bluuebunny/crossref_metadata_2025 huggingface dataset:
Rehabilitation with dental prosthesis can increase cerebral regional blood volume
Authors: Miyamoto Ikuya , Yoshida Kazuya , Tsuboi Yoichi , Iizuka Tadahiko
Published: October 2005

Abstract: Treatment with denture for edentulous people is highly important for maintaining quality of life. However, its effect on the brain is unknown. In this experimental study, we hypothesized that dental prosthesis can recover not only the physical condition of mastication system but also the regional brain activity. We evaluated functional brain imaging of edentulous subjects fixed by dental implant prosthesis with clenching tasks by multi‐channel near‐infrared optical topography. Results revealed a significantly (P<0.001; paired t‐test) increased cerebral regional blood volume during maximum voluntary clenching task by implant‐retained prosthesis. There were no statistically significant differences between patients with and without prosthesis in the latency to the maximum regional blood volume after the task. Conclusively, clenching can be effective for increasing cerebral blood volume; accordingly maintenance of normal chewing might prevent the brain from degenerating.
Effects of Δ12‐prostaglandin J2 on bone regeneration and growth factor expression in rats
Authors: Damrongsri Damrong , Geva Sarah , Salvi Giovanni E. , Cooper Lyndon F. , Limwongse Visaka , Offenbacher Steven
Published: October 2005

Objectives: Cyclopentenone prostaglandins have been shown to promote osteoblast differentiation in vitro. The aim of this study was to examine in a rat model the effects of local delivery of Δ12‐prostaglandin J2 (Δ12‐PGJ2) on new bone formation and growth factor expression in (i) cortical defects and (ii) around titanium implants.

Material and methods: Standardized transcortical defects were prepared bilaterally in the femur of 28 male Wistar rats. Ten microliters of Δ12‐PGJ2 at 4 concentrations (10−9, 10−7, 10−5 and 10−3 mol/l) in a collagen vehicle were delivered inside a half‐cylindrical titanium chamber fixed over the defect. Contralateral defects served as vehicle controls. Ten days after surgery, the amount of new bone formation in the cortical defect area was determined by histomorphometry and expression of platelet‐derived growth factor (PDGF)‐A and ‐B, insulin‐like growth factor (IGF)‐I/II, bone morphogenetic protein (BMP)‐2 and ‐6 was examined by immunohistochemistry. In an additional six rats, 24 titanium implants were inserted into the femur. Five microliters of carboxymethylcellulose alone (control) or with Δ12‐PGJ2 (10−5 and 10−3 mol/l) were delivered into surgically prepared beds prior to implant installation.

Results: Δ12‐PGJ2 (10−5 and 10−3 mol/l) significantly enhanced new bone formation (33%, P<0.05) compared with control cortical defects. Delivery of Δ12‐PGJ2 at 10−3 mol/l significantly increased PDGF‐A and ‐B and BMP‐2 and ‐6 protein expression (P<0.05) compared with control defects. No significant difference was found in IGF‐I/II expression compared with controls. Administration of Δ12‐PGJ2 also significantly increased endosteal new bone formation around implants compared with controls.

Conclusion: Local delivery of Δ12‐PGJ2 promoted new bone formation in the cortical defect area and around titanium implants. Enhanced expression of BMP‐2 and ‐6 as well as PDGF‐A and ‐B may be involved in Δ12‐PGJ2‐induced new bone formation.
Characterization and mode of action of an exopolygalacturonase from the hyperthermophilic bacterium Thermotoga maritima
Authors: Kluskens Leon D. , van Alebeek Gert‐Jan W.M. , Walther Jasper , Voragen Alphons G.J. , de Vos Willem M. , van der Oost John
Published: October 2005

An intracellular pectinolytic enzyme, PelB (TM0437), from the hyperthermophilic bacterium Thermotoga maritima was functionally produced in Escherichia coli and purified to homogeneity. PelB belongs to family 28 of the glycoside hydrolases, consisting of pectin‐hydrolysing enzymes. As one of the few bacterial exopolygalacturonases, it is able to remove monogalacturonate units from the nonreducing end of polygalacturonate. Detailed characterization of the enzyme showed that PelB is highly thermo‐active and thermostable, with a melting temperature of 105 °C and a temperature optimum of 80 °C, the highest described to date for hydrolytic pectinases. PelB showed increasing activity on oligosaccharides with an increasing degree of polymerization. The highest activity was found on the pentamer (1000 U·mg−1). In addition, the affinity increased in conjunction with the length of the oligoGalpA chain. PelB displayed specificity for saturated oligoGalpA and was unable to degrade unsaturated or methyl‐esterified oligoGalpA. Analogous to the exopolygalacturonase from Aspergillus tubingensis, it showed low activity with xylogalacturonan. Calculations on the subsite affinity revealed the presence of four subsites and a high affinity for GalpA at subsite +1, which is typical of exo‐active enzymes. The physiological role of PelB and the previously characterized exopectate lyase PelA is discussed.
The chloroplast ClpP complex in Chlamydomonas reinhardtii contains an unusual high molecular mass subunit with a large apical domain
Authors: Majeran Wojciech , Friso Giulia , van Wijk Klaas Jan , Vallon Olivier
Published: October 2005

The composition of the chloroplast‐localized protease complex, ClpP, from the green alga Chlamydomonas reinhardtii was characterized by nondenaturing electrophoresis, immunoblotting and MS. The detected ClpP complex has a native mass of ≈ 540 kDa, which is ≈ 200 kDa higher than ClpP complexes in higher plant chloroplasts, mitochondria or bacteria. The 540‐kDa ClpP complex contains two nuclear‐encoded ClpP proteins (ClpP3 and P5) and five ClpR (R1, R2, R3, R4 and R6) proteins, as well two proteins, ClpP1L and ClpP1H, both probably derived from the plastid clpP1 gene. ClpP1H is 59 kDa and contains a ≈ 30‐kDa insertion sequence (IS1) not found in other ClpP proteins, responsible for the high MW of the complex. Based on comparison with other sequences, IS1 protrudes as an additional domain on the apical surface of the ClpP/R complex, probably preventing interaction with the HSP100 chaperone. ClpP1L is a 25‐kDa protein similar in size to other ClpP proteins and could arise by post‐translational processing of ClpP1H. Chloramphenicol‐chase experiments show that ClpP1L and ClpP1H have a similar half‐life, indicating that both are stable components of the complex. The structure of the ClpP complex is further discussed in conjunction with a phylogenetic analysis of the ClpP/R genes. A model is proposed for the evolution of the algal and plant complex from its cyanobacterial ancestor.
Structures of the O‐polysaccharides and classification of Proteus genomospecies 4, 5 and 6 into respective Proteus serogroups
Authors: Zych Krystyna , Perepelov Andrei V. , Siwiňska Małgorzata , Knirel Yuriy A. , Sidorczyk Zygmunt
Published: October 2005

An acidic branched O‐polysaccharide was isolated by mild acid degradation of the lipopolysaccharide (LPS) of Proteus genomospecies 4 and studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, ROESY and H‐detected 1H,13C HSQC experiments. The following structure of the pentasaccharide repeating unit of the O‐polysaccharide was established, which is unique among Proteus polysaccharide structures:

where Qui3NAc stands for 3‐acetamido‐3,6‐dideoxyglucose. Based on the O‐polysaccharide structure and serological data, we propose classifying Proteus genomospecies 4 into a new, separate Proteus serogroup, O56. A weak cross‐reactivity of Proteus genomospecies 4 antiserum with LPS of Providencia stuartii O18 and Proteus vulgaris OX2 was observed and is discussed in view of a similarity of the O‐polysaccharide structures. Structural and serological investigations showed that Proteus genomospecies 5 and 6 should be classified into the existing Proteus serogroups O8 and O69, respectively.
Response of the Pacific oyster Crassostrea gigas to hypoxia exposure under experimental conditions
Authors: David Elise , Tanguy Arnaud , Pichavant Karine , Moraga Dario
Published: October 2005

The molecular response to hypoxia stress in aquatic invertebrates remains relatively unknown. In this study, we investigated the response of the Pacific oyster Crassostrea gigas to hypoxia under experimental conditions and focused on the analysis of the differential expression patterns of specific genes associated with hypoxia response. A suppression subtractive hybridization method was used to identify specific hypoxia up‐ and downregulated genes, in gills, mantle and digestive gland, after 7–10 days and 24 days of exposure. This method revealed 616 different sequences corresponding to 12 major physiological functions. The expression of eight potentially regulated genes was analysed by RT‐PCR in different tissues at different sampling times over the time course of hypoxia. These genes are implicated in different physiological pathways such as respiration (carbonic anhydrase), carbohydrate metabolism (glycogen phosphorylase), lipid metabolism (delta‐9 desaturase), oxidative metabolism and the immune system (glutathione peroxidase), protein regulation (BTF3, transcription factor), nucleic acid regulation (myc homologue), metal sequestration (putative metallothionein) and stress response (heat shock protein 70). Stress proteins (metallothioneins and heat shock proteins) were also quantified. This study contributes to the characterization of many potential genetic markers that could be used in future environmental monitoring, and could lead to explore new mechanisms of stress tolerance in marine mollusc species.
Analysis of the stability of the spermadhesin PSP‐I/PSP‐II heterodimer
Authors: Campanero‐Rhodes María Asunción , Menéndez Margarita , Sáiz José Luis , Sanz Libia , Calvete Juan José , Solís Dolores
Published: October 2005

Spermadhesins are a family of 12–16 kDa proteins with a single CUB domain. PSP‐I and PSP‐II, the most abundant boar spermadhesins, are present in seminal plasma as a noncovalent heterodimer. Dimerization markedly affects the binding ability of the subunits. Notably, heparin and mannose 6‐phosphate binding abilities of PSP‐II are abolished, indicating that the corresponding binding sites may be located at (or near) the dimer interface. Pursuing the hypothesis that cryptic binding sites in PSP‐I/PSP‐II may be exposed in specific physiological environments, we examined the influence of Zn2+ and acidic pH on the heterodimer stability. According to near‐UV CD spectra, the core native fold is preserved in the presence of physiological concentrations of Zn2+, a cation unusually abundant in boar seminal plasma. However, the thermostability of the heterodimer decreases significantly, as observed by CD and differential scanning calorimetry. The effect is Zn2+‐specific and is reversed by EDTA. Destabilization is also observed at acidic pH. Gel filtration analysis using radioiodinated PSP‐I/PSP‐II reveals that dissociation of the heterodimer at low (nanomolar) protein concentrations is promoted by both Zn2+ and acidic pH. Although the integrity of the heterodimer in seminal plasma seems to be guaranteed by its high concentration, dissociation may be facilitated in the female genital tract because of dilution of the protein in the intraluminal fluids of the cervix and the uterus, and the acidic fluid of the uterotubal junction. Such a mechanism may be relevant in the regulation of uterine immune reactions.
The ‘missing’ young stellar objects in the central parsec of the Galaxy: evidence for star formation in a massive accretion disc and a top-heavy initial mass function
Authors: Nayakshin Sergei , Sunyaev Rashid
Published: October 2005

A few dozen young high-mass stars orbit Sgr A* at distances as short as ∼0.1 pc, where star formation should be quenched by the strong tidal shear from Sgr A*. The puzzling young stellar population is believed to come into existence in one of two ways: (i) ‘normal’ star formation at several tens of parsecs in a very massive star cluster that then spiralled in; or (ii) star formation in situ in a massive self-gravitating disc. We propose to constrain these two scenarios via the expected X-ray emission from young low-mass stars that should have formed alongside the massive stars. To this end we compare the recent Chandra observations of X-ray emission from young stars in the Orion nebula, and the Chandra observations of the Sgr A* field. We show that the cluster spiral-in model is ruled out irrespectively of the initial mass function (IMF) of the young stars. In addition, for the in situ model, we find that no more than a few thousand low-mass stars could have formed alongside the massive stars. This is more than a factor of 10 fewer than expected if these stars were formed with the standard IMF as elsewhere in the Galaxy. The young stars in the Galactic Centre are thus the first solid observational evidence for star formation in active galactic nucleus (AGN) discs and also require the IMF of these stars to be top-heavy. We briefly consider the implications of these results for AGN in general.
Late internal-shock model for bright X-ray flares in gamma-ray burst afterglows and GRB 011121
Authors: Fan Y. Z. , Wei D. M.
Published: October 2005

We explore two possible models which might give rise to bright X-ray flares in gamma-ray burst (GRB) afterglows. One is an external forward-reverse shock model, in which the shock parameters of forward-reverse shocks are taken to be quite different. The other is a so-called ‘late internal-shock model’, which requires a refreshed unsteady relativistic outflow generated after the prompt γ-ray emission. In the forward-reverse shock model, after the time t× at which the reverse shock crosses the ejecta, the flux declines more slowly than (t⊕/t×)−(2+β), where t⊕ denotes the observer's time and β is the spectral index of the X-ray emission. In the ‘late internal-shock model’, decaying slopes much steeper than (t⊕/te,⊕)−(2+β) are possible if the central engine shuts down after te,⊕ and the observed variability time-scale of the X-ray flare is much shorter than te,⊕.

The sharp decline of the X-ray flares detected in GRB 011121, XRF 050406, GRB 050502b and GRB 050730 rules out the external forward-reverse shock model directly and favours the ‘late internal-shock model’. These X-ray flares could thus hint that the central engine has begun to operate again and a new unsteady relativistic outflow is generated just a few minutes after the intrinsic hard burst.
Effects of Thermal Contact Resistance on Transient Thermoelastic Contacts for an Elastic Foundation
Authors: Jang Yong Hoon
Published: October 2005

The paper presents a numerical solution to the problem of a hot rigid indenter sliding over a thermoelastic Winkler foundation with a thermal contact resistance at constant speed. It is shown analytically that no steady-state solution can exist for sufficiently high temperature or sufficiently small normal load or speed, regardless of the thermal contact resistance. However, the steady-state solution may exist in the same situation if the thermal contact resistance is considered. This means that the effect of the large values of temperature difference and small value of force or velocity which occur at no steady state can be lessened due to the thermal contact resistance. When there is no steady state, the predicted transient behavior involves regions of transient stationary contact interspersed with regions of separation regardless of the thermal contact resistance. Initially, the system typically exhibits a small number of relatively large contact and separation regions, but after the initial transient, the trailing edge of the contact area is only established and the leading edge loses contact, reducing the total extent of contact considerably. As time progresses, larger and larger numbers of small contact areas are established, until eventually the accuracy of the algorithm is limited by the discretization used.
Optical Path, Phase, and Interference
Authors: Newburgh Ronald
Published: October 2005

A powerful tool in wave optics is the concept of optical path length, a notion usually introduced with Fermat's principle.1–3 The analysis of Fermat's principle requires the application of the calculus of variations and the concept of an extremum, ideas too advanced for beginning students. However, the concept has proven its usefulness in the analysis4 of interference experiments such as those of Michelson and Fabry-Perot. In this paper we shall show how optical path length can aid in the analysis of a modified two-slit Young experiment.
Adding Vectors with Microsoft Word
Authors: Rauber Joel
Published: October 2005

One can use Microsoft® Word,1 a text word processing program, for quantitative analysis of vector addition. The advantages include the ubiquitous availability of MS Word for students and teachers alike in a variety of settings and its flexibility of usage. This paper describes a simple method of practicing vector addition skills using the drawing package that comes with MS Word. The method provides the student with a convenient hands-on approach to visualizing vector arithmetic that is both geometric (pictorial)and quantitative.
A Treasure Trove of Physics from a Common Source—Automobile Acceleration Data
Authors: Graney Christopher M.
Published: October 2005

What is better than interesting, challenging physics with good data free for the taking to which everyone can relate? That's what is available to anyone who digs into the reams of automobile performance tests that have been available in popular magazines since the 1950s. Opportunities to do and teach interesting physics abound, as evidenced by the frequent appearance of “physics of cars” articles in The Physics Teacher.1–6
Putting the Humanity Back into Quantum Physics
Authors: Normandeau Magdalen
Published: October 2005

The Feb. 16, 2004, edition of the Toronto Globe and Mail carried an article subtitled “Canada fails to teach the drama of science.” From what I have seen, I doubt that this is a shortcoming peculiar to the Great White North. Under pressure to “get through the material,” the tendency is to teach the concepts and theories, without mention of their origin, or at least of the human components of their origin. This is understandable to a certain extent: There seems to be ever more material that we should teach physics majors before sending them off to graduate school or on to the job market. We hope that they will be curious enough, as many of us were, to look into the human factor on their own. This works to some degree, but fails completely when teaching science to nonscience majors.
The “Ten Most Beautiful” Experiments Interpreted by Novice Students
Authors: Carr Kevin M.
Published: October 2005

In 2002, Robert P. Crease polled Physics World readers to determine “the most beautiful physics experiment of all time.”1 While one may argue at length about the resulting Top Ten list of beautiful experiments, they struck me immediately as a possible teaching tool for covering the core topics I teach in my Physics of Everyday Life course for nonscience majors. I was also intrigued and challenged by the notion that the ten experiments could be reasonably carried out by the nonscience students in my course. As an experiment of my own, I decided to devote a significant portion of the Physics of Everyday Life lab requirement to having small groups (two to three students each) research, reproduce, demonstrate, and present a Top Ten experiment of their choosing.
Conceptualizing Ideal Circuit Elements in the AP Physics C Syllabus
Authors: Morse Robert A.
Published: October 2005

Does it ever bother you that emfs, resistors, and inductors add in series, but capacitors add in parallel? Does it bother your students? The AP Physics C syllabus for electricity and magnetism specifies the mathematical models students are expected to not merely memorize but to understand. Over time, my students' questions have made me rethink my conceptual and mathematical understanding of this material to help them efficiently develop reasonable conceptual and mathematical models of E&M. In this paper I describe aspects of this pedagogical rethinking related to four ideal circuit elements. I specify the end state of understanding that I want students to develop, but do not attempt to detail the pedagogical path to that understanding.
Improving Student Comprehension by Thinking About a Topic in Multiple Ways
Authors: Vondracek Mark
Published: October 2005

Mark Vondracek has taught physics at all levels in the Chicago Public Schools and Northwestern University's Center for Talent Development. He is currently teaching at Evanston Township High School.
Nonlinear effects in the dynamics of clouds of bubbles
Authors: Kumar Sanjay , Brennen Christopher E.
Published: October 2005

This paper presents a spectral analysis of the response of a fluid containing bubbles to the motions of a wall oscillating normal to itself. First, a Fourier analysis of the Rayleigh-Plesset equation is used to obtain an approximate solution for the nonlinear effects in the oscillation of a single bubble in an infinite fluid. This is used in the approximate solution of the oscillating wall problem, and the resulting expressions are evaluated numerically in order to examine the nonlinear effects. Harmonic generation results from the nonlinearity. It is observed that the bubble natural frequency remains the dominant natural frequency in the volume oscillations of the bubbles near the wall. On the other hand, the pressure perturbations near the wall are dominated by the first and second harmonics present at twice the natural frequency while the pressure perturbation at the natural frequency of the bubble is inhibited. The response at the forcing frequency and its harmonics is explored along with the variation with amplitude of wall oscillation, void fraction, and viscous and surface tension effects. Splitting and cancellation of frequencies of maximum and minimum response due to enhanced nonlinear effects are also observed.
A new technique of acoustic mode filtering in shallow sea
Authors: Chouhan Harish M. , Anand G. V.
Published: October 2005

A new technique of normal mode filtering in an isovelocity channel using an equispaced linear array is presented. Filtering is achieved by steering nulls in the directions of arrival of the quasiplane wave pairs associated with the normal modes that are to be rejected. A theoretical analysis of the problem is presented for both horizontal and nonhorizontal arrays. The minimum number of array elements and their weighting coefficients are determined for each case. The null-steering technique offers several advantages over other techniques of mode filtering. The weighting coefficients are independent of the array depth. A horizontal or vertical array of 2M − 1 elements with real weighting coefficients or a horizontal array of M elements with complex weighting coefficients is sufficient to select one mode from a set of M modes. There is no constraint on interelement spacing. The filter performance is equally good under all types of bottom conditions. If a horizontal array is deployed, this method of mode filtering can be used in a horizontally stratified channel also. The null-steering method gives perfect filtering if the orientation of the array and the modal wave numbers are known exactly. An analysis of the sensitivity of the mode filter to errors in the assumed values of these parameters is also presented.
Matched-field processing of 200-Hz continuous wave (cw) signals
Authors: Tran Jean-Marie Q. D. , Hodgkiss William S.
Published: October 2005

Based on data collected at sea by the Marine Physical Laboratory's digital acoustic array during a September 1987 experiment in the northeast Pacific, this paper demonstrates that matched-field processing is a viable processing technique at 200 Hz. Two propagation experiment geometries are studied; first, when the source was towed at a speed of 5 kn and at a depth around 100 m; and, second, when the source was deployed 89 nm from the array at three different depths (300, 150, and 20 m). In both cases, the source projected a 200-Hz continuous wave (cw) tone. The sound-speed information derived from the CTD and XBT data collected during the experiment facilitates good acoustic modeling of the cw transmissions with a range-independent normal mode model. The Bartlett and the minimum variance processors are used to compute the range-depth ambiguity surfaces. Although mismatch exists, matched-field processing produces good estimates of the source range for the source tow and fixed station transmissions. The estimation of the source depth appears to be a more difficult task in this data set. The array system has acoustic navigation capabilities that show that the array is tilted with an angle of, at most, 1°. Since such tilt corresponds to an across horizontal displacement of two wavelengths at 200 Hz, it results in significant mismatch and is considered in simulations as well as in the processing of data. Qualitative improvements are observed in the ambiguity surfaces of the MV processor at low-input signal-to-noise ratio for a tilt angle of 0.4°. Finally, matched-field processing is attempted for a 300-km spatial window using the best estimate of the array shape when the source was deployed at 165-km range and 20-m depth. The location of the highest peak in the ambiguity surface is off in range by a convergence zone, thus suggesting slight sound-speed mismatch.
Applying fuzzy set theory to the evaluation of concert halls
Authors: Wu Shuo-xian
Published: October 2005

Classification of concert halls according to their acoustical qualities is important to acousticians. The purpose of this paper is to demonstrate how techniques from fuzzy set theory can be used to combine the values of several parameters in order to arrive at an overall evaluation of concert halls. As an example, a group of objective acoustical descriptors suggested by V. L. Jordan [Appl. Acoust. 14, 253–266 (1981)] is used because these data are conveniently available. Tentative evaluation criteria and weights are given. The ranking for halls given in this paper should be considered only as an illustration of the method.
Elementary stability considerations for bowed-string motion
Authors: Weinreich Gabriel , Caussé René
Published: October 2005

Using the approach first pioneered by Raman, the Helmholtz motion of a bowed string is discussed as a special case of “two-velocity motions,” in which a given point (at which the bow is located) alternates, in the course of a cycle, between two constant velocities. The fact that the bow typically presents a negative resistance to the string during the “slipping” part of the cycle is adduced as a reason for the “duty cycle,” that is, the fraction of the period that corresponds to slipping, to try to become as short as possible. It is shown that, for a string without dissipation or stiffness, this duty cycle can be arbitrarily low for general bow positions; data obtained with the “digital bow” illustrate this behavior. It is shown theoretically, and confirmed with computer simulations, that instabilities arising from the negative slipping resistance cannot be eliminated by assigning a finite positive value to the sticking resistance. The apparent stability of Helmholtz motion observed in real playing situations remains a puzzle.
Estimating radiation conductance of a thickness-drive transducer from electrical driving-point admittance measurements
Authors: Sarkady Antal A. , Neustadt Herbert M. , Chaskelis Henry H.
Published: October 2005

For many thickness-drive transducer applications, it is desirable to have a good estimate of the radiation conductance (or other property based on power output) of the transducer. Generally, however, it is difficult to measure directly transducer power output. It is therefore desirable to have a procedure for estimating radiation conductance from easily measured quantities. The measured quantities used in this paper are electrical admittances at the terminals of the transducer when it is in air, and when in water. The transducer model used to interpret the measured admittance is a lumped-constant equivalent circuit; it has been refined to represent an electrically excited thickness-drive transducer over the frequency range 0.5–40 MHz. Two methods are used to estimate radiation conductance Grad (f), and efficiency. One, the general-case method, gives values of Grad over a wide range of frequencies, the other gives values of Grad only for the special case in which the transducer is at a half-wave resonance. For the general case, a novel procedure, similar to iterative optimization, is used to estimate parameters for the equivalent circuit. Provision is made for estimating a tuning-coil resistance that is frequency dependent. The validity of the two methods is tested by comparing resultant Grad (f) values with those measured by the National Institute of Standards and Technology (formerly National Bureau of Standards). The maximum discrepancy at the lowest transducer resonance is approximately 15% for the small number of transducers on which measurements have at present been made. The transducers studied herein have active elements with characteristic impedance much higher than that of water. Polymer-film transducers are not considered.
A comparison of the absolute sensitivity of damped and undamped megahertz-range compressional ultrasonic transducers
Authors: Hanna Pamela D. , Yost William T. , Cantrell John H.
Published: October 2005

An instrument and a technique for the absolute calibration of megahertz-range compressional wave transducers are reported. The methodology is based on the wave response characteristics of the previously developed submersible electrostatic acoustic transducer (ESAT). Measurements of absolute wave displacement amplitudes of the order of angstroms as a function of frequency are reported for both damped and undamped transducers immersed in water. Calculations of wave pressure, intensity, and corrections for diffraction based on these measurements are also presented.
A fiber-optic, interferometric, acceleration canceling, flexural disk hydrophone
Authors: Brown David A. , Hofler T. , Garrett S. L.
Published: October 2005

A fiber-optic hydrophone consisting of an air backed cylinder with clamped circular end plates bonded to four 8-m-long flat (spiral) wound single mode optical fibers will be described. For a given pressure differential between the inside and outside of the cylinder, the interior and exterior fiber coils on each 4.5-cm-diam, l-mm-thick aluminum disk experience opposite strains. This “push-pull” design induces an optical path length difference in a Michelson interferometer. When subject to acceleration along the cylindrical axis, both disks are deflected in the same direction, producing a positive strain on the outer surface of one disk and an equal, but negative, strain on the outer surface of the other disk. Since the fiber coils on the exterior of the two disks comprise one arm of the interferometer (the interior coils comprise the second arm), the strains cancel. The calculated strain for this four-coil sensor [A. E. H. Love, A Treatise on the Mathematical Theory of Elasticity (Dover, New York, 1944), 4th ed., Sec. 309] and optically measured strain are in good agreement and yield a sensitivity of 0.5 rad/Pa below the plate resonance frequency of 4.5 kHz.
Theoretical analysis of a class V flextensional fiber-optic interferometric hydrophone
Authors: Garrett S. L. , Danielson D. A.
Published: October 2005

When an oblate spheroidal shell having an aspect ratio a/b>(2 − v), where v = Poisson's ratio, is subject to hydrostatic pression, the major (a) and minor (b) axes experience strain of opposite sign [R. A. Clark and E. Reissner, J. Mech. Phys. Solids 6, 63 (1957)]. If two optical fibers, which comprise the arms of an interferometer, are wound around the equatorial and meridional circumferences of the spheroid, pressure changes induce a differential optical phase shift in the interferometer. Calculations of circumferential strain and of the optical pressure sensitivity and buckling pressure of such a sensor will be presented for thin shells (t/b≪b3/a3, where t is the shell thickness). Sample designs based on these calculations will be compared to other fiber-optic sensors of similar dimensions and materials.
Piezoelectric transducer analysis using the transfer matrix method and a new versatile computer code
Authors: Tierce Pascal , Anifrani Koffi , Decarpigny Jean Noel , Hamonic B.
Published: October 2005

The analysis of many simple magnetostrictive or piezoelectric transducers used in underwater acoustics,macrosonics, acoustical imaging, or nondestructive testing can be performed under a classical plane-wave assumption with the help of the transfer matrix approach [G. E. Martin, J. Acoust. Soc. Am. 35, 510 (1963); 36, 136 (1964); 36, 1496 (1964); D. F. McCammon and W. Thompson, Jr., J. Acoust. Soc. Am. 68, 754 (1980)]. Described here is a new versatile computer code, ASTRE, which relies on this approach and which can be run efficiently and interactively on any mainframe, workstation, or PC. In the mathematical model, the transducer is split into homogeneous elastic magnetostrictive or piezoelectric blocks that are cylinders, parallelepipeds, or conical frustra. These blocks are assembled, either in series or in parallel, without any restriction related to the connectivity. Internal losses are included and various terminal radiation or mechanical impedances are available. The harmonic analysis provides the displacement, strain, and stress fields as well as the electrical impedances, the source level, or the receiving sensitivity, depending upon the use. External electronic circuits can be added at the electrical ports, particularly useful in the receiving mode. Several different analyses are described in detail to demonstrate the capabilities of the code.
Piezoelectric thick copolymer for acoustic transducers
Authors: Bauer F. , Boisrayon M. , Richard M. , Massot C.
Published: October 2005

Vinylidene fluoride/trifluoroethylene (VF2/VF3) copolymers with more than 50% of VF2 mole content are of ferroelectric nature. They can be formed into plates from 1 to 500 μ thick from the molten state. Studies conducted at ISL show that such copolymers can be poled to a high level of remnent polarization Pr ⩾7 μC/cm2. They exhibit a high piezoelectric activity, which is suitable for applications in acoustic detection, hydrophones, pressure measurements, etc. Piezoelectric properties are presented and discussed. In order to increase the capabilities and the performance of such copolymers VF2/VF3 with 70% mole content for acoustic transducers, copolymer plates 3 mm thick have been realized and stabilized. The poling process of an active area of 25 cm2 was done by following the ISL process. Piezoelectric copolymer plates were obtained successfully. The characterization and piezoelectric properties d33, kT, dh of such new active piezoelectric elements are presented. The results are discussed.
Transducer nonlinearity theory
Authors: Chou Y. F.
Published: October 2005

One normally regards a transducer as a linear device. However, as the working frequency of nonlinear parametric arrays becomes lower and the parametric arrays nearfield theory becomes popular, the nonlinear effect of a transducer cannot be tolerated and seriously affects the outcome of the parametric measurement. The present theory regards the transducer linearity and nonlinearity in the following ways: First, the so-called “linearity” is the fact that the transducer will induce some quantity of electricity when there is sound pressure applied on the surface of the transducer, and the transducer can be regarded as a static capacitor. As for the nonlinear process of the transducer, the transducer not only induces some quantity of electricity but also vibrates in the direction of the sound wave, so the transducer is regarded not as a static capacitor but as a time-varied capacitor controlled parametrically by the incident sound pressure. The following conclusions are reached: (i) The transducer nonlinearity is independent of the polarization voltage; (2) the transducer nonlinearity is not only related to the difference frequency but also to the primary frequency; (3) it is a function of the first-order sensitivity of the primary frequency; and (4) the transducer nonlinearity also depends on the transducer characteristics and its shape.
Digital signal processing aspects of digital musical Instruments
Authors: Fujimori Jun-ichi , Kato Hirokazu
Published: October 2005

Digital signal processing techniques are being widely used in electronic musical instruments and their accessories. Today's digital musical instruments provide a greater variety of sounds and a more precise control than ever before. However, these instruments lack intuitive, direct controls making them difficult for most musicians to use. Two possible approaches are being considered to reduce their complexity. One is to utilize a powerful MPU for controlling the parameters of the digital signal processing, and the other is to find models of digital signal processing that arc specific to music. In this paper, several techniques are surveyed, especially as applied to musical activities. In particular, some sound alteration methods are examined, leading toward a solution to the problem of the musician-machine interface.
Rendering piano music via a performance model
Authors: Taguti Tomoyasu
Published: October 2005

A note-list approach for automated music performance on the piano is dealt with. First, a music language that provides the means for a high-level, quantitative description of the musical gesture is presented. It is characterized by (1) the organization of notes into a hierarchical data structure, and (2) the parametrization of performance (or interpretive) practice into terms of dynamics, agogics, articulation, shift, and damper motion. In this language, the notes of a given score can be structured in different ways according to one's musical interpretation, and the parametrized performance practice in each category can be given to any substructures. In this respect, an instance of note-list structure is viewed as a “model of performance” where the parametrized performance practices stand for the parameters of the model. Second, certain empirical rules for such “gestural parameters” are discussed in relation to the data analysis of performed music by professional pianists. [Work supported by the Grant in Aid for Scientific Research, Ministry of Education.]
Digital sound researcher's workbench
Authors: Aoyagi Tatsuya , Hirata Keiji
Published: October 2005

The purpose of the ICOTone project is to develop a workstation for computer music. This paper describes the digital signal-processing aspect of the ICOTone system. There are many well-known techniques established for digital sound synthesis/analysis. However, there are few computer systems in which all of the techniques can be used simultaneously and easily. In the area of statistics, the S system is a good example; this was developed at the AT&T Bell Laboratories and is an interactive environment for data analysis and graphics. In the S system, a user can grasp what statistical data really mean very quickly because of the rich command library and the preferable man-machine interaction. The goal here is, roughly speaking, to build a digital sound system that employs the design principle of the S system. Such a system will be a common workbench for digital sound researchers. The system configurations will be shown briefly. At present, the ICOTone system includes SUN workstations, digital audio tape recorders (DAT), and compact disk players (CD). The software is implemented on the SUN workstations, using the X-window facilities.
Calculation of a musical Fourier transform
Authors: Brown Judith C.
Published: October 2005

The discrete Fourier transform is inappropriate for the description of musical sounds in that it calculates frequency components for frequencies separated by the same absolute frequency difference and with the same resolution. Frequencies of musical interest, i.e., the notes of the equal-tempered scale, are geometrically spaced and one would like a resolution of at least a semitone (6% of the center frequency) independent of center frequency. Using a window size varying linearly with frequency over a low and a high region of musical relevance, and with center frequencies logarithmically spaced, a constant Q Fourier transform has been calculated. Applications to sounds generated by a variety of musical instruments will be presented. Since the frequency components of any sound with harmonic partials have the same spacing when plotted against log f, this calculation is promising as a “pattern recognition” method of pitch tracking. Results on the violin and the flute will be presented. [Work supported by a Brachman Hoffman fellowship from Wellesley College.]
A study of the transient sounds of the shakuhaehi based on ARMA modeling with residual excitation
Authors: Toyama Michiko
Published: October 2005

Although the conventional method of linear predictive analysis is quite widely used in speech analysis and synthesis, the model used in such analysis is rather rigid and lacks flexibility in representing and reproducing the wide range of sound quality found in music. In this study, an attempt was made to use the method of ARMA modeling and excitation by the prediction residual signal, rather than by white noise and periodic pulses, especially for the analysis and synthesis of the sounds of the shakuhachi, a type of Japanese flute. Two taped tones, a weak D (293 Hz, apertures closed) and a strong G with “kazaiki” or breath noise (392 Hz, two apertures open) were used to study the characteristics of the noise the transient, and the steady state. The experimental work is focused on the pattern of the residual signal and on the possibility of its use as the excitation signal, replacing the white noise and pulse, in order to produce a variety of musical sounds. As for the modeling, the results indicate that more experimental studies are required.
Regulatory control over hearing conservation programs—The British Columbia experience
Authors: Roberts Margaret E.
Published: October 2005

Regulations requiring hearing conservation measures have been in effect in British Columbia, Canada, for 10 years. All programs are under the supervision of the Workers' Compensation Board staff who ensure that technician training, equipment standards, and follow-up procedures are consistent throughout the province. All data are submitted to the Workers' Compensation Board main computer system. Reports for scheduling and summarizing program results by occupation, firm, and industry are returned to each company. Experience over the past 10 years has shown that cooperation between workers and management, plus coordination and control by a central regulatory body, have provided an atmosphere for the development of a stable and accepted hearing conservation program for British Columbia's industrial workers.
Development of a comprehensive hearing conservation computer system
Authors: Dixon-Ernst Christine , Belk H. D. , Glover Mark , King Emma Pessolano , Sussman Nancy B.
Published: October 2005

Development of a comprehensive hearing conservation computer system on a personal computer was done to facilitate administration of Alcoa's hearing conservation program. This system is based on a personal computer link to both a microprocessor audiometer and mainframe computer. The personal computer is linked to a microprocessor audiometer to perform automated audiometric tests. Test results are immediately analyzed using an algorithm that determines OSHA standard threshold shifts as well as shifts using criteria developed by Alcoa. Results and recommendations are generated in a letter following the test. Reports are made to both medical and IH personnel to assist in administration of the hearing conservation program. Test results are batched monthly via dedicated lines to a mainframe computer at corporate headquarters while complete demographic updates on plant individuals are batched down to the PC. This link to the mainframe provides accurate demographics, and relieves the nurse from data entry and maintains a central file of audiometric results for company-wide data analysis.
Comparison of a nonlinear versus a linear earmuff for prevention of temporary threshold shirt (TTS) from gunfire and user acceptability for speech understanding
Authors: Royster Larry H. , Royster Julia Doswell , Berger Elliott H. , Ward W. Dixon , Nuss Richard A.
Published: October 2005

Students in firearms classes wore either their regular earmuff or a prototype nonlinear earmuff during firing practice. Audiograms were performed before and after firing to detect TTS. Dosimeters were used to measure Leq noise exposures and peak SPLs for two ammunition types (mean peak = 159 dB, standard deviation = 4.1 dB). Individuals shot an average of 110 rounds, with exposure affected by all 10–12 class members. Audiometric results showed no mean TTS for wearers of the linear earmuff, and a small but statistically significant mean TTS at 4, 6, and 8 kHz for wearers of the nonlinear muff (means > 3 dB, standard deviations > 5.5 dB). Although the nonlinear muff was not as protective against higher peak SPLs, students' questionnaire responses showed that they preferred the nonlinear muff for understanding speech, especially students with preexisting hearing loss.
Introduction: Hair cells as integral parts of cochlear mechanics
Authors: Zwislocki Jozef J.
Published: October 2005

The last 20 years brought about a revolution in our concepts of cochlear sound processing. Sound selectivity proved to be much greater in live animals than had been found by Békésy in post-mortem preparations, and the discovery of an active biological process in the cochlea has provided a partial explanation for the difference. The active process seems to have been accounted for by the discovery of an electrically and biochemically controlled motility of the outer hair cells. In addition, the demonstrations that the stereocilia of cochlear hair cells are stiff and the tectorial membrane is compliant by comparison, together with other insights, suggest that the classical model of hair-cell stimulation must be radically modified. A new model has been proposed, which is consistent with the current experimental evidence. The introduction, the two distinguished lectures, and the following invited papers review some key aspects of the still ongoing revolution. They focus on the electromechanical processes in the hair cells, as examined in vitro and in the cochlear environment.
The frequency limits to transduction in hair cells of the turtle cochlea
Authors: Fettiplace Robert
Published: October 2005

During transduction in auditory hair cells, displacements of the hair bundle modulate an inward transducer current; this then evokes a receptor potential that is filtered by the electrical properties of the cell membrane. The frequency characteristics of these steps have been studied by recording membrane currents in isolated turtle hair cells. When the hair bundle is rapidly deflected, the transducer current is activated with a maximum time constant of about 0.1 to 0.2 ms at 23 °C, thus faithfully encoding frequencies below 1 kHz. The ensuing receptor potentials are shaped by a sharply tuned resonance resulting from the interaction of a voltage-dependent Ca2+ current and a Ca2+-activated K+ current. The activation time constant for the K+ current varies inversely with, and largely determines, the resonant frequency of the hair cell in the range 20 to 600 Hz. The time constant of the Ca2+ current (0.3 ms) is rapid compared to the K+ current but must impose a corner frequency of about 500 Hz on transmission across the afferent synapse.