bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic characterization in whole blood and plasma of site-targeted nanoparticle ultrasound contrast agent for molecular imaging
Authors: Hughes Michael S. , Marsh Jon N. , Hall Christopher S. , Fuhrhop Ralph W. , Lacy Elizabeth K. , Lanza Gregory M. , Wickline Samuel A.
Published: January 2005

The ability to enhance specific molecular markers of pathology with ultrasound has been previously demonstrated by our group employing a nanoparticle contrast agent [Lanza et al., Invest. Radiol. 35, 227–234 (2000); Ultrasound Med. Biol. 23, 863–870 (1997)]. One of the advantages of this agent is very low echogenicity in the blood pool that allows increased contrast between the blood pool and the bound, site-targeted agent. We measured acoustic backscatter and attenuation coefficient as a function of the contrast agent concentration, ambient pressure, peak acoustic pressure, and as an effect of duty cycle and wave form shape. Measurements were performed while the nanoparticles were suspended in either whole porcine blood or plasma. The nanoparticles were only detectable when insonified within plasma devoid of red blood cells and were shown to exhibit backscatter levels more than 30 dB below the backscatter from whole blood. Attenuation of nanoparticles in whole porcine blood was not measurably different from that of whole blood alone over a range of concentrations up to eight times the maximum in vivo dose. The resulting data provide upper bounds on blood pool attenuation coefficient and backscatter and will be needed to more precisely define levels of molecular contrast enhancement that may be obtained in vivo.
The attenuation of the higher-order cross-section modes in a duct with a thin porous layer
Authors: Yin Yean , Horoshenkov Kirill V.
Published: January 2005

A numerical method for sound propagation of higher-order cross-sectional modes in a duct of arbitrary cross-section and boundary conditions with nonzero, complex acoustic admittance has been considered. This method assumes that the cross-section of the duct is uniform and that the duct is of a considerable length so that the longitudinal modes can be neglected. The problem is reduced to a two-dimensional (2D) finite element (FE) solution, from which a set of cross-sectional eigen-values and eigen-functions are determined. This result is used to obtain the modal frequencies, velocities and the attenuation coefficients. The 2D FE solution is then extended to three-dimensional via the normal mode decomposition technique. The numerical solution is validated against experimental data for sound propagation in a pipe with inner walls partially covered by coarse sand or granulated rubber. The values of the eigen-frequencies calculated from the proposed numerical model are validated against those predicted by the standard analytical solution for both a circular and rectangular pipe with rigid walls. It is shown that the considered numerical method is useful for predicting the sound pressure distribution, attenuation, and eigen-frequencies in a duct with acoustically nonrigid boundary conditions. The purpose of this work is to pave the way for the development of an efficient inverse problem solution for the remote characterization of the acoustic boundary conditions in natural and artificial waveguides.
Lexical frequency and neighborhood density effects on the recognition of native and Spanish-accented words by native English and Spanish listeners
Authors: Imai Satomi , Walley Amanda C. , Flege James E.
Published: January 2005

This study examined the effect of presumed mismatches between speech input and the phonological representations of English words by native speakers of English (NE) and Spanish (NS). The English test words, which were produced by a NE speaker and a NS speaker, varied orthogonally in lexical frequency and neighborhood density and were presented to NE listeners and to NS listeners who differed in English pronunciation proficiency. It was hypothesized that mismatches between phonological representations and speech input would impair word recognition, especially for items from dense lexical neighborhoods which are phonologically similar to many other words and require finer sound discrimination. Further, it was assumed that L2 phonological representations would change with L2 proficiency. The results showed the expected mismatch effect only for words from dense neighborhoods. For Spanish-accented stimuli, the NS groups recognized more words from dense neighborhoods than the NE group did. For native-produced stimuli, the low-proficiency NS group recognized fewer words than the other two groups. The-high proficiency NS participants’ performance was as good as the NE group’s for words from sparse neighborhoods, but not for words from dense neighborhoods. These results are discussed in relation to the development of phonological representations of L2 words. (200 words).
Modal analysis and intensity of acoustic radiation of the kettledrum
Authors: Tronchin Lamberto
Published: January 2005

The acoustical features of kettledrums have been analyzed by means of modal analysis and acoustic radiation (p/v ratio) measurements. Modal analysis of two different kettledrums was undertaken, exciting the system both by a hammer and a shaker. Up to 15 vibrational modes were clearly identified. Acoustic radiation was studied using two ways. Based on previous experiments of other researchers, a new parameter, called intensity of acoustic radiation (IAR), has been defined and measured. Results show a strict relationship between IAR and the frequency response function (FRF, which is the v/F ratio), and IAR also strongly relates the modal pattern to acoustic radiation. Finally, IAR is proposed for vibro-acoustical characterization of kettledrums and other musical instruments such as strings, pianos, and harpsichords.
Measurement and modeling of three-dimensional sound intensity variations due to shallow-water internal waves
Authors: Badiey Mohsen , Katsnelson Boris G. , Lynch James F. , Pereselkov Serguey , Siegmann William L.
Published: January 2005

Broadband acoustic data (30–160 Hz) from the SWARM’95 experiment are analyzed to investigate acoustic signal variability in the presence of ocean internal waves. Temporal variations in the intensity of the received signals were observed over periods of 10 to 15 min. These fluctuations are synchronous in depth and are dependent upon the water column variability. They can be explained by significant horizontal refraction taking place when the orientation of the acoustic track is nearly parallel to the fronts of the internal waves. Analyses based on the equations of vertical modes and horizontal rays and on a parabolic equation in the horizontal plane are carried out and show interesting frequency-dependent behavior of the intensity. Good agreement is obtained between theoretical calculations and experimental data.
Mathematical model for characterizing noise transmission into finite cylindrical structures
Authors: Li Deyu , Vipperman Jeffrey S.
Published: January 2005

This work presents a theoretical study of the sound transmission into a finite cylinder under coupled structural and acoustic vibration. Particular attention of this study is focused on evaluating a dimensionless quantity, “noise reduction,” for characterizing noise transmission into a small cylindrical enclosure. An analytical expression of the exterior sound pressure resulting from an oblique plane wave impinging upon the cylindrical shell is first presented, which is approximated from the exterior sound pressure for an infinite cylindrical structure. Next, the analytical solution of the interior sound pressure is computed using modal-interaction theory for the coupled structural acoustic system. These results are then used to derive the analytical formula for the noise reduction. Finally, the model is used to predict and characterize the sound transmission into a ChamberCore cylindrical structure, and the results are compared with experimental data. The effects of incidence angle and internal acoustic damping on the sound transmission into the cylinder are also parametrically studied.
High-frequency ultrasound scattering from microspheres and single cells
Authors: Baddour R. E. , Sherar M. D. , Hunt J. W. , Czarnota G. J. , Kolios M. C.
Published: January 2005

Assessing the proportion of biological cells in a volume of interest undergoing structural changes, such as cell death, using high-frequency ultrasound (20–100 MHz), requires the development of a theoretical model of scattering by any arbitrary cell ensemble. A prerequisite to building such a model is to know the scattering by a single cell in different states. In this paper, a simple model for the high-frequency acoustic scattering by one cell is proposed. A method for deducing the backscatter transfer function from a single, subresolution scatterer is also devised. Using this method, experimental measurements of backscatter from homogeneous, subresolution polystyrene microspheres and single, viable eukaryotic cells, acquired across a broad, continuous range of frequencies were compared with elastic scattering theory and the proposed cell scattering model, respectively. The resonant features observed in the backscatter transfer function of microspheres were found to correspond accurately to theoretical predictions. Using the spacing of the major spectral peaks in the transfer functions obtained experimentally, it is possible to predict microsphere diameters with less than 4% error. Such good agreement was not seen between the cell model and the measured backscatter from cells. Possible reasons for this discrepancy are discussed.
Lip kinematics in long and short stop and fricative consonants
Authors: Löfqvist Anders
Published: January 2005

This paper examines lip and jaw kinematics in the production of labial stop and fricative consonants where the duration of the oral closure/constriction is varied for linguistic purposes. The subjects were speakers of Japanese and Swedish, two languages that have a contrast between short and long consonants. Lip and jaw movements were recorded using a magnetometer system. Based on earlier work showing that the lips are moving at a high velocity at the oral closure, it was hypothesized that speakers could control closure/constriction duration by varying the position of a virtual target for the lips. According to this hypothesis, the peak vertical position of the lower lip during the oral closure/constriction should be higher for the long than for the short consonants. This would result in the lips staying in contact for a longer period. The results show that this is the case for the Japanese subjects and one Swedish subject who produced non-overlapping distributions of closure/constriction duration for the two categories. However, the peak velocity of the lower lip raising movement did not differ between the two categories. Thus if the lip movements in speech are controlled by specifying a virtual target, that control must involve variations in both the position and the timing of the target.
Nonlinear focusing of acoustic shock waves at a caustic cusp
Authors: Marchiano Régis , Coulouvrat François , Thomas Jean-Louis
Published: January 2005

The present study investigates the focusing of acoustical weak shock waves incoming on a cusped caustic. The theoretical model is based on the Khokhlov–Zabolotskaya equation and its specific boundary conditions. Based on the so-called Guiraud’s similitude law for a step shock, a new explanation about the wavefront unfolding due to nonlinear self-refraction is proposed. This effect is shown to be associated not only to nonlinearities, as expected by previous authors, but also to the nonlocal geometry of the wavefront. Numerical simulations confirm the sensitivity of the process to wavefront geometry. Theoretical modeling and numerical simulations are substantiated by an original experiment. This one is carried out in two steps. First, the canonical Pearcey function is synthesized in linear regime by the inverse filter technique. In the second step, the same wavefront is emitted but with a high amplitude to generate shock waves during the propagation. The experimental results are compared with remarkable agreement to the numerical ones. Finally, applications to sonic boom are briefly discussed.
A note on pure-tone masking by broadband noise under free-field and insert-phone conditions (L)
Authors: Houtsma Adrianus J. M.
Published: January 2005

Free-field experiments on masking of low-frequency tones by broadband noise, as reported by Fidell, et al. [J. Acoust. Soc. Am. 73, 628–638 (1983)] should, in principle, yield the same results as the recently reported insert-phone experiment by Houtsma [J. Acoust. Soc. Am. 115, 967–970 (2004)]. Indeed, if Fidell et al.’s data are converted to critical ratios and compared with the recent insert-earphone results, both turn out to be quite similar and significantly different from Hawkins and Stevens’ classical critical ratio results.
Effective impedance spectra for predicting rough sea effects on atmospheric impulsive sounds
Authors: Boulanger Patrice , Attenborough Keith
Published: January 2005

Two methods of calculating the effective impedance spectra of acoustically hard, randomly rough, two-dimensional surfaces valid for acoustic wavelengths large compared with the roughness scales have been explored. The first method uses the complex excess attenuation spectrum due to a point source above a rough boundary predicted by a boundary element method (BEM) and solves for effective impedance roots identified by a winding number integral method. The second method is based on an analytical theory in which the contributions from random distributions of surface scatterers are summed to obtain the total scattered field. Effective impedance spectra deduced from measurements of the complex excess attenuation above 2D randomly rough surfaces formed by semicylinders and wedges have been compared to predictions from the two approaches. Although the analytical theory gives relatively poor predictions, BEM-deduced effective impedance spectra agree tolerably well with measured data. Simple polynomials have been found to fit BEM-deduced spectra for surfaces formed by intersecting parabolas corresponding to average roughness heights between 0.25 and 7.5 m and for five incidence angles for each average height. Predicted effects of sea-surface roughness on sonic boom profiles and rise time are comparable to those due to turbulence and molecular relaxation effects.
Gibbs sampling for time-delay-and amplitude estimation in underwater acoustics
Authors: Michalopoulou Zoi-Heleni , Picarelli Michele
Published: January 2005

Multipath arrivals at a receiving sensor are frequently encountered in many signal-processing areas, including sonar, radar, and communication problems. In underwater acoustics, numerous approaches to source localization, geoacoustic inversion, and tomography rely on accurate multipath arrival extraction. A novel method for estimation of time delays and amplitudes of arrivals with maximum a posteriori (MAP) estimation is presented here. MAP estimation is optimal if appropriate statistical models are selected for the data; implementation, requiring maximization of a multidimensional function, is computationally demanding. Gibbs sampling is proposed as an efficient means for estimating necessary posterior probability distributions, bypassing analytical calculations. The Gibbs sampler includes as unknowns time delays, amplitudes, noise variance, and number of arrivals. Through Monte Carlo simulations, the method is shown to have a performance very close to that of analytical MAP estimation. The method is also shown to be superior to expectation-maximization, which is often applied to time-delay estimation. The Gibbs sampling approach is demonstrated to be more informative than other time-delay estimation methods, providing complete posterior distributions compared to just point estimates; the distributions capture the uncertainty in the problem, presenting likely values of the unknowns that are different from simple point estimates.
Pitch (F0) and formant profiles of human vowels and vowel-like baboon grunts: The role of vocalizer body size and voice-acoustic allometry
Authors: Rendall Drew , Kollias Sophie , Ney Christina , Lloyd Peter
Published: January 2005

Key voice features—fundamental frequency (F0) and formant frequencies—can vary extensively between individuals. Much of the variation can be traced to differences in the size of the larynx and vocal-tract cavities, but whether these differences in turn simply reflect differences in speaker body size (i.e., neutral vocal allometry) remains unclear. Quantitative analyses were therefore undertaken to test the relationship between speaker body size and voice F0 and formant frequencies for human vowels. To test the taxonomic generality of the relationships, the same analyses were conducted on the vowel-like grunts of baboons, whose phylogenetic proximity to humans and similar vocal production biology and voice acoustic patterns recommend them for such comparative research. For adults of both species, males were larger than females and had lower mean voice F0 and formant frequencies. However, beyond this, F0 variation did not track body-size variation between the sexes in either species, nor within sexes in humans. In humans, formant variation correlated significantly with speaker height but only in males and not in females. Implications for general vocal allometry are discussed as are implications for speech origins theories, and challenges to them, related to laryngeal position and vocal tract length.
Geoacoustic inversion with ships as sources
Authors: Koch Robert A. , Knobles David P.
Published: January 2005

Estimation of geoacoustic parameters using acoustic data from a surface ship was performed for a shallow water region in the Gulf of Mexico. The data were recorded from hydrophones in a bottom mounted, horizontal line array (HLA). The techniques developed to produce the geoacoustic inversion are described, and an efficient method for geoacoustic inversion with broadband beam cross-spectral data is demonstrated. The performance of cost functions that involve coherent or incoherent sums over frequency and one or multiple time segments is discussed. Successful inversions for the first sediment layer sound speed and thickness and some of the parameters for the deeper layers were obtained with the surface ship at nominal ranges of 20, 30, or 50 water depths. The data for these inversions were beam cross-spectra from four subapertures of the HLA spanning a little more than two water depths. The subaperture beams included ten frequencies equally spaced in the 120–200 Hz band. The values of the geoacoustic parameters from the inversions are validated by comparisons with geophysical observations and with the parameter values from previous inversions by other invesigators, and by comparing transmission loss (TL) measured in the experiment with modeled TL based on the inverted geoacoustic parameters.
System for determination of ultrasonic wave speeds and their temperature dependence in liquids and in vitro tissues
Authors: Yost William T. , Macias Brandon R. , Cao Peihong , Hargens Alan R. , Ueno Toshiaki
Published: January 2005

An interferometric technique capable of accurately measuring wave speed in liquids is reported. The hardware is adapted from a design to measure nonlinear responses of biological tissues to pressure changes (pressure derivatives) and temperature changes (temperature derivatives). It is used with the highly sensitive variable frequency pulsed phase-locked loop (VFPPLL) instrument. The system uses well-understood and well-characterized components and systems. The apparatus covers a temperature range from below 5 °C to above 45 °C. The system with the high-sensitivity VFPPLL is capable of measurement of wave speed to an uncertainty of less than 0.1%, and changes in wave speed to better than 0.001%. The transducer is an undamped temperature-characterized PZT-5A 500-kHz plate, whose output is corrected for off-resonance operation and for diffraction effects. To test the accuracy of the technique, measurement of ultrasonic compressional wave speed in water at temperatures from 10 °C to 45 °C are reported, with an estimated uncertainty of 0.07% and a temperature uncertainty of 0.15 °C. The agreement between mean values and literature values is better than 0.05%.
Analysis of the sandwich piezoelectric ultrasonic transducer in coupled vibration
Authors: Shuyu Lin
Published: January 2005

The coupled vibration of the sandwich piezoelectric transducer with a large cross-section is analyzed using an approximate analytic method. The resonance frequency equations of the transducer are derived and the effect of the geometrical dimensions on the resonance frequency is studied. It is illustrated that when the radial vibration in the transducer is considered, the vibration of the sandwich transducer becomes more complex. Apart from the longitudinal resonance frequency, the radial resonance frequency can also be obtained. For comparison, numerical methods are also used to simulate the coupled vibration; the resonance frequency and the vibrational displacement distribution are computed. Compared with one-dimensional longitudinal theory, the radial dimensions of the transducer are no longer limited because the coupled vibration is considered. Compared with numerical methods, the physical meaning of the analytic method is concise. It is illustrated that the resonance frequencies obtained from the coupled resonance frequency equations are in good agreement with those from numerical methods, and they are in better agreement with the measured results than those from one-dimensional theory. Since the radial and the coupled vibration are considered in the analysis, more resonance frequencies can be obtained. Therefore, using the coupled resonance frequency equations, the sandwich transducer with multifrequency or wide frequency bandwidth can be designed and used in ultrasonic cleaning, ultrasonic sonochemistry and other applications.
Sound-field reproduction in-room using optimal control techniques: Simulations in the frequency domain
Authors: Gauthier Philippe-Aubert , Berry Alain , Woszczyk Wieslaw
Published: January 2005

This paper describes the simulations and results obtained when applying optimal control to progressive sound-field reproduction (mainly for audio applications) over an area using multiple monopole loudspeakers. The model simulates a reproduction system that operates either in free field or in a closed space approaching a typical listening room, and is based on optimal control in the frequency domain. This rather simple approach is chosen for the purpose of physical investigation, especially in terms of sensing microphones and reproduction loudspeakers configurations. Other issues of interest concern the comparison with wave-field synthesis and the control mechanisms. The results suggest that in-room reproduction of sound field using active control can be achieved with a residual normalized squared error significantly lower than open-loop wave-field synthesis in the same situation. Active reproduction techniques have the advantage of automatically compensating for the room’s natural dynamics. For the considered cases, the simulations show that optimal control results are not sensitive (in terms of reproduction error) to wall absorption in the reproduction room. A special surrounding configuration of sensors is introduced for a sensor-free listening area in free field.
On the binding of successive sounds: Perceiving shifts in nonperceived pitches
Authors: Demany Laurent , Ramos Christophe
Published: January 2005

It is difficult to hear out individually the components of a “chord” of equal-amplitude pure tones with synchronous onsets and offsets. In the present study, this was confirmed using 300-ms random (inharmonic) chords with components at least 1/2 octave apart. Following each chord, after a variable silent delay, listeners were presented with a single pure tone which was either identical to one component of the chord or halfway in frequency between two components. These two types of sequence could not be reliably discriminated from each other. However, it was also found that if the single tone following the chord was instead slightly (e.g., 1/12 octave) lower or higher in frequency than one of its components, the same listeners were sensitive to this relation. They could perceive a pitch shift in the corresponding direction. Thus, it is possible to perceive a shift in a nonperceived frequency/pitch. This paradoxical phenomenon provides psychophysical evidence for the existence of automatic “frequency-shift detectors” in the human auditory system. The data reported here suggest that such detectors operate at an early stage of auditory scene analysis but can be activated by a pair of sounds separated by a few seconds.
Simultaneous recording of stimulus-frequency and distortion-product otoacoustic emission input–output functions in human ears
Authors: Schairer Kim S. , Keefe Douglas H.
Published: January 2005

Stimulus frequency otoacoustic emission (SFOAE) input–output (I/O) functions were elicited in normal-hearing adults using unequal-frequency primaries in equal-level and fixed-suppressor level (Ls) conditions. Responses were repeatable and similar across a range of primary frequency ratios in the fixed-Ls condition. In comparison to equal-frequency primary conditions [Schairer, Fitzpatrick, and Keefe, J. Acoust. Soc. Am. 114, 944–966 (2003)], the unequal-frequency, fixed-Ls condition appears to be more useful for characterizing SFOAE response growth and relating it to basilar-membrane response growth, and for testing the ability to predict audiometric thresholds. Simultaneously recorded distortion-product OAE (DPOAE) I/O functions had higher thresholds than SFOAE I/O functions, and they identified the onset of the nonlinear-distortion mechanism in SFOAEs. DPOAE threshold often corresponded to nonmonotonicities in SFOAE I/O functions. This suggests that the level-dependent nonmonotonicities and associated phase shifts in SFOAE I/O functions were due to varying degrees of cancellation of two sources of SFOAE, such as coherent reflection and distortion mechanisms. Level-dependent noise was observed on-band (at the frequencies of the stimuli) but not off-band, or in the DPOAEs. The variability was observed in ears with normal hearing and ears with cochlear implants. In general, these results indicate the source of the variability is biological, possibly from within the middle ear.
Inversion of sonobuoy data from shallow-water sites with simulated annealing
Authors: Lindwall Dennis , Brozena John
Published: January 2005

An enhanced simulated annealing algorithm is used to invert sparsely sampled seismic data collected with sonobuoys to obtain seafloor geoacoustic properties at two littoral marine environments as well as for a synthetic data set. Inversion of field data from a 750-m water-depth site using a water-gun sound source found a good solution which included a pronounced subbottom reflector after 6483 iterations over seven variables. Field data from a 250-m water-depth site using an air-gun source required 35 421 iterations for a good inversion solution because 30 variables had to be solved for, including the shot-to-receiver offsets. The sonobuoy derived compressional wave velocity–depth (Vp-Z) models compare favorably with Vp-Z models derived from nearby, high-quality, multichannel seismic data. There are, however, substantial differences between seafloor reflection coefficients calculated from field models and seafloor reflection coefficients based on commonly used Vp regression curves (gradients). Reflection loss is higher at one field site and lower at the other than predicted from commonly used Vp gradients for terrigenous sediments. In addition, there are strong effects on reflection loss due to the subseafloor interfaces that are also not predicted by Vp gradients.
Approximate high-order dynamic theory of a fluid layer in between two thick solids
Authors: Zakharov Dmitry D.
Published: January 2005

A thin layer of heavy fluid with bound faces is considered first. For the sake of simplicity, the effects of vortex and viscosity are neglected. Two cases of compressible and incompressible fluids are treated, assuming that a thickness-over-wavelength ratio is a small parameter. For the internal state of medium the relations between the quantities on the layer surfaces are deduced. In contrast to the standard approach, which expands the propagator matrix into power series of a small wave number, the asymptotic integration of 3D equations and boundary conditions of fluid dynamics is performed. Respective relations are represented in a recurrent form and permit one to obtain the high-order components of the displacements and pressure rather simply. When considering two thick solids with a fluid in between, this result is used to derive the so-called “impedance boundary conditions” (IBC) with a relative asymptotic error up to tenth order. Tests show their validity until the first quasiresonance frequency of a layer, so, the analysis is not just long wave but essentially low frequency. Thus, these IBC are applicable to reduce the dimension in the analysis of challenged multicomponent system of fluid-coupled solids in a reasonable frequency range.
STOCHASTIC VOLATILITY MODELS AND THEIR APPLICATION TO GERMAN DAX DATA
Authors: REMER RALF , MAHNKE REINHARD
Published: January 2005

We focus on the stochastic description of the stock price dynamics. Thereby we concentrate on the Heston model and the Hull–White model. We derive the stationary probability density distribution of the variance of both models in the case of zero correlation coefficient. These distributions are used to calculate solutions for the logarithmic returns of the stock price for short time lags. Furthermore we apply the solutions of both models to the German tick-by-tick Dax data [1]. The data are from May 1996 to December 2001. We use the probability density distributions of the logarithmic returns, calculated out of the data, and fit these distributions to the theoretical distributions.
THE ROLE OF NOISE IN SIDEBRANCHING DEVELOPMENT
Authors: GONZÁLEZ-CINCA RICARD , COUDER YVES , MAURER J. , HERNÁNDEZ-MACHADO A.
Published: January 2005

In this paper we study the sidebranching development of solidifying dendrites both experimentally and by numerical integration of a phase-field model with a noise term. Our results support the idea that sidebranching is originated through the selective amplification of natural noise at the tip. The initial stages turn to be of crucial importance in the selection of the final noisy shape. However, our results suggest that after the stochastic initial disturbance, a deterministic mechanism dominates the growth and screening-off process of sidebranching.
HIGHER-ORDER SPECTRA IN NANOPARTICLE GAS SENSORS
Authors: SMULKO J. M. , EDERTH J. , KISH L. B. , HESZLER P. , GRANQVIST C. G.
Published: January 2005

It has previously been shown that resistance fluctuations in resistive sensors provide enhanced sensitivity and selectivity for gas detection. We report measurements and analysis of non-Gaussian components in nanoparticle Pd z ( WO 3)1- z film gas sensors, with z being 0.01 or 0.12, in different ambients. These components can be characterized by higher-order spectra. Contour plots are given of bispectra, and plots of integrated bispectra and trispectra. The phase of the integrated higher-order spectra is analyzed as well.
DIGITAL SIGNAL PROCESSOR (DSP) BASED 1/fa NOISE GENERATOR
Authors: MINGESZ R. , BARA P. , GINGL Z. , MAKRA P.
Published: January 2005

1/f noise is present in many natural and artificial systems, and even though it was discovered decades ago, it is still not completely understood. Due to the lack of an universal model, the main methods of investigating a system where 1/f noise is present are numerical simulations and real measurements. The second method can lead to more adequate results, since it is free from numerical artifacts. In the case of real measurements, we need reliable, wide-band noise generators. Many ways of generating noise are known; most of them have several limitations on the frequency bandwidth or on spectral properties. We wanted to create a device which is easy to use, which can generate any kind of 1/fa (0 < a < 2) noise and whose bandwidth is wide enough to make our investigations. We used a DSP (ADSP2181) to numerically generate the desired noise, and a D/A converter to convert it to an analogue signal. The noise generation algorithm was based on the known method of filtering a Gaussian white noise with a series of first-order digital filters. We enhanced this method to get a better spectral shape and to compensate for the side effects of the digital-to-analogue conversion.
TIME REQUIRED FOR A SPECIFIED LEVEL OF ACCURACY IN NOISE CORRELATION MEASUREMENTS
Authors: REZA SHAHED , BOSMAN GIJS , SAYLOR CHARLES , DUENSING GEORGE R.
Published: January 2005

Correlation measurement is an effective way of measuring noise components with a magnitude smaller than the system noise. The accuracy of such measurement depends on the system bandwidth, the magnitude of the noise to be measured compared to the system noise and the measurement time. The accuracy can be improved by increasing the measurement time. A method of estimating the measurement time required for a desired level of accuracy for a given system noise and bandwidth is presented.
DYNAMICS IMPORTANCE SAMPLING FOR THE COLLECTION OF SWITCHING EVENTS IN VERTICAL-CAVITY SURFACE-EMITTING LASERS
Authors: BERI STEFANO , McCLINTOCK PETER V. E. , MANNELLA RICCARDO
Published: January 2005

A numerical approach based on dynamic importance sampling (DIMS) is applied to investigate polarization switches in vertical-cavity surface-emitting lasers. A polarization switch is described as an activation process in a two-dimensional nonequilibrium system. DIMS accelerates the simulations and allows access to noise intensities that were previously forbidden, revealing qualitative changes in the shape of the transition paths with noise intensity.
REMARK ON A "NON-BREAKABLE DATA ENCRYPTION" SCHEME BY KISH AND SETHURAMAN
Authors: KLAPPENECKER ANDREAS
Published: January 2005

We break a cryptosystem by Kish and Sethuraman and show that the authentication problem of their protocol can be fixed. We prove that finding an instance of this cryptosystem, which meets the design criteria, would show that P≠NP.
Transient Non-Autoimmune Fetal Heart Block
Authors: Breur Johannes M.P.J. , Oudijk Martijn A. , Stoutenbeek Philip , Visser Gerard H.A. , Meijboom Erik J.
Published: January 2005

Objectives: Fetal heart block is a rare and irreversible condition associated with structural heart defects or maternal autoantibodies (SS-A/Ro and SS-B/La) resulting in permanent damage of the atrioventricular (AV) node. This is the first report of 4 cases with a transient fetal heart block in structurally normal hearts without maternal autoantibodies. Methods: A report on 4 patients seen within a 14-year period at one center with fetal heart block without intracardiac abnormalities or maternal autoantibodies. Results: Three patients were referred to our center with a fetal bradycardia (heart rate 70–85 bpm), between 20 and 33 weeks’ gestational age, and 1 for a ‘triple’ test at 16 weeks’ gestational age. Echocardiography showed a complete heart block in 2 fetuses, and a second-degree AV block in the other 2. Heart block had completely resolved at all following visits. Postnatal ECG recordings showed normal sinus rhythm in all patients. Echocardiographic evaluation at presentation and follow-up showed normal cardiac anatomy, without signs of hydrops or cardiac decompensation in all patients. All mothers tested negative on SS-A/Ro and SS-B/La autoantibodies. Conclusions: Fetal heart block can occur in the absence of structural heart defects and maternal autoantibodies to SS-A/Ro and SS-B/La. The origin of such heart block is unknown, but its course seems benign: none of the patients ever showed ventricular heart rates <55 bpm, signs of congestive heart failure or fetal hydrops. Heart block resolved spontaneously in all patients.
Nomograms for the Sonographic Measurement of the Fetal Philtrum and Chin
Authors: Gull Ilan , Wolman Igal , Merlob Paul , Jaffa Ariel J. , Lessing Joseph B. , Yaron Yuval
Published: January 2005

Objective: To generate nomograms for the sonographic measurement of the fetal philtrum and chin during pregnancy. Design: A prospective, cross-sectional study in normal singleton pregnancies. Subjects: One hundred and fifty-three fetuses between 13 and 42 weeks of gestation were studied. Methods: The philtrum was measured from the base of the columella to the upper lip. The chin was measured from the tip of the lower lip to the skin under the lower tip of the mandible. Predictive models were evaluated to generate graphic description of the 5th, 50th and 95th centiles for the fetal philtrum and chin. Results: Fetal philtrum length increased with gestational age. The regression equation for the philtrum length (y) according to gestational age in weeks (x) is best predicted by the S-curve (Gompertz) model, as described by the following equation: y = exp(a + b/x), where a = 2.778577, and b = –23.476723 (R2 = 85.3%, p < 0.0001). The fetal chin length increased with gestational age. The regression equation for the mean chin length (y) according to gestational age in weeks (x) is best predicted by the S-curve model as described in the following equation. y = exp(a + b/x), where a = 3.7922, b = –28.043, (R2 = 89.0%, p < 0.0001). Conclusions: The nomograms generated in this study for the fetal philtrum and chin during pregnancy can be used in confirming subjective impression of facial dysmorphism.
Large Hepatic Mesenchymal Hamartoma Leading to Mid-Trimester Fetal Demise
Authors: Laberge J.-M. , Patenaude Y. , Desilets V. , Cartier L. , Khalife S. , Jutras L. , Chen M.-F.
Published: January 2005

This report describes a fetus with a large multiloculated cystic liver mass. Two small abdominal cysts were seen on ultrasound at 19 weeks of gestation but the patient was referred to us at 23 weeks, after the mass had grown to 8.0 × 5.6 × 7.0 cm, displacing intra-abdominal organs, heart and diaphragm. There was a small amount of ascites but no hydrops. There was polyhydramnios and a thick hyperechoic placenta. After detailed sonograms and MRI suggested the diagnosis of cystic mesenchymal hamartoma of the liver, cyst decompression was favored and consent was obtained. Unfortunately, absence of fetal cardiac activity was noted on the day of the planned intervention. Autopsy confirmed the diagnosis and demonstrated placental changes consistent with mesenchymal stem villous hyperplasia of the placenta. Large fetal cystic abdominal masses that compress the heart, lungs and other organs may benefit from prenatal decompression. This is the first report of cystic hamartoma of the liver apparent on second-trimester sonography, and the fourth time such a lesion is associated with fetal or neonatal death out of 11 cases diagnosed prenatally.
Fetal Cystic Malformations of the Posterior Fossa in the First Trimester of Pregnancy
Authors: Nizard Jacky , Bernard Jean-Pierre , Ville Yves
Published: January 2005

Diagnosis of abnormalities of the posterior fossa, such as Dandy-Walker malformation, can be assessed during the first trimester of pregnancy by ultrasonography. We report on 5 cases of posterior fossa abnormalities, 4 Dandy-Walker malformations and 1 Dandy-Walker variant, diagnosed during the first trimester of pregnancy by ultrasound examination. All cases were confirmed later during the pregnancy by further ultrasound examinations or by postmortem examination when parents elected for termination of pregnancy. Two of our Dandy-Walker malformation cases were siblings from consanguineous parents and had a Meckel syndrome variant associated with the posterior fossa malformation, multicystic kidneys and hepatic fibrosis. We believe first trimester diagnosis of Dandy-Walker complex is possible, but needs to be confirmed later during the pregnancy and should prompt a detailed survey for other abnormalities.
Prolonged Protective Effect of Short Daily Hemodialysis against Dialysis-Induced Hypotension
Authors: Okada Kazuyoshi , Abe Masanori , Hagi Chihiro , Maruyama Takashi , Maruyama Noriaki , Ito Ken , Higuchi Terumi , Matsumoto Koichi , Takahashi Susumu
Published: January 2005

Background/Aims: Short daily hemodialysis (HD) has a protective effect against dialysis-induced hypotension (DIH). We examined whether this effect extends beyond the treatment period. Methods: We analyzed clinical variables in 6 patients (5 with diabetes mellitus) who underwent conventional hemodialysis (CHD) for 4 h three times weekly for 12 weeks; then short daily HD for 2 h six times weekly for 12 weeks, and then 12 more weeks of CHD. All patients had been given vasopressors for severe DIH. Results: The severe DIH disappeared during the short daily HD. There were significant decreases in body weight (BW), cardiothoracic ratio (CTR), blood pressure (BP), normal saline solution (NSS) amount (62.8 ± 26.4 vs. 9.8 ± 7.4 ml/session, p < 0.05), frequency (0.60 ± 0.26 vs. 0.10 ± 0.07 infusions/session, p < 0.05) and postdialysis atrial natriuretic peptide (ANP) (176.8 ± 56.4 vs. 104.8 ± 42.3 pg/ml, p < 0.05). Weekly ultrafiltration volume (6.3 ± 0.9 vs. 7.9 ± 0.7 l, p < 0.05) was significantly higher during the short daily HD period than during the first CHD period. The vasopressor treatment was therefore stopped or reduced in all patients during the short daily HD period. Because DIH recurred in the second CHD period despite a significant increase in BP, the vasopressor treatment was resumed in 5 patients. BW, CTR, NSS infusion amount and frequency, or postdialysis ANP did not differ significantly between the short daily HD and second CHD periods. Conclusions: The protective effect of short daily HD against DIH lasted more than 12 weeks after the treatment ended. We therefore conclude that temporary short daily HD is useful for preventing DIH.
Early Diabetes-Related Complications in Adolescents
Authors: Daneman Denis
Published: January 2005

Micro- and macrovascular complications account for the major part of the morbidity and mortality associated with diabetes developing in childhood. Although advanced complications are exceptionally rare in the adolescent age group, it is during this phase that the progression of risk may accelerate. A number of potentially important factors have been identified which might contribute to risk of complication development: some provide insights into the genetics of these complications, while others are potentially modifiable, such as metabolic control, hypertension, smoking, obesity and hyperlipidemia. Recently, both consensus and evidence-based guidelines have been developed to guide those involved in the care of adolescents with diabetes in the prevention, screening and management of early diabetes-related complications in this vulnerable population. This article reviews the literature that underpins the available guidelines and stresses the pivotal role of excellent metabolic control in complication prevention.
Three Factors in Language Design
Authors: Chomsky Noam
Published: January 2005

The biolinguistic perspective regards the language faculty as an “organ of the body,” along with other cognitive systems. Adopting it, we expect to find three factors that interact to determine (I-) languages attained: genetic endowment (the topic of Universal Grammar), experience, and principles that are language- or even organism-independent. Research has naturally focused on I-languages and UG, the problems of descriptive and explanatory adequacy. The Principles-and-Parameters approach opened the possibility for serious investigation of the third factor, and the attempt to account for properties of language in terms of general considerations of computational efficiency, eliminating some of the technology postulated as specific to language and providing more principled explanation of linguistic phenomena
Palatalization/Velar Softening: What It Is and What It Tells Us about the Nature of Language
Authors: Halle Morris
Published: January 2005

This study proposes an account both of the consonantal changes involved in palatalization/velar softening and of the fact that this change is encountered before front vowels. The change is a straightforward case of feature assimilation provided that segments/phonemes are viewed as complexes of features organized into the “bottle brush” model illustrated in example (4) and elsewhere in the text, and that the universal set of features includes, in addition to the familiar binary features, six unary features, which specify the designated articulator(s) for every segment (not only for consonants).
The Universal Church of the Kingdom of God: A Brazilian Church Finds Success in Southern Africa
Authors: Freston Paul
Published: January 2005

The Universal Church of the Kingdom of God, a Brazilian Pentecostal church which in little more than a decade has had considerable success in southern Africa, is analyzed as a new phenomenon in the region's religious world, bypassing the West and straddling existing ecclesiastical typologies. However, its success has been limited virtually to three countries in the region, and the reasons for its appeal in democratic South Africa and post-Marxist Mozambique and Angola are examined. In the Lusophone sphere, its Brazilian cultural heritage and media power have made it a powerful social force; and in the new South Africa (despite the strong contrast in race relations with its Brazilian homeland), it has found a country with similar levels of development and similar inequalities, within which it has been able to fill a niche in the local religious field newly emerged from apartheid, and to begin a process of South Africanization.
Success and Survival of Skill-Based Pay Plans
Authors: Shaw Jason D. , Gupta Nina , Mitra Atul , Ledford Gerald E.
Published: January 2005

Factors related to the success and survival of skill-based pay (SBP) plans are addressed in a longitudinal study of 97 facilities. Results indicate that certain design features and support variables relate to increased workforce flexibility and to SBP survival, and supervisor support also relates strongly to SBP survival. The results also show that SBP plans are more successful and sustainable in manufacturing facilities than in service facilities, and SBP survival is less likely in facilities pursuing a technical innovation strategy. Implications of the research for theory and practice regarding SBP plans, compensation systems, and human resources management innovations are addressed.
Development and Validation of the Political Skill Inventory
Authors: Ferris Gerald R. , Treadway Darren C. , Kolodinsky Robert W. , Hochwarter Wayne A. , Kacmar Charles J. , Douglas Ceasar , Frink Dwight D.
Published: January 2005

The present research was developed to examine the conceptualization and measurement of the political skill construct and to provide validation evidence for the Political Skill Inventory (PSI). The results of three investigations, involving seven samples, are reported that demonstrate consistency of the factor structure across studies, construct validity, and criterion-related validity of the PSI. As hypothesized, political skill was positively related to self-monitoring, political savvy, and emotional intelligence; negatively related to trait anxiety; and not correlated with general mental ability. Also, the PSI predicted performance ratings of managers in two samples. Implications of these findings and directions for future research are provided.