The effect of spacing on the vortex-induced vibrations of two tandem flexible cylinders

Vortex-induced vibrations (VIV) of two flexible cylinders arranged in tandem are studied using a two-way fluidstructure interaction (FSI) method with different spacing ratios (Sx/D) at Reynolds number Re = 500 using a twoway fluid-structure interaction (FSI) method. The main objective of this study is to investigate the effect of spacing on the hydrodynamic interactions and the VIV responses of these cylinders. The responses of the two flexible cylinders are found to be similar to the classical VIV responses at small Sx/D. Once Sx/D is large enough for the vortices to become detached from the upstream cylinder, the response of the upstream cylinder is similar to the typical VIV response whereas the downstream cylinder undergoes wake-induced vibration (WIV). The characteristics of the response of the downstream cylinder in the present study are similar to those of the first two response regimes classified by previous researchers. The third regime is not observed for the flexible downstream cylinder with both ends fixed. The two changes in the phase relation between the cross-flow displacements of the two tandem flexible cylinders are discovered to be linked with the initial-upper branch transition and the upperlower branch transition, respectively. The correlation lengths of the two flexible cylinders decrease significantly in the transition range between the upper and lower branches. Three modes of vortex shedding (2S, P + S and 2P) have been identified in the present study. The upper-branch 2P mode is found to be associated with largeamplitude vibration of the upstream cylinder and the P + S mode is observed to be related to large-amplitude vibration of the downstream cylinder for Sx/D = 3.5 and 5. On the other hand, the lower-branch 2P mode leads to small-amplitude vibration of the downstream cylinder in the post-lock-in range at Sx/D = 2.5. The relative phase shifts of the sectional lift coefficients on different spanwise cross sections can be attributed to the variation of the vortex shedding flow along the flexible cylinders, and these phase shifts result in poor phasing between the forces and the displacements which is related to the decrease of the correlation lengths

Job design, employment practices and well-being: a systematic review of intervention studies

There is inconsistent evidence that deliberate attempts to improve job design realise improvements in well-being. We investigated the role of other employment practices, either as instruments for job redesign or as instruments that augment job redesign. Our primary outcome was well-being. Where studies also assessed performance, we considered performance as an outcome. We reviewed 33 intervention studies. We found that well-being and performance may be improved by: training workers to improve their own jobs; training coupled with job redesign; and system wide approaches that simultaneously enhance job design and a range of other employment practices. We found insufficient evidence to make any firm conclusions concerning the effects of training managers in job redesign and that participatory approaches to improving job design have mixed effects. Successful implementation of interventions was associated with worker involvement and engagement with interventions, managerial commitment to interventions and integration of interventions with other organisational systems. Practitioner Summary: Improvements in well-being and performance may be associated with system-wide approaches that simultaneously enhance job design, introduce a range of other employment practices and focus on worker welfare. Training may have a role in initiating job redesign or augmenting the effects of job design on well-being

Well-being through learning: a systematic review of learning interventions in the workplace and their impact on well-being

The view that learning is central to well-being is widely held and the workplace is an important setting in which learning takes place. Evaluations of the effectiveness of well-being interventions in work settings are commonplace, but to date, there has been no systematic review of the effectiveness of learning interventions with regard to their impact on well-being. The review synthesizes evidence from 41 intervention studies, and although no studies report a negative impact on well-being, 14 show no effect on well-being, with 27 studies having a positive impact. We classify the studies according to the primary purpose of the learning intervention: to develop personal resources for well-being through learning; to develop professional capabilities through learning; to develop leadership skills through learning; and to improve organizational effectiveness through organizational-level learning. Although there is an abundance of workplace learning interventions, few are evaluated from a well-being perspective despite the commonly held assumption that learning yields positive emotional and psychological outcomes. The evidence indicates an important gap in our evaluation of and design of workplace learning interventions and their impact on well-being, beyond those focusing on personal resources. This raises important theoretical and practical challenges concerning the relationship between learning and well-being in the context of professional capability enhancement, leadership capability and organizational learning

Automated Analysis in Feature Modelling and Product Configuration

The automated analysis of feature models is one of the thriving topics of research in the software product line and variability management communities that has attracted more attention in the last years. A recent literature review reported that more than 30 analysis operations have been identi ed and di erent analysis mechanisms have been proposed. Product con guration is a well established research eld with more than 30 years of successful applications in di erent industrial domains. Our hypothesis, that is not really new, is that these two independent areas of research have interesting synergies that have not been fully explored. To try to explore the potential synergies systematically, in this paper we provide a rapid review to bring together these previously disparate streams of work. We de ne a set of research questions and give a preliminary answer to some of them. We conclude that there are many research opportunities in the synergy of these independent areas.Ministerio de Ciencia e Innovación TIN2009- 07366Junta de Andalucía TIC-590

Maternal Arterial Stiffness in Women Who Subsequently Develop Pre-Eclampsia

BACKGROUND/OBJECTIVES: Pre-eclampsia (PE) is associated with profound changes in the maternal cardiovascular system. The aim of the present study was to assess whether alterations in the maternal arterial stiffness precede the onset of PE in at risk women. METHODOLOGY/PRINCIPAL FINDINGS: This was a cross sectional study involving 70 pregnant women with normal and 70 women with abnormal uterine artery Doppler examination at 22-24 weeks of gestation. All women had their arterial stiffness (augmentation index and pulse wave velocity of the carotid-femoral and carotid-radial parts of the arterial tree) assessed by applanation tonometry in the second trimester of pregnancy, at the time of the uterine artery Doppler imaging. Among the 140 women participating in the study 29 developed PE (PE group) and 111 did not (non-PE group). Compared to the non-PE group, women that developed PE had higher central systolic (94.9 ± 8.6 mmHg vs 104.3 ± 11.1 mmHg; p  =  < 0.01) and diastolic (64.0 ± 6.0 vs 72.4 ± 9.1; p < 0.01) blood pressures. All the arterial stiffness indices were adjusted for possible confounders and expressed as multiples of the median (MoM) of the non-PE group. The adjusted median augmentation index was similar between the two groups (p  =  0.84). The adjusted median pulse wave velocities were higher in the PE group compared to the non-PE group (carotid-femoral: 1.10 ± 0.14 MoMs vs 0.99 ± 0.11 MoMs; p < 0.01 and carotid-radial: 1.08 ± 0.12 MoMs vs 1.0 ± 0.11 MoMs; p < 0.01). CONCLUSIONS/SIGNIFICANCE: Increased maternal arterial stiffness, as assessed by pulse wave velocity, predates the development of PE in at risk women

Explainable Recommendations in Intelligent Systems: Delivery Methods, Modalities and Risks

With the increase in data volume, velocity and types, intelligent human-agent systems have become popular and adopted in different application domains, including critical and sensitive areas such as health and security. Humans’ trust, their consent and receptiveness to recommendations are the main requirement for the success of such services. Recently, the demand on explaining the recommendations to humans has increased both from humans interacting with these systems so that they make an informed decision and, also, owners and systems managers to increase transparency and consequently trust and users’ retention. Existing systematic reviews in the area of explainable recommendations focused on the goal of providing explanations, their presentation and informational content. In this paper, we review the literature with a focus on two user experience facets of explanations; delivery methods and modalities. We then focus on the risks of explanation both on user experience and their decision making. Our review revealed that explanations delivery to end-users is mostly designed to be along with the recommendation in a push and pull styles while archiving explanations for later accountability and traceability is still limited. We also found that the emphasis was mainly on the benefits of recommendations while risks and potential concerns, such as over-reliance on machines, is still a new area to explore

Aortic stiffness in lone atrial fibrillation: A novel risk factor for arrhythmia recurrence

BACKGROUND Recent community-based research has linked aortic stiffness to the development of atrial fibrillation. We posit that aortic stiffness contributes to adverse atrial remodeling leading to the persistence of atrial fibrillation following catheter ablation in lone atrial fibrillation patients, despite the absence of apparent structural heart disease. Here, we aim to evaluate aortic stiffness in lone atrial fibrillation patients and determine its association with arrhythmia re currence following radio-frequency catheter ablation. METHODS We studied 68 consecutive lone atrial fibrillation patients who underwent catheter ablation procedure for atrial fibrillation and 50 healthy age- and sex-matched community controls. We performed radial artery applanation tonometry to obtain central measures of aortic stiffness: pulse pressure, augmentation pressure and augmentation index. Following ablation, arrhythmia recurrence was monitored at months 3, 6, 9, 12 and 6 monthly thereafter. RESULTS Compared to healthy controls, lone atrial fibrillation patients had significantly elevated peripheral pulse pressure, central pulse pressure, augmentation pressure and larger left atrial dimensions (all P<0.05). During a mean follow-up of 2.9±1.4 years, 38 of the 68 lone atrial fibrillation patients had atrial fibrillation recurrence after initial catheter ablation procedure. Neither blood pressure nor aortic stiffness indices differed between patients with and without atrial fibrillation recurrence. However, patients with highest levels (≥75th percentile) of peripheral pulse pressure, central pulse pressure and augmentation pressure had higher atrial fibrillation recurrence rates (all P<0.05). Only central aortic stiffness indices were associated with lower survival free from atrial fibrillation using Kaplan-Meier analysis. CONCLUSION Aortic stiffness is an important risk factor in patients with lone atrial fibrillation and contributes to higher atrial fibrillation recurrence following catheter ablation procedure.Dennis H. Lau, Melissa E. Middeldorp, Anthony G. Brooks, Anand N. Ganesan, Kurt C. Roberts-Thomson, Martin K. Stiles, Darryl P. Leong, Hany S. Abed, Han S. Lim, Christopher X. Wong, Scott R. Willoughby, Glenn D. Young, Jonathan M. Kalman, Walter P. Abhayaratna, Prashanthan Sander