bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification of distant targets situated near channel bottoms
Authors: Liu Hongwei , Runkle Paul , Carin Lawrence , Yoder Timothy , Giddings Thomas , Couchman Luise , Bucaro Joseph
Published: March 2004

Identification algorithms are considered for a class of targets situated near the bottom of a water channel. It is assumed that the target-sensor distance relative to the channel depth is such that a ray-based representation of the scattered fields is appropriate (vis-à-vis a modal representation). Two approaches are considered for processing the scattered fields. In one algorithm a deconvolution is performed to remove the channel response, and thereby recover the free-field target scattered signature. In this case the classifier is trained based on free-field data. In the second approach the array receiver is employed to point the sensor in particular directions, and the beam-formed signal is used directly in the subsequent classifier. In this case the classifier must be trained based on in-channel data. Multiple scattered signals are measured, from a sequence of target-sensor orientations, with the waveforms classified via a hidden Markov model. Example results are presented for scattering data simulated via the finite-element method and coupled to a normal-mode waveguide modal, for elastic targets situated in a water channel.
Hawkins and Stevens revisited with insert earphones (L)
Authors: Houtsma Adrianus J. M.
Published: March 2004

The classical experiment on masking of pure tones by white noise by Hawkins and Stevens [J. Acoust. Soc. Am. 22, 6–13 (1950)] has left two general notions about broadband masking that are still being echoed in present-day textbooks on hearing. One is that broadband masking is linear (i.e., if the noise power level increases, the signal threshold level increases by exactly the same amount). The other is the existence of a nonmonotonic function of frequency, the critical ratio (CR) which, unlike the critical band (CB) or equivalent rectangular bandwidth (ERB) functions, shows a distinct upturn below 300 Hz. Exploring the possibility that Hawkins and Stevens’ measurements may have been adversely affected by acoustic leakage at the headphones at low frequencies, the experiment was repeated with insert earphones. The resulting critical ratio function shows a monotonic dependence on frequency down to 90 Hz, similar to CB and ERB functions. Moreover, the CR function appears to closely approximate the ERB function when the dependence of each filter’s detection efficiency on masker energy uncertainty is incorporated. Masking appears to be linear below 1000 Hz, but thresholds, expressed as S/N0 ratios, were found to increase systematically with increasing masker intensity at higher frequencies.
A vocal-tract model of American English /l/
Authors: Zhang Zhaoyan , Espy-Wilson Carol Y.
Published: March 2004

The production of the lateral sounds involves airflow paths around the tongue produced by the laterally inward movement of the tongue toward the midsagittal plane. If contact is made with the palate, a closure is formed in the flow path along the midsagittal line. The effects of the lateral channels on the sound spectrum are not clear. In this study, a vocal-tract model with parallel lateral channels and a supralingual cavity was developed. Analysis shows that the lateral channels with dimensions derived from magnetic resonance images of an American English /l/ are able to produce a pole–zero pair in the frequency range of 2–5 kHz. This pole–zero pair, together with an additional pole–zero pair due to the supralingual cavity, results in a low-amplitude and relatively flat spectral shape in the F3–F5 frequency region of the /l/ sound spectrum.
Enhanced ultrasound transmission through the human skull using shear mode conversion
Authors: Clement G. T. , White P. J. , Hynynen K.
Published: March 2004

A new transskull propagation technique, which deliberately induces a shear mode in the skull bone, is investigated. Incident waves beyond Snell’s critical angle experience a mode conversion from an incident longitudinal wave into a shear wave in the bone layers and then back to a longitudinal wave in the brain. The skull’s shear speed provides a better impedance match, less refraction, and less phase alteration than its longitudinal counterpart. Therefore, the idea of utilizing a shear wave for focusing ultrasound in the brain is examined. Demonstrations of the phenomena, and numerical predictions are first studied with plastic phantoms and then using an ex vivo human skull. It is shown that at a frequency of 0.74 MHz the transskull shear method produces an amplitude on the order of—and sometimes higher than—longitudinal propagation. Furthermore, since the shear wave experiences a reduced overall phase shift, this indicates that it is plausible for an existing noninvasive transskull focusing method [Clement, Phys. Med. Biol. 47(8), 1219–1236 (2002)] to be simplified and extended to a larger region in the brain.
Harmonic distortion in intracochlear pressure and its analysis to explore the cochlear amplifier
Authors: Olson Elizabeth S.
Published: March 2004

Intracochlear pressure was measured close to the basal basilar membrane in gerbil with pure-tone stimulation. This report describes harmonic distortion in the pressure. The harmonic components were tuned in frequency and physiologically vulnerable, implying that they were related to the cell-derived force that sharpens tuning at low levels in healthy cochleae. For stimulus frequencies in the vicinity of the best frequency the harmonic distortion appeared to be produced locally, at the place of measurement. Therefore, it could be explored with a local nonlinear model. The combined model and observations demonstrate two specific points: First, the harmonics in the cell-based force were likely similar in size to the harmonics in pressure (multiplied by area) close to the basilar membrane. This is distinctly different than the situation for the fundamental component, where the cell-based force is apparently much smaller than the pressure (times area). Second, although the fundamental component of the measured pressure was much larger than its harmonic components, the harmonic and fundamental components of the active force were likely much more similar in size. This allows the harmonic components in the pressure to be used as an indirect measure of the active force.
Comment on “Acoustical losses in wet instrument bores” [J. Acoust. Soc. Am. 114, 1221 (2003)] (L)
Authors: Slaton William V.
Published: March 2004

This letter is a comment on Coltman’s [J. Acoust. Soc. Am. 114, 1221 (2003)] letter describing increased acoustic losses for a water-saturated air mixture in a tube. Recent publications are referenced which supply the necessary theoretical background to calculate the attenuation of sound in an inert gas–vapor mixture enclosed in a wet-walled tube. It is shown that these references are sufficient to analyze the results presented by Coltman.
The psychomechanics of simulated sound sources: Material properties of impacted bars
Authors: McAdams Stephen , Chaigne Antoine , Roussarie Vincent
Published: March 2004

Sound can convey information about the materials composing an object that are often not directly available to the visual system. Material and geometric properties of synthesized impacted bars with a tube resonator were varied, their perceptual structure was inferred from multidimensional scaling of dissimilarity judgments, and the psychophysical relations between the two were quantified. Constant cross-section bars varying in mass density and viscoelastic damping coefficient were synthesized with a physical model in experiment 1. A two-dimensional perceptual space resulted, and the dimensions were correlated with the mechanical parameters after applying a power-law transformation. Variable cross-section bars varying in length and viscoelastic damping coefficient were synthesized in experiment 2 with two sets of lengths creating high- and low-pitched bars. In the low-pitched bars, there was a coupling between the bar and the resonator that modified the decay characteristics. Perceptual dimensions again corresponded to the mechanical parameters. A set of potential temporal, spectral, and spectrotemporal correlates of the auditory representation were derived from the signal. The dimensions related to mass density and bar length were correlated with the frequency of the lowest partial and are related to pitch perception. The correlate most likely to represent the viscoelastic damping coefficient across all three stimulus sets is a linear combination of a decay constant derived from the temporal envelope and the spectral center of gravity derived from a cochlear representation of the signal. These results attest to the perceptual salience of energy-loss phenomena in sound source behavior.
Frequency dependence of dynamic hysteresis in the interaction of acoustic wave with interface
Authors: Gusev Vitalyi
Published: March 2004

The motion of an interface in acoustic field is modeled as a nonlinear relaxator driven by sound wave. The nonlinearity is due to nonlinear dependence of an interaction force between the surfaces composing the interface on their separation distance. The theory describes hysteresis in the response of the interface to continuously varying acoustic loading: with increasing acoustic field a strongly unharmonic variation of a characteristic interface width starts under some circumstances at higher amplitudes of external action than those at which it later stops with decreasing acoustic field. This dynamic hysteresis phenomenon is found to be dispersive in a sense that it depends on the relative values of the acoustic frequency and characteristic relaxation frequencies of the interface. These theoretical predictions might be also relevant to some recent experimental observations of hysteresis phenomena in the interaction of powerful ultrasonic fields with cracks.
Detection of speech landmarks: Use of temporal information
Authors: Salomon Ariel , Espy-Wilson Carol Y. , Deshmukh Om
Published: March 2004

Studies by Shannon et al. [Science, 270, 303–304 (1995)], Van Tasell et al. [J. Acoust. Soc. Am. 82, 1152–1161 (1987)], and others show that human listeners can understand important aspects of the speech signal when spectral shape has been significantly degraded. These experiments suggest that temporal information is particularly important in human speech perception when the speech signal is heavily degraded. In this study, a system is developed that extracts linguistically relevant temporal information that can be used in the front end of an automatic speech recognition system. The parameters targeted include energy onset and offsets (computed using an adaptive algorithm) and measures of periodic and aperiodic content; together these are used to find abrupt acoustic events which signify landmarks. Overall detection rates for strongly robust events, robust events, and weak events in a portion of the TIMIT test database are 98.9%, 94.7%, and 52.1%, respectively. Error rates increase by less than 5% when the speech signals are spectrally impoverished. Use of the four temporal parameters as the front end of a hidden Markov model (HMM)-based system for the automatic recognition of the manner classes “sonorant,” “fricative,” “stop,” and “silence” results in the same recognition accuracy achieved when the standard 39 cepstral-based parameters are used, 70.1%. The combination of the temporal parameters and cepstral parameters results in an accuracy of 74.8%.
Dynamics and noise emission of laser induced cavitation bubbles in a vortical flow field
Authors: Oweis Ghanem F. , Choi Jaehyug , Ceccio Steven L.
Published: March 2004

The sound produced by the collapse of discrete cavitation bubbles was examined. Laser-generated cavitation bubbles were produced in both a quiescent and a vortical flow. The sound produced by the collapse of the cavitation bubbles was recorded, and its spectral content was determined. It was found that the risetime of the sound pulse produced by the collapse of single, spherical cavitation bubbles in quiescent fluid exceeded that of the slew rate of the hydrophone, which is consistent with previously published results. It was found that, as collapsing bubbles were deformed by the vortical flow, the acoustic impulse of the bubbles was reduced. Collapsing nonspherical bubbles often created a sound pulse with a risetime that exceeded that of the hydrophone slew rate, although the acoustic impulse created by the bubbles was influenced largely by the degree to which the bubbles became nonspherical before collapse. The noise produced by the slow growth of cavitation bubbles in the vortex core was not detectable. These results have implications for the interpretation of hydrodynamic cavitation noise produced by vortex cavitation.
Intelligibility of bandpass filtered speech: Steepness of slopes required to eliminate transition band contributions
Authors: Warren Richard M. , Bashford James A. , Lenz Peter W.
Published: March 2004

Despite the recognition that the steepness of filter slopes can play an important role in the intelligibility of bandpass speech, there has been no systematic examination of its importance. The present study used high orders of finite impulse response (FIR) filtering to produce slopes ranging from 150 to 10 000 dB/octave. The slopes flanked 1/3-octave passbands of everyday sentences having a center frequency of 1500 Hz (the region of highest intelligibility for the male speaker’s voice). Presentation levels were approximately 75 and 45 dB. No significant differences were found for the two presentation levels. Average intelligibility scores ranged from 77% at 150 dB/octave down to the asymptotic intelligibility score of 12% at 4800 dB/octave. These results indicate that slopes of several thousand dB/octave may be required for accurate and unambiguous specification of the range of frequencies contributing to intelligibility of filtered speech. In addition, the extremely steep slopes are needed to ensure that none of the spectral components contributing to intelligibility has its relative importance diminished by spectral tilt.
Geoacoustic inversion in range-dependent ocean environments using a plane wave reflection coefficient approach
Authors: Stotts S. A. , Knobles D. P. , Koch R. A. , Grant D. E. , Focke K. C. , Cook A. J.
Published: March 2004

A new, efficient, versatile ray-based model is presented that performs geoacoustic inversions in range-dependent ocean waveguides faster than alternative forward models for which the computation time becomes extremely long, especially for broadband inversions. The water propagation is approximately separated from the seabed interaction using predetermined bathymetry and a possibly range-dependent water sound speed profile. The geometrical optics approximation is used to calculate eigenrays between sources and receivers, including bottom reflecting paths. Modeled broadband pressure fields are obtained by computing the plane wave reflection coefficient at specific angles and frequencies and by then linking this result with the bottom reflected eigenrays. Each perturbation of the seabed requires a recalculation of the plane wave reflection coefficient, but not a recalculation of the eigenrays, resulting in a highly efficient method. Range-independent problems are treated as a limiting case of the approach. The method is first described and then demonstrated with a few simple range-independent theoretical models. The versatility of addressing range-dependence in the bottom seabed is demonstrated with a simulated data set. Finally, the new model is applied to inversion from a measured data set, taken with impulsive sources, for both range-independent and range-dependent continental shelf environments.
Using the Speech Transmission Index for predicting non-native speech intelligibility
Authors: van Wijngaarden Sander J. , Bronkhorst Adelbert W. , Houtgast Tammo , Steeneken Herman J. M.
Published: March 2004

While the Speech Transmission Index (STI) is widely applied for prediction of speech intelligibility in room acoustics and telecommunication engineering, it is unclear how to interpret STI values when non-native talkers or listeners are involved. Based on subjectively measured psychometric functions for sentence intelligibility in noise, for populations of native and non-native communicators, a correction function for the interpretation of the STI is derived. This function is applied to determine the appropriate STI ranges with qualification labels (“bad”–“excellent”), for specific populations of non-natives. The correction function is derived by relating the non-native psychometric function to the native psychometric function by a single parameter (ν). For listeners, the ν parameter is found to be highly correlated with linguistic entropy. It is shown that the proposed correction function is also valid for conditions featuring bandwidth limiting and reverberation.
Tracking target in cluttered environment using multilateral time-delay measurements
Authors: Carevic Dragana
Published: March 2004

The problem considered here is that of tracking a single underwater target in clutter using multilateral time-delay measurements derived from short-duration acoustic emissions, or transients, radiated by the target. The target is moving linearly with constant velocity and depth. To account for the effects on the time-delay estimates due to acoustic propagation in uncertain environments, the time-delay measurement errors between pairs of sensors are modeled using Gaussian mixture distributions. An approach is proposed that utilizes an iterative maximum likelihood optimization technique based on the expectation-maximization algorithm. In each iteration a nonlinear least-squares procedure is used to compute the target model parameters. A detection mechanism is also formulated that can validate the correctness of the estimated track parameters and verify the existence of a target. The proposed method is tested using simulated time-delay measurements from a linear array of three equally spaced sensors mounted onboard an observer platform. Extensive tests are performed for several scenarios with different tracking geometry.
Comment on “Adaptive tuning of an electrodynamically driven thermoacoustic cooler” [J. Acoust. Soc. Am. 111(3), 1251–1258 (2002)] (L)
Authors: Smith Robert W. M.
Published: March 2004

Corrections for equations contained in a recent paper [Li et al., J. Acoust. Soc. Am. 111(3), 1251–1258 (2002)] are provided and unclear items are discussed. Comments are provided on some of the observations and conclusions of this paper.
Reply to comments on “Adaptive tuning of an electrodynamically driven thermoacoustic cooler” [J. Acoust. Soc. Am. 111, 1251–1258 (2002)] (L)
Authors: Li Yaoyu , Paek In-Su , Chiu George T.-C. , Mongeau Luc G. , Braun James E.
Published: March 2004

This Letter is a response to the comments by Smith on the paper published by Li et al. entitled “Adaptive tuning of an electrodynamically driven thermoacoustic cooler.” Some editorial errors in the original paper are corrected. Some confusing notations are clarified and an additional discussion is provided. Questions about the generality of the results are clarified by the author’s comments.
Sound wave channelling in near-critical sulfur hexafluoride (SF6)
Authors: Schlamp Stefan , Rösgen Thomas
Published: March 2004

Strong density and speed of sound gradients exist in fluids near their liquid-vapor critical point under gravity. The speed of sound has an increasingly sharp minimum and acoustic waves are channelled within a layer of fluid. Geometrical acoustic calculations are presented for different isothermal fluid columns of sulfur hexafluoride (SF6) under gravity using a semiempirical crossover equation of state. More than 40% of the emitted acoustic energy is channelled within a 20 mm high duct at 1 mK above the critical temperature. It is shown how, by changes in temperature, frequency, and gravitational strength, the governing length scales (wavelength, radius of ray curvature, and correlation length of the critical density fluctuations) can be varied. Near-critical fluids allow table-top sound channel experiments.
Travel time stability in weakly range-dependent sound channels
Authors: Beron-Vera Francisco J. , Brown Michael G.
Published: March 2004

Travel time stability is investigated in environments consisting of a range-independent background sound-speed profile on which a highly structured range-dependent perturbation is superimposed. The stability of both unconstrained and constrained (eigenray) travel times is considered. Both general theoretical arguments and analytical estimates of time spreads suggest that travel time stability is largely controlled by a property ω′ of the background sound-speed profile. Here, 2π/ω(I) is the range of a ray double loop and I is the ray action variable. Numerical results for both volume scattering by internal waves in deep-ocean environments and rough surface scattering in upward-refracting environments are shown to confirm the expectation that travel time stability is largely controlled by ω′.
A high-resolution algorithm for wave number estimation using holographic array processing
Authors: Roux Philippe , Cassereau Didier , Roux André
Published: March 2004

This paper presents an original way to perform wave number inversion from simulated data obtained in a noisy shallow-water environment. In the studied configuration an acoustic source is horizontally towed with respect to a vertical hydrophone array. The inversion is achieved from the combination of three ingredients. First, a modified version of the Prony algorithm is presented and numerical comparison is made to another high-resolution wave number inversion algorithm based on the matrix-pencil technique. Second, knowing that these high-resolution algorithms are classically sensitive to noise, the use of a holographic array processing enables improvement of the signal-to-noise ratio before the inversion is performed. Last, particular care is taken in the representations of the solutions in the wave number space to improve resolution without suffering from aliasing. The dependence of this wave number inversion algorithm on the relevant parameters of the problem is discussed.
Dynamics of frequency and amplitude modulations in vocalizations produced by eastern towhees, Pipilo erythrophthalmus
Authors: Nelson Brian S.
Published: March 2004

Eastern towhees, Pipilo erythrophthalmus (Emberizidae, Passeriformes), appear to estimate source-SPL using spectral or temporal variables. Nevertheless, vocalizations are dynamic by nature and it remains unclear whether subjects pay attention to correlations between discrete variables or pay attention to the dynamics that these variables summarize. Sine functions are used to describe coarse (slow, <10 Hz) frequency and amplitude modulations in towhee calls and correlations between variables are identified. Towhee calls are also finely (rapidly, >400 Hz) modulated in both amplitude and frequency. Fine amplitude and frequency modulations correlate well (occur in phase) over relatively low fundamental frequencies (<∼3.5 kHz) and tend to have greater amplitudes and frequencies over these same frequencies. Modulations and correlations between modulations might exist due to stable dynamic interactions that occur within and between the physical forces that function to produce modulations in vocalizations. Results support the hypothesis that towhees communicate within separate sound frequency channels defined to each side of ∼3.5 kHz.
A pole-zero representation for the admittance matrix of elastic beam and plate systems
Authors: Photiadis Douglas M. , Marcus Martin H.
Published: March 2004

The behavior of coupled elastic systems is often analyzed in terms of the admittances or impedances of the component systems. In many applications, the admittances are approximated by a small number of simple oscillators; i.e., a low-order truncation of the normal-mode expansion. Such an approach is reasonable in the neighborhood of system resonances, but is much less convenient and accurate in the neighborhood of antiresonances. Pole-zero product expansions of the sort employed in circuit analysis offer a potential means of improving the accuracy of low-order approximations. The validity of such representations of the admittance matrix is explored here, and it is noted that in general the off-diagonal components cannot be written in this fashion. Nevertheless, it is shown below that the entire admittance matrix of beam and plate strip systems can always be represented in the pole-zero product form. Further, the representation is shown to be valid even when the beam or plate is coupled to an arbitrary conservative elastic structure.
Experimental studies of a thermoacoustic Stirling prime mover and its application to a cooler
Authors: Ueda Y. , Biwa T. , Mizutani U. , Yazaki T.
Published: March 2004

An acoustic field spontaneously induced in a thermoacoustic prime mover consisting of a looped tube and resonator is determined through simultaneously measurements of pressure P and velocity U. A thermal efficiency of the thermoacoustic prime mover of this type has been reported to reach 30%. The measurements of the acoustic field in the present system revealed that a phase lead of U relative to P takes a negative value of about −20° in the regenerator where the output power of the prime mover is generated. It was concluded that the possession of a negative phase lead at this position is taken as a clue in a significant increase in the output power. Moreover, the analysis in the thermoacoustic mechanism shows that a precise position for the location of a second regenerator acting as a heat pump exists in the looped tube. Indeed, by locating the second regenerator at the position, a thermoacoustic cooler was constructed. The thermoacoustic cooler could generate a low temperature of −25 °C without involving any moving parts.
Vibration criteria for transit systems in close proximity to university research activities
Authors: Wolf Steven
Published: March 2004

As some of the newer LRT projects get closer to research facilities the question arisesi ‘‘how do you assess the potential impact of train operations on the activities within these types of facilities?’’ There are several new LRT projects that have proposed alignments near or under university research facilities. The traditional ground vibration analysis at these locations is no longer valid but requires a more sophisticated approach to identifying both criteria and impact. APTA, ISO, IES, and FTA vibration criteria may not be adequate for the most sensitive activities involving single cell and nano technology research. The use of existing ambient vibration levels is evaluated as a potential criteria. A statistical approach is used to better understand how the train vibration would affect the ambient vibration levels.
Acoustic influence in crosslanguage phone mapping: Sibilant fricative place mismatch from English to Korean
Authors: Suh Yunju
Published: March 2004

The loanword adaptation and second language production of the English voiceless palatoalveolar fricative into Korean shows an interesting mismatch in tongue position. Korean palatalizes its alveolar fricative to alveolopalatal before high front vocoids. However, English voiceless palatoalveolar fricative before a high front vowel is adapted as an alveolar fricative with the secondary articulation of lip rounding, instead of an alveolopalatal. This paper argues that the failure to use the articulatorily closer Korean alveolopalatal fricative is due to Korean listeners’ interpreting English acoustic patterns in terms of the phonetic, especially acoustic, expectations of their native language. That is, Korean listeners attend more to the peak frequency of the English fricative than to the actual tongue position, and map it to their native fricative sound with the spectral peak at the closest frequency. Data collected from female speakers of American English and Korean show that, from fricative midpoint to end, the highest intensity spectral peaks are located at similar frequencies for English palatoalveolar and Korean rounded alveolar fricatives, while those of the Korean alveolopalatal are 1500–2000 Hz higher. This serves as another piece of evidence that second language/loanword adaptation is crucially affected by fine details of L1 and L2 phonetics.
General practitioner management of intimate partner abuse and the whole family: qualitative study
Authors: Taft Angela , Broom Dorothy H , Legge David
Published: March 2004

Objective To explore management by general practitioners of victimised female patients, male partners who abuse, and children in the family.

Design Triangulated qualitative study comparing doctors' reported management with current recommendations in the literature.

Participants 28 general practitioners attending continuing medical education about management of domestic violence.

Results Doctors perceived partner abuse in diverse ways. Their gender, perceptions, and attitudes could all affect identification and management of this difficult problem. A few doctors practised in recommended ways, but many showed stress and aversion, difficulties in resolving the tensions involved in managing all family members, and neglect of the risks to children. Some doctors used contraindicated practices, such as breaking confidentiality and undertaking or referring for couple counselling. Doctors who were not familiar with community based agencies were reluctant to use them. A lack of expertise and support could have a negative impact on doctors themselves.

Conclusions General practitioners managing partner abuse need to be more familiar with and apply the central principles of confidentiality and safety of women and children. Recommended guidelines for managing the whole family should be developed. Doctors should consider referring one partner elsewhere and avoid couple counselling; always ask about and act on the children's welfare; refer to specialist family violence agencies; and seek training, supervision, and support for the inherent stress. Medical education and administration should ensure comprehensive training and support for doctors undertaking this difficult work.
Effects of training on quality of peer review: randomised controlled trial
Authors: Schroter Sara , Black Nick , Evans Stephen , Carpenter James , Godlee Fiona , Smith Richard
Published: March 2004

Objective To determine the effects of training on the quality of peer review.

Design Single blind randomised controlled trial with two intervention groups receiving different types of training plus a control group.

Setting and participants Reviewers at a general medical journal.

Interventions Attendance at a training workshop or reception of a self taught training package focusing on what editors want from reviewers and how to critically appraise randomised controlled trials.

Main outcome measures Quality of reviews of three manuscripts sent to reviewers at four to six monthly intervals, evaluated using the validated review quality instrument; number of deliberate major errors identified; time taken to review the manuscripts; proportion recommending rejection of the manuscripts.

Results Reviewers in the self taught group scored higher in review quality after training than did the control group (score 2.85 v 2.56; difference 0.29, 95% confidence interval 0.14 to 0.44; P = 0.001), but the difference was not of editorial significance and was not maintained in the long term. Both intervention groups identified significantly more major errors after training than did the control group (3.14 and 2.96 v 2.13; P < 0.001), and this remained significant after the reviewers' performance at baseline assessment was taken into account. The evidence for benefit of training was no longer apparent on further testing six months after the interventions. Training had no impact on the time taken to review the papers but was associated with an increased likelihood of recommending rejection (92% and 84% v 76%; P = 0.002).

Conclusions Short training packages have only a slight impact on the quality of peer review. The value of longer interventions needs to be assessed.
Survival after surgery or therapeutic catheterisation for congenital heart disease in children in the United Kingdom: analysis of the central cardiac audit database for 2000-1
Authors: Gibbs John L , Monro James L , Cunningham David , Rickards Anthony
Published: March 2004

Objectives To analyse simple national statistics and survival data collected in the central cardiac audit database after treatment for congenital heart disease and to provide long term comparative statistics for each contributing centre.

Design Prospective, longitudinal, observational, national cohort survival study.

Setting UK central cardiac audit database.

Main outcome measures Survival at 30 days and one year after treatment in the year April 2000-March 2001, assessed by using both volunteered life status and independently validated life status through the Office for National Statistics, using the patient's unique NHS number, or the general register offices of Scotland and Northern Ireland. Institutional results following a group of six benchmark operations and three benchmark catheterisation procedures.

Results Since April 2000 data have been received from all 13 UK tertiary centres performing cardiac surgery or therapeutic cardiac catheterisation in children with congenital heart disease. Altogether 3666 surgical procedures and 1828 therapeutic catheterisations were performed. Central tracking of mortality identified 469 deaths, 194 occurring within 30 days and 275 later. Forty two of the 194 deaths within 30 days were detected by central tracking but not by volunteered data. For surgery overall, survival at 30 days was 94.9%, falling to 91.2% at one year; this effect was most marked for infants. For therapeutic catheterisation survival at 30 days was 99.1%, falling to 98.1% at one year. Survival of individual centres or individual operators did not differ from the national average after benchmark procedures.

Conclusions Independent data validation is essential for accurate survival analysis. One year survival gives a more realistic view of outcome than traditional perioperative mortality. Currently no detectable difference exists in survival between any of the 13 UK tertiary congenital heart disease centres, but confidence intervals for small centres are wide, limiting our power to detect underperformance from analysis of a single year's data. Appropriately resourced, focused national audit is capable of accurate data collection on which nationwide, long term quality control can be based.
Rate of convergence of bounded variation functions by a Bézier‐Durrmeyer variant of the Baskakov operators
Authors: Gupta Vijay , Abel Ulrich
Published: March 2004

We consider a Bézier‐Durrmeyer integral variant of the
Baskakov operators and study the rate of convergence for
functions of bounded variation.
Symmetry group analysis and invariant solutions of hydrodynamic‐type systems
Authors: Sheftel M. B.
Published: March 2004

We study point and higher symmetries of systems of the
hydrodynamic type with and without an explicit dependence on
t, x. We consider such systems which satisfy the existence
conditions for an infinite‐dimensional group of hydrodynamic
symmetries which implies linearizing transformations for these
systems. Under additional restrictions on the systems, we obtain
recursion operators for symmetries and use them to construct
infinite discrete sets of exact solutions of the studied
equations. We find the interrelation between higher symmetries and
recursion operators. Two‐component systems are studied in more
detail than n‐component systems. As a special case, we consider
Hamiltonian and semi‐Hamiltonian systems of
Tsarëv.
Interpolation methods to estimate eigenvalue distribution of some integral operators
Authors: El-Shobaky E. M. , Abdel-Mottaleb N. , Fathi A. , Faragallah M.
Published: March 2004

We study the asymptotic distribution of eigenvalues of
integral operators Tk defined by kernels k which
belong to Triebel‐Lizorkin function space by using the factorization theorem and
the Weyl numbers xn. We use the relation between
Triebel‐Lizorkin space and Besov
space and the interpolation
methods to get an estimation for the distribution
of eigenvalues in Lizorkin spaces .
On Chung‐Teicher type strong law for arrays of vector‐valued random variables
Authors: Kuczmaszewska Anna
Published: March 2004

We study the equivalence between the weak and strong laws of
large numbers for arrays of row‐wise independent random elements
with values in a Banach space ℬ. The conditions
under which this equivalence holds are of the Chung or
Chung‐Teicher types. These conditions are expressed in terms of
convergence of specific series and o(1) requirements on
specific weighted row‐wise sums. Moreover, there are not any
conditions assumed on the geometry of the underlying Banach space.
Completely multiplicative functions arising from simple operations
Authors: Laohakosol Vichian , Pabhapote Nittiya
Published: March 2004

Given two multiplicative arithmetic functions, various conditions
for their convolution, powers, and logarithms to be completely
multiplicative, based on values at the primes, are derived
together with their applications.
Skew‐symmetric vector fields on a CR‐submanifold of a para‐Kählerian manifold
Authors: Mihai Adela , Rosca Radu
Published: March 2004

We deal with a CR‐submanifold M of a para‐Kählerian manifold
, which carries a J‐skew‐symmetric vector field
X. It is shown that X defines a global Hamiltonian of the
symplectic form Ω on M⊤ and JX is a relative
infinitesimal automorphism of Ω. Other geometric
properties are given.
Extracellular fibrinogen binding protein, Efb, from Staphylococcus aureus binds to platelets and inhibits platelet aggregation
Authors: Shannon Oonagh , Flock Jan-Ingmar
Published: March 2004

S. aureus produces and secretes a protein, extracellular fibrinogen binding protein (Efb), which contributes to virulence in wound infection. We have shown here that Efb is a potent inhibitor of platelet aggregation. Efb can bind specifically to platelets by two mechanisms; 1) to fibrinogen naturally bound to the surface of activated platelets and 2) also directly to a surface localized component on the platelets. This latter binding of Efb is independent of fibrinogen. The specific binding of Efb to the putative receptor on the platelet surface results in a stimulated, non-functional binding of fibrinogen in a dose dependent manner, distinct from natural binding of fibrinogen to platelets. The natural binding of fibrinogen to GPIIb/IIIa on activated platelets could be blocked by a monoclonal antibody against this integrin, whereas the Efb-mediated fibrinogen binding could not be blocked. The enhanced Efb-dependent fibrinogen binding to platelets is of a nature that does not promote aggregation of the platelets; instead it inhibits aggregation. The anti-thrombotic action of Efb may explain the effect of Efb on wound healing, which is delayed in the presence of Efb.
Injection of recombinant activated factor VII can induce transient increase in circulating procoagulant microparticles
Authors: Hugel Bénédicte , Guillet Benoit , Trichet Catherine , Rafowicz Anne , Lambert Thierry , Freyssinet Jean-Marie , Dreyfus Marie , Proulle Valérie
Published: March 2004

Recombinant activated factor VII (rFVIIa) is an effective haemostatic treatment in haemophiliacs with inhibitors. In vitro, FVIIa concentrations corresponding to those obtained with therapeutic doses of rFVIIa have been shown to induce normal thrombin generation and platelet activation in the absence of factors VIII or IX. To further study the in vivo haemostatic changes induced by rFVIIa, circulating procoagulant microparticles (MP) were measured in patients treated with discontinuous injections of Novoseven®. In 6 out of 15 patients, a transient peak of procoagulant MP was observed after injection, occurring 15 min to 2 h after infusion. It was composed primarily of platelet-derived MP and was of very short duration. This peak was not observed in haemophiliacs without inhibitor, who were treated with conventional replacement therapies. Our results provide further in vivo evidence that rFVIIa specifically activates platelets, either directly or as a consequence of a burst of thrombin generation that could account for its haemostatic efficacy.
Contribution of PAR-1, PAR-4 and GPIbα in intracellular signaling leading to the cleavage of the β3 cytoplasmic domain during thrombin-induced platelet aggregation
Authors: Dubois Christophe , Steiner Beat , Meyer Reigner Sylvie
Published: March 2004

Integrin αIIbβ3 plays a pivotal role in platelet aggregation by binding to fibrinogen. The β3 cytoplasmic domain of αIIbβ3 interacts with cytoskeletal and signaling proteins and is cleaved by µ-calpain, a calcium regulated cysteine protease. In the present study, we have investigated in more detail the cleavage of the β3 cytoplasmic domain during platelet aggregation induced by thrombin, TRAP-1 and TRAP-4. Our data show that β3 is cleaved in all three cases. The time course of β3 cleavage and the amount of cleaved β3 depends on the way platelets are activated and on the complete activation of µ-calpain, with a maximum of 90% of cleaved β3 obtained when thrombin is used. Furthermore, our results also show that the cleaved αIIbβ3 is mainly distributed in the Triton soluble fraction, indicating its inability to bind to the cytoskeleton. Interestingly, in the absence of GPIbα or following inhibition of thrombin binding to GPIbα, there is a reduction in the thrombin-induced calcium flux, β3 cleavage and µ-calpain activation. These results suggest that cleavage of the β3 cytoplasmic domain by µ-calpain might be an important step regulating the link between the cytoskeleton and αIIbβ3 during platelet aggregation, and that GPIbα could function as a cofactor for the complete activation of platelets by thrombin.
Plasminogen activator inhibitor-type 1: its plasma determinants and relation with cardiovascular risk
Authors: Hoekstra Tiny , Schouten Evert , Kluft Cees , Geleijnse Johanna
Published: March 2004

The habitual level of PAI-1 is influenced by many factors, of which obesity and insulin resistance are the most important. It is possible to reduce plasma PAI-1 by changes in life style, e.g. weight reduction and physical activity. Data on potential interactions between environmental and metabolic variables on one hand, and the 4G/5G-polymorphism on the other hand, are still scarce. It becomes more and more clear that PAI-1 may possibly not be a major (causal) factor in cardiovascular disease, but its role in inflammation deserves further attention. In the presence of the 4G-allele not only the PAI-1 response was more pronounced, but also the response of other acute-phase reactants, which implies that the increases of these reactants are secondary to the increase in PAI-1. A myocardial infarction also provokes an acute phase response. It can thus be hypothesized that the 4G-allele might exacerbate tissue injury during the acute phase after a myocardial infarction, and thereby negatively affect the prognosis.
Elevated coagulation factor VIII and the risk for recurrent early pregnancy loss
Authors: Dossenbach-Glaninger Astrid , van Trotsenburg Michael , Krugluger Walter , Dossenbach Martin , Oberkanins Christian , Huber Johannes , Hopmeier Pierre
Published: March 2004

Inherited and acquired thrombophilia are associated with recurrent pregnancy loss. Recently, an increased risk for thromboembolic disease was described for patients with elevated coagulation factor VIII, but it is unknown whether there is also an association to early pregnancy loss. We therefore evaluated the relation between recurrent early pregnancy loss and levels of coagulation factor VIII. We enrolled 49 unrelated Caucasian women with a history of 2 6 early pregnancy losses and 48 healthy controls, who had delivered at least one term infant and had never experienced pregnancy loss. We determined factor V Leiden-, G20210A prothrombin-, MTHFR C677Tand A1298Cgene mutations, levels of antithrombin, protein C, protein S, factor VIII, C-reactive protein and antiphospholipid antibodies. There was a significantly higher rate of pregnancy losses in women with Antiphospholipid Syndrome (p = 0.043). Furthermore, plasma levels of coagulation factor VIII were significantly higher in cases than in controls (130.5 IU/dl ± 25.4 vs 119.5 IU/dl ± 24.1; p = 0.032) and appeared independent of Creactive protein (R = 0.146, p = 0.323 in cases; R = 0.028, p = 0.850 in controls). The relative risk for recurrent pregnancy loss in women with factor VIII levels above 151 IU/dl (90th percentile of controls) was 2.5 (0.7 – 8.9, 95 percent confidence interval), for levels above 156 IU/dl (95th percentile of controls) 3.9 (0.8 – 20.0, 95 percent confidence interval). Elevated maternal plasma levels of coagulation factor VIII tend to be associated with an increased risk for recurrent early pregnancy loss.
Use of soluble fibrin antigen instead of D-dimer as fibrin-related marker may enhance the prognostic power of the ISTH overt DIC score
Authors: Wurst Michael , Smolinski Mathias , Lorenz Stephan , Osika Alexandra , Olenik Daniela , Fiedler Fritz , Borggrefe Martin , Dempfle Carl-Erik
Published: March 2004

The overt DIC score of the DIC subcommittee of the ISTH includes a fibrin-related marker (FRM) as indicator of intravascular fibrin formation. The type of marker to be used has not been specified, but D-dimer antigen, or fibrin degradation products are used by most investigators. Soluble fibrin complexes have been suggested as more specific indicators of acute intravascular fibrin formation. The aim of the present study was to compare the predictive value of the overt DIC score concerning clinical outcome in a surgical intensive care cohort, using either D-dimer antigen, or soluble fibrin antigen as FRM. The cutoff values for 2 and 3 score points for the FRM were assigned on the basis of the 25% and 75% quartiles of 1870 plasma samples obtained from 359 ICU patients during a period of 6 months. For 331 patients with complete diagnostic workup and day 1 blood samples, the Iatro SF as FRM component of the overt DIC score displayed the highest prognostic power concerning clinical outcome. The 28-day mortality of patients with overt DIC at day 1, using Iatro SF as FRM assay was 50.0%, whereas 28-day mortality of patients without overt DIC was 14.0% (p <0.0001). Using MDA D-dimer, and TINAquant D-dimer, 28-day mortality was between 35.5% and 39.3% in patients with overt DIC, and 15.5% to 15.6% in patients without overt DIC. Selection of the FRM as component of the DIC score has a small, but relevant impact on the prognostic performance of the overt DIC score. The present data on the distribution of values may provide a basis for the selection of appropriate cutoff points for assigning 2, and 3 points in the score.