Observing an expert's action swapped with an observer's face increases corticospinal excitability during combined action observation and motor imagery.

This study aimed to examine whether observing an expert's action swapped with an observer's face increases corticospinal excitability during combined action observation and motor imagery (AOMI). Twelve young males performed motor imagery of motor tasks with different difficulties while observing the actions of an expert performer and an expert performer with a swapped face. Motor tasks included bilateral wrist dorsiflexion (EASY) and unilateral two-ball rotating motions (DIFF). During the AOMI of EASY and DIFF, single-pulse transcranial magnetic stimulation was delivered to the left primary motor cortex, and motor-evoked potentials (MEPs) were obtained from the extensor carpi ulnaris and first dorsal interosseous muscles of the right upper limb, respectively. Visual analogue scale (VAS) assessed the subjective similarity of the expert performer with the swapped face in the EASY and DIFF to the participants themselves. The MEP amplitude in DIFF was larger in the observation of the expert performer with the swapped face than that of the expert performer (P = 0.012); however, the corresponding difference was not observed in EASY (P = 1.000). The relative change in the MEP amplitude from observing the action of the expert performer to that of the expert performer with the swapped face was positively correlated with VAS only in DIFF (r = 0.644, P = 0.024). These results indicate that observing the action of an expert performer with the observer's face enhances corticospinal excitability during AOMI, depending on the task difficulty and subjective similarity between the expert performer being observed and the observer.

Cross-talk elimination for lenslet array near eye display based on eye-gaze tracking.

Lenslet array (LA) near-eye displays (NEDs) are a recent technical development that creates a virtual image in the field of view of one or both eyes. A problem occurs when the user's pupil moves out of the LA-NED eye box (i.e., cross-talk) making the image look doubled or ghosted. It negatively impacts the user experience. Although eye-gaze tracking can mitigate this problem, the effect of the solution has not been studied to understand the impact of pupil size and human perception. In this paper, we redefine the cross-talk region as the practical pupil movable region (PPMR50), which differs from eye box size because it considers pupil size and human visual perception. To evaluate the effect of eye-gaze tracking on subjective image quality, three user studies were conducted. From the results, PPMR50 was found to be consistent with human perception, and cross-talk elimination via eye-gaze tracking was better understood in a static gaze scenario. Although the system latency prevented the complete elimination of cross-talk for fast movements or large pupil changes, the problem was greatly alleviated. We also analyzed system delays based on PPMR50, which we newly defined in this paper and provided an optimization scheme to meet the maximum eyeball rotation speed.

DFusion: Denoised TSDF Fusion of Multiple Depth Maps with Sensor Pose Noises.

The truncated signed distance function (TSDF) fusion is one of the key operations in the 3D reconstruction process. However, existing TSDF fusion methods usually suffer from the inevitable sensor noises. In this paper, we propose a new TSDF fusion network, named DFusion, to minimize the influences from the two most common sensor noises, i.e., depth noises and pose noises. To the best of our knowledge, this is the first depth fusion for resolving both depth noises and pose noises. DFusion consists of a fusion module, which fuses depth maps together and generates a TSDF volume, as well as the following denoising module, which takes the TSDF volume as the input and removes both depth noises and pose noises. To utilize the 3D structural information of the TSDF volume, 3D convolutional layers are used in the encoder and decoder parts of the denoising module. In addition, a specially-designed loss function is adopted to improve the fusion performance in object and surface regions. The experiments are conducted on a synthetic dataset as well as a real-scene dataset. The results prove that our method outperforms existing methods.

Effects of vibrotactile-enhanced music-based intervention on sensorimotor control capacity in the hand of an aging brain: a pilot feasibility randomized crossover trial.

BACKGROUND: Music-based interventions (MBI), using music as a therapeutic medium, has been utilized as a promising strategy for motor relearning and shaping. However, currently, MBI with active performance training is restricted to being extensively applied for patients with various levels of defects in fine motor skills and cognitive functions. Therefore, the integration of vibrotactile stimulation with MBI has been adopted as a motor training strategy intended to enhance motor learning through use of vibration stimuli. The current study was designed to investigate differences in the sensorimotor performance of older adults' hands under baseline, a single session of active MBI, and vibrotactile-enriched MBI conditions. METHODS: Thirty healthy older adults were recruited and randomized to receive either the single session of 30-min of vibrotactile-enriched MBI or 30-min of active MBI at the beginning of the experiment. After a one-week washout period, they switched their treatment programs and then were assessed to study the training effects of both approaches through measuring precision pinch performance, hand function, and sensory status. RESULTS: The results of the Pinch-Holding-Up Activity test revealed a statistically significant difference in the FRpeak parameter (F = 14.37, p < 0.001, η2p = 0.507) under the vibrotactile-enriched MBI condition compared to the baseline and active MBI conditions. In addition, significant beneficial effects were found on the results of the barognosis (F = 19.126, p < 0.001, η2p = 0. 577) and roughness differentiation subtests (F = 15.036, p < 0.001, η2p = 0.518) in the Manual Tactile Test for the participants in the vibrotactile-enriched MBI group. In addition, the participants under both the active MBI and vibrotactile-enriched MBI conditions exhibited better performance in the three subtests of the Purdue Pegboard Test as compared to under the baseline condition (p < 0.016). CONCLUSIONS: The findings indicated that vibrotactile-enriched MBI potentially improves the precision pinch performance of hands in healthy older adults. In addition, the add-on effect of vibrotactile stimulation to the MBI condition provides beneficial effects on the sensory functions of the upper extremities. TRIAL REGISTRATION: NCT04802564 . Date of registration: 15/03/2021. The first posted date: 17/03/2021.

No Interface, No Problem: Gesture Recognition on Physical Objects Using Radar Sensing.

Physical objects are usually not designed with interaction capabilities to control digital content. Nevertheless, they provide an untapped source for interactions since every object could be used to control our digital lives. We call this the missing interface problem: Instead of embedding computational capacity into objects, we can simply detect users' gestures on them. However, gesture detection on such unmodified objects has to date been limited in the spatial resolution and detection fidelity. To address this gap, we conducted research on micro-gesture detection on physical objects based on Google Soli's radar sensor. We introduced two novel deep learning architectures to process range Doppler images, namely a three-dimensional convolutional neural network (Conv3D) and a spectrogram-based ConvNet. The results show that our architectures enable robust on-object gesture detection, achieving an accuracy of approximately 94% for a five-gesture set, surpassing previous state-of-the-art performance results by up to 39%. We also showed that the decibel (dB) Doppler range setting has a significant effect on system performance, as accuracy can vary up to 20% across the dB range. As a result, we provide guidelines on how to best calibrate the radar sensor.

Positive Emotion Amplification by Representing Excitement Scene with TV Chat Agents.

This paper proposes emotion amplification for TV chat agents allowing users to get more excited in TV sports programs, and a model that estimates the excitement level of TV programs based on the number of social comment posts. The proposed model extracts the exciting intervals from social comments to the program scenes. By synchronizing recorded video streams and the intervals, the agents may talk with the user dynamically changing the frequency and volume of upbeat utterances, increasing the excitement of the user. To test these agents, participants watched TV content under three conditions: without an agent, with four agents that utter with a flat voice, and with four agents with emotion amplification. Results from 24 young adult Japanese individuals showed that their arousal of participants' subjective and physiological emotional responses were boosted because of the agents, enhancing their motivation to interact with the agent in the future. With empirical evidence, this paper supports these expectations and demonstrates that these agents can amplify the positive emotions of TV watchers, enhancing their motivation to interact with the agent in the future.

Effects of Eye Vergence and Accommodation on Interactions with Content on an AR Magic-lens Display and its Surroundings.

Augmented reality (AR) magic-lens (ML) displays, such as handheld devices, offer a convenient and accessible way to enrich our environment using virtual imagery. Several display technologies, including conventional monocular, less common stereoscopic, and varifocal displays, are currently being used. Vergence and accommodation effects on depth perception, as well as vergence-accommodation conflict, have been studied, where users interact only with the content on the display. However, little research exists on how vergence and accommodation influence user performance and cognitive-task load when users interact with the content on a display and its surroundings in a short timeframe. Examples of this are validating augmented instructions before making an incision andperforming general hand-eye coordinated tasks such as grasping augmented objects. To improve interactions with future AR displays in such scenarios, we must improve our understanding of this influence. To this end, we conducted two fundamental visual-acuity user studies with 28 and 27 participants, while investigating eye vergence and accommodation distances on four ML displays. Our findings show that minimizing the accommodation difference between the display and its surroundings is crucial when the gaze between the display and its surroundings shifts rapidly. Minimizing the difference in vergence is more important when viewing the display and its surroundings as a single context without shifting the gaze. Interestingly, the vergence-accommodation conflict did not significantly affect the cognitive-task load nor play a pivotal role in the accuracy of interactions with AR ML content and its physical surroundings.

Quality assurance: recommended guidelines for safe heating by capacitive-type heating technique to treat patients with metallic implants.

This article is a redissemination of the previous Japanese Quality Assurance Guide guidelines. Specific absorption rate and temperature distribution were investigated with respect to various aspects including metallic implant size and shape, insertion site, insertion direction, blood flow and heating power, and simulated results were compared with adverse reactions of patients treated by radio frequency capacitive-type heating. Recommended guidelines for safe heating methods for patients with metallic implants are presented based on our findings.

In vitro assessment of factors affecting the apparent diffusion coefficient of Jurkat cells using bio-phantoms.

It is well known that many tumor tissues show lower apparent diffusion coefficient (ADC) values, and that several factors are involved in the reduction of ADC values. The aim of this study was to clarify how much each factor contributes to decreases in ADC values. We investigate the roles of cell density, extracellular space, intracellular factors, apoptosis and necrosis in ADC values using bio-phantoms. The ADC values of bio-phantoms, in which Jurkat cells were encapsulated by gellan gum, were measured by a 1.5-Tesla magnetic resonance imaging device with constant diffusion time of 30sec. Heating at 42℃ was used to induce apoptosis while heating at 48℃ was used to induce necrosis. Cell death after heating was evaluated by flow cytometric analysis and electron microscopy. The ADC values of bio-phantoms including non-heated cells decreased linearly with increases in cell density, and showed a steep decline when the distance between cells became less than 3µm. The analysis of ADC values of cells after destruction of cellular structures by sonication suggested that approximately two-thirds of the ADC values of cells originate from their cellular structures. The ADC values of bio-phantoms including necrotic cells increased while those including apoptotic cells decreased. This study quantitatively clarified the role of the cellular factors and the extracellular space in determining the ADC values produced by tumor cells. The intermediate diffusion time of 30msec might be optimal to distinguish between apoptosis and necrosis.

Influence of permittivity and electrical conductivity on image pattern of MRI.

In proton density-weighted (PDW) MR imaging, the patterns of signal intensity vary depending on the imaged material, and change with the flip angle (FA) applied to the imaged material. The correlation between the pre-determined FA and the actual FA applied to imaged objects was investigated using 4 types of phantoms having different dielectric properties. PDW images were acquired using the spin-echo (SE) method and different pre-determined FA. Dependency of the signal intensity distribution in the phantom on the pre-determined FA differed among phantoms: patterns for water and 0.402 w/w% saline solution phantoms changed with the pre-determined FA, whereas those for olive oil and 4.02 w/w% saline solution phantoms were barely affected by the pre-determined FA. Causes of these phenomena were considered to be the differences between the pre-determined FA and the actual FA among the phantoms; differences were also influenced by the positioning of the phantom. Our study showed that the actual FA in the phantom is greater than the pre-determined FA in high permittivity media, whereas it is reduced by an increased conductivity of the media.

Systematic Review of Augmented Reality Training Systems.

Recent augmented reality (AR) advancements have enabled the development of effective training systems, especially in the medical, rehabilitation, and industrial fields. However, it is unclear from the literature what the intrinsic value of AR to training is and how it differs across multiple application fields. In this work, we gathered and reviewed the prototypes and applications geared towards training the intended user's knowledge, skills, and abilities. Specifically, from IEEE Xplore plus other digital libraries, we collected 64 research papers present in high-impact publications about augmented reality training systems (ARTS). All 64 papers were then categorized according to the training method used, and each paper's evaluations were identified by validity. The summary of the results shows trends in the training methods and evaluations that incorporate ARTS in each field. The narrative synthesis illustrates the different implementations of AR for each of the training methods. In addition, examples of the different evaluation types of the current ARTS are described for each of the aforementioned training methods. We also investigated the different training strategies used by the prevailing ARTS. The insights gleaned from this review can suggest standards for designing ARTS regarding training strategy, and recommendations are provided for the implementation and evaluation of future ARTS.

Visualization of stent lumen in MR imaging: relationship with stent design and RF direction.

Magnetic resonance imaging (MRI) visualization of metallic stent lumens is possible if the stent structure counteracts eddy currents in the lumen induced by the radio frequency magnetic field, B(1). To examine the effectiveness of various stent designs in counteracting eddy currents, we anchored eight copper stent models and 2 commercially available nickel-titanium alloy (Nitinol) stents in a gel phantom, perpendicular or parallel to the direction of B(1). A mesh stent lumen showed hypointensity irrespective of its alignment relative to B(1). A solenoid stent lumen showed hypointensity with the stent axis parallel to B(1), but it had the same signal intensity as outside the lumen when perpendicular to B(1). A Moebius stent lumen showed no signal reduction, irrespective of alignment relative to B(1). Lumens of the commercially available stents showed hypointensity regardless of alignment relative to B(1). Computer simulation revealed that the signal intensities of the stents corresponded to magnetic flux densities of B(1) in the stents, which are modified by the structure of the stent. While in vivo MRI viewing of a Moebius stent lumen is likely possible regardless of axis alignment, inherent structural weakness may be problematic. As a more practical choice, the solenoid stent is easier to manufacture and generates no hypointensive signal when the axis is parallel to B(0).

In vitro assessment of factors affecting the apparent diffusion coefficient of Ramos cells using bio-phantoms.

The roles of cell density, extracellular space, intracellular factors, and apoptosis induced by the molecularly targeted drug rituximab on the apparent diffusion coefficient (ADC) values were investigated using bio-phantoms. In these bio-phantoms, Ramos cells (a human Burkitt's lymphoma cell line) were encapsulated in gellan gum. The ADC values decreased linearly with the increase in cell density, and declined steeply when the extracellular space became less than 4 µm. The analysis of ADC values after destruction of the cellular membrane by sonication indicated that approximately 65% of the ADC values of normal cells originate from the cell structures made of membranes and that the remaining 35% originate from intracellular components. Microparticles, defined as particles smaller than the normal cells, increased in number after rituximab treatments, migrated to the extracellular space and significantly decreased the ADC values of bio-phantoms during apoptosis. An in vitro study using bio-phantoms was conducted to quantitatively clarify the roles of cellular factors and of extracellular space in determining the ADC values yielded by tumor cells and the mechanism by which apoptosis changes those values.

Robot touch with speech boosts positive emotions.

A gentle touch is an essential part of human interaction that produces a positive care effect. Previously, robotics studies have shown that robots can reproduce a gentle touch that elicits similar, positive emotional responses in humans. However, whether the positive emotional effects of a robot's touch combined with speech can be enhanced using a multimodal approach remains unclear. This study supports the hypothesis that a multimodal interaction combining gentle touch and speech by a robot enhances positive emotional responses. Here, we conducted an experiment using a robotic arm to perform a gentle touch combined with speech and compared three conditions: touch alone, speech alone, and touch with speech. We assessed participants' subjective ratings of valence, arousal, and human likeliness using subjective emotional responses. Furthermore, we recorded facial electromyography (EMG) from the corrugator supercilii and zygomaticus major muscles and measured skin conductance levels (SCLs) as physiological emotional responses. Our results show that touch combined with speech elicited higher subjective valence and arousal ratings, stronger zygomaticus major EMG and SCL activities than touch alone. The results suggest that the positive emotional effects of robotic touch can be boosted by combining elements of speech.

Surface Remeshing: A Systematic Literature Review of Methods and Research Directions.

Triangle meshes are used in many important shape-related applications including geometric modeling, animation production, system simulation, and visualization. However, these meshes are typically generated in raw form with several defects and poor-quality elements, obstructing them from practical application. Over the past decades, different surface remeshing techniques have been presented to improve these poor-quality meshes prior to the downstream utilization. A typical surface remeshing algorithm converts an input mesh into a higher quality mesh with consideration of given quality requirements as well as an acceptable approximation to the input mesh. In recent years, surface remeshing has gained significant attention from researchers and engineers, and several remeshing algorithms have been proposed. However, there has been no survey article on remeshing methods in general with a defined search strategy and article selection mechanism covering the recent approaches in surface remeshing domain with a good connection to classical approaches. In this article, we present a survey on surface remeshing techniques, classifying all collected articles in different categories and analyzing specific methods with their advantages, disadvantages, and possible future improvements. Following the systematic literature review methodology, we define step-by-step guidelines throughout the review process, including search strategy, literature inclusion/exclusion criteria, article quality assessment, and data extraction. With the aim of literature collection and classification based on data extraction, we summarized collected articles, considering the key remeshing objectives, the way the mesh quality is defined and improved, and the way their techniques are compared with other previous methods. Remeshing objectives are described by angle range control, feature preservation, error control, valence optimization, and remeshing compatibility. The metrics used in the literature for the evaluation of surface remeshing algorithms are discussed. Meshing techniques are compared with other related methods via a comprehensive table with indices of the method name, the remeshing challenge met and solved, the category the method belongs to, and the year of publication. We expect this survey to be a practical reference for surface remeshing in terms of literature classification, method analysis, and future prospects.

Development of a human-tissue-like phantom for 3.0-T MRI.

PURPOSE: A 3.0-T MRI phantom having human-tissue-equivalent relaxation times was developed. METHODS: The ingredients of the phantom are carrageenan (for gelatinization), GdCl(3) (as a T(1)-relaxation modifier), agarose (as a T(2)-relaxation modifier), and NaN(3) (as an antiseptic agent). Numerous samples with varying concentrations of GdCl(3) and agarose were prepared, and T(1) and T(2) were measured using 3.0-T MRI. RESULTS: Relaxation times of the phantom samples ranged from 395 to 2601 ms for T(1) values and 29 to 334 ms for T(2) values. Based on the measured results, empirical formulae were devised to express the relationships between the concentrations of relaxation modifiers and relaxation times. CONCLUSIONS: Adjustment of GdCl(3) and agarose concentrations allows arbitrary setting of relaxation times, and the creation of a phantom that can mimic relaxation times of human-tissue. Carrageenan is considered the most suitable as a gelling agent for an MRI phantom, as it permits the relatively easy and inexpensive production of a large phantom such as for the human torso, and which can be easily shaped with a knife.

Robust Reflectance Estimation for Projection-Based Appearance Control in a Dynamic Light Environment.

We present a novel method that robustly estimates the reflectance, even in an environment with dynamically changing light. To control the appearance of an object by using a projector-camera system, an appropriate estimate of the object's reflectance is vital to the creation of an appropriate projection image. Most conventional estimation methods assume static light conditions; however, in practice, the appearance is affected by both the reflectance and environmental light. In an environment with dynamically changing light, conventional reflectance estimation methods require calibration every time the conditions change. In contrast, our method requires no additional calibration because it simultaneously estimates both the reflectance and environmental light. Our method is based on the concept of creating two different light conditions by switching the projection at a rate higher than that perceived by the human eye and captures the images of a target object separately under each condition. The reflectance and environmental light are then simultaneously estimated by using the pair of images acquired under these two conditions. We implemented a projector-camera system that switches the projection on and off at 120 Hz. Experiments confirm the robustness of our method when changing the environmental light. Further, our method can robustly estimate the reflectance under practical indoor lighting conditions.

Viral-derived DNA invasion and individual variation in an Indonesian population of large flying fox Pteropus vampyrus.

Here, we performed next-generation sequencing (NGS) on six large flying foxes (Pteropus vampyrus) collected in Indonesia. Seventy-five virus species in the liver tissue of each specimen were listed. Viral homologous sequences in the bat genome were identified from the listed viruses. This finding provides collateral evidence of viral endogenization into the host genome. We found that two of the six specimens bore partial sequences that were homologous to the plant pathogens Geminiviridae and Luteoviridae. These sequences were absent in the P. vampyrus chromosomal sequences. Hence, plant viral homologous sequences were localized to the hepatocytes as extrachromosomal DNA fragments. Therefore, this suggests that the bat is a potential carrier or vector of plant viruses. The present investigation on wild animals offered novel perspectives on viral invasion, variation, and host interaction.

In vitro experimental study of the relationship between the apparent diffusion coefficient and changes in cellularity and cell morphology.

Diffusion-weighted magnetic resonance imaging (MRI) is frequently used clinically, and is available for the whole-body screening for tumors. The exact mechanism by which the apparent diffusion coefficient (ADC) value decreases in tumorous tissue remains unclear, although various theories have been proposed, including intracellular and extracellular factor theories. It is impossible to distinguish each factor in the intracellular and extracellular spaces as the source of MR signal generation by means of conventional comparison between MR images and pathological specimens. Other factors which have been reported to affect ADC include cellularity and cellular edema of human tissues, and temperature of phantoms at the time of measurement. We employed a new technique that enables cellular MR imaging using a newly developed bio-phantom containing a living culture tumor cell line, Jurkat-N1. We investigated possible reasons for observed decreases in ADC values for tumors, and we considered the contribution of both the intracellular and extracellular space to such a decrease. The ADC values of the bio-phantom increased with increasing heat exposure from 27 to 45 degrees C. ADC values also increased after the destruction by sonication of tumor cell membranes. ADC values decreased as cellularity increased in the bio-phantom. ADC values decreased due to cellular edema caused by a low salt concentration in the bio-phantom. Changes in pressure in the bio-phantom had no effect on the observed ADC values. We calculated both the intracellular ADC and extracellular ADC values using the ADC values, cellularity, and cellular volume of Jurkat-N1 cells in the bio-phantom. The extracellular ADC values in the bio-phantom were estimated to be lower than the ADC value of distilled water. These results indicate that not only intracellular ADC values, but also extracellular ADC values contribute to the determination of the ADC values of bio-phantoms. This is the first report to have examined the contribution of intracellular and extracellular space on the ADC values of bio-phantoms containing cultured tumor cells.

Production of a human-tissue-equivalent MRI phantom: optimization of material heating.

PURPOSE: We conceived a 2-stage heating method to dissolve the ingredients of magnetic resonance (MR) imaging phantoms to overcome issues of uneven quality in conventional MR imaging phantoms, and we evaluated uniformity and the reproducibility of our method. METHODS: We used a 3-liter capacity, column-shaped, enamel-coated porcelain container to produce a muscle-equivalent phantom (diameter, 160 mm; height, 100 mm; volume, 2 liters). The phantom contained: 1) carrageenan as a gelling agent; 2) agarose as a T2 modifier; 3) GdCl3 as a T1 modifier; 4) NaN3 as an antiseptic; and 5) distilled water. We applied both direct heating and 2-stage heating of pre-soaked materials. We placed powdered materials directly into hot water for direct heating but soaked them in water one day before use (post-swelling) in 2-stage heating. The materials in the container were melted in a silicone oil bath of 120 or 140 degrees C under various conditions, then allowed to gel by natural cooling. We observed the resulting gel phantoms macroscopically using a CCD camera and evaluated their uniformity by microscopy and MR imaging. RESULTS: We found it necessary to raise the temperature inside the phantom to 100.0 degrees C, to produce a uniform gel with stable homogeneity and few bubbles. Use of an enamel-coated porcelain container required setting the temperature of the oil bath at 140 degrees C. CONCLUSION: A uniform and reproducible human tissue-equivalent phantom with few bubbles can be manufactured using our 2-stage heating method, which employs pre-soaking in a silicone oil bath at 140 degrees C for 30 min. We then added the swollen carrageenan to the agarose solution, which heating the temperature to 140 degrees C for 30 min while continuously stirring at 120 rpm, following with natural cooling.