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Within the cochlea, the basilar membrane (BM) is coupled to the reticular lamina (RL) through three rows of piezo-like outer hair cells (OHCs) and supporting cells that endow mammals with sensitive hearing. Anatomical differences across OHC rows suggest differences in their motion. Using optical coherence tomography, we measured in vivo and postmortem displacements through the gerbil round-window membrane from approximately the 40–47 kHz best-frequency (BF) regions. Our high spatial resolution allowed measurements across the RL surface at the tops of the three rows of individual OHCs and their bottoms, and across the BM. RL motion varied radially; the third-row gain was more than 3 times greater than that of the first row near BF, whereas the OHC-bottom motions remained similar. This implies that the RL mosaic, comprised of OHC and phalangeal-process tops joined together by adhesion molecules, is much more flexible than the Deiters' cells connected to the OHCs at their bottom surfaces. Postmortem, the measured points moved together approximately in phase. These imply that in vivo, the RL does not move as a stiff plate hinging around the pillar-cell heads near the first row as has been assumed, but that its mosaic-like structure may instead bend and/or stretch. [ABSTRACT FROM AUTHOR]

Objective: Conventional otoscopes and oto-endoscopes, which are used to examine the tympanic membrane (TM), do not provide tomographic information. Optical coherence tomography (OCT) non-invasively reveals the depth-resolved internal microstructure of the TM with very high spatial resolution. We designed this study to examine the TMs with middle ear diseases using a handheld otoscope employing 860nm spectral domain (SD)-OCT, combined with video camera and to demonstrate the clinical applicability of this system. Design: A total of 120 patients with otologic symptoms were enrolled. TM images were obtained using the handheld OCT-based otoscope (860nm central wave length, 15 lm axial resolution, 15 lm lateral resolution, and 7mm scanning range using relay lens). Both OCT and oto-endoscope images were compared according to the clinical characteristics such as perforation, retraction, and postoperative healing process. Results: The objective grade about the thickness of perforation margins and the accurate information about the extent of TM retraction that was not distinguishable by oto-endoscopic exam could be identified using this system. The postoperative healing process of TMs could be also followed using the OCT device. Conclusion: These analyses from the surgeon-oriented perspective suggest another useful application of the handheld OCT device. [ABSTRACT FROM AUTHOR]

• Tensor tympani and stapedius muscles were pulled in human cadaver temporal bones. • Muscle pulls reduced low-frequency middle-ear sound transmission and group delay. • Tensor tympani pull changed the tympanic membrane shape and umbo position. • Modulations of middle-ear delay by the muscles could aid sound localization. • Middle-ear muscles could help the brain align head-centered auditory and ocular-centered visual representations of the environment. The three-bone flexible ossicular chain in mammals may allow independent alterations of middle-ear (ME) sound transmission via its two attached muscles, for both acoustic and non-acoustic stimuli. The tensor tympani (TT) muscle, which has its insertion on the malleus neck, is thought to increase tension of the tympanic membrane (TM). The stapedius (St) muscle, which has its insertion on the stapes posterior crus, is known to stiffen the stapes annular ligament. We produced ME changes in human cadaveric temporal bones by statically pulling on the TT and St muscles. The 3D static TM shape and sound-induced umbo motions from 20 Hz to 10 kHz were measured with optical coherence tomography (OCT); stapes motion was measured using laser-Doppler vibrometry (LDV). TT pulls made the TM shape more conical and moved the umbo medially, while St pulls moved the umbo laterally. In response to sound below about 1 kHz, stapes-velocity magnitudes generally decreased by about 10 dB due to TT pulls and 5 dB due to St pulls. In the 250 to 500 Hz region, the group delay calculated from stapes-velocity phase showed a decrease in transmission delay of about 150 µs by TT pulls and 60 µs by St pulls. Our interpretation of these results is that ME-muscle activity may provide a way of mechanically changing interaural time- and level-difference cues. These effects could help the brain align head-centered auditory and ocular-centered visual representations of the environment. [ABSTRACT FROM AUTHOR]

We investigated the use of optical coherence tomography (OCT) to measure several materials immersed in optical adhesives. The effects of variations in the concentration, physical characteristics, and thickness of the materials were studied, and these parameters were found to significantly affect the OCT measurement. The materials were selected for their distinct spectral properties in the infrared region. To ensure reliability, we acquired images using a scanning electron microscope after performing the semiconductor production process. We verified the feasibility of the application of OCT for defect inspection and product verification of touch-screen panels. [ABSTRACT FROM AUTHOR]

In this study, we report the applicability of two different Optical Coherence Tomography (OCT) technologies for inspecting Light Emitting Diode (LED) structures. Sectional images of a LED were captured using a Spectral Domain OCT (SD-OCT) system and a Swept Source OCT (SS-OCT) system. Their center wavelengths are 850 and 1,310 nm, respectively. We acquired cross-sectional two dimensional (2D) images of a normal LED and extracted sectional profiles to inspect possible wire disconnection that may be present in the LED manufacturing process. The SD-OCT and SS-OCT images were compared with each other in the same sample to study their advantages. The distribution of fluorescence material was observed more clearly with the SD-OCT of 850 nm wavelength, whereas the status of wire connection was clearer in the SS-OCT images with 1,310 nm wavelength. In addition, the volume of the fluorophore space was calculated from the OCT images. This is the first report that a nondestructive optical imaging modality such as OCT can be applied to finding screen defects in LED. We expect this method can improve the inspection efficacy over traditional inspection methods such as Charged Coupled Device (CCD) camera or X-ray instruments. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the study of accelerated pavement testing (APT) with test variables of temperature and air void ratio, which are important factors that influence rutting. The purpose of the study was to use the APT results to calibrate a laboratory rutting model for asphalt concrete (AC) mixtures and to develop an appropriate rutting model for AC pavements. The test specimen for the APT was prepared as a pavement system with an AC layer of 30cm, subbase of 30cm, and subgrade of 180cm. The experimental variables were chosen to be the important factors that influence the rutting of AC pavement: temperature (50°C) and air void ratios (7.31% and 10.57%). A multi-depth deflectometer was installed at depths of 12 and 30cm from the AC pavement surface to measure the plastic and resilient strains, which are necessary for the development of the rutting model. The result was used to examine the rutting models of AC pavement layers suggested by the AASHTO 2002 model as well to calibrate a laboratory rutting model. [ABSTRACT FROM AUTHOR]

A method for designing an airport concrete pavement (ACP) that can withstand environmental loads as well as traffic loads is presented. Information on ACPs for which double dual tandem landing gears were used for design aircrafts was collected and the stresses induced on the slabs when environmental loads and traffic loads were simultaneously applied were predicted with the finite-element analysis program FeaFaa. In addition, a maximum tensile stress regression model of ACP slabs was developed using the statistical analysis program SPSS. When environmental and traffic loads were simultaneously applied, the maximum tensile stress obtained with the finite-element method was significantly different from that obtained using Westergaard's equation of edge loading only in traffic loads. Therefore, the fatigue model in the US Federal Aviation Administration's AC 150/5320-6E design method was corrected to be appropriate for this study. Using the stress regression model developed in this study and the corrected fatigue model, the thickness and joint spacing of existing ACP slabs were redesigned and compared with existing airport pavements. Previously, only the thickness of a slab was designed and the joint spacing was empirically determined. However, from the results of this study, a slab's thickness and joint spacing can be designed mechanistically. [ABSTRACT FROM AUTHOR]