bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and biochemical characterization of the Anopheles gambiae 3‐hydroxykynurenine transaminase
Authors: Rossi Franca , Lombardo Fabrizio , Paglino Alessandra , Cassani Camilla , Miglio Gianluca , Arcà Bruno , Rizzi Menico
Published: October 2005

Spontaneous oxidation of 3‐hydroxykynureine (3‐HK), a metabolic intermediate of the tryptophan degradation pathway, elicits a remarkable oxidative stress response in animal tissues. In the yellow fever mosquito Aedes aegypti the excess of this toxic metabolic intermediate is efficiently removed by a specific 3‐HK transaminase, which converts 3‐HK into the more stable compound xanthurenic acid. In anopheline mosquitoes transmitting malaria, xanthurenic acid plays an important role in Plasmodium gametocyte maturation and fertility. Using the sequence information provided by the Anopheles gambiae genome and available ESTs, we adopted a PCR‐based approach to isolate a 3‐HK transaminase coding sequence from the main human malaria vector A. gambiae. Tissue and developmental expression analysis revealed an almost ubiquitary profile, which is in agreement with the physiological role of the enzyme in mosquito development and 3‐HK detoxification. A high yield procedure for the expression and purification of a fully active recombinant version of the protein has been developed. Recombinant A. gambiae 3‐HK transaminase is a dimeric pyridoxal 5′‐phosphate dependent enzyme, showing an optimum pH of 7.8 and a comparable catalytic efficiency for both 3‐HK and its immediate catabolic precursor kynurenine. This study may be useful for the identification of 3‐HK transaminase inhibitors of potential interest as malaria transmission‐blocking drugs or effective insecticides.
Nerve influence on myosin light chain phosphorylation in slow and fast skeletal muscles
Authors: Bozzo Cyril , Spolaore Barbara , Toniolo Luana , Stevens Laurence , Bastide Bruno , Cieniewski‐Bernard Caroline , Fontana Angelo , Mounier Yvonne , Reggiani Carlo
Published: October 2005

Neural stimulation controls the contractile properties of skeletal muscle fibres through transcriptional regulation of a number of proteins, including myosin isoforms. To study whether neural stimulation is also involved in the control of post‐translational modifications of myosin, we analysed the phosphorylation of alkali myosin light chains (MLC1) and regulatory myosin light chains (MLC2) in rat slow (soleus) and fast (extensor digitorum longus EDL) muscles using 2D‐gel electrophoresis and mass spectrometry. In control rats, soleus and EDL muscles differed in the proportion of the fast and slow isoforms of MLC1 and MLC2 that they contained, and also in the distribution of the variants with distinct isoelectric points identified on 2D gels. Denervation induced a slow‐to‐fast transition in myosin isoforms and increased MLC2 phosphorylation in soleus, whereas the opposite changes in myosin isoform expression and MLC2 phosphorylation were observed in EDL. Chronic low‐frequency stimulation of EDL, with a pattern mimicking that of soleus, induced a fast‐to‐slow transition in myosin isoforms, accompanied by a decreased MLC2 phosphorylation. Chronic administration (10 mg·kg−1·d−1 intraperitoneally) of cyclosporin A, a known inhibitor of calcineurin, did not change significantly the distribution of fast and slow MLC2 isoforms or the phosphorylation of MLC2. All changes in MLC2 phosphorylation were paralleled by changes in MLC kinase expression without any variation of the phosphatase subunit, PP1. No variation in MLC1 phosphorylation was detectable after denervation or cyclosporin A administration. These results suggest that the low‐frequency neural discharge, typical of soleus, determines low levels of MLC2 phosphorylation together with expression of slow myosin, and that MLC2 phosphorylation is regulated by controlling MLC kinase expression through calcineurin‐independent pathways.
Molecular identification of adrenal inner zone antigen as a heme‐binding protein
Authors: Min Li , Strushkevich Natallia V. , Harnastai Ivan N. , Iwamoto Hiroko , Gilep Andrei A. , Takemori Hiroshi , Usanov Sergey A. , Nonaka Yasuki , Hori Hiroshi , Vinson Gavin P. , Okamoto Mitsuhiro
Published: October 2005

The adrenal inner zone antigen (IZA), which reacts specifically with a monoclonal antibody raised against the fasciculata and reticularis zones of the rat adrenal, was previously found to be identical with a protein variously named 25‐Dx and membrane‐associated progesterone receptor. IZA was purified as a glutathione S‐transferase‐fused or His6‐fused protein, and its molecular properties were studied. The UV‐visible absorption and EPR spectra of the purified protein showed that IZA bound a heme chromophore in high‐spin type. Analysis of the heme indicated that it is of the b type. Site‐directed mutagenesis studies were performed to identify the amino‐acid residues that bind the heme to the protein. The results suggest that two Tyr residues, Tyr107 and Tyr113, and a peptide stretch, D99–K102, were important for anchoring the heme into a hydrophobic pocket. The effect of IZA on the steroid 21‐hydroxylation reaction was investigated in COS‐7 cell expression systems. The results suggest that the coexistence of IZA with CYP21 enhances 21‐hydroxylase activity.
The synchrotron foreground and the cosmic microwave background temperature-polarization cross-correlation power spectrum from the first-year WMAP data
Authors: Bernardi G. , Carretti E. , Fabbri R. , Sbarra C. , Cortiglioni S.
Published: October 2005

We analyse the temperature–polarization cross-correlation in the Galactic synchrotron template that we have recently developed, and between the template and cosmic microwave background (CMB) temperature maps derived from WMAP data. Since the polarized synchrotron template itself uses WMAP data, we can estimate residual synchrotron contamination in the CMB CTEℓ angular spectrum. While CTE2 appears to be contaminated by synchrotron, no evidence for contamination is found in the multipole range which is most relevant for the fit of the cosmological optical depth.
SENSORY AND INSTRUMENTAL TEXTURE MEASUREMENT OF THERMALLY PROCESSED RICE
Authors: PRAKASH M. , RAVI R. , SATHISH H.S. , SHYAMALA J.C. , SHWETHA M.A. , RANGARAO G.C.P.
Published: October 2005

Rice is the staple food of many countries and its sensory quality is of great concern to the consumers. Its preservation through thermal processing in retort pouches for ready‐to‐eat purposes was carried out by different time–temperature schedules with and without oil to achieve a minimum Foof 3 min. The sensory analysis of the cooked rice carried out using quantitative descriptive analysis showed that a process schedule of 118C, 8 min was optimum to have the optimal sensory characteristics. The same rice samples were subjected to instrumental texture measurements by texture analyzer using a crosshead speed of 0.5 mm/s with 90% compression for hardness and stickiness parameters. The instrumental hardness showed high correlation with sensory hardness, chewiness and overall quality (r = 0.72; r = 0.73; r = 0.79) and a negative correlation with sensory stickiness (r = −0.75). Applying principal component analysis, thermally processed rice samples were further classified based on the sensory and instrumental texture attributes.
INSTRUMENTAL AND SENSORY EVALUATION OF TEXTURAL ATTRIBUTES IN CHEESE ANALOGS: A CORRELATION STUDY
Authors: PEREIRA R.B. , BENNETT R.J. , LUCKMAN M.S.
Published: October 2005

The objective of this study was to investigate the usefulness of an array of statistical techniques to describe relationships between instrumental data and non‐oral sensory texture profiling scores by using a range of model processed cheese analogs as example. Pairwise correlation, used as an exploratory tool, showed no significant correlation for flexibility and greasiness with any individual instrumental parameter. Stepwise regression, principal component regression and partial least squares regression were used to generate models for firmness, stickiness and curdiness of the analogs studied. No models could be generated for flexibility and greasiness, and models for rubberiness had poor quality of fit compared with the other sensory attributes. In general, firmness, stickiness and curdiness were satisfactorily modeled by using chemical data and small deformation rheological parameters. Compression data (large deformation), often used in correlation studies regarding the texture of cheese, did not necessarily lead to better correlation results in comparison with other instrumental parameters used in this research.
Dynamic Spherical Cavity Expansion in an Elastoplastic Compressible Mises Solid
Authors: Masri Rami , Durban David
Published: October 2005

The elastoplastic field induced by a self-similar dynamic expansion of a pressurized spherical cavity is investigated for the compressible Mises solid. The governing system consists of two ordinary differential equations for two stress components where radial velocity and density are known functions of these stresses. Numerical illustrations of radial profiles of field variables are presented for several metals. We introduce a new solution based on expansion in powers of the nondimensionalized cavity expansion velocity, for both elastic/perfectly plastic response and strain-hardening behavior. A Bernoulli-type solution for the dynamic cavitation pressure is obtained from the second-order expansion along with a more accurate third-order solution. These solutions are mathematically closed and do not need any best fit procedure to numerical data, like previous solutions widely used in the literature. The simple solution for elastic/perfectly plastic materials reveals the effects of elastic-compressibility and yield stress on dynamic response. Also, an elegant procedure is suggested to include strain-hardening in the simple elastic/perfectly plastic solution. Numerical examples are presented to demonstrate the validity of the approximate solutions. Applying the present cavitation model to penetration problems reveals good agreement between analytical predictions and penetration depth tests.
Crack Identification in Thin Plates With Anisotropic Damage Model and Vibration Measurements
Authors: Wu D. , Law S. S.
Published: October 2005

Many approaches on modeling of cracks in structural members have been reported in the literatures. However, most of them are explicitly developed for the purpose of studying the changes in static and dynamic responses of the structure due to the crack damage, which is a forward problem mathematically. Thereby the use of these models is inconvenient or even impossible for detecting damage in structures from vibration measurements, which is usually an inverse problem. An anisotropic damage model is proposed for a two-dimensional plate element with an edge-parallel crack. The cracked plate element is represented by a plate element with orthotropic anisotropic material expressed in terms of the virgin material stiffness and a tensor of damage variables. Instead of using the effective stress concept, strain equivalence, or strain energy equivalence principles, the vector of damage variables is identified based on the principle of equivalent static and dynamic behaviors. A nonmodel-based damage identification approach is developed incorporating the proposed anisotropic model and the estimated uniform load surface curvature (ULSC) from vibration measurements. The actual length of the crack is then predicted from the identified variables based on conservation law of potential energy for crack growth. The validity of the methodology is demonstrated by numerical examples and experiment results with comparison to results from existing strain energy equivalence theory.
Stochastic Dynamics of
Impact Oscillators
Authors: Namachchivaya N.
Sri , Park Jun
H.
Published: October 2005

The purpose of this work is to develop an averaging approach to study the dynamics of a vibro-impact system excited by random perturbations. As a prototype, we consider a noisy single-degree-of-freedom equation with both positive and negative stiffness and achieve a model reduction, i.e., the development of rigorous methods to replace, in some asymptotic regime, a complicated system by a simpler one. To this end, we study the equations as a random perturbation of a two-dimensional weakly dissipative Hamiltonian system with either center type or saddle type fixed points. We achieve the model-reduction through stochastic averaging. Examination of the reduced Markov process on a graph yields mean exit times, probability density functions, and stochastic bifurcations.
New Strain Energy Function for Acoustoelastic Analysis of Dilatational Waves in Nearly Incompressible, Hyper-Elastic Materials
Authors: Kobayashi H. , Vanderby R.
Published: October 2005

Acoustoelastic analysis has usually been applied to compressible engineering materials. Many materials (e.g., rubber and biologic materials) are “nearly” incompressible and often assumed incompressible in their constitutive equations. These material models do not admit dilatational waves for acoustoelastic analysis. Other constitutive models (for these materials) admit compressibility but still do not model dilatational waves with fidelity (shown herein). In this article a new strain energy function is formulated to model dilatational wave propagation in nearly incompressible, isotropic materials. This strain energy function requires four material constants and is a function of Cauchy–Green deformation tensor invariants. This function and existing (compressible) strain energy functions are compared based upon their ability to predict dilatational wave propagation in uniaxially prestressed rubber. Results demonstrate deficiencies in existing functions and the usefulness of our new function for acoustoelastic applications. Our results also indicate that acoustoelastic analysis has great potential for the accurate prediction of active or residual stresses in nearly incompressible materials.
Axisymmetrical Snapping of a Spinning Nonflat Disk
Authors: Chen Jen-San , Lin Chi-Chung
Published: October 2005

In this paper we study the steady-state deflection of a spinning nonflat disk, both theoretically and experimentally. Both the initial and the deformed shapes of the disk are assumed to be axisymmetrical. Von Karman’s plate model is adopted to formulate the equations of motion, and Galerkin’s method is employed to discretize the partial differential equations. In the case when the initial height of the nonflat disk is sufficiently large, multiple equilibrium positions can exist, among them the two stable one-mode solutions P01 and P03 are of particular interest. Theoretical investigation shows that if the disk is initially in the stressed position P03, it will be snapped to position P01 when the rotation speed reaches a critical value. Experiments on a series of copper disks with different initial heights are conducted to verify the theoretical predictions. Generally speaking, the experimental measurements agree well with theoretical predictions when the initial height is small. For the disks with large initial heights, on the other hand, the measured snapping speeds are significantly below the theoretical predictions. The circumferential waviness of the copper disks induced in the manufacturing process and the aerodynamic force at high rotation speed are two possible factors causing this discrepancy.
Procedures for the Verification and Validation of Working Models for Structural Shells
Authors: Szabo Barna A. , Muntges Daniel E.
Published: October 2005

Shell-like structures are viewed as fully three-dimensional solid bodies that allow the imposition of restrictions on the transverse variation of displacement vector components in certain regions. An important practical problem is to select a simplified mathematical model for a particular application so that the simplifications do not affect the data of interest significantly. This involves application of expert knowledge aided by virtual and∕or physical experimentation. An example is presented.
Plane-Strain Propagation of a Fluid-Driven Fracture: Small Toughness Solution
Authors: Garagash Dmitry I. , Detournay Emmanuel
Published: October 2005

The paper considers the problem of a plane-strain fluid-driven fracture propagating in an impermeable elastic solid, under condition of small (relative) solid toughness or high (relative) fracturing fluid viscosity. This condition typically applies in hydraulic fracturing treatments used to stimulate hydrocarbons-bearing rock layers, and in the transport of magma in the lithosphere. We show that for small values of a dimensionless toughness K, the solution outside of the immediate vicinity of the fracture tips is given to O(1) by the zero-toughness solution, which, if extended to the tips, is characterized by an opening varying as the (2∕3) power of the distance from the tip. This near tip behavior of the zero-toughness solution is incompatible with the Linear Elastic Fracture Mechanics (LEFM) tip asymptote characterized by an opening varying as the (1∕2) power of the distance from the tip, for any nonzero toughness. This gives rise to a LEFM boundary layer at the fracture tips where the influence of material toughness is localized. We establish the boundary layer solution and the condition of matching of the latter with the outer zero-toughness solution over a lengthscale intermediate to the boundary layer thickness and the fracture length. This matching condition, expressed as a smallness condition on K, and the corresponding structure of the overall solution ensures that the fracture propagates in the viscosity-dominated regime, i.e., that the solution away from the tip is approximately independent of toughness. The solution involving the next order correction in K to the outer zero-toughness solution yields the range of problem parameters corresponding to the viscosity-dominated regime.
A Nonlinear Model for Dielectric Elastomer Membranes
Authors: Goulbourne Nakhiah , Mockensturm Eric , Frecker Mary
Published: October 2005

The material and geometrical nonlinearities of novel dielectric elastomer actuators make them more difficult to model than linear materials used in traditional actuators. To accurately model dielectric elastomers, a comprehensive mathematical formulation that incorporates large deformations, material nonlinearity, and electrical effects is derived using Maxwell-Faraday electrostatics and nonlinear elasticity. The analytical model is used to numerically solve for the resultant behavior of an inflatable dielectric elastomer membrane, subject to changes in various system parameters such as prestrain, external pressure, applied voltage, and the percentage electroded membrane area. The model can be used to predict acceptable ranges of motion for prescribed system specifications. The predicted trends are qualitatively supported by experimental work on fluid pumps [A. Tews, K. Pope, and A. Snyder, Proceedings SPIE, 2003)]. For a potential cardiac pump application, it is envisioned that the active dielectric elastomer membrane will function as the motive element of the device.
Frequency Analysis of the Tuned Mass Damper
Authors: Krenk Steen
Published: October 2005

The damping properties of the viscous tuned mass damper are characterized by dynamic amplification analysis as well as identification of the locus of the complex natural frequencies. Optimal damping is identified by a combined analysis of the dynamic amplification of the motion of the structural mass as well as the relative motion of the damper mass. The resulting optimal damper parameter is about 15% higher than the classic value, and results in improved properties for the motion of the damper mass. The free vibration properties are characterized by analyzing the locus of the natural frequencies in the complex plane. It is demonstrated that for optimal frequency tuning the damping ratio of both vibration modes are equal and approximately half the damping ratio of the applied damper, when the damping is below a critical value corresponding to a bifurcation point. This limiting value corresponds to maximum modal damping and serves as an upper limit for damping to be applied in practice.
Modeling high-frequency vertical directional spectra
Authors: Kennedy Robert M. , Szlyk Thomas K.
Published: October 2005

A measurement of the acoustic ambient arriving from a horizontal direction along with total sound-pressure-level spectrum allows one to infer directional spectra and some physical characteristics of sea surface-generated sound. A 1-year measurement of these two quantities was made at high frequency, i.e., 8–32 kHz, in The Tongue of the Ocean, The Bahamas. The horizontally directed ambient was measured using vertically oriented line arrays (broadside beam only available) and was observed at wind speeds ranging from 1–30 kn. The resulting database was used to estimate the statistics of anisotropic “noise gain.” The measured statistics showed two distinct cases: whitecaps present and not present. The relationship of these results to the total vertical directional spectrum is investigated by comparisons with a model that includes spatially diffuse near-surface sources, media scattering, and thermal noise. A comparison of the model and experiment results quantified an “effective” thickness of an acoustically active sublayer of monopole sources and a frequency-dependent media smearing of the source-to-receiver ray paths.
Stabilized high-resolution beamforming with horizontal arrays: Two experimental trials in shallow water
Authors: Gragg Robert F. , Pasewark Bruce H.
Published: October 2005

High-resolution algorithms are potentially able to outperform conventional linear methods at the task of beamforming, i.e., spatial-spectrum estimation, and in controlled experiments or simple computer simulations they often do prove superior. In marine environments, however, high-resolution techniques frequently fall short of these expectations. Their outputs can take on an unstable appearance characterized by fading of the true target peak and by the occurrence of multiple false targets. In recent years a class of stabilization techniques has evolved to moderate these effects by suppressing contributions from the smaller eigenvalues of the cross-spectral density matrix. While such techniques generally produce good results in simulations with the maximum likelihood estimator and even with the more sensitive maximum entropy estimator, they have seen little use on sea data. Here, results are presented of two sea trials of a simple eigenvalue stabilization procedure in a relatively demanding class of environments—shallow water. The technique provided what is considered to be marginal stabilization for the maximum likelihood estimator and none at all for maximum entropy.
Directionality of ice cracking events
Authors: Zakarauskas Pierre , Thorleifson Jon M.
Published: October 2005

This paper presents the measured vertical directivity of ice cracking events extracted from a 341 s sample of ambient noise recorded under the polar ice pack. The sample was taken with a vertical linear array of four hydrophones suspended over the Arctic continental shelf in 500 m of water. The hydrophone spacing was 100 m. The samples from each hydrophone were bandpass filtered between 40 and 1250 Hz, and searched for corresponding peaks in the acoustic pressure. The acoustic events are believed to be due predominantly to thermal ice cracking. The angular distribution of the 765 arrivals detected has its maximum at 15 deg below the horizontal, with most of the arrivals occurring between 0 and 25 deg below the horizontal. An explanation for this observation is given in terms of a simple ray-based model of the propagation of ice cracking noise. The asymmetry in the angular distribution is shown to be due mostly to the source directivity favoring bottom reflected and refracted rays arriving at negative angles. A dipole source directivity is shown to produce the best fit to the data.
Sound transmission loss characteristics of sandwich panel constructions
Authors: Moore J. A. , Lyon R. H.
Published: October 2005

The sound transmission loss (TL) characteristics of panel constructions with thin face sheets and a thicker, lighter core are investigated. Analytical models of TL are developed for constructions with isotropic and orthotropic core materials. The occurrence of acoustic coincidence is described for symmetric and antisymmetric modes of propagation, in the panel. Symmetric propagation involves thickness deformation of the core, while antisymmetric propagation involves a bending deformation of the panel without thickness deformation. For symmetric modes, coincidence occurs near the conventional double wall resonance frequency characterized by the stiffness of the core and the mass of the face sheets, and also at higher frequencies associated with bending wave propagation in the face sheets. Antisymmetric modes account for shear deformation in the core, which results in a softening of the bending rigidity of the panel at higher frequencies. For orthotropic core materials, the acoustic behavior is dependent on the direction of propagation over the surface of the panel. Measured TL results for representative panels show good agreement with predictions. Finally, a procedure for obtaining improved TL performance is described, which involves shifting the double wall resonance to below the frequency band of interest, and limiting the shear stiffness of the core to shift the onset of bending wave coincidence to higher frequencies. Greater than mass law TL, similar to that of conventional double wall constructions, can be achieved over a significant frequency band in the audio range. The mechanical integrity of the panel is provided by the shear stiffness of the core.
Acoustic design of a three-layered plate with high sound interception
Authors: Chonan S. , Kugo Y.
Published: October 2005

This paper presents a study on the transmission characteristics of a three-layered infinite plate excited by a plane acoustic wave. Each layer is described by the two-dimensional elasticity theory. An expression predicting the sound transmission loss as a function of both the frequency and the incidence angle of the acoustic wave is derived and calculated numerically for various combinations of the facing and the core materials. Further, based on the information thus obtained, a method to fabricate a sandwich plate with high sound interception is presented and applied to the design of a plate consisting of a steel core and foamed concrete facings.
Detection of silent temporal gaps in sinusoidal markers
Authors: Formby C. , Forrest T. G.
Published: October 2005

Gap detection thresholds were measured by forced-choice procedure for conditions where the duration of a silent gap was varied adaptively between pairs of sinusoidal markers of the same or different frequency. Frequencies of the first sinusoid in a pair of markers ranged from F1 = 500 to 4000 Hz. Second-sinusoid marker frequencies F2 included F1 = F2, and usually frequencies 2%, 5%, 24%, and 50% higher than F1. In preliminary studies the role of presentation level (E/N0) on gap detection was considered. Preliminary data revealed confounding extraneous factors arising from gating transients and from overall stimulus (i.e., markers + gap) and/or masker duration cues. In the main experiments, the contributions of these extraneous cues were evaluated with experimental designs aimed at identifying and minimizing the confounding roles of these cues in gap detection. For conditions where extraneous gating transient cues were minimized (by presenting the sinusoidal markers in a continuous noise masker with random onset phase for the second sinusoid in every pair of markers) and overall stimulus duration cues were diminished (by randomizing the duration of each marker independently), gap detection thresholds increased from 5 to 90 ms as the frequency separation between F1 and F2 was increased by half an octave. When the gap detection thresholds were treated as filter attenuation values by normalizing and converting the data into decibels, the data were closely fit by the roex filter model. On average, the listeners' performances were modeled well by a constant-percentage (7%) bandwidth filter centered on F1.
Thresholds for segregating a narrow-band from a broadband noise based on interaural phase and level differences
Authors: Yost William A.
Published: October 2005

Either an interaural phase shift or level difference was introduced to a narrow section of broadband noise in order to measure the acuity of the binaural system to segregate a narrow-band from a broadband stimulus. Listeners were asked to indicate whether this dichotic noise or a totally diotic noise was presented in a single-interval procedure. Thresholds for interaural phase and level differences were estimated from four point psychometric functions. These thresholds were determined for three bandwidths of interaurally altered noise (2, 10, and 100 Hz) centered at four center frequencies (200, 500, 1000, and 1600 Hz). Thresholds were lowest when the interaurally altered band of noise was centered at 500 Hz, and thresholds increased as the bandwidth of the interaurally altered noise decreased. Performance did not exceed 75% correct when either an interaural phase shift (180°) or interaural level difference (50 dB) was introduced to a 100 Hz band of noise centered at frequencies higher than 1600 Hz. In a second set of conditions, performance was measured when both an interaural phase shift and level difference were presented in a 10-Hz-wide band of noise centered at 500 Hz. A version of the Durlach E-C model was able to account for a great deal of the data. The results are discussed in terms of the Huggins dichotic pitch.
[s] and [∫] as a function of linguapalatal contact place and sibilant groove width
Authors: Fletcher Samuel G. , Newman Dennis G.
Published: October 2005

Sibilant groove place and width were initially examined during [s] and [∫] in isolation and in CV and VC syllables. The [s] was found to be produced through a 6- to 8-mm-wide groove near the front of the alveolar ridge by one talker and near the back of the ridge by the other. [∫] was produced through a 10- to 12-mm groove behind the posterior border of the alveolar ridge by both. In the second experiment three subjects used visual articulatory feedback to vary sibilant groove width and place systematically. One subject was able to do this with comparatively few retrials; one had difficulty with certain targeted grooves; one had difficulty with many targeted grooves. The noises generated were replayed to 14 listeners who labeled them as “s,” “probably s,” “probably sh,” or “sh.” They usually heard the sound as [s] when the grooves were narrow and near the front of the alveolar process, [∫] when the groove was wider and behind the alveolar process. Noise through grooves that matched natural speech places and widths usually produced higher listener recognition scores. Exceptions were found when the subjects had unusual difficulty in achieving stipulated groove widths and places.
Air-based system for the measurement of porosity
Authors: Champoux Yvan , Stinson Michael R. , Daigle Gilles A.
Published: October 2005

An experimental system for the measurement of porosity, the volume fraction of air contained in a material, is described. Porosity is important as one of several parameters required by acoustical theory to characterize a porous material. As with the technique described by Beranek [J. Acoust. Soc. Am. 13, 248–260 (1942)], the isothermal pressure change in a closed volume containing a sample material is measured for a known change in the volume. The volume of air contained in the sample, and hence the porosity, is inferred from these two quantities. The new system, though, avoids the use of liquids, either directly in the technique or for temperature stabilization. Instead, a piston of accurately known diameter is used to produce the change in volume, and the change in pressure is measured with an electronic pressure transducer. Model calculations and measurements on real materials confirm that porosity can be measured rapidly and conveniently with this apparatus, with an accuracy of better than 1% over a broad range of sample volumes and porosities.
A transducer for blood flow noise from intracranial vascular deformations
Authors: Kobayashi Kenji
Published: October 2005

A blood flow noise transducer for use on the eyes has been designed to take the place of an ordinary accelerometer-type setting on the head skin. The blood flow noise is generally considered to be generated by the turbulent flow in an artery due to deformation of the vascular wall, such as an aneurysm. The present transducer is intended to detect the turbulent flow noise from the intracranial aneurysms clearly by setting the transducer on the eyes. A novel transducer has been constructed using PVDF film, which has a sensitivity of − 63 Db (V/μbar) and a bandwidth of over 2.5 kHz. In clinical applications the transducer has shown fairly good results. Simulated experiments using the transducer with a cranial model suggest that the localization of the sound source can be predicted by data processing.
Critical piezoelectricity in percolation
Authors: Sornette Didier , Lagier Michel , Roux Stéphane
Published: October 2005

The problem of the critical behavior of piezoelectricity in percolating media is introduced for the first time. Its relevance stems from the fact that piezoelectricity associates mechanical and electrical properties whose separated critical behavior have been extensively discussed in the literature. It should also yield useful information on the deformation modes of the structures. This problem is suggested by the recent development of low-density, compliant flexible piezoelectric ceramics used as acoustic transducers. The physical properties of these systems are just beginning to be explored experimentally, and their modelization is an open problem. The limiting case of strong heterogeneousness, where percolation ideas may apply and lead to simple and universal predictions, is addressed. The simplicity of the analysis comes from the clear separation of three scales, the microscopic grain size R, the percolation σ which diverges as the percolation threshold is approached, and the macroscopic size L of the system (R ≪ ξ ≪ L). The main result is that the direct piezoelectric effect exhibits a critical divergence as more and more tenuous compliant porous ceramics are considered.
Partial synchrony in musical sounds: Some recent results using time-variant spectral analysis
Authors: Beauchamp James W. , Maher Robert C.
Published: October 2005

Time-variant techniques have been used to analyze quasiharmonic musical signals in terms of s(t) =  ∑ k 1nck (t)cos(2π∫fk (t)dt + θk). One type of synchronous behavior occurs when each harmonic amplitude obeys a definite monotonic relationship ck = Fk (c1). This appears to be approximately true for nonvibrato reed-instrument tones, with the notable exception of their attack epochs. On the other hand, the functions relating the harmonic amplitudes of flute tones exhibit considerable hysteresis. Another type of synchrony has to do with harmonicity and whether the frequencies of the partials are harmonically locked together so that fk (t) = kf1(t). Partials of vocal tones with ribtaro appear to obey this relationship, but those of oboe tones do not. Examples of the analysis and synthesis of sounds with and without synchronous behavior will be given.
String simulation by means of digital waveguides
Authors: Smith Julius O.
Published: October 2005

Research in digital sound synthesis and reverberation at CCRMA has led to a new approach, called “waveguide synthesis,” in which acoustic traveling waves are explicitly simulated using digital delay lines. So far, the best success has been obtained for one-dimensional wave propagation, such as in woodwinds and strings. The ideal string is simulated using two delay lines, where one delay line carries the left-going traveling-wave component, and the other carries the right-going wave. Realistic strings are obtained by perturbing this lossless prototype using low-order digital filtering in cascade with the delay line. Because strings in musical instruments are close to lossless, it is highly efficient to simulate them as a weak perturbation of a lossless system. This paper reviews the fundamentals of string simulation using digital waveguides.
Musicians' and nonmusicians' sensitivity to differences in music performance
Authors: Sundberg J. , Friberg A. , Fryden L.
Published: October 2005

A set of ordered, context-dependent rules for the automatic transformation of a music score to the corresponding musical performance has been developed, using an analysis-by-synthesis method [J. Sundberg in Generative Processes in Music, edited by J. Sloboda (Clarendon, Oxford, 1987), pp. 52–69]. The rules are implemented in the LeLisp language on a Macintosh microcomputer that controls a synthesizer via a MIDI interface. The rules manipulate sound level, fundamental frequency, vibrato extent, and duration of the tones, though only by a barely audible quantity, so as to avoid exaggerated effects. However, for any rule, the quantity can be varied. The present experiment was carried out in order to find out if the sensitivity to these effects differed between musicians and nonmusicians. Pairs of performances of the same examples were presented in different series, one for each rule. Between the pairs in a series, the performance differences were varied within wide limits and, in the first pair in each series, the difference was great, so as to catch the subject's attention. Subjects were asked to decide whether the two performances were identical. The results showed that musicians had a clearly greater sensitivity. The pedagogical implications of this finding will be discussed.
Acoustic studies of single-crystal high-temperature superconductors
Authors: Golding Brage , Haemmerle W. H. , Schneemeyer L. F.
Published: October 2005

The acoustic properties of single crystals of the high-temperature superconductor YBa2Cu3O7 have been measured at temperatures between 0.1 and 300 K for frequencies near 103 and 109 Hz. In the GHz regime, longitudinal modes have been studied for propagation directions parallel and perpendicular to the c axis. At Tc, there is a discontinuity in the sound velocities and their temperature derivatives from which the anisotropic strain dependences of Tc are obtained. In the kHz regime, resonant excitation of flexural modes in thin reeds of YBa2Cu3O7 crystals has permitted precise measurement of acoustic damping and dispersion. The temperature-dependent damping is characterized by at least five features associated with the relaxation of defects. At temperatures below 1 K, the velocity of sound is consistent with the presence of a broad “glasslike” distribution of tunneling modes.
Ultrasonic studies of sintered YBa2Cu3O6.9 and La2CuO4 single crystals
Authors: Okuda Yuichi
Published: October 2005

Single-phase sintered YBa2Cu3O6.9 exhibits no anomaly in the attenuation around Tc (90 K). On the other hand, its sound velocity shows an anomalous increase just below Tc. This may come from lattice hardening due to the condensation of holes. To clarify the relation between this anomaly and the superconductivity, measurement under 8 Tesla was performed. Exactly the same anomaly was observed at 90 K and nothing happened around 72 K, which is the critical temperature under 8 Tesla. The hardening may not be directly related to the superconductivity of this material. An ultrasonic study of a single crystal of La2CuO4 is being made to investigate its antiferromagnetic property, which may be a key in understanding the new superconductivity. A small peak in the attenuation at TN and a very small anomaly in the sound velocity were observed at 43 MHz. The result of a study on a single crystal of YBa2Cu3O6.9 will also be presented at the conference.
Ultrasonic attenuation and velocity investigation of sinter-forged superconducting YBa2Cu3O7
Authors: Levy M. , Sarma B. K. , Xu M.-F. , Adenwalla S. , Zhao Z. , Robinson Q. , Ketterson J. B.
Published: October 2005

Sinter-forged YBa2Cu3O7 exhibits rotational symmetry about the forging axis with the c axis of 80% of the crystallites aligned within 2° of the forging axis. Attenuation measurements as a function of temperature of longitudinal waves propagating perpendicular to the forging axis exhibit it three broad relative maxima at 70, 180, and 250 K. Attenuation measurements with either longitudinal or transverse waves propagating along the forging axis exhibit only one maximum at about 180 K. The absence of the other two maxima along this orientation indicates that they could be produced by interaction mechanisms that may be associated with the Cu-O planes, while the 180-K maximum may be produced by an isotropic interaction mechanism. Sound velocity measurements show the sinter-forged material to be elastically anisotropic. The temperature dependence of the sound velocity shows distinct hysteresis curves that flatten out if the sample is not warmed above 250 K. Upon cooling, lattice softening is observed to start at temperatures much higher than Tc, and to stop below Tc. [Work supported by ONR at the University of Wisconsin—Milwaukee and by NSF at Northwestern University.]
A study on the formant analysis of Korean monophthongs and their resonance effects in vocal tract
Authors: Shin Hyun Jae , Yoon Suk Wang
Published: October 2005

Twelve Korean monophthongs pronounced by five male vocal musicians with five fundamental frequencies were studied by formant analysis. Fundamental frequencies and their harmonics were considered as the parameters of analysis. This study shows that the first and the second formants are characterized by the resonance of the cavities of pharynx and mouth, respectively. The lip-rounding effect decreases the second formant frequency. The phonemes of /a, ɑ/, /e, ɛ/, and /ə, ʌ/ were not distinguished well in this formant analysis for Korean.
Effects of variation in speaking rate, loudness, and vocalic context on linguapalatal contact patterns in Hindi sibilants
Authors: Dixit R. Prakash , Flege James E.
Published: October 2005

A 96-channel electropalatograph was used to monitor normal, fast, and loud production of sibilants in the nonsense words /bisiÝb/, /basáb/, /busúb/ and /bišíb/, /bašáb/, /bušúb/ spoken in a carrier phrase by a native speaker of Hindi. Results showed the following. (1) Groove width (GW, in number of uncontacted sensors×2 mm) was considerably narrower for /s/ (4.64 mm) than /š/ (9.26 mm). (2) GW for /s/ decreased from normal to fast to loud speech; just the opposite was true for /š/. (3) For both /s/ and /š/, GW was narrower in the context of /a/ than /i/ or /u/; in the latter two, it was narrower in the /u/ context. (4) Anterior-posterior location (APL) of the groove (in number of contacted rows) occurred generally at the second and third rows for /s/ and the fourth and fifth rows for /š/. Consequently, the center of the groove for /s/ was 4 mm anterior to that for /š/ (i.e., the difference in the number of rows×2 mm). (5) APL of the groove for /s/ was more anterior in loud than normal or fast speech; in the latter two, it was more anterior in normal speech. (6) Groove APL for /s/ was more anterior in the context of /a/ than /i/ or /u/; in the latter two, it was more anterior in the context of /i/. (7) For /š/, groove APL was more posterior in fast than normal or loud speech; in the latter two, it was more posterior in loud speech. (8) Groove APL for /š/ shifted more posteriorly from /i/ to /a/ to /u/ context. [Work supported by NIH Grant NS20572.]
A comparison of evaluations by American and Japanese listeners of English spoken by Japanese speakers
Authors: Suzuki Hiroshi , Ohyama Ghen
Published: October 2005

By means of the PARCOR analysis and synthesis technique, various combinations of the three prosodic features, i.e., the duration of each sound, pitch change, and the intensity change of an English sentence uttered by Japanese speakers in typically Japanese fashion were replaced with the same combinations of the prosodic features of the same English sentence read by an American. A group of Americans and a group of Japanese listened to the recording of the modified utterances and judged their English acceptability level, or “Englishness.” For the Americans, pitch seems to play a more important role in such judgments than duration and intensity, while, for the Japanese, pitch is far more important than duration, and intensity seems least important.
Acoustic-phonetic analysis of normal, loud, and Lombard speech in simulated cockpit conditions
Authors: Stanton Bill J. , Allen George D. , Jamieson Leah H.
Published: October 2005

It has long been recognized that raising one's voice causes perceptible changes in the speech signal beyond mere increase in overall intensity. This paper reports the results of an extensive analysis of speech produced in a simulated fighter cockpit environment, with helmet and oxygen mask in place. Eight talkers each produced 56 utterances under three conditions: (1) normal, (2) loud (nominally 10 dB above normal), and (3) Lombard (evoked by 90 dB of pink noise played through a headset). A total of 17 671 phonemes were hand marked for analysis using 18 acoustic features (ten frequency bands, spectral COG, low- and high-frequency spectral tilt, F0, F1–3, and duration). For most speakers, both loud and Lombard conditions showed the following shifts in comparison with the normal condition: (1) For vowels and sonorant consonants, lower (0–500 Hz) and higher (5–8 kHz) frequency bands lost energy relative to the mid (1–4 kHz) frequencies; (2) also for vowels and sonorants, F0, F1, and spectral COG all rose; and (3) for fricatives, affricates, and voiceless stops, lower (0–3 kHz) frequencies lost energy relative to higher (4–8 kHz) frequencies. There was much variation in these effects among talkers. [Work supported by Air Force Institute of Technology.]
Structural resonance influences on flow-induced acoustic amplification
Authors: Flatau Alison
Published: October 2005

An experimental investigation of the influence of structural resonance on the acoustic response to vortex shedding is presented. Flow-induced amplification of acoustic energy is of interest in the field of combustion instability in solid rocket motors. Baffles located at the junction of motor segments can cause generation of flow vortices and amplification of acoustic energy. This investigation examines the hypothesis that an additional amplifier of acoustic energy is provided by the vibratory response of these baffles. Flow through a cylindrical cavity is interrupted by annular baffles that extend radially inward from the cylinder walls. Baffle configurations are controlled to induce various frequencies of vortex shedding. Acoustic pressure and baffle vibratory responses for various combinations of baffle resonance and vortex shedding frequency are recorded using a modal analysis technique. This provides the database used to quantify the influence of vortex shedding frequencies and structural resonance on acoustic pressure amplitudes. A theoretical model of the interactions of different baffle configurations with chamber acoustics is presented and shown to be in general agreement with the acoustic pressure amplitudes measured in the test section. [Work supported by Morton Thiokol, Inc.]
Modeling high-frequency bottom backscattering
Authors: Jackson Darrell R.
Published: October 2005

The recent acquisition of acoustic and geoacoustic data sets relevant to high-frequency bottom backscattering has made it possible to rigorously test models based on the composite roughness and Kirchhoff approximations. Examples will be given to show that these single scattering models have performed well within their expected regimes of validity and have helped improve our understanding of the relative importance of scattering from interface roughness and volume inhomogeneities. Some of the data show, however, that there are bottom types that do not fit within the idealizations of the simpler models. Single scattering approximations become increasingly suspect at small grazing angles, for very rough surfaces, and for volume scattering in soft sediments containing numerous buried scatterers. Improved models should incorporate multiple scattering, layering, and the fractal nature of the interface. [Work supported by ONT and NORDA.]