bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipedematous Scalp in a Child
Authors: Rowan Darion M. , Simpson Alan , Wong Kwong P.
Published: June 2006

Abstract:  A nine year old Maori girl was noted to have a spongy consistency to her posterior scalp. The overlying skin appeared normal, as was hair growth in that area. The abnormal findings became more extensive over the subsequent year. A computerized tomography scan showed diffuse thickening of subcutaneous tissues posteriorly on the scalp. A skin biopsy specimen showed a normal epidermis with a thick layer of mature subcutaneous fat and some disruption of the subcutaneous architecture. The clinical features and investigations were consistent with a diagnosis of lipedematous scalp, which has been described predominantly in adult women and is usually associated with alopecia. This condition has not been reported previously in the pediatric literature.
Acute Percutaneous Lactic Acid Poisoning in a Child
Authors: Ramírez Manuela Esteban , Youseef Wael Fasheh , Romero Roser Garrido , Martínez José María Quintillá , González‐Enseñat Maria Antonia , Vilaplana Xavier Sanmartí , Cubells Carles Luaces
Published: June 2006

Abstract:  Percutaneous poisoning is quite rare, and in particular, topical lactic acid poisoning is even more so. We report a young girl with lamellar ichthyosis and symptoms of poisoning, with clinical signs of irritability, agitation, myoclonia, and difficulty in walking, accompanied by lactic acidosis as a result of the more frequent than recommended application of emollients containing lactic acid. The clinical symptoms resolved upon discontinuation of the topical treatment. Among the possible causes of metabolic acidosis, health care providers should be aware of the possibility of percutaneous poisoning.
How Much do you Trust Me? The Dark Side of Relational Trust in New Business Creation in Established Companies
Authors: Zahra Shaker A. , Yavuz R. Isil , Ucbasaran Deniz
Published: June 2006

Entrepreneurship in established companies centers on new business creation that is essential for profitability and growth. Yet, it is a complex process that is riven with technical, organizational, and political uncertainties. In this article, we explore the role of trust in the new business creation process in established companies. While there is agreement that trust is conducive to entrepreneurial activities in these companies, research on the dysfunctional effects of trust on new business creation initiatives has been sparse. We contribute to the literature by discussing the various stages of the business creation process (focusing on opportunity recognition, evaluation, refinement, championing, and implementation) in established companies, examining the positive effects of relational trust on each of these stages, and analyzing the negative effects of overreliance on relational trust for each stage. We conclude by highlighting the key managerial and theoretical implications of our analyses and by outlining promising avenues for future research.
Razorfish: Note to Instructors
Authors: Forbes Daniel P. , Pavone Carla
Published: June 2006

This note provides guidance to instructors who may be interested in using the case study, “Razorfish,” for educational purposes in their classrooms.
Effect of Na2SO4 on Structure and Corrosion Resistance of Ceramics Coatings Containing Zirconium Oxide on Ti–6Al–4V Alloy
Authors: Yao Zhongping , Jiang Zhaohua , Zhang Xuelin
Published: June 2006

A micro‐plasma oxidation (MPO) technique has been developed in recent years, by which ceramic coatings are reported to possess improved properties and promising application prospects in many fields. The aim of this work was to study the effect of sodium sulfate, as an additive in the zirconate system, on the structure and corrosion resistance of ceramics coatings containing zirconium oxide grown on Ti–6Al–4V by MPO process. The phase composition, morphology, and element distribution in the coating were investigated by X‐ray diffractometry, scanning electron microscopy, and energy distribution spectroscopy. Meanwhile, the corrosion resistance of the coated samples was examined by polarizing curves and potentiodynamic anodic curves in 3.5% NaCl solution. The results show that ceramic coatings were composed of m‐ZrO2, t‐ZrO2, and KZr2(PO4)3. The Ti content in the coating near the substrate decreased sharply, and then remained at 5 wt% or so through the coating, while the Zr content near the substrate increased greatly, and then remained at about 55 wt% through the coating. The addition of sodium sulfate did not change the composition of the coatings, but increased the relative proportion of zirconium oxide to KZr2(PO4)3 in the coating. Sodium sulfate decreased the thickness of the coating, while improving the density of the coatings. Moreover, the addition of the sodium sulfate improved the corrosion resistance of the coated samples in a 3.5% NaCl solution, whether considering localized pitting corrosion resistance or uniform corrosion resistance.
Hydrothermal Synthesis of Nano Ce–Zr–Y Oxide Solid Solution for Automotive Three‐Way Catalyst
Authors: Yucai Hu
Published: June 2006

Nano Ce–Zr–Y (CZY) oxide solid solution was synthesized using hydrothermal method using the nitrate of cerium, zirconium, and yttrium as raw materials and urea as a hydrolysis agent. The sample was characterized using a X‐ray diffraction and FT‐Raman spectra to show whether Zr and Y ions were incorporated into the crystal cell of CeO2. Scanning electronic microscopy and transmission microscopy images were recorded to examine the particle morphology. Meanwhile, the palladium‐only three‐way catalyst (TWC)‐containing CZY was prepared and evaluated under the condition of simulated exhaust. The results show that CZY has a cubic fluorite structure and the as‐synthesized solid solution has a particle diameter less than 100 nm. The TWC‐containing CZY has a higher catalytic activity including a wider operation window of air/fuel ratio and a lower lighter‐off temperature.
Effect of Processing on the Microstructure and Induced‐Strain Mismatch in Magnesia–Alumina‐Layered Composites
Authors: Kim Chang Soo , Lombardo Stephen J. , Winholtz Robert A.
Published: June 2006

A method is described whereby thin ceramic shapes are induced to adopt a different shape at elevated temperature without the application of an external pressure. To achieve deformation, thin beams of alumina are coated with magnesia; at a high temperature, the strain mismatch that arises in the sample leads to deformation. Scanning electron microscopy and compositional profiling suggest that a bilayer structure forms. One layer contains both Mg and Al cations and the spinel phase is present, whereas the second layer consists predominantly of alumina. A mechanics model based on strain mismatch in bilayer systems indicates how the resulting curvature depends on the thickness of the two regions. A mechanistic model is derived that describes the strain mismatch in terms of the degree of conversion to spinel, the amount of differential sintering between layers, and the amount of residual porosity present in the two layers of the substrate.
Synthesis and Characterization of Nanocrystalline SrTiO3
Authors: Balaya Palani , Ahrens Martin , Kienle Lorentz , Maier Joachim , Rahmati Behnaz , Lee Sung Bo , Sigle Wilfried , Pashkin Alexej , Kuntscher Christine , Dressel Martin
Published: June 2006

The synthesis and densification of fairly dense nanocrystalline SrTiO3 and its characterization are described in this paper in detail. Significant grain growth was avoided by the application of a two‐stage sintering process using hot pressing. High‐resolution transmission electron microscopy and electron energy loss spectroscopy characterizations indicate pure material with no detectable chemical inhomogeneities. The electrical measurements indicate the disappearance of bulk contribution to the electrical conduction due to the overlap of depleted space charge layers if the grain size is below 100 nm. Owing to the overlap, the capacitance appears as bulk‐like rather than due to space charge polarization. Non‐contact sub‐millimeter optical spectroscopy measurements reveal strong suppression of the dielectric constant values at low temperature.
Effect of different Agaricus species on the development of the mushroom sciarid fly Lycoriella ingenua
Authors: Smith J.E. , White P.F. , Edmondson R.N. , Chandler D.
Published: June 2006

Isolates from eight species of Agaricus were investigated in laboratory experiments for their effect on the development of the mushroom sciarid fly, Lycoriella ingenua (Dufour) (Diptera: Sciaridae), which is an important pest of the white mushroom Agaricus bisporus (Lange) Imbach (Agaricaceae). The population levels of L. ingenua developing in compost inoculated with Agaricus mycelium varied with the Agaricus isolate used, with some isolates causing high levels of inhibition. The development of L. ingenua populations and the survival of larval instars were inversely proportional to the amount of Agaricus inoculum applied. There was also a negative relationship between L. ingenua survival and the extension rate of the Agaricus isolate in compost. The results suggest that inhibition of L. ingenua population development by Agaricus is linked to the rate at which compost is colonized by fungal mycelium. Therefore, on mushroom farms, sciarid fly control should focus on protection of the compost before it has become colonized by mycelium, as this is when it is most vulnerable to the pest.
Spatial and temporal dynamics of oviposition behavior of bollworm and three of its predators in Bt and non‐Bt cotton fields
Authors: Torres Jorge B. , Ruberson John R.
Published: June 2006

Host plants exhibiting insect resistance traits have long been known to influence within‐plant distributions of pests and their natural enemies. Sites and timing of egg deposition are particularly important for synchrony of predators and their prey in the field. Temporal and spatial distribution of eggs of the cotton bollworms [Heliothis virescens (F.) and Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)] and that of the predators Geocoris punctipes (Say) (Heteroptera: Geocoridae), Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae), and Micromus spec. (Neuroptera: Hemerobiidae) were determined during three cotton seasons, from 2002 to 2004, by collecting and examining plants throughout each season. Comparisons also were made between Bt and non‐Bt cotton to investigate possible changes in oviposition behavior on Bt cotton. The study was conducted in commercial fields with insecticide use to manage pests when economic thresholds were exceeded in both cotton types. Egg densities for predators and bollworms varied among years, but were similar on Bt and non‐Bt cottons. Oviposition of bollworms and G. punctipes correlated spatially within plants, with most eggs laid on structures in the top five nodes of cotton plants and on the three outermost leaves on lateral branches regardless of cotton type. Bollworm oviposition dynamics exhibited two peaks within the season (early July and early August). Eggs of all predators and bollworms collected from the field and incubated in the laboratory had high hatching rates throughout each season (74–100%). Temporal association of predator with bollworm oviposition showed a significant correlation with green lacewings, a delay of 10 days for big‐eyed bugs, and no correlation with brown lacewings. Furthermore, Bt cotton plants exerted no significant effect on temporal or spatial patterns of oviposition of bollworms or the predators, indicating no change in oviposition behavior of bollworm females within plant structures after almost one decade of widespread planting of Bt cotton.
Genetic structure of European and Mediterranean maize borer populations on several wild and cultivated host plants
Authors: Leniaud Laurianne , Audiot Philippe , Bourguet Denis , Frérot Brigitte , Genestier Gilles , Lee Siu Fai , Malausa Thibaut , Le Pallec Anne‐Hélène , Souqual Marie‐Claude , Ponsard Sergine
Published: June 2006

Target pests may become resistant toBacillus thuringiensis(Bt) toxins produced by trangenic maize (Zea maysL.). Untreated refuge areas are set aside to conserve high frequencies of susceptibility alleles: a delay in resistance evolution is expected if susceptible individuals from refuges mate randomly with resistant individuals from Bt fields. In principle, refuges can be toxin‐free maize or any other plant, provided it hosts sufficiently large pest populations mating randomly with populations from Bt‐maize fields. Our aim was to examine the suitability of several cultivated or weedy plants [pepper (Capsicum frutescensL.), sorghum (Sorghumspec.), sunflower (Helianthus annuusL.), cocklebur (Xanthiumspec.), cantaloupe (Cucumis meloL.), and hop (Humulus lupulusL.)] as refuges forOstrinia nubilalis(Hübner) (Lepidoptera: Crambidae) andSesamia nonagrioidesLefebvre (Lepidoptera: Noctuidae), two major maize pests in southern Europe. Larvae of both species were collected on these plants. Their genetic population structure was examined at several allozyme loci. We found little or no evidence for an influence of geographic distance, but detected a significant host‐plant effect on the genetic differentiation for both species.Ostrinia nubilalispopulations from sunflower, pepper, cocklebur, and sorghum appear to belong to the same genetic entity as populations collected on maize, but to differ from populations on hop. Accordingly, females from pepper and cocklebur produced exclusively the ‘Z’ type sexual pheromone, which, in France, characterizes populations developing on maize. Qualitatively, these plants (except hop) could thus serve as refuges forO. nubilalis; however, they may be of little use quantitatively as they were found much less infested than maize.Sesamia nonagrioidespopulations on maize and sorghum reached comparable densities, but a slight genetic differentiation was detected between both. The degree of assortative mating between populations feeding on both hosts must therefore be assessed before sorghum can be considered as a suitable refuge for this species.
A Deubiquitinating Enzyme UBPY Regulates the Level of Protein Ubiquitination on Endosomes
Authors: Mizuno Emi , Kobayashi Kaoru , Yamamoto Akitsugu , Kitamura Naomi , Komada Masayuki
Published: June 2006

Monoubiquitination of endocytosed cell surface receptors serves as a sorting signal for their trafficking from endosomes to lysosomes. The sorting of ubiquitinated proteins is executed by concerted actions of class E vacuolar protein sorting (Vps) proteins. Some proteins in the sorting machinery undergo monoubiquitination, suggesting that their functions are also regulated by ubiquitination. The Hrs–STAM complex, a class E Vps protein complex essential for the initial step of the sorting pathway, binds two deubiquitinating enzymes, UBPY and AMSH. Here we examined the effects of inactivating UBPY on protein ubiquitination at endosomes. Overexpression of a catalytically inactive UBPY mutant or depletion of UBPY by RNA interference resulted in the accumulation of ubiquitinated proteins on morphologically aberrant endosomes. Electron microscopy showed that they are aggregates of multivesicular endosomes. Among the sorting machinery proteins that undergo ubiquitination, Eps15 was monoubiquitinated at an elevated level in UBPY‐inactivated cells. UBPY also deubiquitinated Eps15 in vitro, suggesting that Eps15 is a cellular substrate for UBPY. Furthermore, inactivation of UBPY caused the accumulation of Eps15 on the endosomal aggregates. These results suggest that UBPY regulates the level of protein ubiquitination on endosomes, which is required for maintaining the morphology of the organelle.
Does ecological filtering across a productivity gradient explain variation in species pool‐richness relationships?
Authors: R. Houseman Gregory , L. Gross Katherine
Published: June 2006

Concerns about the impact of species diversity loss has heightened the importance of determining what limits local diversity and the relative roles of the available species pool and local interactions. Recent theory suggests that local diversity may exhibit linear or asymptotic responses to regional variation in species pools depending resource supply rates. We tested this idea by augmenting species pools in three sites along a natural productivity gradient (a surrogate for resource supply) in a mid‐successional old‐field. Augmentation of the species pool, enhanced local diversity more at medium than low productivity sites in this field and seed addition had no effect at high productivity, suggesting that diversity was saturated in high resource areas of this field. These results suggest that resource supply rates may mediate species pool‐richness relationships. Species additions into cleared plots demonstrated that the observed differences in species recruitment along this gradient were largely driven by abiotic filtering at low and competitive filtering at high productivity. Furthermore, we observed that augmentation of the species pool shifted the productivity–diversity relationship from a negative linear to unimodal suggesting that species pools may influence reported productivity–diversity patterns.
Partitioning the effects of algal species identity and richness on benthic marine primary production
Authors: Bruno John F. , Lee Sarah C. , Kertesz Johanna S. , Carpenter Robert C. , Long Zachary T. , Emmett Duffy J.
Published: June 2006

Influential research in terrestrial habitats indicates that several ecosystem processes are related to plant biodiversity, yet these links remain poorly studied in marine ecosystems. We conducted one field and one mesocosm experiment to quantify the relative effects of macroalgal species identity and richness on primary production in coral reef macroalgal communities off the north coast of Jamaica. We measured production as the net accumulation of algal biomass in the absence of consumers and as photosynthetic rate using oxygen probes in sealed aquaria. We used two recently developed techniques to attribute deviations in expected relative yield to components associated with species identity or diversity and then to further partition diversity effects into mechanistic components based on dominance, trait‐dependent complementarity, and trait‐independent complementarity. Our results indicate that algal identity had far greater effects on absolute net growth and photosynthesis than richness. The most diverse mixture of macroalgae did not outperform the most productive monoculture or the average monoculture in either measure of primary production (i.e. we did not find evidence of either transgressive or non‐transgressive overyielding). Trait‐independent complementarity effects were positive but dominance and trait‐dependent complementarity were both negative and became stronger when richness was increased. Thus the potentially positive influence of species interactions and niche partitioning on production were negated by dominance and other negative selection effects. These results demonstrate that the counteracting influence of component effects can diminish the net richness effects on production. This could explain frequently observed weak net richness effects in other aquatic and terrestrial systems and suggests that life history tradeoffs greatly reduce the potential for ecologically relevant plant biodiversity effects on ecosystem properties.
Do generalized scaling laws exist for species abundance distribution in mountains?
Authors: Zhang Yuxin , Ma Keming , Anand Madhur , Fu Bojie
Published: June 2006

Knowing the global pattern of species diversity is a central goal of the science of ecology, and scaling laws can be useful for analysis of cross‐scale biodiversity patterns. An elevational gradient in a warm temperate zone of the Donglingshan mountains (China) is used to test the scaling laws of species abundance distribution using multifractal analysis. We show that the power law scaling relationship holds for not just the classical SAR (species–area relationship for richness), but also for Shannon and Simpson diversity. In fact, we find power‐laws in the generalized species abundance distribution at all stratal levels of the forest (trees, shrubs and herbs). The fact that these laws exist across a heterogeneous landscape representing a strong bioclimatic gradient suggests that biodiversity scaling laws may be more robust than previously thought.
On ecological fitting, plant–insect associations, herbivore host shifts, and host plant selection
Authors: Agosta Salvatoe J.
Published: June 2006

“Pests soon colonize plants that are cultivated extensively, plant species recruit different pest species in different regions, and associations of insects with plants are often more casual, fortuitous, and labile than those usually interpreted as coevolutionary.” (Strong 1979, pp. 89)

“… when a parasite arrives in a new habitat, it will feed on those species whose defense traits it can circumvent because of the abilities it carries at the time. Such a parasite cannot be distinguished from one that evolved the ability to circumvent a defense while in trophic contact with its host.” (Janzen 1980, pp. 611)

“We believe that a reasonable null hypothesis … is that many associations between insects and plants can occur without much evolution…” (Rey, McCoy and Strong 1981, pp. 620)

“The main role of secondary plant substances in insect/host plant relationships is that they form the ‘fingerprint’ … by which the insect recognizes the plants … The recognition of a plant as host is unrelated to whether the plant and the insect have evolved together or whether they meet for the first time in their evolutionary history.” (Jermy 1984, pp. 620)
The rapid response of plasma metabolites to changes in feeding rate in a small passerine Wilsonia pusilla
Authors: M. Zajac Ryan , J. Cerasale David , G. Guglielmo Christopher
Published: June 2006

In order to apply plasma metabolite profiling to assess the quality of stopover habitat for migrant birds it is crucial to know how quickly metabolite concentrations change in response to variation in energy intake rate. We fed live mealworms to Wilson's warblers Wilsonia pusilla at rates designed to mimic a low quality (0.58 wet g/h) and a high quality (0.75 wet g/h) habitat. Plasma concentrations of triglycerides and B‐OH‐butyrate were higher and lower, respectively, on the high feeding rate, but plasma glycerol levels did not differ between feeding rates. Birds were then fed at the low rate for five hours, switched to the high rate and blood sampled at various times after the switch. Plasma triglycerides and B‐OH‐butyrate reflected the increase in feeding rate within 10 and 20 min, respectively. Plasma glycerol did not change significantly following the change in feeding rate. We conclude that plasma metabolite concentrations can change very quickly in response to variation in feeding rate, and thus provide a sensitive index of fueling rates near a capture site.
A probabilistic model for the noise generated by breaking waves
Authors: Heitmeyer Richard M.
Published: June 2006

We present a probability law on both the noise field and the beam-noise time waveforms that is based on the assumption that the breaking-wave occurrences are described by a space-time Poisson process and that the breaking-wave waveforms are independent Gaussian processes. The probability law specifies the probability density of all orders in terms of its characteristic function, which is determined as a space-time integral of a functional involving the characteristic function of the contribution of an individual breaking wave. As an illustration, we present examples of the first-order probability density and the correlation function for a noise field observed on a vertical array operating in shallow water. It is seen that for the smaller elevation angles and for deep phones, where the energy is dominated by distant breaking waves, the observed noise waveforms are essentially Gaussian processes. Conversely, for beams pointed toward the surface and for shallow phones, where the noise is dominated by a small number of breaking waves, the noise wave forms are not Gaussian. Finally, we present a measure of the Gaussianity derived from an approximation to the characteristic function and apply it to identify the elevation angles and phone depths where the Gaussian approximation is not valid.
Processing unattended speech
Authors: Rivenez Marie , Darwin Christopher J. , Guillaume Anne
Published: June 2006

Three experiments examine the effect of a difference in fundamental frequency (F0) range between two simultaneous voices on the processing of unattended speech. Previous experiments have only found evidence for the processing of nominally unattended speech when it has consisted of isolated words which could have attracted the listener’s attention. A paradigm recently used by Dupoux et al. [J. Exp. Psychol.: Human Percept. Perform. 29(1), 172–184 (2003)] was modified so that participants had to detect a target word belonging to a specific category presented in a rapid list of words in the attended ear. In the unattended ear, concatenated sentences were presented, some containing a repetition prime presented just before a target word. Primes speeded category detection by 25ms when the two messages were in a difference F0 range. This priming effect was unaffected by whether the target was led to the left or the right ear, but disappeared when there was no F0 range difference between the messages. Finally, it was replicated when participants were compelled to focus on the attended message in order to perform a second task. The results demonstrate that repetition priming can be produced by words in unattended continuous speech provided that there is a difference in F0 range between the voices.
Time reversal operator decomposition with focused transmission and robustness to speckle noise: Application to microcalcification detection
Authors: Robert Jean-Luc , Burcher Michael , Cohen-Bacrie Claude , Fink Mathias
Published: June 2006

The decomposition of the time reversal operator (DORT) is a detection and focusing technique using an array of transmit-receive transducers. In the absence of noise and under certain conditions, the eigenvectors of the time reversal operator contain the focal laws to focus ideally on well-resolved scatterers even in the presence of strong aberration. This paper describes a new algorithm, FDORT, which uses focused transmission schemes to acquire the operator. It can be performed from medical scanner data. A mathematical derivation of this algorithm is given and it is compared with the conventional algorithm, both theoretically and with numerical experiments. In the presence of strong speckle signals, the DORT method usually fails. The influence of the speckle noise is explained and a solution based on FDORT is presented, that enables detection of targets in complex media. Finally, an algorithm for microcalcification detection is proposed. In-vivo results show the potential of these techniques.
First-order and zeroth-order head waves, their sequence, and implications for geoacoustic inversion
Authors: Choi Jee Woong , Dahl Peter H.
Published: June 2006

The relation between the head wave and an arrival often called a ground wave is analyzed with parabolic equation-based simulations, and an interpretation of such a ground wave as a head wave sequence is presented. For a Pekeris waveguide the envelope of the spectrum of the ground wave arrival corresponds to the spectrum of a single head wave, and spectral peaks correspond to odd multiples of the mode-1 cutoff frequency. This head wave is first order in its ray series classification and its amplitude spectrum goes as ∣S(f)∣∕f, where S(f) is the source amplitude spectrum. Basic variations from a Pekeris waveguide are considered; isospeed layers or a positive sound speed gradient in the seabed can each give rise to arrivals that are zeroth order in ray series classification and higher amplitude. For a sound speed gradient there is either a low-amplitude interference head wave whose properties are akin to a first-order head wave, or a high-amplitude interference head wave or non-interfering refracted wave whose properties are zeroth order and spectra follow ∣S(f)∣. Parametric dependences for distinguishing these arrivals and implications for geoacoustic inversion are discussed.
Geoacoustic inversion of broadband data by matched beam processing
Authors: Jiang Yongmin , Chapman N. Ross , DeFerrari Harry A.
Published: June 2006

This paper describes results of geoacoustic inversion using broadband signals from an experiment carried out at a site near the South Florida Ocean Measurement Centre in the Florida Straits. M-sequence coded pulse trains at different center carrier frequencies from 100to3200Hz were recorded at a vertical line array at a distance around 10km. Geoacoustic inversion was carried out to determine the feasibility of inverting the environmental parameters from this long-range propagation experiment. The received signal at lower frequencies below 400Hz consisted of a dominant water column signal and a secondary arrival delayed by 0.4s. The secondary signal was spatially filtered by beamforming the array data, and the beam data were inverted by matched beam processing in the time domain, combined with an adaptive simplex simulated annealing algorithm. The estimated values of compressional wave speed and density were in good agreement with ground truth values from sediment cores. The inverted shear wave speed appears to be a sensitive parameter and consistent with compressional wave speed. As a cross check, range and water depth were also included as inversion parameters, and the inversion results were close to the known values within small uncertainties.
Informational masking of speech in children: Auditory-visual integration
Authors: Wightman Frederic , Kistler Doris , Brungart Douglas
Published: June 2006

The focus of this study was the release from informational masking that could be obtained in a speech task by viewing a video of the target talker. A closed-set speech recognition paradigm was used to measure informational masking in 23 children (ages 6–16years) and 10 adults. An audio-only condition required attention to a monaural target speech message that was presented to the same ear with a time-synchronized distracter message. In an audiovisual condition, a synchronized video of the target talker was also presented to assess the release from informational masking that could be achieved by speechreading. Children required higher target/distracter ratios than adults to reach comparable performance levels in the audio-only condition, reflecting a greater extent of informational masking in these listeners. There was a monotonic age effect, such that even the children in the oldest age group (12–16.9years) demonstrated performance somewhat poorer than adults. Older children and adults improved significantly in the audiovisual condition, producing a release from informational masking of 15dB or more in some adult listeners. Audiovisual presentation produced no informational masking release for the youngest children. Across all ages, the benefit of a synchronized video was strongly associated with speechreading ability.
Evidence for attractors in English intonation
Authors: Braun Bettina , Kochanski Greg , Grabe Esther , Rosner Burton S.
Published: June 2006

Although the pitch of the human voice is continuously variable, some linguists contend that intonation in speech is restricted to a small, limited set of patterns. This claim is tested by asking subjects to mimic a block of 100 randomly generated intonation contours and then to imitate themselves in several successive sessions. The produced f0 contours gradually converge towards a limited set of distinct, previously recognized basic English intonation patterns. These patterns are “attractors” in the space of possible intonation English contours. The convergence does not occur immediately. Seven of the ten participants show continued convergence toward their attractors after the first iteration. Subjects retain and use information beyond phonological contrasts, suggesting that intonational phonology is not a complete description of their mental representation of intonation.
Broadband sound generation by confined pulsating jets in a mechanical model of the human larynx
Authors: Zhang Zhaoyan , Mongeau Luc G.
Published: June 2006

Experiments were performed to study the production of broadband sound in confined pulsating jets through orifices with a time-varying area. The goal was to better understand broadband sound generation at the human glottis during voicing. The broadband component was extracted from measured sound signals by the elimination of the periodic component through ensemble averaging. Comparisons were made between the probability density functions of the broadband sound in pulsating jets and of comparable stationary jets. The results indicate that the quasi-steady approximation may be valid for the broadband component when the turbulence is well established and the turbulence kinetic energy is comparatively large. A wavelet analysis of the broadband sound showed that random sound production was modulated at the driving frequency. Two distinct sound production peaks were observed during one cycle, presumably associated firstly with jet formation and secondly with flow deceleration during orifice closing. Most high-frequency sound was produced during the closing phase. Deviations from quasi-steady behavior were observed. As the driving frequency increased, sound production during the opening phase was reduced, possibly due to the shorter time available for turbulence to develop. These results may be useful for better quality voice synthesis.
The case of the missing delay lines: Synthetic delays obtained by cross-channel phase interaction
Authors: de Cheveigné Alain , Pressnitzer Daniel
Published: June 2006

Temporal models of pitch and harmonic segregation call for delays of up to 30ms to cover the full range of existence of musical pitch. To date there is little anatomical or physiological evidence for delays that long. We propose a mechanism by which delays may be synthesized from cross-channel phase interaction. Phases of adjacent cochlear filter channels are shifted by an amount proportional to frequency and then combined as a weighted sum to approximate a delay. Synthetic delays may be used by pitch perception models such as autocorrelation, segregation models such as harmonic cancellation, and binaural processing models to explain sensitivity to large interaural delays. The maximum duration of synthetic delays is limited by the duration of the impulse responses of cochlear filters, itself inversely proportional to cochlear filter bandwidth. Maximum delay is thus frequency dependent. This may explain the fact, puzzling for temporal pitch models such as autocorrelation, that pitch is more salient and easy to discriminate for complex tones that contain resolved partials.
Simulation of vocal fold impact pressures with a self-oscillating finite-element model
Authors: Tao Chao , Jiang Jack J. , Zhang Yu
Published: June 2006

Vocal fold impact pressures were studied using a self-oscillating finite-element model capable of simulating vocal fold vibration and airflow. The calculated airflow pressure is applied on the vocal fold as the driving force. The airflow region is then adjusted according to the calculated vocal fold displacement. The interaction between airflow and the vocal folds produces a self-oscillating solution. Lung pressures between 0.2 and 2.5kPa were used to drive this self-oscillating model. The spatial distribution of the impact pressure was studied. Studies revealed that the tissue collision during phonation produces a very large impact pressure which correlates with the lung pressure and glottal width. Larger lung pressure and a narrower glottal width increase the impact pressure. The impact pressure was found to be roughly the square root of lung pressure. In the inferior-superior direction, the maximum impact pressure is related to the narrowest glottis. In the anterior-posteriorfirection, the greatest impact pressure appears at the midpoint of the vocal fold. The match between our numerical simulations and clinical observations suggests that this self-oscillating finite-element model might be valuable for predicting mechanical trauma of the vocal folds.
Resonant solutions in wave phase conjugation induced by a limited magnetoacoustic conjugator
Authors: Merlen Alain , Zhang Qi
Published: June 2006

This paper presents, in one dimension, the general analytical solution of the acoustic phase conjugation in an active medium in contact with passive media of arbitrary impedance. The homogeneous case where no impedance jumps exist at the edge of the active zone is obtained as a particular case. This homogeneous case was the only one treated explicitly in the literature but mostly in the frame of Brillouin scattering. In contrast to this previous work, the present theory is based on a preliminary straightforward analysis using a dual-time-scale method and provides very practical results like the threshold of the supercritical modes, the rate of amplification, and its link with the stress repartition in the conjugator.
Ultrasonic evaluation of residual stresses in flat glass tempering: Comparing experimental investigation and numerical modeling
Authors: Duquennoy Marc , Devos Dany , Ouaftouh Mohammadi , Lochegnies Dominique , Roméro Eric
Published: June 2006

In order to control residual stress distribution in glass, techniques based on the phenomenon of photoelasticity are efficient, though subject to the inherent limitations of all optical techniques. To mitigate these limitations, we exploit the phenomenon of acoustoelasticity to estimate residual stress distribution, using surface acoustic waves. Experimental results are obtained for a 6mm thick soda-lime silicate flat glass plate that had been subjected to nonuniform thermal tempering and whose stress distribution is calculated using finite element modeling. The estimated stress distributions provided by our ultrasonic method compare quite well with the results from the modeling, from both the qualitative and quantitative points of view.
Finite element modeling of torsional wave modes along pipes with absorbing materials
Authors: Castaings Michel , Bacon Christophe
Published: June 2006

This paper describes the implementation of equations of dynamic equilibrium in a finite element (FE) code for modeling, in axisymmetry, the propagation of torsional wave modes along metallic pipes coupled to solid elements. Materials constituting either pipes and/or surrounding elements can be absorbing media, the absorption being caused by either their viscoelasticity or scattering on their internal structure (or both). Complex moduli are used as input data to equations of dynamic equilibrium, which are solved in the frequency domain rather than in the temporal domain. Their real and imaginary parts represent material elasticity and damping, respectively. A new definition of efficient and easy-to-implement absorbing regions that suppress undesired reflections from boundaries is proposed. The resolution of equations in the frequency domain, together with the use of absorbing regions, lead to significant reductions in the number of mesh elements and also in the number of iterations required for describing problems of propagation and scattering. Through two examples, the model is validated by successful comparisons of numerical predictions with experimental data. Then, a third example is presented to illustrate the importance of properly modeling waves damping when using FE models for setting-up or optimizing NDT techniques.
Experimental methods for investigating the acoustical interaction between transducers
Authors: Aronov Boris
Published: June 2006

Experimental methods for investigating the mutual radiation impedances in arrays are considered. One method, called the Z method, is based on measurements of the input impedance of the interacting transducers. The second method, called the V method, is based on measurements of the acoustomotive force generated on the surface of one of the transducers by an interacting transducer. This method can be used to investigate the mutual impedances between transducers at frequencies far below their resonant frequencies. Theoretical foundations for the methods are discussed and the experimental setups for implementing the methods are described.
The detection of increments and decrements is not facilitated by abrupt onsets or offsets
Authors: Plack Christopher J. , Gallun Frederick J. , Hafter Ervin R. , Raimond Andrew
Published: June 2006

Two experiments measured thresholds for the detection of increments and decrements in the intensity of a quasi-continuous broadband-noise (experiment 1) or increments in a 477-Hz pure-tone pedestal (experiment 2). A variety of onset and offset ramps for the intensity change were tested, from instantaneous onsets or offsets to ramps lasting several tens of milliseconds. For increments and decrements with equal duration, the characteristics of the ramps had little effect on performance. Abrupt rise times, which are associated with strong transient responses in auditory neurons, did not facilitate detection in comparison to much slower rise times. The temporal window model of temporal resolution provided a good account of the data when the decision statistic was the maximum magnitude of the change in the output of the window produced by the increment or decrement, but provided a poor account of the data when the decision statistic was the maximum rate of change in the output of the window over time. Overall the results suggest that, in the absence of cues in the audio-frequency domain, rapid changes in envelope contribute little to near-threshold increment or decrement detection.
Improving syllable identification by a preprocessing method reducing overlap-masking in reverberant environments
Authors: Hodoshima Nao , Arai Takayuki , Kusumoto Akiko , Kinoshita Keisuke
Published: June 2006

Overlap-masking degrades speech intelligibility in reverberation [R. H. Bolt and A. D. MacDonald, J. Acoust. Soc. Am. 21(6), 577–580 (1949)]. To reduce the effect of this degradation, steady-state suppression has been proposed as a preprocessing technique [Arai et al., Proc. Autumn Meet. Acoust. Soc. Jpn., 2001; Acoust. Sci. Tech. 23(8), 229–232 (2002)]. This technique automatically suppresses steady-state portions of speech that have more energy but are less crucial for speech perception. The present paper explores the effect of steady-state suppression on syllable identification preceded by /a/ under various reverberant conditions. In each of two perception experiments, stimuli were presented to 22 subjects with normal hearing. The stimuli consisted of mono-syllables in a carrier phrase with and without steady-state suppression and were presented under different reverberant conditions using artificial impulse responses. The results indicate that steady-state suppression statistically improves consonant identification for reverberation times of 0.7 to 1.2s. Analysis of confusion matrices shows that identification of voiced consonants, stop and nasal consonants, and bilabial, alveolar, and velar consonants were especially improved by steady-state suppression. The steady-state suppression is demonstrated to be an effective preprocessing method for improving syllable identification by reducing the effect of overlap-masking under specific reverberant conditions.
Frequency and form as determinants of functor sensitivity in English-acquiring infants
Authors: Shi Rushen , Cutler Anne , Werker Janet , Cruickshank Marisa
Published: June 2006

High-frequency functors are arguably among the earliest perceived word forms and may assist extraction of initial vocabulary items. Canadian 11- and 8-month-olds were familiarized to pseudo-nouns following either a high-frequency functor the or a low-frequency functor her versus phonetically similar mispronunciations of each, kuh and ler, and then tested for recognition of the pseudo-nouns. A preceding the (but not kuh, her, ler) facilitated extraction of the pseudo-nouns for 11-month-olds; the is thus well-specified in form for these infants. However, both the and kuh (but not her-ler) facilitated segmentation for 8-month-olds, suggesting an initial underspecified representation of high-frequency functors.
Passive correlation imaging of a buried scatterer
Authors: Larose Eric , Lobkis Oleg I. , Weaver Richard L.
Published: June 2006

Waveforms obtained by correlation of diffuse fields are now widely used to estimate times of flight and ballistic Green's functions. Theory, however, predicts that such passively obtained waveforms should equal the full Green function of a medium, and thereby convey information on the details of a structure and the presence of isolated scatterers. Here we investigate diffuse field correlations in a reverberant elastic body and demonstrate that their shear and Rayleigh waves allow us to image internal and surface features. Resolution in the resulting images is comparable to standard medical and seismic images.
Identification of multipole noise sources in low Mach number jets near the peak frequency
Authors: Suzuki Takao
Published: June 2006

A beam-forming algorithm is developed to identify noise source structures in low Mach number jets near the peak frequency. Pressure data from a conical phased microphone array are Fourier decomposed in the azimuthal direction, and the dominant eigenvectors of a cross-spectral matrix are extracted for each azimuthal mode; subsequently, a robust adaptive beam-forming technique is applied to a cross-spectral matrix reconstructed from the primary eigenmodes. The coherent sound signals are then decomposed into multipoles in spherical coordinates, and the primary mode and its axial position are identified for the axisymmetric and first two azimuthal modes. The proposed beam-forming algorithm is applied to an unheated round jet over a range of Mach numbers and frequencies. The result indicates that at low Mach numbers, the second zenithal mode (i.e., quadrupole) appears to be dominant for each azimuthal mode, and the source position slightly shifts downstream with increasing azimuthal mode number.
Amplitude modulation sensitivity as a mechanism for increment detection
Authors: Gallun Frederick J. , Hafter Ervin R.
Published: June 2006

Detectability of a tonal signal added to a tonal masker increases with increasing duration (“temporal integration”), up to some maximum duration. Initially assumed to be some form of energy integration over time, this phenomenon is now often described as the result of a statistical “multiple looks” process. For continuous maskers, listeners may also use a mechanism sensitive to changes in stimulus intensity, possibly a result of inherent sensitivity to amplitude modulation (AM). In order to examine this hypothesis, change detection was investigated in the presence of AM maskers presented at either the same carrier frequency as the target signal or at a distant frequency. The results are compatible with the hypothesis that listeners detect intensity increments by using change-detection mechanisms (modeled here as the outputs of a bank of modulation filters) sensitive to envelope modulation at both low (4–16Hz) and high (around 100Hz) rates. AM masking occurred even when the masker was at a carrier frequency more than two octaves above that of the signal to be detected. This finding is also compatible with the hypothesis that similar mechanisms underlie sensitivity to AM (where across-frequency masking is commonly shown) and detection of intensity increments.