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Paediatric patients with heart failure requiring ventricular assist devices are at heightened risk of neurologic injury and psychosocial adjustment challenges, resulting in a need for neurodevelopmental and psychosocial support following device placement. Through a descriptive survey developed in collaboration by the Advanced Cardiac Therapies Improving Outcomes Network and the Cardiac Neurodevelopmental Outcome Collaborative, the present study aimed to characterise current neurodevelopmental and psychosocial care practices for paediatric patients with ventricular assist devices.
Method:
Members of both learning networks developed a 25-item electronic survey assessing neurodevelopmental and psychosocial care practices specific to paediatric ventricular assist device patients. The survey was sent to Advanced Cardiac Therapies Improving Outcomes Network site primary investigators and co-primary investigators via email.
Results:
Of the 63 eligible sites contacted, responses were received from 24 unique North and South American cardiology centres. Access to neurodevelopmental providers, referral practices, and family neurodevelopmental education varied across sites. Inpatient neurodevelopmental care consults were available at many centres, as were inpatient family support services. Over half of heart centres had outpatient neurodevelopmental testing and individual psychotherapy services available to patients with ventricular assist devices, though few centres had outpatient group psychotherapy (12.5%) or parent support groups (16.7%) available. Barriers to inpatient and outpatient neurodevelopmental care included limited access to neurodevelopmental providers and parent/provider focus on the child’s medical status.
Conclusions:
Paediatric patients with ventricular assist devices often have access to neurodevelopmental providers in the inpatient setting, though supports vary by centre. Strengthening family neurodevelopmental education, referral processes, and family-centred psychosocial services may improve current neurodevelopmental/psychosocial care for paediatric ventricular assist device patients.
Studies of Kelvin–Helmholtz (KH) instability have typically modelled the initial mean flow as an isolated stratified shear layer. However, geophysical flows frequently exhibit multiple layers. As a step towards understanding these flows, we examine the case of two adjacent stratified shear layers using both linear stability analysis and direct numerical simulations. With sufficiently large layer separation, the characteristics of instability and mixing converge towards the familiar KH turbulence, and similarly when the separation is near zero and the layers add to make a single layer, albeit with a reduced Richardson number. Here, our focus is on intermediate separations, which produce new and complex phenomena. As the separation distance $D$ increases from zero to a critical value $D_c$, approximately half the thickness of the shear layer, the growth rate and wavenumber both decrease monotonically. The minimum Richardson number is relatively low, potentially inducing pairing, and shear-aligned convective instability (SCI) is the primary mechanism for transition. Consequently, mixing is relatively strong and efficient. When $D\sim D_c$, billow length is increased but growth is slowed. Despite the modest growth rate, mixing is strong and efficient, engendered primarily by secondary shear instability manifested on the braids, and by SCI occurring on the eyelids. Shear-aligned vortices are driven in part by buoyancy production; however, shear production and vortex stretching are equally important mechanisms. When $D>D_c$, neighbouring billow interactions suppress the growth of both KH instability and SCI. Strength and efficiency of mixing decrease abruptly as $D_c$ is exceeded. As turbulence decays, layers of marginal instability may arise.
Studies of Kelvin–Helmholtz (KH) instability have typically modelled the initial flow as an isolated shear layer. In geophysical cases, however, the instability often occurs near boundaries and may therefore be influenced by boundary proximity effects. Ensembles of direct numerical simulations are conducted to understand the effect of boundary proximity on the evolution of the instability and the resulting turbulence. Ensemble averages are used to reduce sensitivity to small variations in initial conditions. Both the transition to turbulence and the resulting turbulent mixing are modified when the shear layer is near a boundary: the time scales for the onset of instability and turbulence are longer, and the height of the KH billow is reduced. Subharmonic instability is suppressed by the boundary because phase lock is prevented due to the diverging phase speeds of the KH and subharmonic modes. In addition, the disruptive influence of three-dimensional secondary instabilities on pairing is more profound as the two events coincide more closely. When the shear layer is far from the boundary, the shear-aligned convective instability is dominant; however, secondary central-core instability takes over when the shear layer is close to the boundary, providing an alternate route for the transition to turbulence. Both the efficiency of the resulting mixing and the turbulent diffusivity are dramatically reduced by boundary proximity effects.
Patient- and proxy-reported outcomes (PROs) are an important indicator of healthcare quality and can be used to inform treatment. Despite the widescale use of PROs in adult cardiology, they are underutilised in paediatric cardiac care. This study describes a six-center feasibility and pilot experience implementing PROs in the paediatric and young adult ventricular assist device population.
Methods:
The Advanced Cardiac Therapies Improving Outcomes Network (ACTION) is a collaborative learning network comprised of 55 centres focused on improving clinical outcomes and the patient/family experience for children with heart failure and those supported by ventricular assist devices. The development of ACTION’s PRO programme via engagement with patient and parent stakeholders is described. Pilot feasibility, patient/parent and clinician feedback, and initial PRO findings of patients and families receiving paediatric ventricular assist support across six centres are detailed.
Results:
Thirty of the thirty-five eligible patients (85.7%) were enrolled in the PRO programme during the pilot study period. Clinicians and participating patients/parents reported positive experiences with the PRO pilot programme. The most common symptoms reported by patients/parents in the first month post-implant period included limitations in activities, dressing change distress, and post-operative pain. Poor sleep, dressing change distress, sadness, and fatigue were the most common symptoms endorsed >30 days post-implant. Parental sadness and worry were notable throughout the entirety of the post-implant experience.
Conclusions:
This multi-center ACTION learning network-based PRO programme demonstrated initial success in this six-center pilot study experience and yields important next steps for larger-scale PRO collection, research, and clinical intervention.
In a stably stratified shear layer, multiple competing instabilities produce sensitivity to small changes in initial conditions, popularly called the butterfly effect (as a flapping wing may alter the weather). Three ensembles of 15 simulated mixing events, identical but for small perturbations to the initial state, are used to explore differences in the route to turbulence, the maximum turbulence level and the total amount and efficiency of mixing accomplished by each event. Comparisons show that a small change in the initial state alters the strength and timing of the primary Kelvin–Helmholtz instability, the subharmonic pairing instability and the various three-dimensional secondary instabilities that lead to turbulence. The effect is greatest in, but not limited to, the parameter regime where pairing and the three-dimensional secondary instabilities are in strong competition. Pairing may be accelerated or prevented; maximum turbulence kinetic energy may vary by up to a factor of 4.6, flux Richardson number by 12 %–15 % and net mixing by a factor of 2.
Identifying the most effective ways to support career development of early stage investigators in clinical and translational science should yield benefits for the biomedical research community. Institutions with Clinical and Translational Science Awards (CTSA) offer KL2 programs to facilitate career development; however, the sustained impact has not been widely assessed.
Methods:
A survey comprised of quantitative and qualitative questions was sent to 2144 individuals that had previously received support through CTSA KL2 mechanisms. The 547 responses were analyzed with identifying information redacted.
Results:
Respondents held MD (47%), PhD (36%), and MD/PhD (13%) degrees. After KL2 support was completed, physicians’ time was divided 50% to research and 30% to patient care, whereas PhD respondents devoted 70% time to research. Funded research effort averaged 60% for the cohort. Respondents were satisfied with their career progression. More than 95% thought their current job was meaningful. Two-thirds felt confident or very confident in their ability to sustain a career in clinical and translational research. Factors cited as contributing to career success included protected time, mentoring, and collaborations.
Conclusion:
This first large systematic survey of KL2 alumni provides valuable insight into the group’s perceptions of the program and outcome information. Former scholars are largely satisfied with their career choice and direction, national recognition of their expertise, and impact of their work. Importantly, they identified training activities that contributed to success. Our results and future analysis of the survey data should inform the framework for developing platforms to launch sustaining careers of translational scientists.
The analysis of processing standards alongside samples for quality assurance in radiocarbon (14C) analyses is critical. Ideally, these standards should be similar both in nature and age to unknown samples. A new compound-specific approach was developed at the University of Bristol for dating pottery vessels using palmitic and stearic fatty acids extracted from within the clay matrix and isolated by preparative capillary gas chromatography. Obtaining suitable potsherds for use as processing standards in such analyses is not feasible, so we suggest that bog butter represents an ideal material for such purposes. We sampled ca. 450 g from two bog butter specimens and homogenized them by melting. We verified the homogeneity of both specimens by characterization of their lipid composition, δ13C values of individual lipids, and both bulk- and compound-specific radiocarbon analyses on 10 sub-samples of each bog butter specimen. The weighted means of all 14C measurements on the bog butter standards are 3777 ± 4 BP (IB33) and 338 ± 3 BP (IB38), thereby providing age-relevant standards for archaeological and historical fatty acids and ensuring the accuracy of radiocarbon determinations of lipids using a compound-specific approach. These new secondary standards will be subjected to an intercomparison exercise to provide robust consensus values.
Instabilities are present in all natural fluids from rivers to atmospheres. This book considers the physical processes that generate instability. Part I describes the normal mode instabilities most important in geophysical applications, including convection, shear instability and baroclinic instability. Classical analytical approaches are covered, while also emphasising numerical methods, mechanisms such as internal wave resonance, and simple `rules of thumb' that permit assessment of instability quickly and intuitively. Part II introduces the cutting edge: nonmodal instabilities, the relationship between instability and turbulence, self-organised criticality, and advanced numerical techniques. Featuring numerous exercises and projects, the book is ideal for advanced students and researchers wishing to understand flow instability and apply it to their own research. It can be used to teach courses in oceanography, atmospheric science, coastal engineering, applied mathematics and environmental science. Exercise solutions and MATLAB® examples are provided online. Also available as Open Access on Cambridge Core.