bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐throughput microsatellite marker development in two sparid species and verification of their transferability in the family Sparidae
Authors: REID KERRY , HOAREAU THIERRY B. , BLOOMER PAULETTE
Published: April 2012

Recently, 454 sequencing has emerged as a popular method for isolating microsatellites owing to cost‐effectiveness and time saving. In this study, repeat‐enriched libraries from two southern African endemic sparids (Pachymetopon blochii and Lithognathus lithognathus) were 454 GS‐FLX sequenced. From these, 7370 sequences containing repeats (SCRs) were identified. A brief survey of 23 studies showed a significant difference between the number of SCRs when enrichment was performed first before 454 sequencing. We designed primers for 302 unique fragments containing more than five repeat units and suitable flanking regions. A fraction (<11%) of these loci were characterized with 18 polymorphic microsatellite loci (nine in each of the focal species) being described. Sanger sequencing of alleles confirmed that size variation was because of differences in the number of tandem repeats. However, a case of homoplasy and sequencing errors in the 454 sequencing were identified. These newly developed and four previously isolated loci were successfully used to identify polymorphic markers in nine other economically important species, representative of sparid diversity. The combination of newly developed markers with data from previous sparid cross‐species studies showed a significant negative correlation between genetic divergence to focal species and microsatellite transferability. The high level of transferability we described (48% amplification success and 32% polymorphism) suggests that the 302 microsatellite loci identified represent an excellent resource for future studies on sparids. Microsatellite marker development should commonly include tests of transferability to reduce costs and increase feasibility of population genetics studies in nonmodel organisms.
Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx® flex and comparison with a retrospective study of FS‐laser in situ keratomileusis
Authors: Vestergaard Anders , Ivarsen Anders , Asp Sven , Hjortdal Jesper Ø.
Published: April 2012

Purpose:  To present our initial clinical experience with ReLEx® flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher‐order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS‐LASIK).

Methods:  Prospective study of ReLEx compared with a retrospective study of FS‐LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS‐LASIK patients were retrospectively identified. Visual acuity, spherical equivalent (SE) and corneal tomography were measured before and 3 months after surgery.

Results:  Preoperative SE averaged −7.50 ± 1.16 D (ReLEx) and −7.32 ± 1.09 D (FS‐LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction, 41% of ReLEx and 61% of FS‐LASIK eyes had an uncorrected distance visual acuity of logMAR ≤ 0.10 at day 1 after surgery, increasing to, respectively, 88% and 69% at 3 months. Mean SE was −0.06 ± 0.35 D 3 months after ReLEx and −0.53 ± 0.60 D after FS‐LASIK. The proportion of eyes within ±1.00 D after 3 months was 100% (ReLEx) and 85% (FS‐LASIK). For a 6.0‐mm pupil, corneal spherical aberrations increased significantly less in ReLEx than FS‐LASIK eyes.

Conclusions:  ReLEx is an all‐in‐one femtosecond laser refractive procedure, and in this study, results were comparable to FS‐LASIK. Refractive predictability and corneal aberrations at 3 months seemed better than or equal to FS‐LASIK, whereas visual recovery after ReLEx was slower.
Thermochemical stability of low‐iron, manganese‐enriched olivine in astrophysical environments
Authors: EBEL Denton S. , WEISBERG Michael K. , BECKETT John R.
Published: April 2012

Abstract– Low‐iron, manganese‐enriched (LIME) olivine grains are found in cometary samples returned by the Stardust mission from comet 81P/Wild 2. Similar grains are found in primitive meteoritic clasts and unequilibrated meteorite matrix. LIME olivine is thermodynamically stable in a vapor of solar composition at high temperature at total pressures of a millibar to a microbar, but enrichment of solar composition vapor in a dust of chondritic composition causes the FeO/MnO ratio of olivine to increase. The compositions of LIME olivines in primitive materials indicate oxygen fugacities close to those of a very reducing vapor of solar composition. The compositional zoning of LIME olivines in amoeboid olivine aggregates is consistent with equilibration with nebular vapor in the stability field of olivine, without re‐equilibration at lower temperatures. A similar history is likely for LIME olivines found in comet samples and in interplanetary dust particles. LIME olivine is not likely to persist in nebular conditions in which silicate liquids are stable.
Study of solder bridging for the purpose of assembling three-dimensional structures
Authors: Rao M. , Lusth J. C. , Burkett S. L.
Published: April 2012

Recently, soldering has been used to assemble three-dimensional microscale structures. Solder is deposited on adjacent metallic faces of planar polyhedral patterns, bridging the small gaps between individual faces. When all but one face of a polyhedral pattern are freed from the substrate and solder is reheated to a liquid state (reflow), the free faces of the pattern fold upward, out of the plane, to form the desired polyhedron. The wetting of solder with regards to coverage of metallic faces has been described previously, but the lateral bridging between the metal faces remains relatively unexplored. The goal of this work is to characterize the parameters influencing the bridging and folding process for two different ways of dip soldering: face and edge soldering. Face soldering refers to the complete wetting of metal faces, whereas edge soldering refers to selectively applying solder on the edges of a face that come in contact with other faces when folded. Our work explores bridging yield for various gap spacings and face thicknesses for eight different polyhedral patterns. Experiments show that the thickness and gap spacing strongly influence successful bridging. Experiments also show that improved control over the bridging process increases the yield of folded structures. In particular, gap spacing is positively correlated to face thickness for successful folding. Moreover, face soldering results in higher yields than edge soldering for all patterns.
CT based computerized identification and analysis of human airways: A review
Authors: Pu Jiantao , Gu Suicheng , Liu Shusen , Zhu Shaocheng , Wilson David , Siegfried Jill M. , Gur David
Published: April 2012

As one of the most prevalent chronic disorders, airway disease is a major cause of morbidity and mortality worldwide. In order to understand its underlying mechanisms and to enable assessment of therapeutic efficacy of a variety of possible interventions, noninvasive investigation of the airways in a large number of subjects is of great research interest. Due to its high resolution in temporal and spatial domains, computed tomography (CT) has been widely used in clinical practices for studying the normal and abnormal manifestations of lung diseases, albeit there is a need to clearly demonstrate the benefits in light of the cost and radiation dose associated with CT examinations performed for the purpose of airway analysis. Whereas a single CT examination consists of a large number of images, manually identifying airway morphological characteristics and computing features to enable thorough investigations of airway and other lung diseases is very time‐consuming and susceptible to errors. Hence, automated and semiautomated computerized analysis of human airways is becoming an important research area in medical imaging. A number of computerized techniques have been developed to date for the analysis of lung airways. In this review, we present a summary of the primary methods developed for computerized analysis of human airways, including airway segmentation, airway labeling, and airway morphometry, as well as a number of computer‐aided clinical applications, such as virtual bronchoscopy. Both successes and underlying limitations of these approaches are discussed, while highlighting areas that may require additional work.
A comparison of digital radiography systems in terms of effective detective quantum efficiency
Authors: Bertolini Marco , Nitrosi Andrea , Rivetti Stefano , Lanconelli Nico , Pattacini Pierpaolo , Ginocchi Vladimiro , Iori Mauro
Published: April 2012

Purpose:

The purpose of this study is to compare digital radiography systems using the metric effective detective quantum efficiency (eDQE), which better reflects digital radiography imaging system performance under clinical operating conditions, in comparison with conventional metrics such as modulation transfer function (MTF), normalized noise power spectra (NNPS), and detective quantum efficiency (DQE).

Methods:

The eDQE was computed by the calculation of the MTF, the NNPS, the phantom attenuation and scatter, and estimation of x‐ray flux. The physical characterization of the systems was obtained with the standard beam conditions RQA5 and RQA9, using the PA Chest phantom proposed by AAPM Report # 31 simulating the attenuation and scatter characteristics of the adult human thorax. The MTF (eMTF) was measured by using an edge test placed at the frontal surface of the phantom, the NNPS (eNNPS) was calculated from images of the phantom acquired at three different exposure levels covering the operating range of the system (E0, which is the exposure at which a system is normally operated, 1/3 E0, and 3 E0), and scatter measurements were assessed by using a beam‐stop technique. The integral of DQE (IDQE) and eDQE (IeDQE) was calculated over the whole spatial frequency range.

Results:

The eMTF results demonstrate degradation due to magnification and the presence of scattered radiation. The eNNPS was influenced by the grid presence, and in some systems, it contained structured noise. At typical clinical exposure levels, the magnitude of eDQE(0) with respect to DQE(0) at RQA9 beam conditions was 13%, 17%, 16%, 36%, and 24%, respectively, for Carestream DRX‐1, Carestream DRX‐1C, Carestream Direct View CR975, Philips Digital Diagnost VM, and GE Revolution XR/d. These results were confirmed by the ratio of IeDQE and IDQE in the same conditions.

Conclusions:

The authors confirm the robustness and reproducibility of the eDQE method. As expected, the DR systems performed better than the CR systems due to their superior signal‐to‐noise transfer characteristics. The results of this study suggest the eDQE method may provide an opportunity to more accurately assess the clinical performance of digital radiographic imaging systems by accounting for factors such as the presence of scatter, use of an antiscatter grid, and magnification and focal spot blurring effects, which are not reflected in conventional DQE measures.
Native dialect influences second-language vowel perception: Peruvian versus Iberian Spanish learners of Dutch
Authors: Escudero Paola , Williams Daniel
Published: April 2012

Peruvian Spanish (PS) and Iberian Spanish (IS) learners were tested on their ability to categorically discriminate and identify Dutch vowels. It was predicted that the acoustic differences between the vowel productions of the two dialects, which compare differently to Dutch vowels, would manifest in differential L2 perception for listeners of these two dialects. The results show that although PS learners had higher general L2 proficiency, IS learners were more accurate at discriminating all five contrasts and at identifying six of the L2 Dutch vowels. These findings confirm that acoustic differences in native vowel production lead to differential L2 vowel perception.
Language learning and the developing brain: Cross-cultural studies unravel the effects of biology and culture
Authors: Kuhl Patricia K.
Published: April 2012

Cross-cultural studies show that infants are born with innate abilities that make them “citizens of the world.” By the end of the first year of life, however, culture produces a dramatic transition. Infants' abilities to discern differences in native-language sounds increase, and their abilities to discriminate sounds from other languages decreases. This perceptual narrowing of infants' language skills is caused by two interacting factors: the child's computational skills and their social brains. Computational skills allow rapid and automatic “statistical learning” and social interaction is necessary for this computational learning process to occur. This combination produces the neuroplasticity of the child's mind, and contrasts with the more expert (but less open) mind of the adult. Neuroimaging of infants using Magnetoencephalography (MEG) is helping explain the extraordinary learning of young children. The work is leading to a new theoretical account for the “critical period” for language. Understanding the interaction between biology and culture in human learning in the domain of language may unlock some of the mysteries and mechanisms of the human mind.
Sonofragmentation and sonocrystallization
Authors: Suslick Kenneth S. , Zeiger Brad W.
Published: April 2012

Developing processes for the production of active pharmaceutical ingredients (APIs) with a specific crystal size or polymorph distribution is critical for improved drug delivery by aerosolization, injection or ingestion, for control of bioavailability, and for economy of preparation. The use of ultrasound for the crystallization of APIs has attracted substantial recent attention due to (1) its influence on particle size and size distribution, (2) reduction of metastable zone-width, induction time, and supersaturation levels required for nucleation, (3) improved reproducibility of crystallization, (4) control of polymorphism, and (5) reduction or elimination of the need for seed crystals or other foreign materials. Possible mechanisms for the breakage of molecular crystals under high-intensity ultrasound were investigated using acetylsalicylic acid (aspirin) crystals as a model compound for active pharmaceutical ingredients. Surprisingly, kinetics experiments ruled out particle-particle collisions as a viable mechanism for sonofragmentation. Two other possiblemechanisms (particle-horn and particle- wall collisions) were dismissed on the basis of decoupling experiments. Direct particle-shockwave interactions are therefore indicated as the primary mechanism of sonofragmentation of molecular crystals.
Concert hall acoustics
Authors: Beranek Leo L
Published: April 2012

Three of the world's famous concert halls, Boston's Symphony Hall, Vienna's Grosser Musikvereinssaal and Amsterdam's Concertgebouw, were built before 1901, are rectangular in shape, and are known to have good acoustics. Then came the overriding postulate of Architect Hans Sharoun, “Music in the Center”, which resulted in the Philharmonie Hall in Berlin, built in 1963. This type of hall, now called Surround Shape because the audience sits on all sides of the stage, has since been adopted elsewhere. For very large audiences, a fan-shaped hall, the Koussevitzky Tanglewood Music Shed seating 5000, was erected in 1940, underwent major acoustical changes in 1959, and has become the model for summer venues. An entirely different design is the Town Hall in Christchurch, New Zealand (opened in 1972), sometimes called the “Lateral-directed reflection sequence (LDRS) type,” which emphases lateral reflections that arrive early after the direct sound and that result in reduced energy in the reverberant sound. These types are discussed along with pertinent physical data. In addition to the effects of acoustics on the orchestral sound, factors in selecting a shape are the number of seats, the distance of the farthest seats from the stage, and who are likely to purchase tickets.
Teaching acoustics in Mexico
Authors: Elizondo Garza Fernando J. , Beristain Sergio
Published: April 2012

Mexico has been too slow to create a so called “critical mass” of acousticians, goal still not reached. There are a number of reasons for this condition, such as: a very low government budget to develop science and technology (approximately 0.4 % of the Mexican GNP in 2011); a low cultural level which promote “self formation”; the perception of acoustics/audio as a field somehow considered as a luxury, well beyond food, dress and housing; a little interdisciplinary activity among professionals; the consideration by the education institutions of acoustics as a complimentary knowledge within some technical professions, instead as a field in its own value; the difficulty derived by the low number of specialists for the consolidation of postgraduate programs; and the frequent economical and political crisis that make almost impossible the long term planning among people and companies. In this lecture the education programs and the periodic events on acoustics in Mexico will be described. Short term perspectives are a little discouraging, but thanks to the personal activities of some distinguished acousticians through professional societies and specialized congresses, it is possible to gather researchers, disseminate the Mexican acoustics research activities, and promote the formal education on acoustics in Mexico.
The horizontal correlation of long range bottom reverberation in shallow water with inclined sea floor
Authors: Yang Shi-e , Gao Bo , Piao Sheng-chun
Published: April 2012

The performance of active sonar system is seriously influenced by bottom reverberation in shallow water waveguide. It is important to understand the horizontal correlation of bottom reverberation for active towed-array processing techniques in shallow sea. However, little work had been done for the research on horizontal correlation of distant bottom reverberation. In this paper, a coupled mode reverberation model was applied for the horizontal correlation, and it was investigated as a function of receiving position, time and frequency. Calculations show that transverse correlation is greater than the longitudinal correlation in horizontal space for distant bottom reverberation. The adiabatic mode solution is introduced to derive the mathematic mode for horizontal correlation in the range-dependent waveguide with varying depth and the numerical results indicate that the influence of inclined sea floor on the horizontal correlation should be considered.
Pulse Wave Imaging (PWI) of the human carotid artery: An in vivo feasibility study
Authors: Luo Jianwen , Li Ronny , Konofagou Elisa
Published: April 2012

Noninvasive measurement of the pulse wave velocity (PWV) is of high clinical importance. Pulse Wave Imaging (PWI) has been previously developed by our group to visualize the propagation of the pulse wave and to estimate the regional PWV. The objective of this study was to determine the feasibility of PWI in the human carotid artery in vivo. The left common carotid artery of 8 healthy human subjects (27 ± 4 y.o.) was scanned in a long-axis view. The beam density of the 10 MHz linear array was equal to 16 beams so as to increase the frame rate to 1127 Hz for an imaging depth of 25 mm and width of 38 mm. The RF signals were acquired to estimate the velocity of the arterial wall using a 1D cross-correlation technique. Sequential wall velocity frames depicted the propagation of the pulse wave in the carotid artery within the field of view. Regional PWV was estimated from the spatiotemporal variation of the wall velocities and ranged from 4.0 to 5.2 m/s, in agreement with findings in the literature. PWI was thus proven feasible in the human carotid artery.
Physics prospect of cochlear nonlinear signal processing
Authors: Long Chang-Cai , Tian Lin , Wang Fei
Published: April 2012

We demonstrate in a model that cochlea nonlinear signal processing characteristics, nonlinear tuning, nonlinear amplification, and two tone suppression, stem from a common physics base, nonlinear active force acting on basilar membrane, which decreases with vibration amplitude. This unveiled cochlear physics prospect provides theory for the exploring of active force physiological mechanism, the interpreting and the improving of impaired hearing.
Machinery vibration diagnostics using a statistical analysis on frequency bands of interests
Authors: Li Zhuang , Jin Lei
Published: April 2012

Machinery fault diagnostics is vital for safety and reliability of operation in order to avoid serious consequences such as production downtime and even human lives. As the vibration signals carry useful information to reflect the machinery conditions, many theoretical models have been established to describe the relationship between the vibration signals and the existence of damage. However, sophisticated data analyses are needed to provide insight to the machinery vibration. A statistical model was proposed by the authors based on that the vibration spectra at the Fourier frequencies are exponentially distributed. Such a statistical model is an effective screening technique for damage identification and health monitoring in rotating machinery. While the previous statistical model was based on the full frequency-range spectra, in this research the model has been modified to focus on frequency bands of interests only. Such modifications improve the performance of the fault detection using the statistical model. Experimental vibration data were collected to validate the statistical model.
Paraseismic vibrations—disadvantages and advantages in application in a new system for spatial orientation of blind people
Authors: Wiciak Jerzy
Published: April 2012

Since 2009 the project System For Determination Of Hazardous Areas For The Blind People Using Wave-Vibration Markers has been in constant development. Its first stage was the public opinion survey. The aim of the survey was to analyze and evaluate problems associated with movement of the blind and partially sighted people through an urban environment. This article presents results of research on possible application of paraseismic vibrations and problems with paraseismic vibrations in the system for spatial orientation of blind and partially-sighted people which is built. Particular attention was paid to methodology of signal acquisition of paraseismic vibrations for the purpose of education of spatial orientation of people with vision dysfunction. Finally the frequency bands of vibrations generated by means of traffic and transport in various places and situations in the city are defined. These frequencies allow better designing of the system that support movement of blind people in urban conditions.
Voice onset time as a cue for perceiving place of articulation in stop consonants
Authors: Shuai Lan , Gong Tao
Published: April 2012

It is well-established that the formant transitions are the cues to differentiate the perceived place of articulation (POA) of a stop consonant, regardless of voice onset time (VOT). However, as shown in the acoustic analysis of utterances, it is also documented that stop consonants with different POAs have distinguished VOTs, in English and other languages. Moreover, various models have been proposed to explain the covariation between POA and VOT. Given that there is a correlation between these two, it is possible that VOT also serves as a cue for perceiving POA in addition to formant transitions, and that POA affects the judgment of VOT in addition to temporal cues. Previous research addressed the role of POA in distinguishing voicing contrasts, but the effect of VOT on perceiving POA has not been reported in previous literature. By varying the VOTs of bilabial, alveolar, and velar stops, the current study shows that VOT is also an important cue in distinguishing POA. The results are not consistent with a one-to-one mapping between specific phonetic cues and articulatory gestures, but support a statistical learning of multiple phonetic features in phonemes.
Statistical analysis on the possibility of distinguishing Chinese homonyms by the contrast of their tones
Authors: Liu Song , Sun Qi , Sunaoka Kazuko , Hiki Shizuo
Published: April 2012

The present authors have been analyzing statistically the nature of the Chinese tones (Hiki et al., Proc. Int'l Symposium on Tonal Aspects of Languages, 2004, Beijing, 73-74). The letter database used is the Grammatical Knowledge-base of Contemporary Chinese, S-W. Yu, editor, Tsinghua University Press, China, 1998. In this report, the use of contrast of tones for distinguishing words within a group of homonyms is assessed, from the viewpoint of the amount of information transmitted. Among the bisyllabic words having different simplified Chinese character notation, more than 10% of the words belongs to the homonymous groups having the same Pinyin notation. However, the number of words having the same Pinyin notation and combination of tones is not so many, that about 80% of them can be distinguished by the contrast of their tones. Detailed analysis showed some characteristic distribution regarding the type of tones in the contrast, depending on whether the number of words in a homonymous group is two or more, or whether the position of syllable of the contrastive tones in bisyllabic words is first, second or both. This result is useful for guiding the beginners' Chinese tone learning.
Vector sound intensity measurements with a tetrahedral arrangement of microphones in a spherical probe
Authors: Søndergaard Thomas
Published: April 2012

The three dimensional sound intensity vector may be measured using a number of microphone configurations, an example of which is an orthogonal arrangement of three matched pairs of microphones. This setup is prone to unwanted reflections, however, and uses more microphones than theoretically required. Results are therefore presented on the calculation of the sound intensity vector using atetrahedral arrangement of microphones housed within a solid sphere. The acoustic presence of the sphere is quantified; specifically, frequency dependent phase and pressure measurements due to diffraction are obtained for various incidence angles and compared with theoretical values. The proposed intensity probe is further evaluated against traditional arrangements for the calculation of the acoustic intensity vector and advantages of adopting the spherically mounted, tetrahedral arrangement are highlighted.
Research on underwater acoustic moving target 3-D imaging using spatial scattering model
Authors: Liu Dezhu , Feng Jie , Li Zhaoli , Zeng Feng
Published: April 2012

A spatial scattering model was proposed to analyze underwater acoustic moving target signals received by 3-D imaging sonar, and moving target signals for 3-D imaging sonar was also simulated. Analysis showed the validity of the spatial scattering model. Based on the spatial scattering model and simulated signals, FFT beam forming method was applied and performance of 3-D imaging sonar was analyzed. Result showed that the 3-D imaging performance effected by underwater acoustic moving target's size, shape and distance etc, emphasized the influence of target moving especially. So the spatial scattering model is both a useful theoretical tool and a simulation method aiding further research and analysis of underwater acoustic moving target 3-D imaging.
High-resolution Sonar based on carrier-free narrow pulse: I. transmission characteristic
Authors: Ni Yunlu , Chen Hang
Published: April 2012

In comparison with a sinusoidal carrier in the conventional sonar system, currently realizable carrier-free millisecond or microsecond pulse for novel sonar system has advantages: attaining more target information, restraining fluctuation of reverberation envelop efficiently in short-range detection and achieving accurate estimation. Since the attenuation increases rapidly with frequency in variable ocean, waveform distortion of such narrow pulse with transient wide band has occurred and can not be negligible. In this paper the focus will be on the transmission characteristic of carrier-free narrow pulse in viscid ocean by Finite Element Method. Employing received pulse at certain distance in numerical modeling and physical measurement, a special filter as ocean modeling is exactly designed for carrier-free narrow pulse, which is convenience to collect the pulse wave at arbitrary distance for posterior proceeding.
The harmonic distortion level measurement system of the loudspeaker using two adaptive filters
Authors: Fujioka Toyota , Nagata Yoshifumi , Abe Masato
Published: April 2012

The harmonic distortion level is an important criterion to evaluate loudspeaker performance. The harmonic distortion level is generally obtained using the power spectrum of the audio signal from a loudspeaker, and a microphone is used to receive the audio signal. It is important to measure the accurate harmonic distortion level for evaluating performance of the loudspeaker. Generally, The harmonic distortion level is measured by the spectrum analysis. However, the spectrum analysis requires large computational complexity. Therefore, we proposed the new technique to measure the harmonic distortion level of the loudspeaker by using the adaptive filter. And we evaluated the performance of the proposed technique by experiment. The proposed technique can measure the accurate level the same as the spectrum analysis, but requires long measurement time to converge the filter coefficient. This paper presents a description of the new technique to measure the harmonic distortion of the loudspeaker by using two adaptive filters. The propose technique improves the accuracy and the measurement time of the proposed measurement technique by using the adaptive filter. We show some results of real-time experiments. The results of the real-time experiments verified that the newly proposed technique improves measurement time and accuracy of measured level.
Geoacoustic inversion using low and mid frequency bottom reflected signals in shallow water off the east coast of Korea
Authors: Choi Jee Woong , Lee Changil , Cho Sungho , Kang Donhyug , Park Joung-Soo
Published: April 2012

Two types of short-range propagation experiments were conducted in shallow water (nominal water depth of 150 m) off the east coast of Korea, using 6 to 10 kHz CW signals and low-frequency broadband bulb implosion as acoustic sources. The received signals were recorded on the vertical line arrays at ranges shorter than 500 m. A marine geological observation conducted at the experimental site showed that there was a thin surficial sediment layer with thickness of less than 1 m overlaying the thicker and higher speed sediment layer and the basement was 15-20 m under the water-seabed interface. Bottom reflection loss as a function of grazing angle and frequency were estimated from the single bottom-interacting path of CW signals, which were used for the inversion of geoacoustic parameters for the surficial sediment structure. The geoacoustic inversion for parameters corresponding to the lower interface was performed using the bulb implosion data. The arrival time difference and the amplitude ratio between the single bottom-reflected and sub-bottom-reflected signals were used to estimate the sound speed and attenuation coefficient, respectively, within the second layer. [Supported by ADD (Agency for Defense Development, Korea), and KORDI (Korea Ocean Research and Development Institute)]
Estimation of speech privacy performance from acoustic parmeters in two adjacent rooms
Authors: Sato Hayato , Morimoto Masayuki , Hoshino Yasushi , Odagawa Yasuhiko
Published: April 2012

Sato et al. suggested the equal-intelligibility contours that enable us to predict sound insulation performance and background noise level required to achieve a certain level of speech privacy/security on the basis of the word intelligibility test [Sato et al., Appl. Acoust. 73, 43-49 (2012)]. However, temporal aspects of sound fields, which would affect intelligibility scores, were not considered in the intelligibility test. In the present study, intelligibility tests were performed to investigated the effects of temporal aspects of sound fields on the scores. The possibility of using reverberation time as one of the predictors of speech privacy performance will be discussed on the basis of intelligibility tests.
Perceptual compensation for effects of reverberation in isolated test-words
Authors: Watkins Anthony , Raimond Andrew
Published: April 2012

Reverberation from room reflections tends to degrade speech reception, as happens when listeners are required to identify test words from a “sir”-to-“stir” continuum. When the reverberation is substantial it introduces a “tail” from the [s], which tends to fill the gap that cues the [t]. A degradation effect arises as listeners report correspondingly fewer “stir” sounds. However, a recent report indicates that in certain conditions this degradation is entirely absent, despite substantial reverberation. These conditions are where test words are played in isolation, and where the reverberation is kept at the same level in the test-words of every trial that listeners hear. Conditions used here are generally similar to this except that the level of reverberation in test words is varied unpredictably from trial to trial, with the substantial-level trials intermingled with trials where the level of reverberation is much lower. Under these conditions the degradation effect is restored. This suggests a perceptual compensation from information within test words that can build up over sequences of trials, but only when the test word's reverberation stays the same from trial to trial. Other conditions confirm that reverberation information from the vowel part of isolated test-words affects identification of preceding consonants.
Effects of upper surface layers on the vibration characteristics of floating floor systems in concrete slab structures
Authors: Kim Jae Ho , Jeon Jin Yong
Published: April 2012

The effect of materials with supporting conditions on the vibration characteristics of the floating floor systems have been studied in concrete slab structures. Total 10 types of floor systems which have various sizes of panels and supporting beams with different joints were made based on actual conditions. In the measurement of vibration, ISO rubber ball was used as an impact source in order to reproduce human walking. The vibration characteristics were evaluated through calculating the vibration dose value (VDV) and autocorrelation function (ACF) parameters for the vibrations of the floor surface layers. Finally, a human walking experiment was conducted to investigate the subjective responses to the effect of vibration characteristics of the floating floors. As results, the correlation coefficients between physical parameters and subjective responses were derived and a perception model was obtained.
Experimental study of the sound transmission loss in normal incidence through autoclaved aerated concrete material
Authors: Olivier Delas
Published: April 2012

Sound transmission loss through autoclaved aerated concrete has been recently studied with the help of a computer model that uses the matrix transfer method and represents the material as a general poroelastic layer using Biot theory together with the Johnson-Champoux-Allard model for visco-thermal dissipations. It was found that when the autoclaved aerated concrete material is covered on both sides by plaster daubs, the computed sound transmission loss decreases by 4 dB in the low frequency range (50-400 Hz). One possible explanation of this phenomenon might be the material losing most of its porous characteristics when the pores located at its surface are obstructed. In this research work, the effect of the surface pore obstruction is experimentally studied by measuring the sound transmission loss of the light weight concrete in an impedance tube for different thicknesses and finishes of the material: plain, plaster daubed and painted. Sound transmission loss values are measured in an impedance tube by the 4-microphone method. This article presents the normal incidence sound transmission loss measured for the different configurations of the autoclaved aerated concrete material. The experimental results are compared with the corresponding computed values and conclusions on the effect surface pore obstruction on the sound transmission loss of the material are drawn. Recommendations are provided for the future design of high sound transmission loss wall systems integrating autoclaved aerated concrete materials.
Reflection and transmission properties of a wall-floor building element: comparison between finite element model and experimental data
Authors: Negreira Montero Juan , Bard Delphine
Published: April 2012

Changes in the Swedish construction code introduced in 1994 enabled the construction of wooden multi-storey buildings. The main issue in those is disturbing vibrations and noise propagating throughout the construction. Therefore, gaining knowledge about their behavior is of crucial importance for the industry. In this study, a mockup of a wall/floor junction was investigated by comparing both experimental and simulation (FEM) results. The mockup resembles a section of a real wooden building. It is 9.3 m long and 3.6 m wide. The structure was built using wooden beams as load-bearing components and chipboards as the floor surface. Likewise, a gypsum wall was placed in the middle surrounded by a wooden frame. The reflection and transmission properties of the structure were studied when subjected to harmonic excitations. The junction has been studied experimentally using dual-axis accelerometers attached to the T junction, post-processing the data using the scattering matrix formulation, which allows separating the transmitted and reflected wave as the wave propagates towards the junction, as well as the rate of wave conversion. Subsequently, a FE model of the structure was created allowing the comparation between both cases. This project was funded by Interreg IV, Silent Spaces.
Subharmonics in bubble oscillations: history, physics, applications
Authors: Prosperetti Andrea
Published: April 2012

The paper will start with a brief review of the history of subharmonic emssions from bubbles driven into oscillation by a sound afield. The peculiar nature of subharmonic oscillations as opposed to other manifestations of non-linearity will then be explained and the effects of damping will be illustrated. A few recent applications of subharmonic oscillations of bubbles will then be reviewed.
Modeling subharmonic response from contrast microbubbles for imaging and noninvasive pressure estimation
Authors: Sarkar Kausik , Katiyar Amit , Ketterling Jeffrey A. , Chitnis Parag V.
Published: April 2012

In order to characterize the behaviors of encapsulated contrast microbubbles, an approach will be described where progressively more sophisticated models have been developed guided by experimental observations. The development and characterization process includes independent estimation and validation components — attenuation is used to estimate the model material parameters, and then the estimated model is validated against independently measured subharmonic response. The subharmonic aided noninvasive pressure estimation that depends on experimentally observed decrease of subharmonic response of many commercial contrast agents with local hydrostatic pressure will also be critically examined. It will be shown that the basic bubble dynamics predicts either a decrease or an increase of subharmonic response with pressure increase depending on the excitation frequency and the bubble size. This finding indicates a lack of proper understanding of the underlying process. Finally, the minimum threshold excitation for subharmonic generation from an encapsulated microbubble will be revisited to show that in contrast to the classical perturbative result, it is not always obtained at twice the resonance frequency; instead it can occur over a range of frequency from resonance to twice the resonance frequency. The quantitative variation of the threshold with different models of encapsulation will be discussed. [support: NSF, NIH, DOD]
Optical and acoustical characterization of the subharmonic response of single UCA microbubbles
Authors: Versluis Michel
Published: April 2012

Coated microbubbles, unlike tissue, are able to scatter sound subharmonically. Therefore, the subharmonic behavior of coated microbubbles can be used to enhance the contrast in ultrasound contrast imaging. Theoretically, a threshold amplitude of the driving pressure can be calculated above which subharmonic oscillations of microbubbles are initiated. Interestingly, earlier experimental studies on coated microbubbles demonstrated that the threshold for these bubbles is much lower than predicted by the traditional linear viscoelastic shell models. Here we present an optical and acoustical study on the subharmonic response of individual microbubbles, e.g. the radial subharmonic response of the microbubbles was recorded with the Brandaris ultra high-speed camera as a function of both the amplitude and the frequency of the driving pulse. Threshold pressures for subharmonic generation as low as 5 kPa were found near a driving frequency equal to twice the resonance frequency of the bubble. An explanation for this low threshold pressure is provided by the shell buckling model proposed by Marmottant et al. It is shown that the change in the elasticity of the bubble shell as a function of bubble radius enhances the subharmonic behavior of the microbubbles.
A mechanistic investigation of subharmonic response from polymer-shelled microbubbles in response to high-frequency ultrasound
Authors: Ketterling Jeffrey A. , Chitnis Parag V. , Mamou Jonathan , Koppolu Sujeethraj
Published: April 2012

Polymer-shelled ultrasound contrast agents (UCAs) can undergo a “compression only” behavior leading to shell rupture and nonlinear response of the released gas bubbles when excited below 10 MHz. This study investigated if polymer-shelled UCAs exhibited a similar behavior when excited at frequencies above 10 MHz. Four varieties of polylactide-shelled UCAs, each with a distinct shell-thickness-to-radius ratio (STRR), were employed; the STRRs were 7.5, 40, 65, and 100 nm/μm. Two experiments were performed: one examined the compression-induced rupture of UCA shells by subjecting them to static overpressure, and the other investigated subharmonic components in the backscattered signal produced by individual UCAs sonicated with 20-MHz tone bursts. The four UCAs exhibited distinctly different compression-induced rupture thresholds that were linearly related to their STRR, but were uncorrelated with UCA size. The subharmonic response of the UCAs increased with increasing STRR. Thus, the UCAs with larger STRRs were more resilient to rupture, but they produced significantly greater subharmonic activity. The results of this two-part study indicated that the polymer-shelled UCAs may not adhere to the rupture-based mechanism of subharmonic generation when excited at 20 MHz.
Dependence of the subharmonic signal from ultrasound contrast microbubbles on ambient pressure
Authors: Li Fei , Ling Tao , Liu Chengrui , Jin Qiaofeng , Cai Feiyan , Li Deyu , Zheng Hairong
Published: April 2012

Ultrasound contrast agents (UCA) micro-bubbles have been well recognized as a potential noninvasive tool for blood pressure estimation. However, previous UCA indices, e.g., the shift of the resonance frequency, echo amplitude and the disappearance time, suffered from problems of low resolution, nonlinearity in the relationship with blood pressure, and only variations of the local pressure but the absolute values etc. In this paper, the effect of ambient pressure on UCA sub-harmonic optimal driving frequency (SODF) was investigated, at which the sub-harmonic scattering signals were the maximum. By applying transmit frequencies between 3MHz and 8MHz and the acoustic pressure of 300kPa, the acoustic attenuation and scattering of micro-bubbles were measured at overpressures of 4mmHg, 50mmHg and 100mmHg, comparable with the healthy human blood pressure. For groups of micro-bubbles with 80% in the diameter range of 1-2 micrometers, the shift of the SODF (SSODF) was 0.6MHz between over-pressures of 4mmHg and 100mmHg, which was approximately twice of the corresponding shift of the resonance frequency, thus had an improved sensitivity of pressure estimation. The SSODF of UCA micro-bubbles may be as a novel and sensitive index of the local blood pressure estimation.
Gauge invariance approach, a unified theory of negative refraction and cloaking
Authors: Gan Woon Siong
Published: April 2012

This is an alternative theory of negative refraction. Gauge invariance approach is used. With the discovery that negative refraction is a special case of coordinates transformation when the determinant of the transformation matrix equals -1, this is also a unified theory of negative refraction and cloaking.This is a more formal theory than Veselago's dispersion relation and a more generic theory with wider scope of applications. This is the third important application of gauge invariance to acoustic fields. The other two are invariance/symmetry gives rise to only two elastic constants in isotropic solid and time reversal invariance of acoustic equation of motion gives rise to new field of time reversal acoustics. Reflection invariance or right-left symmetry a form of gauge invariance also gives rise to negative refraction which is a reflection of positive refraction. With -1 as the determinant of the transformation matrix also produces naturally the negative values of permeability and permittivity for the em wave and negative values of mass density and bulk modulus for the acoustic wave. Reflection invariance produces negative refractive index, avoiding the uncertainty of choosing the negative sign of the square root when using the dispersion relation.
Acoustic band gaps in one-dimensional Helmholtz resonator metamaterials with disperiodical defects
Authors: Gao Dongbao , Zeng Xinwu
Published: April 2012

The metamaterials containing Helmholtz resonators (HR) can exhibit two kinds of forbidden gaps. The dynamic density and effective bulk modulus are simultaneously negative in the gap of local-resonant-type. It is considered to be one of the possible materials to implement a lot of applications based on transformation acoustics. Acoustic transmission properties of one-dimensional metamaterials with periodically and disperiodically distributed HRs are calculated based on acoustic transmission line method (ATLM). The relationship between the transmission coefficient and HR parameters is analyzed. The band gaps of 1D HR metamaterials with periodical defects are also investigated. The Bragg-scattering-type gaps exist at the frequencies associated with the effective periodic constant. The defect modes are observed in the gaps of local-resonant-type. Furthermore, another metamterial with gradually changed HRs is also researched as a disperiodical type. This work enriched the studies of HR metamaterials, which can be helpful for realizing new filters and cloaks.