bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term outcome of pediatric obsessive–compulsive disorder: a meta‐analysis and qualitative review of the literature
Authors: Stewart S. E. , Geller D. A. , Jenike M. , Pauls D. , Shaw D. , Mullin B. , Faraone S. V.
Published: May 2004

Objective:  To review the extant literature on the long‐term outcome of child/adolescent‐onset obsessive–compulsive disorder (OCD).

Method:  Medline and Psychlit databases were systematically searched for articles regarding long‐term outcomes of child/adolescent‐onset OCD. Meta‐analysis regression was applied to evaluate predictors and persistence of OCD.

Results:  Sixteen study samples (n = 6–132; total = 521 participants) in 22 studies had follow‐up periods ranging between 1 and 15.6 years. Pooled mean persistence rates were 41% for full OCD and 60% for full or subthreshold OCD. Earlier age of OCD onset (z = −3.26, P = 0.001), increased OCD duration (z = 2.22, P = 0.027) and in‐patient vs. out‐patient status (z = 2.94, P = 0.003) predicted greater persistence. Comorbid psychiatric illness and poor initial treatment response were poor prognostic factors. Although psychosocial function was frequently compromised, most studies lacked comprehensive outcome measures.

Conclusion:  Long‐term persistence of pediatric OCD may be lower than believed. Future studies should include broader measures of outcome including symptomatic persistence and functional impairment in multiple domains.
Longitudinal diagnostic efficiency of DSM‐IV criteria for obsessive–compulsive personality disorder: a 2‐year prospective study
Authors: Grilo C. M. , Skodol A. E. , Gunderson J. G. , Sanislow C. A. , Stout R. L. , Shea M. T. , Morey L. C. , Zanarini M. C. , Bender D. S. , Yen S. , McGlashan T. H.
Published: May 2004

Objective:  To examine the longitudinal diagnostic efficiency of the DSM‐IV criteria for obsessive–compulsive personality disorder (OCPD).

Method:  At baseline, criteria and diagnoses were determined using diagnostic interviews, and blinded assessments were performed 24 months later with 550 participants. Diagnostic efficiency indices (conditional probabilities, total predictive power, and kappa) were calculated for each criterion determined at baseline, using the independent OCPD diagnosis at follow‐up as the standard.

Results:  Longitudinal diagnostic efficiencies for the OCPD criteria varied; findings suggested the overall predictive utility of ‘preoccupied with details’, ‘rigid and stubborn’, and ‘reluctant to delegate’.

Conclusion:  These findings suggest the predictive validity of three cognitive‐interpersonal OCPD criteria.
Insight into current symptoms of schizophrenia. Association with frontal cortical function and affect
Authors: Freudenreich O. , Deckersbach T. , Goff D. C.
Published: May 2004

Objective:  Examine whether frontal lobe dysfunction or affective experiences correlates with lack of symptom awareness in schizophrenia.

Method:  A total of 122 consecutive adult schizophrenia outpatients were assessed cross‐sectionally with standard rating scales of psychopathology and of insight, and underwent neuropsychological assessment with a battery of tests sensitive to frontal lobe dysfunction. Correlational analyses were used to determine relationships between variables.

Results:  About 62% of patients had at least partial awareness of symptoms. Anxiety correlated modestly with insight into the abnormal nature of positive and negative symptoms. No cognitive variable was significantly correlated with symptom awareness.

Conclusion:  The pathological nature of symptoms is better recognized by patients who experience dysphoric affect. Neither severity of psychotic symptoms nor frontal lobe cognitive deficits correlates to symptom awareness. Lack of insight, which can be partial for symptoms of the illness, might be a non‐reducible symptom of schizophrenia.
Social Identity and Community Effects on Contraceptive Use and Intentions in Southern Ethiopia
Authors: Hogan Dennis P. , Biratu Belay
Published: May 2004

In this study, data gathered in southern Ethiopia are used to explain how ethnic and religious identities affect current or intended contraceptive use. The only compositional factors that increase the likelihood of birth limitation are having a member of the family with a higher level of education and community access to health services. Compositional factors by themselves do not explain Muslim and ethnic variations in contraceptive use and intentions. Village health and economic crises do not promote birth limitation. One normative economic factor—the practice of sons' inheritance of land from their fathers–considerably reduces the likelihood of contraceptive use, but does not account for religious and ethnic differentials. No evidence is found of a minority‐status effect on contraception. Exposure to ethnic and religious diversity in the community of residence substantially increases the likelihood of emergent birth limitation, especially among the predominant Muslim Silte population.
Factors Associated with Contraceptive Use in Late‐ and Post‐apartheid South Africa
Authors: Burgard Sarah
Published: May 2004

In 1994, South Africa underwent a transition from the institutionalized racism of an apartheid state to a nonracial democracy. This study uses data from two surveys conducted in the style of the Demographic and Health Surveys to compare patterns and predictors of racial differences in modern contraceptive use in the late‐ and post‐apartheid periods. Age‐group‐specific logistic regression models show that despite strong state family planning programs targeting black women, these women were less likely than nonblacks to practice modern contraception both before and after the political transition, even after controlling for large racial‐group differences in sociodemographic characteristics and the distribution of socioeconomic resources. Black, colored, Indian, and white women show different patterns of contraceptive use across their reproductive careers; in particular, young, unmarried black and colored women show high levels of use. Use of injectable contraceptives is also high among black and colored women, whereas injectables are not the primary method used by Indian or white women. These findings are discussed in light of their research and policy implications.
The Moral Lens of Population Control: Condoms and Controversies in Southern Malawi
Authors: Kaler Amy
Published: May 2004

The study presents an investigation of stories about condoms in southern Malawi. Malawians' concerns about coercive population control imposed by a national government or international cabal provide a moral lens through which condoms and other health promotions are viewed, with unknown but probably negative impact on the use of condoms. The focus of the study is on the long shadow cast by population control because it is underresearched and, in fact, virtually unmentioned in most studies of health promotion, yet appears to be common if not ubiquitous. Moreover, this long shadow poses a distinct challenge to HIV‐prevention and intervention efforts. The data for the study were gathered by six Malawian research assistants in Balaka district, in southern Malawi, who kept journals over a period of three years in which they recorded conversations and everyday chats that they observed. These journals demonstrate that condoms do not arrive in communities as neutral, value‐free objects; rather they enter a social setting permeated with ideas about health, self‐protection, and danger. The lens of population control has proved to be both durable and flexible, providing a moral context in which both commodities and actors can be understood. Disentangling condoms from the symbolic nexus in which they are fused with disease, population control, and malevolence will be an ongoing challenge in the struggle to prevent the spread of HIV/AIDS in Malawi.
Condom Use Within Marital and Cohabiting Partnerships in KwaZulu‐Natal, South Africa
Authors: Maharaj Pranitha , Cleland John
Published: May 2004

Traditionally, the major focus of condom‐promotion strategies has been on increasing use outside marriage. This study explores the extent and determinants of condom use within marital and cohabiting partnerships in KwaZulu‐Natal, South Africa. In focus‐group discussions, in‐depth interviews, and individual survey responses, knowledge of condoms as an effective method of dual protection against the risk of pregnancy and disease was found to be high. Consistent with numerous other studies, this study found widespread disapproval of condom use within marriage. Only 14 percent of men and 17 per cent of women reported consistent or “occasional” condom use. Nevertheless, condom use is much higher among urban, more‐educated individuals than among their rural, less‐educated counterparts. Apart from education, perceived risk of HIV infection from the partner is the most powerful determinant of use within marital and cohabiting partnerships, particularly for women. Resistance to condoms within marital and cohabiting partnerships is not immutable, however, and women may not be as powerless to protect themselves as is often reported.
Partnership working in the production of clinical guidelines
Authors: Keating Liza , Carter Helen , Darwent Melanie , Bateman Sally , Mackay Donald M. , Pullinger Rick
Published: May 2004

This article describes a working partnership between the Cairns Clinical Librarian Service, Health Care Libraries, University of Oxford and the Emergency Department (ED) at the John Radcliffe Hospital, Oxford. This collaboration resulted in the establishment of a guideline development group in June 2002. The aim of the group is to produce a set of easily accessible, user‐orientated, evidence‐based guidelines for the use of clinicians in the Emergency Department, within a realistic timescale. The Cairns Clinical Librarian Project was built on previous models of clinical librarianship and incorporated an evaluation of previous programmes. The objective was to provide information to clinicians at the time and point of need. Consultation with the ED from the outset determined the approach adopted by the Cairns team. Clinical guidelines have been shown to improve clinical practice. Pending the introduction of nationally available protocols, we have begun to establish a collection of evidence‐based guidelines using web‐based architecture in conjunction with the Oxford Radcliffe Hospitals NHS Trust's IT department. A piece of diagnostic analysis was undertaken to ensure a coherent strategy was developed for the guideline project. An ‘intermediate approach’ was adopted, where existing valid guidelines were modified to fit local circumstances. We strove to be transparent at all times about all aspects of the guideline development process. Formative evaluation has shown how the application of evidence‐based health care needs adequate resources and requires people with appropriate knowledge and skills. This article charts the progress of the project and highlights how the partnership between the clinical team and the Clinical Librarian has been deemed to be essential to the success of the project.
All for one, one for all: collaboration between NHS and Higher Education in establishing provision of a multi‐disciplinary, hospital‐based library and information services
Authors: Black Coral , Bury Rachel
Published: May 2004

Developing multi‐disciplinary library and information services is high on the agenda for many NHS trusts and this brings with it a climate of change for both those who manage and work in services today. The development of such new services needs to be carefully managed and developed, and this presents a challenge for librarians and service managers. In the UK during 1999 and 2000, Aintree Hospital Trust, in conjunction with Edge Hill College of Higher Education, established a truly multi‐disciplinary service based at its hospital site and managed by Edge Hill. This paper outlines the key stages in the development of the Library and Information Service with the focus on the management of change, collaboration and the development of a unique partnership between Higher Education and an NHS trust. The case study example will provide an outline of strategic and project planning, with insights into staff management and development, delivering user expectations and developing stakeholder relationships in the health library setting.
Creation and development of an All‐Wales Health Library Catalogue
Authors: John Jennifer , Wright Helen M.
Published: May 2004

This article focuses on the collaboration between the University of Wales College of Medicine (UWCM) libraries and the Welsh National Health Service (NHS) libraries to create a joint library catalogue. The goal was to create an all‐Wales resource that gave users one access point to search for the location and availability of health‐related material in any Welsh medical library. This venture grew out of the existing collaborative scheme, the All‐Wales Health Information and Library Extension Services (AWHILES). Currently, all seven UWCM libraries and 17 NHS libraries contribute to the catalogue. Four more libraries are due to join in late 2003 or early 2004. All UWCM and AWHILES libraries would then be contributing members of the joint catalogue.

The article discusses the background and motivation to the creation of the database. It explores the positives and negatives of the project plus what was learnt as the venture progressed. It reviews the establishment and operations of the Welsh Health Voyager User Group (WHVUG) created to involve all contributing members in the running and future development of the library catalogue.
‘How Do I Choose Thee? Let me Count the Ways’: A Textual Analysis of Similarities and Differences in Modes of Decision-making in China and the United States
Authors: Weber Elke U. , Ames Daniel R. , Blais Ann-Renée
Published: June 2004

This paper investigates the effect of decision-makers' culture on their implicit choice of how to make decisions. In a content analysis of major decisions described in American and Chinese twentieth-century novels, we test a series of hypotheses based on prior theoretical and empirical investigations of cross-cultural variation in human motivation and decision processes. The data show a striking degree of cultural similarity in the relationships between decision content, situational characteristics and the decision mode(s) employed, but also support several hypotheses about cultural differences. As predicted, Chinese decision-makers more frequently used role-based logic (a form of recognition-based decision-making) to arrive at decisions, by virtue of their greater awareness of and need for relational obligations. The hypothesis (based on conjectures about Chinese thinking style and personality differences) that Chinese decision-makers would show more rule-and case-based decision-making (two other variants of recognition-based decision-making) than decision-makers in American novels was also supported. After controlling for other predictor variables, there also was support for the hypothesis (based on comparative analyses of Chinese and Western philosophy) that analytic modes which base decisions on the calculation of best consequences would be used less frequendy by Chinese decision-makers. There was no evidence of greater prevention focus in Chinese decisions. These and other observed cultural similarities and differences in the dynamics of decision mode selection have implications for the study and practice of decision-making in managerial settings.
An Organizational Perspective of Corruption
Authors: Luo Yadong
Published: June 2004

An organizational view of corruption is a frontier and challenging issue in the realm of management and organization research. This article elucidates four interrelated yet sequential issues that collectively constitute organizational explanations of corruption: (i) corruption and organizational environment; (ii) corruption and organizational behaviour; (iii) corruption and organizational consequences; and (iv) corruption and organizational architecture. Specifically, it (1) offers taxonomic metaphors that identify different corrupt organizations on the basis of corruption scale and hierarchical involvement; (2) defines task environments (oligopoly intensity, regulatory control and structural uncertainly) and institutional environments (opaqueness, injustice and complexity) that stimulate illicit acts; (3) confers a typology of corrupt behaviors that align with these task and institutional environments and correspond to different metaphors (system malfeasance, procedural malfeasance, categorical malfeasance and structural malfeasance); (4) develops the logic that corruption impedes organizational development through quadri-damages (evolutionary hazard, strategic impediment, competitive disadvantage and organizational deficiency; and (5) illuminates a corruption-resisting architecture comprising corporate culture, organizational structure and compliance system.
Mathematical Foundation for Modeling Conceptual Design Sketches1
Authors: Zeng Y. , Pardasani , A. , Dickinson , J. , Li , Z. , Antunes , and H. , Gupta V. , Baulier D.
Published: May 2004

This paper aims to establish a mathematical foundation for modeling free-hand design sketches throughout the conceptual design process. Both experimental and theoretical approaches are used. In using the experimental approach, one case study from a book and one case study from an automobile assembly system manufacturer are used to illustrate the characteristics of design sketches. These characteristics provide the requirements for models of sketch representation. In using the theoretical approach, a mathematical structure of design sketches is established. This mathematical structure can naturally and logically model the evolving sketches generated in the design process, through integrating the strengths of set theory and mereology. In addition to the formal representation of design sketches, the mathematical model provides a logical foundation for formally designing sketch interpretation algorithms. An algorithmic structure of three-dimension reconstruction from two-dimension line drawing is derived using this mathematical model.
Computational Issues of a VDIM Based Multipurpose Modeling in Conceptual Design
Authors: Rusa´k Zolta´n
Published: May 2004

To be able to model industrial products in conceptual design, aspects such as function, structure, shape, behavior, sustainability and service are typically considered. Tools developed until now usually focus on individual aspects. The author proposes a new modeling approach called vague discrete interval modeling (VDIM) that integrates shape, structure and behavior modeling. The integration is achieved by the introduction of a multipurpose modeling entity called particle. VDIM offers three means for the representation of a cluster of shapes, for instances of shapes and for physically-based manipulation of shapes. Interval modeling allows representing uncertainty of shapes, which is a characteristic property in shape conceptualization. In addition, particle systems can be applied to model the mechanical behavior of the product. This constructive modeling approach makes it possible to describe the procedural model of incomplete geometries and to capture the structural relations between components. The paper reports on the computational issues related to VDIM.
Simulation-based Virtual Prototyping of Customized Catheterization Devices
Authors: Cai Y. Y. , Chui C.-K. , Ye X. , Anderson J. H. , Liew K.-M. , Sakuma I.
Published: May 2004

Human vascular systems have considerable anatomic variations. In diseased situation, significant pathological changes will be developed with the systems. However, vascular catheterization devices commercially available are essentially designed on normal or average anatomy. Their inadequacies in representing major deviations in human vascular anatomy may present problems during diagnostic or therapeutic interventions. A virtual reality (VR) based simulation method is described in this paper for prototyping of customized patient-specific catheterization devices. Techniques are developed to model patient-specific vascular network, to design catheterization devices, and to simulate physical-based interactions between blood vessels and the devices. Emphasis is made on the integration of normal and variant vascular models, the integration of modeling, visualization and interaction, and the integration of real-time simulation and virtual prototyping.
Predictive Value of Assessing Vehicle Interior Design Ergonomics in a Virtual Environment
Authors: Reuding Thomas , Meil Pamela
Published: May 2004

The predictive value and the reliability of evaluations made in immersive projection environments are limited when compared to the real world. As in other applications of numerical simulations, the acceptance of such techniques does not only depend on the stability of the methods, but also on the quality and credibility of the results obtained. In this paper, we investigate the predictive value of virtual reality and virtual environments when used for engineering assessment tasks. We examine the ergonomics evaluation of a vehicle interior, which is a complex activity relying heavily on know-how gained from personal experience, and compare performance in a VE with performance in the real world. If one assumes that within complex engineering processes certain types of work will be performed by more or less the same personnel, one can infer that a fairly consistent base of experience-based knowledge exists. Under such premises and if evaluations are conducted as comparisons within the VE, we believe that the reliability of the assessments is suitable for conceptual design work. Despite a number of unanswered questions at this time we believe this study leads to a better understanding of what determines the reliability of results obtained in virtual environments, thus making it useful for optimizing virtual prototyping processes and better utilization of the potential of VR and VEs in company work processes.
Flexible Beam Part Manipulation for Assembly Operation Simulation in a Virtual Reality Environment
Authors: Mikchevitch A. , Le´on J.-C. , Gouskov A.
Published: May 2004

The aspects of fast and realistic simulation of flexible parts during the Assembly/Disassembly (A/D) process are discussed in this paper. The proposed approach, adapted to current Virtual Reality (VR) devices and incorporating mechanical models, will be used as a basis for A/D of flexible parts in a VR environment. First of all, the study of current A/D simulation methods is performed. Secondly, a new system integrating real-time and interactive mechanical models is proposed. Finally, an example of the interactive mechanical model for virtual A/D of flexible beam-parts is presented. Numerical tests are set up to evaluate the proposed approach and focus on typical boundary conditions prescribed in the configuration and force spaces introduced.
Reorganizing CAD Assembly Models (as-Designed) for Manufacturing Simulations and Planning (as-Built)
Authors: Jayaram Uma , Kim YoungJun , Jayaram Sankar , Jandhyala Venkata K. , Mitsui Tatsuki
Published: May 2004

A CAD assembly model is a collection of components, comprised recursively of various levels of individual parts and sub-assembly models. Although the overall geometry in the CAD assembly model accurately represents the final finished product, this model is often meaningless from a manufacturing planning and simulation point of view. The grouping of the components into sub-assemblies and the assembly sequence implied by the CAD model does not accurately represent the manufacturing/assembly sequence or process. Reordering, regrouping, and modifying existing sub-assemblies, or creating new sub-assemblies in the CAD model may be needed to ensure this correspondence for simulation or assembly planning tools that derive the manufacturing sequence directly from the CAD system. Although this task can be performed using the existing functionality of the CAD system, it quickly becomes unwieldy for large industry-grade models due to the assembly constraints and relationships in place during the model creation. In industry today, there are several digital mockup and assembly planning tools that greatly outstrip the ability of CAD systems in loading complete models and creating assembly plans. Methods to organize the CAD model assembly quickly and easily for use in these systems, and to record the “as manufactured” assembly in the CAD data format are needed to close the loop and ease the transfer, storage, and maintenance of model data between the CAD systems, PDM systems, and these new age planning and mockup systems. In this paper, a new hybrid method is proposed to provide this functionality. Of key significance is the fact that using this approach, polygonal representations of any new or modified sub-assemblies designated in the reorganized hierarchy can be produced and that the original constraints used in the original assembly are transformed in a consistent manner to the new components. In addition, corresponding property files for the new components can be created for use in the assembly planning tool. In order to validate this hybrid approach, the time required to rearrange the assembly hierarchy and output the required information using both methods are compared–1) the traditional method using the CAD system alone, and 2) the new hybrid system. A statistical analysis using three treatment factors indicates that if the number of components is more than 15, then it is far more efficient to use the hybrid method over the CAD system by itself. This hybrid method implementation has now been used very successfully in virtual assembly simulations of many industry models, some with several hundred components, provided by various industry partners.
Value-Addition of Haptics in Operator Training for Complex Machining Tasks
Authors: Balijepalli Arvind , Kesavadas T.
Published: May 2004

This paper presents a haptic simulator based on a force model that renders precise and crisp force feed back for a range of applications such as grinding, polishing and deburring of metals using an abrasive hand-grinding tool. Many skill based manufacturing and medical applications require a human operator to use grinding tools to impart force to remove material from a surface that may have rough texture or asperities. This paper describes the design, implementation and evaluation of this proposed system. First a force model is presented to compute forces resulting from grinding tool work piece interface. Next an image based 3D Terrain modeling algorithm is developed to simulate the details of work piece topology. To create sensation of metal removal during the grinding processes, a dynamic texture modification algorithm is developed to provide realistic virtual simulation of polishing process. Finally human subject tests are carried out to test the effectiveness of the simulator. The skill sets required for grinding operations are usually learned through practice. The grinding simulator presented here is a step towards using haptics to perfect this skill that is otherwise hard to learn quickly.
Immersive Visual Interfaces–Assessing Usability by the Effects of Learning/Results from an Empirical Study
Authors: Johansson Per , Ynnerman Anders
Published: May 2004

Different immersive visual interfaces’ ability to support engineering designers in product design is assessed in an experimental study. A focus was put on learning as an important factor to measure performance. Subjects were asked to find induced errors in a mechanical product using different display solutions; an Immersive Workbench, a Desktop-VR system and a Desktop system. Results show that Immersive Displays can support the designers in product development. In terms of detection times, subjects using Desktop-VR with stereoscopic glasses performed best, but difference is not significant. No difference was found between the treatments as regards the number of successful trials.
Localization of marine mammals near Hawaii using an acoustic propagation model
Authors: Tiemann Christopher O. , Porter Michael B. , Frazer L. Neil
Published: June 2004

Humpback whale songs were recorded on six widely spaced receivers of the Pacific Missile Range Facility (PMRF) hydrophone network near Hawaii during March of 2001. These recordings were used to test a new approach to localizing the whales that exploits the time-difference of arrival (time lag) of their calls as measured between receiver pairs in the PMRF network. The usual technique for estimating source position uses the intersection of hyperbolic curves of constant time lag, but a drawback of this approach is its assumption of a constant wave speed and straight-line propagation to associate acoustic travel time with range. In contrast to hyperbolic fixing, the algorithm described here uses an acoustic propagation model to account for waveguide and multipath effects when estimating travel time from hypothesized source positions. A comparison between predicted and measured time lags forms an ambiguity surface, or visual representation of the most probable whale position in a horizontal plane around the array. This is an important benefit because it allows for automated peak extraction to provide a location estimate. Examples of whale localizations using real and simulated data in algorithms of increasing complexity are provided.
High-frequency (8–16 kHz) model-based source localization
Authors: Hursky Paul , Porter Michael B. , Siderius Martin , McDonald Vincent K.
Published: June 2004

Matched-field or model-based processing has now been widely demonstrated for improving source localization and detection in ocean waveguides. Most of the processing approaches become increasingly sensitive to fluctuations or uncertainties as the frequency increases. As a result, there has been very limited work above 1 kHz and there is a perception that above several kilohertz the technique cannot be applied. We have conducted acoustic communications experiments in a variety of shallow water sites around coastal areas of the United States. These experiments show that a clear multipath structure is readily observed even in the 8–16 kHz band. Furthermore, it is shown that model-based processing can then be exploited to localize sources at these high frequencies out to ranges of several kilometers.
Listener sensitivity to individual talker differences in voice-onset-time
Authors: Allen J. Sean , Miller Joanne L.
Published: June 2004

Recent findings in the domains of word and talker recognition reveal that listeners use previous experience with an individual talker’s voice to facilitate subsequent perceptual processing of that talker’s speech. These findings raise the possibility that listeners are sensitive to talker-specific acoustic-phonetic properties. The present study tested this possibility directly by examining listeners’ sensitivity to talker differences in the voice-onset-time (VOT) associated with a word-initial voiceless stop consonant. Listeners were trained on the speech of two talkers. Speech synthesis was used to manipulate the VOTs of these talkers so that one had short VOTs and the other had long VOTs (counterbalanced across listeners). The results of two experiments using a paired-comparison task revealed that, when presented with a short- versus long-VOT variant of a given talker’s speech, listeners could select the variant consistent with their experience of that talker’s speech during training. This was true when listeners were tested on the same word heard during training and when they were tested on a different word spoken by the same talker, indicating that listeners generalized talker-specific VOT information to a novel word. Such sensitivity to talker-specific acoustic-phonetic properties may subserve at least in part listeners’ capacity to benefit from talker-specific experience.
Microseismic source deconvolution: Wiener filter versus minimax, Fourier versus wavelets, and linear versus nonlinear
Authors: Ching Jianye , To Albert C. , Glaser Steven D.
Published: June 2004

Deconvolution is commonly performed on microseismic signals to determine the time history of a dislocation source, usually modeled as combinations of forces or couples. This paper presents a new deconvolution method that uses a nonlinear thresholding estimator, which is based on the minimax framework and operates in the wavelet domain. Experiments were performed on a steel plate using artificially generated microseismic signals, which were recorded by high-fidelity displacement sensors at various locations. The source functions were deconvolved from the recorded signals by Wiener filters and the new method. Results were compared and show that the new method outperforms the other methods in terms of reducing noise while keeping the sharp features of the source functions. Other advantages of the nonlinear thresholding estimator include (1) its performance is close to that of a minimax estimator, (2) it is nonlinear and takes advantage of sparse representations under wavelet bases, and (3) its computation is faster than the fast Fourier transform.
Amplitude and phase calibration of hydrophones up to 70 MHz using broadband pulse excitation and an optical reference hydrophone
Authors: Wilkens Volker , Koch Christian
Published: June 2004

A substitution calibration technique for piezoelectric ultrasonic hydrophones is presented that uses an optical multilayer hydrophone as the reference receiver. Broadband nonlinearly distorted focused pulses are first measured with the reference hydrophone and then with the hydrophone to be calibrated. By Fourier transformation of the time wave forms and division of the frequency spectra, the complex-valued frequency response of the hydrophone under test is obtained in a broad frequency range in a very fast and efficient way and with high frequency resolution. The results obtained for a membrane hydrophone and a needle-type hydrophone are compared with those obtained by independent calibration techniques such as primary calibration using optical interferometry and secondary calibration using time-delay spectrometry, and good agreement is found. The calibration data obtained are apt to improve the results of ultrasound exposure measurements using broadband voltage-to-pressure conversion. This is demonstrated for standard pulse parameter determination from exemplar exposure measurements on a commercial diagnostic ultrasound machine. For the membrane hydrophone, the evaluation method commonly used leads to an overestimation of the positive peak pressure by up to 50%, an underestimation of the rarefactional peak pressure by up to 11%, and an overestimation of the pulse intensity integral by up to 28%.
Transient temperature rise due to ultrasound absorption at a bone/soft-tissue interface
Authors: Myers Matthew R.
Published: June 2004

Thermal effects due to high ultrasound absorption in bone pose an ongoing safety issue. Of considerable concern is the heating of the soft tissue adjacent to the bone surface. Mathematical models can be useful in predicting the transient temperature near the interface during insonation. This paper develops a model that provides the temperature field in terms of simple expressions that convey the functional dependence of the material properties, and are easily incorporated into standards and ultrasound machine software, yet are able to incorporate the material properties of both bone and soft tissue. The model contains an asymptotic theory based upon a “high-attenuation” assumption: the distance diffused by heat over the time of interest is large compared to the ultrasound attenuation length. Model predictions of temperature rise and location of maximum temperature were in close agreement with finite-element calculations, using parameters appropriate for radiation-force imaging and focused-ultrasound surgery.
Air-coupled, focused ultrasonic dispersion spectrum reconstruction in plates
Authors: Holland Stephen D. , Teles Sorin V. , Chimenti D. E.
Published: June 2004

This paper presents and demonstrates a noncontact method for measuring the Lamb wave dispersion spectrum of a plate. Noncontact air-coupled source and receive transducers are used with line-focus mirrors and 50–700 kHz broadband apparatus for simultaneous measurement over a broad spectrum of refractive angles and multiple guided modes. Broadband, wide-angle wave forms are measured as a function of position. The Fourier transform of these wave forms from the t–x domain to the ω–k domain gives an approximate spectrum of the dispersion relation. We measure the dispersion spectra of Lucite™, aluminum, balsa wood, and a carbon fiber epoxy laminate, and show that the measured spectra agree well with the dispersion relation calculated from Lamb wave theory.
Effects of time-reversing array deformation in an ocean wave guide
Authors: Sabra Karim G. , Dowling David R.
Published: June 2004

Active acoustic time reversal is a technique for focusing sounds recorded in complex unknown environments back to their remote point(s) of origin. It can be accomplished with a transducer array—a time-reversing array (TRA)—that sends and receives sound. Nearly all prior work on TRA performance has involved stationary arrays. This letter describes how random array deformation influences TRA retrofocusing in shallow ocean environments. For harmonic signals, randomly drifting array elements degrade TRA performance by ∼20% when the average horizontal wavenumber times the root-mean-square horizontal element displacement approaches 0.5. TRA focusing should be less sensitive to vertical element drift.
Effectiveness of parallel-plate heat exchangers in thermoacoustic devices
Authors: Wakeland Ray Scott , Keolian Robert M.
Published: June 2004

Measurements are made of the heat transferred between two identical parallel-plate heat exchangers under conditions of oscillating flow over a range of frequencies and amplitudes. The results are analyzed and summarized in terms of heat-exchanger effectiveness, the ratio of the actual heat transfer rate to the maximum possible heat transfer rate. Measured results are compared to the DELTAE model that is often used in the design of conventional thermoacoustic devices, and possible improvements to the model are offered.
Acoustic performance of a large-aperture, seabed, fiber-optic hydrophone array
Authors: Cranch G. A. , Crickmore R. , Kirkendall C. K. , Bautista A. , Daley K. , Motley S. , Salzano J. , Latchem J. , Nash P. J.
Published: June 2004

A large-aperture, seabed mounted, fiber-optic hydrophone array has been constructed and characterized. The system is designed for use as a large area surveillance array for deployment in shallow water regions. The underwater portion comprises two arrays of 48 hydrophones separated by a 3 km fiber-optic link, which are connected to a shore station by 40 km of single-mode optical fiber. The hydrophone is based on a fiber-optic Michelson interferometer and the acoustic transduction mechanism is a fiber-wrapped mandrel design. No electrical power is required in the underwater portion. The performance of the system is described, characterized during laboratory measurements and during a recent sea trial. Specifically, measurements of the acoustic resolution, array shape, beam patterns, array gain, and target tracking capability of this array. The system demonstrates self-noise levels up to 20 dB (typically 10 dB) lower than the ambient acoustic noise experienced in the sea trial and array gains close to the theoretical maximum. The system telemetry and electronics have been designed to be expandable to accommodate several hundred hydrophones.
Soft-computing base analyses of the relationship between annoyance and coping with noise and odor
Authors: Botteldooren Dick , Lercher Peter
Published: June 2004

The majority of research on annoyance as an important impact of noise, odor, and other stressors on man, has regarded the person as a passive receptor. It was however recognized that this person is an active participant trying to alter a troubled person–environment relationship or to sustain a desirable one. Coping has to be incorporated. This is of particular importance in changing exposure situations. For large populations a lot of insight can be gained by looking at average effects only. To investigate changes in annoyance and effects of coping, the individual or small group has to be studied. Then it becomes imperative to recognize the inherent vagueness in perception and human behavior. Fortunately, tools have been developed over the past decades that allow doing this in a mathematically precise way. These tools are sometimes referred to by the common label: soft-computing, hence the title of this paper. This work revealed different styles of coping both by blind clustering and by (fuzzy) logical aggregation of different actions reported in a survey. The relationship between annoyance and the intensity of coping it generates was quantified after it was recognized that the possibility for coping is created by the presence of the stressor rather than the actual fact of coping. It was further proven that refinement of this relationship is possible if a person can be identified as a coper. This personal factor can be extracted from a known reaction to one stressor and be used for predicting coping intensity and style in another situation. The effect of coping on a perceived change in annoyance is quantified by a set of fuzzy linguistic rules. This closes the loop that is responsible for at least some of the dynamics of the response to a stressor. This work thus provides all essential building blocks for designing models for annoyance in changing environments.
Similarity in loudness and distortion product otoacoustic emission input/output functions: Implications for an objective hearing aid adjustment
Authors: Müller Jörg , Janssen Thomas
Published: June 2004

The aim of the present study was to compare distortion product otoacoustic emissions (DPOAEs) to loudness with regard to the potentiality of DPOAEs to determine characteristic quantities of the cochlear-impaired ear and to derive objective hearing aid parameters. Recently, Neely et al. [J. Acoust. Soc. Am. 114, 1499–1507 (2003)] compared DPOAE input/output functions to the Fletcher and Munson [J. Acoust. Soc. Am. 5, 82–108 (1933)] loudness function finding a close resemblance in the slope characteristics of both measures. The present study extended their work by performing both loudness and DPOAE measurements in the same subject sample, and by developing a method for the estimation of gain needed to compensate for loss of cochlear sensitivity and compression. DPOAEs and loudness exhibited similar behavior when plotted on a logarithmic scale and slope increased with increasing hearing loss, confirming the findings of Neely et al. To compensate for undesired nonpathological impacts on the magnitude of DPOAE level, normalization of DPOAE data was implemented. A close resemblance between gain functions based on loudness and normalized DPOAE data was achieved. These findings suggest that DPOAEs are able to quantify the loss of cochlear sensitivity and compression and thus might provide parameters for a noncooperative hearing aid adjustment.
Time-reversal imaging with multiple signal classification considering multiple scattering between the targets
Authors: Gruber Fred K. , Marengo Edwin A. , Devaney Anthony J.
Published: June 2004

The time-reversal imaging with multiple signal classification method for the location of point targets developed within the framework of the Born approximation in Lehman and Devaney [“Transmission mode time-reversal super-resolution imaging,” J. Acoust. Soc. Am. 113, 2742–2753 (2003)] is generalized to incorporate multiple scattering between the targets. It is shown how the same method can be used in the location of point targets even if there is multiple scattering between them. On the other hand, both the conventional images and the calculated values of the target scattering amplitudes are scattering model-dependent.
Variability of low frequency sound transmission measurements
Authors: Bravo Teresa , Elliott Stephen J.
Published: June 2004

In this paper we discuss the characterization of low frequency sound transmission between two rooms via a flexible panel. A fully-coupled modal model is used to investigate the individual effect of the source room and the receiving room on the measured sound reduction index, and the results are compared with the ideal case of having a free field on both sides of the panel. The effect of the source room on the measured sound reduction index at low frequencies can be reduced by using a number of suitable-driven loudspeakers close to the panel to simulate a diffuse incident field. However, the effect of the receiving room was found not to be reduced by calculating the transmitted acoustic power from a dense array of acoustic intensity measurements, instead of an array of microphones in the receiving room.
Errors in ultrasonic scatterer size estimates due to phase and amplitude aberration
Authors: Gerig Anthony , Zagzebski James
Published: June 2004

Current ultrasonic scatterer size estimation methods assume that acoustic propagation is free of distortion due to large-scale variations in medium attenuation and sound speed. However, it has been demonstrated that under certain conditions in medical applications, medium inhomogeneities can cause significant field aberrations that lead to B-mode image artifacts. These same aberrations may be responsible for errors in size estimates and parametric images of scatterer size. This work derives theoretical expressions for the error in backscatter coefficient and size estimates as a function of statistical parameters that quantify phase and amplitude aberration, assuming a Gaussian spatial autocorrelation function. Results exhibit agreement with simulations for the limited region of parameter space considered. For large values of aberration decorrelation lengths relative to aberration standard deviations, phase aberration errors appear to be minimal, while amplitude aberration errors remain significant. Implications of the results for accurate backscatter and size estimation are discussed. In particular, backscatter filters are suggested as a method for error correction. Limitations of the theory are also addressed. The approach, approximations, and assumptions used in the derivation are most appropriate when the aberrating structures are relatively large, and the region containing the inhomogeneities is offset from the insonifying transducer.
Localization dominance in the median-sagittal plane: Effect of stimulus duration
Authors: Dizon Roberto M. , Litovsky Ruth Y.
Published: June 2004

Localization dominance is an aspect of the precedence effect (PE) in which the leading source dominates the perceived location of a simulated echo (lagging source). It is known to be robust in the horizontal/azimuthal dimension, where binaural cues dominate localization. However, little is known about localization dominance in conditions that minimize binaural cues, and most models of precedence treat the phenomena as “belonging” to the binaural system. Here, localization dominance in the median-sagittal plane was studied where binaural cues are greatly reduced, and monaural spectral/level cues are thought to be the primary cues used for localization. Lead–lag pairs of noise bursts were presented from locations spaced in 15° increments in the frontal, median-sagittal plane, with a 2-ms delay in their onsets, for source durations of 1, 10, 25, and 50-ms. Intermixed with these trials were single-speaker trials, in which lead and lag were summed and presented from one speaker. Listeners identified the speaker that was nearest to the perceived source location. With single-speaker stimuli, localization improves as signal duration is increased. Furthermore, evidence of elevation compression was found with a dependence on duration. With lead–lag pairs, localization dominance occurs in the median plane, and becomes more robust with increased signal duration. These results suggest that accurate localization of a co-located lead–lag pair is necessary for localization dominance to occur when the lag is spatially separated from the lead.