bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison between gradient‐dependent hydraulic conductivities of roots using the root pressure probe: the role of pressure propagations and implications for the relative roles of parallel radial pathways
Authors: BRAMLEY HELEN , TURNER NEIL C. , TURNER DAVID W. , TYERMAN STEPHEN D.
Published: June 2007

Hydrostatic pressure relaxations with the root pressure probe are commonly used for measuring the hydraulic conductivity (Lpr) of roots. We compared the Lpr of roots from species with different root hydraulic properties (Lupinus angustifolius L. ‘Merrit’, Lupinus luteus L. ‘Wodjil’, Triticum aestivum L. ‘Kulin’ and Zea mays L. ‘Pacific DK 477’) using pressure relaxations, a pressure clamp and osmotic gradients to induce water flow across the root. Only the pressure clamp measures water flow under steady‐state conditions. Lpr determined by pressure relaxations was two‐ to threefold greater than Lpr from pressure clamps and was independent of the direction of water flow. Lpr (pressure clamp) was two‐ to fourfold higher than for Lpr (osmotic) for all species except Triticum aestivum where Lpr (pressure clamp) and Lpr (osmotic) were not significantly different. A novel technique was developed to measure the propagation of pressure through roots to investigate the cause of the differences in Lpr. Root segments were connected between two pressure probes so that when root pressure (Pr) was manipulated by one probe, the other probe recorded changes in Pr. Pressure relaxations did not induce the expected kinetics in pressure in the probe at the other end of the root when axial hydraulic conductance, and probe and root capacitances were accounted for. An electric circuit model of the root was constructed that included an additional capacitance in the root loaded by a series of resistances. This accounted for the double exponential kinetics for intact roots in pressure relaxation experiments as well as the reduced response observed with the double probe experiments. Although there were potential errors with all the techniques, we considered that the measurement of Lpr using the pressure clamp was the most unambiguous for small pressure changes, and provided that sufficient time was allowed for pressure propagation through the root. The differences in Lpr from different methods of measurement have implications for the models describing water transport through roots and the potential role of aquaporins.
Age determines memory for face identity and expression
Authors: SAVASKAN Egemen , MÜLLER Sandra Elisabeth , BÖHRINGER Andreas , PHILIPPSEN Christine , MÜLLER‐SPAHN Franz , SCHÄCHINGER Hartmut
Published: June 2007

Background:  The recognition of facial expressions is an important component of emotion processing which contributes to interactional behavior. One of the factors highly associated with potential decline of ability in behavioral tasks is age.

Methods:  We have investigated age‐related changes in facial identity and expression memory of healthy subjects in three age groups: young adults (20–40 years), elderly adults (60–80 years) and, for the first time in the literature, very old adults (over 80 years of age). Using a picture test, photographs of faces with happy or angry expressions were presented to study participants during the encoding task, and the memory for identity and emotional facial expression was investigated in a subsequent recognition task showing emotionally neutral faces. Half of the faces presented in the recognition task were initially shown in the encoding task.

Results:  Age interacted with the memory process: the ability to recognize both facial identity and emotional expression declined with advanced age. Happy facial expressions were better recognized in all age groups. Although there was a continuous overall decrease in recognition of both happy and angry expressions with advanced age, the effect favoring happy facial expressions was stable also in very old adults. Other factors such as gender or educational level did not affect the memory process for facial expressions.

Conclusions:  Our findings suggest that age is a significant determinant of memory for facial identity and emotional expression, and that, similar to younger adults, the recognition process of the elderly favors happy emotional facial expressions.
Effect of activity reminiscence therapy as brain‐activating rehabilitation for elderly people with and without dementia
Authors: YAMAGAMI Tetsuya , OOSAWA Makoto , ITO Sinichi , YAMAGUCHI Haruyasu
Published: June 2007

Background:  Preventing the progression of dementia is a widespread challenge. However, currently there is limited evidence supporting the effectiveness of dementia rehabilitation.

Methods:  We practiced activity reminiscence therapy (ART) as brain‐activating rehabilitation for both lucid and demented persons (n = 18) in a day‐service setting as well as in a group home. The ART sessions were conducted 1 hour every week for 12 weeks (intervention period). We compared the results of three cognitive tests (the Mini‐Mental State Examination, the Kana Pick‐out test and the ‘logical memory’ component of the Wechsler Memory Scale‐Revised) and four behavior and caregiver's burden scales (the Clinical Dementia Rating, the Multidimensional Observation Scale for Elderly Subjects, the Dementia Behavior Disturbance scale and the Zarit Caregiver Burden Interview) conducted during the control period with those taken during the intervention period. At the end of the intervention period, we interviewed the staff and families individually to assess whether the participants seemed to have changed after intervention and, if so, how.

Results:  In cognitive tests, only immediate and delayed recall of the Wechsler Memory Scale‐Revised showed significant improvement. None of the four behavior and caregiver's burden scales showed any significant changes after intervention. However, the interviews showed improvements in subjective aspects of communication, interaction and behavior.

Conclusion:  ART uses old‐style tools. The nostalgia brought about by using these familiar tools led to effective recall of experiences, in which the participants taught the staff how to use the tools, which were unfamiliar to the staff. Through this role‐reversal, they gained a sense of self‐worth and a desire to live. Due to the reconstructed relationship between participants and caregivers, we consider ART to be effective in maintaining and improving emotional functions, activities of daily living and memory. ART should be useful for both lucid and mildly demented persons as brain‐activating rehabilitation therapy.
Gefitinib in advanced non‐small cell lung cancer: Clinical experience in patients of Asian origin
Authors: ARMOUR Alison
Published: June 2007

Background:  The IRESSA Survival Evaluation in Lung cancer (ISEL) trial showed some improvement in survival which failed to reach statistical significance in the overall population and in patients with adenocarcinoma. However, gefitinib (IRESSA) treatment was associated with a significant improvement in the survival in subgroups of patients of Asian origin and never smokers. Here we review the clinical experience of gefitinib in patients of Asian origin with advanced non‐small cell lung cancer (NSCLC) and discuss the evidence for the underlying biological basis for the apparent heterogeneity in clinical outcome between patients of Asian and non‐Asian origin.

Methods:  Reports of clinical experience with gefitinib 250 mg/day in Asia were identified by searching Embase and Medline databases for publications between 1 January 2003 and 27 July 2006.

Results:  A large number of reports in patients of Asian origin show high objective response and disease‐control rates with gefitinib treatment, with median survival >6 months and time to progression >3 months. The reports also indicate that gefitinib is generally well tolerated by patients of Asian origin and epidermal growth factor receptor (EGFR) mutations, which appear to be associated with gefitinib sensitivity, occur at a much higher rate in these patients compared with patients of non‐Asian origin. These reports also indicate that a high EGFRgene copy number may be associated with their response to gefitinib.

Conclusion:  Gefitinib appears to be a valid, efficacious, and generally well‐tolerated treatment option for patients of Asian origin with advanced NSCLC. It is possible that differences in EGFR mutation rates may underlie variations in response rates to gefitinib between Asian and non‐Asian patient populations. Further exploratory analyses conducted in prospective clinical trials are required to fully determine the role of EGFR mutations, a high EGFR gene copy number and other biomarkers in determining the response to gefitinib treatment.
Results of treatment of esophageal carcinoma in 110 patients in north‐west Iran
Authors: SOKOUTI Mohsen , MONTAZERI Vahid , ALIZADEH Mahasti
Published: June 2007

Background:  Esophageal carcinoma is one of the most common lethal malignancies in north and north‐west Iran. It is usually advanced in presentation and is rarely diagnosed in the early stages. The aim of this article is to describe the clinicopathological features and survival of esophageal carcinoma in the advanced and early stages.

Methods:  One hundred and ten patients (49 men and 61 women) with esophageal carcinoma treated by surgery and combination therapies in a referral hospital were studied over a 5‐year period. The clinicopathological features, treatment received, complications of the treatment and survival data of these patients and also the time of diagnosis, stage of cancer, demographic features, surgical therapy and survival were analyzed.

Results:  Among the 110 patients with esophageal cancer who were undergone surgery, there was none in stages 0 and 1. The frequency of patients in stages 2, 3, and 4 were 21%, 70% and 9%, respectively. Of the tumors, 87% were squamous cell carcinomas and 13% adenocarcinomas. Anastomotic leakage and pneumonia were the most common operative complications. The 5‐year survival rate in this study was 2.7%.

Conclusion:  Most of the esophageal cancers in north‐west Iran are detected in the late stages and the survival rate is lower than reported in other studies. Screening and education in order for early detection are important preventive interventions in this region.
HIV and Perceptions of Risky Behaviors: A Network Analysis Approach
Authors: Heaven Patrick , Connors John , Fenton Robert
Published: June 2007

This study examined the perceived causal structure of HIV infection. The respondents were 165 university undergraduates (61 males and 104 females). Multidimensional scaling analysis and network analysis (Knoke & Kuklinski, 1982; Lunt, 1991) were used, and the results indicated that the respondents were able to differentiate among a number of possible causes of HIV infection. Notably, it was found that the causes were viewed as being either distal or proximal and that three clusters of activity were regarded as being risky with respect to HIV infection. These were found to be differentially related to HIV infection, with several interconnections. The findings are discussed, and implications for safe sexual behaviors are noted.
Condom Use Assertiveness and the Stages of Change With Main and Other Partners1
Authors: Grimley Diane M. , Prochaska Gabrielle E. , Prochaska James O.
Published: June 2007

A measure assessing an individual's ability to assert the use of condoms was developed using, N= 248, heterosexually active college men and women. Both principal component analysis (PCA) and structural equation modeling (SEM) procedures were performed. External validity for the assertion for condom use measure was established by integrating the measure with the stages of change dimension from the transtheoretical model of behavior change. The transtheoretical model posits that both the cessation of high‐risk behaviors and the acquisition of health behaviors involve the progression through five stages of change: precontemplation, contemplation, preparation, action, and maintenance. The results indicated that individuals were further along in the stages of change for using condoms with a casual partner, as compared to a steady partner. The degree to which assertive condom use behavior was engaged in was related to an individual's stage of readiness for using condoms with the two types of partners. The utility of stage‐matched intervention strategies, as opposed to the action‐oriented approaches to modify high‐risk sexual behavior, is discussed.
Influences on Food Selection of Women on High‐ and Low‐Fat Diets
Authors: Green Pamela K. , Bowen Deborah J. , Kestin Mark , Feng Ziding
Published: June 2007

There is evidence that long‐term maintenance of a low‐fat diet reduces preference for high‐fat foods. Sensory evaluation of the taste of fat, and preference for high and low‐fat foods were studied in a group of former participants in a randomized dietary intervention trial aimed at lowering fat consumption. Intervention subjects consuming less than 25% of daily calories as fat and control subjects consuming more than 35% of daily calories as fat agreed to be in a “taste perception” study. In Study 1, subjects tasted 20 dairy solutions containing different levels of fat and sugar. Subjects rated the perceived intensity of fat taste, and of liking, for each of the solutions. In Study 2, subjects were asked to taste and rate 4 high‐fat and 4 low‐fat snack foods, and were then allowed to freely consume these foods in a preference test. Intervention and control subjects were similar in their sensory evaluation of the taste of fat in Study 1. In Study 2, intervention subjects reported a reduced hedonic rating of the taste of high‐fat snack foods compared to control subjects, yet intervention subjects consumed the same amount of high‐fat snack foods as control subjects. We conclude that a successful outcome in a dietary intervention may be due to social and cognitive factors, in addition to potential changes in hedonic response to fat.
Cardiac Transplantation: A Quarter Century of Progress
Authors: Thompson Mark E. , Shapiro Alvin P.
Published: June 2007

This article provides a review of the current status of cardiac transplantation, which offers the only viable alternative for the management of patients with refractory congestive heart failure. The criteria for recipient evaluation and selection are discussed. The major limitation to the number of potential recipients of cardiac transplantation is the availability of donors, numbering about 2000 per year. The current one‐year survival rate is approximately 80%, while the 5‐year survival rate is in excess of 70%. These numbers confirm the therapeutic benefit derived from cardiac transplantation, and are in marked contrast to the one‐year mortality rate of 30–60% experienced by patients with New York Heart Association class IV congestive heart failure. The long‐term complications of cardiac transplantation include acute and chronic rejection, infection, the side effects of immunosuppressive agents (including nephrotoxicity and hypertension), the development of neoplasms, and accelerated transplant coronary arteriopathy.

This paper also emphasizes the areas in which investigation into the behavioral aspects of cardiac transplantation may be directed, including: (a) study of the individual and group attitudes toward organ donation; (b) psychologic implications of mechanical circulatory support as an alternative to cardiac transplantation; (c) in the transplanted patient with a denervated heart there is the opportunity to study the interaction between the autonomic nervous system and behavioral stimuli; (d) the psychologic adaptation of the recipient to organ transplantation; (e) the role of educational programs designed to influence favorably the attitude of the general population toward organ transplantation; and (f) in the future, the psychologic aspects of xenograft transplantation as an alternative to homograft transplantation.
Behavioral Factors in Heart Transplantation: Quality of Life and Medical Compliance1
Authors: Dew Mary Amanda
Published: June 2007

The nature and quality of heart recipients' adaptation to transplant must be considered when evaluating the costs of utilizing this procedure. Little is known about the occurrence of clinically significant levels of psychiatric distress or other physical functional and psychosocial limitations in the long‐term following initial recovery. Most important, despite assertions that recipients' well‐being and psychosocial status are critical predictors of their medical compliance and hence, of the ultimate survival, systematic research to document such relationships is lacking. This article summarizes research on quality of life and medical compliance in transplantation, presents a conceptual framework for understanding interrelationships among such variables, and describes early results from a longitudinal study of heart transplant recipients followed during their first year after surgery. Findings indicated that psychological distress and psychosocial status early posttransplant predicted compliance levels in ensuing months; difficulties adhering to the medical regimen were, in turn, related to physical, mental, and social well‐being at subsequent follow‐up. Implications of these patterns of reciprocal effects are considered both for treatment and for refining conceptual models of adaptation to transplantation.
Social Stigma, HIV/AIDS Knowledge, and Sexual Risk1
Authors: Burkholder Gary J. , Harlow Lisa L. , Washkwich Jacque‐Lynne
Published: June 2007

A cross‐sectional study of 481 sexually active, heterosexual late adolescents showed that: (a) heterosexual people may be distancing themselves from HIV/AIDS because of its association with the gay community while also engaging in greater behavioral risk for HIV/AIDS; and (b) the ways a person comes to know about HIV/AIDS (perceived knowledge, passive classroom learning, media influence, and knowing people with HIV/AIDS) can be related to sexual risk behavior through the operation of two mediating variables, condom self‐efficacy and perceived HIV/AIDS risk. The variables studiedare closely linked with Stage 1 factors in the AIDS Risk Reduction Model. Implications for understanding how stigmatizing can affect behavior are discussed, as well as implications for education in HIV/AIDS related issues.
Impact of a Peer‐Led Stress Inoculation Training Intervention on State Anxiety and Heart Rate in College Students
Authors: Fontana Anne M. , Hyra Derek , Godfrey Lauren , Cermak Laurie
Published: June 2007

The purpose of the study was to examine the effectiveness of a preventive peer‐led stress management intervention, based on stress inoculation procedures, on physiological and psychological variables in college students. College students were randomly assigned to either a six‐session treatment intervention or a wait‐list control group. Blood pressure, heart rate, perceived severity of physical symptoms, and state‐anxiety levels were assessed at pretreatment, posttreatment, and a 6‐month follow‐up. At posttreatment, the treatment participants had lower heart rate and state‐anxiety levels than did controls. At follow‐up, the difference in heart rate level between the groups was maintained. The protective aspect of stress inoculation training and the applicability of a peer‐led treatment intervention at the college level are discussed.
Cigarette Smoking and Chewing‐Gum Use Among College Students
Authors: Britt Dana M. , Jr Frank L. Collins, , Cohen Lee M.
Published: June 2007

Smoking cessation treatment programs may be more successful if satisfactory behavioral alternatives for smoking were identified. Chewing gum has been identified as one such simple alternative reinforcer. Marketing trends encourage smokers to chew gum when they cannot smoke; however, there is little empirical research examining the smoking‐chewing gum relationship. The current study examines the relationship among cigarette smoking and chewing gum use in 584 college students. Analyses indicate that nonsmokers are more likely to chew gum than smokers. Additionally, the data suggest a dose‐dependent trend: the heavier smoker one is, the less likely one is to chew gum. Chewing gum may be a viable alternative reinforcer to cigarette smoking, particularly in situations where smoking is prohibited.
Symptoms of Anxiety and Depression as Risk Factors for Development of Asthma1
Authors: Jonas Bruce S. , Wagener Diane K. , Lando James F. , Feldman Jacob J.
Published: June 2007

To test the hypothesis that symptoms of anxiety and depression are associated with increased risk of developing asthma, a population‐based cohort of 5,23! baseline and non‐asthmatic persons aged 25 to 74 was followed for 13 years. The association between asthma incidence and anxiety and depression was analyzed using Cox proportional hazards regression. For nonsmokers and persons without respiratory symptoms or predicted‐to‐observed FEVI ratio less than 65% (FEV1 < 65%), high levels of anxiety and depression remained independent predictors of asthma. The effects of anxiety and depression were particularly strong among nonsmokers without baseline respiratory symptoms or FEVI < 65%. We hypothesize that the baseline presence of strong risk factors such as smoking, respiratory symptoms, or FEV1 < 65% may obscure the effects of anxiety and depression symptomatology on the subsequent development of asthma. These analyses point out the need to move toward more sophisticated stratified models in the study of psychological factors and asthma.
A Quantitative Study of the Accuracy of College Students' HIV Risk Estimates1
Authors: Pinkerton Steven D. , Wagner‐Raphael Lynne I. , Craun Catherine A. , Abramson Paul R.
Published: June 2007

A mathematical model of human immunodeficiency virus (HIV) transmission was used to investigate the ability of college students(N=162) to accurately estimate the risk of transmission for a variety of scenarios, which varied by HIV prevalence, number of sex partners, number of acts per partner, and the use of condoms. In addition, respondents' perceptions of their own lifetime risk of acquiring HIV were compared with the risk faced by similar referents. Participants badly overestimated the per‐act transmission probabilities; all of their estimates differed from corresponding epidemiological estimates by a factor of 10 or more. It appears that their inflated estimates of the cumulative probability of transmission for multiple acts of intercourse were driven by their excessive overestimates of per‐act transmission probabilities.
A Group‐Mediated Cognitive‐Behavioral intervention for Increasing Adherence to Physical Activity in Older Adults1
Authors: Brawley Lawrence R. , Rejeski W. Jack , Lutes Lesley
Published: June 2007

This study examined the efficacy of a group‐mediated cognitive behavioral intervention (GMCB) on adherence rates to physically active lifestyles in older adults. Sixty older adults were randomized to I of 3 groups: waiting list control (WLC), a standard physical activity program (SPA), or GMCB. The SPA and GMCB involved 6 months of combined center‐ and home‐based activity. Contact with participants was then terminated with a follow‐up assessment at 9 months. Results revealed that, at the 9‐month follow‐up the GMCB group had a higher frequency of weekly physical activity than the SPA group. At 6 months, both groups were more active, had higher aerobic power, and improved HRQL when compared with the control group.
The Magnification of Psychopathology Sequelae Associated With Multiple Chronic Medical Conditions 1
Authors: McCracken Laura M. , Gatchel Robert J.
Published: June 2007

Recent literature indicates that chronic temporomandibular disorders (TMD), as well as other chronic medical conditions, are associated with a high degree of concomitant psycho‐pathology. Patients with TMD have been found to evidence a higher distribution of depressive symptoms, as compared with the general population. Moreover, one study examined prevalence rates of psychological disorders for 50 chronic TMD patients and found that 86% of them were diagnosed with at least one Diagnostic and Statistical Manual of Mental Disorders (DSM) Axis I disorder; 46% received two or more Axis I diagnoses; and 40% met diagnostic criteria for a personality disorder. These high rates of psychiatric disorders far exceeded those for the general population, with a considerable disparity noted between the prevalence of major depression among TMD patients (74%) and the base rate of this disorder in the general population (5% to 26%).
The Coping Inventory for Stressful Situations: Factorial Structure and Associations With Personality Traits and Psychological Health1
Authors: Cosway Richard , Endler Norman S. , Sadler Andrew J. , Deary Ian J.
Published: June 2007

Principal components analyses on the Coping Inventory for Stressful Situations (C1SS; Endler & Parker, 1990a) were carried out for 730 Scottish doctors and farmers. Endler and Parker's three‐factor structure was supported both in the male and female subgroups and in the two occupational groups. Intercorrelations of the C1SS factors with personality factors of the NEO‐Five Factor Inventory and a self‐reported psychological distress scale, the General Health Questionaire‐28, provided predictive validity for the C1SS in the transactional model of stress.
The Influence of Traffic Congestion, Daily Hassles, and Trait Stress Susceptibility on State Driver Stress: An Interactive Perspective1
Authors: Hennessy Dwight A. , Wiesenthal David L. , Kohn Paul M.
Published: June 2007

State driver stress was measured in both low and high traffic congestion using cellular telephones. The contributions of time urgency, trait driver stress, and hassles were also examined. Drivers showed substantially more state driver stress under high than low congestion. Time urgency made a significant positive contribution to state driver stress at both congestion levels. Trait driver stress also contributed positively under low congestion. There was a significant hassles X trait stress interaction under high congestion. Hassles exposure moderately increased state driver stress for high trait stress drivers, but reduced state driver stress for medium and low trait stress drivers. These findings indicate that state driver stress is influenced by a combination of situational and personal factors, including factors external to the driving context.
Nonlinear Components of Ship Wake Waves
Authors: Soomere Tarmo
Published: June 2007

Nonlinear components of wakes from large high-speed ships at times carry a substantial part of the wake energy and behave completely differently compared to the classical Kelvin wave system. This overview makes an attempt to summarize the descriptions of nonlinear parts of a ship’s wake. For completeness, also the basic properties of the Kelvin wake are sketched. The central topic is the generation of solitons by ship motion both in channels and in unbounded sea areas. The discussion is mostly limited to disturbances on the surface of nonstratified water. The optional nonlinear components of the ship wake such as the very narrow V-like wake components, packets of monochromatic waves, ship-generated depression areas, and supercritical bores are also discussed. Specific features of solitonic ship waves and their interactions have numerous applications in naval and coastal engineering, and in adjacent areas of applied mechanics. An overview of the practical use of certain properties of phase shifts, and particularly high wave humps occurring during Mach reflection and nonlinear interaction of solitons in decreasing the wave resistance at supercritical speeds and in the freak wave theory, is also presented. The final part of the paper describes the results of studies of far-field properties of nonlinear wakes and possible consequences of the increase of local hydrodynamic activity. There are 263 references cited in this review article.
Three-dimensional finite element modeling of guided ultrasound wave propagation in intact and healing long bones
Authors: Protopappas Vasilios C. , Kourtis Iraklis C. , Kourtis Lampros C. , Malizos Konstantinos N. , Massalas Christos V. , Fotiadis Dimitrios I.
Published: June 2007

The use of guided waves has recently drawn significant interest in the ultrasonic characterization of bone aiming at supplementing the information provided by traditional velocity measurements. This work presents a three-dimensional finite element study of guided wave propagation in intact and healing bones. A model of the fracture callus was constructed and the healing course was simulated as a three-stage process. The dispersion of guided modes generated by a broadband 1-MHz excitation was represented in the time-frequency domain. Wave propagation in the intact bone model was first investigated and comparisons were then made with a simplified geometry using analytical dispersion curves of the tube modes. Then, the effect of callus consolidation on the propagation characteristics was examined. It was shown that the dispersion of guided waves was significantly influenced by the irregularity and anisotropy of the bone. Also, guided waves were sensitive to material and geometrical changes that take place during healing. Conversely, when the first-arriving signal at the receiver corresponded to a nondispersive lateral wave, its propagation velocity was almost unaffected by the elastic symmetry and geometry of the bone and also could not characterize the callus tissue throughout its thickness. In conclusion, guided waves can enhance the capabilities of ultrasonic evaluation.
Interactions of speaking condition and auditory feedback on vowel production in postlingually deaf adults with cochlear implants
Authors: Ménard Lucie , Polak Marek , Denny Margaret , Burton Ellen , Lane Harlan , Matthies Melanie L. , Marrone Nicole , Perkell Joseph S. , Tiede Mark , Vick Jennell
Published: June 2007

This study investigates the effects of speaking condition and auditory feedback on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels prior to implantation, and at one month and one year after implantation. There were three speaking conditions (clear, normal, and fast), and two feedback conditions after implantation (implant processor turned on and off). Ten normal-hearing controls were also recorded once. Vowel contrasts in the formant space (expressed in mels) were larger in the clear than in the fast condition, both for controls and for implant users at all three time samples. Implant users also produced differences in duration between clear and fast conditions that were in the range of those obtained from the controls. In agreement with prior work, the implant users had contrast values lower than did the controls. The implant users’ contrasts were larger with hearing on than off and improved from one month to one year postimplant. Because the controls and implant users responded similarly to a change in speaking condition, it is inferred that auditory feedback, although demonstrably important for maintaining normative values of vowel contrasts, is not needed to maintain the distinctiveness of those contrasts in different speaking conditions.
Phase velocity and normalized broadband ultrasonic attenuation in Polyacetal cuboid bone-mimicking phantoms
Authors: Lee Kang Il , Choi Min Joo
Published: June 2007

The variations of phase velocity and normalized broadband ultrasonic attenuation (nBUA) with porosity were investigated in Polyacetal cuboid bone-mimicking phantoms with circular cylindrical pores running normal to the surface along the three orthogonal axes. The frequency-dependent phase velocity and attenuation coefficient in the phantoms with porosities from 0% to 65.9% were measured from 0.65 to 1.10MHz. The results showed that the phase velocity at 880kHz decreased linearly with porosity, whereas the nBUA increased linearly with porosity. This study provides a useful insight into the relationships between ultrasonic properties and porosity in bone at porosities lower than 70%.
Observable parameters from multipath bottom reverberation in shallow water
Authors: Ainslie Michael A.
Published: June 2007

Multipath ocean reverberation originating from the seabed in shallow isovelocity water, with particular attention to its information content in the cylindrical spreading and mode stripping regions, is considered. The reverberation is evaluated using Weston’s flux integral method, both analytically with various simplifying approximations and numerically with all but one of these approximations rescinded. The functional form of the analytical solution is used to infer which physical seabed parameters can be extracted from measurements of reverberation. Coarse- and fine-grained sediments (sand and clay) are both considered. The main purpose of the numerical solutions is to check the accuracy of the analytical approximations; they also serve as a convenient surrogate for measured reverberation.
Psychophysical estimates of level-dependent best-frequency shifts in the apical region of the human basilar membrane
Authors: Lopez-Poveda Enrique A. , Barrios Luis F. , Alves-Pinto Ana
Published: June 2007

It is now undisputed that the best frequency (BF) of basal basilar-membrane (BM) sites shifts downwards as the stimulus level increases. The direction of the shift for apical sites is, by contrast, less well established. Auditory nerve studies suggest that the BF shifts in opposite directions for apical and basal BM sites with increasing stimulus level. This study attempts to determine if this is the case in humans. Psychophysical tuning curves (PTCs) were measured using forward masking for probe frequencies of 125, 250, 500, and 6000Hz. The level of a masker tone required to just mask a fixed low-level probe tone was measured for different masker-probe time intervals. The duration of the intervals was adjusted as necessary to obtain PTCs for the widest possible range of masker levels. The BF was identified from function fits to the measured PTCs and it almost always decreased with increasing level. This result is inconsistent with most auditory-nerve observations obtained from other mammals. Several explanations are discussed, including that it may be erroneous to assume that low-frequency PTCs reflect the tuning of apical BM sites exclusively and that the inherent frequency response of the inner hair cell may account for the discrepancy.
A Green’s function method for surface acoustic waves in functionally graded materials
Authors: Matsuda Osamu , Glorieux Christ
Published: June 2007

Acoustic wave propagation in anisotropic media with one-dimensional inhomogeneity is discussed. Using a Green’s function approach, the wave equation with inhomogeneous variation of elastic property and mass density is transformed into an integral equation, which is then solved numerically. The method is applied to find the dispersion relation of surface acoustic waves for a medium with continuously or discontinuously varying elastic property and mass density profiles.
Plasticity in vowel perception and production: A study of accent change in young adults
Authors: Evans Bronwen G. , Iverson Paul
Published: June 2007

This study investigated changes in vowel production and perception among university students from the north of England, as individuals adapt their accent from regional to educated norms. Subjects were tested in their production and perception at regular intervals over a period of 2years: before beginning university, 3months later, and at the end of their first and second years at university. At each testing session, subjects were recorded reading a set of experimental words and a short passage. Subjects also completed two perceptual tasks; they chose best exemplar locations for vowels embedded in either northern or southern English accented carrier sentences and identified words in noise spoken with either a northern or southern English accent. The results demonstrated that subjects at a late stage in their language development, early adulthood, changed their spoken accent after attending university. There were no reliable changes in perception over time, but there was evidence for a between-subjects link between production and perception; subjects chose similar vowels to the ones they produced, and subjects who had a more southern English accent were better at identifying southern English speech in noise.
Spectral weighting strategies for sentences measured by a correlational method
Authors: Calandruccio Lauren , Doherty Karen A.
Published: June 2007

Listeners’ ability to understand speech in adverse listening conditions is partially due to the redundant nature of speech. Natural redundancies are often lost or altered when speech is filtered, such as done in AI/SII experiments. It is important to study how listeners recognize speech when the speech signal is unfiltered and the entire broadband spectrum is present. A correlational method [R. A. Lutfi, J. Acoust. Soc. Am. 97, 1333–1334 (1995); V. M. Richards and S. Zhu, J. Acoust. Soc. Am. 95, 423–424 (1994)] has been used to determine how listeners use spectral cues to perceive nonsense syllables when the full speech spectrum is present [K. A. Doherty and C. W. Turner, J. Acoust. Soc. Am. 100, 3769–3773 (1996); C. W. Turner et al., J. Acoust. Soc. Am. 104, 1580–1585 (1998)]. The experiments in this study measured spectral-weighting strategies for more naturally occurring speech stimuli, specifically sentences, using a correlational method for normal-hearing listeners. Results indicate that listeners placed the greatest weight on spectral information within bands 2 and 5 (562–1113 and 2807–11000Hz), respectively. Spectral-weighting strategies for sentences were also compared to weighting strategies for nonsense syllables measured in a previous study (C. W. Turner et al., 1998). Spectral-weighting strategies for sentences were different from those reported for nonsense syllables.
Estimating the transition bandwidth between two auditory processes: Evidence for broadband auditory filters
Authors: Berg Bruce G.
Published: June 2007

A spectral discrimination task was used to estimate the frequency range over which information about the temporal envelope is consolidated. The standard consisted of n equal intensity, random phase sinusoids, symmetrically placed around a signal component. The signal was an intensity increment of the central sinusoid, which on average was 1000Hz. Pitch cues were degraded by randomly selecting the center frequency of the complex and single channel energy cues were degraded with a roving-level procedure. Stimulus bandwidth was controlled by varying the number of tones and the frequency separation between tones. For a fixed frequency separation, thresholds increased as n increased until a certain bandwidth was reached, beyond which thresholds decreased. This discontinuity in threshold functions suggests that different auditory processes predominate at different bandwidths, presumably an envelope analysis at bandwidths less than the breakpoint and across channel level comparisons for wider stimulus bandwidths. Estimates of the “transition bandwidth” for 46 listeners ranged from 100 to 1250Hz. The results are consistent with a peripheral filtering system having multiple filterbanks.
Wideband ipsilateral measurements of middle-ear muscle reflex thresholds in children and adults
Authors: Schairer Kim S. , Ellison John C. , Fitzpatrick Denis , Keefe Douglas H.
Published: June 2007

The goals of the current study were to: 1) evaluate the feasibility of a new wideband approach to measuring middle-ear muscle reflex (MEMR) status, and 2) to test the hypothesis that ipsilateral thresholds elicited with 1 or 2kHz tones and broadband noise activators on a wideband acoustic transfer function (WATF) system are lower than thresholds elicited on a clinical system. Clinical MEMR tests have limitations, including the need for high activator levels to elicit a shift in a narrowband probe (e.g., a 0.226 or 1kHz tone). Wideband MEMR tests using WATFs may elicit the reflex at lower levels because a wideband probe (click) is used and the threshold detection criterion can be wideband. Mean wideband MEMR thresholds across 40 normal-hearing adult ears were 2.2–4.0dB lower than clinical MEMR thresholds, depending on the activator and specific WATF test used (admittance magnitude or energy reflectance). Wideband MEMR has potential clinical utility beyond the adult population, including use in newborn and preschool hearing screenings. In a newborn hearing screening, for example, wideband MEMR could be completed with the same system as otoacoustic emissions. However, further investigations in infants and young children are needed.
Training humans in non-native phoneme perception using a monkey psychoacoustic procedure
Authors: Sinnott Joan M. , Gonzales Christopher L. , Masood Ambrin F. , Ishihara Toshimasa
Published: June 2007

Humans were trained to categorize problem non-native phonemes using an animal psychoacoustic procedure that trains monkeys to greater than 90% correct in phoneme identification [Sinnott and Gilmore, Percept. Psychophys. 66, 1341–1350 (2004)]. This procedure uses a manual left versus right response on a lever, a continuously repeated stimulus on each trial, extensive feedback for errors in the form of a repeated correction procedure, and training until asymptotic levels of performance. Here, Japanese listeners categorized the English liquid contrast /r-l/, and English listeners categorized the Middle Eastern dental-retroflex contrast /d-D/. Consonant-vowel stimuli were constructed using four talkers and four vowels. Native listeners and phoneme contrasts familiar to all listeners were included as controls. Responses were analyzed using percent correct, response time, and vowel context effects as measures. All measures indicated nativelike Japanese perception of /r-l/ after 32 daily training sessions, but this was not the case for English perception of /d-D/. Results are related to the concept of “robust” (more easily recovered) versus “fragile” (more easily lost) phonetic contrasts [Burnham, Appl. Psycholing. 7, 207–240 (1986)].
Numerical simulation of turbulence transition and sound radiation for flow through a rigid glottal model
Authors: Suh Jungsoo , Frankel Steven H.
Published: June 2007

Large eddy simulation (LES)-based computational aeroacoustics techniques were applied to a static model of the human glottis, idealized here as a planar channel with an orifice, to study flow-acoustic interactions related to speech. Rigid models of both converging and diverging glottal passages, each featuring a 20deg included angle and a minimal glottal diameter of 0.04cm, with an imposed transglottal pressure of 15cm H2O, were studied. The Favre-filtered compressible Navier-Stokes equations were integrated for this low-Mach-number flow using an additive semi-implicit Runge-Kutta method and a high-order compact finite-difference scheme with characteristic-based nonreflecting boundary conditions and a multiblock approach. Flow asymmetries related to the Coanda effect and transition to turbulence, as well as the far-field sound, were captured. Acoustic-analogy-based far-field sound predictions were compared with direct simulations and showed that dipole sources, arising from unsteady flow forces exerted on the glottal walls, are primarily responsible for the tonal sound observed in the divergent glottis case.
Reflection and transmission coefficients for guided waves reflected by defects in viscoelastic material plates
Authors: Hosten Bernard , Moreau Ludovic , Castaings Michel
Published: June 2007

The paper presents a Fourier transform-based signal processing procedure for quantifying the reflection and transmission coefficients and mode conversion of guided waves diffracted by defects in plates made of viscoelastic materials. The case of the S0 Lamb wave mode incident on a notch in a Perspex plate is considered. The procedure is applied to numerical data produced by a finite element code that simulates the propagation of attenuated guided modes and their diffraction by the notch, including mode conversion. Its validity and precision are checked by the way of the energy balance computation and by comparison with results obtained using an orthogonality relation-based processing method.
Quieting Weinberg 5C: A case study in hospital noise control
Authors: MacLeod Mark , Dunn Jeffrey , Busch-Vishniac Ilene J. , West James E. , Reedy Anita
Published: June 2007

Weinberg 5C of Johns Hopkins Hospital is a very noisy hematological cancer unit in a relatively new building of a large medical campus. Because of the requirements for dealing with immuno-suppressed patients, options for introducing sound absorbing materials are limited. In this article, a case study of noise control in a hospital, the sound environment in the unit before treatment is described, the chosen noise control approach of adding custom-made sound absorbing panels is presented, and the impact of the noise control installation is discussed. The treatment of Weinberg 5C involved creating sound absorbing panels of 2-in.-thick fiberglass wrapped in an anti-bacterial fabric. Wallpaper paste was used to hold the fabric to the backing of the fiberglass. Installation of these panels on the ceiling and high on corridor walls had a dramatic effect. The noise on the unit (as measured by the equivalent sound pressure level) was immediately reduced by 5dB(A) and the reverberation time dropped by a factor of over 2. Further, this drop in background noise and reverberation time understates the dramatic impact of the change. Surveys of staff and patients before and after the treatment indicated a change from viewing the unit as very noisy to a view of the unit as relatively quiet.
An exact noniterative linear method for locating sources based on measuring receiver arrival times
Authors: Militello C. , Buenafuente S. R.
Published: June 2007

In this paper an exact, linear solution to the source localization problem based on the time of arrival at the receivers is presented. The method is unique in that the source’s position can be obtained by solving a system of linear equations, three for a plane and four for a volume. This simplification means adding an additional receiver to the minimum mathematically required (3+1 in two dimensions and 4+1 in three dimensions). The equations are easily worked out for any receiver configuration and their geometrical interpretation is straightforward. Unlike other methods, the system of reference used to describe the receivers’ positions is completely arbitrary. The relationship between this method and previously published ones is discussed, showing how the present, more general, method overcomes nonlinearity and unknown dependency issues.
Causality and the velocity of acoustic signals in bubbly liquids
Authors: Orris Gregory J. , Dacol Dalcio K. , Nicholas Michael
Published: June 2007

Several versions of the dispersion formula governing the acoustic propagation in bubbly liquids are shown to exhibit acausal behavior. The cause of this behavior is due to the inappropriate application of a low frequency approximation in the determination of the extinction of the signal from radiative scattering. Using a corrected causal formula, several principles of wave propagation in bubbly media consistent with the general theory of wave propagation in dispersive media are demonstrated: There exist two precursors to any finite signal. Both propagate without regard to the source characteristics at velocities, frequencies, and amplitudes dependent wholly upon the characteristics of the medium supporting the wave motion. The first travels at the infinite frequency phase velocity that is coincident with the infinite frequency limit of the group velocity. That part of a propagating wave oscillating at the source frequency arrives at a time determined by the signal velocity. Analogous to the well known signal velocity of electromagnetic wave propagation in conducting media, the value of the signal velocity depends on the detailed structure of the dispersion formula in the complex frequency plane.