bluuebunny/crossref_metadata_2025 huggingface dataset:
Scattering strength uncertainty
Authors: Harrison Chris H.
Published: October 2013

A serious weakness in modeling shallow water reverberation is the uncertainty in bottom scattering strength and its angle-dependence. If the bottom scattering law is assumed to be a separable function of an incoming and outgoing angle it follows that the reverberation contains separable incoming and outgoing propagation terms. Thus the returning multipaths from a scattering patch are weighted directly by (the outgoing part of) the scattering law. This means that comparisons of reverberation and propagation angle-dependence on a vertical receiving array have the potential to reveal the scattering law directly. In this paper we discuss a reverberation experiment with complementary propagation measurements using a VLA and a broadband source to deduce scattering law angle-dependence and absolute scattering strength. The approach is justified by some analysis, and findings are compared with the numerical results of a new multistatic sonar model, SUPREMO. The experiment was conducted in a fairly flat bottomed part of the Mediterranean south of Sicily during BOUNDARY2002.
Internal gravity waves and horizontal refraction of sound in the ocean
Authors: Godin Oleg A. , Voronovich Alexander G. , Zavorotny Valery U.
Published: October 2013

Horizontal refraction, i.e., the deviation of acoustic propagation paths from the source–receiver vertical plane, is usually weak in the ocean. In this paper, a perturbation approach [O. A. Godin, J. Comput. Acoust. 10, 123–151 (2002)] to describe horizontal refraction within the ray and the ‘‘vertical modes—horizontal rays’’ theories is extended to media with a combination of stochastic and deterministic inhomogeneities and subsequently utilized to quantify 3-D acoustic effects due to internal gravity waves. Within the perturbation approach, statistical moments of adiabatic mode amplitude and phase and ray travel time are given explicitly by integrals of respective moments of cross-range derivatives of environmental parameters along the trajectory of the sound wave in an unperturbed (range-dependent) medium. Specific scenarios considered simulate conditions of recent propagation experiments. In shallow water, internal wave soliton-induced horizontal refraction can result in travel time biases O(10 ms) at propagation ranges as small as 10 km. In deep water, at ranges about 1000 km horizontal refraction due to internal waves with the Garrett–Munk spectrum leads to acoustic travel times being O(10 ms) less than in 2-D simulations. Without the internal waves, the travel time bias is found to be smaller by an order of magnitude. [Work supported by ONR.]
Picosecond transient grating acoustic measurements of thin films, microfluidic networks, and microphononic bandgap structures
Authors: Rogers John
Published: October 2013

We describe some new methods for transient grating (TG) photoacoustic measurements, and summarize their use in high frequency acoustic waveguide analysis of a variety of samples with dimensions smaller than 100 microns. This research is motivated in part by the growing interest in micro- and nanostructures whose mechanical and acoustic properties are important either for basic study or device design. Although the conventional TG technique provides a convenient method for exciting and detecting acoustic waves in bulk samples, it is not well suited to microsystems, where signal levels can be low and acoustic dispersion (i.e., variation in acoustic velocity with wavelength) can be pronounced. Here we illustrate how specially designed diffractive optics and imaging lenses remove these limitations by enabling convenient means for: (i) generating and overlapping many (up to 10 has been demonstrated) excitation pulses for launching complex, user-definable acoustic waveforms that enable single-shot measurements of dispersion; and (ii) providing a phase-stabilized heterodyne detection scheme that enhances the sensitivity of the measurement and simplifies many of the alignment procedures. We describe our application of these methods to a range of samples, including thin films and multilayer assemblies, optical fibers, microfluidic networks, and microphononic bandgap structures.
Flexural waves on narrow plates
Authors: Norris Andrew
Published: October 2013

Flexural wave speeds on beams or plates depend upon the bending stiffnesses, which differ by a well-known factor depending on the Poisson’s ratio. A quantitative analysis of a plate of finite lateral width displays the plate-to-beam transition, and permits asymptotic analysis that shows the dependence on the width. Orthotropic plates are analyzed using both the Kirchhoff and Kirchhoff–Rayleigh theories, and isotropic plates are considered for Mindlin’s theory with and without rotational inertia. A frequency dependent Young’s modulus for beams or strips of finite width is suggested, although the form of the correction to the modulus is not unique and depends on the theory used. The sign of the correction for the Kirchhoff theory is opposite to that for the Mindlin theory. These results indicate that the different plate and beam theories can produce quite distinct behavior. This divergence in predictions is further illustrated by comparison of the speeds for antisymmetric flexural modes on narrow plates. The four classical theories predict limiting wave speeds as the plate width vanishes, but the values are different in each case. The deviations can be understood in terms of torsion and how each theory attempts, or fails, to approximate this effect.
Balanced noise control design: A case study for co-generation power plant
Authors: Ma Yong , Hertil Salem
Published: October 2013

Power generation plant generally requires noise mitigation treatment to achieve the specified noise regulations. In this paper, a case study of the noise control design for a cogeneration power plant was presented. Major noise sources included two GE gas combustion turbines, two generators, two heat recovery steam generators (HRSGs), one steam turbine and generator, one 12-cell cooling tower, and other accessory equipment. The acoustic modeling software Cadna/A was used to predict the noise contributions from sources. During the acoustic modeling, alternative noise mitigation measures underwent two specific investigations before they were chosen as a noise solution recommendation. The first was to determine the technical feasibility of attenuating the source equipment. The second was to perform a cost benefit analysis, necessary to find the most cost-effective solution. For example, several acoustic wall and roof assemblies were entered into the acoustic model and the acoustic performance of the ventilation system was varied until we were able to arrive at the most economical acoustic solution. This is the premise on which so called balanced design is based.
Observed intraglottal pressures, their analytic representations, and driving forces for two-mass models
Authors: Scherer Ronald C. , Zhai Guangnian , Zhu Zipeng , Fulcher Lewis
Published: October 2013

Multimass modeling of phonation should be based on valid aerodynamic characteristics. Measured glottal wall pressures over a wide range of glottal geometries and transglottal pressures were used to obtain average driving forces on the surfaces of two-mass models of phonation. A Plexiglas model of the larynx was used for this purpose. Predictions from the classic equations of Ishizaka and Flanagan were compared to these driving forces and movies of the calculated motions of the two-mass models were produced. The data show that the magnitudes of the negative pressures on the lower glottal region tend to be considerably less than those predicted by the Ishizaka–Flanagan equations, which leads to an increase in the number of cycles (longer time) for the vocal folds to reach steady state, lower peak volume flows, and larger open quotients. Subsequently, analytic expressions were used to represent the intraglottal pressures, with special attention to the entrance losses and the form used to describe the Poisseuille frictional effects, and their accuracy was assessed by a comparison with the measured flow rates and pressures. Results from the analytic representations were compared with those generated from the Ishizaka and Flanagan formulation. [Work supported by NIH Grant No. 2 R01 DC03577.]
1/f dynamics in the urban soundscape
Authors: Botteldooren Dick , De Coensel Bert , De Muer Tom
Published: October 2013

Urban soundscapes are characterized by much more than loudness alone. Subjective description has been used by many researchers to grasp these additional dimensions, but very little objective criteria are found in literature. In this paper the dynamics of the soundscape is proposed as a potential indicator. By analyzing loudness and pitch fluctuations in longer sound fragments recorded in urban environment, 1/f spectral behavior at frequencies ranging from 0.01 to 10 Hz was discovered. Such behavior is typical for complex systems and was found to be very common in (classical) music, already in the seventies. Some hypotheses will be given on the origin of this frequency dependence of urban-soundscape dynamics. The possibility of discriminating soundscapes on the basis of the frequency dependence of loudness and pitch fluctuation will be illustrated. For this purpose the urban soundscapes are compared to ‘‘extreme’’ soundscapes that have a very distinct character that is clear to every observer.
Phase matching methods and their use to approximate resonances from various elastic targets
Authors: Werby M. F. , Überall H.
Published: October 2013

This paper considers acoustic scattering from submersed, elongated elastic objects, i.e., solid spheroids and finite-length cylinders. Surface waves are generated on the objects by incident acoustic waves; they can cause resonances in the objects’ vibrations which become evident in the scattered acoustic amplitudes. As it has been shown previously, the resonance frequencies can be obtained by a phase matching condition for multiply circumnavigating surface waves as they propagate on the object over closed paths. Comparing with calculated resonances in the scattering amplitude, it is found that the phase matching condition furnishes correct values for the calculated resonance frequencies for the case of Rayleigh-type surface waves. For spheroids and cylinders of larger aspect ratio, it is shown that bar-wave induced eigenfrequencies may also be used to approximate the calculated resonance frequencies.
Laboratory measurements of noise generation by shoaling breakers
Authors: Means Steven L. , Gendron Paul J.
Published: October 2013

Simultaneous measurements of the surface gravity wave field, void fraction entrained during breaking, and the generated acoustic spectra were made in a sand beached wave tank at the Center for Applied Coastal Research at the University of Delaware during April 2002. The tank has the dimensions of 30 m (l)×2 m (w)×1.5 m (d) and a 0.2-mm sand beach. Four hydrophones were distributed along the sand beach beneath the region of active breaking. Wave gauges measured surface gravity wave properties along the beach cross-shore. Conductivity and temperature probes allowed for the measurement of the void fraction of the entrained bubble cloud. A video camera captured the evolution of the entrained bubble cloud through the tank’s PlexiglasTM side panel. The paper presents generated acoustic power levels as a function of surface wave amplitude and period. Initial results in obtaining the relationships between void fractions of the entrained bubble clouds and the spectral components of the generated acoustic signal will also be discussed. [Work supported by ONR base funding at NRL.]
Functional segregation of segmental features, pitch-accents, and nondistinctive suprasegmental features in working memory
Authors: Tanaka Akihiro , Mori Koichi , Takano Yohtaro
Published: October 2013

Japanese has pitch-accent which contribute to lexical distinctiveness just as segmental features. A dual-task experiment was conducted to examine the independence among segmental features, pitch-accents, and nondistinctive suprasegmental features in working memory. Japanese speakers of Tokyo dialect participated in the experiment. The primary task was a working memory task which required the retention of both segmental and suprasegmental features of nonsense words. The suprasegmental features were either regular pitch-accent of Tokyo dialect or pseudopitch changes that do not exist in a Japanese accent pattern. The secondary task was silent mouthing of irrelevant verbal material either without putative pitch change, with pitch accent, or with pseudopitch change, that was performed during the retention period of the primary task. The results revealed selective interference according to distinctivity of pitch patterns in native speakers of Tokyo dialect, suggesting functional segregation between distinctive and nondistinctive suprasegmental features. In contrast, functional segregation was not observed in ‘‘non-native’’ speakers of Tokyo dialect, suggesting that the prosody of the non-native dialect acts as ‘‘second language.’’ Additionally, in both groups, suprasegmental processing did not interfere with the retention of segmental features. The results suggest that there are at least three substores for segmental features, pitch-accents, and nondistinctive suprasegmental features.
Fisher information for a Gaussian random variable with unequal real and imaginary covariances: Derivation and application to beamforming
Authors: Collier Sandra L. , Wilson D. Keith
Published: October 2013

There are many physical situations in which a received signal may be modeled as a complex Gaussian random variable. One such situation occurs when an acoustic wave is strongly scattered as a result of propagation through a random medium such as the atmosphere or ocean. However, there are also many conditions under which this model fails to provide an adequate representation. A specific example is the geometric acoustics regime, in which diffraction and scattering by the medium are both weak and the variance of the phase fluctuations is much larger than the variance of the log-amplitude fluctuations. The reduced wavefunction is the wavefunction of a signal propagating in an inhomogeneous medium normalized by the wavefunction in free space. A statistical model is developed for a reduced wavefunction whose real and imaginary components are Gaussian random variables with unequal covariances. A linear transformation is performed and the probability density function of the received signal at a passive array is calculated. The Fisher information is calculated for special conditions of the transformation that are of interest to acoustic beamforming. The coupling of the Cramer–Rao lower bounds on the parameter estimates (e.g., the angles of arrival, source phase, and medium parameters) is addressed.
Development of a device for reduction of low-frequency sound transmission reduction in small launch vehicles
Authors: Griffin Steven F. , Lane Steven A.
Published: October 2013

Launch acoustic loads have the potential to damage sensitive payloads within a payload fairing, often requiring more structural mass to withstand these loads than would otherwise be necessary to survive launch. A typical payload fairing will exhibit several cavity resonance modes related to its axial length. These modes are excited both by the vibrations transmitted through the structure during launch, and by acoustic ground reflections coupled into the system during the initial launch phase. Conventional acoustic blankets mitigate the acoustic environment within a payload fairing, but are generally only effective above 250 Hz. In this work we present an Adaptive Vibro-Acoustic Device (AVAD), which is designed to actively and passively absorb acoustic energy in a payload fairing at frequencies below 250 Hz. To date, a prototype has been designed and tested for application to a sounding rocket experiment, Vibro-Acoustic Launch Protection Experiment (VALPE), being conducted by the Air Force Research Laboratory. Prototype test results as well as projected performance in flight will be presented.
Geoacoustic inversion by using the broadband signals
Authors: Li Zhenglin , Zhang Renhe , Liu Jianjun , Li Fenghua , Xiao Ling
Published: October 2013

Three different methods are used to invert the sea bottom parameters (sound speed, density, and attenuation) based on the fact that each parameter has different effect on the sound fields. First, the vertical reflection coefficients of sea bottom and the bottom acoustic impedance are inverted from the light-bulb signals. Second, the matched-field processing method is used to the propagation bomb signal to split the density and sound speed from the impedance with an assumed attenuation. In the end, the attenuation coefficients are gotten from the transmission loss data at the different frequency band. [Work supported by the National Natural Science Foundation of China.]
Identifying intrinsic constituents of focus through ‘‘imitation via restoration.’’
Authors: Xu Yi , Xu Ching X. , Sun Xuejing
Published: October 2013

In this study we test the hypothesis that although certain parts of an observed intonation may seem dispensable in perception tests, they nevertheless are consistently produced by speakers. We refer to all consistently produced parts of an intonation as its ‘‘intrinsic constituents.’’ To identify the intrinsic constituents, we developed an experimental paradigm called ‘‘imitation via restoration.’’ In this paradigm, the intonation under scrutiny is first recorded by a native speaker. Then words carrying a potential constituent of the intonation are replaced by a loud noise. During the experiment, the sentence containing the replacement noise is presented to the subjects together with the text. The subjects’ task is to repeat the sentence in exactly the same way as they hear it. The consistency with which subjects restore the missing parts of the target intonation would therefore provide a reasonable indication as to which of them are truly intrinsic to the intonation. Our first such experiment was conducted on determining whether focus consists of only on-focus pitch range expansion or it also involves obligatory post-focus pitch range suppression. Eight native speakers of Beijing Mandarin participated as subjects. Preliminary results have provided supporting evidence for the dual-component hypothesis.
Can listeners hear who is singing? A comparison of three-note and six-note discrimination tasks
Authors: Erickson Molly , Perry Susan
Published: October 2013

Timbre is typically investigated as a perceptual attribute that differentiates a sound source at one pitch and loudness; however, singers are believed to have one timbre and singers with similar timbres are thought to comprise a voice category. Yet, by the technical definition, each singer would have a set of timbres across pitch, vowel, and loudness combinations, so that each singer or singing voice category might have a timbre template which allows listeners to recognize one singer or category of singer. This paper investigated the ability of listeners to identify which pitch in an ascending or descending sequence of three or six stimuli was sung by a different singer within and across voice categories. For three-note sequences, the task was difficult and listeners chose the most dissimilarly pitched stimulus as coming from the oddball singer. For six-note sequences, the detection of the oddball singer was much improved, with cross-category comparisons being the easiest. These results support the idea that timbre should be understood as a transformation that connects the different sounds of one source, that a ‘‘rich’’ set of exemplars is necessary to discover the trajectory, and that singers of the same category have similar timbre transformations.
The acoustic field of singing humpback whales in the vertical plane
Authors: Au Whitlow W. L. , Pack Adam A. , Lammers Marc O. , Herman Louis , Andrews Kimberly , Deakos Mark
Published: October 2013

A vertical array of five hydrophones was used to measure the acoustic field of singing humpback whales. Once a singer was located, two swimmers with snorkel gear were deployed to determine the orientation of the whale and to position the boat so that the array could be deployed in front of the whale at a minimum standoff distance of 10 m. The spacing of the hydrophones was 7 m with the deepest hydrophone deployed at depth of 35 m. An 8-channel TASCAM recorder having a bandwidth of 24 kHz was used to record the hydrophone signals. The location of the singer was determined by computing the time of arrival differences between the hydrophone signals. The maximum source level varied between individual units in a song, with values between 180 and 190 dB. The acoustic field determined by considering the relative intensity of higher frequency harmonics in the signals indicate that the sounds are projected in the horizontal direction with the singer’s head canted downward 45 to 60°. High-frequency harmonics extended beyond 24 kHz, suggesting that humpback whales may have an upper frequency limit of hearing as high as 24 kHz.
Evoked potential measurement of the masked hearing threshold of a Pacific white-sided dolphin (Lagenorhynchus obliquidens)
Authors: Au Whitlow W. L. , Jeanette Thomas , Western A. , Rameriz Kenneth M.
Published: October 2013

The masked hearing threshold of a Pacific white-sided dolphin (Lagenorhynchus obliquidens) was determined by measuring the animal’s auditory brainstem response (ABR). The dolphin was trained to wear surface-contact electrodes embedded in suction cups and to swim into a hoop centered at 1 m below the water surface facing a sound projector 5 m away. Broadband transient signals with center frequencies of 8, 16, 32, 64, 80, and 100 kHz were used as the stimuli. ABR signals were measured by digitizing the electrode signals in 32 point blocks at a sampling rate of 20 kHz. Five hundred blocks were averaged in order to obtain an ABR. The response latency for suprathreshold threshold signals was approximately 1.9 ms with the highest peak-to-peak ABR amplitude of approximately 2.8 uV occurring for a signal frequency of 64 kHz. The spectrum of the ABR signal was similar to that of Tursiops truncatus, with a major peak at 1120 Hz and a secondary peak at 664 Hz. Threshold was determined by progressively reducing the amplitude of the stimulus until an evoked potential could not be detected. The energy signal-to-noise ratio within an integration window at threshold varied between 1 and 8 dB.
Evidence of peripheral nonlinearity in psychometric function slopes of forward-masked tones at 250 and 4000 Hz
Authors: Schairer Kim S. , Jesteadt Walt
Published: October 2013

Results from this laboratory suggest that the compressive nonlinearity of the basilar membrane is reflected in slopes of psychometric functions (PFs) for forward-masked tones of 4000 Hz. Briefly, as the signal level at the threshold increases, slopes of PFs decrease. Many other behavioral measures have suggested significant nonlinearity at high frequencies, but results are less consistent at low frequencies. The purpose of the current study was to use a PF slope to investigate nonlinearity using low- and high-frequency stimuli in the same normal-hearing adults. Signals were 250 or 4000 Hz, 10-ms (5-ms rise/fall) duration, presented with a 10-ms delay. The on-frequency forward-maskers were 200-ms (2-ms rise/fall), presented at levels of 30-, 50-, 70-, and 90-dB SPL in separate conditions. A two-track, two-interval-forced-choice adaptive procedure was used, with decision rules to estimate 71% correct on one track, and 87% on the other track. Data from both tracks were combined to estimate PF slopes. PF slopes were steeper in low-threshold conditions and shallower in high-threshold conditions for both frequencies. These results suggest a significant nonlinearity at 250 Hz. [Work supported by NIDCD.]
Acoustic streaming at high amplitudes in plane and cylindrical channels
Authors: Hamilton Mark F. , Ilinskii Yurii A. , Zabolotskaya Evgenia A.
Published: October 2013

At low amplitudes, acoustic streaming generated by standing waves in a plane channel is similar to streaming in a cylindrical tube. However, numerical simulations based on fully nonlinear equations for the streaming flow reveal significant differences at high amplitudes, at which Reynolds numbers for the streaming exceed unity. In these calculations, the acoustic field driving the streaming is prescribed independently. With increasing acoustic amplitude, the centers of the streaming vortices shift, the streamlines lose their symmetry, and the transverse velocity distribution departs from a parabolic profile. The vortex centers shift in opposite directions in the cylinder and the plane channel. In the cylinder the vortex centers move toward antinodes of the acoustic velocity field as the amplitude is increased, whereas in the plane channel the centers move toward the nodes. Simultaneously, the transverse streaming velocity profiles are observed to become narrower in some regions and broader in others. In general, these nonlinear streaming effects are more pronounced for the plane channel and therefore must be taken into account for Reynolds numbers smaller than for the cylinder. The influence of harmonic generation in the acoustic field will also be discussed. [Work supported by ONR.]
Growth of interleaved masking patterns for cochlear implant listeners at different stimulation rates
Authors: Kwon Bom Jun , van den Honert Chris , Parkinson Wendy
Published: October 2013

This study investigates the pattern of growth of masking (GOM) for interleaved masking with Nucleus cochlear implant users. For an interleaved masking paradigm, where the masker and probe overlap in a same time window, the masker may have contrasting effects: it may increase the threshold (as a masker normally does) or decrease it due to a neural summation effect, facilitating detection of the probe. Several stimulation rates and masker levels were tested to examine under what conditions what phenomenon would occur. The results indicated that, in most of the conditions, the amount of masking was positive, i.e., the facilitating effect was not consistently observed. However, the slope of the GOM appears to be dependent upon the stimulation rate: the higher the stimulation rate, the lower the slope, implying that the facilitating effect might be always present and make a bigger impact on overall masking as the stimulation rate becomes high. The amount of masking was also often nonzero (positive) even when the masker was below the threshold level. Overall, the present findings indicate that interleaved masking should be handled with care to understand cochlear implant users speech perception and improve speech coding, as it contains some nontraditional aspects of masking.
Seabottom geoacoustic inversion from reverberation vertical coherence in shallow water
Authors: Zhou Ji-Xun , Zhang Xue-Zhen
Published: October 2013

Shallow-water reverberation from one shot offers a continuous spatial sampling of the surrounding sound field up to several tens of kilometers from the source. It involves a bottom-controlled two-way sound propagation and bottom scattering process, and brings back rich information on seabottom geoacoustic parameters. Thus, geoacoustic inversion from reverberation in shallow water is very attractive for saving time and cost compared with inversion from propagation measurements. In this paper, the reverberation vertical coherence in shallow water, derived by ray-mode analogies [Zhou, Acta Oceanol. Sinica 1, 212–218 (1979)], is converted back to a more familiar summation of normal-modes. Measured reverberation cross-correlation coefficients as a function of time, frequency and hydrophone separation at different areas with a flat seabed are in good agreement with theoretical predictions. From the best match between the measurements and predictions of the reverberation vertical coherence, sound velocities and attenuations in sediments from China seas, including the ASIAEX01 site, have been inverted at low and mid-frequencies. [Work supported by ONR and CAS.]
Richard H. Bolt: Scientist, educator and friend
Authors: Beranek Leo L.
Published: October 2013

The author will discuss his close relation to Dick Bolt, starting with their first meeting in 1938. This will include Bolt’s doctoral years at the University of California, his National Research Fellowship in Physics at MIT, his contributions to the World War II effort, his tenured appointment, guidance of students and formation of the Acoustical Laboratory at MIT, and his co-founding of and subsequent participation in Bolt Beranek and Newman. Dick’s principal contributions to the field of acoustics, to education and to the Acoustical Society of America will be presented up until 1957, after which his talents were largely taken over by national missions, which are mentioned. Richard H. Bolt was an inspiring educator, researcher and organizer. He truly was a national treasure.
Acoustic swimbladder resonance spectroscopy: Fundamentals in scattering theory
Authors: Francis David T. I. , Foote Kenneth G.
Published: October 2013

A history of the physics of acoustic resonance is given. The primary, low-frequency, resonant scattering model for air bubbles in water [Minnaert (1933)] is reviewed. Subsequent applications to swimbladdered fish, including models by Andreeva (1964), Love (1978), and Feuillade and Nero (1998), among others, are developed. Reference is made to exemplary measurements of backscattering by Holliday (1972) and Loevik and Hovem (1979), and of forward scattering, or absorption, by Weston (1967) and Diachok (2000), among others. High-frequency resonances are also described, with presentation of both analytical and numerical results for the immersed air bubble. Comparison of these validates the numerical, boundary-element method (BEM). The BEM allows high-frequency resonances to be studied for swimbladders of realistic shapes under pressure and for typical wave-number-swimbladder length products of order 10–40. Implications of high-frequency swimbladder resonance for auditory function in fish are mentioned. [Work supported by ONR.]
Comparison of broadband mode arrivals at ranges of 3515 km and 5171 km in the North Pacific
Authors: Wage Kathleen E. ,   the ATOC Group
Published: October 2013

The Acoustic Thermometry of Ocean Climate (ATOC) provided an opportunity to observe signals propagating in the low-order modes of the ocean waveguide. Understanding the fluctuations of these mode signals is an important prerequisite to using them for tomography or other applications. In previous work, we characterized the cross-mode coherence and temporal variability of the low-order mode arrivals at 3515 km range [Wage et al., J. Acoust. Soc. Am. (in press)]. This study compares the mode arrivals for two different ranges : 3515 km and 5171 km, using data from the ATOC vertical line arrays at Hawaii and Kiritimati. We discuss the mode intensity and coherence statistics for each of the arrays and examine mean arrival time trends over the year-long deployment. Experimental results are compared to PE simulations of propagation through a realistic background environment perturbed by internal waves of varying strengths. The dependence of mode statistics on the path-dependent changes in the background sound speed and the parameters of the internal wave field is explored. [Work supported by an ONR Ocean Acoustics Young Faculty Award.] a)A. B. Baggeroer, T. G. Birdsall, C. Clark, J. A. Colosi, B. D. Cornuelle, D. Costa, B. D. Dushaw, M. A. Dzieciuch, A. M. G. Forbes, B. M. Howe, D. Menemenlis, J. A. Mercer, K. Metzger, W. H. Munk, R. C. Spindel, P. F. Worcester, and C. Wunsch.
A cocktail-party listening experiment with children
Authors: Wightman Frederic , Callahan Michael , Kistler Doris
Published: October 2013

In an experiment modeled after one reported recently by Brungart and Simpson [J. Acoust. Soc. Am. 112, 2985–2995 (2002)], 38 children (ages 4–16) and 10 adults responded to a monaural target speech signal in the presence of one or two distracter speech signals. The target speaker was a male and the distracter speakers were females. When two distracters were present they were in different ears. Performance at several different target ear S/N was measured and psychometric functions were fitted to estimate threshold, or the 50% performance level. The youngest children required approximately 20 dB higher S/N than adults to achieve threshold with a single distracter. This difference disappeared by age 16. The impact of adding the contralateral distracter, which is thought to contribute only informational masking, was roughly constant across age, however. Adult thresholds increased about 11 dB and the thresholds for the youngest children increased about 10 dB. This was surprising given previous experiments that showed much larger informational masking effects in young children. Also inconsistent with previous results is the lack of individual differences. Nearly all listeners showed almost the same contralateral distracter effect. [Work supported by NICHD.]
Tactual displays of consonant voicing to supplement speechreading
Authors: Yuan Hanfeng , Reed Charlotte M. , Durlach Nat
Published: October 2013

This research is concerned with the development of tactual displays of voicing to supplement speechreading in persons with profound hearing impairment. The voicing cue was based on the onset-time difference between amplitude envelopes derived from two different filtered bands of speech (a low-pass band at 350 Hz and a high-pass band at 3000 Hz). This envelope-onset-asynchrony cue was presented through a multifinger tactual stimulator. The amplitude envelopes of the low- and high-frequency bands were used to modulate the amplitude of a 50-Hz sinusoid presented to the thumb and a 250-Hz sinusoid presented to the index finger (respectively). Acoustic measurements of envelope-onset asynchrony in CVC syllables indicate that this timing difference provides a reliable and robust cue for voicing. Perceptual measurements were made of the ability to discriminate (1) temporal-onset order for sinusoidal signals (fixed in frequency but roving in amplitude and duration); and (2) eight pairs of consonant contrasts in CVC syllables under conditions of speechreading alone, tactual cue alone, and the combined condition. Relations among the results for the two perceptual tasks, as well as for the associated acoustic measurements, will be discussed. [Work supported by NIH/NIDCD.]
Deduction of the acoustic impedance of the ground via a simulated three-dimensional microphone array
Authors: Kirkpatrick Alberts W. C. , Sanchez Kevin J.
Published: October 2013

While commonly used ground impedance deduction methods often utilize pairs of vertically separated microphones, deployed arrays rarely have this configuration, which increases the difficulty in automatically deducing local ground impedance from these arrays. The ability to deduce ground impedance using random sounds incident on a three-dimensional array would increase, for example, the accuracy of estimated elevation angles. The methods described by the American National Standards Institute Method for Determining the Acoustic Impedance of Ground Surfaces are extended to simulate deducing ground impedance by a three-dimensional array. Ground parameters indicative of grassland are successfully determined using a simulated three-dimensional array.
Serotype distribution of invasive Streptococcus pneumoniae in Canada after the introduction of the 13-valent pneumococcal conjugate vaccine, 2010–2012
Authors: Demczuk Walter H.B. , Martin Irene , Griffith Averil , Lefebvre Brigitte , McGeer Allison , Lovgren Marguerite , Tyrrell Gregory J. , Desai Shalini , Sherrard Lindsey , Adam Heather , Gilmour Matthew , Zhanel George G. ,   Toronto Bacterial Diseases Network,   Canadian Public Health Laboratory Network
Published: October 2013

The introduction of the 7-valent pneumococcal vaccine (PCV7) in Canada was very effective in reducing invasive pneumococcal disease (IPD) in children; however, increases of non-PCV7 serotypes have subsequently offset some of these reductions. A 13-valent pneumococcal vaccine (PCV13) targeting additional serotypes was implemented between 2010 and 2011, and in 2012 changes in the incidence of disease and the distribution of IPD serotypes began to emerge. The incidence of IPD in children <5 years of age declined from 18.0 to 14.2 cases per 100 000 population between 2010 and 2012; however, the incidence in ages ≥5 years remained relatively unchanged over the 3-year period, at about 9.7 cases per 100 000 population. From 2010 to 2012, PCV13 serotypes declined significantly from 66% (224/339) to 41% (101/244, p < 0.001) in children <5 years of age, and from 54% (1262/2360) to 43% (1006/2353, p < 0.001) in children ≥5 years of age. Serotypes 19A, 7F, 3, and 22F were the most common serotypes in 2012, with 19A decreasing from 19% (521/2727) to 14% (364/2620, p < 0.001), 7F decreasing from 14% (389/2727) to 12% (323/2620, p = 0.04), and 22F increasing from 7% (185/2727) to 11% (279/2620, p < 0.001) since 2010. Serotype 3 increased from 7% (23/339) to 10% (24/244) in <5-year-olds (p = 0.22) over the 3-year period. The highest rates of antimicrobial resistance were observed with clarithromycin (23%), penicillin using meningitis breakpoints (12%), clindamycin (8%), and trimethoprim–sulfamethoxazole (6%). Shifts in the distribution of IPD serotypes and reductions in the incidence of disease suggest that current immunization programs in Canada are effective in reducing the burden of IPD in children. While we acknowledge the limited data on the effectiveness of the PCV13 vaccine, to our knowledge, this study represents one of the first descriptions of the potential impact of the PCV13 vaccine in the Canadian population. Continued surveillance will be important to recognize replacement serotypes, to determine the extent of herd immunity effects in nonpaediatric populations, and to assess the overall effectiveness of PCV13 in reducing IPD in Canada.
Bariatric surgery relieves type 2 diabetes and modulates inflammatory factors and coronary endothelium eNOS/iNOS expression in db/db mice
Authors: Liu Bingyang , Kuang Lirun , Liu Jingang
Published: October 2013

Overexpression of endothelial nitric oxide synthetase (eNOS)/inducible nitric oxide synthase (iNOS) and inhibition of inflammatory factors can improve vascular function. We hypothesized that bariatric (gastric bypass) surgery could inhibit inflammatory factors and improve the eNOS/iNOS expression of coronary arterioles in the db/db mice. The animals were randomly allocated to the following groups: sham-operated lean mice, lean mice that underwent surgery, sham-operated db/db mice, and db/db mice that underwent surgery (5, 10, 20, and 30 days post-operation). The plasma levels of adiponectin, ghrelin, and IL-6, as well as the protein expression of eNOS/iNOS in coronary arterioles were measured with Western blot. Bariatric surgery decreased body mass and blood glucose levels in db/db mice. Ghrelin receptor and GHS-R1a expression in the hypothalamus were increased in db/db mice, but surgery attenuated GHS-R1a expression. Bariatric surgery elevated plasma concentration and protein expression of adiponectin and ghrelin, and attenuated plasma concentration and protein expression of IL-6. Coronary protein expression of eNOS and SOD2 was lower in the sham-operated db/db mice, and bariatric surgery increased eNOS and SOD2 expression. Gastric bypass surgery upregulates ghrelin and adiponectin expression, and decreases IL-6 expression, which might induce up-regulation of eNOS and SOD2, and down-regulation of iNOS. These interactions could counteract the endothelium dysfunction in type 2 diabetes mellitus.
White, brite, and brown adipocytes: the evolution and function of a heater organ in mammals
Authors: Li Yongguo , Lasar David , Fromme Tobias , Klingenspor Martin
Published: October 2013

Brown fat is a specialized heater organ in eutherian mammals. In contrast to the energy storage function of white adipocytes, brown adipocytes dissipate nutrient energy by uncoupling of mitochondrial oxidative phosphorylation, which depends on uncoupling protein 1 (UCP1). UCP1, as well as UCP2 and UCP3, belong to the family of mitochondrial carriers inserted into the inner mitochondrial membrane for metabolite trafficking between the matrix and the intermembrane space. UCP1 transports protons into the mitochondrial matrix when activated by a rise in free fatty acid levels in the cell. This UCP1-dependant proton leak drives high oxygen consumption rates in the absence of ATP synthesis and dissipates proton motive force as heat. The enormous heating capacity of brown fat is supported by dense vascularization, high rates of tissue perfusion, and high mitochondrial density in brown adipocytes.

It has been known for more than 50 years that nonshivering thermogenesis in brown fat serves to maintain body temperature of neonates and small mammals in cold environments, and is used by hibernators for arousal from torpor. It has been speculated that the development of brown fat as a new source for nonshivering thermogenesis provided mammals with a unique advantage for survival in the cold. Indeed brown fat and UCP1 is found in ancient groups of mammals, like the afrotherians and marsupials. In the latter, however, the thermogenic function of UCP1 and brown fat has not been demonstrated as of yet. Notably, orthologs of all three mammalian UCP genes are also present in the genomes of bony fishes and in amphibians. Molecular phylogeny reveals a striking increase in the substitution rate of UCP1 between marsupial and eutherian lineages. At present, it seems that UCP1 only gained thermogenic function in brown adipocytes of eutherian mammals, whereas the function of UCP1 and that of the other UCPs in ectotherms remains to be identified.

Evolution of thermogenic function required expression of UCP1 in a brown-adipocyte-like cell equipped with high mitochondrial density embedded in a well-vascularized tissue. Brown-adipocyte-like cells in white adipose tissue, called “brite” (brown-in-white) or “beige” adipocytes, emerge during adipogenesis and in response to cold exposure in anatomically distinct adipose tissue depots of juvenile and adult rodents. These brite adipocytes may resemble the archetypical brown adipocyte in vertebrate evolution. It is therefore of interest to elucidate the molecular mechanisms of brite adipocyte differentiation, study the bioenergetic properties of these cells, and search for the presence of related brown-adipocyte-like cells in nonmammalian vertebrates.
Analysis of blood flow in deformable vessels via a lattice Boltzmann approach
Authors: De Rosis Alessandro
Published: October 2013

In this paper, the lattice Boltzmann (LB) method is used in order to simulate non-Newtonian blood flows in deformable vessels. Casson's rheological model is adopted and a local correction to the relaxation time is implemented in order to modify the viscosity. The hyperelastic, hardening and anisotropic behavior of a flexible arterial wall is discussed and a closed-form solution is used to predict the deformed configuration of the vessel. A partitioned staggered-explicit strategy to couple the LB method and such analytical prediction is proposed.
TOWARDS A HOLOGRAPHIC THEORY OF COSMOLOGY — THREADS IN A TAPESTRY
Authors: NG Y. JACK
Published: October 2013

In this paper, we address several fundamental issues in cosmology: What is the nature of dark energy and dark matter? Why is the dark sector so different from ordinary matter? Why is the effective cosmological constant nonzero but so incredibly small? What is the reason behind the emergence of a critical acceleration parameter of magnitude 10-8 cm/s2 in galactic dynamics? We suggest that the holographic principle is the linchpin in a unified scheme to understand these various issues.
COSMOLOGICAL ZITTERBEWEGUNG
Authors: GIRDHAR PARTH , KOBAKHIDZE ARCHIL
Published: October 2013

We describe a new phenomenon of zitterbewegung of a free Dirac particle in cosmological spacetimes. Unlike the similar effect theorized by Schrödinger in 1930, the cosmological zitterbewegung is a real, physically attainable effect, which originates from the mixing of positive and negative frequency modes of a field operator in cosmological spacetimes. We briefly discuss the potential for observing this effect in laboratory experiments with trapped ions.
A SIMPLE SHORTCUT TO UNSUPERVISED ALIGNMENT-FREE PHYLOGENETIC GENOME GROUPINGS, EVEN FROM UNASSEMBLED SEQUENCING READS
Authors: MAURER-STROH SEBASTIAN , GUNALAN VITHIAGARAN , WONG WING-CHEONG , EISENHABER FRANK
Published: October 2013

We propose an extension to alignment-free approaches that can produce reasonably accurate phylogenetic groupings starting from unaligned genomes, for example, as fast as 1 min on a standard desktop computer for 25 bacterial genomes. A 6-fold speed-up and 11-fold reduction in memory requirements compared to previous alignment-free methods is achieved by reducing the comparison space to a representative sample of k-mers of optimal length and with specific tag motifs. This approach was applied to the test case of fitting the enterohemorrhagic O104:H4 E.coli strain from the 2011 outbreak in Germany into the phylogenetic network of previously known E.coli-related strains and extend the method to allow assigning any new strain to the correct phylogenetic group even directly from unassembled short sequence reads from next generation sequencing data. Hence, this approach is also useful to quickly identify the most suitable reference genome for subsequent assembly steps.
RECOGNISING DISCOURSE CAUSALITY TRIGGERS IN THE BIOMEDICAL DOMAIN
Authors: MIHĂILĂ CLAUDIU , ANANIADOU SOPHIA
Published: October 2013

Current domain-specific information extraction systems represent an important resource for biomedical researchers, who need to process vast amounts of knowledge in a short time. Automatic discourse causality recognition can further reduce their workload by suggesting possible causal connections and aiding in the curation of pathway models. We describe here an approach to the automatic identification of discourse causality triggers in the biomedical domain using machine learning. We create several baselines and experiment with and compare various parameter settings for three algorithms, i.e. Conditional Random Fields (CRF), Support Vector Machines (SVM) and Random Forests (RF). We also evaluate the impact of lexical, syntactic, and semantic features on each of the algorithms, showing that semantics improves the performance in all cases. We test our comprehensive feature set on two corpora containing gold standard annotations of causal relations, and demonstrate the need for more gold standard data. The best performance of 79.35% F-score is achieved by CRFs when using all three feature types.