bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of shear wave generation methods for intraoperative magnetic resonance elastography in a clinical transcranial focused ultrasound system
Authors: Brinker Spencer , McDannold Nathan
Published: June 2017

The current standard for FDA approved real-time monitoring of transcranial Focused Ultrasound (FUS) ablation is MR-thermometry. Ultrasound-elastography and Magnetic Resonance Elastography (MRE) have shown success in monitoring FUS ablation in various parts of the body. Introducing shear wave vibrations into the brain during transcranial-FUS becomes technologically challenging given the stringent constraints of the operating space in water filled transcranial phased array devices and since patients are fixed in stereotactic headgear during treatment. This study investigates the feasibility of using intraoperative-MRE during transcranial-FUS ablation in the ExAblate 4000 (InSightec, Ltd.) platform. Acoustic radiation force induced vibration using the ExAblate 4000 transducer and common MRE surface actuation methods are evaluated for shear wave generation. Elastic phantom experiments were used to gauge the acoustic power levels and time incurred during vibrations from MRE scanning while in the FUS transducer. These values were compared to FUS and MR parameters used in clinical transcranial-FUS treatments. MRE derived 3D displacement fields within the phantom materials are evaluated for all vibration methods. The cooling water in the ultrasound traducer influenced the MR signal using current MRE pulse sequences. Future work will involve integrating MRE into sequences less sensitive to cooling water media and minimizing intraoperative-MRE scan time.
Ultrasound exposure during collagen polymerization produces pro-migratory fiber structures
Authors: Grygotis Emma , Dalecki Diane , Hocking Denise C.
Published: June 2017

Non-invasive techniques to control protein structure and function are needed for tissue engineering applications. This study tested the hypothesis that non-thermal effects of ultrasound can produce changes in collagen microstructure that support directional cell migration. Type I rat tail collagen was polymerized for 15 minutes in the presence of an 8-MHz ultrasound standing wave field over a range of 0 to 30 W/cm2 spatial peak, temporal average intensity. Temperature-matched sham gels were manufactured in a heated water bath without exposure to ultrasound. To test for effects of acoustically-modified collagen on cellular behavior, fibronectin-null mouse embryonic fibroblasts or mouse skin explants were seeded on gel surfaces and cultured up to 7 days prior to imaging with phase or second harmonic generation (SHG) microscopy. Acellular acoustically-modified collagen gels were characterized by regions of radial fiber alignment, increased pore size, and denser fibers, with greater heterogeneity at higher intensities. Ultrasound-exposed gels supported rapid directional cell migration with accumulation of cells in the regions of highest SHG signal. Neither fiber alignment nor cellular migration was observed in temperature-matched sham gels. Results demonstrate that ultrasound exposure during collagen polymerization can result in functionally altered collagen microstructure, in part through a non-thermal mechanism.
Dynamics of pulsed-ultrasound driven gas-liquid interfaces
Authors: Patterson Brandon , Johnsen Eric
Published: June 2017

Pulsed ultrasound has been shown to be capable of inducing lung hemorrhage in mammals, though the physical mechanism remains unknown. We model ultrasound-alveolar interactions as a compressible fluid system and perform numerical experiments to investigate the relevant dynamics. Previously we demonstrated that the interaction between trapezoidal acoustic waves and perturbed gas-liquid interfaces, such as those in the lung, can generate sufficient baroclinic vorticity to appreciably deform the interface under certain conditions. In this work we study the dynamics of perturbed liquid-gas interfaces driven by a single ultrasound pulse in and out of the clinically relevant range with frequencies 1.5-3 MHz and amplitudes 1-15 MPa. We calculate theoretical stresses and strains and compare to established failure criteria. We observe that for ultrasound pulses that significantly deform the interface during the wave-interface interaction, there is residual vorticity left at the interface which can deform the interface long after the passage of the wave. This effect increases with wave amplitude, pulse duration, and initial interface perturbation amplitude. Previously presented scaling laws for the interface perturbation amplitude and arc length growth are tested. While we find that nominal interface strains greater than 1 occur we recognize that the applicability of this study to diagnostic lung ultrasound is limited by the accuracy of the model.
Noninvasive and localized acoustic micropumping—An in vitro study of an ultrasound method that enhances drug distribution through a physiologically-relevant material
Authors: Elghamrawy Ahmed , de Comtes Florentina , Koruk Hasan , Mohammed Ali , Choi James
Published: June 2017

Acoustic streaming—the displacement of fluid by sound—has been proposed as the mechanism for therapeutic effects, such as drug distribution enhancement, yet there have been no direct observation or characterization of this effect in soft tissue, making it difficult to optimize and control. We aimed to directly observe ultrasound-induced streaming during sonication in a tissue-mimicking material. We hypothesized that existing ultrasound phantoms (e.g., polyacrylamide (PAA) and gelatin) mimic the acoustic properties of tissue, but not the tissue microenvironment. Scanning electron microscopy revealed that gelatin and PAA had closed pores suggesting that they can’t support acoustic streaming. In contrast, macroporous acrylamide (MPPA), a new phantom we created, had interconnected pores resembling the interstitial space of soft tissue. The focal point of a focused ultrasound (FUS) transducer was placed at the distal surface of the MPPA phantom. A model drug (Bromophenol blue) was injected in and around the focal region and different FUS parameters were evaluated. Dye clearance at the hydrogel surface was observed with a video camera. Increasing ultrasound pressure produced higher streaming. Pulsed ultrasound having the same total energy as continuous wave ultrasound produced higher streaming. Using MPPA, we were able to study acoustic streaming under different parameters. Our future work is to optimize ultrasound parameters to maximize acoustic streaming in this material and in in-vivo tissue for enhancing drug distribution.
Changes in the optical scattering and absorption spectra of ex vivo chicken breast tissue following exposure to high-intensity focused ultrasound
Authors: Raymond Jason L. , Cleveland Robin , Roy Ronald A.
Published: June 2017

Real-time acousto-optic (AO) sensing has been shown to non-invasively detect changes in ex vivo tissue optical properties during high-intensity focused ultrasound (HIFU) exposures. Baseline changes in optical properties have been previously measured as a function of thermal dose for chicken breast exposed to a temperature-controlled water bath (doi:10.1088/0031-9155/59/13/3249). In this work, the wavelength-dependent optical scattering and absorption coefficients of ex vivo chicken breast tissue exposed to HIFU were measured using an integrating sphere spectrophotometric technique employed previously. A focused HIFU transducer coupled to an acoustic lens was used to produce a large focal heating area in a thin (approximately 2 mm) section of tissue. Spatiotemporal surface temperature elevations were measured using an infrared camera and used to calculate the spatially dependent thermal dose delivered to a localized region of tissue as the exposure intensity and time were varied. Results will show how wavelength-dependent optical property changes can be used to improve the AO sensing of lesion formation during HIFU therapy as an alternative to thermometry and dosimetery. [Work supported by the F. V. Hunt Postdoctoral Fellowship, the University of Oxford, and EPSRC grant number EP/K02020X/1.]
Design of quieter kitchen appliances: Sound pressure level modeling and validation of a household refrigerator using statistical energy analysis
Authors: Zarate Roberto , Matus Edgardo , Lopez Marcelo , Ballesteros Luis
Published: June 2017

The design of efficient and quieter kitchen appliances represents a significant challenge for manufacturers. In domestic refrigerators, the compressor, condenser's fan, and evaporator's fan are important sources of noise. This paper presents the statistical energy analysis (SEA) carried out to estimate the sound pressure level generated in a domestic refrigerator's evaporator subsystem. The work focuses on the evaporator's fan and the subsystem's mechanical assembly; these constitute the main source of noise and path for vibration transmission. The results of the analysis for a frequency band noise between 100 Hz and 10 kHz are reported. A semi-anechoic chamber was used to validate the SEA analysis presented herein; the authors also set up an experiment using microphones and accelerometers complying with standard ISO-3745, achieving a correlation of up to 96%. The analysis and experimental data were then used to produce a set of design guidelines to help kitchen appliance designers in the configuration of innovative cabinet geometries and the implementation of noise reduction strategies in household refrigerators.
Reading, writing, and arithmetic: Encouraging students to read textbooks and take organized notes
Authors: Russell Daniel A.
Published: June 2017

Common practice for many graduate level physics and engineering courses is for professors to teach using traditional lectures to a student audience while using textbooks as primary references. Traditional lecture styles often fall at one of two extremes: a more historical approach where a professor writes notes on a board while students dutifully copy those notes down, or a conference style approach where lecture content is presented with PowerPoint slides while students watch without taking notes. This talk will describe two approaches the author uses in the teaching of graduate level acoustics courses: (i) to encourage students to read material from relevant textbooks prior to the topic being covered in greater depth during lecture; and (ii) a middle ground lecture method using partial notes where students are given a set of well-organized, but very incomplete, handouts which are annotated during a class session. Discussion will include examples, as well feedback from professor and students regarding the effectiveness of these approaches. While these methods are used by the author for graduate level acoustics courses, they may be effectively adapted for teaching undergraduate courses as well.
The potential of comprehensive reference to acoustic overall scenarios and their subjective experience with regard to urban sound planning
Authors: Scheuren Joachim , Altreuther Beate , Alves Sonia
Published: June 2017

The refinement of descriptors for subjective sound assessments and growing recognition that comfortable sound environments definitely need more than a limitation of sound levels have changed the scope of engineering acoustics over the last decades. Instead of focusing on objective physical parameters more and more emphasis has been put on understanding and promoting the subjective experience of acoustic environments. However, to what extent such approaches have been applied to practice strongly depends on the applicative environment. While subjective criteria for product sound quality are widely accepted if they immediately serve the user, they apparently face difficulties if applied to the benefits of uninvolved but affected third parties. After a short review of underlying motivations the potential of comprehensive, holistic approaches which relate to the full spectrum of acoustic scenarios from the point of view of subjective experiences will be outlined and demonstrated with particular reference to urban sound planning, the acoustic planning for urban environments.
Implementing Zwicker sharpness using specific loudness calculated from the “Procedure for the Computation of Loudness of Steady Sounds.”
Authors: Swift S. Hales , Gee Kent L.
Published: June 2017

Sharpness as defined by Fastl and Zwicker [2007] is a measure of the weighted spectral balance of a sound, i.e., sounds with relatively greater high-frequency content have a greater sharpness than those with proportionally greater low-frequency content. The sharpness percept also influences the overall “pleasantness” of a sound and is thus important to sound quality. Measures of sharpness have been predominantly constructed to work with Zwicker's loudness model [DIN 45631/ISO 532B], with less attention to the standardized model given in “Procedure for the Computation of Loudness of Steady Sounds” [ANSI S3.4-2007]. In this paper, a mathematical method for adapting Zwicker's sharpness measure for use with the ANSI S3.4-2007 loudness standard (and other loudness metrics producing a specific loudness distribution) is discussed. Benchmarking results for the resultant metric and potential limitations of this approach are also addressed.
Self-fitting hearing aids reveal strong effects of sound quality and comfort
Authors: Nelson Peggy B. , VanTasell Danne , Perry Trevor T.
Published: June 2017

Noisy rooms present difficult challenges for listeners with hearing loss, and sensory aids have limitations in overcoming those challenges. New technology from EarMachine(c) allows for individuals with hearing loss to self-adjust hearing aid amplification parameters. This technology can provide data to empirically answer questions about listener preferences in noise. Results from 30 listeners demonstrated gain profiles revealing extremely large individual preferences that are not well predicted by age, gender, or hearing loss. Preference judgments suggest that sound quality and comfort are important variables that can be achieved without significant loss of speech intelligibility.
MRI investigation of the ear canal deformation due to earplugs: A first step toward understanding wearing comfort
Authors: Benacchio Simon , Varoquaux Arthur , Le Troter Arnaud , Wagnac Eric , Doutres Olivier , Bendahan David , Callot Virginie , Sgard Franck C.
Published: June 2017

The effective protection of earplugs is related to the acoustical attenuation but also to the comfort they provide. Earplugs are acoustic seals used to reduce sound transmission in the ear canal. A perfect contact between ear canal and earplug should ideally avoid acoustic leaks leading to under-protection. Practically, this acoustic seal is achieved applying a greater or lesser deformation on the ear canal walls which depends on the earplug insertion and type. However, a too large deformation can modify the acoustic attenuation and cause physical pain due to mechanical pressure exerted onto ear canal walls leading the wearer to take earplugs off and reducing their protection. This study aims at investigating the ear canal deformation of one human subject due to insertion of various earplugs known for providing different levels of protection and different levels of comfort. The shape of the open and occluded right and left ear canals of the subject is measured using MRI technology. The deformation along the ear canal is estimated using an imaging registration method. The results show large displacements at the ear canal entrance for all earplugs and non negligible displacements after the first bend of the ear canal for some of them.
Fitness noise impact in mixed use buildings
Authors: Tikriti Walid
Published: June 2017

The paper discusses noise impact from fitness activities in high rise mixed used buildings. The presented project will be discussing noise complaints from residences living above and below the fitness center. The project is located in Addison, TX. The complaints from residents are related to impact noise from fitness room class activities. Onsite sound measurements were taken and analyzed for noise source. Noise mitigation solutions were provided and implanted by the clients.
A review about hearing protection comfort and its evaluation
Authors: Doutres Olivier , Sgard Franck C. , Terroir Jonathan
Published: June 2017

Though it should ideally be the last choice in terms of noise exposure reduction, hearing protection devices (HPDs) remain the most commonly used noise control solution. However, the lack of comfort of HPDs can make it difficult for the worker to consistently and correctly wear them during work shift. It can thereby decrease their effective protection. Numerous studies have addressed the comfort of HPDs since the late fifties. These works mainly differ on (i) their definition of “comfort”, (ii) how “comfort” is measured (questionnaires), (iii) their measurement conditions (laboratory versus field, naïve versus experienced wearers, type of tested HPDs…) and finally, (iv) their conclusions. The objective of this paper is to propose a comprehensive literature review of these works and to put them into perspective regarding a definition of HPD comfort based on three main components: (1) the physical one which is related to the human perception of the acoustical, biomechanical and thermal interactions between the HPD and the ear, (2) the functional one which is associated to the ergonomic aspects of the HPD and its capacity to fulfill its objectives, and (3) the psychological one which is linked to the wearer feeling in terms of acceptability, satisfaction, or habituation.
Evolution of Rayleigh streaming flow velocity components in a resonant waveguide at high acoustic levels
Authors: Daru Virginie , Bailliet Hélène , Weisman Catherine , Baltean-Carlès Diana , Reyt Ida
Published: June 2017

The interaction between an acoustic wave and a solid wall generates a mean steady flow called Rayleigh streaming, generally assumed to be second order in a Mach number expansion. This flow is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at the antinode. For higher acoustic levels, additional streaming cells have been observed. In the present study, results of LDV and PIV measurements are compared to direct numerical simulations. The evolution of axial and radial velocity components for both acoustic and streaming flows is studied from low to high acoustic amplitudes. Two streaming flow regimes are pointed out, the axial streaming dependency upon acoustics going from quadratic to linear. The hypothesis of the radial streaming velocity being of second order in a Mach number expansion is shown to be invalid at high amplitudes. The change of regime occurs when the radial streaming velocity amplitude becomes larger than the radial acoustic velocity amplitude, high levels being therefore characterized by nonlinear interaction of the different velocity components.
Sequential streaming of speech sounds under normal and impaired hearing
Authors: David Marion , Strelcyk Olaf , Oxenham Andrew J.
Published: June 2017

Segregating and understanding speech within complex auditory scenes remains a major challenge for hearing-impaired (HI) listeners. This study compared the ability of normal-hearing (NH) listeners and HI listeners with mild-to-moderate loss to segregate sequences of speech tokens, consisting of an unvoiced fricative consonant and a vowel (CV), based on a difference in fundamental frequency (F0) and/or vocal tract length (VTL). The CVs were amplified and spectrally shaped to ensure audibility for the HI listeners. In the streaming task, the CV tokens were concatenated into sequences that alternated in F0, VTL or both. The resulting interleaved sequences were preceded by a “word” consisting of two random syllables. The listeners were asked to indicate whether the word (which varied from trial to trial) was present in the interleaved sequence. The word, if present, occurred either within one sequence or across the alternating sequences. Preliminary results showed no difference in performance between the two groups, suggesting that the listeners with mild-to-moderate sensorineural hearing loss are able to use differences in F0 and VTL to segregate speech sounds in situations where there is no temporal overlap between the competing sounds.
Having two ears can facilitate or interfere with the perceptual separation of concurrent talkers for bilateral and single-sided deafness cochlear-implant listeners
Authors: Bernstein Joshua G. , Goupell Matthew , Wess Jessica , Stakhovskaya Olga , Brungart Douglas S.
Published: June 2017

Binaural hearing provides normal-hearing listeners with tremendous speech-understanding benefits in complex listening conditions. While head-shadow advantages improve speech understanding in noise for bilateral (BI) and single-sided deafness (SSD) cochlear-implant (CI) listeners, it is unclear whether bilateral input can facilitate the perceptual organization of a complex auditory scene. We review a series of studies examining speech perception in the presence of interfering talkers for these listeners. For some BI-CI listeners and for SSD-CI listeners attending to their normal-hearing ear, having two ears facilitates the perceptual separation of concurrent talkers. For other BI-CI listeners and for SSD-CI listeners attending to their CI ear, bilateral input can produce speech-perception interference. Factor analyses and vocoder simulations suggest that the presence of binaural benefit or interference can depend on hearing history (duration of deafness) or physical factors (interaural spectral mismatch). To maximize binaural-hearing benefits and reduce the likelihood of interference, CI candidates should be implanted soon after deafness onset, with frequency-allocation tables optimized to minimize interaural mismatch. [Support: NIH-NIDCD/R01-DC-015798 (Bernstein/Goupell), DMRDP/DM130007 (Bernstein) and NIH-NIDCD/R01-DC-014948 (Goupell). The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.]
Reproducibility of speech intelligibility scores in spatially reconstructed and re-reconstructed vehicle cabin noise
Authors: Macpherson Ewan A.
Published: June 2017

We assessed the fidelity of the multichannel freefield soundfield reconstruction technique proposed by Minnaar et al (AES 2013) by comparing Hearing in Noise Test (HINT) speech reception thresholds (SRTs) obtained in reconstructed, and then re-reconstructed, vehicle cabin noise soundfields. Recordings were first made in a moving vehicle under a variety of driving conditions (50 km/hr, smooth/rough road, open/closed windows) using a 32-channel spherical microphone array (Eigenmike ®, m.h. acoustics) placed in the passenger's head location. Using a six-loudspeaker array in the same stationary vehicle, the soundfields were approximately reconstructed, and SRTs were obtained for 12 normally hearing listeners located in the passenger seat; a small loudspeaker reproduced target speech from the driver's position and two rear passenger positions. For comparison, the in-vehicle reconstructed soundfields (R1) and speech were re-recorded and then re-reconstructed (R2) in an anechoic chamber using a 48-loudspeaker array, where SRTs were obtained for the same listeners. Mean SRTs were uniformly lower in R2 by 0.32 to 1.87 dB depending on speaker location and driving condition. The differences were larger when the speaker was beside rather than behind the listener by a mean of 0.98 dB and larger when windows were open by a mean of 0.23 dB. The results suggest that the reconstruction technique requires minor refinement in order to yield speech intelligibility scores equivalent to those in the original environment.
Adaptive interpolation techniques for structural acoustic system response
Authors: Wixom Andrew S. , McDaniel James G.
Published: June 2017

In recent years, several new techniques for interpolating the response of structural acoustic systems have been developed. Besides the various underlying approximation schemes that utilize concepts such as Padé approximants or implicitly interpolatory subspaces, the main advantage of these methods is that their structure is adaptively determined, meaning that they select interpolation points and, when appropriate, interpolation order as the algorithm proceeds. This allows users to have little to no a priori knowledge of the system response and yet still achieve approximations of a desired accuracy. Furthermore, the interpolation is generated at minimal cost giving rise to approximations that are efficient as well as accurate. A variety of these techniques are introduced and discussed with emphasis on the trade-offs between the methods. Then, a numerical test bed is developed to evaluate the performance of the interpolation schemes giving each access to the same computational resources. Recommendations are made based on these simulations concerning the appropriate choice of adaptive interpolation for various scenarios.
Modeling and optimization of acoustic black hole vibration absorbers
Authors: Shepherd Micah R. , McCormick Cameron A. , Conlon Stephen C. , Feurtado Philip A.
Published: June 2017

Recent studies have shown that the acoustic black hole (ABH) effect can be used to provide vibration absorption and improved structural-acoustic response. In this talk, several aspects of the design and implementation of ABH vibration absorbers will be discussed. First, to address the competing nature of the best ABH taper for vibration reduction and the underlying theoretical assumptions, a multi-objective approach is used to find the best ABH parameters where both criteria are sufficiently met. Next, the modeling challenges associated with one- and two-dimensional ABH design will be discussed and a mesh convergence study will be presented. Finally, the use of multiobjective optimization for ABH design will be discussed for aerospace and marine applications.
Coda and tonal effects on perceived vowel duration
Authors: Chang Yi-ling , Lu Yu-an
Published: June 2017

The shape of pitch contours has been shown to have an influence on the perceived vowel duration in that listeners tend to perceive vowels as shorter when they are produced as longer (compensatory listening strategy, Guessenhoven & Zhou, 2013). This study further investigates if the syllable structure allowed in one's native language and the frequency of tone types also affect perceived duration. An AX perceptual experiment was conducted using disyllabic structures (i.e., mepVC) in which the target vowel ([a] and [i]) in four duration steps (180, 210, 240, 270ms) and 5 pitch contours (LL, HH, HL, LH, HLH) and 7 codas ([p], [t], [k], [m], [n], [ŋ], [∅]) are embedded in the second syllable, to be compared with an anchor stimulus with a fixed vowel duration (225ms) and pitch (195Hz). Taiwanese Southern Min speakers, whose native language allows obstruent codas, and Mandarin speakers, whose native language only allows nasal codas, were recruited to participate in the experiment in which they were told to listen to pairs of meaningless words and asked to compare the durations of the second vowels and rate them on a 7-point scale. The results showed that perceived duration cannot be solely explained by compensatory listening strategy. Instead, tone inventory, tone frequency and the syllable structure allowed in the native language all contribute to the perceived vowel duration.
Assessing the fit between phonological feature theories and neural data
Authors: McCloy Daniel , Lee Adrian KC
Published: June 2017

Phonological features have been called the most important advance in linguistic theory of the 20th century, yet there is still no consensus regarding their epistemic basis. Many feature systems are based on articulatory properties of consonants and acoustic properties of vowels, others are solely articulatory, and perceptually-based feature systems are rare, despite the fact that phonemes (and by extension, features) allegedly reflect how speech sounds are represented in the brain. Here we examine the fit between several phonological feature systems and electroencephalographic (EEG) recordings made during speech perception. We label EEG data with phonological feature values from different systems, train classifiers to categorize the EEG signals, and assess the accuracy of classifying held-out unlabeled EEG data. By varying only the phonological feature system from which we draw the training labels, we can assess the extent to which neural data recapitulate the patterns inherent in the different feature systems.
Relationship between individuals' compensation for coarticulation and production
Authors: Long Yanyu
Published: June 2017

This study examines the relationship between compensation for coarticulation and production. We tested individuals’ perceptual compensation of /s/ before /u/ and ability to imitate /s/ that were manipulated to sound equally over-coarticulated before /u/ and /a/. It is hypothesized that people who compensate more should converge less to the manipulated stimuli in the coarticulatory context. All /s/ were measured by center of gravity. Regression analyses showed that perceptual compensation is not a significant predictor of imitation of the manipulated /s/ in both contexts. We then obtained individuals’ perceptual and production /s/ distributions using the tasks and used an exemplar model which assigns different weights to the existing distributions and the stimuli to predict the production in imitation. The resulting stimuli weights are indicators of the degree of imitation. Again, the results showed no effect of perceptual compensation on the stimuli weight. Instead, it depends on the perceptual distributions: within a range, the perceptual distribution mean is positively correlated with stimuli weight, suggesting more imitation when the stimuli are perceptually saliently different from the existing distribution mean. These findings show that the perceptual-production relation can be better understood using a dynamic model that takes into consideration existing and new information.
Historical development of side scan sonar
Authors: Sternlicht Daniel D.
Published: June 2017

The seabed mapping side scan sonar, conceived and developed in the 1950s at the U.S. Navy Mine Defense Laboratory (USNMDL) [Commander and Sternlicht, J. Acoust. Soc. Am. 137, 2307 (2015)], was inspired by the Royal Navy ASDIC Type-162, a late-WWII hull mounted side-looking sonar capable of recording the silhouettes of bottomed U-boats. The commissioned U.S. Navy C-MK-1 SHADOWGRAPH, which operated in the Megahertz band and employed curved apertures for cross-track focusing, represents the first in a long history of military and commercial innovations. Commercial side scan sonars, typically operating in the tens or hundreds of Kilohertz, reached the marketplace in the 1960s. The SHADOWGRAPH series led to the Navy’s AN/AQS-14 and French DUBM-series mine detection sonars, and the active tow vehicles of the C-MK-1 served as test platforms for the first synthetic aperture sonars (SAS) fielded at USNMDL (now the Naval Surface Warfare Center Panama City Division) during the 1970s. Through the present day these systems, military and commercial, have been augmented by revolutionary: developments in swath bathymetry side scan sonar, multi-beam echo sounders, and SAS; signal processing advances in acoustic tomography and spectroscopy; and information processing advances in environmental characterization, automatic target recognition and seabed change detection.
Computing navigation corrections for co-registration of repeat-pass synthetic aperture sonar images
Authors: Myers Vincent , Quidu Isabelle , Sæbø Torstein O. , Hansen Roy E. , Zerr Benoit
Published: June 2017

Interferometric processing of repeat-pass Synthetic Aperture Sonar (SAS) data requires a precise co-registration of the images in order to exploit the phase information for applications such as differential interferometry or coherent change detection. Co-registration of SAS images is made difficult by changing environmental conditions and positioning ambiguities that give rise to warping functions which are not well modeled by affine or polynomial transformations, resulting in non-negligible residual misregistration errors. The objective of this presentation will be to examine these warping functions in greater detail to gain a better physical understanding of the estimated along- and across-track displacements. A non-linear least-squares optimization is used to determine the corrections to be applied to the repeat-pass data that will yield a repeat-pass image that is co-registered with the original. These corrections include sway, heave and yaw as well as sound speed errors and element-level surge adjustments. Repeat-pass SAS data collected a Kongsberg HISAS 1020 system is used to demonstrate this optimization, showing good agreement with modeled and real data for most parameters, while determining surge estimates are shown to be particularly challenging. An examination of the resulting repeat-pass coherence will also be performed.
Through-the-sensor sediment characterization from autonomous underwater vehicle sonar systems
Authors: Isakson Marcia J.
Published: June 2017

Ocean bottom sediment type is a key parameter in understanding physical processes such as sediment transport and object burial as well as acoustic processes such as propagation and backscatter. However, direct methods such as coring and grab samples are time-consuming and coverage limited. The analysis of normal-incidence echo sounding has proven to be a reliable technique for certain frequency ranges. For this method, a clear understanding of the physical processes such as scattering and reflection is critical. For higher coverage, the normal-incidence echo sounder technique can be applied to through-the-sensor measurements. This is attractive since it requires no additional equipment particularly important to autonomous underwater vehicle operations. However, through-the-sensor measurements have the additional complications of understanding hardware and signal processing algorithms that were not specifically designed for sediment characterization or normal-incidence echo sounding. In this talk, measurements from two sensors, the light-weight conformal array and the small synthetic aperture minehunter, are analyzed for sediment type. The results are compared with ground truth data. Challenges and issues involved with using these sensors for sediment characterization will be discussed. [Work supported by ONR, Ocean Acoustics.]
Numerical simulations of T-wave generation and conversion at shores: Influence of slope angles and of the SOFAR channel
Authors: Bottero Alexis , Cristini Paul , Komatitsch Dimitri
Published: June 2017

The term T waves is generally associated to acoustic signals generated by earthquakes which end up traveling horizontally in the ocean at the speed of sound in the water. After traveling over long ranges they reach the shore, where they can be reflected or converted into (visco)elastic waves. For almost 90 years, T waves have been the subject of numerous studies in order to identify their generation mechanisms. Generally, it is supposed that seismic waves are converted to horizontally propagating T-waves by a sloping sea bottom before entering the SOFAR channel. In this study, we present a two-step parametric study of the influence of the slope on a typical T-wave generation/conversion scenario. We use a 2D spectral-element method that allows for full-waveform modeling of wave propagation. In a first step we study the amount of acoustic energy channeled from a deep earthquake below a sloping sea-floor. We then model the reflection/transmission of T waves at the shore. Our results suggest that an optimum slope angle exists for T-wave generation, and that a non-negligible amount of the channeled energy can be reflected at a sloping shore. We find no evidence of a significant influence of the SOFAR channel.
Characterizing global infrasonic ocean ambient noise
Authors: Le Pichon Alexis , Stutzmann Eleonore , Ardhuin Fabrice , Sylvain Leon
Published: June 2017

The ability of the International Monitoring System (IMS) global infrasound network to detect atmospheric explosions and events of interest strongly depends on station specific ambient noise which includes both incoherent wind noise and real coherent infrasonic waves. To characterize the coherent ambient noise, a broadband array processing was performed on 10 years of continuous recordings at IMS stations. Multi-year comparisons between the observed and modeled directional microbarom amplitude variations at several IMS stations using two-dimensional wave energy spectrum ocean wave products are performed to build of a reference database of infrasound oceanic sources. Microseisms are attributed the same source processes as microbaroms, involving the interaction of standing ocean waves. To further evaluate oceanic wave action models, the infrasound analysis will be supplemented with several other approaches including microseisms collected at seismic instrumentation (single stations and arrays). The expected benefits of such studies concern the use of multi-year complementary data to finely characterize coupling mechanisms at the ocean-atmosphere interface. In return, a better knowledge of the source of the ambient ocean noise opens new perspectives by providing additional integrated constraints on the dynamics of the middle atmosphere and its disturbances where data coverage is sparse.
Infrasound in the stratosphere captured with balloon-borne sensors
Authors: Bowman Daniel C. , Lees Jonathan M. , Le Pichon Alexis , Arrowsmith Stephen
Published: June 2017

Infrasound sensors launched into the stratosphere on high altitude balloons experience zero wind noise, travel across regions inaccessible to ground stations, and access a unique geoacoustic wave field that has not been examined in half a century. Recent flights in the American Southwest have detected one to several events per hour, a capability that may be due to the lack of wind noise and the balloons' presence in a stratospheric wave guide. The provenance of these events is currently uncertain, but a known explosive source was detected at greater ranges compared to nearby ground stations. A 14 day circumnavigation of Antarctica revealed that high altitude sensors have lower noise floors than International Monitoring System (IMS) infrasound stations. The ocean microbarom was continuously recorded during this flight. The sensors flew directly over spatially extended microbarom source regions circulating along the Antarctic Circumpolar Current; these signals are also detected on IMS stations. Other signals that resemble far-field explosions were detected in the stratosphere, as well as many whose sources are unknown. We look forward to the development of a new branch of geoacoustics focusing on signals recorded in the free atmosphere at extreme range, above the open ocean, and over phenomena such as severe storms that preclude ground based observation.
Balloon borne infrasound platforms: Low noise, high yield
Authors: Lees Jonathan M. , Bowman Daniel C.
Published: June 2017

A balloon borne infrasound sensor circumnavigating Antarctica over the Southern Ocean shows significant broad band signals recorded on a simple microphone. A 10 hour portion of the flight traversed South American Andes, in southern Chile just north of the active Villarrica Volcano. We present signals recorded during this expedition and suggest that the high frequency signals represent transmissions from the earth, or possible bolide activity. While the source of the high frequency signals is yet unknown we provide a statistical analysis of the content during the flight. Verification of signals using chemical explosions in New Mexico demonstrate that infrasound signals are well recorded on stratospheric stations floating hundreds of km from the source. Comparison of stratospheric floating balloon platforms with ground based (IMS) infrasound stations shows considerable improvement in the noise floor, suggesting that balloon borne signals offer a high fidelity alternative to traditional acoustic installations.
Effects of time dispersion on echo, reverberation, and echo to reverberation ratio in a range-dependent Pekeris waveguide
Authors: Ainslie Michael A. , Ellis Dale D.
Published: June 2017

In shallow water, active sonar performance is typically limited by reverberation, making the prediction of target echo and reverberation, and their ratio, an important part of sonar performance prediction. In range-dependent shallow water environments, these quantities are often calculated without considering the effect of dispersion. The effect of time dispersion is considered taking examples for a range-dependent bathymetry from the 2010 Weston Memorial Workshop. Using the analytical method of [M. A. Ainslie and D. D. Ellis (in press), IEEE Journal of Oceanic Engineering], combined with normal mode predictions [D. D. Ellis (1995). The Journal of the Acoustical Society of America, 97(5), 2804-2814], neglect of time dispersion is found to result in an error of up to 16 dB in the echo level for a short CW pulse (duration 3 ms). The effect of 3D geometry is considered, and results for a cylindrically symmetric bathymetry are shown to differ by up to 14 dB from the corresponding results with a Cartesian symmetry. The difficulties associated with modeling an LFM pulse are discussed.
Asymptotic stepwise coupled modes for horizontally-variable acoustic media
Authors: White Charles E. , Clark Cathy Ann , Potty Gopu R. , Miller James H
Published: June 2017

Efficient and accurate mathematical codes for the prediction of underwater sound propagation are a critical component of SONAR system development and operation. The goal of the research presented herein is to develop, implement, and verify an efficient and rigorous coupled-mode solution for acoustic wave propagation in shallow water range-dependent environments. A theoretical framework involving a range-expanded inner product for capturing the coupling between modes as they propagate through a horizontally-variable medium is presented. This framework includes a novel discretization of the range-dependent acoustic medium. A difference equations approach, which implements the inner product to account for non-adiabatic energy transfer between modes, is used to recursively compute reflection and transmission coefficients throughout the discretized environment. Increased efficiency is gained in the method due to the ability to compute coupling via closed-form algebraic expressions and in the application of asymptotic analysis to simplify the transmission and reflection coefficients. Results will be shown for a sample of waveguides with horizontally-variable bottom depth, along with comparable results from R. Evans’ COUPLE model and an FEM solution produced by ARL-UT. [This work was funded by the Naval Undersea Warfare Center, Newport Rhode Island.]
RNA-Based Amplicon Sequencing Reveals Microbiota Development during Ripening of Artisanal versus Industrial Lard d'Arnad
Authors: Ferrocino Ilario , Bellio Alberto , Romano Angelo , Macori Guerrino , Rantsiou Kalliopi , Decastelli Lucia , Cocolin Luca
Published: June 2017

Valle d'Aosta Lard d'Arnad is a protected designation of origin (PDO) product produced from fat of the shoulder and back of heavy pigs. Its manufacturing process can be very diverse, especially regarding the maturation temperature and the NaCl concentration used for the brine; thereby, the main goal of this study was to investigate the impact of those parameters on the microbiota developed during curing and ripening. Three farms producing Lard d'Arnad were selected. Two plants, reflecting the industrial process characterized either by low maturation temperature (plant A [10% NaCl, 2°C]) or by using a low NaCl concentration (plant B [2.5% NaCl, 4°C]), were selected, while the third was characterized by an artisanal process (plant C [30% NaCl, 8°C]). Lard samples were obtained at time 0 and after 7, 15, 30, 60, and 90 days of maturation. From each plant, 3 independent lots were analyzed. The diversity of live microbiota was evaluated by using classical plate counts and amplicon target sequencing of small subunit (SSU) rRNA. The main taxa identified by sequencing were
Acinetobacter johnsonii
,
Psychrobacter
,
Staphylococcus equorum
,
Staphylococcus sciuri
,
Pseudomonas fragi
,
Brochothrix
,
Halomonas
, and
Vibrio
, and differences in their relative abundances distinguished samples from the individual plants. The composition of the microbiota was more similar among plants A and B, and it was characterized by the higher presence of taxa recognized as undesired bacteria in food-processing environments. Oligotype analysis of
Halomonas
and
Acinetobacter
revealed the presence of several characteristic oligotypes associated with A and B samples.

IMPORTANCE
Changes in the food production process can drastically affect the microbial community structure, with a possible impact on the final characteristics of the products. The industrial processes of Lard d'Arnad production are characterized by a reduction in the salt concentration in the brines to address a consumer demand for less salty products; this can negatively affect the dynamics and development of the live microbiota and, as a consequence, can negatively impact the quality of the final product due to the higher abundance of spoilage bacteria. This study is an overview of the live microbiota that develop during lard manufacturing, and it highlights the importance of the use of traditional process to produce PDO from a spoilage perspective.
Complete Genome Sequence of Bacillus subtilis J-5, a Potential Biocontrol Agent
Authors: Jia Zhenhua , Jin Weiwei , Huang Yali , Song Shuishan
Published: June 2017

Bacillus subtilis
J-5 was isolated from tomato rhizosphere soil and exhibited strong inhibitory activity against
Botrytis cinerea
. To shed light on the molecular mechanism underlying the biological control on phytopathogens, the whole genome of this strain was sequenced. Genes encoding antimicrobial compounds and the regulatory systems were identified in the genome.
Genome Sequence of a Novel Human Gammapapillomavirus Isolated from Skin
Authors: Dutta Sankhadeep , Robitaille Alexis , Olivier Magali , Rollison Dana E. , Tommasino Massimo , Gheit Tarik
Published: June 2017

A new human gammapapillomavirus (HPV_MTS2) genome was isolated and fully cloned from a skin swab. The L1 open reading frame of HPV_MTS2 was 79% and 80% identical to those of its closest relatives, HPV type 149 (species Gamma-7 of the genus
Gammapapillomavirus
) and HPV isolate Dysk2 (GenBank accession no. KX781281), respectively, thus qualifying it as a new HPV type.
Draft Genome Sequences of Enterobacter cloacae Strains CAPREx E7 and CAPREx E2-2
Authors: Monson Rita E. , Honger Joseph , Rawlinson Alison , Salmond George P. C.
Published: June 2017

Enterobacter cloacae
strains CAPREx E7 and CAPREx E2-2 were isolated from Ghanaian yams at a London market. The draft genome sequences indicate that the two strains are similar, with genomes of 5,042,838 and 5,039,930 bp and 56.19% and 55.05% G+C content, respectively. Both strains encoded three different β-lactamases, including one of the AmpC family.