bluuebunny/crossref_metadata_2025 huggingface dataset:
An adaptive equalization scheme using acoustic energy density
Authors: Chen Xi , Sommerfeldt Scott D. , Leishman Timothy W.
Published: September 2013

This paper presents an equalization system based on the filtered-x algorithm and acoustic energy density. Previous theoretical results have shown that equalization filters using acoustic energy density produce greater spatial uniformity in equalization than those using acoustic pressure. The paper discusses the implementation of the equalization system in a one-dimensional duct. An adaptive algorithm is utilized in the time domain to determine and apply the equalization filter. Results from a traditional filter design and the energy density filter design are compared.
Separation and identification of a transient signal using the characteristics of eigenvectors
Authors: Larue James P. , Smith George B. , Ioup George E. , Ioup Juliette W.
Published: September 2013

This is an extension of previous research [Larue et al., J. Acoust. Soc. Am. 113, 2212 (2003)] into the physical characteristics possessed by eigenvectors in a singular value decomposition (SVD) of a covariance matrix formed from a sinusoidal signal corrupted by multipath to which Gaussian noise is added. An animation of the SVD in progress will focus on the creation of the eigenvectors rather than the singular values. In this case, the SVD forms a three-part subspace decomposition corresponding to the three components of the signal. These subspaces are clearly determined from characteristics (Fourier transform and the Kaiser Varimax norm) associated with the eigenvectors and are not so easily determined from the singular values alone. [Research supported by the NRC-AFRL/IFEC and ONR.]
Two-dimensional Gabor analysis of space–time transient Lamb waves using Laser ultrasonic investigation
Authors: Martinez Loic , Van Riet Nikolaas , Glorieux Christ
Published: September 2013

Laser generation/detection methods allow the investigation of ultrasonic transient phenomena in both space and time dimensions. Used for the experimental investigation of surface wave propagation along a one-dimensional medium, laser ultrasonics leads to two-dimensional (2D) space–time signal collections. In order to extract the wave propagation information, the classical high resolution signal processing methods or 2D Fourier transforms are not suitable to identify the transient and local aspect of wave propagation and mode conversion. In order to quantify these transient aspects in the space–time-wave number–frequency domains, the 2D Gabor transform is introduced. Its potential for the identification of the local and transient complex wave numbers is illustrated on the propagation of Lamb waves on a plane limited plate. The mode conversion sequences are clearly identified in the space–time–wave number-frequency planes. The experimental results are in good agreement whith the numerical simulations.
Phase velocimetry based on the spatio-temporal gradient analysis for detecting subsurface defects
Authors: Teramoto Kenbu
Published: September 2013

Ultrasonic Lamb-wave techniques are potential candidates of nondestructive evaluation (NDE) methodology: they allow the detection of surface defects or internal delamination. Because they propagate over a long distance, weakly attenuated in the case of a free-elastic plate, they are used for the evaluation of the assembly of large free plates in aeronautics, for example. The phase velocity of A0-mode Lamb-wave increases with thickness of the plate. Delaminations or internal defects, therefore, make the phase velocity slower. In this paper, an instantaneous phase velocimetry based on the spatio-temporal gradient analysis is proposed. The proposed method has an ability to measure the phase velocity of A0-mode Lamb wave field through the linearity among the four-dimensional vectors which is defined by following components: (1) a vertical displacement; (2) its vertical velocity; and (3) and (4) a pair of out-of-plane shear strains of the plate. In this study, the computational process of the local velocimetry is discussed and its physical meanings are investigated through FDTD simulations. Several results obtained through the proof-of-concept model are in relatively good agreement with the simulations.
Precise measurement of travel time in 1999 OAT experiment
Authors: Yong Wang , Hiroyuki Hachiya
Published: September 2013

The 1999 OAT experiment is performed in the Central Equatorial Pacific to monitor the ocean phenomenon associated with El Niño and the Southern Oscillation (ENSO). In order to analyze the travel-time perturbations due to ocean current, amplitude information of the received signal is used in the conventional method. However, it is difficult to measure the travel-time difference precisely, mainly because of the attenuation of long-range transmission. In this report, we propose a new technique which is the complex vector method by using the amplitude and phase information. From the ray identification results, we estimated the travel-time difference between corresponding rays of the reciprocal transmissions. Since the phase of a ray signal is very stable in 130-s signal duration time, the precision of the measurement of the travel-time difference using phase difference is higher than the conventional estimation. The travel-time differences estimated by using this method have reasonable magnitudes.
Advanced sonar array concepts for small underwater vehicle applications
Authors: Benjamin Kim C.
Published: September 2013

Low-frequency acoustic reception and high directivity are difficult to obtain simultaneously using small undersea (robot) platforms. The dimensions and geometry of the hydrodynamic shapes that are required for efficient transit through the water preclude the use of broad apertures required for low-frequency directional applications. This paper will present array concepts that could be considered the next step in developing low-frequency directional acoustic payloads for undersea research and exploration. The talk will include results of previous Navy experimental demonstrations of wide aperture arrays for small vehicles as well as future advanced sonar packaging concepts that rely on new transduction technologies. [Work supported by the U.S. Navy.]
Acoustic navigation for autonomous underwater vehicles
Authors: Yang Wen-Bin , Yang T. C.
Published: September 2013

To effectively use groups of autonomous underwater vehicles (AUVs), an accurate navigation capability must be developed. We describe an acoustic navigation technique that uses an acoustic communications probe signal to estimate the range, range rate and direction of arrival signal. The acoustic signal may be transmitted from one vehicle or node (e.g., AUV, ship or fixed mooring) to another. The technique was tested during the RAGS03 experiment. A towed acoustic communications receiver that replicated the motion of an AUV and a fixed source node were used. The receiver was navigated with a global position system (GPS). The range, range rate and direction of arrival signal have been estimated using the acoustic signal received on a horizontal line array. The results are compared to the known GPS source and receiver positions. The navigation technique will be discussed. Its advantages over the traditional navigation by multiple transponders will be outlined. [Work supported by the ONR.]
Archaeological acoustics—A guide to trends in community noise levels
Authors: Raichel Daniel R. , Brooks Bennett M. , Lubman David
Published: September 2013

Archaeological acoustics may be defined as assessment of the acoustical situations of the past by the use of scientific methods in examining the available remaining evidence. These principles may be applied to the study of historic trends in community noise by measuring the types of noise sources prevalent at the time, estimating the noise level of the environment on the basis of information as to types and number of noise sources, amount of traffic and industry, types of road surfaces, and layout of surrounding buildings and local landscaping. For instance, the clopping of horses and wagons passing by can be measured with modern instruments at current-day rodeos, parades, and exhibitions. The noise levels can be transposed to a bygone scene through acoustical analyses, possibly with computer-aided methodologies. Archives can be consulted for population density, details of buildings that existed at the time, paving types of streets, presence of sidewalks, amount of commercial and pedestrian traffic, etc. Estimates of the noise levels in major cities for specific periods of time can lead to detection of noise trends over a period of centuries. Several noise trend estimate examples are illustrated.
Comparative analysis of the urban noise between two different areas in the city of Curitiba, PR
Authors: Paz Elaine C. , Ferreira Andressa C. , Zannin Paulo T.
Published: September 2013

The purpose of this work is to analyze the urban noise perception comparatively in the inhabitants of a residential area (neighborhood) and a mixed area (center), in the city of Curitiba, PR, in order to characterize two different situations: (1) acoustically ideal urban environment; and (2) acoustically polluted urban environment. For that, subjective and objective evaluations were accomplished, where an aleatory sample of each area was submitted to a survey. In the objective evaluation, the medium equivalent sound levels calculated were 53.50 dB(A) and 72.90 dB(A) for the neighborhood and center, respectively. The parameters used for comparison of the calculated medium equivalent sound levels where the values of 55.00 dB(A) (Municipal Law No. 10.625) and 65.00 dB(A) (WHO), in the period of the day for residential areas. The interpretation of the subjective results verified that the central zone inhabitants have an annoyance perception bigger than the residential zone inhabitants. The interpretation of the objective results classified the neighborhood and center areas as acoustically control zone and acoustically polluted zone, respectively, according to the adopted parameters. Starting from the comparison between these two areas, it was defined that both can be classified as reference factor for other evaluations.
Ultrasonic inhomogeneous waves: Three decades of fascination
Authors: Declercq Nico F. , Briers Rudy , Degrieck Joris , Leroy Oswald
Published: September 2013

Inhomogeneous waves are mathematically described as pure homogeneous plane waves except for the important fact that all wave parameters, i.e., wave vector, polarization vector and frequency, can be complex valued. Even though the existence of a complex wave vector was known for a long time, Henry Cooper was the first to study such waves and their interaction with interfaces. It was not until 1980 that researchers became aware of the fact that inhomogeneous waves are mandatory phenomena in the description of reflection/transmission phenomena between lossy media. Later, it was shown that inhomogeneous waves also formed natural building blocks of bounded beams and formed a physical explanation for the Schoch effect. This paper describes this development from a historical point of view and describes scientific properties (e.g., their polarization, dispersion) whenever needed in order to understand the evolution from 1980 until the present. All topics of inhomogeneous wave research are taken into account, such as waves in viscoelastic solids and liquids, thermo-viscous liquids and solids, anisotropic viscoelastic materials, periodically rough materials, the features of complex frequency and the experimental generation of inhomogeneous waves. [Work supported by The Flemish Institute for the Encouragement of the Scientific and Technological Research in Industry (I.W.T.).]
Acoustical properties of gravel
Authors: Attenborough Keith , Umnova Olga
Published: September 2013

Gravel is an example of a rigid-porous granular material. It is available with several mean stone sizes and hence with a range of flow resistivity. The flow resistivity of gravel varies significantly with flow velocity. Data for low- and high-amplitude impedance are presented and compared with predictions of linear and nonlinear theories based on the Johnson-Allard model for rigid-porous media. Comparisons are made also between data and predictions for shock wave reflection and transmission at single- and multiple-layer gravel surfaces including recent data obtained with laser-generated acoustic shocks. Tolerable agreement is obtained between data and predictions. It is found that a low flow resistivity gravel layer has a reflection coefficient that has a minimum as the incident pressure is increased. A layered system that offers the lowest reflection coefficient at linear sound pressures does not continue to do so as the incident pressure is increased. [Work supported by USACE ERDC BT25 program.]
Identification and discrimination of Spanish front vowels
Authors: Castellanos Isabel , Lopez-Bascuas Luis E.
Published: September 2013

The idea that vowels are perceived less categorically than consonants is widely accepted. Ades [Psychol. Rev. 84, 524–530 (1977)] tried to explain this fact on the basis of the Durlach and Braida [J. Acoust. Soc. Am. 46, 372–383 (1969)] theory of intensity resolution. Since vowels seem to cover a broader perceptual range, context-coding noise for vowels should be greater than for consonants leading to a less categorical performance on the vocalic segments. However, relatively recent work by Macmillan et al. [J. Acoust. Soc. Am. 84, 1262–1280 (1988)] has cast doubt on the assumption of different perceptual ranges for vowels and consonants even though context variance is acknowledged to be greater for the former. A possibility is that context variance increases as number of long-term phonemic categories also increases. To test this hypothesis we focused on Spanish as the target language. Spanish has less vowel categories than English and the implication is that Spanish vowels will be more categorically perceived. Identification and discrimination experiments were conducted on a synthetic /i/-/e/ continuum and the obtained functions were studied to assess whether Spanish vowels are more categorically perceived than English vowels. The results are discussed in the context of different theories of speech perception.
Role of experience in eliciting perceptual overshoot with sine waves
Authors: Aravamudhan Radhika , Hawks John W.
Published: September 2013

Previous studies in vowel perception have demonstrated perceptual overshoot (PO) with vowels in CVC contexts. The first experiment investigated the elicitation of PO with speech and nonspeech signals. Boundary estimates were obtained for four continua: (1) steady-state synthetic vowels; (2) synthetic vowel transitions in /wV/ context; (3) sine wave analogs mimicking the steady-state vowels; and (4) sine wave analogs mimicking the transition continuum. Results replicated the findings of previous studies by demonstrating PO with synthetic vowels; however, PO was not elicited with the sine wave analogs. This led to a second experiment, where the role of training on the elicitation of PO with sine wave analogs was investigated. Subjects from the first experiment were divided into two groups. One group was trained to categorize the steady-state sine wave analogs based on their synthetic vowel boundary. Training occurred over 3–6 1-h sessions until subjects achieved 90%-correct identification. The control group received no training. Post-training boundary estimates were obtained for the four original continua from both groups. The results indicated that PO was now elicited with the sine wave analogs for the trained group, but not for the control group. Further implications of these findings will be discussed.
Information conveyed by vowels about other vowels
Authors: Javkin Hector R. , Drom Elaine , Christie Carol , Cangiano Gaston R.
Published: September 2013

Rapid adaptation to different speakers has become an important issue in speech recognition (ASR) but has been known in human listeners for a long time. Ladefoged and Broadbent [J. Acoust. Soc. Am. 29, 98–104 (1957)] demonstrated that human perception of synthesized vowels occurring in monosyllabic words (bit, bet, bat, but) can be changed by changing the formants of an introductory phrase (Please say what this word is). These stimuli meant that the introductory phrase ranged over the same portion of the vowel space (front vowels, or relatively high F2), thus facilitating listeners adaptation. To further test the limits of human adaptation, we replicated the experiment keeping the same words, substituting introductory phrases consisting of back (low F2) vowels, and maintaining a similar level of low-quality synthesized speech. The effects are difficult to replicate with natural or high-quality synthetic speech. However, we will suggest that low quality speech is analogous to the low-dimensionality representation of speech of many ASR front ends, which discard, for example, information as to the higher formants. Therefore, these findings are relevant to the use of adaptation in improving ASR. [Work supported by a Faculty Small Grant from San Jose State University.]
Movie MRI at five frames a second for evaluation of speech and swallowing
Authors: Kumada Masanobu , Mori Koichi , Nakajima Yasoichi , Nozaki Seiji
Published: September 2013

Magnetic resonance imaging (MRI) is a noninvasive imaging method that is widely used in the medical field. One of the limitations of MRI is its low time-resolution; images of MRI are usually obtained as still images. Here we introduced a newly developed method of ‘‘movie’’ MRI with high time-resolution at five images a second. Its good application would include study and evaluation of speech and swallowing. Instrument: MRT-2001 XG with Software ver.5.5. (Toshiba). Coil: head QD coil for the tongue; CTL ARRY coil (3ch) for the neck, Imaging condition: sagital FFE2D; TR=2.8 ms; TE=1.2 ms; FA=10 deg; Matrix=64×128; ST=10 mm; NAQ=1 AV; FOV=23×35 ; ROAFI; sequential acquisition. Maximum imaging length=51 s. A healthy Japanese male (Tokyo dialect speaker, 39 years). Task: Repetitive utterance of /tenten.../ and intentional swallowing of saliva. Results: In the task of /tenten..../, we could detect, in temporal order, velopharyngeal (VP) closure, opening of the tongue-palate (TP) closure, VP opening, TP closure, VP closure, and so on. In the swallowing task of saliva, we could detect movement of the tongue for conveying saliva to the pharynx, VP closure, backward movement of the tongue root, elevation and descent of the larynx in this temporal order. Our ‘‘Movie MRI’’ seemed promising for the noninvasive evaluation of speech and deglutition. Appropriate materials for swallowing evaluation will be presented.
Aeroacoustics production of fricative speech sounds
Authors: Krane Michael , Gary Settles
Published: September 2013

The aeroacoustic production of fricative speech sounds is studied using schlieren imaging and acoustic measurements. The focus is the structure of the turbulent jets formed during fricative speech sound production, and how interaction of the jet with articulators affects the acoustic nature of the speech sound. Patterns of the jets formed during the articulation of both voiced and unvoiced fricatives (s and z) are shown using schlieren images. In particular, the interaction of the jet with articulators such as teeth and lips are clearly seen, and demonstrated by varying articulator positions. Pressure measurements were made in conjunction with the images using a microphone placed near the teeth and one in the farfield. The pressure measurements show the acoustic consequences of the various jet/articulator interactions, further clarifying which articulators are most important in determining the aeroacoustic source characteristics.
My 65 years in acoustics
Authors: Beranek Leo L.
Published: September 2013

My entry into acoustics began as research assistant to Professor F. V. Hunt at Harvard University. I received my doctorate in 1940 and directed the Electro-Acoustic Laboratory at Harvard from October 1940 until September 1945. In 1947, I became a tenured associate professor at MIT, and, with Richard H. Bolt, formed the consulting firm Bolt and Beranek, that later included Robert B. Newman, becoming BBN. My most significant contributions before 1970 were design of wedge-lined anechoic chambers, systemization of noise reduction in ventilation systems, design of the world’s largest muffler for the testing of supersonic jet engines at NASA’s Lewis Laboratory in Cleveland, speech interference level, NC noise criterion curves, heading New York Port Authority’s noise study that resulted in mufflers on jet aircraft, and steep aircraft climb procedures, and publishing books titled, Acoustical Measurements, Acoustics, Noise Reduction, Noise and Vibration Control, and Music, Acoustics and Architecture. As President of BBN, I supervised the formation of the group that built and operated the ARPANET (1969), which, when split in two (using TCP/IP protocol) became the INTERNET (1984). Since then, I have written two books on Concert Halls and Opera Houses and have consulted on four concert halls and an opera house.
Monaural informational masking release in children and adults
Authors: Buss Emily , Hall Joseph W. , Grose John H.
Published: September 2013

Informational masking refers to an elevation in signal threshold due to stimulus uncertainty, rather than to energetic masking. This study assessed informational masking and utilization of cues to reduce that masking in children aged 5–9 and adults. We used a manipulation introduced by Kidd et al. [J. Acoust. Soc. Am. 95, 3475–3480 (1994)] in which the signal was a train of eight consecutive tone bursts, each at 1 kHz and 60 ms in duration. Maskers were comprised of a pair of synchronous tone-burst trains whose frequencies were selected from the range spanning 0.2–5 kHz, with a protected region 851–1175 Hz. In the reference condition, where informational masking is pronounced, these maskers were eight bursts and had a fixed frequency within each interval, with new frequencies chosen randomly prior to each interval. Two conditions of masking release were tested: random frequency selection for each masker burst and a masker leading fringe of two additional 60-ms bursts. Both children and adults showed a significant informational masking effect, with children showing a larger effect. Both groups also showed significant release from masking, though initial results suggest that this may have been reduced in the youngest children. [Work supported by NIH, RO1 DC00397.]
Impact of classroom noise on reading and vocabulary skills in elementary school-aged children
Authors: Allen Prudence , Brogan Nashlea , Allan Chris
Published: September 2013

Classroom noise levels often exceed recommendations and, in large scale retrospective studies, it has been suggested that higher noise levels often correlate significantly with poorer academic performance [e.g., Shield., et al. (2002)]. However, experimental data on the performance of individual children are limited. This study therefore examined the effect of noise on the performance of children in grades 3–4 and 7–8 on standardized tests of oral reading, silent reading, and vocabulary (the Gray Oral Reading Test, the Gray Silent Reading Test, and the Peabody Picture Vocabulary Test). Each child completed parallel forms of a test in quiet and in classroom noise presented at 60 dB SPL. Required speech was presented at +10 S/N. Results from grouped data showed significantly reduced performance in noise only on the silent reading task and only for the older group of children. However, across tasks, when the effects of noise were evaluated as a function of childrens quiet performance levels, the noise effect was shown to be significant for the children performing at above average levels in quiet. These findings suggest that the effect of classroom noise may vary significantly across tasks and children. [Work supported by CLLRNet.]
Methods to quantify opera houses acoustics—Changes to why, what, and how?
Authors: Harris Robert W
Published: September 2013

The historical and current reasons for quantifying opera house acoustics (the why?) are reviewed. The emerging shift from quantitiative assessment (by measurement) to qualitative assessment (by auralization) is discussed. The key characteristics of the acoustics of opera houses (the what?) are then considered. Assessment of a theatre with an audience present is suggested to be more important than unoccupied measurements. This has implications for the development of assessment methods. The suitability of classical room acoustics parameters—mostly derived from concert hall studies—is debated (the how?). Possible new assessment techniques are emerging. Characteristics not addressed by the classical parameters include the early (ensemble) and late (room) support provided to the singers and the onset threshold of image shifting of the sound of instruments within the orchestra pit. The assessment of loudness balance between the stage and the pit requires refinement and development. A difficulty with the assessment and comparison of opera houses is the effect of the stage settings on the acoustics.
A study of listening habits in adolescents: Correlating stated loudness preferences with actual listening levels
Authors: Warren Laura , Warren Jean , Cheenne Dominique
Published: September 2013

Evidence suggests that children are damaging their hearing in substantial numbers [Niskar et al., J. Am. Med. Assoc. (1998)]. Conventional thinking would suggest that cultural norms and attitudes contribute to a desire in children to model what they have seen in the media, thus implying that they would be listening to music at levels that are considered harmful. Our study focused on a gender-balanced group of 316 elementary-age students and aimed at assessing a correlation between an attitudinal survey related to loud music and the children’s own listening levels. The study was broader in scope and in sample size than previous work [Fucci, 138th ASA Meeting, 11/99]. Findings were both surprising and encouraging, citing that a majority of children who expressed favoritism towards loud music listened to the presented samples at lower levels than expected. The study also proposes a set of listening level distribution curves that may prove useful for future studies with older participants.
Vertical directivity of ambient noise in the presence of internal waves
Authors: Evans Richard B.
Published: September 2013

Near surface sources of ambient noise, such as shipping and wind, excite only steeply traveling sound waves. After a sufficient range, the steepest are stripped away by loss mechanisms, such as bottom interaction. Consequently, the vertical directivity of surface generated noise is expected to be peaked about two (up- and down-going) angles with very little contribution near the horizontal. This expectation is not always met in measurements. A possible explanation, for the noise at the horizontal, is the random scattering of the up- and down-going waves by volume inhomogeneities caused by internal waves. The purpose of this paper is to demonstrate the validity of this hypothesis. The coupled power theory of Dozier and Tappert [J. Acoust. Soc. Am. 63, 353–365 (1978)], in an updated form, is applied to the calculation of noise due to distant near surface sources. The vertical directivity of the resultant field is shown to demonstrate that internal wave scattering can produce noise at the horizontal. Rough surface scattering is expected to have a similar effect.
A theory for thermoelastic damping in MEMS and NEMS flexural oscillators
Authors: Norris Andrew
Published: September 2013

Intrinsic damping is a major roadblock in the drive to smaller high frequency RF oscillators, from the current mm size to MEMS and ultimately NEMS. Recent measurements on silicon MEMS platelike oscillators show that thermoelastic (TE) damping is the limiting damping mechanism. This talk will describe how the classical theory of Zener for TE damping needs to be revised for small thickness NEMS oscillators. A critical plate thickness is identified, separating thermally thick and thin regimes. In thermally thick oscillators the thermal diffusion is across the thickness, whereas in-plane thermal diffusion can dominate in thermally thin plates. Using the Kirchhoff assumption for the elastic deformation, it is shown that the local thermal relaxation loss depends upon the local state of vibrating flexure, specifically, the principal curvatures at a given point on the plate. The thermal loss is zero at points where the principal curvatures are equal and opposite, i.e., saddle shaped deformation. Effective plate equations are derived that incorporate TE loss as a damping term. A new form of the effective damping is obtained for both thermally thick and thin plates, generalizing the single relaxation Zener model. Applications to MEMS and NEMS oscillators will be discussed.
Science enabled by ocean observatory acoustics: The NSF ORION program
Authors: Howe Bruce M. , Miller James H.
Published: September 2013

The National Science Foundation (NSF) has started the Ocean Research Interactive Observatories Network (ORION) program for research-driven sustained observations. The core infrastructure will consist of: (1) a coarse global array of buoys, (2) a regional cabled observatory in the northeast Pacific (with Canada already funded for the northern portion), and (3) coastal observatories. Seafloor junction boxes providing power and communications are a common enabling feature. The ORION Workshop (Puerto Rico, 4–8 January 2004) developed science themes that can be addressed utilizing this infrastructure. Acoustics enable much of the science. The use of acoustics to sense the synoptic 3-D/volumetric ocean environment was found to be ubiquitous through most ORION working groups. One reason for this is the relative transparency of the ocean to sound and the opaqueness to electromagnetic radiation. Participants at the workshop formed an Acoustics Working Group. Based on its report, we review the science and technical drivers for acoustics and educational opportunities. Themes include inherent volumetric, near instantaneous sampling, robust transducers, imaging at many scales, navigation, communications, and using sound in the sea as a major education and outreach mechanism. Recommendations include the formation of a standing ORION committee on acoustics and a workshop. See http://www.orionprogram.org and http://www.oce.uri.edu/ao/AOWEBPAGE.
Magneto-elastic interactions in Fe–Ga alloys
Authors: Petculescu G. , Bass H. E. , Lorasso T. A. , Clark A. E.
Published: September 2013

The elastic anisotropy of iron’s most common α-structure increases significantly when gallium is substituted for a fraction of the iron. Concurrently occurring, the tremendous boost in tetragonal magnetostriction [one order of magnitude above that of pure Fe, 3/2λ100(Fe81Ga19)=400 ppm] makes Fe–Ga alloys important for magnetoelastic applications. Measurements of the elastic tensor of Fe–Ga single crystals, with or without a magnetic field and within 4–300 K, were performed using the resonant ultrasound spectroscopy technique on 100-cut rectangular parallelepipeds. In the vicinity of 24% Ga an anomaly occurs in the magnetostriction as well as in the elastic moduli and in the magnitude of their ΔE-effect, in an apparent conspiracy to maintain the magnetoelastic energy-constants (b1,2) ‘‘normal.’’ [Work supported by ONR.]
Multichannel time reversal communications in a highly reverberative environment
Authors: Candy James V. , Guidry Brian , Poggio Andrew , Kent Claudia
Published: September 2013

The development of point-to-point time-reversal (T/R) communications in a highly reverberative environment was discussed previously [Candy et al., J. Acoust. Soc. Am. Suppl. 1 114, 2367]. This paper focuses on the extension of that effort to the multichannel case. Here, we discuss the theoretical development of a suite of multichannel TR receiver realizations, similar to the point-to-point case, using an acoustic T/R array and a set of client stations. The performance of these processors on both simulated and experimental data is discussed in detail. The experiment is provided by a stairwell between two floors of a noisy building. The stairwell is populated with obstructions (pipes, rails, wall, etc.) and a 90-deg landing—clearly a highly reverberative environment. It is shown that the multichannel receivers perform quite well when compared to their point-to-point counterparts, and are able to reliably extract the transmitted code from the noisy measurements.
Assessing the accuracy of auralizations computed using a hybrid geometrical-acoustics and wave-acoustics method
Authors: Summers Jason E. , Takahashi Kengo , Shimizu Yasushi , Yamakawa Takashi
Published: September 2013

When based on geometrical acoustics, computational models used for auralization of auditorium sound fields are physically inaccurate at low frequencies. To increase accuracy while keeping computation tractable, hybrid methods using computational wave acoustics at low frequencies have been proposed and implemented in small enclosures such as simplified models of car cabins [Granier et al., J. Audio Eng. Soc. 44, 835–849 (1996)]. The present work extends such an approach to an actual 2400-m3 auditorium using the boundary-element method for frequencies below 100 Hz. The effect of including wave-acoustics at low frequencies is assessed by comparing the predictions of the hybrid model with those of the geometrical-acoustics model and comparing both with measurements. Conventional room-acoustical metrics are used together with new methods based on two-dimensional distance measures applied to time-frequency representations of impulse responses. Despite in situ measurements of boundary impedance, uncertainties in input parameters limit the accuracy of the computed results at low frequencies. However, aural perception ultimately defines the required accuracy of computational models. An algorithmic method for making such evaluations is proposed based on correlating listening-test results with distance measures between time-frequency representations derived from auditory models of the ear-brain system. Preliminary results are presented.
Differential effectiveness of cues in informational masking studies
Authors: Richards Virginia M. , Huang Rong , Kidd Gerald
Published: September 2013

For the detection of a tone added to random multitone maskers, playing a preview of the masker before detection trials can reduce thresholds compared to when there is no preview. In contrast, playing a preview of the signal-plus-masker does not provide a release from masking. This differential effectiveness of cues was examined in several conditions. Using the method of constant stimuli and a yes/no task, observers detected a 1000-Hz tone added to six-tone maskers. Prior to each trial, the frequencies of the masker components were randomly drawn. Two types of cues were tested, either a copy of the masker or a copy of the signal-plus-masker. The cues were presented either before or after the yes/no presentation interval. Finally, data were collected either blocked for each condition or the trials from the four conditions were interleaved. D-prime values were higher when the conditions were blocked than when they were interleaved. The pattern of results was the same in both situations; d was highest for pretrial masker cues, lowest for pretrial signal-plus-masker cues, and intermediate when either cue followed the trial interval. [Work supported by NIH/NIDCD.]
Analysis of risk factors for death after blunt traumatic rupture of the thoracic aorta
Authors: Franzen Daniel , Genoni Michele
Published: September 2013

Traumatic aortic rupture (TAR) is a rare but serious injury, leading to death at the scene in most cases. Between 1990 and 2003, all consecutive patients and victims with TAR were retrospectively analysed by reviewing hospital and autopsy records. Univariate and multivariate Cox regression analyses were performed to define determinants of mortality. During the study period, a total of 85 patients (70 men, mean age 47±18.8 years) with TAR were observed in the greater area of Zurich giving a population-based rate of 0.6 cases per 100 000 persons per year. Prehospital, in-hospital and overall mortalities were 40.0%, 31.4% and 58.8%, respectively, with a median survival time of 2 days (IQR 1–3617 days). In the univariate analysis, significant determinants of prehospital and overall mortality were age (HR 1.05, p=0.006), complete aortic transection (HR 7.17, p=0.003), number (HR 1.35, p=0.009) and associated injuries to chest (HR 3.41, p=0.03), liver (HR 6.00, p=0.002) and spine (HR 5.19, p=0.01). By comparison, risk factors for in-hospital mortality included haemodynamic instability upon arrival in the emergency room (HR 16.11, p<0.001) and open surgical repair (HR 14.29, p=0.02). In the multivariate model, only age (p=0.02) and complete aortic transection (p=0.001) were significant determinants of mortality. Therefore, with the exception of complete aortic transection, risk factors of prehospital and in-hospital death in patients with TAR differ greatly. The in-hospital mortality was not affected by the number or localisation of associated injuries, whereas haemodynamic instability and open aortic repair seem to predict in-hospital mortality after TAR.

Clinical Trial Registration

NCT01632774.
Emergency department management of early sepsis: a national survey of emergency medicine and intensive care consultants
Authors: Jiwaji Zoeb , Brady Shirin , McIntyre Lauralyn A , Gray Alasdair , Walsh Timothy S
Published: September 2013

Objectives

Early goal-directed therapy (EGDT) is recommended for sepsis management in current guidelines, but the underpinning evidence is controversial. Clinician beliefs and the capacity to implement all recommended elements of EGDT in emergency departments (EDs) are uncertain. Our study aimed to explore self-reported management of early sepsis by Scottish emergency medicine (EM) and intensive care medicine (ICM) consultants, delineate important differences and determine the guideline recommendations rated most important and deliverable within the ED.

Methods

A postal survey using a hypothetical patient with septic shock was sent to all EM and ICM consultants practising in Scotland.

Results

67% (76/114) EM and 61% (96/157) ICM consultants responded. Normal saline was preferred by EM respondents (‘always/often used’: EM 86%, ICM 23%, p<0.0001), whereas ICM respondents preferred Hartmann's solution (EM 42%, ICM 72%, p=0.0164), gelofusin (EM 10%, ICM 63%, p<0.0001) and starch (EM 0%, ICM 24%, p<0.0001). More ICM respondents indicated they used central venous pressure and invasive arterial pressure monitoring in the ED, and initiated vasopressors (EM 57%, ICM 90%, p<0.0001). More ICM consultants used specific haemoglobin transfusion triggers (48% EM, 77% ICM, p=0.0002), but marked variation in haemoglobin triggers and targets was reported. Lactate was rated the most important single resuscitation parameter by both specialties; no ED and only two ICM consultants rated ScVO2most important.

Conclusions

Differences in early fluid and vasopressor management of sepsis exist between Scottish ICM and EM consultants. Transfusion practice is highly variable, suggesting clinical uncertainty. Lactate is considered more important than ScVO2measurement.
The role of the community vet nurse
Authors: Boland Zara
Published: September 2013

The role of community vet nurses is well established in human health care, but less so in the veterinary field. This article brings together information from a number of charities, animal welfare organisations, the British Veterinary Nursing Association and private vet practices to gauge the breadth and depth of community veterinary nursing across the UK. Zara Boland describes the current role of community vet nurses, as well as their future potential and the rewards for practices that are willing to embrace the concept.
ON THE INDEX-CONJECTURE OF LENGTH FOUR MINIMAL ZERO-SUM SEQUENCES II
Authors: SHEN CAIXIA , XIA LI-MENG
Published: September 2013

Let G be a finite cyclic group. Every sequence S over G can be written in the form S = (n1g) ⋅ … ⋅ (nlg) where g ∈ G and n1, …, nl ∈ [1, ord (g)], and the index ind S of S is defined to be the minimum of (n1 + ⋯ + nl)/ ord (g) over all possible g ∈ G such that 〈g〉 = G. A conjecture says that if G is finite such that gcd (|G|,6) = 1, then ind (S) = 1 for every minimal zero-sum sequence S. In this paper, we prove that the conjecture holds if S is reduced and the (A1) condition is satisfied (see [On the index-conjecture of length four minimal zero-sum sequences, Int. J. Number Theory9(6) (2013) 1505–1528]).
Extended knowledge attributed Petri Nets
Authors: Fűr Attila
Published: September 2013

Choosing the best way for describing physical reality has always been standing in focus of research. Several methodologies have been developed based on classical mathematics, or statistics and also new disciplines — such as soft-computing techniques — appeared. Petri Nets as one of the most naturalistic modeling methodologies are well suited to describe complex process in general. However in some fields of modeling the describing power of basic Petri Nets proved not to be robust enough, therefore several extensions were made to the original concept. Colored tokens (Colored Petri Nets), stochastic delayed streaming of mobile entities (Stochastic Petri Nets), object oriented architecture (Object Oriented Petri Nets), numerical (Numerical Petri Nets) and linguistic attributes (Fuzzy Petri Nets) broaden the range of capabilities. In some fields of problem solving, usage of static and mobile knowledge bases is needed: e.g., flexible manufacturing systems, or intelligent traffic simulation. These problems to be investigated involved new conceptual developments of Petri Nets and led to the introduction of Knowledge Attributed Petri Nets. At the same time distributed control in simulation appeared, intelligent agents supported the connection of mobile knowledge bases and static inference engines in an effective way. The mentioned extensions brought general support in model synthesis, but some unsolved questions remained related to the implementation of intelligent mobile entities. This paper highlights a new level of AI controlled simulation introducing the Extended Knowledge Attributed Petri Nets that offer the capability of easy implementation of mobile inference engines and knowledge base, providing general mobile AI in Petri Nets.
Shedding Light on the Sea: André Morel's Legacy to Optical Oceanography
Authors: Antoine David , Babin Marcel , Berthon Jean-François , Bricaud Annick , Gentili Bernard , Loisel Hubert , Maritorena Stéphane , Stramski Dariusz
Published: September 2013

André Morel (1933–2012) was a prominent pioneer of modern optical oceanography, enabling significant advances in this field. Through his forward thinking and research over more than 40 years, he made key contributions that this field needed to grow and to reach its current status. This article first summarizes his career and then successively covers different aspects of optical oceanography where he made significant contributions, from fundamental work on optical properties of water and particles to global oceanographic applications using satellite ocean color observations. At the end, we share our views on André's legacy to our research field and scientific community.
Estimating the Number of Species in Microbial Diversity Studies
Authors: Bunge John , Willis Amy , Walsh Fiona
Published: September 2013

For decades, statisticians have studied the species problem: how to estimate the total number of species, observed plus unobserved, in a population. This problem dates at least as far back as 1943, to a paper by R.A. Fisher. These methods have found many applications in general ecology, but their importance has grown considerably in recent years, driven by the introduction of high-throughput DNA sequencing into microbial ecology. We examine the state of the art in terms of estimating the total number of taxa in a microbial population from a sample of sequences. We focus mainly on estimating the number of species within a single population (α-diversity), but we also briefly consider statistical inference for comparing the numbers of species across populations (β-diversity). We discuss the full range of statistical techniques, parametric and nonparametric as well as frequentist and Bayesian, and specific implications of their use in microbial diversity studies. We conclude with some recommendations for theoretical investigation and computational tool development.
The lateral mesopontine tegmentum regulates both tonic and phasic activity of VTA dopamine neurons
Authors: Chen Li , Lodge Daniel J.
Published: September 2013

Anatomic studies have demonstrated that the mesolimbic dopamine system receives a substantial afferent input from a variety of regions ranging from the prefrontal cortex through to the brain stem. However, how these afferents regulate dopamine neuron activity is still largely unknown. The mesopontine tegmentum provides a significant input to ventral tegmental area (VTA) dopamine neurons, and it has been demonstrated that discrete subdivisions within this region differentially alter dopamine neuron activity. Thus the laterodorsal tegmental nucleus provides a tonic input essential for maintaining burst firing of dopamine neurons, whereas the pedunculopontine tegmental (PPTg) nucleus regulates a transition from single-spike firing to burst firing. In contrast, the recently identified rostromedial tegmental nucleus provides an inhibitory input to the VTA and decreases spontaneous dopamine neuron activity. Here, we demonstrate that an area adjacent to the PPTg regulates both population activity as well as burst firing of VTA dopamine neurons. Specifically, N-methyl-d-aspartic acid (NMDA) activation of the lateral mesopontine tegmentum produces an increase in the number of spontaneously active dopamine neurons and an increase in the average percentage of burst firing of dopamine neurons. This increase in neuronal activity was correlated with extracellular dopamine efflux in the nucleus accumbens, as measured by in vivo microdialysis. Taken together, we provide further evidence that the mesopontine tegmentum regulates discrete dopamine neuron activity states that are relevant for the understanding of dopamine system function in both normal and disease states.
Association ofIL-4-590C>TandIL-13-1112C>TGene Polymorphisms with the Susceptibility to Type 2 Diabetes Mellitus
Authors: Alsaid Afaf , El-Missiry Mohammed , Hatata El-Sayed , Tarabay Mohammad , Settin Ahmad
Published: September 2013

Background.The goal of the study is to investigate the association ofIL-4-590 andIL-13-1112 genetic polymorphisms with type 2 diabetes mellitus (T2DM) in Egyptian patients.Subjects and Methods.The study included 135 cases with T2DM and 75 healthy unrelated age-matched controls from the same locality of Egypt. DNA was extracted and processed by the ARMS-PCR technique for characterization of genetic variants ofIL-4-590C>TandIL-13-1112C>Tpolymorphisms.Results.Egyptian cases with T2DM showed a lower frequency of theIL-4-590CChomozygous genotype compared to controls (10.4% versus 43.48%) with a higherCTheterozygous genotype (85.2% versus 47.8%). Similarly, cases showed a lower frequency of theIL-13-1112CCgenotype (20.7% versus 56.8%) with a higher frequency of the heterozygousIL-13-1112CTgenotype (76.3% versus 41.3%). Both polymorphisms showed significantly positive associations with T2DM in the dominant, codominant, and overdominant models of inheritance. On the other hand, comparing genotypes of subgroups related to gender, positive family history, and positive consanguinity showed a nonsignificant difference ().Conclusion.Heterozygous genotypes (IL-4-590CTandIL-13-1112CT) could be considered as risk factors, while the homozygous wild types (-590CCand -1112CC) might be considered protective to T2DM.