bluuebunny/crossref_metadata_2025 huggingface dataset:
An ongoing process of inner negotiation – a Grounded Theory study of self‐management among people living with chronic illness
Authors: Audulv Åsa , Norbergh Karl‐Gustaf , Asplund Kenneth , Hörnsten Åsa
Published: December 2009

Aim.  The aim of this study was to better understand the main concern of self‐management processes among people with chronic illness.

Background.  One aspect of living with chronic illness is self‐management that can reduce the illness impact on daily life and promote future health. Although factors that influence self‐management have been identified in previous research, little attention has been brought to the process of making self‐management decisions. In clinical settings, use of a theory could facilitate patient‐empowering approaches.

Method.  The data collection for this Grounded Theory was mostly conducted in 2006. Data were collected by interviews with 26 adults with a variety of chronic illnesses, including rheumatoid arthritis, diabetes mellitus, inflammatory bowel syndrome, multiple sclerosis, ischaemic heart disease and chronic kidney failure.

Results.  Individuals are conflicted by competing preferences when taking decisions about self‐management. Consequently, the decision‐making process can be understood as an ongoing inner negotiation between different incompatible perspectives, e.g. social needs vs. medical needs. The process of negotiating self‐management starts with the individual’s considering beliefs about health and illness, which make the individual face illness threats and the need for self‐management. Several aspects influence negotiating self‐management namely, assessing effects of self‐management; evaluating own capacity; perceiving normality or stigmatisation; and experiencing support and external resources. The process has been demonstrated in a model.

Conclusions.  The process of negotiating self‐management is an ongoing inner debate rather than a one‐time decision. This opens up new ways of understanding, and communicating with, patients. The described model also links behavioural theories and research findings in a comprehensive understanding.

Relevance to clinical practice.  This model could be applicable as a communication tool for health‐care providers in identifying barriers to, and resources in, self‐management behaviour among individuals with chronic illness.
Is the role of Chlamydia trachomatis underestimated in patients with suspected reactive arthritis?
Authors: OWLIA Mohammad‐Bagher , ELEY Adrian R.
Published: December 2009

Reactive arthritis is usually caused by bacteria of either the enteric or genital tracts. In the genital tract, Chlamydia trachomatis is perhaps the only aetiological agent. In Iran, newer evidence suggests that as C. trachomatis is more commonly found in the general population than was previously believed, its role in reactive arthritis may well be currently overlooked. In this review, as well as emphasizing the potential role of C. trachomatis in reactive arthritis in patients from developing countries, we also make recommendations for further clinical studies to determine its prevalence. Moreover, we also stress the need for standardization of new testing methodologies for C. trachomatis, including the use of new commercial systems in an attempt to determine a truer picture of chlamydial infection in reactive arthritis.
Severe autoimmune hemolytic anemia associated with IgM warm auto‐antibodies in primary Sjögren’s syndrome
Authors: SHINODA Koichiro , TAKI Hirofumi , HOUNOKI Hiroyuki , OGAWA Reina , SUGIYAMA Eiji , TOBE Kazuyuki
Published: December 2009

Primary Sjögren’s syndrome is an autoimmune disorder involving mainly salivary and lachrymal glands. However, many extraglandular symptoms have also been reported. Although leucocytopenia and lymphocytopenia are frequently observed in hematological disorders, autoimmune hemolytic anemia is rarely reported. We experienced a case of primary Sjögren’s syndrome developing severe autoimmune hemolytic anemia. The patient’s red blood cells showed spontaneous agglutination in saline at room temperature, and immunoglobulin M (IgM) was detected on the surface of red blood cells by flow cytometry, indicating that autoimmune hemolytic anemia was caused by warm reactive IgM antibodies. Immediate corticosteroid therapy resulted in a dramatic recovery. We report a first case of severe autoimmune hemolytic anemia caused by warm reactive IgM antibodies in primary Sjögren’s syndrome.
A diagnosis not to be missed: Behcet’s disease as a cause of dilated cardiomyopathy in a young Arab male patient
Authors: AL IZZI Mustafa , EL BUR Mohammed , ARIF Mohammed
Published: December 2009

We report a 33‐year‐old Arab male patient who was thought to have severe idiopathic dilated cardiomyopathy (DCM) associated with complete atrioventricular block for more than 6 years, then was found to possess features suggestive of underlying Behcet’s disease in the form of recurrent oral and genital ulcers, cutaneous folliculitis, superficial thrombophlebitis, pathergism, partially thrombosed portal vein and a positive human leukocyte antigen ‐B51.
Klinefelter’s syndrome and rheumatoid arthritis: report of a case and review of the literature
Authors: AL‐ARFAJ Hussein F.
Published: December 2009

Kilnefelter’s syndrome (KFS) tends to be associated with autoimmune diseases. Although several reports describe association of KFS with different autoimmune diseases, association with rheumatoid arthritis is very rare. We report a case of (KFS) who had seropositive erosive rheumatoid arthritis, and discuss the role of sex hormones/X chromosome in the pathogenesis of disease.
Subsurface damage from helium ions as a function of dose, beam energy, and dose rate
Authors: Livengood Richard , Tan Shida , Greenzweig Yuval , Notte John , McVey Shawn
Published: December 2009

In recent years, helium ion microscopy has produced high resolution images with novel contrast mechanisms. However, when using any charged particle beam, one must consider the potential for sample damage. In this article, the authors will consider helium ion induced damage thresholds as compared to other more traditional charged-particle-beam technologies, as a function of dose, dose rate, and beam energy, and describe potential applications operating regimes.
Optimization of focused ion beam performance
Authors: Hagen C. W. , Kruit P.
Published: December 2009

The authors have analyzed how much current can be obtained in the probe of an optimized two-lens focused ion beam (FIB) system. This becomes relevant, as systems become available that have the potential to image and/or fabricate structures smaller than 10 nm. The probe current versus probe size curves were calculated for a commercial gallium-FIB, the nano-FIB system, and the helium microscope, using partly published, partly estimated system parameters. The current in sub-10 nm probes in the Ga systems turns out to be limited by the reduced brightness of the source and the chromatic aberration of the objective lens. In probes larger than 40 nm the current is limited by the angular current density and the spherical aberration of both lenses. The He system is limited at all probe sizes by the angular current density of the source and the chromatic aberration of both lenses in sub-5 nm probes and the spherical aberration of both lenses at probes larger than 10 nm. As the emission current of the He source is much smaller than that of the Ga source, the statistical Coulomb interactions in the gun lens region do not contribute to the total probe size, as is the case for the Ga systems.
Charged particle nanopatterning
Authors: Platzgummer Elmar , Loeschner Hans
Published: December 2009

Charged particle nanopatterning techniques based on electron and ion multibeam projection techniques are finding increased industrial interest for the fabrication of leading-edge complex masks, nanoimprint templates, and,—using maskless and resistless techniques,—for nanosystem device research and development. A proof-of-concept tool for ion projection multibeam nanopatterning has been realized. Inserting a programable aperture plate system with integrated 0.25μm complementary metal oxide semiconductor electronics, providing switchable beams of 2.5×2.5μm2 size, with 200× ion-optical reduction, 43 000 programmable beams of 12.5nm size were obtained, demonstrating 20nm resolution capability.
Fabrication of high-aspect ratio silicon nanopillars and nanocones using deep reactive ion etching
Authors: Fischer C. , Menezes J. W. , Moshkalev S. A. , Veríssimo C. , Vaz A. R. , Swart J. W.
Published: December 2009

Bosch type processes have been employed to fabricate nanostructured Si surfaces. Nanopillars and nanocones in Si have been fabricated using different techniques for Ni micromasking. Plasma redeposition of Ni was found to be responsible for Si pillar formation with diameters varying in the submicron range. A possibility to produce tilted nanopillars with tilt angles up to as high as 25° has been demonstrated. In other method, previously deposited and annealed thin Ni films were employed. Smaller Ni nanoislands were obtained, and the formation of Si nanocones was demonstrated using longer passivation steps. In this case, reflection coefficients as low as 1.2% were obtained for the optimized etching process time.
Evaluations of the hopping growth characteristics on three-dimensional nanostructure fabrication using focused ion beam
Authors: Kometani Reo , Warisawa Shin’ichi , Ishihara Sunao
Published: December 2009

Hopping growth characteristics were examined to clarify the growth mechanism of three-dimensional nanostructures fabricated using focused-ion-beam chemical-vapor deposition (FIB-CVD). In this study, the gas density distribution of FIB-CVD was examined. As a result, a gas density has a large distribution on the vertical direction. However, the growth mechanism of a hopping nanostructure could not be explained completely. Therefore, sequential scanning ion microscope images of a hopping growth process were captured. It was found that the gap distance between the growth edges of the upper and lower structures changed during the hopping structure growth. This indicated the positional relationship between the Ga+ FIB and the growth structure. The change in this relationship induced the formation of a bridge bent structure and the change in the growth direction of the upper structure. To confirm the cause of the lower structure growth, the relationship between the Ga+ penetration depth into diamondlike carbon and the thickness of the upper structure was examined. The deposition onto the substrate was caused by the Ga+ FIB’s tail (directly irradiated beam). A hopping growth structure was formed by the repetition of these growth processes.
Electron postgrowth irradiation of platinum-containing nanostructures grown by electron-beam-induced deposition from Pt(PF3)4
Authors: Botman A. , Hagen C. W. , Li J. , Thiel B. L. , Dunn K. A. , Mulders J. J. L. , Randolph S. , Toth M.
Published: December 2009

The material grown in a scanning electron microscope by electron beam-induced deposition (EBID) using Pt(PF3)4 precursor is shown to be electron beam sensitive. The effects of deposition time and postgrowth electron irradiation on the microstructure and resistivity of the deposits were assessed by transmission electron microscopy, selected area diffraction, and four-point probe resistivity measurements. The microstructure, notably the platinum nanocrystallite grain size, is shown to evolve with electron fluence in a controllable manner. The resistivity was observed to decrease as a result of postgrowth electron irradiation, with the lowest observed value of 215±15μΩcm. The authors demonstrate that electron beam-induced changes in microstructure can be caused using electron fluences similar to those used during the course of EBID and suggest that the observed effects can be used to tailor the microstructure and functionality of deposits grown by EBID in situ without breaking vacuum.
High rate gas dosing for tip based nanofabrication processes
Authors: Kanouff M. P. , Randall J. N. , Nadesalingham M. , Kirk W. P. , Wallace R. M.
Published: December 2009

Tip based nanofabrication (TBN) processes promise unprecedented degrees of control and precision for the manufacture of nanostructured materials and devices. These processes use atomic force microscope or scanning tunneling microscope tips to create localized electric fields, electron beams, and other catalyzing conditions to control and detect the position, size, dimension, and orientation of nanostructures. Tip based approaches have deposited metals, oxides, and organic molecules to name a few. Often, a gas phase precursor is required to provide the material for the deposit. The TBN conditions for gas dosing are unique compared to other fabrication processes, e.g., chemical vapor deposition. The manufacture of precision nanostructures requires a contamination-free environment, and hence ultrahigh vacuum conditions must be maintained in the chamber. This can cause a gas jet from a doser to spread into a wide fan resulting in a small precursor flux with a broad distribution. This makes it difficult to meet the large fabrication rates desired for TBN. Ideally, gas dosing would promote rapid deposition rates while limiting the chamber pressure by creating a focused gas jet that is restricted to the intended fabrication area. Continuum gas dynamics and direct simulation Monte Carlo calculations were used to study the effect of design and operational parameters on gas doser performance. The source pressure, doser design, and operating conditions are shown to affect the flux distribution at the substrate. The calculated results are compared to experimental measurements. A novel gas doser design was identified and its performance predicted.
Laser print patterning of planar spiral inductors and interdigitated capacitors
Authors: Klejwa N. , Misra R. , Provine J. , Howe R. T. , Klejwa S. J.
Published: December 2009

This article describes direct laser printing of thin-film polymer onto rigid substrates for use as an etch mask or liftoff layer in patterning on-chip electrical components. Using this technique, the authors fabricated planar spiral inductors of 12×12mm2 with 2.5–5.5 turns producing series inductance Ls=80–180nH as well as planar interdigitated capacitors of 10×10mm2 with two to nine fingers producing series capacitance Cs=100–1600nF. This technique is a low cost, low temperature, rapid turn around, maskless, resist-free means of patterning device features as small as 130μm.
Generating integrated-circuit patterns via cutting and stitching of gratings
Authors: Zhao Lin , Xuan Yi , Qi Minghao
Published: December 2009

Integrated-circuit patterns, such as those of transistor gates, usually consist of multivertex paths whose line segments are along two orthogonal directions. Such patterns are sometimes called “Manhattan structures” and are typically designed to achieve the highest packing density with a given linewidth. Owing to their arbitrary shapes, these patterns are predominantly generated via electron-beam lithography, a serial process which is inherently slow compared to parallel processes. Moreover, throughput is further reduced with the necessity of proximity correction in electron-beam lithography. On the other hand, interference lithography is a low-cost, parallel process that can achieve small linewidths and pitches, yet the achievable patterns are limited to gratings or other periodic structures. Here the authors propose to synthesize arbitrary Manhattan structures from regular structures such as gratings via cutting and stitching. They demonstrate the cutting and stitching of large-area, highly smooth gratings formed by interference lithography and orientation-dependent etch of silicon. Our method could significantly reduce the writing time in electron-beam lithography for pattern generation and requires no proximity correction.
Direct write of optical waveguides on chalcogenide thin films using electron beams
Authors: Hoffman G. B. , Zhou W. , Sooryakumar R. , Reano R. M.
Published: December 2009

Electron beam induced reliefs in Ge0.2Se0.8 thin films deposited by pulsed laser deposition on oxide coated silicon wafers are fabricated for the direct write of rib optical waveguides at telecommunication wavelengths. The physical dimensions of the reliefs are experimentally determined as a function of electron beam exposure conditions. Relief heights in excess of three times the initial film thickness are achieved. The lateral translation of the thin film material is observed to be of the order of tens of microns for relatively slow beam scan rates. Numerical simulations based on a full-wave finite element eigenmode analysis support the existence of single mode guided waves. The surface roughness of the optical waveguides, dominated by the pulse laser deposition process, is reduced to approximately 1nm by planarization of the thin film, via thermal embossing, prior to electron beam exposure. A bidirectional writing scheme is implemented to remove variations in relief heights observed at waveguide terminations. Nonuniform electron beam exposures are used to demonstrate three-dimensional waveguide tapers useful for the realization of fiber-to-waveguide optical transitions.
Inspection method for contact/via-holes using a low-energy electron microcolumn
Authors: Kim Y. C. , Kim D. W. , Ahn S. , Oh T. S. , Kim J. B. , Roh Y. S. , Hasko D. G. , Kim H. S.
Published: December 2009

Further scaling of semiconductor devices is limited by the increasing number of defects in contact- or via-holes that occur as the aspect ratio increases. Inspection of the bottom of a via-hole, to check for complete clearance, becomes problematical for aspect ratios greater than about 5. Such an inspection is extremely important to circuit yield, as any residue in the hole will result in device failure. At present, holes are inspected from the top using conventional scanning electron microscope imaging, but this method is ineffective for hole diameters <100nm. Smaller holes need to be observed by this method in cross section to ensure clearance; a method that is not suitable for manufacturing. To resolve the problem, the authors propose a novel method of inspecting small contact/via-holes using a low voltage microcolumn, where the image formed by the specimen current is very sensitive to the presence of residues in the hole. Simply when the beam is place over the hole, the presence of a residual thin film at the bottom of the hole can be reliably detected simply by measuring the sample current due to a stationary electron probe. This inspection method is been demonstrated with a patterned SiO2 layer on a Si substrate. Preliminary results for currents measured from this sample show that the Si substrate and the SiO2 residual layer are clearly distinguished. The inspection method and test results for a submicrometer pattern will be discussed in detail.
A discrete impulsive model for random heating and Brownian motion
Authors: Ramshaw John D.
Published: December 2009

The energy of a mechanical system subjected to a random force with zero mean increases irreversibly and diverges with time in the absence of friction or dissipation. This random heating effect is usually encountered in phenomenological theories formulated in terms of stochastic differential equations, the epitome of which is the Langevin equation of Brownian motion. We discuss a simple discrete impulsive model that captures the essence of random heating and Brownian motion. The model may be regarded as a discrete analog of the Langevin equation, although it is developed ab initio. Its analysis requires only simple algebraic manipulations and elementary averaging concepts, but no stochastic differential equations (or even calculus). The irreversibility in the model is shown to be a consequence of a natural causal stochastic condition that is closely analogous to Boltzmann’s molecular chaos hypothesis in the kinetic theory of gases. The model provides a simple introduction to several ostensibly more advanced topics, including random heating, molecular chaos, irreversibility, Brownian motion, the Langevin equation, and fluctuation-dissipation theorems.
The momentum distribution of a one-dimensional ideal gas of N atoms
Authors: Boozer A. D.
Published: December 2009

We calculate the average momentum distribution and the average deviation from this distribution for a one-dimensional ideal gas of N atoms. The calculation is performed using analytical and numerical methods, and the results obtained using the two methods are compared. We use these results to show that in the limit of large N, almost all the possible microstates of an ideal gas have momentum distributions that are very close to the Maxwell distribution. We discuss the significance of this fact for understanding why an ideal gas approaches thermal equilibrium.
The longitude problem from the 1700s to today: An international and general education physics course
Authors: Bensky T. J.
Published: December 2009

For instructors wishing to use physics as part of an international or general education course, the framework for a course based on the “longitude problem” from the 1700s is described. The longitude problem is teeming with basic principles of physics and astronomy, which makes it ideal for a non-science-major-based college-level course. This paper summarizes the longitude problem in the context of conceptual physics and astronomy and outlines an appropriate curriculum. Specifics on teaching such a course in London, as part of an international studies program, are discussed.
Intonation and compensation of fretted string instruments
Authors: Varieschi Gabriele U. , Gower Christina M.
Published: December 2009

We discuss theoretical and physical models that are useful for analyzing the intonation of musical instruments such as guitars and mandolins and can be used to improve the tuning on these instruments. The placement of frets on the fingerboard is designed according to mathematical rules and the assumption of an ideal string. The analysis becomes more complicated when we include the effects of deformation of the string and inharmonicity due to other string characteristics. As a consequence, perfect intonation of all the notes on the instrument cannot be achieved, but complex compensation procedures can be introduced to minimize the problem. To test the validity of these procedures, we performed extensive measurements using standard monochord sonometers and other acoustical devices, confirming the correctness of our theoretical models. These experimental activities can be integrated into acoustics courses and laboratories and can become a more advanced version of basic experiments with monochords and sonometers.
Fabrication of slits for Young’s experiment using graphic arts films
Authors: Lee Changsug , Shin Kwangmoon , Lee Sungmuk , Lee Jaebong
Published: December 2009

Diffraction and interference experiments with narrow slits play an important role in helping students understand many properties of light. Of special interest is the diffraction experiment suggested by PSSC physics. Slits made with two razors can have large errors, and commercial slits may not offer the variety of slit widths needed to obtain specific diffraction patterns. We show how slits can be made more easily and inexpensively with graphic arts films with errors of less than 5%.
Rayleigh scattering revisited: From gases to crystals
Authors: Rojo Alberto G. , Berman P. R.
Published: December 2009

The intensity of Rayleigh scattering is proportional to the number of scatterers in a dilute gas. In contrast, for liquids or solids at low temperatures, any lateral Rayleigh scattering can be suppressed significantly. Microscopically, it is not obvious why the lateral Rayleigh scattering is diminished as the density in the medium increases. We use simple exactly solvable models to show that the suppression of Rayleigh scattering is proportional to the ratio of the interparticle correlation length to the interparticle distance. The wavelength of the scattered radiation is much larger than both these quantities in many cases of interest and does not play an explicit role in the suppression of lateral Rayleigh scattering.
What Bell proved: A reply to Blaylock
Authors: Maudlin Tim
Published: December 2009

Blaylock argues that the derivation of Bell’s inequality requires a hidden assumption, counterfactual definiteness, of which Bell was unaware. A careful analysis of Bell’s argument shows that Bell presupposes only locality and the predictions of standard quantum mechanics. Counterfactual definiteness, insofar as it is required, is derived in the course of the argument rather than presumed. Bell’s theorem has no direct bearing on the many worlds interpretation not because that interpretation denies counterfactual definiteness but because it does not recover the predictions of standard quantum mechanics.
Modeling excitable systems: Reentrant tachycardia
Authors: Lancaster Jarrett L. , Hellen Edward H. , Leise Esther M.
Published: December 2009

Excitable membranes are an important type of nonlinear dynamical system, and their study can be used to provide a connection between physical and biological circuits. We discuss two models of excitable membranes important in cardiac and neural tissues. One model is based on the Fitzhugh–Nagumo equations, and the other is based on a three-transistor excitable circuit. We construct a circuit that simulates reentrant tachycardia and its treatment by surgical ablation. This project is appropriate for advanced undergraduates as a laboratory capstone project or as a senior thesis or honors project and can also be a collaborative project, with one student responsible for the computational predictions and another for the circuit construction and measurements.
A simple model for Carnot heat engines
Authors: Arnaud Jacques , Chusseau Laurent , Philippe Fabrice
Published: December 2009

We discuss a model consisting of two reservoirs, each with N possible ball locations, at heights Eh and El<Eh in a gravitational field. The two reservoirs contain nh and nl weight 1 balls. Empty locations are treated as weight 0 balls. The reservoirs are shaken so that all possible ball configurations are equally likely to occur. A cycle consists of exchanging a ball randomly chosen from the higher reservoir and a ball randomly chosen from the lower reservoir. We relate this system to a heat engine and show that the efficiency, which is defined as the ratio of the average work produced to the average energy lost by the higher reservoir, is 1−El/Eh. When nl is comparable to nh, the efficiency is found to coincide with the maximum efficiency 1−Tl/Th, where the temperatures Tl and Th are defined from a simple expression for the entropy. We also discuss the evaluation of fluctuations and the history of the Carnot discovery.
Using a signal cancellation technique involving impulse response to assess directivity of hearing aids
Authors: Wu Yu-Hsiang , Bentler Ruth A.
Published: December 2009

The directional microphone systems of modern digital hearing aids are capable of changing their spatial directivity pattern and/or the microphone mode in response to changes in the properties of environmental sounds. These adaptive/automatic features make measurement of a hearing aid’s directivity in a given test environment very difficult. Assessing the directivity of such systems requires a signal that can record the system’s response while not changing the system’s directivity. This paper proposes a method using a signal cancellation technique involving impulse responses to acoustically assess a hearing aid’s directivity (referred to as the IR method). The impulse is presumed to be undetectable to the adaptive/automatic system because it contains little energy and a short response could be recorded before the system actually reacts. In the current study, the IR method was evaluated by testing five adaptive/automatic directional hearing aids in noise of various intensities. The results revealed that the IR method was an accurate and repeatable way to assess slow-acting directional systems in noise of varying intensities and fast-acting systems in noise of high intensities.
Effect of ultrasound contrast agent dose on the duration of focused-ultrasound-induced blood-brain barrier disruption
Authors: Yang Feng-Yi , Liu Shing-Hwa , Ho Feng-Ming , Chang Chi-Hong
Published: December 2009

It has been shown that focused ultrasound (FUS) is capable of noninvasive and reversible disruption of the blood-brain barrier (BBB) at target regions when applied in the presence of ultrasound contrast agent (UCA). The purpose of this study was to investigate the effects of UCA dose on the reversibility of BBB disruption induced by the same acoustical power of FUS. Sonications were applied at an ultrasound frequency of 1MHz with a 5% duty cycle and a repetition frequency of 1Hz. The brains of 66 male Sprague-Dawley rats were subjected to sonications with three doses of UCA. BBB integrity was evaluated via femoral vein injection of Evans Blue (EB) while the rats were anesthetized. The relationship between UCA dose and the region of EB extravasation was evaluated at an acoustic power of 1.43W. The BBB disruption, as indexed by the amount of EB extravasation, was the largest immediately after the sonications. The quantity of Evans blue extravasation decreased as a function of time at various UCA doses. This study demonstrates that the appropriate dose of UCA not only enhance the BBB opening but also effectively aid in controlling the duration of BBB disruption.
Analysis of acoustic reduction using spectral similarity measures
Authors: Hämäläinen Annika , Gubian Michele , ten Bosch Louis , Boves Lou
Published: December 2009

Articulatory and acoustic reduction can manifest itself in the temporal and spectral domains. This study introduces a measure of spectral reduction, which is based on the speech decoding techniques commonly used in automatic speech recognizers. Using data for four frequent Dutch affixes from a large corpus of spontaneous face-to-face conversations, it builds on an earlier study examining the effects of lexical frequency on durational reduction in spoken Dutch [Pluymaekers, M. et al. (2005). J. Acoust. Soc. Am. 118, 2561–2569], and compares the proposed measure of spectral reduction with duration as a measure of reduction. The results suggest that the spectral reduction scores capture other aspects of reduction than duration. While duration can—albeit to a moderate degree—be predicted by a number of linguistically motivated variables (such as word frequency, segmental context, and speech rate), the spectral reduction scores cannot. This suggests that the spectral reduction scores capture information that is not directly accounted for by the linguistically motivated variables. The results also show that the spectral reduction scores are able to predict a substantial amount of the variation in duration that the linguistically motivated variables do not account for.
Amplification of interaural level differences improves sound localization in acoustic simulations of bimodal hearing
Authors: Francart Tom , Van den Bogaert Tim , Moonen Marc , Wouters Jan
Published: December 2009

Users of a cochlear implant and contralateral hearing aid are sensitive to interaural level differences (ILDs). However, when using their clinical devices, most of these subjects cannot use ILD cues for localization in the horizontal plane. This is partly due to a lack of high-frequency residual hearing in the acoustically stimulated ear. Using acoustic simulations of a cochlear implant and hearing loss, it is shown that localization performance can be improved by up to 14° rms error relative to 48° rms error for broadband noise by artificially introducing ILD cues in the low frequencies. The algorithm that was used for ILD introduction is described.
Effects of bandwidth on auditory localization with a noise masker
Authors: Brungart Douglas S. , Simpson Brian D.
Published: December 2009

Although high-frequency content is known to be critically important for the accurate location of isolated sounds, relatively little is known about the importance of high-frequency spectral content for the localization of sounds in the presence of a masker. In this experiment, listeners were asked to identify the location of a pulsed-noise target in the presence of a randomly located continuous noise masker. Both the target and masker were low-pass filtered at one of eight cutoff frequencies ranging from 1to16kHz, and the signal-to-noise ratio was varied from −12to+12dB. The results confirm the importance of high frequencies for the localization of isolated sounds, and show that high-frequency content remains critical in cases where the target sound is masked by a spatially separated masker. In fact, when two sources of the same level are randomly located in space, these results show that a decrease in stimulus bandwidth from 16to12kHz might result in a 30% increase in overall localization error.
A special relation between Young’s modulus, Rayleigh-wave velocity, and Poisson’s ratio
Authors: Malischewsky Peter G. , Tuan Tran Thanh
Published: December 2009

Bayón et al. [(2005). J. Acoust. Soc. Am. 117, 3469–3477] described a method for the determination of Young’s modulus by measuring the Rayleigh-wave velocity and the ellipticity of Rayleigh waves, and found a peculiar almost linear relation between a non-dimensional quantity connecting Young’s modulus, Rayleigh-wave velocity and density, and Poisson’s ratio. The analytical reason for this special behavior remained unclear. It is demonstrated here that this behavior is a simple consequence of the mathematical form of the Rayleigh-wave velocity as a function of Poisson’s ratio. The consequences for auxetic materials (those materials for which Poisson’s ratio is negative) are discussed, as well as the determination of the shear and bulk moduli.
Short-range shock formation and coalescence in numerical simulation of broadband noise propagation
Authors: Shepherd Micah R. , Gee Kent L. , Wochner Mark S.
Published: December 2009

The number of jet and rocket noise studies has increased in recent years as researchers have sought to better understand aeroacoustic source and radiation characteristics. Although jet and rocket noise is finite-amplitude in nature, little is known about the existence of shock formation and coalescence close to the source. A numerical experiment is performed to propagate finite-amplitude noise and determine the extent of the nonlinearity over short distances with spherical spreading. The noise is filtered to have a haystack shape in the frequency domain, as is typical of such sources. The effect of the nonlinearity is compared in both the temporal and frequency domains as a function of distance. Additionally, the number of zero-crossings and overall sound pressure level is compared at several distances. The results indicate that the center frequency plays a particularly important role in the amount of coalescence and spectral redistribution that occurs. The general applicability of these results to actual near-field finite-amplitude jet and rocket noise experiments is also presented.
Adaptive extraction of modulation for cavitation noise
Authors: Bao Fei , Wang Xinlong , Tao Zhiyong , Wang Qingfu , Du Shuanping
Published: December 2009

Modulation analysis is an important issue in target classification and identification for ship-radiated noise. However, the modulated cavitation noise sought for analyzing is always submerged under strong ambient noise and difficult to be separated out. In this paper, an approach is proposed to extract the modulated cavitation noise adaptively by combining empirical mode decomposition and singular value decomposition. The results for both synthetical and practical signals demonstrate the practicability and effectivity of the approach.
Exploiting forward scattering for detecting submerged proud/half-buried unexploded ordnance
Authors: Bucaro J. A. , Houston B. H. , Simpson H. , Dragonette L. R. , Kraus L. , Yoder T.
Published: December 2009

Laboratory underwater bistatic scattering measurements are reported for free, proud, and half-buried unexploded ordnances for 0° and 90° source angles. Forward echoes are larger than backscattered returns, and half burial significantly decreases the latter but not the former. Results agree with analytic predictions borrowed from radar. The forward echo and source signal are separated by measurements made with and without the target, a method not possible in a target search. For this, a method is described that uses knowledge of the source location and the hyperbolic character in time-cross range of the signals received at points along a line.
Masking with interaurally “double-delayed” stimuli: The range of internal delays in the human brain
Authors: Marquardt Torsten , McAlpine David
Published: December 2009

Is binaural processing in humans different to that of other mammals? While psychophysical data suggest that the range of internal delays necessary for processing interaural time differences is at least ±3 ms, physiological data from small mammals indicate a more limited range. This study demonstrates that binaural detection is impeded by reduced interaural coherence in auditory channels remote from the signal frequency, in accordance with the wider critical bandwidths reported for binaural processing. This explains previous psychophysical data without requiring long internal delays. The current psychophysical data support the view that human binaural processing is similar to that of other mammals.
Sound propagation in and low frequency noise absorption by helium-filled porous material
Authors: Choy Y. S. , Huang Lixi , Wang Chunqi
Published: December 2009

Low-frequency noise is difficult to deal with by traditional porous material due to its inherent high acoustic impedance. This study seeks to extend the effective range of sound absorption to lower frequencies by filling a low density gas, such as helium, in the porous material. Compared with conventional air-filled absorption material, the helium-filled porous material has a much reduced characteristic impedance; hence, a good impedance matching with pure air becomes more feasible at low frequencies. The acoustic properties of a series of helium-filled porous materials are investigated with a specially designed test rig. The characteristic of the sound propagation in a helium-filled porous material is established and validated experimentally. Based on the measured acoustic properties, the sound absorption performance of a helium-filled absorber (HA) of finite thickness is studied numerically as well as experimentally. For a random incidence field, the HA is found to perform much better than the air-filled absorber at low frequencies. The main advantage of HA lies in the middle range of oblique incidence angles where wave refraction in the absorber enhances sound absorption. The advantage of HA as duct lining is demonstrated both numerically and experimentally.
Automatic detection of the second subglottal resonance and its application to speaker normalization
Authors: Wang Shizhen , Lulich Steven M. , Alwan Abeer
Published: December 2009

Speaker normalization typically focuses on inter-speaker variabilities of the supraglottal (vocal tract) resonances, which constitute a major cause of spectral mismatch. Recent studies have shown that the subglottal airways also affect spectral properties of speech sounds, and promising results were reported using the subglottal resonances for speaker normalization. This paper proposes a reliable algorithm to automatically estimate the second subglottal resonance (Sg2) from speech signals. The algorithm is calibrated on children’s speech data with simultaneous accelerometer recordings from which Sg2 frequencies can be directly measured. A cross-language study with bilingual Spanish-English children is performed to investigate whether Sg2 frequencies are independent of speech content and language. The study verifies that Sg2 is approximately constant for a given speaker and thus can be a good candidate for limited data speaker normalization and cross-language adaptation. A speaker normalization method using Sg2 is then presented. This method is computationally more efficient than maximum-likelihood based vocal tract length normalization (VTLN), with performance better than VTLN for limited adaptation data and cross-language adaptation. Experimental results confirm that this method performs well in a variety of testing conditions and tasks.
Effects of electrode separation between speech and noise signals on consonant identification in cochlear implants
Authors: Kwon Bom Jun
Published: December 2009

The aim of the present study was to examine cochlear implant (CI) users’ perceptual segregation of speech from background noise with differing degrees of electrode separation between speech and noise. Eleven users of the nucleus CI system were tested on consonant identification using an experimental processing scheme called “multi-stream processing” in which speech and noise stimuli were processed separately and interleaved. Speech was presented to either ten (every other electrode) or six electrodes (every fourth electrode). Noise was routed to either the same (the “overlapped” condition) or a different set of electrodes (the “interlaced” condition), where speech and noise electrodes were separated by one- and two-electrode spacings for ten- and six-electrode presentations, respectively. Results indicated a small but significant improvement in consonant recognition (5%–10%) in the interlaced condition with a two-electrode spacing (approximately 1.1 mm) in two subjects. It appears that the results were influenced by peripheral channel interactions, partially accounting for individual variability. Although the overall effect was small and observed from a small number of subjects, the present study demonstrated that CI users’ performance on segregating the target from the background might be improved if these sounds were presented with sufficient peripheral separation.
Transmission characteristics of a tee-junction in a rectangular duct at higher-order modes
Authors: Lau Siu-Kit , Leung Kwan-Hao
Published: December 2009

Numerical and experimental studies were undertaken to characterize the noise transmission and scattering properties in higher-order modes across the tee-junction of a rectangular duct used in ventilation and air-conditioning systems. To measure these properties, a formulation of a transmission matrix based on the transfer function and a two-microphone method was devised. The measurement of modal sound transmission and scattering coefficients is demonstrated for a duct element in a rectangular duct. The results of numerical simulations were verified by experiments. The results show that sound transmissions of fundamental mode and higher-order modes across the main duct are high at the eigen-frequencies of the main duct and sidebranch. Weak modal coupling of the branch-modes and the traveling wave in the main duct is observed at or very close to the eigen-frequencies of the sidebranch, which shifts excitation of the higher-order branch-modes at higher frequencies. A decrease in sound transmission and increase in sound scattering into higher-order modes occur with excitation of the axial branch-mode. Excitation of the longitudinal branch-mode due to branch-end reflection also results in lower sound transmission of higher-order modes across the junction along the main duct.
Influence of the filling fluid on frequency-dependent velocity and attenuation in cancellous bones between 0.35 and 2.5 MHz
Authors: Pakula Michal , Padilla Frederic , Laugier Pascal
Published: December 2009

The paper is focused on experiments on human cancellous bones filled with different fluids with the goal of evaluating their contribution to velocity dispersion, absorption, and scattering mechanisms. The specimens were measured first filled with marrow and subsequently, after marrow removal, with water and alcohol. No significant influence of the fluids was evidenced on the attenuation coefficient. Given the absence of impact of viscosity of the saturating fluid, the authors hypothesized that the source of attenuation is associated with viscoelastic absorption in the solid trabeculae and with scattering. Alteration of scattering obtained by changing the acoustic impedance mismatch between the fluid (alcohol vs water) and the trabeculae was reflected neither in the attenuation nor in its slope. This led the authors to suggest that longitudinal-to-shear scattering together with absorption in the solid phase are candidates as main sources for the attenuation. The differences in velocity values indicate that the elastic properties of the fluid are main determinants of the phase velocity. This finding is particularly significant in the context of /in vivo/ measurements, because it demonstrates that the subject-dependent properties of marrow may partly explain the inter-subject variability of speed of sound values.
Postnatal development of sound pressure transformations by the head and pinnae of the cat: Binaural characteristics
Authors: Tollin Daniel J. , Koka Kanthaiah
Published: December 2009

There are three acoustical cues to sound location: Interaural time differences (ITDs), interaural level differences (ILDs), and monaural spectral shape cues. During development, the increasing interaural distance and pinnae size associated with a growing head and pinnae result in localization cues that change continuously until maturation is complete. Here the authors report measurements of both the physical dimensions of the head and pinnae, as well as acoustical measurements of the binaural localization cues of cats aged 1.3 weeks to adulthood. For a given source location, ILD magnitude tended to increase with both frequency and age. Moreover, the range of significant ILD production (∼10 dB) shifted with age from higher to lower frequencies. ITD magnitude increased with age. Partial correlation analyses revealed that increasing pinnae size accounted for ∼31% of the variance in the development of ILDs while increasing head size accounted for virtually none. On the other hand, increases in both the head and pinnae sizes contributed to the development of the ITD cues accounting for ∼71% and ∼25% of the variance, respectively. ILD and ITD cues in cats reach maturity by ∼16 and ∼22 weeks, respectively, which match the time period over which the pinnae and head dimensions reach maturity.
A source separation approach to enhancing marine mammal vocalizations
Authors: Gur M. Berke , Niezrecki Christopher
Published: December 2009

A common problem in passive acoustic based marine mammal monitoring is the contamination of vocalizations by a noise source, such as a surface vessel. The conventional approach in improving the vocalization signal to noise ratio (SNR) is to suppress the unwanted noise sources by beamforming the measurements made using an array. In this paper, an alternative approach to multi-channel underwater signal enhancement is proposed. Specifically, a blind source separation algorithm that extracts the vocalization signal from two-channel noisy measurements is derived and implemented. The proposed algorithm uses a robust decorrelation criterion to separate the vocalization from background noise, and hence is suitable for low SNR measurements. To overcome the convergence limitations resulting from temporally correlated recordings, the supervised affine projection filter update rule is adapted to the unsupervised source separation framework. The proposed method is evaluated using real West Indian manatee (Trichechus manatus latirostris) vocalizations and watercraft emitted noise measurements made within a typical manatee habitat in Florida. The results suggest that the proposed algorithm can improve the detection range of a passive acoustic detector five times on average (for input SNR between −10 and 5dB) using only two receivers.