bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of PVP on gas‐sensing properties of ZnO micro/nanostructure materials in SDS‐PVP composite
Authors: Chen Hiaxia , Yu Hai , Cui Shu , Liu Chengyou
Published: April 2019

ZnO is often used as gas sensor. In order to increase the sensitivity of the sensors, many methods are used to change the gas‐sensing properties. In this paper, ZnO was synthesized by hydrothermal method using Zn (NO3)2 as a zinc source. Sodium lauryl sulfate (SDS) and polyvinylpyrrolidone (PVP) were added into the system to control microstructure and surface morphology of ZnO nanoparticles. The SDS was kept constant, and the PVP was changed. The morphology and composite were investigated by field emission scanning electron microscopy and X‐ray diffraction. The chemical valence of the elements was determined by X‐ray photoelectron spectroscopy. The sensing properties were investigated at different PVP components. It is found that ZnO has a red zinc structure. When the mSDS:mPVP = 1:1, the sensing sensitivity is best. The mechanism of equivalent matching structure optimization performance is proposed.
Two novel ANK1 loss‐of‐function mutations in Chinese families with hereditary spherocytosis
Authors: Hao Lili , Li Shanshan , Ma Duan , Chen Shiyu , Zhang Bowen , Xiao Deyong , Zhang Jin , Jiang Nan , Jiang Shayi , Ma Jing
Published: April 2019

Hereditary spherocytosis (HS) is the most common inherited haemolytic anaemia disorder. ANK1 mutations account for most HS cases, but pathogenicity analysis and functional research have not been widely performed for these mutations. In this study, in order to confirm diagnosis, gene mutation was screened in two unrelated Chinese families with HS by a next‐generation sequencing (NGS) panel and then confirmed by Sanger sequencing. Two novel heterozygous mutations (c.C841T, p.R281X and c.T290G, p.L97R) of the ANK1 gene were identified in the two families respectively. Then, the pathogenicity of the two new mutations and two previously reported ANK1 mutations (c.C648G, p.Y216X and c.G424T, p.E142X) were studied by in vitro experiments. The four mutations increased the osmotic fragility of cells, reduced the stabilities of ANK1 proteins and prevented the protein from localizing to the plasma membrane and interacting with SPTB and SLC4A1. We classified these four mutations into disease‐causing mutations for HS. Thus, conducting the same mutation test and providing genetic counselling for the two families were meaningful and significant. Moreover, the identification of two novel mutations enriches the ANK1 mutation database, especially in China.
The integration of new nurse practitioners into care of older adults: A survey study
Authors: Henni Silje Havrevold , Kirkevold Marit , Antypas Konstantinos , Foss Christina
Published: April 2019

Aims and objectives

To assess Norwegian advanced geriatric nurses’ (AGNs) use of their knowledge and skills, and factors that may influence AGNs’ opportunities to use their knowledge and skills to reach their full potential.

Background

Despite the need for nurses with advanced knowledge and skill in the care of older adults, the introduction of new advanced nursing roles has been challenging. Countries in the process of establishing advanced roles need to monitor and identify possible implementation issues.

Design

A cross‐sectional descriptive survey.

Methods

We invited the total population of AGNs in Norway (n = 26) and some of their colleagues (n = 465) to answer an online questionnaire. Twenty‐three (88.5%) of the AGNs and 195 (42.0%) of the invited colleagues completed and submitted the questionnaires. The data were analysed with descriptive statistics. STROBE guidelines were used in reporting this study.

Results

Of the AGNs, 16 (69.6%) used their knowledge and skills to their full potential when providing direct care. However, a minority used their knowledge and skills to their full potential when proving indirect care (n = 11, 47.8%), teaching/supervision (n = 11, 47.8%) and coordination (n = 5, 21.8%). A total of 47 (24.1%) colleagues experienced the AGNs’ scope of practice as completely clear, and 52 (26.6%) collaborated with the AGNs several times a week. Of the colleagues, 131 (67.2%) considered the AGNs’ role and scope of practice contributed positively to a high degree to health service for older adults.

Conclusion

The results indicate the need for greater focus on organisational adjustment for the AGNs to utilise their knowledge and skills to their full potential.

Relevance to clinical practice

There is a need for greater focus on organisational adjustment to integrate AGNs at the workplace, as complete integration may improve the AGNs’ use of their knowledge and skills.
Using two models of workplace facilitation to create conditions for development of a person‐centred culture: A participatory action research study
Authors: Hardiman Michele , Dewing Jan
Published: April 2019

Aims and objectives

To examine facilitation in workplace learning where nurses are focused on creating person‐centred cultures; to provide a framework for novice and proficient facilitators/practitioners to learn in and from their own workplaces and practices; and to provide the conditions where practitioners can gain an understanding of the culture and context within their own workplace.

Background

Evidence suggests that person‐centred cultures depend on purposeful, facilitated practice‐based learning activities. For person‐centredness to become more meaningful to nursing leaders in their daily work, focus must be placed on their acquisition and use of facilitation skills. The facilitation framework “Critical Companionship” remains an exemplar in the development of expert facilitation skills. Two sequential facilitation models were developed as “steps” towards Critical Companionship, as a framework for novice and proficient facilitators and practitioners to learn in and from their own workplaces and practices.

Design and Methods

This research, situated in a critical social science paradigm, drew on participatory action research to devise, explore and refine two facilitation models: Critical Allies and Critical Friends. The researcher adopted an insider approach to work with five nursing leaders, which was subsequently reported using the EQUATOR guidelines on best practice in reporting of participatory action research.

Results

The results show the complexity of enabling facilitation within the workplace. Four themes and twelve subthemes emerged from the data that describe the attributes needed to facilitate workplace learning and reveal that managers can have an active role in enabling person‐centred culture development.

Conclusions

This research adds to the body of knowledge on developing person‐centred culture. It offers practical stepping stones for novice and proficient facilitators to enable embodiment of the skills necessary to facilitate learning in person‐centred cultures. The models offer a workplace‐friendly pathway with practical methods and further contribute to our understanding of how we create person‐centred cultures.

Relevance to clinical practice

Facilitation of practice development and workplace learning remains the most effective methods to develop person‐centred cultures. This research introduces a pathway for clinical leaders/managers to become facilitators with their own teams, maximising the impact on the culture where care is delivered.
Developing and Piloting a School‐Based Online Adolescent Student‐Athlete Concussion Surveillance System
Authors: Shendell Derek G. , Gonzalez Lauren , Listwan Tracy A. , Pancella Joseph , Blackborow Mary , Boyd Joanna
Published: April 2019

BACKGROUND

Despite increased awareness of concussions, epidemiologic surveillance efforts have been scarce, especially among adolescents. This project, which was developed with school stakeholders (certified athletic trainers [ATCs], nurses, athletic directors), piloted a public secondary school‐based online surveillance tool for interscholastic and intramural sports and physical education‐related concussions in New Jersey during 2014‐2017 school years (SY).

METHODS

Participating public high schools (5 within 4 districts) and career‐technical‐vocational education districts (2 with 5 campuses) completed forms anonymously online via PsychData within 5 days.

RESULTS

There were 208 concussions reported, 115 in 2015‐2016 SY and 93 in 2016‐2017 SY. In fall 2015, 86 concussions were reported, including 16 from summer preseason. In fall 2016, 56 concussions were reported; 3 occurred during preseason. There were 7 concussions reported in winter 2016 and 16 in winter 2017. Twenty‐two concussions were reported in spring of both 2016 and 2017. Most online forms were completed in <10 minutes, usually using either desktop computers or tablets/iPads. School nurses followed by ATCs were primary sources of data entered online, usually by ATCs.

CONCLUSIONS

Cooperation of nurses and ATCs at participating schools suggested online surveillance was valued and viable. Data inform future concussion prevention education and ongoing injury surveillance.
Lexicon for multiparameter texture assessment of snack and snack‐like foods in English, Spanish, Chinese, and Hindi
Authors: Kumar Rajesh , Chambers Edgar
Published: April 2019

Snack food is an important part of human life across the world, in part, due to its convenience, availability, and of course its sensory qualities. Because texture is such a critical aspect of snack foods, a lexicon applicable to various processed and unprocessed snack foods (e.g., crackers, chips, vegetables, yogurt, etc.) is needed. This study also investigated how textures are experienced by vision, hand tactile, lip feel, first bite, multiple bite, and in throat swallowing. This study developed a texture lexicon for various snack foods. Eighty‐five different food products from eight countries around the world were used to create an initial lexicon. The highly trained panel used descriptive analysis techniques to identify 76 texture attributes and develop definitions, techniques, and references for product evaluation. Fifty of the products then were selected and evaluated for intensities using references. Principal component analysis of the data shows that the developed terms differentiated the products. K‐means cluster analysis was done to find the existing clusters between attributes, and correlation analysis used to find the highest correlated and uncorrelated attributes. The article presents attributes, definitions and techniques in English, Hindi, Mandarin Chinese, and Spanish.

Practical application

The texture lexicon developed in this study for various snack foods can be useful for researchers and food manufacturers to identify and describe similarities and differences present in textures of foods to help with product development and assessment of snack categories in various countries. The lexicon can serve as a tool for texture evaluation for correlating descriptive data, consumer preferences and conduct studies with same standards applicable to wide range of products.
New finds of charophytes in Iceland with an update on the distribution of the charophyte flora
Authors: Hrafnsdottir Thora , Ingimarsson Finnur , Ingvason Haraldur R. , Stefánsson Stefán Már , Þorvaldsdóttir Eva G. , Malmquist Hilmar J. , Langangen Anders
Published: April 2019

Charophyte species new to the flora of Iceland are reported and an update on the distribution of the previously known species is given. Four species are new to Iceland;Chara asperaWilldenow,Chara contrariaBraun ex Kützing,Tolypella canadensisSawa andTolypella glomerata(Desvaux) Leonhardi, while four species were previously known:Chara globularisThuiller,Chara virgataKützing,Nitella flexilis(L.) Agardh andNitella opaca(Agardh ex Bruzelius) Agardh. The finding of the species new to Iceland add to the hitherto known worldwide distribution of those species, including a significant extension to the north.
Social Policy Perspectives on Economic Inequality in Wealthy Countries
Authors: Giordono Leanne S. , Jones Michael D. , Rothwell David W.
Published: April 2019

This essay reviews the policy‐oriented literature on economic inequality in wealthy countries published from 2008 to 2018. We focus on this decade because it is a period bookended by both the beginnings of the Great Recession of 2008–2009 as well as the recovery. During this timeframe, attention to inequality by social policy scholars grew substantially, which we argue reflects an interest in both inequality trends as well as redistributive social policy. We observe in the literature sustained efforts to understand both the relationship between social policy and economic inequality, as well as determinants of changes to redistributive social policy. We also note substantial variation in research traditions, as well as opportunities to address substantive, methodological, and theoretical gaps. Our review summarizes the approaches and findings from the literature and discusses the implications of the findings for the study of economic inequality within the academic field of public policy.
Clinical and diagnostic evaluation of intraocular expulsion of a corneal epithelial inclusion cyst in a dog
Authors: Heller Amanda R. , DiFazio Matthew R. , Espinheira Gomes Filipe , Ledbetter Eric C.
Published: April 2019

Case description: An 8‐year‐old spayed female mixed‐breed dog was presented for evaluation of an axial, raised, vascularized, lightly pigmented 3 mm diameter corneal lesion affecting the left eye (OS) that was present since adoption three years prior to presentation. The presumed cyst ruptured into the anterior chamber 5 months following initial presentation with progressive extrusion of intralesional contents into the anterior chamber. High‐frequency ultrasound and in vivo confocal microscopy revealed minimal normal stroma posterior to the corneal lesion. Due to the lack of stroma, a deep anterior lamellar keratoplasty (DALK) was attempted using the viscodissection technique. While separating the stroma from Descemet's membrane, a tear in the membrane was observed, and the procedure was converted to a penetrating keratoplasty (PK). The mass was excised en bloc, and a frozen corneal allograft and conjunctival pedicle graft were utilized to restore corneal thickness. The extruded material was irrigated out of the anterior chamber and submitted for culture and cytology. There was no growth on aerobic, anaerobic, or fungal cultures, and cytology revealed mixed neutrophilic and macrophagic inflammation with keratinizing squamous epithelium. Histopathology identified the mass to be a corneal epithelial inclusion cyst lined with well‐differentiated stratified squamous epithelium. The dog is doing well 10 months post‐operatively with no signs of recurrence along with good comfort and vision.
Application of Bat Algorithm for The Detection of Hidden Nodes in IEEE802.11ah Networks
Authors: Fapohunda Kofoworola , Paulson Eberechukwu Numan , Suleiman Zubair , Saliu Oladimeji , Michael David , Mohammed Yusof Kamaludin
Published: April 2019

Hidden node problem sometimes referred to as frequent packets collision that mostly leads to loss of packets is no longer new in wireless networks because it affects the previous IEEE802.11 standards. The new IEEE802.11ah standard which is also a sub-standard of IEEE 802.11 is no exemption. As a matter of fact, IEEE802.11ah suffers from a hidden node problem more than networks (IEEE 802.11a/b/n/ac) due to their wider coverage which is up to 1km, high number of devices they can support (over 8000 nodes to one AP) and frequent simultaneous sleeping and sending of the nodes (power saving mode). A few researchers have worked on this hidden node problem in IEEE802.11ah but could not get a lasting solution to it. Therefore, this paper proposes an algorithm which detects hidden nodes and also proposes a theoretical solution based on previous works which was also experimentally verified through the BIHD-CM.
Más allá de las moléculas...lo que los clínicos desconocen: Acortando brechas
Authors: Gutierrez Gómez Maria Lucia , Calixto Nuñez Camilo Andrés , Gómez Ana María , Mesa Valentina Lugo , García Guete Maria Margarita , Vivas Ramírez Nicolás , Andrade Moreno Maria De la Paz , Bejarano Rodríguez Juan Pablo , Moros Martín Natalia , Farfan Robles Camila Andrea , Daza Daza Maria Beatriz
Published: April 2019

El propósito de este artículo es explicar, de manera simple, la transcripción de la información codificada en el ADN a un intermediario conocido como RNA mensajero, mediante la expresión génica diferencial. La importancia de este proceso radica en que a pesar de tener todas las células del organismo el mismo genoma, éstas alcanzan diferentes funciones por medio de la activación selectiva de genes, sea en estados fisiológicos o patológicos. Lo anterior inicia gracias a eventos epigenéticos, donde se permite tener acceso al ADN, mediante modificaciones de las histonas. Es así que la secuencia de ADN puede ser leída de múltiples maneras para obtener una gran variedad de proteínas necesarias para el organismo. A partir de lo anterior, se busca facilitar el entendimiento crítico del progreso que ha venido surgiendo en este campo. En las últimas décadas se han generado avances importantes en cuanto a la comprensión del genoma y su constitución. Gracias a esto, se han desarrollado investigaciones que buscan determinar las aplicaciones clínicas de los procesos involucrados en la expresión génica diferencial, de manera que se pueda fomentar una mejor comprensión de las enfermedades comunes, posibles tratamientos y métodos diagnósticos para realizar un mejor abordaje de las mismas.
Flow Transitions for Flow Through a Pipe With a Twisted Tape Insert
Authors: Chaware Parag , Sewatkar C. M.
Published: April 2019

Insertion of twisted tape in a pipe provides heat transfer augmentation due to swirl formation inside the pipe. Understanding of the transitions of such a swirling flow is an important fluid flow problem. This problem has been studied numerically for H/D = 8.0 and 700 ≤ Re ≤ 1400, where H is the pitch of the twisted tape, D is the diameter of the pipe, and Re is the Reynolds number based on the pipe diameter. The results obtained with large eddy simulations (LES) of such a flow are used in the present work to explore the transitions in the flow through a pipe with twisted tape insert. It is observed that the flow is steady laminar for Re ≤ 700 and changes to periodic laminar flow for 700 ≤ Re ≤ 1126. During this flow regime, the flow occurs with sinusoidal variation of streamwise velocity which exhibit single frequency in the flow. For 1126 ≤ Re ≤ 1263, the flow behavior is quasi-periodic in nature and the time series of streamwise velocity shows two incommensurate frequencies namely primary and secondary frequencies with harmonics in the form of linear combination of primary and secondary frequencies. Further, for 1263 ≤ Re ≤ 1400, the flow transits to chaotic behavior. These transitions have been obtained through a bifurcation analysis of instantaneous streamwise velocity signals captured at a point where maximum fluctuations are likely to occur. It is noticed that the Hopf bifurcation occurs three times as flow changes from steady laminar to chaotic flow. It is further observed through the vorticity contours that, at low Reynolds number, the rate of vorticity generation is low and this vorticity is transported by mere diffusion. Beyond critical Reynolds number, the vorticity pumped from boundary layer into the shear layer is high and diffusion is not sufficient to transport the vorticity and hence the convection of vorticity sets in. This causes the vorticity shedding in the flow, and hence, the fluctuations in the velocity. These results should help to improve the understanding of transitions in the flow through a pipe with twisted tape insert.
Ultrafast Tunable Near-Field Radiative Thermal Modulator Made of Ge3Sb2Te6
Authors: Lu Lu , Song Jinlin , Zhou Kun , Ou Han , Cheng Qiang , Luo Zixue
Published: April 2019

We show numerically the phase change material Ge3Sb2Te6 (GST) with special configuration as a heat modulator in the regime of near-field radiative heat transfer (NFRHT). The ability of GST to allow ultrafast reversible switch between two phases endows it great potential in practical modulation application. By designing silicon carbide (SiC) nanoholes (NHs) filled with GST, this configuration could achieve a considerable modulation effect and large near-field radiative heat flux. The underlying mechanism can be explained by the observation that the entire configuration supports either hyperbolic modes or surface phonon polaritons (SPhPs) resonance modes and even the combination of both modes, thereby resulting in the remarkable modulation effect. In addition, the effects of the volume filling factor and graphene coverage are also investigated at the vacuum gap distance of 100 nm. With graphene coverage, the modulation factor can be further improved to as high as 0.72 achieved at the volume filling factor of 0.6 with temperature difference of 20 K. The proposed configuration has the potential to effectively modulate heat in the near-field regime for designing heat modulation applications in the future.
Dissection Versus Incubation: The Within-Subject Effects of Product Dissection Activities on Design Variety
Authors: Starkey Elizabeth M. , Alzayed Mohammad Alsager , Hunter Samuel , Miller Scarlett R.
Published: April 2019

Product dissection is a popular educational tool in engineering design due to its ability to help students understand a product, provide inspiration for new design ideas, and aid in product redesign. While prior research has investigated how dissecting a product before idea generation impacts the creative output of the ideation session, these studies failed to look at the types of ideas generated before dissection or how the type of product dissected impacts this. Thus, the goal of the current study was to examine how product dissection impacts the solution space explored by students. Fifty-five undergraduate engineering students participated in the experiment; 40 participants virtually dissected a product, while the remaining 15 completed a personality test. The results of the study highlight that students explored new types of ideas during the second ideation session for all conditions and at all levels, with students having the biggest increase in embodiment variety when they dissected analogically far products. Overall, there were no differences in design variety between students in the dissection condition and the incubation condition. This study highlights how incubation can impact design variety and calls for further investigation of the interaction between product dissection and incubation.
Performance Analyses and Evaluation of Co2 and N2 as Coolants in a Recuperated Brayton Gas Turbine Cycle for a Generation IV Nuclear Reactor Power Plant
Authors: Osigwe Emmanuel O. , Gad-Briggs Arnold , Nikolaidis Theoklis , Pilidis Pericles , Sampath Suresh
Published: April 2019

As demands for clean and sustainable energy renew interests in nuclear power to meet future energy demands, generation IV nuclear reactors are seen as having the potential to provide the improvements required for nuclear power generation. However, for their benefits to be fully realized, it is important to explore the performance of the reactors when coupled to different configurations of closed-cycle gas turbine power conversion systems. The configurations provide variation in performance due to different working fluids over a range of operating pressures and temperatures. The objective of this paper is to undertake analyses at the design and off-design conditions in combination with a recuperated closed-cycle gas turbine and comparing the influence of carbon dioxide and nitrogen as the working fluid in the cycle. The analysis is demonstrated using an in-house tool, which was developed by the authors. The results show that the choice of working fluid controls the range of cycle operating pressures, temperatures, and overall performance of the power plant due to the thermodynamic and heat properties of the fluids. The performance results favored the nitrogen working fluid over CO2 due to the behavior CO2 below its critical conditions. The analyses intend to aid the development of cycles for generation IV nuclear power plants (NPPs) specifically gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs).
An advanced sensor platform for acoustic quantification of the ocean twilight zone
Authors: Lavery Andone C. , Stanton Timothy K. , Jech J. Michael , Wiebe Peter
Published: April 2019

The ocean twilight zone (OTZ) is the vast, globe-spanning, layer of water between 200 and 1000 m depth—home to diverse communities of small fishes, cephalopods, crustaceans, and gelatinous organisms. Yet, little is known about the biology, abundance, biomass, and distribution of these organisms. The OTZ is difficult to sample due to a combination of organism patchiness and avoidance, and difficulties capturing fragile species. Recent evidence suggests that the global OTZ biomass may be sufficient to commercially harvest. Furthermore, much of this biomass performs daily vertical migration (DVM) and may play a potentially critical role in regulating Earth’s climate through the export of carbon to the deep ocean. Deep-See, an advanced senor platform, was developed to fill the technological void for characterizing the OTZ. This towed vehicle integrates wide-band, split-beam acoustics (1–500 kHz) with optical, environmental, and eDNA sensors that can address many of the challenges associated with sampling in the OTZ. Data from the inaugural cruise in August 2018 highlight that (i) a surprisingly high abundance of organisms can be found outside the dense sound scattering layers and (ii) the target strength of many organisms that perform DVM changes with the depth, which is critical to estimate biomass.
Should hybrid and electric vehicles have acoustic alerting systems?
Authors: Weinandy Rene , Schade Lars , Gebhardt Jan
Published: April 2019

Noise is an oft-overlooked environmental issue within densely populated regions. Vehicles, railways, and airports operating within or near cities are all contributing to the growing noise pollution problem—causing negative health and economic impacts. Due to this, it is of primary importance to make our cities quieter. The German Environment Agency is working on noise and its effects on humans, especially with respect to policy in order to make traffic as quiet as possible by addressing all the relevant elements from roads and tracks to vehicles, operational procedures, and measures along the sound propagation path. Europe, as well as most of the world, faces a future full of environmentally friendly hybrid or pure electric road vehicles. Concerns were raised that these low-emission vehicles could pose a risk to blind and low vision pedestrians. To address this concern, the European Union has legislated that future hybrid and pure electric cars must be equipped with acoustic vehicle alerting systems (AVAS). The presentation provides a critical assessment of the effectiveness of AVAS and of their negative side effects. Furthermore, it explores alternative non-acoustic approaches addressing aspects such as environmental protection, road safety, feasibility, and usability.
Data-driven methods in a model-driven world: Making sense of auditory classification images for continuous speech
Authors: Venezia Jonathan
Published: April 2019

Some of my recent work has focused on the development of Auditory Bubbles, a method for generating classification images that show the acoustic features underlying different percepts of continuous speech. Auditory Bubbles work by applying randomly shaped spectrotemporal filters to the modulation power spectrum of sentence-level speech stimuli. A reverse correlation is then used to relate the filter patterns to a behavioral outcome (e.g., keyword recognition). This technique is data driven—i.e., a computational approach (regression) is taken to estimate the relation between stochastically varying acoustic-speech features and listener responses (the classification image). For a complex stimulus such as continuous speech, this relation may be determined by multiple underlying factors—e.g., task demands, listener characteristics, response strategies, and perceptual acuity. As such, it can be difficult to interpret classification images, which (blindly) reflect the combined influence of these underlying factors. In this talk, I present the classification images from multiple speech experiments comparing (a) different stimuli (single- versus multi-talker), (b) different tasks (intelligibility versus emotion perception), and (c) different listener groups (persons with versus without hearing loss, musicians versus non-musicians) and discuss preliminary efforts to constrain the interpretation of classification images by appealing to the tenets of signal detection theory.
High frequency cavity modes of a Helmholtz resonator excited by an air jet
Authors: Shaw Emma , Cottingham James P. , Stills Robert
Published: April 2019

In 1990, Khosropour and Millet reported on a study of the internal spectrum of a Helmholtz resonator excited by an air jet and reported that the data for frequency and amplitude of the Helmholtz mode as a function of jet speed show a series of domains separated by narrow transition regions [JASA 88, 1211–1221 (1990)]. The idea was to observe the behavior of the air jet when the resonator effectively has just a single mode, and does not overblow to higher frequency modes at moderate jet velocities. Further research explored the effects of changes in neck length and jet angle, but higher resonator modes were ignored. This paper presents characterizations of some of the higher modes of cavity vibration, which can be excited at high jet velocities. Unlike the Helmholtz mode, these modes depend on the shape of the cavity shape as well as the volume. Several of these modes were observed, sometimes with more than one mode sounding simultaneously. Guided by finite element simulations, the nature of these higher cavity modes was verified experimentally by observing frequencies and locating nodal surfaces.
Control of vocal loudness in singing
Authors: Titze Ingo R.
Published: April 2019

Vocal loudness in sones is quantified on the basis of changes in spectral slope and harmonic tuning in a range of singing fundamental frequencies of 125 Hz to 1000 Hz. Spectral slope of the mouth output pressure is bracketed in the range of -3 dB/octave to -12 dB/octave to reflect a typical glottal spectrum from breathy to pressed adduction. To approximate formant tuning of harmonics, the SPL level of the first three harmonics is raised by 10, 20, and 30 dB. It is shown that spectral slope change is more effective in increasing vocal loudness than tuning a single harmonic with a vocal tract resonance. Some applications to amplified and unamplified vocal production and respective training are given.
Prevention of structural shorts in highly engineered noise and vibration isolation systems
Authors: Born Alexander C. , Harkin Sean
Published: April 2019

Noise and vibration isolation in structures is becoming more and more common as the world we live in becomes noisier and noisier. The increase in noise coupled with people’s desire for lower background noise and vibration criteria results in the need for higher performing isolation systems. In order to achieve these performance levels, the system needs to be properly designed and engineered. One of the most common culprits for a system not providing the expected performance calculated during the design process is a short or sound bridge . A short typically occurs during the installation of the system by rigidly connecting the structure or machine that is being isolated to an unisolated element. This causes noise and vibration from sources such as subway, transit, and mechanical equipment to transfer with ease into the structure intended for isolation, rendering the highly engineered system useless or highly degraded. This paper will examine a multitude of ways to eliminate the possibility of a short and elaborate on the importance of the installation process of isolated systems. It will also review how the process differs when isolating for vibration compared to noise and the importance of each.
Early history of nonlinear acoustics: Waveform distortion, disaster, and redemption
Authors: Blackstock David T. , Hamilton Mark F.
Published: April 2019

The first (although slightly incorrect) wave equations for finite-amplitude sound in lossless fluids were obtained independently by Euler in 1759 and Lagrange in 1760. Poisson (1808) provided the first major breakthrough with his exact solution for progressive waves of finite amplitude in a lossless gas. Although a far-reaching result, the progressive waveform distortion (and disastrous consequences) implied by his solution went unrecognized for 40 years. Challis (1848) showed that the Poisson solution is not single valued but did not understand why. Stokes (1848) provided the why. He saw that the Poisson waveform distorts as the wave travels, eventually threatening to become multivalued. He postulated that a discontinuity (shock) develops to avoid waveform overturning. He also saw that viscosity (not accounted for by Poisson) would prevent true discontinuities. Earnshaw (1860) and Riemann (1860) cleaned up plane waves in lossless gases. However, how to predict propagation after shocks form? Rankine (1870) and Hugoniot (1887, 1889) provided the first solutions for propagation when dissipation is included. These were the first steps toward redemption. The curtain rang down on this era of nonlinear acoustics with the excellent papers in 1910 by Rayleigh and Taylor on steady shocks in a thermoviscous fluid.
Sonic booms and sonic thumps for non-specialists
Authors: Sparrow Victor
Published: April 2019

One of the most straightforward applications of nonlinear acoustics is in the long range propagation of the shock waves created by supersonic aircraft. The sounds heard on the ground are either loud (sonic booms) or are quiet (sonic thumps) depending on the pressure versus time signature. This talk with give a brief overview of sonic booms and the role nonlinear acoustics plays in their propagation. The carpet of sounds heard on the ground from an example single flight will be shown. The role of nonlinear acoustics in the certification of future supersonic low-boom aircraft will be highlighted. Much more information about sonic boom is freely available from ntrs.nasa.gov, and one great reference is “Sonic Boom” by Maglieri, et al. (NASA/SP-2014-622). [Work supported by the U.S. Federal Aviation Administration Office of Environment and Energy through ASCENT, the FAA Center of Excellence for Alternative Jet Fuels and the Environment, Project 41 through FAA Award Number 13-C-AJFE-PSU under the supervision of Sandy Liu. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA.]
Audio spotlight: Sound from ultrasound
Authors: Pompei Joseph
Published: April 2019

The Audio Spotlight® is the trade name of the first and only commercially successful ultrasonic loudspeaker, and delivers a laser-like beam of sound as tight as a beam of light. This allows audio to be delivered to one listener or a small group, without disturbing others nearby, or sound can be projected to create “true surround sound” without multiple loudspeakers. Originally developed at MIT, the technology is used widely in a variety of fields, such as museums, libraries, hospitals, and retail displays. This invited lecture will present an overview of the nonlinear acoustics as a basis for such a device, as well as some specific engineering challenges. Commercial applications will be discussed, and live demonstrations are included.
Nonlinear focusing of high amplitude sound using time-reversal
Authors: Patchett Brian D. , Anderson Brian E. , Willardson Matthew L. , Denison Michael
Published: April 2019

Time reversal (TR) is a signal processing technique that may be used to intentionally generate high amplitude focusing of sound. The use of time reversal in room acoustics has been studied by others, but the application to generating high amplitude focusing has not previously been explored. The purpose of this study is to generate high amplitude sound waves in order to mimic a virtual spherical source with enough intensity to observe nonlinear wave propagation. Experiments have been carried out in a reverb chamber with eight compression horn drivers. Using these drivers, the impulse response is calculated, reversed in time, and modified using the clipping technique. When these signals are broadcast from the sources, a focus is generated at the receiver location with peak levels reaching 198 dB (ref 20 μPa). As the waves superpose at the focus, the amplitudes observed do not scale linearly when the experiment is repeated at increasing amplification levels. The compression peaks are higher in amplitude than expected, and the rarefaction troughs are lower in amplitude (less negative) than expected, when compared to linear scaling. Additionally, the diverging waves from the focus resemble the propagation of a single spreading shockwave.
Simulation of the second harmonic ultrasound field in heterogeneous soft tissue using a mixed domain method
Authors: Gu Juanjuan , Jing Yun
Published: April 2019

A mixed-domain method dubbed frequency-specific mixed domain method is introduced for the simulation of the second harmonic ultrasound field in weakly heterogeneous media. The governing equation for the second harmonics is derived based on the quasilinear theory. The speed of sound, nonlinear coefficient, and attenuation coefficient are all spatially varying functions in the equation. The fundamental frequency pressure field is first solved by the frequency-specific mixed domain method, and it is subsequently used as the source term for the second harmonics equation. This equation can be again solved by the frequency-specific mixed domain method to rapidly obtain the second harmonic pressure field. Five two-dimensional cases, including one with a realistic human tissue map, are studied to systematically verify the proposed method. Results from the previously developed transient mixed domain method are used as the benchmark solutions. Comparisons show that the two methods give similar results for all cases. More importantly, the frequency-specific mixed domain method has a crucial advantage over the transient mixed domain method in that it can be two orders of magnitude faster.
Backward recognition masking of similar and dissimilar environmental sounds
Authors: Clark Kelli , Holtz Allison , Srinivasan Nirmal Kumar , Gaston Jeremy , Perelman Brandon
Published: April 2019

Backward Recognition Masking (BRM) of sound occurs when two sounds are presented close in time to one another and the second sound hinders the recognition of the first sound. Previous studies on BRM used either white noise or sine tones. Here, we present backward recognition thresholds using environmental sounds. 34 young normal hearing individuals were presented with 6 combinations of similar or dissimilar environmental sounds from the categories of household appliances, automobiles, and power tools. The sounds were selected based on their multi-dimensional scaling distances (Rosen et al., 2017). The sounds were presented at 20 dB SL re: 3 frequency PTA and the inter stimulus interval was fixed at 22.2 ms. A two-down one-up adaptive procedure was used to identify the target duration at which the listeners could identify that the target is different from the masker. Initial data analyses indicated that similar sounds needed significantly longer presentation durations to be identified as different compared to dissimilar sounds, indicating more backward masking for similar sounds compared to dissimilar sounds. These results potentially highlight how critical safety information in real-world environments may be missed in complex listening scenarios.
The effects of modulator shape and methods for expressing modulation depth on spectral modulation detection thresholds
Authors: Isarangura Sittiprapa , Palandrani Katherine , Stavropoulos Trevor , Seitz Aaron , Hoover Eric C. , Gallun Frederick J. , Eddins David A.
Published: April 2019

The detection of sinusoidal modulation is commonly used for assessing the auditory perception of temporal, spectral, and spectro-temporal acoustic features. For temporal (amplitude) modulation, the sinusoidal modulator usually is expressed on a linear amplitude scale. For spectral modulation, the sinusoidal modulator has been specified on a linear amplitude scale, consistent with temporal modulation, or on a logarithmic amplitude scale, with the notion of approximating a sinusoidal excitation pattern. The definition of modulation depth depends on the measurement points (i.e., midpoint to peak or peak to peak) and order of operations when expressing depth in dB. Such differences can make it difficult to compare results for similar tasks among investigations. Here we quantify differences among methods and provide a complete matrix for translating among methods. Spectral modulation detection was measured for 9 normal-hearing listeners in ten conditions (linear vs. logarithmic shape at 0.5, 1, 2, 4, and 8 cycles/octave). Peak-to-peak values of the modulation envelope were equalized, thus only modulation waveform shape differed. Noise carriers had a passband from 400 to 3200 Hz. Thresholds revealed statistically significant effects of both spectral shape and spectral modulation frequency. Several methods for expressing threshold modulation depth were compared to highlight differences among the methods.
Masking of short tones in noise: Evidence for envelope-based, rather than energy-based detection
Authors: Jennings Skyler G. , Chen Jessica
Published: April 2019

A short tone added to a longer simultaneous masker may be detected by observing an increase in overall acoustic energy. This detection scheme predicts probe thresholds to be independent of the masker’s temporal envelope. A recent study [Jennings et al., J. Assoc. Res. Oto. 19, 717–727 (2018)] revealed that probe thresholds were 10 dB higher for maskers with flattened compared to fluctuating envelopes, suggesting an envelope-based detection strategy. This study test the hypothesis that probe thresholds are proportional to envelope power by measuring detection thresholds for a 4-kHz, 6-ms probe in one of three temporal positions within a 400-ms masker in normal-hearing listeners. The narrow-band, low-fluctuating noise masker was preceded by flattened or fluctuating noise precursors. The precursor’s offset was delayed from the masker’s onset by -2, 0, 10, 25, 100, or 250 ms. Probe thresholds were positively correlated with envelope power (R-squared = 0.75), consistent with masking from precursor envelope fluctuations and from fluctuations introduced by precursor and masker ramps. These findings suggest that future modeling efforts for short probes presented in longer maskers should consider a decision variable based on envelope fluctuations.
ManyBabies1: Infants' preference for infant-directed speech
Authors: Soderstrom Melanie
Published: April 2019

There is growing concern about the replicability of basic findings in psychology, including in infancy research (Frank et al., 2017). ManyBabies is a large-scale international collaboration to replicate basic empirical findings in infancy. Our first project is ManyBabies1, which examines infant preference for infant-directed speech (IDS). Over 70 laboratories collaborated to collect data from over 2500 infants aged 3–15 months. Stimuli consisted of speech produced in a semi-naturalistic elicitation task where fifteen different mothers who spoke North American English talked about a series of novel and familiar objects to their infant and separately to an experimenter. A set of 8 passages each in IDS and adult-directed speech (ADS) were created after a comprehensive norming process. Infants were tested in 3 primary methods: eyetracking, central fixation and headturn preference. Overall, the effect of preference for IDS was replicated, although the calculated effect was smaller than that reported by meta-analysis (Dunst et al., 2012, metalab.stanford.edu). Preference for IDS increased across development. The success of this project shows that infant research conducted collaboratively and at-scale can answer new questions about the replicability and generalizability of infant findings across different laboratory, methodological, and infant participant characteristics.
Infant-directed speech facilitates neural encoding of speech during infants’ first year of life
Authors: Kalashnikova Marina
Published: April 2019

Infant-directed speech (IDS) is the special speech register that parents use when addressing young infants. Compared to adult-directed speech (ADS), it is characterised by positive affect, high pitch and wide pitch range, and acoustically exaggerated speech sounds. These acoustic components of IDS have been proposed to facilitate early language acquisition by attracting infants’ attention to speech, or by providing them with a type of speech input that is easier to perceive and learn, or both. Indeed, infants are more successful in a variety of behavioural language processing tasks when presented with IDS stimuli, but it is unclear whether these effects are due to the linguistic function of IDS or solely to its attention-grabbing qualities. I will present three studies that address this question by directly measuring infants’ neurophysiological responses to IDS and ADS. Our findings demonstrate that IDS elicits greater neural activation and more mature neural response patterns compared to ADS in measures of neural entrainment to continuous speech, phonemic discrimination, and semantic processing in 4-to-9-month-old infants. This evidence indicates that beyond capturing infants’ attention to speech, IDShas a privileged status in facilitating neural encoding of speech, which may augment infants’ early speech processing and even later language development.
Using naturalistic paradigms to study how adult speakers accommodate infant listeners’ unique processing demands
Authors: Piazza Elise A. , Lordan Marius Catalin , Hasenfratz Liat , Hasson Uri , Lew-Williams Casey
Published: April 2019

Communication is inherently social and requires an efficient exchange of complex acoustic cues between individuals. What are the behavioral and neural processes that allow young listeners to understand, couple to, and learn from adult speakers in complex, everyday interactions? In one study, we recorded mothers’ natural speech during play and reading and uncovered a pervasive timbre fingerprint of infant-directed speech (IDS) that generalized across 10 diverse languages. Classification of IDS and adult-directed speech (ADS) was driven by a statistical summary measure that concisely describes the vocal spectrum and could not be explained by pitch alone. In a second study, using dual-brain functional near-infrared spectroscopy (fNIRS), we measured the real-time neural dynamics of communication between infants and adults during natural interaction. We found that the infant prefrontal cortex (PFC) tracked several communicative cues, including the adult’s pitch variability, with high temporal precision. Furthermore, infant-adult neural coupling was significantly greater when the members of a dyad interacted with each other than when they performed control tasks. Surprisingly, PFC activation in the infant brain slightly preceded similar activation in the adult brain, which crucially advances our understanding of children’s influence over the accommodative behaviors of the caregivers around them during everyday communication.