Kazunori Nozaki

Real-time multi-scale brain data acquisition, assembly, and analysis using an end-to-end OptIPuter

At iGrid 2005 we demonstrated the transparent operation of a biology experiment on a test-bed of globally distributed visualization, storage, computational, and network resources. These resources were bundled into a unified platform by utilizing dynamic lambda allocation, high bandwidth protocols for optical networks, a Distributed Virtual Computer (DVC) [N. Taesombut, A. Chien, Distributed Virtual Computer (DVC): Simplifying the development of high performance grid applications, in: Proceedings of the Workshop on Grids and Advanced Networks, GAN 04, Chicago, IL, April 2004 (held in conjunction with the IEEE Cluster Computing and the Grid (CCGrid2004) Conference)], and applications running over the Scalable Adaptive Graphics Environment (SAGE) [L. Renambot, A. Rao, R. Singh, B. Jeong, N. Krishnaprasad, V. Vishwanath, V. Chandrasekhar, N. Schwarz, A. Spale, C. Zhang, G. Goldman, J. Leigh, A. Johnson, SAGE: The Scalable Adaptive Graphics Environment, in: Proceedings of WACE 2004, 23-24 September 2004, Nice, France, 2004]. Using these layered technologies we ran a multi-scale correlated microscopy experiment [M.E. Maryann, T.J. Deerinck, N. Yamada, E. Bushong, H. Ellisman Mark, Correlated 3D light and electron microscopy: Use of high voltage electron microscopy and electron tomography for imaging large biological structures, Journal of Histotechnology 23 (3) (2000) 261-270], where biologists imaged samples with scales ranging from 20X to 5000X in progressively increasing magnification. This allows the scientists to zoom in from entire complex systems such as a rat cerebellum to individual spiny dendrites. The images used spanned multiple modalities of imaging and specimen preparation, thus providing context at every level and allowing the scientists to better understand the biological structures. This demonstration attempts to define an infrastructure based on OptIPuter components which would aid the development and design of collaborative scientific experiments, applications and test-beds and allow the biologists to effectively use the high resolution real estate of tiled displays.

Sibilant /s/ Simulator Based on Computed Tomography Images and Dental Casts

The sibilant /s/ is produced by raising the tongue against the roof of the mouth to form a narrow constriction, which is adjusted so that the airstream emerging from it impinges on the incisors. However, the location where the sibilant sound occurs is unclear, as are the details of the mechanisms of its generation. In this study, we used a realistically shaped replica produced with a three-dimensional printer and demonstrated that turbulent flow was generated in the oral tract near the incisors and lips and that sufficiently developed turbulent flow generated a sound source up to 20,000 Hz at 333, 500, and 667 cm3/sec, which agrees with the range of physiological flow rates typical for /s/. The characteristics of the sound spectra agreed with those of the sibilant /s/ sound emitted by our control individual. Such a physical perspective could yield knowledge useful for oral surgery and speech science – for example, to predict how the generation of sibilants may be occasionally affected by orthodontic and prosthodontic treatments.

Visualization of Large-scale CFD Simulation Results Using Distributed Particle-Based Volume Rendering

In this paper, we present a technique for visualizing a large-scale irregular volume dataset that is generated from an LES-based CFD simulation. Since our computational mesh was too large for a single computational node, it was divided into multiple regions; moreover, the resulting file was comprised of various irregular volume datasets. In order to cope with the multiple volume datasets, we extended our particle-based volume rendering (PBVR) technique so to fit the distributed computing environment. We applied our distributed PBVR technique to an LES-based CFD simulation, which explores dental fricative sound sources in order to confirm the effectiveness of the technique.

LES AND 'IN-VITRO' EXPERIMENTAL VALIDATION OF FLOW AROUND A TEETH-SHAPED OBSTACLE

The current paper aims to provide numerical and experimental flow data relevant for physical modelling of human fricative sound production due to the interaction of airflow with the teeth. A simplified upper incisor-palate geometry is derived from typical morphological features. The geometry is inserted in a rectangular channel for which the width-to-height ratio yields 4. The obstruction degree due to the presence of the simplified upper incisor yields 70%. Numerical flow data are obtained from large eddy simulations. Experimental flow data are gathered from single-sensor anemometry on a rigid plaster print of the computational grid. Transverse velocity profiles are obtained downstream in the constricted area, i.e., from x = 0 up to x/h = 1.5 with h denoting the aperture height. The Reynolds number is set to 4000. The mean velocity profiles derived on simulated and measured data exhibit a strong asymmetry due to the presence of the obstruction. Nevertheless, significant differences appear with respect to the jet development, as e.g., quantified by the downstream evolution of the jet width or the appearance of significant turbulence intensities (>10%) at the teeth edge in the measured data whereas the simulated flow remains laminar.

Integration of computational fluid dynamics and computational aero acoustics on grid for dental applications

The hybrid applications are needed in dental research because the result of their operation could be predicted by both modeling of an oral truct and more than two kind of physical simulations. However, it takes long time to perform the hybrid applications, cost a lot of money and needs some experience to deal with them. This paper proposes a new execution procedure of two applications which can reduce the implementation time by considering parallel efficiency of those applications. It can determine which attitude should be taken, sequential or separate execution of two different applications related with each other. Following the execution procedure, the dental hybrid application was performed. As a result of that, desirable pairs of the number of CPUs allocated to each simulation could be found. This means that the adequate procedure should be considered before execution of the hybrid applications, in order to play a compute power producer for dental clinics and hospitals.

Evaluating tooth brushing performance with smartphone sound data

This paper presents a new method for evaluating tooth brushing performance using audio collected from a smartphone. To do this, we use hidden Markov models (HMMs) to recognize audio data that include various types of tooth brushing actions, such as brushing the outer surface of the front teeth and brushing the inner surface of the back teeth. We then use the output of the HMMs to build regression models to estimate tooth brushing performance scores, such as stroke quality of brushing for the back inner teeth and duration of brushing for the front teeth. The scores used to train these regression models are obtained from a dentist who specializes in dental care instruction, with the resulting regression models estimating performance scores that closely correspond to the scores assigned by the dentist.

Numerical Simulation of Sibilant [s] Using the Real Geometry of a Human Vocal Tract

Speech is the one of the oral function due to fluid dynamics. The sibilant [s], one of dental fricative voice, is assumed to be generated from turbulence around the frontal teeth. Large Eddy Simulation with taking the real morphological vocal tract into account was demonstrated. The mean flow of the sibilant [s] separates from the tip of the upper anterior teeth and induces half plane jet along the lower anterior teeth. ΔP on surface of the anterior teeth is assumed to be somehow linked to the location of the high value Powell sound source.

Estimation of minimum oral tract constriction area in sibilant fricatives from aerodynamic data

Speech screening of sibilant fricative phonemes is an important tool for oral health care. Nevertheless, screening as a function of quantitative geometrical markers is mostly limited to teeth features whereas the minimum area of the narrowed air passage upstream from the tooth is known to be a key production feature. The minimum area is estimated from non-invasive aerodynamic measurements using a laminar flow model. The influence of viscid flow losses on the area estimation is shown to be negligible. Current data suggest that speech screening is most effective for phoneme /s/, which supports common practice in oral health care.

The role of initial flow conditions for sibilant fricative production

Sibilant fricative sound production depends on the geometric and flow properties of the production system. Nevertheless, few studies deal with the potential impact of flow properties other than the inlet volume flow rate on the noise produced. In this work, an experimental study is presented using a replica based on a reconstructed oral cavity for the phoneme /s/. Initial flow conditions upstream from the sibilant groove are altered by varying the method of air supply. Statistical moments of the initial velocity distribution are characterized using hot-film anemometry and related to spectral features of the radiated acoustic pressure. Discrepancies in the dynamic amplitude (≤25%) and negative spectral slope (≤35%) observed at a constant Reynolds number but different initial upstream flow conditions are of the same order of magnitude as those previously reported in humans. This suggests that consideration of the upstream flow conditions is important in the study of sibilant fricative sound production.

The effect of wearing custom-made mouthguards on the aeroacoustic properties of Japanese sibilant /s/

BACKGROUND/AIM There have been many reports on the discomfort of speech when wearing oral appliances. Fricatives articulated in an oral cavity can be difficult to pronounce when oral appliances are worn, because the oral cavity is partially changed by their installation. Sibilant /s/, one fricative, is especially difficult to pronounce when wearing oral appliances. This study investigates the effect of the difference in the setting positions of the palatal margin of custom-made mouthguards on the aeroacoustic characteristics of sibilant /s/. MATERIALS AND METHODS Eighteen subjects (11 women and seven men) participated. The palatal margin of mouthguards was set at the gingival line for nine subjects and 4 mm from the line for another nine subjects. Acoustical analyses examined the difference of the palatal margins of the mouthguards on the autocorrelation coefficient, the zero crossing count, and the spectral peaks of sibilant /s/. RESULTS The results showed that the zero crossing count of the waveforms and the spectral peaks of sibilant /s/ were significantly broadened and shifted toward the low-frequency range with the mouthguard whose palatal margin extended 4 mm from the gingival line than the mouthguard whose palatal margin was set at the gingival line. CONCLUSION We believe that a more appropriate palatal mouthguard design for custom-made mouthguards can be made by considering the aeroacoustical effects. Our study supported the mouthguard whose palatal margin was set at the gingival line by considering the influence on pronouncing sibilant /s/. We believe that a more appropriate palatal mouthguard design for custom-made mouthguards can be made based on the balance of aeroacoustical effects and mechanical requirements.