bluuebunny/crossref_metadata_2025 huggingface dataset:
Alanine aminotransferase and metabolic syndrome in adolescents: the Korean National Health and Nutrition Examination Survey Study
Authors: Park J‐H. , Kim S‐H. , Park S. , Park M. J.
Published: October 2013

What is already known about this subject

Adolescent NAFLD has increased in parallel with obesity.

Elevated serum ALT level is a surrogate marker for NALFD.

Increased ALT levels are closely related to NAFLD and metabolic syndrome.

What this study adds

Increased ALT within normal range are associated with an increased risk of metabolic syndrome.

All of the five components of metabolic syndrome were associated with high ALT within normal range.

By elevation of ALT, the prevalence of metabolic syndrome increased in obese adolescents and normal‐weight adolescents as well.

Background/Aims

The potential interactions between alanine aminotransferase (ALT) and components of metabolic syndrome (MetS) have not been fully investigated in healthy adolescents. This study investigated the impact of a mild ALT elevation on the risks of MetS in healthy Korean adolescents.

Methods

From the Korean National Health and Nutrition Examination Surveys 1998–2009, the data of 5026 adolescents aged 10–18 years (2604 boys and 2422 girls) were analysed. Individuals who had ALT levels equal or more than 40 IU L−1 were excluded.

Results

Subjects in the upper ALT tertile had higher mean values of body mass index (BMI), homeostasis model assessment‐insulin resistance and prevalence of MetS than subjects in the lower tertile. The risk of each five components of MetS was significantly higher than subjects in the lower tertile. Compared with the subjects in the lower ALT tertile, the prevalence of MetS was higher in the upper tertile among obese adolescents (44.6–50.7% vs. 31.2–40.0%) as well as normal‐weight adolescents (5.2–7.7% vs. 2.7–3.2%). Subjects in the upper ALT tertile were at a higher risk of MetS than those in the lower tertile (odds ratio [OR] = 1.95 for boys, OR = 2.00 for girls) after controlling for age and BMI.

Conclusions

A high serum ALT within normal range increased the risk of all the components of MetS. The prevalence of MetS increased with the elevation of obesity level, and it increased further with the elevation of ALT tertile. Thus, serum ALT levels in addition to BMI might be useful as a marker for early detection of MetS.
Full‐gestational exposure to nicotine and ethanol augments nicotine self‐administration by altering ventral tegmental dopaminergic function due to NMDA receptors in adolescent rats
Authors: Roguski Emily E. , Sharp Burt M. , Chen Hao , Matta Shannon G.
Published: October 2013

In adult rats, we have shown full‐gestational exposure to nicotine and ethanol (Nic + EtOH) augmented nicotine self‐administration (SA) (increased nicotine intake) compared to pair‐fed (PF) offspring. Therefore, we hypothesized that full‐gestational exposure to Nic + EtOH disrupts control of dopaminergic (DA) circuitry by ventral tegmental area (VTA) NMDA receptors, augmenting nicotine SA and DA release in nucleus accumbens (NAcc) of adolescents. Both NAcc DA and VTA glutamate release were hyper‐responsive to intra‐VTA NMDA in Nic + EtOH offspring versus PF (p = 0.03 and 0.02, respectively). Similarly, DA release was more responsive to i.v. nicotine in Nic + EtOH offspring (p = 0.02). Local DL‐2‐Amino‐5‐phosphonopentanoic acid sodium salt (AP5) (NMDA receptor antagonist) infusion into the VTA inhibited nicotine‐stimulated DA release in Nic + EtOH and PF offspring. Nicotine SA was augmented in adolescent Nic + EtOH versus PF offspring (p = 0.000001). Daily VTA microinjections of AP5 reduced nicotine SA by Nic + EtOH offspring, without affecting PF (p = 0.000032). Indeed, nicotine SA in Nic + EtOH offspring receiving AP5 was not different from PF offspring. Both VTA mRNA transcripts and NMDA receptor subunit proteins were not altered in Nic + EtOH offspring. In summary, adolescent offspring exposed to gestational Nic + EtOH show markedly increased vulnerability to become dependent on nicotine. This reflects the enhanced function of a subpopulation of VTA NMDA receptors that confer greater nicotine‐induced DA release in NAcc.

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We hypothesized that concurrent gestational exposure to nicotine and ethanol would disrupt the control of VTA dopaminergic circuitry by NMDA receptors. Resulting in the augmented nicotine self‐administration (SA) in adolescent offspring.
Strategic Patenting and Software Innovation
Authors: Noel Michael , Schankerman Mark
Published: October 2013

Strategic patenting is widely believed to raise the costs of innovating, especially in industries characterised by cumulative innovation. This paper studies the effects of strategic patenting on R&D, patenting and market value in the computer software industry. We focus on two key aspects: patent portfolio size, which affects bargaining power in patent disputes, and the fragmentation of patent rights (‘patent thickets’) which increases the transaction costs of enforcement. We develop a model that incorporates both effects, as well as knowledge spillovers. Using panel data for 121 firms covering the period 1980–99, we show that strategic patenting and spillovers affect innovation and market value of software firms, that there is a patent premium accounting for 20 per cent of the returns to R&D, and that software firms do not appear to be trapped in a prisoners' dilemma of ‘excessive patenting.’
Energy Harvesting Capability of Lipid‐Merocyanine Macromolecules: A New Design and Performance Model Development
Authors: Tayebi Lobat , Mozafari Masoud , El‐khouri Rita , Rouhani Parvaneh , Vashaee Daryoosh
Published: October 2013

Light induced cis/trans isomerization in the family of merocyanine (MC) dyes offers a recyclable proton pumping ability which can potentially be used in hybrid bio‐electronic devices. In this article, a hexadecyl MC dye is embedded in lipid molecules to make a macromolecular configuration of a lipid/hexadecyl MC membrane. Lipid molecules play a critical role in stabilizing the dye in a membrane structure for practical use in energy devices. In this study, we first examined the proton pumping characteristic of the lipid/hexadecyl MC membrane in a conventional photoelectrochemical cell. Next, a major modification in the cell was introduced by eliminating I2/I‐electrolyte which resulted in a two‐fold increase in the open circuit voltage compared with that of the conventional cell. In addition, the charging time in the new cell was reduced approximately four orders of magnitude. This research demonstrated that the newly designed lipid‐ MC cell can act as a promising bioelectronic device based on the green energy of photoinduced MC dye proton pumping.
Cyclobutane Pyrimidine Dimer Density as a Predictive Biomarker of the Biological Effects of Ultraviolet Radiation in Normal Human Fibroblast
Authors: Sproul Christopher D. , Mitchell David L. , Rao Shangbang , Ibrahim Joseph G. , Kaufmann William K. , Cordeiro‐Stone Marila
Published: October 2013

This study compared biological responses of normal human fibroblasts (NHF1) to three sources of ultraviolet radiation (UVR), emitting UVC wavelengths, UVB wavelengths, or a combination of UVA and UVB (solar simulator; emission spectrum, 94.3% UVA and 5.7% UVB). The endpoints measured were cytotoxicity, intra‐S checkpoint activation, inhibition of DNA replication and mutagenicity. Results show that the magnitude of each response to the indicated radiation sources was best predicted by the density of DNA cyclobutane pyrimidine dimers (CPD). The density of 6‐4 pyrimidine–pyrimidone photoproducts was highest in DNA from UVC‐irradiated cells (14% of CPD) as compared to those exposed to UVB (11%) or UVA–UVB (7%). The solar simulator source, under the experimental conditions described here, did not induce the formation of 8‐oxo‐7,8‐dihydroguanine in NHF1 above background levels. Taken together, these results suggest that CPD play a dominant role in DNA damage responses and highlight the importance of using endogenous biomarkers to compare and report biological effects induced by different sources of UVR.
Cytokine mRNA expression in bronchoalveolar lavage cells during Dictyocaulus viviparus infection in calves
Authors: Holmgren S. , Hagberg Gustavsson M. , Lundén A. , Wattrang E.
Published: October 2013

The purpose of this study was to monitor local cytokine responses to Dictyocaulus viviparus in calves during primary infection and re‐infection. Bronchoalveolar lavage fluid (BALF) was collected weekly from experimentally infected calves and interleukin‐2 (IL‐2), IL‐4, IL‐5, IL‐10 and IFN‐γ mRNA expression was quantified in BALF cells. The major finding was a prominent transient increase in IL‐4 mRNA expression, compared with that of uninfected calves, observed in BALF cells collected 2–3 weeks post‐primary D. viviparus infection. At 2 weeks post‐infection, macroscopic worms were also first observed in BALF. Calves re‐infected after 10 weeks were partially immune which was evident at slaughter 5 weeks post‐infection as a lower worm burden than in previously naïve calves infected at the same time. IL‐4 mRNA expression in BALF cells 2 weeks post‐re‐infection was increased compared with that of uninfected animals but not as high as that of primarily infected calves. BALF cell expression of the other cytokines tested for was not as clearly effected by the D. viviparus infection. It seems likely that the strong IL‐4 response observed during primary infection reflects an innate response to the worms that may initiate an ensuing Th2 response, which confers protective immunity.
Committee report: Publication guidelines and recommendations for studies using electroencephalography and magnetoencephalography
Authors: Keil Andreas , Debener Stefan , Gratton Gabriele , Junghöfer Markus , Kappenman Emily S. , Luck Steven J. , Luu Phan , Miller Gregory A. , Yee Cindy M.
Published: October 2013

Electromagnetic data collected using electroencephalography (EEG) and magnetoencephalography (MEG) are of central importance for psychophysiological research. The scope of concepts, methods, and instruments used by EEG/MEG researchers has dramatically increased and is expected to further increase in the future. Building on existing guideline publications, the goal of the present paper is to contribute to the effective documentation and communication of such advances by providing updated guidelines for conducting and reporting EEG/MEG studies. The guidelines also include a checklist of key information recommended for inclusion in research reports on EEG/MEG measures.
Shifts in Portfolio Preferences of International Investors: An Application to Sovereign Wealth Funds
Authors: Sá Filipa , Viani Francesca
Published: October 2013

We develop a dynamic general equilibrium model to analyze the macroeconomic effects of a shift in portfolio preferences of foreign investors. The model has two countries and two asset classes (equities and bonds). It is characterized by imperfect substitutability between assets and allows for endogenous adjustment in interest rates and asset prices. To illustrate the mechanics of the model, we calibrate it to analyze a transfer of reserves from central banks to sovereign wealth funds (SWFs). We look separately at two diversification paths: a shift away from dollar assets (path 1), and a shift away from US bonds to US equities (path 2). In path 1, the dollar depreciates and US net debt falls on impact and increases in the long run. In path 2, the dollar depreciates and US net debt increases in the long run.
Structural Change in the External Balances Response to Macroeconomic Policies: Perspective from a Two‐Sector New Open Economy Macroeconomic Model
Authors: Yamamoto Shugo
Published: October 2013

The response of the Japanese trade balance against expansionary macroeconomic policy shocks changed from positive to negative in the 1990s. With consideration of intratemporal (between tradable and nontradable goods) and intertemporal elasticity of substitutions, we investigate this cause using two‐sector new open economy macroeconomics (NOEM). Empirical methods, considering structural change, were applied and show that before the break, intratemporal elasticity of substitution dominates, but subsequently the relation inverted and intertemporal elasticity became predominant and hence, the theoretical response of trade balance changed. Finally, we verify this theoretical implication empirically by impulse response analysis of structural vector auto regression.
Volatility Spillovers and Contagion from Mature to Emerging Stock Markets
Authors: Beirne John , Caporale Guglielmo Maria , Schulze‐Ghattas Marianne , Spagnolo Nicola
Published: October 2013

This paper models volatility spillovers from mature to emerging stock markets, tests for changes in the transmission mechanism during turbulences in mature markets, and examines the implications for conditional correlations between mature and emerging market returns. Tri‐variate GARCH–BEKK models of returns in mature, regional emerging, and local emerging markets are estimated for 41 emerging market economies (EMEs). Wald tests suggest that mature market volatility affects conditional variances in many emerging markets. Moreover, spillover parameters change during turbulent episodes. In the majority of the sample EMEs, conditional correlations between local and mature markets increase during these episodes. While conditional variances in local markets rise as well, volatility in mature markets rises more, and this shift is the main factor behind the increase in conditional correlations. With few exceptions, conditional beta coefficients between mature and emerging markets tend to be unchanged or lower during turbulences.
Failure Analysis of α-MDEA Air-Cooled Heat Exchanger of CO2 Removal Unit Based on the Semiquantitative Risk-Based Inspection Method
Authors: Reza Lashgari Hamid , Hanaei Amir , Adeli A. R.
Published: October 2013

Risk-based inspection program (RBI) is a decision making techniques for providing refineries and petrochemical plants with an effective and appropriate inspection planning. The aim of the present study is to analyze failure behavior and risk ranking of α-MDEA fin/fan cooler of CO2 removal unit based on API 581 in order to find out the reason(s) of tubes failure. According to previous experience in similar plant, risk calculation results and conducted inspection activity by using RFT eddy current technique, CO2 corrosion damage mechanism was identified as a main reason of tubes failure. In next step, process key variable, prevention/mitigation methods and inspection planning programs were determined so as to minimize the similar failure behavior in the rest of the lean amine air-cooled heat exchangers of CO2 removal unit.
Measurements of the total scattering and absorption cross-sections of the human body
Authors: Conti Stephane G. , Roux Philippe , Demer David A. , de Rosny Julien
Published: October 2013

Presented here are the first absolute measurements of the total acoustic energy scattered and absorbed by humans. The total scattering and absorption cross-sections were obtained from long-duration acoustic reverberation, for individual humans walking randomly in a room. An extension of the technique is proposed to estimate the absorption cross-section for the human body. Within the audible range, the sound scattering spectra of the human body is similar to that of a hard ellipsoid with the same volume (dimensions proportional to the weight to the one-third power). Moreover, we show that increasing amounts of clothing have little effect on scattering while absorption is greatly increased.
Sound sources of the screech tone radiated from circular supersonic jet oscillating in the helical mode
Authors: Umeda Yoshikuni , Ishii Ryuji
Published: October 2013

The generation mechanism of the screech tone in the helical oscillation mode is investigated using a series of instantaneous photographs. From the analysis of the photographs, six evanescent sound sources are observed as prominent points along the jet axis. These sound sources move along circular orbits in the planes perpendicular to the jet axis and slightly downstream of the rear edges of each shock cell. The speed of the moving sound sources is supersonic and moving Mach cones generated behind the moving sound sources form the helical-shaped wave fronts of the screech tone. The existence of the moving Mach cones about the jet axis was confirmed by comparing Schlieren photographs and drawings of the envelopes of the moving Mach cones. [Work supported by The Mitsubishi Foundation.]
Psychoacoustic processing of test signals
Authors: Kadlec Frantisek
Published: October 2013

For the quantitative evaluation of electroacoustic system properties and for psychoacoustic testing it is possible to utilize harmonic signals with fixed frequency, sweeping signals, random signals or their combination. This contribution deals with the design of various test signals with emphasis on audible perception. During the digital generation of signals, some additional undesirable frequency components and noise are produced, which are dependent on signal amplitude and sampling frequency. A mathematical analysis describes the origin of this distortion. By proper selection of signal frequency and amplitude it is possible to minimize those undesirable components. An additional step is to minimize the audible perception of this signal distortion by the application of additional noise (dither). For signals intended for listening tests a dither with triangular or Gaussian probability density function was found to be most effective. Signals modified this way may be further improved by the application of noise shaping, which transposes those undesirable products into frequency regions where they are perceived less, according to psychoacoustic principles. The efficiency of individual processing steps was confirmed both by measurements and by listening tests. [Work supported by the Czech Science Foundation.]
The effect of compression and attention allocation on speech intelligibility
Authors: Choi Sangsook , Carrell Thomas
Published: October 2013

Research investigating the effects of amplitude compression on speech intelligibility for individuals with sensorineural hearing loss has demonstrated contradictory results [Souza and Turner (1999)]. Because percent-correct measures may not be the best indicator of compression effectiveness, a speech intelligibility and motor coordination task was developed to provide data that may more thoroughly explain the perception of compressed speech signals. In the present study, a pursuit rotor task [Dlhopolsky (2000)] was employed along with word identification task to measure the amount of attention required to perceive compressed and non-compressed words in noise. Monosyllabic words were mixed with speech-shaped noise at a fixed signal-to-noise ratio and compressed using a wide dynamic range compression scheme. Participants with normal hearing identified each word with or without a simultaneous pursuit-rotor task. Also, participants completed the pursuit-rotor task without simultaneous word presentation. It was expected that the performance on the additional motor task would reflect effect of the compression better than simple word-accuracy measures. Results were complex. For example, in some conditions an irrelevant task actually improved performance on a simultaneous listening task. This suggests there might be an optimal level of attention required for recognition of monosyllabic words.
A laser-based acoustic velocity sensor
Authors: Stepanishen Peter R. , Antonelli Lynn
Published: October 2013

A linear systems model is presented for a Laser Doppler Vibrometer (LDV), which is used to detect the acoustically induced normal surface velocity at an air-water interface. Previous acoustic test tank results for signal reception are interpreted using the model. Noise performance is addressed using the model for a commercially available LDV where thermal noise in the fluid is shown to be of lesser importance than the internal noise of the sensor. In addition to the internal sensor noise that can be viewed as an additive noise which is uncorrelated to the signal, it is also noted that sidebands of the signal spectrum can be generated for large displacements of the air-water interface. For the case of harmonic signals the spectral distortion increases as kY increases where k is the acoustic wavenumber and Y is the amplitude of the surface displacement. Results from a series of experiments in-air and in-water using a piezo-ceramic disk with a variable voltage excitation are discussed in light of the model. The in-air experiments use the vibrating face of the disk as the reflecting surface whereas the in-water experiments use the air/water interface in a wave tube excited by the disk.
Learning to perceive Mandarin tones: The role of acoustic information
Authors: So Connie K.
Published: October 2013

Studies show that auditory-training improves non-native listeners’ tonal identification; however, persistently perceptual confusion of several tone pairs is still observed. This may imply that learners have not yet mastered/acquired the lexical tones. Their confusion may be reduced further if the essential acoustic information of tones (e.g., duration and pitch contour) could be implemented and emphasized during training. To verify the assumption, the present study examines the impact of employing acoustic information of lexical tones as feedback on non-native listeners’ performance during a computer-based perception training of Mandarin tones. Non-native speakers of Mandarin were randomly assigned to one of two groups. Listeners in the control group were merely shown that the answer was right or wrong. In contrast, those in the experimental group received acoustic information by means of both visual and auditory feedback when the response was incorrect (i.e., showing pitch graphs and presenting the audio files for the contrastive tonal pairs). Results indicated a significant improvement in the tonal identifications for listeners who received detailed acoustic information during training. This suggests that training with acoustic information of lexical tones assists non-native listeners in distinguishing the tone pairs more effectively. [Work supported by SSHRC.]
Intonational phonology description of Porteno Spanish
Authors: Barjam John P.
Published: October 2013

In this study the intonational patterns of Porteno Spanish (PS) are described within an Autosegmental Metrical (AM) (Ladd, 1996) approach. Porteno Spanish is the Spanish spoken in Buenos Aires, Argentina, and because of the influence from Italian and other languages, it differs markedly from varieties of Spanish that have been previously described. Six monolingual PS speakers were recorded saying 99 sentences which include declaratives, interrogatives, imperatives, and focused declarative and interrogative sentences. A ToBI framework, based on the F0 contour, was developed for labeling the sentences intonation. Preliminary results suggest that each phrase contains a somewhat regular pattern: (1) the stressed syllables of content words carry one of five pre-nuclear pitch accents, (2) nuclear pitch accents are more restrictive and tend to vary depending on the sentence type, and (3) boundary tones, both intermediate and intonational, are regular but also vary depending on sentence type.
Advancements in text-to-speech technology and implications for AAC applications
Authors: Syrdal Ann K.
Published: October 2013

Intelligibility was the initial focus in text-to-speech (TTS) research, since it is clearly a necessary condition for the application of the technology. Sufficiently high intelligibility (approximating human speech) has been achieved in the last decade by the better formant-based and concatenative TTS systems. This led to commercially available TTS systems for highly motivated users, particularly the blind and vocally impaired. Some unnatural qualities of TTS were exploited by these users, such as very fast speaking rates and altered pitch ranges for flagging relevant information. Recently, the focus in TTS research has turned to improving naturalness, so that synthetic speech sounds more human and less robotic. Unit selection approaches to concatenative synthesis have dramatically improved TTS quality, although at the cost of larger and more complex systems. This advancement in naturalness has made TTS technology more acceptable to the general public. The vocally impaired appreciate a more natural voice with which to represent themselves when communicating with others. Unit selection TTS does not achieve such high speaking rates as the earlier TTS systems, however, which is a disadvantage to some AAC device users. An important new research emphasis is to improve and increase the range of emotional expressiveness of TTS.
Assessment of variation between and within speakers
Authors: Bahr Ruth Huntley
Published: October 2013

While few individuals would argue that vocal cues can signal a person’s identity, it is difficult to specify exactly which parameter(s) provide the most salient information for speaker identification. Previous literature has suggested that speaking fundamental frequency, long-term spectra, vowel formant frequencies, and speech tempo can provide speaker-specific information. However, investigations focused on automatic speaker identification have provided less than satisfactory results. These findings could be related to how each acoustic parameter is measured or, more probably, to the idea that these acoustic parameters interact in specific ways that may be more obvious in the perceptual realm and may vary across speaking situations. To further complicate matters, individuals may speak more than one language or use multiple dialects. Little is known about the effect of code switching on voice production and identification. The purpose of this presentation is to present some of the relevant literature on voice recognition and factors related to misidentification. The role of intraspeaker variability will be discussed with a special emphasis on bilingualism and bidialectalism. Implications for voice production in augmentative and alternative communication devices will be described.
The noise spectral parameters and the energy of breaking waves experimental study
Authors: Tegowski Jaroslaw
Published: October 2013

The process of wave breaking and whitecap creation is one of the most important and least understood phenomena associated with the evolution of the surface gravity waves in the open sea. This process is the main way of energy and momentum transfer between ocean and atmosphere. However, it is very difficult to estimate, under real sea conditions, the frequency of breaking wave events or the fraction of sea surface covered by whitecaps and the amount of dissipated energy produced by wave breaking. A controlled experiment was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway). The simulation of random waves of the prescribed spectra provided a very realistic pattern of the sea surface. The number of breaking waves was estimated using photography method and wave staff recording. Acoustic measurements during the experiments were conducted in order to examine the relationship between the noise spectral parameters and both the whitecap coverage and dissipation energy of breaking waves for different types of waves. A comparison of simultaneous video observations, wave staff records of the surface wave above the hydrophones, with the spectral parameters of acoustical signals made it possible to find physical links between processes.
Propagation and scattering in bubbly liquids near resonance: A review of recent laboratory measurements
Authors: Wilson Preston S. , Park Eun-Joo , Carey William M. , Roy Ronald A.
Published: October 2013

Acoustic waves propagating through bubbly liquid experience dispersion and attenuation when the excitation frequency is near the resonance frequency region of the bubble distribution. Due to high attenuation in this regime, traditional standing wave and time-of-flight measurement techniques fail and existing theories remain unverified above void fractions of about 10−4. An impedance tube technique was developed in order to investigate this regime by inferring phase speed and attenuation within a bubbly layer from its complex reflection coefficient. Results of experiments using this technique, as well as its limitations, will be reviewed. We found that existing theory described the measured results near the resonance region within the uncertainty of the measured parameters of the bubble population. In a second class of experiments, scattering from laboratory bubble clouds was investigated. Here, the bubbles were much smaller than resonance size and the bubbly liquid was treated as an effective medium, with density given by a mixture law and sound speed given by Wood’s equation. Experimental results and the predictions of an effective fluid scattering model will be reviewed for spherical and cylindrical bubbly-liquid targets. [Work supported by U.S. Navy ONR.]
An experiment on near-shore sonar performance
Authors: Le Dantec Nicolas , Deane Grant B.
Published: October 2013

In order to further investigate the use of sonar systems in the near-shore environment, a simple, short range sonar system has been deployed along with additional devices to characterize the environmental conditions. The goal of the experiment is to determine the effects of volume and boundary conditions on the performance limits of sonar in the near-shore. A 10 kHz source transmitted a series of acoustic pulses with Barker code phase modulation along a 40 m propagation path to spherical targets just outside the surf zone north of Scripps Pier. Both forward and backscatter acoustic signals were recorded. A pressure array mounted on the seafloor measured the shoaling surface waves along the transmission path and the seawater conductivity, temperature and horizontal velocity was measured mid-way between the source and targets. Meteorological data were also collected. The effects of surface gravity waves focusing and multi-path arrivals on target discrimination will be addressed, along with scattering from artificially created bubble clouds. [Work supported by ONR.]
Bubble acoustics near surfaces
Authors: Dacol Dalcio K. , Orris Gregory J.
Published: October 2013

Boundary effects were included in Foldy’s effective medium theory of acoustic propagation in a bubbly fluid. This allowed for the discussion of bubble effects on propagation near interfaces and in waveguides such as the ones encountered in ocean acoustics. The implications of this model were examined in a variety of situations from laboratory experiments to acoustic propagation in shallow waters.
Forensic acoustics: An overview of the process
Authors: Weissenburger J. T.
Published: October 2013

There is a potential role for the acoustical expert in litigation. The technical issues may involve aeroacoustics, underwater acoustics, physical effects of sound, environmental acoustics, noise, architectural acoustics, physiological acoustics, speech and hearing, music, psychoacoustics and/or bioacoustics. This brief paper offers an overview of the process of being an expert, the qualifications to be an expert and what is expected of an expert. The six general phases of an expert’s involvement—retention, investigation, discovery, deposition, preparation, trial—are addressed. Some antidotal experiences are presented.
Resonances due to near-bottom soliton packets
Authors: Chin-Bing Stanley A. , Warn-Varnas Alex C. , King David B. , Lamb Kevin G. , Hawkins James A. , Lynch James F.
Published: October 2013

At the Acoustical Society of Americas Nashville meeting, 28 April–2 May 2003, we presented oceanographic modeling and acoustic modeling of the ONR winter 1997 Primer4 experiment conducted on the shelfbreak and continental slope south of Cape Cod in the Middle Atlantic Bight. Near-bottom solitary internal wave simulations in this region were generated using a forcing tidal velocity of 0.3 m/s to initiate the primitive equation Lamb model. The simulated internal waves were benchmarked against oceanographic data taken by Lynch. Similar to the acoustic mode coupling mechanism seen in the near-surface solitary wave packets, these near-bottom solitary internal waves also exhibited acoustic mode coupling—in this case the coupling transferred the acoustic energy from the trapped normal modes to the lossy continuous modes. This resulted in a loss in signal intensity, but no accompanying resonances were observed. As an update to that work we will show cases where the resonances are present, and are due to the conversion of the acoustic energy from the trapped normal modes to the lossy continuous modes. [Work supported by ONR/NRL.]
Sector array transducers for vibro-acoustography
Authors: Silva Glauber , Chen Shigao , Kinnick Randall , Greenleaf James , Fatemi Mostafa
Published: October 2013

Vibro-acoustography is an imaging technique that maps the acoustic response of an object to a localized harmonic radiation force. This force is generated by two interfering continuous-wave ultrasound beams at slightly different frequencies f1 and f2. The system point-spread function (PSF) is related to the radiation force on a point-target. Imaging artifacts depend on the PSF sidelobes, which can be reduced by mismatching the sidelobes of each ultrasound beam. Here, we propose a beamforming approach based on an 8-element sector transducer with consecutive elements alternately driven at f1 and f2. The transducer generates two ultrasound beams skewed by 22.5° with respect to each other. The system PSF is analytically derived. The theory is validated by experiments using a small steel sphere (radius =0.2 mm) as a point-target. A laser vibrometer is used to measure the vibration of the sphere and evaluate the PSF of the system. Theoretically, the PSF sidelobes are under −15.8 dB in eight spots circularly distributed and separated by 22.5°, which agrees with the experimental results. Simulation shows that with 16 elements sidelobes are under −35.2 dB. In conclusion, sector transducers for vibro-acoustography may have lower sidelobes as the number of array elements is increased. [Work supported by Grant Nos. EB00535-01, EB2640, and IMG0100744.]
Relationships between cortical bone properties and head wave ultrasonic velocity at 1 MHz: An in vitro investigation
Authors: Bossy Emmanuel , Talmant Maryline , Peyrin Françoise , Cloetens Peter , Akrout Leila , Laugier Pascal
Published: October 2013

The axial transmission technique provides a measurement of the velocity (SOS) of elastic waves propagating along the surface of cortical bone. Currently, SOS is derived from the time of flight of the first arriving signal. Our goal was to investigate the relationship between SOS and several bone properties that independently contribute to bone strength. One-MHz SOS measurements were performed with a proprietary probe on 41 excised human radius with soft tissue removed. Small pieces of cortical bone were removed from the site of ultrasonic testing to be investigated using synchrotron radiation microtomography (resolution 10 μm). Cortical thickness, cortical porosity, and tissue mineralization were derived from the 3-D data set. Mean SOS values were 3940 (3796–4120) ms−1. The reproducibility of the SOS measurements expressed as a variation coefficient (CV) was 0.5%. The relationships between SOS and bone properties were assessed using linear regression and displayed significant correlations : R2=0.20 (p<10−5) for cortical thickness, R2=0.30 (p<10−3) for cortical porosity, R2=0.37 (p<10−4) for tissue mineralization. A multiple regression analysis showed that cortical porosity and tissue mineralization in the periosteal region were the most predictive variables and explained 60% of the total variance of the SOS. These results are in agreement with predictions obtained using 3-D numerical computations based on a finite-difference method.
Ultrasonic axial transmission on cortical bone: A 3-D simulation study
Authors: Bossy Emmanuel , Talmant Maryline , Laugier Pascal
Published: October 2013

In vivo, cortical bone is currently investigated using ultrasonic velocity measurement in the megahertz frequency range. It is virtually impossible to analytically model the extremely complex field resulting from the interaction of an incident wave with cortical bone, taking into account 3-D geometry, boundary conditions, anisotropic and heterogeneous bone properties. Recently developed simulation methods based on finite difference offer a fertile alternative to inextricable analytic formulations. Wave propagation simulation is applied here to the problem of axial transmission along the radius. 3-D computations showed that different types of head wave propagate along the anisotropic cortex depending on the thickness-to-wavelength ratio. Simulated variations of SOS as a function of thickness are in good agreement with in vivo [Njeh (1999)] and in vivo [Prevrhal (2001)] observations. Cortical porosity leads to a velocity decrease of approximately 50 ms−1 (respectively 25 ms−1) per % of porosity increase in the axial (respectively, radial) direction. When the cortical thickness is larger than one compressional wavelength, the signal velocity reflects bone properties over a depth of about half a wavelength. Numerical simulation brings an insightful view into the influence of several bone properties on signal velocity, and can also be of great value in testing inverse calculation procedures.
Quantitative object localization and characterization from broadband ultrasonic backscatter
Authors: Ulker Karbeyaz Basak , Miller Eric L. , Cleveland Robin O. , Roy Ronald A.
Published: October 2013

The goal of many image applications in biomedical ultrasound is to ascertain the structure of regions in tissue which are, in a sense, anomalous relative to a background. To obtain quantitatively accurate reconstructions of the location, size, shape, and contrast (in sound speed, attenuation, or density) of the anomaly, one could invert for the acoustic properties on a finely sampled grid. However, this formulation is known to be ill-posed, especially when only limited view data, e.g., backscatter, are available. To avoid the difficulties associated with regularization schemes for overcoming ill-posedness, we introduce an inversion method in which we directly determine from the data the relevant geometric structure of the anomaly (center location, parameters governing shape and orientation) and a low order representation of the spatial structure of the possibly unknown background. By concentrating the information in the limited data to extract only these few unknowns, explicit regularization is not required. The details of this nonlinear inversion method will be provided and its performance and robustness will be demonstrated using both simulated broadband ultrasound backscatter data and monostatic backscatter measurements. [Work supported in part by CenSSIS (NSF Award No. EEC-9986821) and NSF Award No. 0208548.]
Acoustics, computers and measurements
Authors: Truchard James J.
Published: October 2013

The human ear has created a high standard for the requirements of acoustical measurements. The transient nature of most acoustical signals has limited the success of traditional volt meters. Professor Hixson’s pioneering work in electroacoustical measurements at ARL and The University of Texas helped set the stage for modern computer-based measurements. The tremendous performance of modern PCs and extensive libraries of signal processing functions in virtual instrumentation application software has revolutionized the way acoustical measurements are made. Today’s analog to digital converters have up to 24 bits of resolution with a dynamic range of over 120 dB and a single PC processor can process 112 channels of FFTs at 4 kHz in real time. Wavelet technology further extends the capabilities for analyzing transients. The tools available for measurements in speech, electroacoustics, noise, and vibration represent some of the most advanced measurement tools available. During the last 50 years, Professor Hixson has helped drive this revolution from simple oscilloscope measurements to the modern high performance computer-based measurements.
Modeling the dynamics of piano keys
Authors: Brenon Celine , Boutillon Xavier
Published: October 2013

The models of piano keys available in the literature are crude: two degrees of freedom and a very few dynamical or geometrical parameters. Experiments on different piano mechanisms (upright, grand, one type of numerical keyboard) exhibit strong differences in the two successive phases of the key motion which are controlled by the finger. Understanding the controllability of the escapement velocity (typically a few percents for professional pianists), the differences between upright and grand pianos, the rationale for the numerous independent adjustments by technicians, and the feel by the pianist require sophisticated modeling. In addition to the inertia of the six independently moving parts of a grand piano mechanism, a careful modeling of friction at pivots and between the jack and the roll, of damping and nonlinearities in felts, and of internal springs will be presented. Simulations will be confronted to the measurements of the motions of the different parts. Currently, the first phase of the motion and the transition to the second phase are well understood while some progress must still be made in order to describe correctly this short but important phase before the escapement of the hammer. [Work done in part at the Laboratory for Musical Acoustics, Paris.]
Emerging technologies in ANC at VAL-Virginia Tech
Authors: Johnson Marty , Fuller Chris , Homma Kenji
Published: October 2013

This presentation will overview the development and application of three new active noise control technologies at VAL-Virginia Tech. Distributed Active Vibration Absorbers (DAVAs) consist of large area spring elements with embedded active elements and covered with a dynamic mass layer. Development of conformal DAVAs and their application to noise control in aircraft and launch vehicle fairings will be overviewed. New work in applying active control techniques to developing virtual acoustic systems and its application to virtual prototyping and virtual reality applications will be discussed. The development a modular, compact active noise control duct which utilizes very small active sources, transducers and a cost effective controller to reducing the total radiated sound from small fans will be presented. The application of the modular ANC duct to a small computer cooling fan will be presented.
On the application of magneto-rheological dampers for reducing floor vibrations
Authors: Ahmadian Mehdi , Koo Jeong-Hoi
Published: October 2013

The primary purpose of this study is to experimentally evaluate the dynamics of a magneto-rheological tuned vibration absorber (MR TVA) with several semi-active control schemes. A test rig is built to represent a two degree of freedom primary structure model coupled with an MR TVA, and four semi-active control policies are considered. The four control policies include: velocity-based, on–off groundhook control (on–off VBG); velocity-based, continuous groundhook control (continuous VBG); displacement-based, on–off groundhook control (on–off DBG); and displacement-based, continuous groundhook control (continuous DBG). Using the test apparatus, a series of tests are conducted to investigate the dynamics of the MR TVA with each control policy. The performance of each of the cases is then evaluated along with an equivalent passive TVA, using a transmissibility analysis. The experimental results indicate that the MR TVA with all of the semi-active control policies outperforms the passive TVA in reducing structural vibrations. Furthermore, the displacement-based groundhook control policies perform better in reducing the resonant vibrations of the primary structure than the velocity-based groundhook control schemes.
Low-power, cylindrical, air-coupled acoustic levitation/concentration devices
Authors: Kaduchak Gregory , Kwiatkowski Christopher , Sinha Dipen
Published: October 2013

The detection, identification, and separation of aerosols have applications in a wide variety of fields. Particle size, size distribution, and particle composition are quantities that are important to scientists studying both the environmental impact of industrial smog and the detection of chemical or biological agents in air. One common rule in aerosol detection is that most aerosol detection devices (particle sizers, optical classifiers, etc.) are more sensitive at higher aerosol concentrations. The present research describes a new class of acoustic aerosol concentration devices that alleviate many of the alignment and power consumption requirements of traditional acoustic levitators/concentrators [Kaduchak et al., Rev. Sci. Instrum. 73, 1332–1336 (2002)]. These devices are inexpensive, low-power, and never require alignment. They are constructed from a single PZT tube. The devices operate on the premise that the lowest-order structural modes of the tube are tuned to match a corresponding resonant mode of the interior air-filled cavity. The coupled mode can be driven efficiently; drops of water in excess of 1 mm diameter can be levitated for approximately 100 mW of input electrical power. Both axisymmetric and dipole vibrational modes will be demonstrated in aerosol concentration and collection experiments.
Ultrasonic particle concentration in a line driven cylindrical tube
Authors: Goddard Greg , Kaduchak Gregory
Published: October 2013

Acoustic particle manipulation has many uses in flow cytometry and micro-fluidic array applications. Currently, most ultrasonic particle positioning devices utilize a quasi-one-dimensional geometry to set up the positioning field. A transducer fit with a quarter-wave matching layer locally drives a cavity of width one-half wavelength. Particles within the cavity experience a time-averaged drift force that transports them to a nodal position. Present research investigates an acoustic particle-positioning device where the acoustic excitation is generated by the entire structure, as opposed to a localized transducer. The lowest-order structural modes of a long cylindrical glass tube driven by a piezo-ceramic with a line contact are tuned, via material properties and aspect ratio, to match resonant modes of the fluid-filled cavity. The cylindrical geometry eliminates the need for accurate alignment of a transducer/reflector system, in contrast to the case of planar or confocal fields. Experiments show that the lower energy density in the cavity, brought about through excitation of the whole cylinder, results in reduced cavitation, convection, and thermal gradients. The effect of excitation and material parameters on concentration quality and power consumption is theoretically evaluated, using two-dimensional elastodynamic equations describing the fluid-filled cylindrical shell with a line excitation.
Accelerated adsorption by activated carbon powders in the presence of an acoustic field
Authors: Hawkins Timothy W. , Meegan G. Douglas , Peterson Chris E.
Published: October 2013

Vaporous contaminants can be removed from a gas stream by adsorption into powdered activated carbon (PAC). For example, the injection of PAC upstream of particle collectors is the leading approach for the removal of mercury vapor from the exhaust streams of incinerators and coal fired power plants. The removal of dilute vapors, though, can require significant time and significant quantities of PAC. A numerical model will be described that suggests that the adsorption process can be accelerated by applying an intense sound field to the gas after the PAC is injected. It is theorized that a sound field improves diffusion limited adsorption reactions by creating an oscillatory motion of the gas relative to the activated carbon particles. The translation effectively mixes the particles and gas on a microscopic scale and improves the concentration gradient at the surface of the PAC. Results from the numerical model suggest that adsorption rates can be increased by over 50% with the application of an appropriate sound field. Simple laboratory experiments have been performed studying the adsorption of dilute vaporous ethanol in air, and the results support the model. Data has also been collected at a coal fired power plant that demonstrates the improved adsorption of mercury vapor.