Search Results (71)

Accurate spot-centroid localization is fundamental for determining optical metrics such as modulation transfer function (MTF) and effective focal length (EFL). Conventional methods struggle under non-ideal conditions—asymmetric spots, high noise, and vibration—and mid-wave infrared (MWIR) vibration has received little attention. To address these gaps, we propose multi-scale Gaussian fitting with subpixel edge reconstruction (MSGF-SER), combining image pyramid fitting, Zernike-moment edge extraction, and adaptive eccentricity-weighted fusion. Validated on simulated spots with varying SNRs and experimental sequences (visible off-axis aberration, long-wave infrared (LWIR) high-noise, MWIR micro-vibration), MSGF-SER achieved a noise-free RMSE of 0.03 pixel and 0.84 pixel at 5 dB SNR. On real MWIR vibration sequences, the Y-direction standard deviation (STD) dropped to 0.098 pixel, and the trajectory displacement variance was more than an order of magnitude lower than that of conventional methods. MTF deviations remained within 0.01, and the deviation of the measured mean EFL from the nominal focal length was better than 0.05 mm, and the STD was below 0.02 mm. These results demonstrate that MSGF-SER substantially improves centroid localization accuracy, repeatability, and smoothness under challenging conditions, providing reliable support for high-precision optical system parameter measurement. Full article

Background: Spasticity significantly impairs functional recovery after severe acquired brain injury. Current management methods predominantly rely on pharmacological interventions, which can cause substantial side effects or require invasive medical procedures in refractory cases. Focal muscle vibration, a noninvasive technique that applies mechanical vibrations to muscle–tendon units and alters spinal and cortical excitability via proprioceptive pathways, has been effective in reducing spasticity in subjects with stroke. However, there is limited data to support focal muscle vibration as a viable option for improving functional recovery in patients with severe acquired brain injury. Objectives: To evaluate the clinical effects of adding focal muscle vibration to standard physiotherapy compared with standard physiotherapy alone in patients with severe acquired brain injury and spastic hypertonia. Methods: Twenty-four patients were randomly assigned to receive focal muscle vibration in addition to standard care (n = 12) or standard care alone (n = 12) for 3 weeks. Assessments were conducted at baseline, immediately after physiotherapy, and 3 weeks after physiotherapy. The outcomes assessed included the Modified Ashworth Scale, Disability Rating Scale, Modified Barthel Index, and three pain measures. Results: A significant reduction in spasticity was observed in the focal muscle vibration group, as indicated by the Modified Ashworth Scale scores (p = 0.014). Disability Rating Scale scores demonstrated a statistically significant decrease in disability ratings at the end of treatment (p = 0.002) and during the follow-up phase (p = 0.002). Between-group comparisons of change scores revealed a statistically significant improvement in disability ratings in the focal muscle vibration group during the treatment phase (p = 0.011). Significant functional gains were noted on the Disability Rating Scale, which persisted at the follow-up evaluation. Conclusions: Focal muscle vibration reduces muscle spasticity and improves functional status in patients with severe acquired brain injury during inpatient rehabilitation. Future studies with larger sample sizes, blinded assessments, and stratified randomization are needed to verify these findings and develop standardized treatment protocols for this underserved population. Full article

Seafloor hydrothermal systems at mid-ocean ridges are focal points for heat and matter exchange between the seawater and lithosphere. While seafloor seismographs (OBS) and pressure recorders (BPR) are standard for regional monitoring, achieving high-precision, vertical sub-surface data in complex hydrothermal terrains remains a significant technical objective. This study presents a novel in situ penetration probe designed for multi-parameter monitoring of marine hydrothermal vent areas. A key innovation of this work is its operational versatility and engineering efficiency: the probe is specifically designed for post-drilling deployment in boreholes, effectively utilizing existing coring sites to achieve direct coupling with the deep-seated crust, or for targeted placement via Remotely Operated Vehicles (ROVs). The device integrates a titanium-alloy conical tip and cylindrical chamber, housing tri-axial accelerometers and dual temperature-pressure sensors. Numerical simulations using the SST k-ω turbulence model and finite element analysis optimized the cone aperture and assessed fluid–structure stability under deep-sea conditions. Laboratory vibration tests and shallow-water sea trials validated the probe’s basic dynamic response, electromechanical integrity, and capability to acquire coupled environmental parameters. This compact, modular design provides a scalable and cost-effective framework for precise three-dimensional observation of sub-surface hydrothermal processes and deep-sea resource exploration. Full article

Cerebellar Ataxia, Neuropathy and Bilateral Vestibular Areflexia Syndrome (CANVAS) is a progressive multisystem disorder characterized by cerebellar ataxia, sensory neuropathy and bilateral vestibular failure. Although intensive rehabilitation is commonly recommended, the actual effectiveness and the most appropriate physiotherapeutic strategy for CANVAS have not been clearly established. Background/Objectives: To evaluate the effects of an integrated rehabilitation program combining neurocognitive therapeutic exercise and focal muscle vibration (FMV) on clinical and instrumental measures of gait, balance and postural stability in a CANVAS patient. Methods: A structured protocol consisting of neurocognitive therapeutic exercise and FMV was administered. Clinical measures included the Berg Balance Scale, Tinetti, SARA and SF-36. The instrumental evaluations included stabilometry and gait analysis. Results: The intervention produced improvements in balance scores associated with a reduction in fall risk. Stabilometry revealed reduction in oscillation area. Conclusions: FMV combined with neurocognitive therapeutic exercise may promote clinical and biomechanical improvements in CANVAS. Full article

Off-axis reflective telescopes are prone to component misalignment due to external environmental factors and mechanical vibrations. This misalignment introduces low-order aberrations, which severely degrade imaging quality. Thus, active misalignment correction is crucial for maintaining the imaging performance of off-axis reflective telescopes. Current computer-aided alignment technologies for optical systems mostly rely on wavefront sensors to acquire aberrations at multiple fixed fields of view (FOVs) or even the full FOV. This significantly increases system complexity and hinders practical engineering applications. To address this issue, this study first conducts sensitivity analysis of misaligned degrees of freedom (DOFs) using a mode truncation algorithm based on singular value decomposition (SVD). A compensation strategy is proposed to avoid the aberration coupling effect. Furthermore, two novel misalignment aberration compensation methods for off-axis reflective telescopes are presented. These methods require only a single focal spot image and eliminate the need for aberration detection and iterative calculations. One method directly solves component misalignment errors using a convolutional neural network (CNN) based on the system’s point spread function (PSF). To further improve compensation performance, an improved method fusing spot images and Zernike coefficients is proposed. In practical misalignment correction, both methods input a single acquired focal spot image into a well-trained model to obtain the misalignment compensation amount. Simulation experiments demonstrate that the improved method, which uses Zernike polynomial coefficients as an intermediate feature bridge, effectively establishes the mapping relationship between spot images and misalignment amounts. It achieves higher solution accuracy and better aberration compensation effect compared to the direct CNN method. This verifies the necessity of extracting Zernike polynomial coefficient features from spot images. Comparative experiments with the traditional sensitivity matrix method show that the two proposed methods outperform the sensitivity matrix method in aberration compensation accuracy over a large misalignment range. Comprehensive simulation results confirm the feasibility and effectiveness of the proposed methods. They overcome the limitations of existing methods, such as complex structure, high cost, and low efficiency, to a certain extent. Full article

Background and Objectives: Postural instability is a key feature of Parkinson’s disease (PD), contributing to disability and increased risk of falls. Pharmacological treatments are important, but it is necessary to integrate them with rehabilitation programs that provide benefits for gait and balance. Focal muscle vibration (fMV) has been proposed as a proprioceptive-oriented intervention to enhance postural control, but evidence in PD remains heterogeneous. This observational, retrospective, and controlled pilot study aimed to evaluate whether the integration of fMV into a standardized rehabilitation program provides additional benefits for balance, gait, and fall risk compared to standardized exercise alone in patients with PD. Materials and Methods: Medical records of 35 outpatients with Parkinson’s disease (Hoehn & Yahr stage II–III) were reviewed. All practiced a standardized rehabilitation exercise group program. Of these, 18 patients agreed to undergo fMV before the exercise sessions (fMV group); 17 patients did not accept fMV due to personal organizational reasons (EG) and were considered a retrospective control group. In detail, (i) the fMV group receivdc focal muscle vibration during the first three weeks in addition to a standardized group rehabilitation exercise program, and (ii) the EG underwent a standardized rehabilitation program only. Both groups then completed an identical 16-week standardized rehabilitation program. Functional outcomes were assessed at baseline (T0) and after one month (T1). Results: Groups were homogeneous at baseline. The fMV group showed significant improvements in SPPB (from 8.16 ± 1.6 to 10.2 ± 1.6 p < 0.001) in the Tinetti total (from 18.38 ± 3.2 to 21.5 ± 2.9 p < 0.05). Stabilometric analysis revealed a significant improvement in the Romberg Quotient in the fMV group (p < 0.005). Conclusions: A short time-limited fMV intervention may act as a sensory primer, enhancing the effects of a subsequent standardized rehabilitation program in PD. Full article

Functional ankle instability (FAI) is a common consequence of lateral ankle sprains, characterized by impaired sensorimotor control. While orthoses and localized vibration have shown individual benefits for FAI, their combined application in a wearable device has not been previously investigated. This pilot randomized trial compared the effects of a vibrotactile foot orthosis (VFO) and a vibrotactile ankle orthosis (VAO) on joint position sense (JPS) and postural control in individuals with FAI. Sixteen participants were randomized to receive either a VFO or a VAO, both delivering 30–50 Hz pulsed vibration in 20 min sessions, three times a week, for two weeks. Outcome measures included joint position sense (JPS) error (°), center of pressure (COP) velocity (mm/s), the Star Excursion Balance Test (SEBT), and the Six-Meter Hop Test (SMHT), which were assessed pre-intervention, immediately post-intervention, and after two weeks of use. The analysis showed a statistically significant interaction between time and intervention group for JPS error (p = 0.02, η² = 0.42). Specifically, the VFO group improved JPS significantly more than VAO at two weeks follow-up (MD = −1.75°, p = 0.005, d = −1.68). Both groups significantly reduced in anteroposterior COP velocity after two weeks (VFO: MD = 1, p = 0.003, d = 1.47; VAO: MD = 1.39, p ˂ 0.001, d = 2.05) with no between-group differences. No changes were observed in the SEBT or SMHT. Plantar-based vibrotactile stimulation was more effective than ankle-based stimulation in enhancing proprioceptive acuity in individuals with FAI. Both interventions improved static postural stability, supporting the potential of integrated vibrotactile orthoses in FAI rehabilitation. No major practical issues were reported during the intervention. Two participants experienced minor discomfort related to the electronic housing bulk in the first week, which was resolved by week two. No further complaints regarding device weight or usability were observed. Full article

As the core observation instrument of the China Space Station Telescope (CSST), the Survey Camera (SC) features large volume, heavy weight and high complexity, which poses considerable challenges to the development of its Main Structure (MST). Focusing on the design, optimization and verification of the MST, this study aims to meet the technical requirements of lightweight, high stiffness, high strength and mechanical stability, and provide high-precision Measurement References (MRs) for components such as the Focal Plane Array (FPA). The MST is an M55J carbon fiber/cyanate ester resin composite framework and incorporates titanium alloy inserts for thread machining. The thickness of carbon fiber plies was optimized using size optimization techniques to maximize structural efficiency. The carbon fiber plies and embedded parts along the structural force transmission path were strengthened to improve structural strength. A spherically mounted retroreflector (SMR)–cube mirror composite MR system was employed, along with a contact–non-contact integrated measurement scheme, achieving a position and angle measurement uncertainty of 5.26 μm/5.53″ (3σ). Through experimental verification, the final mass of the MST was controlled at 66.8 kg, and the fundamental frequency reached 120.6 Hz. After assessment via vibration tests and thermovacuum tests, the strength, mechanical stability, and thermal stability of the structure all met the mission requirements. Full article

Ultrasonic phased arrays have shown promise in generating virtual texture haptics through haptics feedback points. However, factors such as skin vibration speed, amplitude variations, acoustic interference, and energy loss can influence textural haptics. In this study, using Spatiotemporal Modulation (STM), virtual textures are produced through movement of the focal point. The acoustic field of the ultrasonic phased array as well as the stress and strain experienced by the skin during texture perception are simulated by numerical analysis. At the same time, psychophysical experiments are conducted by volunteers to evaluate these textures. The experimental results indicate that as the focal rotation frequency increases, regions closer to the center experience more significant shear wave effects, resulting in longer shear wave propagation, reduced tangential stress amplitude, and a larger affected area. Moreover, as the frequency of the shear wave interference shifts, it results in increasingly complex textural representations. Full article

Background/Objectives: Activities of daily living (ADL) are critical for independence after stroke, yet many survivors remain functionally limited. Vibration therapy (VT), including whole-body and focal modalities, has been proposed as an adjunct to enhance recovery, but effects on ADL remain unclear. This study aimed to evaluate the overall effectiveness of VT on ADL and to identify moderating factors. Methods: A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines. Thirteen controlled trials (12 RCTs, 1 nRCT) involving VT in stroke were included. Standardized mean differences (Hedges’ g) were synthesized using random-effects models. Meta-regression and subgroup analyses examined moderators such as session number, vibration parameters, stroke stage, and ADL subdomains. Risk of bias was assessed with RoB 2 and ROBINS-I. Results: VT produced a small but significant effect on ADL (Hedges’ g = 0.19; 95% CI: 0.06–0.33; p = 0.008), though significance was lost after adjustment for publication bias. Heterogeneity was moderate (I² = 34%). Session number was the only significant moderator (p = 0.045), explaining ~24% of variance, with the greatest benefit in the 13–24 session range (g = 0.34; 95% CI: 0.05–0.63). Subgroup analysis showed improvement in physical function/mobility (g = 0.32; p = 0.048), but not in self-care or quality-of-life outcomes. Other parameters were not significant moderators. Conclusions: VT confers modest benefits for ADL after stroke, particularly in mobility-related domains. Session number appears clinically important, with 13–24 sessions suggesting an optimal dose window. Full article

Background and Objectives: Parkinson’s disease is the second most common neurodegenerative disorder after Alzheimer’s disease, and its incidence increases with age, being particularly high in people over 70 years of age. For patients with this condition, medical rehabilitation can have a profound impact, helping to improve mobility, preserve functional autonomy, and enhance quality of life. Focal vibration stimulation is a promising, well-tolerated, and easy-to-apply method with potential to facilitate motor activity and support the motor learning process, making it also useful in gait reeducation for patients with various neurological conditions. This systematic review aims to analyze the existing scientific evidence on the effectiveness of focal muscle vibration therapy in managing symptoms of Parkinson’s disease. Materials and Methods: This systematic review of the literature was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the protocol was registered in PROSPERO under the protocol registration number CRD420251120737. Searches were conducted in five databases (PubMed, PEDro, ScienceDirect, Cochrane Library, Web of Science). The selection criteria targeted original clinical studies, published in English between 2010 and the present, that investigated focal muscle vibration therapy in patients with Parkinson’s disease and were fully available, excluding review papers, meta-analyses, books, and articles inaccessible in full text. Version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2) was used to assess the quality of the included studies. Results: The results of the studies were interpreted individually for each study, and the main information was synthesized in a comparative table to facilitate analysis. The final analysis included five studies that investigated the effects of focal muscle vibration in patients with Parkinson’s disease. The results suggest that this form of stimulation may offer benefits for patients with gait disorders, improving balance and stability. Among the study’s limitations are the small number of included articles (n = 5) and the restriction to English-language publications, which may limit the applicability of the results. Conclusions: Given the promising results, focal muscle vibration therapy could represent a useful option in the management of Parkinson’s disease. Integrating this method into rehabilitation plans could bring significant functional benefits, but further studies are needed to confirm its long-term effectiveness and to establish standardized application protocols. No external funding was received for the conduct of this review. Full article

Multiple sclerosis (MS) is a chronic disease of the central nervous system that significantly impairs gait and mobility, contributing to a high risk of falls, reduced participation in daily activities, and diminished quality of life. Despite existing interventions such as exercise programs and pharmacological treatments, challenges such as fatigue, pain, and limited accessibility underscore the need for alternative therapies. Focal vibration therapy (FVT) has shown promise in improving gait, reducing spasticity, and enhancing mobility in people with MS (PwMS). However, further research is required to evaluate its long-term feasibility and optimize its parameters. This study examined the feasibility and preliminary efficacy of a home-based four-week wearable FVT device on gait and explored how FVT parameters impact gait and mobility outcomes. In this pilot double-blind randomized controlled trial, 22 PwMS were randomized into control and vibration groups (four FVT groups with varying vibration intensities/durations). Participants wore Myovolt^® vibrators on distal quadricep muscles near the rectus femoris insertion (approximately 2 cm from the medial edge of the patella), gastrocnemius/soleus, and tibialis anterior muscles (10 min/muscle, 3 days/week, 4 weeks). Feasibility was evaluated via adherence and satisfaction (QUEST 2.0, interviews). Gait (3D motion analysis) and mobility (T25FW) were assessed at baseline and post-intervention. Data were analyzed using descriptive/inferential statistics and thematic analysis. Of 22 participants, 17 completed post-intervention (16 intervention, 1 control). Wearable FVT showed promising feasibility, with high satisfaction despite minor adjustability issues. Intervention groups improved gait speed (p = 0.014), stride length (p = 0.004), and ankle angle (p = 0.043), but T25FW was unchanged (p > 0.05). High-intensity FVT enhanced knee/hip moments. This study’s results support the feasibility of wearable FVT for home-based management of mobility symptoms in MS with high participant satisfaction and acceptance. Notable gains in gait parameters suggest FVT’s potential to enhance neuromuscular control and proprioception but may be insufficient to lead to mobility improvements. Subgroup analyses highlighted the impact of vibration intensity and duration on knee joint mechanics, emphasizing the need for personalized dosing strategies. Challenges included participant retention in the control group and burdensome biomechanical assessments, which will be addressed in future studies through improved sham devices and a larger sample size. Full article

Herein, we report a USB-powered VR-HMD prototype integrated with our 33 mm aperture varifocal liquid lenses and electronic drive components, all assembled in a conventional VR-HMD form-factor. In this volumetric-display-based VR system, a sequence of virtual images are rapidly flash-projected at different plane depths in front of the observer and are synchronized with the correct accommodations provided by the varifocal lenses for depth-matched focusing at chosen sweep frequency. This projection mechanism aids in resolving the VAC that is present in conventional fixed-depth VR. Additionally, this system can address refractive error corrections like myopia and hyperopia for prescription users and do not require any eye-tracking systems. We experimentally demonstrate these lenses can vibrate up to frequencies approaching 100 Hz and report the frequency response of the varifocal lenses and their focal characteristics in real time as a function of the drive frequency. When integrated with the prototype’s 120 fps VR display system, these lenses produce a net diopter change of 2.3 D at a sweep frequency of 45 Hz while operating at ~70% of its maximum actuation voltage. The components add a total weight of around 50 g to the off-the-shelf VR set, making it a cost-effective but lightweight minimal solution. Full article

Background/Objectives: Spasticity is a common and disabling sequela of stroke that limits voluntary movement and functional recovery. Vibration therapy (VT) has been proposed as a non-invasive neuromodulatory intervention, but the existing studies report inconsistent outcomes due to methodological heterogeneity. This study aimed to evaluate the overall effectiveness of VT in reducing post-stroke spasticity and to identify optimal stimulation parameters via meta-analytic and meta-regression approaches. Methods: A systematic review and meta-analysis were conducted following the PRISMA 2020 guidelines. Standardized effect sizes (Hedges’ g) were calculated based on the within-group pre–post changes and compared across the groups. Meta-regression and subgroup analyses explored seven potential moderators, including the vibration frequency, amplitude, and time since stroke onset. Results: Thirteen randomized controlled trials (RCTs) involving whole-body or focal vibration interventions in stroke populations were included. Vibration therapy significantly reduced spasticity, yielding a moderate overall effect size (Hedges’ g = −0.50; 95% CI: −0.65 to −0.34; p < 0.001). The greatest treatment effects were observed when VT was applied during the late subacute to early chronic phase (6–12 months post-stroke), with low-frequency (<20 Hz) and low-amplitude (≤0.5 mm) stimulation. The frequency, amplitude, and stroke onset emerged as significant moderators (p < 0.05). Conclusions: Vibration therapy is an effective and clinically meaningful intervention for post-stroke spasticity, particularly when delivered with low-intensity parameters during the optimal recovery window. These findings support the development of individualized VT protocols and provide evidence to guide future rehabilitation strategies. Full article

Background and Objective: Fatigue represents a hallmark symptom in Multiple Sclerosis (MS), but its diagnosis and clinical evaluation is difficult because it is described as a subjective feeling of exhausted physical and mental sensation. Studies have also shown that approaches based on assisted therapies and robotics, as well as the use of vibration, which are used to improve sensory integration, reduce fatigue. The primary outcome in this study is to evaluate the effects of the application of focal vibrations on the reduction in fatigue, muscle strength, and endurance in MS patients with moderate disability. The secondary outcome is to assess the effects on quality of life, cognitive status, and mood. Methods: We enrolled 40 MS patients. The study was designed as a parallel randomized controlled trial: 20 patients were assigned to the experimental group (EG), who received vibration training, and 20 to the control group (CG), who received traditional physical exercise. Results: We found significant differences in the EG in fatigue, motor, and cognitive outcome and improvement of some aspects of quality of life (QoL). There are correlations between perceived multidimensional fatigue and cadence, step length, and health quality of life composite. Conclusions: Our study demonstrated the potential effectiveness of vibration training in balance, walking endurance, and reduction in the risk of falls in patients with Multiple Sclerosis. In addition, we added evidence about fatigue, non-motor outcomes, in particular promoting mental and physical QoL and individual life satisfaction. The name of the registry is clinicaltrial.gov; the number of registration id NCT05783999; and the date of registration is 14 March 2023. Full article