Physical activity has cultural significance and population health benefits. However, Aboriginal and Torres Strait Islander adults may experience challenges in participating in physical activity. This mixed methods systematic review aimed to synthetize existing evidence on facilitators and barriers for physical activity participation experienced by Aboriginal and Torres Strait Islander adults in Australia. The Joanna Briggs Institute methodology was used. A systematic search was undertaken of 11 databases and 14 grey literature websites during 2020. The included studies reported physical activity facilitators and barriers experienced by Aboriginal or Torres Strait Islander participants aged 18+ years, living in the community. Twenty-seven studies met the inclusion criteria. Sixty-two facilitators were identified: 23 individual, 18 interpersonal, 8 community/environmental and 13 policy/program facilitators. Additionally, 63 barriers were identified: 21 individual, 17 interpersonal, 15 community/environmental and 10 policy/program barriers. Prominent facilitators included support from family, friends, and program staff, and opportunities to connect with community or culture. Prominent barriers included a lack of transport, financial constraints, lack of time, and competing work, family or cultural commitments. Aboriginal and Torres Strait Islander adults experience multiple facilitators and barriers to physical activity participation. Strategies to increase participation should seek to enhance facilitators and address barriers, collaboratively with communities, with consideration to the local context.
A lumped parameter model of human cardiovascular-implantable rotary blood pump (iRBP) interaction has been developed based on experimental data recorded in two healthy pigs with the iRBP in situ. The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, as well as the iRBP. A subset of parameters was optimized in a least squares sense to faithfully reproduce the experimental measurements (pressures, flows and pump variables). Our fitted model compares favorably with our experimental measurements at a range of pump operating points. Furthermore, we have also suggested the importance of various model features, such as the curvilinearity of the end systolic pressure-volume relationship, the Starling resistance, the suction resistance, the effect of respiration, as well as the influence of the pump inflow and outflow cannulae. Alterations of model parameters were done to investigate the circulatory response to rotary blood pump assistance under heart failure conditions. The present model provides a valuable tool for experiment designs, as well as a platform to aid in the development and evaluation of robust physiological pump control algorithms.
To date there have only been limited studies exploring abnormal hemodynamic responses to head-up tilt tests (HUTs) in elderly, treated patients with hypertension. Cardiovascular regulation in response to HUT as well as upright hemodynamics may be altered when older hypertensive patients with antihypertensive treatments are studied. Hypertensive patients with and without receiving antihypertensive medication and above the age of 45 were recruited in this study. This study compared the cardiovascular responses to HUT and at rest between healthy and hypertensives using non-invasive hemodynamic measurements. Parameters such as systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke index (SI) and total peripheral resistance index (TPRI) were measured in 40 subjects (20 healthy and 20 hypertensives) for 10-min supine baseline, 10-min HUT at 70 ◦ and 6-min supine recovery. At rest and during HUT, SBP and TPRI were significantly higher in hypertensives together with a significantly smaller baseline SI. In response to HUT, both groups showed changes in hemodynamic parameters at differing degrees. During recovery, all parameters returned to the baseline range. Our findings indicated that hypertensive patients of older age being treated by antihypertensive drugs may have different cardiovascular changes in response to orthostatic stress.Clinical Relevance— This pilot study describes how cardiovascular regulation in response to postural change may behave differently in hypertensive elder patients taking antihypertensive drugs.
Abstract Objective. The spatial resolution of an implantable neural stimulator can be improved by creation of virtual channels (VCs). VCs are commonly achieved through synchronized stimulation of multiple electrodes. It remains unknown whether asynchronous stimulation is able to generate comparable VC performance in retinal stimulation, and how VC can be optimized by re-designing stimulation settings. This study begins with exploring the feasibility of creating VCs using synchronous and asynchronous epiretinal stimulation, and ending with predicting the possible VC performance with a thorough exploration of stimulation parameter space. Approach. A computational model of epiretinal dual-electrode stimulation is developed to simulate the neural activity of a population of retinal ganglion cells (RGCs) under both synchronous and asynchronous stimulation conditions. The interaction between the electrode and RGCs under a range of stimulation parameters are simulated. Main results. Our simulation based on direct RGC activation suggests that VCs can be created using asynchronous stimulation. Two VC performance measures: 1) linearity in the change in centroid location of activated RGC populations, and 2) consistency in the size of activated RGC populations, have comparable performance under asynchronous and synchronous stimulation with appropriately selected stimulation parameters. Significance. Our findings support the possibility of creating VCs by directly activating RGCs under synchronous and asynchronous stimulation conditions. This study establishes the fundamental capability of VC creation based on temporal interactions within the RGC population alone and does not include the effects of potential indirect activation of any surviving inner retinal network neurons. Our results provide theoretical evidence for designing next-generation retinal prosthesis with higher spatial resolution.
Neurodevelopmental and neurodegenerative disorders (NNDs) are a group of conditions with a broad range of core and co-morbidities, associated with dysfunction of the central nervous system. Improvements in high throughput sequencing have led to the detection of putative risk genetic loci for NNDs, however, quantitative neurogenetic approaches need to be further developed in order to establish causality and underlying molecular genetic mechanisms of pathogenesis. Here, we discuss an approach for prioritizing the contribution of genetic risk loci to complex-NND pathogenesis by estimating the possible impacts of these loci on gene regulation. Furthermore, we highlight the use of a tissue-specificity gene expression index and the application of artificial intelligence (AI) to improve the interpretation of the role of genetic risk elements in NND pathogenesis. Given that NND symptoms are associated with brain dysfunction, risk loci with direct, causative actions would comprise genes with essential functions in neural cells that are highly expressed in the brain. Indeed, NND risk genes implicated in brain dysfunction are disproportionately enriched in the brain compared with other tissues, which we refer to as brain-specific expressed genes. In addition, the tissue-specificity gene expression index can be used as a handle to identify non-brain contexts that are involved in NND pathogenesis. Lastly, we discuss how using an AI approach provides the opportunity to integrate the biological impacts of risk loci to identify those putative combinations of causative relationships through which genetic factors contribute to NND pathogenesis.
The concept of early goal-directed therapy emphasizes the need for early diagnosis and intervention to achieve better therapeutic outcomes in critical care. There has been rapidly growing interest in the use of the photoplethysmogram (PPG), also known as the "pulse oximetry waveform", as a noninvasive diagnostic tool in this clinical setting. The peripheral PPG exhibits beat-to-beat variability driven by physiological mechanisms such as respiration and sympathetic vascular activity. This paper provides an overview of the current progress towards the application of PPG waveform variability (PPGV) in emergency and intensive care. Studies to date have demonstrated the potential value of PPGV for assessing a range of pathophysiological conditions including blood loss, sepsis and low systemic vascular resistance. Translation of research findings into clinical practice poses several future challenges, including the need for large scale validation studies with appropriate measurement systems, more robust solutions to signal quality issues (such as motion artifacts), and better physiological understanding of the information-rich PPGV.
An isolated rabbit cardiac sinoatrial node (SAN) tissue preparation was used experimentally to map activation times and conduction velocities of extracellular cardiac action potential (AP) propagation. Extracellular recordings were carried out using a two-dimensional array of unipolar Ag-AgCl microelectrodes connected to a 128-channel data acquisition system. A 20(th) order, low-pass Butterworth filter, with a cut-off frequency of 50 Hz, was used in conjunction with a Matlab algorithm to map activation times and conduction velocities. Results show an initial slow-down of the activation wavefront emanating from the SAN, followed by acceleration in some regions, particularly near the Superior Vena Cava, as it travels towards the SAN periphery.
Abstract Wide bandgap (WBG) semiconductors have attracted significant research interest for the development of a broad range of flexible electronic applications, including wearable sensors, soft logical circuits, and long‐term implanted neuromodulators. Conventionally, these materials are grown on standard silicon substrates, and then transferred onto soft polymers using mechanical stamping processes. This technique can retain the excellent electrical properties of wide bandgap materials after transfer and enables flexibility; however, most devices are constrained by 2D configurations that exhibit limited mechanical stretchability and morphologies compared with 3D biological systems. Herein, a stamping‐free micromachining process is presented to realize, for the first time, 3D flexible and stretchable wide bandgap electronics. The approach applies photolithography on both sides of free‐standing nanomembranes, which enables the formation of flexible architectures directly on standard silicon wafers to tailor the optical transparency and mechanical properties of the material. Subsequent detachment of the flexible devices from the support substrate and controlled mechanical buckling transforms the 2D precursors of wide band gap semiconductors into complex 3D mesoscale structures. The ability to fabricate wide band gap materials with 3D architectures that offer device‐level stretchability combined with their multi‐modal sensing capability will greatly facilitate the establishment of advanced 3D bio‐electronics interfaces.
Abstract Taking a leaf out of evolutionary biology, soft robots have begun to utilize compliant materials and structures for improved interactions with humans and complex environments. However, these advances have not been followed closely by sensing mechanisms. Biology has had a head start on the development of advanced sensing systems. The human body and its skeletal muscles can tune their morphologies to interact with the surrounding environment. Inspired by such biological systems, this paper introduces a novel hydraulic soft filament sensor (SFS) with tunable sensitivity. The SFS is a type of hydraulic pressure‐based tubular strain sensor, which has a sensing core made of a soft and stretchable micro‐sized filament filled with incompressible fluid where its inner hydraulic pressure is changed with strain. The SFS can be customized to form a wide range of configurations such as a long fiber or a skin‐like structure. To demonstrate the SFS capability, different configurations for the SFS are fabricated and experimentally validated. The scalable and tunable nature of the SFS makes it suitable for a wide range of wearable and medical applications.
Computational models have become essential in predicting medical device efficacy prior to clinical studies. To investigate the performance of a left-ventricular assist device (LVAD), a fully-coupled cardiac fluid-electromechanics finite element model was developed, incorporating electrical activation, passive and active myocardial mechanics, as well as blood hemodynamics solved simultaneously in an idealized biventricular geometry. Electrical activation was initiated using a simplified Purkinje network with one-way coupling to the surrounding myocardium. Phenomenological action potential and excitation-contraction equations were adapted to trigger myocardial contraction. Action potential propagation was formulated within a material frame to emulate gap junction-controlled propagation, such that the activation sequence was independent of myocardial deformation. Passive cardiac mechanics were governed by a transverse isotropic hyperelastic constitutive formulation. Blood velocity and pressure were determined by the incompressible Navier-Stokes formulations with a closed-loop Windkessel circuit governing the circulatory load. To investigate heart-LVAD interaction, we reduced the left ventricular (LV) contraction stress to mimic a failing heart, and inserted a LVAD cannula at the LV apex with continuous flow governing the outflow rate. A proportional controller was implemented to determine the pump motor voltage whilst maintaining pump motor speed. Following LVAD insertion, the model revealed a change in the LV pressure-volume loop shape from rectangular to triangular. At higher pump speeds, aortic ejection ceased and the LV decompressed to smaller end diastolic volumes. After multiple cycles, the LV cavity gradually collapsed along with a drop in pump motor current. The model was therefore able to predict ventricular collapse, indicating its utility for future development of control algorithms and pre-clinical testing of LVADs to avoid LV collapse in recipients.
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)