bluuebunny/crossref_metadata_2025 huggingface dataset:
The recognition of isolated words and words in sentences: Individual variability in the use of sentence context
Authors: Grant Ken W. , Seitz Philip F.
Published: July 2002

Auditory–Visual (AV) speech recognition is influenced by at least three primary factors: (1) the ability to extract auditory (A) and visual (V) cues; (2) the ability to integrate these cues into a single linguistic object; and (3) the ability to use semantic and syntactic constraints available within the context of a sentence. In this study, the ability of hearing-impaired individuals to recognize bandpass filtered words presented in isolation and in meaningful sentences was evaluated. Sentence materials were constructed by concatenating digitized productions of isolated words to ensure physical equivalence among the test items in the two conditions. Formulae for calculating k factors [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101–114 (1988)], which relate scores for words and sentences, were applied to individual subject data obtained at three levels of isolated word-recognition performance approximating 30%, 50%, and 70% correct. In addition, A, V, and AV sentence recognition in noise was evaluated using natural productions of fluent speech. Two main issues are addressed: (1) the effects of intelligibility on estimates of k within individual subjects; and (2) the relations between individual estimates of k and sentence recognition in noise as a function of presentation modality. [Work supported by NIH Grant DC00792.]
Apparent movement of sounds originating in different hemifields
Authors: Green Micah , Gallegos Jose A. , Perrott David R. , Lin Nick
Published: July 2002

In the current study, five participants were asked to describe the sequence of two sounds that originated from the front and back hemifield, relative to the subject. The stimuli were 50-ms broadband noise pulses presented at an A-weighted sound-pressure level of 70 dB. Across sessions, the distance between speakers varied from 78 to 234 in. Within sessions, the delay between the onset (interstimulus onset interval or ISOI) of the first and second speakers varied from 4 to 150 ms. Both ISOI and inter-speaker distance affected the participant performance on the task [f(8,32)=8.21, p<0.001]. It is clear from these results that continuous movement originating from the front and back hemifields [f(2,8)=14.06, p<0.001] occurs over the same time intervals as on the horizontal azimuth. Implications for motion research will also discussed.
Forward modeling techniques for range-dependent problems
Authors: Collins Michael D. , Lingevitch Joseph F. , Siegmann William L.
Published: July 2002

This paper will discuss progress that has been made in modeling range-dependent propagation problems and outline some of the unresolved problems. The parabolic equation (PE) method has proven to be the most useful approach for solving range-dependent problems. Finite-difference solutions and range-dependent mode and spectral solutions are useful for confirming the accuracy of PE solutions and for solving problems that PE techniques cannot handle (or cannot yet handle). Combinations of these approaches, such as the coupled mode PE, are also useful. In the mid 1980s, it was widely believed that there was not much left to do in propagation modeling. The amount of work that has been done in the past decade or so is evidence of how shortsighted this view was. Although there now exist accurate and efficient techniques for solving a wide variety of range-dependent problems, there still remain important problems to be solved. [Work supported by ONR.]
Two-dimensional acoustic field measurements in a complex, shallow-water waveguide
Authors: Connor Laurence N. , Frisk George V. , Becker Kyle M. , Sellers Cynthia J.
Published: July 2002

A shallow-water acoustics modal mapping experiment (MOMAX) was conducted in March 1997 in the vicinity of the East Coast STRATAFORM site. An acoustic modal field was established in a shallow-water environment using fixed and drifting sources radiating several pure tones in the range 50–300 Hz. The field was then densely sampled on a horizontal plane at midwater depth using freely drifting buoys equipped with suspended hydrophones and a radio telemetric link to the ship for data acquisition. GPS and acoustic navigation were used on each buoy for precise spatial tracking to a maximum range of 10 km. An overview of the experiment is presented emphasizing buoy configuration and drift paths, signal processing, and acoustic field mapping. Specific buoy deployments will be examined with regard to the lateral variability of the acoustic field using data obtained from the two-dimensional buoy drift tracks. [Work supported by ONR.]
Modal evolution in a three-dimensionally varying shallow-water waveguide
Authors: Becker Kyle M. , Frisk George V. , Connor Laurence N.
Published: July 2002

Theory shows that the wave-number spectrum of a propagating normal-mode field is a function of position for a complex, shallow-water waveguide whose acoustic properties vary in three spatial dimensions. To demonstrate these effects, a modal mapping experiment (MOMAX) was conducted in the vicinity of the East Coast STRATAFORM site. Using both fixed and drifting source configurations, several pure tones in the range 50–300 Hz were transmitted to a field of freely drifting buoys, each containing a hydrophone, GPS and acoustic navigation, and radio telemetry. The resulting two-dimensional, synthetic aperture planar array can then be used to determine the evolution of the normal modes with position. By measuring the spatially varying spectral content of the modal field, propagation characteristics of the waveguide may then be inferred. Preliminary results will be presented for different source and buoy configurations demonstrating modal evolution as a function of position. Supporting environmental and model data will also be presented and correlated with the experimental results. [Work supported by ONR.]
Submeter range determination in an ocean environment using differential moving-source kinematic GPS software
Authors: Doutt James A. , von der Heydt Keith , Eck Calvert , Connor Laurence N. , Cosandier Darren , Martell Hugh
Published: July 2002

A relative accuracy of about 1 m in range between a ship-towed sound source and drifting buoys was required for the analysis of data from the MOMAX shallow-water acoustics experiment performed off the New Jersey coast in March 1997. The maximum separation between the ship and the buoys was less than 10 km. Single-frequency GPS receivers providing both code and carrier phase information were installed on the ship and the buoys, and their outputs were recorded for postprocessing at sea. Differential moving-source kinematic software was used to determine the ranges between the ship and the buoys to submeter accuracy. [Work supported by ONR.]
Sound source segregation using the inter-channel differences in both intensity and phase
Authors: Aoki Mariko , Aoki Shigeaki
Published: July 2002

A method is proposed for segregating sounds from multiple sources recorded on a two-channel system. It uses the differences in both intensity and phase, between the channels. In addition, the relation between frequency resolution and sound quality of the proposed method is examined. In the tests, three pairs of mixed sounds were used, namely, male speech with female speech, two kinds of female speech (the same person with different phrases), and a cock’s call with female speech. Frequency resolution was varied between 5 and 80 Hz. In the subjective test, subjects listened to the original sound plus sounds segregated at five different resolutions: 5, 10, 20, 40, and 80 Hz. Then they estimated the quality of these sounds on a five-point scale. Moreover, the correlation coefficient between the original sound and each segregated sound is discussed. In the case of a human voice, it is determined that the optimal frequency resolution is 10 or 20 Hz. The interesting fact is that the optimal frequency resolution was not the highest. Compared with the human voice, lower frequency resolution may be enough to segregate a cock’s call.
Transmission loss measurement in time domain using an impulse technique in ducts
Authors: Cherman Andre L. , Tenenbaum Roberto A.
Published: July 2002

The method proposed is an option to the one described by ISO-140, which needs two reverberant chambers. It consists of a duct 3 m long with a cutoff frequency around 1300 Hz, with a loudspeaker at one end and an anechoic termination at the other. The sample is placed 1 m from the loudspeaker and two microphones are placed around 500 mm from the sample, the first between the loudspeaker and the sample and the second between the sample and the anechoic termination. An impulse is generated and captured at microphone 1 as the incident pulse at the sample and at microphone 2 as the transmitted pulse through the sample. The impulse size is controlled in order to have enough energy in the frequency range desired and not to be too long to mix with the pulse reflected by the sample. In the frequency domain, the energy difference between the signals is compared with the mass law. The ultimate goal of this research is achieving a simple technique for evaluation of transmission loss in multilayered partitions.
Near-field acoustical holography—interior problems
Authors: Williams Earl G.
Published: July 2002

Near-field acoustical holography (NAH) provides a practical solution to a challenging inverse problem: Calculation of the normal velocity on the surface of a vibrator from the pressure field measured in the acoustic near field of the vibrating surface. Furthermore, NAH uses this same pressure measurement to compute the pressure field at the surface, and throughout the volume of interest. Thus structural vibration and acoustic radiation are reconstructed from a single pressure-array measurement. NAH has been used extensively throughout the years to study the vibration, radiation, and scattering applied to exterior problems, in particular, plates and cylinders. Recent applications, however, have been for interior problems in which the vibrations of the walls surrounding a cavity, as well as the pressure field throughout the cavity, are determined from a two-dimensional, conformal array interior pressure measurement. The aircraft fuselage is a good example of recent applications. Recent research is poised to solve the inverse problem for partially correlated noise sources. This research centers on a spherical measurement antenna for the interior problem, with the inversion relying on decomposition into spherical harmonics along with very fast numerical quadrature algorithms. Most current in this approach is the use of analytic continuation to translate the measured field to a different origin, without the need for further measurement.
On energy-conserving boundary conditions for parabolic wave equations
Authors: Godin Oleg A.
Published: July 2002

Realistic description of sound interaction with the ocean bottom requires environmental models having piecewise-continuous dependence of their parameters on position. For a boundary-value problem to be well posed for a parabolic equation (PE), unlike the wave equation, type, and even the number of boundary conditions (BCs) to be imposed at an interface, depends on the interface geometry and the PE itself. In this paper, the boundary conditions at staircase and sloping interfaces are considered for a class of PEs for which the operator square root is approximated by a rational function. Boundary conditions are derived from the PEs themselves thereby ensuring consistency between the equation and the BCs. In particular, energy-conserving PEs produce energy-conserving BCs. Physically, this procedure can be viewed as the substitution of an interface by an infinitesimally thin transition layer. The existence and uniqueness of solutions for the boundary-value problem for a wide-angle PE in the presence of interfaces are both illustrated by considering plane-wave reflection and transmission. Moreover, this fundamental problem provides insight into asymptotic accuracy of the parabolic approximation in media with piecewise-continuous parameters. [Work supported by NSERC.]
Simulated wave propagation in elastic environmental flat and sloping waveguides by a finite length ping time-dependent ray trace model
Authors: White Elmer
Published: July 2002

A finite length ping ray trace program (FLPRT) has been extended which is now capable of simulating time-dependent wave motion in a complicated elastic bathymetric waveguide. From the original concept of sound waves being generated from an infinite set of point sources, FLPRT expands a finite set into the following ray theory including shear and compression logic in a half-space. Wave propagation is demonstrated in a constant velocity shallow-ocean environment for both flat and sloping bathymetries. Not only is the objective to compare the model-generated transmission loss calculations against those computed by EFEPE, an elastic parabolic equation model by Collins of ARL, but also show the time-generated path of the acoustic waves in both cases. Narrow angle-generated pings show nonmodal characteristics than those generated by wide-angle pulses which exhibit fluctuating waves predicted by normal mode theory. As in all cases, adiabaticity is assumed within each very small incremental time step. A 3- to 5-min videotape will be shown on a VCR demonstrating wave motion in the presence of a flat and sloping wedge half-space exhibiting both shear and compressional waves on the half-spaces.
Concert hall design: A consultant’s perspective and retrospective
Authors: Jaffe J. Christopher
Published: July 2002

Architectural environments for symphonic performances can perhaps be described as one of the most complex problems in physical acoustics due to the multiplicity of sound source–path–receiver systems present in listening spaces. On the other hand, people performed and enjoyed listening to music in architectural and outdoor spaces long before the development of architectural acoustics as a scientific discipline and well before there were acoustical consultants. This paper describes one practitioner’s historical perspective and analysis of the problem as it relates to public concert hall design and musical performance over the last several centuries and how the interrelationship between the two has actually fashioned the traditional symphonic environment. Based on this analysis, a methodology will be discussed to successfully replicate traditional symphonic environments utilizing psychoacoustic rather than geometric guidelines. The results of applying this methodology in a variety of building types over a period of 40 years, e.g., concert halls, recital halls, music pavillions, multiuse halls, etc., will be discussed. Both physical and electroacoustical solutions will be presented to support the author’s original analytic premise.
Real-time sonar classification of proud and buried targets using dolphinlike echolocation signals
Authors: Shizumura Reid H. , Au Whitlow W. L. , Moons Gerald C. , Nachtigall Paul E. , Roitblat Herbert L. , Hicks Robert C.
Published: July 2002

A broadband active sonar system using dolphinlike echolocation signals and biologically inspired signal processing algorithms was developed to classify proud and buried targets in real time. A dolphin simulator transducer was attached to a bottom-crawling remotely operated vehicle and used to transmit a dolphin click (120-kHz center frequency, 39-kHz bandwidth, 50-μs duration) through seawater. Reflected target echoes were received and transmitted via cable to a shore-based computer system where the echoes were digitized at 1 MHz and subsequently processed. Two time-frequency representations of the echoes, one based on the short-time Fourier transform and the other on the Morlet wavelet, were processed in a hierarchical neural network system to derive target classifications. Echolocation returns were collected from six objects (cast iron pot, stainless steel sphere, glass jar, concrete tile, and coral rock) that were placed either on the ocean bottom or buried by bottom sediment. Echoes were separated into three target categories: (1) cast iron pot; (2) stainless steel sphere; and (3) a miscellaneous category consisting of the remaining four objects. Following supervised neural network training, the system was able to correctly identify 74%, 97%, and 88% of the category 1, 2, and 3 test echoes.
Spectral integration and the detection of tones in modulated and unmodulated noise
Authors: Bacon Sid. P. , Grimault Nicolas , Lee Jungmee
Published: July 2002

The intent of the present study was to determine whether spectral integration is similar in modulated and unmodulated noise. The signal consisted of one sinusoid of a triplet, or all three sinusoids together. Four sets of triplets were used. The masker consisted of one or three 100-Hz-wide bands of noise centered at the sinusoidal component(s) of the signal. They were unmodulated or sinusoidally amplitude modulated (in phase) at a rate of 8 Hz and a depth of 1.0. Thresholds were measured adaptively for each sinusoid in a triplet, and then for all three together, with the relative level of each determined by the threshold differences when measured individually. In unmodulated noise, the improvement in threshold (from one to three sinusoids) was about 2 dB, consistent with a √3 improvement. In modulated noise, however, the improvement was often greater than that (5 dB). This greater improvement could not be explained by shallower psychometric functions in the modulated condition, as the psychometric functions for the detection of the individual sinusoids were similar for both backgrounds. Instead, it is likely due to the comodulated nature of the three masker bands. [Work supported by NIDCD.]
Effects of fine structure on onset behavior of distortion products in humans
Authors: Talmadge Carrick L. , Long Glenis R. , Tubis Arnold
Published: July 2002

There is accumulating evidence that the fine structure of distortion product otoacoustic emissions (DPOAEs) in humans originates from an interference between two cochlear sources, one at the ‘‘overlap’’ site of the two primaries, and the other at the best frequency for the DPOAE. It is shown that the DPOAE onset behavior measured in humans, after the turn on of an external tone, is consistent with previous evidence for a ‘‘two source’’ origin of DPOAE fine structure [reviewed in Mills, J. Acoust. Soc. Am. 102, 413–429 (1997)]. A variation of Whitehead’s methodology [J. Acoust. Soc. Am. 100, 1663–1679 (1996)] was used to measure the initial DPOAE buildup. The f1 primary was on continuously for a given measurement and the f2 primary was pulsed (square wave, 50% duty cycle) at a rate of 5 Hz. The DPOAE had an initial buildup, followed either by further growth of the DPOAE, when the DPOAE frequency was near a fine-structure maximum, or by decay of the DPOAE, when the DPOAE frequency was near a fine-structure minimum. This pattern of secondary growth/decay is shown to be further evidence favoring the two-source model of DPOAE fine structure.
Labeling a speech database with landmarks and features
Authors: Choi Jeung-Yoon , Chuang Erika , Gow David , Kwong Katherine , Shattuck-Hufnagel Stefanie , Stevens Kenneth , Zhang Yong
Published: July 2002

A database of utterances has been labeled for acoustically salient landmarks and for phonetic features. The landmarks locate syllabic nuclei, glide midpoints, and acoustic discontinuities at the narrowing or releasing of consonantal constrictions. The consonantal landmarks are labeled with values of the articulator-free features (e.g., [continuant] and [sonorant]), and values of articulator-bound features are recorded at each landmark based on acoustic evidence near the landmark. These features specify, for example, the major articulator and its placement, as well as the activity of secondary articulators such as the glottis and the soft palate. Conventions have been developed for labeling reduced vowels, syllabic consonants, glottal stops, consonant sequences in which closures or releases are not acoustically marked, etc. The labeled database is being used for two purposes: (1) to provide a documentation of instances in which the acoustic/articulatory representation of an utterance deviates from the underlying feature-based lexical representation and (2) to train and to test signal-processing algorithms that are being developed to locate the landmarks and to identify the features attached to these landmarks. An advantage of this labeling method is that it gives a more fine-grained phonologically-relevant representation of an utterance than a conventional labeling in terms of phonetic symbols. [Supported in part by NIH Grant No. DC02978.]
Experiments on bit-rate reduction for orthophony signals
Authors: Monsalve Caballero Ana M.
Published: July 2002

Orthophony is the art of recording an acoustical sound field from a room and the reproduction of it by means of loudspeakers. For the reproduction of the signals, the simplest method is to use a transference matrix with the signals. The problem of the matrices is the sizes that they have, because they usually present dimensions too difficult to transmit or/and store. A way to solve the problem is using bit-rate reduction. Based on orthophony signals recorded in the studio of the institute of KW (Kommunikationswissenschaft) of the Technical University in Berlin and their corresponding matrices, experiments were accomplished for the reduction using MATLAB since it facilitates especially the use of matrices. The behavior of the different methods with different signal types (for example, speech, music, and noise) was observed and analyzed. The results are presented in this work. [This work was supported by Professor M. Krause, Institute of KW. Tech. Univ. of Berlin, Germany.]
Recent simulations in computational aeroacoustics
Authors: Morris Philip J.
Published: July 2002

Computational aeroacoustics involves the direct simulation of noise production and radiation from unsteady flows. Its application to problems of practical interest has depended on both algorithm development and advances in computer technology. This paper presents some recent computational aeroacoustics calculations in several different areas. In each case parallel computations are performed to improve efficiency. A new methodology for the numerical simulation of high-speed jet noise is described. It is based on a separation of the instantaneous flow variables into time-averaged and disturbance components. The disturbances are obtained from a three-dimensional, time-dependent, compressible flow simulation. Results are presented for the effects of Mach number and temperature on jet noise. In the simulation of broadband noise from rotors and propellers, a key component is the noise generated by the interaction of a vortical gust with an airfoil. Simulations are described for such an interaction including studies of the effect of airfoil shape and loading. Finally, some examples of the simulation of acoustic scattering in both two and three dimensions from complex geometry bodies in nonuniform flow are described. A discussion of the choice of algorithms, including discretization, boundary treatments, artificial dissipation, and steady-state computations, is provided. [Work supported by NASA.]
Drop and bubble dynamics investigations on Earth and in low gravity using ultrasonics
Authors: Trinh Eugene H.
Published: July 2002

Two ultrasonic devices for the positioning and the remote manipulation of free drops and bubbles have been used during the recent STS-94 Spacelab flight. One apparatus is designed to levitate or to position single or a small number of individual droplets in air, to induce drop shape oscillations, and to control the residual drop rotation. Implementation in low gravity has allowed the measurement of droplet dynamics and rotational stability in the absence of the overwhelming constraint imposed by the high-intensity ultrasonic field required for levitation on Earth. The second apparatus permits the trapping or positioning of gas bubbles in a water-filled resonant cell with a square cross section. Confirming earlier results from a previous flight experiment, it was found that gravity plays a determining part in the stable centering of bubbles larger than resonant size. Both devices operate at about 22.5 kHz and allow the monitoring of the drop or bubble motion through the detection of scattered light from a collimated diode laser beam illuminating the fluid particles. These investigations are low cost, they are built from commercially available components, and they are manually operated by crew members in the Middeck/Spacelab Glovebox facility. [Work funded by NASA.]
Hill-type ultrasonic relaxation spectra of liquids
Authors: Menzel K. , Rupprecht A. , Kaatze U.
Published: July 2002

The Hill relaxation spectral function, originally designed for the description of dielectric relaxation spectra, has been applied to a variety of sonic attenuation spectra. Both theoretical models and measured broadband spectra have been considered. It was found that the Hill function can be favorably used to represent the acoustic relaxation properties of critically demixing liquids but also of such liquid systems that show precritical behavior. The Hill spectral function also complies with the thermal and viscoelastic boundary effects in suspensions and emulsions, with the special absorption characteristics of surfactant solutions with high critical micelle concentration, and with effects of cluster formation in solutions of transition metal halides. Empirical relations between the relaxation time distribution parameters of the Hill function and characteristics of theoretical models are displayed.
A boundary integral equation method for two-dimensional acoustic scattering problems
Authors: Yang S. A.
Published: July 2002

This work formulates the singularity-free integral equations to study 2-D acoustic scattering problems. To avert the nonuniqueness difficulties, Burton’s and Burton and Miller’s methods are employed to solve the Dirichlet and Neumann problems, respectively. The surface Helmholtz integral equations and their normal derivative equations in bounded form are derived. The weakly singular integrals are desingularized by subtracting a term from the integrand and adding it back with an exact value. Depending on the relevant problem, the additional integral can finally be either expressed in an explicit form or transformed to form a surface source distribution of the related equipotential body. The hypersingular kernel is desingularized further using some properties of an interior Laplace problem. The new formulations are advantageous in that they can be computed by directly using standard quadrature formulas. Also discussed is the Γ-contour, a unique feature of 2-D problems. Instead of dividing the boundary surface into several small elements, a parametric representation of a 2-D boundary curve is further proposed to facilitate a global numerical implementation. Calculations consist of acoustic scattering by a hard and a soft circular cylinder, respectively. Comparing the numerical results with the exact solutions demonstrates the proposed method’s effectiveness.
Order tracking using the Vold–Kalman tracking filter
Authors: Gade Svend , Herlufsen Henrik , Konstantin-Hansen Hans
Published: July 2002

The Vold–Kalman filter allows for the high-performance simultaneous tracking of orders in systems with multiple independent axles. The interactions associated with close and crossing orders give rise to beating and complex psychoacoustic phenomena. With this new filter and using multiple tachometer references, waveforms as well as amplitude and phase may be extracted without the beating interactions. The Vold–Kalman filter provides several filter shapes for optimum resolution and stopband suppression. Orders extracted as waveforms have no phase bias, and may hence be used in synthesis and tailoring. The input to Vold–Kalman filtering is time history data. The class of algorithms based on Kalman filters shows no data between preselected orders, but has fine resolution, and is independent of slew rates. The calculation speed may be an issue if a large number of orders is to be extracted. This paper shows an example of the various steps of order tracking using the Vold–Kalman method applied on a simple single-shaft motor. Filter shapes are discussed and an example of decoupling of orders from a multishaft system is demonstrated. The Vold–Kalman filter is implemented in PULSE, the Brüel & Kjær Multianalysis System.
The use of neural networks to classify echolocation calls of bats
Authors: Burnett Stephen C. , Masters W. Mitchell
Published: July 2002

The echolocation calls of bats contain substantial information about the animal producing the call. Previous studies have used discriminant function analysis (DFA) to classify calls to individual, to calling situation, to age, and to sex. DFA requires that the number of groups in the sample be known beforehand, and thus cannot be used to determine the group structure of novel sets of data. Echolocation calls (described by a variety of frequency, time, and amplitude variables) were given as inputs to artificial neural networks. The networks attempted to classify the calls without prior knowledge of group composition. A self-organizing map (SOM) neural network was used to estimate the number of bats that produced the set of calls on the basis of the variables describing the calls. Results suggest that this approach may yield a reasonable estimate of the number of bats in the sample even when a priori information is lacking. This may be useful for estimating the number of bats flying in an area based on recordings of their echolocation calls. Further analyses were conducted to determine the usefulness of using neural networks for other classifications. [Work supported by NIH.]
Time-dependent compressible extrudate-swell problem with slip at the wall
Authors: Georgiou Georgios C. , Crochet Marcel J.
Published: July 2002

We solve the time-dependent compressible Newtonian extrudate-swell problem with slip at the wall, in an attempt to simulate the stick-slip extrusion instability. An arbitrary nonlinear slip model relating the shear stress to the velocity at the wall is employed, such that the flow curve consists of two stable branches separated by an unstable negative-slope branch. Finite elements are used for the space discretization and a standard fully implicit scheme for the time discretization. When the volumetric flow rate at the inlet is in the unstable regime and compressibility is taken into account, self-sustained periodic oscillations of the pressure drop and of the mass flow rate at the exit are observed and the extrudate surface becomes wavy, as is the case in stick-slip instability. Results are presented for different values of the compressibility number. As compressibility is reduced, the frequency of the oscillations becomes higher, the amplitude of the pressure drop oscillations decreases, and the amplitude of the mass flow-rate oscillations decreases, whereas the amplitude and the wavelength of the free-surface waves decrease.
Time‐Resolved Potential‐Induced Changes in Fe/N/C‐Catalysts Studied by In Situ Modulation Excitation X‐Ray Absorption Spectroscopy
Authors: Ebner Kathrin , Clark Adam H. , Saveleva Viktoriia A. , Smolentsev Grigory , Chen Jingfeng , Ni Lingmei , Li Jingkun , Zitolo Andrea , Jaouen Frédéric , Kramm Ulrike I. , Schmidt Thomas J. , Herranz Juan
Published: February 2022

To advance the widespread implementation of electrochemical energy storage and conversion technologies, the development of inexpensive electrocatalysts is imperative. In this context, Fe/N/C‐materials represent a promising alternative to the costly noble metals currently used to catalyze the oxygen reduction reaction (ORR), and also display encouraging activities for the reduction of CO2. Nevertheless, the application of these materials in commercial devices requires further improvements in their performance and stability that are currently hindered by a lack of understanding of the nature of their active sites and the associated catalytic mechanisms. With this motivation, herein the authors exploit the high sensitivity of modulation excitation X‐ray absorption spectroscopy toward species undergoing potential‐induced changes to elucidate the operando local geometry of the active sites in two sorts of Fe/N/C‐catalysts. While the ligand environment of a part of both materials’ sites appears to change from six‐/five‐ to fourfold coordination upon potential decrease, they differ substantially when it comes to the geometry of the coordination sphere, with the more ORR‐active material undergoing more pronounced restructuring. Furthermore, these time‐resolved spectroscopic measurements yield unprecedented insights into the kinetics of Fe‐based molecular sites’ structural reorganization, identifying the oxidation of iron as a rate‐limiting process for the less ORR‐active catalyst.
Filter‐membrane treatment of continuous‐flow tetracycline through photocatalysis‐assisted peroxydisulfate oxidation
Authors: Zhu Zuoyan , Tang Haifang , Du Yi , Wei Yuanfeng , Chen Yuqing , Yang Weijian , Zhang Danyu , Li Ziru , Liu Chengbin
Published: February 2022

Herein, we craft a high‐performance advanced oxidation process (AOP) of photocatalysis‐coupled peroxydisulfate (PDS) system toward practical applications in organic wastewater treatment. CoFe2O4 nanoparticles well grow onto TiO2 nanotube arrays (TNAs) mesh (CoFe2O4/TNAs). The artful CoFe2O4/TNAs composite plays a bifunctional role in the proposed AOP. On one hand, CoFe2O4/TNAs itself is a visible‐light‐response photocatalyst. On the other hand, the Co(II) or Fe(II) in CoFe2O4 can heterogeneously activate PDS to generate energetic active species (•OH, SO4˙–, O2˙–, and 1O2). Meanwhile, the photo‐induced electrons can be also captured by electron traps Co(III) (or Fe(III)) which are further reduced to Co(II) (or Fe(II)) for continuous activation of PDS. As a result, the robust AOP of photocatalysis‐coupled PDS can almost completely degrade 10 mg/L refractory tetracycline within 40 min. Moreover, the proposed process shows a stable continuous‐flow treatment performance. This work provides basic understanding and support for continuous‐flow treatment of organic wastewater by photocatalysis‐coupled PDS system.
Spinal fixation after laminectomy in pigs prevents postoperative spinal cord injury
Authors: Slot Emma M. H. , de Boer Bart , Redegeld Saskia , van Thoor Sander , Moayeri Nizar , Slooff Willem‐Bart , Schaafsma Irene A. , Meij Björn , van Doormaal Tristan P. C.
Published: February 2022

Background

A safe, effective, and ethically sound animal model is essential for preclinical research to investigate spinal medical devices. We report the initial failure of a porcine spinal survival model and a potential solution by fixating the spine.

Methods

Eleven female Dutch Landrace pigs underwent a spinal lumbar interlaminar decompression with durotomy and were randomized for implantation of a medical device or control group. Magnetic resonance imaging (MRI) was performed before termination.

Results

Neurological deficits were observed in 6 out of the first 8 animals. Three of these animals were terminated prematurely because they reached the predefined humane endpoint. Spinal cord compression and myelopathy was observed on postoperative MRI imaging. We hypothesized postoperative spinal instability with epidural hematoma, inherent to the biology of the model, and subsequent spinal cord injury as a potential cause. In the subsequent 3 animals, we fixated the spine with Lubra plates. All these animals recovered without neurological deficits. The extent of spinal cord compression on MRI was variable across animals and did not seem to correspond well with neurological outcome.

Conclusion

This study shows that in a porcine in vivo model of interlaminar decompression and durotomy, fixation of the spine after lumbar interlaminar decompression is feasible and may improve neurological outcomes. Additional research is necessary to evaluate this hypothesis.
Not All Entangled States are Useful for Ancilla‐Assisted Quantum Process Tomography
Authors: Lu Guo‐Dong , Zhang Zhou , Dai Yue , Dong Yu‐Li , Zhang Cheng‐Jie
Published: February 2022

It is well known that one can extract all the information of an unknown quantum channel by means of quantum process tomography, such as standard quantum‐process tomography and ancilla‐assisted quantum process tomography (AAQPT). Furthermore, it is shown that entanglement is not necessary for AAQPT; there exist separable states that are also useful for it. Surprisingly, in this work we find that not all entangled states are useful for AAQPT; there also exist some entangled states that are useless. The realignment operation used in entanglement detection can be related to the question whether a bipartite state is useful for AAQPT. The relationship between them is derived and the process of extracting the complete information of an unknown channel by the realignment operation shown. Based on this relationship, examples of a two‐qutrit entangled state and a two‐qutrit bound entangled state are presented. Both of these two examples are entangled but they cannot be used for AAQPT. Last but not the least, experimental verification is been performed on the IBM platform.
Seasonal and diel activities of the Yangtze finless porpoise in natural and highly disturbed habitats: Implications for conservation planning of freshwater cetaceans
Authors: Chen Minmin , Yu Daoping , Wang Kangwei , Zhang Kang , Wang Zixuan
Published: February 2022

Knowledge of fine‐scale seasonal and diel activity patterns of animals provides insights into habitat utilization dynamics and informs conservation action planning against potential human impacts. Such information is particularly important for riverine cetaceans, such as the Yangtze finless porpoise, which is threatened by habitat loss and disturbances by a variety of human activities.

Passive acoustic monitoring (PAM) techniques were used to survey the seasonal and diel activities of the Yangtze finless porpoise in two natural habitat patches of the Anqing Yangtze Finless Porpoise Natural Reserve, and in one highly disturbed area adjacent to the reserve.

In the two natural habitat patches, significantly higher detection rates of porpoises were observed during autumn and winter. The detection rates during autumn and winter were significantly higher at night than during daytime, whereas during spring and summer the diel difference in porpoise detection rates was not statistically significant. In the highly disturbed habitat, the porpoise detection rates were significantly lower than those in the two natural habitats. Although seasonal differences in porpoise detection rates were not statistically significant, diel detection rates were significantly different in autumn and winter.

Information on seasonal patterns of porpoise activities suggested strengthening monitoring and law enforcement during autumn and winter, during the period in which diel activity patterns implied a potential conservation gap during nighttime. Extremely low levels of porpoise activities in port areas implied an ecological impact of coastal engineering on megafauna viability through the alteration of habitat functionality.

To provide information on animal occurrences and activities and to minimize the bias of ‘false‐absence’ from visual surveys, the census survey design should consider both visual and PAM techniques. In seasons when occurrences of river cetaceans and habitat use are increasing, heightened conservation monitoring and law enforcement efforts are required, particularly during nighttime.
3D homogeneous potentials producing isoenergetic families of orbits: An application to galactic dynamics
Authors: Kotoulas Thomas
Published: February 2022

In the light of the inverse problem of Newtonian dynamics, we study three‐dimensional homogeneous potentials of degree producing a given two‐parametric family of regular orbits. Especially, we are interested in isoenergetic families of orbits, that is, families of orbits, which are described with constant energy by a test particle of unit mass. First, we offer the criteria, which must be fulfilled by the given family of regular orbits so that it can be created by such a potential. Second, we examine special cases, for example, , and we present families of orbits, which are generated by genuine 3D potentials. Finally, applications to galactic models are also given.
Enhancing the Cyclability of VS4 Positive Electrode in Carbonate‐Based Electrolyte using Fluoroethylene Carbonate Additive
Authors: Yoshii Kazuki , Kohno Kazushige , Maeyoshi Yuta , Taguchi Noboru , Yano Akira , Takeuchi Tomonari , Sakaebe Hikari
Published: February 2022

Vanadium polysulfide (VS4) is a promising material of construction for positive electrodes of next‐generation batteries due to its high theoretical capacity and electrical conductivity compared to those of elemental sulfur. In this study, we investigated the charge and discharge behavior of a low‐crystalline VS4 positive electrode using different electrolytes and under differing charge and discharge conditions. The electrolyte composed purely of cyclic carbonate exhibited higher cycle performance than the one containing linear carbonate. Furthermore, the addition of fluoroethylene carbonate (FEC) to the electrolyte was very effective to improve the cycle performance. The effects of FEC on the VS4 positive electrode were investigated using electrochemical techniques, X‐ray photoelectron spectroscopy, and electron microscopy, the results whereof indicated that LiF‐containing components were formed on the VS4 surface, and probably contributed to the improvement of the charge and discharge behavior of the VS4 positive electrode.
Advanced strategies to thwart foreign body response to implantable devices
Authors: Capuani Simone , Malgir Gulsah , Chua Corrine Ying Xuan , Grattoni Alessandro
Published: February 2022

Mitigating the foreign body response (FBR) to implantable medical devices (IMDs) is critical for successful long‐term clinical deployment. The FBR is an inevitable immunological reaction to IMDs, resulting in inflammation and subsequent fibrotic encapsulation. Excessive fibrosis may impair IMDs function, eventually necessitating retrieval or replacement for continued therapy. Therefore, understanding the implant design parameters and their degree of influence on FBR is pivotal to effective and long lasting IMDs. This review gives an overview of FBR as well as anti‐FBR strategies. Furthermore, we highlight recent advances in biomimetic approaches to resist FBR, focusing on their characteristics and potential biomedical applications.
Vascularized lymph node transplantation successfully reverses lymphedema and maintains immunity in a rat lymphedema model
Authors: Sakarya Ahmet Hamdi , Huang Chi‐Wei , Yang Chin‐Yu , Hsiao Hui‐Yi , Chang Frank Chun‐Shin , Huang Jung‐Ju
Published: February 2022

Vascularized lymph node transplantation (VLNT) has shown inspiring results for the treatment of lymphedema. Nevertheless, it remains unclear how VLNT restores lymphatic drainage and whether or not immunity recovers after surgery. Hindlimb lymphedema model was created using rats with extensive groin and popliteal lymph node removable following with radiotherapy, and the lymphedema was confirmed using indocyanine green (ICG) lymphangiography and micro‐computer tomography for volume measurement. VLNT was performed 1 month later. Volume measurement, ICG lymphangiography, histology, and immune reaction were done 1 month after surgery. VLNT successfully reduced the volume of the lymphedema hindlimb, restored lymphatic drainage function with proven lymphatic channel, and reduced lymphedema‐related inflammation and fibrosis. It promotes lymphangiogenesis shown from ICG lymphangiography, histology, and enhanced lymphangiogenesis gene expression. Dendritic cell trafficking via the regenerated lymphatic channels was successfully restored, and maintained systemic immune response was proved using dinitrofluorobenzene sensitization and challenge. VLNT effectively reduces lymphedema and promotes lymphatic regeneration in the capillary lymphatic but not the collecting lymphatic vessels. Along with the re‐established lymphatic system was the restoration of immune function locally and systemically. This correlated to clinical experience regarding the reduction of swelling and infection episodes after VLNT in lymphedema patients.
Tunable Circularly Polarized Luminescent Supramolecular Systems: Approaches and Applications
Authors: Chen Xu‐Man , Zhang Shu , Chen Xiao , Li Quan
Published: February 2022

The front cover artwork is provided by Xu‐Man Chen et al., Institute of Advanced Materials and School of Chemistry and Chemical Engineering, Southeast University. The image shows left and right hands manipulating the supramolecular building blocks to control the emission color, intensity and chirality of circularly polarized luminescent materials. Read the full text of the Review at 10.1002/cptc.202100256.
pH analysis of still and carbonated bottled water: Potential influence on dental erosion
Authors: Morgado Mariana , Ascenso Carla , Carmo Joana , Mendes José João , Manso Ana Cristina
Published: February 2022

Objective

To assess pH values to characterize bottled water in Portugal, being able to provide information for both patients and clinicians about its erosive potential, as a tool to prevent the ingrowing prevalence of dental erosion and its progression, especially in patients who are at greater risk, such as those with dry mouth syndrome, making the dissemination of this knowledge a fundamental tool for clinical decision.

Materials and Methods

One hundred and five common brands of bottled water (n = 105), commercialized in Portugal, were analyzed. Of these, 73 were smooth water (Group A) and 32 carbonated water (Group B). All pH values were assessed by potentiometric measurement with a calibrated electrode. For each brand, five independent measurements were recorded at 25°C for further calculation of the mean pH value and standard deviation.

Results

Focusing on the mean pH values from Group A, one had a pH mean value lower than 5.2, four between 5.2 and 5.5, thirty‐seven between 5.5 and 6.8, and thirty‐one higher than 6.8. In Group B, ten had a mean pH value lower than 5.2, ten between 5.2 and 5.5, twelve between 5.5 and 6.8, and none above 6.8.

Conclusions

Bottled water, commercialized in Portugal, has different mean pH values, some below the critical threshold of enamel and/or dentin, suggesting that they may have a greater risk of consumption than others, only with respect to the pH parameter of erosive potential. Further investigation concerning this area is needed for wider conclusions.