bluuebunny/crossref_metadata_2025 huggingface dataset:
Structures of an unliganded neurophysin and its vasopressin complex: Implications for binding and allosteric mechanisms
Authors: Wu Chia Kuei , Hu Bing , Rose John P. , Liu Zhi‐Jie , Nguyen Tam L. , Zheng Changsheng , Breslow Esther , Wang Bi‐Cheng
Published: July 2002

The structures of des 1–6 bovine neurophysin‐II in the unliganded state and as its complex with lysine vasopressin were determined crystallographically at resolutions of 2.4 Å and 2.3 Å, respectively. The structure of the protein component of the vasopressin complex was, with some local differences, similar to that determined earlier of the full‐length protein complexed with oxytocin, but relatively large differences, probably intrinsic to the hormones, were observed between the structures of bound oxytocin and bound vasopressin at Gln 4. The structure of the unliganded protein is the first structure of an unliganded neurophysin. Comparison with the liganded state indicated significant binding‐induced conformational changes that were the largest in the loop region comprising residues 50–58 and in the 7–10 region. A subtle binding‐induced tightening of the subunit interface of the dimer also was shown, consistent with a role for interface changes in neurophysin allosteric mechanism, but one that is probably not predominant. Interface changes are suggested to be communicated from the binding site through the strands of β‐sheet that connect these two regions, in part with mediation by Gly 23. Comparison of unliganded and liganded states additionally reveals that the binding site for the hormone α‐amino group is largely preformed and accessible in the unliganded state, suggesting that it represents the initial site of hormone protein recognition. The potential molecular basis for its thermodynamic contribution to binding is discussed.
Multiple‐site fast exchange model for spin–lattice relaxation in the Fricke‐gelatin dosimeter
Authors: Audet C. , Schreiner L. J.
Published: July 2002

The ferrous sulfate‐doped gel dosimeters have been developed for three‐dimensional magnetic resonance imaging of radiation dose distributions. When the gel dosimeter is irradiated, ferrous ions are converted to ferric ions and the nuclear magnetic spin relaxation of the dosimeter varies with dose. In this paper, a model is presented for the dose dependence of the spin–lattice relaxation rate R1 of the ferrous sulfate doped‐gelatin dosimeter. The model is based on three basic physical quantities: the ferric ion yield and the ferrous and ferric ion relaxivities, r2+ and r3+, respectively. These relaxivities specify the ability of the ions to enhance the spin–lattice relaxation of water protons. The effects of gelatin and sulfuric acid concentration on the ferric ion yield and ion relaxivities are presented. The measured r2+ values agree with those predicted by a model in which the measured spin relaxation is considered the result of the fast exchange of water hydrating the ferrous ion with water in the bulk. The r3+ values are lower than predicted by the fast exchange model. The discrepancies in the measured and predicted r3+ values are shown to result from the complexing of ferric ions arising from pH variation caused by changes in gelatin or sulfuric acid concentrations. A modified version of the R1‐dose response model accounting for ferric ion complexing is presented and tested spectrophotometrically.
Implementation and verification of Virtual Wedge in a three‐dimensional radiotherapy planning system
Authors: Miften Moyed , Zhu X. Ron , Takahashi Kaz , Lopez Francisco , Gillin Michael T.
Published: July 2002

Virtual Wedge (VW) is a Siemens treatment modality which generates wedge‐shaped dose distributions by moving a collimator jaw from closed to open at a constant speed while varying the dose rate in every 2 mm jaw position. In this work, the implementation and verification of VW in a radiotherapy treatment planning (RTP) system is presented. The VW implementation models the dose delivered by VW using the Siemens monitor units (MU) analytic formalism which determines the number of MU required to generate a wedge‐fluence profile at points across the VW beam. For any set of treatment parameters, the VW algorithm generates an “intensity map” that is used to model the modification of fluence emanating from the collimator. The intensity map is calculated as the ratio of MU delivered on an axis point, divided by the monitor units delivered on the central‐axis MU(0). The dose calculation is then performed using either the Clarkson or Convolution/Superposition algorithms. The VW implementation also models the operational constraints for the delivery of VW due to dose rate and jaw speed limits. Dose verifications with measured profiles were performed using both the Clarkson and Convolution/Superposition algorithms for three photon beams; Siemens Primus 6 and 23 MV, and Mevatron MD 15 MV. Agreement within 2% or 2 mm was found between calculated and measured doses, over a large set of test cases, for 15, 30, 45, and 60 degree symmetric and asymmetric VW fields, using the manufacturer's supplied and c values for each beam.
On the sound field radiated by a tuning fork
Authors: Russell Daniel A.
Published: July 2002

When a sounding tuning fork is brought close to the ear, and rotated about its long axis, four distinct maxima and minima are heard. However, when the same tuning fork is rotated while being held at arm’s length from the ear only two maxima and minima are heard. Misconceptions concerning this phenomenon are addressed and the fundamental mode of the fork is described in terms of a linear quadrupole source. Measured directivity patterns in the near field and far field of several forks agree very well with theoretical predictions for a linear quadrupole. Other modes of vibration are shown to radiate as dipole and lateral quadrupole sources.
The Thomas rotation
Authors: Costella John P. , McKellar Bruce H. J. , Rawlinson Andrew A. , Stephenson Gerard J.
Published: July 2002

We review why the Thomas rotation is a crucial facet of special relativity, that is just as fundamental, and just as “unintuitive” and “paradoxical,” as such traditional effects as length contraction, time dilation, and the ambiguity of simultaneity. We show how this phenomenon can be quite naturally introduced and investigated in the context of a typical introductory course on special relativity, in a way that is appropriate for, and completely accessible to, undergraduate students. We also demonstrate, in a more advanced section aimed at the graduate student studying the Dirac equation and relativistic quantum field theory, that careful consideration of the Thomas rotation will become vital as modern experiments in particle physics continue to move from unpolarized to polarized cross sections.
Student understanding of light as an electromagnetic wave: Relating the formalism to physical phenomena
Authors: Ambrose Bradley S. , Heron Paula R. L. , Vokos Stamatis , McDermott Lillian C.
Published: July 2002

During an investigation of student understanding of physical optics, we found that some serious difficulties that students have with this topic may be due, at least in part, to a lack of understanding of the nature of light as an electromagnetic wave. We therefore decided to look carefully at how students interpret the diagrammatic and mathematical formalism commonly used to represent a plane EM wave. The results of this research have guided the development and modification of tutorials that address some of the difficulties that we identified. These instructional materials are an example of how, within a relatively short time allotment, a curriculum developed on the basis of research can help students relate the concepts and formal representations associated with EM waves to physical phenomena.
Spontaneous speech recognition using a statistical coarticulatory model for the vocal-tract-resonance dynamics
Authors: Deng Li , Ma Jeff
Published: July 2002

A statistical coarticulatory model is presented for spontaneous speech recognition, where knowledge of the dynamic, target-directed behavior in the vocal tract resonance is incorporated into the model design, training, and in likelihood computation. The principal advantage of the new model over the conventional HMM is the use of a compact, internal structure that parsimoniously represents long-span context dependence in the observable domain of speech acoustics without using additional, context-dependent model parameters. The new model is formulated mathematically as a constrained, nonstationary, and nonlinear dynamic system, for which a version of the generalized EM algorithm is developed and implemented for automatically learning the compact set of model parameters. A series of experiments for speech recognition and model synthesis using spontaneous speech data from the Switchboard corpus are reported. The promise of the new model is demonstrated by showing its consistently superior performance over a state-of-the-art benchmark HMM system under controlled experimental conditions. Experiments on model synthesis and analysis shed insight into the mechanism underlying such superiority in terms of the target-directed behavior and of the long-span context-dependence property, both inherent in the designed structure of the new dynamic model of speech.
A computational approach for flow–acoustic coupling in closed side branches
Authors: Radavich Paul M. , Selamet Ahmet , Novak James M.
Published: July 2002

The quarter-wave resonator, which produces a narrow band of high acoustic attenuation at regularly spaced frequency intervals, is a common type of silencer used in ducts. The presence of mean flow in the main duct, however, is likely to promote an interaction between these acoustic resonances and the flow. The coupling for some discrete flow conditions leads to the production of both large wave amplitudes in the side branch and high noise levels in the main duct, thereby transforming the quarter-wave silencer into a noise generator. The present approach employs computational fluid dynamics (CFD) to model this complex interaction between the flow and acoustic resonances at low Mach number by solving the unsteady, turbulent, and compressible Navier–Stokes equations. Comparisons between the present computations and the experiments of Ziada [PVP-Vol. 258, ASME, 35–59 (1993)] for a system with two coaxial side branches show that the method is capable of reproducing the physics of the flow–acoustic coupling and predicting the flow conditions when the coupling occurs. The theory of Howe [IMA J. Appl. Math. 32, 187–209 (1984)] is then employed to determine the location and timing of the acoustic power production during a cycle.
Effects of temporal envelope modulation on acoustic signal recognition in a vocal fish, the plainfin midshipman
Authors: McKibben Jessica R. , Bass Andrew H.
Published: July 2002

Amplitude modulation is an important parameter defining vertebrate acoustic communication signals. Nesting male plainfin midshipman fish, Porichthys notatus, emit simple, long duration hums in which modulation is strikingly absent. Envelope modulation is, however, introduced when the hums of adjacent males overlap to produce acoustic beats. Hums attract gravid females and can be mimicked with continuous tones at the fundamental frequency. While individual hums have flat envelopes, other midshipman signals are amplitude modulated. This study used one-choice playback tests with gravid females to examine the role of envelope modulation in hum recognition. Various pulse train and two-tone beat stimuli resembling natural communication signals were presented individually, and the responses compared to those for continuous pure tones. The effectiveness of pulse trains was graded and depended upon both pulse duration and the ratio of pulse to gap length. Midshipman were sensitive to beat modulations from 0.5 to 10 Hz, with fewer fish approaching the beat than the pure tone. Reducing the degree of modulation increased the effectiveness of beat stimuli. Hence, the lack of modulation in the midshipman’s advertisement call corresponds to the importance of envelope modulation for the categorization of communication signals even in this relatively simple system.
Acoustic characteristics of the piriform fossa in models and humans
Authors: Dang Jianwu , Honda Kiyoshi
Published: July 2002

The piriform fossa forms the bottom part of the pharynx and acts as a pair of side branches of the vocal tract. Because of its obscure form and function, the piriform fossa has usually been neglected in the current speech production models. This study examines the geometric and acoustic characteristics of the piriform fossa by means of MRI-based mechanical modeling, in-vivo experiments and numerical computations. Volumetric MRI data showed that the piriform fossa is 2.1 to 2.9 cm3 in volume and 1.6 to 2.0 cm in depth for four Japanese subjects (three males and one female). The results obtained from mechanical models showed that the piriform fossa contributes strong troughs, i.e., spectral minima, to speech spectra in a region of 4 to 5 kHz. The antiresonances were identified with increasing frequency when water was injected into the piriform fossa of human subjects in in-vivo experiments. Antiresonances obtained from the experiments and simulations were confirmed to be consistent with those in natural speech within 5%. Acoustic measurements and simulations showed that the influence of the piriform fossa extends to the lower vowel formants in addition to the local troughs. This global effect can be explained by the location of the fossa near the glottal end of the vocal tract.
Effects of acoustic trauma on the representation of the vowel /ε/ in cat auditory nerve fibers
Authors: Miller Roger L. , Schilling John R. , Franck Kevin R. , Young Eric D.
Published: July 2002

A population study of cat auditory-nerve fibers was used to characterize the permanent deficits induced by exposure to 110–115 dB SPL, narrow-band noise. Fibers in the region of acoustic trauma (roughly 1–6 kHz) showed a loss of sensitivity at best frequency (BF) of about 50–60 dB and an increased tuning bandwidth. A correlation between weakened two-tone suppression and loss of sensitivity was found for fibers with BFs above 1 kHz. Single-fiber responses to the vowel /ɛ/ were recorded at intensities ranging from near threshold to a maximum of about 110 dB SPL. In normal cochleas, the temporal response patterns show a capture phenomenon, in which the first two formant frequencies dominate the responses at high sound levels among fibers with BFs near the formant frequencies. After acoustic trauma, fibers in the region of threshold shift synchronized to a broad range of the vowel’s harmonics and thus did not show capture by the second formant at any sound level used. The broadband nature of this response is consistent with the broadened tuning observed in the damaged fibers, but may also reflect a weakening of compressive nonlinearities responsible for synchrony capture in the normal cochlea.
The application of geographic spatial analysis in modeling traffic noise propagation away from a freeway
Authors: Bennett John C.
Published: July 2002

This paper demonstrates the use of a geographic information system (GIS) to perform a spatial analysis of traffic noise away from a freeway. The more traditional analysis procedures used by the Federal Highway Administration (FHWA, 1978 and 1982) employ a noise model that is range limited and not designed to handle large-scale topographic variation near a freeway noise source. A digital elevation map of a portion of a freeway in San Diego County that includes a mesa and valley landscape is incorporated into a GIS where a spatial analysis of ray path geometry, substrate, and vegetation is used to evaluate measured noise levels of traffic. Preliminary results indicate that a GIS model of traffic noise provides a more realistic basis for predicting noise impacts, particularly at longer ranges in areas of variable topography.
Maximum likelihood localization of sources propagating in a random media using intensity measurements
Authors: Song Bong-Gee , Ritcey James A. , Ewart Terry E.
Published: July 2002

A statistical signal processing solution is proposed for locating a monochromatic source propagating in a random media. The media is fully parametrized by the normalized scattering strength γ and scaled range X, which depend upon the physics of the media. M independent intensity measurements are observed, each drawn from the generalized gamma distribution. This has been shown by Ewart [J. Acoust. Soc. Am. 86, 1490–1498 (1989)] to describe sources propagating through internal waves in ocean environments. The parameters of the distribution are related to the scattering parameters, γ and X. Maximum likelihood estimation is used to infer X, given the observations and our knowledge of γ. The estimation performance is well-characterized by the Cramer–Rao lower bound (CRLB). The results show that we can estimate range to a precision of about 20%, for ranges up to half the distance to the focus of the medium. Simulation results verify both the normality of the estimates and the validity of the CRLB as a predictor of the estimator precision at these ranges. The practical value of this method will depend on our ability to gather enough independent measurements, and on the accuracy of the statistical models we assume, including prior knowledge of γ. It can be expected to augment other methods such as matched field processing.
Neuronal response to cochlear distortion products in the anteroventral cochlear nucleus of the gerbil
Authors: Faulstich Michael , Kössl Manfred
Published: July 2002

To receive information on the intracochlear magnitude and propagation properties of cochlear distortion products, the neuronal response of AVCN cells to distortion stimuli and the acoustical correlates in the ear canal (DPOAE) were measured for frequencies between 0.7 and 45.3 kHz. Comparison of the growth of neuronal response to a distortion stimulus and the neuronal rate-versus-level function for an externally applied pure tone of equal frequency allowed for an assessment of the intracochlear magnitude of the distortions. AVCN neurons with a characteristic frequency (CF) >1.8 kHz started to respond to the intracochlear distortion stimulus, at primary levels for which the ear-canal level of the corresponding DPOAE was close to the pure-tone threshold of the units. This finding suggests that transmission of sound energy is comparable in the forward and reverse direction, and that mechanical distortions of the cochlea are fully encoded by neurons in the AVCN. For neurons with a CF <1.8 kHz, the intracochlear magnitude of the distortion stimulus appeared to be about 15 to 30 dB higher than the corresponding DPOAE, at the threshold of neuronal response. This discrepancy between intracochlear magnitude of cochlear distortions and their acoustical expression may be explained by high-pass filter action of the middle ear during DPOAE re-emission from the cochlea. A contribution to the observed discrepancy of the type of distortion (cubic versus quadratic) used as stimulus, and possible differences in mechanical frequency processing between the apex and base of the gerbil cochlea, are also discussed. The delay of the neuronal response to an intracochlear distortion stimulus was on average 1.1 ms longer than the neuronal delay to an external pure tone of equal frequency and intensity, most likely stemming from the activation delay of the DPOAE generating mechanisms.
Performance of sinusoidally deformed hydrophone line arrays
Authors: Caveny Deanna M. , Del Balzo Donald R. , Leclere James H. , Ioup George E.
Published: July 2002

It is well known that array deformations can distort beam patterns and introduce bearing errors if the beamformer assumes linearity. It is also known that deformed arrays can resolve left–right ambiguities, provided the shape is known. In this work, these two effects are studied for undamped and damped sinusoidally deformed arrays with small deformation amplitudes in the horizontal (x,y) plane only. By use of fixed arc-length separations along the array, the hydrophone (x,y) coordinates are determined numerically and the error in assuming equal x spacing is summarized for a sample array. Array-response patterns are analyzed for two conditions: (1) when the deformed array shape is assumed linear and (2) when the deformed array shape is known exactly. Degradations resulting from assuming linearity and the ability to resolve left–right ambiguities are discussed in terms of reduced gain, degraded angular resolution, and bearing errors. Shape-unknown signal-gain degradation ranges to 7 dB at broadside, but is less than 1 dB near endfire. For the shape-known case, signal gain for the true peak is greater than signal gain for the ambiguous peak by up to 9 dB for sources at broadside and to just over 2.5 dB for arrivals near endfire.
Forward masking among infant and adult listeners
Authors: Werner Lynne A.
Published: July 2002

Psychophysical forward-masked thresholds were estimated for 3- and 6-month-old infants and for adults. Listeners detected a repeated 1000-Hz probe, with 16-ms rise time, no steady-state duration, and 16-ms fall time. Unmasked thresholds were determined for one group of listeners who were trained to respond when they heard the probe but not at other times. In the masking conditions, each tone burst was preceded by a 100-ms broadband noise masker at 65 dB SPL. Listeners were trained to respond when they heard the probe and masker, but not when they heard the masker alone. The masker–probe interval, Δt, was either 5, 10, 25, or 200 ms. Four groups of subjects listened in the masked conditions, each at one value of Δt. Each listener attempted to complete a block of 32 trials including four probe levels chosen to span the range of expected thresholds. “Group” thresholds, based on average psychometric functions, as well as thresholds for individual listeners, were estimated. Both group and individual thresholds declined with Δt, as expected, for both infants and adults. Infants’ masked thresholds were higher than those of adults, and comparison of masked to unmasked thresholds suggested that infants demonstrate more forward masking than adults, particularly at short Δt. Forward masking appeared to have greater effects on 3-month-olds’ detection than on either 6-month-olds’ or adults’. Compared to adults, 6-month-olds demonstrated more forward masking only for Δt of 5 ms. Thus, susceptibility to forward masking may be nearly mature by 6 months of age.
Compensation strategies for the perturbation of French [u] using a lip tube. II. Perceptual analysis
Authors: Savariaux Christophe , Perrier Pascal , Orliaguet Jean-Pierre , Schwartz Jean-Luc
Published: July 2002

A perceptual analysis of the French vowel [u] produced by 10 speakers under normal and perturbed conditions () is presented which aims at characterizing in the perceptual domain the task of a speaker for this vowel, and, then, at understanding the strategies developed by the speakers to deal with the lip perturbation. Identification and rating tests showed that the French [u] is perceptually fairly well described in the [F1,(F2–F0)] plane, and that the parameter (((F2–F0)+F1)/2) (all frequencies in bark) provides a good overall correlate of the “grave” feature classically used to describe the vowel [u] in all languages. This permitted reanalysis of the behavior of the speakers during the perturbation experiment. Three of them succeed in producing a good [u] in spite of the lip tube, thanks to a combination of limited changes on F1 and (F2–F0), but without producing the strong backward movement of the tongue, which would be necessary to keep the [F1,F2] pattern close to the one measured in normal speech. The only speaker who strongly moved his tongue back and maintained F1 and F2 at low values did not produce a perceptually well-rated [u], but additional tests demonstrate that this gesture allowed him to preserve the most important phonetic features of the French [u], which is primarily a back and rounded vowel. It is concluded that speech production is clearly guided by perceptual requirements, and that the speakers have a good representation of them, even if they are not all able to meet them in perturbed conditions.
Wavelet transforms for bioacoustic signal processing
Authors: Sibul Leon H.
Published: July 2002

Wavelet transforms (WT) are natural tools for analysis of bioacoustic signals. In analysis of transient signals and nonstationary stochastic processes it is important to know not only what are the frequency content transients but when did these transient signals occur. The importance of representation of signals on the time-frequency plane, not only on frequency or time axes, is now widely accepted. Linear time-frequency analysis of transient signals (signals with time-varying frequency content) can be based on short-time Fourier transforms (STFT) and generalized Gabor transforms (GT). Wavelet transform analysis is analogous to STFT and GT analysis, except WTs represent signals on time and scale plane. In time-frequency analysis there is a tradeoff between time and frequency resolution. WTs have the advantage that they have constant time-frequency resolution over a wide frequency range. WT represent constant fractional or constant Q frequency analysis, thus efficiently analyzing a wideband of frequencies. Continuous wavelet transforms are linear transforms that can be inverted. In this tutorial paper basic properties of continuous and discrete wavelet transforms are reviewed, basic issues between Fourier transform techniques are discussed and disadvantages and advantages of WT are pointed out. [Work supported by ONR, Code 333.]
A performance adequate computational model for auditory localization
Authors: Chung Wing , Carlile Simon , Leong Philip
Published: July 2002

A computational model of auditory localization resulting in performance similar to humans is reported. The model incorporates both the monaural and binaural cues available to a human for sound localization. Essential elements used in the simulation of the processes of auditory cue generation and encoding by the nervous system include measured head-related transfer functions (HRTFs), minimum audible field (MAF), and the Patterson–Holdsworth cochlear model. A two-layer feed-forward back-propagation artificial neural network (ANN) was trained to transform the localization cues to a two-dimensional map that gives the direction of the sound source. The model results were compared with (i) the localization performance of the human listener who provided the HRTFs for the model and (ii) the localization performance of a group of 19 other human listeners. The localization accuracy and front–back confusion error rates exhibited by the model were similar to both the single listener and the group results. This suggests that the simulation of the cue generation and extraction processes as well as the model parameters were reasonable approximations to the overall biological processes. The amplitude resolution of the monaural spectral cues was varied and the influence on the model’s performance was determined. The model with 128 cochlear channels required an amplitude resolution of approximately 20 discrete levels for encoding the spectral cue to deliver similar localization performance to the group of human listeners.
Cross-correlation procedures for measuring noise and distortion in AGC hearing aids
Authors: Kates James M.
Published: July 2002

The magnitude-squared coherence function (MSC) has been used to measure noise and distortion in linear and compression hearing aids. However, the MSC will overestimate the distortion in a linear time-varying system such as a compression amplifier. The reduction in coherence caused by varying the gain in an otherwise linear system can be substantial, and can lead to large errors in estimating the distortion present in a compression hearing aid. The effects of gain changes in a linear system can be reduced by measuring the normalized system input–output cross correlation, which emphasizes the variance in the system phase response and deemphasizes the system gain fluctuations. Estimates of the total noise and distortion produced using the MSC, phase variance, and notched-noise measurement techniques are compared for additive noise, clipping distortion, and compression amplification. The MSC is found to give the most accurate results for estimating the noise and distortion in a linear time-invariant system, and the notched noise measurements are the most accurate for a compression system. The phase variance is found to give reasonable measurements for a time-varying gain as long as the system variations are slow relative to the length of the analysis data segments.
Individual differences in speech adaptation to an artificial palate
Authors: Baum Shari R. , McFarland David H.
Published: July 2002

This preliminary investigation examined the ability of individual speakers to adapt to a structural perturbation to the oral environment in the production of [s]. In particular, the experiment explored whether previous evidence of relatively quick adaptation subsequent to intensive practice would be replicated, whether vowel environment would influence the degree of adaptation, whether adaptive strategies would carry over to normal productions and/or similar sounds (i.e., cause negative aftereffects), and whether adaptive strategies developed during the practice phase could be recalled 1 h later. Results of acoustic and perceptual analyses generally revealed improvement after practice, few consistent effects of vowel context, few negative aftereffects, and an absence of quick recall of adaptive strategies. Moreover, extensive individual differences were found in both the degree of initial perturbation and the extent of adaptation. Implications of the results for issues in speech adaptation are briefly discussed.
Auditory and behavioral responses of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) to impulsive sounds resembling distant signatures of underwater explosions
Authors: Finneran James J. , Schlundt Carolyn E. , Carder Donald A. , Clark Joseph A. , Young Jane A. , Gaspin Joel B. , Ridgway Sam H.
Published: July 2002

A behavioral response paradigm was used to measure masked underwater hearing thresholds in two bottlenose dolphins and one beluga whale before and after exposure to impulsive underwater sounds with waveforms resembling distant signatures of underwater explosions. An array of piezoelectric transducers was used to generate impulsive sounds with waveforms approximating those predicted from 5 or 500 kg HBX-1 charges at ranges from 1.5 to 55.6 km. At the conclusion of the study, no temporary shifts in masked-hearing thresholds (MTTSs), defined as a 6-dB or larger increase in threshold over pre-exposure levels, had been observed at the highest impulse level generated (500 kg at 1.7 km, peak pressure 70 kPa); however, disruptions of the animals’ trained behaviors began to occur at exposures corresponding to 5 kg at 9.3 km and 5 kg at 1.5 km for the dolphins and 500 kg at 1.9 km for the beluga whale. These data are the first direct information regarding the effects of distant underwater explosion signatures on the hearing abilities of odontocetes.
A cross-language study of the identification of non-native nasal consonants varying in place of articulation
Authors: Harnsberger James D.
Published: July 2002

Seven listener groups, varying in terms of the nasal consonant inventory of their native language, orthographically labeled and rated a set of naturally produced non-native nasal consonants varying in place of articulation. The seven listener groups included speakers of Malayalam, Marathi, Punjabi, Tamil, Oriya, Bengali, and American English. The stimulus set included bilabial, dental, alveolar, and retroflex nasals from Malayalam, Marathi, and Oriya. The stimulus set and nasal consonant inventories of the seven listener groups were described by both phonemic and allophonic representations. The study was designed to determine the extent to which phonemic and allophonic representations of perceptual categories can be used to predict a listener group’s identification of non-native sounds. The results of the experiment showed that allophonic representations were more successful in predicting the native category that listeners used to label a non-native sound in a majority of trials. However, both representations frequently failed to accurately predict the goodness of fit between a non-native sound and a perceptual category. The results demonstrate that the labeling and rating of non-native stimuli were conditioned by a degree of language-specific phonetic detail that corresponds to perceptually relevant cues to native language contrasts.
Phenotypic differences between Edwardsiella piscicida and Edwardsiella anguillarum isolates in Japan
Authors: Sugiura Hidehiro , Fukunishi Kosuke , Kawakami Hidemasa , Imajoh Masayuki
Published: August 2022

Objective

Edwardsiella tarda has been regarded as the causative agent of edwardsiellosis in cultured marine and freshwater fish species in Japan. Our previous study genetically classified an E. tarda-like isolate from diseased Olive Flounder Paralichthys olivaceus as E. piscicida and that from diseased Red Seabream Pagrus major as E. anguillarum. This study aimed to understand the phenotypic differences between E. piscicida and E. anguillarum.

Methods

Fourteen E. piscicida and seven E. anguillarum isolates were used in this study. The colonies of each isolate were grown on brain–heart infusion agar plates and then subjected to DNA extraction. The extracted DNA was amplified using PCR. carbohydrate fermentation of the isolates was examined using API 50 CH test kits. Moreover, the growth of the two species was examined in defined media. Also, free amino acids in Olive Flounder and Red Seabream sera were detected and quantified via high-performance liquid chromatography–mass spectrometry. Statistical differences in the concentrations of free amino acids were analyzed using Welch's t-tests.

Result

The API 50 CH test revealed that L-arabinose and D-mannitol were fermented by E. anguillarum isolates but not E. piscicida isolates. Furthermore, the growth of E. piscicida and E. anguillarum was reduced in the defined medium without methionine and iron sulfate. The growth of E. piscicida was reduced in the defined medium without phenylalanine, tyrosine, alanine, or nicotinic acid, whereas the growth of E. anguillarum was reduced in the defined medium without serine, cysteine, leucine, threonine, or isoleucine. Tyrosine and alanine were present in higher concentrations in the Olive Flounder serum, whereas threonine and isoleucine were present in higher concentrations in the Red Seabream serum, suggesting favorable growth conditions for E. piscicida and E. anguillarum.

Conclusion

This study characterizes a minimal defined medium that can be used for developing vaccines against E. piscicida and E. anguillarum.
Structure and Luminescence Properties of Ho:(Y1−xScx)2O3 Ceramics
Authors: Bai Yuchen , Zhao Hongyang , Xu Xiaodong , Zhang Jian , Wang Shiwei
Published: August 2022

Ho‐doped sesquioxide is one of the most important laser gain media for 2 micron wavelength band laser applications. It is hard to be transparent by sintering because of its high melting point. Herein, the structural and spectral properties of 0.5 at% Ho:(Y1−xScx)2O3 (x = 0, 0.3, 0.5, 0.7, 1.0) ceramics fabricated by vacuum pressureless sintering are studied. Then, 0.5 at% Ho:(Y0.7Sc0.3)2O3 transparent ceramics with 1.0 at% ZrO2 as a sintering aid are prepared by vacuum pressureless presintering (1680 °C for 4 h) combined with hot isostatic pressing sintering treatment (1600 °C/190 MPa for 3 h). The transmittance of Ho:(Y0.7Sc0.3)2O3 ceramic reaches 80.8% at 1100 nm (6 mm in thickness), which is close to its theoretic value. The addition of ZrO2 has no significant influence on spectroscopic properties of 0.5 at% Ho:(Y0.7Sc0.3)2O3 ceramics.
Stably Immobilizing Sub‐3 nm High‐Entropy Pt Alloy Nanocrystals in Porous Carbon as Durable Oxygen Reduction Electrocatalyst
Authors: Zhang Wenjing , Feng Xin , Mao Zhan Xin , Li Jing , Wei Zidong
Published: August 2022

Immobilizing ultrafine high‐entropy Pt alloy nanocrystals (HENs) in porous carbon (PC) with strong interface interaction, which is crucial to efficient and durable oxygen reduction reaction (ORR), remains a challenge. In this study, an anchoring‐carbonization strategy for strongly bonding sub‐3 nm HENs in ordered mesoporous carbon is reported. When heating the orderly assembled composites containing hydrophobic organometallic precursors, structure directing agent F127, and hydrophilic resol, F127 is first removed at moderate temperature region, leading to reduced metallic species directly anchored on partially carbonized resol framework. Then along further temperature increase, in situ carbonization of resol around the HENs, enables more effective plane bonding rather than a single point contact of HENs with carbon. It not only enhances the anchor strength, but also inhibits migration and size growth of HENs along the subsequent high‐temperature carbonization. As a result, senary, septenary, octonary, and denary Pt‐based HENs with average nanocrystal sizes of 2.2, 2.6, 2.9, and 2.8 nm, respectively, are successfully imbedded into porous carbon. In electrocatalytic ORR, porous carbon‐supported senary Pt‐based HENs (6‐HENs/PC) exhibit superior activity and durability, representing a promising electrocatalyst. This strategy allows for the preparation of a range of ultrafine HENs strongly loaded on porous carbon for wide applications.
Efficient and Stable 3D/2D Perovskite Solar Cells through Vertical Heterostructures with (BA)4AgBiBr8 Nanosheets
Authors: Zhao Dan , Gao Danpeng , Wu Xin , Li Bo , Zhang Shoufeng , Li Zhen , Wang Qi , Wu Zongxiao , Zhang Chunlei , Choy Wallace C. H. , Zhong Xiaoyan , He Qiyuan , Zhu Zonglong
Published: August 2022

Perovskite solar cells (PVSCs) have drawn great attention due to their high processability and superior photovoltaic properties. However, their further development is often hindered by severe nonradiative recombination at interfaces that decreases power conversion efficiency (PCE). To this end, a facile strategy to construct a 3D/2D vertical heterostructure to reduce the energy loss in PVSCs is developed. The heterostructure is contrived through the van der Waals integration of 2D perovskite ((BA)4AgBiBr8) nanosheets onto the surface of 3D‐FAPbI3‐based perovskites. The large bandgap of (BA)4AgBiBr8 enables the formation of type‐I heterojunction with 3D‐FAPbI3‐based perovskites, which serves as a barrier to suppress the trap‐assisted recombination at the interface. As a result, a satisfying PCE of 24.48% is achieved with an improved open‐circuit voltage (VOC) from 1.13 to 1.17 V. Moreover, the 2D perovskite nanosheets can effectively mitigate the iodide ion diffusion from perovskite to the metal electrode, hence enhancing the device stability. 3D/2D architectured devices retain ≈90% of their initial PCE under continuous illumination or heating after 1000 h, which are superior to 3D‐based devices. This work provides an effective and controllable strategy to construct 3D/2D vertical heterostructure to simultaneously boost the efficiency and stability of PVSCs.
Sequential Drug Release Achieved with Dual‐Compartment Microcontainers: Toward Combination Therapy
Authors: Christfort Juliane Fjelrad , Milián‐Guimerá Carmen , Kamguyan Khorshid , Hansen Morten Borre , Hagner Nielsen Line , Thamdrup Lasse Højlund Eklund , Zór Kinga , Boisen Anja
Published: August 2022

Combination drug therapy is commonly used to treat cancer, diabetes, cardiovascular conditions, and infections. However, these therapies face challenges associated with patient compliance and toxicology. Over the past decades, microdevices have emerged as a promising candidate for oral delivery allowing for targeted drug delivery with a tunable drug release. In the present work, engineered and monodisperse dual‐compartment microdevices are developed to achieve a physical separation of two drugs followed by a sequential release in the gastrointestinal tract. As proof‐of‐concept, the compartments are sealed with two pH‐sensitive polymers of different thicknesses to control the sequential release of propranolol and furosemide. In vitro release studies and in vivo absorption studies in rats confirm a sequential drug release from the two compartments. Unlike other proposed approaches, it is highly advantageous that the drugs can be loaded directly as powders, and that their release can be tuned via optimized coatings to achieve the desired release and absorption profiles. Conclusively, this study lays a strong foundation for the future use of microdevices to enable co‐delivery of drugs followed by a sequential release in close proximity in the gastrointestinal tract.
Automated Recognition of Plasmodium falciparum Parasites from Portable Blood Levitation Imaging
Authors: Deshmukh Shreya S. , Byaruhanga Oswald , Tumwebaze Patrick , Akin Demir , Greenhouse Bryan , Egan Elizabeth S. , Demirci Utkan
Published: August 2022

In many malaria‐endemic regions, current detection tools are inadequate in diagnostic accuracy and accessibility. To meet the need for direct, phenotypic, and automated malaria parasite detection in field settings, a portable platform to process, image, and analyze whole blood to detect Plasmodium falciparum parasites, is developed. The liberated parasites from lysed red blood cells suspended in a magnetic field are accurately detected using this cellphone‐interfaced, battery‐operated imaging platform. A validation study is conducted at Ugandan clinics, processing 45 malaria‐negative and 36 malaria‐positive clinical samples without external infrastructure. Texture and morphology features are extracted from the sample images, and a random forest classifier is trained to assess infection status, achieving 100% sensitivity and 91% specificity against gold‐standard measurements (microscopy and polymerase chain reaction), and limit of detection of 31 parasites per µL. This rapid and user‐friendly platform enables portable parasite detection and can support malaria diagnostics, surveillance, and research in resource‐constrained environments.
Catalytic Disproportionation for Suppressing Polysulfide Shuttle in Li–S Pouch Cells: Beyond Adsorption Interactions
Authors: Lin Yilong , Zhou Yecheng , Huang Sheng , Xiao Min , Han Dongmei , Qin Jiaxiang , Wang Shuanjin , Meng Yuezhong
Published: August 2022

Addressing the lithium polysulfide shuttle is critical for the high‐energy‐density lithium–sulfur pouch cells in practical applications, especially under high sulfur loading and lean electrolyte conditions. In contrast to previously reported heterogeneous adsorption catalysis within cathode or separator with slow catalytic kinetics and limited adsorption area, herein, lithium difluorophosphate (LiPO2F2) is demonstrated as a homogeneous catalyst in electrolyte which mitigates polysulfide diffusion. The Li–S pouch cell with LiPO2F2 in the electrolyte has record‐breaking shelving stability of two months, significantly improved capacity retention from 37.0% to 81.4% after long cycling, and electrical‐car‐level energy density over 400 Wh kg−1. A minimal amount of 1 wt% LiPO2F2 tends to facilitate lithium polysulfide disproportionation on the S/C cathode instead of in the electrolyte, which initiates the fast transformation of soluble lithium polysulfide to insoluble solid S8 and Li2S2/Li2S. The reliable mechanism of polysulfide disproportionation via biradicals is further proposed by both density functional theory calculation and experiments. To best of the authors’ knowledge, this is the first report on mechanism of polysulfide disproportionation via biradical intermediates. It is believed that this new insight into homogeneous catalytic mechanisms in electrolytes may pave the way for the commercialization of high‐energy‐density Li–S batteries.
Biomass‐derived Sugar Ionic Liquid as a Sustainable Organocatalyst: An Efficient Synthesis of Functionalized Dihydropyrano Coumarins
Authors: Garg Pooja , Reddy Sabbasani Rajasekhara
Published: August 2022

Multi‐component reaction approach was utilized in the synthesis of dihydropyrano coumarins under mild reaction conditions. Biomass derived carbohydrate was used as sugar source for the formation of D‐ribose based sugar ionic liquid. The developed catalyst catalyzed efficient synthesis of these hetero atom functionalized compounds. A wide range of substrates were prepared with substituted aliphatic or aromatic aldehydes. Substitution in phenyl ring did not affect the rate of reaction much. All compounds were obtained in good to excellent yield up to 76–92%. The recyclablity of the catalyst was also examined.
Accessing hearing‐health services for deaf and hard‐of‐hearing children during the COVID‐19 pandemic: Parent and child perspectives
Authors: Mardinli Ahmed , Weerasuriya Rona , Gillespie Alanna , Smith Libby , Sung Valerie
Published: August 2022

To describe hearing‐health service use, especially use of telehealth, during the early stages of the COVID‐19 pandemic in deaf/hard‐of‐hearing children. In 2020, the Victorian Childhood Hearing Longitudinal Databank surveyed 497 (61.6%) families of deaf/hard‐of‐hearing children aged 0.4–19.6 years, with 449 (90.3%) providing quantitative data and 336 (67.6%) providing free‐text comments about COVID‐19's impact on service use and access. We summarised quantitative data using descriptive statistics and analysed free‐text responses using inductive and deductive reasoning. Of the 1152 services families used during the pandemic, 711 (62%) were accessed via telehealth. Parents reported several challenges and facilitators of service access during the pandemic, particularly regarding telehealth. Parents reported that their child found telehealth appointments more difficult (347/665, 52.1%) and of worse quality (363/649, 55.9%) compared to in‐person. These difficulties were more evident in pre‐school than school‐age children. Consideration of these factors when implementing telehealth practice beyond the pandemic would improve family experiences, ensuring quality of care.
Modular Construction of Heterobiaryl Atropisomers and Axially Chiral Styrenes via All‐Carbon Tetrasubstituted VQMs
Authors: Gou Bo‐Bo , Tang Yue , Lin Yan‐Hong , Yu Le , Jian Qing‐Song , Sun Huai‐Ri , Chen Jie , Zhou Ling
Published: August 2022

Here we report a new type of chiral all‐carbon tetrasubstituted VQMs generated via chiral phosphoric acids catalyzed nucleophilic addition of 2‐alkynylnaphthols too‐quinone methides or imines, which can be captured intramolecularly as a result of cycloaddition reaction. A new class of naphthyl‐2H‐chromenes bearing axially and centrally chiral elements and axially chiral quinone‐naphthols were prepared efficiently with good to excellent yields, diastereoselectivities and enantioselectivities. Noteworthy, the enantioselective cycloaddition of alkynylnaphthols witho‐quinone methides proceeded via a [2+2] cycloaddition, followed by a retro‐4π‐electrocyclization and a 6π re‐cyclization. While the cycloaddition of alkynylnaphthols with imines proceeded via a sequential [2+4] cycloaddition and an auto oxidation reaction. Moreover, the obtained axially chiral naphthols can be converted into valuable phosphine ligands and other functional molecules.