bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Continuous and Truncated Ribs on Internal Blade Tip Cooling
Authors: Salameh Tareq , Sunden Bengt
Published: August 2013

In the present work, an experimental study related to turbulent flow inside the bend part of a U-duct geometry was performed concerning pressure drop and heat transfer. Such duct geometries can be found inside gas turbine blades, where the cooling air extracts heat from hot internal walls while it is flowing inside the cooling passage. Both friction factors and convective heat transfer coefficients were established inside the bend part of the U-duct for two different rib cases, namely continuous and truncated ribs with varying Reynolds number from 8,000 to 20,000. For the continuous rib case, the length of the ribs was equal to the height of the duct while in the truncated rib case two different rib lengths, i.e., 46 mm and 40 mm, respectively, were considered. The rib height-to-hydraulic diameter ratio, e/Dh, was 0.1 and the pitch ratio was 10. The test rig has been built in such a way that various experimental setups can be handled as the outer wall of the bend (turn) part of the U-duct can easily be removed and the ribs can be changed. Both the U-duct and the ribs were made from acrylic material to allow optical access for measuring the surface temperature by using a high-resolution measurement technique based on the narrow band thermochromic liquid crystals (TLC R35C5W) and a CCD camera placed facing the bend (turn) part of the U-duct. The calibration of the TLC is based on the hue-based color decomposition system using an in-house designed calibration box. The ribs were placed transversely to the direction of the main flow at the outer wall of the bend (turn) part where the wall was heated by an electrical heater. The pressure drop was almost identical for the continuous and truncated rib cases, while the heat transfer coefficient is 10% higher for the continuous rib case at Re = 20000. The uncertainties in the evaluated properties were 3% and 6% for the Nusselt number and friction factor, respectively.
Coupled Fluid-Structure Transient Thermal Analysis of a Gas Turbine Internal Air System With Multiple Cavities
Authors: Ganine Vlad , Javiya Umesh , Hills Nick , Chew John
Published: August 2013

This paper presents the transient aero-thermal analysis of a gas turbine internal air system through an engine flight cycle featuring multiple fluid cavities that surround a HP turbine disk and the adjacent structures. Strongly coupled fluid-structure thermal interaction problems require significant computational effort to resolve nonlinearities on the interface for each time step. Simulation times may grow impractical if multiple fluid domains are included in the analysis. A new strategy is employed to decrease the cost of coupled aero-thermal analysis. Significantly lower fluid domain solver invocation counts are demonstrated as opposed to the traditional coupling approach formulated on the estimates of heat transfer coefficient. Numerical results are presented using 2D FE conduction model combined with 2D flow calculation in five separate cavities interconnected through the inlet and outlet boundaries. The coupled solutions are discussed and validated against a nominal stand-alone model. Relative performance of both coupling techniques is evaluated.
Full-Coverage Film Cooling: Film Effectiveness and Heat Transfer Coefficients for Dense Hole Arrays at Different Hole Angles, Contraction Ratios, and Blowing Ratios
Authors: Goodro Matt , Ligrani Phil , Fox Mike , Moon Hee-Koo
Published: August 2013

Experimental results are presented for a full coverage film cooling arrangement which simulates a portion of a gas turbine engine, with appropriate streamwise static pressure gradient. The test surface utilizes varying blowing ratio along the length of the contraction passage which contains the cooling hole arrangement. For the different experimental conditions examined, film cooling holes are sharp-edged and streamwise inclined either at 20° or 30° with respect to the liner surface. The film cooling holes in adjacent streamwise rows are staggered with respect to each other. Data are provided for turbulent film cooling, contraction ratios of 1, 3, 4, and 5, blowing ratios (at the test section entrance) of 2.0, 5.0, and 10.0, coolant Reynolds numbers Refc of 10,000 to 12,000, freestream temperatures from 75°C to 115°C, a film hole diameter of 7 mm, and density ratios from 1.15 to 1.25. Non-dimensional streamwise and spanwise film cooling hole spacings, X/D and Y/D, are 6, and 5, respectively. When the streamwise hole inclination angle is 20°, spatially-averaged and line-averaged adiabatic effectiveness values at each x/D location are about the same as the contraction ratio varies between 1, 3, and 4, with slightly higher values at each x/D location when the contraction ratio Cr is 5. For each contraction ratio, there is a slight increase in effectiveness when the blowing ratio is increased from 2.0 to 5.0 but there is no further substantial improvement when the blowing ratio is increased to 10.0. Overall, line-averaged and spatially-averaged adiabatic film effectiveness data, and spatially-averaged heat transfer coefficient data are described as they are affected by contraction ratio, blowing ratio, hole angle α, and streamwise location x/D. For example, when α = 20°, the detrimental effects of mainstream acceleration are apparent since heat transfer coefficients for contraction ratios Cr of 3 and 5 are often higher than values for Cr = 1, especially for x/D > 100.
Phase transition of In/Si(111)-4×1 surface studied with low-energy electron diffraction
Authors: Yeo Jonghoon , Shim Hyungjoon , Lee Geunseop
Published: August 2013

The structural phase transition of an In/Si(111) surface was examined by low-energy electron diffraction (LEED). The transition temperature between the room-temperature 4×1 structure and low-temperature 8×2 structure was determined from the changes in the LEED intensity of the half-order (×2), eighth-order (8×), and fourth-order (4×) spots with temperature. The transition temperatures determined independently from three sets of LEED beam spots were within 1 K. The differently prepared In/Si(111)−4×1 surfaces, which had similar LEED quality at room temperature, showed variations of the transition temperature. The differences in the measured transition temperatures were attributed to the effects of the additional In adatoms remaining on the surface during the formation of a 4×1 reconstruction. The In adatoms suppress the condensation of the (8×2) phase, decreasing the phase transition temperature and rounding the otherwise sharp transition.
Influence of Al/TiN/SiO2 structure on MOS capacitor, Schottky diode, and fin field effect transistors devices
Authors: Lima Lucas P. B. , Diniz José A. , Radtke Claudio , dos Santos Marcos V. P. , Doi Ioshiaki , Godoy Fo José
Published: August 2013

Titanium nitride (TiN) films were tested for their suitability as upper electrodes in metal–oxide–semiconductor (MOS) capacitors and Schottky diodes and as metal gate electrodes in fin field effect transistor devices. TiOxNy formation on TiN surfaces was confirmed by x-ray photoelectron spectroscopy and appears to be associated with exposure of the metal electrodes to ambient air. In order to avoid the formation of TiOxNy and TiO2, a layer of aluminum (Al) was deposited in situ after the TiN deposition. TiN work function was calculated for the devices to study how dipole variation at the interface TiN/SiO2 influences TiN work function. TiOxNy and TiO2 formation at the film surface was found to affect the dipole variations at the TiN/SiO2 interface increasing the dipole influence on MOS structure. Furthermore, the estimated values TiN work function are suitable for complementary metal–oxide–semiconductor (CMOS) technology. Finally, this work had shown that Al/TiN structure can be used in CMOS technology, especially on n-type metal–oxide–semiconductor field effect transistor devices.
Particle smoothers in sequential geoacoustic inversion
Authors: Yardim Caglar , Gerstoft Peter , Hodgkiss William S.
Published: August 2013

Sequential Bayesian methods such as particle filters have been used to track a moving source in an unknown and space/time-evolving ocean environment. These methods treat both the source and the ocean parameters as non-stationary unknown random variables and track them via the multivariate posterior probability density function. Particle filters are numerical methods that can operate on nonlinear systems with non-Gaussian probability density functions. Particle smoothers are a natural extension to these filters. A smoother is appropriate in applications where data before and after the time of interest are readily available. Both past and “future” measurements are exploited in smoothers, whereas filters just use past measurements. Geoacoustic and source tracking is performed here using two smoother algorithms, the forward-backward smoother and the two-filter smoother. Smoothing is demonstrated on experimental data from both the SWellEx-96 and SW06 experiments where the parameter uncertainty is reduced relative to just filtering alone.
Priming of lowpass-filtered speech affects response bias, not sensitivity, in a bandwidth discrimination task
Authors: Freyman Richard L. , Griffin Amanda M. , Macmillan Neil A.
Published: August 2013

Priming is demonstrated when prior information about the content of a distorted, filtered, or masked auditory message improves its clarity. The current experiment attempted to quantify aspects of priming by determining its effects on performance and bias in a lowpass-filter-cutoff frequency discrimination task. Nonsense sentences recorded by a female talker were sharply lowpass filtered at a nominal cutoff frequency (F) of 0.5 or 0.75 kHz or at a higher cutoff frequency (F + ΔF). The listeners' task was to determine which interval of a two-interval-forced-choice trial contained the nonsense sentence filtered with F + ΔF. On priming trials, the interval 1 sentence was displayed on a computer screen prior to the auditory portion of the trial. The prime markedly affected bias, increasing the number of correct and incorrect interval 1 responses but did not affect overall discrimination performance substantially. These findings were supported through a second experiment that required listeners to make confidence judgments. The paradigm has the potential to help quantify the limits of speech perception when uncertainty about the auditory message is removed.
Wave separation in the trumpet under playing conditions and comparison with time domain finite difference simulation
Authors: Kemp Jonathan A. , Bilbao Stefan , McMaster James , Smith Richard A.
Published: August 2013

Wave separation within a trumpet is presented using three high pressure microphones to measure pressure waves within the curved, constant cross-section tuning slide of the instrument while the instrument was being played by a virtuoso trumpet player. A closer inter-microphone spacing was possible in comparison to previous work through the use of time domain windowing on non-causal transfer functions and performing wave separation in the frequency domain. Time domain plots of the experimental wave separation were then compared to simulations using a physical model based on a time domain finite difference simulation of the trumpet bore coupled to a one mass, two degree of freedom lip model. The time domain and frequency spectra of the measured and synthesized sounds showed a similar profile, with the sound produced by the player showing broader spectral peaks in experimental data. Using a quality factor of 5 for the lip model was found to give greater agreement between the simulated and experimental starting transients in comparison to the values in the range 1–3 often assumed. Deviations in the spectral content and wave shape provide insights into the areas where future research may be directed in improving the accuracy of physical modeling synthesis.
Across-frequency envelope correlation discrimination and masked signal detection
Authors: Grose John H. , Buss Emily , Porter Heather L. , Hall Joseph W.
Published: August 2013

This study compared the dependence of comodulation masking release (CMR) and monaural envelope correlation perception (MECP) on the degree of envelope correlation for the same narrowband noise stimuli. Envelope correlation across noise bands was systematically varied by mixing independent bands with a base set of comodulated bands. The magnitude of CMR fell monotonically with reductions in envelope correlation, and CMR varied over a range of envelope correlations that were not discriminable from each other in the MECP paradigm. For complexes of 100-Hz-wide noise bands, discrimination thresholds in the MECP task were similar whether the standard was a comodulated set of noise bands or a completely independent set of noise bands. This was not the case for 25-Hz-wide noise bands. Although the data demonstrate that CMR and MECP exhibit different dependencies on the degree of envelope correlation, some commonality across the two phenomena was observed. Specifically, for 25-Hz-wide bands of noise, there was a robust relationship between individual listeners' sensitivity to decorrelation from an otherwise comodulated set of noise bands and the magnitude of CMR measured for those same comodulated noise bands.
Continuum-based free vibration of circular trigonal and isotropic plates
Authors: Heyliger Paul R. , Johnson Ward
Published: August 2013

The free vibration behavior of completely unrestrained elastic circular plates with trigonal and isotropic material symmetry is studied with an approach involving approximate continuum solutions to the three-dimensional theory of linear elasticity. Of primary interest are (1) the influence of trigonal material symmetry on the modes of free vibration and (2) the accuracy of thin plate theory relative to the more exact three-dimensional theory. Resonant frequencies are calculated from the weak form of the equations of motion for the plate through the use of approximation functions and the Ritz method formulated in cylindrical coordinates. This approach enables the resulting eigenvalue problem to be split through group-theoretical symmetry analysis. Representative examples are given and quantitative limits are discussed.
Pitch- and spectral-based dynamic time warping methods for comparing field recordings of harmonic avian vocalizations
Authors: Daniel Meliza C , Keen Sara C. , Rubenstein Dustin R.
Published: August 2013

Quantitative measures of acoustic similarity can reveal patterns of shared vocal behavior in social species. Many methods for computing similarity have been developed, but their performance has not been extensively characterized in noisy environments and with vocalizations characterized by complex frequency modulations. This paper describes methods of bioacoustic comparison based on dynamic time warping (DTW) of the fundamental frequency or spectrogram. Fundamental frequency is estimated using a Bayesian particle filter adaptation of harmonic template matching. The methods were tested on field recordings of flight calls from superb starlings, Lamprotornis superbus, for how well they could separate distinct categories of call elements (motifs). The fundamental-frequency-based method performed best, but the spectrogram-based method was less sensitive to noise. Both DTW methods provided better separation of categories than spectrographic cross correlation, likely due to substantial variability in the duration of superb starling flight call motifs.
High frequency acoustic transmission loss of perforated plates at normal incidence
Authors: Phong Vincent , Papamoschou Dimitri
Published: August 2013

A study has been conducted on the transmission loss of perforated plates at normal incidence. The investigation includes a theoretical analysis of the problem with validation through experimentation. The experiments comprised microphone measurements of transmission loss for 11 perforated plates with variable thickness, hole size, and porosity. The theoretical model is based on planar wave propagation through a single contraction/expansion chamber with modifications to account for hole interaction effects. The resulting formula for transmission loss yields superior predictions over past theories for the range of properties investigated. Deviations between experimental measurements and theoretical predictions of transmission loss are less than about 1.5 dB for dimensionless hole diameter d/λ < 0.5. The accuracy of the model does not show a strong dependence on plate thickness-to-diameter ratio or porosity.
Using channel-specific statistical models to detect reverberation in cochlear implant stimuli
Authors: Desmond Jill M. , Collins Leslie M. , Throckmorton Chandra S.
Published: August 2013

Reverberation is especially detrimental for cochlear implant listeners; thus, mitigating its effects has the potential to provide significant improvements to cochlear implant communication. Efforts to model and correct for reverberation in acoustic listening scenarios can be quite complex, requiring estimation of the room transfer function and localization of the source and receiver. However, due to the limited resolution associated with cochlear implant stimulation, simpler processing for reverberation detection and mitigation may be possible for cochlear implants. This study models speech stimuli in a cochlear implant on a per-channel basis both in quiet and in reverberation, and assesses the efficacy of these models for detecting the presence of reverberation. This study was able to successfully detect reverberation in cochlear implant pulse trains, and the results appear to be robust to varying room conditions and cochlear implant stimulation parameters. Reverberant signals were detected 100% of the time for a long reverberation time of 1.2 s and 86% of the time for a shorter reverberation time of 0.5 s.
Perceiving sequential dependencies in auditory streams
Authors: Kidd Gerald , Mason Christine R. , Streeter Timothy , Thompson Eric R. , Best Virginia , Wakefield Gregory H.
Published: August 2013

This study examined the ability of human listeners to detect the presence and judge the strength of a statistical dependency among the elements comprising sequences of sounds. The statistical dependency was imposed by specifying transition matrices that determined the likelihood of occurrence of the sound elements. Markov chains were constructed from these transition matrices having states that were pure tones/noise bursts that varied along the stimulus dimensions of frequency and/or interaural time difference. Listeners reliably detected the presence of a statistical dependency in sequences of sounds varying along these stimulus dimensions. Furthermore, listeners were able to discriminate the relative strength of the dependency in pairs of successive sound sequences. Random variation along an irrelevant stimulus dimension had small but significant adverse effects on performance. A much greater decrement in performance was found when the sound sequences were concurrent. Likelihood ratios were computed based on the transition matrices to specify Ideal Observer performance for the experimental conditions. Preliminary modeling efforts were made based on degradations of Ideal Observer performance intended to represent human observer limitations. This experimental approach appears to be useful for examining auditory “stream” formation and maintenance over time based on the predictability of the constituent sound elements.
Formant frequency estimation of high-pitched vowels using weighted linear prediction
Authors: Alku Paavo , Pohjalainen Jouni , Vainio Martti , Laukkanen Anne-Maria , Story Brad H.
Published: August 2013

All-pole modeling is a widely used formant estimation method, but its performance is known to deteriorate for high-pitched voices. In order to address this problem, several all-pole modeling methods robust to fundamental frequency have been proposed. This study compares five such previously known methods and introduces a technique, Weighted Linear Prediction with Attenuated Main Excitation (WLP-AME). WLP-AME utilizes temporally weighted linear prediction (LP) in which the square of the prediction error is multiplied by a given parametric weighting function. The weighting downgrades the contribution of the main excitation of the vocal tract in optimizing the filter coefficients. Consequently, the resulting all-pole model is affected more by the characteristics of the vocal tract leading to less biased formant estimates. By using synthetic vowels created with a physical modeling approach, the results showed that WLP-AME yields improved formant frequencies for high-pitched sounds in comparison to the previously known methods (e.g., relative error in the first formant of the vowel [a] decreased from 11% to 3% when conventional LP was replaced with WLP-AME). Experiments conducted on natural vowels indicate that the formants detected by WLP-AME changed in a more regular manner between repetitions of different pitch than those computed by conventional LP.
Adaptation to spectrally-rotated speech
Authors: Green Tim , Rosen Stuart , Faulkner Andrew , Paterson Ruth
Published: August 2013

Much recent interest surrounds listeners' abilities to adapt to various transformations that distort speech. An extreme example is spectral rotation, in which the spectrum of low-pass filtered speech is inverted around a center frequency (2 kHz here). Spectral shape and its dynamics are completely altered, rendering speech virtually unintelligible initially. However, intonation, rhythm, and contrasts in periodicity and aperiodicity are largely unaffected. Four normal hearing adults underwent 6 h of training with spectrally-rotated speech using Continuous Discourse Tracking. They and an untrained control group completed pre- and post-training speech perception tests, for which talkers differed from the training talker. Significantly improved recognition of spectrally-rotated sentences was observed for trained, but not untrained, participants. However, there were no significant improvements in the identification of medial vowels in /bVd/ syllables or intervocalic consonants. Additional tests were performed with speech materials manipulated so as to isolate the contribution of various speech features. These showed that preserving intonational contrasts did not contribute to the comprehension of spectrally-rotated speech after training, and suggested that improvements involved adaptation to altered spectral shape and dynamics, rather than just learning to focus on speech features relatively unaffected by the transformation.
Piezoelectric circular ring flexural transducers
Authors: Aronov Boris S.
Published: August 2013

An analytical treatment of the piezoelectric ceramic complete ring transducer undergoing flexural vibrations is presented. Conditions for the electromechanical excitation of the flexural vibrations are discussed and it is shown that the fundamental mode of the flexural vibration of a complete ring can be considered as sufficiently dominant over a broad frequency range. Hence, the one-dimensional equivalent electromechanical circuit representation of the transducer is applicable and all the parameters of the equivalent circuit are determined. Possibilities to optimize the effective coupling coefficient of the transducer by changing the extent of the electrodes on the piezoelectric body are considered. It is shown that for effective operation of the flexural ring transducer as a low frequency hydroacoustic projector the opposing quadrants (or three quadrants in case of a planar array configuration) have to be covered with baffles. The radiation impedance and directional factors of the transducers with baffles are considered. Limitations of the acoustical power radiated by the transducers are discussed.
The role of vowel perceptual cues in compensatory responses to perturbations of speech auditory feedback
Authors: Reilly Kevin J. , Dougherty Kathleen E.
Published: August 2013

The perturbation of acoustic features in a speaker's auditory feedback elicits rapid compensatory responses that demonstrate the importance of auditory feedback for control of speech output. The current study investigated whether responses to a perturbation of speech auditory feedback vary depending on the importance of the perturbed feature to perception of the vowel being produced. Auditory feedback of speakers' first formant frequency (F1) was shifted upward by 130 mels in randomly selected trials during the speakers' production of consonant-vowel-consonant words containing either the vowel /Λ/ or the vowel /ɝ/. Although these vowels exhibit comparable F1 frequencies, the contribution of F1 to perception of /Λ/ is greater than its contribution to perception of /ɝ/. Compensation to the F1 perturbation was observed during production of both vowels, but compensatory responses during /Λ/ occurred at significantly shorter latencies and exhibited significantly larger magnitudes than compensatory responses during /ɝ/. The finding that perturbation of vowel F1 during /Λ/ and /ɝ/ yielded compensatory differences that mirrored the contributions of F1 to perception of these vowels indicates that some portion of feedback control is weighted toward monitoring and preservation of acoustic cues for speech perception.
Vocabulary influences older and younger listeners' processing of dysarthric speech
Authors: McAuliffe Megan J. , Gibson Elizabeth M. R. , Kerr Sarah E. , Anderson Tim , LaShell Patrick J.
Published: August 2013

This study examined younger (n = 16) and older (n = 16) listeners' processing of dysarthric speech—a naturally occurring form of signal degradation. It aimed to determine how age, hearing acuity, memory, and vocabulary knowledge interacted in speech recognition and lexical segmentation. Listener transcripts were coded for accuracy and pattern of lexical boundary errors. For younger listeners, transcription accuracy was predicted by receptive vocabulary. For older listeners, this same effect existed but was moderated by pure-tone hearing thresholds. While both groups employed syllabic stress cues to inform lexical segmentation, older listeners were less reliant on this perceptual strategy. The results were interpreted to suggest that individuals with larger receptive vocabularies, with their presumed greater language familiarity, were better able to leverage cue redundancies within the speech signal to form lexical hypothesis—leading to an improved ability to comprehend dysarthric speech. This advantage was minimized as hearing thresholds increased. While the differing levels of reliance on stress cues across the listener groups could not be attributed to specific individual differences, it was hypothesized that some combination of larger vocabularies and reduced hearing thresholds in the older participant group led to them prioritize lexical cues as a segmentation frame.
Spatio-temporal articulatory movement primitives during speech production: Extraction, interpretation, and validation
Authors: Ramanarayanan Vikram , Goldstein Louis , Narayanan Shrikanth S.
Published: August 2013

This paper presents a computational approach to derive interpretable movement primitives from speech articulation data. It puts forth a convolutive Nonnegative Matrix Factorization algorithm with sparseness constraints (cNMFsc) to decompose a given data matrix into a set of spatiotemporal basis sequences and an activation matrix. The algorithm optimizes a cost function that trades off the mismatch between the proposed model and the input data against the number of primitives that are active at any given instant. The method is applied to both measured articulatory data obtained through electromagnetic articulography as well as synthetic data generated using an articulatory synthesizer. The paper then describes how to evaluate the algorithm performance quantitatively and further performs a qualitative assessment of the algorithm's ability to recover compositional structure from data. This is done using pseudo ground-truth primitives generated by the articulatory synthesizer based on an Articulatory Phonology frame-work [Browman and Goldstein (1995). “Dynamics and articulatory phonology,” in Mind as motion: Explorations in the dynamics of cognition, edited by R. F. Port and T.van Gelder (MIT Press, Cambridge, MA), pp. 175–194]. The results suggest that the proposed algorithm extracts movement primitives from human speech production data that are linguistically interpretable. Such a framework might aid the understanding of longstanding issues in speech production such as motor control and coarticulation.
Simultaneous masking additivity for short Gaussian-shaped tones: Spectral effects
Authors: Laback Bernhard , Necciari Thibaud , Balazs Peter , Savel Sophie , Ystad Sølvi
Published: August 2013

Laback et al. [(2011). J. Acoust. Soc. Am. 129, 888−897] investigated the additivity of nonsimultaneous masking using short Gaussian-shaped tones as maskers and target. The present study involved Gaussian stimuli to measure the additivity of simultaneous masking for combinations of up to four spectrally separated maskers. According to most basilar membrane measurements, the maskers should be processed linearly at the characteristic frequency (CF) of the target. Assuming also compression of the target, all masker combinations should produce excess masking (exceeding linear additivity). The results for a pair of maskers flanking the target indeed showed excess masking. The amount of excess masking could be predicted by a model assuming summation of masker-evoked excitations in intensity units at the target CF and compression of the target, using compressive input/output functions derived from the nonsimultaneous masking study. However, the combinations of lower-frequency maskers showed much less excess masking than predicted by the model. This cannot easily be attributed to factors like off-frequency listening, combination tone perception, or between-masker suppression. It was better predicted, however, by assuming weighted intensity summation of masker excitations. The optimum weights for the lower-frequency maskers were smaller than one, consistent with partial masker compression as indicated by recent psychoacoustic data.
The coarticulation/invariance scale: Mutual information as a measure of coarticulation resistance, motor synergy, and articulatory invariance
Authors: Iskarous Khalil , Mooshammer Christine , Hoole Phil , Recasens Daniel , Shadle Christine H. , Saltzman Elliot , Whalen D. H.
Published: August 2013

Coarticulation and invariance are two topics at the center of theorizing about speech production and speech perception. In this paper, a quantitative scale is proposed that places coarticulation and invariance at the two ends of the scale. This scale is based on physical information flow in the articulatory signal, and uses Information Theory, especially the concept of mutual information, to quantify these central concepts of speech research. Mutual Information measures the amount of physical information shared across phonological units. In the proposed quantitative scale, coarticulation corresponds to greater and invariance to lesser information sharing. The measurement scale is tested by data from three languages: German, Catalan, and English. The relation between the proposed scale and several existing theories of coarticulation is discussed, and implications for existing theories of speech production and perception are presented.
An inter-comparison of sediment classification methods based on multi-beam echo-sounder backscatter and sediment natural radioactivity data
Authors: Snellen Mirjam , Eleftherakis Dimitrios , Amiri-Simkooei AliReza , Koomans Ronald L. , Simons Dick G.
Published: August 2013

This contribution presents sediment classification results derived from different sources of data collected at the Dordtse Kil river, the Netherlands. The first source is a multi-beam echo-sounder (MBES). The second source is measurements taken with a gamma-ray scintillation detector, i.e., the Multi-Element Detection System for Underwater Sediment Activity (Medusa), towed over the sediments and measuring sediment natural radioactivity. Two analysis methods are employed for sediment classification based on the MBES data. The first is a Bayesian estimation method that uses the average backscatter data per beam and, therefore, is independent of the quality of the MBES calibration. The second is a model-based method that matches the measured backscatter curves to theoretical curves, predicted by a physics-based model. Medusa provides estimates for the concentrations of potassium, uranium, thorium, and cesium, known to be indicative for sediment properties, viz. mean grain size, silt content, and the presence of organic matter. In addition, a hydrophone attached to the Medusa system provides information regarding the sediment roughness. This paper presents an inter-comparison between the sediment classification results using the above-mentioned methods. It is shown that although originating from completely different sources, the MBES and Medusa provide similar information, revealing the same sediment distribution.
Surfactant shedding and gas diffusion during pulsed ultrasound through a microbubble contrast agent suspension
Authors: O'Brien Jean-Pierre , Stride Eleanor , Ovenden Nicholas
Published: August 2013

Interest in coated microbubbles as agents for therapeutic and quantitative imaging applications in biomedical ultrasound has increased the need for their accurate theoretical characterization. Effects such as gas diffusion, variation in the properties of the coating and the resulting changes in bubble behavior under repeated exposure to ultrasound pulses are, however, still not well understood. In this study, a revised equation for microbubble motion is proposed that includes the effects of gas diffusion, as well as adsorption, desorption and shedding of a surfactant from the bubble surface. This is incorporated into a nonlinear wave propagation model to account for these additional time dependent effects in the response of microbubble populations. The results from the model indicate there can be significant changes in both bubble behavior and the propagated pulse over time. This is in agreement with existing experimental data but is not predicted by existing propagation models. The analysis indicates that changes in bubble dynamics are dominated by surfactant shedding on the timescale of a diagnostic ultrasound pulse and gas diffusion over the timescale of the pulse repetition frequency. The implications of these results for the development of more accurate algorithms for quantitative imaging and for therapeutic applications are discussed.
The impact of practice on the adjustment of interaural cues in a lateralization task
Authors: Ignaz Alina , Lang Albert-Georg , Buchner Axel
Published: August 2013

Lang and Buchner [J. Acoust. Soc. Am. 124, 3120–3131 (2008)] conducted trading experiments showing that the phenomenon of different trading ratios depending on which cue is adjusted by the listener is independent of the presentation of an explicit reference tone. Four experiments were conducted to test whether implicit reference tones during the preceding practice phase may have caused the different trading ratios. The results of Lang and Buchner were replicated, showing that an implicit reference learned during the practice phase cannot account for different trading ratios in experiments without the presentation of a reference tone.
Nonlinear focal shift beyond the geometrical focus in moderately focused acoustic beams
Authors: Camarena Francisco , Adrián-Martínez Silvia , Jiménez Noé , Sánchez-Morcillo Víctor
Published: August 2013

The phenomenon of the displacement of the position along the axis of the pressure, intensity, and radiation force maxima of focused acoustic beams under increasing driving voltages (nonlinear focal shift) is studied for the case of a moderately focused beam. The theoretical and experimental results show the existence of this shift along the axis when the initial pressure in the transducer increases until the acoustic field reaches the fully developed nonlinear regime of propagation. Experimental data show that at high amplitudes and for moderate focusing, the position of the on-axis pressure maximum and radiation force maximum can surpass the geometrical focal length. On the contrary, the on-axis pressure minimum approaches the transducer under increasing driving voltages, increasing the distance between the positive and negative peak pressure in the beam. These results are in agreement with numerical KZK model predictions and the existed data of other authors and can be explained according to the effect of self-refraction characteristic of the nonlinear regime of propagation.
Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels
Authors: Khokhlova Vera A. , Shmeleva Svetlana M. , Gavrilov Leonid R. , Martin Eleanor , Sadhoo Neelaksh , Shaw Adam
Published: August 2013

Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm2 to at least 50 W/cm2. Significantly higher intensities could be measured simply by reducing the duty cycle.
Microbubble behavior in an ultrasound field for high intensity focused ultrasound therapy enhancement
Authors: Okita Kohei , Sugiyama Kazuyasu , Takagi Shu , Matsumto Yoichiro
Published: August 2013

The enhancement of heating due to inertial cavitation has been focused to reduce the long treatment time of conventional high-intensity focused ultrasound (HIFU) therapy. The influences of the physical properties of surrounding tissues, initial void fraction, and spatial distribution of bubbles on microbubble-enhanced HIFU are examined. A bubble dynamics equation based on the Keller-Miksis equation is employed in consideration of the elasticity of surrounding tissue. The mixture phase and bubbles are coupled by the Euler-Lagrange method to take into account the interaction between ultrasound and bubbles. As a result, the temperature around the target increases with the initial void fraction. But at the high void fraction of 10−5, ultrasound is too attenuated to heat the target, and the heating region moves to the transducer side. On the other hand, both the viscosity and shear elasticity of the surrounding media reduce the attenuation of ultrasound propagation through the bubbly mixture. Numerical results show that localized heating is induced with increasing viscosity or shear elasticity, though it depends on the pressure amplitudes. In addition, it was numerically confirmed that the localization of the microbubble distribution is important to obtain efficient localized heating.
Cavitation microstreaming generated by a bubble pair in an ultrasound field
Authors: Wang Chenghui , Cheng Jianchun
Published: August 2013

An analytical theory has been developed to calculate the acoustic streaming velocity inside and outside bubbles for the case of a bubble pair suspended in an unbounded viscous liquid, taking into account the two predominant modes of a bubble pair: The volume and translation modes. It was demonstrated that the interaction between bubbles can affect the magnitude and direction of acoustic streaming, especially for tangential components outside of bubbles. The acoustic streaming intensifies as the radius of the neighboring bubble increases and is weakened as the distance between the bubbles increases.
Split-mode ultrasonic transducer
Authors: Ostrovskii Igor , Cremaldi Lucien
Published: August 2013

A split-mode ultrasonic transducer is investigated in both theory and experiment. This transducer is a two-dimensional structure of periodically poled domains in a ferroelectric wafer with free surfaces. The acoustic vibrations are excited by a radio frequency electric current applied along the length of the wafer, which allows the basal-plane surfaces to be free of metal coatings and thus ready for further biomedical applications. A specific physical property of this transducer consists of the multiple acousto-electric resonances, which occur due to an acoustic mode split when the acoustic half-wavelength is equal to the domain length. Possible applications include ultrasonic generation and detection at the micro-scale, intravascular sonification and visualization, ultrasound therapy of localized small areas such as the eye, biomedical applications for cell cultures, and traditional nondestructive testing including bones and tissues. A potential use of a non-metallized wafer is a therapeutic application with double action that is both ultrasound itself and an electric field over the wafer. The experimental measurements and theoretical calculations are in good agreement.
Non-paraxial model for a parametric acoustic array
Authors: Cervenka Milan , Bednarik Michal
Published: August 2013

This study is concerned with parametric radiation from an arbitrary axisymmetric planar source with a special focus on low-frequency difference-frequency fields. As a model equation accounting for nonlinearity, diffraction, and dissipation, the Westervelt equation is used. The difference-frequency-field patterns are calculated in the quasi-linear approximation by the method of successive approximations. A multi-layer integral for calculation of the acoustic field is reduced to a three-dimensional one by employing an approximate analytical description of the primary field with the use of a multi-Gaussian beam expansion. This integral is subsequently reduced in the paraxial approximation to a one-dimensional form which has previously been published in literature and which represents a means for fast calculations of secondary acoustic fields. The three-dimensional integral is calculated numerically and the numerical results predict nonzero amplitude of the low-frequency field in the vicinity of the source which is an effect that cannot be correctly encompassed in the paraxial approximation.
The influence of glottal cross-section shape on theoretical flow models
Authors: Wu Bo , Van Hirtum Annemie , Pelorson Xavier , Luo Xiaoyu
Published: August 2013

Physical and mathematical phonation models commonly rely on a quasi-one-dimensional flow model. The assumption of quasi-one-dimensional flow through a glottis with fixed length is analyzed for different cross-section shapes: Circle, rectangle, ellipse, and circular segment. A simplified flow model is formulated which accounts for kinetic losses, viscosity, and cross-section shape. It is seen that the cross-section shape cannot be neglected since it alters boundary layer development and hence the viscous contribution to the pressure drop across the glottis. The commonly applied quasi-one-dimensional flow model is shown to be inaccurate, indicating the potential benefit of taking into account the cross-section shape.
A Long Noncoding RNA Mediates Both Activation and Repression of Immune Response Genes
Authors: Carpenter Susan , Aiello Daniel , Atianand Maninjay K. , Ricci Emiliano P. , Gandhi Pallavi , Hall Lisa L. , Byron Meg , Monks Brian , Henry-Bezy Meabh , Lawrence Jeanne B. , O’Neill Luke A. J. , Moore Melissa J. , Caffrey Daniel R. , Fitzgerald Katherine A.
Published: August 2013

A New Linc in Innate Immunity

Long noncoding RNAs (lncRNAs) have recently emerged as important regulators of gene expression in a wide variety of biological processes, although specific roles for these molecules in the immune system have not been described.

Carpenter
et al.

(p.
789
, published online 1 August) now define the function of one such lncRNA in the immune system, lincRNA-Cox2. Whole-transcriptome profiling revealed that lincRNA-Cox2 was induced in mouse macrophages in response to activation of Toll-like receptors—molecules that detect microbes and alert the immune system to respond. LincRNA-Cox2 both positively and negatively regulated the expression of distinct groups of inflammatory genes. Negative regulation of gene expression was mediated by lincRNA-Cox interaction with heterogeneous nuclear ribonucleoprotein A/B and A2/B1.
Marine Studies Show Potential for U.S.-Cuban Collaboration
Authors: Friedman-Rudovsky Jean
Published: August 2013

The U.S. embargo continues to get in the way of joint research on the parallel ecosystems of Cuba and South Florida.
Out of the Kenyan Mud, an Ancient Climate Record
Authors: Pennisi Elizabeth
Published: August 2013

Scientists gather for a first look at a fresh sediment core, hoping that it will offer hard data linking environmental change to human evolution.
Worth a Thousand Words
Authors: Pennisi Elizabeth
Published: August 2013

Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.
Genome Sequences of Amycolatopsis orientalis subsp.
orientalis
Strains DSM 43388 and DSM 46075
Authors: Jeong Haeyoung , Sim Young Mi , Kim Hyun Ju , Lee Yong-Jik , Lee Dong-Woo , Lim Si-Kyu , Lee Sang Jun
Published: August 2013

Strains of
Amycolatopsis orientalis
produce vancomycin or other related glycopeptide antibiotic compounds. Here we report the draft genome sequences of glycopeptide nonproducers
Amycolatopsis orientalis
subsp.
orientalis
DSM 43388 and DSM 46075. Their genome information will provide insights into the acquisition and regulation of glycopeptide antibiotic resistance genes.
Draft Genome Sequence of the Brazilian Toxic Bloom-Forming Cyanobacterium Microcystis aeruginosa Strain SPC777
Authors: Fiore Marli F. , Alvarenga Danillo O. , Varani Alessandro M. , Hoff-Risseti Caroline , Crespim Elaine , Ramos Rommel T. J. , Silva Artur , Schaker Patricia D. C. , Heck Karina , Rigonato Janaina , Schneider Maria Paula C.
Published: August 2013

Microcystis aeruginosa
strain SPC777 is an important toxin-producing cyanobacterium, isolated from a water bloom of the Billings reservoir (São Paulo State, Brazil). Here, we report the draft genome sequence and initial findings from a preliminary analysis of strain SPC777, including several gene clusters involved in nonribosomal and ribosomal synthesis of secondary metabolites.
Genome Sequence of Clostridium butyricum Strain DSM 10702, a Promising Producer of Biofuels and Biochemicals
Authors: Xin Bo , Tao Fei , Wang Yu , Gao Chao , Ma Cuiqing , Xu Ping
Published: August 2013

Clostridium butyricum
strains have been considered promising producers of biofuels and biochemicals, such as hydrogen, butanol, butyric acid, and 1,3-propanediol. Here, we present a 4.59-Mb assembly of the genome sequence of DSM 10702 (VPI 3266), a type strain of
C. butyricum
.
Genome Sequence of the Polyphosphate-Accumulating Organism
Arthrobacter
sp. Strain PAO19 Isolated from Maize Rhizosphere Soil
Authors: Li Xiaolong , Yuan Hongli , Yang Jinshui , Li Baozhen
Published: August 2013

Arthrobacter
sp. strain PAO19 is a polyphosphate-accumulating organism isolated from maize rhizosphere soil. Here we report its genome sequence, which may shed light on its role in phosphate removal from water bodies. To our knowledge, this is the first genome announcement of a polyphosphate-accumulating strain of the genus
Arthrobacter
.