Maneuvering Characteristics of Bilateral Amplitude-Asymmetric Flapping Motion Based on a Bat-Inspired Flexible Wing

Flapping-wing micro air vehicles (FWMAVs) have gained much attention from researchers due to their exceptional performance at low Reynolds numbers. However, the limited understanding of active aerodynamic modulation in flying creatures has hindered their maneuverability from reaching that of their biological counterparts. In this article, experimental investigations were conducted to examine the effect of the bilateral amplitude asymmetry of flexible flapping wings. A reduced bionic model featuring bat-like wings is built, and a dimensionless number ΔΦ* is introduced to scale the degree of bilateral amplitude asymmetry in flapping motion. The experimental results suggest that the bilateral amplitude-asymmetric flapping motion primarily induces maneuvering control forces of coupling roll moment and yaw moment. Also, roll moment and yaw moment have a good linear relationship. To achieve more efficient maneuvers based on this asymmetric motion, it is advisable to maintain ΔΦ* within the range of 0 to 0.4. The magnitude of passive pitching deformation during the downstroke is significantly greater than that during the upstroke. The phase of the peak of the passive pitching angle advances with the increase in flapping amplitude, while the valleys lag. And the proportion of pronation and supination in passive pitching motion cannot be adjusted by changing the flapping amplitude. These findings have important practical relevance for regulating turning maneuvers based on amplitude asymmetry and help to understand the active aerodynamic modulation mechanism through asymmetric wing kinematics.

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. Here we considered the rapid escape maneuver of hummingbirds who were initially hovering but then startled by the frontal approach of a looming object. During the maneuver, the hummingbirds substantially changed their wingbeat frequency, wing trajectory, and other kinematic parameters. Using wing kinematics reconstructed from high-speed videos and computational fluid dynamics modeling, we found that although the same inertial effect drove the wing flipping at stroke reversal as in hovering, significant power input was required to pitch up the wings during downstroke to enhance aerodynamic force production; furthermore, the net power input could be positive for wing pitching in a complete wingbeat cycle. Therefore, our study suggests that an active mechanism was present during the maneuver to drive wing pitching. In addition to the powered pitching, wing deviation during upstroke required twice as much power as hovering to move the wings caudally when the birds redirected the aerodynamic force vector for escaping. These findings were consistent with our hypothesis that enhanced muscle recruitment is essential for hummingbirds' escape maneuvers.

Clinical significance of down-beating nystagmus and postural control loss when returning to a sitting position during the canalith repositioning maneuver

Patients with benign paroxysmal positional vertigo (BPPV) occasionally experience severe dizziness, could not maintain the sitting posture, and then fall onto or off the examination table when they return to the sitting position, which is the last step of the barbecue maneuver and Epley maneuver (EM); down-beating nystagmus is also observed. This study aims to investigate the clinical characteristics and significance of these findings. We retrospectively reviewed video data showing nystagmus and medical records of adult patients diagnosed with canalolithiasis of the horizontal canal and the posterior canal (PC) BPPV who underwent barbecue maneuver and EM, respectively, in outpatient clinics from April 2014 to March 2019. This study included 112 patients (28 horizontal canal BPPV and 94 PC BPPV cases). Among the 122 BPPV cases, only 14 (14.9%) were analyzed, due to their occurrence during EM. Down-beating nystagmus appeared at 3.6 seconds on average after returning to the sitting position, and the patients fell onto or off the examination table at 4.4 seconds on average after the onset of the nystagmus. The average duration of the down-beating nystagmus was 20.3 seconds. In all 14 cases, no nystagmus was induced by the Dix-Hallpike test performed again after EM, confirming that the treatment was successful. During the EM, down-beating nystagmus and falling onto or off the examination table occurred in approximately 15% of cases. As the risk of falls increases, the patient should be secured immediately after EM. Moreover, it can be inferred that the findings occur when otoconia in the PC enter the utricle, suggesting a successful treatment.

Use of the "ee" Maneuver in a Patient With Dysphagia Due to Severe Pseudobulbar Palsy

Dysphagia in pseudobulbar palsy is characterized by impairment of the oral stage of swallowing. The flow of the bolus from the oral cavity into the pharynx at the fauces may be blocked in some patients, which prevents the bolus flow by contact of the tongue with the palate. Herein, we demonstrated a case with pseudobulbar palsy who could deliver bolus from the oral cavity to the pharynx by vocalizing "ee." An 81-year-old man presented with a recurrent cerebral infarction due to cardiogenic embolism. He presented with pseudobulbar palsy and had severe dysphagia due to bilateral cerebral hemisphere lesions. On day 84, a videofluoroscopic examination of swallowing was performed in a 30° reclining posture. When the bolus reached the posterior part of the tongue in the oral cavity, the clinician asked the patient to say "ee." The base of the tongue moved forward and downward, and the anterior to the middle part of the tongue was elevated in the mouth. As a result, the fauces opened, the functional blockage was released, and the bolus flowed into the pharyngeal cavity. Shortly after the swallowing reflex, the bolus passed through the pharynx. We have named this swallowing maneuver the "ee" maneuver. The "ee" maneuver can be one of the swallowing methods to improve bolus transport from the oral cavity to the pharynx in patients with dysphagia and cognitive impairment due to pseudobulbar palsy.

BPPV Simulation: A Powerful Tool to Understand and Optimize the Diagnostics and Treatment of all Possible Variants of BPPV

BPPV is a mechanical disorder caused by the displacement of otolith debris into the semicircular canals. The treatment involves different repositioning maneuvers to bring the debris back into the utricle. This study aims to show how dynamic simulation models based on fluid dynamics and MRI, can help to visualize and understand the movement of the debris within the canals during head movement in 3D as a function of time. The user can define the rotation angle and plane at each step of the maneuver and then the model visualizes the canal and the otoconial movement in 3D. The simulation developed also allows alteration of various parameters like the rotational head acceleration, the duration of each step of the maneuver, the initial position of the otoconial debris in the canal, the size and the number of the particles and fluid dynamics of endolymph. The clod movement is visualized in such a way that it allows a better understanding of the impact and efficacy of various liberation maneuvers and why certain maneuvers might fail when not applied properly in the clinic. The model allows simulation of multi-canal BPPV. In this paper we demonstrate the power of the model applied on the maneuvers of Semont and Yacovino when executed in different ways. The model aims to provide a visual explanation for the need of specific maneuvers for each type of BPPV. The simulator presented here can be used to test the efficacy of existing maneuvers and help in the development of new maneuvers to treat different BPPV variants.

Whole-Body Change-of-Direction Task Execution Asymmetries After Anterior Cruciate Ligament Reconstruction

Cutting maneuvers can be executed at a range of angles and speeds, and these whole-body task descriptors are closely associated with lower-limb mechanical loading. Asymmetries in angle and speed when changing direction off the operated and nonoperated limbs after anterior cruciate ligament reconstruction may therefore influence the interpretation of interlimb differences in joint-level biomechanical parameters. The authors hypothesized that athletes would reduce center-of-mass heading angle deflection and body rotation during the change-of-direction stance phase when cutting from the operated limb, and would compensate for this by orienting their center-of-mass trajectory more toward the new intended direction of travel prior to touchdown. A total of 144 male athletes 8 to 10 months after anterior cruciate ligament reconstruction performed a maximum-effort sidestep cutting maneuver while kinematic, kinetic, and ground reaction force data were recorded. Peak ground reaction force and knee joint moments were lower when cutting from the operated limb. Center-of-mass heading angle deflection during stance phase was reduced for cuts performed from the operated limb and was negatively correlated with heading angle at touchdown. Between-limb differences in body orientation and horizontal velocity at touchdown were also observed. These systematic asymmetries in cut execution may require consideration when interpreting joint-level interlimb asymmetries after anterior cruciate ligament reconstruction and are suggestive of the use of anticipatory control to co-optimize task achievement and mechanical loading.

Frequency and Significance of Maneuvers to Dissect the Distal Internal Carotid Artery During Carotid Endarterectomy

OBJECTIVES

To describe the frequency, factors associated with, and significance of surgical dissection maneuvers of the distal internal carotid artery (ICA) during carotid endarterectomy (CEA).

METHODS

In this retrospective analysis of prospectively collected information in patients undergoing CEA, we recorded information on demographics, risk factors and comorbidities, dissection maneuvers of the distal ICA, other operative variables and neurological outcome measures.

RESULTS

During the period July 2008 and February 2020 inclusive, 218 consecutive patients (180 males, median age 69.5 years) underwent 240 CEAs. In 117 (48.8%) of them, CEA was performed for a symptomatic stenosis. Dissection maneuvers of the distal ICA were required in 77 cases (32.1%), including division and ligation of the sternocleidomastoid vessels in 66 cases (27.5%), mobilization of the XII cranial nerve in 69 cases (28.7%, with concomitant transection of the superior root of the ansa cervicalis in 11 cases, 4.6%) and division of the posterior belly of the digastric muscle in 8 cases (3.3%). Styloid osteotomy was not required in any case. Smoking was the single predictive factor associated with the use of an adjunctive dissection maneuver (odds ratio 2.23, p = 0.009). The use of a patch was more common in smokers (16% vs 7.1% in non-smokers, odds ratio 2.48, p = 0.05). Perioperative stroke and/or death rate was 0%, not allowing testing for associations with maneuver performance. Two patients (0.8%) developed a transient ischemic attack and 4 patients (1.7%) a cranial nerve injury (CNI), including 2 patients with recurrent laryngeal nerve palsy, diagnosed on routine laryngoscopy during planning of a contralateral CEA. There was no association between CNI and dissection of the distal ICA using an operative adjunct (p = 0.60).

CONCLUSIONS

Several surgical maneuvers are often required to accomplish dissection of the distal ICA beyond the point of atherosclerotic disease. When dictated by operative findings, such maneuvers are deemed safe.

Short CRP for Anterior Canalithiasis: A New Maneuver Based on Simulation With a Biomechanical Model

Introduction/Objective: Anterior canalithiasis is an uncommon and challenging diagnosis. This is due in part to the difficulty of defining the affected side, the extreme positioning required to carry out described therapeutic maneuvers, and the infrequent use of specific maneuvers. Our objective is to present a new treatment alternative for anterior canalithiasis which is based on the well-known canalith repositioning procedure (CRP) described by Epley and which is used routinely in the treatment of both posterior and anterior canalithiasis. Analysis of the standard CRP for anterior canalithiasis with a biomechanical model validates that this new maneuver is an enhanced treatment option for anterior canalithiasis. We call the new maneuver the “short CRP.”

Methods: A previously published 3D biomechanical model of the human labyrinths for the study of BPPV was used to analyze the conventional CRP in the treatment of anterior canalithiasis. The expected position of free otoliths near the anterior ampulla of the anterior semicircular duct was followed while recreating the sequential positions of the CRP. Although the standard CRP was possibly effective, certain enhancements were evident that could increase successful repositioning. These enhancements were incorporated into the modification of the CRP presented here as the “short CRP” for anterior canalithiasis.

Results: The traditional CRP used for posterior canalithiasis can also be used for anterior canalithiasis. Although in the traditional CRP the head hangs 30° below horizontal, our simulation shows that a 40° head-hang below horizontal is an enhancement and may ensure progression of anterior otolith debris. Elimination of Position 4 of the classic CRP, in which the face is turned 45° toward the floor, was also seen as an enhancement as this position is predicted to cause retrograde movement of otoliths back into the anterior canal if the patient tucks the chin in position 4 or when sitting up.

Conclusion: A modification of the CRP called the “short CRP” can be used to treat anterior canalithiasis. Model analysis predicts possible increased efficacy over the standard CRP. Model analysis of existing BPPV treatments is a valuable exercise for examination and can lead to realistic enhancements in patient care.

BeiDou Satellite Unhealthy States and the Impact on System Performance

The BeiDou system satellites may be unhealthy due to many reasons, affecting system performance in different ways. Therefore, it is important to analyze the causes and characteristics of the satellites’ unhealthy states. In this study, these states are classified into five types based on the broadcast ephemeris. Three criteria are presented, based on which a general classification method is proposed. Data from July 2017 to June 2018 are analyzed to validate the method, from which we know that the average unhealthy duration due to satellite maneuvers is much longer than the duration of unhealthy states related to satellite orbit or clock anomalies, and the other unhealthy states may be caused by inbound or outbound satellites. Statistics show that most of the time, the number of unhealthy satellites is no more than two and the average positioning accuracy in the service area will decrease by no more than 0.75 and 1.2 meters when one or two BDS satellites are unhealthy, respectively.

Treatment of Patients With Benign Paroxysmal Positional Vertigo and Severe Immobility Using the Particle Repositioning Chair: A Retrospective Cohort Study

OBJECTIVE

To report treatment of benign paroxysmal positional vertigo (BPPV) in patients unable to undergo traditional canalith repositioning maneuvers (CRMs) using a particle repositioning chair (PRC).

METHODS

A retrospective chart review was conducted at a single high-volume otology practice of patients diagnosed with BPPV from 2007 to 2017 with immobility prohibiting use of traditional CRMs. Patients were diagnosed and treated using a PRC, and outcome measures including resolution, recurrence, and number of treatment visits were recorded.

RESULTS

A total of 34 patients meeting criteria were identified, 24 of whom had cervical spine disease and 10 of whom had other prohibitive immobility. Symptoms were present for between 5 days and 11 years at presentation, with mean and median of 552 and 90 days, respectively. Symptoms resolved in 68% of patients and recurred in 13% of those patients. Most patients required 1 treatment visit.

CONCLUSIONS

Successful treatment of patients with BPPV and concomitant immobility prohibiting traditional CRMs is reported using the PRC. Benign paroxysmal positional vertigo in the setting of immobility is an indication for treatment with a PRC if available.

Prebronchoplasty ventilation maneuver: Steering the outcome in the management of bronchial injuries!

Bronchial injuries are infrequently seen following blunt chest trauma and mostly have subtle clinical presentation. Its diagnosis is challenging and may be delayed resulting in myriad complications such as secondary infection, bronchiectasis, atelectasis, collapse, and fibrosis. We discuss the anesthetic management of a case of complete right principle bronchus transection with distal lung collapse, posted for surgical repair and highlight the unique intraoperative ventilation maneuver to identify the functional lung segment. This unique yet less recognized ventilation maneuver of the collapsed lung segment was performed just before bronchoplasty. The aforesaid maneuver may act as a pointer for further surgical course and a useful diagnostic and therapeutic modality in ensuring the eventual outcome in this subset of patients.

A Detailed Review of Hip Reduction Maneuvers: A Focus on Physician Safety and Introduction of the Waddell Technique

Dislocation of the hip is a well-described event that occurs in conjunction with high-energy trauma or postoperatively after total hip arthroplasty. Bigelow first described closed treatment of a dislocated hip in 1870, and in the last decade many reduction techniques have been proposed. In this article, we review all described techniques for the reduction of hip dislocation while focusing on physician safety. Furthermore, we introduce a modified technique for the reduction of posterior hip dislocation that allows the physician to adhere to the back safety principles set for by the Occupational Safety and Health Administration.