmonary arteries created from three-dimensional medical imaging data with terminal impedance boundary conditions derived from linear wave propagation theory applied to morphometric models of distal vessels. A tuning method, employing numerical solution methods for nonlinear systems of equations, was developed to modify the distal vasculature to match measured pressure and flow distribution data. One-dimensional blood flow equations were solved with a finite element method in image-based pulmonary arterial models using prescribed inlet flow and morphometry-based impedance at the outlets. Application of these methods in a pilot study of the effect of removal of unilateral pulmonary arterial stenosis induced in a pig showed good agreement with experimental measurements for flow redistribution and main pulmonary arterial pressure. Next, these methods were applied to a patient with repaired tetralogy of Fallot and predicted insignificant hemodynamic improvement with relief of the stenosis. This method of coupling image-based and morphometry-based models could enable increased fidelity in pulmonary hemodynamic simulation.

Magnetic resonance (MR) imaging techniques and a custom MR-compatible exercise bicycle were used to measure, in vivo, the effects of exercise on hemodynamic conditions in the abdominal aorta of eleven young, healthy subjects. Heart rate increased from 73 +/- 6.2 beats/min at rest to 110 +/- 8.8 beats/min during exercise (p<0.0001). The total blood flow through the abdominal aorta increased from 2.9 +/- 0.6 L/min at rest to 7.2 +/- 1.4 L/min during exercise (p <0.0005) while blood flow to the digestive and renal circulations decreased from 2.1 +/- 0.5 L/min at rest to 1.6 +/- 0.7 L/min during exercise (p<0.01). Infrarenal blood flow increased from 0.9 +/- 0.4 L/min at rest to 5.6 +/- 1.1 L/min during exercise (p<0.0005). Wall shear stress increased in the supraceliac aorta from 3.5 +/- 0.8 dyn/cm2 at rest to 6.2 +/- 0.5 dyn/cm2 during exercise (p<0.0005) and increased in the infrarenal aorta from 1.3 +/- 0.8 dyn/cm2 at rest to 5.2 +/- 1.3 dyn/cm2 during exercise (p<0.0005).

Arterial wall shear stress is hypothesized to be an important factor in the localization of atherosclerosis. Current methods to compute wall shear stress from magnetic resonance imaging (MRI) data do not account for flow profiles characteristic of pulsatile flow in noncircular vessel lumens. We describe a method to quantify wall shear stress in large blood vessels by differentiating velocity interpolation functions defined using cine phase-contrast MRI data on a band of elements in the neighborhood of the vessel wall. Validation was performed with software phantoms and an in vitro flow phantom. At an image resolution corresponding to in vivo imaging data of the human abdominal aorta, time-averaged, spatially averaged wall shear stress for steady and pulsatile flow were determined to be within 16% and 23% of the analytic solution, respectively. These errors were reduced to 5% and 8% with doubling in image resolution. For the pulsatile software phantom, the oscillation in shear stress was predicted to within 5%. The mean absolute error of circumferentially resolved shear stress for the nonaxisymmetric phantom decreased from 28% to 15% with a doubling in image resolution. The irregularly shaped phantom and in vitro investigation demonstrated convergence of the calculated values with increased image resolution. We quantified the shear stress at the supraceliac and infrarenal regions of a human abdominal aorta to be 3.4 and 2.3 dyn/cm2, respectively.

Cytoskeletal motors drive the transport of organelles and molecular cargoes within cells1, and have potential applications in molecular detection and diagnostic devices2,3. Engineering molecular motors with dynamically controllable properties will allow selective perturbation of mechanical processes in living cells, and yield optimized device components for complex tasks such as molecular sorting and directed assembly3. Biological motors have previously been modified by introducing activation/deactivation switches that respond to metal ions4,5 and other signals6. Here we show that myosin motors can be engineered to reversibly change their direction of motion in response to a calcium signal. Building on previous protein engineering studies7–11 and guided by a structural model12 for the redirected power stroke of myosin VI, we constructed bidirectional myosins through the rigid recombination of structural modules. The performance of the motors was confirmed using gliding filament assays and single fluorophore tracking. Our general strategy, in which external signals trigger changes in the geometry and mechanics of myosin lever arms, should enable spatiotemporal control over a range of motor properties including processivity, stride size13, and branchpoint turning14.

Purpose-Many organisations remain adverse to self-organised teams. The reasons are non-trivial and complex, but it is suspected that not willing to let go to direct control by senior management is at the root cause. There is a perceived security in following traditional, hierarchical chains of command under the guise of reducing risks and maintaining efficiency. The purpose of this paper is to describe the development of a research agenda that will empirically test in the field a range of widely held assumptions around leadership of self-organised teams. In total, 23 companies have agreed to participate in the proposed longitudinal research. Design/methodology/approach-An extensive literature review has identified extant theories, frameworks, and methodologies adopted by researchers to gain greater understanding of self-organised teams. This knowledge will be used as the basis for generating hypotheses for subsequent testing in the field. Findings-There is a considerable knowledge base established for self-organised teams. However, there is limited understanding of the benefits or detrimental effects of self-organised teams on organisational productivity and the appropriate style of leadership. This initial research has identified several hypotheses that will be used to develop questionnaires and instruments for information collection. Research limitations/implications-The tools and techniques presented in this article need to be adapted to the organisation's specificities as well as to the contextual situation. Practical implications-The work is of significant practical use. The research will be completed in a number of companies. There will be continuous input from operational and executive management. The findings from the work will be disseminated through various channels including workshops and conferences. Companies implementing and using self-organised teams will benefit from the knowledge generated. Social implications-Self-organised teams are used in a variety of settingscommercial businesses, not-for-profit, NGOs. The work will explore issues around behavioural networks and inter-intra-team relationships. Originality/value-There is much rhetoric around the adoption and uses of self-organised teams, yet there appears to be little understanding of the effect of leadership style of these teams and effect on productivity. This work will therefore contribute to the understanding of self-organised teams. While prior research has been conducted in the motivational and behavioural implications of self-organised teams, the knowledge is at best scant when leadership models for self-organised teams and operational factors are explored.