bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural encoding and perceptual decision weights associated with attention to different acoustic spectral features
Authors: Isarangura Sittiprapa , Eddins David A. , Ozmeral Erol J. , Lutfi Robert A. , Eddins Ann C.
Published: December 2020

Two spectral cues that often co-vary are the spectral envelope, indexed here by spectral modulation (SM) frequency, and the modulation carrier frequency (CF). The perceptual weighting of such different spectral cues during behavioral tasks and the encoding of those weighted cues by the human auditory system is unexplored. Fifteen young normal-hearing listeners participated in two experiments. Stimuli included noise bands (three octaves wide) centered at 1500 or 1700 Hz and SM frequencies (SMF) of 2 or 4 cycles/octave. Behavioral and electroencephalographic (EEG) responses were measured simultaneously during 2-alternative, single-interval tasks. To evaluate attention to SMF versus CF cues, responses were measured in 4 conditions: passive, undirected attention, or directed attention to SMF or CF. Cortical response components were differentially modulated in attention versus passive conditions and by selective attention to SMF or CF cues. To differentiate encoding during selective attention to SMF or CF cues, perceptual decision weights were measured using a condition-on-a-single-stimulus (COSS) analysis with simultaneously recorded EEG. Results revealed individual differences in perceptual weights across listeners but distinctive cortical responses for those assigning greater weight to SMF versus CF cues. Weight- and cue-dependent neural activity indexed by source analysis will be discussed. [NIH P01AG009524; NIH DC015051.]
The perceptual simultaneity range for complex tones
Authors: Okazaki Satoshi , Tsuzaki Minoru
Published: December 2020

Recently, we found that the range of perceptual simultaneity, within which two asynchronous pure tones are perceived to start simultaneously, shows a V-shaped curve as a function of frequency separation with the breakpoint at 0.5 Bark. This study aimed to test whether such a law of perceptual simultaneity range is applicable to complex tones. The two-tone harmonic complexes with different fundamental frequencies were used to measure the perceptual simultaneity range. Listeners were asked to judge whether the two complex tones start simultaneously or asynchronously. The use of the perceptual fusion cue for the simultaneity judgment was avoided. Results showed that the perceptual simultaneity range for two-tone complexes did not follow the above law as a function of the fundamental frequency. However, it seems that the individual components of the complex tones followed the law. These results suggest that the behavior of the perceptual simultaneity range for complex tones could be predicted by the law of perceptual simultaneity range for pure tones with considering the contributions of pure-tone components.
Word recognition in noise and extended high frequency auditory thresholds
Authors: Rawool Vishakha , Campbell Chelsea
Published: December 2020

Thirty-one individuals within the age-range of 18 to 27 years and 30 individuals within the age-range of 45 to 59 years participated in this study. Auditory thresholds were established in a sound treated booth from 250 to 16000 Hz. Words in noise scores were obtained under Sennheiser HD201 headphones through an iPad (NIH toolbox). The auditory thresholds were averaged across three frequency groups: 0.25, 0.5 and 1 kHz; 2, 3, 4, 6, 8, 9 and 10 kHz and 11.2, 12.5, 14 and 16 kHz. WIN scores were significantly correlated with all average thresholds. The correlations between the average auditory thresholds at 0.25, 0.5 and 1 kHz and WIN scores were −0.457 and −0.413 for the right and left ears. The correlations between the average auditory thresholds at 11.2, 12.5, 14 and 16 kHz were -0.699 for the right and -0.627 for the left ear. The correlation between average auditory thresholds at 2, 3, 4, 6, 8, 9 and 10 kHz for the right and left ears were −0.78 and −0.74. These findings suggest the importance of higher frequencies. [Funded by Grace Clements Communication Sciences & Disorders Research Endowment Award at West Virginia University.]
Parameterizing effects of precursor spectral characteristics on categorization of subsequent vowel sounds
Authors: Stilp Christian
Published: December 2020

When spectra differ between earlier (context) and later (target) sounds, listeners perceive larger spectral changes than are physically present. When context sounds (e.g., a sentence) possess relatively higher frequencies, the target sound (e.g., a vowel sound) is perceived as possessing relatively lower frequencies, and vice versa. These spectral contrast effects (SCEs) are pervasive in auditory perception, but studies traditionally employed context stimuli with high spectrotemporal variability, obscuring precisely when spectral properties of the context biased perception. Here, contexts were two-second speech-shaped noise segments divided into four consecutive 500-ms epochs. Contexts were filtered to amplify low-F1 (100–400 Hz) or high-F1 (550–850 Hz) frequencies to encourage perception of /ε/ (“bet”) or /I/ (“bit”) respectively via SCEs. Spectral peaks in the context occurred in the first 1/2/3/all 4 epochs (Onset condition), the last 1/2/3/all 4 epochs (offset condition), or only one epoch (single condition). SCE magnitudes increased as spectral peaks occurred later in the context (closer to the target), with Onset and Offset conditions producing similar results. Even brief spectral peaks in earlier epochs biased categorization. Results will be discussed with regard to pedestals, as earlier spectral peaks followed by sustained spectrally neutral context still biased perception of the subsequent vowel target.
Effects of age and tinnitus: Limited physiological evidence and no perceptual consequence of cochlear synaptopathy
Authors: Patro Chhayakant , Kreft Heather , Wojtczak Magdalena
Published: December 2020

Evidence from animal models and human temporal bones has shown that cochlear synaptopathy is associated with aging. Previous work from our lab has suggested that a weakened middle-ear-muscle-reflex (MEMR) in individuals with tinnitus and normal hearing may reflect the presence of cochlear synaptopathy. In this study, we investigated effects of age and tinnitus on the MEMR strength. We also investigated the relationship between the MEMR strength and amplitudes of auditory brainstem responses (ABRs) as well as several perceptual measures that rely on precise temporal neural coding, such as amplitude-modulation detection, the detection of envelope interaural phase difference, and spatial release from speech-on-speech masking. Younger (20–30 yrs) and older (55–69 yrs) listeners with and without tinnitus and with normal or near-normal hearing were tested. We found that aging and tinnitus were associated with significant reductions in MEMR strength and ABR-based measures. However, only the MEMR-strength reduction was significant after accounting for group differences in high-frequency hearing sensitivity. No significant group differences between the older, tinnitus and control groups were found in the perceptual measures obtained in this study. Results will be discussed in terms of sensitivity of these measures to cochlear synaptopathy in humans. [Work supported by NIH grant R01 DC015987.]
Steady state pressure distribution in a simple model of the cochlea with a rigid basilar membrane
Authors: Knoll Henk , Vermeulen Arthur
Published: December 2020

Sound propagating through the scalae of the cochlea causes pressure changes which set the basilar membrane in motion. These pressure changes are studied in the present work with a simple model consisting of a tube with a varying diameter and a rigid wall. Analytical expressions are derived for the pressure changes in relation to the geometry of the tube, fluid friction, the acceleration of the liquid in the tube (perilymph) and stiffness of the membrane of the round window. Using a realistic parameter set, the pressure changes turn out to be dominated by the acceleration of the perilymph. The pressure changes are in phase with the acoustic stimulation and their amplitude depends on the geometry of the tube; tapering towards the middle (the helicotreme) turns out to be advantageous; the amplitudes of the differential pressure and the pressure change over the basilar membrane are maximized along the cochlear duct. Finally, the stiffness of the membrane of the round window only has impact on the static pressure in the duct.
The effect of level-ratio paradigm on DPOAE fine structure
Authors: Scheidler Samantha K. , Norton Mikayla , Naghibolhosseini Maryam
Published: December 2020

Distortion product otoacoustic emissions (DPOAEs), sound signals recorded in the ear canal and generated inside the cochlea by presenting two primary tones (f1/L1 and f2/L2; f2 > f1) in the ear canal, can be used to study the health and function of the cochlea. Different primary tone level-ratioparadigms (L1:L2) can be used for obtaining DPOAEs and depending on the selected paradigm, different fine structure patterns are observed. The goal of this study is to understand how three common level-ratio paradigms affect DPOAE fine structure, generated by sweeping primary tones in frequency. The paradigms used are scissors, L1 = 0.4L2 + 39 dB; Boys Town “optimal,” L1 = 0.45L2 + 44 dB; and the equal-level, L1 = L2. The main components of the DPOAE signals, generator and reflection components, are extracted using a least squares fit algorithm. For each level paradigm, the phases of the generator and reflection components are used to determine the frequency distance between adjacent fine structure minima and maxima. This analysis is carried out for different primary levels and all paradigms. The interaction of the primary tones inside the cochlea and their impact on the fine structure pattern for each paradigm will be discussed.
Endogenous brain oscillations in the 10–20 Hz range during auditory spatial attention
Authors: Love Jordan , Shinn-Cunningham Barbara , Bharadwaj Hari
Published: December 2020

Oscillatory brain activity in the alpha frequency range (7–13 Hz) is commonly implicated in the attention literature, though the exact role it plays in facilitating attention is debated. A popular functional theory, the “alpha suppression hypothesis,” suggests that changes in alpha amplitudes can be interpreted as a marker of active suppression of neural assemblies that code for distractors. Recent studies of visual selective attention have questioned this hypothesis. In the auditory attention literature, alpha power during listening has been reported to fluctuate with the temporal structure of target sounds. Yet, studies examining whether purely endogenous alpha activity during orienting of attention predicts trends in subsequent task performance are limited. The current study addresses this gap by quantifying changes in alpha power observed in the electroencephalography (EEG) signal during an auditory selective attention task. This analysis focuses on the preparatory period, a window of time following a directional attention cue but preceding the auditory stimulus. Preliminary results suggest the presence of robust endogenous oscillations between 10 and 20 Hz during this preparatory period. Further analysis will compare the strength of these rhythms to individual differences in task performance, to variations in task demands, and to within-individual trial-to-trail variations in perceptual outcomes.
Development of Indonesian audiovisual speech synthesis system for assistance children with delayed speech
Authors: Anggrayni Elok , Arifianto Dhany , Purnami Nyilo , Sarwono Joko , Wira Sangsaka
Published: December 2020

Hearing impairment is one of the congenital deafness frequently found in children, which is followed by a delayed speech. Furthermore, a speech therapist currently available is limited. In this research, we outlined the development of the Indonesian audio-visual speech synthesis system for learning of the deaf children with delayed speech. First, we developed two kinds of Indonesian corpus, such as speech corpus and audio-visual corpus. The speech corpus contains speech recordings from professional speech therapists. The total duration of all recorded Indonesian speech database is more than 18 hours of audio. The audio-visual corpus contains visual phoneme (viseme) which is the visualization of Indonesian phoneme for lips. Segmentation and labeling were conducted to create transcriptions. We did some variation in the number of sentences and the type of sentences used in the training part of speech synthesis. Audio-visual synthesis used viseme concatenation method. The objective evaluation result using the Mel-cepstrum distortion method was 2.8. The subjective evaluation result using Mean Opinion Score was 3.71. The evaluation results showed that the new design of Indonesian audio-visual speech synthesis for learning to produce any single meaningful word was capable to use as the alternative for hospitals for the therapy of the delayed speech patients.
Mapping Southern spoken dialect features with geographic information systems
Authors: Jones Jonathan , Renwick Margaret E.
Published: December 2020

We use GIS mapping to analyze spatial trends in spoken language, testing how features identified as part of the ‘Southern dialect' by the Atlas of North American English (ANAE) are realized in the Digital Archive of Southern Speech (DASS). We analyze mergers, diphthongization, monophthongization, fronting, g-dropping, and rhoticity. Acoustic data from DASS was analyzed using R, generating feature-appropriate summary statistics. GIS analysis was conducted with GeoDa, QGIS, and ArcGIS Online. Spatial analysis used the Local Moran's I method to identify geographic clusters of similar values. Generally, DASS data agrees with ANAE's descriptions. However, POOL-PULL are not consistently merged, unlike in ANAE, except for a cluster in Eastern Tennessee. /cI/-monophthongization also varies: averages indicate the vowel was still fairly diphthongized, while spatial autocorrelation finds monophthongization in Central Tennessee and Atlanta. /oΩ/ appears to front only weakly; however, the greatest fronting is found in Florida. We find high rates of g-dropping and rhoticity, but mapping and analysis for these features reveals clusters of more g-dropping in Eastern Tennessee, less rhoticity along Florida's Gulf Coast, and more rhoticity in Northern Mississippi. Our analysis partially corroborates ANAE's description, suggesting that Southern speech changed between the DASS interviews and the later publication of ANAE.
Coarticulatory assimilation of velar consonants on vowels in the Southern Dialect of America English
Authors: Bouguyon Jaden , Seitter Ryan , Kim Yun J.
Published: December 2020

Previous studies have shown dialectal differences in assimilatory coarticulation patterns. For example, Southern American English (i.e., SAE) speakers have more nasalized vowels in pre-nasal contexts than non-SAE speakers (e.g., Awan et al., 2015). This study asks whether SAE and non-SAE speakers differ in another assimilatory coarticulation process, namely, the “velar pinch,” or the convergence of F2 and F3 in pre-velar vowels. To answer this question, a production study is conducted: 5 SAE speakers and 5 non-SAE speakers are recruited to produce 24 words embedded in sentences. The target words include three types of assimilatory contexts: pre-/k,g/, pre-/η/, and pre-/n/ vowels. The degree of vowel nasalization and the formant transitions before the consonant are analyzed based on Kaiser (1997). Preliminary results show that SAE speakers have stronger vowel nasalization in the pre-/n/ and pre-/η/ contexts, and smaller F3-F2 differences in the pre-/k,g/ contexts, suggesting that SAE speakers show not only stronger vowel nasalization but also stronger “velar pinch” than non-SAE speakers. Interestingly, in the pre-/η/ contexts in which both types of coarticulatory assimilation are possible, SAE speakers have weaker “velar pinch” than non-SAE speakers. Sociolinguistic implications of the results will be discussed.
Effect of consonants on onset F0: Evidence from Kansai Japanese
Authors: Zhang Miao
Published: December 2020

This study investigates the effect of voicing on onset F0 in Kansai Japanese. In tone languages, the effect of initial consonants on F0 tends to be smaller and shorter, hypothetically to maximize the tonal contrast preserved for lexical items. A recent study (Gao and Arai, 2019) found that despite Tokyo Japanese being a pitch-accent language, the consonant effect on F0 was not necessarily inhibited. However, this might be due to decreased laryngeal control in Tokyo Japanese because of its simple tonal contrast. Since the pitch accent system of Kansai Japanese is more complex than that of Tokyo Japanese, Kansai Japanese should show less F0 perturbation. In the experiment, five native speakers (4 females, 1 male) produced the target words /CVma/ (C: /n, b, p/, V: /i, a/) in different pitch accent types (HH, HL, LH) and focus conditions (broad, narrow, contrast focus). My data show that overall, F0 following /p/ is significantly higher. The more complex pitch-accent system did not lessen the F0 perturbation. Consistent across focus, the effect is slightly larger in words with a high pitch accent and in the high vowel /i/ context. This may be due to the congruence in laryngeal settings for high F0 production.
Do children compensate for their vocal tract morphology during vowel production?
Authors: Cychosz Margaret
Published: December 2020

Children's vocal tracts (VT) are not miniature adult versions: the oral cavities are longer relative to the pharyngeal. Children may compensate for this morphology by shifting constriction location to approximate adult-like resonances (Ménard et al., 2007). But the same lingual adjustment may be insufficient across development because children exhibit non-uniform VT growth. The constriction location required to create a resonator at age 4 will differ from that required at age 8. For child formant normalization, then, uniform scaling techniques which disregard formant and vowel identity and rely on single factors such as VT length, may not factor out all differences between children. We address this by comparing two formant scaling techniques, non-uniform (Lobanov) and uniform (DeltaF) (Johnson, 2020). 60 children, aged 4–10, produced /a, i, u/. Formants (F1–F3) were Lobanov- and DeltaF-scaled. Lobanov-scaled formants were more variable than Delta-F scaled formants, indicating that even after VT length normalization (uniform scaling), between-speaker variability remained in the children's speech. The children's F1:F2 ratio, a proxy for oral to pharyngeal cavity length ratio, explained some of this variability. This result suggests that children are not uniformly compensating for their morphologies and uniform scaling may not be appropriate at every developmental stage.
Random matrix theory analysis of the dominant mode rejection beamformer white noise gain
Authors: Hulbert Christopher , Wage Kathleen E.
Published: December 2020

The dominant mode rejection (DMR) beamformer [Abraham and Owsley, IEEE Oceans (1990)] is an adaptive spatial processor that has been effectively used to null interference sources in scenarios where the number of training samples to estimate the sample covariance matrix (SCM) is limited. In these scenarios the ratio of the SCM dimension (array size) to the number of snapshots (training samples) is close to or even greater than one. Whereas classical asymptotic SCM results require the number of samples grow to infinity while keeping the dimension fixed, random matrix theory (RMT) provides a robust mathematical framework to analyze the SCM spectrum in snapshot-limited scenarios. RMT predictions of the SCM eigenvectors have already been applied to predict DMR beamformer notch depth in a single interferer environment (Buck and Wage, IEEE SSP (2012)]. This talk presents an RMT-based asymptotic approximation of the DMR SCM inverse in a loud multi-interferer environment. The RMT SCM model is used to predict the white noise gain (WNG) of the DMR beamformer, accounting for the impact when bulk spectral components are included in the dominant subspace. The performance of the RMT-based WNG prediction is compared to the sample mean using Monte Carlo simulations. [Funded by ONR 321US.]
Potential restorative effect of the urban soundscape experience
Authors: Jo Hyun In , Lee Kounseok , Jeon Jin Yong
Published: December 2020

This study investigated the potential restorative effect of various urban soundscape experiences. The evaluation stimulus was implemented using virtual reality technology in a laboratory environment. Restoration-related semantic expression words were selected from the interview responses of 50 subjects, and the presence or absence of the expression of the words was newly proposed as a restorative potential criteria. The objective characteristics of urban soundscapes were analyzed based on auditory, visual, and object aspects, and subjects responded to sound source identification, perceived affective quality, and overall quality. The temperament and character inventory-revised short version and satisfaction with life scale were used to investigate individual characteristics. Based on this, a prediction model having an accuracy of 83% was proposed for the restorative potential criteria. As a result, it was found that the overall perception of soundscape was a crucial factor in increasing the restorative potential effect of the urban soundscape experience. In addition, it was confirmed that the restorative potential effect by individual characteristics varied significantly even in the same space. The findings of this study are expected to serve as a basis for sustainable and healthy urban soundscape design.
Analysis of the acoustic characteristics of spaces relating to their emotional impact
Authors: Algargoosh Alaa
Published: December 2020

Sound and emotions have a link that has been widely studied in music. However, when sound propagates through space during a performance, the architectural features of the space impact how sound reflects, causing an alteration in some of the original sound characteristics. Therefore, it is essential to study how the acoustic environment contributes to the emotional impact. For instance, researchers in worship spaces have reported the significance of the acoustic environment in impacting emotions and enhancing the spiritual experience. Nevertheless, further research is required to understand the acoustic parameters that contribute to that effect. In a previous study, the researcher analyzed the emotional response to the acoustic environments of worship spaces using self-report and physiological indicators. This study builds on the earlier results by analyzing the acoustic characteristics of such spaces and their relationship to the emotional impact. Establishing such a link between room acoustics' parameters and emotions provides a guide for designing spaces that enhance the occupant's experience.
Nocturnal distribution of Guiana dolphins (Sotalia guianensis) in a coastal bay: Using the help of local fisherman and passive acoustic monitoring
Authors: Barbosa Mariana , Bittencourt Lis , Santos-Neto Elitieri , Bisi Tatiana , Lailson-Brito José , Azevedo Alexandre
Published: December 2020

Overlap between dolphin distribution and fishing activities can lead to accidental by-catch. Assessing the nocturnal distribution of a resident population of dolphins can help highlight sensitive areas where by-catch occurs. The goal of this study was to use passive acoustics equipment deployed by local fisherman in different areas of Sepetiba Bay, southeastern Brazil, to assess Guiana dolphins' distribution at night. In total, 64 recording sessions and 316 hours were collected at a sampling rate of 96 kHz, covering the period between 18:00 and 04:00. To detect Guiana dolphin sounds a Raven pro 1.5 band limited energy detector was defined between frequencies of 25 and 48 kHz and SNR>5dB. An experienced observer validated detections, quantifying according to time and area of occurrence. Guiana dolphins were more frequently encountered in two major areas, where they were present between 68% and 33% of recorded hours. The mean concentration of sounds/hour in the bay was 72 (±113), ranging from 0.6 to 325 across areas. In one location, there was also a higher concentration of detections between 18:00 and 19:00. Future work should rely on local knowledge of fisherman to detect major fishing areas during the night and help creating Guiana dolphin conservation plans.
Experimental results of tomographing the third-order acoustic nonlinear parameter
Authors: Kotelnikov Egor , Dmitriev Konstantin , Rumyantseva Olga
Published: December 2020

Tomography of the acoustic nonlinear parameters is a method of obtaining information about biological tissue using nonlinear interaction of acoustic waves. In the schemes under consideration, three plane coded non-collinear signals probe an investigated object and intersect inside it. Each point of the intersection region generates coded signal at the third-order combination frequencies. Correlation processing of received total signal allows determining the combination of the second- and third-order acoustic nonlinear parameters in each resolution element of the object. Results of physical experiment on reconstructing the spatial distribution of the combined acoustic nonlinear parameter by the scheme with one monochromatic and two coded probing signals are presented. Principal disadvantage of this scheme is nonlocality of generation area of the unique coded combination signal carrying information about the object. This makes it impossible to distinguish the signal generated by the only fixed resolution element of the object. As a consequence, reconstructed quantitative values of the nonlinear parameters can be distorted. The next step is the scheme with three coded probing signals, that is more complex for implementation. Nevertheless, now each unique signal is generated by the single resolution element. Thereby, it becomes possible to adequately reconstruct the desired values of nonlinear parameters.
Coherence-based quantification of acoustic clutter sources in medical ultrasound
Authors: Long James , Long Will , Bottenus Nick , Trahey Gregg
Published: December 2020

The relative contributions of aberration and incoherent noise sources, such as diffuse reverberation and thermal noise, to image quality in medical ultrasound are not well understood. We present a theoretical framework to predict losses in the correlation of ultrasonic backscatter, i.e., spatial coherence, and imaging contrast in response to combinations of incoherent noise and aberration levels. This framework is based on estimating the beamformer gain and channel SNR, using measurements of spatial coherence. A method to separate the contributions of incoherent noise and aberration in the spatial coherence domain is also explored and applied to predict losses in contrast. Results indicate excellent agreement between theory and simulations for beamformer gain and expected contrast loss. Coherence-predicted contrast loss and measured contrast loss in aberration differ by less than 1.5dB on average, for a −20 dB contrast target and aberrators with RMS time delay errors and spatial autocorrelation profiles similar to those measured in vivo. Results also indicate that the contribution of aberration to contrast loss varies with channel SNR, peaking around 0 dB SNR. This framework shows promise to facilitate novel, targeted clutter reduction strategies by providing a means to isolate and estimate the contributions of correlated and uncorrelated noise.
Larry Royster—The early years, North Carolina regional chapter, and scholarship support
Authors: Stewart Noral D.
Published: December 2020

This paper in three parts will discuss (1) the early life of Larry Royster, his education and early career to the point that he became involved in hearing conservation, (2) the North Carolina Regional Chapter of the Acoustical Society of America which he founded, and (3) his strong support of scholarships for students especially the Royster Award administered by the regional and student chapters of the society.
Severe weather observations from a deployable four sensor infrasound array
Authors: Petrin Christopher , KC Real J. , Elbing Brian R.
Published: December 2020

Infrasound is sound at frequencies below 20 Hz. It has been observed to be emitted by tornado-producing storms up to two hours before tornadogenesis. Due to the low atmospheric attenuation of sound at these low frequencies, infrasound may be detected several hundreds of kilometers away under ideal atmospheric conditions. Therefore, passive infrasound monitoring has potential for the study and prediction of tornadoes and other severe weather if the received infrasound signals can be correlated with thermodynamic and flow field properties of the storms and/or tornadoes. Previous work accomplished at Oklahoma State University has focused on observations from a single stationary array located in Stillwater, OK. However, the large distance between this array and the nearest NEXRAD II radar stations makes low-level storm characterization challenging to accomplish in tandem with infrasound observation of severe weather. Therefore, a second array was designed to be deployable at various sites in Oklahoma within 50 km of the radar stations, in order to ensure low-altitude radar resolution. Containing four microphones, the new array was deployed during the summer of 2020 at several sites affiliated with the Oklahoma Mesonet. Details of the array's design and deployment will be presented, as well as preliminary data collected during non-tornadic thunderstorms in 2020. [This work was supported by NOAA Grant NA19OAR4590340 and NOAA Grant NA18OAR4590307.]
Frequency-dependent analytic models for scattering off finite half planes
Authors: Alkhairy Samiya
Published: December 2020

Established theories of wave scattering off points and infinite reflectors have limitations for many problems encountered in wave propagation. Our goal is to extend acoustic scattering theory towards a model that not only describes conventional scattering but also the less idealized case of scattering off finite objects. We develop an analytic object-centric forward frequency domain model of the signal at the receiver. The expression is explicitly parameterized in terms of medium and finite object properties that explicitly incorporates frequency-dependence. Our construction uses perturbation theory and integrates over effective point sources along the object surfaces that acts as finite half planes. From this, we derive closed-form expressions using integral approximation methods; and we also determine frequency, material and geometry conditions under which the conventional theories and associated operators apply. We utilize limiting cases to guide and test our model. The model also provides nontraditional extensions of reflection theory, e.g., for sources with spherical radiation patterns. The unified treatment of the continuum of wave phenomena is not only important theoretically but may also be useful in frequency-based object-centric estimation, array optimization and designing signal processing and acquisition schemes.
Passively achieving mode coalescence in acoustic waveguides with simple resonators
Authors: Kelsten Matthew , Norris Andrew N.
Published: December 2020

A double root, commonly referred to as an exceptional point (EP), for modal frequencies in a 2-D or 3-D waveguide can exhibit almost perfect absorption over a relatively broad frequency range. The key to the phenomenon is that the wall impedance is such that modes coalesce at a complex-valued frequency. In this talk we consider a novel approach to feasibly achieve the aforementioned wall impedance with the use of simple resonators, which can be shown to exhibit mode coalescence at distinct frequencies when treated as a unit cell component of a larger metasurface. In order to evaluate each unit cell design, an efficiency parameter, EP density, was created which quantifies the number of double root frequencies within a given range all while satisfying the following constraints: realizable resonator dimensions, scale separation, and target absorption/attenuation goals. Strategies capable of deriving the necessary resonator parameters for this effect are given. The impact of these strategies on feasibility and performance are discussed via simulated and numerical results. An experiment design consisting of additively manufactured Helmholtz resonators incorporated onto a custom-made impedance tube to simulate the resonant metasurface is discussed along with preliminary results. [Work supported by NSF.]
A muddy legacy
Authors: Voosen Paul
Published: December 2020

A dozen years after two scientists showed how centuries-old mud has smothered many U.S. streams, their ideas are guiding restoration efforts.
Europe is locking down again—but its strategy is unclear
Authors: Kupferschmidt Kai
Published: December 2020

Without a plan to eliminate the virus, countries may face shutdowns over and over, scientists warn.
Synchronous timing of abrupt climate changes during the last glacial period
Authors: Corrick Ellen C. , Drysdale Russell N. , Hellstrom John C. , Capron Emilie , Rasmussen Sune Olander , Zhang Xu , Fleitmann Dominik , Couchoud Isabelle , Wolff Eric
Published: December 2020

All together then

Many geographically dispersed records from across the globe reveal the occurrence of abrupt climate changes, called interstadial events, during the last glacial period. These events appear to have happened at the same time, but the difficulty of determining absolute dates in many of the records have made that proposition difficult to prove. Corrick
et al.
present results from 63 precisely dated speleothems that confirm the synchrony of those interstadial events. Their results also provide a tool with which to validate model simulations of abrupt climate change and calibrate other time series such as ice-core chronologies.

Science
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Rational design of layered oxide materials for sodium-ion batteries
Authors: Zhao Chenglong , Wang Qidi , Yao Zhenpeng , Wang Jianlin , Sánchez-Lengeling Benjamín , Ding Feixiang , Qi Xingguo , Lu Yaxiang , Bai Xuedong , Li Baohua , Li Hong , Aspuru-Guzik Alán , Huang Xuejie , Delmas Claude , Wagemaker Marnix , Chen Liquan , Hu Yong-Sheng
Published: December 2020

Layering the charge

Layered metal oxides such as lithium cobalt oxide have attracted great attention for rechargeable batteries. In lithium cells, only the octahedral structure forms, but in sodium cells, trigonal prismatic structures are also possible. However, there is a lack of understanding about how to predict and control the formation of each structure. Zhao
et al.
used the simple properties of ions, namely their charge and their radius appropriately weighted by stoichiometry, to determine whether sodium in the interlayers between the transition metal or other ion-oxide layers remain octahedral rather than switching over to trigonal prismatic coordination.

Science
, this issue p.
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Resource conservation manifests in the genetic code
Authors: Shenhav Liat , Zeevi David
Published: December 2020

Maximizing elements for your genome

The accumulation of mutations is typically limited by selective parameters. One such parameter is the elements needed to build proteins and molecules to maintain cells. Examining the underlying carbon, oxygen, and nitrogen content for different amino acids, Shenhav
et al.
examined the selective pressure resulting from nutrient limitation (see the Perspective by Polz and Cordero). The authors identified “resource-driven” selection as a purifying selective force associated with environmental nutrient availability, particularly nitrogen, and determined the impact of mutations on the organismal nutritional budget. From this constraint, the authors have proposed that the structure of the genetic code across organisms reflects the mutational impact on elemental resources.

Science
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; see also p.
655
Julich-Brain: A 3D probabilistic atlas of the human brain’s cytoarchitecture
Authors: Amunts Katrin , Mohlberg Hartmut , Bludau Sebastian , Zilles Karl
Published: December 2020

A present-day atlas of the human brain

Defining brain regions and demarking their spatial extent are important goals in neuroscience. A modern map of the brain's cellular structure, a cytoarchitectonic atlas, should provide maps of areas in three dimensions, integrate recent knowledge about brain parcellation, consider variations between individual brains, rely on reproducible workflows, and provide web-based links to other resources and databases. Amunts
et al.
created such an atlas based on serial histological sections of brain. They developed a computational framework and refined the current boundaries of the human brain based on cytoarchitectural patterns. This technique can easily be transferred to build brain atlases for other species or a spatial framework for other organs, other modalities, or multimodal maps for regions of interest at higher spatial scales. This research makes similar future attempts simultaneously reproducible and flexible.

Science
, this issue p.
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Enigmatic amphibians in mid-Cretaceous amber were chameleon-like ballistic feeders
Authors: Daza Juan D. , Stanley Edward L. , Bolet Arnau , Bauer Aaron M. , Arias J. Salvador , Čerňanský Andrej , Bevitt Joseph J. , Wagner Philipp , Evans Susan E.
Published: December 2020

Ancient amphibians preserved in amber

Extant amphibians are represented by three fairly simple morphologies: the mostly hopping frogs and toads, the low-crawling salamanders, and the limbless caecilians. Until the early Pleistocene—and for more than 165 million years—there was another group, the albanerpetontids. We know little about this group because amphibian fossils are poorly preserved, and previous specimens from this group are both rare and mostly badly damaged. Daza
et al.
describe a set of fossils preserved in amber showing that this group was unusual both in their habitat use (they may been climbers) and their feeding mode, which appears to have been convergent with the ballistic feeding now seen in chameleons (see the Perspective by Wake).

Science
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; see also p.
654
Epidemiology and transmission dynamics of COVID-19 in two Indian states
Authors: Laxminarayan Ramanan , Wahl Brian , Dudala Shankar Reddy , Gopal K. , Mohan B Chandra , Neelima S. , Jawahar Reddy K. S. , Radhakrishnan J. , Lewnard Joseph A.
Published: December 2020

Epidemiology in southern India

By August 2020, India had reported several million cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with cases tending to show a younger age distribution than has been reported in higher-income countries. Laxminarayan
et al.
analyzed data from the Indian states of Tamil Nadu and Andhra Pradesh, which have developed rigorous contact tracing and testing systems (see the Perspective by John and Kang). Superspreading predominated, with 5% of infected individuals accounting for 80% of cases. Enhanced transmission risk was apparent among children and young adults, who accounted for one-third of cases. Deaths were concentrated in 50- to 64-year-olds. Incidence did not change in older age groups, possibly because of effective stay-at-home orders and social welfare programs or socioeconomic status. As in other settings, however, mortality rates were associated with older age, comorbidities, and being male.

Science
, this issue p.
691
; see also p.
663
A surprising fossil vertebrate
Authors: Wake David B.
Published: December 2020

An ancient amphibian converged on a chameleon-like way of feeding
Draft Genome Sequence of Lactobacillus rhamnosus NCB 441, Isolated from Egyptian White Domiati Cheese
Authors: Moore Madison A. , Whittington Hunter D. , Azcarate-Peril M. Andrea , Bruno-Bárcena José M.
Published: December 2020

Here, we report the draft genome sequence of
Lactobacillus rhamnosus
NCB 441, which was isolated from pickled white cheese samples gathered at Farafra Oasis in New Valley Governorate, Egypt. The genome size is 2,969,245 bp, with a G+C content of 46.7%.
Supplemental Material: Influence of pre-existing structure on pluton emplacement and geomorphology: The Merrimac plutons, northern Sierra Nevada, California, USA
Authors: Langenheim V.E. , al. et
Published: December 2020

Age and trace chemistry for Merrimac and other plutons, recalculation of previous Merrimac ages, and examples of Merrimac pluton textures.
Late onset depression: dopaminergic deficit and clinical features of prodromal Parkinson’s disease: a cross-sectional study
Authors: Kazmi Hiba , Walker Zuzana , Booij Jan , Khan Faraan , Shah Sachit , Sudre Carole H , Buckman Joshua E.J. , Schrag Anette-Eleonore
Published: December 2020

Background

Late onset depression (LOD) may precede the diagnosis of Parkinson’s disease (PD) or dementia with Lewy bodies (DLB). We aimed to determine the rate of clinical and imaging features associated with prodromal PD/DLB in patients with LOD.

Methods

In a cross-sectional design, 36 patients with first onset of a depressive disorder (Diagnostic and Statistical Manual of Mental Disorders IV criteria) diagnosed after the age of 55 (LOD group) and 30 healthy controls (HC) underwent a detailed clinical assessment. In addition, 28/36 patients with LOD and 20/30 HC underwent a head MRI and 29/36 and 25/30, respectively, had dopamine transporter imaging by 123I-ioflupane single-photon emission computed tomography (SPECT) imaging. Image analysis of both scans was performed by a rater blind to the participant group. Results of clinical assessments and imaging results were compared between the two groups.

Results

Patients with LOD (n=36) had significantly worse scores than HC (n=30) on the PD screening questionnaire (mean (SD) 1.8 (1.9) vs 0.8 (1.2); p=0.01), Movement Disorder Society Unified Parkinson’s Disease Rating Scale total (mean (SD) 19.2 (12.7) vs 6.1 (5.7); p<0.001), REM-sleep behaviour disorder screening questionnaire (mean (SD) 4.3 (3.2) vs 2.1 (2.1); p=0.001), Lille Apathy Rating Scale (mean (SD) −23.3 (9.6) vs −27.0 (4.7); p=0.04) and the Scales for Outcomes in PD-Autonomic (mean (SD) 14.9 (8.7) vs 7.7 (4.9); p<0.001). Twenty-four per cent of patients with LOD versus 4% HC had an abnormal 123I-ioflupane SPECT scan (p=0.04).

Conclusions

LOD is associated with increased rates of motor and non-motor features of PD/DLB and of abnormal 123I-ioflupane SPECTs. These results suggest that patients with LOD should be considered at increased risk of PD/DLB.
MULTIPLIER, SPILLOVER, AND FEEDBACK EFFECTS OF EMPLOYMENT IN CHINA AND THE UNITED STATES: A SKILLS- AND SECTOR-BASED PERSPECTIVE
Authors: WANG LAFANG , ZHANG BIN , YE JIABAI
Published: December 2020

This study uses world input–output (IO) data from 1995 to 2014 to investigate the influence of economic ties on employment in the United States and China. We conclude that the job spillover in China mainly increase the number of jobs employed by the manufacturing industry and the service industry in US, especially the employment of medium- and high-skilled labors accounting for more than 90%. In the meantime, the job spillover effect in the US to China is increasing constantly, especially to the employment of low- and medium-skilled labors in manufacturing and service industries, which tend to be further enhanced. However, the main factors of employment changes on both sides that are from the changes of industrial structure, rather than the impact of foreign products. The most important thing is that the production between China and the United States doesn’t reduce the number of each other’s employment, but optimizes the employment structure of each other, forming a “win–win” situation.
INFORMATION DISCLOSURE IN THE TWO-SIDED MARKET
Authors: GONG YAXIAN , LU YUANZHU
Published: December 2020

This paper analyzes information disclosure in the two-sided market with one monopolistic platform and competing platforms. We find that pertaining to the monopoly platform, greater network externalities tend to increase the information being disclosed, but with competing platforms, increasing network externalities may decrease or increase the disclosed information, depending on the information disclosure cost. However, the relation between the competitiveness of either side and the amount of disclosed information is ambiguous. We show that under certain conditions, the welfare and disclosure cost demonstrate a U-shaped relation, which cautions against the policy aiming at decreasing the information disclosure cost.
Gravitational waves in the spinor theory of gravity
Authors: Novello M. , Hartmann A. E. S.
Published: December 2020

We analyze the gravitational waves within the Spinor Theory of Gravity (STG) and compare it with the General Relativity proposal. In the case of STG, a gravitational wave may occur if the effective gravitational metric induced by the spinorial field is Ricci flat.
Novel study on mechanical properties of pack carburizing SCM 420 steel with energizer dog conch
Authors: Ramli  , Wu Chung-Chun
Published: December 2020

Dog conch shell powder (DCSP) and coconut shell powder (CSP) are used as the calcium carbonate source (energizer) and carbon source, respectively, in the pack carburizing of SCM 420 low carbon steel. The surface hardness of the carburized specimens is investigated for various CSP:DCSP ratios and carburizing temperatures. It is found that a significant improvement in the hardness level is obtained for a DCSP concentration of 40% and a carburizing temperature of 950[Formula: see text]C. It is additionally shown that while DCSP can be used as an energizer in the carburizing process, it cannot be used as an activated carbon source. Finally, it is shown that the surface hardness of the carburized specimens can be significantly improved through a further quenching operation in water. Overall, the results presented in this study confirm the potential for utilizing natural resources such as DCSP and CSP for the pack carburizing of low-to-medium carbon steels.
AVERAGE DISTANCES OF LINDSTRÖM SNOWFLAKE NETWORKS
Authors: ZHAO BING , FAN JIAQI , XI LIFENG
Published: December 2020

In this paper, for renormalized Lindström Snowflake networks, we discuss the geodesic metric of their limit space which is quite different from the Euclidean metric on the Lindström Snowflake. Using the dihedral group, we simplify the geodesic patterns and obtain 10,850 patterns and thus calculate the limit of average distances on renormalized Lindström Snowflake networks.
FRACTAL ANALYSIS OF SHALE GAS TRANSPORT THROUGH MICROPORES AND MICROFRACTURES
Authors: GAO QI , CHENG YUANFANG , HAN SONGCAI , LI YANG , YAN CHUANLIANG , HAN ZHONGYING
Published: December 2020

In order to commercially develop shale gas reservoirs, it is necessary to understand the gas transport mechanisms in shale matrix and how matrix permeability evolves during reservoir depletion. In this work, improved apparent permeability models to describe gas transport through microstructures (i.e. micropores and microfractures) in organic matter (OM) and inorganic matter (iOM) of shale matrix are proposed. The models are able to consider the combined effects of poromechanics, non-Darcy flow, gas sorption and fractal dimension of microstructures on gas flow behavior. The obtained results indicate that microfracture aperture declines by a larger margin than micropore diameter when reservoir depletes. A greater microstructure size fractal dimension and maximum microstructure size lead to a larger apparent permeability, while a greater tortuosity fractal dimension leads to a smaller apparent permeability. In shale matrix, the apparent permeability of inorganic microstructures is much larger than that of organic microstructures. In OM or iOM, when micropores and microfractures have the same cross-section area, the apparent permeability of micropores is larger than that of microfractures. Furthermore, for microstructures in OM, the contribution of different flow regimes to total gas flow varies with pore pressure and microstructure size. For microstructures in iOM, the contribution of slip flow dominates the gas transport. The obtained results provide new insights for understanding gas transport behavior in shale reservoirs from a microscopic perspective.