bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of segmental factors on fundamental frequency in fluent speech
Authors: Umeda Noriko
Published: October 2005

The segmental factors which determine the fundamental frequency, F0, of vowels in stressed syllables in fluent readings were studied. The paper describes five characteristics of F0 in the following vowel for different preceding consonants: (1) the direction of F0 change at the vowel onset, (2) the frequency at voice onset, (3) the peak F0 during the vowel, (4) the amount of F0 increase, and (5) the time required to reach the peak. The two speakers show similar consistent tendencies for all the fundamental-frequency characteristics. Our results are similar to those reported with isolated or carrier-phrased utterences in general, but different in details. Evidence for the so-called intrinsic fundamental frequencies for different vowels was not observed in our data.
Identification of local and propagating distortion products from cochlear microphonic responses
Authors: Ronken Don A. , Eldredge Donald H.
Published: October 2005

Careful measurements show that sound pressures of 40 dB re 20 μN/m2 are sufficient to reveal two varieties of well-behaved, nonlinear distortion products in the cochlear microphonic (CM). The first variety appears in the primary-tone area and is designated as a local CM distortion product. The second type exists apical to the primary-tone area and is identical to the mechanically propagated distortion seen in the phase-locked responses of primary auditory nerve fibers. The existence of the propagating distortion product forces the conclusion that there must be a mechanical contribution to the local ’’CM’’ distortion product as well. The intrusion of nonlinear mechanical responses at such low levels (<40 dB SPL) indicates that the effective mechanical input to the hair cells may be nonlinear over most of the audible range. An important but unanswered question is the range over which the transducer characteristic of CM could be effectively linear, for that would determine whether CM could be used to probe mechanical nonlinear effects in the primary tone area.
Adaptive focusing: A spatial distortion-adaptive receiver
Authors: Claus A. J. , Labianca F. M.
Published: October 2005

Adaptive focusing is an array processing scheme in which the receiver is designed for adaptive detection of localized sources under conditions where the signal field distribution across the array aperture is distorted from that of a plane wave, but is unknown a priori. Complex propagation conditions, including slow medium fluctuations, coupled with source motion render the signal field non-Gaussian. This property is brought into play in the design of the detector as a maximum-likelihood receiver which actually exploits the slowness of the acoustic channel changes. The problem is to detect the signal in a spatially white Gaussian noise field. The receiver utilizes the spatial structure of the signal as it manifests itself in the maximum eigenvalue of the data sample covariance matrix. Temporal stability of the field distribution and signal-to-noise ratio are important parameters. These are incorporated into a Monte Carlo simulation which shows that for stable signals at threshold level in the output of a conventional beamformer degraded by 5 dB, adaptive focusing can perform within a fraction of 1 dB of a hypothetical ideal beamformer for which the signal field is known a priori. Decreased temporal stability coming about as a result of, say, increased source motion necessarily has an adverse affect on performance.
Adaptive focusing: The likelihood ratio
Authors: Labianca F. M. , Lloyd S. P.
Published: October 2005

The problem of detecting a certain non-Gaussian random acoustic signal field in a spatially white Gaussian noise field is solved within the formalism of classical detection theory. Two solutions of the problem are compared: the maximum-likelihood or adaptive-focusing (AF) receiver and the Neyman–Pearson or adaptive focusing optimal (AFO) receiver. Based on two criteria for comparison, it is found that the two receivers differ only slightly in performance with the AFO, of course, being the better. One of the criteria is based on the signal deflection ratio, and the other is the ROC (receiver operating characteristic) curve. The comparisons are done for a Monte Carlo simulation.
Comparison of coupled-mode theory with the small-waveheight approximation for sea-surface scattering
Authors: McDaniel Suzanne T.
Published: October 2005

The coupled-mode theory of sea-surface scattering is shown to be identical to the small-waveheight theory for the case of a deep isovelocity ocean where the modal spectrum forms a continuum. Numerical calculations demonstrate that the same results are also obtained for a shallow-water example where the modal spectrum is discrete.
Effect on short-range propagation of random currents in a perturbed cylindrical eddy
Authors: Newhall B. K. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

An analysis of a perturbed idealized cyclonic mesoscale eddy is performed. Included are random perturbations from perfectly circular streamlines and random perturbations in current magnitude. The random current fluctuations are required to satisfy conservation of mass. Short-range acoustic transmissions through the perturbed eddy are considered, and an approximate solution of the ray equations is found. An approximation for ray travel times is developed in terms of the horizontally averaged, source–receiver current component, and travel-time statistics are investigated. Travel times over different ray paths are nearly perfectly correlated, implying that current perturbations can have significant effects on total-field phase, but have little effect on total-field intensity. Statistics of the horizontally averaged current components are analyzed and their effects on travel times and acoustic phase are determined for various source and receiver locations in the eddy. Source–receiver orientation is shown to be crucial in determining current effects on both the mean and the standard deviation of phase.
Statistical estimation of correlation for nonstationary aircraft noise
Authors: Cho P. L. , Maestrello I. L.
Published: October 2005

Based on the acoustic radiation theory for a moving source, the estimation of the correlation function of a nonstationary acoustic signal is considered. We obtain an estimator for the acoustic correlation, which is shown to be unbiased and consistent. The estimation procedure can be applied to an aircraft noise measurement, where the reflected wave can be eliminated.
Finite-difference solution to the parabolic wave equation
Authors: Lee Ding , Botseas George , Papadakis John S.
Published: October 2005

In this article an implicit finite-difference (IFD) scheme is introduced for solving underwater acoustic wave propagation problems. This scheme is applied to the parabolic wave equation model for the acoustic problem with a free surface and arbitrary bottom and bottom boundary conditions. The mathematical theory of the implicit finite-difference method as applied to the parabolic equation is developed, and a computer model to implement the IFD is introduced. Representative problems are presented to demonstrate the capability of the IFD model. Advantages and limitations of the IFD are discussed.
Improved ray calculations in shallow water
Authors: Tindle C. T. , Bold G. E. J.
Published: October 2005

The lateral displacement of a bounded beam which is totally reflected from an interface is well-known. This beam displacement is used to modify the ray paths in a ray model of shallow water propagation in the simple Pekeris channel. Inclusion of the beam displacement for total reflection at the bottom greatly alters the eigenray distribution. Coherent summation of pulses traveling along each eigenray yields a series of arrivals with the depth dependence characteristic of normal modes. The calculations are in good agreement with experimental data obtained at 5.1-km range in water 50 m deep for four cycle pulse transmissions in the range 60–140 Hz. There is also good agreement with the results of normal mode calculations and exact analytic expressions for the mode eigenvalues and group velocities are obtained using the actual eigenrays of the problem. The improved ray method appears to be as good as normal mode theory for practical calculations in shallow water.
Ultrasonic visualization of tongue motion during speech
Authors: Sonies Barbara C. , Shawker Thomas H. , Hall Thomas E. , Gerber Lynn H. , Leighton Stephen B.
Published: October 2005

A real-time ultrasonic imaging system has been developed to visualize dynamic motions of the tongue during continuous speech. Lingual motion configurations are displayed and recorded synchronously with the speech signal, time in milliseconds, and frontal and lateral views of the face during articulation. All data are video-taped and stored permanently for analysis. Data on the vertical movement of the tongue surface was obtained on 30 normal adult speakers. This technique seems to provide a useful, noninvasive technique for quantifying tongue position during speech utterances and possibly has potential as a clinical tool.
Linear dynamic range of an optical nearfield diffraction technique for studying ultrasonic waves
Authors: Riley Ward A.
Published: October 2005

An optical nearfield diffraction technique was recently described for studying ultrasonic waveforms in the low megahertz frequency range [W. A. Riley, J. Acoust. Soc. Am. 67, 1386–1388 (1980)]. The theoretical optical amplitude response of this technique is linear with acoustic pressure under only a limited range of experimental conditions. The objective of this work was to experimentally determine the linear dynamic range of this optical system assembled from inexpensive components and used in conjunction with a good laboratory oscilloscope. A linear dynamic range of approximately 20 dB was determined from these results which corresponds to acoustical powers between 0.1 and 10 mW in distilled water. This 20-dB window can be lowered approximately 10 dB by selecting an acousto-optic medium more efficient than water. It can be raised by 40 dB by examining normal reflections from the boundary between liquids having small acoustic impedance differences. With this approach, one can effectively observe narrow-band acoustic pulse waveforms over a 70-dB dynamic range from approximately 10 μW to 100 W with a precision of approximately 1 dB.
Scattering of sound waves at the ocean surface: A diffraction theory
Authors: Holford R. L.
Published: October 2005

Previous treatments of the scattering of sound at a rough ocean surface have dealt with cases where the surface irregularities are much larger or much smaller than the acoustic wavelength. This paper provides an attack on the important practical problem of cases where the surface roughness and acoustic wavelength are of comparable magnitude. In this approach, a complex ocean surface is considered to be decomposed into its periodic components or traveling waves, each of which acts as a moving diffraction grating that scatters the incident energy into certain characteristic directions (the diffraction orders) with associated Doppler shifts which are harmonics of the surface-wave frequency. The solution for scattering from any one such traveling wave is obtained by the novel application of a Lorentz-type transformation which reduces the problem to one of a stationary grating. Phenomenological treatments are given for both one- and two-dimensionally rough surfaces and applied to the results of a laboratory experiment. A leading implication of the theory in case of plane-wave illumination of a wind-driven sea surface is that the field scattered into a given direction has its origin in surface waves possessing certain ’’resonant’’ wavelengths and traveling at a unique angle to the wind direction.
Scattering of sound waves at a periodic, pressure-release surface: An exact solution
Authors: Holford R. L.
Published: October 2005

It has been demonstrated that the problem of plane-wave scattering from a traveling ocean wave can be reduced to that of plane-wave scattering from a stationary, periodic, pressure-release surface. An exact method of solution to the latter problem is presented herein. The important characteristic of a periodic surface is that it produces strong, directional scattering when its period is comparable with the wavelength of the incident radiation, and the method provides an efficient scheme for numerical evaluation of the scattering amplitudes in case of a smooth profile of arbitrary shape. A review of previously reported ’’exact’’ solutions is given and it is shown that they fail for rather fundamental reasons which do not appear to be generally understood or appreciated. On the other hand, the work of Urusovskii on a closely related problem does not suffer from the same inadequacy and provides the lead to the rigorous method of solution given herein. It is shown how the method of solution can be extended (following Urusovskii) to treat the case of an arbitrary incident field and a refractive medium when the surface is at rest.
Modified Prony method approach to echo-reduction measurements
Authors: Trivett D. H. , Robinson A. Zed
Published: October 2005

A modified Prony method is presented for measuring the steady-state echo reduction of acoustic panels. The method extrapolates the steady-state amplitudes from the transient portion of the signal allowing time-limited measurements. The method is applied to measurements of square panels 76 cm on an edge and 0.95-cm thick of steel and aluminum in the frequency range of 3–10 kHz. The signals were time limited to 200 μs (0.6 to 2.0 wavelengths) by the arrival of the diffracted signal from the panel edges. Results are compared with theoretical values and indicate the method is capable of making measurements subject to ambient noise.
Estimation of location and motion parameters of a moving source observed from a linear array
Authors: Hassab Joseph C. , Guimond Brian W. , Nardone Steven C.
Published: October 2005

A structure is presented for passive estimation of range and bearing as well as velocity of a source from a linear array. It uses a quasi-optimal post processor of the time delays, which are obtained from a generalized correlator with finite observation time. The post processor ultimately maps the sequential time-delay observations onto invariant source trajectory parameters over which smoothing is performed to reduce, jointly, the variance and the bias in the estimate of the source kinematics. The present approach remains viable for moving sources at long ranges, off-broadside source directions and high time-delay variances. Analysis and simulation results are presented to justify its usefulness under the stated stringent conditions. Review of and comparison to existing approaches are made to highlight the viability of present approach in the estimation of source trajectory.
Model for a piezoelectric polymer flexural plate hydrophone
Authors: Ricketts Donald
Published: October 2005

A mathematical model of the piezoelectric polymer flexural plate hydrophone is presented, with application to sheets of polymer attached to air-backed rectangular flexural plates. Expressions are given for the low-frequency electroacoustic sensitivity, as well as for the evaluation of hydrophone mechanical behavior under hydrostatic loading. Numerical results are presented for the supported plate and for the special case of a supported beam. The analytic results reveal that the selection criterion for the substrate plate should be its strength-to-elastic modulus ratio, in order to maximize the product of hydrophone sensitivity and maximum operating pressure. The theoretical model is applied to a plastic flexural plate polymer hydrophone, which results in close agreement between the predicted and measured sensitivities.
An underwater sound sensor with interdigital transducers operating at liquid–solid interface
Authors: Toda Kohji , Katayama Kazumi , Urabe Heijiro
Published: October 2005

A new sound sensor system is proposed by the use of two delay devices with interdigital transducers operating at liquid–solid interface. One of two devices, immersed in water, has a delay time dependent upon the sound pressure level. The variation of the phase difference between two output signals of the delay devices, corresponding to a sound signal in water, is detected as an electrical signal via a phase comparating circuit. The sensitivity of the system is constant at frequencies below 800 Hz.
Absolute calibration of microphones by a laser-Doppler technique
Authors: Taylor K. J.
Published: October 2005

A new technique for the absolute calibration of microphones is described. This is based on the measurement of acoustic particle velocity in a traveling-wave tube by means of a laser-Doppler system. From this measurement and a knowledge of the specific acoustic impedance of the air in the tube, the sound pressure is determined at a point in the tube where a microphone is mounted and, by measuring the output voltage of the microphone, its sensitivity is found. At 500 Hz, the method is accurate to within ±0.03 dB. No significant discrepancy was found between a calibration by this method and one by a precise reciprocity technique, although there is some residual uncertainty arising from the fact that one calibration is made in a small coupler and the other in an essentially free field. The result is seen as validating the assumption of reciprocity on which most precise microphone calibrations rely.
Average dose absorbed by biological specimens in a diffuse ultrasonic exposure field
Authors: Christman C. L.
Published: October 2005

A reverberation method has been investigated for determining the total acoustic energy absorbed by biological specimens exposed to ultrasound at clinical frequencies. The specimen is exposed to a diffuse ultrasonic field created in a small water-filled tank by a 1.0-MHz carrier signal, frequency modulated with white noise. Measurements of the total acoustic input power and the decay rate, both with and without the specimen, are used to determine average dose. Three different methods for measuring input power and one method for measuring decay rate have been investigated. Numerous performance tests have been used to assign uncertainty limits for the measurement of average dose. This new reverberation exposure method has been compared to the more traditional free-field exposure method by recording the temperature rise within anesthetized mice for both methods. These results will be used to estimate the exposure conditions for each method needed to produce the same average temperature rise within an animal.
Synthesizing intonation
Authors: Pierrehumbert Janet
Published: October 2005

This paper describes a computer program for synthesizing fundamental frequency (F0) contours for English, and sketches the theory which underlies it. The F0 contour is described as a series of targets within an envelope specifying F0 range; the F0 contour between targets is computed by transition rules. The use of nonmonotonic transitions permits a sparser specification of the contour than has been possible in most previous frameworks. The program generates a good synthesis of neutral declarative intonation. Unlike most previous F0 synthesis programs, it can also be used to synthesize a variety of non-neutral intonation patterns.
Diffraction of sound by a convex or a concave dome in an infinite baffle
Authors: Suzuki Hideo , Tichy Jiri
Published: October 2005

In the previous paper [Suzuki and Tichy, J. Acoust. Soc. Am. 69, 41–49 (1981)] the radiation from a convex or a concave dome in an infinite baffle was discussed. This paper is concerned with the second part of the work, dealing with the diffraction of sound by a convex or a concave dome. The effect of the dome on the on-axis sound pressure responses and directivity patterns of a concentric ring source were calculated using a least-square error method. The representation of the sound field by the energy flow as well as the pressure distribution around the source was quite successfully used to discuss the diffraction phenomena.
Simplified technique for the calibration and use of a miniature hydrophone in intensity measurements of pulsed ultrasound fields
Authors: Jones Steven M. , Carson Paul L. , Banjavic Richard A. , Meyer Charles R.
Published: October 2005

A simplified technique for calibration of the response of a miniature hydrophone as a function of frequency was evaluated experimentally for reproducibility and for its uncertainty in calibration of hydrophones intended for intensity measurements in broadband medical ultrasound fields. In this hydrophone calibration technique, the known total acoustic power passing through a plane lying normal to an ultrasound beam is compared with the surface integral of the intensity over that plane. Broadband source transducers calibrated by the National Bureau of Standards were driven in a narrow-band tone-burst mode to calibrate the hydrophone at multiple discrete frequencies. A least squares polynomial fit to the discrete values provided a continuous estimate curve of the hydrophone intensity response factor (Kf2) as a function of frequency. Good reproducibility of this multipoint technique was demonstrated by an independent, but similar, calibration of the hydrophone by the Bureau of Radiological Health. This hydrophone was then employed to measure acoustic intensities and power in broadband fields of typical pulse echo systems. If the variation in Kf2 is adequately small over the frequency spectrum of the measured pulse and the wave pressure is not so high as to be producing large nonlinear effects, a ±30% uncertainty in SPTA intensity can be achieved by use of a single Kf2 value determined either at the center frequency of the pulse or as the mean of the Kf2 values at the center and half-power frequencies of the spectrum of the pulse. In those cases where the variability of Kf2 exceeds ±1.5 dB over a one-octave range centered about the center frequency of the pulse’s spectrum, use of an effective Kf2 value determined by a deconvolution technique is recommended.
Resonance frequencies of the recorder (English flute)
Authors: Lyons Donald H.
Published: October 2005

The passive resonance frequencies of the alto recorder have been measured and compared with the frequencies of blown notes. The acoustic reactance of the opening from the windway to the tone-generating edge, i.e., the window, was determined experimentally, as a function of frequency over the playing range. The window is found to act like an open extension of the recorder, about 35-mm long for the middle frequency range. A compact theoretical treatment of perturbations from an ’’ideal’’ recorder is given, and used to calculate the blown and passive resonance frequencies. The results of the calculation are compared to the experimental frequencies. The typical deviation between theory and experiment is of the order of 12 cents (0.7%).
Pure-tone sensitivity and ear canal pressure at threshold in children and adults
Authors: Yoneshige Yvonne , Elliott Lois L.
Published: October 2005

Previous investigations have found that young children have poorer pure-tone auditory sensitivity than older children or adults. This study addressed the question of whether these age-related sensitivity differences are attributable to children having middle ear disorders that produce a conductive hearing loss or to differences in ear canal sound pressure at threshold. Results ruled out both of these possible explanations for the age effect.
AP measurements of short-term adaptation in normal and in acoustically traumatized ears
Authors: Gorga Michael P. , Abbas Paul J.
Published: October 2005

A forward-masking paradigm was used to measure short-term adaptation in normal and in acoustically traumatized ears. AP amplitude was measured to a tone burst of fixed frequency and level while masker intensity (Lm) and duration (Tm), as well as the interval between masker offset and probe onset (Δt) were varied. Masker and probe frequency were held constant at 4 kHz. In one experiment, short-term perstimulatory adaptation was examined through the measurement of probe-elicited N1 amplitude at a fixed Δt while both Lm and Tm were varied. These probe response-versus-Tm functions were modeled exponentially, yielding time constants that did not differ between normal and exposed ears. In another series of experiments, recovery from short-term adaptation was examined by holding Tm constant and measuring probe-response amplitude as a function of Δt. When the decrement- (amount by which the probe-elicited N1 amplitude was reduced by the masker) versus-Δt functions were fit with an exponential model that accounted for long-term effects, no differences were observed between recovery time constants from normal and traumatized ears. Finally, growth of response to the masker was estimated by examining the decrement in normalized amplitude of response to the probe as a function of Lm. Acoustically traumatized ears revealed steeper growth functions, suggesting steeper single-fiber rate-versus-level functions.
On the Biot–Gassmann equations for the elastic moduli of porous rocks (Critical comment on a paper by J. G. Berryman)
Authors: Korringa J.
Published: October 2005

Equations for the Biot moduli H, C, and M by J. G. Berryman [J. Acoust. Soc. Am. 69, 416–424 (1981)] are shown to be wrong. A new first principles derivation of the generally accepted equations is given. It is obtained from relations which are tautological in the framework of elastostatics with one simplifying substitution which reflects the assumption that equal changes in pore pressure and confining pressure leave the porosity unchanged. An assumption equivalent to this was made by Biot. A porous rock with a matrix of homogeneous material would have this property. This was assumed by Gassmann.
Re-examination of the low-frequency (50–1000 Hz) normal threshold of hearing in free and diffuse sound fields
Authors: Berger E. H.
Published: October 2005

In two experimental replications involving a total of 17 otologically normal subjects, hearing threshold levels were observed that were from 2.6 to 7.1 dB less sensitive in the 125–1000 Hz frequency range, than those specified in ISO R226–1961. The published data from 12 additional threshold experiments conducted since 1933 were reviewed. Variables that could affect the data, such as free versus diffuse sound fields, pure tones versus 1/3-octave noise band stimuli, psychophysical method, pulsed versus continuous stimuli, binaural versus monaural listening, age, sex, race, and otological rejection criteria, were analyzed. For frequencies from 50–1000 Hz and ages up to 35, the only corrections found to be necessary were for sound field conditions and binaural versus monaural listening. A second-order polynomial regression line was fitted to the combined, corrected data. The resultant thresholds were 5–6 dB less sensitive than ISO R226 between 50 and 250 Hz, with the divergence dropping to +1.7 and −1.5 dB at 500 and 1000 Hz, respectively.
Played-again SAM: Further observations on the pitch of amplitude-modulated noise
Authors: Burns Edward M. , Viemeister Neal F.
Published: October 2005

The pitchlike sensation elicited by sinusoidally amplitude-modulated (SAM) noise remains a controversial phenomenon. The controversy centers on two major points: (1) whether this sensation is ’’really’’ pitch rather than, e.g., roughness or intermittency, and (2) the possibility that any pitch sensation is mediated by short-term spectral information rather than temporal information—thus nullifying an interesting aspect of the phenomenon. Three experiments employing SAM wideband noise, SAM wideband noise bandpass-filtered after modulation, and a SAM 10 kHz pure tone were performed: (1) open-set melody identification, (2) melodic dictation, and (3) musical-interval adjustment. These experiments extend our earlier study [Burns and Viemeister, J. Acoust. Soc. Am. 60, 863 (1976)]. The results provide further evidence that SAM noise can, at suitable modulation frequencies, elicit a sensation of pitch (as defined by the ability to carry melodic information), and that this pitch represents a purely temporal phenomenon.
Laryngeal adjustments in the production of consonant clusters and geminates in American English
Authors: Yoshioka Hirohide , Löfqvist Anders , Hirose Hajime
Published: October 2005

The glottal opening gesture and its timing control in various sequences of voiceless obstruents were investigated by the combined techniques of electromyography, photo-electric glottography, and fiberoptic endoscopy. The results obtained at both electromyographic and movement levels revealed that the glottal opening gesture is characterized by a one-, two-, or more-than-two-peaked pattern in a regular fashion according to the phonetic nature of the voiceless segments: each voiceless obstruent or geminate accompanied by aspiration or frication noise tends to require a single separate peak of the opening gesture, while an unaspirated stop embedded in a voiceless environment can be produced within the opening gesture attributed to an adjacent aspirated stop or fricative. Such an independent opening gesture of the glottis for the production of voiceless aspirated stops or voiceless fricatives even in sequentially unvoiced contexts can be interpreted as assuring the aerodynamic requirements for turbulent noise production during the aspirated stop or fricative segment.
Monaural phase sensitivity with Ronken’s paradigm
Authors: Henning G. Bruce , Gaskell H.
Published: October 2005

This paper describes an experiment using stimuli (pairs of clicks or pulses) similar to those used by Ronken [J. Acoust. Soc. Am. 47, 1091–1099 (1970)] in one part of his investigation of monaural phase sensitivity. The main difference between the studies is that Ronken’s basic pulses were 250 μs in duration whereas ours were 20 μs in duration; phase discrimination fails in Ronken’s experiments when pulse separation is less than about 2 ms but phase discrimination in our experiment fails only when the pulse separation is made less than 200 μs. We consider three different explanations of the results.
Continuous wave transmission techniques for measuring ultrasonic phase and group velocities in dispersive materials and composites
Authors: Lynnworth Lawrence C. , Rea Warren R. , Papadakis Emmanuel P.
Published: October 2005

Phase and group velocities V and U, respectively, were measured in the 100:1 frequency range 50 kHz to 5 MHz using longitudinal and shear ultrasonic continuous waves, in Teflon and in a dispersive three-dimensional reinforced composite. A transmission approach was developed which utilized broadband transducers and a pair of wedges to obtain V by a differential path, fixed frequency technique, and to obtain U by a fixed path differential frequency technique. The path or frequency was incremented to fit additional whole wavelengths in the path, as indicated by 2π phase shifts in a Lissajous pattern. Cross checks between U and V confirmed the validity of the approach at least for the two materials investigated.
Characteristics of cw signals propagated under the ice in the Arctic
Authors: Mikhalevsky Peter N.
Published: October 2005

Envelope statistics and tonal spectra have been measured from 15, 20, and 30-Hz cw signals propagated via an ice-covered path over a range of approximately 300 km. These data were taken during the tristen/framii experiment on the pack ice over the Pole Abyssal Plain in April/May 1980. Five hours of data are analyzed. The received signals were very stable in time and exhibited only minor fluctuations due entirely to the in-band noise. The envelope amplitude statistics are Rician. Though the source and receiver were on drifting ice floes, the drift rates were negligible during transmission periods and thus these results apply to transmissions between essentially fixed terminals.
Effective range derivative for acoustic propagation loss in a horizontally stratified ocean
Authors: Weinberg H.
Published: October 2005

A method for predicting acoustic propagation loss in a horizontally stratified ocean had been developed. We begin by comparing two widely used models, and demonstrate that unresolved discrepancies exist. Then classical ray tracing equations are developed by evaluating a multipath integral by stationary phase. The inaccuracy of ray theory is attributed to deficiencies in the stationary phase approach. In order to correct these shortcomings, we express multipaths in terms of Fresnel integrals and effective range derivatives. The approach is generalized to shadow zone propagation. Finally, we introduce a computer model that is based on the effective range derivative evaluation of the multipath expansion. The main emphasis of this paper, however, is not model comparison, but the effective range derivative technique, itself.
Direct Labeling of Polyphosphate at the Ultrastructural Level inSaccharomyces cerevisiaeby Using the Affinity of the Polyphosphate Binding Domain ofEscherichia coliExopolyphosphatase
Authors: Saito Katsuharu , Ohtomo Ryo , Kuga-Uetake Yukari , Aono Toshihiro , Saito Masanori
Published: October 2005

Inorganic polyphosphate (polyP) is a linear polymer of orthophosphate and has many biological functions in prokaryotic and eukaryotic organisms. To investigate polyP localization, we developed a novel technique using the affinity of the recombinant polyphosphate binding domain (PPBD) ofEscherichia coliexopolyphosphatase to polyP. An epitope-tagged PPBD was expressed and purified fromE. coli. Equilibrium binding assay of PPBD revealed its high affinity for long-chain polyP and its weak affinity for short-chain polyP and nucleic acids. To directly demonstrate polyP localization inSaccharomyces cerevisiaeon resin sections prepared by rapid freezing and freeze-substitution, specimens were labeled with PPBD containing an epitope tag and then the epitope tag was detected by an indirect immunocytochemical method. A goat anti-mouse immunoglobulin G antibody conjugated with Alexa 488 for laser confocal microscopy or with colloidal gold for transmission electron microscopy was used. When theS. cerevisiaewas cultured in yeast extract-peptone-dextrose medium (10 mM phosphate) for 10 h, polyP was distributed in a dispersed fashion in vacuoles in successfully cryofixed cells. A few polyP signals of the labeling were sometimes observed in cytosol around vacuoles with electron microscopy. Under our experimental conditions, polyP granules were not observed. Therefore, it remains unclear whether the method can detect the granule form. The method directly demonstrated the localization of polyP at the electron microscopic level for the first time and enabled the visualization of polyP localization with much higher specificity and resolution than with other conventional methods.
Metabolic Engineering of the Purine Pathway for Riboflavin Production in
Ashbya gossypii
Authors: Jiménez Alberto , Santos María A. , Pompejus Markus , Revuelta José L.
Published: October 2005

Purine nucleotides are essential precursors for living organisms because they are involved in many important processes, such as nucleic acid synthesis, energy supply, and the biosynthesis of several amino acids and vitamins such as riboflavin. GTP is the immediate precursor for riboflavin biosynthesis, and its formation through the purine pathway is subject to several regulatory mechanisms in different steps. Extracellular purines repress the transcription of most genes required for de novo ATP and GTP synthesis. Additionally, three enzymes of the pathway, phosphoribosyl pyrophosphate (PRPP) amidotransferase, adenylosuccinate synthetase, and IMP dehydrogenase, are subject to feedback inhibition by their end products. Here we report the characterization and manipulation of the committed step in the purine pathway of the riboflavin overproducer
Ashbya gossypii
. We report that phosphoribosylamine biosynthesis in
A. gossypii
is negatively regulated at the transcriptional level by extracellular adenine. Furthermore, we show that ATP and GTP exert a strong inhibitory effect on the PRPP amidotransferase from
A. gossypii
. We constitutively overexpressed the Ag
ADE4
gene encoding PRPP amidotransferase in
A. gossypii
, thereby abolishing the adenine-mediated transcriptional repression. In addition, we replaced the corresponding residues (aspartic acid
310
, lysine
333
, and alanine
417
) that have been described to be important for PRPP amidotransferase feedback inhibition in other organisms by site-directed mutagenesis. With these manipulations, we managed to enhance metabolic flow through the purine pathway and to increase the production of riboflavin in the triple mutant strain 10-fold (228 mg/liter).
Long-Term Survival of Pathogenic and Sanitation Indicator Bacteria in Experimental Biowaste Composts
Authors: Lemunier Mélanie , Francou Cédric , Rousseaux Sandrine , Houot Sabine , Dantigny Philippe , Piveteau Pascal , Guzzo Jean
Published: October 2005

For economic, agricultural, and environmental reasons, composting is frequently used for organic waste recycling. One approach to limiting the potential risk from bacterial food-borne illnesses is to ensure that soil amendments and organic fertilizers are disinfected. However, more knowledge concerning the microbiological safety of composted substrates other than sludge and manure is necessary. Experimental in-vessel biowaste composts were used to study the survival of seeded
Listeria monocytogenes
,
Salmonella enterica
subsp.
enterica
serotype Enteritidis, and
Escherichia coli
. Four organic waste mixtures, containing various proportions of paper and cardboard, fruits and vegetables, and green waste, were composted in laboratory reactors with forced aeration. The physicochemical and microbiological parameters were monitored for 12 weeks during composting. The survival of bacteria over a 3-month period at 25°C was assessed with samples collected after different experimental composting times. Strain survival was also monitored in mature sterilized composts. Nonsterile composts did not support pathogen growth, but survival of seeded pathogens was observed.
Salmonella
serovar Enteritidis survived in all composts, and longer survival (3 months) was observed in mature composts (8 and 12 weeks of composting). Mature biowaste composts may support long-term survival of
Salmonella
serovar Enteritidis during storage at room temperature.
E. coli
and
L. monocytogenes
survival was observed only in 4-week-old composts and never in older composts. Proper composting may prevent long-term survival of
E. coli
and
L. monocytogenes
. These results suggest that like composted sewage sludge or manure, domestic waste composts may support pathogen survival. Survival was not related to the physicochemical characteristics of the composts.
Use of Random and Saturation Mutageneses To Improve the Properties of
Thermus aquaticus
Amylomaltase for Efficient Production of Cycloamyloses
Authors: Fujii Kazutoshi , Minagawa Hirotaka , Terada Yoshinobu , Takaha Takeshi , Kuriki Takashi , Shimada Jiro , Kaneko Hiroki
Published: October 2005

Amylomaltase from
Thermus aquaticus
catalyzes intramolecular transglycosylation of α-1,4 glucans to produce cyclic α-1,4 glucans (cycloamyloses) with degrees of polymerization of 22 and higher. Although the amylomaltase mainly catalyzes the transglycosylation reaction, it also has weak hydrolytic activity, which results in a reduction in the yield of the cycloamyloses. In order to obtain amylomaltase with less hydrolytic activity, random mutagenesis was perfromed for the enzyme gene. Tyr54 (Y54) was identified as the amino acid involved in the hydrolytic activity of the enzyme. When Y54 was replaced with all other amino acids by site-directed mutagenesis, the hydrolytic activities of the mutated enzymes were drastically altered. The hydrolytic activities of the Y54G, Y54P, Y54T, and Y54W mutated enzymes were remarkably reduced compared with that of the wild-type enzyme, while those of the Y54F and Y54K mutated enzymes were similar to that of the wild-type enzyme. Introducing an amino acid replacement at Y54 also significantly affected the cyclization activity of the amylomaltase. The Y54A, Y54L, Y54R, and Y54S mutated enzymes exhibited cyclization activity that was approximately twofold higher than that of the wild-type enzyme. When the Y54G mutated enzyme was employed for cycloamylose production, the yield of cycloamyloses was more than 90%, and there was no decrease until the end of the reaction.
Concentrations of Pathogens and Indicators in Animal Feces in the Sydney Watershed
Authors: Cox Peter , Griffith Merran , Angles Mark , Deere Daniel , Ferguson Christobel
Published: October 2005

A fecal analysis survey was undertaken to quantify animal inputs of pathogenic and indicator microorganisms in the temperate watersheds of Sydney, Australia. The feces from a range of domestic animals and wildlife were analyzed for the indicator bacteria fecal coliforms andClostridium perfringensspores, the pathogenic protozoaCryptosporidiumandGiardia, and the enteric viruses adenovirus, enterovirus, and reovirus. Pathogen and fecal indicator concentrations were generally higher in domestic animal feces than in wildlife feces. Future studies to quantify potential pathogen risks in drinking-water watersheds should thus focus on quantifying pathogen loads from domestic animals and livestock rather than wildlife.
Factors Associated with the Presence of Coliforms in the Feed and Water of Feedlot Cattle
Authors: Sanderson Michael W. , Sargeant Jan M. , Renter David G. , Griffin D. Dee , Smith Robert A.
Published: October 2005

The objective of this study was to investigate coliform counts in feedlot cattle water and feed rations and their associations with management, climate, fecal material, and water
Escherichia coli
O157 using a cross-sectional study design. Coliform counts were performed on feed samples from 671 pens on 70 feedlots and on water samples from 702 pens on 72 feedlots in four U.S. states collected between May and August 2001. Management and climate factors were obtained by survey and observation. Month of sampling (higher in May and June), presence of corn silage in the ration (negative association), temperature of the feed 1 in. (ca. 2.5 cm) below the surface at the time of sampling (negative association), and wind velocity at the time of sampling (positive association) were significantly associated with log
10
coliform levels in feed. Month of sampling (lower in May versus June July and August), water pH (negative association), and water total solids (positive association) were significantly associated with log
10
water coliform levels. Coliform counts in feed and water were not associated with prevalence of
E. coli
O157 in cattle feces or water. Management risk factors must be interpreted with caution but the results reported here do not support the use of coliform counts as a marker for
E. coli
O157 contamination of feed or water.
Detection and Characterization of
Streptococcus thermophilus
Bacteriophages by Use of the Antireceptor Gene Sequence
Authors: Binetti Ana G. , Del Río Beatriz , Martín M. Cruz , Álvarez Miguel A.
Published: October 2005

In the dairy industry, the characterization of
Streptococcus thermophilus
phage types is very important for the selection and use of efficient starter cultures. The aim of this study was to develop a characterization system useful in phage control programs in dairy plants. A comparative study of phages of different origins was initially performed based on their morphology, DNA restriction profiles, DNA homology, structural proteins, packaging mechanisms, and lifestyles and on the presence of a highly conserved DNA fragment of the replication module. However, these traditional criteria were of limited industrial value, mainly because there appeared to be no correlation between these variables and host ranges. We therefore developed a PCR method to amplify VR2, a variable region of the antireceptor gene, which allowed rapid detection of
S. thermophilus
phages and classification of these phages. This method has a significant advantage over other grouping criteria since our results suggest that there is a correlation between typing profiles and host ranges. This association could be valuable for the dairy industry by allowing a rational starter rotation system to be established and by helping in the selection of more suitable starter culture resistance mechanisms. The method described here is also a useful tool for phage detection, since specific PCR amplification was possible when phage-contaminated milk was used as a template (detection limit, 10
5
PFU ml
−1
).
Role of thessuandseuGenes ofCorynebacterium glutamicumATCC 13032 in Utilization of Sulfonates and Sulfonate Esters as Sulfur Sources
Authors: Koch D. J. , Rückert C. , Rey D. A. , Mix A. , Pühler A. , Kalinowski J.
Published: October 2005

Corynebacterium glutamicumATCC 13032 was found to be able to utilize a broad range of sulfonates and sulfonate esters as sulfur sources. The two gene clusters potentially involved in sulfonate utilization,ssuD1CBAandssuI-seuABC-ssuD2, were identified in the genome ofC. glutamicumATCC 13032 by similarity searches. While thessugenes encode proteins resembling Ssu proteins fromEscherichia coliorBacillus subtilis, theseugene products exhibited similarity to the dibenzothiophene-degrading Dsz monooxygenases ofRhodococcusstrain IGTS8. Growth tests with theC. glutamicumwild-type and appropriate mutant strains showed that the clustered genesssuC,ssuB, andssuA, putatively encoding the components of an ABC-type transporter system, are required for the utilization of aliphatic sulfonates. InC. glutamicumsulfonates are apparently degraded by sulfonatases encoded byssuD1andssuD2. It was also found that theseugenesseuA,seuB, andseuCcan effectively replacessuD1andssuD2for the degradation of sulfonate esters. The utilization of all sulfonates and sulfonate esters tested is dependent on a novel putative reductase encoded byssuI. Obviously, all monooxygenases encoded by thessuandseugenes, including SsuD1, SsuD2, SeuA, SeuB, and SeuC, which are reduced flavin mononucleotide dependent according to sequence similarity, have SsuI as an essential component. Using real-time reverse transcription-PCR, thessuandseugene cluster was found to be expressed considerably more strongly during growth on sulfonates and sulfonate esters than during growth on sulfate.