bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of flood frequency analysis to data record, statistical model, and parameter estimation methods: An evaluation over the contiguous United States
Authors: Hu Lanxin , Nikolopoulos Efthymios I. , Marra Francesco , Anagnostou Emmanouil N.
Published: November 2019

The current statistical methods applied in flood frequency analysis require long data records to obtain reliable estimates, particularly for long return periods. Moreover, the choice of the statistical model and the parameter estimation procedure may introduce uncertainty in the estimates. In this work, we investigate the sensitivity of flood frequency analysis to various sample sizes, statistical models, and parameter estimation methods over six major hydrological regions in the contiguous United States. Results show that flood frequency estimates based on annual maximum series approach convergence to the reference values (estimates derived from 70 years record) in terms of median for 35‐year or longer records. However, the uncertainty remains significant and a record of 35 years (20 years) is associated with ~50% (100%) larger uncertainty on the estimated 100‐year flood. The generalised extreme value distribution combined with maximum likelihood estimation method is associated with the largest uncertainty, while the log‐Pearson type III exhibits comparable bias and smaller uncertainty. Application of the partial duration series approach to 20‐year records shows no significant advantage. Our findings suggest that the hydroclimatic characteristics of the catchments exhibit limited impact on the uncertainty.
An Innovation Center Model to Transform Health Systems to Improve Care of Older Adults
Authors: Allen Kyle , Hazelett Susan , Martin Michael , Jensen Christine
Published: November 2019

The US population is aging faster than at any other time in our history. This growth, coupled with a slow adaptive health policy framework, is creating an urgent need to reengineer and improve the quality, safety, and cost‐effectiveness of health systems to meet the needs of older adults and embrace the success we have achieved with longevity. Without rapid adoption of evidence‐based models that are known to improve safety and health outcomes, we significantly jeopardize the lives of thousands of older adults receiving care under our current health systems' processes and models. This article describes an innovation and operations infrastructure that was successfully tested in two independent and geographically distinct community health systems. This operations and implementation framework can be scaled and used to accelerate the changes needed to improve care for older adults in health systems throughout the United States. J Am Geriatr Soc 68:15–22, 2019
Understanding Thai consumer attitudes and expectations of ginseng food products
Authors: Doungtip Peerarat , Sriwattana Sujinda , Kim Kyung T.
Published: November 2019

Ginseng is now increasingly popular in Thailand because of its multifunctional health properties. However, the recognition and acceptance of ginseng food products in Thailand have been limited. The objectives of this research were to investigate consumer attitudes toward ginseng products and to obtain useful information to develop ginseng food products that meet the expectations of Thai consumers. Consumer surveys and focus group interviews were conducted. The 430 respondents participated in the consumer surveys. Six focus group interviews (n = 51) were also conducted. Results showed that most Thai consumers know ginseng. Ginseng is representative of a healthy image. Consumers wanted new products, such as beverages, and this product should be easily absorbed or digested. For focus group interviews, older participants (more than 40 years old) had positive impressions toward ginseng food products in contrast to young participants. Participants were concerned about convenience, price, and taste and aroma of new ginseng products.

Practical applications

The study of Thai consumer attitudes and expectations of Korean ginseng products posed an interesting challenge and could provide information for promoting Korean ginseng in Thailand. The results of this research can be used for idea generation and further development studies on ginseng products. Advertisement and education may also increase consumption of ginseng food products among Thai consumers.
Vancomycin therapeutic drug monitoring in paediatrics
Authors: Patel Joanne , Lucas Catherine J , Ryan Jessica , Jenkins Michelle , Martin Jennifer H
Published: November 2019

Aim

Vancomycin guidelines for therapeutic drug monitoring (TDM) aim to maximise efficacy while minimising toxicity and resistance. Vancomycin is effective against Staphylococcus aureus when it achieves area under the concentration–time curve (AUC)/minimum inhibitory concentration (MIC) > 400. Studies in children have shown that target trough concentrations poorly correlate to AUC/MIC > 400; however, they are used in practice for clinical convenience. This review in paediatric inpatients aims to audit performance against TDM guidelines and consider what changes are needed to optimise vancomycin monitoring.

Methods

Vancomycin prescriptions in patients younger than 18 years old were collected over a 15‐month period. Primary outcome measures were vancomycin initial dose (mg/kg/day) and the timing and result of first trough concentration (mg/L). Secondary outcome measures were the numbers achieving recommended targets and whether appropriate dose adjustments were made in response to TDM.

Results

A total of 133 courses reached the time when TDM should occur. Average patient age was 6.5 years, and the average initial dose was 52.55 mg/kg/day (range 19.05–86.54 mg/kg). Only 25% of courses (n = 34) had a trough concentration measured at the recommended time. The mean trough concentration was 11.6 mg/L (range < 2.0–39.7). Of 40 patients with a low trough concentration, 50% continued without dose adjustment.

Conclusion

As shown in the literature, there is a poor correlation between the vancomycin dose given and the trough concentration achieved. Given that recommendations for trough concentration monitoring are designed to simplify the process yet are poorly adhered to, a strategic plan to address these issues is needed.
Licensing versus assignment: Innovation transfer in an asymmetric duopoly
Authors: Niu Shuai
Published: November 2019

Suppose that the relatively inefficient firm in an asymmetric duopoly market develops a nondrastic process innovation. To maximize returns on the innovation, the innovator must determine the most lucrative commercial policy. Should it be in‐house exploitation, or licensing or assignment? It turns out that the innovator never uses innovation exclusively. The choice of licensing or assignment depends on the size of the initial cost difference. When the initial cost difference is relatively small, the innovator would resort to licensing, whereas when there is a significant initial cost gap, the innovator would rather assign the property rights of the innovation to the rival. In the case of assignment, the assignee may license the innovation back to the assignor. With the option of reverse licensing, an assignment will always be more profitable than (direct) licensing. Interestingly, if the initial cost gap were sufficiently large, the innovator would exit the market postassignment, and thus act as an outside nonoperating licensor.
Re‐Examining the Case for a Vertical Industrial Policy in Mexico: A Step Backward or Forward?
Authors: Zaga Szenker Daniel
Published: November 2019

This article examines the evolution of Mexican industrial policy since World War II. From the 1950s, Mexico intervened actively in the economy, closed it off from international competition, and achieved high economic growth rates. At the same time, it faced serious imbalances in fiscal and external accounts, which resulted in the debt crisis of the early 1980s. Afterward, Mexico left the productive sphere and allowed the market to rule the economy through a horizontal industrial policy, resulting in slower economic growth rates but less macroeconomic imbalance. This study suggests that Mexico needs to follow a long‐term vertical industrial policy approach, avoiding fiscal and external account deficits and favoring activities or economic sectors associated with higher levels of productivity, innovation, and technological capacities, which contribute to enhance local productive linkages and positive dynamic externalities. By doing so, it will certainly accelerate its long‐term economic growth.
CXCL1 is upregulated during the development of ileus resulting in decreased intestinal contractile activity
Authors: Docsa Tibor , Bhattarai Deepa , Sipos Adam , Wade Charles E. , Cox Charles S. , Uray Karen
Published: November 2019

Background

Although the development of ileus is widespread and negatively impacts patient outcomes, the mechanism by which ileus develops remains unclear. The purpose of our study was to examine the contribution of myogenic mechanisms to postoperative ileus development and the involvement of inflammation in mediating intestinal smooth muscle dysfunction.

Methods

Contractile activity and the effects of CXCL1 were studied in a gut manipulation model.

Key Results

Contraction amplitude in the ileum decreased significantly, while tone increased significantly in response to gut manipulation. Differences in contraction amplitude were affected by tetrodotoxin at earlier time points, but not at later time points. Agonist‐induced contractions in the small intestine decreased significantly with ileus development. Intestinal transit slowed significantly after the induction of ileus. Myosin light chain phosphorylation was significantly decreased and edema increased significantly in the intestinal wall. Conditioned media from mechanically activated macrophages depressed intestinal contractile activity. CXCL1 (GroA) was significantly increased in the mechanically activated macrophages and intestinal smooth muscle within 1 hour after induction of ileus compared with control cells and sham animals, respectively. Treatment with CXCL1 significantly decreased contraction amplitude and agonist‐induced contractile activity and increased tone in the small intestine. In the gut manipulation model, treatment with a CXCR2 antagonist prevented the decrease in agonist‐induced contractile activity but not contraction amplitude.

Conclusions & Inferences

These data suggest that CXCL1, released from macrophages during intestinal wall stress, can suppress intestinal contractile activity. CXCL1 is a potential target for preventing or treating ileus in trauma patients.
Cutaneous ultrasound and its utility in Pediatric Dermatology: Part II—Developmental anomalies and vascular lesions
Authors: Rodríguez Bandera Ana Isabel , Sebaratnam Deshan Frank , Feito Rodríguez Marta , de Lucas Laguna Raúl
Published: November 2019

High‐frequency ultrasonography represents a promising tool for pediatric dermatologists. It is a noninvasive and harmless diagnostic technique that is especially appealing when working with children. It can be easily performed at the patient's bedside, avoiding diagnostic delays, sedation, or multiple visits. It represents a useful adjunct to clinical examination and aids our understanding of cutaneous pathology. In this second part, we describe the ultrasonographic findings of developmental anomalies and vascular lesions.
Offshore versus Onshore Sourcing: Quick Response, Random Yield, and Competition
Authors: Jung Seung Hwan
Published: November 2019

Motivated by the recent reshoring initiatives, we study firms’ global sourcing strategies from two different supply sources, offshore and onshore supply bases, under supply and demand uncertainty. Interestingly, even though onshore sourcing has a significant benefit from market responsiveness, offshore sourcing having no cost advantage also provides benefits in the presence of yield uncertainty and market competition. If competing firms commit single sourcing, one firm may choose inferior offshore sourcing to dampen competition. When a dual‐sourcing option is available, firms always utilize dual sourcing, offshore sourcing as well as onshore sourcing, for risk pooling purpose. Our result shows that risk pooling is an essential driver in supplier selection in that the need for dual sourcing cannot be eliminated by other influential factors (e.g., responsiveness and competition effect). However, we find that firms may suffer from a dual‐sourcing option under competition. This contrasts with the conventional wisdom that dual sourcing benefits firms in the presence of supply uncertainty. When it comes to order allocation, market responsiveness is not necessarily an order winner since it does not lead to a larger order to an onshore supplier if demand is guaranteed above a certain level. Under competition, firms’ order allocation is mainly determined by supply yield correlations.
Dismissing the “Vocal Minority”: How Policy Conflict Escalates When Policymakers Label Resisting Citizens
Authors: Wolf Eva Elizabeth Anne
Published: November 2019

This article investigates, through the theory of social construction and policy design, the feedforward effects of labeling on policy conflicts. It argues that such conflicts escalate when policymakers distinguish between more and less deserving and more and less powerful segments of the population. It draws on the empirical analysis of 32 narrative interviews with vital stakeholders in the conflict over the contested multibillion‐euro Oosterweelconnection highway in Antwerp (Belgium), as well as on the media analysis of 739 articles. According to such analyses, Flemish policymakers became increasingly hostile toward action groups as the latter moved beyond conventional policy‐making procedure, labeling them as a powerful but undeserving “vocal minority.” Meanwhile, they endorsed the Oosterweel policy, claiming that it represented an increasingly powerless but deserving “silent majority.” However, labeling action groups as powerful but undeserving and consequently dismissing them resulted in the escalation of a substantive policy conflict to a relational policy conflict, which became increasingly difficult to settle as parties fought each other rather than fighting over policies.
Does corporal punishment erode the quality of the mother–child interaction in early childhood?
Authors: Laible Deborah , Davis Alexandra , Karahuta Erin , Van Norden Clare
Published: November 2019

Corporal punishment is believed to exert its influence partially on children's externalizing behavior by undermining the quality of parent‐child relationships, but empirical evidence for this belief is lacking. Thus, the goal of this study was to explore longitudinally whether the use of corporal punishment by mothers was associated with declining quality in parent‐child interactions and whether these declines mediated the links between corporal punishment and later externalizing behavior. Based on data from the NIHCD SECCYD, the findings from this study indicated that the links between the quality of parent‐child interaction and corporal punishment were bidirectional: high quality parent‐child interaction was associated with less use of subsequent corporal punishment by mothers, and maternal use of corporal punishment at 36 months was associated with declines in the quality of parent‐child interaction at 54 months. There were not significant indirect effects of corporal punishment at 36 months on grade 3 aggression through 54 month parent‐child interaction quality, however, which suggests other mechanisms might account for the links between early corporal punishment and later externalizing problems.
Social Distance Reexamined: European Ancestry Groups in the Early Twentieth‐Century United States
Authors: Boyd Robert L.
Published: November 2019

Emory Bogardus' 1926 social distance survey revealed, not surprisingly, that native‐born Americans tended to view Southern, Central, and Eastern (SCE) Europeans as far less desirable than Northern and Western (NW) Europeans for most social relationships. This well‐known finding has been attributed to both racial/ethnic prejudice and social class prejudice. The present study investigates the relative contributions of these two forms of prejudice to the total prejudice against SCE Europeans, testing the prediction that social distance attitudes toward European groups in Bogardus' pioneering survey were significantly influenced by group differences in socioeconomic status (SES), net of the NW‐SCE European distinction. The prediction is supported in analyses that consider survey respondents' uniquely intense desires for social distance from those SCE Europeans that were visible because of their relatively high SES, notably, Russian‐ancestry Jews. The study concludes that social class prejudice substantially affected divisions among European ancestry groups in early twentieth‐century America.
Network Analysis of ‘Urban Systems’: Potential, Challenges, and Pitfalls
Authors: Derudder Ben
Published: November 2019

This paper critically reviews the urban systems literature adopting graph‐theoretical conceptions of 'network analysis'. A network‐analytical approach allows specifying and measuring how cities interact, the importance and roles of cities in these interactions, and some of the key characteristics of the urban system as a whole. Throughout the paper, the focus is on ‘world city network’ research. After an overview of how network analysis first entered this literature and subsequently developed into a vibrant research agenda, the paper clarifies the use of network analysis by comparing two different network approaches. This is then used to discuss the potential and challenges/pitfalls associated with the use of network analysis, respectively. It is argued that the combination of careful abstraction and the methodological opportunities offered by network analysis offers geographers a powerful methodological toolkit. At the same time, a permanent appraisal of the real versus the alleged potential of network analysis is needed.
Intertwined metal homeostasis, oxidative and biotic stress responses in the Arabidopsis frd3 mutant
Authors: Scheepers Maxime , Spielmann Julien , Boulanger Madeleine , Carnol Monique , Bosman Bernard , De Pauw Edwin , Goormaghtigh Erik , Motte Patrick , Hanikenne Marc
Published: November 2019

FRD3 (FERRIC REDUCTASE DEFECTIVE 3) plays a major role in iron (Fe) and zinc (Zn) homeostasis in Arabidopsis. It transports citrate, which enables metal distribution in the plant. An frd3 mutant is dwarf and chlorotic and displays a constitutive Fe‐deficiency response and strongly altered metal distribution in tissues. Here, we have examined the interaction between Fe and Zn homeostasis in an frd3 mutant exposed to varying Zn supply. Detailed phenotyping using transcriptomic, ionomic, histochemical and spectroscopic approaches revealed the full complexity of the frd3 mutant phenotype, which resulted from altered transition metal homeostasis, manganese toxicity, and oxidative and biotic stress responses. The cell wall played a key role in these processes, as a site for Fe and hydrogen peroxide accumulation, and displayed modified structure in the mutant. Finally, we showed that Zn excess interfered with these mechanisms and partially restored root growth of the mutant, without reverting the Fe‐deficiency response. In conclusion, the frd3 mutant molecular phenotype is more complex than previously described and illustrates how the response to metal imbalance depends on multiple signaling pathways.
Racialized Space: Children Map the Post‐Apartheid Landscape
Authors: Reed Amber R.
Published: November 2019

Can children's maps shed light on legacies of structural inequality? This article presents a participatory mapping project with rural youth in South Africa's Eastern Cape. The analysis of the maps demonstrates that intergenerational legacies of racial oppression are critical to children's conceptions of space and place. Through a visual analysis of recurring features in the maps, I argue that rural South African children experience a racialized environment that informs their mapmaking and is a product of apartheid's linking of race, space, and territory. Contributing a case study within the larger field of participatory mapping, I offer a visual methodology to access worldviews of youth.
Enhancing respiratory sinus arrhythmia increases cardiac output in rats with left ventricular dysfunction
Authors: O'Callaghan Erin L. , Lataro Renata M. , Roloff Eva L. , Chauhan Ashok S. , Salgado Helio C. , Duncan Edward , Nogaret Alain , Paton Julian F. R.
Published: November 2019

Key points

Respiratory sinus arrhythmia is physiological pacing of the heart that disappears in cardiovascular disease and is associated with poor cardiac prognosis.

In heart failure, cardiac pacing has little, if any, variation in rate at rest.

We proposed that reinstatement of respiratory sinus arrhythmia would improve cardiac function in rats with heart failure.

Heart failure rats were paced daily for 2 weeks with either respiratory sinus arrhythmia or paced monotonically at a matched heart rate; cardiac function was measured using non‐invasive echocardiography.

Cardiac output and stroke volume were increased in rats paced with respiratory sinus arrhythmia compared to monotonic pacing, via improvement in systolic function that persisted beyond the pacing treatment period.

We propose that respiratory sinus arrhythmia pacing reverse‐remodels the heart in heart failure and is worth considering as a new form of cardiac pacemaking.

Natural pacing of the heart results in heart rate variability, an indicator of good health and cardiac function. A contributor to heart rate variability is respiratory sinus arrhythmia or RSA – an intrinsic respiratory modulated pacing of heart rate. The loss of RSA is associated with poor cardiac prognosis and sudden cardiac death. We tested if reinstatement of respiratory‐modulated heart rate (RMH) would improve cardiac performance in heart failure. Heart failure was induced in Wistar rats by ligation of the left anterior descending coronary artery. Rats were unpaced, monotonically paced and RMH paced; the latter had the same average heart rate as the monotonically paced animals. Cardiac function was assessed non‐invasively using echocardiography before and after 2 weeks of daily pacing at a time when pacing was turned off. RMH increased cardiac output by 20 ± 8% compared to monotonic pacing (−3 ± 5%; P < 0.05). This improvement in cardiac output was associated with an increase in stroke volume compared to monotonic pacing (P = 0.03) and improvement in circumferential strain (P = 0.02). Improvements in ejection fraction (P = 0.08) and surrogate measures of left ventricle compliance did not reach significance. Increases in contractility (P < 0.05) and coronary blood flow (P < 0.05) were seen in vitro during variable pacing to mimic RMH. Thus, in rats with left ventricular dysfunction, chronic RMH pacing improved cardiac function through improvements in systolic function. As these improvements were made with pacing switched off, we propose the novel idea that RMH pacing causes reverse‐remodelling.
2D bismuth telluride analyzed by XPS
Authors: Shallenberger Jeffrey R. , Smyth Christopher M. , Addou Rafik , Wallace Robert M.
Published: November 2019

Bismuth telluride (Bi2Te3) was analyzed using x-ray photoelectron spectroscopy. A freshly exfoliated, oxygen-free flake was analyzed. Spectral regions for O 1s, Te 3d, C 1s, Bi 4f, Bi 5d, and Te 4d were acquired. Bulk quantitative analyses by x-ray fluorescence, inductively coupled plasma-mass spectrometry, and x-ray diffraction indicated that the material was stoichiometric, contained low concentrations of impurities, and was phase pure, respectively.
Fabrication of Mg2Sn(111) film by molecular beam epitaxy
Authors: Aizawa Takashi , Ohkubo Isao , Lima Mariana S. L. , Sakurai Takeaki , Mori Takao
Published: November 2019

Magnesium stannide (Mg2Sn) is a small bandgap semiconductor of interest as a promising thermoelectric or optoelectronic material. Thin films of Mg2Sn were epitaxially grown on sapphire (0001) surfaces using molecular beam epitaxy. The epitaxial relationship is (111)Mg2Sn∥(0001)Al2O3 and [112¯]Mg2Sn∥[101¯0]Al2O3, with a small amount of stacking faults. A relatively high growth rate of 0.21–0.27 nm/s was attainable.
Cognitive hierarchy of acoustic power spectrum features for simulated biosonar target echoes in the bottlenose dolphin (Tursiops truncatus)
Authors: Accomando Alyssa W. , Mulsow Jason , Houser Dorian S. , Finneran James J.
Published: November 2019

Previous work with bottlenose dolphins [Dubrovsky et al., “Mechanisms of signal discrimination and identification in the auditory system of Tursiops truncatus,” in Marine Mammal Sensory Systems, edited by Thomas et al. (Plenum, New York, 1992), pp. 235–240] suggested that the perception of coarse envelopes of echo power spectra (“macrostructure”) is hierarchically dominant to finer-scale spectral features (“microstructure”). In the present study, two dolphins passively listened to and discriminated between two standard click doublets having different micro- and macrostructure. The dolphins were provided food reinforcement for remaining on an underwater station after the “negative” stimulus (two clicks with 100-μs separation) and for touching a paddle after the “positive” stimulus (two clicks with 150-μs separation). The dolphins were then presented with probe stimuli that were hybrids of the two standard stimuli. Each probe had a macrostructure identical to the positive or negative stimulus but the microstructure of the alternate standard. Preliminary results show the dolphins responding to probes in a manner consistent with macrostructure supremacy. This is in line with previous work suggesting that the macrostructure is hierarchically dominant over microstructure. [Work supported by the Office of Naval Research.]
Underwater glider localization using broadband source transmissions in the Canada Basin
Authors: Van Uffelen Lora J. , Webster Sarah E. , Dzieciuch Matthew , Worcester Peter F.
Published: November 2019

Two Seaglider autonomous underwater vehicles were deployed as mobile receiving platforms in a 2016–2017 tomography experiment in the Canada Basin. The introduction of gliders into a tomography experiment has the advantage of adding acoustic data receptions at many depths and ranges relative to moored acoustic sources. The challenge in interpreting these data is the lack of statistics at any given location and the uncertainty in the glider position during a dive, the latter resulting in a fundamental ambiguity between the position and sound speed. The acoustic arrival matching localization technique, performed in post-processing, has been employed to position the instruments while underwater using transmissions from moored acoustic sources. This technique capitalizes on the broadband nature of the tomography sources and estimates latitude and longitude while relying upon the vehicle’s pressure sensor for depth. Acoustic ranging was also performed onboard the gliders during the deployment, and estimated ranges from the moored sources were transmitted via Iridium satellite link every few hours when the glider surfaced. Positions resulting from acoustic arrival matching localization will be compared with results based on semi-real time acoustic ranging. Results will be discussed in the context of reviewing the state of the art in underwater glider localization.
Azimuthal, spatial, and temporal variability of acoustic intensity in cross-shelf direction during the yearlong shallow water Canada Basin Acoustic Experiment 2016–2017
Authors: Badiey Mohsen , Wan Lin , Pecknold Sean , Turgut Altan
Published: November 2019

A yearlong study of spatial, temporal, and azimuthal variability of sound propagation with simultaneously measured oceanography on Chukchi shelf is reported. In a shallow water region, two acoustic sources were deployed for studying the “along” and “cross-shelf” propagation. The “along-shelf” study is presented separately [J. Ascout. Sci. Am. 145 (2019)]. Here, we focus on the “cross-shelf” signal propagation in two frequencies (0.7–1.1 and 1.5–4 kHz) transmitted from a single sound source placed near the sound channel axis in 320 m water depth. Three “cross-shelf” acoustic tracks connected the source and three receiver arrays placed along 50 m isobath. The angle between east most and west most tracks was around 106 deg. Another array at 250 m isobath was deployed along the middle track. Sound emitted from the common source shows different behavior along each track. Concurrently, detailed water column salinity and temperature were measured by environmental arrays in both “along” and “cross-shelf” directions. Sea surface ice was measured by an upward looking sonar for several months. Seasonal injection of different water masses in this region and variations of sea surface conditions (full-ice, transition, and free-surface) are examined using the acoustical oceanographic data. This paper quantifies analysis using correlation between acoustics and oceanographic signals. [Work supported by ONR 322OA.]
Lipid-functionalized porous oxide nanoparticles for acoustic imaging and site-directed therapy
Authors: Goodwin Andrew P.
Published: November 2019

While most US contrast agents are fluid-filled micro- or nanoparticles, their stability of fluid-filled particles is limited by inherent Laplace pressure and equilibrium with the surroundings. Here, I will present our work designing silica nanoparticles of ∼100 nm with specifically tailored surfaces that can nucleate the formation of ultrasound-responsive microbubbles under reduced acoustic pressures. I will discuss the underlying materials science behind their activity, the effects of chemical functionalization on acoustic contrast (with the potential for stimulus-responsiveness), and applications in imaging and directed mechanical cell killing.
Making sonic boom measurements during adverse weather: Summarizing BYU’s participation in QSF18
Authors: Gee Kent L. , Novakovich Daniel J. , Rasband Reese D. , Leete Kevin M. , Loubeau Alexandra
Published: November 2019

One challenge with outdoor sonic boom measurements is making high-fidelity recordings under adverse weather conditions. This paper describes the deployment of a “weather-robust” measurement system as part of Brigham Young University’s (BYU) participation in the NASA Quiet Supersonic Flights 2018 (QSF18) test in Galveston, TX. BYU made measurements at four different stations across the city representing potentially different ambient environments: Scholes airport, a cemetery, a city park near a busy street, and the U.S. post office. At each station, multiple measurements were made using different data acquisition hardware and microphone types and configurations. These recordings, made within a few meters of each other, allowed for the comparison of different measurement approaches in terms of practicality, instrumentation noise floor, measurement bandwidth, wind noise, etc. The test itself and data analysis demonstrated the viability of the weather-robust measurement system, under real-world adverse weather conditions. They also yielded some lessons learned and recommended paths forward for future sonic boom measurements. [Work supported by NASA Langley Research Center through the National Institute of Aerospace.]
NASA supersonic testing: Streets, suburbs, and sonic booms
Authors: Kamlet Matt
Published: November 2019

NASA’s Quiet Supersonic Flights 2018 campaign in Galveston, TX, or QSF18 for short, marked a major milestone in the agency’s efforts to demonstrate quiet supersonicflight. The flights, which took place from 5 to 15 November 2018, marked NASA’s first supersonic flight research series to feature active participation and feedback from a large community unaccustomed to quiet supersonic overflights. The data obtained fromQSF18 are directly preparing NASA for the Low-Boom Flight Demonstration mission, in which NASA’s X-59 Quiet SuperSonic Technology X-plane, or QueSST, will fly overcommunities around the country to demonstrate the ability to reduce the loud, disruptive sonic boom typically associated with supersonic flight, to a quiet thump. NASA’s efforts to communicate with the community played a critical role in the successor QSF18, just as it will play a critical role in X-59’s Low-Boom Flight Demonstration mission. The process to successful communications, based on experience and lessons learned from previous supersonic flight research, is an effort that spans multiple fronts, including high public awareness, extensive communication based on each region’s unique features, character, and resources, local government partnership, media coordination, educational resources, direct public communication and accommodation,and as much coordination as possible through local and regional emergency response organizations.
Employing digital pole-shifting filters to improve low-frequency response of sonic boom measurements
Authors: Rasband Reese D. , Gee Kent L. , Gabrielson Thomas B. , Loubeau Alexandra
Published: November 2019

High-fidelity measurement of sonic boom waveforms requires microphones and data acquisition hardware with flat frequency responses that extend well below 1 Hz. However, digital pole-shifting filters that account for the microphone and data acquisition system roll-offs of conventional hardware can be used in post-processing to extend the effective bandwidth. This approach is demonstrated for sonic boom recordings from the NASA Quiet Supersonic Flights 2018 (QSF18) measurement campaign. Recordings of several booms at multiple measurement sites using different data acquisition hardware and microphone combinations were used to understand the robustness of the processing technique. In particular, manufacturers report nominal hardware roll-off frequencies with which filters can be designed. However, the QSF18 data can be used to derive filters computationally using a mean-square error method. Results, including residual errors and other limitations, are discussed. The transferability of the technique is further described through application to a launch vehicle reentry sonic boom, which had markedly different characteristics than the QSF18 recordings. [Work supported by NASA Langley Research Center through the National Institute of Aerospace.]
Acoustic radiation force and torque on inhomogeneous scatterers in the Born approximation
Authors: Jerome Thomas S. , Hamilton Mark F.
Published: November 2019

If a scatterer and the surrounding medium have similar material properties and the dominant contribution to the acoustic radiation force is due to energy density gradients in the sound field, the Born approximation may be used to reduce calculation of the radiation force and torque on a scatterer of arbitrary shape to an integral over the volume of the scatterer. Comparison with full solutions based on wave function expansions demonstrates that the approximation is accurate for homogeneous spheres and prolate spheroids in a standing plane wave when the size of the scatterer is less than about one wavelength [Jerome et al., J. Acoust. Soc. Am. 145, 36 (2019)]. Here, the Born approximation is extended to inhomogeneous scatterers by allowing the compressibility and density to vary within a scatterer in a standing plane wave. Analytical expressions for both the force and torque are obtained for a finite cylinder with inhomogeneity that varies linearly along its axis. Effects of inhomogeneity are examined for both cylinders and prolate spheroids. Physical insight is provided by simplified analytical expressions for narrow axisymmetric scatterers, such as thin rods, that are much smaller than a wavelength. [TSJ was supported by the ARL:UT McKinney Fellowship in Acoustics.]
Aligning high-aspect ratio particles in user-specified orientations with ultrasound directed self-assembly
Authors: Prisbrey Milo , Raeymaekers Bart
Published: November 2019

We use ultrasound directed self-assembly (DSA) to create two-dimensional patterns of high aspect ratio particles with user-specified orientation. We theoretically derive a method to determine the operating parameters of any arrangement of ultrasound transducers, required to align high aspect ratio particles in any user-specified orientation. The method finds the ultrasound wave field that maximizes the curvature of the acoustic radiation potential orthogonal to the user-specified particle orientation and in user-specified locations. We simulate the theoretical solution resulting from this method and experimentally validate it using carbon microfibers in water, and we quantify the position and orientation error. The method enables controlling the location and orientation of high aspect ratio particles, including simultaneously orienting multiple high aspect ratio particles in different directions. This work finds application in the biomedical field and in using ultrasound DSA as a processing or manufacturing method for engineered materials.
Cell agglomeration using guided surface acoustic waves through a couplant layer
Authors: Mei Jiyang , Takemura Kenjiro , Friend James
Published: November 2019

Cell agglomeration has been useful and crucial for tissue engineering, cell culturing, and drug testing, such as for cancer drug development. However, most of the methods require specific and complex experimental setups and the resulting agglomerates are generally slow or of poor quality. We propose a microfluidic device using surface acoustic waves (SAWs), a contact-free means, in the application of cell engineering. It is composed of a piezoelectric substrate, 127.86 deg Y-rotated X-propagating lithium niobate, and a focused interdigital transducer to generate focused surface waves with a resonant frequency at 100 MHz. An aluminum guiding layer is deposited on top of the substrate to overcome the beam steering and lateral diffraction problems due to the anisotropy nature of the piezoelectric material, further trapping the wave to a small region of a few wavelengths. The SAWs generated travel into a thin layer of liquid and diffract at the Rayleigh angle, so that the acoustic radiation is coupled and propagates into the superstrate, which can be a bio-friendly container culturing cells. The localized acoustic streaming induced from the radiation carries and accumulates the cells to the center of the recirculation. Our data show that the agglomeration can form in less than 20 s, and the separation between the living yeast cell agglomeration islands can be as small as △x = 720 μm. This device is proven to be an effective, reliable, and easy-to-handle approach for cell manipulation, independent of the culturing container.
Acoustic localization using Green’s function retrieval methods and range migration processing
Authors: Denis Max , Collier Sandra L. , Noble John , Alberts W. C. Kirkpatrick , Ligon David , Sim Leng , James Deryck D.
Published: November 2019

In this work, Green’s function retrieval and frequency-wavenumber methods are employed to enhance array plane-wave beamforming maps for acoustic source localization and range estimation in an outdoor environment. The crosscorrelation and multidimensional deconvolution Green’s function retrieval methods are used to improve the signal-to-noise ratio of the beamforming maps. The Stolt’s frequency-wavenumber migration method is adapted to the plane-wave beamforming map to find the source positions, applying frequency-wavenumber migration image to the Stolt spatial transformation mapping. Open field microphone array measurements of active and passive sources are investigated. Of particular interests are the accuracy of the estimated source position, the effects of multiple sources, and the image contrast of the beamforming maps.
Imaging the shear and secondary compression wave: Ultrafast ultrasound in saturated foams reveals porous dispersion
Authors: Aichele Johannes , Giammarinaro Bruno , Reinwald Michael , LeMoign Goulven , Catheline Stefan
Published: November 2019

Wave propagation in porous materials is of relevance in many fields of acoustics such as geophysics, noise cancellation, and biomedical imaging. In contrast to classical elastic materials, poroelastic materials support three types of elastic waves and exhibit a distinctive dispersion in the presence of viscous fluids. In addition to the compression and shear wave, a secondary compression wave, often named Biot slow wave, exists. Both, the slow compression wave and the shear wave are highly attenuated. This poses crucial difficulties for experimental detection. We overcome this challenge by using high frame rate ultrasound imaging for wave tracking inside saturated, highly porous melamine foams. To our knowledge, we show the first experimental speed and attenuation measurements inside a soft porous materials. In particular, experimental detection of the slow compression wave is scarce, and no direct imaging inside a porous material has been reported. Both wavespeeds are governed by the weak frame of the foam and exhibit a strong dispersion due to the fluid viscosity. Our experiments have direct implications for medical imaging: Melamine foams exhibit a similar microstructure as lung tissue. Furthermore, other organs such as the liver can be modeled as a soft porous material.
Additive manufacturing and architected materials: New process developments and materials
Authors: Spadaccini Christopher
Published: November 2019

Material properties are governed by the chemical composition and spatial arrangement of constituent elements at multiple length-scales. This fundamentally limits material properties with respect to each other creating trade-offs when selecting materials for specific applications. For example, strength and density are inherently linked so that, in general, the more dense the material, the stronger it is in bulk form. We are combining advanced design method such as topology optimization, with advanced additive micro- and nanomanufacturing techniques to create new material systems with previously unachievable property combinations – mechanical metamaterials. The performance of these materials is fundamentally controlled by geometry at multiple length-scales rather than chemical composition alone. We have demonstrated designer properties of these mechanical metamaterials in polymers, metals, ceramics and combinations thereof. Properties include ultra-stiff lightweight materials, negative stiffness, and negative thermal expansion to name a few, as well as functional properties such electrical, optical, acoustic, and chemical responses. We have primarily utilized our custom developed additive micro-manufacturing techniques to create these structures and materials. These include projection microstereolithography, direct ink writing, electrophoretic deposition, volumetric AM via tomographic reconstruction, parallel two-photon polymerization, and diode-based additive manufacturing of metals.
Continuous scan beamforming with CLEAN-SC for mapping of highly varying amplitude acoustic sources with significantly restricted sensor budgets
Authors: Lee Abe H. , Shah Parthiv , White Andrew
Published: November 2019

Continuous scan beamforming (CSBF) is a novel approach that employs virtual sensors to improve array performance without increasing the physical number of sensors. Previous CSBF demonstrations (at the Spring 2019 ASA meeting in Louisville, KY) showed the capability to perform high resolution mapping of acoustic sources and identify almost an 18 dB difference in source level, which was not possible using conventional beamforming with an equal sensor budget. The current work investigated the capability of CSBF combined with CLEAN-SC for conducting source localization with significantly reduced sensor budgets (on the order of ten sensors), in which conventional beamforming is practically impossible to obtain appreciable results. Results of a four-speaker noise test showed that CSBF can perform accurate identification of the locations and levels of the sources with such restricted sensor counts, and can provide an accurate input to CLEAN-SC for further enhancement of the source map.
Application of ray-based blind deconvolution to long-range acoustic communications
Authors: Kim Donghyeon , Park Heejin , Kim Jea Soo , Park Joung-Soo
Published: November 2019

For unknown source waveforms, the channel impulse response (CIR) can be estimated by ray-based blind deconvolution (RBD). In previous papers, RBD was successfully demonstrated using the simulation and data in a shallow water environment. In this study, we investigate the applicability of RBD for a long range (e.g., 30 km, 60 km, and 90 km) in about 1000 m deep water, using experimental data recently conducted in the east of Pohang, South Korea, in October 2018. The goal of BLAC18 was to obtain the underwater communication data in deep water. Simulation and data results are presented to demonstrate CIR estimation of a communication signal (2.2–2.9 kHz) using a 16-element, 42-m long vertical array in approximately 1000 m deep water. The results show that the CIR estimated from RBD is comparable to that of matched-filter result. Additional communication performance comparison will be also presented.
Low complexity energy efficient orthogonal frequency division multiplexing communication system over underwater acoustic channel by partial transmit sequence peak to average power ratio reduction
Authors: Raza Waleed , Ma Xuefei , Wang Tingting , Bilal Muhammad
Published: November 2019

We discourse the power consumption for underwater acoustic transceivers in this study. We have proposed a less computational complex underwater acoustic OFDM communication system. Underwater acoustic transceivers consume more power than that Radio frequency transceivers. The methods which are being utilized in Radio frequency cannot directly be applied to underwater acoustic system. Therefore, it needs to re-investigated and the new techniques should be introduced to achieve reliable and energy efficient acoustic data transmission. It also relies upon condition of acoustic channel and transmission distances. There is long-term battery-operated deployment of underwater acoustic modems in some applications. To maintain sustainable network operations an energy efficient OFDM system is required. In this paper, we have used partial transmit sequence peak to average power ratio reduction technique to design a novel energy efficient OFDM system for underwater acoustic channel with less complexity. This framework will be remarkably helpful in future for long term battery deployed applications of underwater acoustic transceivers. The results are expected to provide the enhanced performance of PAPR reduction with better sustainability. It has less complexity and better energy efficiency for underwater acoustic sensor/sensing networks.
The problem with E90
Authors: Taylor Corey , Herreman Kevin
Published: November 2019

Wall constructions are typically evaluated at an accredited acoustical laboratory for sound transmission loss per the ASTM E90 standard and the STC determined per the ASTM E413 standard. In North America, there are several accredited acoustic laboratories where walls can be evaluated. Accredited acoustic laboratories are required by the ASTM E90 standard to demonstrate that their facility is in compliance with the standard by performing transmission loss testing utilizing a reference specimen outlined in the ASTM E1289 standard. This standard prescribes a series of reference assemblies based on sheet metal panels in a metal frame, all with STC values less than 30, to be used in demonstrating compliance. A recent study conducted at the Owens Corning Acoustic Research Center, an accredited acoustical laboratory, provided enough data to perform a gauge study on the E90 test. The results of that study will be presented in this paper.