bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of passive sonar to detect sound production and calculate population densities of penaeid shrimp in the Gulf of Mexico.
Authors: Berk Ilona M. , Evans William E. , Benson Robert H. , Duncan Michael E.
Published: October 2005

Past research concluded that nonstridulating pink shrimp (Penaeus duorarum) found in the Gulf of Mexico did not make sound in the sonic range, but might produce ultrasonic sound via friction between parts of the exoskeleton [W. R. Gehring, Sea Grant Bulletin ♯5 (1971)]. Recordings of ‘‘frying’’ noises over known penaeid shrimp beds led to speculation that the shrimp were mechanically producing the ‘‘frying’’ portion of the ambient noise, and that passive sonar might be used as a tool for penaeid shrimp detection and estimation of population densities [W. E. Evans, Acoustics Signature Catalog, 82–141 (1982)]. Sound production by nonstridulating white shrimp (Penaeus setiferus) of the Gulf of Mexico was studied using passive sonar. Video and hydrophone recordings were made of captive shrimp populations with known densities. Hydrophone recordings of wild populations were made pre- and postshrimp trawls, and trawl catch data were noted. Results showed that the captive shrimp produced detectable mechanical sound primarily via escape movements and possibly mastication. Initial comparison suggests that wild shrimp and captive shrimp sounds are similar. It is hoped that the final results of analysis will confirm that wild penaeid shrimp population density calculations are feasible using passive sonar data.
Intraspecific variation in the vocalizations of the willet Catoptrophorus semipalmatus.
Authors: Douglas Hector D.
Published: October 2005

The acoustical repertoire of the eastern willet was recorded at sites along the Atlantic seaboard using a Marantz portable cassette recording deck (model PMD 221), a Sennheiser microphone (model K3-U), and a 62-cm fiberglass parabolic recording dish. Associated behaviors were annotated on audio tape and in field notebooks. Call parameters were measured using a DSP Sona-Graph model 5500. Variation in call parameters was assessed within individuals, within populations, between geographical regions, and between subspecies using cross correlations and univariate and multivariate statistical methods. Sonograms, preliminary quantitative results and aural comparisons suggest relatively little structural variation in calls across large geographical regions. One notable exception in this pattern was observed at the subspecific level, and a hypothesis is advanced linking differences in ecology and environmental features to explain this divergence. Some intraindividual variation could be linked to hypothesized transitions in motivational states as indicated by incidental changes in behavior. Results suggest that vocal development in the willet is based upon innate templates. However, observations also suggest that these forms may be recombined to encode different information.
Objective analysis of song learning in birds: Toward automated techniques.
Authors: Anderson S. E. , Staicer C. A. , Inoue S. , Margoliash D.
Published: October 2005

It is demonstrated that indigo buntings sing bouts of ‘‘adult plastic’’ songs (APS) distinct from stereotyped songs (SS). Some distinguishing characteristics of APS include syllables of variable morphology and syllables not present in SS. The hypothesis that APS may play a role in adult song learning is tested by monitoring socially paired males housed together. Some yearlings changed their SS to more closely match their tutors’ SS, by replacing syllables or inserting new syllables. New syllables were developed in APS through transformation and combination of morphologically similar existing syllables, and syllables were transferred from APS into SS. To address the limitations of manual scoring of spectrographs, dynamic time warping (DTW) for template-based automated analysis of continuous recordings of birdsongs was evaluated. With laboratory recordings, the DTW algorithm employed identified syllables and syllable boundaries of SS and calls of indigo bunting and zebra finch with greater than 97% accuracy. APS constituents were identified with approximately 84% accuracy. Under these restricted recording conditions, DTW has general applicability to objective analysis of birdsongs, and dramatically decreases the effort required. Application of hybrid hidden Markov models may improve the performance for variable vocalizations such as APS, and under noisy conditions of field recordings.
Acoustic radiation by a rattling plate: Experimental and theoretical analysis.
Authors: Lee Karen J. , Grosh Karl
Published: October 2005

Rattle noise is directly tied to customers’ perceptions of product quality. The accurate and efficient prediction of this noise component remains an important and challenging area. Sound-pressure levels (SPLs) in the acoustic field of a rattling plate were measured experimentally and compared to predictions based on the plate’s equations of motion. The aluminum plate was hinged at one end and contacted a point at the other. Rattle was induced by exciting the plate supports using a shaker with a sinusoidal input. SPL measurements were made with a microphone at different points in the acoustic field. For the initial theoretical predictions, the plate was modeled as a rigid body and a closed-form solution was found for the linearized equations of motion to obtain the contact forces. The calculated force was used to generate the predicted plate vibration which, in turn, was used to predict the SPL in the acoustic field surrounding the plate. Later in the study, plate flexibility was added into the contact force model, and the effects of adding an increasing number of vibrational modes were studied. The experimental and theoretical data were compared in the time and frequency domains.
Advances in acoustic pyrometry.
Authors: Kleppe John A.
Published: October 2005

Instrumentation based on acoustic principles is finding widespread use in utility boiler applications. This paper describes how acoustic systems are currently being used to measure volumetric flow rate in large ducts and stacks for continuous emission monitoring system (CEMS) applications as well as for the measurement of high-temperature flue gases and boiler control. Acoustic pyrometry is a useful tool for the measurement of gas temperatures in the furnace and superheater regions in boilers. Results have shown that acoustic pyrometry is easy to apply, accurate, and noninvasive. Gas temperature measurements are provided and displayed on a continuous real-time basis for single path volumes in various furnace regions and for multiple path arrays in the furnace exit gas plane. The determination and presentation of isothermal maps of gas temperature provide a new tool for operation and maintenance diagnostics, not achievable by any other currently known method. Acoustic pyrometers are now being used to help identify and correct burner problems, slagging problems, and furnace overheating before these conditions can adversely affect operations.
Time capture method for improvements in absolute calibration of accelerometers by laser interferometry.
Authors: Wu Lixue
Published: October 2005

The measurement uncertainty in the absolute calibration of accelerometers using laser interferometry was reduced by a time capture method. Outputs of a photodetector and accelerometer were digitally sampled at a rate of 256k samples per second. Displacement amplitudes and accelerometer sensitivities were found from the sampled data. During data processing, a technique was used that decomposes a multivariable nonlinear optimization into a series of single-variable optimizations. This decomposition technique not only reduces the computational complexity but also avoids the convergence to local minima. Results of calibrations showed that the measurement uncertainty at the high-frequency end (800 Hz) for a small acceleration of 10 ms−2 was less than 0.9% at 95% confidence level. This time capture method can be applied to any time-variant (nonsinusoidal, nonperiodic) displacement measurement. With the above method, measurement requirements such as frequency stability and acceleration amplitude stability, can be less stringent. The effects of airborne noise and vibration can also be reduced.
A conical shock tube that simulates the heavyweight shock tests in MIL-S-901D.
Authors: Luker L. D. , Van Buren A. L.
Published: October 2005

Sonar transducers and related components mounted on the hulls of ships and submarines are subject to both inertial shock and acoustic pressure shock when a weapon explodes in the water near the vessel. Consequently, sonar transducers are required to pass an open-water explosive shock test using the floating shock platform (FSP) as specified in MIL-S-901D(NAVY). These tests are expensive, infrequent, and susceptible to erroneous results due to damage incurred in shipment of the transducers between the shock test site and the acoustic calibration facility. This paper describes the development of a conical shock tube (CST) facility at NUWC-USRD that is an inexpensive, rapid-turnaround alternative to open-water testing. CST tests are performed indoors in a closed, water-filled tube with a 25-cm-diam muzzle opening. The CST matches the peak pressures observed in the FSP test using only several grams of explosive. It also matches the axial motion experienced by the FSP in open-water tests. Both design criteria and experimental results are presented. [Work supported by NAVSEA.]
Sonar dome deflection and strain measurement system.
Authors: Covey Joel F. , Weaver Diane B. , Walker Jonathan B.
Published: October 2005

A multiplexed computer-controlled deflection and strain measurement system has been developed for use in performing at-sea data collection on a Naval surface ship sonar dome rubber window. The deflection of the window is measured at 128 points on its water-filled inner surface by an acoustic time-of-flight technique. At each point of interest a 2-cm-diam hemispherical acoustic transducer is pulsed at 110 kHz and the signal is received by an array of four similar transducers fixed to the ship’s sonar array. Ten different receiver arrays are used to allow for direct line-of-sight reception for each of the points of interest. The 85 strain sensors were built into the wire plies of the window by the manufacturer (B. F. Goodrich). The system records data from all 128 transducers, all strain sensors, as well as numerous environmental parameters at a rate of approximately 200 reading/s. The measurement system is nonobtrusive to normal ship sonar operations and performance. The data collected is being used in characterizing the behavior of these windows at high speeds and sea states and in the calibration of numerical experiments and window redesign efforts. [Work supported by NAVSEA.]
Measured in-water acoustic performance of 1-3 piezocomposite materials.
Authors: Howarth Thomas R.
Published: October 2005

A selection of different 1-3 piezocomposite materials has been fabricated and tested. Each of the 1-3 piezocomposite materials that will be presented was fabricated by the Material Systems Inc. of Littleton, MA. The materials selection includes variations in volume content of piezoceramic, types of piezoceramic, host matrix materials of varying compliances and air-voided microballoon content, as well as the use of types of cover plates on the radiating surfaces. The acoustic measurements were conducted at both the Lake Gem Mary lake facility and the Anechoic Test Facility 1 (ATF1) of the Underwater Sound Reference Detachment in Orlando, FL. The presentation will include comparisons of free-field voltage sensitivities (FFVS) and transmitting voltage response (TVR) as well as directivity patterns. The measurements from ATF1 will also show the effects of hydrostatic pressure and temperatures of 4 ° and 22 °C. The presentation will include a discussion of how specific 1-3 piezocomposite materials can be tailored to meet specific applications. [Work supported by Advanced Research Projects Agency and NSWC/Coastal Systems Station.]
Experimental evidence for maximum efficiency operation of a magnetostrictive transducer.
Authors: Calkins Frederick T. , Flatau Alison B.
Published: October 2005

Experimental broadband testing of a magnetostrictive transducer has been used to study the trade-off between operating for maximum efficiency and maximum output. Although the largest output, displacement or acceleration, is achieved at the resonant frequency, a greater operating efficiency is achieved at a frequency above resonance. An explanation for this phenomenon for general transducers via the theory of electroacoustics is reviewed [F. V. Hunt, Electroacoustics: The Analysis of Transduction, and Its Historical Background, Acoustical Society of America, Woodbury, NY (1982)]. This frequency of maximum efficiency is derived for a general electromagnetic transducer and shown graphically on a motional-impedance locus plot. An evaluation of the efficiency shows that the reactance, the imaginary component of the electrical impedance, can be ‘tuned’ to achieve maximum efficiency. For a magnetostrictive transducer the reactance tuning is related to reducing eddy losses. The effective permeability of the material is shown to decrease significantly after resonance, well below the nominal value at low frequency; thus operating in this frequency region results in a significant decrease in eddy current losses and hence a higher efficiency. Experimental results are provided to demonstrate the advantages of operating a transducer at the maximum efficiency frequency. [Work supported by NASA Graduate Student Research Program, NASA Langley.]
Analysis of tonpilz with flexing pistons.
Authors: Lubell Alan H. , Simon Ralph
Published: October 2005

The acoustic loading of each of the first six modes of a double piston piezoelectric stack-driven underwater acoustic transducer is found using Botman’s method [NAA report NA65H-1024, June 1965] revised with the use of the Helmholtz integral formulation of Chertok [J. Acoust. Soc. Am. 36, 1305–1313 (1964)]. Both self and mutual impedances are obtained and the admittance of each mode solved for. Finite element analysis is used to determine the mode parameters of the first 30 modes and the contribution to compliance loading of modes 7-30. Using symmetry, the eight-element stack is represented by a ten-mesh circuit that includes joint compliances, end piece masses, a distributed parameter representation of the stressbar, and the contact compliances between end pieces and pistons. Input impedance and total radiated power are computed for a wide range of frequencies. For joint compliance of the order of 0.25 E–10 M/N or less, a simpler stack model is found to be adequate.
Lecture demonstrations in acoustics.
Authors: Bell-Berti Fredericka , Everbach E. Carr , Hastings Mardi C. , Kuhl Patricia K. , Weisenberger Janet M.
Published: October 2005

A series of lecture demonstrations in acoustics will be given to high-school students from Indianapolis area high schools. Attendance and participation by meeting attendees are welcome.
Nonlinear surface wave propagation in crystals.
Authors: Hamilton M. F. , Il’inskii Yu. A. , Zabolotskaya E. A.
Published: October 2005

Elastic wave propagation along the free surface of a crystal differs from Rayleigh wave propagation in an isotropic solid. In particular, the phase speed and depth dependence vary with the direction of propagation with respect to the crystallographic axes, and the wave-vector component perpendicular to the surface is complex. Results from a theoretical investigation of nonlinear propagation along a free surface of a crystal are presented. The analysis is based on spectral equations that are derived with Hamiltonian formalism. The equations were integrated numerically to illustrate finite-amplitude distortion of a surface wave that is sinusoidal at the source. In one example, calculations based on published material properties are presented for surface wave propagation in KCl out to distances beyond where shock formation occurs. Waveform distortion associated with propagation along the [111] axis in KCl was found to be similar to that of Rayleigh waves in isotropic solids. However, for propagation along the [001] axis in KCl, energy transfer from the fundamental to the second harmonic component is very inefficient, and the waveform distortion was found to differ considerably from that of Rayleigh waves. [Work supported by NSF, ONR, and the Schlumberger Foundation.]
Propagation of finite-amplitude broadband noise.
Authors: Menounou Penelope , Blackstock David T.
Published: October 2005

Burgers’ equation is used to predict the effect of nonlinearity on the power spectral density of plane broadband noise traveling in a nondispersive thermoviscous fluid. The source signal is assumed to be stationary Gaussian noise, which, because of nonlinear propagation distortion, becomes non-Gaussian as it travels. As opposed to time-domain methods, the method presented here is based directly on the power spectral density of the signal, not the signal itself. The Burgers equation is transformed into an unclosed set of linear equations that describe the evolution of the joint moments of the signal. A method for solving the system of equations is presented. Only the evolution of appropriately selected joint moments needs to be calculated in order to predict the evolution of the power spectral density of the signal. The results are in good agreement with a time-domain code [Cleveland et al., J. Acoust. Soc. Am. 98, 2865(A) (1995)]. The method can be also applied when the source condition is a stationary, ergodic, and Gaussian stochastic process. [Work supported by NASA.]
Absorption of sound by noise in one dimension.
Authors: Larraza Andrés , Denardo Bruce
Published: October 2005

Experimental results are presented for the excess attenuation of mono- frequency waves in the presence of high-intensity noise in one dimension. The theory by Rudenko and Chirkin predicts a Gaussian attenuation of a weak signal in the presence of shockless noise, thus showing that in one dimension translational invariance has been broken. The theory is modified to incorporate wall losses providing, only then, excellent agreement with experiment. The agreement is shown as the frequency, noise level, and distance from the source are varied. In addition, the spectral intensity of the high-frequency tail of fully developed shockless noise is observed to be an f−3 power law in the frequency f, in accord with theory. This power law is a consequence of the far off equilibrium nature of the system. [Work supported by ONR.]
Nonlinearity versus diffraction within a focusing weak shock.
Authors: Piacsek Andrew A.
Published: October 2005

In a classic paper treating the propagation of weak shocks, Whitham elucidated the process by which nonlinear effects would prevent rays within a concave portion of a shock front from intersecting, thereby avoiding a folded wavefront and associated caustics [G. B. Whitham, J. Fluid Mech. 1, 290–318 (1956)]. Whitham’s analysis neglected the effects of diffraction arising from a finite shock thickness. When this length scale is small compared to that of the wavefront’s curvature, Whitham’s nonlinear correction to geometrical acoustics is a good model for the development of the shock front. When the length scales are comparable, as they are near the focal point, diffraction becomes important and acts both in conjunction with nonlinearity (to limit the shock amplitude) as well as against it (inhibiting the refraction of rays). Recent numerical studies [A. Piacsek, Ph.D. thesis, The Pennsylvania State University (1995)] indicate that the latter effect can lead to the formation of a folded wavefront, bounded by caustics, just as linear geometric theory predicts. The present paper addresses quantitatively how the relative importance of nonlinearity and diffraction (as represented by the shock amplitude, thickness, and wavefront curvature) determines the behavior of a focusing weak shock. [Work performed by the Lawrence Livermore National Laboratory under U. S. Department of Energy Contract No. W-7405-ENG-48.]
Generation of localized low-frequency vibrations by remote ultrasound sources.
Authors: Fatemi Mostafa , Greenleaf James F.
Published: October 2005

This paper presents a new method of inducing localized low-frequency acoustic energy in an object by remote sources. In this method two interacting high-power, high-frequency, ultrasound beams at two different frequencies are used. These beams are positioned to interact at the object’s surface (or any other impedance discontinuity inside the object). The result is a radiation force at the difference frequency, df, exerted in a small area defined by the beamwidths. Experiments are performed on a small steel needle and blocks of gelatin. To monitor the vibration, a high-frequency probing transducer is used in pulse echo mode with the beam aimed at the vibrating part of the object. This transducer shoots tone bursts at a rate much higher than df. Echoes are quadrature detected and the resulting in-phase and quadrature signals are recorded. These signals are used to calculate the phase of the returned echo which is shown to be proportional to the target displacement. In the experiments, the power beams were driven at 20 W each and df=10 Hz. Amplitude of the resulting vibrations were 5 μm for the gelatin block and 1.2 μm for the needle.
Nonlinear effects on acoustic field measurement in biomedical frequency range.
Authors: Ye S. G. , Gong X. F. , Liu X. Z.
Published: October 2005

It was shown that ultrasound propagation in media is accompanied with nonlinear phenomena and the nonlinear effects on the measurement of acoustic field cannot be neglected. A needle hydrophone was used to receive the signal in the acoustic field for further analysis and the radiation force method was used to measure the total output power of the transmitter. The case of emitting power was constant, the nonlinear phenomena were accumulated due to the distance between the transmitter, and the hydrophone increased from a few centimeter to less than 20 cm. With increasing distance between the transmitter and the hydrophone, the ultrasound energy was gradually transferred from fundamental frequency f0 to high harmonics. Using the spectrum analyzer, the dependence of f0 and nf0 (n=2,3,...) on the distance increased was measured. When the distance between the transmitter and the hydrophone was fixed, the nonlinear phenomena became stronger as the emitting power increased. The acoustic intensity of f0 was no longer linearly increased with the increased emitting power acoustic intensity, and the acoustic intensity of f0 would tend toward a saturation value. [Work supported by NSFC.]
Active acoustic stabilization of capillary bridges significantly beyond the Rayleigh limit: Experimental confirmation.
Authors: Marr-Lyon Mark J. , Thiessen David B. , Marston Philip L.
Published: October 2005

Liquid bridges between two solid surfaces have applications in low gravity such as the solidification of floating zones. Long bridges naturally become unstable to a symmetric mode by bulging near one end while the opposite end thins. For a cylindrical bridge in low gravity of radius R and length L, the slenderness S=L/2R has a natural (Rayleigh) limit of π beyond which the bridge breaks. It has been demonstrated that acoustic radiation pressure may be used in simulated low gravity to produce stable bridges significantly beyond the Rayleigh limit with S as large as 3.6. The bridge (PDMS mixed with a dense liquid) has the same density as the surrounding water bath containing an ultrasonic standing wave. Modulation can be used to excite specific bridge modes [Morse et al., Phys. Fluids 8, 3–5 (1996)]. The shape of our bridge is optically sensed and the ultrasonic drive is electronically adjusted such that the radiation stress distribution dynamically quenches the most unstable mode. This active control simulates passive stabilization suggested for low gravity [J. Acoust. Soc. Am. 97, 3377(A) (1995)]. Feedback increases the mode frequency in the naturally stable region. [Work supported by NASA.]
Acoustic sensing of the nonlinear dynamics of density stratified vortices.
Authors: Ezersky Alexander B. , Soustov Poul L. , Zobnin Alexander B.
Published: October 2005

Data on the nonlinear processes in an atmosphere and in the ocean may be obtained by means of remote acoustic sensing. The principal task is to use the data obtained in experiments for reconstruction of temperature, pressure, and velocity fields, and thus reconstruct the flow. Results of laboratory investigations of the potentialities of remote acoustic sensing of flows are presented. The scattering of sound at vortices behind a cylinder was explored. The temperature of the cores of the vortices formed as a boundary layer was detached from the heated cylinder was higher than that of the incident flow. The experiment was performed in a low-turbulence wind tunnel at flow velocities much lower than the sound velocity. It is shown that the characteristics of the scattered signal (indications of scattering and time spectra) may be used to determine vortex parameters such as vorticity, repetition rate, and spatial period, to estimate the temperature of vortex cores and the amount of the heat transferred, as well as to identify the processes of vortex merging and vortex core oscillations. Results of acoustic sensing are in a good agreement with theoretical estimates, direct measurements by a hot-wire anemometer, and data of experiments on vortex visualization.
AM detection with one- and two-tone modulators.
Authors: Sheft Stanley , Yost William A.
Published: October 2005

Psychometric functions were measured for detecting amplitude modulation (AM) of a wideband noise carrier that was either gated with the 400-ms modulator or was on continuously. AM rates were 5, 20, 80, and 2000 Hz. The functions were steepest at the 80-Hz AM rate and shallowest with 2-kHz AM. A linear regression of log d′ on 20 log m showed the slope of the functions ranging from 0.83 to 1.59 in the gated conditions and from 1.34 to 1.79 in the continuous conditions. The increase in function slope between the gated- and the continuous-carrier conditions was less than predicted by Laming’s model of sensory processing [D. Laming, Sensory Analysis (Academic, New York, 1986)]. AM detection ability was also measured with two-tone modulators centered at either 2 or 6.5 kHz. Modulator tones were separated by 5, 20, or 80 Hz. Performance with the two-tone modulators was often better than predicted by either the envelope rms or max/min value, especially with the tones centered at 6.5 kHz. This result is consistent with incorporation of a second nonlinearity into a model of auditory envelope detection, introducing intermodulation at the low-modulator beat rates. [Work supported by NIH.]
Effects of frequency, increment and decrement duration, and pedestal duration on the detection of increments and decrements in sinusoids.
Authors: Peters Robert W. , Moore Brian C. J.
Published: October 2005

Thresholds for detection of increments and decrements in level of sinusoidal signals were measured as a function of signal duration (10, 20, or 200 ms), pedestal duration before the signal (10, 200 ms, or pedestal on continuously) and frequency (250, 1000, and 4000 Hz). Pedestal duration was varied to study adaptation effects and signal duration was varied to study temporal integration. The sinusoids were presented in a background noise intended to mask spectral splatter. Seven normal-hearing subjects were used. Thresholds improved with increasing frequency and with increased duration for both increments and decrements. Increasing the pedestal duration before the increment from 10 to 200 ms generally improved the threshold for increment durations of 10 and 20 ms but not for an increment duration of 200 ms. When the pedestal was on continuously, distinct adaptation occurred at 4000 Hz; the pedestal appeared to fade away. However, this did not greatly affect increment thresholds, except for a slight improvement for the increment duration of 200 ms. Decrement thresholds generally became worse when the pedestal was on continuously. The results are discussed in terms of the effects of adaptation and temporal integration.
Masking additivity in an excitation-pattern model.
Authors: Espinoza-Varas B.
Published: October 2005

An excitation-pattern model [Moore and Glasberg, Hear. Res. 28, 209–225 (1987)] was used to predict the masking additivity of two simultaneous sinusoidal maskers. The prediction relies on the assumption that masked threshold is reached when the addition of the signal to the masker produces a critical difference in the masker excitation pattern (EP) at any center frequency (the critical EP difference is termed criterion EPD). For equally effective maskers, masking additivity was assumed be equal to the difference between two signal levels: The level that produces the criterion EPD with the combination of maskers minus the level that produces the criterion EPD with the individual maskers. Excitation-pattern predictions of masking additivity were obtained for signal frequencies of 500, 1000, and 5000 Hz, each masked by two sinusoidal maskers symmetrically placed about the signal frequencies; maskers frequencies within and outside the signal ERB were considered. The masking additivity predicted by the EP model is compared to that predicted by the modified power law model [Humes et al., J. Acoust. Soc. Am. 83, 188–202 (1988)], and to masking-additivity data [Lutfi, J. Acoust. Soc. Am. 73, 262–267 (1983)].
Processing transitions in a band-widening experiment.
Authors: Berg Bruce G. , Southworth Curt , Branstetter Brian K.
Published: October 2005

Literature suggests that in the absence of single-channel level information, discriminations of narrow-band sounds are temporally based, whereas discriminations of wideband sounds rely on across-channel level comparisons. The transition between processes is investigated using a band-widening paradigm. Thresholds are estimated for increments in the intensity of the central tone of a band of equal intensity, random phase tones evenly separated in frequency (parametrically varied between 10 and 160 Hz). A 20-dB roving-level procedure degrades overall-level information. Uniformly distributed frequency shifts of the complex over a 100-Hz range degrade pitch cues. As the number of tones is increased, thresholds increase up to a certain bandwidth, after which thresholds decrease or remain constant. It is proposed that these breakpoints in threshold functions represent a transition from temporal to spectral discrimination processes. The mean ratio of breakpoints to center frequencies of 500, 1000, 2000, and 4000 Hz is approximately 0.4. Regarding individual differences, a significant positive correlation exists between breakpoints and thresholds in a wideband profile analysis task. [Work supported by ONR.]
Effects of wind velocity fluctuations on the statistical moments of plane and spherical sound waves in the turbulent atmosphere with the Gaussian correlation function of wind velocity fluctuations.
Authors: Ostashev V. E. , Goedecke G. , Noble John M.
Published: October 2005

It is quite often assumed in the theories of waves in random media that medium inhomogeneities have a Gaussian correlation function. Equations for the main statistical moments of plane and spherical sound waves propagating in a medium with temperature fluctuations are well known in the literature. Among these statistical moments are the following: the mean sound field, the variances and correlation functions of log-amplitude and phase fluctuations, and the transverse coherence function. The present paper deals with a derivation of equations for these statistical moments for the case of plane and spherical wave propagation in the atmosphere with wind velocity fluctuations. It is shown that the derived equations can differ not only quantitatively but also qualitatively from analogous equations for the case of sound propagation in the atmosphere with temperature fluctuations even if the wind velocity and temperature fluctuations make the same contributions to the variance of the acoustical refractive-index fluctuations. The results obtained are generalized to the case of sound propagation in an arbitrary medium (for example, for sound propagation in the ocean with current fluctuations). [This material is based upon Work supported by the U.S. Army Research Office under Contract No. DAAH04-95-1-0593.]
Sound radiation from a centrifugal blower in a free field.
Authors: Su Shigong , Wu Sean F. , Hsi Morris Y.
Published: October 2005

A new formulation for predicting sound radiation from a centrifugal blower in a free field is derived. The fundamental difference between the present formula and the previously derived ones is that the former considers a new monopole, while the latter assumes the dipole as the primary source. For an axial flow fan or a rotor blade under steady flow condition, the usual monopole source proportional to (ρo∂vn/∂t) is negligible [Siddon, J. Acoust. Soc. Am. 53, 616–633 (1973)]. However, for a centrifugal blower the monopole source induced by Coliolis acceleration (ω×vt) cannot be neglected because of a large inclination angle of the impeller. With the inclusion of this monopole source term, the formula yields a dependence of the radiated sound power on the fourth power of the azimuthal speed, which agrees with the experimental data [Maling, J. Acoust. Soc. Am. 35, 1556–1564 (1963); Neise, J. Sound Vib. 43, 61–75 (1975)]. The resulting formula can be used to derive the radiated sound power spectrum using the turbulence correlation curve. The spectra thus obtained are compared with the measured ones from a centrifugal blower mounted in a free field. A favorable agreement is obtained in all test cases.
The consonantal properties of the unrounded high-mid back vowel /■/ in Mandarin Chinese.
Authors: Zhang Jie
Published: October 2005

The vowel /■/ in Mandarin has traditionally been documented as a simple vowel although it has been noticed to involve more complicated articulator movements in its production than a monophthong. Three male speakers of Beijing Mandarin were recorded for an acoustic study of this vowel. The frequency and energy values of F1 through F4 of the beginning part (around 20 ms), the first quarter, and the rest of the vowel were measured from the spectrogram and LPC using CSL. Results of two-tail paired t tests show that the first quarter of the vowel has significantly weaker energy in F2 through F4 than the rest of the vowel at p=0.05 level, indicating approximantlike properties in this part. Also, the initial 20 ms of the vowel has higher F1 and lower F2 than the following part, indicating a possible pharyngeal constriction. So phonetically, /■/ consists of a very short pharyngeal approximant [■], a velar approximant [■‖], and a real vowel [■] in sequence. This phonetic characteristic accounts for the fact that glottal stop insertion before a syllable-initial /■/ is much less likely than that before a real onsetless monophthong /a/, but patterns with that before a syllable-initial /wo/.
Stationary phase for summations
Authors: Graham W. R.
Published: October 2005

The geometrical, or ‘‘ray’’ approach to high-frequency wave fields is well known. Using the method of stationary phase, the ray terms can be shown to arise as the leading-order solution of an exact integral formulation for the wave field. However, this analysis cannot be applied directly when the problem geometry is cylindrical or circular, and the integral is replaced by a summation. Instead the sum must first be converted into an integral by the rather cumbersome means of a Watson transformation. Here an intuitive and concise extension of the method of stationary phase, which may be applied directly to summations, is presented, and the validity of the approach is confirmed using the Watson transformation.
The role of job strain on return to work after carpal tunnel surgery
Authors: Gimeno D , Amick B C , Habeck R V , Ossmann J , Katz J N
Published: October 2005

Aims:To examine the impact of job strain (that is, high psychological job demands and low job control) on return to work and work role functioning at two months, six months, or both, following carpal tunnel release surgery.

Methods:A community based cohort of carpal tunnel syndrome (CTS) patients from physician practices was recruited between April 1997 and October 1998 throughout Maine (USA). 128 patients at two months and 122 at six months completed all relevant questions. A three level outcome variable indicated whether patients had: (1) returned to work functioning successfully, (2) returned to work functioning with limitations, or (3) not returned to work for health reasons. Two job strain measures were created: one, by combining psychological job demands and job control; and two, by dividing demands by control. Ordinal logistic regression was used to identify predictors of the three level work outcome variable.

Results:After adjustment, workers with high demands and high control (active work) were less likely to successfully return to work (OR = 0.22; p = 0.014) at two months. Having a job with higher demands than job control (high strain) predicted not returning to work or returning to work but not successfully meeting job demands (OR = 0.14; p = 0.001), at six months.

Conclusions:The findings underscore the role of psychosocial work conditions, as defined by the Karasek demand-control model, in explaining a worker’s return to work. Clinicians, researchers, and employers should consider a multidimensional and integrative model of successful work role functioning upon return to work. Moreover, since the evidence of the effects of work process changes on the reduction of CTS is very scarce, these findings point to the opportunity for collaborative workplace interventions to facilitate successful return to work.
Agricultural pesticide use and risk of glioma in Nebraska, United States
Authors: Lee W J , Colt J S , Heineman E F , McComb R , Weisenburger D D , Lijinsky W , Ward M H
Published: October 2005

Background:To evaluate the risk of the adult glioma associated with farming and agricultural pesticide use, the authors conducted a population based case control study in eastern Nebraska.

Methods:Telephone interviews were conducted with men and women diagnosed with gliomas (n = 251) between 1988 and 1993 and controls (n = 498) randomly selected from the same geographical area. Unconditional logistic regression was used to calculate adjusted odds ratios (ORs) for farming and for use of individual and chemical classes of insecticides and herbicides, including pesticides classified as nitrosatable (able to form N-nitroso compounds upon reaction with nitrite). Non-farmers were used as the reference category for all analyses.

Results:Among men, ever living or working on a farm and duration of farming were associated with significantly increased risks of glioma (⩾55 years on a farm OR = 3.9, 95% CI 1.8 to 8.6); however, positive findings were limited to proxy respondents. Among women, there were no positive associations with farming activities among self or proxy respondents. Specific pesticide families and individual pesticides were associated with significantly increased risks among male farmers; however, most of the positive associations were limited to proxy respondents. For two herbicides and three insecticides, use was positively associated with risk among both self and proxy respondents. Based on a small number of exposed cases, ORs were significantly increased for the herbicides metribuzin (OR = 3.4, 95% CI 1.2 to 9.7) and paraquat (OR = 11.1, 95% CI 1.2 to 101), and for the insecticides bufencarb (OR = 18.9, 95% CI 1.9 to 187), chlorpyrifos (OR = 22.6, 95% CI 2.7 to 191), and coumaphos (OR = 5.9, 95% CI 1.1 to 32).

Conclusion:The authors found significant associations between some specific agricultural pesticide exposures and the risk of glioma among male farmers but not among female farmers in Nebraska; however, most of the positive associations were limited to proxy respondents. These findings warrant further evaluation in prospective cohort studies where issues of recall bias are not a concern.
A prospective cohort study among new Chinese coal miners: the early pattern of lung function change
Authors: Wang M-L , Wu Z-E , Du Q-G , Petsonk E L , Peng K-L , Li Y-D , Li S-K , Han G-H , Atffield M D
Published: October 2005

Aims:To investigate the early pattern of longitudinal change in forced expiratory volume in 1 second (FEV1) among new Chinese coal miners, and the relation between coal mine dust exposure and the decline of lung function.

Methods:The early pattern of lung function changes in 317 newly hired Chinese underground coal miners was compared to 132 referents. This three year prospective cohort study involved a pre-employment and 15 follow up health surveys, including a questionnaire and spirometry tests. Twice a month, total and respirable dust area sampling was done. The authors used a two stage analysis and a linear mixed effects model approach to analyse the longitudinal spirometry data, and to investigate the changes in FEV1 over time, controlling for age, height, pack years of smoking, mean respirable dust concentration, the room temperature during testing, and the group×time interaction terms.

Results:FEV1 change over time in new miners is non-linear. New miners experience initial rapid FEV1 declines, primarily during the first year of mining, little change during the second year, and partial recovery during the third year. Both linear and quadratic time trends in FEV1 change are highly significant. Smoking miners lost more FEV1 than non-smokers. Referents, all age less than 20 years, showed continued lung growth, whereas the miners who were under age 20 exhibited a decline in FEV1.

Conclusion:Dust and smoking affect lung function in young, newly hired Chinese coal miners. FEV1 change over the first three years of employment is non-linear. The findings have implications for both methods and interpretation of medical screening in coal mining and other dusty work: during the first several years of employment more frequent testing may be desirable, and caution is required in interpreting early FEV1 declines.
Erythroid-specific 5-aminolevulinate synthase protein is stabilized by low oxygen and proteasomal inhibition
Authors: Abu-Farha Mohamed , Niles Jacques , Willmore William G
Published: October 2005

5-aminolevulinate synthase (ALAS; E.C. 2.3.1.37) catalyzes the first and rate-limiting step of heme synthesis within the mitochondria. Two isozymes of ALAS, encoded by separate genes, exist. ALAS1 is ubiquitously expressed and provides heme for cytochromes and other hemoproteins. ALAS2 is expressed exclusively in erythroid cells and synthesizes heme specifically for haemoglobin. A database search for proteins potentially regulated by oxygen tension revealed that ALAS2 contained a sequence of amino acids (LXXLAP where L is leucine, X is any amino acid, A is alanine, and P is proline) not occurring in ALAS1, which may be hydroxylated under normoxic conditions (21% O2) and target the enzyme for ubiquitination and degradation by the proteasome. We examined protein turnover of ALAS2 in the presence of cycloheximide in K562 cells. Normoxic ALAS2 had a turnover time of approximately 36 h. Hypoxia (1% O2) and inhibition of the proteasome increased both the stability and the specific activity of ALAS2 (greater than 2- and 7-fold, respectively, over 72 h of treatment). Mutation of a key proline within the LXXLAP sequence of ALAS2 also stabilized the protein beyond 36 h under normoxic conditions. The von Hippel-Lindau (vHL) protein was immunoprecipitated with FLAG epitope-tagged ALAS2 produced in normoxic cells but not in hypoxic cells, suggesting that the ALAS2 is hydroxylated under normoxic conditions and targeted for ubiquitination by the E3 ubiquitin ligase system. ALAS2 could also be ubiquitinated under normoxia using an in vitro ubiquitination assay. The present study provides evidence that ALAS2 is broken down under normoxic conditions by the proteasome and that the prolyl-4-hydroxylase/vHL E3 ubiquitin ligase pathway may be involved.Key words: erythroid-specific 5-aminolevulinate synthase, hypoxia, hydroxylation, prolyl-4-hydroxylases, E3 ubiquitin ligases, von Hippel-Lindau protein, proteasome.
Beyond apoptosis: nonapoptotic cell death in physiology and disease
Authors: Hetz Claudio A , Torres Vicente , Quest Andrew F.G
Published: October 2005

Apoptosis is a morphologically defined form of programmed cell death (PCD) that is mediated by the activation of members of the caspase family. Analysis of death-receptor signaling in lymphocytes has revealed that caspase-dependent signaling pathways are also linked to cell death by nonapoptotic mechanisms, indicating that apoptosis is not the only form of PCD. Under physiological and pathological conditions, cells demonstrate a high degree of flexibility in cell-death responses, as is reflected in the existence of a variety of mechanisms, including necrosis-like PCD, autophagy (or type II PCD), and accidental necrosis. In this review, we discuss recent data suggesting that canonical apoptotic pathways, including death-receptor signaling, control caspase-dependent and -independent cell-death pathways.Key words: apoptosis, necrosis, nonapoptotic programmed cell death, death receptors, ceramides.
Inhibition of colony formation by mouse mammary cancer cells co-cultured with early embryonic cells
Authors: Vitou Con K , Li Xiaoming , Mukherjee Barid
Published: October 2005

Mammary cancer cells from C3H/HeOUJ mice fail to form colonies when grown on monolayers of cells from 9- and 10-d mouse embryos but not on those from 11- and 12-d-old embryos.Key words: mammary cancer, embryonic cells, diffusible factors.
Helianthus tuberosus agglutinin directly induces neutrophil migration, which can be modulated/inhibited by resident mast cells
Authors: Alencar Veruska B.M , Brito Gerly A.C , Alencar Nylane M.N , Assreuy Ana M.S , Pinto Vicente P.T , Teixeira Edson H , Souza Emmanuel P , Debray Henri , Ribeiro Ronaldo A , Cavada Benildo S
Published: October 2005

We investigated the effect of Helianthus tuberosus agglutinin (HTA) on neutrophil migration in vivo and in vitro. The role of resident cells in this effect was analyzed. Peritonitis was induced by injecting stimuli into rat (150–200 g) peritoneal cavities, and in vitro neutrophil chemotaxis was performed using a Boyden microchamber. HTA (80, 200, or 500 µg/mL per cavity) induced significant in vivo neutrophil migration (p < 0.05); in vitro assays showed that this lectin also induced neutrophil chemotaxis, an effect inhibited by the incubation of lectin associated with α-D(+)-mannose, its specific binding sugar. Depletion of the resident-cell population by peritoneal lavage did not alter HTA-induced neutrophil migration (200 µg/mL per cavity). The opposite strategy, increasing peritoneal macrophages by intraperitoneally injecting rats with thioglycollate, did not enhance the neutrophil migration produced by HTA (200 µg/mL per cavity). In addition, injection of supernatant from HTA-stimulated macrophage culture (300 µg/mL) into rat peritoneal cavities did not induce neutrophil migration. However, reduction of the peritoneal mast-cell population potentiated the neutrophil migration (p < 0.05) induced by HTA (200 µg/mL per cavity). Lectin from H. tuberosus has a direct neutrophil chemotatic effect that is modulated by mast cells.Key words: lectins, inflammation, Helianthus tuberosus, neutrophil migration.