Temporal Detection Threshold of Audio-Tactile Delays With Virtual Button.

Synchronization of audio-tactile stimuli represents a key feature of multisensory interactions. However, information on stimuli synchronization remains scarce, especially with virtual buttons. This work used a click sensation produced with traveling waves and auditory stimulus (a bip-like sound) related to a virtual click for a psychological experiment. Participants accomplish a click gesture and judge if the two stimuli were synchronous or asynchronous. Delay injection was performed on the audio (haptic first) or the click (audio first). In both sessions, one stimulus follows the other with a delay ranging from 0-700 ms. We use weighted and transformed 3-up/1-down staircase procedures to estimate people's sensitivity. We found a threshold of 179 ms and 451 ms for the auditory first and haptic first conditions, respectively. Statistical analysis revealed a significant effect between the two stimuli' order for threshold. Participants' acceptable asynchrony decreased when the delay was on the haptic rather than on the audio. This effect could be due to the natural experience in which the stimuli tend to be first tactile and then sonorous rather than the other way around. Our findings will help designers to create multimodal virtual buttons by managing audio-tactile temporal synchronization.

Shrimp sensitization in house dust mite algerian allergic patients: A single center experience.

Background: Cross-reactivity between shrimp and house dust mite (HDM) proteins has been widely documented. However, a significant geographical variability in sensitization patterns and cross-reactive allergens has been reported which may impact the diagnosis and management of shrimp allergy among HDM-shrimp co-sensitized patients. This study aimed to investigate the prevalence of shrimp and tropomyosin sensitization among HDM-allergic patients in order to understand the local epidemiology to inform the development of targeted diagnostic and therapeutic tools. Methods: Four hundred forty-six (446) HDM-allergic patients and 126 atopic controls were screened for shrimp-specific IgE using the IMMULITE 2000 XPI® System. HDM-shrimp sensitized subjected were also tested for IgE tropomyosin (nPen m 1) and thoroughly interviewed about their shellfish consumption habits. Tropomyosin sensitized patients were subjected to further analysis including measurement of IgE specific to squid and crab. Results: The prevalence of shrimp sensitization in the HDM-allergic population was 20.4% vs 0% in the control group. Of them 63.7% were clinically allergic to shrimp, while 9 cases had no history of allergic reaction to this food and 24 patients reported not having consumed shrimp before. Besides, 72.5% of the HDM-shrimp sensitized subjects had tropomyosin-specific IgE with a positivity rate of 82.8% among shrimp-allergic patients. Among tropomyosin reactors, 95.5% were sensitized to crab and 89.5% to squid, none of them had previously ingested neither crab nor squid. Nevertheless, one-third of HDM-shrimp sensitized patients who never consumed shrimp before did not react to tropomyosin. Conclusions: Shrimp allergy seems to be strictly dependent on HDM sensitization, at least in this geographical area. Therefore, HDM allergic patients should be systematically screened for shrimp sensitization and asked about the consumption of shellfish. Tropomyosin is a major and clinically relevant shrimp allergen that accounts for shellfish-HDM cross-reactivity. However, other components could be involved.

PCA Model of Fundamental Acoustic Finger Force for Out-of-Plane Ultrasonic Vibration and its Correlation with Friction Reduction.

When a finger touches an ultrasonic vibrating plate, a non-sinusoidal contact force is produced. This force is called acoustic finger force. In a setup where closed-loop control is performed on the vibration amplitude, a component of the acoustic finger force can be measured at the fundamental vibration frequency of the plate. This calculation is obtained from the measurement of the variation of the controller voltage between the no-load case and when a finger is present. This calculation is made for a group of twelve participants. From these results a PCA (Principal Component Analysis) model is created. This model permits estimation of the acoustic finger force response of a participant at any vibration amplitude, based on a one or two point measurement. Finally, a linear relation between the PCA coefficients and the friction reduction is proposed. The objective of this relation would be to ultimately provide the means to create an amplitude reference calibration based on the desired friction reduction level, and thus be able to produce a standardized tactile feedback for each user, despite the biomechanical differences in finger pad properties between subjects.