Hummingbirds rapidly respond to the removal of visible light and control a sequence of rate-commanded escape manoeuvres in milliseconds.

Hummingbirds routinely execute a variety of stunning aerobatic feats, which continue to challenge current notions of aerial agility and controlled stability in biological systems. Indeed, the control of these amazing manoeuvres is not well understood. Here, we examined how hummingbirds control a sequence of manoeuvres within milliseconds, and tested whether and when they use vision during this rapid process.

Inertial coupling of the hummingbird body in the flight mechanics of an escape manoeuvre.

When a hovering hummingbird performs a rapid escape manoeuvre in response to a perceived threat from the front side, its body may go through simultaneous pitch, yaw and roll rotations. In this study, we examined the inertial coupling of the three-axis body rotations and its effect on the flight mechanics of the manoeuvre using analyses of high-speed videos as well as high-fidelity computational modelling of the aerodynamics and inertial forces. We found that while a bird's pitch-up was occurring, inertial coupling between yaw and roll helped slow down and terminate the pitch, thus serving as a passive control mechanism for the manoeuvre.

An Integrated Experimental-Computational Study of Vocal Fold Vibration in Type I Thyroplasty.

Subject-specific computational modeling of vocal fold (VF) vibration was integrated with an ex vivo animal experiment of type 1 thyroplasty to study the effect of the implant on the vocal fold vibration. In the experiment, a rabbit larynx was used to simulate type 1 thyroplasty, where one side of the vocal fold was medialized with a trans-muscular suture while the other side was medialized with a silastic implant. Vocal fold vibration was then achieved by flowing air through the larynx and was filmed with a high-speed camera.

Direct observation of carbon slurry flow behavior and its effect on electrochemical performance in a microfluidic electrochemical flow capacitor.

Carbon slurries have been used as "flowable electrodes" in various electrochemical systems, and the slurry flow characteristics play an important role in the system electrochemical performance. For example, in an electrochemical flow capacitor (EFC), activated carbon particles must pass electrical charge from a stationary electrode to surrounding particles particle-electrode and particle-particle interactions to store energy in the electric double layer. So far, particle behaviors under a continuous flow condition have not been observed due to the slurry's opacity, and studies of the device's performance thus have been mainly on a bulk level.

Hummingbirds use wing inertial effects to improve manoeuvrability.

Hummingbirds outperform other birds in terms of aerial agility at low flight speeds. To reveal the key mechanisms that enable such unparalleled agility, we reconstructed body and wing motion of hummingbird escape manoeuvres from high-speed videos; then, we performed computational fluid dynamics modelling and flight mechanics analysis, in which the time-dependent forces within each wingbeat were resolved. We found that the birds may use the inertia of their wings to achieve peak body rotational acceleration around wing reversal when the aerodynamic forces were small.

Active wing-pitching mechanism in hummingbird escape maneuvers.

Previous studies suggested that wing pitching, i.e. the wing rotation around its long axis, of insects and hummingbirds is primarily driven by an inertial effect associated with stroke deceleration and acceleration of the wings and is thus passive.

Subject-Specific Modeling of Implant Placement for Type I Thyroplasty Surgery.

Type I thyroplasty is widely used to improve voice production in patients affected by unilateral vocal fold paralysis. Almost two-thirds of laryngologists report using Silastic® implants to medialize the vocal fold, with implant size, shape, and location determined experientially. However, post-surgical complications arising from this procedure (extrusion, migration, resizing) necessitate revision in 4.

Custom Laser-Cut Silastic® Implants for Type I Thyroplasty in a Preclinical Model.

This study aimed to produce customized silicone elastomer implants of varied size and shape for optimization of type I thyroplasty procedures in a rabbit model. Computer-aided design models of different implant designs were designed and used to program laser cutting of a medical-grade Silastic® sheet. Laser-cut implants were produced rapidly and cost-efficiently.

Musculoskeletal wing-actuation model of hummingbirds predicts diverse effects of primary flight muscles in hovering flight.

Hummingbirds have evolved to hover and manoeuvre with exceptional flight control. This is enabled by their musculoskeletal system that successfully exploits the agile motion of flapping wings. Here, we synthesize existing empirical and modelling data to generate novel hypotheses for principles of hummingbird wing actuation.

Aortic Leaflet Stresses Are Substantially Lower Using Pulmonary Visceral Pleura Than Pericardial Tissue.

Porcine heart and bovine pericardium valves, which are collagen-based with relatively little elastin, have been broadly utilized to construct bioprosthetic heart valves (BHVs). With a larger proportion of elastin, the pulmonary visceral pleura (PVP) has greater elasticity and could potentially serve as an advantageous biomaterial for the construction/repair of BHVs. The question of how the aortic valve's performance is affected by its bending rigidity has not been well studied.

Subject-Specific Computational Fluid-Structure Interaction Modeling of Rabbit Vocal Fold Vibration.

A full three-dimensional (3D) fluid-structure interaction (FSI) study of subject-specific vocal fold vibration is carried out based on the previously reconstructed vocal fold models of rabbit larynges. Our primary focuses are the vibration characteristics of the vocal fold, the unsteady 3D flow field, and comparison with a recently developed 1D glottal flow model that incorporates machine learning. The 3D FSI model applies strong coupling between the finite-element model for the vocal fold tissue and the incompressible Navier-Stokes equation for the flow.

Numerical and experimental investigations on vocal fold approximation in healthy and simulated unilateral vocal fold paralysis.

We have developed a novel surgical/computational model for the investigation of unilateral vocal fold paralysis (UVFP) which will be used to inform future in silico approaches to improve surgical outcomes in type I thyroplasty. Healthy phonation (HP) was achieved using cricothyroid suture approximation on both sides of the larynx to generate symmetrical vocal fold closure. Following high-speed videoendoscopy (HSV) capture, sutures on the right side of the larynx were removed, partially releasing tension unilaterally and generating asymmetric vocal fold closure characteristic of UVFP (sUVFP condition).

A one-dimensional flow model enhanced by machine learning for simulation of vocal fold vibration.

A one-dimensional (1D) unsteady and viscous flow model that is derived from the momentum and mass conservation equations is described, and to enhance this physics-based model, a machine learning approach is used to determine the unknown modeling parameters. Specifically, an idealized larynx model is constructed and ten cases of three-dimensional (3D) fluid-structure interaction (FSI) simulations are performed. The flow data are then extracted to train the 1D flow model using a sparse identification approach for nonlinear dynamical systems.

Medialization Laryngoplasty: A Review for Speech-Language Pathologists.

Purpose The purpose of this study is to familiarize speech-language-pathologists with the current state of the science regarding medialization laryngoplasty in the treatment of voice disorders, with emphasis on current evidence-based practice, voice outcomes, and future directions for research. Method A literature review was performed in PubMed and Embase using the keywords and or . Articles published between 2010 and 2020 were reviewed for data about clinical applications, technical approach, voice-related outcomes, and basic science or clinical innovations with the potential to improve patient care.

A reduced-order flow model for vocal fold vibration: from idealized to subject-specific models.

We present a reduced-order model for fluid-structure interaction (FSI) simulation of vocal fold vibration during phonation. This model couples the three-dimensional (3D) tissue mechanics and a one-dimensional (1D) flow model that is derived from the momentum and mass conservation equations for the glottal airflow. The effects of glottal entrance and pressure loss in the glottis are incorporated in the flow model.

3D computational models explain muscle activation patterns and energetic functions of internal structures in fish swimming.

How muscles are used is a key to understanding the internal driving of fish swimming. However, the underlying mechanisms of some features of the muscle activation patterns and their differential appearance in different species are still obscure. In this study, we explain the muscle activation patterns by using 3D computational fluid dynamics models coupled to the motion of fish with prescribed deformation and examining the torque and power required along the fish body with two primary swimming modes.

A Reduced-Order Flow Model for Fluid-Structure Interaction Simulation of Vocal Fold Vibration.

We present a novel reduced-order glottal airflow model that can be coupled with the three-dimensional (3D) solid mechanics model of the vocal fold tissue to simulate the fluid-structure interaction (FSI) during voice production. This type of hybrid FSI models have potential applications in the estimation of the tissue properties that are unknown due to patient variations and/or neuromuscular activities. In this work, the flow is simplified to a one-dimensional (1D) momentum equation-based model incorporating the entrance effect and energy loss in the glottis.

Computational Fluid Dynamics Analysis of Surgical Approaches to Bilateral Vocal Fold Immobility.

Objectives: Bilateral vocal fold immobility (BVFI) is a rare and life-threatening condition in which both vocal folds are fixed, resulting in airway obstruction associated with life-threatening respiratory compromise. Treatment of BVFI is largely surgical and remains an unsatisfactory compromise between voice, breathing, and swallowing. No comparisons between currently employed techniques currently exist.

A novel device for air removal from vascular access line: a bench study.

Efficient air removal from a vascular access line is a key step to prevent air embolism. Existing devices, especially for rapid infusers, are far from optimum. In this study, we developed a novel device, vascular access line air removal device (VALARD), and compared its efficiency of air removal and pause time of forward bulk flow with a commonly used device, the Belmont pump.

Three-dimensional simulation for fast forward flight of a calliope hummingbird.

We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s(-1).

Nonstimulated rabbit phonation model: Cricothyroid approximation.

Objectives/hypothesis: To describe a nonstimulated in vivo rabbit phonation model using an Isshiki type IV thyroplasty and uninterrupted humidified glottal airflow to produce sustained audible phonation.

Study Design: Prospective animal study.

Methods: Six New Zealand white breeder rabbits underwent a surgical procedure involving an Isshiki type IV thyroplasty and continuous airflow delivered to the glottis.

Subject-Specific Computational Modeling of Evoked Rabbit Phonation.

When developing high-fidelity computational model of vocal fold vibration for voice production of individuals, one would run into typical issues of unknown model parameters and model validation of individual-specific characteristics of phonation. In the current study, the evoked rabbit phonation is adopted to explore some of these issues. In particular, the mechanical properties of the rabbit's vocal fold tissue are unknown for individual subjects.

Wing-pitching mechanism of hovering Ruby-throated hummingbirds.

In hovering flight, hummingbirds reverse the angle of attack of their wings through pitch reversal in order to generate aerodynamic lift during both downstroke and upstroke. In addition, the wings may pitch during translation to further enhance lift production. It is not yet clear whether these pitching motions are caused by the wing inertia or actuated through the musculoskeletal system.

Three-dimensional flow and lift characteristics of a hovering ruby-throated hummingbird.

A three-dimensional computational fluid dynamics simulation is performed for a ruby-throated hummingbird (Archilochus colubris) in hovering flight. Realistic wing kinematics are adopted in the numerical model by reconstructing the wing motion from high-speed imaging data of the bird. Lift history and the three-dimensional flow pattern around the wing in full stroke cycles are captured in the simulation.

Fluid-structure interaction involving large deformations: 3D simulations and applications to biological systems.

Three-dimensional fluid-structure interaction (FSI) involving large deformations of flexible bodies is common in biological systems, but accurate and efficient numerical approaches for modeling such systems are still scarce. In this work, we report a successful case of combining an existing immersed-boundary flow solver with a nonlinear finite-element solid-mechanics solver specifically for three-dimensional FSI simulations. This method represents a significant enhancement from the similar methods that are previously available.