bluuebunny/crossref_metadata_2025 huggingface dataset:
New algorithm for valganciclovir dosing in pediatric solid organ transplant recipients
Authors: Åsberg A. , Bjerre A. , Neely M.
Published: October 2013

CMV infections are common after SOT. v‐GCV is increasingly used in children. The aim of this study was to evaluate presently used dosing algorithms. Data from 104 pediatric SOT recipients (kidney, liver, and heart) aged 0.3–16.9 yr and receiving v‐GCV once a day were used for model development and validation with the Pmetrics package for R. Monte Carlo simulations were performed to compare the probability of a GCV AUC 40–60 mg*h/L with the different algorithms across a range of ages, weights, and GFRs. GCV pharmacokinetics was well described by the non‐parametric model. Clearance was dependent on GFR and Cockcroft‐Gault estimates improved the model fit over Schwartz. Simulations showed that our new algorithm, where v‐GCV dose is: Weight [kg]*(0.07*GFR [mL/min]+k), where k = 5 for GFR ≤ 30 mL/min, k = 10 for GFR > 30 mL/min and weight > 30 kg and k = 15 for GFR > 30 mL/min and weight ≤ 30 kg, outperformed the other algorithms. Thirty‐three percent of all patients achieve an exposure above and 21% within the therapeutic window. We propose a simple algorithm for initial v‐GCV dosing that standardizes plasma drug exposure better than current algorithms. Subsequent TDM is strongly suggested to achieve individual drug levels within the therapeutic window.
Facilitation allows plant coexistence in Cuban serpentine soils
Authors: Oviedo R. , Faife‐Cabrera M. , Noa‐Monzón A. , Arroyo J. , Valiente‐Banuet A. , Verdú M.
Published: October 2013

Serpentine soils represent stressful habitats where plants have to cope with heavy metals, moisture limitation and low nutrient availability. We propose that facilitation is an important mechanism structuring plant communities under such stressful conditions. Facilitation has been shown to generate the spatial association of species, forming discrete vegetation patches of phylogenetically distant species. We measured these spatial and phylogenetic signatures left by facilitation in a serpentine plant community of central Cuba. Our results show that seedlings preferentially grow under plants of different species, and that adults are significantly aggregated into vegetation patches. In these patches, adults tend to co‐occur with distant relatives, ultimately forming phylogenetically diverse neighbourhoods. We discuss possible mechanisms explaining how species adapted to serpentine areas may be acting as nurses, reducing the stressful conditions for the establishment of other species.
The Electoral Roots of America's Dysfunctional Government
Authors: Abramowitz Alan I.
Published: October 2013

Since the 2010 midterm election, a combination of ideologically polarized parties and divided government has resulted in gridlock in Washington. Neither party can implement its own policy agenda, but bipartisan compromise appears to be almost impossible to achieve. In this article, I present evidence that the deep ideological divide between the parties in Washington is itself rooted in divisions that have been developing in American society for decades. Democratic and Republican voters are much more divided along geographic, racial, cultural, and ideological lines than in the past. Polarization in Washington reflects polarization within the American electorate. The result has been gridlock in Washington along with increasing divergence of social and economic policies at the state level with red states and blue states moving in opposing directions. I argue that the only way to end gridlock in Washington is party democracy, which would require, at a minimum, ending the Senate filibuster but, ideally, major constitutional reforms such as eliminating midterm elections.
LordBryce's Curse: The Costs of Presidential Heroism and the Hope of Deliberative Incrementalism
Authors: Jacobs Lawrence R.
Published: October 2013

Presidents yearn for greatness to cement their “standing in history.” But their efforts are vulnerable to constitutional and political constraints. The gap between presidential hope and the limits on their power is vividly displayed by their record of “going public.” This article illustrates the costs of presidential promotions through a case study ofPresidentBarackObama's public campaign on behalf of health reform, which provoked countermobilization, encouraged media coverage of the opposition, and widened the public's exposure to potent messages that undercutWhiteHouse communications. The article concludes by suggesting partial steps to moderate expectations and work within institutional boundaries.
Presidents and Party Teams: The Politics of Debt Limits and Executive Oversight, 2001‐2013
Authors: Lee Frances E.
Published: October 2013

This article analyzes the president's leadership predicament in light of purely partisan considerations in Congress, meaning members' interests in winning and holding control of national institutions. I examine congressional votes to raise the debt limit, which are highly dependent upon patterns of institutional party control. I also examine high‐profile congressional charges of administration misdoing, another arena in which members of the president's party behave starkly differently from members of the president's opposition. These differences have consequences for presidential leadership, no matter the configuration of party control of national institutions.
Presidential Success in Supreme Court Appointments: Informational Effects and Institutional Constraints
Authors: Hitt Matthew P.
Published: October 2013

Spatial models of Supreme Court appointments assume that the president knows the preferences of nominees and is constrained only by the ideology of the Senate. However, nominees vary in the amount of available information that can be used to determine their preferences. I find that justices who offered more information in the form of relevant professional experience at the time of nomination are more congruent with their appointing president. Institutional factors, such as polarization between the Senate and president, exert less influence on congruence. The president is, however, constrained from appointing highly experienced justices if the Senate and president are distant ideologically.
Polls and Elections: Decreasing the Economy's Impact on Evaluations of the President: An Experiment on Attribution Framing
Authors: Newman Brian
Published: October 2013

Decades of research has shown that economic considerations are strongly tied to evaluations of the president. Many studies have found that framing (often called priming) by news coverage, events, and presidential rhetoric can increase the weight of economic and other considerations in presidential evaluations. I use a survey experiment to show that attribution frames can decrease the weight of economic considerations on presidential evaluations. The finding holds implications for the public's capacity to hold the president accountable and presidents' legislative strategies.
The Historical Presidency: Mr Secretary, My Son‐in‐Law:WilliamG.McAdoo,WoodrowWilson, and the Presidential Cabinet
Authors: Craig Douglas B.
Published: October 2013

The presidential cabinet has long been neglected by political scientists and political historians. The former tend to dismiss the cabinet as a noninstitution that has never transcended its lack of constitutional foundation; the latter have generally ignored it. Focusing on the progressive era, and upon one ofWoodrowWilson's most prominent cabinet secretaries, this article argues for a reconsideration of the presidential cabinet and its individual members as important policy and political actors during a time of increasing federal government competency but as yet unformedWhiteHouse executive agencies and staff.
Do soccer and Zumba exercise improve fitness and indicators of health among female hospital employees? A 12‐week RCT
Authors: Barene S. , Krustrup P. , Jackman S. R. , Brekke O. L. , Holtermann A.
Published: October 2013

This randomized controlled study investigated the effectiveness of soccer and Zumba on fitness and health indicators in female participants recruited from a workplace. One hundred seven hospital employees were cluster‐randomized to either a soccer group (SG), Zumba group (ZG), or control group (CG). Intervention effects for the two training groups were compared with CG. The training was conducted outside working hours as 2–3 1‐h sessions per week for 12 weeks. Peak oxygen uptake (VO2peak), fat percentage, fat mass, bone mineral content, and plasma osteocalcin were measured before and after the intervention period. Based on intention‐to‐treat‐analyses, SG significantly improved the VO2peak relative to body mass (5%; P = 0.02) and decreased heart rate during 100‐W cycle exercise (−7 bpm; P = 0.01), total body fat percentage (−1.1%; P = 0.002), and total body fat mass (−1.0 kg; P = 0.001) compared with CG. ZG significantly improved the VO2peak relative to body mass (5%; P = 0.03) and decreased total fat mass (−0.6 kg; P < 0.05) compared with CG. Plasma osteocalcin increased in SG (21%; P < 0.001) and ZG (10%; P = 0.01) compared with CG. The present study indicates that workplace initiated short‐term soccer training as well as Zumba outside working hours may result in fitness and modest health benefits among female hospital employees.
Controlled‐frequency breath swimming improves swimming performance and running economy
Authors: Lavin K. M. , Guenette J. A. , Smoliga J. M. , Zavorsky G. S.
Published: October 2013

Respiratory muscle fatigue can negatively impact athletic performance, but swimming has beneficial effects on the respiratory system and may reduce susceptibility to fatigue. Limiting breath frequency during swimming further stresses the respiratory system through hypercapnia and mechanical loading and may lead to appreciable improvements in respiratory muscle strength. This study assessed the effects of controlled‐frequency breath (CFB) swimming on pulmonary function. Eighteen subjects (10 men), average (standard deviation) age 25 (6) years, body mass index 24.4 (3.7) kg/m2, underwent baseline testing to assess pulmonary function, running economy, aerobic capacity, and swimming performance. Subjects were then randomized to either CFB or stroke‐matched (SM) condition. Subjects completed 12 training sessions, in which CFB subjects took two breaths per length and SM subjects took seven. Post‐training, maximum expiratory pressure improved by 11% (15) for all 18 subjects (P < 0.05) while maximum inspiratory pressure was unchanged. Running economy improved by 6 (9)% in CFB following training (P < 0.05). Forced vital capacity increased by 4% (4) in SM (P < 0.05) and was unchanged in CFB. These findings suggest that limiting breath frequency during swimming may improve muscular oxygen utilization during terrestrial exercise in novice swimmers.
A Closer Look at the Notorious Birthday Coincidences
Authors: Falk Ruma
Published: October 2013

The article asks about the minimal number of persons required for achieving a probability 1/2 thata. At least two share a birthday,b. At least one shares the reader's birthday. A basic question about the necessary number of checks underlies both problems.
Emotional‐motivational barriers to blood donation among Togolese adults: a structural approach
Authors: Alinon K. , Gbati K. , Sorum P. C. , Mullet E.
Published: October 2013

Background

Although the number of blood donors has been rapidly increasing in Togo since 2003, it is nevertheless insufficient to cover the demand.

Objectives

To increase needed blood donation in Togo, it is necessary to understand why most people are reluctant to do it.

Methods

A sample of 400 adult volunteers in Lomé, mostly university educated, rated, on a scale of 0–10, the relevance to them of a comprehensive list of reasons that might deter people from donating blood. The ratings of 250 participants were subjected to factor analysis, and the resulting factorial structure was confirmed on the ratings of the other 150 participants.

Results

The resulting six factors were labelled (in order of their ratings of a representative sample of items): Lack of Courage and Lack of Information (mean 5·43 of 10), Concerns about the Use of Blood (4·72), Risk Aversion (4·37), Fear of Medical Settings (2·41), Conformity with Tradition (1·88) and Indifference to Others and Hostility to the Procedure (1·69).

Conclusion

To increase blood donation, a public information campaign should address the emotional‐motivational barriers found even in the most educated segment of Togolese society.
Quantitative profiling and pattern analysis of triacylglycerol species in Arabidopsis seeds by electrospray ionization mass spectrometry
Authors: Li Maoyin , Baughman Ethan , Roth Mary R. , Han Xianlin , Welti Ruth , Wang Xuemin
Published: October 2013

Plant triacylglycerols (TAGs), or vegetable oils, provide approximately 25% of dietary calories to humans and are becoming an increasingly important source of renewable bioenergy and industrial feedstocks. TAGs are assembled by multiple enzymes in the endoplasmic reticulum from building blocks that include an invariable glycerol backbone and variable fatty acyl chains. It remains a challenge to elucidate the mechanism of synthesis of hundreds of different TAG species in planta. One reason is the lack of an efficient analytical approach quantifying individual molecular species. Here we report a rapid and quantitative TAG profiling approach for Arabidopsis seeds based on electrospray ionization tandem mass spectrometry with direct infusion and multiple neutral loss scans. The levels of 93 TAG molecular species, identified by their acyl components, were determined in Arabidopsis seeds. Quantitative TAG pattern analyses revealed that the TAG assembly machinery preferentially produces TAGs with one elongated fatty acid. The importance of the selectivity in oil synthesis was consistent with an observation that an Arabidopsis mutant overexpressing a patatin‐like phospholipase had enhanced seed oil content with elongated fatty acids. This quantitative TAG profiling approach should facilitate investigations aimed at understanding the biochemical mechanisms of TAG metabolism in plants.
Navigating the boundaries of active global citizenship
Authors: Lough Benjamin J , McBride Amanda Moore
Published: October 2013

This paper informs the active global citizenship debate by assessing whether returned international volunteers with a strong belief in the need for global governance also believe that participation in national political and civic spaces can drive global change. Regression models use survey responses from 245 returned international volunteers at three points in time. Findings indicate no significant difference in volunteers' conceptions of global citizenship before and after international service. However, volunteers who hold cosmopolitan views about the need for global governance have a higher sense of efficacy that participation in national spaces may affect global change. In addition, they are more likely to engage internationally but not locally. Findings suggest that global citizens may maintain an active civic identity rooted in overlapping locations. In addition, heightened notions of global citizenship appear to have a significant effect on returned volunteers' interest in international affairs and active engagement across national borders.
Evaluation of adjuvant carboplatin chemotherapy in the management of surgically excised anal sac apocrine gland adenocarcinoma in dogs
Authors: Wouda R. M. , Borrego J. , Keuler N. S. , Stein T.
Published: October 2013

There is no widely accepted standard of care for canine anal sac apocrine gland adenocarcinoma (ASAGAC). Surgery alone is inadequate in many cases, but the benefit of adjuvant chemotherapy is not well established. The primary objective of this retrospective study was to evaluate the role of carboplatin chemotherapy in the post‐operative management of ASAGAC. Seventy‐four dogs with naturally occurring ASAGAC underwent surgery. Forty‐four dogs received adjuvant carboplatin and 30 did not. Median overall survival (OS) was 703 days. Median time to progression (TTP) was 384 days. Only primary tumour size and lymph node metastasis at diagnosis significantly impacted the outcome. Differences in OS and TTP, between the dogs that received adjuvant carboplatin and those that did not, failed to reach statistical significance. Treatment of progressive disease, whilst not limited to chemotherapy, significantly prolonged the survival. This study shows that adjuvant carboplatin chemotherapy is well tolerated and may have a role in the management of dogs with ASAGAC.
Cryptic species in the cosmopolitan Bugula neritina complex (Bryozoa, Cheilostomata)
Authors: Fehlauer‐Ale Karin H. , Mackie Joshua A. , Lim‐Fong Grace E. , Ale Ezequiel , Pie Marcio R. , Waeschenbach Andrea
Published: October 2013

Previous analyses of the mitochondrial gene cytochrome c oxidase subunit 1 (COI) and γ‐proteobacterial endosymbiont diversity have suggested that the marine bryozoan Bugula neritina is a complex of three cryptic species, namely Types S, D and N. Types D and N were previously reported to have restricted distributions along California (western USA) and Delaware and Connecticut (eastern USA), respectively, whereas Type S is considered widespread in tropical, subtropical and temperate regions due to anthropogenic transport. Here, Bayesian species delimitation analysis of a data set composed of two mitochondrial (COI and large ribosomal RNA subunit [16S]) and two nuclear genes (dynein light chain roadblock type‐2 protein [DYN] and voltage‐dependent anion‐selective channel protein [VDAC]) demonstrated that Types S, D and N correspond to three biological species. This finding was significantly supported, in spite of the combinations of priors applied for ancestral population size and root age. Furthermore, COI sequences were used to assess the introduction patterns of the cosmopolitan Type S species. Two COI haplotypes of Type S (S1a and S1d) were found occurring at a global scale. Mantel tests showed correlation between these haplotypes and local sea surface temperature tolerance. Accordingly, the distributions of Type S haplotypes may reflect intraspecific temperature tolerance variation, in addition to the role of introduction vectors. Finally, we show that the Type N may also have been introduced widely, as this species was found for the first time in Central California and north‐eastern Australia.
Blade Tip Shape Optimization for Enhanced Turbine Aerothermal Performance
Authors: De Maesschalck C. , Lavagnoli S. , Paniagua G.
Published: October 2013

In high-speed, unshrouded turbines, tip leakage flows generate large aerodynamic losses and intense unsteady thermal loads over the rotor blade tip and casing. The stage-loading and rotational speeds are steadily increased to achieve higher turbine efficiency, and hence, the overtip leakage flow may exceed the transonic regime. However, conventional blade tip geometries are not designed to cope with supersonic tip flow velocities. A great potential lies in the modification and optimization of the blade tip shape as a means to control the tip leakage flow aerodynamics, limit the entropy production in the overtip gap, manage the heat-load distribution over the blade tip, and improve the turbine efficiency at high-stage loading coefficients. The present paper develops an optimization strategy to produce a set of blade tip profiles with enhanced aerothermal performance for a number of tip gap flow conditions. The tip clearance flow was numerically simulated through two-dimensional compressible Reynolds-averaged Navier–Stokes (RANS) calculations that reproduce an idealized overtip flow along streamlines. A multiobjective optimization tool, based on differential evolution combined with surrogate models (artificial neural networks), was used to obtain optimized 2D tip profiles with reduced aerodynamic losses and minimum heat transfer variations and mean levels over the blade tip and casing. Optimized tip shapes were obtained for relevant tip gap flow conditions in terms of blade thickness to tip gap height ratios (between 5 and 25) and blade pressure loads (from subsonic to supersonic tip leakage flow regimes), imposing fixed inlet conditions. We demonstrated that tip geometries that perform superior in subsonic conditions are not optimal for supersonic tip gap flows. Prime tip profiles exist, depending on the tip flow conditions. The numerical study yielded a deeper insight on the physics of tip leakage flows of unshrouded rotors with arbitrary tip shapes, providing the necessary knowledge to guide the design and optimization strategy of a full blade tip surface in a real 3D turbine environment.
Mexican laws and standards on acoustics
Authors: Saad Omar
Published: October 2013

We explore the current state of Mexican standards and laws on acoustics, current efforts on the way to improve such standard and international standards that society has adopted due to the limited Mexican laws on noise.
Analysis of the Mexican standard on optimal reverberation times according to enclosure function
Authors: Beristain Sergio
Published: October 2013

The Mexican Standard No. NOM-C-211-1977 on optimal reverberation times according to the enclosure use, published in December 1977, and without any substantial modification so far, establishes optimum re- verberation times for different room applications, which by virtue of time reverberation measurements described in the Mexican Standard No. NOM-C-147-1977 on field measurements of reverberation time in enclosures, and the Eyring reverberation time equation, requires given acoustical conditions within rooms, and sets tolerance limits, so this is a method for testing and modification of already-built rooms’ response. The full procedure is presented in this paper, so actually two Mexican standards are being discussed here, in order to be able to compare with other standards and methods employed elsewhere.
Airport noise complaint patterns and interviews of frequent complainers at two major air carrier airports
Authors: Jaggers Nicholas , Eiff Gary
Published: October 2013

The complex and highly sensitive topic of aircraft noise and population annoyance continues to be a major inhibitor to airport development plans. The projected growth of air travel necessitates expanded capacity at many existing airports and the development and construction of new airports in order to accommodate burgeoning traveler needs. Concerns by citizens near major airports about their economic, health, and social welfare continue to generate community and individual declarations of annoyance and concern which threaten timely solutions to airport expansion plans. A deeper understanding of the nature of these concerns is important to more effectively cope with airport expansion concerns among adjacent communities and surrounding neighbors. This study analyzed existing noise complaints registered at Denver International Airport (DEN) and Fort Lauderdale/Hollywood International Airport (FLL) in an attempt to gain greater understanding of noise complaint drivers and public annoyance. Interviews of frequent complainers were utilized in order to gain richer data concerning individual annoyance issues.
Bill Lang’s many contributions to international standardization in acoustics
Authors: Higginson Roger
Published: October 2013

Over the past 40 years, Bill Lang has been a major force in Intl. Standards, not only as ongoing leader of the U.S. delegation, but in a personal capacity as project leader for the development of the pivotal group of standards on methods of determining sound power level. As Convenor of the previous Working Group 6 of Sub-Committee 1, Noise, of ISO Tech. Committee 43, Acoust., he oversaw the production of the ISO 3740 series of standards during the 1970s and early 1980s. A revision of this same series was made starting in the late 1980s, once more under Bill’s supervision in the current Working Group 28. At the same time, this Group compiled the new series of ISO 11200 standards on determination of emission sound pressure levels, on declaration and verification of noise emission levels and on guidelines for writing noise test codes. As if this was not enough, the same group is now in the throes of another major short-term revision of all the documents and has plans for further more radical revisions in the future. This paper outlines Bill’s contributions to this major international combined effort, which even after such sustained activity goes from strength to strength, gathering participation from a new generation of acousticians around the world.
Geoacoustic inversion using ship noise received on the ship-towed line array
Authors: Yang T. C. , Yoo Kwang , Fialkowski Laurie
Published: October 2013

There has been increased interest in geoacoustic inversion using a ship-towed line array including recent work by M. Siderius et al., J. Acoust. Soc. Am. 11, 1523 (2002), D. J. Battle et al., IEEE J. Ocean Eng. 28, 454 (2003), and M. R. Fallat et al., IEEE J. Ocean Eng. 29, 78 (2004). One notes that bottom properties in the littoral oceans can vary substantially over a small spatial scale (a few kilometers). Using either manned noise or own ship noise received on the towed array, one can invert for the geoacoustic properties of the bottom under the ship. With the ship’s mobility, one can potentially survey a large area in a short time. The problem is that geoacoustic inversion can have ambiguous solutions, namely, that often more than one solution can fit the data. For building a database, this method becomes useless if inconsistent solutions are obtained between measurements. In this paper, recent advances that lead to a reliable, consistent, and often unique solution using a signal with known waveform are reviewed. This is demonstrated with at-sea data and generalized to geoacoustic inversion using own ship noise. [Work supported by the U.S. ONR.]
Estimating geoacoustic properties of marine sediments by matched field inversion using ship noise as a sound source
Authors: Morley Michael G. , Chapman N. Ross
Published: October 2013

The first stage of a seafloor observatory to monitor marine gas hydrates will be deployed in the Gulf of Mexico in the fall of 2005. One component of the monitoring station is a vertical line hydrophone array moored on the seafloor. This paper reports research to investigate using matched field inversion of sound generated by passing ships to detect changes in the geoacoustic parameters of the seabed that may indicate the occurrence of a gas hydrate dissociation event. First, synthetic multifrequency data were used to investigate the performance of the inversion method for estimating sediment sound speeds near the seafloor. The synthetic data were generated using the parabolic equation method for a geoacoustic environment that simulated the seabed at the site in Mississippi Canyon. The geoacoustic model consisted of a multilayered structure with relatively slow sound speeds to significant depths below the seafloor. The inversion based on normal mode replica fields indicated that performance strongly depends on using a realistic parametrization of the geoacoustic model. Experimental ship noise data were recorded along radial tracks in a preliminary deployment of the vertical array. Results are reported for estimating a geoacoustic model from the noise data.
Matched-field passive inversion using ships of opportunity
Authors: DelBalzo Donald R. , Wilson James H. , Prater Robert A. , Neumann Peter D.
Published: October 2013

Acoustic field estimation in littoral areas is severely limited by uncertainty in sediment property characteristics. Direct methods of obtaining geophysical data are expensive, so inverse methods have recently become popular. Most techniques rely on inverting reverberant signals from controlled active sources received on vertical apertures. This work is focused on using surface ships of opportunity in a range-staggered way to create a range-dependent mosaic of sediment properties and bathymetry with ever increasing confidence. Matched-field/matched-phase techniques and adaptive simulated annealing are applied in a complex simulated shallow-water environment with a single vertical array and high signal-to-noise ratios. These procedures can also be applied to horizontal arrays. The inversion process is evaluated as a function of frequency bandwidth and array length. The simulations indicate significant potential for passive geoacoustic characterizations out to ranges of tens of water depths in shallow water.
Measurement and visualization of three-dimensional directivity pattern
Authors: Arndt Georg-Erwin , Gebert Anton , Klemenz Harald , Ritter Hartmut C.
Published: October 2013

In order to optimize a new second-order multimicrophone technology for a KEMAR dummy head, a three-dimensional directivity measurement setup was developed. To minimize mechanical mass and to reduce total measurement time a C-Bow setup was used, containing 18 calibrated loudspeakers. Those small tweeters identical in construction are placed in every 10 deg of elevation in a semicircular arc of 2-m diameter. The only moving part of this setup is a full-circle rotating KEMAR. The ANSI Standard 3.35 for directional measurement is fully supported and the required 48 measuring points are completed in less than 3 min. Using this fast and simple setup, the various responses attained from different latitudes need to be weighted to calculate a three-dimensional directivity value. Utilizing an equally distributed number, for example 400 measuring points easily executable with this setup, weighting can be omitted and a three-dimensional plot with high resolution can be visualized. Additionally, two-dimensional cuts of different planes in horizontal, vertical, and sagittal direction can be displayed. Data of unaided KEMAR, as well as data from the hearing aid used during those measurements, are presented and discussed.
Measurement of directivity index by three-dimensional spatial sampling
Authors: Julstrom Stephen D.
Published: October 2013

The traditional method for finding the directivity index (DI) of a microphone by extrapolation from its two-dimensional polar pattern may not be accurate when the microphone or its mounting surface is acoustically large. In situ hearing aid microphone DI determination requires knowledge of the full three-dimensional directional response. Microphone DI may be measured directly by comparison of the on-axis anechoic sensitivity to the sensitivity in a diffuse sound field, normalizing the comparison by reference to a perfect omnidirectional microphone. In practice, creating an accurately diffuse field is difficult, and is traditionally accomplished by averaging measurements taken at several locations in a reverberant room excited by multiple uncorrelated sound sources. Theoretically equivalent results can be obtained by three-dimensional spatial sampling in an anechoic environment, inferring the full spherical response from a finite number of directional measurements. The necessary density, positioning, and positioning accuracy of measurement directions is determined by sampling theory, tests employing mathematically defined polar patterns, and practical considerations, leading to a minimum specification of 48 measurement points arranged in five horizontal zones. Non-uniform spacing of these points necessitates employing a weighted average of the sensitivity measurements to obtain the best prediction of the actual diffuse field response.
On the use of waveform images to describe the initial response of finite-length waveguides
Authors: Ginsberg Jerry H.
Published: October 2013

The d’Alembert solution of the wave equation can be adapted to describe reflection from planar boundaries. One technique for doing so images the incident wave on the opposite side of the boundary. This concept has been introduced in a few texts, most extensively by Morse and Ingard [Theoretical Acoustics, McGraw-Hill, New York (1964), pp. 106–115], but only for nondissipative ends (infinite or zero impedance.) This paper formalizes the procedure for the case where the boundary has a resistive impedance that is independent of frequency, and then extends it to treat waveguides of finite length. It is shown that the field that results from arbitrary initial conditions can be represented by an infinite number of images. This leads to a representation of the acoustic field as oppositely propagating wave in an unbounded waveguide, with only a limited number of images overlapping at any instant. Both mathematical and graphical descriptions of these waves are derived. In addition to assisting the student to understand the evolution of the field, mathematical analysis of the image construction leads to a number of physical and mathematical insights to fundamental acoustic phenomena. These include the fact that the field in the dissipationless case can be represented as a modal series with associated natural frequencies, and a quantitative understanding of the manner in which the field decays when either end is dissipative. A corollary of the latter analysis is an expression for reverberation time that is remarkably similar to the Norris–Eyring formula. From an instructional viewpoint, the fact that all results are derived without recourse to solving differential equations makes the image waveform concept especially useful as a way of introducing new students to fundamental acoustic phenomena.
Status of duct liner technology for application to aircraft engine nacelles
Authors: Parrott Tony L. , Jones Michael G. , Watson Willie R.
Published: October 2013

The peculiar technical requirements that constrain the design of acoustic liners used to suppress turbo-machinery noise emission from commercial aircraft engine nacelles continue to make the design of such liners a challenge. The need for increased liner efficiency and suppression bandwidth is particularly critical in the face of ever decreasing nacelle wall area available for liner treatments in modern high bypass ratio engines. This paper reviews some of the key advances in the enabling measurement technologies that have been critical to creating and validating impedance models for liner structures suitable for the harsh aeroacoustic environments encountered on the inside of nacelle inlets and exhaust ducts. Specifically, the paper describes recent advances and outstanding issues related to determining liner impedance beneath high speed grazing flows combined with high sound levels. Evolution of this technology has resulted from the need for more reliable/accurate impedance determinations, and from the impetus provided by modern data acquisition systems and computational methodologies. Outstanding issues include discrepancies between impedances as educed in different laboratories under similar aeroacoustic conditions. For single layer, perforate over honeycomb type structures, these discrepancies are mainly confined to the normalized resistance component and may be as large as 0.50.
Application of acoustic radiosity methods to noise propagation within buildings
Authors: Muehleisen Ralph T. , Beamer C. Walter
Published: October 2013

The prediction of sound pressure levels in rooms from transmitted sound is a difficult problem. The sound energy in the source room incident on the common wall must be accurately predicted. In the receiving room, the propagation of sound from the planar wall source must also be accurately predicted. The radiosity method naturally computes the spatial distribution of sound energy incident on a wall and also naturally predicts the propagation of sound from a planar area source. In this paper, the application of the radiosity method to sound transmission problems is introduced and explained.
Time-domain calculations of attenuative and dispersive sound propagation in porous media
Authors: Wilson D. Keith , Ostashev Vladimir E. , Collier Sandra L. , Marlin David H. , Aldridge David F. , Symons Neill P.
Published: October 2013

Previously, a set of time-domain equations for broadband sound propagation in rigid-framed porous materials [Wilson et al., J. Acoust. Soc. Am. 116, 1889–1892 (2004)] was derived by modeling viscous and thermal diffusion in the pores as relaxational processes. In this paper, the time-domain relaxational model is shown to be analogous to a phenomenological model previously proposed by Zwikker and Kosten, when the resistance constant, structure constant, and compressional modulus are allowed to be slowly varying functions of frequency. An algebraic inversion of the structure constant and compressional modulus is described that leads to a state-equation system amenable to numerical implementation. Attenuation and dispersion are described by convolution integrals between the acoustic fields and the relaxation functions. Numerical techniques are formulated that discretize the convolution integrals and reduce to known results in low- and high-frequency limits. The techniques are implemented in finite-integro-difference, time-domain calculations of sound interactions with absorbing porous panels and outdoor propagation scenarios involving hills and barriers.
Application of noise source identification techniques to information technology equipment
Authors: Upton Roger , Dirks Gijs
Published: October 2013

Conventional noise source identification techniques are usually associated with larger mechanical sources such as engines, gearboxes, and the like, having medium to high noise emissions. The IT industry presents a different problem-set, though, in that the noise sources are usually smaller and are relatively low level. However, this does not prevent use of these techniques, in that they can be adapted to measurements on typical IT products. Tools for doing this include the use of non-contacting transducers such as laser vibrometers as references, making array measurements with a small-geometry transducer such as a probe microphone, and using conventional microphone arrays but with reduced grid spacing. This paper examines the application of these tools to noise source identification techniques such as coherent power, intensity mapping, and stationary and non-stationary near-field acoustical holography, such that they can be used on IT equipment. The different methods are illustrated with noise source identification exercises on a laptop PC and a 3 1/2-in. hard-disk-drive. Finally, the paper discusses the application of beam-forming techniques for noise source identification on IT products in general.
Evaluating the bonding condition of NASA spray on foam insulation (SOFI) using audio frequency sound absorption measurements
Authors: Thompson Todd A. , Mann J. Adin
Published: October 2013

The bonding condition of the spray on foam insulation (SOFI) used to insulate the external tank of the NASA space shuttle can be found by using the audio frequency sound absorption coefficient. The ASTM E1050 standard method for sound absorption measurements was used with an open-ended 1-in-diam cast acrylic impedance tube sealed to the SOFI with closed cell PVC foam. Two artificially disbonded locations, measuring 1.0 in. by 5.5 in. by 0.0625 in. and 2.0 in. by 8.0 in. by 0.0625 in., were detected by peaks in the sound absorption coefficient spectrum. The peaks in the sound absorption spectrum between 1000 and 4000 Hz were 25% to 50% higher over disbonded areas when compared to bonded locations. The maximum and minimum sound absorption levels for the foam ranged between approximately 0.1 and 0.3. The entire sample was scanned using the sound absorption peaks as indicators. Samples of 2-in.-thick polystyrene foam were used with different sized defects at different locations in the foam to relate defect size and location to peaks in absorption coeffi-cient spectrum. [Work supported by NASA under Award No. NAG102098.]
Application of the heterogeneous (HG) blankets for controlling the base structure vibration levels
Authors: Gautam Ashwini , Fuller C.R. , Carneal James
Published: October 2013

This work presents an extensive analysis of the properties of the heterogeneous blankets (HGs) and their effectiveness in controlling the vibration of the base structures. The HG blankets act as a distributed vibration absorbers consisting of mass inhomogeneities inside a layer of porous media (acoustic foam). To asses the effectiveness of these HG blankets in controlling the vibration of the base structure (plate), detailed finite element (FE) models of the foam, the HG blanket, and the plate have been developed. The foam has been dicretized using the eight node hexahedral elements. The HG blanket model consists of the foam model with point masses attached to the nodes of the elements. The structural (plate) domain is discretized using four node rectangular plate elements. Each of the FE models has been individually validated by comparing the numerical results with their respective analytical and experimental results. The structural and the HG blanket FE models were then combined into a larger FE model comprised of a base plate with the HG treatment on its surface. The results from this numerical model have shown that there is a significant reduction in the vibration levels of the base plate due to the HG treatment on it.
Identification and prediction of piping system noise
Authors: Fagerlund Allen , Catron Fred , Karzcub Denis , Martin Tucker
Published: October 2013

In a power plant environment, the piping systems form a network that extends throughout the facility. Various components can be major sources of in-plant and community noise, both the pipe and the contained fluid can be propagation paths, and radiation can occur from the external surface. Though the basics of these phenomena may be understood, the translation into workable predictive tools has been slow. Too often, source, propagation, and radiation effects are treated as separate entities without allowing for the interactions that exist. The spectral characteristics of the sources will govern the type of response by the system. Pipe transmission loss models will change in pipe to duct transition areas. The status of these concepts will be reviewed with a discussion of current and possible future efforts to improve existing models.
Critical assessment of thermal/acoustical insulation for pipe and duct noise
Authors: Hale Marlund E.
Published: October 2013

Piping and duct networks are among the major sources and distributors of noise in power plants. This noise is generated primarily by large rotating equipment and devices, primarily valves, with a large pressure drop. Piping and duct noise controls include silencers, thermal/acoustical insulation (lagging), and special treatments (e.g., low noise valve trims and diffusers). The effectiveness of acoustical lagging for pipe and duct noise depends on the type of source, coupling of the piping to sources or support structures, and the frequency spectra radiated. The acoustical performance of pipe lagging systems has been reported by a number of researchers over the past several decades. Today both ASTM and ISO have issued testing standards for the evaluation of pipe lagging systems, and the ISO standard also provides pipe lagging design guidance. Current technology for measuring the TL of lagging, predicting pipe and duct noise, and predicting the IL of lagging is critically assessed. This paper reviews the methods and results of the two standards and compares several laboratory test results with field measurements. Some challenges are presented along with suggestions for improving prediction of piping and ductwork noise abatement within power plants and in the community.
Acoustical performance of power plant enclosure walls—a critical assessment of needs
Authors: Putnam Robert A. , Frederick Noel
Published: October 2013

The acoustical design of power generating facilities invariably requires knowledge of the transmission loss characteristics of acoustical enclosures, from component specific housings to generation buildings. Many of the composite wall configurations used by vendors are either proprietary or of such recent design that laboratory test data (TL per ASTM E90) are not available. Several factors contribute to uncertainty in the application of test data. At frequencies of 125 Hz and below, all such laboratory based test data should be considered suspect, especially since for plants in which sound emissions are heavily attenuated, the low frequencies tend to become progressively more dominant at far field positions. Thus the far field A-weighted sound levels from power plants, especially those of low noise design, are governed by sound energy in precisely the frequency range for which the TL’s for walls and enclosures are least reliable. Further, the size and mounting of power plant walls differs significantly from the same walls mounted in an ASTM E90 test facility. This paper gives a critical assessment of the sources of the uncertainties, suggestions for methodologies to obtain more reliable TL data and discusses the effects to be expected, illustrated by way of selected examples.
The development of specifications and discussion of business models for ensuring speech privacy in the healthcare industry
Authors: Lavallee Timothy , Good Kenneth , Sykes David
Published: October 2013

The Health Insurance Portability and Accountability Act of 1996 (HIPAA) was developed, among other reasons, to hold healthcare providers accountable for the privacy of patient’s personal and medical information. It includes language addressing the need for ‘‘reasonable safeguards’’ for speech privacy and oral communication in a healthcare setting. After 50 years of development, speech privacy science and mechanisms are well understood. However, current specifications cannot be directly applied and are not specifically written to address the application of the current acoustical knowledgebase to the health care industry’s need for compliance. This is a discussion of the state of existing privacy technology and specifications; the ability and availability of mechanisms currently in the health care industry as a possible route for implementation of the regulation; the state of development of specification to address specifically the industry’s needs; and a potential business model for implementation.
Speech privacy: Beyond architectural solutions
Authors: Mazer Susan
Published: October 2013

HIPAA regulations have brought unparalleled pressures on healthcare organizations to protect private and confidential information from reaching third parties. Yet, as this paper explains, often in the middle of noisy corridors and waiting rooms, this same information needs to be quickly transferred from physician to nurse to family member to others for the care of patients. Research and examples are presented that show that when families, patients, staff are participating together, although independently, in the same or adjacent spaces, the ‘‘caf effect’’ produces rising noise levels as each person competes to be heard. This threatens the very confidentiality demanded by HIPAA. Solutions to this problem are not easy or completely resolved by engineering or design specifications. This paper makes the case that it is ultimately the culture of a healthcare organization that determines the ‘‘sound’’ of a hospital, and any other organization that battles openness with privacy. It presents and discusses proven solutions to address culture in tandem with architectural and acoustic design interventions.
Speech privacy performance of a new hospital and medical office building
Authors: Roy Kenneth P. , Good Kenneth W. , Snader Anita M. , Hatzel Sharon K.
Published: October 2013

Shortly after the occupation of a new hospital and medical office building, both objective and subjective evaluations of the acoustic performance of these facilities were made. The goals of this work were twofold: first, to survey the occupants’ subjective perception of the acoustic environment relative to noise, distractions, speech privacy, etc; and second, to relate the subjective perception to objective measures of noise isolation rating (NIC), background noise (dBA), and speech privacy rating (PI). Knowing the construction details of the walls, ceiling, doors, etc. also allowed a comparison of the measured NIC to the expected STC for each type of construction. In this way it was possible to identify robust architectural systems versus weak systems with inherent flanking and leakage paths.