Head Stabilization Research Articles

Noisy galvanic vestibular stimulation influences head stability in young healthy adults while standing on a moving platform

BackgroundThe ability to stand with eyes closed on a sinusoidal translational moving platform may be affected by spatial orientation owing to vestibular input information. Moreover, changes in the frequency of the moving platform may affect the sensory reweighting through somatosensory and vestibular sensations. However, it is unclear whether noisy galvanic vestibular stimulation (nGVS), which activates vestibular-related brain regions, affects the stability of individuals standing on a platform moving at different frequencies. Research questionDo vestibular stimulation by nGVS and changes in the frequency of translationally moving platforms affect the standing stability of individuals? MethodsThirty-one healthy young adult participants were provided both sham and nGVS interventions while they maintained a static standing position, with their eyes closed, on an anterior-posterior sinusoidal translation platform. The nGVS was adapted to an optimal intensity below the perceptual threshold (frequency band: 100–640 Hz), and the sham stimulus was adapted to 0 µA. The participants were randomly assessed for postural stability at 0.2, 0.6, and 1.2 Hz moving platform frequencies for 80 s each under both stimulus conditions. Postural stability was calculated as the root mean square (RMS) sway from head accelerations in the anteroposterior (AP) and mediolateral (ML) directions for 50 s between 20 and 70 s during the 80 s period, measured using an inertial sensor placed on the external occipital ridge. ResultsnGVS significantly reduced the RMS sway of head acceleration in the AP direction compared with sham stimulation. Furthermore, nGVS significantly reduced RMS sway in the ML direction compared with sham stimulation at a 1.2 Hz moving platform oscillation. SignificanceThese findings suggest that postural adjustment by the vestibular system influences head stability on a moving platform at specific sinusoidal translation frequencies, suggesting that nGVS may reduce head sway.

Transition of deformation modes from bending to auxetic compression in origami-based metamaterials for head protection from impact

For the protection of the human head by energy absorption structures, a soft mechanical response upon contact with the head is required to mitigate the effect of impact, while a hard mechanical response for highly efficient energy absorption is required to stop the movement of the head. This study realized the opposite mechanical properties during head protection by transitioning the deformation mode from bending to auxetic compression. First, non-linear finite element (FE) models were constructed to numerically reproduce the bending behavior. The calculated force responses agreed well with forces in bending tests. Using the FE models, the EA structures with proper transition of deformation modes were designed and installed in the seat headrests of real vehicles. Head protection was evaluated by dynamic loading in sled testing, in which the force on the head of the crash test dummy was measured. The head injury criterion improved from 274 to 155, indicating the superior performance of the tested structures compared to that achieved by energy absorption structures based on steel plates. Moreover, the deformation of auxetic structures prevented neck bending by holding the head. These findings present new possibilities for effectively protecting the human body by mitigating impact, facilitating energy absorption, and ensuring head stability.

Research on Unmanned Surface Vessel Aggregation Formation Based on Improved A* and Dynamic Window Approach Fusion Algorithm

The traditional A* and DWA fusion algorithm has three problems in the task of aggregation formation: one is the lack of meeting coordination strategy, the other is the inability to unify the terminal course, and the third is too many turning points in the global path. To solve the above problems, an improved algorithm is proposed. Firstly, by smoothing the global planning path, the stability of a USV heading in the navigation is improved. Then, by adding the key points of the global path, a guide path is formed to unify the terminal heading range. Finally, by adding an encounter coordination strategy, aggregation efficiency is improved. Simulation experiments were carried out in the Python environment based on this algorithm. The results show that the improved algorithm can improve the navigation obstacle avoidance ability of USVs and guide multiple USVs to finish the task of aggregation formation.

Effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during sitting position.

The purpose of this study was to test the hypothesis in healthy subjects that masticatory movements affect head and trunk sways, and sitting and foot pressure distributions during sitting position. A total of 30 healthy male subjects with an average age of 25.3 years (range, 22-32 years) were evaluated. The CONFORMatTM and MatScanTM system were used to analyze changes in sitting pressure distribution (center of sitting pressure: COSP) and changes in foot pressure distribution (center of foot pressure: COFP) respectively, and the 3-dimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained sitting position with rest position, centric occlusion, and chewing. The total trajectory length of COSP/COFP, COSP/COFP area, and head and trunk sway values were compared between the three conditions to evaluate whether masticatory movement affected the stability of head and trunk sways, and sitting and foot pressure distributions. Total trajectory length of COSP and COSP area during chewing were significantly shorter and smaller respectively than it was in rest position and centric occlusion (p < 0.016). Head sway value during chewing was significantly larger than it was in rest position and centric occlusion (p < 0.016). Masticatory movements affect sitting pressure distribution and head movements during sitting position.

QUANTITATIVE ASSESSMENT OF THE STABILITY OF PORTABLE RADIOGRAPHIC MONITORING TOOLS TO THE FACTORS OF A TRANSPORT ACCIDENT BY THE METHOD OF FINITE ELEMENT CALCULATIONS

A method of quantitative finite-element verification of stability of design and technological solutions of new generation portable radiographic equipment to the factors of transport accident at the stage of automated design of mathematical solid model of the shutter-type radiation head using software packages: "ZENIT-95" and "LS-DYNA" is proposed for consideration. The need for virtual quantitative assessment of stability of developed gamma detector components to emergency transport conditions at the design stage is largely due to the need to reduce costs for full-scale prototyping of technical solutions and test emergency tests. At the same time, production of prototypes equipped with radionuclide emitters without substantiating confirmation of the consistency of design solutions to extreme transportation conditions is certainly risky. Minimization of risk of making incorrect technical decisions at the stage of designing of radiographic control facilities of new generation with confirmation of consistency of design solutions to conditions of emergency transportation can be provided with the use of systems of automated design in 3D format and program-calculating modules "LS-DYNA" and "ZENIT-95" by finite-element calculations method. The object of the quantitative analysis of stability of the main functional unit of portable gamma detector to the transport accident factors by the finite element calculations method is a mathematical solid model of the radiation head conditionally containing radionuclide radiator and virtually exposed to transport accident factors: fall from height onto a target; thermal effects of fire. The 3D model of the WG as the main functional part of the gamma detector represents a logically connected system of elements, the state of which can be described by a set of differential equations, the solution of which using digital technology determines the stresses, strains and zones of thermal effect, allowing a quantitative assessment of mechanical strength and thermal stability of the structural solutions of the product. The results of finite element analysis in the software package "LS-DYNA" with a quantitative assessment of structural and strength stability of the radiation head of a gamma detector when falling from height, as well as the results of stability to thermal influence by the example of a finite element model of the radiation head in the software package "ZENIT-95" are presented.

Closed Reduction Technique for Acetabular Fractures with Femoral Head Protrusion and Concomitant Superolateral Impaction: A Case Report.

Closed reduction of acetabular fractures with femoral head protrusion and superolateral femoral head impaction may be challenging because the intact acetabular roof may block anatomic reduction with traditional maneuvers. We report the use of a 5-step technique for this unique pattern: medializing force to disengage the femoral head, axial traction to clear the intact ilium, lateralizing force to center the head underneath the acetabular roof, confirmation of femoral head stability, and skeletal traction placement. Acetabular fractures with femoral head protrusion and concomitant superolateral impaction may be reduced with an initial medializing force followed by axial and lateralizing forces.

Znaczenie systematycznej rehabilitacji na przestrzeni 45 lat pacjentki z rozwojową dysplazją stawu biodrowego (studium przypadku)

Congenital hip dysplasia is a teratogenic defect and affects 2% of the population; It arises in the fetal period and can be caused by pathological factors from both the mother and the fetus. The hallmark of congenital hip dysplasia is an undeveloped, excessively shallow acetabulum that prevents stabilization of the femoral head, resulting in hip dislocation. In recent years, there has been a shift in understanding of this musculoskeletal defect, based on early clinical and ultrasound findings, to developmental hip dysplasia, which can present as hip subluxation or dislocation. This paper presents the stages of treatment of a patient with developmental hip dysplasia over a 45-year period, the course of rehabilitation, and the effects of improvement after the use of CD34+ stem cells.

Influence of wearing complete dentures on control of head position during walking in edentulous older adults.

Coordination between the trunk and head is considered important for walking stability. Recent studies have reported that wearing complete dentures could improve trunk stability during walking; however, its effect on the head has not been clarified. This study aimed to clarify the effect of complete dentures on head stability during walking in edentulous older adults. Twenty edentulous older adults (11 men and 9 women; mean age, 78.6±5.8 years) who used complete dentures were included in the study. Acceleration and angle rate sensors were placed on the participants' brow, chin, and waist, and they were asked to walk a 20-m passage under two conditions: with and without dentures. The outcomes used to assess head stability were the variance values of acceleration and angle rate, the peak-to-peak values, harmonic ratio, root mean square, integrated values of the difference, and dynamic time warping data obtained from the sensors. The variance values of the brow acceleration were compared using a paired t-test, and other outcomes were compared using a Wilcoxon signed-rank test. All significance levels were set at 5%. Acceleration without dentures, the variance values of the chin and the peak-to-peak values of the brow and chin were significantly larger than with dentures. Angle rate without dentures, the variance values and the peak-to-peak values of the brow and chin were also significantly larger than with dentures. Wearing complete dentures while walking might improve head stability and contribute to walking stability in edentulous older adults.

WITHDRAWN: Incision capsulaire de la hanche en forme de U : un moyen simple de réaliser la capsulorrhaphie dans la maladie luxante de la hanche – Note technique

Developmental dysplasia of the hip is one of the commonest hip anomalies encountered in pediatric patients. Stabilization of the femoral head into the acetabulum is crucial for normal hip joint development. When surgical intervention is decided, open reduction is needed to remove any obstacle that hinders hip reduction. Capsulorraphy is an essential step for minimizing instability of the hip after reduction. The classic T-shaped capsular incision is done by two incisions: vertical limb parallel to femoral neck axis and a transverse one parallel to the inguinal ligament 5mm distally to proximal capsular attachment. The cumbersomeness of this technique was noticed in suturing of the resulted two flabs from this incision. So, the suggested U-shaped incision makes suturing of the capsule easier with multiple stitches. Level of evidenceIV.

Modular, cement-free, customized headpost and connector-chamber implants for macaques

BackgroundNeurophysiological studies with awake macaques typically require chronic cranial implants. Headpost and connector-chamber implants are used to allow head stabilization and to house connectors of chronically implanted electrodes, respectively. New methodWe present long-lasting, modular, cement-free headpost implants made of titanium that consist of two pieces: a baseplate and a top part. The baseplate is implanted first, covered by muscle and skin and allowed to heal and osseointegrate for several weeks to months. The percutaneous part is added in a second, brief surgery. Using a punch tool, a perfectly round skin cut is achieved providing a tight fit around the implant without any sutures. We describe the design, planning and production of manually bent and CNC-milled baseplates. We also developed a remote headposting technique that increases handling safety. Finally, we present a modular, footless connector chamber that is implanted in a similar two-step approach and achieves a minimized footprint on the skull. ResultsTwelve adult male macaques were successfully implanted with a headpost and one with the connector chamber. To date, we report no implant failure, great headpost stability and implant condition, in four cases even more than 9 years post-implantation. Comparison with existing methodsThe methods presented here build on several related previous methods and provide additional refinements to further increase implant longevity and handling safety. ConclusionsOptimized implants can remain stable and healthy for at least 9 years and thereby exceed the typical experiment durations. This minimizes implant-related complications and corrective surgeries and thereby significantly improves animal welfare.

Modeling the influence of the extrinsic musculature on phonation.

Neck muscles play important roles in various physiological tasks, including swallowing, head stabilization, and phonation. The mechanisms by which neck muscles influence phonation are not well understood, with conflicting reports on the change in fundamental frequency for ostensibly the same neck muscle activation scenarios. In this work, we introduce a reduced-order muscle-controlled vocal fold model, comprising both intrinsic muscle control and extrinsic muscle effects. The model predicts that when the neck muscles pull the thyroid cartilage in the superior-anterior direction (with a sufficiently large anterior component), inferior direction, or inferior-anterior direction, tension in the vocal folds increases, leading to fundamental frequency rise during sustained phonation. On the other hand, pulling in the superior direction, superior-posterior direction, or inferior-posterior direction (with a sufficiently large posterior component) tends to decrease vocal fold tension and phonation fundamental frequency. Varying the pulling force location alters the posture and phonation biomechanics, depending on the force direction. These findings suggest potential roles of particular neck muscles in modulating phonation fundamental frequency, with implications for vocal hyperfunction.

Roles for cerebellum and subsumption architecture in central pattern generation.

Within vertebrates, central pattern generators drive rhythmical behaviours, such as locomotion and ventilation. Their pattern generation is also influenced by sensory input and various forms of neuromodulation. These capabilities arose early in vertebrate evolution, preceding the evolution of the cerebellum in jawed vertebrates. This later evolution of the cerebellum is suggestive of subsumption architecture that adds functionality to a pre-existing network. From a central-pattern-generator perspective, what additional functionality might the cerebellum provide? The suggestion is that the adaptive filter capabilities of the cerebellum may be able to use error learning to appropriately repurpose pattern output. Examples may include head and eye stabilization during locomotion, song learning, and context-dependent alternation between learnt motor-control sequences.

U-shaped hip capsular incision: An easier way to do hip capsulorrhaphy in developmental dysplasia of the hip – Technical note

Developmental dysplasia of the hip (DDH) is one of the most common hip anomalies encountered in pediatric patients. Stabilization of the femoral head into the acetabulum is crucial for normal hip joint development. When surgical intervention is decided, open reduction is needed to remove any obstacle that hinders hip reduction. Capsulorraphy is an essential step for minimizing instability of the hip after reduction. The classic T-shaped capsular incision is done by two incisions: vertical limb parallel to femoral neck axis and a transverse one parallel to the inguinal ligament 5mm distally to proximal capsular attachment. The cumbersomeness of this technique was noticed in suturing of the resulted two flabs from this incision. So, the suggested U-shaped incision makes suturing of the capsule easier with multiple stitches.

Результаты исследований по обеспечению продольной устойчивости колёсного энергетического средства

To increase the traction properties of a wheeled power vehicle, one of the classic solutions is to implement the entire weight load that falls on its propellers. The most rational and applied method in tractor construction is the 4K4 wheel formula, which allows the maximum weight of the tractor to be realized in the coupling. This is especially true when performing transport work in conditions where the implementation of traction properties largely depends on the condition of the base on which the movement takes place. When moving a transport unit on a horizontal surface, various additional methods of increasing traction properties are also known and widely used, often used of which are the installation of additional loads and increasing the contact area of the mover with the base on which the power vehicle moves (twin wheels, half-track, etc.). At the same time, when performing transport operations on roads with a significant longitudinal slope (ascent or descent) these methods of increasing the coupling weight are not always effective due to the unstable nature of the movement. This article presents experimental studies to improve the longitudinal stability of a tractor-transport unit (TTA) by using an original towing-distributing device, which allows simultaneously adjusting the longitudinal stability of the energy vehicle by redistributing the coupling weight inherent in the design characteristics in the tractor-transport unit system during its movement. Keywords: HEADING STABILITY, STABILIZATION, TRACTOR-TRANSPORT UNIT, TOW-DISTRIBUTING DEVICE, EFFICIENCY

Study on Head Stabilization Control Strategy of Non-Wheeled Snake Robot Based on Inertial Sensor

In this paper, the head stabilization problem of the snake robot in planar motion is studied. When the snake robot performs a planar movement with an inchworm locomotion gait, the head controller of the snake robot swings up and down due to a fluctuation in the joint angle of the neck joint. However, the snake robot usually has a laser radar and other visual instruments on the head, and the swing of the head causes the visual instrument to fail to obtain external visual information normally, which affects the navigation and detection of the snake robot. In this paper, a head stabilization method for a snake robot in planar motion is proposed. The inertial sensor is used to obtain the direction parameters to control the swing of the head when the snake robot moves, and the effectiveness of the method is verified by a simulation and an experiment of the real robot.

A Pilot Experiment to Measure the Initial Mechanical Stability of the Femoral Head Implant in a Cadaveric Model of Osteonecrosis of Femoral Head Involving up to 50% of the Remaining Femoral Head

Background and Objectives: Currently, only patients with osteonecrosis of the femoral head (ONFH), who had bone defects involving 30-33.3% of the remaining femoral head, are indicated in hip resurfacing arthroplasty (HRA). In an experimental cadaver model of ONFH involving up to 50% of the remaining femoral head, the initial stability of the femoral head implant (FHI) at the interface between the implant and the remaining femoral head was measured. Materials and Methods: The ten specimens and the remaining ten served as the experimental group and the control group, respectively. We examined the degree of the displacement of the FHI, the bonding strength between the FHI and the retained bone and that at the interface between the FHI and bone cement. Results: Changes in the degree of displacement at the final phase from the initial phase were calculated as 0.089 ± 0.036 mm in the experimental group and 0.083 ± 0.056 mm in the control group. However, this difference reached no statistical significance (p = 0.7789). Overall, there was an increase in the degree of displacement due to the loading stress, with increased loading cycles in both groups. In cycles of up to 6000 times, there was a steep increase. After cycles of 8000 times, however, there was a gradual increase. Moreover, in cycles of up to 8000 times, there was an increase in the difference in the degree of displacement due to the loading stress between the two groups. After cycles of 8000 times, however, such difference remained almost unchanged. Conclusions: In conclusion, orthopedic surgeons could consider performing the HRA in patients with ONFH where the bone defects involved up to 50% of the remaining femoral head, without involving the femoral head-neck junction in the anterior and superior area of the femoral head. However, more evidence-based studies are warranted to justify our results.

Segmentation stability of human head and neck cancer medical images for radiotherapy applications under de-identification conditions: Benchmarking data sharing and artificial intelligence use-cases.

Demand for head and neck cancer (HNC) radiotherapy data in algorithmic development has prompted increased image dataset sharing. Medical images must comply with data protection requirements so that re-use is enabled without disclosing patient identifiers. Defacing, i.e., the removal of facial features from images, is often considered a reasonable compromise between data protection and re-usability for neuroimaging data. While defacing tools have been developed by the neuroimaging community, their acceptability for radiotherapy applications have not been explored. Therefore, this study systematically investigated the impact of available defacing algorithms on HNC organs at risk (OARs). A publicly available dataset of magnetic resonance imaging scans for 55 HNC patients with eight segmented OARs (bilateral submandibular glands, parotid glands, level II neck lymph nodes, level III neck lymph nodes) was utilized. Eight publicly available defacing algorithms were investigated: afni_refacer, DeepDefacer, defacer, fsl_deface, mask_face, mri_deface, pydeface, and quickshear. Using a subset of scans where defacing succeeded (N=29), a 5-fold cross-validation 3D U-net based OAR auto-segmentation model was utilized to perform two main experiments: 1.) comparing original and defaced data for training when evaluated on original data; 2.) using original data for training and comparing the model evaluation on original and defaced data. Models were primarily assessed using the Dice similarity coefficient (DSC). Most defacing methods were unable to produce any usable images for evaluation, while mask_face, fsl_deface, and pydeface were unable to remove the face for 29%, 18%, and 24% of subjects, respectively. When using the original data for evaluation, the composite OAR DSC was statistically higher (p ≤ 0.05) for the model trained with the original data with a DSC of 0.760 compared to the mask_face, fsl_deface, and pydeface models with DSCs of 0.742, 0.736, and 0.449, respectively. Moreover, the model trained with original data had decreased performance (p ≤ 0.05) when evaluated on the defaced data with DSCs of 0.673, 0.693, and 0.406 for mask_face, fsl_deface, and pydeface, respectively. Defacing algorithms may have a significant impact on HNC OAR auto-segmentation model training and testing. This work highlights the need for further development of HNC-specific image anonymization methods.

Effect of a Motion Artifact Correction System on Cone-Beam Computed Tomography Image Characteristics.

Determine the effect of the motion correction system on cone-beam computed tomography (CBCT) image quality parameters, artifacts, and contrast-to-noise ratio (CNR) using different motion settings. A customized phantom insert array was prepared using SEDENTEX CT IQ Phantom (Leeds Test Objects, Yorkshire, England) stabilized over a rotating electric turntable. Thirty baseline CBCT scans were acquired with standardized technique factors on the ProMax 3D (Planmeca, Helsinki, Finland) machine using combinations of different motion settings, including no motion, three- and six-degree motion, and with and without the use of a motion correction system. The standardized images were exported to ImageJ software. Image quality parameters, artifacts, and CNRvalues were evaluated and compared among the different acquisition settings. The use of the motion correction system algorithm compared with the different motion settings showed a statistically significant difference for all the parameters (p<0.05) except for artifact values for six-degree motion (p<0.07). The effect of different motion settings on the parameters was not statistically significant. The use of a motion correction system, a proprietary algorithm-based system incorporated in the ProMax 3D CBCT unit, deteriorates the image quality characteristics evaluated in this in vitro study, namely artifact value and CNR. Its use in clinical settings might be limited to situations where patient motion is expected and appropriate head stabilization is not possible due to age or disease.

PHYSICAL THERAPY IN CEREBRAL PALSY. CLINICAL ASPECTS. CASE REPORT

Cerebral palsy is a non-progressive functional disorder affecting the developing central nervous system, predominantly motor neurons, whose onset occurs during pregnancy, delivery or in the perinatal period. The incidence of cerebral palsy ranges from 1.5 to 2.5 per 1,000 live births. Brain damage due to periventricular leukomalacia and intraventricular haemorrhage in newborns is the most common cause of cerebral palsy. This paper presents the clinical picture of a girl with cerebral palsy. The child experienced perinatal hypoxia, which resulted in central nervous system damage and changes in the form of periventricular leukomalacia. Initially, she exhibited considerable axial hypotonia and upper and lower limb hypotonia. Rehabilitation was promptly initiated using a combination of multiple neurological methods, for example Vojta’s method, NDT Bobath therapy and PNF. The rehabilitation produced the desired effects, with the child achieving better motor control with respect to trunk and head stabilisation. She began using orthopaedic aids and undergoing verticalisation at the age of two years. She started experimental stem cell treatment in 2016. Currently her therapy takes place five times a week. The child is able to walk a short distance when she is being held by her arms. She acquires new skills and learns fast and has a wide vocabulary. She is motivated and determined to continue her rehabilitation in order to achieve her dream of walking with a walker by herself. Systematic motor rehabilitation contributed to an improvement in the physical fitness and everyday functioning of the child.

A Novel Approach for Dynamic Stable Clustering in VANET Using Deep Learning (LSTM) Model

Clustering in VANETs, which dynamically evolve into wireless networks, is difficult due to the networks' frequent disconnection and fast changing topology. The stability of the cluster head (CH) has a huge impact on the network's robustness and scalability. The overhead is decreased. The stable CH assures that intra- and inter-cluster communication is minimal. Because of these difficulties, the authors seek a CH selection technique based on a weighted combination of four variables: community neighborhood, quirkiness, befit factor, and trust. The stability of CH is influenced by the vehicle's speed, distance, velocity, and change in acceleration. These are considered for in the befit factor. Also, when changing the model, the precise location of the vehicle is critical. Thus, the predicted location is used to evaluate CH stability with the help of the Kalman filter. The results showed that the befit factor performed better than the latest developments. Because of the high speed of the vehicle, dynamic changes and frequent communication link breaks are unavoidable. In order to fully perceive issue, a graphing approach employed to assess the eccentricity then the communal neighborhood. Using Eigen gap heuristic, the link dependability is determined. Trust is the final important parameter that has not yet been taken into account in the weighted method. The trust levels are specifically being evaluated for the primary users using an adaptive spectrum sensing. Long short-term memory (LSTM), a deep recurrent learning network, used to train the likelihood of detection under diverse signal and noise situations. By using LSTM model, significantly decreased the false rate. The cluster head stability has improved for high traffic density, significantly improved according to the comparative analysis with the weighted and individual metrics. The efficiency of the network has also greatly increased in terms of throughput, packet delay, packet delay ratio, and energy consumption.