bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hall effect in accelerating and stationary conductors
Authors: Goedecke G. H. , Kanim S. E.
Published: January 2007

The acceleration of the ions in an unconstrained current-carrying conductor in an external magnetic field is shown to be produced solely by an electric field due to a modified Hall effect, despite the fact that the total force on the conductor is proportional to only the magnetic field. The modification of the Hall field from the conventional one is typically of the order of one part in 104 or less, but it is essential to obtain self-consistent results. The same modified Hall electric field results from a single-particle model, a model consisting of two rigid charge distributions, and a plasma model. The latter two models predict the existence and the widths of the surfacelike charge sheaths that are the sources of the Hall electric field. For a conductor held at rest, the three models yield the correct total force of constraint, but an additional assumption must be made in the single-particle and the rigid charge distribution models to obtain the Hall field. The plasma model predicts a unique modified Hall field that differs from that for an unconstrained conductor.
How the potentials in different gauges yield the same retarded electric and magnetic fields
Authors: Heras José A.
Published: January 2007

This paper presents a simple and systematic method for showing how the potentials in the Lorentz, Coulomb, Kirchhoff, velocity, and temporal gauges yield the same retarded electric and magnetic fields. The method uses the appropriate dynamical equations for the scalar and vector potentials to obtain two wave equations whose retarded solutions lead to the electric and magnetic fields. The advantage of this method is that it does not use explicit expressions for the potentials in the various gauges, which are generally simple to obtain for the scalar potential but difficult to calculate for the vector potential. The spurious character of the term generated by the scalar potential in the Coulomb, Kirchhoff, and velocity gauges is noted. The nonspurious character of the term generated by the scalar potential in the Lorenz gauge is emphasized.
Probing a resonant circuit with a PC sound card
Authors: Magno W. C. , de Araújo A. E. P. , Lucena M. A. , Montarroyos E. , Chesman C.
Published: January 2007

We discuss an inexpensive experimental system that enables us to generate and acquire electronic signals using only a personal computer and its sound card to study the resonance of an RLC oscillator circuit.
Measurements of sound propagation in a littoral environment using a vertical synthetic array
Authors: Simpson Harry J. , Frederickson Carl K. , Porse Erik C. , Houston Brian H. , Kraus Larry A. , Liskey Steve W. , Berdoz Alain R. , Frank Philip A. , Stanic Steve
Published: January 2007

Shallow-water propagation experiments were carried out in St. Andrews Bay, Florida. These investigations used a vertical one-dimensional synthetic array measurement system where two hydrophones incrementally mapped the acoustic pressure from 2m below through 2m above the sand-water interface. A broadband (1 to 12kHz) chirp was used to insonify the water channel. The source to receiver distance was varied and included measurements at 20, 30, 50, 70, and 90m. These measurements quantified the acoustic pressure above and below a sandy bottom and the results are presented along with frequency analysis, temporal impulse analysis, and wave number analysis. To obtain a better understanding of the results, the measurements are compared to two numerical models. The first model is a temporal ray path prediction of sound propagation in the water channel. The second model, range-dependent acoustic model (RAM), based on a parabolic equation, predicts the sound propagating in a water channel with a sandy bottom. The experimental results agreed well with both numerical predictions in the water column. However, the measured acoustic energy in the sandy bottom was different from the prediction by RAM, which assumed a smooth air-water and water-bottom interface and a point source.
Evoked-potential recovery during double click stimulation in a whale: A possibility of biosonar automatic gain control
Authors: Supin Alexander Ya. , Nachtigall Paul E. , Breese Marlee
Published: January 2007

False killer whale Pseudorca crassidens auditory brainstem responses (ABR) were recorded using a double-click stimulation paradigm specifically measuring the recovery of the second response (to the test click) as a function of the inter-click interval (ICI) at various levels of the conditioning and test click. At all click intensities, the slopes of recovery functions were almost constant: 0.6–0.8μV per ICI decade. Therefore, even when the conditioning-to-test-click level ratio was kept constant, the duration of recovery was intensity-dependent: The higher intensity the longer the recovery. The conditioning-to-test-click level ratio strongly influenced the recovery time: The higher the ratio, the longer the recovery. The dependence was almost linear using a logarithmic ICI scale with a rate of 25–30dB per ICI decade. These data were used for modeling the interaction between the emitted click and the echo during echolocation, assuming that the two clicks simulated the transmitted and echo clicks. This simulation showed that partial masking of the echo by the preceding emitted click may explain the independence of echo-response amplitude of target distance. However, the distance range where this mechanism is effective depends on the emitted click level: The higher the level, the greater the range.
Suppression of distortion product otoacoustic emissions in the anuran ear
Authors: Meenderink Sebastiaan W. F. , Narins Peter M.
Published: January 2007

When a two-tone stimulus is presented to the ear, so-called distortion product otoacoustic emissions (DPOAEs) are evoked. Adding an interference tone (IT) to these two DPOAE-evoking primaries affects normal DPOAE generation. The “effectiveness“ of interference depends on the frequency of the IT in relation to the primary frequencies and this provides clues about the locus of emission generation within the inner ear. Here results are presented on the effects of ITs on DPOAEs thought to originate from the basilar papilla (BP) of a frog species. It is found that the IT always resulted in a reduction of the recorded DPOAE amplitude: DPOAE enhancement was not observed. Furthermore, iso-suppression curves (ISCs) exhibited two relative minima suggesting that the DPOAEs arise at different loci in the inner ear. These minima occurred at fixed frequencies, which coincided with those primary frequencies that resulted in maxima in DPOAE audiograms. The occurrence of two minima suggests that DPOAEs, which are presumed to originate exclusively from the BP, partially arise from the amphibian papilla as well. Finally, the finding that the minima in the ISCs are independent of the primary or DPOAE frequencies provides support for the notion that the BP functions as a single auditory filter.
Variance analysis of arrival time and amplitude estimates from random speckle signal
Authors: Måsøy Svein-Erik , Angelsen Bjørn , Varslot Trond
Published: January 2007

An aberration estimation algorithm, previously developed in the frequency domain, is implemented in the time domain. The algorithm is used to estimate arrival time and amplitude fluctuations with signals from random scatterers. Simulations have been performed to investigate the variance of the estimates. Stability differences between the two implementations are also explored. Eight body wall models, emulating the human abdominal wall, were used for this purpose. The variance was investigated as a function of the number of independent scatterer realizations, used to obtain an estimate. Such signals may be acquired by imaging moving scatterers, e.g., blood or contrast agent. Alternatively they can be obtained by using different nonoverlapping beams from a sector/linear scan. The results show only minor differences between the two implementations with respect to stability. This means that the algorithm can be readily implemented in the time domain for real-time applications. The standard deviation of arrival time and amplitude fluctuation estimates decrease, when the number of independent signals increase. Using only one signal for estimation produces a relatively high standard deviation, but an iterative transmit-beam aberration correction scheme still converges to a properly corrected focus using between one and four transmit-beam iterations for the investigated aberrators.
Ultrasonic characterization of microstructure evolution during processing
Authors: Yang Liyong , Turner Joseph A. , Li Zheng
Published: January 2007

Many cold-working processes for polycrystalline metals cause alignment of the grains with a single symmetry axis. This type of microstructure is called fiber texture. The existence of a preferred orientation of the grains has a significant influence on the propagation and scattering of ultrasonic waves, which are often used for material inspection. Knowledge of the wave attenuation of such textured materials is of both theoretical and practical interest to nondestructive testing and materials characterization. In this article, the quantitative relations between fiber texture and wave attenuations of hexagonal crystals are presented. The texture is characterized by a Gaussian distribution function that contains a single parameter that governs the transition of the texture from perfectly aligned crystals to statistically isotropic. Under this assumption, the materials of interest have a varying degree of transverse isotropy representative of processing conditions. Simple expressions for the attenuations of the three modes of waves are given in a concise, generalized representation. Finally, numerical results are presented and discussed in terms of the directional, frequency, and texture dependence. The results presented are expected to improve the understanding of the microstructure evolution during thermomechanical processing.
Sound characteristics of big-snout croaker, Johnius macrorhynus (Sciaenidae)
Authors: Lin Yuan C. , Mok Hin K. , Huang Bao Q.
Published: January 2007

The sounds of a big-snout croaker, Johnius macrorhynus, produced under hand-held and voluntary conditions (in a large aquarium and in the field) were compared. Voluntary calls included “purr” and “dual-knocks”, only purrs were produced when the fish was hand-held. The purr is composed of pulses in which the first interpulse interval was six to nine times longer than the other interpulse intervals, which were approximate in duration, and is a unique sound type in the coastal water of Taiwan. Purrs emitted under these conditions did not differ significantly, suggesting that the hand-held sound can be employed to match the sound in the field. These sounds contained energy reaching 5kHz, with two peaks at about 1 and 2kHz—the former being the dominant frequency. First interpulse interval, main interpulse interval, repetition rate of pulse, and pulse duration may serve as the diagnostic characters for the species-specific sound (i.e., purrs). One specimen survived in a large aquarium for 6 months and its vocal activity was monitored. The fish produced fewer dual-knocks than purrs, and purrs were about 11dB louder than dual-knocks emitted in the aquarium. The temporal sequential relationship of these types in the sound of this individual was described.
Separability of seabed reflection and scattering properties in reverberation inversion
Authors: Harrison Chris H. , Nielsen Peter L.
Published: January 2007

Separation of scattering properties (Lambert’s μ) from reflection properties (the reflection loss’ angle derivative α) presents difficulties in the geoacoustic inversion of long range reverberation in isovelocity water, and here it is shown that there is still a problem in a refracting environment. An alternative technique is proposed where reverberation is modified by altering the source or receiver beam pattern, for instance, using a triplet array or ring source, to provide a dipole and monopole pattern. Combinations of these two measures of reverberation then conveniently determine α and μ independently of other unknown quantities from long (or short) range data, in fact even from a single range. In addition the short range ratio of the two quantities determines the critical angle independently. The effects of refraction and other source or receiver beam patterns, including a horizontal beam and a tilted beam, are investigated by using analytical techniques. To enhance the credibility of these findings and demonstrate the benefits of the approach an example is posed as a standard inversion problem using a cost function based on both types of reverberation. Finally the technique is applied to some experimental data by forming simultaneous monopole and dipole beams in the vertical plane.
Wave propagation patterns in a “classical” three-dimensional model of the cochlea
Authors: Boer Egbert de , Nuttall Alfred L. , Shera Christopher A.
Published: January 2007

The generation mechanisms of cochlear waves, in particular those that give rise to otoacoustic emissions (OAEs), are often complex. This makes it difficult to analyze wave propagation. In this paper two unusual excitation methods are applied to a three-dimensional stylized classical nonlinear model of the cochlea. The model used is constructed on the basis of data from an experimental animal selected to yield a smooth basilar-membrane impedance function. Waves going in two directions can be elicited by exciting the model locally instead of via the stapes. Production of DPOAEs was simulated by presenting the model with two relatively strong primary tones, with frequencies f1 and f2, estimating the driving pressure for the distortion product (DP) with frequency 2f1−f2, and computing the resulting DP response pattern – as a function of distance along the basilar membrane. For wide as well as narrow frequency separations the resulting DP wave pattern in the model invariably showed that a reverse wave is dominant in nearly the entire region from the peak of the f2-tone to the stapes. The computed DP wave pattern was further analyzed as to its constituent components with the aim to isolate their properties.
Comparative study of audio spatializers for dual-loudspeaker mobile phones
Authors: Bai Mingsian R. , Shih Geng-Yu , Lee Chih-Chung
Published: January 2007

MPEG-1, layer 3 handsets equipped with dual loudspeakers and three-dimensional audio modules have received much attention in the market of consumer electronics. To create spatial impression during audio reproduction, the head-related transfer function (HRTF) and the crosstalk cancellation system (CCS) are key elements in many audio spatializers. However, there are many factors that one should take into account during the design and implementation stages of an audio spatializer in the handset application. In the paper, a comprehensive study was undertaken to compare various audio spatializers for use with dual-loudspeaker handsets, in the context of inverse filtering strategies. Two deconvolution approaches, the frequency-domain method and the time-domain method, are employed to design the required inverse filters. Different approaches to design audio spatializers with the HRTF, CCS, and their combination are compared. In particular, two modified CCS approaches are suggested. Issues in the implementation phase such as regularization, complex smoothing, and structures of inverse filters are also addressed in the paper. Comprehensive objective and subjective tests were conducted to investigate the aforementioned aspects of audio spatializers. The data obtained from the subjective tests are processed by using the multianalysis of variance to justify statistical significance of the results.
Investigation of an anisotropic tortuosity in a Biot model of ultrasonic propagation in cancellous bone
Authors: Hughes Elinor R. , Leighton Timothy G. , White Paul R. , Petley Graham W.
Published: January 2007

The modeling of ultrasonic propagation in cancellous bone is relevant to the study of clinical bone assessment. Historical experiments revealed the importance of both the viscous effects of bone marrow and the anisotropy of the porous microstructure. Of those propagation models previously applied to cancellous bone, Biot’s theory incorporates viscosity, but has only been applied in isotropic form, while Schoenberg’s anisotropic model does not include viscosity. In this paper we present an approach that incorporates the merits of both models, by utilizing the tortuosity, a key parameter describing pore architecture. An angle-dependent tortuosity for a layered structure is used in Biot’s theory to generate the “Stratified Biot Model” for cancellous bone, which is compared with published bone data. While the Stratified Biot model was inferior to Schoenberg’s model for slow wave velocity prediction, the proposed model improved agreement fast wave velocity at high propagation angles, particularly when sorted for porosity. An attempt was made to improve the fast wave agreement at low angles by introducing an angle-dependent Young’s Modulus, which, while improving the agreement of predicted fast wave velocity at low angles, degraded agreement at high angles. In this paper the utility of the tortuosity in characterizing the architecture of cancellous bone is highlighted.
Steady-spectrum contexts and perceptual compensation for reverberation in speech identification
Authors: Watkins Anthony J. , Makin Simon J.
Published: January 2007

Perceptual compensation for reverberation was measured by embedding test words in contexts that were either spoken phrases or processed versions of this speech. The processing gave steady-spectrum contexts with no changes in the shape of the short-term spectral envelope over time, but with fluctuations in the temporal envelope. Test words were from a continuum between “sir” and “stir.” When the amount of reverberation in test words was increased, to a level above the amount in the context, they sounded more like “sir.” However, when the amount of reverberation in the context was also increased, to the level present in the test word, there was perceptual compensation in some conditions so that test words sounded more like “stir” again. Experiments here found compensation with speech contexts and with some steady-spectrum contexts, indicating that fluctuations in the context’s temporal envelope can be sufficient for compensation. Other results suggest that the effectiveness of speech contexts is partly due to the narrow-band “frequency-channels” of the auditory periphery, where temporal-envelope fluctuations can be more pronounced than they are in the sound’s broadband temporal envelope. Further results indicate that for compensation to influence speech, the context needs to be in a broad range of frequency channels.
Quasistatic nonlinear characteristics of double-reed instruments
Authors: Almeida André , Vergez Christophe , Caussé René
Published: January 2007

This article proposes a characterization of the double reed in quasistatic regimes. The nonlinear relation between the pressure drop, Δp, in the double reed and the volume flow crossing it, q, is measured for slow variations of these variables. The volume flow is determined from the pressure drop in a diaphragm replacing the instrument’s bore. Measurements are compared to other experimental results on reed instrument exciters and to physical models, revealing that clarinet, oboe, and bassoon quasistatic behavior relies on similar working principles. Differences in the experimental results are interpreted in terms of pressure recovery due to the conical diffuser role of the downstream part of double-reed mouthpieces (the staple).
Properties of distortion product otoacoustic emissions and neural suppression tuning curves attributable to the tectorial membrane resonance
Authors: Lukashkin Andrei N. , Smith Judith K. , Russell Ian J.
Published: January 2007

Mechanically coupled cochlear structures are likely to form a resonator with several degrees of freedom. Consequently one can expect complex, frequency-dependent relative movements between these structures, particularly between the tectorial membrane and reticular lamina. Shearing movement between these two structures excites the cochlear receptors. This excitation should be minimal at the frequency of the hypothesized tectorial membrane resonance. In each preparation, simultaneous masking neural tuning curves and distortion product otoacoustic emissions were recorded. The position of the low-frequency minima in the tuning curves, frequency dependence of the emission bandpass structure, and level-dependent phase reversal were compared to determine if they were generated by a common phenomenon, for example the tectorial membrane resonance. The notch in the masking curves and the phase inversion of the emission growth functions at the auditory thresholds are both situated half an octave below the probe frequency and the high-frequency primary, respectively, and show similar frequency dependence. The emission bandpass structure is, however, likely to be generated by a combination of mechanisms with different ones dominating at different stimulus parameters.
Prediction of transmission loss of double panels with a patch-mobility method
Authors: Chazot Jean-Daniel , Guyader Jean-Louis
Published: January 2007

Sound transmission loss through double panels is studied with a patch-mobility approach. An overview of the method is given with details on acoustic and structural patch mobilities. Plate excitation is characterized by blocked patch pressures that take into account room geometry and source location. Hence, panel patch velocities before coupling can be determined and used as excitation in the mobility model. Then a convergence criterion of the model is given. Finally, transmission loss predicted with a patch-mobility method is compared with measurements.
Dolphin (Tursiops truncatus) echoic angular discrimination: Effects of object separation and complexity
Authors: Branstetter Brian K. , Mevissen Sonja J. , Pack Adam A. , Herman Louis M. , Roberts Scott R. , Carsrud Lea K.
Published: January 2007

A bottlenose dolphin was tested on its ability to echoically discriminate horizontal angular differences between arrays of vertically oriented air-filled PVC rods. The blindfolded dolphin was required to station in a submerged hoop 2radialm from the stimuli and indicate if an array with two rods (S+) was to the right or the left of a single rod (S−). The angular separation between the two rods (θw) was held constant within each experiment while the angle between the S+ and the S− stimuli (θb) varied to produce angular differences (Δθ=θb−θw) ranging from 0.25 to 4°. In experiment I, θw was maintained at 2° and in experiment II, θw was maintained at 4°. Resulting 75% correct thresholds (method of constant stimuli) were 1.5 and 0.7°, respectively. The two main findings of this study are: (1) decreasing the number of targets does not aid in localization, and (2) increasing the space between the rods enhances localization. Taken as a whole, the experiments suggest dolphins have a well-developed ability to resolve spatial information through sonar.
The stability of decentralized multichannel velocity feedback controllers using inertial actuators
Authors: Baumann Oliver Nicholas , Elliott Stephen John
Published: January 2007

The application of direct velocity feedback control on vibrating structures is well known to provide additional damping and reduce vibration levels. A number of previously studied control systems use multiple feedback loops with ideal velocity sensors and force actuators. While accelerometer signals may be utilized to accurately estimate velocity, there is rarely a structure off which one may react an ideal force. This paper concentrates on the use of multiple electrodynamic inertial actuators as a means of applying a force. A time domain model of a plate structure with multiple velocity sensors and collocated inertial actuators is derived. This model is then used to optimize the decentralized controller in order to minimize the total kinetic energy of the plate. These results are compared with those obtained with a decentralized controller in which each local loop has the same gain. It is demonstrated that for low control efforts, and hence control gains, both controllers perform almost identically, however at large gains the equal gain controller becomes unstable. The cause of this instability is attributed to the resonance of the inertial actuator. The implications of using multiple inertial actuators is discussed and some experimental results are presented and compared with simulations.
Echo features used by human listeners to discriminate among objects that vary in material or wall thickness: Implications for echolocating dolphins
Authors: DeLong Caroline M. , Au Whitlow W. L. , Stamper Sarah A.
Published: January 2007

Echolocating dolphins extract object feature information from the acoustic parameters of echoes. To gain insight into which acoustic parameters are important for object discrimination, human listeners were presented with echoes from objects used in two discrimination tasks performed by dolphins: Hollow cylinders with varying wall thicknesses (±0.2, 0.3, 0.4, and 0.8mm), and spheres made of different materials (steel, aluminum, brass, nylon, and glass). The human listeners performed as well or better than the dolphins at the task of discriminating between the standard object and the comparison objects on both the cylinders (humans=97.1%; dolphin=82.3%) and the spheres (humans=86.6%; dolphin=88.7%). The human listeners reported using primarily pitch and duration to discriminate among the cylinders, and pitch and timbre to discriminate among the spheres. Dolphins may use some of the same echo features as the humans to discriminate among objects varying in material or structure. Human listening studies can be used to quickly identify salient combinations of echo features that permit object discrimination, which can then be used to generate hypotheses that can be tested using dolphins as subjects.
Individual differences in the masking level difference with a narrowband masker at 500 or 2000Hz
Authors: Buss Emily , Hall, Joseph W. , Grose John H.
Published: January 2007

The masking level difference (MLD) for a narrowband noise masker is associated with marked individual differences. This pair of studies examines factors that might account for these individual differences. Experiment 1 estimated the MLD for a 50Hz wide band of masking noise centered at 500 or 2000Hz, gated on for 400ms. Tonal signals were either brief (15ms) or long (200ms), and brief signals were coincident with either a dip or peak in the masker envelope. Experiment 2 estimated the MLD for both signal and masker consisting of a 50Hz wide bandpass noise centered on 500Hz. Signals were generated to provide only interaural phase cues, only interaural level cues, or both. The pattern of individual differences was dominated by variability in NoSπ thresholds, and NoSπ thresholds were highly correlated across all conditions. Results suggest that the individual differences observed in Experiment 1 were not primarily driven by differences in the use of binaural fine structure cues or in binaural temporal resolution. The range of thresholds obtained for a brief NoSπ tonal signal at 500Hz was consistent with a model based on normalized interaural correlation. This model was not consistent for analogous conditions at 2000Hz.
On the potential limitations of conventional sound metrics in quantifying perception of nonlinearly propagated noise
Authors: Gee Kent L. , Hales Swift S. , Sparrow Victor W. , Plotkin Kenneth J. , Micah Downing J.
Published: January 2007

The use of conventional metrics to quantify the perception of nonlinearly propagated noise has been studied. Gaussian noise waveforms have been numerically propagated both linearly and nonlinearly, and from the resulting waveforms, several metrics are calculated. These metrics are overall, A-, C-, and D-weighted sound pressure levels, perceived noise level, Stevens Mark VII perceived loudness, Zwicker loudness, and sharpness. Informal listening demonstrations indicate that perceived differences in annoyance between linearly and nonlinearly propagated waveforms are substantial. Because the metrics studied seem inadequate in representing the perceived differences, rigorous subjective testing is encouraged to properly quantify and understand these differences.
Use of wind and turbulent stability for classifying mean refraction
Authors: White Michael J. , Swearingen Michelle E.
Published: January 2007

The functional shapes of mean wind and temperature profiles in the boundary layer above the ground depend most strongly on the wind speed and turbulent stability scale size. By use of these two parameters and the wind direction, it is possible to substantially characterize the mean refraction for sound propagation to distances up to about 10 km. This presentation investigates ranges of values and the sensitivity of the vertical effective sound speed profiles to these variations and considers the mean refraction as an objective measure for classifying horizontal propagation.
A HIGH SPEED AND COMPACT MIXED-SIGNAL CMOS FUZZIFIER
Authors: ESMAILI ARASH , KHOEI ABDOLLAH , HADIDI KHAYROLLAH
Published: January 2007

A novel high speed linear tunable transconductor suitable for analog and mixed-signal fuzzy circuits operating in current mode is proposed. Using this OTA, we construct a high speed fuzzifier and implement trapezoidal/triangular functions with all parameters (slope, width, and position) independently and continuously tunable, and excellent for low voltage applications. Computer simulations verify the performance of this circuit, showing high speed (up to 100 MHz) and a high support range (up to 2.5 V).
IMAGE COMPRESSION SYSTEM FOR MOBILE COMMUNICATION: ADVANCEMENT IN THE RECENT YEARS
Authors: REAZ M. B. I. , AKTER M. , MOHD-YASIN F.
Published: January 2007

Mobile communication has a great potential to the users due to fulfilling the dreams of real-time multimedia communication like voice, image, and text. The huge amount of data redundancy in still image should be compressed using exact image compression algorithm (ICA) before transmitting via wireless channel. Thus, an ICA should be adaptive, simple, and cost-effective and suitable for feasible implementation. Hardware implementation of the different algorithms has improved using modern, fast, and cost-effective technologies. The main aim of this paper is to review and demonstrate various ICAs developed based on image transmission via wireless channel as well as their hardware implementation. Finally, this review makes bridge for researchers to the future relative studies between different algorithms and architectures, and stands as a reference point for developing more controlling and flexible structures.
HIGH INPUT AND LOW OUTPUT IMPEDANCE VOLTAGE-MODE LOWPASS, BANDPASS, AND HIGHPASS ACTIVE-R FILTER
Authors: AHMED SHAH NISAR , RATHER MOHAMMAD FAROOQ
Published: January 2007

A novel filtering topology with a single input and three outputs (SITO) employing a single four-terminal current feedback amplifier (CFA) with an external compensation pin, such as AD844, two operational amplifiers (OAs), and as many resistors is presented. The circuit offers the features of simultaneous realization of lowpass (LP), bandpass (BP), and highpass (HP) filtering functions, free from component matching conditions, cascadability due to high input and low output impedances, orthogonal/independent adjustment of the filtering parameters, and low active and passive sensitivities. PSPICE simulation results are included to confirm the theoretical results.
Albumin synthesis in preterm infants on the first day of life studied with [1-13C]leucine
Authors: Bunt Jan Erik H. , Rietveld Trinet , Schierbeek Henk , Wattimena J. L. Darcos , Zimmermann Luc J. I. , van Goudoever Johannes B.
Published: January 2007

Albumin is the major binding protein in the human neonate. Low production of albumin will lower its transport and binding capacity. This is especially important in preterm infants, in whom albumin binds to potentially toxic products such as bilirubin and antibiotics. To study the metabolism of plasma albumin in preterm infants, we administered a 24-h constant infusion of [1-13C]leucine to 24 very low birth weight (VLBW) infants (28.4 ± 0.4 wk, 1,080 ± 75 g) on the first day of life. The caloric intake consisted of glucose only, and therefore amino acids for albumin synthesis were derived from proteolysis. The fractional synthesis rate (FSR) of plasma albumin was 13.9 ± 1.5%/day, and the absolute synthesis rate was 148 ± 17 mg·kg−1·day−1. Synthesis rates were significantly lower ( P < 0.03) in infants showing intrauterine growth retardation. Albumin synthesis increased with increasing SD scores for gestation and weight ( P < 0.05). The FSR of albumin tended to increase by 37% after administration of antenatal corticosteroids to improve postnatal lung function ( P = 0.09). We conclude that liver synthetic capacity is well developed in VLBW infants and that prenatal corticosteroids tend to increase albumin synthesis. Decreased weight gain rates in utero have effects on protein synthesis postnatally.
Multiple routes of chemosensitivity to free fatty acids in humans
Authors: Chalé-Rush Angela , Burgess John R. , Mattes Richard D.
Published: January 2007

Selected free fatty acids (FFAs) are documented effective somatosensory and olfactory stimuli whereas gustatory effects are less well established. This study examined orthonasal olfactory, retronasal olfactory, nasal irritancy, oral irritancy, gustatory, and multimodal threshold sensitivity to linoleic, oleic, and stearic acids. Sensitivity to oxidized linoleic acid was also determined. Detection thresholds were obtained using a three-alternative, forced-choice, ascending concentration presentation procedure. Participants included 22 healthy, physically fit adults sensitive to 6- n-propylthiouracil. Measurable thresholds were obtained for all FFAs tested and in 96% of the trials. Ceiling effects were observed in the remaining trials. Greater sensitivity was observed for multimodal stimulation and lower sensitivity for retronasal stimulation. There were no statistically significant correlations for linoleic acid thresholds between different modalities, suggesting that each route of stimulation contributes independently to fat perception. In summary, 18-carbon FFAs of varying saturation are detected by multiple sensory systems in humans.
Role of transient receptor potential vanilloid 1 receptors in endotoxin-induced airway inflammation in the mouse
Authors: Helyes Zsuzsanna , Elekes Krisztián , Németh József , Pozsgai Gábor , Sándor Katalin , Kereskai László , Börzsei Rita , Pintér Erika , Szabó Árpád , Szolcsányi János
Published: January 2007

Airways are densely innervated by capsaicin-sensitive sensory neurons expressing transient receptor potential vanilloid 1 (TRPV1) receptors/ion channels, which play an important regulatory role in inflammatory processes via the release of sensory neuropeptides. The aim of the present study was to investigate the role of TRPV1 receptors in endotoxin-induced airway inflammation and consequent bronchial hyperreactivity with functional, morphological, and biochemical techniques using receptor gene-deficient mice. Inflammation was evoked by intranasal administration of Escherichia coli lipopolysaccharide (60 μl, 167 μg/ml) in TRPV1 knockout (TRPV1−/−) mice and their wild-type counterparts (TRPV1+/+) 24 h before measurement. Airway reactivity was assessed by unrestrained whole body plethysmography, and its quantitative indicator, enhanced pause (Penh), was calculated after inhalation of the bronchoconstrictor carbachol. Histological examination and spectrophotometric myeloperoxidase measurement was performed from the lung. Somatostatin concentration was measured in the lung and plasma with radioimmunoassay. Bronchial hyperreactivity, histological lesions (perivascular/peribronchial edema, neutrophil/macrophage infiltration, goblet cell hyperplasia), and myeloperoxidase activity were significantly greater in TRPV−/− mice. Inflammation markedly elevated lung and plasma somatostatin concentrations in TRPV1+/+ but not TRPV1−/− animals. In TRPV1−/− mice, exogenous administration of somatostatin-14 (4 × 100 μg/kg ip) diminished inflammation and hyperreactivity. Furthermore, in wild-type mice, antagonizing somatostatin receptors by cyclo-somatostatin (4 × 250 μg/kg ip) increased these parameters. This study provides the first evidence for a novel counterregulatory mechanism during endotoxin-induced airway inflammation, which is mediated by somatostatin released from sensory nerve terminals in response to activation of TRPV1 receptors of the lung. It reaches the systemic circulation and inhibits inflammation and consequent bronchial hyperreactivity.
A psychophysical and electrophysiological analysis of salt taste in Trpv1 null mice
Authors: Treesukosol Yada , Lyall Vijay , Heck Gerard L. , DeSimone John A. , Spector Alan C.
Published: January 2007

Current evidence suggests salt taste transduction involves at least two mechanisms, one that is amiloride sensitive and appears to use apically located epithelial sodium channels relatively selective for Na+ and a second that is amiloride insensitive and uses a variant of the transient receptor potential vanilloid receptor 1 (TRPV1) that serves as a nonspecific cation channel. To provide a functional context for these findings, we trained Trpv1 knockout (KO) and wild-type (WT) C57BL/6J mice ( n = 9 or 10/group) in a two-response operant discrimination procedure and measured detection thresholds to NaCl and KCl with and without amiloride. The KO and WT mice had similar detection thresholds for NaCl and KCl. Amiloride shifted the NaCl sensitivity curve to the same degree in both groups and had virtually no effect on KCl thresholds. In addition, a more detailed analysis of chorda tympani nerve (CT) responses to NaCl, with and without benzamil (Bz, an amiloride analog) treatment revealed that the tonic portion of the CT response of KO mice to NaCl + Bz was absent, but both KO and WT mice displayed some degree of a phasic response to NaCl with and without Bz. Because these transients constitute the entire CT response to NaCl + Bz in Trpv1 KO mice, it is possible that these signals are sufficient to maintain normal NaCl detectabilty in the behavioral task used here. Additionally, there may be other amiloride-insensitive salt transduction mechanisms in taste receptor fields other than the anterior tongue that maintain normal salt detection performance in the KO mice.
Effect of extracellular osmolality on cell volume and resting metabolism in mammalian skeletal muscle
Authors: Antolic AnaMaria , Harrison Rosemarie , Farlinger Chris , Cermak Naomi M. , Peters Sandra J. , LeBlanc Paul , Roy Brian D.
Published: January 2007

The purpose of the present investigation was to establish an in vitro mammalian skeletal muscle model to study acute alterations in resting skeletal muscle cell volume. Isolated, whole muscles [soleus and extensor digitorum longus (EDL)] were dissected from Long-Evans rats and incubated for 60 min in Sigma medium 199 (1 g of resting tension, bubbled with 95% O2-5% O2, 30 ± 2°C, and pH 7.4). Medium osmolality was altered to simulate hyposmotic (190 ± 10 mmol/kg) or hyperosmotic conditions (400 ± 10 mmol/kg), whereas an isosmotic condition (290 ± 10 mmol/kg) served as a control. After incubation, relative water content of the muscle decreased with hyperosmotic and increased with hyposmotic condition in both muscle types ( P < 0.05). The cross-sectional area of soleus type I and type II fibers increased ( P < 0.05) in hyposmotic, whereas hyperosmotic exposure led to no detectable changes. The EDL type II fiber area decreased in the hyperosmotic condition and increased after hyposmotic exposure, whereas no change was observed in EDL type I fibers. Furthermore, exposure to the hyperosmotic condition in both muscle types resulted in decreased muscle ATP and phosphocreatine ( P < 0.05) contents and increased creatine and lactate contents ( P < 0.05) compared with control and hyposmotic conditions. This isolated skeletal muscle model proved viable and demonstrated that altering extracellular osmolality could cause acute alterations in muscle water content and resting muscle metabolism.
Surviving sepsis:bcl-2 overexpression modulates splenocyte transcriptional responses in vivo
Authors: Wagner Tracey H. , Drewry Anne M. , MacMillan Sandra , Dunne W. Michael , Chang Katherine C. , Karl Irene E. , Hotchkiss Richard S. , Cobb J. Perren
Published: January 2007

We hypothesized that spleen microarray gene expression profiles analyzed with contemporary pathway analysis software would provide molecular pathways of interest and target genes that might help explain the effect of bcl-2 on improving survival during sepsis. Two mouse models of sepsis, cecal ligation and puncture and tracheal instillation of Pseudomonas aeruginosa, were tested in both wild-type mice and mice that overexpress bcl-2. Whole spleens were obtained 6 h after septic injury. DNA microarray transcriptional profiles were obtained using the Affymetrix 430A GeneChip, containing 22,690 elements. Ingenuity Pathway Analysis software was used to construct hypothetical transcriptional networks that changed in response to sepsis and expression of the bcl-2 transgene. A conservative approach was used wherein only changes induced by both abdominal and pulmonary sepsis were studied. At 6 h, sepsis induced alterations in the abundance of hundreds of spleen genes, including a number of proinflammatory mediators (e.g., interleukin-6). These sepsis-induced alterations were blocked by expression of the bcl-2 transgene. Network analysis implicated a number of bcl-2-related apoptosis genes, including bcl2L11 ( bim), bcl-2L2 ( bcl-w), bmf, and mcl-1. Sepsis in bcl-2 transgenic animals resulted in alteration of RNA abundance for only a single gene, ceacam1. These findings are consistent with sepsis-induced alterations in the balance of pro- and anti-apoptotic transcriptional networks. In addition, our data suggest that the ability of bcl-2 overexpression to improve survival in sepsis in this model is related in part to prevention of sepsis-induced alterations in spleen transcriptional responses.
The importance of limitations in aerobic metabolism, glycolysis, and membrane excitability for the development of high-frequency fatigue in isolated rat soleus muscle
Authors: Murphy K. T. , Clausen T.
Published: January 2007

We investigated the role of limitations in aerobic metabolism, glycolysis, and membrane excitability for development of high-frequency fatigue in isolated rat soleus muscle. Muscles mounted on force transducers were incubated in buffer bubbled with 5% CO2 and either 95% O2 (oxygenated) or 95% N2 (anoxic) and stimulated at 60 Hz continuously for 30–120 s or intermittently for 120 s. Cyanide (2 mM) and 2-deoxyglucose (10 mM) were used to inhibit aerobic metabolism and both glycolysis and aerobic metabolism, respectively. Excitability was reduced by carbacholine (10 μM), a nicotinic ACh receptor agonist, or ouabain (10 μM), an Na+-K+ pump inhibitor. Membrane excitability was measured by recording M waves. Intracellular Na+ and K+ contents and membrane potentials were measured by flame photometry and microelectrodes, respectively. During 120 s of continuous stimulation, oxygenated and anoxic muscles showed the same force loss. In oxygenated muscles, cyanide did not alter force loss for up to 90 s, whereas 2-deoxyglucose increased force loss (by 19–69%; P < 0.01) from 14 s of stimulation. In oxygenated muscles, 60 s of stimulation reduced force, M wave area, and amplitude by 70–90% ( P < 0.001). Carbacholine or ouabain increased intracellular Na+ content ( P < 0.001), induced a 7- to 8-mV membrane depolarization ( P < 0.001), and accelerated the rate of force loss (by 250–414%) during 30 s of stimulation ( P < 0.001). Similar effects were seen with intermittent stimulation. In conclusion, limitations in glycolysis and subsequently also in aerobic metabolism, as well as membrane excitability but not aerobic metabolism alone, appear to play an important role in the development of high-frequency fatigue in isolated rat soleus muscle.
Adjustable passive length-tension curve in rabbit detrusor smooth muscle
Authors: Speich John E. , Dosier Christopher , Borgsmiller Lindsey , Quintero Kevin , Koo Harry P. , Ratz Paul H.
Published: January 2007

Until the 1990s, the passive and active length-tension ( L-T) relationships of smooth muscle were believed to be static, with a single passive force value and a single maximum active force value for each muscle length. However, recent studies have demonstrated that the active L-T relationship in airway smooth muscle is dynamic and adapts to length changes over a period of time. Furthermore, our prior work showed that the passive L-T relationship in rabbit detrusor smooth muscle (DSM) is also dynamic and that in addition to viscoelastic behavior, DSM displays strain-softening behavior characterized by a loss of passive stiffness at shorter lengths following a stretch to a new longer length. This loss of passive stiffness appears to be irreversible when the muscle is not producing active force and during submaximal activation but is reversible on full muscle activation, which indicates that the stiffness component of passive force lost to strain softening is adjustable in DSM. The present study demonstrates that the passive L-T curve for DSM is not static and can shift along the length axis as a function of strain history and activation history. This study also demonstrates that adjustable passive stiffness (APS) can modulate total force (35% increase) for a given muscle length, while active force remains relatively unchanged (4% increase). This finding suggests that the structures responsible for APS act in parallel with the contractile apparatus, and the results are used to further justify the configuration of modeling elements within our previously proposed mechanical model for APS.
Isoform switching in myofibrillar and excitation-contraction coupling proteins contributes to diminished contractile function in regenerating rat soleus muscle
Authors: Esposito Alessandra , Germinario Elena , Zanin Marika , Palade Philip T. , Betto Romeo , Danieli-Betto Daniela
Published: January 2007

Postnatal development of skeletal muscle occurs through the progressive transformation of diverse biochemical, metabolic, morphological, and functional characteristics from the embryonic to the adult phenotype. Since muscle regeneration recapitulates postnatal development of muscle fiber, it offers an appropriate experimental model to investigate the existing relationships between diverse muscle functions and the expression of key protein isoforms, particularly at the single-fiber level. This study was carried out in regenerating soleus muscle 14 days after injury. At this intermediate stage, the regenerating muscle exhibited a recovery of mass greater than its force generation capacity. The lower specific tension of regenerating muscle suggested intrinsic defective excitation-contraction coupling and/or contractility processes. The presence of developmental isoforms of both the voltage-gated Ca2+channel (α1C) and of ryanodine receptor 3, paralleled by an abnormal caffeine contracture development, confirms the immature excitation-contraction coupling of the regenerating muscle. The defective Ca2+handling could also be confirmed by the lower sarcoplasmic reticulum caffeine sensitivity of regenerating single fibers. Also, regenerating single fibers revealed a lower maximal specific tension, which was associated with the residual presence of embryonic myosin heavy chains. Moreover, the fibers showed a reduced Ca2+sensitivity of myofibrillar proteins, particularly those simultaneously expressing the slow and fast isoforms of troponin C. The present results indicate that the expression of developmental proteins determines the incomplete functional recovery of regenerating soleus.