bluuebunny/crossref_metadata_2025 huggingface dataset:
The Employer's Role in Reforming the U.S. Health Care System
Authors: Sperling Kenneth L.
Published: March 2006

In 2005 large U.S. employers spent an average of almost $7,400 per head on health care benefits, a 73% increase in the last five years. If the current trend continues, American companies may find it difficult to compete in a global marketplace where international competitors provide labor with heath care at a fraction of U.S. costs.

This article argues that effective reform of the U.S. health care system will require major efforts from all major “stakeholders,” starting with the federal government and state and local governments and including insurance companies and the “consumers” of health care services. By far the important role, however, is reserved for private‐sector employers, which have been the incubator for recent innovations in American health care and are in the best position to coordinate and drive health care reform.

But incremental steps in cost‐sharing, small‐scale pilot projects of consumer‐based designs, and employee awareness campaigns will not be enough. Employers need to take radical steps to break through the inertia that has built up among all stakeholders over the past 50 years. Chief among the author's proposals for employers are the following:

In choosing a health care plan for employees, use value‐based purchasing criteria that consider more than just the price and access to services.

Help consumers by demanding information from providers and insurers about the cost and efficacy of health care services, and of alternative treatments, before the choices are made.

Encourage “consumerism” by setting up benefit plans that have a Health Reimbursement Arrangement (HRA) or a Health Savings Account (HSA) component.

As the author states in closing, “Let these reforms begin with employers as the organizing force to drive needed change across the system. That may very well be the only way to save our employment‐based model.”
New Leadership at the Federal Reserve*
Authors: Plosser Charles I.
Published: March 2006

As Chairman of the Federal Reserve for the past 18 years, Alan Greenspan deserves praise for his stewardship of monetary policy. He has guided the Fed and monetary policy in a way that has led to low and stable inflation. But if Greenspan's record clearly deserves praise, he could have done more to move monetary policy into the 21st century and prepare the institution for the future.

Greenspan has relied heavily on his personal judgment and has argued repeatedly that the Fed must have extensive flexibility to respond to the economic environment. But if Greenspan's judgment, skill, and luck have served him and the country well, it is dangerous to rely so heavily on the judgment of a single individual. When he departed, he took with him his skill and judgment, as well as his credibility and his personal commitment to low inflation. The Fed he leaves behind has no explicit institutional commitment to long‐run price stability.

This article argues that by operating with a set of rules and guidelines, or at a minimum clearly stated institutional objectives, the Fed would eliminate much of the second guessing about what it is doing and why, and the associated volatility in markets. More generally, the benefits of more explicit guidelines for monetary policy include:

Increasing public understanding of monetary policy, including what it can and cannot do.

Increasing transparency and accountability. Most organizations have clear goals and we hold their leaders accountable. The Fed is different. The Fed seems to be held accountable for all things economic and thus it is truly accountable for nothing. It never has to explain its actions and what went right or wrong.

Establishing a clear focus for the Fed regarding its goals and objectives.

Creating increased confidence that sound monetary policy will be followed in the future.
Promoting nurse practitioner practice through research: Opportunities, challenges, and lessons
Authors: Hayes Eileen
Published: March 2006

Purpose: To discuss the opportunities derived, challenges faced, and lessons learned in the research process, including recruiting and retaining nurse practitioner (NP) participants, obtaining institutional approval, and solving research team issues in a National Institutes of Health/National Institute of Nursing Research (NIH/NINR)‐funded study of communication between NPs and their older patients in managed care and non–managed care settings.

Data sources: The video‐taped interactions between 30 NPs and 150 patients, research team experiences in conducting the research, and a review of relevant literature.

Conclusions: Key factors in NP study participation included recognizing the importance of research in demonstrating the effectiveness of the NP role and for advancing the profession, having participated in previous research, enjoying the research process, employer incentives, membership in NP professional organizations, relationships with the university and the school of nursing conducting the research, and knowledge of the coinvestigator's work. NP recruitment was facilitated by word of mouth, professional organization assistance, and articles in a widely distributed, free nursing journal. Data collection was significantly delayed by attrition of NP participants, logistical problems with scheduling and travel, and varied approval procedures by Institutional Review Boards (IRBs) at study sites. The pace of nursing research could be much more efficient if IRB processes involved fewer bureaucratic entanglements. Preliminary study findings, however, show positive outcomes for older patients after NP care.

Implications for practice: To demonstrate positive patient outcomes and move the NP profession forward, NPs must be willing to commit to participation in research on their effectiveness as providers in today's healthcare environment.
Analysis of canine and feline blood samples using the Kuadro in‐house wet‐reagent chemistry analyser
Authors: Papasouliotis K. , Dodkin S. , Murphy K. , Woloszczuk G. , Fleming M.
Published: March 2006

Objectives: Kuadro is a new wet‐reagent biochemistry analyser that is available for in‐house use. The aim of this study was to compare the results produced by this analyser with those obtained by a wet‐reagent analyser (KoneLab 30i) that served as the reference instrument.

Methods: Blood samples from 80 clinical cases (40 dogs and 40 cats) were analysed for urea, creatinine, total proteins, albumin, glucose, cholesterol, alanine aminotransferase, alkaline phosphatase, total bilirubin, amylase, total calcium, and phosphate using both the reference and Kuadro instruments.

Results: Kuadro performed very well on canine and feline samples, showing clinically acceptable correlations (r value) (canine/feline) for urea (0·99/0·97), creatinine (0·99/0·98), total proteins (0·95/0·97), albumin (0·98/0·90), glucose (0·99/0·99), cholesterol (0·99/0·99), alanine aminotransferase (1·00/0·99), alkaline phosphatase (0·96/0·99), total bilirubin (1·00/1·00), amylase (0·98/0·96), and phosphate (0·91/0·92). The correlation for total calcium measurements was clinically unacceptable (0·78/0·83).

Clinical Significance: Urea, creatinine, albumin, glucose, cholesterol, alanine aminotransferase, and phosphate Kuadro values can be used interchangeably with those generated by the reference analyser. Alkaline phosphatase, amylase, and total proteins Kuadro values cannot be used interchangeably, as Kuadro overestimated alkaline phosphatase and amylase and underestimated total protein measurements. Kuadro significantly underestimated total calcium concentrations due to the shorter incubation time used by the Kuadro analyser compared with the incubation time used in the reference analyser assay system.
Distribution, abundance, and individual strategies: a multi‐scale analysis of dasyurid marsupials in arid central Australia
Authors: Haythornthwaite Adele S. , Dickman Christopher R.
Published: March 2006

We investigated the effects of different environmental factors on the distribution and abundance of 6 species of dasyurid marsupials using a multiple‐scale analysis. Data collected in the spinifex dunefields of the Simpson Desert, Australia, were analysed at 3 spatial scales spanning more than 5 orders of magnitude: “metasite” (covering an area of 1000–2000 km2), site (2–12 km2) and grid (0.01 km2). Temporal variability was also investigated, using data collected in March, April, and May in 4 consecutive years from 1997 to 2000. Both abiotic and biotic factors influenced the capture rates of different species at different times and spatial scales. At the coarsest spatial scale, Dasycercus cristicauda (mulgara) was consistently limited in its distribution by the intensity of rainfall, probably as an indirect result of increased grazing pressure from pastoral activity and a higher density of feral predators in high rainfall areas. However, at the finest spatial scale, this partly carnivorous species was scarce in areas of dense spinifex, perhaps because such habitats yield lowest returns during foraging, and was more common in areas where small invertebrate prey were abundant. Factors affecting the distribution of the most abundant dasyurid species in the study area, Sminthopsis youngsoni (lesser hairy‐footed dunnart), could not be identified at any scale; we conclude that this reflects the opportunistic foraging strategies and flexible habitat requirements of this insectivorous species. Both Ningaui ridei (wongai ningaui) and Sminthopsis hirtipes (hairy‐footed dunnart) were less abundant throughout the study region. For N. ridei, a spinifex specialist, predictors of occurrence could be identified only at the finest scale of analysis; at the grid level, a close positive association was detected in 2 of the 4 study years between capture rate and spinifex cover. For S. hirtipes, all 3 levels of spatial analysis revealed a negative association between capture rate and both rainfall and spinifex density. For the rarely‐caught S. crassicaudata (fat‐tailed dunnart) and Planigale tenuirostris (narrow‐nosed planigale), no clear results were obtained at any spatial scale, and we interpret this to indicate that the study region represents sub‐optimal habitat for these species.

Given that different factors affected the distribution and abundance of dasyurids at different spatial scales over time, we conclude that a multiple‐scale approach to population and community analysis is vital to accurately identify which environmental processes shape population and community dynamics. Understanding the interplay between regional and local processes will be crucial for management of existing species populations and for prediction of their distributions and abundances in future.
Individual quality and food availability determine yolk and egg mass and egg composition in tree swallows Tachycineta bicolor
Authors: Ardia Daniel R. , Wasson Matthew F. , Winkler David W.
Published: March 2006

Variation in egg size and composition can have important consequences for the quality of offspring. We investigated the factors influencing the yolk mass and egg mass of tree swallows breeding in Ithaca, NY. Using a nondestructive technique to estimate yolk mass via standardized digital‐candler photographs, we compared yolk size and egg size of tree swallows Tachycineta bicolor in response to variation in food availability and individual quality. Insect availability one to three days prior to laying, but not four to six days, predicted yolk mass, while insect availability two to three days prior to laying predicted total egg mass. This suggests that, while eggs are formed over longer periods, food availability closer to time of laying has the greatest influence on egg size. These results were supported by collected eggs, as yolk rings revealed that tree swallow eggs are formed over 5–6 days. There was an influence of female quality as well, with early laying birds, independent of food availability, laying larger eggs. Eggs laid later in the laying sequence had larger yolks and greater egg mass. Overall, variation in egg quality appears to be due to a combination of environmental conditions, reflected in food resources, individual quality, and allocation tradeoffs during the laying period.
Error Analysis and Compensation for Meshing Contact of Toroidal Drives
Authors: Yao Ligang , Dai Jian S. , Wei Guowu
Published: March 2006

This paper investigates the meshing errors of the toroidal drive, reveals three typical latency errors and develops the error analysis in this typical type of gear drives. Having identified the latency errors, the error integrated coordinate transformation is implemented. This leads to the development of the error impinged meshing model. The model reveals for the first time the effect of the latency errors in gear meshing contact of a toroidal drive and characterizes the error effect on meshing contact. The effect of these errors on the gear coordinate frames is hence presented and on the contact paths of rollers is analyzed. The study leads to a new method for compensating the three latency errors by introducing a bearing with a changeable oil film. The method is then verified in a prototype and demonstrates to be effective.
Finding Dead-Point Positions of Planar Pin-Connected Linkages Through Graph Theoretical Duality Principle
Authors: Shai O. , Polansky I.
Published: March 2006

The paper brings another view on detecting the dead-point positions of an arbitrary planar pin-connected linkage by employing the duality principle of graph theory. It is first shown how the dead-point positions are derived through the interplay between the linkage and its dual determinate truss—the relation developed in the previous works by means of graph theory. At the next stage, the process is shown to be performed solely upon the linkage by employing a new variable, the dual of potential, termed face force. Since the mathematical foundation of the presented method is discrete mathematics, the paper points to possible computerization of the method.
Automated Conceptual Design of Mechanisms Using Improved Morphological Matrix
Authors: Chen Yong , Feng Peien , He Bin , Lin Zhonquin , Xie Youbai
Published: March 2006

Conceptual design of mechanisms has attracted a number of research efforts in recent years due to its significance in product development. However, existing approaches for automated conceptual design of mechanisms are either prone to a loss of optimal solutions or inextensible to achieve conceptual design of complex mechanisms. This paper is devoted to developing a comprehensive and extensible methodology for automated conceptual design of mechanisms utilizing a design prototype synthesis methodology. To support automated mechanism synthesis effectively, the traditional morphological matrix is improved as a motional function matrix (MFM). In addition, a mechanism prototype knowledge base is developed to provide systematic knowledge support for conceptual design decision-making. Based on the integrated MFM, an exhaustive mechanism synthesis algorithm is developed to yield as many solutions as possible to desired functions to facilitate the discovery of novel and optimal combinatorial solutions. To curb the possible combinatorial explosion from the exhaustive search, a performance constraint verification approach is proposed to help designers filter out combinatorial solutions violating performance constraints, followed by a satisfaction degree-based approach for evaluating the total performances of combinatorial solutions according to the performances of their subsolutions. An automated mechanism conceptual design prototype system is developed and a design case is presented to illustrate the feasibility and practicality of the proposed methodology.
Shape and Size Synthesis of Compliant Mechanisms Using Wide Curve Theory
Authors: Zhou Hong , Ting Kwun-Lon
Published: March 2006

A wide curve is a curve with width or cross section. This paper introduces a shape and size synthesis method for compliant mechanisms based on free-form wide curve theory. With the proposed method, detailed dimensions synthesis can be performed to further improve the performance after the topology is selected. Every connection in the topology is represented by a parametric wide curve in which variable shape and size are fully described and conveniently controlled by the limited number of parameters. The shape and size synthesis is formulated as the optimization of the control parameters of wide curves corresponding to all connections in the topology. Problem-dependent objectives are optimized and practical constraints are imposed during the optimization process. The optimization problem is solved by the constrained nonlinear programing algorithm in the MATLAB Optimization Toolbox. Two examples are included to demonstrate the effectiveness of the proposed synthesis procedure.
Linear Property of the Screw Surface of the Spatial RPRP Linkage
Authors: Huang Chintien , Tu Han-Tsung
Published: March 2006

This paper investigates the screw surface of the RPRP linkage, an overconstrained linkage with mobility one. The screw surface is a ruled surface containing screws for displacing the coupler of the RPRP linkage from one reference position to all reachable positions. In this paper, two types of RPRP linkages, in folded and unfolded forms, are constructed by using hexahedrons in accordance with Delassus’ criteria. It is shown that the screw surfaces of both types of RPRP linkages can be represented by screw systems of the second order. These novel finite screw systems are obtained by intersecting two 3-systems corresponding to the finite displacements of the RP and PR dyads. The intersection of finite screw systems is conducted by employing the intersection operation of vector subspaces of the six-dimensional vector space.
A Topology Optimization Problem in Control of Structures Using Modal Disparity
Authors: Diaz A. R. , Mukherjee R.
Published: March 2006

Modal disparity and a topology optimization problem seeking to maximize this disparity are introduced, with the goal of developing a new methodology for control of vibration in flexible structures. Modal disparity is generated in a structure by the application of external forces that vary the stiffness of the structure. When the forces are switched on and off and, as a result, the structure is switched between two stiffness states, modal disparity results in vibration energy being transferred from a set of not-controlled modes to a set of controlled modes. This allows the vibration of the structure to be completely attenuated by removing energy only from a small set of controlled modes. A topology optimization problem determines the best locations for application of the external forces. Simulation results are presented to demonstrate control of vibration exploiting modal disparity in two three-dimensional (3D) frame structures.
An Instant Center Approach Toward the Conceptual Design of Compliant Mechanisms
Authors: Kim Charles J. , Kota Sridhar , Moon Yong-Mo
Published: March 2006

As with conventional mechanisms, the conceptual design of compliant mechanisms is a blend of art and science. It is generally performed using one of two methods: topology optimization or the pseudo-rigid-body model. In this paper, we present a new conceptual design methodology which utilizes a building block approach for compliant mechanisms performing displacement amplification/attenuation. This approach provides an interactive, intuitive, and systematic methodology for generating initial compliant mechanism designs. The instant center is used as a tool to construct the building blocks. The compliant four-bar building block and the compliant dyad building block are presented as base mechanisms for the conceptual design. It is found that it is always possible to obtain a solution for the geometric advantage problem with an appropriate combination of these building blocks. In a building block synthesis, a problem is first evaluated to determine if any known building blocks can satisfy the design specifications. If there are none, the problem is decomposed to a number of sub-problems which may be solved with the building blocks. In this paper, the problem is decomposed by selecting a point in the design space where the output of the first building block coincides with the second building block. Two quantities are presented as tools to aid in the determination of the mechanism's geometry – (i) an index relating the geometric advantage of individual building blocks to the target geometric advantage and (ii) the error in the geometric advantage predicted by instant centers compared to the calculated value from FEA. These quantities guide the user in the selection of the location of nodes of the mechanism. Determination of specific cross-sectional size is reserved for subsequent optimization. An example problem is provided to demonstrate the methodology's capacity to obtain good initial designs in a straightforward manner. A size and geometry optimization is performed to demonstrate the viability of the design.
Calculation of amplitudes of acoustic normal modes from the reciprocity principle
Authors: Godin Oleg A.
Published: March 2006

Recently, J. D. Achenbach [J. Acoust. Soc. Am. 116, 1481–1487 (2004)] put forward, on heuristic grounds, an elegant technique to calculate amplitudes of guided waves in an elastic solid. The technique is based on application of the reciprocity principle. In this article, the technique is applied to acoustic waveguides. A mathematical justification of the technique is obtained. The technique is extended to enable calculation of excitation coefficients of modes of both discrete and continuous spectra by a given sound source. The results are shown to be identical to those derived with the traditional methods that rely on integral transforms.
Sensitivity to isolated and concurrent intensity and fundamental frequency increments by cochlear implant users under natural listening conditions
Authors: Rogers Cheryl F. , Healy Eric W. , Montgomery Allen A.
Published: March 2006

Sensitivity to acoustic cues in cochlear implant (CI) listening under natural conditions is a potentially complex interaction between a number of simultaneous factors, and may be difficult to predict. In the present study, sensitivity was measured under conditions that approximate those of natural listening. Synthesized words having increases in intensity or fundamental frequency (F0) in a middle stressed syllable were presented in soundfield to normal-hearing listeners and to CI listeners using their everyday speech processors and programming. In contrast to the extremely fine sensitivity to electrical current observed when direct stimulation of single electrodes is employed, difference limens (DLs) for intensity were larger for the CI listeners by a factor of 2.4. In accord with previous work, F0 DLs were larger by almost one order of magnitude. In a second experiment, it was found that the presence of concurrent intensity and F0 increments reduced the mean DL to half that of either cue alone for both groups of subjects, indicating that both groups combine concurrent cues with equal success. Although sensitivity to either cue in isolation was not related to word recognition in CI users, the listeners having lower combined-cue thresholds produced better word recognition scores.
Curle’s equation and acoustic scattering by a sphere
Authors: Davis Anthony M. J. , Nagem Raymond J.
Published: March 2006

Recent papers have initiated interesting comparisons between aeroacoustic theory and the results of acoustic scattering problems. In this paper, we consider some aspects of these comparisons for acoustic scattering by a sphere. We give a derivation of Curle’s equation for a specific class of linear acoustic scattering problems, and, in response to previous claims to the contrary, give an explicit confirmation of Curle’s equation for plane wave scattering by a stationary rigid sphere of arbitrary size in an inviscid fluid. We construct the complete solution for scattering by a rigid sphere in a viscous fluid, and show that the neglect of viscous terms in Curle’s equation yields an incomplete prediction of the far field dipole pressure. We also consider the null field solution of the sphere scattering problem, and give its extension to the vorticity modes associated with viscosity. Finally, we construct a solution for an elastic sphere in a viscous fluid, and show that the rigid sphere/null field solution is recovered from the limit of infinite longitudinal and shear wave speeds in the elastic solid.
Bayesian analysis of polyphonic western tonal music
Authors: Davy Manuel , Godsill Simon , Idier Jérôme
Published: March 2006

This paper deals with the computational analysis of musical audio from recorded audio waveforms. This general problem includes, as subtasks, music transcription, extraction of musical pitch, dynamics, timbre, instrument identity, and source separation. Analysis of real musical signals is a highly ill-posed task which is made complicated by the presence of transient sounds, background interference, or the complex structure of musical pitches in the time-frequency domain. This paper focuses on models and algorithms for computer transcription of multiple musical pitches in audio, elaborated from previous work by two of the authors. The audio data are supposedly presegmented into fixed pitch regimes such as individual chords. The models presented apply to pitched (tonal) music and are formulated via a Gabor representation of nonstationary signals. A Bayesian probabilistic structure is employed for representation of prior information about the parameters of the notes. This paper introduces a numerical Bayesian inference strategy for estimation of the pitches and other parameters of the waveform. The improved algorithm is much quicker and makes the approach feasible in realistic situations. Results are presented for estimation of a known number of notes present in randomly generated note clusters from a real musical instrument database.
Monaural speech segregation using synthetic speech signals
Authors: Brungart Douglas S. , Iyer Nandini , Simpson Brian D.
Published: March 2006

When listening to natural speech, listeners are fairly adept at using cues such as pitch, vocal tract length, prosody, and level differences to extract a target speech signal from an interfering speech masker. However, little is known about the cues that listeners might use to segregate synthetic speech signals that retain the intelligibility characteristics of speech but lack many of the features that listeners normally use to segregate competing talkers. In this experiment, intelligibility was measured in a diotic listening task that required the segregation of two simultaneously presented synthetic sentences. Three types of synthetic signals were created: (1) sine-wave speech (SWS); (2) modulated noise-band speech (MNB); and (3) modulated sine-band speech (MSB). The listeners performed worse for all three types of synthetic signals than they did with natural speech signals, particularly at low signal-to-noise ratio (SNR) values. Of the three synthetic signals, the results indicate that SWS signals preserve more of the voice characteristics used for speech segregation than MNB and MSB signals. These findings have implications for cochlear implant users, who rely on signals very similar to MNB speech and thus are likely to have difficulty understanding speech in cocktail-party listening environments.
Synchronization of organ pipes: experimental observations and modeling
Authors: Abel M. , Bergweiler S. , Gerhard-Multhaupt R.
Published: March 2006

We report measurements on the synchronization properties of organ pipes. First, we investigate influence of an external acoustical signal from a loudspeaker on the sound of an organ pipe. Second, the mutual influence of two pipes with different pitch is analyzed. In analogy to the externally driven, or mutually coupled self-sustained oscillators, one observes a frequency locking, which can be explained by synchronization theory. Further, we measure the dependence of the frequency of the signals emitted by two mutually detuned pipes with varying distance between the pipes. The spectrum shows a broad “hump” structure, not found for coupled oscillators. This indicates a complex coupling of the two organ pipes leading to nonlinear beat phenomena.
Stimulus variability and the phonetic relevance hypothesis: Effects of variability in speaking style, fundamental frequency, and speaking rate on spoken word identification
Authors: Sommers Mitchell S. , Barcroft Joe
Published: March 2006

Three experiments were conducted to examine the effects of trial-to-trial variations in speaking style, fundamental frequency, and speaking rate on identification of spoken words. In addition, the experiments investigated whether any effects of stimulus variability would be modulated by phonetic confusability (i.e., lexical difficulty). In Experiment 1, trial-to-trial variations in speaking style reduced the overall identification performance compared with conditions containing no speaking-style variability. In addition, the effects of variability were greater for phonetically confusable words than for phonetically distinct words. In Experiment 2, variations in fundamental frequency were found to have no significant effects on spoken word identification and did not interact with lexical difficulty. In Experiment 3, two different methods for varying speaking rate were found to have equivalent negative effects on spoken word recognition and similar interactions with lexical difficulty. Overall, the findings are consistent with a phonetic-relevance hypothesis, in which accommodating sources of acoustic-phonetic variability that affect phonetically relevant properties of speech signals can impair spoken word identification. In contrast, variability in parameters of the speech signal that do not affect phonetically relevant properties are not expected to affect overall identification performance. Implications of these findings for the nature and development of lexical representations are discussed.
Mode-matching without root-finding: Application to a dissipative silencer
Authors: Lawrie Jane B. , Kirby Ray
Published: March 2006

This article presents an analytic mode-matching approach suitable for modelling the propagation of sound in a two-dimensional, three-part, ducting system. The approach avoids the need to find roots of the characteristic equation for the middle section of the duct (the component) and is readily applicable to a broad class of problems. It is demonstrated that the system of equations, derived via analytic mode-matching, exhibits certain features which ensure that they can be recast into a form that is independent of the roots of the characteristic equation for the component. The precise details of the component are irrelevant to the procedure; it is required only that there exists an orthogonality relation, or similar, for the eigenmodes corresponding to the propagating wave forms in this region. The method is applied here to a simple problem involving acoustic transmission through a dissipative silencer of the type commonly found in heating ventilation and air-conditioning ducts. With reference to this example, the silencer transmission loss is computed, and the power balance for the silencer is investigated and is shown to be an identity that is necessarily satisfied by the system of equations, regardless of the level of truncation.
Temporal processing deficits in the pre-senescent auditory system
Authors: Grose John H. , Hall Joseph W. , Buss Emily
Published: March 2006

This study tested the hypothesis that temporal processing deficits are evident in the pre-senescent (middle-aged) auditory system for listening tasks that involve brief stimuli, across-frequency-channel processing, and/or significant processing loads. A gap duration discrimination (GDD) task was employed that used either fixed-duration gap markers (experiment 1) or random-duration markers (experiment 2). Independent variables included standard gap duration (0, 35, and 250ms), marker frequency (within- and across-frequency), and task complexity. A total of 18 young and 23 middle-aged listeners with normal hearing participated in the GDD experiments. Middle age was defined operationally as 40–55years of age. The results indicated that middle-aged listeners performed more poorly than the young listeners in general, and that this deficit was sometimes, but not always, exacerbated by increases in task complexity. A third experiment employed a categorical perception task that measured the gap duration associated with a perceptual boundary. The results from 12 young and 12 middle-aged listeners with normal hearing indicated that the categorical boundary was associated with shorter gaps in the young listeners. The results of these experiments indicate that temporal processing deficits can be observed relatively early in the aging process, and are evident in middle age.
Elastic wave propagation in sinusoidally corrugated waveguides
Authors: Banerjee Sourav , Kundu Tribikram
Published: March 2006

The ultrasonic wave propagation in sinusoidally corrugated waveguides is studied in this paper. Periodically corrugated waveguides are gaining popularity in the field of vibration control and for designing structures with desired acoustic band gaps. Currently only numerical method (Boundary Element Method or Finite Element Method) based packages (e.g., PZFlex) are in principle capable of modeling ultrasonic fields in complex structures with rapid change of curvatures at the interfaces and boundaries but no analyses have been reported. However, the packages are very CPU intensive; it requires a huge amount of computation memory and time for its execution. In this paper a new semi-analytical technique called Distributed Point Source Method (DPSM) is used to model the ultrasonic field in sinusoidally corrugated waveguides immersed in water where the interface curvature changes rapidly. DPSM results are compared with analytical solutions. It is found that when a narrow ultrasonic beam hits the corrugation peaks at an angle, the wave propagates in the backward direction in waveguides with high corrugation depth. However, in waveguides with small corrugation the wave propagates in the forward direction. The forward and backward propagation phenomenon is found to be independent of the signal frequency and depends on the degree of corrugation.
Electropalatographic, acoustic, and perceptual data on adaptation to a palatal perturbation
Authors: Aasland Wendi A. , Baum Shari R. , McFarland David H.
Published: March 2006

Exploring the compensatory responses of the speech production system to perturbation has provided valuable insights into speech motor control. The present experiment was conducted to examine compensation for one such perturbation—a palatal perturbation in the production of the fricative /s/. Subjects wore a specially designed electropalatographic (EPG) appliance with a buildup of acrylic over the alveolar ridge as well as a normal EPG palate. In this way, compensatory tongue positioning could be assessed during a period of target specific and intense practice and compared to nonperturbed conditions. Electropalatographic, acoustic, and perceptual analyses of productions of /asa/ elicited from nine speakers over the course of a one-hour practice period were conducted. Acoustic and perceptual results confirmed earlier findings, which showed improvement in production with a thick artificial palate in place over the practice period; the EPG data showed overall increased maximum contact as well as increased medial and posterior contact for speakers with the thick palate in place, but little change over time. Negative aftereffects were observed in the productions with the thin palate, indicating recalibration of sensorimotor processes in the face of the oral-articulatory perturbation. Findings are discussed with regard to the nature of adaptive articulatory skills.
Elastic moduli approximation of higher symmetry for the acoustical properties of an anisotropic material
Authors: Norris Andrew N.
Published: March 2006

The issue of how to define and determine an optimal acoustical fit to a set of anisotropic elastic constants is addressed. The optimal moduli are defined as those which minimize the mean-squared difference in the acoustical tensors between the given moduli and all possible moduli of a chosen higher material symmetry. The solution is shown to be identical to minimizing a Euclidean distance function, or equivalently, projecting the tensor of elastic stiffness onto the appropriate symmetry. This has implications for how to best select anisotropic constants to acoustically model complex materials.
Model-based analysis of dispersion curves using chirplets
Authors: Kuttig Helge , Niethammer Marc , Hurlebaus Stefan , Jacobs Laurence J.
Published: March 2006

Time-frequency representations, like the spectrogram or the scalogram, are widely used to characterize dispersive waves. The resulting energy distributions, however, suffer from the uncertainty principle, which complicates the allocation of energy to individual propagation modes (especially when the dispersion curves of these modes are close to each other in the time-frequency domain). This research applies the chirplet as a tool to analyze dispersive wave signals based on a dispersion model. The chirplet transform, a generalization of both the wavelet and the short-time Fourier transform, enables the extraction of components of a signal with a particular instantaneous frequency and group delay. An adaptive algorithm identifies frequency regions for which quantitative statements can be made about an individual mode’s energy, and employs chirplets (locally adapted to a dispersion curve model) to extract the (proportional) energy distribution of that single mode from a multimode dispersive wave signal. The effectiveness of this algorithm is demonstrated on a multimode synthetic Lamb wave signal for which the ground-truth energy distribution is known for each mode. Finally, the robustness of this algorithm is demonstrated on real, experimentally measured Lamb wave signals by an adaption of a correlation technique developed in previous research.
Mean field of a low-frequency sound wave propagating in a fluctuating ocean
Authors: Voronovich Alexander G. , Ostashev Vladimir E.
Published: March 2006

Statistical characteristics of low-frequency sound waves propagating over long distances in a fluctuating ocean are important for many practical problems. In this paper, using the theory of multiple scattering, the mean field of a low-frequency sound wave was analytically calculated. In these calculations, the ratio of the sound wavelength and the scale of random inhomogeneities can be arbitrary. Furthermore, the correlation function of inhomogeneities is expressed in terms of a modal spectrum (e.g., internal waves modes). The obtained mean sound field is expressed as a sum of normal modes that attenuate exponentially. It is shown that the extinction coefficients of the modes are linearly related to the spectrum of random inhomogeneities in the ocean. Measurements of the extinction coefficients can therefore be used for retrieving this spectrum. The mean sound field is calculated for both 3D and 2D geometries of sound propagation. The results obtained can be used to study the range of applicability of the 2D propagation model.
Auditory temporal resolution in normal-hearing preschool children revealed by word recognition in continuous and interrupted noise
Authors: Stuart Andrew , Givens Gregg D. , Walker Letitia J. , Elangovan Saravanan
Published: March 2006

The purpose of this study was to examine temporal resolution in normal-hearing preschool children. Word recognition was evaluated in quiet and in spectrally identical continuous and interrupted noise at signal-to-noise ratios (S/Ns) of 10, 0, and −10dB. Sixteen children 4to5years of age and eight adults participated. Performance decreased with decreasing S/N. At poorer S/Ns, participants demonstrated superior performance or a release from masking in the interrupted noise. Adults performed better than children, yet the release from masking was equivalent. Collectively these findings are consistent with the notion that preschool children suffer from poorer processing efficiency rather than temporal resolution per se.
On phonetic convergence during conversational interaction
Authors: Pardo Jennifer S.
Published: March 2006

Following research that found imitation in single-word shadowing, this study examines the degree to which interacting talkers increase similarity in phonetic repertoire during conversational interaction. Between-talker repetitions of the same lexical items produced in a conversational task were examined for phonetic convergence by asking a separate set of listeners to detect similarity in pronunciation across items in a perceptual task. In general, a listener judged a repeated item spoken by one talker in the task to be more similar to a sample production spoken by the talker’s partner than corresponding pre- and postinteraction utterances. Both the role of a participant in the task and the sex of the pair of talkers affected the degree of convergence. These results suggest that talkers in conversational settings are susceptible to phonetic convergence, which can mark nonlinguistic functions in social discourse and can form the basis for phenomena such as accent change and dialect formation.
Coherence detection: Effects of frequency, frequency uncertainty, and onset∕offset delays
Authors: Huang Rong , Richards Virginia M.
Published: March 2006

The detectability of a sequence of equal-frequency (coherent) tonal components embedded in random, multiburst maskers was evaluated. The masker was comprised of tonal components located in a time-by-frequency spectrogram with eight 30ms time columns and 29 frequency rows ranging logarithmically from 200to5000Hz. The probability that a tone occurred in any one cell of the spectrogram, p, was the independent variable. The signal and masker components were of equal duration and equal level. Using a yes∕no procedure, threshold values of p were estimated for five signal frequencies (220, 445, 1000, 2245, 4490Hz) and when the signal frequency was random. Thresholds were worst for the random-frequency signal and best for the fixed 1000Hz signal. In additional conditions, the value of p was fixed and the signal components were delayed relative to the masker components. A 1ms delay provided better sensitivity (d′ grew from 0.5 to 1) for all but the lowest signal frequency tested. An analysis of no-signal trials revealed that false alarm rates were higher when components falling at the signal frequency were consecutive than when they were distributed across bursts. Thus, coherence rather than total energy at the signal frequency is important for signal detection.
Near-irreversibility in a conservative linear structure with singularity points in its modal density
Authors: Carcaterra A. , Akay A. , Koç I. M.
Published: March 2006

Through two complementary approaches, using modal response and wave propagation, the analyses presented here show the conditions under which a decaying impulse response, or a nearly irreversible energy trapping, takes place in a linear conservative continuous system. The results show that the basic foundation of near-irreversibility or apparent damping rests upon the presence of singularity points in the modal density of dynamic systems or, analogously, in the wave-stopping properties associated with these singularities. To illustrate the concept of apparent damping in detail, a simple undamped beam is modified to introduce a singularity point in its modal density distribution. Simulations show that a suitable application of a compressive axial force to an undamped beam placed on an elastic foundation attenuates its impulse response with time and develops the characteristics of a nearly irreversible energy trap.
Frequency- and level-dependent changes in auditory brainstem responses (ABRs) in developing mice
Authors: Song Lei , McGee JoAnn , Walsh Edward J.
Published: March 2006

The development of the auditory brainstem response was studied to quantitatively assess its dependence on stimulus frequency and level. Responses were not observed to stimuli ⩾16kHz on P12, however, the full range of responsive frequencies included in the study was observed by P14. Response thresholds were high on P12, exceeding 100dB SPL for all stimuli tested. The rate of threshold development increased progressively for stimulus frequencies between ∼2 and 10kHz, with the most rapid changes occurring at frequencies >10kHz. Adultlike thresholds were observed by P18. Response latencies and interpeak intervals matured rapidly over the course of the second and third postnatal weeks and did not achieve adultlike characteristics until after P18. Latencies of higher-order peaks were progressively and sequentially delayed relative to wave I. Wave I amplitudes developed nonmonotonically, growing during the first 24days and stabilizing at adult values by ∼P36. Slopes of wave I amplitude-and latency-level curves were significantly steeper than those of adults during the neonatal period and the outcome of input-output analyses, as well as frequency-specific maturational profiles, support developmental models in which function initially matures in the mid-frequency range and proceeds, simultaneously, in both apical and basal directions.
Polling the effective neighborhoods of spoken words with the verbal transformation effect
Authors: Bashford James A. , Warren Richard M. , Lenz Peter W.
Published: March 2006

Studies of the effects of lexical neighbors upon the recognition of spoken words have generally assumed that the most salient competitors differ by a single phoneme. The present study employs a procedure that induces the listeners to perceive and call out the salient competitors. By presenting a recording of a monosyllable repeated over and over, perceptual adaptation is produced, and perception of the stimulus is replaced by perception of a competitor. Reports from groups of subjects were obtained for monosyllables that vary in their frequency-weighted neighborhood density. The findings are compared with predictions based upon the neighborhood activation model.
Role of Inorganic Polyphosphate in Promoting Ribosomal Protein Degradation by the Lon Protease in
E. coli
Authors: Kuroda Akio , Nomura Kazutaka , Ohtomo Ryo , Kato Junichi , Ikeda Tsukasa , Takiguchi Noboru , Ohtake Hisao , Kornberg Arthur
Published: March 2006

Inorganic polyphosphate (polyP), a polymer of hundreds of phosphate (P
i
) residues, accumulates in
Escherichia coli
in response to stresses, including amino acid starvation. Here we show that the adenosine 5′-triphosphate–dependent protease Lon formed a complex with polyP and degraded most of the ribosomal proteins, including S2, L9, and L13. Purified S2 also bound to polyP and formed a complex with Lon in the presence of polyP. Thus, polyP may promote ribosomal protein degradation by the Lon protease, thereby supplying the amino acids needed to respond to starvation.
Manifesto for a Cytoplasmic Revolution
Authors: Stossel Thomas P.
Published: March 2006

Cells, Gels and the Engines of Life
A New, Unifying Approach to Cell Function. Gerald H. Pollack. Ebner, Seattle, 2001. 319 pp. Paper, $27.95. ISBN 0-9626895-2-1.

Treating cells as polymer gels and stressing the physical chemistry of water and solutes, Pollack offers an accessible, non-mathematical challenge to mainstream approaches to cell biology.
Observation of Quantum Shock Waves Created with Ultra- Compressed Slow Light Pulses in a Bose-Einstein Condensate
Authors: Dutton Zachary , Budde Michael , Slowe Christopher , Hau Lene Vestergaard
Published: March 2006

We have used an extension of our slow light technique to provide a method for inducing small density defects in a Bose-Einstein condensate. These sub- resolution, micrometer-sized defects evolve into large-amplitude sound waves. We present an experimental observation and theoretical investigation of the resulting breakdown of superfluidity, and we observe directly the decay of the narrow density defects into solitons, the onset of the “snake” instability, and the subsequent nucleation of vortices.