bluuebunny/crossref_metadata_2025 huggingface dataset:
Sounds from airguns and fin whales recorded in the mid-Atlantic Ocean, 1999–2009
Authors: Nieukirk Sharon L. , Mellinger David K. , Moore Sue E. , Klinck Karolin , Dziak Robert P. , Goslin Jean
Published: February 2012

Between 1999 and 2009, autonomous hydrophones were deployed to monitor seismic activity from 16° N to 50° N along the Mid-Atlantic Ridge. These data were examined for airgun sounds produced during offshore surveys for oil and gas deposits, as well as the 20 Hz pulse sounds from fin whales, which may be masked by airgun noise. An automatic detection algorithm was used to identify airgun sound patterns, and fin whale calling levels were summarized via long-term spectral analysis. Both airgun and fin whale sounds were recorded at all sites. Fin whale calling rates were higher at sites north of 32° N, increased during the late summer and fall months at all sites, and peaked during the winter months, a time when airgun noise was often prevalent. Seismic survey vessels were acoustically located off the coasts of three major areas: Newfoundland, northeast Brazil, and Senegal and Mauritania in West Africa. In some cases, airgun sounds were recorded almost 4000 km from the survey vessel in areas that are likely occupied by fin whales, and at some locations airgun sounds were recorded more than 80% days/month for more than 12 consecutive months.
Use of an adaptive-bandwidth protocol to measure importance functions for simulated cochlear implant frequency channels
Authors: Whitmal Nathaniel A. , DeRoy Kristina
Published: February 2012

The Articulation Index and Speech Intelligibility Index predict intelligibility scores from measurements of speech and hearing parameters. One component in the prediction is the frequency-importance function, a weighting function that characterizes contributions of particular spectral regions of speech to speech intelligibility. The purpose of this study was to determine whether such importance functions could similarly characterize contributions of electrode channels in cochlear implant systems. Thirty-eight subjects with normal hearing listened to vowel-consonant-vowel tokens, either as recorded or as output from vocoders that simulated aspects of cochlear implant processing. Importance functions were measured using the method of Whitmal and DeRoy [J. Acoust. Soc. Am. 130, 4032–4043 (2011)], in which signal bandwidths were varied adaptively to produce specified token recognition scores in accordance with the transformed up-down rules of Levitt [J. Acoust. Soc. Am. 49, 467–477 (1971)]. Psychometric functions constructed from recognition scores were subsequently converted into importance functions. Comparisons of the resulting importance functions indicate that vocoder processing causes peak importance regions to shift downward in frequency. This shift is attributed to changes in strategy and capability for detecting voicing in speech, and is consistent with previously measured data.
Neuromuscular control of fundamental frequency and glottal posture at phonation onset
Authors: Chhetri Dinesh K. , Neubauer Juergen , Berry David A.
Published: February 2012

The laryngeal neuromuscular mechanisms for modulating glottal posture and fundamental frequency are of interest in understanding normal laryngeal physiology and treating vocal pathology. The intrinsic laryngeal muscles in an in vivo canine model were electrically activated in a graded fashion to investigate their effects on onset frequency, phonation onset pressure, vocal fold strain, and glottal distance at the vocal processes. Muscle activation plots for these laryngeal parameters were evaluated for the interaction of following pairs of muscle activation conditions: (1) cricothyroid (CT) versus all laryngeal adductors (TA/LCA/IA), (2) CT versus LCA/IA, (3) CT versus thyroarytenoid (TA) and, (4) TA versus LCA/IA (LCA: lateral cricoarytenoid muscle, IA: interarytenoid). Increases in onset frequency and strain were primarily affected by CT activation. Onset pressure correlated with activation of all adductors in activation condition 1, but primarily with CT activation in conditions 2 and 3. TA and CT were antagonistic for strain. LCA/IA activation primarily closed the cartilaginous glottis while TA activation closed the mid-membranous glottis.
Effective wave numbers for thermo-viscoelastic media containing random configurations of spherical scatterers
Authors: Luppé Francine , Conoir Jean-Marc , Norris Andrew N.
Published: February 2012

The dispersion relation is derived for the coherent waves in fluid or elastic media supporting viscous and thermal effects and containing randomly distributed spherical scatterers. The formula obtained is the generalization of Lloyd and Berry’s [Proc. Phys. Soc. London 91, 678–688 (1967)], the latter being limited to fluid host media, and it is the three-dimensional counterpart of that derived by Conoir and Norris [Wave Motion 47, 183–197 (2010)] for cylindrical scatterers in an elastic host medium.
Classification of vocalizations in the Mongolian gerbil, Meriones unguiculatus
Authors: Kobayasi Kohta I. , Riquimaroux Hiroshi
Published: February 2012

The Mongolian gerbil (Meriones unguiculatus) has been an important model system in auditory physiology, but its natural sounds are not well known. Vocalizations produced by colonies of adult gerbils were recorded during various social interactions in a standard laboratory animal-rearing facility. Sound recordings were made continuously for 24 h. This species exhibited a rich repertoire of vocalizations that varied in spectrotemporal structure. Calls were classified into 13 distinct syllable types. These syllables were further categorized into eight simple syllables and five composite syllables, which could be described by combinations of two to three simple syllables. The durations of individual syllables ranged from 30 to 330 ms with fundamental frequencies of 5 to 50 kHz. Those with lower fundamental frequencies typically contained more harmonic components (up to nine). Analysis of syllable sequences indicated that syllables may be combined into three types of simple phrases. These results provide a basis for future studies not only of the behavioral significance of vocalization, but also of the neural basis of vocal communication in the Mongolian gerbil.
Faciliation of Mandarin tone perception by visual speech in clear and degraded audio: Implications for cochlear implants
Authors: Smith Damien , Burnham Denis
Published: February 2012

Cochlear implant (CI) users in tone language environments report great difficulty in perceiving lexical tone. This study investigated the augmentation of simulated cochlear implant audio by visual (facial) speech information for tone. Native speakers of Mandarin and Australian English were asked to discriminate between minimal pairs of Mandarin tones in five conditions: Auditory-Only, Auditory-Visual, CI-simulated Auditory-Only, CI-simulated Auditory-Visual, and Visual-Only (silent video). Discrimination in CI-simulated audio conditions was poor compared with normal audio, and varied according to tone pair, with tone pairs with strong non-F0 cues discriminated the most easily. The availability of visual speech information also improved discrimination in the CI-simulated audio conditions, particularly on tone pairs with strong durational cues. In the silent Visual-Only condition, both Mandarin and Australian English speakers discriminated tones above chance levels. Interestingly, tone-naïve listeners outperformed native listeners in the Visual-Only condition, suggesting firstly that visual speech information for tone is available, and may in fact be under-used by normal-hearing tone language perceivers, and secondly that the perception of such information may be language-general, rather than the product of language-specific learning. This may find application in the development of methods to improve tone perception in CI users in tone language environments.
Classification of stop place in consonant-vowel contexts using feature extrapolation of acoustic-phonetic features in telephone speech
Authors: Lee Jung-Won , Choi Jeung-Yoon , Kang Hong-Goo
Published: February 2012

Knowledge-based speech recognition systems extract acoustic cues from the signal to identify speech characteristics. For channel-deteriorated telephone speech, acoustic cues, especially those for stop consonant place, are expected to be degraded or absent. To investigate the use of knowledge-based methods in degraded environments, feature extrapolation of acoustic-phonetic features based on Gaussian mixture models is examined. This process is applied to a stop place detection module that uses burst release and vowel onset cues for consonant-vowel tokens of English. Results show that classification performance is enhanced in telephone channel-degraded speech, with extrapolated acoustic-phonetic features reaching or exceeding performance using estimated Mel-frequency cepstral coefficients (MFCCs). Results also show acoustic-phonetic features may be combined with MFCCs for best performance, suggesting these features provide information complementary to MFCCs.
The influence of age and high-frequency hearing loss on sensitivity to temporal fine structure at low frequencies (L)
Authors: Moore Brian C. J. , Glasberg Brian R. , Stoev Martin , Füllgrabe Christian , Hopkins Kathryn
Published: February 2012

Sensitivity to temporal fine structure (TFS) at low frequencies may be adversely affected by hearing loss at high frequencies even when absolute thresholds at low frequencies are within the normal range. However, in several studies suggesting this, the effects of hearing loss and age were confounded. Here, interaural phase discrimination (IPD) thresholds for pure tones at 500 and 750 Hz were measured for 39 subjects with ages from 61 to 83 yr. All subjects had near-normal audiometric thresholds at low frequencies, but thresholds varied across subjects at high frequencies. IPD thresholds were correlated with age. IPD thresholds for the test frequency of 750 Hz were weakly correlated with absolute thresholds at high frequencies, but these correlations became non-significant when the effect of age was partialed out. The results do not confirm that sensitivity to TFS at low frequencies is influenced by hearing loss at high frequencies, independently of age.
Automatic speech recognition in cocktail-party situations: A specific training for separated speech
Authors: Marti Amparo , Cobos Maximo , Lopez Jose J.
Published: February 2012

Automatic speech recognition (ASR) refers to the task of extracting a transcription of the linguistic content of an acoustical speech signal automatically. Despite several decades of research in this important area of acoustic signal processing, the accuracy of ASR systems is still far behind human performance, especially in adverse acoustic scenarios. In this context, one of the most challenging situations is the one concerning simultaneous speech in cocktail-party environments. Although source separation methods have already been investigated to deal with this problem, the separation process is not perfect and the resulting artifacts pose an additional problem to ASR performance. In this paper, a specific training to improve the percentage of recognized words in real simultaneous speech cases is proposed. The combination of source separation and this specific training is explored and evaluated under different acoustical conditions, leading to improvements of up to a 35% in ASR performance.
An equivalent source technique for recovering the free sound field in a noisy environment
Authors: Bi Chuan-Xing , Stuart Bolton J.
Published: February 2012

In previous studies, a sound field separation technique based on the equivalent source method (ESM) was successfully applied to separate the incoming and outgoing fields composing a non-free field. However, if the incoming wave is scattered by the source surface, the outgoing field is not the field that would be generated by the source in a free field. The object of the present work was to provide an equivalent source technique that allows the recovery of that free field in a noisy environment. In this approach, the incoming and outgoing fields, including the scattered and directly radiated fields on the measurement surface, are separated to obtain the free-field pressure that would be radiated by the source in an anechoic environment. The recovered free-field pressure is then used to reconstruct the whole free field of the source by using near-field acoustical holography based on the ESM, which makes the results equivalent to those that could be obtained from a free-field measurement. A theoretical description of the technique is given first, and then three numerical cases are investigated to demonstrate the ability of the proposed method.
Acoustic method for calibration of audiometric bone vibrators
Authors: Margolis Robert H. , Stiepan Samantha M.
Published: February 2012

The standard method for the calibration of audiometric bone vibrators requires the use of an artificial mastoid, a device that converts vibratory energy to an electrical analog. The mechanical input impedance of the device is designed to represent the average mechanical impedance of the human head. For calibration purposes, it is not necessary that the coupling device represent the impedance of the head. It is only necessary that it provides a repeatable measurement of the output of the vibrator that can be related to the normal threshold of hearing at each test frequency. In addition to the mechanical output that serves as the stimulus for the hearing test, bone vibrators produce an acoustic signal that is proportional to the mechanical force delivered to the head. By determining the transfer function relating the acoustic sound pressure to the mechanical force, the acoustic signal can serve as a proxy for the vibratory stimulus. This article describes the design and validation of an acoustic coupler for the calibration of audiometric bone vibrators.
Acoustic transmission analysis on cavity resonance sound in a cylindrical cavity system: Application to a Korean bell
Authors: Jeong Won Tae , Kang Yeon June , Kim Seock Hyun
Published: February 2012

This paper presents an analytical model for acoustic transmission characteristics of a cylindrical cavity system representing the acoustic resonance conditions of a Korean bell. The cylindrical cavity system consists of an internal cavity, a gap, an auxiliary cavity, and a rigid base. Since the internal cavity is connected to the external field through a gap, determination of the acoustic transmission characteristics becomes a coupling problem between the internal cavity and external field. The acoustic field of the internal cavity is considered by expanding the solution method of the mixed boundary problem, and the external field is addressed by modifying the radiation impedance model of a finite cylinder. The analytical model is validated by comparison with both experiment and a boundary element method. Using the analytical model, the resonance conditions are determined to maximize the resonance effect. Thus, the resonance frequencies of the bell cavity system are investigated according to the gap size and auxiliary cavity depth. By adjusting gap size or auxiliary cavity depth, the cavity resonance frequency is tuned to resonate partial tones of the bell sound. Finally, the optimal combination of gap size and auxiliary cavity depth is determined.
Linguistic contributions to speech-on-speech masking for native and non-native listeners: Language familiarity and semantic content
Authors: Brouwer Susanne , Van Engen Kristin J. , Calandruccio Lauren , Bradlow Ann R.
Published: February 2012

This study examined whether speech-on-speech masking is sensitive to variation in the degree of similarity between the target and the masker speech. Three experiments investigated whether speech-in-speech recognition varies across different background speech languages (English vs Dutch) for both English and Dutch targets, as well as across variation in the semantic content of the background speech (meaningful vs semantically anomalous sentences), and across variation in listener status vis-à-vis the target and masker languages (native, non-native, or unfamiliar). The results showed that the more similar the target speech is to the masker speech (e.g., same vs different language, same vs different levels of semantic content), the greater the interference on speech recognition accuracy. Moreover, the listener’s knowledge of the target and the background language modulate the size of the release from masking. These factors had an especially strong effect on masking effectiveness in highly unfavorable listening conditions. Overall this research provided evidence that that the degree of target-masker similarity plays a significant role in speech-in-speech recognition. The results also give insight into how listeners assign their resources differently depending on whether they are listening to their first or second language.
Behavioral responses of two captive bottlenose dolphins (Tursiops truncatus) to a continuous 50 kHz tone
Authors: Niu Fu-qiang , Liu Zhen-wen , Wen Hong-tao , Xu De-wei , Yang Yan-ming
Published: February 2012

At present, the fundamental frequencies of signals of most commercially available acoustic alarms to deter small cetaceans are below 20 kHz, but it is not well ascertained whether higher frequencies have a deterrent effect on bottlenose dolphins (Tursiops truncatus). Two captive bottlenose dolphins housed in a floating pen were subjected to a continuous pure tone at 50 kHz with a source level of 160 ± 2 dB (re 1 μPa, rms). The behavioral responses of dolphins were judged by comparing surfacing distance relative to the sound source, number of surfacings, and number of echolocation clicks produced, during forty 15 min baseline periods with forty 15 min test periods (four sessions per day, 40 sessions in total). On all 10 study days, surfacing distance and the number of surfacings increased while click production decreased during broadcasts of test sound. The avoidance threshold sound pressure level for a continuous 50 kHz tone for the bottlenose dolphins, in the context of this study, was estimated to be 144 ± 2 dB (re 1 μPa, rms). The results indicated that a continuous 50 kHz tonal signal can deter bottlenose dolphins from an area.
On the use of an absorption layer for the angular spectrum approach (L)
Authors: Jing Yun
Published: February 2012

Reducing the spatial aliasing error of the angular spectrum method by using an absorption layer is investigated in this paper. The acoustic equation including the absorption layer is presented and is transformed in the spatial frequency domain, where an implicit analytic solution is readily available. Its approximation, which is more suitable for numerical simulation, is derived and is numerically implemented. The comparisons between the present method and available methods demonstrate its validity and advantages.
Sound radiation from Caribbean steelpans using nearfield acoustical holography
Authors: Muddeen Fasil , Copeland Brian
Published: February 2012

The sound-field of a Caribbean low tenor steelpan is examined using nearfield acoustical holography (NAH). The particular instrument, a Bertrand Kelman low tenor, has been previously examined in a single plane using a four microphone sound intensity technique. This paper will examine the sound radiation in a cuboid space enclosing the instrument at three frequencies. Presented will be the results of sound pressure level (SPL), active acoustic intensity (AI), and reactive acoustic intensity (RI) obtained through application of the NAH technique. The limitations of NAH when applied to an irregularly shaped object such as a tenor steelpan will also be presented.
The effect of loudness on the reverberance of music: Reverberance prediction using loudness models
Authors: Lee Doheon , Cabrera Densil , Martens William L.
Published: February 2012

This study examines the auditory attribute that describes the perceived amount of reverberation, known as “reverberance.” Listening experiments were performed using two signals commonly heard in auditoria: excerpts of orchestral music and western classical singing. Listeners adjusted the decay rate of room impulse responses prior to convolution with these signals, so as to match the reverberance of each stimulus to that of a reference stimulus. The analysis examines the hypothesis that reverberance is related to the loudness decay rate of the underlying room impulse response. This hypothesis is tested using computational models of time varying or dynamic loudness, from which parameters analogous to conventional reverberation parameters (early decay time and reverberation time) are derived. The results show that listening level significantly affects reverberance, and that the loudness-based parameters outperform related conventional parameters. Results support the proposed relationship between reverberance and the computationally predicted loudness decay function of sound in rooms.
Three-dimensional biomechanical properties of human vocal folds: Parameter optimization of a numerical model to match in vitro dynamics
Authors: Yang Anxiong , Berry David A. , Kaltenbacher Manfred , Döllinger Michael
Published: February 2012

The human voice signal originates from the vibrations of the two vocal folds within the larynx. The interactions of several intrinsic laryngeal muscles adduct and shape the vocal folds to facilitate vibration in response to airflow. Three-dimensional vocal fold dynamics are extracted from in vitro hemilarynx experiments and fitted by a numerical three-dimensional-multi-mass-model (3DM) using an optimization procedure. In this work, the 3DM dynamics are optimized over 24 experimental data sets to estimate biomechanical vocal fold properties during phonation. Accuracy of the optimization is verified by low normalized error (0.13 ± 0.02), high correlation (83% ± 2%), and reproducible subglottal pressure values. The optimized, 3DM parameters yielded biomechanical variations in tissue properties along the vocal fold surface, including variations in both the local mass and stiffness of vocal folds. That is, both mass and stiffness increased along the superior-to-inferior direction. These variations were statistically analyzed under different experimental conditions (e.g., an increase in tension as a function of vocal fold elongation and an increase in stiffness and a decrease in mass as a function of glottal airflow). The study showed that physiologically relevant vocal fold tissue properties, which cannot be directly measured during in vivo human phonation, can be captured using this 3D-modeling technique.
A New Means To Identify Type 3 Secreted Effectors: Functionally Interchangeable Class IB Chaperones Recognize a Conserved Sequence
Authors: Costa Sonia C. P. , Schmitz Alexa M. , Jahufar Fathima F. , Boyd Justin D. , Cho Min Y. , Glicksman Marcie A. , Lesser Cammie F.
Published: February 2012

Many Gram-negative bacteria utilize specialized secretion systems to inject proteins (effectors) directly into host cells. Little is known regarding how bacteria ensure that only small subsets of the thousands of proteins they encode are recognized as substrates of the secretion systems, limiting their identification through bioinformatic analyses. Many of these proteins require chaperones to direct their secretion. Here, using the newly described protein interaction platform assay, we demonstrate that type 3 secretion system class IB chaperones from one bacterium directly bind their own effectors as well as those from other species. In addition, we observe that expression of class IB homologs from seven species, including pathogens and endosymbionts, mediate the translocation of effectors from
Shigella
directly into host cells, demonstrating that class IB chaperones are often functionally interchangeable. Notably, class IB chaperones bind numerous effectors. However, as previously proposed, they are not promiscuous; rather they recognize a defined sequence that we designate the conserved chaperone-binding domain (CCBD) sequence [(LMIF)
1
XXX(IV)
5
XX(IV)
8
X(N)
10
]. This sequence is the first defined amino acid sequence to be identified for any interspecies bacterial secretion system, i.e., a system that delivers proteins directly into eukaryotic cells. This sequence provides a new means to identify substrates of type III secretion systems. Indeed, using a pattern search algorithm for the CCBD sequence, we have identified the first two probable effectors from an endosymbiont,
Sodalis glossinidius
.

IMPORTANCE
Many Gram-negative pathogens utilize type 3 secretion systems to deliver tens of effectors into host cells. In order to understand the diverse ways that these organisms cause disease, it is necessary to identify their effectors, many of which require chaperones to be secreted. Here we establish that class IB chaperones are not promiscuous, as previously proposed, but rather recognize a conserved effector sequence. We demonstrate that pattern search algorithms based on this defined sequence can be used to identify previously unknown effectors. Furthermore, we observe that class IB chaperones from at least seven bacterial species are functionally interchangeable. Not only do they bind and mediate the delivery of their own set of effectors into host cells but they also bind to type 3 substrates from other bacteria, suggesting that inhibitors that block chaperone-effector interactions could provide a novel means to effectively treat infections due to Gram-negative pathogens, including organisms resistant to currently available antibiotics.
C reactive protein, erythrocyte sedimentation rate, or both, in the diagnosis of atraumatic paediatric limb pain?
Authors: Robinson Sara , Leonard Paul
Published: February 2012

Objective

To assess if measurement of either C reactive protein (CRP) or erythrocyte sedimentation rate (ESR) individually has an equivalent diagnostic value to measurement of both in identifying orthopaedic infection as the cause of paediatric atraumatic limb pain.

Setting

Emergency department of a paediatric teaching hospital.

Study design

Retrospective study of case notes for patients attending the emergency department with a complaint of atraumatic limb pain and in whom both ESR and CRP were measured at the time of presentation. Laboratory results at the time of presentation were recorded along with the final diagnosis. Receiver operating characteristic (ROC) curves were created using the data and the optimum cut-off values for each of ESR and CRP were derived using the point of best trade off between sensitivity and specificity. Likelihood ratios for ESR and CRP individually and in combination were calculated.

Results

259 patients were included in the study, of whom 17 were considered to have an orthopaedic infection. ROC curves revealed the best results were obtained using cut-off values of CRP >7 and ESR >12. The combination of a CRP >7 and an ESR >12 gave the best positive likelihood ratio at 6.26 (likelihood ratio 5.34 (CRP >7) vs 2.57 (ESR >12)). For ruling out disease, the combination of CRP ≤7 and ESR ≤12 also outperformed either variable individually (negative likelihood ratio 0.09 (CRP ≤7 and ESR ≤12) vs 0.34 (CRP ≤7) vs 0.18 (ESR ≤12)).

Conclusion

Measurement of both CRP and ESR should be considered an important aid in the investigation of atraumatic limb pain.
N-SOLITON SOLUTIONS AND CONSERVATION LAWS OF THE MODIFIED TODA LATTICE EQUATION
Authors: WEN XIAO-YONG
Published: February 2012

The modified Toda lattice equation is investigated via Darboux transformation (DT) technique, the N-fold DT is constructed based on its Lax representation. The N-soliton solutions are also derived via the resulting N-fold DT. Soliton structures and interaction behavior of those solutions are shown graphically. Finally, the infinitely many conservation laws for that system are given.
CHIRALITY-ASYMMETRY MACROSCOPIC FORCE INDUCED BY AXION BETWEEN THE α-QUARTZ AND COPPER BLOCK
Authors: HU YONGHONG , WU YUNYI
Published: February 2012

A macroscopic force induced by the effective potential suggested by Moody and Wilczek between α-quartz crystal and copper block is studied in detail. The matrix elements in the force formula are analyzed according to representations of the non-symmorphic space group P 3121 of α-quartz crystal. The asymmetry distribution of valence electrons and the selection rules do not cancel the force. We conclude that there exists a CP-violating macroscopic force. According to the limit of the production of the axion coupling constants gs gp/ℏc ≤ 10-26 at the Compton wavelength λ = 10-3 m, the macroscopic force between a 0.08 × 0.08 × 0.02 m3 block of α-quartz and a 0.08 × 0.08× 0.01 m3 copper block with a separation being 0.5 × 10-3 m in between, is estimated at less than 3.09 × 10-26 N.
SINGLE ON-RAMP IN ASYMMETRIC SIMPLE EXCLUSION PROCESSES
Authors: XIAO SONG , LIU MINGZHE , SHANG JING
Published: February 2012

This paper studies the single on-ramp in a totally asymmetric simple exclusion processes (TASEPs). In our model, particles can only attach irreversibly with rate q to a bulk site k + 1, which is far away from boundaries. The model is investigated under random sequential update and open boundary conditions by using Monte Carlo simulations and mean-field calculations. In the case of hopping rate p = 1, when attachment rate q is fixed and q < 0.5, there are five phases in the system, while when q > 0.5, the system includes only four phases and the LD/LD phase vanishes.
ACOUSTIC POLARON IN CYLINDRICAL QUANTUM WIRES
Authors: HOU JUNHUA , LIANG X. X. , ZHOU XIN
Published: February 2012

The ground state energies and the derivates of the acoustic polaron in cylindrical quantum wire systems are performed by using the Huybrechts-like variational approach. The criterions for presence of the self-trapping transition of the acoustic polaron in cylindrical quantum wires are determined qualitatively. It is found that the critical coupling constant for the discontinuous transition from a quasi-free state to a trapped state of the acoustic polaron in cylindrical quantum wires tends to shift toward the weaker electron–phonon coupling with the increasing of cutoff wave vector. Detailed numerical results confirm that the self-trapping transition is expected to occur in the cylindrical quantum wire systems of alkali halides and wide-band-gap semiconductors.
STRUCTURE, ELECTRICAL TRANSPORT AND MAGNETO-RESISTANCE PROPERTIES OFLa5/8Ca3/8MnO3MANGANITE SYNTHESIZED WITH DIFFERENT MANGANESE PRECURSORS
Authors: NAVASERY M. , HALIM S. A. , LIM K. P. , CHEN S. K. , ROSLAN A. S. , ABD-SHUKOR R.
Published: February 2012

We synthesized the polycrystalline manganite of La5/8Ca3/8MnO3with three different manganese routes prepared through a solid state reaction method. The effects of the manganese route selection on the structure, electrical transport and magneto-transport properties were examined in this study. The samples were characterized using X-ray diffraction (XRD) and SEM to identify their structure and morphology. XRD analysis confirmed that all samples were in single phase with orthorhombic structure and belonged to the Pnma space group. The average grain sized samples with manganese route of Mn2O3and MnCO3had a grain size of 1.2–8.7 μm and 2–7.5 μm, respectively. For the MnO2route, the sample had a small melt-like shape with higher porosity. The metal–insulator transition temperature, TMI, for LCMO ( Mn2O3), LCMO ( MnO2) and LCMO ( MnCO3) samples were 270 K, 266 K and 258 K, respectively. All the samples showed negative magneto-resistance with significant increase in value near the TMItemperature. The highest CMR (colossal magneto-resistance) ratio was found in LCMO ( Mn2O3), -22.06% at 270 K, followed by -16.69% for LCMO ( MnO2) at 80 K, and 15.2% for LCMO ( MnCO3) at 100 K in a 1 T magnetic field.
DIMENSION REDUCTION FOR ANALYSIS OF UNSTABLE PERIODIC ORBITS USING LOCALLY LINEAR EMBEDDING
Authors: COY BENJAMIN
Published: February 2012

An autonomous four-dimensional dynamical system is investigated through a topological analysis. This system generates a chaotic attractor for the range of control parameters studied and we determine the organization of the unstable periodic orbits (UPOs) associated with the chaotic attractor. Surrogate UPOs were found in the four-dimensional phase space and pairs of these orbits were embedded in three-dimensions using Locally Linear Embedding. This is a dimensionality reduction technique recently developed in the machine learning community. Embedding pairs of orbits allows the computation of their linking numbers, a topological invariant. A table of linking numbers was computed for a range of control parameter values which shows that the organization of the UPOs is consistent with that of a Lorenz-type branched manifold with rotation symmetry.
CHARACTERIZATION OF THE DYNAMICAL BEHAVIOR OF THE COMPRESSIBLE "POOR MAN'S NAVIER–STOKES EQUATIONS"
Authors: STRODTBECK J. P. , McDONOUGH J. M. , HISLOP P. D.
Published: February 2012

The compressible "poor man's Navier–Stokes equations" (PMNS equations) are a discrete dynamical system derived from a Galerkin expansion of the compressible Navier–Stokes equations. Complete details of the derivation are presented, with attention given to the differences from the original, incompressible case. A thorough numerical investigation of the bifurcation behavior is given in the form of regime maps characterizing the different kinds of dynamical behavior, bifurcation sequences, power spectral density analysis, time series and phase portraits. As in the case of previously studied incompressible PMNS equations, the full range of dynamical behavior associated with physical turbulence is exhibited by the system of coupled maps. The conclusion is drawn that this system can be viable as a source of temporal fluctuations in synthetic-velocity subgrid-scale models for large-eddy simulation.
USING JACOBIAN ELLIPTIC FUNCTIONS TO MODEL NATURAL SHAPES
Authors: CHACÓN RICARDO
Published: February 2012

Jacobian elliptic functions are at the heart of nonlinear science long before the discovery of chaos and complexity. Here, these fundamental functions are shown to be a suitable tool to model complex natural shapes in contrast to the traditionally used sinusoidal functions. In particular, it is demonstrated through the examples of butterfly-like curves and seashell-like surfaces that they allow one to incorporate diverse aspects of complexity such as diversity of contour shapes and textures (patterns) which are absent in a description based on the sinusoidal functions.
USING ENERGY-PHASE METHOD TO STUDY GLOBAL BIFURCATIONS AND SHILNIKOV TYPE MULTIPULSE CHAOTIC DYNAMICS FOR A NONLINEAR VIBRATION ABSORBER
Authors: LI S. B. , ZHANG W. , YAO M. H.
Published: February 2012

Global bifurcations and Shilnikov type multipulse chaotic dynamics for a nonlinear vibration absorber are investigated by using the energy-phase method for the first time. A two-degree-of-freedom model of a nonlinear vibration absorber is considered. After the nonlinear nonautonomous equations of this model are given, the method of multiple scales is used to derive four first-order nonlinear ordinary differential equations governing the modulation of the amplitudes and phases of the two interacting modes in the presence of 1:1 internal resonance and primary resonance. Using several coordinate transformations to transform the modulation equation into a standard form, we can apply the energy-phase method to show the existence of the multipulse chaotic dynamics by identifying Shilnikov-type multipulse orbits in the perturbed phase space. We are able to obtain the explicit restriction on the damping, forcing excitation and the detuning parameters, under which the multipulse chaotic dynamics is expected. These multipulse orbits represent the repeated departure from purely vertical oscillations for the nonlinear vibration absorber. Numerical simulations also indicate that there exist different forms of the multipulse chaotic responses and jumping phenomena for the nonlinear vibration absorber.
BIFURCATION STRUCTURE OF A VAN DER POL OSCILLATOR SUBJECTED TO NONSINUSOIDAL PERIODIC EXCITATION
Authors: SIMO H. , WOAFO P.
Published: February 2012

Bifurcation structures of a Van der Pol oscillator subjected to the effects of nonsinusoidal excitations are obtained both numerically and experimentally. It is found that the bifurcation sequences are similar, but the ranges of a particular behavior and the bifurcation points of the control parameter are different. The experimental investigation using electronic components shows that results are similar to those observed from numerical simulations.
NONLINEAR RESPONSE OF THE MASS-SPRING MODEL WITH NONSMOOTH STIFFNESS
Authors: LITAK GRZEGORZ , SEOANE JESÚS M. , ZAMBRANO SAMUEL , SANJUÁN MIGUEL A. F.
Published: February 2012

In this paper, we study the nonlinear response of the nonlinear mass-spring model with nonsmooth stiffness. For this purpose, we take as prototype model, a system that consists of the double-well smooth potential with an additional spring component acting on the system only for large enough displacement. We focus our study on the analysis of the homoclinic orbits for such nonlinear potential for which we observe the appearance of chaotic motion in the presence of damping effects and an external harmonic force, analyzing the crucial role of the linear spring in the dynamics of our system. The results are shown by using both the Melnikov analysis and numerical simulations. We expect our work to have implications on problems concerning the suspension of vehicles, among others.
COMPLEXITY INDEX OF OUTER-TOTALISTIC BINARY CELLULAR AUTOMATA WITH ARBITRARY DIMENSION AND NEIGHBORHOOD
Authors: PAZIENZA GIOVANNI E. , GOMEZ-RAMIREZ EDUARDO
Published: February 2012

The concept of complexity index is of key importance in the systematic analysis of the dynamics of Cellular Automata (CA); nevertheless, it has been defined only for the special case of 1D elementary CA. In this paper, we first introduce a complexity index for outer-totalistic binary CA with arbitrary dimension and neighborhood by means of a rigorous mathematical theory, and then propose a method to find it easily, given only the truth table of an outer-totalistic binary CA rule. Through our technique, we study in detail both 1D and 2D elementary CA rules, including the well-known Game of Life.
USING NONLINEAR MODELING OF RECONSTRUCTED PHASE SPACE AND FREQUENCY DOMAIN ANALYSIS TO IMPROVE AUTOMATIC SPEECH RECOGNITION PERFORMANCE
Authors: JAFARI AYYOOB , ALMASGANJ FARSHAD
Published: February 2012

This paper introduces a combinational feature extraction approach to improve speech recognition systems. The main idea is to simultaneously benefit from some features obtained from nonlinear modeling applied to speech reconstructed phase space (RPS) and typical Mel frequency Cepstral coefficients (MFCCs) which have a proved role in speech recognition field. With an appropriate dimension, the reconstructed phase space of speech signal is assured to be topologically equivalent to the dynamics of the speech production system, and could therefore include information that may be absent in linear analysis approaches. In the first part of this paper the application of Lyapunov Exponents (LE) and Fractal Dimension as two usual chaotic features in speech recognition are tested and then a short discussion is made on the weakness of these features in speech recognition. In the following, a statistical modeling approach based on Gaussian mixture models (GMMs) is applied to speech RPS. A final pruned feature set is obtained by applying an efficient feature selection approach to the combination of the parameters of the GMM model and MFCC-based features. A hidden Markov model-based (HMM) speech recognition system and TIMIT speech database are used to evaluate the performance of the proposed feature set by conducting isolated and continuous speech recognition experiments. In final Continuous Speech Recognition (CSR) Experiments, using tri-phone models, 3.7% absolute phoneme recognition accuracy improvement against using MFCC features alone were obtained.
THE COEFFICIENT REGULARIZED REGRESSION WITH RANDOM PROJECTION
Authors: CHEN DI-RONG , LI HAN
Published: February 2012

In this paper, the coefficient regularized regression algorithm with random projection is proposed. The excess error of the proposed algorithm associated with the reproducing kernel Hilbert space is bounded. Theoretical analysis shows that it is possible to learn directly in the projected domain and that random projection, as a preprocessing step in supervised learning, leads to empirical risk minimization on the projected data computationally simple.
IMAGE DENOISING BASED ON GAUSSIAN AND NON-GAUSSIAN ASSUMPTION
Authors: ZHAO PING , SHANG ZHAOWEI , ZHAO CHUN
Published: February 2012

In this paper, we first present an adaptive intra-scale noise removal scheme, and estimate clean wavelet coefficients using new prior information with Bayesian estimation techniques. A new model using the non-informative improper Jeffreys' prior is given under the supposed Gaussian distribution for orthogonal wavelet transformation. Then, we propose a computationally feasible adaptive noise smoothing algorithm that considers the dependency characteristics of images. The wavelet coefficients are assumed to be non-Gaussian random variables for non-orthogonal redundancy transformation. The variances of the wavelet coefficients are estimated locally by a centered square-shaped window for every pixel within each subband. The experimental results show that the orthogonal wavelet transformation provides better results at the Gaussian assumption, while the non-orthogonal redundancy wavelet transformation performance tends to increase when the non-Gaussian bivariate distribution is used.
EFFICIENT TiO2 NANOPARTICLES/NANORODS COMPOSITE ELECTRODES FOR DYE-SENSITIZED SOLAR CELLS
Authors: HUANG XIANWEI , SHEN PING , FENG XIAOMING , TAN ZHUO , ZHAO BIN , TAN SONGTING
Published: February 2012

A new TiO2 nanoparticles/nanorods composite electrode was fabricated and applied in dye-sensitized solar cells (DSSCs). The TiO2 nanorods were obtained by grinding the electrospun TiO2 nanofibers mechanically. The composite photoanode of dye-sensitized solar cells was fabricated by using TiO2 nanoparticles (P25) and electrospun TiO2 nanorods. At the optimized condition, the power conversion efficiency (η) based on a triphenylamine dye (SD2) and a ruthenium dye (N719) are 8.28% and 8.80% under AM 1.5 illumination (100 mW ⋅ cm-2), respectively. The results show that the electrospun TiO2 nanorods in the composite photoanode improve the physicochemical properties and enhance the photovoltaic performances of solar cells.
Amino acid absorption and subsequent muscle protein accretion following graded intakes of whey protein in elderly men
Authors: Pennings Bart , Groen Bart , de Lange Anneke , Gijsen Annemie P. , Zorenc Antoine H. , Senden Joan M. G. , van Loon Luc J. C.
Published: February 2012

Whey protein ingestion has been shown to effectively stimulate postprandial muscle protein accretion in older adults. However, the impact of the amount of whey protein ingested on protein digestion and absorption kinetics, whole body protein balance, and postprandial muscle protein accretion remains to be established. We aimed to fill this gap by including 33 healthy, older men (73 ± 2 yr) who were randomly assigned to ingest 10, 20, or 35 g of intrinsically l-[1-13C]phenylalanine-labeled whey protein ( n = 11/treatment). Ingestion of labeled whey protein was combined with continuous intravenous l-[ ring-2H5]phenylalanine and l-[ ring-2H2]tyrosine infusion to assess the metabolic fate of whey protein-derived amino acids. Dietary protein digestion and absorption rapidly increased following ingestion of 10, 20, and 35 g whey protein, with the lowest and highest (peak) values observed following 10 and 35 g, respectively ( P < 0.05). Whole body net protein balance was positive in all groups (19 ± 1, 37 ± 2, and 58 ± 2 μmol/kg), with the lowest and highest values observed following ingestion of 10 and 35 g, respectively ( P < 0.05). Postprandial muscle protein accretion, assessed by l-[1-13C]phenylalanine incorporation in muscle protein, was higher following ingestion of 35 g when compared with 10 ( P < 0.01) or 20 ( P < 0.05) g. We conclude that ingestion of 35 g whey protein results in greater amino acid absorption and subsequent stimulation of de novo muscle protein synthesis compared with the ingestion of 10 or 20 g whey protein in healthy, older men.
Genetic susceptibility to S. aureus mastitis in sheep: differential expression of mammary epithelial cells in response to live bacteria or supernatant
Authors: Bonnefont Cécile M. D. , Rainard Pascal , Cunha Patricia , Gilbert Florence B. , Toufeer Mehdi , Aurel Marie-Rose , Rupp Rachel , Foucras Gilles
Published: February 2012

Staphylococcus aureus is a prevalent pathogen for mastitis in dairy ruminants and is responsible for both clinical and subclinical mastitis. Mammary epithelial cells (MEC) represent not only a physical barrier against bacterial invasion but are also active players of the innate immune response permitting infection clearance. To decipher their functions in general and in animals showing different levels of genetic predisposition to Staphylococcus in particular, MEC from ewes undergoing a divergent selection on milk somatic cell count were stimulated by S. aureus . MEC response was also studied according to the stimulation condition with live bacteria or culture supernatant. The early MEC response was studied during a 5 h time course by microarray to identify differentially expressed genes with regard to the host genetic background and as a function of the conditions of stimulation. In both conditions of stimulation, metabolic processes were altered, the apoptosis-associated pathways were considerably modified, and inflammatory and immune responses were enhanced with the upregulation of il1a, il1b, and tnfa and several chemokines known to enhance neutrophil ( cxcl8) or mononuclear leukocyte ( ccl20) recruitment. Genes associated with oxidative stress were increased after live bacteria stimulation, whereas immune response-related genes were higher after supernatant stimulation in the early phase. Only 20 genes were differentially expressed between Staphylococcus spp-mastitis resistant and susceptible animals without any clearly defined role on the control of infection. To conclude, this suggests that MEC may not represent the cell type at the origin of the difference of mastitis susceptibility, at least as demonstrated in our genetic model. Supernatant or heat-killed S. aureus produce biological effects that are essentially different from those induced by live bacteria.
A Comprehensive Overview and Characterization of Wireless Channels for Networked Robotic and Control Systems
Authors: Gonzalez-Ruiz Alejandro , Ghaffarkhah Alireza , Mostofi Yasamin
Published: February 2012

The goal of this overview paper is to serve as a reference for researchers that are interested in the realistic modeling of wireless channels for the purpose of analysis and optimization of networked robotic systems. By utilizing the knowledge available in the wireless communication literature, we first summarize a probabilistic framework for the characterization of the underlying multiscale dynamics of a wireless link. We furthermore confirm this framework with our robotic testbed, by making an extensive number of channel measurements. To show the usefulness of this framework for networked robotic applications, we then discuss a few recent examples where this probabilistic channel characterization has been utilized for the theoretical analysis and communication-aware design of networked robotic systems. Finally, we show how to develop a realistic yet simple channel simulator, which can be used to verify cooperative robotic operations in the presence of realistic communication links.