Fine Wire Research Articles

Study on Fast Temporal Prediction Method of Flame Propagation Velocity in Methane Gas Deflagration Experiment Based on Neural Network

To address the challenges of high experimental costs, complexity, and time consumption associated with pre-mixed combustible gas deflagration experiments under semi-open space obstacle conditions, a rapid temporal prediction method for flame propagation velocity based on Ranger-GRU neural networks is proposed. The deflagration experiment data are employed as the training dataset for the neural network, with the coefficient of determination (R2) and mean squared error (MSE) used as evaluation metrics to assess the predictive performance of the network. First, 108 sets of pre-mixed methane gas deflagration experiments were conducted, varying obstacle parameters to investigate methane deflagration mechanisms under different conditions. The experimental results demonstrate that obstacle-to-ignition source distance, obstacle shape, obstacle length, obstacle quantity, and thick and fine wire mesh obstacles all significantly influence flame propagation velocity. Subsequently, the GRU neural network was trained, and different activation functions (Sigmoid, Relu, PReLU) and optimizers (Lookahead, RAdam, Adam, Ranger) were incorporated into the backpropagation updating process of the network. The training results show that the Ranger-GRU neural network based on the PReLU activation function achieves the highest mean R2 value of 0.96 and the lowest mean MSE value of 7.16759. Therefore, the Ranger-GRU neural network with PReLU activation function can be a viable rapid prediction method for flame propagation velocity in pre-mixed methane gas deflagration experiments under semi-open space obstacle conditions.

Investigation on the microstructure, mechanical properties and chlorine resistance of fine aluminum alloy wires

Wire bonding is a fundamental and mature technology in semiconductor packaging process, primarily using materials such as gold, silver, aluminum, and copper for the wires. To address application limitations of aluminum wires, such as low electromigration resistance and limited ductility, techniques including to enhance alloying (with Zn and Si), heat treatment, and surface treatment are employed to enhance the performance of aluminum alloy wires and broaden their application value. This study selects Al-3Zn-0.3Si (AZS303) and Al-7Zn-0.3Si (AZS703), with AZS303 undergoing gold plating to produce AC-AZS303 wires. Various high-temperature heat treatments are applied, verifying that under 400 °C conditions, the AZS series aluminum alloy wires exhibit grain growth and form single-crystal equiaxed grain structures, resulting in stable mechanical properties and excellent electrical performance. Additionally, the AC-AZS303 wires optimize resistance values through gold layer diffusion induced by the electrothermal effect.Chlorine experiments indicates that the gold plating on AC-AZS303 can't enhance the aluminum wire's resistance to chlorine corrosion. However, the alloying effect of zine and silicon elements imparts excellent chlorine corrosion resistance to the Al-Zn-Si wires. This study of bonding properties examines the bond strength and observes the bonded area of Al-Zn-Si wires after bonding. It is noted that the H400-AZS303 wire exhibits the best bond strength and bonding area, demonstrating good bonding with the substrate.

Spatial and Temporal Freezing Dynamics of Leaves Revealed by Time-Lapse Imaging.

Freezing air temperatures kill most leaves, yet the leaves of some species can survive these events. Tracking the temporal and spatial dynamics of freezing remains an impediment to characterizing frost tolerance. Here we deploye time-lapse imaging and image subtraction analysis, coupled with fine wire thermocouples, to discern the in situ spatial dynamics of freezing and thawing. Our method of analysis of pixel brightness reveals that ice formation in leaves exposed to natural frosts initiates in mesophyll before spreading to veins, and that while ex situ xylem sap freezes near 0°C, in situ xylem sap has a freezing point of -2°C in our model freezing-resistant species of Lonicera. Photosynthetic rates in leaves that have been exposed to a rapid freeze or thaw do not recover, but leaves exposed to a slow, natural freezing and thawing to -10°C do recover. Using this method, we are able to quantify the spatial formation and timing of freezing events in leaves, and suggest that in situ and ex situ freezing points for xylem sap can differ by more than 4°C depending on the rate of temperature decline.

Experimental study on temperature distribution of double-layer solid cylinder under local heating source

Abstract Heating equipment is widely used in production and life, the transient temperature of the heated object reflects the effect of heating equipment, but also an important basis for the design of heating equipment. In the internal temperature measurement of micro heating equipment, some of the temperature measurement instruments are large in size, which makes it difficult to realize precision measurement, and the use of infrared measurement, laser temperature measurement and other methods cannot be used to accurately measure the temperature of the internal points of the material without destroying the material and equipment at the same time. In this study, based on the thermocouple temperature measurement technology and considering the problem of fragility and breakage caused by the small diameter of very fine thermocouple wires, a multi-point temperature synchronization measurement platform is constructed to realize the precise measurement of the temperature at multiple points inside the micro-heating element. Transient temperatures were measured at different locations of a water-containing porous medium inside a 15 mm long heating element under static heating and dynamic suction conditions in the case study. The results show that moisture and suction have a significant effect on the temperature inside the porous media layer. During the suction process, the temperature drop near the suction opening was larger, and the temperature drop near the wall was about 47% of the temperature drop inside. This study is a guide to the design of heating structures for vacuum drying equipment, electrically heated atomization systems and other micro-miniature heating equipment.

On the mitigation of landing gear noise using a solid fairing and a dense wire mesh

A solid fairing and a wire-mesh fairing consisting of very fine wires and pores are numerically and experimentally investigated for the mitigation of landing gear noise. A slightly modified LAGOON landing gear and two configurations, one equipped with a solid fairing and the other with a wire-mesh fairing, are numerically simulated using the Improved Delayed Detached-Eddy Simulation (IDDES) in combination with the Ffowcs Williams and Hawkings (FW-H) analogy. Instead of resolving the detailed flow features through the wire mesh, a recently proposed numerical model is used to represent the effect of the wire-mesh fairing. The simulated flow fields and the far-field noise spectra are validated against the experiments conducted in an anechoic wind tunnel. The superiority of the recently proposed wire-mesh model over a classical wire-mesh model in modelling both the aerodynamic and aeroacoustic effects of the wire mesh is demonstrated. Results also show that the dense wire-mesh fairing functions very similarly to the solid fairing and that significant noise can be reduced through the installation of a solid fairing or a wire-mesh fairing upstream of the landing gears. For the baseline landing gear, the torque link and the brakes are identified noise sources. With the aerodynamic penalty of a 50% increase in drag, both fairings mitigate the pressure fluctuation on the torque link and brakes, resulting in the reduction of surface noise sources. The noise directivity shows that a solid fairing or a dense wire-mesh fairing contributes to a noise reduction of 4-6 dB in all radial directions. The findings in this study pave the way for the low-noise design of aircraft landing gears.

Applying SPH-DEM theory to the motion of particulate solid-liquid flow on continuous screening

Challenges in current research on fine mesh wet screening (≥50 mesh) include representing fine wire boundaries, contentious porous media handling, and low computational efficiency. To address these challenges, this study employs an averaged SPH-DEM method for modeling solid-liquid flow on screen. It integrates the Symplectic scheme and quaternion method to enhance computational accuracy and scalability. The fine wire boundaries are discretized into spheres to facilitate Hertz contact of DEM particles, and a novel screen aperture-fluid resistance model is introduced to calculate the resistance exerted on SPH particles by screen surface. The simulation results of dam break and periodic screening exhibit robust consistency with experimental data and other models, effectively validating the feasibility and accuracy of this methodology. Moreover, simulations of continuous screening using a 0.2 mm wire demonstrate that liquid enhances particle passage, further substantiating the practical viability of employing this model for simulating fine mesh wet screening.

The Production of Three-Dimensional Metal Objects Using Oscillatory-Strain-Assisted Fine Wire Shaping and Joining.

Material shaping and joining are the two fundamental processes that lie at the core of many forms of metal manufacturing techniques, including additive manufacturing. Current metal additive manufacturing processes such as laser/e-beam powder bed fusion and Directed Energy Deposition predominantly use heat and subsequent melt-fusion and solidification to achieve shaping and joining. The energy efficiency of these processes is severely limited due to energy conversion losses before energy is delivered at the point of melt-fusion for shaping and joining, and due to losses through heat transfer to the surrounding environment. This manuscript demonstrates that by using the physical phenomenon of lowered yield stress of metals and enhanced diffusion in the presence of low amplitude high frequency oscillatory strain, metal shaping and joining can be performed in an energy-efficient way. The two performed simultaneously enable a metal additive manufacturing process, namely Resonance-Assisted Deposition (RAD), that has several unique capabilities, like the ability to print net-shape components from hard-to-weld alloys like Al6061 and the ability to print components with a very high aspect ratio. In this study, we show this process's capabilities by printing solid components using aluminum-based metal alloys.

Flutter characteristics of a sheet with an elastic support in three-dimensional uniform flow

In the manufacturing processes of thin flexible plates (sheets) such as polarizing films, the flutter can be caused to the sheets due to the interaction between the motion of the sheets and fluid flow. Then, the flutter can cause serious damage to the sheets, leading to the wrinkles and scratches. Thus, it is crucial to investigate a detailed characteristics and excitation mechanism of the flutter. In the present study, a detailed flutter characteristics and excitation mechanism of a rectangular sheet with an elastic support is investigated. The elastic support is implemented using a fine flexible wire. The influence of bending stiffness of the support section on the flutter velocity and frequency is clarified through wind-tunnel experiments and numerical analysis. Moreover, the work done by the fluid force on the sheet surface was determined.The flutter velocity and frequency drastically decrease owing to decrease in bending stiffness of the support section regardless of the aspect and mass ratio. Then, the positive work region around the leading edge of the sheet expands owing to the large-amplitude oscillation around the leading edge. The expansion of positive work region owing to a large-amplitude oscillation around the leading edge of the sheet destabilizes the system.

The opioid buprenorphine differentially affects laryngeal and tracheal sensory receptors

The current study aims to determine mechanisms of impaired airway protection following opioid administration. Experiments were performed on N=10 anesthetized male Sprague Dawley rats. Bipolar fine wire electromyogram (EMG) wires were implanted in various muscles to evaluate breathing and swallowing. Swallows were evoked by activation of laryngeal touch receptors, tracheal mechanoreceptors, and tracheobronchial c-fibers as follows: A) Light laryngeal touch with a Von Frey filament; B) Rapid inflation of a balloon in the proximal trachea; C) Stimulation of the carina with thin polyethylene tubing. Trials were performed before and after buprenorphine administration (0.01 mg/kg IV). 2-Way ANOVA detected an effect of drug [F(1,16)=40.6, p<0.0001] and stimulus [F(2,19)=4.2, p=0.03] on swallow frequency. Post hoc comparisons showed that after buprenorphine administration, laryngeal touch evoked significantly more swallows (10±4) than tracheal distension (1±1, p=0.03) or carina stimulation (1±3, p=0.04), suggesting that laryngeal sensation is critical for airway protection following opioid administration. This has implications for prevention of aspiration pneumonia in populations that have an increased risk of reduced laryngeal sensation and are commonly treated with opioids (e.g., post-surgical, critically ill, and/or head and neck cancer patients). Research reported in this abstract was supported by NIH grants NS110169, HL155721, HL163008, HD110951, NS097781, OT20D001983, the Craig H. Neilsen Foundation Pilot Research Grant 546714, Kentucky Spinal Cord and Head Injury Research Trust, and the Commonwealth of Kentucky Challenge for Excellence. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

AN IN VITRO STUDY EXAMINING WIRE TENSION IN FINE WIRE CIRCULAR EXTERNAL FIXATION CONSTRUCTS

IntroductionIlizarov fixators are reliant on tensioned fine wires for stability. The tension in the wires is generated using specific tensioning devices. Loss of wire tension over time may lead of loss a stability and complications. A series of in vitro experiments were undertaken to explore wire tensioner accuracy, the impact of fixation bolt torque and initial tension on loss of tension in ilizarov constructs under static and dynamic loads.Materials & MethodsMedical grade materials were applied to a synthetic bone analogue using surgical instruments in all experiments. Bolt torque was fixed at 6, 10 or 14 Nm using a torque limiting wrench. Wire tension was assessed using a strain measurement bridge. Wires were tensioned to 90, 110 and 130kg as measured by a commercial dynamometric tensioner. Static and dynamic testing was undertaken using an instron testing machine. Cyclical loads from 50–750N were applied for 5000 cycles.ResultsActual wire tension was approximately 15% less than indicated by the tensioner device. Using fixation bolt torques of 10Nm and 14Nm achieved final wire tensions of around 60% and 80% of that applied at 90 and 130kg of applied tension. Static load testing demonstrated self stiffening to similar levels in all pre-tensions. Dynamic testing demonstrated significant loss of tension, most of which occured in the first 3 cycles, inversely proportional to the tension initially applied.ConclusionsThese experiments provides insight into the effect of initially applied wire tension on Illizarov mechanical performance. It is important surgeons understand how the different ways that these devices are applied affects mechanical performance. Further research examining what factors affect performance across different manufacturers equipment would therefore be relevant, alongside the development of novel fixation methods to reduce wire slippage and the further development of equipment for clinical use.

MIDFOOT CHARCOT ARTHROPATHY: BUTT FRAME CORRECTION FOLLOWED BY BEAMING FOR SEVERE DEFORMITY

IntroductionCharcot neuroarthropathy is a limb threatening condition and the optimal surgical strategy for limb salvage in gross foot deformity remains unclear. We present our experience of using fine wire frames to correct severe midfoot deformity, followed by internal beaming to maintain the correction.Materials and MethodsNine patients underwent this treatment between 2020–2023. Initial deformity correction by Ilizarov or hexapod butt frame was followed by internal beaming with a mean follow up of 11 months. A retrospective analysis of radiographs and electronic records was performed. Meary's angle, calcaneal pitch, cuboid height, hindfoot midfoot angle and AP Meary's angle were compared throughout treatment. Complications, length of stay and the number of operations are also described.ResultsMean age was 53 years (range:40–59). Mean frame duration was 3.3 months before conversion to beaming. Prior frame-assisted deformity correction resulted in consistently improved radiological parameters. Varying degrees of subsequent collapse were universal, but 5 patients still regained mobility and a stable, plantargrade, ulcer-free foot. Complications were common, including hardware migration (N=6,66%), breakage (N=2,22%), loosening (N=3,33%), infection (N=4,44%), 1 amputation and an unscheduled reoperation rate of 55%. Mean cumulative length of stay was 42 days.ConclusionsAggressive deformity correction and internal fixation for Charcot arthropathy requires strategic and individualised care plans. Complications are expected for each patient. Patients must understand this is a limb salvage scenario. This management strategy is resource heavy and requires timely interventions at each stage with a well-structured MDT delivering care. The departmental learning points are to be discussed.

Experimental evaluation of flow field design on open-cathode proton exchange membrane fuel cells (PEMFC) short stack consisting of three cells

The promising nature of proton exchange membrane fuel cell stacks in energy conversion has sparked the need to improve the cell components for improved performance, durability, sustainability, and cost competitiveness. This work presents the pros and cons of different flow field designs concluded from an open-cathode short stack, composed of three cells. The flow fields consist of 3D fine mesh, fine wire mesh, metal foam, and conventional straight channels. The results presented in this study show that the fine wire mesh gives better performance, both when integrated, and not integrated with straight channels. It is followed by the 3D fine mesh, straight channels, and metal foam. The different performance improvements are caused by the various flow fields influencing flow rate, current conductivity, and temperature increment. Water management seems to be a significant factor in the performance variation. This is presented by the IV curves, which show a dramatic discrepancy over the concentration loss region. The straight channels integrated with fine wire mesh cell have the highest degradation rate at a constant voltage of 1.7 V, even though it reached a constant value after 1.4 h of operation.

Breakdown dynamics and instability of underwater metallic aerosol bubble atomized by electrical explosion

This study delves into the electrophysical processes and intricate fluid dynamics of an electrical-explosion-induced bubble in water. A fine copper wire is heated up and exploded to dense metallic aerosol (vapor–drop mixture) via a μs-timescale 10 kA current pulse, crossing a wide range of the density–temperature parametric space. High-speed photography along with discharge diagnostics reveals two modes for plasma development (restrike) inside explosion products: gas discharge and volume ionization. Experimental results indicate the metal–insulator transition of metal can easily throttle down circuit current at a moderate degree of vaporization, resulting in a free-expanding metallic aerosol in the presence of a quasi-direct current axial electric field of kV/cm level. After dozens of μs, an anode-directed, “ionization wave” is observed inside the aerosol bubble, propagating with a speed of 3–10 km/s. Remarkably, adjustments in the electric field permit the observation of cathode-directed discharge development. Increasing the charging voltage or wire diameter promotes the overheating degree, accompanied by partial ionized striation of electro-thermal instability. With sufficient high overheating of the wire (ξ > 1), the gas discharge disappears and restrike is dominated by volume ionization.

Optically transparent meta-window for satellite signal reception

Glass window, as a widely used functional unit in architecture and transportation, is a visual bridge connecting the indoor and outdoor world, and also a wireless communication window that is easily overlooked. In order to explore additional possibilities of glass window in the field of wireless communication, we propose to use meta-windows combining traditional window glass with metasurface to manipulate electromagnetic waves in microwave frequency band while ensuring its good optical transparency. Here, the meta-window is constructed by rotated meta-atoms made of fine copper wires printed on glasses to minimize the loss of optical transparency. As a proof of concept, we design and fabricate an optically transparent focusing meta-window for receiving satellite signals. In the experiment of television reception from the ChinaSat 9 satellite, stable high-definition video reception has been verified. The meta-windows endow traditional glass windows with new capabilities in electromagnetic modulations, which may be applied in 5G/6G communications, satellite ground integrations, and smart cities.

Micro CT Analysis and 3D Modelling of Fluid Permeability of Talar Subchondral Bone After Marrow Stimulation Techniques Demonstrates Superiority of Nanofracture Over Microfracture and Fine Wire Drilling

Introduction/Purpose: The aim was to compare different bone marrow stimulation techniques and consequent fluid permeability of subchondral bone by assessing flow of radiopaque contrast agent using μCT image analysis and 3D modelling. Methods: Donated human tali specimens (n=12) were prepared by creating separate matched 10mm diameter chondral defects in each. Each defect underwent one of three surgical techniques: fine wire drilling, nanofracture or microfracture, addition of radiopaque contrast agent and imaged using a clinical μCT scanner. Using Slicer 3D software each μCT scan was segmented for bone and contrast agent regions in each surgical site of each sample. Each site was resolved into a cylinder and the ratio of segmented pixels of contrast agent against bone calculated. Results: μCT analysis indicated that 8/12 nanofracture regions demonstrated enhanced flow of contrast to at least the depth of the fracture site, with some additional lateral flow also observed. 8/12 microfracture regions demonstrated flow of contrast agent localised to the fracture site and preferential flow laterally. Only 1/12 samples with fine wire drilling demonstrated any fluid flow. In 11/12 samples that showed no permeation of contrast agent, a residual layer of contrast agent on the chondral surface was seen. Segmentation of each sample site showed a significant increase (n=12, p< 0.05) in fluid flow of the contrast agent in the nanofracture sites (11%) compared to microfracture (5%) and fine wire drilling (2%). Conclusion: Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture allowed some fluid flow, but only confined to the immediate area around the fracture site, while fine wire drilling allows very little fluid flow at all. This study suggests that nanofracture should perhaps be the preferred mode of subchondral bone preparation for osteochondral lesions of the talus. Quantitative measurement of contrast permeability into talar subchondral bone by technique Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling

Enhanced Electrical Conductivity of Graphene-Incorporated Copper Wire and its Performances on Coaxial Cable Application at Sub 6 GHz

Intensive global research is focused on advanced conductive materials to meet the electrical requirements of the telecommunication and power industry. The primary aim is to enhance electrical conductivity, resulting of improved current-carrying capacity and reduced energy loss during transmission. Copper and its composites are vital for power transmission and telecommunications due to their electrical, thermal, and mechanical qualities. However, current methods have drawbacks, such as compromised conductivity with alloying. Graphene, an extraordinary carbon allotrope with exceptional properties and high conductivity, offers promising opportunities for the development of superior materials; such as graphene-incorporated copper (GrCu). The incorporation of graphene into copper wire holds significant potential for various industries, including electronics, energy transmission, and telecommunications, where high conductivity and reliability are paramount. This study investigates GrCu characteristics through mixing graphene and copper, vacuum melting, fine copper wire drawing, and GrCu coaxial cable manufacturing. Graphene infusion enhances conductivity and mechanical properties, altering microstructure and inducing twin boundaries in copper grains. Graphene's disruption during wire drawing triggers this effect, elevating wire conductivity to 103.5% by IACS. GrCu coaxial cable demonstrates performance coherence with HFSS simulation up to 6 GHz. Graphene's inclusion offers tailored material properties. Ongoing research promises further optimization and advancement of graphene-copper composites, paving the way for novel technological progress.

Terahertz structured deep-subwavelength plasmonic grating metasurface for manipulating polarization-dependent coupling response

The complex electromagnetic anisotropy of terahertz (THz) metasurfaces with geometric symmetry breaking has attracted extensive attention. Typical effects arise from the coupling of polarization responses in orthogonal directions of various components of the metasurface structure, such as the electromagnetically induced transparency (EIT) effect. However, it is a challenge to precisely control or perfectly avoid the polarization-dependent coupling responses. In this work, deep-subwavelength plasmonic gratings (PGs) with a fine wire width of 1 μm at the order of deep subwavelengths of 1/100 THz wave are fabricated by electron beam lithography, and these wire gratings are graphically designed as a C-shaped metasurface pattern with a period of 100 μm in sub-wavelength scale. The complete anisotropic response in the single-oriented PG metasurface is demonstrated by both simulation and experiments, where the polarization-dependent coupling effect is eliminated. More interestingly, the hybrid-oriented PG metasurface exhibits narrowband and wideband EIT effects in the x and y polarization directions with the maximum polarization extinction ratio of 20 dB, respectively, indicating this mechanism can realize more flexible manipulation of polarization-dependent coupling. This patterned deep-subwavelength PG provides a new structure and mechanism for excitation, regulation, and restriction of polarization-dependent mode coupling, and has important applications in THz spectroscopic detection, polarization imaging, and wireless communication.

High Speed Transmission Characteristics on Glass Based Interposers

Interposers for system in package will became more and more important for advanced electronic systems. As the industry moves toward HPC (High Performance Computing) for huge data transmission with low power consumption. The major engineering requirements for HPC application are highdensity, high speed data transmission, low loss, precision manufacturing and low cost. On the 2.5D heterogenous package structure, key technology is fine wiring connected with CPU chip and HBM chips. The fine wires needed high speed transmission. This paper presents the demonstration of Glass-based twin type interposers, Glass interposer with fine pitch metalized through via and RDL interposer with low loss dielectrics on Glass carrier. We compare twin types of Interposes fabrication process capability with panel size format 300x400mm. Finally, we compare the transmission characteristics using eye diagram for heterogenous integration application. Glass Interposer has low loss glass via, it is effective vertical interconnection. RDL interposer has low loss dielectric layers, excellent transmission characteristics obtained on fine pitch trace area.

PLIF Flame Study on the Qualitative and Quantitative Measurement of OH Species for Conventional and Alternative Jet Fuels; Experimental and Theoretical Investigations

ABSTRACT The hydroxyl molecule is one of the most important intermediate species in the chemistry of combustion processes and plays an important role in the chemical reactions of a hydrocarbon-air flame. However, investigation on a laser-based quantitative measurement of OH in heavy liquid hydrocarbon flames remains very scarce. Thus, in this study, OH radicals were measured qualitatively with the aid of planar laser-induced fluorescence in atmospheric pressure studies of burner stabilized laminar flames of kerosene and alcohol-to-jet (ATJ) fuel. These qualitative profiles were then put on a quantitative basis by analysis of the impact of temperature on the Boltzmann distribution of OH over the ground electronic state rotational energy levels and the use of a simple methane reference flame and its modeling using ANSYS Chemkin-Pro. The quantitative profiles in turn were used to validate the developed chemical kinetic mechanisms of kerosene and ATJ combustion. An experimental apparatus has been developed to investigate the temperature profile and the OH relative amounts of kerosene and ATJ laminar flames in an optimized premixed flat flame burner, under three different air/fuel ratio conditions. Fine wire type thermocouples were applied to provide reliable temperature profiles for the fuel flames. In general, reasonable agreement were observed between the experimental OH results and the simulations for the target fuel flames in the case of kerosene, while a higher peak value of OH was predicted in the ATJ model output compared to the PLIF derived data.

Short term effects of contralateral tendon vibration on motor unit discharge rate variability and force steadiness in people with Parkinson's disease.

Vibration of one limb affects motor performance of the contralateral limb, and this may have clinical implications for people with lateralized motor impairments through vibration-induced increase in cortical activation, descending neural drive, or spinal excitability. The objective of this study was to evaluate the effects of acute biceps brachii tendon vibration on force steadiness and motor unit activity in the contralateral limb of persons with Parkinson's disease. Ten participants with mild to moderate Parkinson's disease severity performed a ramp, hold and de-ramp isometric elbow flexion at 5% of maximum voluntary contraction with the more-affected arm while vibration was applied to the distal biceps brachii tendon on the contralateral, less-affected arm. Using intramuscular fine wire electrodes, 33 MUs in the biceps brachii were recorded across three conditions (baseline, vibration, and post-vibration). Motor unit recruitment & derecruitment thresholds, discharge rates & variability, and elbow flexion force steadiness were compared between conditions with and without vibration. Coefficient of variation of force and discharge rate variability decreased 37 and 17%, respectively in post-vibration compared with baseline and vibration conditions. Although the motor unit discharge rates did not differ between conditions the total number of motor units active at rest after de-ramp were fewer in the post-vibration condition. Contralateral tendon vibration reduces MU discharge rate variability and enhances force control on the more affected side in persons with Parkinson's disease.