bluuebunny/crossref_metadata_2025 huggingface dataset:
Muller condition and fairness on multitransition systems
Authors: Mihoubi Douadi
Published: May 2011

This paper presents an extension of a result by Guessarian and Niar to the framework of multitransition systems. In the case of a single process, Guessarian and Niar had shown that the set of fair computations of regular SCCS processes coincides with the class of ε-freeω-regular languages. Here, in the case of multitransition systems, we show essentially that the sets of fair computations on multitransition systems are strictly included in the class of ε-freeω-regularN-languages. The inclusions of these fair sets into the class of ε-freeω-regularN-languages are obtained by showing that the strict (respectively weak, strong) fair condition can be simulated by the Muller acceptance condition on multitransition systems. The strictness of the inclusions is obtained by exhibiting two counter-examples showing that the reverse is false, that is, not everyω-regularN-language is the set of fair computations of some multitransition system.
Neurometabolic coupling differs for suppression within and beyond the classical receptive field in visual cortex
Authors: Li Baowang , Freeman Ralph D.
Published: May 2011

Non‐technical summary  In visual cortex, underlying neural circuits process images by decoding responses of cells to specific stimuli. The transducer for this process is the receptive field, i.e. the territory which enables a single neuron to be highly selective for visual stimuli. Suppression effects within and outside the receptive field serve to shape the selectivity by modulation of neural firing. We show here that oxygen metabolism decreases or increases, respectively, for suppression within or outside the receptive field. The difference in activity‐induced oxygen demand between the two types of suppression helps clarify the function of associated neural circuits.
TRPA1 contributes to specific mechanically activated currents and sensory neuron mechanical hypersensitivity
Authors: Brierley Stuart M. , Castro Joel , Harrington Andrea M. , Hughes Patrick A. , Page Amanda J. , Rychkov Grigori Y. , Blackshaw L. Ashley
Published: May 2011

Non‐technical summary  Detecting mechanical stimuli is vital to determining our responses to environmental challenges. The speed required for this process suggests ion channels are opened in response to mechanical forces. A specialised membrane protein called the TRPA1 ion channel mediates chemical based pain; however its role in mechanical pain remains unresolved. Here we show that TRPA1 contributes to the detection of mechanical stimuli in a select set of pain sensing neurons. Furthermore, we also show that acute activation of this channel enhances the mechanical responsiveness of these neurons. Finally, we also show that increasing the expression of TRPA1 causes a further enhancement in the mechanical response. These findings suggest that a drug designed to block TRPA1 would be beneficial for the treatment of numerous pathological conditions associated with mechanical pain.
Rapid serial prototyping of magnet-tipped attonewton-sensitivity cantilevers by focused ion beam manipulation
Authors: Longenecker Jonilyn G. , Moore Eric W. , Marohn John A.
Published: May 2011

The authors report a method for rapidly prototyping attonewton-sensitivity cantilevers with custom-fabricated tips and illustrate the method by preparing tips consisting of a magnetic nanorod overhanging the leading edge of the cantilevers. Micron-long nickel nanorods with widths of 120–220 nm were fabricated on silicon chips by electron beam lithography, deposition, and lift-off. Each silicon chip, with its integral nanomagnet, was attached serially to a custom-fabricated attonewton-sensitivity cantilever using focused ion beam manipulation. The magnetic nanorod tips were prepared with and without an alumina capping layer, and the minimum detectable force and tip magnetic moment of the resulting cantilevers was characterized by cantilever magnetometry. The results indicate that this serial but high-yield approach is an effective way to rapidly prepare and characterize magnetic tips for the proposed single-electron-spin and single-proton magnetic resonance imaging experiments. The approach also represents a versatile route for affixing essentially any vacuum-compatible sample to the leading edge of an attonewton-sensitivity cantilever.
Energy velocity and quality factor of poroelastic waves in isotropic media
Authors: Gerasik Vladimir , Stastna Marek
Published: May 2011

The energy velocity and Q factor of poroelastic acoustic waves in the context of classical isotropic Biot’s theory are revisited. Special attention is paid to the high frequency regime when interphase interaction is viscoelastic. The analogy with viscoelastic behavior is emphasized in derivation of the energy balance equations which relate kinetic energy, potential energy, viscous power dissipation, and elastic energy stored associated with each wave. These lead to exact closed form expressions for the energy velocity and Q factor for both longitudinal and shear waves from energy principles. Most notably, the analysis of the resulting expressions reveals that the energy velocity of both longitudinal and shear waves equals (exceeds) the corresponding phase velocity in the case of the low (full) frequency range theory, and that the exact expression for the Q factor contains an additive correction due to viscoelastic interphase interaction.
A characterization of the scattered acoustic intensity field in the resonance region for simple spheres
Authors: Barton Robert J. , Smith Kevin B. , Vincent Harold T.
Published: May 2011

The properties of the scattered acoustic vector fields generated by simple spheres illuminated by monotonic continuous wave (CW) plane waves are investigated. Analytical solutions are derived from general acoustic pressure scattering models and analyzed for wave numbers in the resonance region. Of particular interest is the understanding of the characteristics of the scattered acoustic vector field in the near-to-far-field transition region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented for the near and transition regions for a rigid sphere. A method of mapping nulls in the scattered intensity field components is described. The analysis is then extended to include a simple fluid-filled boundary and finally the evacuated thin-walled shell. Near field acoustic intensity field structures are compared against mechanical material properties of vacuous shells. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic vector sensor probes to measure the scattered acoustic vector field from rigid spheres.
Rhythm measures and dimensions of durational variation in speech
Authors: Loukina Anastassia , Kochanski Greg , Rosner Burton , Keane Elinor , Shih Chilin
Published: May 2011

Patterns of durational variation were examined by applying 15 previously published rhythm measures to a large corpus of speech from five languages. In order to achieve consistent segmentation across all languages, an automatic speech recognition system was developed to divide the waveforms into consonantal and vocalic regions. The resulting duration measurements rest strictly on acoustic criteria. Machine classification showed that rhythm measures could separate languages at rates above chance. Within-language variability in rhythm measures, however, was large and comparable to that between languages. Therefore, different languages could not be identified reliably from single paragraphs. In experiments separating pairs of languages, a rhythm measure that was relatively successful at separating one pair often performed very poorly on another pair: there was no broadly successful rhythm measure. Separation of all five languages at once required a combination of three rhythm measures. Many triplets were about equally effective, but the confusion patterns between languages varied with the choice of rhythm measures.
Characterizing distortion-product otoacoustic emission components across four species
Authors: Martin Glen K. , Stagner Barden B. , Chung You Sun , Lonsbury-Martin Brenda L.
Published: May 2011

Distortion-product otoacoustic emissions (DPOAEs) were measured as level/phase (L/P) maps in humans, rabbits, chinchillas, and rats with and without an interference tone (IT) placed either near the 2f1−f2 DPOAE frequency place (fdp) or at one-third of an octave above the f2 primary tone (1/3-oct IT). Vector differences between with and without IT conditions were computed to derive a residual composed of the DPOAE components removed by the IT. In humans, a DPOAE component could be extracted with the expected steep phase gradient indicative of reflection emissions by ITs near fdp. In the laboratory species, ITs near fdp failed to produce any conclusive evidence for reflection components. For all species, 1/3-oct ITs extracted large DPOAE components presumably generated at or basal to the IT-frequency place that exhibited both distortion- and reflection-like phase properties. Together, these findings suggested that basal distortion components could assume reflection-like phase behavior when the assumptions of cochlear-scaling symmetry, the basis for shallow phase gradients for constant f2/f1 ratio sweeps, are violated. The present results contradict the common belief that DPOAE components associated with steep or shallow phase slopes are unique signatures for reflection emissions arising from fdp or distortion emissions generated near f2, respectively.
Effects of consonant manner and vowel height on intraoral pressure and articulatory contact at voicing offset and onset for voiceless obstruents
Authors: Koenig Laura L. , Fuchs Susanne , Lucero Jorge C.
Published: May 2011

In obstruent consonants, a major constriction in the upper vocal tract yields an increase in intraoral pressure (Pio). Phonation requires that subglottal pressure (Psub) exceed Pio by a threshold value, so as the transglottal pressure reaches the threshold, phonation will cease. This work investigates how Pio levels at phonation offset and onset vary before and after different German voiceless obstruents (stop, fricative, affricates, clusters), and with following high vs low vowels. Articulatory contacts, measured using electropalatography, were recorded simultaneously with Pio to clarify how supraglottal constrictions affect Pio. Effects of consonant type on phonation thresholds could be explained mainly in terms of the magnitude and timing of vocal-fold abduction. Phonation offset occurred at lower values of Pio before fricative-initial sequences than stop-initial sequences, and onset occurred at higher levels of Pio following the unaspirated stops of clusters compared to fricatives, affricates, and aspirated stops. The vowel effects were somewhat surprising: High vowels had an inhibitory effect at voicing offset (phonation ceasing at lower values of Pio) in short-duration consonant sequences, but a facilitating effect on phonation onset that was consistent across consonantal contexts. The vowel influences appear to reflect a combination of vocal-fold characteristics and vocal-tract impedance.
Relation between annoyance and single-number quantities for rating heavy-weight floor impact sound insulation in wooden houses
Authors: Ryu Jongkwan , Sato Hiroshi , Kurakata Kenji , Hiramitsu Atsuo , Tanaka Manabu , Hirota Tomohito
Published: May 2011

This study investigated the relation between annoyance and single-number quantities to rate heavy-weight floor impact sound insulation. Laboratory experiments were conducted to evaluate the subjective response of annoyance resulting from heavy-weight floor impact sounds recorded in wooden houses. Stimuli had two typical spectra and their modified versions, which simulate the precise change in frequency response resulting from insulation treatments. Results of the first experiment showed that the Zwicker’s percentile loudness (N5) was the quantity to rate most well annoyance of heavy-weight impact sound over a wide sound level range. The second experiment revealed that arithmetic average (LiFavg,Fmax) of octave-band sound pressure levels measured using the time constant “fast” and Zwicker’s percentile loudness (N5) much better described annoyance by the precise change in the sound spectrum attributable to insulation treatments than Japanese standardized single-number quantities (Li,Fmax,r, LiA,Fmax, and Li,Fmax,Aw) do. Japanese standardized single-number quantities using the A-weighting curve as a rating curve were found to be excessively influenced by the 63 Hz octave-band sound level and have the great sound level-dependences in the relation with subjective ratings.
Signal-to-noise ratio for source determination and for a comodulated masker in goldfish, Carassius auratus
Authors: Fay Richard R.
Published: May 2011

The masking effects of white and amplitude comodulated noise were studied with respect to simple signal detection and sound source determination in goldfish. A stimulus generalization method was used to determine the signal-to-noise ratio required to completely determine the signal’s characteristics. It was found that the S/N required for this determination is about 4 dB greater than that required for signal detection, or was about 4 dB greater than the critical masking ratio. This means that the potential harm to fish of a given masking noise is at least 4 dB greater than previously thought, based on critical masking ratios. However, for amplitude comodulated noise between 10 and 50 Hz modulation rate, the potential harmful effects are up to 5.3 dB less than would be predicted from the critical masking ratio for unmodulated noise.
Measurements of ultrasonic phase velocities and attenuation of slow waves in cellular aluminum foams as cancellous bone-mimicking phantoms
Authors: Zhang Chan , Le Lawrence H. , Zheng Rui , Ta Dean , Lou Edmond
Published: May 2011

The water-saturated aluminum foams with an open network of interconnected ligaments were investigated by ultrasonic transmission technique for the suitability as cancellous bone-mimicking phantoms. The phase velocities and attenuation of nine samples covering three pores per inch (5, 10, and 20 PPI) and three aluminum volume fractions (5, 8, and 12% AVF) were measured over a frequency range of 0.7–1.3 MHz. The ligament thickness and pore sizes of the phantoms and low-density human cancellous bones are similar. A strong slow wave and a weak fast wave are observed for all samples while the latter is not visible without significant amplification (100×). This study reports the characteristics of slow wave, whose speeds are less than the sound speed of the saturating water and decrease mildly with AVF and PPI with an average 1469 m/s. Seven out of nine samples show positive dispersion and the rest show minor negative dispersion. Attenuation increases with AVF, PPI, and frequency except for the 20 PPI samples, which exhibit non-increasing attenuation level with fluctuations due to scattering. The phase velocities agree with Biot’s porous medium theory. The RMSE is 16.0 m/s (1%) at n = 1.5. Below and above this value, the RMSE decreases mildly and rises sharply, respectively.
Fine-grained variation in caregivers’ /s/ predicts their infants’ /s/ category
Authors: Cristià Alejandrina
Published: May 2011

Within the debate on the mechanisms underlying infants’ perceptual acquisition, one hypothesis proposes that infants’ perception is directly affected by the acoustic implementation of sound categories in the speech they hear. In consonance with this view, the present study shows that individual variation in fine-grained, subphonemic aspects of the acoustic realization of /s/ in caregivers’ speech predicts infants’ discrimination of this sound from the highly similar /∫/, suggesting that learning based on acoustic cue distributions may indeed drive natural phonological acquisition.
Vortex sound in the presence of a low Mach number flow across a drum-like silencer
Authors: Tang S. K.
Published: May 2011

The sound generated by a vortex propagating across a two-dimensional duct section with flexible walls (membranes) in an infinitely long rigid duct conveying a flow is investigated numerically using the matched asymptotic expansion technique and the potential theory. The effects of the initial vortex position, the mechanical properties of the flexible walls, and the mean flow on the sound generation are examined in detail. Results show that the presence of a vortex inside a uniform mean flow can strengthen or attenuate the sound generation, depending on the phase of the membrane vibration when the vortex starts vigorous interaction with the membranes and the strength of the mean flow. The results tend to imply that there is a higher chance of sound amplification when a vortex stream is moving closer to the lighter membrane under a relatively strong mean flow or when the mean flow is weak. The chances of sound amplification or attenuation are equal otherwise.
Experimental investigation on self-excited resonances of a cylindrical tube in cross-flow
Authors: Duro Vincent , Décultot Dominique , Léon Fernand , Maze Gérard
Published: May 2011

This paper is devoted to the study of acoustic vibrations induced by a flow upon an air-filled cylindrical tube vertically placed in water. A water pump with adapted piping generates a turbulent flow horizontally canalized in a large laboratory tank (6 m × 4 m × 3 m). The tube is located across this flow and an accelerometer measures vibrations. The signal processing performed on the recorded signals brings out resonance modes of the tube excited by the flow. A theoretical study (tube in air) and complementary experiments (tube in air and in water) are conducted to identify these modes.
Multiband analysis and synthesis of spectro-temporal modulations of Fourier spectrogram
Authors: Chi Tai-Shih , Hsu Chung-Chien
Published: May 2011

The two-dimensional spectro-temporal modulation filtering concept of the auditory model [T. Chi, P. Ru, and S. A. Shamma, J. Acoust. Soc. Am. 118(2), 887–906 (2005)] is implemented on the Fourier spectrogram. The Fourier magnitude spectrogram is analyzed in terms of its joint spectro-temporal modulations, which embed the temporal dynamics and spectral structures. Instead of iterative projection methods, the overlap-and-add method is adopted to invert modified Fourier spectrograms back to sounds. The proposed framework not only provides a similar spectro-temporal analytical process for sounds as the auditory model but also produces synthesized sounds with better quality in a timely manner, which makes proposed framework feasible to human speech recognition (HSR) applications as well.
Fly-ear inspired micro-sensor for sound source localization in two dimensions
Authors: Lisiewski A. P. , Liu H. J. , Yu M. , Currano L. , Gee D.
Published: May 2011

Inspired by the hearing organ of the fly Ormia ochracea, a miniature sound localization sensor is developed, which can be used to pinpoint a sound source in two dimensions described by the azimuth and elevation angles. The sensor device employs an equilateral triangle configuration consisting of three mechanically coupled circular membranes whose oscillations are detected by a fiber-optic system. The experimental results indicate that significant amplification of the directional cues and directional sensitivity can be achieved with the fly-ear inspired sensor design. This work can provide a basis for the development of miniature sound localization sensors in two dimensions.
Microbubble cloud characterization by nonlinear frequency mixing
Authors: Cavaro M. , Payan C. , Moysan J. , Baqué F.
Published: May 2011

In the frame of the fourth generation forum, France decided to develop sodium fast nuclear reactors. French Safety Authority requests the associated monitoring of argon gas into sodium. This implies to estimate the void fraction, and a histogram indicating the bubble population. In this context, the present letter studies the possibility of achieving an accurate determination of the histogram with acoustic methods. A nonlinear, two-frequency mixing technique has been implemented, and a specific optical device has been developed in order to validate the experimental results. The acoustically reconstructed histograms are in excellent agreement with those obtained using optical methods.
Distortion products and backward-traveling waves in nonlinear active models of the cochlea
Authors: Sisto Renata , Moleti Arturo , Botti Teresa , Bertaccini Daniele , Shera Christopher A.
Published: May 2011

This study explores the phenomenology of distortion products in nonlinear cochlear models, predicting their amplitude and phase along the basilar membrane. The existence of a backward-traveling wave at the distortion-product frequency, which has been recently questioned by experiments measuring the phase of basilar-membrane vibration, is discussed. The effect of different modeling choices is analyzed, including feed-forward asymmetry, micromechanical roughness, and breaking of scaling symmetry. The experimentally observed negative slope of basilar-membrane phase is predicted by numerical simulations of nonlinear cochlear models under a wide range of parameters and modeling choices. In active models, positive phase slopes are predicted by the quasi-linear analytical computations and by the fully nonlinear numerical simulations only if the distortion-product sources are localized apical to the observation point and if the stapes reflectivity is unrealistically small. The results of this study predict a negative phase slope whenever the source is distributed over a reasonably wide cochlear region and/or a reasonably high stapes reflectivity is assumed. Therefore, the above-mentioned experiments do not contradict “classical” models of cochlear mechanics and of distortion-product generation.
Electroacoustic absorbers: Bridging the gap between shunt loudspeakers and active sound absorption
Authors: Lissek Hervé , Boulandet Romain , Fleury Romain
Published: May 2011

The acoustic impedance at the diaphragm of an electroacoustic transducer can be varied using a range of basic electrical control strategies, amongst which are electrical shunt circuits. These passive shunt techniques are compared to active acoustic feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. The formulation of feedback-based acoustic impedance control reveals formal analogies with shunt strategies, and highlights an original method for synthesizing electric networks (“shunts”) with positive or negative components, bridging the gap between passive and active acoustic impedance control. This paper describes the theory unifying all these passive and active acoustic impedance control strategies, introducing the concept of electroacoustic absorbers. The equivalence between shunts and active control is first formalized through the introduction of a one-degree-of-freedom acoustic resonator accounting for both electric shunts and acoustic feedbacks. Conversely, electric networks mimicking the performances of active feedback techniques are introduced, identifying shunts with active impedance control. Simulated acoustic performances are presented, with an emphasis on formal analogies between the different control techniques. Examples of electric shunts are proposed for active sound absorption. Experimental assessments are then presented, and the paper concludes with a general discussion on the concept and potential improvements.
Examining the use of a time-varying loudness algorithm for quantifying characteristics of nonlinearly propagated noise (L)
Authors: Swift S. Hales , Gee Kent L.
Published: May 2011

A previous letter by Gee et al. [J. Acoust. Soc. Am. 121, EL1–EL7 (2007)] revealed likely shortcomings in using common, stationary (long-term) spectrum-based measures to quantify the perception of nonlinearly propagated noise. Here, the Glasberg and Moore [J. Audio Eng. Soc. 50, 331–342 (2002)] algorithm for time-varying loudness is investigated. Their short-term loudness, when applied to a shock-containing broadband signal and a phase-randomized signal with equivalent long-term spectrum, does not show a significant difference in loudness between the signals. Further analysis and discussion focus on the possible utility of the instantaneous loudness and the need for additional investigation in this area.
Model-based sediment classification using single-beam echosounder signals
Authors: Snellen Mirjam , Siemes Kerstin , Simons Dick G.
Published: May 2011

Acoustic remote sensing techniques for mapping sediment properties are of interest due to their low costs and high coverage. Model-based approaches directly couple the acoustic signals to sediment properties. Despite the limited coverage of the single-beam echosounder (SBES), it is widely used. Having available model-based SBES classification tools, therefore, is important. Here, two model-based approaches of different complexity are compared to investigate their practical applicability. The first approach is based on matching the echo envelope. It maximally exploits the information available in the signal but requires complex modeling and optimization. To minimize computational costs, the efficient differential evolution method is used. The second approach reduces the information of the signal to energy only and directly relates this to the reflection coefficient to obtain quantitative information about the sediment parameters. The first approach provides information over a variety of sediment types. In addition to sediment mean grain size, it also provides estimates for the spectral strength and volume scattering parameter. The need to account for all three parameters is demonstrated, justifying computational expenses. In the second approach, the lack of information on these parameters and the limited SBES beamwidth are demonstrated to hamper the conversion of echo energy to reflection coefficient.
The reciprocity theorem for the scattered field is the progenitor of the generalized optical theorem
Authors: Douma Huub , Vasconcelos Ivan , Snieder Roel
Published: May 2011

By analyzing correlation-type reciprocity theorems for wavefields in perturbed media, it is shown that the correlation-type reciprocity theorem for the scattered field is the progenitor of the generalized optical theorem. This reciprocity theorem, in contrast to the generalized optical theorem, allows for inhomogeneous background properties and does not make use of a far-field condition. This theorem specializes to the generalized optical theorem when considering a finite-size scatterer embedded in a homogeneous background medium and when utilizing the far-field condition. Moreover, it is shown that the reciprocity theorem for the scattered field is responsible for the cancellation of non-physical (spurious) arrivals in seismic interferometry, and as such provides the mathematical description of such arrivals. Even though here only acoustic waves are treated, the presented treatment is not limited to such wavefields and can be generalized to general wavefields. Therefore, this work provides the framework for deriving equivalents of the generalized optical theorem for general wavefields.
The breaking of cochlear scaling symmetry in human newborns and adults
Authors: Abdala Carolina , Dhar Sumitrajit , Mishra Srikanta
Published: May 2011

Scaling symmetry appears to be a fundamental property of the cochlea as evidenced by invariant distortion product otoacoustic emission (DPOAE) phase above ∼1–1.5 kHz when using frequency-scaled stimuli. Below this frequency demarcation, phase steepens. Cochlear scaling and its breaking have been described in the adult cochlea but have not been studied in newborns. It is not clear whether immaturities in cochlear mechanics exist at birth in the human neonate. In this study, DPOAE phase was recorded with a swept-tone protocol in three, octave-wide segments from 0.5 to 4 kHz. The lowest-frequency octave was targeted with increased signal averaging to enhance signal-to-noise ratio (SNR) and focus on the apical half of the newborn cochlea where breaks from scaling have been observed. The results show: (1) the ear canal DPOAE phase was dominated by the distortion-source component in the low frequencies; thus, the reflection component cannot explain the steeper slope of phase; (2) DPOAE phase-frequency functions from adults and infants showed an unambiguous discontinuity around 1.4 and 1 kHz when described using two- and three-segment fits, respectively, and (3) newborns had a significantly steeper slope of phase in the low-frequency portion of the function which may suggest residual immaturities in the apical half of the newborn cochlea.
A simulation study on photoacoustic signals from red blood cells
Authors: Saha Ratan K. , Kolios Michael C.
Published: May 2011

A two dimensional simulation study was performed to investigate the photoacoustic signal properties of non-aggregated and aggregated erythrocytes. Spatial distributions of non-aggregated blood samples were generated by employing a Monte Carlo method and aggregated blood samples were simulated using a hexagonal packing scheme. For the non-aggregating case photoacoustic signals demonstrated a monotonic rise with hematocrit. For the aggregating case it was found that spectral (<20 MHz) intensity increased (11 dB at 15.6 MHz) when the aggregate size increased. This study strongly suggests that the assessment of erythrocyte aggregation level in human blood might be possible by using a photoacoustic spectroscopic method.
Six-month-old infants discriminate voicing on the basis of temporal envelope cues (L)
Authors: Bertoncini Josiane , Nazzi Thierry , Cabrera Laurianne , Lorenzi Christian
Published: May 2011

Young deaf children using a cochlear implant develop speech abilities on the basis of speech temporal-envelope signals distributed over a limited number of frequency bands. A Headturn Preference Procedure was used to measure looking times in 6-month-old, normal-hearing infants during presentation of repeating or alternating sequences composed of different tokens of /aba/and /apa/ processed to retain envelope information below 64 Hz while degrading temporal fine structure cues. Infants attended longer to the alternating sequences, indicating that they perceive the voicing contrast on the basis of envelope cues alone in the absence of fine spectral and temporal structure information.
Octave illusion elicited by overlapping narrowband noises
Authors: Jonas Brännström K. , Nilsson Patrik
Published: May 2011

The octave or Deutsch illusion occurs when two tones, separated by about one octave, are presented simultaneously but alternating between ears, such that when the low tone is presented to the left ear the high tone is presented to the right ear and vice versa. Most subjects hear a single tone that alternates both between ears and in pitch; i.e., they hear a low pitched tone in one ear alternating with a high pitched tone in the other ear. The present study examined whether the illusion can be elicited by aperiodic signals consisting of low-frequency band-pass filtered noises with overlapping spectra. The amount of spectral overlap was held constant, but the high- and low-frequency content of the signals was systematically varied. The majority of subjects perceived an auditory illusion in terms of a dominant ear for pitch and lateralization by frequency, as proposed by Deutsch [(1975a) Sci. Am. 233, 92–104]. Furthermore, the salience of the illusion increased as the high frequency of the content in the signal increased. Since no harmonics were present in the stimuli, it is highly unlikely that this illusion is perceived on the basis of binaural diplacusis or harmonic binaural fusion.
The sound strength parameter G and its importance in evaluating and planning the acoustics of halls for music
Authors: Beranek Leo
Published: May 2011

The parameter, “Strength of Sound G” is closely related to loudness. Its magnitude is dependent, inversely, on the total sound absorption in a room. By comparison, the reverberation time (RT) is both inversely related to the total sound absorption in a hall and directly related to its cubic volume. Hence, G and RT in combination are vital in planning the acoustics of a concert hall. A newly proposed “Bass Index” is related to the loudness of the bass sound and equals the value of G at 125 Hz in decibels minus its value at mid-frequencies. Listener envelopment (LEV) is shown for most halls to be directly related to the mid-frequency value of G. The broadening of sound, i.e., apparent source width (ASW) is given by degree of source broadening (DSB) which is determined from the combined effect of early lateral reflections as measured by binaural quality index (BQI) and strength G. The optimum values and limits of these parameters are discussed.
On the efficacy of spatial sampling using manual scanning paths to determine the spatial average sound pressure level in rooms
Authors: Hopkins Carl
Published: May 2011

In architectural acoustics, noise control and environmental noise, there are often steady-state signals for which it is necessary to measure the spatial average, sound pressure level inside rooms. This requires using fixed microphone positions, mechanical scanning devices, or manual scanning. In comparison with mechanical scanning devices, the human body allows manual scanning to trace out complex geometrical paths in three-dimensional space. To determine the efficacy of manual scanning paths in terms of an equivalent number of uncorrelated samples, an analytical approach is solved numerically. The benchmark used to assess these paths is a minimum of five uncorrelated fixed microphone positions at frequencies above 200 Hz. For paths involving an operator walking across the room, potential problems exist with walking noise and non-uniform scanning speeds. Hence, paths are considered based on a fixed standing position or rotation of the body about a fixed point. In empty rooms, it is shown that a circle, helix, or cylindrical-type path satisfy the benchmark requirement with the latter two paths being highly efficient at generating large number of uncorrelated samples. In furnished rooms where there is limited space for the operator to move, an efficient path comprises three semicircles with 45°–60° separations.
Level dependence of distortion product otoacoustic emission phase is attributed to component mixing
Authors: Abdala Carolina , Dhar Sumitrajit , Kalluri Radha
Published: May 2011

Distortion product otoacoustic emissions (DPOAEs) measured in the ear canal represent the vector sum of components produced at two regions of the basilar membrane by distinct cochlear mechanisms. In this study, the effect of stimulus level on the 2f1 − f2 DPOAE phase was evaluated in 22 adult subjects across a three-octave range. Level effects were examined for the mixed DPOAE signal measured in the ear canal and after unmixing components to assess level effects individually on the distortion (generated at the f1, f2 overlap) and reflection (at fdp) sources. Results show that ear canal DPOAE phase slope becomes steeper with decreasing level; however, component analysis further explicates this result, indicating that interference between DPOAE components (rather than a shift in mechanics related to distortion generation) drives the level dependence of DPOAE phase measured in the ear canal. The relative contribution from the reflection source increased with decreasing level, producing more component interference and, at times, a reflection-dominated response at the lowest stimulus levels. These results have implications for the use of DPOAE phase to study cochlear mechanics and for the potential application of DPOAE phase for clinical purposes.
Use of intonation contours for speech recognition in noise by cochlear implant recipients
Authors: Meister Hartmut , Landwehr Markus , Pyschny Verena , Grugel Linda , Walger Martin
Published: May 2011

The corruption of intonation contours has detrimental effects on sentence-based speech recognition in normal-hearing listeners Binns and Culling [(2007). J. Acoust. Soc. Am. 122, 1765–1776]. This paper examines whether this finding also applies to cochlear implant (CI) recipients. The subjects’ F0-discrimination and speech perception in the presence of noise were measured, using sentences with regular and inverted F0-contours. The results revealed that speech recognition for regular contours was significantly better than for inverted contours. This difference was related to the subjects’ F0-discrimination providing further evidence that the perception of intonation patterns is important for the CI-mediated speech recognition in noise.
Temporal aspects of suppression in distortion-product otoacoustic emissions
Authors: Rodriguez Joyce , Neely Stephen T.
Published: May 2011

This study examined the time course of cochlear suppression using a tone-burst suppressor to measure decrement of distortion-product otoacoustic emissions (DPOAEs). Seven normal-hearing subjects with ages ranging from 19 to 28 yr participated in the study. Each subject had audiometric thresholds ≤15 dB HL [re ANSI (2004) Specifications for Audiometers] for standard octave and inter-octave frequencies from 0.25 to 8 kHz. DPOAEs were elicited by primary tones with f2 = 4.0 kHz and f1 = 3.333 kHz (f2/f1 = 1.2). For the f2, L2 combination, suppression was measured for three suppressor frequencies: One suppressor below f2 (3.834 kHz) and two above f2 (4.166 and 4.282 kHz) at three levels (55, 60, and 65 dB SPL). DPOAE decrement as a function of L3 for the tone-burst suppressor was similar to decrements obtained with longer duration suppressors. Onset- and setoff- latencies were ≤4 ms, in agreement with previous physiological findings in auditory-nerve fiber studies that suggest suppression results from a nearly instantaneous compression of the waveform. Persistence of suppression was absent for the below-frequency suppressor (f3 = 3.834 kHz) and was ≤3 ms for the two above-frequency suppressors (f3 = 4.166 and 4.282 kHz).
Methylation of a Phosphatase Specifies Dephosphorylation and Degradation of Activated Brassinosteroid Receptors
Authors: Wu Guang , Wang Xiuling , Li Xianbin , Kamiya Yuji , Otegui Marisa S. , Chory Joanne
Published: May 2011

The abundance of brassinosteroid receptors and thus the intensity of brassinosteroid signaling are set by methylation of a protein phosphatase.
Phosphorylation Makes the Switch
Authors: Wong Wei
Published: May 2011

Phosphorylation enables DISC1 to drive proliferation and migration at the appropriate times in the developing cerebral cortex.
Two Cells, One Receptor Complex
Authors: Gough Nancy R.
Published: May 2011

T cells acquire the ligand and a subunit of the interleukin-2 receptor from dendritic cells.
Mass and Flow
Authors: Ray L. Bryan
Published: May 2011

Simultaneous measurement of more than 30 properties in individual human cells is used to characterize signaling in the immune system.
Infectious Behavior
Authors: Hurtley Stella M.
Published: May 2011

Two nematode worm neurons “smell” disease and promote resistance to pathogens.
Remodeling Responses
Authors: Ray L. Bryan
Published: May 2011

Bimodal expression of genes is activated in response to osmotic stress.
Integrating the Chemotactic Response
Authors: Adler Elizabeth M.
Published: May 2011

PDGF stimulates β1 integrin activation to promote stabilization of the actin nucleating protein N-WASP, PDGF internalization, and fibroblast chemotaxis.
Effects of Etravirine Alone and with Ritonavir-Boosted Protease Inhibitors on the Pharmacokinetics of Dolutegravir
Authors: Song Ivy , Borland Julie , Min Sherene , Lou Yu , Chen Shuguang , Patel Parul , Wajima Toshihiro , Piscitelli Stephen C.
Published: May 2011

Dolutegravir (DTG) is an unboosted, once-daily integrase inhibitor currently in phase 3 trials. Two studies evaluated the effects of etravirine (ETR) alone and in combination with ritonavir (RTV)-boosted protease inhibitors (PIs) on DTG pharmacokinetics (PK) in healthy subjects. DTG 50 mg every 24 h (q24h) was administered alone for 5 days in period 1, followed by combination with ETR at 200 mg q12h for 14 days in period 2 (study 1) or with ETR/lopinavir (LPV)/RTV at 200/400/100 mg q12h or ETR/darunavir (DRV)/RTV at 200/600/100 mg q12h for 14 days in period 2 (study 2). PK samples were collected on day 5 in period 1 and day 14 in period 2. All of the treatments were well tolerated. ETR significantly decreased exposures of DTG, with geometric mean ratios of 0.294 (90% confidence intervals, 0.257 to 0.337) for the area under the curve from time zero until the end of the dosage interval (AUC
0-τ
), 0.484 (0.433 to 0.542) for the observed maximum plasma concentration (
C
max
), and 0.121 (0.093 to 0.157) for the plasma concentration at the end of the dosage interval (
C
τ
). ETR combined with an RTV-boosted PI affected the exposure of DTG to a lesser degree: ETR/LPV/RTV treatment had no effect on the DTG plasma AUC
0-τ
and
C
max
, whereas the
C
τ
increased by 28%. ETR/DRV/RTV modestly decreased the plasma DTG AUC
0-τ
,
C
max
, and
C
τ
by 25, 12, and 37%, respectively. Such effects of ETR/LPV/RTV and ETR/DRV/RTV are not considered clinically relevant. The combination of DTG and ETR alone should be avoided; however, DTG may be coadministered with ETR without a dosage adjustment if LPV/RTV or DRV/RTV is concurrently administered.
Exploring the Inhibition of CTX-M-9 by β-Lactamase Inhibitors and Carbapenems
Authors: Bethel Christopher R. , Taracila Magdalena , Shyr Teresa , Thomson Jodi M. , Distler Anne M. , Hujer Kristine M. , Hujer Andrea M. , Endimiani Andrea , Papp-Wallace Krisztina , Bonnet Richard , Bonomo Robert A.
Published: May 2011

Currently, CTX-M β-lactamases are among the most prevalent and most heterogeneous extended-spectrum β-lactamases (ESBLs). In general, CTX-M enzymes are susceptible to inhibition by β-lactamase inhibitors. However, it is unknown if the pathway to inhibition by β-lactamase inhibitors for CTX-M ESBLs is similar to TEM and SHV β-lactamases and why bacteria possessing only CTX-M ESBLs are so susceptible to carbapenems. Here, we have performed a kinetic analysis and timed electrospray ionization mass spectrometry (ESI-MS) studies to reveal the intermediates of inhibition of CTX-M-9, an ESBL representative of this family of enzymes. CTX-M-9 β-lactamase was inactivated by sulbactam, tazobactam, clavulanate, meropenem, doripenem, ertapenem, and a 6-methylidene penem, penem 1.

K
i

values ranged from 1.6 ± 0.3 μM (mean ± standard error) for tazobactam to 0.02 ± 0.01 μM for penem 1. Before and after tryptic digestion of the CTX-M-9 β-lactamase apo-enzyme and CTX-M-9 inactivation by inhibitors (meropenem, clavulanate, sulbactam, tazobactam, and penem 1), ESI-MS and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identified different adducts attached to the peptide containing the active site Ser70 (+52, 70, 88, and 156 ± 3 atomic mass units). This study shows that a multistep inhibition pathway results from modification or fragmentation with clavulanate, sulbactam, and tazobactam, while a single acyl enzyme intermediate is detected when meropenem and penem 1 inactivate CTX-M-9 β-lactamase. More generally, we propose that Arg276 in CTX-M-9 plays an essential role in the recognition of the C
3
carboxylate of inhibitors and that the localization of this positive charge to a “region of the active site” rather than a specific residue represents an important evolutionary strategy used by β-lactamases.
Establishment of a Novel Model of Onychomycosis in Rabbits for Evaluation of Antifungal Agents
Authors: Shimamura Tsuyoshi , Kubota Nobuo , Nagasaka Saori , Suzuki Taku , Mukai Hideki , Shibuya Kazutoshi
Published: May 2011

We developed a novel model of onychomycosis in which we observed fungi in the deep layer of the nail, and we used the model to evaluate the efficacy of two topical antifungal drugs. To establish an experimental,
in vivo
model of onychomycosis, we applied
Trichophyton mentagrophytes
TIMM2789 to the nails of the hind limbs of rabbits that underwent steroid treatment. The nails were taken from the rabbits' feet at 0, 2, and 6 weeks after a 2-week infection. The localization of the fungi was evaluated histopathologically. Some fungi were seen to penetrate to the nail bed, and the infection rate in the sample at 0, 2, and 6 weeks after infection was 57, 87, and 93%, respectively. In addition, fungi proliferated and moved proximally into the nail plate in a manner that depended on the duration of infection. Second, using this model we evaluated antifungal efficacy both by the culture recovery method and histopathological examination. Two topical antifungal drugs, 8% ciclopirox nail lacquer and 5% amorolfine nail lacquer, were applied to the nail for 4 weeks in each group. On histopathological examination, two antifungal treatment groups showed no significant difference against the nontreated control group. However, there were a significantly low fungus-positive rate and intensity of the recovery of fungi on culture between antifungal treatment and nontreated control groups. We therefore suggest that we have established an
in vivo
model of onychomycosis that is useful for the evaluation of the efficacy of antifungal agents.
Population Pharmacokinetics of Colistin Methanesulfonate and Formed Colistin in Critically Ill Patients from a Multicenter Study Provide Dosing Suggestions for Various Categories of Patients
Authors: Garonzik S. M. , Li J. , Thamlikitkul V. , Paterson D. L. , Shoham S. , Jacob J. , Silveira F. P. , Forrest A. , Nation R. L.
Published: May 2011

With increasing clinical emergence of multidrug-resistant Gram-negative pathogens and the paucity of new agents to combat these infections, colistin (administered as its inactive prodrug colistin methanesulfonate [CMS]) has reemerged as a treatment option, especially for critically ill patients. There has been a dearth of pharmacokinetic (PK) data available to guide dosing in critically ill patients, including those on renal replacement therapy. In an ongoing study to develop a population PK model for CMS and colistin, 105 patients have been studied to date; these included 12 patients on hemodialysis and 4 on continuous renal replacement therapy. For patients not on renal replacement, there was a wide variance in creatinine clearance, ranging from 3 to 169 ml/min/1.73 m
2
. Each patient was treated with a physician-selected CMS dosage regimen, and 8 blood samples for PK analysis were collected across a dosage interval on day 3 or 4 of therapy. A linear PK model with two compartments for CMS and one compartment for formed colistin best described the data. Covariates included creatinine clearance on the total clearance of CMS and colistin, as well as body weight on the central volume of CMS. Model-fitted parameter estimates were used to derive suggested loading and maintenance dosing regimens for various categories of patients, including those on hemodialysis and continuous renal replacement. Based on our current understanding of colistin PK and pharmacodynamic relationships, colistin may best be used as part of a highly active combination, especially for patients with moderate to good renal function and/or for organisms with MICs of ≥1.0 mg/liter.
Symmetry Requirements for Effective Blocking of Pore-Forming Toxins: Comparative Study with α-, β-, and γ-Cyclodextrin Derivatives
Authors: Yannakopoulou Konstantina , Jicsinszky Laszlo , Aggelidou Crysie , Mourtzis Nikolaos , Robinson Tanisha M. , Yohannes Adiamseged , Nestorovich Ekaterina M. , Bezrukov Sergey M. , Karginov Vladimir A.
Published: May 2011

We compared the abilities of structurally related cationic cyclodextrins to inhibit
Bacillus anthracis
lethal toxin and
Staphylococcus aureus
α-hemolysin. We found that both β- and γ-cyclodextrin derivatives effectively inhibited anthrax toxin action by blocking the transmembrane oligomeric pores formed by the protective antigen (PA) subunit of the toxin, whereas α-cyclodextrins were ineffective. In contrast, α-hemolysin was selectively blocked only by β-cyclodextrin derivatives, demonstrating that both symmetry and size of the inhibitor and the pore are important.