bluuebunny/crossref_metadata_2025 huggingface dataset:
Sputum ADAM8 expression is increased in severe asthma and COPD
Authors: Oreo K. M. , Gibson P. G. , Simpson J. L. , Wood L. G. , McDonald V. M. , Baines K. J.
Published: October 2013

Background

Severe asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory airway diseases in which the mechanisms are not fully understood. A disintegrin and metalloproteinase domain 8 (ADAM8) is an enzyme expressed on most leucocytes and may be important for facilitating leucocyte migration in respiratory disease.

Objective

To investigate ADAM8 mRNA and protein expression in asthma and COPD and its relationship between asthma severity and inflammatory phenotypes.

Methods

Induced sputum was collected from 113 subjects with asthma (severe n = 31, uncontrolled n = 39 and controlled n = 35), 20 subjects with COPD and 21 healthy controls. Sputum ADAM8 mRNA expression was measured by qPCR, and soluble ADAM8 (sADAM8) protein was measured in the sputum supernatant by validated ELISA.

Results

ADAM8 mRNA correlated with ADAM8 protein levels (r = 0.27, P < 0.01). ADAM8 mRNA (P = 0.004) and sADAM8 protein (P = 0.014) levels were significantly higher in both asthma and COPD compared with healthy controls. ADAM8 mRNA (P = 0.035) and sADAM8 protein (P = 0.002) levels were significantly higher in severe asthma compared with controlled asthma. Total inflammatory cell count (P < 0.01) and neutrophils (P < 0.01) were also elevated in severe asthmatic sputum. Although ADAM8 mRNA was significantly higher in eosinophilic and neutrophilic asthma (P < 0.001), sADAM8 did not differ between asthma inflammatory phenotypes. ADAM8 expression positively correlated with sputum total cell count and sputum neutrophils.

Conclusions and Clinical Relevance

ADAM8 expression is increased in both severe asthma and COPD and associated with sputum total cell count and neutrophils. ADAM8 may facilitate neutrophil migration to the airways in severe asthma and COPD.
Piezoelectric vs. conventional drilling in implant site preparation: pilot controlled randomized clinical trial with crossover design
Authors: Canullo Luigi , Peñarrocha David , Peñarrocha Miguel , Rocio Alonso‐Gonzalez , Penarrocha‐Diago Maria
Published: October 2013

Objective

To compare implant stability throughout osseointegration, peri‐implant marginal bone loss, and success rates of implants placed with conventional and mixed drilling/piezoelectric osteotomy.

Materials and methods

A pilot randomized‐controlled trial was performed on 15 patients. Each patient received two implants in the mandibular molar region. All sites were prepared with conventionally up to the 2.8 mm wide drill. Osteotomies were randomly finalized with a 3 mm diameter drill (control group) or with two consecutive ultrasonic tips (2.8 mm and 3 mm wide, respectively) (test group). Resonance frequency analysis measurements were taken at implant placement and after 1, 3, 8, and 12 weeks. Peri‐implant marginal bone loss 12 months after loading was calculated using periapical radiographs. Wilcoxon test for related samples was used to study differences in implant stability and in peri‐implant marginal bone loss between the two groups.

Results

Twenty‐nine of 30 implants osseointegrated successfully (one failure in the control group). Stability was significantly higher in the test group at the 8th week assessment; differences were non‐significant at all other time‐points. Longitudinally, differences were observed between the patterns of implant stability changes: in the test group stability increased more progressively, while in the control group an abrupt change occurred between the 8th and 12th weeks assessments. No difference was found in peri‐implant marginal bone loss between the groups. All 29 implants were functionally successful at the 15‐month visit.

Conclusions

Within the limit of this pilot study (small sample size, short follow‐up), data suggested that implant stability might develop slightly faster when implant site osteotomy is performed with a mixed drilling/ultrasonic technique.
Composite endpoints in trials of type‐2 diabetes
Authors: Einarson T. R. , Garg M. , Kaur V. , Hemels M. E. H.
Published: October 2013

Composite endpoints (CEPs) are being used more frequently as outcomes for trials of drugs in type‐2 diabetes. We reviewed the literature to determine how CEPs have been used to date in trials of drugs for type‐2 diabetes. A systematic search was undertaken on Medline, Embase and Cochrane databases and Clinicaltrials.gov for randomized controlled trials of currently marketed agents including SGLT‐2 inhibitors (dapagliflozin), GLP‐1 agonists (exenatide, liraglutide) and DPP‐4 inhibitors (linagliptin, saxagliptin, sitagliptin and vildagliptin). CEPs used were identified as well as numbers and percentages of patients achieving each. Thirty‐six studies were identified that reported results on ≥1 CEP; 15 different CEPs were reported (7 with 2 components, 8 with 3 components). All CEPs addressed goals recommended by the American Diabetes Association (ADA). All included HbA1c<7%; other endpoints measured weight, blood pressure and hypoglycaemic events. Results were obtained for CEPs from 6 months to 2 years. Rates of achieving CEPs decreased with increasing numbers of components and outcomes assessed. CEPs are becoming used as indicators of clinical outcomes in type‐2 diabetes trials, but are still not common. More research is required to identify optimal CEPs. Standardization of outcomes and their reporting is needed.
Factors influencing egg parasitism in sub‐social insects: insights from the treehopper Alchisme grossa (Hemiptera, Auchenorrhyncha, Membracidae)
Authors: CAMACHO LUIS , KEIL CLIFFORD , DANGLES OLIVIER
Published: October 2013

Subsocial insects rely on maternal care in order to enhance offspring survival. Subsocial Hoplophorionini treehoppers defend their egg masses from predatory and parasitoid attacks. Egg parasitic wasps are important enemies of the Membracidae.

We examined parasitism patterns and female defence mechanisms in the Hoplophorionini treehopper Alchisme grossa (Fairmaire). We examined the effect of aggregations of egg‐guarding females, spatial aggregations of host plants and female A. grossa, and host plant identity on the incidence of egg mass parasitism. Additionally, we measured the effect of female maternal care strategies on reducing the amount of parasitism on their egg masses.

Aggregation of egg‐guarding females on a single host plant was the most important factor affecting egg mass parasitism. Increased numbers of aggregated females lowered both parasitism risk and parasitism levels on their egg masses. When spatial clumping of host plants and egg‐guarding females occurred simultaneously, parasitism risk was also reduced. Maternal care strategies such as coverage of the egg mass by the females' pronota and intensity of female defensive behaviour also seemed to lower parasitism on egg masses.

A reduction of parasitism by female aggregation on host plants can be explained by a selfish herd dilution effect. This dilution effect was potentiated by a possible cooperation between aggregated egg‐guarding females on the host plant. The present study provides a new dimension to sub‐sociality in Hoplophorionini treehoppers.
Chlorophyll‐a concentrations and macroinvertebrate declines coincide with the collapse of overwintering diving duck populations in a large eutrophic lake
Authors: Tománková Irena , Harrod Chris , Fox Anthony D. , Reid Neil
Published: October 2013

Lough Neagh is one of the most important non‐estuarine sites in the British Isles for overwintering wildfowl. A change in the waterbird assemblage following the winter of 2000/2001 was driven mainly by a rapid decline in the population of overwintering diving ducks. Sudden and discrete changes in resident as well as migratory waterbirds may suggest an intrinsic cause.

We compared the density and biomass of benthic macroinvertebrates, the food of overwintering diving ducks, in 2010 (following the diving duck population decline) with values from a baseline survey conducted in 1997/1998 (before the decline in diving ducks).

The mean total density of macroinvertebrates declined significantly by c. 65% from 15 300 m−2 in 1997/1998 to 5136 m−2 in 2010. There was a concomitant c. 70% decline in mean macroinvertebrate biomass from 15 667 mg m −2 to 5112 mg m−2. In terms of taxonomic composition, the relative contribution of Tanypodinae, Glyptotendipes spp. and Tanytarsini declined, while the relative contribution of Chironomus spp. increased.

We describe a shift in chlorophyll‐a concentration, a proxy of phytoplankton biomass, in the largest freshwater lake in the British Isles coincident with a significant reduction in macroinvertebrate density and biomass, with potential implications for ecosystem processes and ecologically and economically important consumer populations, including waterbirds and fishes.
The Impact of Modern Noninvasive Cardiac Imaging on Coronary Intervention Rates
Authors: FRÖHLICH GEORG M. , SCHOCH BORIS , WOLFRUM MATHIAS , OSRANEK MARTIN , ENSELEIT FRANK , HERZOG BERNHARD A. , HASUN MATHIAS , LÜSCHER THOMAS F. , MEIER PASCAL , GAEMPERLI OLIVER , KAUFMANN PHILIPP A. , CORTI ROBERTO
Published: October 2013

Objectives

It remains still unclear whether the use of modern noninvasive diagnostic modalities for evaluation of coronary artery disease (computed tomography coronary angiography (CTCA), nuclear myocardial perfusion imaging (MPI)) were able to change the “diagnostic yield” of invasive coronary angiography (ICA).

Methods

The total number of ICA in the years 2000–2009 was related to the number of percutaneous interventions (PCIs) and we assessed whether there was a significant trend over time using time series analyses. We compared these data with the number of patients undergoing CTCA and nuclear MPI in the same time period.

Results

During the 10‐year observational period, 23,397 ICA were performed. The proportion of purely diagnostic ICA (without PCI) remained stable over the whole study period (tau = −0.111, P = 0.721). A CTCA program was initiated in 2005 and 1,407 examinations were performed until 2009. Similarly, the number of nuclear MPI increased from 2,284 in the years 2000–2004 to 5,260 in the years 2005–2009 (P = 0.009).

Conclusion

Despite increasing availability, noninvasive testing modalities did not significantly alter the rate of purely diagnostic ICA, and still are underused as gatekeeper to ICA. Further effort is needed to optimize the use of noninvasive imaging modalities in the work‐up process for coronary artery disease. (J Interven Cardiol 2014;27:50–57)
Innovation Incentives under Transferable Fast‐Track Regulatory Review
Authors: Gans Joshua S. , Ridley David B.
Published: October 2013

Under a 2007 U.S. law, the developer of a treatment for a neglected disease is rewarded with a fast‐track voucher that can be sold to another developer. Similar fast‐track vouchers are being offered by other agencies. We model how the existence of transferable, fast‐track vouchers can impact innovation for both humanitarian and other products, and can create competition between otherwise unrelated pursuits. We consider the tradability of fast‐track vouchers and map these to innovation race outcomes. Our analysis highlights areas for further exploration in policy settings as well as predictions for empirical analysis.
Venture Capitalists and the Patenting of Innovations
Authors: Fabrizi Simona , Lippert Steffen , Norbäck Pehr‐Johan , Persson Lars
Published: October 2013

We model patent‐signaling by informed venture capitalists to incumbent acquirers of developed innovations. We show that, to signal, venture capitalists develop more patents with higher impact than incumbents would. A tightening of patenting requirements by the patent offices, such as an increase in the required inventive step, increases the pool of unprotected early‐stage ideas, which venture capitalists are better at judging than incumbents, and decreases the number and breadth of patented claims needed to separate highly valuable from less valuable innovations. Consequently, such a tightening would make venture capitalists more likely to back entrepreneurs and increase entrepreneurial incentives to innovate.
Uncertainty and Roll‐Call Voting in Lame‐Duck Sessions of the U.S. House, 1969–2010
Authors: Nokken Timothy P.
Published: October 2013

Lame‐duck sessions of Congress have become increasingly common of late. Such sessions are marked by higher levels of ideological and participatory shirking among departing members, creating a more uncertain legislative environment. I investigate the consequences of such shirking on coalition formation and roll‐call behavior. I analyze House roll‐call votes held in the 12 congresses that convened lame‐duck sessions from 1969 to 2010 (91st to 111th Congresses) to assess how roll‐call behavior changes across sessions. I find subtle but statistically significant changes across sessions consistent with claims regarding greater uncertainty in roll‐call voting in lame‐duck sessions.
Evaluating Probabilistic Forecasts with Bayesian Signal Detection Models
Authors: Steyvers Mark , Wallsten Thomas S. , Merkle Edgar C. , Turner Brandon M.
Published: October 2013

We propose the use of signal detection theory (SDT) to evaluate the performance of both probabilistic forecasting systems and individual forecasters. The main advantage of SDT is that it provides a principled way to distinguish the response from system diagnosticity, which is defined as the ability to distinguish events that occur from those that do not. There are two challenges in applying SDT to probabilistic forecasts. First, the SDT model must handle judged probabilities rather than the conventional binary decisions. Second, the model must be able to operate in the presence of sparse data generated within the context of human forecasting systems. Our approach is to specify a model of how individual forecasts are generated from underlying representations and use Bayesian inference to estimate the underlying latent parameters. Given our estimate of the underlying representations, features of the classic SDT model, such as the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC), follow immediately. We show how our approach allows ROC curves and AUCs to be applied to individuals within a group of forecasters, estimated as a function of time, and extended to measure differences in forecastability across different domains. Among the advantages of this method is that it depends only on the ordinal properties of the probabilistic forecasts. We conclude with a brief discussion of how this approach might facilitate decision making.
Domestic and Trade Equivalences of State Trading Importers
Authors: McCorriston Steve , MacLaren Donald
Published: October 2013

Market intermediaries in importing countries in the form of state trading enterprises (STEs) involve government manipulation of market structure that can be designated a nontariff measure because they are perceived to affect market access. However, the trade effect may be only an unintended consequence of the pursuit of the domestic concerns towards which the objectives of the STE are targeted as well as the extent of the exclusive rights that it is given. These objectives may reflect concerns about domestic distortions or, where these do not exist, redistribution towards producers or consumers. To this end, identifying the domestic effects of STEs through the use of producer and consumer subsidy equivalents that complement measures of the trade distorting effect is important in gauging the overall impact of STEs. In this paper, we outline a method to measure these policy equivalences which can be readily applied to aid transparency in trade negotiations.
A Mixed Methods Examination of Adolescents' Reports of the Values Emphasized in Their Families
Authors: Wray‐Lake Laura , Flanagan Constance A. , Benavides Celina M. , Shubert Jennifer
Published: October 2013

Building on value socialization and personal values theories, this study examined adolescents' open‐ended reports of the values their families emphasize. Based on open‐ended reports of an ethnically and socioeconomically diverse sample of adolescents, we described adolescent‐reported familial values using qualitative and cluster analysis techniques. Adolescents' open‐ended responses about the values held by their families were coded using a prominent circumplex value model, and values largely, but not completely, aligned with this model. Using person‐oriented cluster analysis on the coded data, seven distinct value clusters were identified that captured various sets of values that adolescents hear from families. Several demographic differences emerged among the clusters, and mean differences by familial value cluster were found for adolescents' close‐ended reports of values of helping others and religiosity. Results suggest that adolescents are able to articulate values emphasized in their families in ways that fit a universal structure of values; these values are related in meaningful ways to the values that they themselves want to live by.
The novel allele, HLA‐DQB1*02:27, identified in a German cord blood donor and his mother
Authors: Strobel J. , Ringwald J. , Hauck B. , Eckstein R. , Zingsem J.
Published: October 2013

The novel allele HLA‐DQB1*02:27 identified in two related individuals of Caucasian origin is described.
Identification of a novel HLA‐B allele HLA‐B*07:185 in a Japanese individual
Authors: Maekawa K. , Futagami T. , Kusunoki Y. , Matsuzaki Y. , Takikawa H.
Published: October 2013

HLA‐B*07:185 differs from B*07:02:01 by one nucleotide substitution in exon 2 at position 300G>C.
Motor unit recruitment by size does not provide functional advantages for motor performance
Authors: Dideriksen Jakob L. , Farina Dario
Published: October 2013

Key points

Motor unit recruitment according to size (orderly recruitment) is almost universally observed in human muscles.

Using genetic optimization methods on neuromuscular models, we explored the functional basis for orderly recruitment.

We show that the key features for optimal muscle performance are the number of motor neurons innervating the muscle and the distribution of their innervation numbers, and that a random recruitment order is as effective as a recruitment ordered by size.

This implies that size‐ordered recruitment of motor neurons universally arises due to its intrinsic linkage to innervation number and not for function optimization.

These findings have implications for our understanding of human neural control of movement.

Abstract  It is commonly assumed that the orderly recruitment of motor units by size provides a functional advantage for the performance of movements compared with a random recruitment order. On the other hand, the excitability of a motor neuron depends on its size and this is intrinsically linked to its innervation number. A range of innervation numbers among motor neurons corresponds to a range of sizes and thus to a range of excitabilities ordered by size. Therefore, if the excitation drive is similar among motor neurons, the recruitment by size is inevitably due to the intrinsic properties of motor neurons and may not have arisen to meet functional demands. In this view, we tested the assumption that orderly recruitment is necessarily beneficial by determining if this type of recruitment produces optimal motor output. Using evolutionary algorithms and without any a priori assumptions, the parameters of neuromuscular models were optimized with respect to several criteria for motor performance. Interestingly, the optimized model parameters matched well known neuromuscular properties, but none of the optimization criteria determined a consistent recruitment order by size unless this was imposed by an association between motor neuron size and excitability. Further, when the association between size and excitability was imposed, the resultant model of recruitment did not improve the motor performance with respect to the absence of orderly recruitment. A consistent observation was that optimal solutions for a variety of criteria of motor performance always required a broad range of innervation numbers in the population of motor neurons, skewed towards the small values. These results indicate that orderly recruitment of motor units in itself does not provide substantial functional advantages for motor control. Rather, the reason for its near‐universal presence in human movements is that motor functions are optimized by a broad range of innervation numbers.
Spiral model of pitch
Authors: Miller James D.
Published: October 2013

A spiral model of pitch interrelates tone chroma, tone height, equal temperament scales, and a cochlear map. Donkin suggested in 1870 that the pitch of tones could be well represented by an equiangular spiral. More recently, the cylindrical helix has been popular for representing tone chroma and tone height. Here it is shown that tone chroma, tone height, and cochlear position can be conveniently related to tone frequency via a planar spiral. For this ‘‘equal-temperament spiral,’’ (ET Spiral) tone chroma is conceived as a circular array with semitones at 30° intervals. The frequency of sound on the cent scale (re 16.351 Hz) is represented by the radius of the spiral defined by r=(1200/2π)θr, where θr is in radians. By these definitions, one revolution represents one octave, 1200 cents, 30° represents a semitone, the radius relates θ to cents in accordance with equal temperament (ET) tuning, and the arclength of the spiral matches the mapping of sound frequency to the basilar membrane. Thus, the ET Spiral gives tone chroma as θ, tone height as the cent scale, and the cochlear map as the arclength. The possible implications and directions for further work are discussed.
On perception of missing fundamental
Authors: Matsuoka Takahide , Ito KeNichi
Published: October 2013

The frequency band of one channel of telephone line is from 300 Hz to 3400 Hz. Although the pitch frequency of speech is not in the frequency band, the frequency can be perceived through telephone. So, the psycho acoustic experiments of missing fundamental f0 were carried out at hearing a compound sound of f1 and f2, where f1=nf0, f2=(n+k)f0, n and k: natural numbers. It has been confirmed, by a significant difference test, that the missing fundamental can be heard. Then, it was investigated how the phase difference and amplitude difference between f1 and f2 influence the production of f0. The results are the following. The phase difference does not influence on the perception of f0. The amplitude difference in some range does not influence it. Those mechanisms have been made clear by consideration based on the experimental results using cochlea models. Now, the perception of missing fundamental for higher harmonics is being investigated.
Adaptive modeling of compression hearing aids: Convergence and tracking issues
Authors: Parsa Vijay , Jamieson Donald
Published: October 2013

Typical measurements of electroacoustic performance of hearing aids include frequency response, compression ratio, threshold and time constants, equivalent input noise, and total harmonic distortion. These measurements employ artificial test signals and do not relate well to perceptual indices of hearing aid performance. Speech-based electroacoustic measures provide means to quantify the real world performance of hearing aids and have been shown to correlate better with perceptual data. This paper investigates the application of system identification paradigm for deriving the speech-based measures, where the hearing aid is modeled as a linear time-varying system and its response to speech stimuli is predicted using a linear adaptive filter. The performance of three adaptive filtering algorithms, viz. the Least Mean Square (LMS), Normalized LMS, and the Affine Projection Algorithm (APA) was investigated using simulated and real digital hearing aids. In particular, the convergence and tracking behavior of these algorithms in modeling compression hearing aids was thoroughly investigated for a range of compression ratio and threshold parameters, and attack and release time constants. Our results show that the NLMS and APA algorithms are capable of modeling digital hearing aids under a variety of compression conditions, and are suitable for deriving speech-based metrics of hearing aid performance.
Vowel formant discrimination in high-fidelity speech by hearing-impaired listeners
Authors: Kewley-Port Diane , Liu Chang , Burkle T. Zachary
Published: October 2013

The ability to discriminate differences in vowel formant frequency under a more ordinary listening condition has been reported recently by Kewley-Port and Zheng (1999) for synthetic speech and Liu and Kewley-Port (2003) for high-fidelity speech. Results for normal-hearing (YNH) listeners showed that a longer phonetic context (sentences versus words) degraded formant discrimination while adding a sentence identification task did not. The present study used the same high-fidelity stimuli but employed listeners with moderate hearing impairment (YHI). Experimental factors manipulated included phonetic context (isolated vowels, words and sentences), level [70-dB SPL (partially audible) and 95-dB SPL (fully audible)], and task (discrimination with and without the sentence identification task). Thresholds for F1 and F2 of the vowels /I, ε, æ ʌ/ were estimated using adaptive tracking for 71% correct discrimination. The anticipated degrading effects of higher formant frequency and longer phonetic context were obtained. Unexpectedly formant thresholds for high-fidelity vowels at the higher (95-dB SPL) were slightly elevated compared to the 70-dB SPL level, the opposite of results for synthetic vowels. No effect of the added sentence task was seen, similar to the YNH listeners. Details of the differences in vowel processing attributable to moderate hearing impairment will be discussed. [Research supported by NIH-NIDCD.]
Measurement of acoustic and streaming velocities in fluids using laser Doppler anemometry
Authors: Thompson Michael W. , Atchley Anthony A.
Published: October 2013

The optical technique of laser Doppler anemometry (LDA) can be used to measure both acoustic and streaming velocities in a fluid. In a typical LDA system, two coherent laser beams intersect within the fluid to form a series of interference fringes. Whenever a small tracer particle suspended in the fluid passes through these fringes, light is scattered with an intensity that fluctuates at a frequency proportional to the particle velocity. This intensity is measured using a photodetector, and the resultant signal is processed to yield the fluid velocity. An overview of several signal processing methods will be given, and the inherent strengths and weaknesses of the LDA technique will be discussed. The authors have used LDA with burst spectrum analysis and recursive Fourier averaging to measure standing-wave acoustic velocities in the range of 0.02–15 m/s, and to measure Rayleigh streaming velocities in the range of 0.1–20 cm/s in the presence of standing-wave acoustic velocities that were 2–3 orders of magnitude larger. [Work supported by ONR.]
Particle image velocimetry measurements in thermoacoustic refrigerators
Authors: Blanc-Benon Philippe
Published: October 2013

The knowledge of flow fields in the microchannels and at the edges of the stack plates becomes an increasingly important issue in the design of heat exchangers for thermoacoustic engines. We have developed numerical simulations and conducted experiments in a resonant standing wave thermoacoustic refrigerator model. Recent computational evidence indicates that near the edges of the plates the flow field is dominated by concentrated eddies, whose complex motion significantly affects the performance of the device. Consequently, the effective design and optimization of thermoacoustic refrigerators necessitates a fundamental understanding of these vortical motions, and their dependence on geometric parameters and operating conditions. We present experimental data obtained using Particle Image Velocimetry: velocity profiles across the microchannels, 2D velocity maps including a zoom for the edges of the stack, and vorticity fields calculated with a criterion based on a normalized angular momentum. Results are obtained for two distinct configurations, involving thin and thick stack plates. In the first case, the flow field around the edge of the stack exhibits elongated vorticity layers, while in the latter it is dominated by the shedding and impingement of concentrated vortices. Time-resolved PIV measurements of the velocity and vorticity fields are compared with computational predictions.
Measurements in acoustic boundary layers
Authors: Huelsz G. , Castrejon-Pita A. A. , Castrejon-Pita J. R. , Lopez-Alquicira F. , Ramos E. , Tovar R.
Published: October 2013

A summary of the results from experimental measurements of temperature and velocity in the oscillatory boundary layers produced by acoustic waves (acoustic boundary layers) are presented. Temperature measurements were done using the named cold wire anemometer and velocity measurements were done using hot wire and laser Doppler anemometers and particle image velocimetry. Experimental results are compared to theoretical results of a linear theory. The advantages and the limitations of these experimental techniques are discussed, especially for their use in acoustic boundary layers. [Partial support for this work has been provided by DGAPA-UNAM IN104702-2 and CONACYT 32707-U projects.]
Age effects on acquisition of word stress in Spanish–English bilinguals
Authors: Guion Susan G. , Clark J. J. , Harada Tetsuo
Published: October 2013

Based on studies of syntactic and semantic learning, it has been proposed that certain aspects of second language learning may be more adversely affected by delays in language learning than others. Here, this proposal is extended to the phonological domain in which the acquisition of English word stress patterns by early (AOA <6 years) and late (AOA >14 years) Spanish–English bilinguals is investigated. The knowledge of English word stress was investigated by three behavioral tasks. In a production task, participants produced two syllable nonwords in both noun and verb sentence frames. In a perception task, participants indicated a preference for first or last syllable stress on the nonwords. Real words that were phonologically similar to the test items were also collected from each participant. Regression analyses and ANOVAs were conducted to determine the effect of syllable structure, lexical class, and stress pattern of phonologically similar words on the data from the production and perception tasks. Early bilinguals patterned similarly to the native English participants. Late bilinguals showed little evidence of learning prosodically based stress patterns but did show evidence of application of distributional patterns based on lexical class and analogy in stress assignment. [Research supported by NIH.]
The effects of four variables on the intelligibility of synthesized sentences
Authors: Conroy Carol , Raphael Lawrence J. , Bell-Berti Fredericka
Published: October 2013

The experiments reported here examined the effects of four variables on the intelligibilty of synthetic speech: (1) listener age, (2) listener experience, (3) speech rate, and (4) the presence versus absence of interword pauses. The stimuli, eighty IEEE–Harvard Sentences, were generated by a DynaVox augmentative/alternative communication device equipped with a DECtalk synthesizer. The sentences were presented to four groups of 12 listeners each (children (9–11 years), teens (14–16 years), young adults (20–25 years), and adults (38–45 years). In the first experiment the sentences were heard at four rates: 105, 135, 165, and 195 wpm; in the second experiment half of the sentences (presented at two rates: 135 and 165 wpm), contained 250 ms interword pauses. Conditions in both experiments were counterbalanced and no sentence was presented twice. Results indicated a consistent decrease in error rates with increased exposure to the synthesized speech for all age groups. Error rates also varied inversely with listener age. Effects of rate variation were inconsistent across listener groups and between experiments. The presences versus absences of pauses affected listener groups differently: The youngest listeners had higher error rates, and the older listeners lower error rates when interword pauses were included in the stimuli. [Work supported by St. John’s University and New York City Board of Education, Technology Solutions, District 75.]
Experimental design and processing for time-reversal communications in a highly reverberant environment
Authors: Guidry Brian L. , Candy James V. , Poggio Andrew J. , Meyer Alan W.
Published: October 2013

A suite of experiments has recently been conducted to validate the utility of using time-reversal (T/R) theory to solve a communications problem for highly reverberant environments. This paper discusses the design and layout of those experiments as well as experimental equipment criteria and selection. Solutions to problems arising from equipment limitations encountered during the experimental design process are examined. The signal processing used to extract information from gathered data is described and it is shown that communications receivers utilizing T/R theory can be used to accurately reproduce messages broadcast through hostile, reverberant communications channels.
Software-centered implementation of 128 channel huge speaker array with stock PC
Authors: Mizoguchi Hiroshi , Tamai Yuki , Nagashima Koichi , Kagami Satoshi , Takano Tachio , Nagashima Koichi
Published: October 2013

A huge speaker array system of 128 loudspeakers was constructed and experimented. It was implemented as ‘‘software-centered’’ style utilizing stock loudspeakers and a PC. No dedicated hardware nor DSP was utilized. Spot forming, instead of beam forming, could be realized by 32 by 4 square layout of the array. Spot means small area of higher sound pressure level. Number of the spot was not limited to one. In the experiment, within 3 m by 3 m area, four spots of different sounds could be simultaneously formed. This spot forming was confirmed by actually measured spatial distribution of sound pressure level. The effect of the spot was also confirmed auditorily. Since the system was software-centered, it was dynamic. By simply changing software parameters, location of the spot can be easily moved even while the system was running. This movability of the spot was intended to be basis for visual steering. To realize the system, a simultaneous 128 channel 14-bit DA converter PCI board was developed. 44.1 kHz sampling rate was achieved by 2.4-GHz Intel Xeon-based PC utilizing the DA board and a real-time OS, named ART-Linux. Approximately 23-μs loop could be realized by software. It was the world’s fastest software loop.
Measurements of the attenuation and phase velocities in bubbly fresh and salt water
Authors: Nicholas Michael , Orris Gregory J.
Published: October 2013

Several types of bubblers have been used to create a dense bubble cloud that fills a 44-m3 tank, wherein phase velocity and attenuation measurements have been made over a wide range of frequencies. Initial experimental results on the measurement of the phase velocity and attenuation have been previously reported [J. Acoust. Soc. Am. 112, 2269]. We present in this paper how this work has been extended with respect to the environmental parameter landscape. Paramount among these parameters are the bubble size distribution, void fraction, temperature, and surface tension. In these sets of experiments, void fractions from 0.5% to roughly 4% are investigated over a wide set of temperatures to give a much larger experimental picture of acoustic propagation through near-surface bubble clouds. Current techniques for measuring these quantities will be discussed and results presented within the context of current theories with implications on ocean acoustic experiments. Additionally, initial work using data collected using various concentrations of salt water will also be presented. [Work supported by ONR.]
Pulse distortion of a signal passing through a bubble cloud
Authors: Goodman Ralph R. , Caruthers Jerald W.
Published: October 2013

At the 145th Meeting of the Acoustical Society the authors presented a paper on the dispersion and absorption of sound in an idealized bubble field that had a bubble radius size distribution n(a) decreasing as the fourth power [J. Acoust. Soc. Am. 113, 1278 (2003)]. It was shown that, for this case, exact, relatively simple, analytic solutions exist both for dispersion and absorption. The same model is used here to calculate the effects of dispersion and absorption on pulsed signals as they propagate through a bubbly mixture. The approach is essentially the same as that used by Frank Henyey (unpublished) to analyze the propagation of signals through clouds that were observed in the well-known 1997 Scripps Pier experiment. The effects on signal shapes as a function of range and bubble density and size distribution will be presented.
Field trial of a Doppler sonar system for fisheries applications
Authors: Tollefsen Cristina D. S. , Zedel Len
Published: October 2013

Various deployments of commercial Doppler current profiling systems have demonstrated that these instruments can detect fish and measure their swimming speeds. However, research into the possible application of Doppler sonar to fisheries problems is limited and has not taken advantage of coherent signal processing schemes. A field trial was undertaken in August 2002 to explore the capabilities of a coherent Doppler sonar when applied to detecting discrete targets. The passage of migrating salmon on the Fraser River in British Columbia provided an ideal test opportunity with fish of well-defined swimming behavior and allowed for comparisons with conventional fisheries acoustics techniques. The instrument tested was a 250-kHz sonar which provided for phase coding of transmit pulses and coherent sampling of successive acoustic returns. The field trial resulted in 11 consecutive days of Doppler sonar data acquired during the peak of the sockeye salmon (Oncorhynchus nerka) migration. A total of 7425 individual fish were identified and their swimming speed was measured with an accuracy of between 10 cms−1 and 20 cms−1, which depended on pulse length, pulse spacing, and target range. By comparison, water velocity measurements made with the same instrument can only achieve a theoretical accuracy of 60 cms−1.
Fish schools are the dominant cause of long-range active sonar clutter in the New Jersey Continental Shelf: Quantitative correlations
Authors: Symonds Deanelle T. , Ratilal Purnima , Nero Redwood W. , Makris Nicholas C.
Published: October 2013

Long-range underwater acoustic remote sensing data, acquired using a low- to mid-frequency bistatic sonar system, is compared with data from a downward-directed, fisheries-standard high-frequency fish-finding sonar. These data were simultaneously measured in the New Jersey Continental Shelf environment during the Main Acoustic Clutter Experiment 2003. The long-range sonar is capable of imaging extensive areas, spanning tens of kilometers in range, in near real-time. This makes it possible to continuously observe the spatial and temporal variability of environmental returns over wide areas. In contrast, the fish-finding sonar’s single, downward-directed beam typically provides a swath of only 10 m width along the ship track. Dense populations of fish, indicated by prominent returns from the fish-finding sonar, are overlain onto long-range acoustic images. The outputs of the two systems are also directly correlated along the track of the fish-finding sonar. High correlation was found between locations of prominent environmental clutter in the long-range sonar system and locations of densely clustered fish schools measured with the fish-finding sonar. Additionally, regions absent of clutter were also found to be absent of significant fish populations. These correlations were observed repeatedly over a period of roughly 3 weeks.
Long-term, large-scale acoustic fluctuations in the Ulleung Basin
Authors: DelBalzo Donald R. , Winsett LauriAne , Rike Erik R.
Published: October 2013

An analysis of long-term, large-scale oceanographic conditions in the Southern Japan/East Sea has identified several interesting phenomena, including a previously undiscovered stable eddy. That analysis was based on temperature profile data observed daily with 23 PIES (pressure inverted echo sounder) instruments spaced at about 40 km throughout the Ulleung Basin during a 2-year period. In the present work, a gridded version of the PIES data was used to study the relation between oceanographic structure and acoustic transmission loss structure from 50 to 500 Hz throughout the area in terms of long-term fluctuations on the order of days to weeks. Significant correlations between oceanographic and acoustic variability were observed with different characteristics during summer and winter. The results indicate predictably stable acoustic paths that correlate with benign ocean conditions and predictably unstable acoustic paths that correlate with dynamic ocean features. The implication is that there are frequencies and sensor geometries that favor long-term acoustic monitoring with controlled uncertainty and that certain stable scenarios preclude the need for daily temperature sampling. [Work sponsored by ONR.]
Gulf of Mexico oceanography and acoustic-pulse propagation across the DeSoto Canyon
Authors: Caruthers Jerald W. , Vinogradov Sergey , Vinogradova Nadya , Sidorovskaia Natalia A. , Ioup George E. , Ioup Juliette W. , Udovydchenkov Ilya
Published: October 2013

To investigate the feasibility of monitoring the movements of the large eddies that dominate circulation in the deep waters of the Gulf of Mexico, acoustic-propagation studies are made using historic and ocean dynamic model data for sound-speed profiles representing the distinctions among the various water masses inside and outside these eddies. The propagation work concentrates on a slice across the DeSoto Canyon in the northeast Gulf from the shelf break off the Mississippi Delta to the Florida shelf—a region in which a deep sound channel exists. The objective for the study of this slice is to determine the potential for monitoring the movement and evolution of eddies as they enter DeSoto Canyon. Two frequency bands of a pulse source (400–600 and 900–1100 Hz) and deep water source placements near the sound-channel axis (900 m) and a vertical array of receivers are used in modeling. Details of the temporal structure in the arrivals show significant variations for the different waters of the order of 0=2E1 s. Transmission losses in the deep-water channel were of the order of 100 dB over the approximate 200-km propagation path used in the modeling, which gives an estimate of the requirements for the source-receiving system. [Work supported in part by the Littoral Acoustic Demonstration Center sponsored by ONR.]
Angular dependence of fluctuations in acoustic transmissions relative to tidal direction in the SWAT environment
Authors: George Jacob , Field Robert L.
Published: October 2013

Recently, fluctuations in continuous wave acoustic transmissions through internal tides that are periodic and have a constant amplitude in range have been studied [J. George and R. L. Field, J. Acoust. Soc. Am. 113, 2333 (2003)]. It was demonstrated through WKB/Pekeris calculations that the fluctuations are significantly greater when the transmission is nearly perpendicular to the tidal direction, and decrease when the transmission becomes more parallel to the tidal direction. Testing the validity of the above results in the realistic ocean provided the motivation for the present work. This was done through simulation using the NRL Coastal Ocean Model (NCOM) fitted to experimental data. The NCOM output provided the sound speed profile as a function of space and time. Results of the simulation will be presented. [Work supported by ONR (PE-62435N), and administered by NRL.]
Time-frequency variability of broadband sound propagation through shallow water internal soliton
Authors: Katsnelson Boris , Pereselkov Sergey , Badiey Mohsen , Lynch James
Published: October 2013

Temporal fluctuations of the sound intensity in shallow water are studied using broadband acoustic signal propagation through an internal soliton (IS) wave front. Time-frequency analysis of the received signals at two different vertical arrays is conducted based on the wavelet transform. The intensity fluctuations as a function of geophysical time are shown for different positions of the IS with respect to the acoustic propagation path. A theoretical model consisting of internal waves coupled with the acoustic normal modes and horizontal rays is presented. The correlation between the signal fluctuations and the internal soliton is analyzed using frequency dependent index of refraction. Model results are compared with the SWARM-95 experimental observation. [Work supported by ONR and RFBR Grant No. 03-05-64568.]
Vibration characteristics of implants
Authors: Al-Jumaily Ahmed M. , Fatemi Mostafa , Greenleaf James F.
Published: October 2013

Vibro-acoustography is a technique that uses the radiation force of amplitude-modulated ultrasound to evaluate the dynamic response of an object at the modulation frequency. One potential application of this technique is to assess the reaction of the host tissue to the implant material by evaluating the mechanical properties of the tissue surrounding the implant. To do this, we use vibro-acoustography to measure the frequency response of the implant, and use this information to evaluate the mechanical parameters of the surrounding. Two theoretical models are developed to study the dynamic response of an implant in tissue. The first model is for an implant (1×25-mm steel beam) fully embedded in a viscoelastic medium (tissue). The second model is for a partially embedded implant with one part exposed to the open environment. The exposed end is rigidly connected to a base, and the other end is freely embedded in the viscoelastic medium. At the interface between the two media matching of boundary conditions is achieved to determine the force response. For both models eigenvalues and eigenfunctions are determined and transfer functions are evaluated. The first two natural frequencies compare well with available experimental and finite-element data.
Analogies between the measurement of acoustic impedance via the reaction on the source method and the automatic microwave vector network analyzer technique
Authors: McLean James , Sutton Robert , Post John
Published: October 2013

One useful method of acoustic impedance measurement involves the measurement of the electrical impedance ‘‘looking into’’ the electrical port of a reciprocal electroacoustic transducer. This reaction on the source method greatly facilitates the measurement of acoustic impedance by borrowing highly refined techniques to measure electrical impedance. It is also well suited for in situ acoustic impedance measurements. In order to accurately determine acoustic impedance from the measured electrical impedance, the characteristics of the transducer must be accurately known, i.e., the characteristics of the transducer must be ‘‘removed’’ completely from the data. The measurement of acoustic impedance via the measurement of the reaction on the source is analogous to modern microwave measurements made with an automatic vector network analyzer. The action of the analyzer is described as de-embedding the desired data (such as acoustic impedance) from the raw data. Such measurements are fundamentally substitution measurements in that the transducer’s characteristics are determined by measuring a set of reference standards. The reaction on the source method is extended to take advantage of improvements in microwave measurement techniques which allow calibration via imperfect standard loads. This removes one of the principal weaknesses of the method in that the requirement of high-quality reference standards is relaxed.