bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of spatial configuration in a divided attention task
Authors: Best Virginia , Ihlefeld Antje , Shinn-Cunningham Barbara
Published: October 2013

The effect of spatial separation on the ability of listeners to report keywords from two simultaneous talkers was examined. The talkers were presented with equal intensity at a clearly audible level, but were processed to minimize their spectral overlap and reduce energetic interference. The two talkers were presented with various angular separations around references of −45°, 0°, or 45° azimuth. Overall, performance did not vary dramatically with spatial configuration, but depended on spatial separation and reference direction. With the talkers in front or to the left, performance tended to first increase and then decrease with increasing separation. With both talkers to the right, performance tended to improve monotonically with increasing separation. The relative levels of the two talkers at each ear in each configuration partially accounted for results. For each talker a different ear contained a signal-to-noise ratio advantage, and performance was positively correlated with the mean signal-to-noise ratio across the two ‘‘better ears.’’ Thus, when tracking two sources simultaneously, listeners may make use of the information at the two ears independently. Furthermore, the drop in performance for some large talker separations may reflect increased difficulty in following sources that do not fall within a single ‘‘spotlight’’ of spatial attention.
Auditory nerve response to broadband noise with high-frequency spectral notches
Authors: Alves-Pinto Ana , Lopez-Poveda Enrique A. , Palmer Alan R.
Published: October 2013

The threshold notch depth for discriminating between a flat-spectrum broadband noise and a similar noise with a rectangular spectral notch centered at 8 kHz varies nonmonotonically with stimulus level (Alves-Pinto and Lopez-Poveda, submitted to J. Acoust. Soc. Am.). A possible explanation for this result is that the notch may be encoded in the rate profile of auditory nerve (AN) fibers with high spontaneous rate (HSR) at low levels and in that of low spontaneous rate (LSR) fibers at high levels. To test this hypothesis, the rate profile of guinea pig AN fibers was measured in response to broadband notched noise for different notch depths and widths and for overall levels ranging from 40 to 100 dB SPL. Preliminary results support the hypothesis that HSR fibers can encode the spectral notch only for levels up to around 70 dB SPL. However, they also suggest that, as in the psychophysics, the negative effect of level is less pronounced the wider the notch. Additional data are required to confirm the role of LSR fibers to encode for the notch at higher levels. [Work supported by Spanish FIS PI020343 and G03/203.]
Multiple auditory steady-state response (ASSR) thresholds to bone-conduction stimuli in young infants with normal hearing
Authors: Small Susan A. , Hatton Jennifer , Stapells David R.
Published: October 2013

Bone-conduction ASSR thresholds (carrier frequencies: 500–4000 Hz; 77–101-Hz modulation rates; amplitude/frequency modulated; single-polarity stimulus) were obtained in two infant groups (N=29 pre-term, tested in NICU; N=14 0-to-8 months of age, tested in soundbooth). Mean (1SD) ASSR thresholds were 16 (11), 16 (10), 37 (10), and 33 (13) dBHL in pre-term infants and 14 (13), 2 (7), 26 (6), and 22 (8) dBHL in older infants at 500, 1000, 2000, and 4000 Hz, respectively. Both infant groups had significantly better thresholds for 500 and 1000 Hz compared to 2000 and 4000 Hz, in contrast to adults who have similar thresholds across frequency (22, 26, 18, and 18 dBHL) [Small and Stapells, J. Am. Acad. Audiol (in press)]. When 500- and 1000-Hz thresholds were pooled, NICU infants and 0–8-month-old infants tended to have better low-frequency thresholds than adults. When 2000- and 4000-Hz thresholds were pooled, NICU and 0–8 month-old infants tended to have poorer thresholds than adults. Overall, these results suggest that low-frequency bone-conduction thresholds worsen and high-frequency bone-conduction thresholds improve with maturation. [Work supported by CIHR and NSERC Canada.]
Human electrophysiological examination of the buildup of the precedence effect (Clifton effect)
Authors: Dimitrijevic Andrew , Stapells David R.
Published: October 2013

The relationship between behavioral measures of buildup of precedence effect [or Clifton effect (CE)] and electrophysiological responses using an event-related potential (ERP) paradigm was examined in 14 young adults with normal hearing. The CE was elicited using a binaural paired-click (left and right speaker delay) in sound field. This study aimed to determine whether ERP measures were related to the perception of buildup. Subjects participated in two sessions: (i) Session ♯1 psychoacoustic measures of the degree of buildup as function of click delay (left and right side). (ii) Session ♯2 recorded cortical ERPs using click delays (varying from 6 to 8 ms) that would maximize the degree of buildup in each subject. Stimuli consisted of repeated trains containing 5 paired-clicks (left speaker leading) with a noise burst separating consecutive trains. Results: Significant N1 amplitude hemispheric asymmetries were observed related to click position. N1 responses decreased (43%) as a function click position in the train at electrode sites contralateral to the leading stimulus and, conversely, increased (30%) at electrode sites ipsilateral to the lead. These results suggest that differential refractoriness of the N1 response may lead to the lateralized perception of buildup to the precedence effect. [Work supported by NSERC-Canada.]
The event-related brain potentials to uncorrelated fragment of noise
Authors: Huang Juan , Wu Xihong , Li Liang , Qi James , Scheneider Bruce , He Yu , Alain Claude
Published: October 2013

Two correlated waveforms of broadband noise presented to the left and right ear simultaneously or with a short delay are often perceptually fused into one sound image. However, when an uncorrelated noise fragment (UCNF) is inserted in a long duration sound, listeners report hearing a transient burst of noise. The detection of the UCNF is dependent on the duration of the UCNF and the binaural delays. Here, we recorded event-related brain potentials (ERPs) to 100-ms UCFN and varied the binaural delay (0, 3, 10, and 20 ms) from trial to trial. The likelihood of detecting the UCNF decreased with increasing binaural delay. At 0 delay, the UCNF elicited negative and positive waves peaking at about 100 and 200 ms after UCNF onset (N1-P2 complex), which was present even when the stimuli were ignored. The conscious detection of the UCNF elicited an additional positive wave between 250 and 450 ms at parietal and occipital sites (P3b). The P3b latency was longer and its amplitude larger for binaural delay of 3 than 0 ms. Our results show that the detection of UCF involved both automatic and attention-dependent processes especially when a binaural delay is introduced between two source of correlated noises.
The gradient influence of talker sex and perceived sexual orientation on fricative perception
Authors: Munson Benjamin , Jefferson Sarah V. , McDonald Elizabeth C.
Published: October 2013

Listeners are more likely to hear a synthetic fricative ambiguous between /s/ and /∫/ as /∫/ if it is appended to a woman’s voice than a man’s voice [Strand, J. Lang. Soc. Psych. 18, 86–99 (1999)], suggesting that speech perception is sensitive to social-indexical information. This study examined the influence of two variables on listeners’ fricative perception: (a) talker sex, and (b) talkers’ perceived sexual orientation (PSO, i.e., the probability that a talker is identified as gay, lesbian, or bisexual (GLB) based on speech alone). Stimuli were created by pairing a synthetic nine-step /s/-to-/∫/ series with tokens of /æk/ and /Ip/ taken from natural productions of shack and ship by 44 talkers (22 women, 22 men), for a total of 88 different continua. Forty listeners rated the 44 talkers’ PSO. A different group of 10 listeners participated in a series of two-alternative sack-shack and sip-ship identification experiments. As expected, listeners identified more /∫/ tokens for women’s voices than for men’s. GLB-sounding women elicited significantly fewer /∫/ percepts than heterosexual-sounding women. No consistent influence of PSO on fricative identification was noted for men’s voices. Regression analyses showed strong relationships between fricative identification and ratings of PSO for women talkers only.
A model of invariant patterns of articulatory movements
Authors: Bonaventura Patrizia
Published: October 2013

The goal of the present study is to model the ‘‘iceberg’’ portions of the demisyllables, previously extracted from the microbeam articulatory data (Bonaventura, 2003), by curve fitting. The polynomial analysis was designed to include an appropriate weighting window centering around the threshold crossing point, and aimed to provide an estimate of how, in the vicinity of the crossing point, the curve deviates from a straight line: this deviation would be represented by the higher order coefficients of the polynomial. The model was obtained preliminarily on the basis of 100 curves for the lower lip movement for /f/ and /v/ (in initial and final demisyllable for ‘‘five’’), and from 100 curves for the tongue tip displacement (for /n/ in ‘‘nine’’). In order to fit the data to the model, a robust least square method (Least Absolute Residuals) has been used, in order to minimize the influence of the outliers, that are present in the read speech data, and cannot be accounted for by ‘‘phrase final lengthening effects.’’ The fit results for the cubic polynomials satisfactorily approximated the ‘‘iceberg’’ curves. The 95% confidence bounds on the fitted coefficients indicated that they were acceptably accurate.
Age differences in detecting gaps in speech and non-speech
Authors: Pichora-Fuller M. Kathleen , Schneider Bruce A. , Benson Nancy , Hamstra Stanley , Storzer Edward
Published: October 2013

Ability to detect gaps in speech and non-speech stimuli was measured in children, young adults, and older adults with good audiograms. The markers varied in duration (40 vs 250 msec) and in spectral symmetry. In spectrally symmetrical conditions, the leading and lagging markers were the same: the vowel [u] in speech conditions and a 500-Hz tone in non-speech conditions. In asymmetrical speech conditions, the lagging marker was the same as in the symmetrical conditions, but the leading marker was the consonant [s] in the speech conditions and a broadband noise (1 to 6 kHz) in the non-speech conditions. For all groups, gap detection thresholds in spectrally symmetrical markers were far smaller than in spectrally asymmetrical markers. Thresholds were significantly smaller in young adults than in either children or older adults. Gaps between spectrally asymmetrical speech markers were detected better than gaps between analogous non-speech stimuli. It is argued that phonological knowledge compensates for auditory processing difficulties. [Research funded by the International Dyslexia Association, the Natural Sciences and Engineering Research Council of Canada, and the Canadian Institutes of Health Research.]
A role for tracheal resonances in speech perception
Authors: Bachrach Asaf , Lulich Steven , Malyska Nicolas
Published: October 2013

Acoustic coupling between the vocal tract and the trachea results in the introduction of pole-zero pairs corresponding to resonances of the uncoupled trachea. If the second formant (F2) passes through the second tracheal resonance (T2) a discontinuity in amplitude occurs. This work explores the hypothesis that the F2−T2 discontinuity affects how listeners perceive the distinctive feature [back] in transitions from a front vowel (high F2) to a labial stop (low F2). We synthesized two versions of an utterance (‘‘apter’’) with an F2−T2 discontinuity at different locations in the initial VC transition. Subjects heard portions of the utterance with and without the discontinuity, and were asked to identify the utterance. Results show that the presence of the F2−T2 discontinuity facilitated the perception of frontness in the vowel. Discontinuities of the F2−T2 sort are proposed to play a role in shaping vowel inventories in the world’s languages [K. N. Stevens, J. Phonetics 17, 3–46 (1989)]. Our results support a model of lexical access in which acoustic discontinuities subserve phonological feature identification.
Phoneme clustering based on segmental lip configurations in naturally spoken sentences
Authors: Xue Jianxia , Alwan Abeer , Jiang Jintao , Bernstein Lynne E.
Published: October 2013

It has been shown that face (lips, cheeks, and chin) information can account to a large extent for visual speech perception in isolated syllables and words. Visual speech synthesis has used small reduced sets of phonemes (‘‘visemes’’), under the theory that perceivers are limited in their ability to extract visual speech information. In this study, lip configurations from a manually segmented sentence database [L. Bernstein et al., J. Acoust. Soc. Am. 107, 2887 (2000)] were analyzed to provide phoneme clusters that are algorithmically distinguishable using mouth vertical/horizontal opening and lip protrusion from the middle position of each segment. The lip feature sample spaces for each phoneme were represented by Gaussian mixture models. Maximum posterior probability classification results were computed for each phoneme. Confusion matrices were generated from the classification results, and a set of confusions with 74% or higher within-group classification correct was judged to be a cluster. Preliminary results from 191 sentences by a single talker generated the following clusters: {/p, b, m/(77%), /f, v/(74%), /w, r/(80%), /t, d, s, z, D, k, n/(88%)}. We will present results analyzing the entire English phoneme set across different talkers and compare the results with visual perceptual clusters. [Work supported in part by the NSF.]
Basin Acoustic Seamount Scattering Experiment (BASSEX 04) II. Downslope propagation
Authors: Heaney Kevin D. , Baggeroer Arthur B. , Becker Kyle M. , Scheer Eddie , Vonderheydt Keith
Published: October 2013

During the Basin Acoustic Seamount Scattering EXperiment (BASSEX04), the Five-Octave Research Array (FORA) was deployed near the North Pacific Acoustics Laboratory (NPAL) bottom mounted tomography source just off the coast of Kauai. Receptions from the Kauai source were taken at ranges from 2 km out to 500 km. The data was taken to examine the affects of seafloor interaction on downslope propagation (propagation down both steep and shallow slopes), shallow water range-dependent 3-D propagation and conversion from shallow water propagation to deep water propagation. Conventional and adaptive beamforming results will be presented as well as comparisons between measured responses and PE modeled responses. Geo-acoustic inversions will be performed with the broadband source in end-fire and broadside orientations of the array. [Work supported by ONR Ocean Acoustics.]
Rapid acoustic field computations within environmental uncertainty bounds
Authors: Heaney Kevin D.
Published: October 2013

Oceanographic and geo-acoustic variability in the shallow water can dominate acoustic propagation. Often the environment is critically undersampled, compared to the sensitivity of the full-field propagation model used [such as the Parabolic Equation (PE) model]. For regions with environmental uncertainty (which is known from measurements or models), there will be a Minimum Achievable Uncertainty (MAU) in acoustic propagation modeling (Transmission Loss). Given this MAU, it is proposed that field interpolation techniques be applied to speed up the acoustic propagation computation, consistent with keeping the interpolation errors below the MAU. Techniques for estimating the uncertainty in TL and speeding up the broadband range-dependent computation using the Navy Standard PE model will be presented. For fully 3-D field computations in a range-dependent environment, the speed up is expected to be several orders of magnitude.
Transaural virtual reality applied to front-back localization
Authors: Zhang Peter Xinya , Hartmann William M.
Published: October 2013

Human sound localization can be studied by measuring head-related transfer functions for different source locations and subsequently using the data to simulate different spatial locations using headphone presentation. This technique fails to adequately simulate the difference between front and back locations because the frequencies relevant to pinna cues are so high. A transaural (cross-talk cancellation) technique has been developed that is accurate up to 16 kHz. By controlling the levels and phases of spectral components, as measured by probe microphones in the ear canals, the technique eliminates significant differences between the baseline simulation and reality. The technique has been used, with modifications to the baseline simulation, to study the front-back information content in different frequency bands by eliminating the information while maintaining the energy. It has also been used to test for orthogonality between front-back localization and azimuthal localization based on simple interaural differences. The technique has verified that front-back discrimination cannot be mediated by interaural differences alone. By flattening the level spectrum in one ear while leaving the other ear unchanged it has been possible to demonstrate an ear advantage for front-back discrimination. [Work supported by the NIDCD, grant DC 00181.]
Intensity and time-angle fluctuations of high frequency signal propagation in shallow water
Authors: Badiey Mohsen , Luo Jing , Song Aijun
Published: October 2013

Several high frequency experiments in recent years have been directed towards assessing signal variability as a function of channel environmental parameters. In this paper, results from one of these experiments in a shallow water region are shown. Acoustic communication coded signals were transmitted between a source and two receiver arrays separated 1 and 2 km respectively while detailed measurement of the channel environmental parameters were recorded. Channel impulse response function and the correlation time of the channel are obtained. Ray theory is used to analyze and interpret the experimental data. Arrival time-angle fluctuations were found to be directly correlated with the environmental variability due to ocean dynamics in the experiment region.
Spectral features of sound field fluctuations in shallow water with internal solitons
Authors: Badiey Mohsen , Grigorev Valery , Katsnelson Boris , Lynch James
Published: October 2013

Mode coupling of acoustic wave propagation in shallow water, in the presence of internal soliton is considered. It is shown that quasiperiodical behavior of temporal variability of the received signal (arising from the motion of soliton packets) provides some peaks in frequency spectrum. Positions of these peaks in spectrum are determined both by the space scales of interference beating (ray cycles) and velocity of solitons. Results of theoretical and numerical modeling as well as related experimental setup is discussed. [Work supported by ONR, RFBR and CRDF.]
Method for automatic measurement of second language speaking proficiency
Authors: Bernstein Jared , Balogh Jennifer
Published: October 2013

Spoken language proficiency is intuitively related to effective and efficient communication in spoken interactions. However, it is difficult to derive a reliable estimate of spoken language proficiency by situated elicitation and evaluation of a person’s communicative behavior. This paper describes the task structure and scoring logic of a group of fully automatic spoken language proficiency tests (for English, Spanish and Dutch) that are delivered via telephone or Internet. Test items are presented in spoken form and require a spoken response. Each test is automatically-scored and primarily based on short, decontextualized tasks that elicit integrated listening and speaking performances. The tests present several types of tasks to candidates, including sentence repetition, question answering, sentence construction, and story retelling. The spoken responses are scored according to the lexical content of the response and a set of acoustic base measures on segments, words and phrases, which are scaled with IRT methods or parametrically combined to optimize fit to human listener judgments. Most responses are isolated spoken phrases and sentences that are scored according to their linguistic content, their latency, and their fluency and pronunciation. The item development procedures and item norming are described.
Auditory plasticity in deaf children with bilateral cochlear implants
Authors: Litovsky Ruth
Published: October 2013

Human children with cochlear implants represent a unique population of individuals who have undergone variable amounts of auditory deprivation prior to being able to hear. Even more unique are children who received bilateral cochlear implants (BICIs), in sequential surgical procedures, several years apart. Auditory deprivation in these individuals consists of a two-stage process, whereby complete deafness is experienced initially, followed by deafness in one ear. We studied the effects of post-implant experience on the ability of deaf children to localize sounds and to understand speech in noise. These are two of the most important functions that are known to depend on binaural hearing. Children were tested at time intervals ranging from 3-months to 24-months following implantation of the second ear, while listening with either implant alone or bilaterally. Our findings suggest that the period during which plasticity occurs in human binaural system is protracted, extending into middle-to-late childhood. The rate at which benefits from bilateral hearing abilities are attained following deprivation is faster for speech intelligibility in noise compared with sound localization. Finally, the age at which the second implant was received may play an important role in the acquisition of binaural abilities. [Work supported by NIH-NIDCD.]
Comparing listener preferences for text-level prosody in English and French
Authors: Smith Caroline
Published: October 2013

Cross-language prosodic differences are well-known at the phrasal level and below, and a few studies have shown language-dependent differences in speakers’ prosody over a discourse or text [Fon (2002), Smith and Hogan (2003)]. For comparison with the patterns found in production, this study examines listeners’ preferences in text-level prosody. Previously-analyzed recordings of one speaker of American English reading aloud an English text, and one speaker of Parisian French reading a comparable French text, were used as a basis. The discourse organization of each text was analyzed by several native speakers who categorized each sentence-to-sentence transition as a Topic Shift, Continuation or Elaboration. The original recordings were manipulated in several ways to alter rate, sentence-final lengthening and pause duration, and the manipulated versions were presented to listeners. English listeners liked best those versions where values for rate and lengthening matched the speakers’ means for each separate type of topic transition. French listeners preferred the version where each prosodic variable kept the same mean value throughout. These results are supported by acoustic measurements which also point to a more salient role for rhythmic effects at the discourse level in English than in French. [Work supported by NSF grant BCS-9983106.]
Using vertical directionality to study the ambient noise fluctuations due to internal waves in South China Sea
Authors: Chan Hsiang-Chih , Wei Ruey-Chang , Hu Wen-Zheng , Chen Chi-Fang
Published: October 2013

A range-dependent acoustic propagation model is used to simulate the complex ambient noise field, which offers the key to the understanding of noise varying during the ASIAEX 2001 SCS experiment. The surface noise sources that are generated by wind/waves and ships are distributed horizontally in the simulated model. Observed ambient noise fluctuations in South China Sea are greatly affected by prevailing internal waves in this area, the vertical directionality changes on vertical line array output were believed to be results of interaction between sound and ocean environment. The measured twin-peak beam patterns are not consistent with previous studies on flat or upslope bathymetry. Therefore, in this study the discrepancy is explained by modeling and correlation between the noise distributions and internal wave position.
Acoustic spreading and boat noise within shallow Florida waterways
Authors: Phillips Richard , Niezrecki Christopher , Beusse Diedrich O.
Published: October 2013

The West Indian manatee has become endangered partly because of watercraft collisions in Florida’s coastal waterways. Several boater warning systems, based upon manatee vocalizations, have been proposed to reduce the number of collisions. One aspect of the feasibility of an acoustically based system will rely upon the distance in which a manatee vocalization can be detected. The magnitude of environmental noise and manatee vocalizations, as well as the acoustic spreading properties of the habitat will help to estimate the detection range of a manatee. This study surveyed several shallow-water coastal areas in Florida (Crystal River, Cedar Key, and Indian River) which are likely to be inhabited by manatees. Using a chirp signal (1–10 kHz) broadcast by an underwater transducer, it was observed that the acoustic pressure data collected was best represented by the mixed and Lurton spreading models. The overall data obtained from passing a boat directly over the hydrophone was most closely represented by a spherical spreading model. However, for a boat that is approaching, a mixed spreading model is the most appropriate. The mean SPL for boat traffic was measured to be 140 dB and the background environment noise level ranged between 69 and 105 dB.
Auditory evoked potentials (AEP) methods for population-level assessment of hearing sensitivity in bottlenose dolphins
Authors: Houser Dorian , Finneran James
Published: October 2013

A portable system for recording auditory evoked potentials (AEP) was developed to rapidly assess the hearing sensitivity of dolphins in air. The system utilizes a transducer embedded in a silicone suction cup to deliver amplitude modulated tones to the dolphin through the lower jaw. Frequencies tested range from 10–150 kHz and testing of both ears is completed within 90 min. AEP-determined thresholds from one subject were benchmarked against that subject’s direct field behavioral audiogram to quantify variation between the two methods. To date, AEP audiograms have been obtained from over 30 bottlenose dolphins. Considerable individual variation in frequency-specific hearing sensitivity was observed. Some high-frequency hearing loss was observed in relatively young (early 20s) and old (35+ years) animals; conversely, age was not necessarily related to hearing loss as several animals greater than 40 years of age had good hearing sensitivity across the range of tested frequencies. Profound hearing loss typically occurred at higher frequencies. Decline in sensitivity was rapid in all cases and began between 50–60 kHz. Increased sample size of hearing sensitivity in dolphins suggest that the use of audiometric functions from single animals as representative of population level audiometry might be misleading.
Time-dependent finite-element model for optimizing source array element position and excitation for a seismic sonar for buried mine detection
Authors: Johnson Anthony N. , Scandrett Clyde L. , Baker Steven R.
Published: October 2013

A three-dimensional (3-D) continuum mechanics approach to the development of a time-dependent finite-element model for optimizing the position and excitation of source array elements for use in a seismic sonar to detect buried landmines is presented. Mathematical formulation of the problem consists of the coupling of a system of linear, second order, partial differential equations and related boundary conditions into one single wave equation, from which a composite elastic finite element is derived. The hp-adaptive finite-element kernel, ProPHLEX [Altair Engineering, Inc., McKinney, TX], is used to perform the numerical computations. The radiation characteristics of a discrete number of transient seismic sources are analyzed in a linear, isotropic, homogeneous half-space. Results for radial and vertical radiation fields, and for radiated Rayleigh wave strength will be presented for various source configurations. Particular attention will be paid to those configurations which maximize the radiation of unidirectional Rayleigh waves, while suppressing the radiation of unwanted body waves.
Acoustic quantification of fish in the riverine environment: Challenges
Authors: Foote Kenneth G.
Published: October 2013

Quantifying fish acoustically in rivers presents many challenges. Some are common to other aquatic environments, but are exacerbated in rivers. Acoustic issues of particular concern are reviewed. These include the backscattering cross section of fish, sampling volume, and both volumetric and surface reverberation. Advantages of methods based on multiple observations of the same fish, such as Doppler analysis, target-tracking, and sensing the angular dependence of fish scattering, or on correlation analysis, given sufficient bandwidth, are emphasized. The need for calibration of involved acoustic devices is mentioned.
A method for locating nearby sources
Authors: Olson John V. , Arnoult Kenneth , Szuberla Curt. A. S.
Published: October 2013

A fast method for locating nearby sources based solely on the time-of-flight information is described. The time delays for a signal passing between all sensor pairs is determined using cross-correlations and a vector of time delays is constructed. In the noise free case, where the speed of sound is constant, each point in the plane is associated with a unique value of the time delay vector. The method we present uses a fast, simplex-based search of the plane for a source location by minimizing the difference between the vector associated with the candidate location on the plane and the value estimated from cross-correlations. The search takes place over the three dimensional space that includes two coordinates in the plane and the propagation speed. The starting point for the search is constructed from an analytic fit of circular wave fronts to groups of sensors within the array. This method has been useful in identifying near-field sources in the 153US and 155US CTBT/IMS infrasound arrays. Examples of the locations we have determined along with a description of the statistical confidence limits associated with the method will be presented.
Unsupervised classification of beluga whale vocalizations
Authors: Clemins Patrick J. , Johnson Michael T.
Published: October 2013

Unsupervised classification techniques are designed to discover natural groupings in a collection of data. For instance, unsupervised classification methods can be used to help define a repertoire for a species by grouping similar vocalizations together. The vocalizations grouped together are then defined as a single call type in the repertoire. There are a number of difficulties in applying these algorithms to vocalizations including quantifying the vocalization into a set of features and accounting for temporal variations in the vocalizations. Using generalized perceptual linear predication coefficients and a set of hidden Markov models to overcome these difficulties, beluga whale vocalizations are classified using K-means unsupervised classification. These classifications are then compared to labels assigned by human experts in order to determine the reliability of the classification system. The underlying goal of this research is to establish a generalized framework that can be used to analyze and classify the vocalizations of a number of species. [Work supported by the National Science Foundation under the Dr. Dolittle Project.]
Insulinoma presenting with cardiac arrest and cardiomyopathy
Authors: Thirumalai Arthi , Levander Ximena A , Mookherjee Somnath , White Andrew A
Published: October 2013

A 33-year-old woman presented with ventricular fibrillation cardiac arrest and was found to have a blood glucose of 1.83 mmol/L. Cardiac catheterisation revealed a dilated left ventricle with an ejection fraction (EF) of 26% and angiographically normal coronary arteries. Continuous dextrose infusion was required to treat hypoglycaemia, which prompted consideration of insulinoma as a possible cause for her cardiomyopathy. Whipple's triad was demonstrated; a 72 h fast provided biochemical evidence of insulinoma, and imaging localised a tumour in her pancreas. The tumour was resected and pathology confirmed insulinoma; pancreaticoduodenectomy cured her hypoglycaemia. No alternate cause of cardiomyopathy was found and 4 months after surgery her EF improved to 41%. High insulin levels can close cardiac KATPchannels associated with dilated cardiomyopathy; the catecholamine surge from hypoglycaemia may also contribute to ventricular remodelling. Hypoglycaemia can cause QT segment prolongation, and may have precipitated fibrillation in this patient's arrhythmia-prone myocardium.
Hitchhiker antigens: Inconsistent ChIP results, questionable immunohistology data, and poor antibody performance may have a common factor
Authors: Parseghian Missag Hagop
Published: October 2013

Questionable data and poor antibody performance may have a common factor: antigens “hitchhiking” on the very antibodies designed to target them. Here I focus on histone hitchhikers and their antibodies, given the impact of chromatin immunoprecipitation on our understanding of DNA regulation. Caused by a lack of stringency during antibody purification, hitchhikers will impede important advances in chromatin research and therapeutics derived from that research, if similar circumstances in the study of lupus decades ago are any guide. Evidence of this phenomenon is reviewed, purification modifications for antibody manufacturing are suggested, and a histone hitchhiker detection procedure is provided.
Computing technologies for reflective, creative care of people with dementia
Authors: Maiden Neil , D'Souza Sonali , Jones Sara , Müller Lars , Pannese Lucia , Pitts Kristine , Prilla Michael , Pudney Kevin , Rose Malcolm , Turner Ian , Zachos Konstantinos
Published: October 2013

Mobile apps manage data on individual residents to help carers deliver more person-centered care.
More than a mouse
Authors: Savage Neil
Published: October 2013

Gesture and gaze are among the newest additions to a growing family of computer interfaces.
Puzzled
Authors: Winkler Peter
Published: October 2013

Each of these puzzles involves coin flipping. Simple stuff, right? Not necessarily…though solutions will indeed be provided in next month's column.
Random graphs and the parity quantifier
Authors: Kolaitis Phokion G. , Kopparty Swastik
Published: October 2013

The classical zero-one law for first-order logic on random graphs says that for every first-order property φ in the theory of graphs and every
p
∈ (0,1), the probability that the random graph
G
(
n
,
p
) satisfies φ approaches either 0 or 1 as
n
approaches infinity. It is well known that this law fails to hold for any formalism that can express the parity quantifier: for certain properties, the probability that
G
(
n
,
p
) satisfies the property need not converge, and for others the limit may be strictly between 0 and 1.

In this work, we capture the limiting behavior of properties definable in first order logic augmented with the parity quantifier, FO[⌖], over
G
(
n
,
p
), thus eluding the above hurdles. Specifically, we establish the following “modular convergence law”.

For every FO[⌖] sentence φ, there are two explicitly computable rational numbers

a
0

,

a
1

, such that for
i
∈ {0,1}, as
n
approaches infinity, the probability that the random graph
G
(2
n
+
i
,
p
) satisfies φ approaches

a
i

.

Our results also extend appropriately to FO equipped with Mod
q
quantifiers for prime
q
.

In the process of deriving this theorem, we explore a new question that may be of interest in its own right. Specifically, we study the joint distribution of the subgraph statistics modulo 2 of
G
(
n
,
p
): namely, the number of copies, mod 2, of a fixed number of graphs
F
1
, …,
F
ℓ
of bounded size in
G
(
n
,
p
). We first show that every FO[⌖] property φ is almost surely determined by subgraph statistics modulo 2 of the above type. Next, we show that the limiting joint distribution of the subgraph statistics modulo 2 depends only on
n
mod 2, and we determine this limiting distribution completely. Interestingly, both these steps are based on a common technique using multivariate polynomials over finite fields and, in particular, on a new generalization of the Gowers norm.

The first step is analogous to the Razborov-Smolensky method for lower bounds for AC
0
with parity gates, yet stronger in certain ways. For instance, it allows us to obtain examples of simple graph properties that are exponentially uncorrelated with every FO[⌖] sentence, which is something that is not known for AC
0
[⌖].
Effects of the green tea polyphenol epigallocatechin-3-gallate on high-fat diet-induced insulin resistance and endothelial dysfunction
Authors: Jang Hyun-Ju , Ridgeway Simone D. , Kim Jeong-a
Published: October 2013

Insulin resistance, a hallmark of metabolic disorders, is a risk factor for diabetes and cardiovascular disease. Impairment of insulin responsiveness in vascular endothelium contributes to insulin resistance. The reciprocal relationship between insulin resistance and endothelial dysfunction augments the pathophysiology of metabolism and cardiovascular functions. The most abundant green tea polyphenol, epigallocatechin-3-gallate (EGCG), has been shown to have vasodilator action in vessels by activation of endothelial nitric oxide synthase (eNOS). However, it is not known whether EGCG has a beneficial effect in high-fat diet (HFD)-induced endothelial dysfunction. Male C57BL/6J mice were fed either a normal chow diet (NCD) or HFD with or without EGCG supplement (50 mg·kg−1·day−1) for 10 wk. Mice fed a HFD with EGCG supplement gained less body weight and showed improved insulin sensitivity. In vehicle-treated HFD mice, endothelial function was impaired in response to insulin but not to acetylcholine, whereas the EGCG-treated HFD group showed improved insulin-stimulated vasodilation. Interestingly, EGCG intake reduced macrophage infiltration into aortic tissues in HFD mice. Treatment with EGCG restored the insulin-stimulated phosphorylation of eNOS, insulin receptor substrate-1 (IRS-1), and protein kinase B (Akt), which was inhibited by palmitate (200 μM, 5 h) in primary bovine aortic endothelial cells. From these results, we conclude that supplementation of EGCG improves glucose tolerance, insulin sensitivity, and endothelial function. The results suggest that EGCG may have beneficial health effects in glucose metabolism and endothelial function through modulating HFD-induced inflammatory response.
Thrombospondin-1/CD36 pathway contributes to bone marrow-derived angiogenic cell dysfunction in type 1 diabetes via Sonic hedgehog pathway suppression
Authors: Wang Jie-Mei , Isenberg Jeffery S. , Billiar Timothy R. , Chen Alex F.
Published: October 2013

Refractory wounds in diabetic patients present a significant clinical problem. Sonic hedgehog (SHH), a morphogenic protein central to wound repair, is deficient in diabetes. Regulation of SHH in wound healing is poorly understood. We hypothesize that thrombospondin-1 (TSP-1), through its receptor CD36, contributes to the SHH signaling defect in bone marrow-derived angiogenic cells (BMACs) in type 1 diabetic mice. Isolated BMACs from TSP-1-knockout mice demonstrated improved tube formation, migration, and adhesion in parallel with active SHH signaling. BMACs from STZ-induced type 1 diabetic mice showed significantly impaired Matrigel tube formation ( n = 5; P < 0.05 vs. control), which was rescued by TSP-1 depletion ( n = 5; P < 0.05 STZ-TSP-1−/−vs. STZ-WT) or exogenous SHH (20 mg/l, 24 h, n = 4; P < 0.05 vs. STZ-control). The expression of CD36 was elevated in BMACs from STZ mice ( n = 4; P < 0.05). SHH signaling was significantly higher in BMACs from TSP-1−/−mice and TSP-1 receptor CD36-knockout mice ( n = 6; P < 0.05 vs. WT) but not CD47-knockout mice ( n = 3; P > 0.05 vs. WT). The impairment of recombinant human TSP-1 (2.2 nM, 24 h) on BMAC Matrigel tube formation was delayed significantly by CD36 deletion ( n = 5; P < 0.05). CD36−/−BMACs demonstrated better tube formation under both normal and diabetic conditions with active SHH signaling ( n = 4; P < 0.05 vs. WT BMACs). In conclusion, The TSP-1/CD36 pathway contributes to the SHH signaling defect, resulting in BMAC dysfunction in type 1 diabetic mice.
Integration and segregation of multiple motion signals by neurons in area MT of primate
Authors: McDonald J. Scott , Clifford Colin W. G. , Solomon Selina S. , Chen Spencer C. , Solomon Samuel G.
Published: October 2013

We used multielectrode arrays to measure the response of populations of neurons in primate middle temporal area to the transparent motion of two superimposed dot fields moving in different directions. The shape of the population response was well predicted by the sum of the responses to the constituent fields. However, the population response profile for transparent dot fields was similar to that for coherent plaid motion and hence an unreliable cue to transparency. We then used single-unit recording to characterize component and pattern cells from their response to drifting plaids. Unlike for plaids, component cells responded to the average direction of superimposed dot fields, whereas pattern cells could signal the constituent motions. This observation provides support for a strong prediction of the Simoncelli and Heeger (1998) model of motion analysis in area middle temporal, and suggests that pattern cells have a special status in the processing of superimposed dot fields.
The Afferent Visual Pathway: Designing a Structural-Functional Paradigm of Multiple Sclerosis
Authors: Costello Fiona
Published: October 2013

Multiple sclerosis (MS) is a disease of the central nervous system (CNS) believed to arise from a dysfunctional immune-mediated response in a genetically susceptible host. The actual cause of MS is not known, and there is ongoing debate about whether this CNS disorder is predominantly an inflammatory versus a degenerative condition. The afferent visual pathway (AVP) is frequently involved in MS, such that one in every five individuals affected presents with acute optic neuritis (ON). As a functionally eloquent system, the AVP is amenable to interrogation with highly reliable and reproducible tests that can be used to define a structural-functional paradigm of CNS injury. The AVP has numerous unique advantages as a clinical model of MS. In this review, the parameters and merits of the AVP model are highlighted. Moreover, the roles the AVP model may play in elucidating mechanisms of brain injury and repair in MS are described.
One‐Step Synthesis of PEGylated Gold Nanoparticles with Tunable Surface Charge
Authors: Stiufiuc Rares , Iacovita Cristian , Nicoara Raul , Stiufiuc Gabriela , Florea Adrian , Achim Marcela , Lucaciu Constantin M.
Published: October 2013

The present work reports a rapid, simple and efficient one‐step synthesis and detailed characterisation of stable aqueous colloids of gold nanoparticles (AuNPs) coated with unmodified poly(ethylene)glycol (PEG) molecules of different molecular weights and surface charges. By mixing and heating aqueous solutions of PEG with variable molecular chain and gold(III) chloride hydrate (HAuCl4) in the presence of NaOH, we have successfully produced uniform colloidal 5 nm PEG coated AuNPs of spherical shape with tunable surface charge and an average diameter of 30 nm within a few minutes. It has been found out that PEGylated AuNPs provide optical enhancement of the characteristic vibrational bands of PEG molecules attached to the gold surface when they are excited with both visible (532 nm) and NIR (785 nm) laser lines. The surface enhanced Raman scattering (SERS) signal does not depend on the length of the PEG molecular chain enveloping the AuNPs, and the stability of the colloid is not affected by the addition of concentrated salt solution (0.1 M NaCl), thus suggesting their potential use for in vitro and in vivo applications. Moreover, by gradually changing the chain length of the biopolymer, we were able to control nanoparticles’ surface charge from −28 to −2 mV, without any modification of the Raman enhancement properties and of the colloidal stability.
Fine Distributed Moderating Material with Improved Thermal Stability Applied to Enhance the Feedback Effects in SFR Cores
Authors: Merk Bruno
Published: October 2013

The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effect in sodium-cooled fast reactor cores is described. The influence of the moderating material on the fuel assembly geometry, the neutron spectrum, the feedback effects, the power and burnup distribution, and the transmutation performance is given. An overview on possible materials is provided and the relationship between hydrogen content and thermal stability is described. A solution for the problem of the limited thermal stability of primarily proposed hydrogen-bearing moderating material ZrH1.6is developed by the use of yttrium-mono-hydride. The similarity in the effects reached by ZrH and YH is demonstrated by comparison calculations. The topic is closed by an overview on material properties, manufacturing issues, experience in fast reactors, and a comparison of raw material costs.
Deep Venous Reflux Associated with a Dilated Popliteal Fossa Vein Reversed with Endovenous Laser Ablation and Sclerotherapy
Authors: Link Daniel P. , Feneis Jennifer , Carson John
Published: October 2013

Objective. To report an incidence of reflux in the deep venous system reversed by ablation of a popliteal fossa vein (PFV).Method. A 40-year-old man with pain and swelling in the medial upper calf was found to have an incompetent PFV.Results. Reflux in the femoral and popliteal veins was reversed utilizing endovenous laser ablation and foam sclerotherapy, documented on Duplex studies before and after the intervention. There was also resolution of symptoms.Conclusion. A PFV can be associated with deep venous reflux. Correction of this reflux with ablation of the PFV suggests that his type of reflux is secondary to volume effects of the incompetent popliteal vein.
A Comparison of Calcium Hydroxyapatite and Dextranomer/Hyaluronic Acid for the Endoscopic Treatment of Vesicoureteral Reflux
Authors: Ngo Tin C. , Wong Ilene Yi-Zhen , Kennedy William A.
Published: October 2013

Purpose. Minimal data exists comparing dextranomer/hyaluronic acid (Dx/HA) and calcium hydroxyapatite (CaHA) for the endoscopic treatment of VUR in the hands of a single user.Materials and Methods. We reviewed our consecutive single-user case series of 27 children (42 ureters) receiving endoscopic treatment with CaHA and 21 children (33 ureters) who received Dx/HA injection. Children receiving CaHA injections were divided into two groups of 13 and 14 patients (Coaptite I and II) to assess the learning curve effects. Postoperatively, RBUS and VCUG were performed. Multiple regression analysis was performed to assess statistical significance of success rates.Results. The total CaHA group had a per-ureter success rate (Grade 0) of 52% after one injection. When separated into two cohorts, the single injection per-ureter success rates were 43% for Coaptite I and 62% for Coaptite II. In contrast, the Dx/HA series had a single injection per-ureter success rate (Grade 0) of 78%.Conclusions. Our consecutive case experience shows improved results for Dx/HA compared to CaHA, though the learning curve effects and evolution of injection technique likely played a role in the improved outcomes in the Dx/HA cohort. A randomized controlled multicenter trial would provide the most accurate data comparing these two agents.