bluuebunny/crossref_metadata_2025 huggingface dataset:
The transition matrix for acoustic and elastic wave scattering in prolate spheroidal coordinates
Authors: Hackman Roger H.
Published: October 2005

A spheroidal-coordinate-based transition matrix is derived for acoustic and elastic wave scattering. The formalism is based on Betti’s third identity and an appropriately chosen set of vector spheroidal basis functions. Transition matrices are obtained for the scattering from an elastic inclusion in an elastic medium and in an inviscid fluid.
Acoustical wave propagation in cylindrical ducts: Transmission line parameter approximations for isothermal and nonisothermal boundary conditions
Authors: Keefe Douglas H.
Published: October 2005

Approximate expressions are given for the characteristic impedance and propagation wavenumber for linear acoustic transmission through a gas enclosed in a rigid cylindrical duct. These expressions are most complicated in the transition zone where the thermoviscous boundary layers are on the order of the tube radius. The approximations are accurate to within 1% for all frequencies and tube diameters except within the transition zone where the approximations are accurate to within 10%. A simple modification of the transmission line parameters is presented for the case where the tube walls are nonisothermal.
A temperature correlation for the radiation resistance of a thick-walled circular duct exhausting a hot gas
Authors: Mahan J. R. , Cline J. G. , Jones J. D.
Published: October 2005

It is often useful to know the radiation impedance of an unflanged but thick-walled circular duct exhausting a hot gas into relatively cold surroundings. The reactive component is shown to be insensitive to temperature, but the resistive component is shown to be temperature dependent. A temperature correlation is developed permitting prediction of the radiation resistance from a knowledge of the temperature difference between the ambient air and the gas flowing from the duct, and a physical basis for this correlation is presented.
Frequency domain method for the prediction of the ultrasonic field patterns of pulsed, focused radiators
Authors: Cobb Wesley N.
Published: October 2005

A theoretical model is presented which can be used to calculate the pressure field patterns of pulsed, focused ultrasonic radiators in attenuating and nonattenuating media. Pressure pulses are calculated by superimposing continuous wave solutions at discrete frequencies. Due to the speed of the method, time signals can be calculated at many positions in the transducer beam in a reasonable amount of time. To test the model, theoretical predictions for the pressure signals are compared to hydrophone measurements for a conventional diagnostic transducer. In addition, signal envelopes are studied in order to determine the effects of attenuation and dispersion on the imaging characteristics of a focused radiator. This work may have significant application to the design of transducers for specific imaging purposes or to the analysis of the imaging process.
An experimental study of interaction between surface waves and a surface breaking crack
Authors: Yew C. H. , Chen K. G. , Wang D. L.
Published: October 2005

The interaction between surface waves and a surface breaking crack is studied experimentally. In this study, the surface wave is generated by dropping a small ball on the long side of a large plate. The wave motions are monitored on both sides of the crack with a pair of piezoelectric transducers. Upon analyzing the results, we have found that: (1) the arrival time of different wave components to the recording transducer placed on the forward side of the crack may be estimated by regarding the crack tip as a buried source to each impinging wave components; and (2) the depth of the crack may be estimated by comparing the amplitude spectra of the wave motions recorded on both sides of the crack.
Responses of pigeon vestibular nerve fibers to sound and vibration with audiofrequencies
Authors: Wit H. P. , Bleeker J. D. , Mulder H. H.
Published: October 2005

Single unit recordings were made from the nerve branch innervating the crista in the horizontal semicircular canal of a pigeon. The vestibular organ was either stimulated with sound through the ear canal or with a vibrator in contact with the membraneous ampulla roof. Units responding to sound or vibration showed tuning with a best frequency of approximately 0.7 kHz. The average low-frequency slope of the tuning curves is −16 dB/oct; the average high-frequency slope 20 dB/oct. The threshold amplitude for vibrator stimulation is 30 nm. This value comes close to the calculated threshold value for cupula deflection in the human semicircular canal.
Dependence of post-masking on masker duration and its relation to temporal effects in loudness
Authors: Zwicker Eberhard
Published: October 2005

Temporal masking of tones by noise was investigated using a post- (forward-) masking paradigm. The masker level and duration were varied. For every masker level employed, the rate of decay of masking was found to depend on the duration of the masker. Specific loudness values were computed from the forward masking functions and an electronic device which simulates these loudness functions is presented. In the simulation, a series of integrators or a single integration with one long time constant was utilized. The effect of the proposed integrators on loudness meters is discussed.
Comparison of dBA and ISO ratings in assessing sound isolation
Authors: Moreno-Arranz Antonio , Pfretzschner Jaime , Zaragoza Julián G.
Published: October 2005

This work deals with the correlation existing between the ISO index Rw for global evaluation of the isolation of walls and partitions and the so-called dBA index. This study, carried out over 86 actual walls, with a fairly regular distribution in the interval 20≤Rw≤70, leads to a correlation between both indices given by the expression I(dBA)=−0.6+0.98 Rw. As the chosen walls include most types of insulation curves, the authors state the equivalence between both indices in assessing acoustic isolation. Some experimental advantages of dBA ratings are also discussed.
Application of Twersky’s multiple scattering formalism to a dense suspension of elastic particles in water
Authors: Ma Y. , Varadan V. K. , Varadan V. V.
Published: October 2005

Acoustic wave propagation through a dense suspension of solid elastic particles in water is studied. The particles in suspension have a size distribution and their relative positions are described by a pair-correlation function. Twersky’s multiple scattering formalism is employed to obtain new analytical expressions for the phase velocity and coherent attenuation of a wide range of concentrations. Numerical results presented are of interest in the study of marine sediments.
Linear inviscid wave propagation in a waveguide having a single boundary discontinuity: Part II: Application
Authors: Thompson Charles
Published: October 2005

The method of match asymptotic expansions MMAE, is used to analyze wave propagation in two problem geometries. The acoustic pressure is evaluated for a waveguide having a single discontinuity in wall slope and a waveguide having a right-angle bend. A two-port representation of the fluid motion across the discontinuity for each problem is tabulated. A uniformly valid expression for the pressure for each problem is given.
Tests for nonstationarity
Authors: Tsao Y. H.
Published: October 2005

Most practical random processes are more or less nonstationary. The concept of stationarity appears to be merely a mathematical model. The question then is how to decide the ‘‘degree’’ of nonstationarity underlined in a given time series. This report explains how and why estimated evolutionary spectra of the time series can be used to test the nonstationarity for the random processes; the methods are essentially the modification and extension of Priestley’s evolutionary spectrum test technique. Various test models are further proposed in this paper including ‘‘two-way’’ and ‘‘three-way’’ tests using both discrete (or equispaced) frequency and/or frequency bands. The techniques developed are applied to both synthetic and practical acoustic data captured from aircraft fly-over events.
Constructing an imaging operator to enhance resolution
Authors: Lee Hua , Wade Glen
Published: October 2005

Constructing a real-time high-resolution imaging operator has been one of the most important objectives in image reconstruction. It is especially desirable to holographic, tomographic, and synthetic aperture radar systems with limited detection apertures. This paper introduces a method of constructing such an operator by using the step size generated from the steepest descent algorithm to improve the resolution of backward-projected images. With this operator we can overcome resolution limitations due to small-sized apertures and it is not necessary to go through tedious computations as in the case with iterative algorithms.
Spatial coherence of multipath underwater acoustic transmission: An experiment at two frequencies concurrently
Authors: Broek H. W. , Tom C.
Published: October 2005

Measurements were made of the fluctuations in amplitude and spatial coherence of acoustic wavefronts transmitted through the deep ocean at two frequencies concurrently, 114 and 400 Hz. The signals were generated by a ship-suspended souce at 1000-ft depth and received over two ranges, 130 and 145 nmi, on a string of five bottomed receivers laid horizontally on a deep-water slope at about 5000-ft depth. The receiver spacing varied from 500–2500 ft. Amplitude fluctuations were found to differ significantly at receiver separations of 500 ft and appeared unrelated at separations of 2000 ft or more. For multipath transmission, unlike single-path transmission, the relative phase fluctuations between given receiver pairs were not proportional to frequency, and phase coherence at a given receiver separation was generally less than for single-path transmission. Coherence at 145 nmi was almost as good as for single path, presumably because ray-tracing predicts a dominant path and because the phase measurements were averaged over 10 s, and thereby discriminated against frequency modulation effects by the sea surface. Thus frequency resolution and time resolution of the experiment are as important to the results as range, frequency, and receiver separation. Poorer coherence at 130 nmi is tentatively attributed to lack of a dominant arrival at 114 Hz, and near-surface refractions at both frequencies.
Frequency and intensity difference limens for harmonics within complex tones
Authors: Moore Brian C. J. , Glasberg Brian R. , Shailer Michael J.
Published: October 2005

A two-interval, two-alternative forced choice task was used to estimate frequency difference limens (DLs) for individual harmonics within complex tones, and DLs for the periodicity (i.e., number of periods per s) of the whole complexes. For complex tones with equal-amplitude harmonics, the DLs for the lowest harmonics were small (less than one percent). The DLs increased rather abruptly around the fifth to seventh harmonic. The highest harmonic in each complex was also well discriminated, and the discriminability of a single high harmonic was markedly improved by increasing its level relative to the other components. The DL for a complex tone was generally smaller than the frequency DL of its most discriminable component. The DL for a complex was found to be predictable from the DLs of the harmonics comprising the complex, using a formula derived by Goldstein [J. Acoust. Soc. Am. 54, 1496–1516 (1973)] from his optimum processor theory for the formation of the pitch of complex tones. The DL for a complex is sometimes primarily determined by high harmonics, such as the highest harmonic, or a harmonic whose level exceeds that of adjacent harmonics. We also measured intensity DLs for individual harmonics within complex tones. The intensity DLs were smallest for low harmonic numbers, and for the highest harmonic in a complex. An excitation-pattern model was used to determine whether the frequency DLs of harmonics within complex tones could be explained in terms of place mechanisms, i.e., in terms of changes in the amount of excitation at appropriate frequency places. We conclude that place mechanisms are not adequate, and that information about the frequencies of individual harmonics is probably carried in the time patterning of neural impulses.
Sinusoidal and noise maskers in simultaneous and forward masking
Authors: Weber Daniel L. , Patterson Roy D.
Published: October 2005

We compare psychophysical tuning curves obtained with sinusoidal and narrow-band (50-Hz wide) noise maskers in both simultaneous and forward masking. In one experiment, we examine the effects of different combinations of duration and intensity of the 1-kHz sinusoidal signal. In a second experiment, we compare tuning curves obtained with a sinusoidal signal to those obtained with a noise signal. In both experiments, a narrow-band noise is a more effective simultaneous masker than a sinusoid for masker frequencies near the signal frequency. We argue that this is probably due to the use of different detection cues in the presence of sinusoidal and noise maskers, and that the greater masking produced by the noise is not simply due to its greater variability. As observed in other studies, tuning curves are narrower in forward masking than in simultaneous masking.
A method for the generation of broadband acoustic transmissions
Authors: Holly Arthur C.
Published: October 2005

This paper reviews a technique for the generation of broadband acoustic transmissions. Wiener (least-squares) filtering is applied to the problem of precompensating the transducer driving waveform so that the subsequent acoustic pulse has a broadband nature. Experimental results show that a transducer having two resonance peaks at 9 and 17 kHz, each having bandwidths of about 2.5 kHz, may be compensated to have less than 3.5-dB ripple in the transmitting frequency response from 7 to 37 kHz.
Vibration and stability of orthotropic circular cylindrical shells subjected to axial load
Authors: Yamada Gen , Irie Toshihiro , Tsushima Mitsuo
Published: October 2005

An analysis is presented for the vibration and stability of an orthotropic circular cylindrical shell subjected to an axial static load by use of the transfer matrix approach. The applicability of the thin-shell theory is assumed, and the governing equations of free vibration of the shell are written in a matrix differential equation by using the transfer matrix of the shell. Once the matrix has been determined by a solution to the equation, the natural frequencies and the critical loads are calculated numerically in terms of the elements of the matrix for a given set of boundary conditions at the edges. This method is applied to orthotropic circular cylindrical shells simply supported at the edges, and the effects of the length ratio, orthotropy, and axial load on the vibration and stability are studied.
Interaural intensity discrimination: Insensitivity at 1000 Hz
Authors: Grantham D. Wesley
Published: October 2005

Recent data from three laboratories have replicated Mills’ [J. Acoust. Soc. Am. 32, 132–134 (1960)] finding that interaural intensity discrimination is relatively poorer for tones of 1000 Hz than for tones of either higher or lower frequencies. To get a finer look at this frequency effect, interaural intensity difference thresholds were obtained from four subjects for tones of several frequencies around 1000 Hz. An adaptive two-interval forced-choice procedure was employed, in which the overall intensity of the signals was varied randomly in order to prevent subjects from listening to monaural loudness changes. Despite large intersubject differences in overall sensitivity to interaural intensity differences, all four subjects showed a local peak in their threshold functions at or near 1000 Hz. This curious ‘‘1000-Hz effect’’ might be explained by imagining that an interaural intensity comparator operates more efficiently as frequency increases, but that a peripheral interaural intensity difference to interaural-time difference conversion contributes to laterality judgments for low-frequency tones, thus acting to lower thresholds again for frequencies below 1000 Hz.
Speech recognition in a special case of low-frequency hearing loss
Authors: Van Tasell Dianne J. , Turner Christopher W.
Published: October 2005

Recognition of speech stimuli consisting of monosyllabic words, sentences, and nonsense syllables was tested in normal subjects and in a subject with a low-frequency sensorineural hearing loss characterized by an absence of functioning sensory units in the apical region of the cochlea, as determined in a previous experiment [C. W. Turner, E. M. Burns, and D. A. Nelson, J. Acoust. Soc. Am. 73, 966–975 (1983)]. Performance of all subjects was close to 100% correct for all stimuli presented unfiltered at a moderate intensity level. When stimuli were low-pass filtered, performance of the hearing-impaired subject fell below that of the normals, but was still considerably above chance. A further diminution in the impaired subject’s recognition of nonsense syllables resulted from the addition of a high-pass masking noise, indicating that his performance in the filtered quiet condition was attributable in large part to the contribution of sensory units in basal and midcochlear regions. Normals’ performance was also somewhat decreased by the masker, suggesting that they also may have been extracting some low-frequency speech cues from responses of sensory units located in the base of the cochlea.
The role of release bursts in the perception of [s]-stop clusters
Authors: Repp Bruno H.
Published: October 2005

The role of the release burst as a cue to the perception of stop consonants following [s] was investigated in a series of studies. Experiment 1 demonstrated that silent closure duration and burst duration can be traded as cues for the ‘‘say’’–‘‘stay’’ distinction. Experiment 2 revealed a similar trading relation between closure duration and burst amplitude. Experiments 3 and 4 suggested, perhaps surprisingly, that absolute, not relative, burst amplitude is important. Experiment 5 demonstrated that listeners’ sensitivity to bursts in a labeling task is at least equal to their sensitivity in a burst detection task. Experiments 6 and 7 replicated the trading relation between closure duration and burst amplitude for labial stops in the ‘‘slit’’–‘‘split’’ and ‘‘slash’’–‘‘splash’’ distinctions, although burst amplification, in contrast to attenuation, had no effect. All experiments revealed that listeners are remarkably sensitive to the presence of even very weak release bursts.
Recovering from long-term and short-term adaptation of the whole nerve action potential
Authors: Abbas Paul J.
Published: October 2005

Properties of adaptation and recovery from adaptation are measured in response to adapter tones of short duration (100 ms), intermediate duration (1 m), and long duration (2–15 m). The decrease in N1 potential in response to a probe tone burst was used to assess the magnitude of adaptation. By measuring the response at different times after adapter offset the time course of recovery was assessed. By measuring the response to different probe frequencies, the spread of adaptation across place in the cochlea was assessed. Adapters of different duration showed quite different spread of adaptation across probe frequency. Short-duration adapters resulted in decrements of probe response greatest at and above probe frequency. Intermediate- and long-duration adapters showed progressively greater shifts in peak decrement to higher probe frequencies as adapter level was increased.
Sound field of a parametric focusing source
Authors: Tjo/tta Jacqueline Naze , Tjo/tta Sigve
Published: October 2005

An analytical description of the sound field of a parametric focusing source was given in a previous paper by Lucas, Naze Tjo/tta, and Muir [J. Acoust. Soc. Am. 73, 1966–1971 (1983)]. Results of an experimental investigation were also presented and compared with the theory. The results of new numerical computations are shown in the present paper. They lead to a more accurate evaluation of the parametric field in planes perpendicular to the axis of symmetry and to a better agreement with the observations.
An iterative perturbation approach for ocean acoustic tomography
Authors: Spofford C. W. , Stokes A. P.
Published: October 2005

An iterative algorithm for the inversion of ocean acoustic tomographic data is introduced. This allows the calculation of ocean environmental acoustic parameters from measured travel times between a distributed system of acoustic sources and receivers. The algorithm does not require expensive (because slowly convergent) nonlinear ray tracing. In each iteration both the modified environmental parameters and the perturbations to the ray paths are calculated from linearized equations. A convergence proof is outlined. It is shown in an example that a single iteration, which corresponds to the classical perturbation solution, can give insufficient accuracy in a realistic ocean. This is accomplished by evaluating the second variation of the travel-time data with respect to the environmental parameters and demonstrating that in typical, strongly focused sound channels it can be comparable in size to, or larger than the first variation.
Optical measurement of the reflection coefficient for bounded acoustic waves
Authors: Leroy O. , Claeys J. M.
Published: October 2005

Two alternative methods for optical measurement of reflection effects of bounded ultrasonic waves are suggested. Corresponding reflection coefficients are defined and theoretical results for the special case of Gaussian ultrasonic beams prove consistency with the plane-wave reflection coefficient. Calculated values of both newly defined reflection coefficients should be directly comparable to experimental data even when bounded beams are incident at critical angles where beam shift and phase reversal occur.
A uniform theory of diffraction for elastic solids
Authors: McMaken H.
Published: October 2005

We present a new method for approximating the scattering by cracks in elastic solids in which we reduce the normal surface integral over the crack surface to a line integral along the crack edge. The resultant approximation is spatially uniform and valid for high frequencies (ωa/cL  large). It recovers the geometrical theory of diffraction in the limit as ωa/cL → ∞, and as such may be considered an extension of this theory. Comparison is made with exact results for circular cracks, with excellent agreement found.
Studies in reverberation III. Perturbation theory of scattering of sound by convection
Authors: Pekeris C. L.
Published: October 2005

A perturbation method is developed for treating scattering of sound by convection. When applied to the problem of scattering of a plane sound wave by a cylindrical vortex, treated previously, good agreement was obtained for a value of the ratio of the frequency of rotation ω to the frequency σ of sound equal to 0.01. As the wavelength of sound diminishes to values smaller than the circumference of the cylinder, the waves which are scattered in directions lying on the side of the source become increasingly weaker than those scattered in directions on the side away from the source.
Sound scatter and shadowing at a seamount: Hybrid physical solutions in two and three dimensions
Authors: Medwin Herman , Childs Emily , Jordon Edgar A. , Spaulding Robert A.
Published: October 2005

Laboratory scale models and wedge diffraction computer models of sound propagation over a seamount have been used to determine the laws and the physical causes of seamount shadowing in terms of diffraction, forward scatter, and multiple reflections from seamount to ocean surface. The model results are ‘‘hybridized’’ with a ray solution (FACT model) for the refractive and attenuative effects away from the seamount and the sum produces excellent agreement with detailed continuous wave and impulse ocean data for Dickins Seamount over the frequency range 50–500 Hz [G. R. Ebbeson and R. G. Turner, J. Acoust. Soc. Am. 73, 143–152 (1983) and N. R. Chapman and G. R. Ebbeson, J. Acoust. Soc. Am. 73, 1979–1984 (1983)]. It is shown that: depending on the ocean roughness, diffraction over the crest can be the strongest contributor to the sound in the shadow region; the diffracted signal always arrives before the multiply reflected sound; the diffraction loss is proportional to f1/2; a two-dimensional model produces excessive diffraction and excessive multiple reflection signal compared to a realistic three-dimensional model.
The effects of intensity on the detection of interaural differences of time in high-frequency trains of clicks
Authors: Dye Raymond H. , Hafter Ervin R.
Published: October 2005

Threshold values of interaural differences of time (ΔIDTs) were measured for trains of dichotic clicks whose levels were 20, 40, or 60 dB SPL. All clicks were bandpass filtered at 4 kHz, and the number of clicks in the train (n) was 1, 2, 4, 8, 16, or 32. The interclick interval (ICI) was 5, 2, or 1 ms. Performance was compared to that of an ideal integrator of information, which produces slopes of −0.5 when log ΔIDT versus log n is plotted. The results showed that increases in level had no effect on the slopes of the log–log functions regardless of the ICI but did decrease the intercepts. Shortening the ICI caused the slopes to go from nearly −0.5 towards 0.0. The improvement with level could be explained by either a decrease in the temporal variability of neural discharges, or by an increase in the number of samples of IDT at higher intensities brought on by increased firing rates or the activation of more auditory units. A review of the physiological literature found the most parsimonious explanation to be that the decline in threshold IDT was mediated by an increase in the number of active units, each possessing the same degree of adaptation.
An acoustic lens design using the geometrical theory of diffraction
Authors: Shield Thomas W. , Harris John G.
Published: October 2005

The design of an acoustic lens that reduces the diffraction spreading from an ultrasonic transducer to produce a narrow focused beam is proposed. The design is based upon a description of the radiated field using the geometrical theory of diffraction.
Vibrational relaxation of SF6 in mixtures with Cl2 and H2
Authors: Detsch Richard M. , Bass Henry E.
Published: October 2005

Ultrasonic absorption has been measured in mixtures of SF6 with Cl2 and H2 for frequency to pressure ratios between 10 and 103 kHz/atm at room temperature. The absorption has been corrected for tube and classical losses to obtain vibrational relaxation times of SF6 during collisions with H2 and Cl2. The relaxation time of SF6 in 1 atm of Cl2 is found to be 4.4×10−7 s; in 1 atm of H2, the relaxation time is 0.18×10−7 s. The number of collisions required for Cl2 to de-excite the lowest vibrational model of SF6 is deduced to be 1600; for H2, only 81 collisions are required.
Comments on ‘‘A simple accurate method for predicting sonar performance without the need for computer simulations’’ [J. Acoust. Soc. Am. 7
3, 2059–2067(1983)]
Authors: Bordelon Derrill J.
Published: October 2005

It is shown that early assumptions needlessly restrict the generality of a result of RŠ. [Richter and Šmits, J. Acoust. Soc. Am. 73, 2059–2067 (1983)]. Evaluation of a double integral as a univariate error function is effected by a suitable rotation of the base plane.
Time relations between cricothyroid muscle activity and the voice fundamental frequency (F0) during sinusoidal modulations of F
Authors: Sapir Shimon , McClean Michael D. , Luschei Erich S.
Published: October 2005

Electromyographic (EMG) recordings from the cricothyroid (CT) muscle were obtained in two adult male subjects attempting to modulate their voice fundamental frequency (F0) sinusoidally between 150 and 225 Hz or between 300 and 450 Hz at a rate of 1 Hz. Sinusoidal modulations of F0 were associated with similar modulations in the rectified CT EMG. Signal averaging and spectral analysis techniques were used to assess the time relation between the rectified CT EMG and F0 signals. At a rate of 1-Hz F0 modulation, the F0 signal lagged behind the CT EMG signal by 52°–57°, corresponding to a time lag of 144–158 ms. These findings are discussed in relation to previous measures of the EMG–F0 time relationship and the mechanisms of F0 control.
Intensity in stratified random media
Authors: Mazar R. , Beran M. J.
Published: October 2005

Using a three-scale expansion, we solved the equation governing the propagation of the coherence function in a random medium with a mean index of refraction profile. An expression for the intensity distribution near a caustic was obtained including both diffraction and scattering effects. The expression may be readily evaluated in the absence of scattering and in the case of weak or strong scattering. Numerical examples are presented.
Long-range Pacific acoustic multipath identification
Authors: Northrop John , Shockley Richard C.
Published: October 2005

Acoustic signals from three long-range (500–700 km) transmission paths in the Northeast Pacific were examined for multipath structures. Sound propagation along each path encountered both different sound-speed provinces and unique bathymetry which, together with the range differences, caused characteristic pulse arrival patterns at each hydrophone site. The receivers were all on a sloping bottom at depths between 1200 and 1400 m and the source depth was at 450 m in deep water. Ray-path arrivals were modeled using impulse, a new ray-theoretical impulse response code written by one of us (RCS). This code uses piecewise continuous cubic polynomials to fit the sound-speed profile and bathymetric profile, and Runge–Kutta methods to solve the ray equation of motion. It allows arbitrary ray density in launch angle, and identifies eigenrays by searching for rays whose depths bracket the receiver and which were adjacent at the source. Using this procedure, we were able to identify most of the major pulse arrivals observed at each of the recording sites.
Acoustic spectrogram and complex-frequency poles of a resonantly excited elastic tube
Authors: Gaunaurd G. C. , Brill D.
Published: October 2005

We present a study of the resonance scattering undergone by an air-filled hollow elastic cylinder excited by an incident plane acoustic wave. We construct the boundary value problem, obtain its classical solution, the solution based on the Resonance Scattering Theory (RST), and generate a variety of useful computed results, some of which are later compared to experimental observations recently performed in France. We present highly accurate expressions for the phase and group velocities and for the phase and group attenuations of the first few surface waves circumnavigating (the extreme cases) of rigid and soft cylinders, and display these dispersion plots in all instances. We analyze the modal backgrounds and modal resonances of the shell, display them in a wide spectral band, determine the SEM-type pole-position diagram in the complex k1a plane, and obtain and display the background-suppressed cross section of the tube. This result serves to generate the acoustic spectrogram of the shell as well as to show the excellent agreement of this theoretical prediction with the experimental observations carried on in France. We analyze cross-sectional poles and cross-sectional dips, and reduce many of the present shell results to particular cases for impenetrable cylinders and solid elastic cylinders. For these latter ones, we obtain the dispersion plots for the phase and group velocities of the internal surface waves revolving around them. We determine expressions for the nearfield shell cross sections at different ranges, and compare them to the usual farfield results. We determine the sound pressure levels transmitted into the shell’s interior, and exhibit the controlling role the tube resonances have on the isobaric contours. We display extensive computerized calculations to illustrate all these points. Comparisons with experimental observations are shown to be quite favorable, particularly for the background-suppressed shell cross section, and for its acoustic spectrogram.
Evaluation of the nonlinearity parameter of liquid metals
Authors: Narayana K. L. , Swamy K. M.
Published: October 2005

Equations have been developed for evaluating the temperature and pressure coefficients of sound velocity using the easily accessible parameters. In the case of liquid metals the calculated B/A values obtained through the above equations are found to agree well with the experimental values of B/A. Further, the authors’ treatment takes care of the isochoric acoustic exponent K″ whose value is assumed to be zero by previous investigators.
‘‘Facedness’’and its relation to musical talent
Authors: Smith Karl U.
Published: October 2005

This is a preliminary report on the study of a newly recognized aspect of lateral dominance termed facedness, and its relation to musical talent. The research deals with facial asymmetries in populations of various countries and in individuals of demonstrated exceptional musical talent. [AIP]
Comments on ‘‘The optimization of electronic precision in ultrasonic velocity measurements: A comparison of the time interval averaging and sing around methods’’ [J. Acoust. Soc. Am. 7
3, 1833–1837 (1983)]
Authors: Karplus Henry B.
Published: October 2005

J. D. Aindow and R. C. Chivers [J. Acoust. Soc. Am. 73, 1833 (1983)] compared the precision of the direct ‘‘time-of-flight’’ technique with the ‘‘sing-around’’ method for sound velocity measurement. Their conclusion is changed by the newer, faster, commercial clocks (2 ns HP5345<0.1 ns HP5370), giving the advantage to the time of flight method. The analysis is herewith augmented by calculating the time jitter in terms of signal to noise ratio, which was correctly shown to be negligible with 100-ns clocks, but becomes increasingly more significant with faster clocks.
Model studies of barrier performance in the presence of ground surfaces. Part I—Thin, perfectly reflecting barriers
Authors: Hutchins D. A. , Jones H. W. , Russell L. T.
Published: October 2005

A scale model study is presented of the performance of thin, perfectly reflecting semi-infinite barriers in the presence of both asphalt and grass-covered surfaces. The barrier insertion loss is shown to be strongly dependent on the type of ground on either side of the barrier. Observed behavior is explained by a study of the interference phenomena occurring in both the barrier’s presence and its absence.
Comment on ‘‘Measurement of pitch in speech: An implementation of Goldstein’s theory of pitch perception’’ [J. Acoust. Soc. Am. 7
1, 1568 (1982)]
Authors: Allik Jüri , Mihkla Meelis , Ross Jaan
Published: October 2005

The pitch detection algorithm proposed by Duifhuis, Willems, and Sluyter [J. Acoust. Soc. Am. 71, 1568–1580 (1982)] can be made more than 20 times faster by replacing the harmonic sieve procedure by the approximate common denominator procedure, the results differing only slightly.
A Lamb wave frequency modulator with three interdigital transducers
Authors: Toda Kohji , Mizutani Koichi
Published: October 2005

A voltage-controlled oscillator using a Lamb wave device with three interdigital transducers is demonstrated as a frequency modulator. One of three transducers at the central part of the device is used to feed a modulating signal via FETs as voltage-controlled resistors. The other two transducers compose a delay line oscillator with an amplifier. The oscillation frequency varies linearly with the voltage applied to FETs. The design and basic properties are described.
Sexual Selection Can Resolve Sex-Linked Sexual Antagonism
Authors: Albert Arianne Y. K. , Otto Sarah P.
Published: October 2005

Sexual selection is a potent evolutionary force. However, very few models have considered the evolution of female preferences for traits expressed in both sexes. Here we explore how female preferences coevolve with sexually antagonistic traits, which involve alleles that are beneficial to one sex but harmful to the other. We show that with a sexually antagonistic trait on the X chromosome (males XY, females XX), females evolve to prefer mates carrying alleles beneficial to daughters. In contrast, with a Z-linked trait (males ZZ, females ZW), females more often evolve mating preferences for mates carrying alleles beneficial to sons (that is, flashy displays).
A Reversible, Unidirectional Molecular Rotary Motor Driven by Chemical Energy
Authors: Fletcher Stephen P. , Dumur Frédéric , Pollard Michael M. , Feringa Ben L.
Published: October 2005

With the long-term goal of producing nanometer-scale machines, we describe here the unidirectional rotary motion of a synthetic molecular structure fueled by chemical conversions. The basis of the rotation is the movement of a phenyl rotor relative to a naphthyl stator about a single bond axle. The sense of rotation is governed by the choice of chemical reagents that power the motor through four chemically distinct stations. Within the stations, the rotor is held in place by structural features that limit the extent of the rotor's Brownian motion relative to the stator.
Diagnosis of Invasive Pneumococcal Disease among Children in Kenya with Enzyme-Linked Immunosorbent Assay for Immunoglobulin G Antibodies to Pneumococcal Surface Adhesin A
Authors: Scott J. Anthony G. , Mlacha Zena , Nyiro Joyce , Njenga Salome , Lewa Pole , Obiero Jacktone , Otieno Hanningtone , Sampson Jacquelyn S. , Carlone George M.
Published: October 2005

Diagnostic techniques for invasive pneumococcal disease (IPD) in children are insensitive and underestimate both the burden of disease and the cost-effectiveness of pneumococcal conjugate vaccination (PCV). Consequently, there is little demand for the highly effective PCV outside the United States and Europe. In Kenya, diagnosis of pneumococcal pneumonia in adults was achieved with a sensitivity of 0.70 and a specificity of 0.98 using enzyme-linked immunosorbent assays (ELISAs) of paired plasma samples for immunoglobulin G (IgG) to pneumococcal surface adhesin A (PsaA). We aimed to validate the same technique in children. We assayed paired blood samples from 98 children with IPD, 95 age-matched children with malaria/anemia, and 97 age-matched healthy controls by using an ELISA for anti-PsaA IgG. Sensitivity and specificity were determined in IPD patients and healthy controls. Specificity (0.97; 95% confidence interval [CI], 0.91 to 0.99) and sensitivity (0.42; 95% CI, 0.32 to 0.52) were optimized at a 2.7-fold rise in anti-PsaA antibody concentration. Sensitivity was improved to a maximum of 0.50 by restricting testing to children of <2 years old, by excluding IPD patients who were not sampled on the first day of presentation, and by incorporating high existing antibody concentrations in the analysis. Assay performance was independent of nasopharyngeal carriage of pneumococci at recruitment. This assay improves on existing diagnostic tools for IPD in children but would still leave over half of all cases undetected in epidemiological studies. Effective diagnosis of pneumococcal disease in children is urgently required but poorly served by existing technology.
Generation of Feline Dendritic Cells Derived from Peripheral Blood Monocytes for In Vivo Use
Authors: Freer Giulia , Matteucci Donatella , Mazzetti Paola , Bozzacco Leonia , Bendinelli Mauro
Published: October 2005

Dendritic cells (DCs) are professional antigen-presenting cells that can prime T cells and polarize the cellular immune response. Because Th1-type immune responses have been connected to success in combating viral infection, a promising therapeutic application of DCs would be their differentiation in vitro and injection back into the host to boost an immune response in infected animals. This study was aimed both at developing a protocol to cultivate feline DCs in the absence of exogenous proteins for their use in vivo and at investigating what might be the most appropriate stimulus to induce their maturation in vitro and finding correlates of maturation. We generated DCs from peripheral blood monocytes in the presence of feline interleukin-4 and granulocyte-macrophage colony stimulating factor, and after 5 days their maturation was induced with either lipopolysaccharide, human recombinant tumor necrosis factor alpha, poly(I:C), or activated feline platelets. After 48 h, their CD14, CD1a, major histocompatibility complex class II, and B7.1 surface expression was analyzed in parallel with their ability to uptake antigen or prime a mixed leukocyte reaction. The results presented show that feline DCs cultured in autologous plasma differentiate and are able to mature in the presence of stimuli similar to the ones currently used for other species. The present work sets the grounds for future use of DCs obtained by the protocol described for in vivo vaccination and immunotherapy of feline immunodeficiency virus-infected cats.
Lassa Fever Virus Peptides Predicted by Computational Analysis Induce Epitope-Specific Cytotoxic-T-Lymphocyte Responses in HLA-A2.1 Transgenic Mice
Authors: Boesen Agnieszka , Sundar Krishnan , Coico Richard
Published: October 2005

Lassa fever is a hemorrhagic disease caused by Lassa fever virus (LV). Although the precise host defense mechanism(s) that affords protection against LV is not completely understood, cellular immunity mediated by cytotoxic T lymphocytes (CTLs) plays a pivotal role in controlling viral replication and LV infection. To date, there have been no reports mapping major histocompatibility complex (MHC) class I-binding CTL epitopes for LV. Using computer-assisted algorithms, we identified five HLA-A2.1-binding peptides of LV glycoprotein (GP) and two peptides from LV nucleoprotein (NP). Synthesized peptides were examined for their ability to bind to MHC class I molecules using a flow cytometric assay that measures peptide stabilization of class I. Three of the LV-GP peptides tested (LLGTFTWTL, SLYKGVYEL, and YLISIFLHL) stabilized HLA-A2. The LV-NP peptides tested failed to stabilize this HLA-A2. We then investigated the ability of the HLA-A2-binding LV-GP peptides to generate peptide-specific CTLs in HLA-A2.1 transgenic mice. Functional assays used to confirm CTL activation included gamma interferon enzyme-linked immunospot (ELISPOT) assays and intracellular cytokine staining of CD8+T cells from peptide-primed mice. CTL assays were also performed to verify the cytolytic activity of peptide-pulsed target cells. Each of the LV-GP peptides induced CTL responses in HLA-A2-transgenic mice. MHC class I tetramers prepared using one LV-GP peptide that showed the highest cytolytic index (LLGTFTWTL) confirmed that peptide-binding CD8+T cells were present in pooled lymphocytes harvested from peptide-primed mice. These findings provide direct evidence for the existence of LV-derived GP epitopes that may be useful in the development of protective immunogens for this hemorrhagic virus.
An investigation of the anger levels of residents: medical compared with surgical disciplines
Authors: Satar S , Cenkseven F , Karcioglu O , Topal M , Sebe A
Published: October 2005

Objective

To evaluate medical and surgical residents’ anger levels with regard to the department in which they worked, seniority, sex, satisfaction with their work environment, and the number of nightshifts worked per month. The specific situations and persons at whom residents reacted with anger were also investigated.

Methods

116 randomly selected residents staffed in a university hospital (62 medical and 54 surgical residents) were enrolled. The trait anger and anger expression scale was used to find out the personal anger levels of each participant. The participants also clarified the persons and situations that made them angry at work.

Results

Trait anger levels were greater in the surgical residents in their first two years when compared with levels of their senior colleagues (p = 0.033). Mean trait anger levels were greater in the residents who were not satisfied with their department (p = 0.004). Anger levels were not found to be related to the number of shifts per month. Male residents had higher levels of anger than female colleagues (p = 0.019).

Conclusion

Residents in clinical sciences seem to have the potential to benefit from a screening process in terms of anger and its subcomponents by means of a tool such as the trait anger and anger expression scale during their residency.
Toward health and wellbeing for indigenous Australians
Authors: van Holst Pellekaan S M , Clague L
Published: October 2005

The health of indigenous Australians remains well below that of non-indigenous Australians and indigenous peoples in Canada and New Zealand. Although recent planning has initiated many outstanding, culturally appropriate programmes with indigenous involvement, health statistics only reflect marginal improvement in recent years. It is crucial that positive programmes are sustained with appropriately directed funding. An approach that includes respect for the emotional and spiritual wellbeing of Australia’s indigenous peoples will assist to redress some of the disadvantage caused by dispossession of country, language, and identity. It is clear from many programmes that are in place, that primary health care delivered locally through community controlled organisations, will minimise the impact of serious illnesses that currently threaten whole families and communities. Westernised health care systems are slow to learn from indigenous peoples in Australia and other places, that maintenance of wellness, not management of illness should be the goal.
Nutrition support for patients in the intensive care unit
Authors: Griffiths R D , Bongers T
Published: October 2005

Enteral nutrition (EN) is the mainstay of nutrition delivery within intensive care seeking to capitalise on its benefits for the gastrointestinal tract and associated immune system, but this has brought new challenges in delivery to the sick. The hoped for benefit has led to the mistaken belief by some that parenteral nutrition (PN) is no longer required. However, a greater appreciation of the risks of EN delivery in the sick patient combined with improvements in PN formulation and use help explain why PN is not as risky as some have believed. Real outcome benefits have been described with the new glutamine containing PN formulations. PN remains important in the presence of gastrointestinal feed intolerance or failure.
CHEMICAL STATE ANALYSIS OF Cr AND Fe BY IN-AIR PIXE USING A CURVED CRYSTAL SPECTROMETER COMBINED WITH A POSITION-SENSITIVE PROPORTIONAL COUNTER
Authors: MAEDA KUNIKO , HASEGAWA KENICHI , HAMANAKA HIROMI , OGIWARA KIYOSHI , TSUJI MASAMICHI , MURAO SATOSHI
Published: October 2005

The feasibility of RIKEN high-resolution PIXE system for direct chemical state analysis of 3d transition elements was examined. K β spectra of Cr and Fe from several compounds were measured in air at atmospheric pressure using a crystal spectrometer consisting of a position-sensitive proportional counter and a curved crystal in v. Hamos geometry. Fine structures which reflect the chemical states of Cr and Fe were well recognized with the measuring time of tens minutes.
LINEAR ACCELERATOR MASS SPECTROMETRY WITH PIXE CALIBRATION
Authors: UEDA SHINTARO , HATTORI TOSHIYUKI , HAYASHIZAKI NORIYOSU , HATA TOSHIKI , KAWASAKI KATUNORI , NAGAE DAISUKE
Published: October 2005

AMS is commonly used in radioisotope analysis because it can detect isotopes down to levels of 10-15 by abundance, but applications for trace element analysis are few. Therefore, we propose a new kind of AMS for trace element analysis using a linear accelerator (LINAC), an Electron Cyclotron Resonance Ion Source (ECRIS), and calibration methods with PIXE analysis. Abundance ratios of each element measured by PIXE are applied to create distribution charts of particles and charge states, and these charts are used for quantitative analysis. We report the concepts behind our AMS and calibration methods in this paper.