bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of a Conserved Core Genome with Group‐Specific Genes from Comparative Genomics of Ten Different Candidatus Phytoplasma Strains
Authors: Wang Qiang , Guo Ya , Wang Nan , Li Yan , Chen Wang , Chen Wei , Wu Yunfeng
Published: February 2014

Plant pathogenic phytoplasmas can infect hundreds of plant species and lead to enormous economic loss. To understand the interactions between phytoplasmas and their hosts, genome sequencing plays an important role. To date, ten phytoplasma genomes from five phylogenetic groups have been released. A comparative genomics analysis showed 170 common conserved genes existing in these ten genomes. Genes involved in translation, ribosomal structure and biogenesis (75 genes) are the largest proportion. Interestingly, the predicted secreted proteins were not found in our core set, suggesting that these genes were diverse. In addition, a highly stringent strategy was taken to mine the group‐specific genes among the five groups. Although the largest part was the hypothetical proteins, some putative secreted proteins (potential effectors) were identified. TENGU was selected to be one of the 16SrI group‐specific genes. This may partly account for the diverse pathogenicity in different 16Sr groups. In addition, our results revealed that Amp and Imp had great potentials of being group specific. Above all, based on the conserved genes, our results provide new insights for the phytoplasma genome assembly, identification and functional genomics.
Protective effects of melatonin in reducing oxidative stress and in preserving the fluidity of biological membranes: a review
Authors: García Joaquín J. , López‐Pingarrón Laura , Almeida‐Souza Priscilla , Tres Alejandro , Escudero Pilar , García‐Gil Francisco A. , Tan Dun‐Xian , Reiter Russel J. , Ramírez Jose M. , Bernal‐Pérez Milagros
Published: February 2014

Free radicals generated within subcellular compartments damage macromolecules which lead to severe structural changes and functional alterations of cellular organelles. A manifestation of free radical injury to biological membranes is the process of lipid peroxidation, an autooxidative chain reaction in which polyunsaturated fatty acids in the membrane are the substrate. There is considerable evidence that damage to polyunsaturated fatty acids tends to reduce membrane fluidity. However, adequate levels of fluidity are essential for the proper functioning of biological membranes. Thus, there is considerable interest in antioxidant molecules which are able to stabilize membranes because of their protective effects against lipid peroxidation. Melatonin is an indoleamine that modulates a wide variety of endocrine, neural and immune functions. Over the last two decades, intensive research has proven this molecule, as well as its metabolites, to possess substantial antioxidant activity. In addition to their ability to scavenge several reactive oxygen and nitrogen species, melatonin increases the activity of the glutathione redox enzymes, that is, glutathione peroxidase and reductase, as well as other antioxidant enzymes. These beneficial effects of melatonin are more significant because of its small molecular size and its amphipathic behaviour, which facilitates ease of melatonin penetration into every subcellular compartment. In the present work, we review the current information related to the beneficial effects of melatonin in maintaining the fluidity of biological membranes against free radical attack, and further, we discuss its implications for ageing and disease.
Thinking beyond organism energy use: a trait‐based bioenergetic mechanistic approach for predictions of life history traits in marine organisms
Authors: Sarà Gianluca , Rinaldi Alessandro , Montalto Valeria
Published: February 2014

The functional trait‐based bioenergetic approach is emergent in many ecological spectra, from the conservation of natural resources to mitigation and adaptation strategies in a global climate change context. Such an approach relies on being able to exploit mechanistic rules to connect environmental human‐induced variability to functional traits (i.e. all those specific traits defining species in terms of their ecological roles) and use these to provide estimates of species life history traits (LH;e.g. body size, fecundity per life span, number of reproductive events).LHs are species‐specific and proximate determinants of population characteristics in a certain habitat. They represent the most valuable quantitative information to investigate how broad potential distributional boundaries of a species are, and to feed predictive population models. There is much to be found in the current literature that describes mechanistic functional trait‐based bioenergetics models, using them to test ecological hypotheses, but a mathematical framework often renders interpretation and use complicated. Here, we wanted to present a simpler interpretation and description of one of the most important recent mechanistic bioenergetic theories: the dynamic energy budget theory by Kooijman (Dynamic Energy Budget Theory for Metabolic Organisation, 2010, Cambridge University Press, Cambridge). Our main aim was to disentangle those aspects that at first reading may seem too mathematically challenging to many marine biologists, ecologists and environmental scientists, and present them for use in mechanistic applications.
Differential gene expression by Moniliophthora roreri while overcoming cacao tolerance in the field
Authors: Bailey Bryan A. , Melnick Rachel L. , Strem Mary D. , Crozier Jayne , Shao Jonathan , Sicher Richard , Phillips‐Mora Wilberth , Ali Shahin S. , Zhang Dapeng , Meinhardt Lyndel
Published: February 2014

Frosty pod rot (FPR) of Theobroma cacao (cacao) is caused by the hemibiotrophic fungus Moniliophthora roreri. Cacao clones tolerant to FPR are being planted throughout Central America. To determine whether M. roreri shows a differential molecular response during successful infections of tolerant clones, we collected field‐infected pods at all stages of symptomatology for two highly susceptible clones (Pound‐7 and CATIE‐1000) and three tolerant clones (UF‐273, CATIE‐R7 and CATIE‐R4). Metabolite analysis was carried out on clones Pound‐7, CATIE‐1000, CATIE‐R7 and CATIE‐R4. As FPR progressed, the concentrations of sugars in pods dropped, whereas the levels of trehalose and mannitol increased. Associations between symptoms and fungal loads and some organic and amino acid concentrations varied depending on the clone. RNA‐Seq analysis identified 873 M. roreri genes that were differentially expressed between clones, with the primary difference being whether the clone was susceptible or tolerant. Genes encoding transcription factors, heat shock proteins, transporters, enzymes modifying membranes or cell walls and metabolic enzymes, such as malate synthase and alternative oxidase, were differentially expressed. The differential expression between clones of 43 M. roreri genes was validated by real‐time quantitative reverse transcription polymerase chain reaction. The expression profiles of some genes were similar in susceptible and tolerant clones (other than CATIE‐R4) and varied with the biotrophic/necrotropic shift. Moniliophthora roreri genes associated with stress metabolism and responses to heat shock and anoxia were induced early in tolerant clones, their expression profiles resembling that of the necrotrophic phase. Moniliophthora roreri stress response genes, induced during the infection of tolerant clones, may benefit the fungus in overcoming cacao defense mechanisms.
Metabolic Syndrome Increases the Prevalence of Spine Osteoarthritis
Authors: Gandhi Rajiv , Woo Kenneth M , Zywiel Michael G , Rampersaud Y Raja
Published: February 2014

Objective

To determine whether the prevalence of severe spinal osteoarthritis (OA) increases with the number of metabolic syndrome (MetS) risk factors.

Methods

Data from a single surgeon's high volume, spine surgery practice were reviewed. Severe OA was defined as degenerative spondylolisthesis or cervical or lumbar stenosis causing neurologically based symptoms and early OA as lumbar and cervical spondylosis causing axial pain only. Logistic regression modeling was used to determine the odds (adjusted for age and sex) of having severe spine OA with more numerous MetS risk factors.

Results

Severe spinal OA was identified in 839/1502 patients (55.9%) and early OA in the remaining 663 individuals (44.1%). The overall prevalence of MetS was 30/1502 (2.0%): 26/839 (3.1%) in the severe OA group and 4/663 (0.6%) in the early OA group (P = 0.001). Presence of all four MetS risk factors was associated with almost quadruple the odds of having severe OA as compared with absence of risk factors (OR 3.9 [1.4–11.6], P < 0.01).

Conclusion

The components of MetS are more prevalent in subjects with severe spinal OA than in those with spondylosis causing axial pain. Future study of the association between MetS and the incidence of OA is required.
Vasovagal syncope and severe bradycardia following intranasal dexmedetomidine for pediatric procedural sedation
Authors: Patel Vinit J. , Ahmed Sheikh S. , Nitu Mara E. , Rigby Mark R.
Published: February 2014

We report syncope and bradycardia in an 11‐year‐old girl following administration of intranasal dexmedetomidine for sedation for a voiding cystourethrogram. Following successful completion of VCUG and a 60‐min recovery period, the patient's level of consciousness and vital signs returned to presedation levels. Upon leaving the sedation area, the patient collapsed, with no apparent inciting event. The patient quickly regained consciousness and no injury occurred. The primary abnormality found was persistent bradycardia, and she was admitted to the hospital for telemetric observation. The bradycardia lasted ~2 h, and further cardiac workup revealed no underlying abnormality. Unanticipated and previously unreported outcomes may be witnessed as we expand the use of certain sedatives to alternative routes of administration.
Dimerization of Resveratrol Induced by Red Light and Its Synergistic Analgesic Effects with Cobra Neurotoxin
Authors: Ye Yong , Fang Fei , Li Yue
Published: February 2014

Resveratrol polymer has better effects than monomer in some aspects as reported, but most of synthetic methods acquire severe conditions and no analgesic effects are investigated. A novel method is found to synthesize resveratrol polymer by excitation of photosensitizer pheophorbide at red light of 630 nm. The polymer was analyzed by fluorescence spectra and HPLC, further isolated by preparative liquid chromatography and identified as a resveratrol dimer by MS and NMR. Analgesic effects were measured by acetic acid writhing and hot‐plate test in mice. The resveratrol dimer has the stronger analgesic effects than monomer, and drug combination of the dimer and cobra neurotoxin enhances and prolongs analgesic effects, suggesting the synergistic action. Simulation of molecular interaction reveals that the dimer spontaneously binds to cobra neurotoxin and makes a complex substance. The dimer can interact with cyclooxygenase‐2, μ receptor and nicotine receptor, the synergistic analgesic effects of the complex are attributed to its multiple targets role. The combination of resveratrol dimer and cobra neurotoxin may make up for their deficiencies in analgesic effects, and has prospects in clinical use.
Resting and task‐elicited prefrontal EEG alpha asymmetry in depression: Support for the capability model
Authors: Stewart Jennifer L. , Coan James A. , Towers David N. , Allen John J. B.
Published: February 2014

The capability model of frontal electroencephalographic (EEG) asymmetry suggests that brain activity during emotional challenge will be a more powerful indicator of predispositions toward psychopathology than activity observed at rest. EEG data were assessed during a resting baseline and a facial emotion task, wherein individuals with (n = 143) and without (n = 163) lifetime major depressive disorder (MDD) made approach (angry and happy) and withdrawal (afraid and sad) facial expressions. EEG asymmetry during emotional challenge was a more powerful indicator of MDD status than resting asymmetry for average, Cz, and linked mastoid references, results in support of the capability model. However, current‐source‐density (CSD) transformed asymmetry was indicative of lifetime MDD status under resting and task‐elicited conditions. Findings suggest that CSD‐transformed data may be more robust indicators of trait frontal EEG asymmetry.
Exhaled breath condensate pH decreases during exercise‐induced bronchoconstriction
Authors: Bikov Andras , Galffy Gabriella , Tamasi Lilla , Bartusek Dora , Antus Balazs , Losonczy Gyorgy , Horvath Ildiko
Published: February 2014

Background and objective

Exercise‐induced bronchoconstriction (EIB) is the temporary narrowing of the airways caused by physical exercise. Its exact pathophysiology is unclear; however, acute changes in airways pH may play a role. Exhaled breath condensate (EBC) pH was suggested as a surrogate indicator for airway acid–base status, but its value is also affected by volatile molecules and respiratory droplet dilution. The aim of the study was to assess changes in EBC pH during EIB.

Methods

Twenty‐two asthmatics who reported breathlessness following exercise and 16 healthy individuals participated in the study. Lung function test was performed and exhaled breath samples were collected for pH, dilution factor and volatile compound pattern measurements (Cyranose 320) pre‐exercise and at 0, 10, 20 and 30 min after physical exercise challenge. Fractional exhaled nitric oxide was measured before exercise.

Results

EIB developed in 13 asthmatic subjects. In these participants, but not in the EIB‐negative asthmatics (P = 0.51), EBC pH reduced significantly during exercise (P = 0.01). In addition, changes in EBC pH were related to the degree of bronchospasm in the EIB‐positive group (P = 0.01, r = 0.68). Exhaled volatile pattern became altered (P < 0.05) during exercise in all subjects (asthmatics and controls). EBC pH changes were not related to EBC dilution or volatile compound pattern alterations (P > 0.05).

Conclusions

The development of EIB was related to acute changes of EBC pH, which suggest the role of airway pH decrease in the pathophysiology of EIB. Exercise‐induced changes in exhaled biomarkers suggest methodological precautions to avoid physical exercise before performing exhaled breath tests.
Measurement surveys of eight British concert halls
Authors: Richardson Russell , Shield Bridget M.
Published: February 2014

Objective measurement surveys and subjective surveys have been carried out in eight leading concert venues in the United Kingdom. In each hall a questionnaire survey of the whole audience at a concert of symphonic music was used to elicit the opinions of nonexpert listeners. Altogether over 3000 responses have been received. An objective survey of each (empty) hall has also been carried out, the parameters measured including reverberation time, early decay time, clarity index and definition. The number of measurement positions in each hall varied from 36 to 92. The questionnaire response data is to be correlated with the results of the objective measurements to investigate the relationship between objective data and the subjective impressions of nonexpert listeners. This paper will present summary data of the measurements in the eight halls and examine the variation in the values of the different parameters across each hall. The differences between the halls will also be considered. 2284,2284
Interaural cross-correlation: Sources of variability in concert halls
Authors: Madaras Gary S.
Published: February 2014

Impulse responses were measured inside multiple concert halls. Data analysis identified the level of the direct sound relative to the level of the architectural reflections as a significant source of IACC80 variability. Excluding the direct sound from the IACC80 integral durations (IACC80×DIR) significantly decreased the variability. The remaining variability seemed to relate to the arrival direction of the architectural reflections. A testing model capable of various configurations and a scale measurement method were developed. Models that had reflections approaching the receiver from the sides produced much lower IACC80×DIR values than those without reflections approaching the receiver from the sides. The various configurations of architectural elements (i.e., balconies and stage canopy) and surface treatments (i.e., diffusive and specular) affected IACC80×DIR values to a lesser extent than altering the arrival direction of the architectural reflections. It was concluded that the general direction from which the architectural reflections arrive and the finish of the architectural surfaces are both sources of IACC80×DIR variability (the former having a much greater effect). It was also concluded that unless the direct sound is excluded from the integral duration, variability of interaural cross-correlation values does not relate as strongly to the arrival direction of the architectural reflections. [Work supported by the Concert Hall Research Group and the University of Florida.]
Multibeam sonars: Applications for fisheries research
Authors: Mayer Larry A. , Li Yanchao , Melvin Gary
Published: February 2014

Multibeam sonars are rapidly becoming a standard tool for seafloor mapping in support of geological, geophysical, and engineering applications. More recently, the ability of multibeam sonars to provide high-resolution, large areal coverage, and potentially quantitative, coregistered, backscatter has been applied very successfully to problems of defining fisheries habitat. While most multibeam sonars are designed to gate out all midwater returns, newly developed systems now allow access to the full data stream and thus offer the possibility of application to studies of pelagic and demersal fisheries. Traditional acoustic approaches to fisheries issues have used single beam echo sounders that sample a relatively small volume of the water column within a survey area. Multibeam sonars provide a mechanism to greatly enhance both the resolution and the area of coverage. When combined with powerful new 3-D visualization techniques, they can offer immediate feedback on fish behavior as well as the critical question of vessel avoidance. If properly calibrated, multibeam sonars can provide the means for much more robust assessment of stock levels and perhaps even species identification.
Physical constraints in sonar design
Authors: Atkins Philip R. , Collins Tim
Published: February 2014

The dynamic range and processing gains achievable within a simple passive sonar will be reviewed. It will be demonstrated that the constraints of modern electronic hardware components do not necessarily limit the performance of a passive sonar system when compared with the physical constraints of the acoustic channel. By contrast it will be demonstrated that the pulse design of an active sonar places significant limitations on the capability of the system. For example, range resolution, Doppler resolution, range sidelobes, ambiguities and reverberation performance all depend on the design of the sonar transmission. Techniques available to the designer for suppressing range sidelobes and pulse designs with both range and Doppler sensitivity will be reviewed. The constraints imposed by the transducer will be considered, particularly in relationship to ultrahigh range resolution capabilities. Finally, a comparison between an early 1960s sonar and a modern equivalent will be made in terms of performance, power consumption and size.
A hybrid numerical model to predict the effect of buried objects on the acoustic-to-seismic coupling on ground surfaces
Authors: Taherzadeh Shahram
Published: February 2014

A numerical model based on a hybrid boundary integral equation/wave number integration is presented and is used to predict the influence of rigid objects buried within a layered, porous elastic soil upon excitation of the ground surface induced by an airborne sound source. Recently, acoustic-to-seismic coupling phenomena have been used successfully to detect buried landmines [J. Sabatier and N. Xiang, J. Acoust. Soc. Am. 106, 2143 (1999), 107, 2896 (2000)]. If a ground surface is subjected to insonification, the sound wave penetrates the ground and is reflected and refracted from the topsoil layers, resulting in complex acoustic-to-seismic spectra. The presence of an object alters these spectra by scattering and/or enhancing certain vibrational modes. The model will be applied to predict these changes in the presence of buried landmines. a)Permanent address: Faculty of Technology, The Open Univ., Milton Keynes, UK.
Loudness-independent cues to object striking force
Authors: Lakatos Stephen , Beauchamp James W.
Published: February 2014

To what degree can listeners rely on auditory cues besides loudness to correctly judge the striking forces used to excite an object? Listening experiments used a discrimination task to assess whether individuals could correctly map loudness relations onto striking forces for stimuli derived from tam–tam, tympani, and xylophone-bar recordings. On each trial, listeners heard two sound pairs representing an instrument struck with differing strike forces using a mallet; one pair had its loudness relations intact while the other had its loudness relations inverted. Listeners determined which pair preserved its correct loudness relations. Both striking force and mallet properties served as independent variables. Discrimination varied in general with the extent to which the mallet and striking force excited the characteristic vibrational modes of the instruments: the more acoustic modes available, the higher the discrimination performance. Discrimination was significantly poorer for instruments with fewer acoustic cues generated by such modes, like the xylophone, than it was for instruments with a rich set of cues, like the tam–tam. Mallet density and weight were also important factors in modulating discrimination. The results indicate source-based cues besides loudness can convey information about striking force, albeit with less effectiveness. [Research supported by Air Force Grant F49620-99-1-0293.]
Effects of instructions to produce hyperarticulated vowels on formant values
Authors: Pouplier Marianne , Whalen D. H.
Published: February 2014

Clear speech collected in the laboratory is typically well articulated, but speakers can produce even clearer speech (‘‘hyperarticulated’’) when so instructed. Johnson et al. [Language 69, 505–528 (1993)] found that hyperarticulations, averaged across speakers, are more extreme in both the F1 and F2 dimension. Here, 10 speakers of a Rhode Island dialect of English recorded words with 11 different vowels in (h)Vd environments (e.g., ‘‘heed,’’ ‘‘aid’’). Individuals show the effect for between 2 and 9 vowels; there was no vowel that had more extreme formant values (for F1 or F2) for all 10 speakers. (Averaged across talkers, only the low front vowel had more extreme values in both F1 and F2.) Typically, hyperarticulations that were not more extreme in formant values were equivalent to the normal production, while a few had less extreme values. The lack of consistency in the individual results calls into question the use averaged values, since speakers may be changing articulatory parameters in a more complex way. The dynamic nature of some of the vowels may have an influence, since the initial measurements were taken from a single point in the syllable. [Work supported by NIH.]
On trading relations in vowel production: An x-ray microbeam study
Authors: Slama Angela , Weismer Gary
Published: February 2014

The purpose of this study was to investigate the articulatory and acoustic variability in vowel production, across 52 normal speakers of English. Specific to that variability, the notion of trading relations was addressed. In a study by Perkell et al. (1993), trading relations describes the complementary nature by which two different articulatory mechanisms are employed by a single speaker, when producing a given speech sound. Perkell and colleagues found weak, negative correlations within three out of four speakers, for the tongue-raising and lip-rounding mechanisms used to produce the English vowel /u/. These findings suggest that within a given speaker, the two primary articulatory mechanisms used to produce /u/ may be traded, or used in a complementary fashion, to constrain the acoustic variability of the vowel. In the current experiment, kinematic and acoustic measurements were used to explore the possibility of the same kinds of trading relations across speakers. The specific question asked was, do speakers who demonstrate large amounts of lip rounding for the vowel /u/, also use small amounts of tongue backing and/or rounding, and vice versa? Interspeaker variability for the acoustic and kinematic measures will be evaluated and discussed relative to this question. [Work supported by NIH No. DC03274.]
Male and female vowels identified by visual inspection of raw complex waveforms
Authors: Stokes Michael A.
Published: February 2014

A perceptual experiment involving visual identification of the raw complex waveforms of American English vowels from two male speakers was presented at the 131st meeting of Acoustical Society of America (Stokes, 1996). In that study, a subject correctly identified five out of nine vowels for both male speakers using only a visual presentation of the raw complex waveforms. The present study replicates those earlier results with the same subject correctly identifying four out of nine vowels and six out of nine vowels for two new male speakers. Furthermore, four out of nine vowels produced by a female speaker were correctly identified. These results demonstrate that the visual cues being used for vowel identification can be applied across genders, in addition to extending the work from 1996 to now show successful visual identification of vowels across four male talkers using only raw complex waveform displays. These results will be discussed, including an analysis of the errors made by the subject. A description of the visual cues and the new model of vowel perception and production that resulted from these cues can be found at http://www.indy.net/∼masmodel.
Exploring the ‘‘hyperspace’’ effect in vowel perception
Authors: Whalen D. H. , Magen Harriet
Published: February 2014

When using the method of adjustment to choose the best representative of an English vowel in an F1 by F2 space, listeners have been found to select formant values more extreme than those they actually produce [Johnson et al., Language 69, 505–528 (1993)]. This preference for ‘‘hyperspace’’ targets (those beyond actual productions) is argued to indicate a phonetic target more extreme than the subjects’ actual hyperarticulations. The same methodology was used with 10 Rhode Island subjects. They produced vowels under two conditions, citation and then (after the perceptual task) hyperarticulated speech. Perception was assessed with a grid of 298 F1/F2 combinations from which listeners chose the best match for a keyword’s vowel. Females and males were nearly equivalent in perception, as assumed previously but not shown. However, only one vowel was clearly extreme in both formants, with seven other vowels being more extreme on one formant, two vowels showing hypoarticulation, and the final one showing no effect. This lack of a robust effect may be due to difficulty of using F2 in perceiving the synthetic vowels. It may also be that the listeners were selecting perceptual targets from a more neutral dialetic than their own. [Work supported by NIH.]
Acoustic properties underlying vowel intelligibility in words with mixed consonantal contexts
Authors: Hargus Ferguson Sarah , Kewley-Port Diane , Brown Aaron P.
Published: February 2014

This study explored the relative importance of spectral target, dynamic formant, and duration information to vowel identification in mixed consonantal contexts. Vowel intelligibility was varied naturally by one talker producing test words in sentences using clear and conversational speech. In /bVd/ context only, vowels identified by normal-hearing listeners in noise were significantly more intelligible (15%) in clear speech than in conversational speech. Clear and conversational tokens of the 10 vowels also differed significantly on several spectral and temporal measures. Regression analyses revealed that intelligibility differences for individual vowels were well predicted by various combinations of spectral target, dynamic formant, and duration metrics [S. H. Ferguson and D. Kewley-Port, J. Acoust. Soc. Am. 106, 2272 (1999)]. A second data set was collected concurrently with the /bVd/ data, with the same listeners identifying vowels in mixed CVC contexts. A significant intelligibility advantage (18%) for clear speech was found for these materials. However, regression analyses were less straightforward for vowels in CVC context than in /bVd/ context. Several acoustic metrics were investigated to determine whether intelligibility differences could be modeled for vowels in mixed consonantal contexts. The results will be discussed in terms of theories of vowel perception. [Work supported by NIHDCD-02229, the American Speech-Language-Hearing Foundation, and NIHDCD-00012.]
Influence of /r/ on burst spectra for stop place
Authors: Hodge Megan M. , Hegedus Janka , Kenny Megan , Souster Carmen
Published: February 2014

Bilabial and lingua-alveolar stops in 20 minimally contrastive word pairs in both singleton and stop /r/ (cluster) contexts were recorded from two girls, one with facial paralysis (CFP) and one with normal facial movement (CNM). Auditory identification of these productions by 12 listeners revealed a significant place by context interaction for CFP. Identification scores were high for her lingua-alveolar stops (99.3% singletons; 94.8% clusters). Identification scores for her bilabial stops were lower, with singletons being significantly lower (57.8%) than clusters (77.8%). Acoustic cues for stop place (F2 onset frequency, VOT, mean and skewness of burst spectra) were measured for all word productions. For both girls, F2 onset and VOT measures were lower for bilabial than lingua alveolar stops in singletons and clusters. CFP’s burst spectra for bilabials had a higher mean and more negative skewness than lingua alveolars in singletons and clusters. CNM’s burst spectra for bilabials had a lower mean and more positive skewness than lingua alveolars in singletons (expected) but a higher mean and more negative skewness for bilabials than lingua alveolars in clusters (unexpected). This unexpected finding may account for CFP’s higher identification rates for bilabial clusters (all acoustic cues ‘‘fit’’ those of a child with normal facial movement).
Evaluating vowel normalization transformations through generalized linear modeling
Authors: Adank Patti , Smits Roel
Published: February 2014

Nearey [ICSLP (1992)] suggests using generalized linear modeling (GLM) to investigate the role of vowel-intrinsic (e.g., role of F0) and vowel-extrinsic (e.g., z-transformation, log-mean transformation) normalization schemes. A generalized linear model consists of two parts: a linear predictor and a nonlinear link function. GLM is used to predict values both for dependent variables with discrete distributions and for variables that are nonlinearly related to the predictors. GLM can therefore be useful for dealing with relations between vowel-intrinsic and vowel-extrinsic information and vowel categories, since intrinsic factors can be tested as predictors in the linear predictor function and extrinsic factors can be tested using the link function. The GLM approach was applied to speech data from 80 speakers from four different regions in The Netherlands. The regional accent spoken in each group was different from the other three groups. The nine monophthong vowels of Dutch were produced in a neutral context. For each vowel, F0 and F1–F3 were measured. These values were transformed according to several vowel normalization schemes. The coefficients for the normalizations were estimated through maximum likelihood estimation. Overall, the results indicate that GLM can be a useful tool for evaluating normalization transformations.
Identification of Swedish vowel quantity by pre-adults
Authors: Behne Dawn M. , Czigler Peter E. , Sullivan Kirk P. H.
Published: February 2014

Research on the perception of Swedish vowel quantity by adult native listeners shows that vowel duration is a primary cue for identifying vowel quantity. However, when a vowel has a relatively long duration (e.g., due to its inherent duration, or its context), adult listeners may make use of both duration and spectra to identify vowel quantity. Use of the vowel spectrum in these special cases might be seen as the result of perceptual fine tuning to improve the processing efficiency in vowel identification. If so, we would expect a developmental change in how children use vowel duration and spectra to identify vowel quantity, with the use of vowel spectra as a cue coming relatively late. This investigation examines how young native listeners, from 9 to 15 years old, use vowel duration and F1-F2 to identify Swedish vowel quantities. For each of three vowel types, 100 /kVt/ words were resynthesized with ten degrees of vowel duration and ten degrees of F1 and F2 adjustment. Each child responded to a subset of these in a rhyming task. Results show a late developing ability to identify vowel quantity and trace the use of vowel duration and F1-F2 as perceptual cues to vowel quantity.
The acoustics of gestural overlap
Authors: Iskarous Khalil
Published: February 2014

Acoustic modeling of speech production focuses on the effects of a single tongue constriction and a simultaneous labial constriction on the formant frequencies of an acoustic tube. But research on dynamic speech production reveals that tongue gestures overlap in time, so two or more simultaneous tongue constrictions affect the acoustic output of the tube. Understanding the acoustics of natural speech therefore requires an investigation of the acoustic effects of multiple constrictions. The goal is to generate a generalized formant nomogram that would reveal how the acoustic effects of single constrictions combine and interact in determining the acoustic output of the whole tract. Results will be presented from a finite element simulation of the acoustic effects of two constrictions that vary independently in location and size. The location of each constriction varied in 34 steps and the size varied in 16 steps. Independent variation of the two constrictions yields 295936 constriction combinations. The function relating the acoustic output of the multiply constricted tract to the acoustic effects of each of the constrictions when made alone is generally nonlinear. Several features of this function will be discussed, and conditions for its linearization will also be presented. [Work supported by NIH.]
Spectral tilt versus formant frequency in static and dynamic vowels
Authors: Kiefte Michael , Kluender Keith R.
Published: February 2014

The relative importance of gross (e.g., spectral tilt) versus detailed (e.g., formant peak frequencies) for speech perception is an enduring question of substantial importance in understanding performance of both impaired and unimpaired listeners [cf. Kiefte, J. Acoust. Soc. Am. (submitted)]. In this study, subjects were presented with steady-state stimuli varying perceptually between [i] and [u] for which spectral tilt and formant frequencies were fully crossed. Results show an effect for both tilt and formants indicating some perceptual importance for both in the identification of statically specified vowels. However, this result does not appear to extend to more natural sounding stimuli with dynamic formants. For example, there was no effect for spectral tilt in a similar experiment using diphthongs ranging from [ai] to [au]. One hypothesis for this difference is that the F2 of front vowels is masked by F1 when combined with sharply falling spectral tilt and that this effect is mitigated in dynamic or naturally produced vowels. Results are also presented which compare the perception of these continua with similar stimuli in which F2 is absent as well as with dichotically presented stimuli in which F1 and F2 are heard in different ears. [Work supported by NIDCD DC04072.]
Dynamic information in the perception and production of Rhode Island vowels
Authors: Magen Harriet , Iskarous Khalil
Published: February 2014

Comparisons were made of the production and perception of 11 vowels for 10 Rhode Island speakers. To assess perception, the method of adjustment (MOA) was used. Subjects were presented with a grid of 298 steady state F1/F2 combinations and asked to choose the best match to a visually presented keyword. [Johnson et al., Language 69, 505–528 (1993)]. The same subjects produced the 11 vowels; acoustic measurements were made 1/3 of the way through. For two pairs of vowels ([eI]-[I], [ɔ]-[oU]) there was a disparity between production and perception, calling into question the perceptual strategy listeners use when normally present dynamic information is absent. To address the issue of the dynamics of production, measurements were made at additional points. At all three points measured, values of F1 of [eI] and [I] overlap substantially; however, perceptually they are distinct. While this dialect maintains the [ɑ]-[ɔ] distinction, [ɔ] and [oU] show overlap in production early in the vowel, diverging later in the vowel; static formant values chosen as the best instance of [oU] overlapped with the formants of producted [ɔ]. The efficacy of the MOA for dynamic information will be discussed. [Work supported by NIH and the RIC Faculty Research Fund.]
Improved detection using propagation and target responses
Authors: Gaumond Charles F. , Baer Ralph N.
Published: February 2014

The detection results of a monostatic sonar simulation are presented. The bandwidth of the simulation is 200 Hz to 950 Hz and the environment is range-independent, shallow water. A target is modeled as a point with a frequency-dependent response simulated using a finite element model and the propagation is simulated using the RAM PE model. These two broadband simulation results are combined using a coherent form of the sonar equation. The improvement of detection is shown for several cases comparing the use of environment-alone, target-alone, and combined-environment-target matched filters with the detection from the use of simple matched filtering. [Research sponsored by ONR.]
Effective analysis technique of unstable acoustic signature from ship radiated noise
Authors: Yoon Jong-rak , Ro Yong-ju , Chun Jae-Jin
Published: February 2014

Acoustic signatures of ship radiated noise are important passive sonar parameters in target ship detection and classification. Among these signatures an unstable signature, which is defined as frequency change with respect to the time or frequency modulation, is due to the external loading variation in specific machinery components. As an example, propeller blade frequency is measured as an unstable signature and is controlled by the speed governor which is dependent on the propeller resistance to sea surface waves or current turbulence. In this study an extended Kalman filtering algorithm is applied to detect the unstable signature. To obtain better performance than with the existing similar technique, state model parameters such as variance and bandwidth are expressed as a function of the sea state wave spectrum. In addition background noise variance in the measurement model is also defined as a sea state function. Its performance is evaluated using measured surface ship radiated noise data and it is also applied to Dopplerized signal analysis which is essential in moving target monitoring. [Work supported by the Underwater Acoustics Research Center.]
Characterization of the left/right bearing ambiguities for passive line arrays
Authors: Boyle Frank A. , Grant David E.
Published: February 2014

The symmetry of a straight horizontal line array produces a left/right bearing ambiguity that makes it impossible to determine on which side of the array a source is located. A simple technique for resolving left/right ambiguities is to break the symmetry by curving the array. Under certain common conditions, however, significantly curved arrays still possess left/right ambiguities that depend on the source’s range and the beamformer’s focal length. These ambiguities can be modeled, given a source and array configuration, to produce a prediction of source localization capability. Comparisons with actual data were generally consistent with modeled results in the cases considered. The presentation will include a description of how the ambiguities are modeled, and a comparison between modeled and experimental results. Considerations on how curved arrays can be configured to minimize ambiguities will also be discussed.
Finding the right cross-correlation peak for locating sounds in multipath environments with a fourth-moment function
Authors: Spiesberger John L.
Published: February 2014

To locate calling animals in reverberant environments from recordings on widely separated receivers, a fourth moment ‘‘augmented-template correlation function’’ (ATCF) helps identify which of many peaks in each cross-correlation function is that corresponding to the difference in travel times for the first arrivals (reference-lag). This peak may not be the largest. The ATCF, by providing an approximate correlation between auto- and cross-correlation functions, can be orders of magnitude more efficient in selecting the reference-lag than the alternative of randomly selecting peaks. The ATCF’s efficacy increases with the number of paths and their signal-to-noise ratios. [Work supported by ONR.]
Wavefront scatter and wavefront healing
Authors: Feuillade C.
Published: February 2014

While acoustic scattering is essentially a time domain phenomenon, studies of scattering from objects in water, and from boundaries, have often concentrated on time-independent/cw descriptions. There are, however, critical aspects of the scattering problem which become evident only in the time domain. In this paper, time-domain visualizations of impulse scattering from rigid, pressure-release, fluid, and elastic spheres are presented. The results provide important insights into the physical processes which lead to the construction of scattered wavefronts. Using this method, it is possible to time-separate and identify different scattering mechanisms: geometrical scatter; diffraction (which, for rigid spheres, gives rise to the circumferential wave); refraction; and wave conversion in the body of the scattering obstacle. Of particular interest is the characterization of the forward scatter region, where the process of wavefront healing can be directly observed. The presentation will be illustrated by movie animations. [Work supported by ONR.]
A two-way coupled mode method, matrix methods, and bandedness of the integration with free scattering solutions and the solution of imbedded objects in a waveguide
Authors: Werby M. F.
Published: February 2014

Since the seminal work of Richard Evans in 1983 when he proved to the world the viability of a two-wave general waveguide solution in coupled mode form his method and implementation has been the gold standard of other range-dependent approximations. The method by its very nature is tedious to implement and requires much time in computation. Often a one-way solution is adequate allowing many to circumvent this more complicated solution. A one-way coupled mode method has been developed at NRL that takes advantage of representation theory in terms of a basis set that leads to analytical forms suitable for use in representing incident fields as input for scattering problems. It is apparent that in many cases the addition of an inclusion renders coupling in both directions in a waveguide and thus the one-way approach is extended to a two-way coupled mode solution and by extension to a generalization of the integrated solution of an object in a waveguide for more general inclusions.
Theory and computation for small-slope scattering from rough elastic ocean floors
Authors: Gragg Robert F. , Wurmser Daniel
Published: February 2014

A bistatic theory is presented for the scattering strength of a random rough interface bounding a uniform medium (either fluid or elastic solid) for cases where the Bragg scale lies within the power-law tail of the roughness spectrum. The physical basis is an inherently reciprocity-preserving, local small-slope theory. A robust numerical implementation is also presented that functions smoothly throughout a wide range of spectral exponents (from 2.4–3.9, at least). The practical result is a significantly improved formulation for the interface component of sea floor scattering. Results are compared to those of perturbation theory, and illustrate the dependence on frequency, environmental parameters, and bistatic geometry. Validation of the model using at-sea data is addressed by Soukup [R. J. Soukup, J. Acoust. Soc. Am. (submitted)]. [Work supported by ONR.]
Acoustic scattering from bubbly cylinders and spheres
Authors: Wilson Preston S. , McCormick Ryan D. , Roy Ronald A. , Carey William M.
Published: February 2014

This presentation deals with acoustic scattering from bubble clouds. In the most general manifestation, the cloud has arbitrary shape and extent and consists of a population of bubbles with arbitrary size distribution; the ensuing scattering problem is considerable. In the asymptotic limit of an acoustically compact cloud consisting of acoustically small bubbles (both conditions are satisfied at sufficiently low frequencies) the situation condenses down to the much simpler problem of scattering from a uniform compressible object, and to lowest order in the Helmholtz number (ka) this object is a sphere. Experimental evidence supporting this approximation was obtained at Lake Seneca [Roy et al., J. Acoust. Soc. Am. 92, 2993 (1992)], as well as numerous laboratory noise and scattering experiments that followed. We present additional data that supports this view, and extends it to higher order in ka for the case of scattering from a cylindrical bubble cloud. Data obtained at the NUWC underwater test facility details the frequency-dependent scattering from well-characterized bubbly cylinders, and a good match to data is obtained using an effective medium model for the uniform compressible cylinder. Accompanying scattering data from two types of bubbly spheres (voided polyurethane, gel-filled) are also presented. [Work supported by ONR.]
Linear acoustics in bubbly liquids from an effective medium theory
Authors: Kargl Steven G.
Published: February 2014

Proposed corrections to the lowest-order approximation of an effective wave number obtained from Foldy’s exact multiple scattering theory [Foldy, Phys. Rev. 67, 107 (1945)] has sparked renewed interest in linear wave propagation through bubbly liquids. An alternative approach to wave propagation through a bubbly liquid reduces the governing equations for a two-phase medium to an effective medium. Commander and Prosperetti [J. Acoust. Soc. Am. 85, 732 (1989)], based on this method, derive an expression for the lowest-order approximation to an effective wave number. At this level of approximation the bubbles interact with the mean acoustic field without higher-order rescattering. That is, the field scattered from a bubble may interact with one or more new bubbles in the distribution, but a portion of that scattered field may not be scattered back to any previous bubble. Simple modifications to the results of Commander and Prosperetti lead to a new expression for the effective wave number, which properly accounts for all higher orders of multiple scattering. [Work supported by ONR, Code 321OA.]