Vibratory Stimuli Research Articles

Substrate-borne vibrations reduced the density of tobacco whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) infestations on tomato, Solanum lycopersicum: an experimental assessment

Managing pests with insecticides is probably the most conventional available control method. However, insecticide overuse often results in resistance and subsequent pest resurgence, and often adversely affects the ecosystem. The physical management of insect pests by utilizing substrate-borne vibrations, sounds, or both is increasingly attracting attention as an alternative, as it has modest ecosystem impacts. This method exploits vibroacoustic insect communication used for mating and the perception of approaching enemies, provoking behavioral responses in an ingenious manner. We aimed to examine whether substrate-borne vibrations effectively drive away tobacco whiteflies [Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)], which are serious agricultural pests. To do so, B. tabaci individuals were artificially introduced into greenhouses where tomato (Solanum lycopersicum L.) plants were reared. A substantial reduction in the average density of B. tabaci nymphs and adults was achieved by transmitting vibrational stimuli to the plants. At the same time, no obvious reduction was found in the number of tomato plant flowers. Although the performance of the vibrational device and transmission procedures requires further improvement, the present results shed light on the potential of substrate-borne vibrations as a promising alternative for pest management.

Correspondence between physiological and behavioural responses to vibratory stimuli during the sleep onset period: A quantitative electroencephalography analysis.

Behavioural responses to auditory stimuli cease in late N1 or early N2 sleep. Yet, responsiveness to minimal intensity tactile stimuli and the correspondence with sleep microstructure during the sleep onset period is unknown. The aim of the present study was to investigate sleep microstructure using quantitative electroencephalography analysis when participants behaviourally responded to minimal intensity vibratory stimuli compared to when participants did not respond to stimuli during the sleep onset period. Eighteen participants wore a device that emitted vibratory stimuli to which individuals responded by tapping their index finger. A fast Fourier transform using multitaper-based estimation was applied to electroencephalography signals in 5-s epochs. Participants exhibited increases in higher frequencies 5s before and immediately after the stimulus presentation when they responded to the stimulus compared to when they did not respond during all sleep stages. They also had greater delta power after stimulus onset when they did not respond to stimuli presented in N1 and N2 sleep compared to when they did respond. Participants responded to a significantly greater proportion of stimuli in wake than in N1 sleep (p<.001, d=2.38), which was also significantly greater than the proportion of responses in N2 sleep (p<.001, d=1.12). Participants showed wake-like sleep microstructure when they responded to vibratory stimuli and sleep-like microstructure when they did not respond during all sleep stages. The present study adds to the body of evidence characterising N1 sleep as a transitional period between sleep and wake containing rapid fluctuations between these two states.

Propuesta del entrenamiento vibratorio en escaladores de la categoría juvenil de Pichincha

Introducción: La escalada deportiva es un deporte en el cual se evidencian capacidades condicionales como la fuerza-resistencia, gracias a la secuencia de movimientos acíclicos cuyas dificultades varían en un tiempo determinado, siendo necesario el uso de varios grupos de músculos ya sean de sostén o ejecutores. La aplicación de las vibraciones en los entrenamientos ha tomado fuerza en los últimos años, consecuencia de varios estudios de su aplicación para el desarrollo de fuerza, potencia en el salto, así como en la rehabilitación de personas lesionadas o adultos mayores como terapia de oposición a los efectos del envejecimiento. Objetivo: Proponer un entrenamiento a base de vibraciones mediante una plataforma luego de realizar una revisión sistemática. Método: El presente estudio es de tipo descriptivo-explicativo, informando acerca del entrenamiento a base de vibraciones y cómo estas influyen en los deportistas. Se emplea para la búsqueda sistemática el Google Académico, consultando las fuentes de investigación acerca del entrenamiento de fuerza-resistencia y entrenamiento vibratorio. Resultados: Propuesta de entrenamiento vibratorio en la plataforma Power Fit, detallando los ejercicios que pueden aplicar previo a los entrenamientos de suspensión y escalada. Se planteó un protocolo a seguir para que pueda tener una transferencia positiva las vibraciones a los ejercicios específicos que se realizan para la capacidad de fuerza-resistencia en los escaladores de la categoría juvenil de Pichincha. Conclusiones: El estímulo vibratorio acorta los tiempos que tomaría potenciar una capacidad mientras que protege las articulaciones de un desgaste prematuro por la carga de trabajo.

Vibration attraction response is a plastic trait in blind Mexican tetra (Astyanax mexicanus), variable within subpopulations inhabiting the same cave.

Animals evolve their sensory systems and foraging behaviours to adapt and colonize new and challenging habitats such as the dark cave environment. Vibration attraction behaviour (VAB) gives fish the ability to locate the source of a water disturbance in the darkness. VAB evolved in the blind Mexican cave tetra, Astyanax mexicanus. VAB is triggered in cavefish by vibration stimuli peaking at 35 Hz, which is within the main spectrum of water fluctuations produced by many prey crustaceans and insects. VAB has a genetic component and is correlated to an increased number of head mechanosensory neuromasts in the eye orbital region when compared to surface fish. Previous competitive prey capture assays have supported the advantage of VAB for foraging in the dark. Despite its putative adaptive function, VAB has been described as absent in some Astyanax cave populations (Tinaja and Molino) but present in others (Pachón, Piedras, Toro and Sabinos). Here we have tested the occurrence of VAB in the field and in multiple cave populations using a vibrating device in natural pools. Our results confirmed the presence of VAB in caves such as Pachón, Toro and Sabinos but showed that VAB is also present in the Tinaja and Molino cave populations, previously reported as VAB-negative in laboratory experiments. Thus, VAB is available throughout the range of hypogean A. mexicanus. However, and most notably, within a given cave the levels of VAB were highly variable among different pools. Fish at one pool may express no VAB, while fish at another nearby pool of the same cave may actively show VAB. While a variety of environmental conditions may foster this diversity, we found that individuals inhabiting pools with a high abundance of organic matter have reduced expression of VAB. In contrast, in pools with little organic debris where fish probably depend more on hunting than on scavenging, VAB is enhanced. Our results suggest that expression of VAB is a plastic trait whose variability can depend on local conditions. Such plasticity may be required within and among caves where high environmental variability between pools results in a diverse availability of food.

Reducing Results Variance in Lifespan Machines: An Analysis of the Influence of Vibrotaxis on Wild-Type Caenorhabditis elegans for the Death Criterion.

Nowadays, various artificial vision-based machines automate the lifespan assays of C. elegans. These automated machines present wider variability in results than manual assays because in the latter worms can be poked one by one to determine whether they are alive or not. Lifespan machines normally use a “dead or alive criterion” based on nematode position or pose changes, without poking worms. However, worms barely move on their last days of life, even though they are still alive. Therefore, a long monitoring period is necessary to observe motility in order to guarantee worms are actually dead, or a stimulus to prompt worm movement is required to reduce the lifespan variability measure. Here, a new automated vibrotaxis-based method for lifespan machines is proposed as a solution to prompt a motion response in all worms cultured on standard Petri plates in order to better distinguish between live and dead individuals. This simple automated method allows the stimulation of all animals through the whole plate at the same time and intensity, increasing the experiment throughput. The experimental results exhibited improved live-worm detection using this method, and most live nematodes (>93%) reacted to the vibration stimulus. This method increased machine sensitivity by decreasing results variance by approximately one half (from individual error per plate to ) and error in lifespan curve was reduced as well (from to ).

Arousal from death feigning by vibrational stimuli: comparison of Tribolium species

Death feigning (or tonic immobility) is an effective antipredator strategy. However, prolonged immobility on the ground increases the risk of being parasitized or eaten by predators, and thus, insects must rouse themselves when appropriate stimulation is provided. Very few studies on the effect of stimulus intensity on arousal from death feigning have been conducted. A previous study using Tribolium castaneum showed an existing threshold for the intensity of the stimulus that causes arousal from death feigning. Whether there are differences between species in the threshold for arousal is an interesting question. In the present study, we, therefore, compared the effect of stimulus strength on arousal from death feigning in two closely related species, namely, T. confusum and T. freemani, which are established strains that have been artificially selected for longer duration of death feigning. Also, part of the study was to determine whether there was a positive association between intensity of stimulus needed to rouse and the duration of death feigning. We discuss why there is a difference in the strength of the stimulus needed for arousal from death feigning among Tribolium species, for which we included the data for T. castaneum from a previous study.

The Anatomical and Physiological Basis of Clinical Tests of Otolith Function. A Tribute to Yoshio Uchino.

Otolithic receptors are stimulated by gravitoinertial force (GIF) acting on the otoconia resulting in deflections of the hair bundles of otolithic receptor hair cells. The GIF is the sum of gravitational force and the inertial force due to linear acceleration. The usual clinical and experimental tests of otolith function have used GIFs (roll tilts re gravity or linear accelerations) as test stimuli. However, the opposite polarization of receptors across each otolithic macula is puzzling since a GIF directed across the otolith macula will excite receptors on one side of the line of polarity reversal (LPR at the striola) and simultaneously act to silence receptors on the opposite side of the LPR. It would seem the two neural signals from the one otolith macula should cancel. In fact, Uchino showed that instead of canceling, the simultaneous stimulation of the oppositely polarized hair cells enhances the otolithic response to GIF—both in the saccular macula and the utricular macula. For the utricular system there is also commissural inhibitory interaction between the utricular maculae in each ear. The results are that the one GIF stimulus will cause direct excitation of utricular receptors in the activated sector in one ear as well as indirect excitation resulting from the disfacilitation of utricular receptors in the corresponding sector on the opposite labyrinth. There are effectively two complementary parallel otolithic afferent systems—the sustained system concerned with signaling low frequency GIF stimuli such as roll head tilts and the transient system which is activated by sound and vibration. Clinical tests of the sustained otolith system—such as ocular counterrolling to roll-tilt or tests using linear translation—do not show unilateral otolithic loss reliably, whereas tests of transient otolith function [vestibular evoked myogenic potentials (VEMPs) to brief sound and vibration stimuli] do show unilateral otolithic loss. The opposing sectors of the maculae also explain the results of galvanic vestibular stimulation (GVS) where bilateral mastoid galvanic stimulation causes ocular torsion position similar to the otolithic response to GIF. However, GVS stimulates canal afferents as well as otolithic afferents so the eye movement response is complex.

How can Cattle be Toilet Trained? Incorporating Reflexive Behaviours into a Behavioural Chain.

Simple SummaryThe mixing of bovine faeces and urine leads to climate-damaging ammonia emissions. If cattle could be taught to use a latrine, this would reduce the area of emissions, the separation of excreta could easily be accomplished by mechanical means, and animal health could be improved. Attempts to train toileting in cattle have shown limited success. In children, toileting is trained mainly by (i) interrupting voiding that starts outside the toilet, then taking the child to the toilet and rewarding the resumption of excretion, or (ii) placing the child on the toilet, waiting for urination/defecation and rewarding appropriate excretory behaviour. The first method is reported to be more successful. Thus, a similar procedure was evaluated for training latrine use for urination in calves. On 95% of occasions, the calves inhibited or stopped urination when receiving a signal to move to the latrine, and on 65% of occasions, they reinitiated urination in the latrine. Furthermore, during 63% of urinations in the latrine, the calves oriented towards the reward location before any food was delivered, providing additional evidence that calves can be successfully toilet trained with food rewards.Untrained cattle do not defecate or urinate in defined locations. The toilet training of cattle would allow urine and faeces to be separated and stored, reducing climate-damaging emissions and improving animal health. In a proof-of-concept study, we evaluated a novel protocol for toilet training in cattle. Five heifer calves (and yoked controls) were trained in the voluntary (operant) behaviours of a toileting chain. Then, reflexive urinating responses were incorporated into the chain, with toileting signalled by a tactile (vibratory) stimulus. On 95% of occasions, the calves inhibited/interrupted urination when receiving the stimulus, and on 65% of these occasions, reinitiated urination in the latrine. Furthermore, during 63% of urinations in the latrine, the calves oriented to the reward location before any food was delivered, providing additional evidence that calves can be successfully toilet trained with food rewards. Yoked controls failed to learn most of the operant elements and all the reflexive responses of toilet training. The results show that reflexive behaviours can be incorporated into voluntary toileting sequences with cattle and extend the range of species that can be toilet trained. Future refinement of the protocol to allow training under practical farm conditions offers the potential to mitigate climate damage and improve animal health.

Rendering Spatiotemporal Haptic Effects Via the Physics of Waves in the Skin.

A major challenge in haptic engineering has been to design practical methods to efficiently stimulate distributed areas of skin. Here, we show how to use a single actuator to generate vibrotactile stimuli which cause sensations of temporally varying spatial extent. Through optical vibrometry methods, we show that vibrational stimuli applied at the fingertip elicit waves in the finger that propagate proximally toward the hand and show how the frequency-dependent damping behavior of skin causes propagation distances to decrease rapidly with increasing frequency of stimulation. Utilizing these results, we design haptic stimuli applied through a single actuator that produces wavefields that expand or contract in size. In a perception experiment, participants accurately (median $>$95%) identified these stimuli as expanding or contracting without prior exposure or training. As a potential application, we used these effects as haptic cues for interactions in virtual reality. We show through a second experiment that the spatiotemporal haptic stimuli were rated as significantly more engaging than conventional vibrotactile stimuli. These findings demonstrate how the physics of waves in skin can be utilized to excite spatiotemporal tactile effects over large surface areas with a single actuator, and inform methods to utilize the effects in practical applications.

A comparison of the mechanisms controlling the hatching time and synchrony of the desert locust Schistocerca gregaria and the Bombay locust Nomadacris succincta (Orthoptera: Acrididae)

Hatching behaviors of the desert locust Schistocerca gregaria (Forskal) (Orthoptera: Acrididae) and the Bombay locust Nomadacris succincta (Johannson 1763) (Orthoptera: Acrididae) were observed to analyze the mechanisms controlling the hatching time and synchrony. At a 12-h thermoperiod of 25 °C and 30 °C under continuous illumination, most eggs hatched during the low temperature period in the desert locust, and the proportion of such individuals was lower in eggs kept in a mass than in those kept singly. In the Bombay locust, most eggs hatched during the high temperature period; however, the inter-pod variation was large. Both locusts hatched earlier with increasing the egg mass size in a range from 2 to 10 or 20 with similar hatching intervals. Desert locust eggs from different pods advanced the hatching but did not delay it to synchronize the hatching. In contrast, Bombay locust eggs advanced or delayed hatching depending on the age of the paired egg. The results suggested the presence of embryo–embryo interactions. In both locusts, a vibrational stimulus that was emitted by the embryo and transmitted via a piece of wire was likely to be responsible for synchronized hatching. The hatching patters of these species were compared with those reported previously for other taxa.

Tri-Modal Tactile Display and Its Application Into Tactile Perception of Visualized Surfaces.

Tactile representation on touchscreens plays an important role in improving realism and richness of users' interaction experience. The dynamic lateral force range and the efficient feedback dimensions are very critical in determining the fidelity of tactile displays. This article develops a tri-modal Electrovibration, Ultrasonic Vibration, and Mechanical Vibration (EUMV) tactile display integrating three types of representative principles, which enhances the dynamic lateral force range by leveraging electrostatic and ultrasonic vibrations stimuli, and induces the normal feedback dimension by utilizing mechanical vibration stimulus. Then, a tactile perception scheme with the EUMV display is proposed for simultaneously rendering contour and texture roughness features of visualized surfaces, in which the contour gradient-lateral force model and the texture gradient-perceived roughness model are determined respectively. Objective and subjective evaluations with 20 participants show that the novel scheme establishes significant improvements in both correct recognition ratios of geometric shapes and tactile perception realism of visualized images than the previous studies.

EFFECT OF BASIC FITNESS FUNCTION ACCORDING TO WHOLE-BODY VIBRATION STIMULUS WITH SLOPE DURING DEADLIFT

We aimed to investigate the effect of basic fitness function according to whole-body vibration (WBV) stimulus with slope during deadlift in adults. A total of 15 subjects performed deadlift exercise with a sound-wave vibrator. The subjects consisted of three groups: no slope and WBV group (control), WBV only group (group 1), and slope and WBV group (group 2). Slope was set at [Formula: see text], and the frequency and amplitude of WBV were 10[Formula: see text]Hz and 5[Formula: see text]mm, respectively. The participants performed Romanian deadlift 2 days a week for 4 weeks, including 10 trials per set and five sets a day. We measured basic fitness function factor including the isokinetic muscle contraction test using biodex system3. All groups showed an increase in strength of approximately [Formula: see text]%. Group 2 showed the highest increase. Moreover, maximal peak torque of the lumbar joint showed an increase trend similar to that of back muscle strength. An increase of 15.72%, 24.86%, and 51.44% was noted in the control, group 1, and group 2, respectively. The findings indicate that WBV exercise with slope is the most efficient exercise protocol for improving muscle function of the trunk. WBV with slope could help stimulate trunk muscles more and efficiently, could result in a more positive effect on muscle function compared with WBV only, and could be included in an exercise program for efficient patient rehabilitation.

Nanopolystyrene particles at environmentally relevant concentrations causes behavioral and biochemical changes in juvenile grass carp (Ctenopharyngodon idella)

The biometric, behavioral and biochemical toxicity of polystyrene nanoplastics (PS NPs) in aquatic freshwater vertebrates and in environmentally relevant concentrations remains poorly known. Thus, using different toxicity biomarkers we tested the hypothesis that the exposure of Ctenopharyngodon idella juveniles to small PS NPs concentrations (0.04 ng/L, 34 ng/L and 34 μg/L), for a short period-of-time, may affect their growth/development, individual and collective behavior, and biochemical parameters. Animals exposed to NPs did not show increased biometric parameters (i.e.: body biomass, total and standard length, peduncle height, head height and visceral somatic and hepatosomatic indices). Despite the lack of damage on the locomotor (open field test) and visual (visual stimulus test) abilities of the evaluated fish, the expected increase in locomotor activity during the vibratory stimulus test was not evident in animals exposed to NPs. Non-exposed animals were the only ones showing increased activity/locomotion time in the presence of the predatory stimulus during the individual anti-predatory response test. The behavior of animals directly confronted with a potential predator has evidenced the influence of NPs on shoals’ aggregation and on the distance kept by individuals from the predatory stimulus. These changes were associated with PS NPs accumulation in animals' brains, oxidative stress and increased acetylcholinesterase activity (hepatic and cerebral). Therefore, the current study has confirmed the initial hypothesis and showed that, even at low concentrations, PS NPs can affect the health of C. idella individuals at early life stage.

Comparison of Neural Activation Area in Primary Somatosensory Cortex and Brodmann Area 3 According to Finger and Phalange High-Frequency Vibration Stimulation

In this study, we measured neuronal activation in the primary somatosensory area (S1) and Brodmann area 3 (BA3) using 3T functional magnetic resonance imaging (fMRI) while presenting a 250-Hz high-frequency vibrational stimulus to each of three phalanges (distal, intermediate, and proximal) of four fingers of the right hand (index, middle, ring, and little). We compared the nerve activation area between each finger and each phalange. Ten healthy male college students (26.6 ± 2.5 years old) participated in this study. One session consisted of three blocks: a rest (30 s), stimulation (30 s), and response phase (9 s). In the rest phase, the vibrational stimulus was not presented. In the stimulation phase, the vibrational stimulation was presented at any one of the three phalanges of the selected finger. In the response phase, subjects were instructed to press a button corresponding to the phalange that they thought had received the vibration. The subtraction method was used to extract the activation area. The activation area in the S1 was the largest when the little finger was stimulated (for the finger comparison), and largest when the second phalange was stimulated (for the phalange comparison). The BA3 showed similar trends, and there was no statistically significant difference.

Effect of Local Vibration on Triceps Surae Flexibility Compared to Static Stretching

Purpose: This study examined the effects of local vibration using a massage gun on the triceps surae flexibility by measuring the ankle dorsiflexion range of motion (ROM) compared to static stretching in healthy adults. Methods: Twenty healthy subjects were instructed in this study. They were allocated randomly to two groups: local vibration (LV) and static stretching (SS). The ankle dorsiflexion ROM was measured before and after the intervention in supine (open kinetic chain, OKC) and standing (closed kinetic chain, CKC). The LV group received local vibration using a massage gun for five minutes on their triceps su rae, and the SS group stood on the Q board with a dorsiflexed ankle for five minutes. The ROM between pre- and post-intervention and the change in ROM between two groups were analyzed. A paired t-test was used to compare the ROM between pre- and post-interven tion, while an independent t-test was used to compare the change in ROM between the two groups. Results: Both groups showed a significant difference between pre- and post-intervention in the position of both the OKC and CKC. The change in ROM, however, was not significantly different between the two groups. Conclusion: The application of local vibration using a massage gun for five minutes on the triceps surae could improve its flexibility as much as the application of static stretching. A massage gun for the application of a local vibration stimulus may be effective, simple, portable, and comfortable.

Effects of exercise combined with whole body vibration in patients with patellofemoral pain syndrome: a randomised-controlled clinical trial

BackgroundPatellofemoral pain is a prevalent condition in the general population, especially in women, and produces functional impairment in patients. Therapeutic exercise is considered an essential part of the conservative management. The use of vibration platforms may help improve strength and function and reduce pain in patients with knee disorders. The aim of this investigation was to determine the effects of adding whole body vibration (vertical, vibration frequency of 40 Hz, with an amplitude from 2 to 4 mm) to an exercise protocol for pain and disability in adults with patellofemoral pain.MethodsA randomised clinical trial was designed, where 50 subjects were randomly distributed into either an exercise group plus whole body vibration or a control group. Pain, knee function (self-reported questionnaire) and range of motion and lower limb functionality were assessed at baseline and at 4 weeks. The experimental group performed 12 supervised sessions of hip, knee and core strengthening exercises on a vibration platform 3 times per week during 4 weeks. The control group followed the same protocol but without vibration stimuli. Differences in outcome measures were explored using an analysis of the variance of 2 repeated measures. Effect sizes were estimated using Square Eta (η2). Significant level was set al P < 0.05.ResultsStatistically significant differences were found after intervention in favour of the experimental group in the between-groups comparison and in the interaction of the experimental group before and after treatment in terms of pain perception (P = 0.000; η2 = 0.63) and function outcomes scores (P = 0.000; η2 0.39 and 0.51 for lower limb functional scale and Kujala scores respectively).ConclusionA 4-week whole body vibration exercise programme reduces pain level intensity and improves lower limb functionality in patellofemoral pain patients and is more effective than exercise alone in improving pain and function in the short-term.Trial registrationClinicalTrials.gov (NCT04031248). This study was prospectively registered on the 24th July, 2019.

Dhikrullah Vibration as Stimulus of Social Behavior Change

Dhikrullah is a strong single sound stimulus not yet applied as a stimulus to invite alpha wave in the brain as a center of human consciousness. Dhikrullah has been practiced among Muslims for more than a thousand years, but research on the function of dhikrullah as a stimulus to the brain waves as the center of human consciousness has not yet been completed. Chapter 2 of al-Anfal verse 2 and chapter ar-Rad verse 28. This study is an academic response to the foundation of discovering science for social change through dhikrullah. Scientific attention to behavior change through vibration stimuli is still very few. The combined data in this study consisted of qualitative data from 4 respondents in order to find the Dhikrullah model and quantitative data from 10 subjects to obtain dhikrullah stimulus samples on subject brain waves through Electro Encephalo Graf (EEG). The results obtained by EEG encourage dhikrullah as vibrations to be carried out as a stimulus to brain waves. Dhikrullah through the audiotory nerve is able to stimulate the brain to present alpha waves on the subject while running the dhikrullah. All subjects stated the difficulty of feeling calm during and after dhikrullah as a basis for behavior change. This study is new because it uses EEG to prove that dhikrullah vibration can be a stimulus for behavior change. Behavioral reviewers, especially practitioners can use dhikrullah as a stimulus to help humans who want to get change easily and cheaply.

Improved Tactile Perception of 3D Geometric Bumps Using Coupled Electrovibration and Mechanical Vibration Stimuli

Abstract At present, the tactile perception of 3D geometric bumps (such as sinusoidal bumps, Gaussian bumps, triangular bumps, etc.) on touchscreens is mainly realized by mapping the local gradients of rendered virtual surfaces to lateral electrostatic friction, while maintaining the constant normal feedback force. The latest study has shown that the recognition rate of 3D visual objects with electrovibration is lower by 27$\%$ than that using force-feedback devices. Based on the custom-designed tactile display coupling with electrovibration and mechanical vibration stimuli, this paper proposes a novel tactile rendering algorithm of 3D geometric bumps, which simultaneously generates the lateral and the normal perceptual dimensions. Specifically, a mapping relationship with the electrostatic friction proportional to the gradient of 3D geometric bumps is firstly established. Then, resorting to the angle between the lateral friction force and the normal feedback force, a rendering model of the normal feedback force using mechanical vibration is further determined. Compared to the previous works with electrovibration, objective evaluations with 12 participants showed that the novel version significantly improved recognition rates of 3D bumps on touchscreens.

Whole body vibration in the static modified push-up position in untrained healthy women stimulates neuromuscular system potentiating increased handgrip myogenic response

ObjectiveTo investigate the acute effect of whole-body vibration (WBV) on handgrip strength (HS) and electromyographic activity of the flexor digitorum superficialis muscle of healthy women in the static push-up position. MethodsTwenty-eight women received four experimental tests in a randomized order: A) Control – rest in seating position with feet on the floor and hands in the supine position on the lower limbs. There was no vibration stimulus; B) Placebo – push-up position with their hands on the vibratory platform that remained disconnected, but with a sonorous stimulus mimicking the vibration; C) Low vibration and D) High vibration – push-up position with their hands on the vibratory platform using one of the vibratory stimulus intensity: low vibration: 25 Hz/2 mm/49.30 m s−2; or high vibration: 45 Hz/2 mm/159.73 m s−2. Participants remained 5 min in each situation. HS and electromyography (EMG) were performed at baseline and after all four experimental tests. The index of neural efficiency (i.e. the ratio between EMG and HS) was also calculated to determine the efficiency of muscle contraction. Statistical analysis was performed by ANOVA two-way design mixed test with Tukey's post hoc test, being considered significant p < 0.05. ResultsHigh vibration increased HS compared with all the other experimental tests (p = 0.0006, F = 6.03). There was a reduction of EMG activity of the flexor digitorum superficialis muscle only after high vibration (p = 0.0135, F = 6.22), which was accompanied by lower values of the index of neural efficiency after intervention (between-group difference, p = 0.0002, F = 0.674). ConclusionWBV in the push-up position has an acute positive effect on HS accompanied by a lower index of neural efficiency, providing a better efficiency of muscle contraction.

Pulling Illusion Based on the Phase Difference of the Frequency Components of Asymmetric Vibrations

When presented with asymmetric vibrations, humans experience an illusory force, similar to the sensation of being pulled in a particular direction. A pulling illusion has also been used in new display elements for a virtual reality content and a pedestrian navigation system. However, the basic design of asymmetric vibration stimuli that can induce this illusion has not yet been determined. In particular, it is unclear as to which part of the vibration waveform should be asymmetric to induce an illusion. To better understand the design of asymmetric vibration stimuli that can induce a pulling illusion, we evaluated the effect of the illusion corresponding to the waveform deformation due to a change in phase difference of asymmetric-vibration frequency components. The results of a psychophysical experiment demonstrate that when the phase differences of the fundamental and second harmonic waves of the asymmetric vibration are close to 0° or -180°, the illusion is more likely to occur. This result implies that the difference in the rate by which the acceleration changes at each polarity contributes to the illusion.