bluuebunny/crossref_metadata_2025 huggingface dataset:
Geoacoustic inversion for bottom parameters in the deep-water area of the South China Sea
Authors: Wu Shuanglin , Li Zhenglin , Qin Jixing
Published: October 2018

The properties of bottom acoustic parameters are greatly influenced on sound field prediction. Acoustic parameters in deep water are not well understood. We will discuss experience with geoacoustic inversion of transmission-loss (TL) data from 100 to 600 Hz from deep water regions. Bottom acoustic parameters are sensitive to the TL data in the shadow zone of deep water. Multiple steps TL inversion method is proposed to invertsound speed, density and attenuation in deep water. Both a uniform liquid half-space and a two-layer geoacoustic profile are assumed. Sound speeds of bottom are inverted by using TL data in the shadow zones at low frequency obtained in an acoustic propagation experiment conducted in the South China Sea (SCS) in summer 2014. Meanwhile, bottom densities are estimated combining with the Hamilton sediment empirical relationship. Attenuation coefficients at different frequencies are then estimated from the long range TL data by using the known sound speeds and densities as a constraint condition. The nonlinear relationship between attenuation coefficient and frequency is given in the end. The inverted bottom parameters can be used to forecast the transmission loss in deep water area of SCS very well.
Beyond the chamber, plate, or digital reverb. Electronic architecture and the acoustically flexible recording environment
Authors: Barbar Steve , Berger Russ
Published: October 2018

For more than 20 years, Electronic architecture has been successfully integrated in a variety of venues for live performances. We will discuss how the inclusion of this technology in recording facilities has both altered recording methods, and expanded clientele at three recording facilities: The Dimenna Center for Classical Music is New York’s premier facility for recording acoustic music. Recent projects include the soundtrack for the Coen Brothers’ feature film Hail, Caesar!; the Grammy-nominated cast album for The King and I featuring Kelli O’Hara and Ken Watanabe; the soundtrack for James Schamus’ Indignation; a Grammy Award-winning album by Room Full of Teeth; and an upcoming harmonia mundi release featuring Pablo Heras-Casado and Orchestra of St. Luke’s. Sweetwater Music has recently expanded its recoding capabilities and upgraded the E-Coustic system with the latest hardware and software. Recent sessions include the Counting Crows, Adrian Belew, and Steve Curtis Chapman. Fo’Yo’ Soul is Grammy award winning Kirk Franklin’s new facility in Arlington Texas designed by Russ Berger. The studio (Uncle Jesse’s Kitchen) features one of the first E-Studio product installations that allows acoustical conditions in the studio to be adjusted at the touch of a button, allowing soloists and ensembles to record in an environment tailored for comfort and creativity.
Audio rendering based on separation of direct and diffuse sound
Authors: Ando Akio
Published: October 2018

Multichannel audio with many channels can capture the sound field with higher sense of reality. In the reproduction, however, a system with many loudspeakers can be setup only in the special room like a studio. Therefore, the audio rendering that converts the number of channels should be necessary in the reproduction. Many studies have been made on the audio rendering. These methods were based on the directional information of channels. On the other hand, there are two kinds of sense of reality: the reality by the object sound (“object reality”) and that by the field sound (“field reality”). There are also two kinds of sound in the multichannel audio signal: the direct and diffuse sound. The direct sound brings the object reality, and the diffuse sound brings the field reality. Since the conventional rendering methods rely on the directional information, it may be difficult to handle the diffuse sound. In this paper, we address a rendering method based on the separation of direct and diffuse sound. Since the direct sound can be rendered by the conventional method, we clarify the requirements for the diffuse sound rendering from the viewpoint of sound reflection in the room.
Please turn it down!
Authors: Plsek Thomas J.
Published: October 2018

Sustained levels of 95 to 100 dBA and beyond are not uncommon in rock and pop music genres, leading to daily noise doses that are 100% or more above the recommendations established by the National Institute for Occupational Safety and Health. There are three options of addressing this situation: leaving the environment, using hearing protection, and turning the offending level down. It is the last of these that I will explore. The first two listed have problems with implementation. Using Leq measurements of various ensemble performance situations, the question addressed is whether or not musicians can learn to control the level of their instruments efficiently enough, referencing NIOSH recommended noise exposures, to make a meaningful difference in exposure time without significantly sacrificing the quality of the music.
Nature as muse: How cave acoustics can help us be more imaginative with our reverb choices
Authors: Lysoivanov Yuri
Published: October 2018

The cave is an oft-overlooked option for the audio practitioner's toolbox. With the aid of the science team from the National Park Service, we recorded impulse responses and analyzed the properties of several acoustically distinctive spaces inside Mammoth Cave in Kentucky, the longest cave network in the world. An understanding of the unique characteristics of these areas can help inform more creative approaches in reverb selection and educate us to be more innovative in music, sound, and room design.
Forward masking recovery in bottlenose dolphins (Tursiops truncatus): Auditory brainstem responses to paired-click stimuli in high-pass masking noise
Authors: Mulsow Jason , Coffinger Sean P. , Finneran James J. , Burkard Robert F.
Published: October 2018

Adaptation is a fundamental process in the auditory system and underlies the automatic gain control system of echolocating bottlenose dolphins. As pulse-echo delay increases, auditory brainstem response (ABR) amplitudes to the echoes progressively increase. This study examined adaptation across cochlear frequency regions using a paired-click (i.e., forward masking) paradigm and high-pass masking noise. Bottlenose dolphins passively listened to paired click stimuli (20–160 kHz “pink” spectra). A “conditioning” click was followed by a “probe” click with equal amplitude and a time delay ranging from 125 to 750 μs. ABRs to click pairs were obtained with and without high-pass masking noise that precluded the basal turn of the cochlea from responding to the click stimuli. The ABR evoked by a single click (temporally aligned with the first click of the paired-click condition) was subtracted from the click-pair ABR to visualize the response evoked by the probe click. Probe ABR amplitudes recovered linearly with increasing delay relative to the conditioning click, and were approximately 70% of full response amplitude at 750-μs delay. Paired-click interval ABR amplitude recovery functions were similar for the unmasked and high-pass masked conditions. [Work sponsored by ONR.]
The auditory attributes of Golden Eagles: Do Golden (Aquila chrysaetos) and Bald Eagles (Haliaeetus leucocephalus) share the same auditory space?
Authors: Walsh Edward J. , Nelson Peggy B. , Ponder Julia , Milliren Christopher , Feist Christopher , Marr Jeff , Redig Patrick , McGee JoAnn
Published: October 2018

According to the U.S. Fish and Wildlife Service (2018), fatalities associated with wind turbine collisions have been reported for more than 200 bird species. Furthermore, based on statistical models of industry growth it has been suggested that as many as 1.4 million bird fatalities/year could be realized if the Department of Energy (DOE) wind energy goals are achieved; i.e., wind energy supplying 20% of total U.S. energy needs by 2030. Although passerine bird fatalities are most commonly reported, raptors that hunt by day, including bald and golden eagles, are the second most frequent casualties of turbine collisions. To address this concern, deterrence protocols designed to discourage eagles from encroaching into wind energy facility air spaces and thereby constrain the degree of risk to which birds are exposed are under investigation. As part of an effort to guide development of acoustic deterrence protocols, we report that the responsive frequency range of golden eagles is similar to that reported for bald eagles; upper and lower frequency limits of hearing are approximately 6.0 and 0.3 kHz, respectively. Suprathreshold response profiles measured in golden eagles exhibit standard features that will be compared with those of bald eagles. [Work supported by DOE grant #DE-EE0007881.]
Estimation of the acoustic environment through machine learning techniques
Authors: Viquez Oscar A. , Fischell Erin M. , Schmidt Henrik
Published: October 2018

The material composition of the bottom of shallow waterways can have significant effects on the corresponding acoustic environment, which autonomous underwater vehicles (AUVs) rely upon for sensing, navigation, and communication. Techniques that require an adequate environmental model are often used onboard AUVs to interpret the sensor data, but such techniques are often sensitive to even small deviations between the model and reality. A proposed approach to reduce this deviation is to use data from local soil and bathymetry surveys to generate environmental model approximations that may be loaded onto the vehicle in advance. During the early stage of deployment, the vehicle uses a K-nearest-neighbor classification approach to compare field calibration measurements with the various models, and select the most suitable solutions for use during the remainder of the active mission. Acoustic field simulations based on the environmental models are produced using normal mode theory as well as wavenumber integration, then compared with field array data. The techniques developed here could be used to facilitate the use of environment-sensitive approaches for detection and tracking during autonomous operations. [Work supported by the Office of Naval Research.]
Estimating the probability density function of transmission loss in an uncertain ocean using machine learning
Authors: Lee Brandon M. , Dowling David R.
Published: October 2018

Predicted values of transmission loss (TL) in ocean environments are sensitive to environmental uncertainties. The resulting predicted-TL uncertainty can be quantified via the probability density function (PDF) of TL. Monte Carlo methods can determine the PDF of TL but typically require thousands of field calculations, making them inappropriate for real-time applications. Thus, a variety of alternative techniques based on polynomial chaos, field shifting, modal propagation in ocean waveguides, and spatial variations of TL near the point(s) of interest have been proposed. This presentation describes an innovative approach to estimating the PDF of TL based on nominal TL, ocean environmental parameters, and machine learning. This approach has two main challenges. First, appropriate representations must be found for ground-truth PDFs of TL generated from Monte Carlo calculations so that a neural network can be constructed to predict each parameter of the estimated PDF of TL. Four such representations are considered here. And second, a framework must be developed to generate training data for the neural networks. A proposed framework that predicts candidate environments’ training utility without computing any PDFs of TL is described. The performance of this approach is analyzed and compared to that of prior techniques. [Sponsored by ONR.]
Using machine learning in ocean noise analysis during marine seismic reflection surveys
Authors: Abadi Shima
Published: October 2018

Marine seismic reflection surveys use repetitive broadband sound signals to image the structure of the seafloor. High energy sound signals generated by airguns are recorded by single or multiple long horizontal hydrophone arrays towed behind the vessel. Marine seismic reflection surveys raise concern over their effects on marine animals. In particular, there is concern about (1) the impact of the airgun sound power level on marine mammals and (2) the increase in the background noise level caused by the reverberation between shots which may mask marine mammals’ vocalizations and degrade the performance of the passive acoustic monitoring systems. Quantifying these effects is a challenging task due to the complexity of local geology, seafloor topography, and uncertainty in water properties. In this study, a machine learning approach is used to predict the airgun sound power level and the reverberation level off the ocean floor. The data utilized in this study are from the COAST (Cascadia Open-Access Seismic Transects) seismic reflection survey conducted with the R/V Marcus Langseth in July 2012. This experiment spanned a wide range of water depths from the continental shelf to deep water. Data was recorded by an 8-km horizontal array with 636 hydrophones sampled at 500 Hz.
Source localization using a compact tetrahedral array
Authors: Miller James H , Potty Gopu R. , Tripathy Aditi , Tazawa Makio , Amaral Jennifer , Vigness-Raposa Kathleen J. , Lin Ying-Tsong , Newhall Arthur
Published: October 2018

We localized sound sources collected on a compact tetrahedral hydrophone array in a continental shelf environment south of Block Island, Rhode Island. The tetrahedral array of phones, 0.5 m on a side, was deployed to monitor the underwater sound of construction and operation of the first offshore wind farm in the United States. Signals from shipping and marine mammals, including fin whales, humpback whales, and right whales, were detected on the array. Directions of arrival (DOAs) for a number of signals were computed using a time difference of arrival technique. Given the DOAs, ranges were estimated using supervised machine learning techniques outlined by Niu et al. (JASA, 2017). The approach was tested using simulated data from Kraken assuming environmental information consistent with this continental shelf environment. Performance on signals from individual ships and marine mammals is presented. Ship localizations are compared to Automated Identification System (AIS) fixes. An error analysis is also presented. [Work supported by the Office of Naval Research and the Bureau of Ocean Energy Management.]
Picosecond opto-acoustics for the remote ultrasonography of single cells
Authors: Audoin Bertrand
Published: October 2018

Picosecond ultrasonics (PU) is a technique that offers the possibility to generate and detect acoustic waves remotely with an unequalled frequency bandwidth. After decades of developments and applications for researches in solid-state physics, a vast application field was recently demonstrated for PU in biology and medicine. The technique allows imaging single cells with a lateral resolution limited by optics and with the mechanical properties as the contrast mechanism. The opto-acoustic images can reveal the structure of the cell nucleus, the fine details of the actin network and of the adhesion pattern. In addition to imaging capabilities, quantitative analysis of the interaction of the GHz acoustic waves with the complex cell medium provides information on the cell nanostructure. For instances, the standard deviation of impedance data we measured for single nuclei revealed differences between different cell types arising from the multiplicity of local chromatin conformations within the nucleus. Moreover, the distribution of the cell-substrate interface stiffness we identified allowed us to separate the contribution of passive and active adhesion processes. The technique allows thus gaining new insights into cell mechano transduction.
Insights into the roles of radiation forces in bubble mediated sonothrombolysis
Authors: Acconcia Christopher , Wright Alex , Kiezun Kevin , Goertz David
Published: October 2018

It is increasingly recognized that radiation forces on bubbles are relevant to a range of therapeutic applications such as sonothrombolysis. In this paper, we discuss work using high speed microscopy to investigate the interactions between ultrasound stimulated bubbles and the boundary of biologically relevant materials. Initial studies with fibrin gels (clots), demonstrated that bubbles could be stimulated to deform, penetrate, and damage the fibrin network. This highlighted two distinct processes where radiation forces play a central role: transporting bubbles from a vessel lumen to a target boundary and facilitating therapeutic effects at the target. To investigate the transport process, experimental data were acquired to assess translational bubble dynamics as a function of size and exposure condition, and this data were used to calibrate a model where both shell and history forces are captured. Experiments and modeling showed that both exposure scheme and flow rate can profoundly influence the number and size distribution of bubbles reaching a target site on a vessel boundary. Once at the boundary, cyclical deformations are induced by the bubble extending well into the material, and these are asymmetric on the forcing and recovery cycles. Deformation, as well as penetration and damage are found to be highly dependent on bubble size and exposure schemes. An improved understanding of these complex processes may facilitate improvements in applications involving large vessels, such as sonothrombolysis.
Efficient rendering of saxophone sound by modal synthesis and wave scattering
Authors: Maestre Esteban , Scavone Gary , Smith Julius O.
Published: October 2018

We present a digital filter design technique for the modeling of impedance and radiation transfer functions as measured from an alto saxophone. For each fingering position, both the input impedance and sound radiation are jointly modeled via a recursive parallel filter structure akin to a modal expansion, with the filter coefficients estimated in the frequency domain by means of constrained pole optimization and least-squares. For modeling the transition between fingering positions, we propose a simple model based on linear interpolation of impedance and radiation models. For efficient sound rendering, the common impedance-radiation model is used to construct a joint reflectance-radiation filter realized as a digital waveguide termination that is interfaced to a reed model based on non-linear scattering.
Physics-based resynthesis of clarinet performance using numerical optimization
Authors: Chatziioannou Vasileios , Pàmies-Vilà Montserrat , Schmutzhard Sebastian , Hofmann Alex
Published: October 2018

The functioning of musical instruments has been an active area of research since the beginning of the last century, using both theoretical approaches and experimental measurements. Regarding wind instruments, the subtleties of embouchure control are of particular interest, since the actions of the player's lips and tongue evade direct measurement. One approach towards analyzing such actions is by extracting relevant information from signals that allow non-intrusive measurements, such as the blowing pressure, the mouthpiece pressure and the reed bending [Pàmies-Vilà et al. (2018) Frontiers in Psychology 9: 617]. Alternatively, it is possible to formulate a physical model of the player-instrument interaction and estimate the actions of the player while resynthesizing the oscillations of the instrument [Chatziioannou et al. (2012) Acta Acustica united with Acustica 98(4): 629–639]. This work presents such an attempt based on measurements carried out on expert clarinet players. An excerpt of Weber's clarinet concerto No. 2 is performed by the players and resynthesized using a refined physical model taking embouchure effects into account. Using inverse modeling, the underlying model parameters are being tracked in order to extract information on the physical phenomena that take place at the excitation mechanism.
Acoustical impedance of brass instruments: Measurements and modeling for undergraduate physics course
Authors: Hoffman Kurt
Published: October 2018

We will present recent work developing experimental and modeling exercises for an intermediate physics course focusing on vibrations and waves with applications to acoustics. The measurements described here utilize a simple acoustical impedance measuring system that can be used to identify the resonant frequencies of a variety of brass instruments. For modeling purposes, we will have the students build approximate brass instruments from PVC tubing and couplers to simplify the shape of the instrument. Despite the abrupt changes in radius of the PVC instrument, adjustment of the cylindrical tube lengths results in a regular pattern of resonances that matches quite well to the first five or six harmonic intervals required in brass instruments. We have developed a Mathematica based program to model the impedance of the PVC brass instruments. The model results can be compared to the measured impedance resonances of the tube. In addition, the resonances can also be measured by lip buzzing the instrument to demonstrate the modification of the resonance frequencies by the vibrating lips at the mouthpiece. We will also discuss the some pedagogical benefits of using acoustical systems as an introduction to solving differential equations and boundary value problems.
Is anything radically new in noise control research?
Authors: Horoshenkov Kirill , Swift Mark
Published: October 2018

This paper attempts to review the state of art of noise control research globally and answer a key question: Has anything been radically new in noise control research lately? There is anecdotal evidence that no radical noise control solution has emerged from noise control research since the invention of active noise control by Paul Lueg in 1936 (U.S. Patent 2,043,416). Among passive noise control solutions used for sound absorption the market is dominated by mineral wool and fibreglass (43% in 2017, Global Insulation Market Report, 2024). Technical foams used for acoustic absorption cover pretty much of the rest. Similar situation is for common solutions used for noise and vibration insulation. Their acoustical properties and in-situ performance can be predicted within experimental and material parameter uncertainties using a commercial package such as Comsol or semi-empirical models such as by Delany and Bazley. There seem no radical solutions has emerged recently to challenge this status quo. Metamaterials are one promising solution for the future, but they remain largely in the realm of academic laboratories or fancy theories. Therefore, another key question is: What has true impact of noise control research been so far and what fundamental ideas need to emerge to radically improve this situation?
Neural entrainment to missing pulse rhythms
Authors: Large Edward W. , Wasserman Charles S. , Skoe Erika , Read Heather L.
Published: October 2018

Pulse is the perceptual phenomenon in which an individual perceives a steady beat underlying a complex auditory rhythm, as in music. The neural mechanism by which pulse is computed from a complex rhythm is a topic of current debate. Neural Resonance Theory (NRT) predicts that synchronization itself is the neural mechanism of pulse perception and is supported by studies that demonstrate neural entrainment to complex rhythms. Here we report a behavioral and an EEG study of stimulus rhythms that have no spectral energy at the perceived pulse frequency. A dynamical systems model based on NRT predicts that endogenous oscillation will emerge at the “missing” pulse frequency. We observed 1) strong pulse-frequency steady-state evoked potentials (SS-EPs) to isochronous and missing pulse rhythms, but not to a random control; 2) strong coherence between model-predicted SS-EPs and brain responses for all rhythms; 3) differing pulse-frequency activation topographies for missing pulse rhythms versus isochronous and random controls; and 4) differing frequency-following response (FFR) amplitudes for events in missing pulse rhythms versus isochronous and random rhythms. These observations support the theory that the perception of pulse results from the entrainment of emergent population oscillations to stimulus rhythms.
Neural convergence of rhythm and language: From trait to state
Authors: Yu Leyao , Myers Brett , Gordon Reyna L.
Published: October 2018

As a growing literature has shed light on associations between cognitive mechanisms for music and language, an important role of rhythm and timing is emerging for individual differences in language skills in children. In this talk we will address: A) how musical rhythm relates to individual differences in spoken grammar traits in children ages 5 to 8; and B) potential neural synchronization by which an overlap in processing rhythm and language might occur. Results in the current study show strong correlations between musical rhythm perception and spoken grammar production, converging with prior work. In addition, we found that individual differences in neural synchronization to the speech envelope (measured with EEG) during passive listening are associated with performance on prosodic and musical rhythm behavioral task performance. Additional EEG data (during musical rhythm beat perception) has also been collected from N = 50 children with typical language development and N = 13 children with grammatical impairments (all children had non-verbal IQ in the normal range); data analysis is underway. In light of these studies and others showing that rhythmic listening can impact grammatical task performance, we will discuss other ongoing translational work that takes first steps towards exploring a causal influence of rhythm on grammar states.
Redundancy in the speech signal helps amusics perceive prosody
Authors: Tierney Adam
Published: October 2018

Speech is information dense, rapidly conveying segmental, semantic, syntactic, and prosodic information through the manipulation of a small handful of acoustic cues. As a result, impaired perception of one of these cues could impede acquisition of linguistic structure at multiple levels. For example, impaired perception of temporal patterns has been linked to developmental language delays. However, auditory impairments do not necessarily lead to language delays, suggesting that some people are able to compensate for difficulties with sound perception. This may be due to the perceptual redundancy of speech—the fact that multiple auditory dimensions often convey the same linguistic information. We tested this hypothesis by examining prosody perception in individuals with amusia, i.e., severe difficulties with the perception of musical melodies. First, we find that amusics show decreased functional connectivity between auditory and motor cortices during speech perception, suggesting that amusia is a domain-general deficit in pitch perception stemming from decreased auditory-motor connectivity. Second, we find that amusics compensate for their impairment by relying upon preserved perceptual abilities, suggesting that redundancy makes speech somewhat robust to individual differences in perceptual skill.
Improving lyrical intelligibility in live music and concert settings: Evaluating the application of alternative sound reinforcement techniques
Authors: Koshiol Jared H. , DeBlasio Greg
Published: October 2018

Thirteen individuals were asked to listen to eight short passages of music from two songs containing sung lyrics. They compared the music as it was presented at 94dBA through three different systems; one control emulating a standard live music performance, another with the vocal channel assisted by digital effects (Compression, an Adaptive Limiter, EQ and a Harmonic Exciter), and a third where vocals were removed from the left and right speakers and instead played through a single center speaker of the same make while instruments remained in the left and right speakers. This third design is similar to common mixing of 5.1 theatrical audio. Participants indicated their perception of lyrical intelligibility and pleasurability of the sound for each passage and were asked to ignore artistic choices. Responses indicated that the use of effects processing for vocals somewhat improved lyrical intelligibility and pleasurability for one song, while slightly decreasing these values for the other. The center speaker system for vocals greatly improved (in one case almost doubled) listeners’ ability to perceive the lyrics as well as their overall enjoyment of the sound. This improvement is likely linked to spatial hearing; a musical extension of the Cocktail party effect.
Efficient emission of directional sound waves by using subwavelength meta-cavities
Authors: Zhang Likun , Fan Xudong , Zhao Jiajun , Liang Bin , Cheng Jianchun , Wu Ying , Landi Maryam
Published: October 2018

Efficient emission of directional sound waves is critical in imaging and communication, yet is held back by the inefficient emission at low frequencies, especially for a small source. A subwavelength enclosure with degenerate Mie resonances was implemented to experimentally enhance the sound power emitted to the far field where the radiation directivity pattern is preserved [L. Maryam et al., Physical Review Letters 120 (11), 114301, 2018]. When considering the efficient emission of directional sound waves, a subwavelength meta-cavity of hybrid resonances can be used to convert the monopole sources to multipole emission [X. Fan et al., Physical Review Applied 9 (3), 034035, 2018] or Mie resonances with spatial asymmetry can be used to even emit directional sound beams [J. Zhao et al., Scientific reports 8 (1), 1018, 2018]. The work offers a practical path toward applications that demand miniaturization of speakers for efficient emission.
Finite element modeling of fluid-saturated metallic foams from micro-computed tomography
Authors: Cops Mark J. , McDaniel James G. , Magliula Elizabeth A. , Bamford David J.
Published: October 2018

Open-cell metallic foams are high stiffness-to-weight cellular materials whose microstructure allows for saturation of viscous liquid. Such a composite has advantages for underwater sound absorption over traditional rubbers due to minimal compression from hydrostatic pressure, composite tunability, and potential for specific gravity less than one. Semi-phenomenological and hybrid numerical models have been shown to predict sound absorption performance of metallic foams, however difficulty arises in determining parameters for the numerical models such as tortuosity, viscous characteristic length, thermal characteristic length, and flow resistivity. Such models also assume that the porous frame is rigid, an assumption valid for only a limited frequency range. In this presentation, finite element models of fluid-saturated metallic foams are created from micro-computed tomography scans and analyzed to determine sound absorption performance. The advantage of this method is that the entire foam microstructure and surrounding fluid can be accurately modeled through a finite element mesh. In addition, experimental measurement of model parameters is not required and the rigid frame assumption can be removed.
Understanding the influence of grain scattering noise on array imaging and defect characterisation
Authors: Drinkwater Bruce W. , Bai Long , Velichko Alexander
Published: October 2018

The performance of ultrasonic inspection degrades for coarse grained materials because of the multiple scattering effects caused by the material microstructure. The influence of grain scattering noise on detection and characterisation of defects is studied in this paper. Two parameters, mean grain size and grain size variation, are used to describe a particular grain structure, which is included in a finite element (FE) model to simulate the array data of a defect with the presence of grain noise. The ultrasonic attenuation and multiple scattering effects become more significant at high frequencies, and so a low frequency is shown to be preferable for defect detection. However, the frequency should also be higher than a certain limit for the defect to be characterisable based on its scattering matrix. Here we extract the noise scattering matrix due to the grain scattering from the simulated array data and use its statistical distribution is used to determine the characterisation uncertainty. Preliminary results obtained at 2.5 MHz for stainless-steel show that 1 mm (i.e., 0.45λ) cracks can be sized reliably when the mean grain size is less than 0.2 mm. However, when the mean grain size exceeds 0.15 mm, it is difficult to distinguish the 1 mm cracks from volumetric defects of the same size.
Experimental research on fatigue performance of aero-structure under two combined loads
Authors: Liu Zhihong , zhang Li , Liu Xing , Guo Dingwen , Pan Kai
Published: October 2018

In this paper, a new engineering test method which put forward the initial stage of aircraft design, bearing both acoustic and static loads, is carried out in Lab. From currently test effect, it could accurately simulate the real situation of aircraft panel under hydrostatic load and acoustic load, and the test result shows that the structure presents plastic deformation under the combined action of acoustic load and static load, which differs from the common failure mode of the structure under the action of the single strong noise load. Furthermore, the proposed method could provide guidance to support aircraft type selection.
Aging effects on categorical perception of Mandarin tones in noise
Authors: Xu Can , Wang Yuxia , Yang Xiaohu , Liu Chang
Published: October 2018

The current study aimed at investigating the aging effect on the categorical perception of Mandarin lexical tones with varied fundamental frequency (F0) contours in noise. Mandarin tone identification and tone discrimination in quiet and noise were measured for younger and older listeners in a categorical perception paradigm where the stimuli continua varied their F0 contour systematically from the level to the rising/falling tones. Results reported that older listeners, in contrast with their younger counterparts, performed with less stimulus-tuned changes in both identification and discrimination functions and smaller peakedness in the discrimination function for both level-rising and level-falling tones. The aging effects on Mandarin tone categoricality were observed in both quiet and noise. Moreover, noise aggravated the aging effects, especially with the high SNR condition. Plus, older listeners’ identification and discrimination functions in CP paradigm positively correlated with their performance in general speech identification in noise; such correlation was not found with younger listeners. Our study suggested that older listeners had less categoricality in both identification and discrimination functions for the level-rising and level-falling tones, probably due to the aging-related decline in temporal processing.
Evaluation of axially transmitted shear waves in cortical bone: Experimental and simulation study
Authors: Bustamante Diaz Leslie V. , Saeki Masaya , Matsukawa Mami
Published: October 2018

Quantitative ultrasound has become a useful technique for bone assessment. Axial transmission technique has demonstrated various advantages over the through-transmission technique. Longitudinal wave and Lamb modes measurements in bone have been extensively reported while shear waves have been neglected. Shear wave velocities are lower than longitudinal wave velocities and can be useful for bone torsional strength characterization. In this study, plate samples were fabricated from bovine cortical bone. An ultrasonic pulse was transmitted along the long axis of the sample and shear waves were experimentally detected in the MHz range. Using time-of-flight technique, velocities were determined considering three different points of the received wave as a function of the ultrasound incident angle, transmitter-receiver distance and bone plate thickness. The observed shear wave velocities varied in a range (1630 to 1860 m/s) depending on the incident angle and the particular wave path, due to the anisotropy and heterogeneity of the bone structure. A 2D simulation using FDTD method was developed to understand the wave propagation phenomenon. Experimental and simulation results showed good agreement respect to the shear wave velocity estimated in a through-transmission measurement (1720 m/s), specially in angles close to the critical angle (60°).
Inverse characterization of radius bone using low-frequency ultrasonic guided waves
Authors: Pereira Daniel , Fernandes Julio , Belanger Pierre
Published: October 2018

The success of the cortical bone characterization using the axial transmission is highly dependent on the inversion model used to match experimental data with the true bone properties. Simplified models such as plate or cylinder are typically used in the literature. In our previous work, a more elaborate model based on a bone-like geometry built using semi-analytical finite element (SAFE) method was introduced. The model was successfully implemented in an inverse characterization routine using laboratory-controlled measurements on bone phantoms. Thus, the aim of this work is to apply the proposed inverse scheme on the characterization of ex-vivo radius samples. In order to do so, five radiuses were taken from donors aged between 53 and 88 years old and tested using typical axial transmission configuration. Ultrasonic guided wave modes were excited at low-frequency (100-400 kHz) using a piezoelectric transducer and measured using a laser interferometer at the middle of the diaphysis. The measured velocities were systematically compared to velocities obtained with the SAFE model in order to predict the cortical bone properties. For each sample, four parameters were estimated: (1) Young’s modulus; (2) density; (3) thickness; and (4) outer diameter. The results showed a notable correlation of the thickness and outer diameter with respect to the μCT images of the samples, while a less significant correlation was observed for the Young’s modulus and density with respect to the gray level of the μCT images.
Microbubble gas volume: A unifying dose parameter in blood-brain barrier disruption by focused ultrasound
Authors: Song Kang-Ho , Harvey Brandon , Borden Mark
Published: October 2018

Focused ultrasound with microbubbles is being developed to transiently, locally and noninvasively disrupt the blood-brain barrier (BBB) for improved pharmaceutical delivery. Prior work has demonstrated that, for a given concentration dose, microbubble size affects both the intravascular circulation persistence and extent of BBB opening. In this study, we independently measured the effects of microbubble size (2 vs. 6 μm diameter) and concentration, covering a range of overlapping gas volume doses (1–40 μL/kg). We first demonstrated precise targeting and a linear dose-response of Evans Blue dye extravasation to the rat striatum for a set of constant microbubble and ultrasound parameters. We found that dye extravasation increased linearly with gas volume dose, with data points from both microbubble sizes collapsing to a single line. A linear trend was observed for both the initial sonication and a second sonication on the contralateral side. Based on these results, we conclude that microbubble gas volume dose, not size, determines the extent of BBB opening by focused ultrasound (1 MHz, ~0.5 MPa at the focus). Finally, using optimal parameters determined for Evan blue, we demonstrated gene delivery and expression using a viral vector one week after BBB disruption.
The Effect of Prior Tennis Experience on Wheelchair Tennis Players’ Visual Search
Authors: Hunfalvay Melissa , Murray Nicholas
Published: October 2018

The purpose of this study was to examine whether prior biped tennis playing experience results in different visual search strategies compared with no prior biped playing experience. A total of 32 wheelchair (WC) tennis players, 17 males and 15 females, ranked between 1 and 16 on the International Tennis Federation rankings participated in this study. Half the players had prior experience playing tennis as a biped player, and half had no prior experience in biped tennis. The athletes viewed 18 different serves from an expert WC player while their gaze was monitored using eye tracking. Results revealed significant differences between the groups in fixation duration and number of fixations. Differences were also found in fixation locations and durations across biomechanical phases of the serve. The WC only players had more fixations for shorter periods than did WC with biped players in the ritual phase. In the preparatory and execution phases, however, the WC only players had fewer fixations for longer duration than the WC with biped players. Results are discussed in terms of long-term memory structures, learning, and considerations when coaching and training WC tennis players.
The Utility and Cross-Validation of a Composite Physical Activity Score in Relation to Cardiovascular Health Indicators: Coronary Artery Risk Development in Young Adults
Authors: Pettee Gabriel Kelley , Pérez Adriana , Jacobs David R. , Lee Joowon , Kohl Harold W. , Sternfeld Barbara
Published: October 2018

Background: Single-method assessment of physical activity (PA) has limitations. The utility and cross-validation of a composite PA score that includes reported and accelerometer-derived PA data has not been evaluated. Methods: Participants attending the Year 20 exam were randomly assigned to the derivation (two-thirds) or validation (one-third) data set. Principal components analysis was used to create a composite score reflecting Year 20 combined reported and accelerometer PA data. Generalized linear regression models were constructed to estimate the variability explained (R2) by each PA assessment strategy (self-report only, accelerometer only, composite score, or self-report plus accelerometer) with cardiovascular health indicators. This process was repeated in the validation set to determine cross-validation. Results: At Year 20, 3549 participants (45.2 [3.6] y, 56.7% female, and 53.5% black) attended the clinic exam and 2540 agreed to wear the accelerometer. Higher R2 values were obtained when combined assessment strategies were used; however, the approach yielding the highest R2 value varied by cardiovascular health outcome. Findings from the cross-validation also supported internal study validity. Conclusions: Findings support continued refinement of methodological approaches to combine data from multiple sources to create a more robust estimate that reflects the complexities of PA behavior.
Glycans for good
Authors: Kaiser Katherine A. , Arpaia Nicholas
Published: October 2018

The gut commensal bacterium
Bifidobacterium bifidum
promotes immune tolerance by facilitating the induction of colonic regulatory T cells. See related Research Article by

Verma
et al
.
Gram-Positive Anaerobic Cocci
Authors: Murdoch D. A.
Published: October 2018

Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum β-lactam resistance.
Clinical, Cellular, and Molecular Factors That Contribute to Antifungal Drug Resistance
Authors: White Theodore C. , Marr Kieren A. , Bowden Raleigh A.
Published: October 2018

In the past decade, the frequency of diagnosed fungal infections has risen sharply due to several factors, including the increase in the number of immunosuppressed patients resulting from the AIDS epidemic and treatments during and after organ and bone marrow transplants. Linked with the increase in fungal infections is a recent increase in the frequency with which these infections are recalcitrant to standard antifungal therapy. This review summarizes the factors that contribute to antifungal drug resistance on three levels: (i) clinical factors that result in the inability to successfully treat refractory disease; (ii) cellular factors associated with a resistant fungal strain; and (iii) molecular factors that are ultimately responsible for the resistance phenotype in the cell. Many of the clinical factors that contribute to resistance are associated with the immune status of the patient, with the pharmacology of the drugs, or with the degree or type of fungal infection present. At a cellular level, antifungal drug resistance can be the result of replacement of a susceptible strain with a more resistant strain or species or the alteration of an endogenous strain (by mutation or gene expression) to a resistant phenotype. The molecular mechanisms of resistance that have been identified to date in Candida albicans include overexpression of two types of efflux pumps, overexpression or mutation of the target enzyme, and alteration of other enzymes in the same biosynthetic pathway as the target enzyme. Since the study of antifungal drug resistance is relatively new, other factors that may also contribute to resistance are discussed.
Dengue and Dengue Hemorrhagic Fever
Authors: Gubler Duane J.
Published: October 2018

Dengue fever, a very old disease, has reemerged in the past 20 years with an expanded geographic distribution of both the viruses and the mosquito vectors, increased epidemic activity, the development of hyperendemicity (the cocirculation of multiple serotypes), and the emergence of dengue hemorrhagic fever in new geographic regions. In 1998 this mosquito-borne disease is the most important tropical infectious disease after malaria, with an estimated 100 million cases of dengue fever, 500,000 cases of dengue hemorrhagic fever, and 25,000 deaths annually. The reasons for this resurgence and emergence of dengue hemorrhagic fever in the waning years of the 20th century are complex and not fully understood, but demographic, societal, and public health infrastructure changes in the past 30 years have contributed greatly. This paper reviews the changing epidemiology of dengue and dengue hemorrhagic fever by geographic region, the natural history and transmission cycles, clinical diagnosis of both dengue fever and dengue hemorrhagic fever, serologic and virologic laboratory diagnoses, pathogenesis, surveillance, prevention, and control. A major challenge for public health officials in all tropical areas of the world is to devleop and implement sustainable prevention and control programs that will reverse the trend of emergent dengue hemorrhagic fever.