bluuebunny/crossref_metadata_2025 huggingface dataset:
Neue und etablierte Indikationen der UV‐B‐311‐nm‐Phototherapie
Authors: Berneburg Mark , Brod Corinna , Benedix Frauke , Röcken Martin
Published: October 2005

UV‐B‐Breitband‐Phototherapie (280 – 320 nm) stellt eine effektive und sichere Therapiemöglichkeit für zahlreiche entzündliche Erkrankungen der Haut dar. Neben der UVB‐Breitband‐Phototherapie hat insbesondere die UV‐B‐Schmalspektrum‐Therapie, mit einem Emissionsspektrum zwischen 310 – 315 nm, für die Behandlung der Psoriasis, der atopischen Dermatitis und der Vitiligo zunehmend an Bedeutung gewonnen. Die UV‐B‐Schmalspektrumphototherapie, auch als UV‐B‐311‐nm‐Phototherapie bezeichnet, hat sich in den letzten Jahren auch bei weiteren Erkrankungen, wie Mycosis fungoides, polymorpher Lichtdermatose, Pruritus und GvHD, als effektiv erwiesen. Die unterschiedlichen Effekte der Schmalspektrum‐UV‐B‐Therapie im Vergleich zu anderen etablierten Phototherapien sowie neue und etablierte Indikationen werden in diesem Artikel diskutiert.
Behandlung des therapieresistenten erosiven, oralen Lichen ruber mit extrakorporaler Photopherese (ECP)
Authors: Kunte Christian , Erlenkeuser‐Uebelhoer Istrid , Michelsen Silke , Scheerer‐Dhungel Karla , Plewig Gerd
Published: October 2005

Hintergrund: Der erosive, orale Lichen ruber ist meist sehr therapieresistent. Histologisch und immunpathologisch sind Lichen ruber und lichenoide Graft‐versus‐host‐Erkrankung (GvHD) sehr ähnlich. Die Wirksamkeit der extrakorporalen Photopherese bei der GvHD wurde in einigen Arbeiten beschrieben, ebenso bei chronisch erosivem Lichen ruber in einer Publikation.

Patienten und Methodik: Vier Patienten mit erosivem, oralen Lichen ruber wurden in die Studie eingeschlossen. Die Behandlung erfolgte an zwei aufeinanderfolgenden Tagen (1 Zyklus) in anfänglich zweiwöchigen Abständen. Die Therapieintervalle wurden bei klinischem Ansprechen verlängert.

Ergebnisse: Eine Besserung der klinischen Symptomatik und Schleimhauterscheinungen war bei allen vier Patienten nach sieben bis neun Zyklen zu registrieren. Zahnärztliche Eingriffe führten bei zwei Patienten zu einer temporären Befundverschlechterung, bei einem dieser Patienten ist eine kontinuierliche Therapie erforderlich. Bei zwei Patienten wurde die Behandlung in fast abgeheiltem Zustand wegen des Auftretens unabhängiger Erkrankungen beendet. Bei einer Patientin Beendigung der Therapie nach 19 Zyklen bei kompletter Abheilung, Erscheinungsfreiheit auch neun Monate nach Therapieende. Nebenwirkungen traten nicht auf.

Schlussfolgerung: Die extrakorporale Photopherese ist eine wirkungsvolle Therapie des oralen Lichen ruber, die vor allem wegen der fehlenden Nebenwirkungen eine gute Alternative zu den bislang gängigen Therapien darstellt. Die Behandlung sollte durch die Anwendungen von Lokaltherapeutika unterstützt werden.
Seasonal community structure of macromycetes in Veracruz, Mexico
Authors: Munguia P. , Guzmán G. , Ramírez‐Guillén F.
Published: October 2005

A study of phenological patterns in macromycete communities in Veracruz, Mexico was carried out in order to understand changes in community structure across regions of different vegetation types. Previous studies suggest that similarities in community composition occur when there are similarities in certain geographical and climatological characteristics, however they do not address functional groups or seasonal changes across regions. Macromycete communities in Veracruz showed similar species distribution patterns, but individual assemblages changed structure seasonally, changes that were strongly correlated with rainfall. Interestingly, the number of functional groups (species performing similar ecological functions) was not determined by rainfall, but the distribution of species within functional groups was determined by rainfall. Temperature did not appear to play a role in structuring community diversity at this regional scale. However, temperature and other environmental factors such as pH or light may be the mechanism triggering phenological patterns, and influencing the species pool at localized scales. This work brings new light to fungal community diversity patterns in a largely unknown group of species.
Control of arterial PCO2 by somatic afferents in sheep
Authors: Haouzi Philippe , Chenuel Bruno
Published: October 2005

The ventilatory response to electrically induced rhythmic muscle contractions (ERCs) was studied in six urethane–chloralose‐anaesthetized sheep, while arterial oxygen and carbon dioxide pressure (P and P) and perfusion pressure were maintained constant at the known chemoreception sites. With cephalic P held constant, the response to inhaled CO2 was virtually abolished (0.03 ± 0.04 l min−1 Torr−1). During low‐current ERC, which doubled the metabolic rate ( increased from 192 ± 23 to 317 ± 84 ml min−1, P < 0.01), followed the change in closely (from 5.24 ± 1.81 to −9.27 ± 3.60 l min−1, P < 0.01) in the absence of any chemical error signal occurring at carotid and central chemoreceptor level (Δcephalic P=−0.75 ± 1 Torr). Systemic P decreased by −2.47 ± 1.9 Torr (P < 0.01). Both heart rate and systemic blood pressure increased significantly by 18.6 ± 5.5 beats min−1 and 7.0 ± 9.3 mmHg, respectively. When the CO2 flow to the central circulation was reduced during ERC by blocking venous return ( decreased by 102 ± 45 l min−1, P < 0.01), ventilation was stimulated (from 11.99 ± 4.11 to 13.01 ± 4.63 l min−1, P < 0.05). The opposite effect was observed when the arterial supply was blocked. Finally, raising the CO2 content and flow in the systemic blood did not significantly stimulate ventilation provided that the peripheral and central chemoreceptors were unaware of the changes in blood CO2/H+ composition. Our results support the existence of a system capable of controlling blood P homeostasis when the metabolism increases independently of peripheral and central respiratory chemoreceptors. Information from the skeletal muscles related to the local vascular response provides the central nervous system with a respiratory stimulus proportional to the rate at which gases are exchanged in the muscles, thereby coupling ventilation to the metabolic rate.
A comparison of release kinetics and glutamate receptor properties in shaping rod–cone differences in EPSC kinetics in the salamander retina
Authors: Cadetti Lucia , Tranchina Daniel , Thoreson Wallace B.
Published: October 2005

Synaptic transmission from cones is faster than transmission from rods. Using paired simultaneous recordings from photoreceptors and second‐order neurones in the salamander retina, we studied the contributions of rod–cone differences in glutamate receptor properties and synaptic release rates to shaping postsynaptic responses. Depolarizing steps evoked sustained calcium currents in rods and cones that in turn produced transient excitatory postsynaptic currents (EPSCs) in horizontal and OFF bipolar cells. Cone‐driven EPSCs rose and decayed faster than rod‐driven EPSCs, even when comparing inputs from a rod and cone onto the same postsynaptic neurone. Thus, rod–cone differences in EPSCs reflect properties of individual rod and cone synapses. Experiments with selective AMPA and KA agonists and antagonists showed that rods and cones both contact pharmacologically similar AMPA receptors. Spontaneous miniature EPSCs (mEPSCs) exhibited unimodal distributions of amplitude and half‐amplitude time width and there were no rod–cone differences in mEPSC properties. To examine how release kinetics shape the EPSC, we convolved mEPSC waveforms with empirically determined release rate functions for rods and cones. The predicted EPSC waveform closely matched the actual EPSC evoked by cones, supporting a quantal release model at the photoreceptor synapse. Convolution with the rod release function also produced a good match in rod‐driven cells, although the actual EPSC was often somewhat slower than the predicted EPSC, a discrepancy partly explained by rod–rod coupling. Rod–cone differences in the rates of exocytosis are thus a major factor in producing faster cone‐driven responses in second‐order retinal neurones.
Atypical slow waves generated in gastric corpus provide dominant pacemaker activity in guinea pig stomach
Authors: Hashitani Hikaru , Garcia‐Londoño A. Pilar , Hirst G. David S. , Edwards Frank R.
Published: October 2005

When intracellular recordings were made from the circular layer of the intact muscular wall of the isolated guinea pig gastric corpus, an ongoing regular high frequency discharge of slow waves was detected even though this region lacked myenteric interstitial cells. When slow waves were recorded from preparations consisting of both the antrum and the corpus, slow waves of identical frequency, but with different shapes, were generated in the two regions. Corporal slow waves could be distinguished from antral slow waves by their time courses and amplitudes. Corporal slow waves, like antral slow waves, were abolished by buffering the internal concentration of calcium ions, [Ca2+]i, to low levels, or by caffeine, 2‐aminoethoxydiphenyl borate or the chloride channel blocker DIDS. Corporal preparations demonstrated an ongoing discharge of unitary potentials, as has been found in all other tissues containing interstitial cells. The experiments show that the corpus provides the dominant pacemaker activity which entrains activity in other regions of the stomach and it is suggested that this activity is generated by corporal intramuscular interstitial cells.
Neonatal isolation accelerates the developmental switch in the signalling cascades for long‐term potentiation induction
Authors: Huang Chiung‐Chun , Chou Pei‐Hsuan , Yang Chih‐Hao , Hsu Kuei‐Sen
Published: October 2005

The molecular mechanisms underlying long‐term potentiation (LTP) in the CA1 region of the hippocampus are known to vary with developmental age. The physiological factors regulating this developmental change, however, have not yet been elucidated. Here we show that mild neonatal isolation accelerates the developmental switch in the signalling cascades for hippocampal CA1 LTP induction from a cyclic AMP‐dependent protein kinase (PKA)‐ to a Ca2+/calmodulin‐dependent protein kinase II (CaMKII)‐dependent pattern via the activation of the corticotrophin‐releasing factor (CRF) system. Furthermore, this action appears to be mediated through an increased transcription of the α isoform of the CaMKII (CaMKIIα) gene. We also demonstrate that application of CRF to cultured hippocampal neurones significantly increases the expression of CaMKIIα, which is blocked by the non‐specific CRF receptor antagonist astressin, the specific CRF receptor 1 antagonist NBI 27911, and the PKA inhibitor KT5720, but not by the CRF receptor 2 antagonist K 41498, or the protein kinase C inhibitor, bisindolylmaleimide I. CRF signalling also mediates the normal maturation of LTP. These results suggest a novel role for CRF in regulating early developmental events in the hippocampus, and indicate that, although maternal deprivation is stressful for the neonate, appropriate neonatal isolation can serve to promote an endocrine state that fosters the rate of maturation of the signalling cascades underlying the induction of LTP in the developing hippocampus.
Determination of the elastic constants of isotropic solids by optical heterodyne interferometry
Authors: Bayón A. , Varadé A. , Gascón F.
Published: October 2005

An experimental method based on the application of speckle interferometry is proposed in order to determine the dynamic elastic constants of an isotropic material. A broad frequency spectrum impact is applied to a cylindrical sample and, when this vibrates freely, a heterodyne laser interferometer is used to detect the displacement of a point of the material. Once the sample is suitably excited, the displacement component of interest, either in-plane or out-of-plane, is detected in order to determine its frequency content. A spectral analysis allows the determination of the longitudinal, transverse, and torsional natural frequencies. From this the elastic constants are calculated. The measurement precision is checked experimentally using the same method by means of a third detection.
A membrane motor model for the fast motility of the outer hair cell
Authors: Iwasa K. H.
Published: October 2005

A model is presented for describing the membrane potential-dependent motility of the outer hair cell. This model assumes that the motility is due to conformational changes of motor molecules in the plasma membrane. Two kinds of experimental observations, elasticity of the cell and stretch dependence of the motor molecule, are important for characterize this motility by the model. The motor molecule can be described by a two-state model which has electrical and mechanical components in the free energy. The electrical component is due to the charge transferred across the membrane and the mechanical component is due to a change in membrane area in the two states. It can be shown that the elastic element and the motor element are connected in series. Thus the apparent strain of the cell is represented by the sum of true elastic strain and changes due to motor molecules. This model predicts the amplitude of the movement and the force produced by the motility. The model predicts the force produced under isometric condition is about 0.1 nN/mV, in agreement with values estimated from in vivo conditions. The effect of an elastic load attached to the cell is also discussed.
A framework for assessing the relative efficiency of stimulus sequences in evoked response measurements
Authors: Van Veen Barry D. , Lasky Robert E.
Published: October 2005

A general matrix-based framework for characterizing the performance of cross-correlation techniques for recovering the response to an arbitrary stimulus sequence is presented. In general an infinite number of recovery sequences can be identified for any given stimulus sequence. The recovery sequence that minimizes the noise in the recovered response is derived and the effect of the recovery operation on the noise is analyzed. This general framework is employed to develop analytic expressions for the relative efficiencies of conventional signal averaging and binary MLS based methods for the most commonly used recovery operation and the one that optimizes SNR assuming the background noise is uncorrelated. The results depend on the ratio of response length to MLS minimum pulse interval and the amplitude loss as a function of stimulus rate. Examples based on measured amplitude loss functions for ABR recordings are employed to evaluate the relative efficiencies of MLS techniques. When the noise is uncorrelated conventional signal averaging is from two to five times as efficient as MLS techniques. The relative advantage of averaging is shown to decrease when the noise is dominated by low-frequency components.
Active control of extended acoustic sources in a half-space
Authors: Shepard W. Steve , Cunefare Kenneth A.
Published: October 2005

Many noise sources, such as an electronic transformer, are located on or near an acoustically rigid planar surface, such as a concrete floor. Thus far, however, most of the active noise control research has been based on the free-field assumption. The work presented here investigates the effect the presence of a rigid plane has on the active noise control of an acoustic source with characteristic dimensions comparable to the acoustic wavelength at the frequency of interest. It is shown that when the source is located a distance of one wavelength or more from the plane, the presence of the plane may be neglected. However, the minimum radiated power computed using a free space active analysis can be significantly greater than that predicted using a half space active analysis for distances less than one wavelength. As a result, using the simpler free space analysis techniques leads to less effective control for distances less than one wavelength.
Asymmetric actuation and sensing of a beam using piezoelectric materials
Authors: Charette François , Guigou Catherine , Berry Alain , Plantier Guy
Published: October 2005

This paper presents the development of a theoretical model and an experimental study for the response of a beam actuated by a ceramic piezoelectric on one side with a PVDF piezoelectric on the opposite side acting as a sensor. The two piezoelectric are of different types, may be of arbitrary length, and are positioned independently along the beam. Since the actuation is done by a single piezo on one side of the beam, an asymmetric excitation is applied to the beam that causes simultaneously extensional and flexural displacements. Both piezoelectric elements are considered perfectly bonded to the beam. The variational approach with Hamilton’s principle is used to develop the theoretical model. This formulation, which is energy based, allows one to consider any boundary conditions at the ends of the beam and to take into account the dynamic effects (mass loading and stiffness) of both piezos on the beam response ignored in existing models. Experimental results are presented for the free–free boundary conditions. Those results show good agreement with the theoretical model and prove that the piezo’s modify the mode shapes and natural frequencies of the beam. The changes in the mode shapes can be of vital importance in some applications.
Reduction of plate vibration and acoustic radiation using adaptively controlled boundaries
Authors: Gruenhagen Deborah A. , Burroughs Courtney B. , Sommerfeldt Scott D.
Published: October 2005

Reduction of plate vibration and acoustic radiation at low frequencies using adaptively controlled boundaries is experimentally demonstrated. The control is based on changing the clamping pressure at the boundaries of the plate to continuously detune the plate resonance frequencies from the frequency of pure-tone excitation. Results are presented for the control of plate vibration with constant and varying frequencies of excitation and for the control of acoustic radiation with constant frequency excitation.
On the exterior acoustic radiation modes of structures
Authors: Cunefare Kenneth A. , Currey M. Noelle
Published: October 2005

The use of a modal-style approach for the analysis of the exterior radiation characteristics of structures has recently received increasing attention. This approach generally seeks to find a set of orthogonal functions, or acoustic modes, that diagonalizes a radiation operator. These acoustic modes are found through an eigenfunction or singular value decomposition of the radiation operator. The eigenvalue or singular value associated with a given acoustic mode is directly proportional to the radiation efficiency of that acoustic mode. The acoustic mode represents a particular velocity pattern on the surface of the radiator. As with the analogous problem of finding structural natural frequencies and mode shapes, the accuracy of the acoustic modal representation depends on the number of degrees of freedom in the radiation operator. The radiation efficiency of the most efficient acoustic mode has a finite upper bound, and converges fastest with increasing degrees of freedom. Each additional degree of freedom in a model introduces a new least efficient acoustic mode. In fact, the radiation efficiency of the least efficient acoustic mode may be forced arbitrarily close to zero by introducing sufficient degrees of freedom. The most efficient acoustic modes are least sensitive to perturbations in their velocity patterns, while the least efficient acoustic modes are most sensitive. These characteristics of the exterior modal acoustic representation have significant implications for the use of the modal representation in design, optimization, and active noise control. This paper explores these issues using the example of a finite baffled beam.
Signals, signal processing, and general results
Authors: Birdsall Theodore G. , Metzger Kurt , Dzieciuch Matthew A.
Published: October 2005

Acoustic path lengths in the Heard Island Feasibility Test ranged from under 1 Mm to 18 Mm (1 Mm is 1000 km). The signal set consisted of three basic waveforms: cw, pentaline, and M-sequence-modulated carrier. This set offered the opportunity for successful measurements given the large uncertainty in prior estimates of propagation loss, stability, and arrival spread. Receivers ranged from simple sonobuoy systems to elaborate horizontal and vertical arrays. International collaborators acquired data at a variety of sites worldwide. The resulting data has been collected and subjected to a summary form of frequency domain processing. Variations in the recorded spectral phases are largely the result of nonuniformity in the speed of the source ship as determined by GPS comparison. Time domain processing has shown that at all ranges the receptions exhibit exceptional stability.
Integrated autocorrelation phase at one period lag
Authors: Birdsall Theodore G. , Metzger Kurt , Dzieciuch Matthew A. , Spiesberger John
Published: October 2005

Various types of phase measurements have been introduced into ocean acoustic measurements since the early 1960s, many utilizing the increased precision possible with digital processing. These are usually considered natural and basic by their developers, but are frequently misunderstood and mistrusted by those they were designed to benefit. This paper explains a recent phase technique which was used in the Heard Island Feasibility Test data analysis of the Ascension Island receptions. It revealed that the common phase fluctuations of the wideband M-sequence receptions were not random, but were caused by minor deviations of the source ship track 9200 km away.
Comparison of data and model predictions for Heard Island acoustic transmissions
Authors: McDonald B. Edward , Collins Michael D. , Kuperman W. A. , Heaney Kevin D.
Published: October 2005

Propagation paths and signal characteristics from the Heard Island Feasibility Test are modeled using a combination of adiabatic mode theory, coupled mode theory, and parabolic equation (PE) methods. Adiabatic mode theory predicts the horizontal propagation paths (including small grazing angle reflections from bathymetry), group travel times, and estimates of signal loss due to bottom interaction. The PE calculations are performed primarily to illustrate modal coupling near sharp oceanic fronts and bathymetry intruding into the sound channel. They are carried out in depth and range along selected horizontal ray paths. For the Heard Island to Christmas Island path, we carry out a time domain pulse transmission using coupled mode equations. The result gives a pulse envelope in approximate agreement with observations.
Heard Island Feasibility Test: Analysis of Pacific path data obtained with a horizontal line array
Authors: Heard Garry J. , Chapman N. R.
Published: October 2005

Preliminary results from the Heard Island Feasibility Test are presented for data obtained with a towed horizontal line array off the coast of southern California. Signal characteristics examined include signal-to-noise ratios, sound-pressure levels, transmission loss, and arrival bearing angles. For the transmissions analyzed to date the mean sound-pressure level was found to be (63.8±2) dB//1 μPa. The mean transmission loss was found to be (150±3) dB which is significantly greater than that found for receivers in the Atlantic at similar ranges. The mean arrival angle was found to be (214±3)°T and a travel time of approximately 3 h 17 m was measured. Measurements compare favorably with model predictions which indicate that the relatively large transmission loss is due to bottom interactions in the south western Pacific.
Vertical array receptions of the Heard Island transmissions
Authors: Baggeroer Arthur B. , Sperry Brian , Lashkari Khosrow , Chiu Ching-Sang , Miller James H. , Mikhalevsky Peter N. , von der Heydt Keith
Published: October 2005

A long, vertical line array was deployed off Monterey, California during the Heard Island Feasibility Test to measure the modal content of the received signals. The array contained 32, equally spaced hydrophones spanning from 345 to 1740-m depth. The multichannel data were recorded through a tether to the R/V Point Sur. The measurements had very low signal to noise ratios and indicated the cw transmission losses were approximately 140 dB for a source/receiver range of 17 000 km. Modal content was analyzed using (i) the modal extent versus depth, (ii) frequency-vertical wave-number spectra, (iii) modal beamforming and (iv) least squares fitting. All led to the conclusion that the modal population is surprisingly rich. There was strong evidence of population up to at least mode seven in the data.
Observation of the Heard Island signals near the Gulf Stream
Authors: Fraser Ian A. , Morash Peter D.
Published: October 2005

Transmission-loss and spatial-coherence data were obtained for acoustic signals of center frequency 57 Hz projected from the vicinity of Heard Island in the southern Indian Ocean during the 1991 Heard Island Feasibility Test. The acoustic signals were monitored nearly 17 000 km away from the source by a 1.8-wavelength-long array of hydrophones towed from warm water south of the Gulf Stream to the much colder water north of the Stream. An adiabatic normal mode model predicted acoustic transmission losses in good agreement with those measured in cold water near the Gulf Stream. In warmer water, the measured signal level was generally higher than predicted, possibly because of signal energy scattered from lower to higher modes by boundary scattering. At the most southerly measurement sites, no signal was detected, probably because of bathymetric blockage. The spatial coherence of the signal was limited only by incoherent background noise and occasional interfering signals from discrete directions.
Parametric transformation of sound in systems with strong acoustic nonlinearity
Authors: Nazarov V. E.
Published: October 2005

The paper deals with the parametric transformation of sound in a resonator that is a circular plane-parallel plate submerged in a liquid. When a cylindrical pump wave of the frequency ω interacts with a plane signal wave of the frequency Ω incident on the plate from the liquid, the plate radiates waves of the combination frequencies ωs=2mω±Ω (m is an integer). The calculations performed show that these systems may be used to provide phase conjugation of a signal wave and to develop an aperture parametric receiver.
Closed-form solution for the transient reflected pressure for a point source above an acoustic half-space with an exponentially stratified density
Authors: Cao Jiasu , He Sailing
Published: October 2005

The reflection problem for a transient point source over an acoustic half-space with an exponentially stratified density is considered. A spatial Hankel transform is used to obtain a one-dimensional wave equation. The transient reflected pressure on the surface in the Hankel-transformed space is expressed by a convolution of a reflection kernel and the transformed incident pressure, and the exact expression for the reflection kernel is obtained by means of a Laplace transform. Closed-form solution of the transient reflected pressure in physical space is obtained through an inverse Hankel transform. Closed-form solution for a generalization of the exponential density profile is also given. Numerical examples are given to illustrate these closed-form solutions.
Acoustic scattering by a spherical body near a plane boundary
Authors: Gaunaurd G. C. , Huang H.
Published: October 2005

Acoustic scattering is studied by considering spherical bodies near plane boundaries when they are insonified by plane waves at arbitrary incidence angles. Using the method of images, there is an image sphere on the side of the boundary opposite to the side containing the real sphere, and both the sphere and its image contribute to the resulting sound field. The plane boundary is introduced and the scattering problem is solved. The resulting sound field consists of four parts: the incident field, its reflection from the boundary, the scattered field from the sphere, and that scattered by its image. The whole solution is referred to the center of the real sphere, and any depth below the boundary is possible. The treatment is analytic and exact, and it uses the addition theorems for spherical wave functions and the whole (atomic-physics-like) machinery of the coupling of various angular momentum vectors. The required coupling coefficients bmn emerge from the solution of an infinite linear system of algebraic equations, which is appropriately truncated to obtain numerical predictions for the ‘‘form functions.’’ Form functions that account for either one or two of the four components of the total acoustic field, as well as for the overall effect of all four contributions together, are considered. The two individual components are shown so that the distortions they induce in the field can be separately assessed. All the form functions are displayed versus ka, for various values of the normalized sphere depth d/a. These plots also serve to predict quantitatively the critical depths beyond which the effect of the boundary becomes negligible. They also provide exact benchmark curves against which the accuracy of some approximate techniques, based on the numerical evaluation of certain integral equations can be assessed.
Effect of collagen on the anisotropy of quasi-longitudinal mode ultrasonic velocity in fibrous soft tissues: A comparison of fixed tendon and fixed myocardium
Authors: Hoffmeister Brent K. , Verdonk Edward D. , Wickline Samuel A. , Miller James G.
Published: October 2005

The widespread use of echocardiography has generated considerable interest in the ultrasonic properties of myocardial collagen. This study was designed to investigate the effect of collagen on the propagation of ultrasound by measuring the anisotropy of ultrasonic velocity through formalin fixed specimens of bovine Achilles tendon. Tendon was chosen for this study because it possesses a high content of collagen and a well-defined unidirectional arrangement of fibers. Ultrasonic velocity data were acquired from nine samples of fixed tendon that were each insonified at multiple angles relative to the fibers in 2° increments for a full 360°. Analysis of the data revealed a substantial angular dependence of velocity qualitatively similar to that reported for formalin fixed specimens of normal human myocardium, but approximately 17 times larger in magnitude. Together with measured values of density, these results were used to compute the elastic stiffness coefficients C11 (corresponding to propagation perpendicular to the fibers) and C33 (corresponding to propagation parallel to the fibers) of fixed tendon, yielding 3.08 and 4.51 GPa, respectively.
Sensorimotor model of bat echolocation and prey capture
Authors: Kuc Roman
Published: October 2005

A model of the bat sensorimotor system is developed using acoustics, signal processing, and control theory to illustrate the fundamental issues in accomplishing prey capture with echolocation. This model indicates that successful nonpredictive tracking of an ideal prey can be accomplished with a very simple system. Circular apertures approximate the mouth and ears for deriving acoustic beam patterns, using the big brown bat Eptesicus fuscus as a model. Fundamental and overtone frequency components in the emissions allow two simultaneous acoustic beams to be defined. A pair of nonlinear, time-variable, sampled-data controllers alter the bat’s heading by applying yaw and pitch heading corrections. The yaw correction attempts to position the prey in the midsagittal plane by nulling the interaural intensity difference of the fundamental component. The pitch correction compares the intensities of the overtone and fundamental components and acts to null their difference. By initiating pitch correction when the overtone intensity first exceeds that of the fundamental, the ambiguity problem is solved and the prey is directed to the capture region. Simulations of passive prey capture indicate that the capture probability decreases as the prey speed increases. Both quick and sluggish prey are considered, with sluggish prey found to be caught with slightly better efficiency. The magnitude of the prey’s lateral motion just prior to capture is observed to be an important factor determining capture. The presence of a blind stage is considered, during which the interference of the emission with the echo is assumed to disrupt any sonar information. The presence of such a blind stage is found to have negligible effect on capture efficiency.
Context-dependent Markov model structured by locus equations: Applications to phonetic classification
Authors: Deng Li , Braam Doug
Published: October 2005

In this paper, a quantitative and parametric model is presented that incorporates the role of context-dependent formant transitions in phonetic decoding of speech. The idea is to use the locus equations established from speech science to constrain the model parameters so that the number of parameters for the context-dependent model reduces to the same order as that for the context-independent model. In contrast to the knowledge-based, largely qualitative approaches employing also the formant transition information, our approach allows the parameters of the phonetic classifier, including the locus-equation slopes and intercepts, in conjunction with the hidden Markov model parameters, to be subject to mathematical optimization via an effective and efficient training procedure developed in this study. Detailed analysis of the results obtained from automatic training shows that the estimates of the locus-equation slopes and intercepts are consistent with those manually derived and reported in the speech science literature. Further, the experimental results using a phonetic classifier trained on the TIMIT database demonstrate the effectiveness of our new model, measured by a 15% classification error rate reduction, in comparison with a conventional statistical phonetic classifier under identical training and testing conditions.
Training Japanese listeners to identify English /r/ and /l/. III. Long-term retention of new phonetic categories
Authors: Lively Scott E. , Pisoni David B. , Yamada Reiko A. , Tohkura Yoh’ichi , Yamada Tsuneo
Published: October 2005

Monolingual speakers of Japanese were trained to identify English /r/ and /l/ using Logan et al.’s [J. Acoust. Soc. Am. 89, 874–886 (1991)] high-variability training procedure. Subjects’ performance improved from the pretest to the post-test and during the 3 weeks of training. Performance during training varied as a function of talker and phonetic environment. Generalization accuracy to new words depended on the voice of the talker producing the /r/–/l/ contrast: Subjects were significantly more accurate when new words were produced by a familiar talker than when new words were produced by an unfamiliar talker. This difference could not be attributed to differences in intelligibility of the stimuli. Three and six months after the conclusion of training, subjects returned to the laboratory and were given the post-test and tests of generalization again. Performance was surprisingly good on each test after 3 months without any further training: Accuracy decreased only 2% from the post-test given at the end of training to the post-test given 3 months later. Similarly, no significant decrease in accuracy was observed for the tests of generalization. After 6 months without training, subjects’ accuracy was still 4.5% above pretest levels. Performance on the tests of generalization did not decrease and significant differences were still observed between talkers. The present results suggest that the high-variability training paradigm encourages a long-term modification of listeners’ phonetic perception. Changes in perception are brought about by shifts in selective attention to the acoustic cues that signal phonetic contrasts. These modifications in attention appear to be retrained over time, despite the fact that listeners are not exposed to the /r/–/l/ contrast in their native language environment.
Hearing smiles and frowns in normal and whisper registers
Authors: Tartter Vivien C. , Braun David
Published: October 2005

Two experiments measured listeners’ abilities to detect facial expression in unfamiliar speech in normal and whisper registers. Acoustic differences between speech produced with neutral or marked facial expression were also assessed. Experiment 1 showed that in a forced-choice identification task, listeners could accurately select frowned speech as such, and neutral speech as happier sounding than frowned speech in the same speakers. Listeners were able to judge frowning in the same speakers’ whispered speech. Relative to neutral speech, frowning lowers formant frequencies and increases syllable duration. In both registers, judgments of frowning and its relative happiness were significantly poorer for lip-rounded vowels, suggesting that listeners may recover lip protrusion in making judgments. Experiment 2 replicated the finding [V. Tartter, Percept. Psychophys. 27, 24–27 (1980)] that listeners can select speech produced with a smile as happier sounding than neutral speech in normal register, and extended the findings to whisper register. Relative to neutral, smiling increased second formant frequency. Results are discussed with respect to nonverbal auditory emotion prototypes and with respect to the direct realist theory of speech perception.
Loudness growth in forward masking: Relation to intensity discrimination
Authors: Zeng Fan-Gang
Published: October 2005

The growth of loudness of a tone burst following an intense forward masker was measured as a function of the tone level. The level of the forward-masked tone was adjusted to balance the loudness of a standard tone presented without a forward masker, using a 2AFC, double-staircase, tracking procedure. The forward masker was a 90-dB SPL, 100-ms, 1000-Hz pure tone. The standard tone and the masked tone were both 25-ms, 1000-Hz pure tones. The forward masker and the masked tone were always presented in the first interval. With a 100-ms delay between them, there was little or no threshold elevation for the masked tone. However, the masker caused the masked tone to sound louder than it would if it had not been masked, a phenomenon termed ‘‘loudness enhancement’’ [Irwin and Zwislocki, Percept. Psychophys. 10, 189–192 (1971); Galambos et al., J. Acoust. Soc. Am. 52, 1127–1130 (1972)]. In addition, the present results show a nonmonotonic enhancement function that the forward masker introduced a 10–16-dB enhancement effect for tones of 40–65 dB SPL and no significant effect for the 30 and 90 dB SPL tones. The loudness variability in forward masking was estimated from the upper and lower sequences tracking the 21% and the 79% louder response levels on the psychometric function, respectively. The variability demonstrated a similar nonmonotonic function. In forward masking loudness grows more steeply at low-medium sensation levels, and merges with normal growth at high levels. The relationship between loudness growth and intensity discrimination is also examined. The present study argues that loudness enhancement does not directly contribute to the midlevel hump on the forward-masked intensity discrimination function, but rather that the increase in loudness variability caused by forward masking is responsible for the midlevel hump.
Two-tone suppression in a locally active nonlinear model of the cochlea
Authors: Kanis Luc-J. , de Boer Egbert
Published: October 2005

In auditory nerve, inner-hair cell and basilar-membrane responses, it has been found that the response to one tone can be suppressed by another tone. This phenomenon, called two-tone suppression, is examined on the level of the basilar membrane with a locally active long-wave model of the cochlea in which the active mechanism is nonlinear. The model is solved in the frequency domain by means of a quasilinear solution method. Several phenomena, such as difference in growth of suppression for low-side and high-side suppressors and critical dependence of the phase of the probe response on suppressor parameters, have been replicated. The attenuation hypothesis which states that the presence of a suppressor has the same effect on the probe response as attenuation of probe level is shown to be insufficient in explaining the experimental data. This model, in which suppression is simply reduction of power amplification due to saturation of the active mechanism, is more successful in this respect.
Modeling the fine structure of the 2f1-f2 acoustic distortion product. I. Model development
Authors: Sun Xu-mei , Schmiedt Richard A. , He Ning-ji , Lam Chan F.
Published: October 2005

The fine structure of the 2f1-f2 acoustic distortion product (ADP) as a function of frequency has been measured in human subjects and shows a series of sharp peaks and valleys (rippling) with peak-to-valley level differences of up to 15–20 dB. In order to delineate the cause of the ADP rippling pattern, a computer model was developed to simulate the behavior of the ADP, specifically the ADP fine structure. The ADP model includes the middle ear and cochlea. The middle ear was treated as a simple signal delivery system in both the forward and reverse directions. The ADP was assumed to be generated within the cochlea by nonlinear elements taken to be the outer hair cells (OHCs), and an array of ADP generators was used to simulate the OHCs along the basilar membrane (BM). The magnitude and phase of the output of each of the ADP generators were functions of the local responses of the two primary traveling waves. The traveling waves were calculated from a passive transmission line model of the BM using the WKB approximation, coupled to a second-order resonance to mimic the contribution from active OHC feedback. The system output of ADP in dB was proportional to the weighted vectorial sum of all the components, arriving at the stapes. Parameters such as lateral coupling and feedback gain were examined. From the computer simulation, it appears that the ADP fine structure can be reconstructed by introducing a statistical irregularity to the feedback gain of each generator. Moreover, lateral coupling between the ADP generators is important in determining the overall amplitude of the peak-to-valley ratio in the ADP fine structure.
Modeling the fine structure of the 2f1-f2 acoustic distortion product. II. Model evaluation
Authors: Sun Xu-mei , Schmiedt Richard A. , He Ning-ji , Lam Chan F.
Published: October 2005

In a previous article, a vector sum model was developed that successfully reproduces the ADP rippling pattern when a nonuniformity is introduced in the active damping factor, a parameter that is inversely related to the energy gain contribution of the outer hair cells [OHCs, Sun et al., J. Acoust. Soc. Am. 96, 2166–2174 (1994)]. Here, the mean of the damping factor is increased nonlinearly with input level, mimicking the saturation of the active feedback of the OHCs. The passive damping factor in the transmission line model was also nonlinearly increased with input level to reproduce the frequency shift of the peak of the traveling wave observed in experimental data. The resulting model simulates an ADP that is compatible with data from human subjects wherein the ADP fine structure does not saturate with level. Moreover, the model suggests that the shifting of the ADP pattern with level is a direct result of the peak shift of the traveling wave, thus implicating the nonlinear damping factors as the underlying basis of this phenomenon. The input/output (I/O) functions of the simulated ADP emissions at specific frequencies were also examined. The resulting functions show a variety of shapes, depending on the pattern of ADP fine structure around the I/O frequency, and the way the fine structure shifts as primary levels increase. These I/O functions are also similar to those observed in human subjects, even with regard to overall slopes which approximate one. Thus the model illustrates how cubic distortion generators coupled with damping nonlinearities can yield I/O function slopes on the order of one, rather than the expected three. The effects of OHC damage on ADP emissions were also examined. The simulation results suggest that the ADP profile across frequency under conditions of constant primary intensity is reminiscent of the actual OHC damage; however, the ADP profile can be offset to higher frequencies and can be wider in its frequency extent than that of the actual lesion.
Measurements of the acoustic input impedance of cat ears: 10 Hz to 20 kHz
Authors: Lynch Thomas J. , Peake William T. , Rosowski John J.
Published: October 2005

The acoustic input impedance of the ear is a useful measure of the behavior of the middle ear and of its effect on the acoustics of the external ear. A high-impedance acoustic source with an integral microphone was designed for acoustic-impedance measurements. The source’s Norton equivalent circuit was determined from measurements of the sound pressure it generated in known acoustic loads. Tests on simple acoustic configurations show errors in impedance measurements of less than 10% in magnitude and 7° in angle over a frequency range from 10 Hz to 10 kHz with increasing errors at higher frequencies. Measurements at the tympanic membrane (TM) on five cat ears with widely opened middle-ear cavities show an impedance that is compliance-like below 0.3 kHz and approximately resistive above 2 kHz. With the cavities intact the impedance magnitude is somewhat larger for low frequencies, has a sharp maximum near 4 kHz, and at the highest frequencies is little affected by the state of the cavities. Impedance magnitude varies among ears by a factor of 3. The pressure reflection-coefficient that is determined from the impedance is frequency dependent with magnitude between 0.2 and 1. To characterize the motion transformation of the TM we calculate the ratio of tympanic-membrane volume velocity to the velocity of the mallear umbo, called here the kinematic area ATK. This complex quantity is constant with an angle of zero for frequencies below 0.6 kHz, but at higher frequencies both magnitude and angle of ATK vary with frequency.
Modulation of the hair cell motor: A possible source of odd-order distortion
Authors: Brown Ann M.
Published: October 2005

A recent paper by Nuttall and Dolan [J. Acoust. Soc. Am. 93, 2061–2068 (1993)] on intermodulation distortion in the cochlea concluded that electrical quadratic distortion (f2−f1) came predominantly from inner hair cells (IHCs). However, they suggested that the outer hair cells provided the mechanical input that caused this even-order distortion. The data reported here describe the nonlinear components in the gross electrical and acoustic emission responses of the gerbil and suggest a mechanism by which odd-order distortion could be generated by modulation of the fast phasic motile response of outer hair cells (OHCs) by the even-order distortion signal.
Shell function method for computing the acoustic pressure field in arbitrary inhomogeneous media
Authors: Pan Haitao , Ohtsuki Shigeo
Published: October 2005

The shell function method is presented as a new technique to evaluate the acoustic pressure field produced by a practical source of finite area, in a medium having an arbitrary spatially varying sound speed in three dimensions. Instead of initially subdividing the source surface area into many area elements, the shell function method determines the surface element of source area associated with the ray received at the observation point for a specified travel time. Special attention is given to the deficiency of conventional ray tracing for the case of a caustic, where an infinite pressure is predicted. On the other hand, the shell function method takes into account both the convergent state of a sound beam and the corresponding surface element of the source area. As a consequence, the sound pressure at and in the vicinity of caustics can be given an appropriate value directly. Numerical examples are included to show the computational procedure of the shell function method and the ensuing results.