bluuebunny/crossref_metadata_2025 huggingface dataset:
Periodontitis and arterial stiffness: a systematic review and meta‐analysis
Authors: Schmitt Audrey , Carra Maria Clotilde , Boutouyrie Pierre , Bouchard Philippe
Published: October 2015

Introduction and Aims

Patients with periodontitis have a higher risk of cardiovascular diseases, although a causal relationship between these conditions remains unclear. Arterial stiffness is considered a marker of arteriosclerosis and a risk factor for cardiovascular diseases. A systematic review of the literature on clinical studies using pulse wave velocity (PWV) to assess arterial stiffness in patients with periodontitis was carried out to answer the following questions: (i) Do patients with periodontitis have impaired arterial stiffness compared to non‐periodontal diseased subjects? (ii) Is periodontal treatment effective as a means to improve arterial stiffness in patients with periodontitis?

Literature Review

Literature search was done on different databases up to September 2014. All clinical studies (excluding case reports) using PWV in patients with periodontitis were retrieved for a full‐text evaluation. A total of 10 studies were included. Patients with periodontitis have increased arterial stiffness compared to controls (PWV mean difference 0.85 m/s; 95% confidence interval: 0.53–1.16; p<0.00001). The only two interventional studies showed contradictory results on the effects of periodontal treatment on PWV.

Conclusion

Patients with periodontitis appear to have higher values of PWV compared to controls. The effect of periodontal treatment on arterial stiffness remains unclear.
Commentary: An exemplar of progress in understanding complex disorders – reflections on what we have learned about eating disorders (Culbert et al., 2015)
Authors: Smith Gregory T. , Davis Heather A.
Published: October 2015

A number of recent advances in eating disorders research have helped clarify the nature of risk for the development of such disorders. Culbert et al. () provide an empirical and thoughtful review of these recent advances. The authors identified empirically established risk factors in each of several categories of risk for eating disorders: genetic influences, neurotransmitter activity, hormones, personality, and sociocultural influences. We highlight three implications of their review. First, the review can serve as an important asset to eating disorder researchers, both substantively, by providing a comprehensive account of empirically supported risk processes; and methodologically, by highlighting good standards of evidence for acceptance of a candidate risk factor. Second, eating disorder risk is increased by both transdiagnostic and eating disorder‐specific factors; there is a need to understand how these types of factors transact with each other. Third and most important, we highlight the importance of Culbert et al.'s advocacy for the development of theoretical models, and empirical tests of those models that specify transactions among different types of risk factors, such as those based on genetic, neurobiological, personality, and social processes.
Pharmacogenomics and Implications for Nursing Practice
Authors: Cheek Dennis J. , Bashore Lisa , Brazeau Dan Alan
Published: October 2015

Purpose

This article aims to introduce the nurse to pharmacogenomics and its implications for clinical practice with regard to drug therapy.

Organizing Constructs

Pharmacogenomics is discussed with regard to the basic tenets, relationships to common health conditions, education and practice resources, and implications for nursing practice.

Methods

Peer‐reviewed literature, websites, and expert professional guidelines were reviewed with relation to pharmacogenomics and nursing practice.

Findings

The genetic–genomic literature has grown significantly since the completion of the Human Genome Project in 2003. This information is now being translated into practice with regard to the patient's genetic profile and the impact on drug therapy, which is pharmacogenomics.

Conclusions

The utilization of the patient genetic–genomic profile is beginning to have an impact on patient drug therapy in clinical practice.

Clinical Relevance

Nurses are in the position to make sure, with the increased translation of pharmacogenomics into clinical practice, that adverse drug reactions are avoided and doses are optimized.
Regulation of Th1/Th2 balance through OX40/OX40L signalling by glycyrrhizic acid in a murine model of asthma
Authors: Wu Qiaozhen , Tang Ying , Hu Xiaoyun , Wang Qin , Lei Wei , Zhou Linfu , Huang Jianan
Published: October 2015

Background and objective

Glycyrrhizic acid (GA) has been reported to have attenuating airway inflammation effects in asthma mouse model. However, the potential molecular mechanisms by which GA exerts anti‐inflammatory effects on ovalbumin (OVA)‐induced allergic asthma have not been well elaborated.

Methods

The effect of GA on OVA‐sensitized and challenged mice was investigated. The effect of GA on anti‐OX40 mAb stimulated splenocytes from asthma mice model was also examined.

Results

In OVA‐induced asthmatic mice, GA treatment prevented the decrease of T helper1 cytokine (interferon (IFN)‐γ) and the increase of T helper2 cytokines (interleukin (IL)‐4, IL‐5, IL‐13) in bronchoalveolar lavage fluid (BALF), reduced serum immunoglobulin (Ig)E and OVA‐specific IgE levels, prohibited the protein and mRNA expression of OX40 and OX40 Ligand (OX40L) in lung tissues, and the expression of OX40 in CD4+ T cells and OX40L in CD11b+ monocytes and CD19+ B cells in spleens in a dose‐dependent manner compared with the vehicle treatment (all P < 0.05). Moreover, OVA significantly increased the activation of p38 mitogen‐activated protein kinase (MAPK) in lung tissues, whereas GA and anti‐OX40L mAb markedly reduced phosphorylation of p38 MAPK. In addition, GA could inhibit the T cell proliferation and modulate the balance of Th1/Th2 in anti‐OX40 mAb stimulated CD4+ T cells from asthmatic spleens (all P < 0.05).

Conclusions

GA may exert a therapeutic effect on OVA‐induced experimental asthma partly by regulating the Th1/Th2 balance through suppressing OX40‐OX40L signalling and p38 MAPK activity. GA may be a promising treatment for asthma.
Understanding persons with psychological distress in primary health care
Authors: Arvidsdotter Tina , Marklund Bertil , Kylén Sven , Taft Charles , Ekman Inger
Published: October 2015

The purpose of this study was to gain more knowledge and a deeper understanding of experiences of persons living with psychological distress who seek help in primary care. Psychological distress is a state of emotional suffering associated with stressors and demands that are difficult to cope with in daily life. The lack of effective care for and difficulty in identifying psychological distress is frustrating for patients and health professionals alike. The aim was therefore to gain more knowledge about the experience of living with psychological distress. Twelve persons (nine women and three men) aged 23–51 years were interviewed. Analyses were based on a phenomenological hermeneutic method and indicated that psychological distress may be seen as an imbalance (incongruence) between the self and the ideal self, which slowly breaks down a person's self‐esteem. This imbalance was described in three dimensions: Struggling to cope with everyday life, Feeling inferior to others and Losing one's grip on life. It seems to be associated with a gradual depletion of existential capacities and lead to dissatisfaction, suffering, poor self‐esteem and lack of control. As psychological distress may be a forerunner to mental, physical and emotional exhaustion, there is a need to initiate preventive or early interventions to avoid mental, physical and emotional chaos in such patients. Patients' with psychological distress need to be involved in a person‐centred salutogenic dialogue with health professionals to become aware of and strengthen their own capacities to regain health and well‐being.
Beta spatial linear mixed model with variable dispersion using Monte Carlo maximum likelihood
Authors: Melo Oscar O. , Melo Carlos E. , Mateu Jorge
Published: October 2015

We propose a beta spatial linear mixed model with variable dispersion using Monte Carlo maximum likelihood. The proposed method is useful for those situations where the response variable is a rate or a proportion. An approach to the spatial generalized linear mixed models using the Box–Cox transformation in the precision model is presented. Thus, the parameter optimization process is developed for both the spatial mean model and the spatial variable dispersion model. All the parameters are estimated using Markov chain Monte Carlo maximum likelihood. Statistical inference over the parameters is performed using approximations obtained from the asymptotic normality of the maximum likelihood estimator. Diagnosis and prediction of a new observation are also developed. The method is illustrated with the analysis of one simulated case and two studies: clay and magnesium contents. In the clay study, 147 soil profile observations were taken from the research area of the Tropenbos Cameroon Programme, with explanatory variables: elevation in metres above sea level, agro‐ecological zone, reference soil group and land cover type. In the magnesium content, the soil samples were taken from 0‐ to 20‐cm‐depth layer at each of the 178 locations, and the response variable is related to the spatial locations, altitude and sub‐region.
Increased Adoption of Quality Improvement Interventions to Implement Evidence‐Based Practices for Pressure Ulcer Prevention in U.S. Academic Medical Centers
Authors: Padula William V. , Mishra Manish K. , Makic Mary Beth F. , Wald Heidi L. , Campbell Jonathan D. , Nair Kavita V. , Valuck Robert J.
Published: October 2015

Objective

In 2008, the U.S. Centers for Medicare and Medicaid Services enacted a nonpayment policy for stage III and IV hospital‐acquired pressure ulcers (HAPUs), which incentivized hospitals to improve prevention efforts. In response, hospitals looked for ways to support implementation of evidence‐based practices for HAPU prevention, such as adoption of quality improvement (QI) interventions. The objective of this study was to quantify adoption patterns of QI interventions for supporting evidence‐based practices for HAPU prevention.

Methods

This study surveyed wound care specialists working at hospitals within the University HealthSystem Consortium. A questionnaire was used to retrospectively describe QI adoption patterns according to 25 HAPU‐specific QI interventions into four domains: leadership, staff, information technology (IT), and performance and improvement. Respondents indicated QI interventions implemented between 2007 and 2012 to the nearest quarter and year. Descriptive statistics defined patterns of QI adoption. A t‐test and statistical process control chart established statistically significant increase in adoption following nonpayment policy enactment in October 2008. Increase are described in terms of scope (number of QI domains employed) and scale (number of QI interventions within domains).

Results

Fifty‐three of the 55 hospitals surveyed reported implementing QI interventions for HAPU prevention. Leadership interventions were most frequent, increasing in scope from 40% to 63% between 2008 and 2012; “annual programs to promote pressure ulcer prevention” showed the greatest increase in scale. Staff interventions increased in scope from 32% to 53%; “frequent consult driven huddles” showed the greatest increase in scale. IT interventions increased in scope from 31% to 55%. Performance and improvement interventions increased in scope from 18% to 40%, with “new skin care products . . .” increasing the most.

Linking Evidence to Action

Academic medical centers increased adoption of QI interventions following changes in nonpayment policy. These QI interventions supported adherence to implementation of pressure ulcer prevention protocols. Changes in payment policies for prevention are effective in QI efforts.
Further Investigation on Transonic Compressor Stall Margin Enhancement With Stall Precursor-Suppressed Casing Treatment
Authors: Sun Dakun , Nie Chaoqun , Liu Xiaohua , Lin Feng , Sun Xiaofeng
Published: October 2015

A kind of casing treatment, named as stall precursor-suppressed (SPS), has been developed recently, which was proved to be able to effectively improve stall margin (SM) without significant efficiency loss in low-speed axial flow compressors and a transonic compressor rotor. In this paper, the effectiveness of the SPS casing treatment is investigated in a single-stage transonic compressor. Based on an extended stall inception model, the quantitative evaluation of the SM enhancement by the SPS casing treatment is presented for the transonic compressor stage. The model predicts that a 2.5–6.8% of stall margin improvement (SMI), which is defined in terms of mass flow rate at stall inception, can be achieved at the design rotational speed. The experimental results show that the SPS casing treatment can achieve 3.5–9.3% of the SMI at 95% design rotational speed. Due to the fact that the distributions of the total pressure ratio along the spanwise direction are kept the same as those of the solid wall casing at the same mass flow rate, the SPS casing treatments with a small open area ratio and large backchamber enhance the SM without a recognizable efficiency loss and a migration of the pressure-rise characteristics. Furthermore, the mechanism of SMI with the SPS casing treatment is investigated in the experiments. In comparison with the solid wall casing, the emergence and the evolution of the stall inception waves are suppressed and the nonlinear development of the stall process is delayed with the SPS casing treatment.
Three-Dimensional Numerical Analysis of Solid Oxide Electrolysis Cells Steam Electrolysis Operation for Hydrogen Production
Authors: Kang Juhyun , Park Joonguen , Bae Joongmyeon
Published: October 2015

Hydrogen is a resource that provides energy and forms water only after reacting with oxygen. Among the many hydrogen generation systems, solid oxide electrolysis cells (SOECs) have attracted considerable attention as advanced water electrolysis systems because of their high energy conversion efficiency and low use of electrical energy. To find the relationship between operating conditions and the performance of SOECs, research has been conducted both experimentally, using actual SOECs, and numerically, using computational fluid dynamics (CFD). In this investigation, we developed a 3D simulation model to analyze the relationship between the operating conditions and the overall behavior of SOECs due to different contributions to the overpotential. Simulations were performed with various inlet gas compositions of cathode and anode, cathode thickness, and electrode porosity to identify the main parameters related to performance.
Atomic layer deposition of ultrathin Cu2O and subsequent reduction to Cu studied by in situ x-ray photoelectron spectroscopy
Authors: Dhakal Dileep , Assim Khaybar , Lang Heinrich , Bruener Philipp , Grehl Thomas , Georgi Colin , Waechtler Thomas , Ecke Ramona , Schulz Stefan E. , Gessner Thomas
Published: October 2015

The growth of ultrathin (<5 nm) Ru-doped Cu2O films deposited on SiO2 by atomic layer deposition (ALD) and Cu films by subsequent reduction of the Cu2O using HCO2H or CO is reported. Ru-doped Cu2O has been deposited by a mixture of 16: 99 mol. % of [(nBu3P)2Cu(acac)] as Cu precursor and 17: 1 mol. % of [Ru(η5-C7H11)(η5-C5H4SiMe3)] as Ru precursor. The catalytic amount of Ru precursor was to support low temperature reduction of Cu2O to metallic Cu by formic acid (HCO2H) on arbitrary substrate. In situ x-ray photoelectron spectroscopy investigations of the Cu2O ALD film indicated nearly 1 at. % of carbon contamination and a phosphorous contamination below the detection limit after sputter cleaning. Systematic investigations of the reduction of Ru-doped Cu2O to metallic Cu by HCO2H or CO as reducing agents are described. Following the ALD of 3.0 nm Cu2O, the ultrathin films are reduced between 100 and 160 °C. The use of HCO2H at 110 °C enabled the reduction of around 90% Cu2O. HCO2H is found to be very effective in the removal of oxygen from Ru-doped Cu2O films with 2.5–4.7 nm thickness. In contrast, CO was effective for the removal of oxygen from the Cu2O films only below 3.0 nm at 145 °C. Root mean square surface roughness of 0.4 ± 0.1 nm was observed from atomic force microscopy (AFM) investigations after the ALD of Cu2O, followed by the subsequent reduction of 3.0 nm Cu2O using either HCO2H at 110 °C or CO at 145 °C on SiO2. Furthermore, ex situ low energy ion scattering and AFM investigations confirmed that the Cu2O film after ALD and Cu films after subsequent reduction was continuous on the SiO2 substrate.
Analysis of cloaks for flexural waves
Authors: Climente Alfonso , Torrent Daniel , Sanchez-Dehesa Jose
Published: October 2015

We report a comprehensive analysis of the cloaks proposed for bending waves propagating in a thin metallic plate. The analysis uses a semi-analytical model which is able to reproduce the experimental data reported by Stenger and coworkers [see Phys. Rev. Lett., vol. 108, 014301 (2012)]. The model is based on the Kirkoff-Love equation of motion and employs the multilayer scattering algorithm to calculate the interaction of the propagating waves with the cloak. The boundary equations apply to the designed device give a complete description of the data without using simplified algorithms solved in a finite element framework. The performance of the cloak is characterized with the visibility factor, a parameter already employed in several acoustic cloaks. A discussion will be given of the performance of the cloak for flexural waves in comparison with acoustic cloaks. [Work supported by ONR.]
Subwavelength acoustic metamaterial with tunable acoustic absorption
Authors: Viard Nicolas , Gallardo Cali , Xu Jun , Fang Nicholas
Published: October 2015

We present numerical simulations and experimental measurements for ultrasonic transmission through a subwavelength metamaterial consisting of an array of hollow cylinders embedded in a soft elastic matrix. The mechanical properties of the matrix, the lattice constant, and the size of the cylinders are optimized in order to maximize sound absorption in the metamaterial while the cylinders are filled with air. The acoustic transmission is restored when the cylinders are filled with water. Our design expands the concept of metamaterial as it demonstrates the ability to tune the acoustic properties of a subwavelength material.
Rotating the directivity of sound radiation by acoustic meta-structures
Authors: Zhang Likun , Jiang Xue , Liang Bin , Zou Xin-ye , Cheng Jian-chun
Published: October 2015

Radiation directivity is an important measure of sound fields radiated from acoustic sources. Manipulation of the directivity plays a significant role in many situations ranging from audio and auditorium acoustics to medical ultrasound applications. An acoustic meta-structure is presented here to rotate the directivity of sound radiation from sources surrounded by the meta-structure with an anisotropic acoustic property. The meta-structure consists of an array of platelets, regularly arranged in several concentric rings. The platelets’ orientation is determined from transformation acoustics model. Numerical simulations of sound fields with the structure reveal that the angle of sound directivity rotated by the structure is independent of sound frequency and source location. The rotation is verified through experimental measurements with the meta-structure fabricated by thermoplastics materials via 3D printing. The rotation angle varies over a broad range through tuning geometry parameters of the meta-structure. The meta-structure with its extreme performance can hence provide various applications in the effective control of radiation directivity in acoustic engineering.
Interdisciplinary tutorial on sonic booms: A “super” sonic saga
Authors: Sparrow Victor W.
Published: October 2015

This tutorial will provide an introduction to sonic booms, including background, current status of research, and future prospects. Supersonic aircraft generate sonic booms, so the physics of shock propagation through the atmosphere is involved. But those shocks are ultimately heard on the ground indoors and outdoors, both by people and wildlife. Hence, physical acoustics, psychological and physiological acoustics, animal bioacoustics, structural acoustics, vibration, and noise are all involved. Aircraft manufacturers have plans to build new civilian supersonic passenger aircraft, and these new aircraft intend to have sonic booms that are much quieter than those produced by either military aircraft or the now-retired Concorde supersonic airliner. Thus, an additional objective of this tutorial is to provide a quick-start technical basis for ASA members to understand the basics of sonic booms, enabling them to communicate effectively about sonic booms. If the aircraft manufacturers meet their stated goals, millions of people around the world will potentially begin hearing quiet sonic booms in the future. The material is highly interdisciplinary and should be useful both to the curious and to specialists across almost all of the Acoustical Society of America's technical areas. [The opinions, findings, conclusions, and recommendations stated here are those of the author and do not necessarily reflect the views of sponsors of the ASCENT Center of Excellence including the Federal Aviation Administration.]

In conjunction with the Tutorial Lecture on sonic booms on Monday evening, Gulfstream Aerospace Corporation will be bringing their sonic boom simulator to the Jacksonville, FL meeting. The Supersonic Acoustic Signature Simulator II is a specially equipped mobile audio booth designed to accurately reproduce the noise an observer on the ground would hear if a supersonic aircraft flew by. More specifically, the visitor at the ASA meeting will experience a back-to-back comparison of two radically different synthesized sonic booms. The first sonic boom signature will represent the “traditional” N-wave signature produced by the Concorde. The second sonic boom will represent a shaped signature that is representative of a low-boom aircraft. The intent of this demonstration is to provide the visitor with an opportunity to experience a fully immersive simulation that contains a sophisticated auralization of stimuli that contribute to subjective response caused by a sonic boom.

The simulator will only be available on Monday, November 2 (12:00 noon to 7:00 p.m.), and Tuesday, November 3 (9:00 a.m. to 6:00 p.m.), and will be located at Jacksonville Landing, just steps away from the Hyatt Regency. Walking directions will be provided on site via convenient signs. Please come and take advantage of this special opportunity to hear the Supersonic Acoustic Signature Simulator II.
Change in Canada’s national building code—Overview of new requirements and of projects supporting the change
Authors: Hoeller Christoph , Zeitler Berndt , Mahn Jeffrey
Published: October 2015

The proposed 2015 edition of the National Building Code of Canada sees a major change in sound insulation requirements. Instead of prescribing requirements for the separating assembly only (in terms of STC values), the Code now sets requirements for the sound insulation performance of the complete system (in terms of Apparent Sound Transmission Class (ASTC) values), including flanking sound transmission. The National Research Council Canada is actively supporting the change in the Code by conducting various projects with industry associations from different construction sectors, in order to provide tools, guidance, and the necessary data for compliance. This presentation provides an overview of the new requirements and of the different paths to compliance. Furthermore, various projects conducted at the National Research Council Canada to support the Code change are presented, including tools and guidance to help practitioners. Detailed descriptions of two of the projects are given in two complementary presentations.
A comparative study of Pinna motions in horseshoe bats and old world leaf-nosed bats
Authors: Yin Xiaoyan , Nguyen Phat , Tucker Thomas J. , Müller Rolf
Published: October 2015

Horseshoe bats (Rhinolophidae) and Old World leaf-nosed bats (Hipposideridae) are two closely related bat families that stand out for the dynamics of their ears during biosonar behaviors. In bats belonging to both families, the outer ears (pinnae) can undergo substantial, fast, and non-rigid shape changes while the animals emit their biosonar pulse trains. So far, characterization of these motions has been limited to either very general measures (e.g., of overall ear rotation) and/or limited data sets covering only a single species. Here, we have combined high-speed stereo vision with digital animation techniques to reconstruct and compare the motions of the pinnae and the head in one rhinolophid (Rhinolophus ferrumequinum) and two hipposiderid species (Hipposideros armiger and Hipposideros pratti). In parallel, we have also recorded the pulses and echoes received by the animals. We found that the pinna motions in both families frequently overlap in time with the arrival of the echoes, so they could have a functional relevance for echo reception. The pinna motions were found to follow similar patterns in all three species and could be decomposed into three main components. Beyond these fundamental similarities, there were also pronounced quantitative differences between the motions seen in the two families.
Single-sensor density estimation of highly broadband marine mammal calls
Authors: Küsel Elizabeth T. , Siderius Martin , Mellinger David K.
Published: October 2015

Odontocete echolocation clicks have been used as a preferred cue for density estimation studies from single-sensor data sets. Such sounds are broadband in nature, with 10-dB bandwidths of 20 to 40 kHz or more. Estimating their detection probability is one of the main requirements of density estimation studies. For single-sensor data, detection probability is estimated using the sonar equation to simulate received signal-to-noise ratio of thousands of click realizations. A major problem with such an approach is that the passive sonar equation is a continuous-wave (CW) analysis tool (single-frequencies). Using CW analysis with a click’s center frequency while disregarding its bandwidth has been shown to introduce bias to detection probabilities and hence to population estimates. In this study, the methodology used to estimate detection probabilities is re-evaluated, and the bias in sonar equation density estimates is quantified by using a synthetic data set. A new approach based on the calculation of arrivals and subsequent convolution with a click source function is also presented. Application of the new approach to the synthetic data set showed accurate results. Further complexities of density estimation studies are illustrated with a data set containing highly broadband false killer whale (Pseudorca crassidens) clicks. [Work supported by ONR.]
Ambient-noise inversion in ocean geoacoustics and seismic-hazard assessment
Authors: Quijano Jorge E. , Molnar Sheri , Dosso Stan E.
Published: October 2015

This paper presents methodologies and results for the estimation of seabed and soil-column geophysical properties based on Bayesian inversion of ambient ocean-acoustic and seismic noise, respectively. In both marine and terrestrial applications, beamforming is applied to array-based measurements to select the direction of arrival of ambient-noise energy. For the ocean-acoustic application, wave-generated surface noise is recorded at a vertical line array and beamformed to extract up- and down-going energy fluxes from which bottom loss vs. angle can be computed and inverted for geoacoustic profiles. Results from ambient-noise measurements at the Malta Plateau are presented and compared to controlled-source inversions and core measurements. The terrestrial seismic application is aimed at earthquake-hazard site assessment, which requires knowledge of the shear-wave velocity profile over the upper tens of meters of the soil column. In this case, urban seismic noise is recorded on a geophone array and beamformed to determine the dominant direction of arrival over short time windows, from which the Rayleigh-wave dispersion curve can be estimated and inverted. Two sites with differing geology are considered, and results are compared to invasive (borehole) measurements.
Acoustic particle velocity sensor: Application to infrasonic detection
Authors: Solomon Latasha
Published: October 2015

Infrasonics is the study of low-frequency acoustics that is below the normal limit of human hearing. Infrasound has the ability to propagate extremely long ranges and is often utilized to monitor naturally occurring phenomena and explosives. Acoustic particle velocity sensors have shown promise in detection and localization of transient signals in the audio range such as small arms fire, mortars, and rocket propelled grenades. Ideally, this sensor can be used to detect various targets spanning a broad range of frequencies to include that of infrasound. The primary objective of this research is to characterize the acoustic vector sensor’s localization performance for infrasonic sources given varying atmospheric conditions using algorithms developed at the Army Research Laboratory (ARL).
Contributions to the intensity field in shallow water waveguides
Authors: Moss Geoffrey R. , Deal Thomas , Smith Kevin B.
Published: October 2015

In a typical waveguide propagation, the acoustic intensity field is made up from contributions by a direct wave, bottom and surface reflected waves, and a number of interface waves. In shallow water environments, the laterally traveling headwave, generated by interaction with a faster propagating bottom layer, may become important. Several numerical techniques are used to calculate intensity fields in shallow water environments including normal modes, parabolic equation, and finite element methodologies. Bottom interactions are modeled with equivalent fluid properties, and the relative influence of the laterally traveling head wave is examined for several bathymetries of interest. Each codes' solution and merits are compared when calculating both propagating (active) and stationary (reactive) low frequency acoustic intensities.
Measurement of high level impulse noise for the use with different damage risk criteria
Authors: Buck Karl , Hamery Pascal , De Mezzo Sebastien , Koenigstein Florian
Published: October 2015

On the battlefield, but also during training, a soldier is continuously exposed to various types of noise (impulse and continuous). This exposure is not only noise generated by his own weapon but also by weapons or vehicles of close by troops. The exposure levels are between 160 dB peak for small arms and 190 dB peak at the soldier's ear for some anti tank weapons, with A-durations from 0.3 ms (small caliber) to 4 ms for large caliber weapons (e.g., Howitzers). In order to protect the soldier to noise exposures which may induce hearing loss, damage risk criteria (DRC) are implemented, and proposed for the prediction of the potential risk due to a certain noise exposure. Depending on the type of criteria (Pressure-Time-History or A-weighted Energy based), the recording and evaluation of different physical signal parameters has to be done in accordance to the used DRC. The paper will present the problems which may arise when recording impulse (weapon) noise with very high peak pressure levels and discuss measurement techniques compatible with the used DRCs. The paper will also discuss problems which may arise during the use and development of portable noise dose meters for the use in the military environment.
Nonlinearity in the auditory hazard assessment algorithm for humans
Authors: Fedele Paul D. , Kalb Joel T.
Published: October 2015

The Auditory Hazard Assessment Algorithm for Humans (AHAAH) is a software application that evaluates hearing damage risk associated with impulsive noise (http://www.arl.army.mil/ahaah). AHAAH applies pressure response dynamics across the external, middle, and inner ear, to bio-mechanically model the ear’s physical response to impulsive sound. Cumulative strain-induced fatigue in the cochlea’s organ of Corti determines the risk of auditory hazard. AHAAH includes nonlinear behavior observed in stapes displacement and associated with the annular ligament in the middle ear. AHAAH’s nonlinear behavior has been validated by Price (2007) based on human test results produced by Johnson (1966, 1993, and 1997). Presented analyses results show that the risk of hearing hazard cannot be predicted solely on the basis of waveform energy (A-weighted or not) or waveform peak pressure, because of the middle ear nonlinearity. The risk of hearing hazard does not necessarily behave monotonically with any summary waveform characterization. Although the AHAAH may seem complex, it analyzes response to the full time-dependence of the waveform to accurately analyze hearing damage risk through the nonlinear elements of the human middle ear.
Deriving long-distance coarticulation from local constraints
Authors: Flemming Edward
Published: October 2015

Coarticulatory effects can extend over two or more syllables. For example, we find in a study of English nonce words of the form [bV1C1əC2V2t] that F2 of V1 is shifted toward the F2 of V2. One approach to such long-distance coarticulatory effects posits direct interactions between the segments involved. For example, coproduction models attribute coarticulatory variation to temporal overlap between segments, so coarticulatory effects of V2 on V1 imply that a V2 gesture begins two syllables earlier, during V1. An alternative account posits that long-distance coarticulation results from iterative local coarticulation. That is, V1 can show coarticulatory effects of V2 because each intervening segment can partially assimilate to the next, resulting in a chain of coarticulatory effects between the two vowels. Since the iterative coarticulation analysis posits that long-distance coarticulation is mediated by intervening segments, it predicts that (i) coarticulatory variation at V1 due to V2 should be predictable from variation at the following segment, with no independent effect of later segments, and (ii) if intervening segments resist local coarticulation they should also attenuate non-local coarticulation across them. Neither prediction follows if distant segments can interact directly with each other. Both predictions are confirmed.
Resolving small events within a dense urban array
Authors: Riahi Nima , Gerstoft Peter
Published: October 2015

We use data from a large 5200 element geophone array that blanketed 70 km2 of the city of Long Beach (CA) to characterize very localized urban seismic and acoustic phenomena. Such small events are hard to detect and localize with conventional array processing techniques because they are only sensed by a tiny fraction of the array sensors. To circumvent this issue, we first identify significant entries in the large coherence matrix of the array (5200 × 5200 entries) and then use graph analysis to reveal spatially small and contiguous clusters of receivers with correlated signals. This procedure allows us to track local events over time and also characterize their frequency content. The analysis requires no prior medium information and can therefore be applied under conditions of relatively high scattering. We show how the technique exposes a helicopter traversing the array, several oil production facilities, and late night activity on a golf course.
Detection and localization of microcracking in polymer concrete using coda wave interferometry (CWI) at resonance
Authors: Mechri Charfeddine , Bentahar Mourad , Toumi Souad , Boubneider Fouad , El Guerjouma Rachid
Published: October 2015

Nonlinear resonance and Coda Wave Interferometry (CWI) proved their potential to detect the evolution of a structure, namely, in the case of damage. Nevertheless, these techniques do not allow localizing defects in a structure. CWI may allow this localization through heavy statistical algorithms. In this case, the main problem remains the real time monitoring on one hand. On the other hand, in the case of highly scattering media, the amplitude of the acoustic pulse may cause the Coda signal to be affected by conditioning/relaxation effects. Moreover, Coda signal is very sensitive to experimental conditions, namely, to temperature. In order to overcome these inconveniences, we propose a method based on a comparative study of Coda signal contents in rest state and under a weak (linear) vibration. In this communication, we report the results obtained on a polymer concrete specimen excited under different resonance modes and for different dispositions of the sample which defect is not isotropic on which we apply simultaneously through transmission experiments in order to monitor changes in the coda signal.
Does knowledge of probabilistic pronunciation patterns aid perception?
Authors: Kang Shinae , Cohen Clara , Fonyo Rozina
Published: October 2015

Words which are probable in their morphological paradigms tend to have lengthened affixes (Cohen, 2014; Kuperman et al., 2007). Here, we ask whether listeners use the pattern to aid perception. If so, paradigmatically probable words with lengthened affixes should be perceived more quickly than similarly lengthened improbable words. In two experiments (Experiment 1: phoneme monitoring; Experiment 2: lexical decision), we measured listeners’ reaction time (RT) to 50 English verbs with [-s] suffixes (e.g., looks, breaks). Each suffix was adjusted in duration to either a normalized proportion of stem duration, shortened by 25% of the normalized duration, or lengthened by 25%. In Experiment 2, paradigmatic probability did not affect RT, but short words had slower RTs than normalized or lengthened words, suggesting that generally reduced suffix duration impedes perception. In Experiment 1, RT decreased with increased probability for the long condition, but not for the normalized condition. This suggests that a match between suffix length and paradigmatic probability facilitates perception. However, RT also decreased in the short condition, suggesting that when the stimulus was most difficult to perceive, listeners drew on general probabilistic information to aid perception. Our results further indicate that the effect of paradigmatic probability on perception is task-dependent.
Random matrix theory enabled performance analysis and algorithms for underwater signal processing
Authors: Nadakuditi Raj R.
Published: October 2015

Random matrices arise naturally in many undersea signal processing applications such as sonar and underwater acoustic communications. For example, the matrix formed by stacking a noisy time series of observations collected at a sensor array alongside each other is a random matrix. Random matrix theory provides a mathematical framework for reasoning about and understanding the structure in such noisy matrix-valued signals in an analogous manner to how Fourier analysis provides us a mathematical framework for reasoning about and understanding the structure in noisy vector valued signals. We highlight some recent breakthroughs in random matrix theory that have allowed us to predict the fundamental performance limits of weak signal detection, estimation and classification and discuss some recent successes where the theory has led to the development of powerful new algorithms for better estimating weaker signals than previously thought possible.
The surprising sample covariance matrix: Unexpected characteristics and understanding them
Authors: Yellepeddi Atulya , Preisig James
Published: October 2015

The Sample Covariance Matrix (SCM) is important to many problems in acoustic signal processing in both time-domain and frequency-domain processing. However, some careful analysis suggests that the SCM contains a variety of surprises. For instance, not all elements of the SCM have the same error—the error of a particular element depends on the location of the element in the matrix and is different for SCMs of real-valued processes and complex-valued processes. Moreover, when the samples of the process used to compute the SCM are correlated, the sample covariance matrix behaves differently yet again. In particular, for frequency-domain sample covariance matrices, which are common in underwater acoustic communication and sonar signal processing, the SCM obtained using a tapped delay line is a better estimate of the covariance matrix than that obtained using independent samples—a most counterintuitive result. In this talk, we present a unified analysis technique using ergodic theory that predicts a variety of unexpected characteristics of the SCM, and explain the reasons behind some of them. Given the wide variety of algorithms that rely on the SCM, understanding this behavior is crucial to designing robust and accurate algorithms.
Sixty years studying wave propagation in random media at the Applied Physics Laboratory
Authors: Ewart Terry E. , Rouseff Daniel
Published: October 2015

Ocean acoustics has been a useful avenue for testing evolving theories for Wave Propagation in Random Media (WPRM). These theories generally assume that the index of refraction statistics are stable in space and time, an assumption proven reasonably true in the deep ocean for acoustic paths away from boundaries. In the present work, results from 60 years of theoretical and experimental WPRM research at the University of Washington's Applied Physics Laboratory (APL) are reviewed. The first experiment was performed in 1959 to test theories for amplitude fluctuations based on the Born approximation. The Rytov approximation (from Russian literature) for calculating the log-amplitude fluctuations was also evaluated. Conclusion: neither applied. Experiments in 1971 and 1977 measured acoustic fluctuation statistics for an 18 km acoustic path at sonar-relevant frequencies, 2–13 kHz. A 1985 experiment under Arctic ice used 2–16 kHz signals over a 6 km path. These experiments are discussed together with theoretical issues based on the Moment Equation method to provide one viewpoint on the history of ocean acoustic WPRM. The following translation of Voltaire is appropriate: “The ancients when reasoning about physics without the enlightenment of experiments are like blind men explaining the nature of colors to other blind men.”
Shallow water experiments and results
Authors: Lynch James , Duda Timothy F. , Newhall Arthur E. , Lin Ying T.
Published: October 2015

Shallow water acoustics has flourished over the past fifty years, but most especially over the last 25 years. After World War II, the Cold War between the USSR and the West focused the emphasis in ocean acoustics on deep, “blue water.” After the Cold War waned in 1990, the emphasis changed to “brown water” coastal acoustics studies. In this paper, we will look at the advances over the past half-century in shallow water acoustics, with emphasis on the experimental results from acoustics, oceanography, marine geology, and marine biology.
Acoustic levitation device for probing biological cells with high-frequency ultrasound
Authors: Patchett Brian D. , Sullivan Natalie C. , Doyle Timothy E.
Published: October 2015

High-frequency ultrasound has been shown to be sensitive to changes in the cell cytoskeletal makeup during a variety of biological processes. It can therefore be used to study cellular responses such as T-cell activation and cancer metastasis. To date, obtaining cytoskeletal properties with high-frequency ultrasound has required the use of monolayer cell cultures. Ultrasonic signals from these cultures can be problematic due to the interference of reflections from the culture-plate well. The cell structure is also often deformed from its native state due to adhesion to the culture plate. The objective of this study was to develop an acoustic levitation device that creates a monolayer of cells suspended in a fluid in order to simulate their environment in vivo. By using a 250 kHz transducer, standing waves were generated in a suspension of polyethylene microspheres (53–63μm diameter) in distilled H2O. Microspheres formed layers at the standing-wave nodes. Varying the shape of the transducer voltage waveform had a significant effect on layer thickness, with a square waveform creating thinner, more distinct layers than a sine waveform due to steeper pressure gradients at the nodes. Future work will entail creating a monolayer suspension of biological cells that can be probed with high-frequency ultrasound.
Seismic surveys and marine wildlife: Impacts, the lack thereof, and thoughts on managing both
Authors: Nowacek Douglas P.
Published: October 2015

Sufficient scientific data exist to conclude that seismic airguns used in geophysical exploration have a low probability of direct harm to most marine life, except at close range where physical injury is a real danger. Further, airguns in some conditions do not appear to disturb animals; however, in other conditions, they result in moderate to extreme behavioral responses and/or acoustic masking over large areas. Additionally, recent studies have reported the presence of seismic survey sound energy over ranges of ~4000 km. While the potential for effects have not even been investigated at such ranges, the presence of the signals must be taken into account when evaluating overall potential for impacts. Mitigation measures have historically focused on reducing immediate harm, but systematically measuring and understanding the full potential for impacts is an important aspect of any responsible development program. The European Union has recognized ocean noise as a pollutant and as an indicator of environmental quality under its Marine Strategy Framework Directive. Given this and the international and transboundary nature of noise from marine seismic surveys, their ubiquity, the presence of numerous other sources of ocean noise, and that incorporating acoustic disturbance into an understanding of population level consequences is progressing, a responsible path forward should focus on the creation of legally binding international commitments and standards for the management and minimization of noise.
Spectral characteristics and formant bandwidths of English vowels produced by American males with different speaking styles
Authors: Yang Byunggon
Published: October 2015

Speaking styles tend to have an influence on spectral characteristics of produced speech. There are not many studies on the spectral characteristics of speech because of complicated processing of too many spectral data. This study examined spectral characteristics and formant bandwidths of English vowels produced by nine American males with different speaking styles: clear or conversational styles; high- or low-pitched voices. PRAAT was used to collect pitch-corrected long-term averaged spectra and bandwidths of the first two formants of 11 vowels in the speaking styles. Results showed that the spectral characteristics of the vowels varied systematically according to the speaking styles. The clear speech showed higher spectral energy of the vowels than that of the conversational speech while the high-pitched voice did the same over the low-pitched voice. Second, there was no statistically significant difference between B1 and B2 in the speaking styles. B1 was generally lower than B2 reflecting the source spectrum and radiation effect. However, there was a statistically significant difference in B2 between the front and back vowel groups. The author concluded that spectral characteristics reflect speaking styles systematically while bandwidths measured at a few formant frequency points do not reveal style differences properly.