Turing Instabilities are Not Enough to Ensure Pattern Formation.

Symmetry-breaking instabilities play an important role in understanding the mechanisms underlying the diversity of patterns observed in nature, such as in Turing's reaction-diffusion theory, which connects cellular signalling and transport with the development of growth and form. Extensive literature focuses on the linear stability analysis of homogeneous equilibria in these systems, culminating in a set of conditions for transport-driven instabilities that are commonly presumed to initiate self-organisation. We demonstrate that a selection of simple, canonical transport models with only mild multistable non-linearities can satisfy the Turing instability conditions while also robustly exhibiting only transient patterns.

Optimal face-to-face coupling for fast self-folding kirigami.

Kirigami-inspired designs can enable self-folding three-dimensional materials from flat, two-dimensional sheets. Hierarchical designs of connected levels increase the diversity of possible target structures, yet they can lead to longer folding times in the presence of fluctuations. Here, we study the effect of rotational coupling between levels on the self-folding of two-level kirigami designs driven by thermal noise in a fluid.

VisualPDE: Rapid Interactive Simulations of Partial Differential Equations.

Computing has revolutionised the study of complex nonlinear systems, both by allowing us to solve previously intractable models and through the ability to visualise solutions in different ways. Using ubiquitous computing infrastructure, we provide a means to go one step further in using computers to understand complex models through instantaneous and interactive exploration. This ubiquitous infrastructure has enormous potential in education, outreach and research.

Minimal Morphoelastic Models of Solid Tumour Spheroids: A Tutorial.

Tumour spheroids have been the focus of a variety of mathematical models, ranging from Greenspan's classical study of the 1970 s through to contemporary agent-based models. Of the many factors that regulate spheroid growth, mechanical effects are perhaps some of the least studied, both theoretically and experimentally, though experimental enquiry has established their significance to tumour growth dynamics. In this tutorial, we formulate a hierarchy of mathematical models of increasing complexity to explore the role of mechanics in spheroid growth, all the while seeking to retain desirable simplicity and analytical tractability.

Concentration-Dependent Domain Evolution in Reaction-Diffusion Systems.

Pattern formation has been extensively studied in the context of evolving (time-dependent) domains in recent years, with domain growth implicated in ameliorating problems of pattern robustness and selection, in addition to more realistic modelling in developmental biology. Most work to date has considered prescribed domains evolving as given functions of time, but not the scenario of concentration-dependent dynamics, which is also highly relevant in a developmental setting. Here, we study such concentration-dependent domain evolution for reaction-diffusion systems to elucidate fundamental aspects of these more complex models.

Scheduled methadone reduces overall opioid requirements after pediatric posterior spinal fusion: A single center retrospective case series.

Background: Posterior spinal fusion to correct adolescent idiopathic scoliosis is associated with significant postoperative pain. Different modalities have been reported as part of a multimodal analgesic plan. Intravenous methadone acts as a mu-opioid agonist and N-Methyl-D-aspartate (NMDA) antagonist and has been shown to have opioid-sparing effects.

Preserved β-adrenergic-mediated vasodilation in skeletal muscle of young adults with obesity despite shifts in cyclooxygenase and nitric oxide synthase.

Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults.

Nitric oxide synthase inhibition in healthy adults reduces regional and total cerebral macrovascular blood flow and microvascular perfusion.

The importance of nitric oxide (NO) in regulating cerebral blood flow (CBF) remains unresolved, due in part to methodological approaches, which lack a comprehensive assessment of both global and regional effects. Importantly, NO synthase (NOS) expression and activity appear greater in some anterior brain regions, suggesting region-specific NOS influence on CBF. We hypothesized that NO contributes to basal CBF in healthy adults, in a regionally distinct pattern that predominates in the anterior circulation.

Control and controllability of microswimmers by a shearing flow.

With the continuing rapid development of artificial microrobots and active particles, questions of microswimmer guidance and control are becoming ever more relevant and prevalent. In both the applications and theoretical study of such microscale swimmers, control is often mediated by an engineered property of the swimmer, such as in the case of magnetically propelled microrobots. In this work, we will consider a modality of control that is applicable in more generality, effecting guidance via modulation of a background fluid flow.

Modelling Motility: The Mathematics of Spermatozoa.

In one of the first examples of how mechanics can inform axonemal mechanism, Machin's study in the 1950s highlighted that observations of sperm motility cannot be explained by molecular motors in the cell membrane, but would instead require motors distributed along the flagellum. Ever since, mechanics and hydrodynamics have been recognised as important in explaining the dynamics, regulation, and guidance of sperm. More recently, the digitisation of sperm videomicroscopy, coupled with numerous modelling and methodological advances, has been bringing forth a new era of scientific discovery in this field.

Opioid prescribing to preteen children undergoing ambulatory surgery in the United States.

Background: Overuse and misuse of opioids is a continuing crisis. The most common reason for children to receive opioids is postoperative pain, and they are often prescribed more than needed. The amount of opioids prescribed varies widely, even for minor ambulatory procedures.

Intercostal nerve cryoablation is associated with lower hospital cost during minimally invasive Nuss procedure for pectus excavatum.

Unlabelled: Minimally invasive repair of pectus excavatum (Nuss procedure) is associated with significant pain, and efforts to control pain impact resource utilization. Bilateral thoracic intercostal nerve cryoablation has been proposed as a novel technique to improve post-operative pain control, though the impact on hospital cost is unknown.

Methods: We conducted a retrospective study of patients undergoing a Nuss procedure from 2016 to 2019.

Computer-assisted beat-pattern analysis and the flagellar waveforms of bovine spermatozoa.

Obstructed by hurdles in information extraction, handling and processing, computer-assisted sperm analysis systems have typically not considered in detail the complex flagellar waveforms of spermatozoa, despite their defining role in cell motility. Recent developments in imaging techniques and data processing have produced significantly improved methods of waveform digitization. Here, we use these improvements to demonstrate that near-complete flagellar capture is realizable on the scale of hundreds of cells, and, further, that meaningful statistical comparisons of flagellar waveforms may be readily performed with widely available tools.

Epidural versus PCA Pain Management after Pectus Excavatum Repair: A Multi-Institutional Prospective Randomized Trial.

Introduction:  Postoperative pain control remains the primary reason for inpatient stay after minimally invasive repair of pectus excavatum. In a previous study, our group reported that early pain control was better in patients managed with a thoracic epidural, while late pain control was better in patients managed with patient-controlled analgesia (PCA). After revising our epidural transition and modifying the PCA protocol, we conducted a multi-institutional prospective randomized trial to evaluate these two pain control strategies.

Variation Between and Within Hospitals in Single Injection Caudal Local Anesthetic Dose: A Report From the Pediatric Regional Anesthesia Network.

Background: Given that variation exists in health care utilization, expenditure, and medical practice, there is a paucity of data on variation within the practice of anesthesia. The Pediatric Regional Anesthesia Network (PRAN) data lend itself to explore whether different medical practice patterns exist and if there are nerve blocks with more local anesthetic dosing variation than others. The primary aim of this study was to quantify variation in single injection caudal block dosing, and the secondary aim was to explore possible causes for variation (eg, number of blocks performed versus geographic location).

High-speed multifocal plane fluorescence microscopy for three-dimensional visualisation of beating flagella.

Analysis of flagellum and cilium beating in three dimensions (3D) is important for understanding cell motility, and using fluorescence microscopy to do so would be extremely powerful. Here, high-speed multifocal plane fluorescence microscopy, where the light path is split to visualise multiple focal planes simultaneously, was used to reconstruct and movement in 3D. These species are uniflagellate unicellular parasites for which motility is vital.

Automated identification of flagella from videomicroscopy via the medial axis transform.

Ubiquitous in eukaryotic organisms, the flagellum is a well-studied organelle that is well-known to be responsible for motility in a variety of organisms. Commonly necessitated in their study is the capability to image and subsequently track the movement of one or more flagella using videomicroscopy, requiring digital isolation and location of the flagellum within a sequence of frames. Such a process in general currently requires some researcher input, providing some manual estimate or reliance on an experiment-specific heuristic to correctly identify and track the motion of a flagellum.

Response of monoflagellate pullers to a shearing flow: A simulation study of microswimmer guidance.

Microscale swimming may be intuited to be dominated by background flows, sweeping away any untethered bodies with the prevalent flow direction. However, it has been observed that many microswimmers utilize ambient flows as guidance cues, in some cases resulting in net motion upstream, contrary to the dominant background fluid direction and our accompanying intuition. Thus the hydrodynamic response of small-scale motile organisms requires careful analysis of the complex interaction between swimmer and environment.

Boundary behaviours of Leishmania mexicana: A hydrodynamic simulation study.

It is well established that the parasites of the genus Leishmania exhibit complex surface interactions with the sandfly vector midgut epithelium, but no prior study has considered the details of their hydrodynamics. Here, the boundary behaviours of motile Leishmania mexicana promastigotes are explored in a computational study using the boundary element method, with a model flagellar beating pattern that has been identified from digital videomicroscopy. In particular a simple flagellar kinematics is observed and quantified using image processing and mode identification techniques, suggesting a simple mechanical driver for the Leishmania beat.

Complications in Pediatric Regional Anesthesia: An Analysis of More than 100,000 Blocks from the Pediatric Regional Anesthesia Network.

What We Already Know About This Topic: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Complications in pediatric regional anesthesia are rare, so a large sample size is necessary to quantify risk. The Pediatric Regional Anesthesia Network contains data on more than 100,000 blocks administered at more than 20 children's hospitals. This study analyzed the risk of major complications associated with regional anesthesia in children.

Greater Beta-Adrenergic Receptor Mediated Vasodilation in Women Using Oral Contraceptives.

Background: β-adrenergic receptors play an important role in mitigating the pressor effects of sympathetic nervous system activity in young women. Based on recent data showing oral contraceptive use in women abolishes the relationship between muscle sympathetic nervous system activity and blood pressure, we hypothesized forearm blood flow responses to a β-adrenergic receptor agonist would be greater in young women currently using oral contraceptives (OC+, n = 13) when compared to those not using oral contraceptives (OC-, n = 10).

Methods: Women (18-35 years) were studied during the early follicular phase of the menstrual cycle (days 1-5) or placebo phase of oral contraceptive use.

Preserved Microvascular Endothelial Function in Young, Obese Adults with Functional Loss of Nitric Oxide Signaling.

Data indicate endothelium-dependent dilation (EDD) may be preserved in the skeletal muscle microcirculation of young, obese adults. Preserved EDD might be mediated by compensatory mechanisms, impeding insight into preclinical vascular dysfunction. We aimed to determine the functional roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) toward EDD in younger obese adults.

Exercise vasodilation is greater in women: contributions of nitric oxide synthase and cyclooxygenase.

Purpose: We hypothesized exercise vasodilation would be greater in women due to nitric oxide synthase (NOS) and cyclooxygenase (COX) signaling.

Methods: 45 healthy adults (23 women, W, 22 men, M, 26 ± 1 years) completed two 10-min trials of dynamic forearm exercise at 15 % intensity. Forearm blood flow (FBF; Doppler ultrasound), arterial pressure (brachial catheter), and forearm lean mass were measured to calculate relative forearm vascular conductance (FVCrel) = FBF 100 mmHg(-1) 100 g(-1) lean mass.