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Sample records for auditory fatigue

  1. Fatigue Modeling via Mammalian Auditory System for Prediction of Noise Induced Hearing Loss

    Directory of Open Access Journals (Sweden)

    Pengfei Sun

    2015-01-01

    Full Text Available Noise induced hearing loss (NIHL remains as a severe health problem worldwide. Existing noise metrics and modeling for evaluation of NIHL are limited on prediction of gradually developing NIHL (GDHL caused by high-level occupational noise. In this study, we proposed two auditory fatigue based models, including equal velocity level (EVL and complex velocity level (CVL, which combine the high-cycle fatigue theory with the mammalian auditory model, to predict GDHL. The mammalian auditory model is introduced by combining the transfer function of the external-middle ear and the triple-path nonlinear (TRNL filter to obtain velocities of basilar membrane (BM in cochlea. The high-cycle fatigue theory is based on the assumption that GDHL can be considered as a process of long-cycle mechanical fatigue failure of organ of Corti. Furthermore, a series of chinchilla experimental data are used to validate the effectiveness of the proposed fatigue models. The regression analysis results show that both proposed fatigue models have high corrections with four hearing loss indices. It indicates that the proposed models can accurately predict hearing loss in chinchilla. Results suggest that the CVL model is more accurate compared to the EVL model on prediction of the auditory risk of exposure to hazardous occupational noise.

  2. Fatigue Modeling via Mammalian Auditory System for Prediction of Noise Induced Hearing Loss.

    Science.gov (United States)

    Sun, Pengfei; Qin, Jun; Campbell, Kathleen

    2015-01-01

    Noise induced hearing loss (NIHL) remains as a severe health problem worldwide. Existing noise metrics and modeling for evaluation of NIHL are limited on prediction of gradually developing NIHL (GDHL) caused by high-level occupational noise. In this study, we proposed two auditory fatigue based models, including equal velocity level (EVL) and complex velocity level (CVL), which combine the high-cycle fatigue theory with the mammalian auditory model, to predict GDHL. The mammalian auditory model is introduced by combining the transfer function of the external-middle ear and the triple-path nonlinear (TRNL) filter to obtain velocities of basilar membrane (BM) in cochlea. The high-cycle fatigue theory is based on the assumption that GDHL can be considered as a process of long-cycle mechanical fatigue failure of organ of Corti. Furthermore, a series of chinchilla experimental data are used to validate the effectiveness of the proposed fatigue models. The regression analysis results show that both proposed fatigue models have high corrections with four hearing loss indices. It indicates that the proposed models can accurately predict hearing loss in chinchilla. Results suggest that the CVL model is more accurate compared to the EVL model on prediction of the auditory risk of exposure to hazardous occupational noise.

  3. Fatigue

    Science.gov (United States)

    ... Learn better ways to relax. Try yoga or meditation. Maintain a reasonable work and personal schedule. Change ... cause fatigue or drowsiness Feel sad or depressed Insomnia What to Expect at Your Office Visit Your ...

  4. Auditory hallucinations.

    Science.gov (United States)

    Blom, Jan Dirk

    2015-01-01

    Auditory hallucinations constitute a phenomenologically rich group of endogenously mediated percepts which are associated with psychiatric, neurologic, otologic, and other medical conditions, but which are also experienced by 10-15% of all healthy individuals in the general population. The group of phenomena is probably best known for its verbal auditory subtype, but it also includes musical hallucinations, echo of reading, exploding-head syndrome, and many other types. The subgroup of verbal auditory hallucinations has been studied extensively with the aid of neuroimaging techniques, and from those studies emerges an outline of a functional as well as a structural network of widely distributed brain areas involved in their mediation. The present chapter provides an overview of the various types of auditory hallucination described in the literature, summarizes our current knowledge of the auditory networks involved in their mediation, and draws on ideas from the philosophy of science and network science to reconceptualize the auditory hallucinatory experience, and point out directions for future research into its neurobiologic substrates. In addition, it provides an overview of known associations with various clinical conditions and of the existing evidence for pharmacologic and non-pharmacologic treatments.

  5. Auditory Hallucination

    Directory of Open Access Journals (Sweden)

    MohammadReza Rajabi

    2003-09-01

    Full Text Available Auditory Hallucination or Paracusia is a form of hallucination that involves perceiving sounds without auditory stimulus. A common is hearing one or more talking voices which is associated with psychotic disorders such as schizophrenia or mania. Hallucination, itself, is the most common feature of perceiving the wrong stimulus or to the better word perception of the absence stimulus. Here we will discuss four definitions of hallucinations:1.Perceiving of a stimulus without the presence of any subject; 2. hallucination proper which are the wrong perceptions that are not the falsification of real perception, Although manifest as a new subject and happen along with and synchronously with a real perception;3. hallucination is an out-of-body perception which has no accordance with a real subjectIn a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid, substantial, and located in external objective space. We are going to discuss it in details here.

  6. Fatigue (PDQ)

    Science.gov (United States)

    ... may include teaching the patient ways to increase energy and cope with fatigue in daily life. Exercise ... the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest ...

  7. Auditory Imagery: Empirical Findings

    Science.gov (United States)

    Hubbard, Timothy L.

    2010-01-01

    The empirical literature on auditory imagery is reviewed. Data on (a) imagery for auditory features (pitch, timbre, loudness), (b) imagery for complex nonverbal auditory stimuli (musical contour, melody, harmony, tempo, notational audiation, environmental sounds), (c) imagery for verbal stimuli (speech, text, in dreams, interior monologue), (d)…

  8. Chronic Fatigue Syndrome

    Science.gov (United States)

    Chronic fatigue syndrome (CFS) is a disorder that causes extreme fatigue. This fatigue is not the kind of tired feeling that ... activities. The main symptom of CFS is severe fatigue that lasts for 6 months or more. You ...

  9. Event-related potentials and cognitive performance in multiple sclerosis patients with fatigue.

    Science.gov (United States)

    Pokryszko-Dragan, Anna; Zagrajek, Mieszko; Slotwinski, Krzysztof; Bilinska, Malgorzata; Gruszka, Ewa; Podemski, Ryszard

    2016-09-01

    The aim of this study was to evaluate event-related potentials (ERP) and cognition in multiple sclerosis (MS) patients with regard to fatigue and disease-related variables. The study comprised 86 MS patients and 40 controls. Fatigue was assessed using the Fatigue Severity Scale (FSS/FSS-5) and the Modified Fatigue Impact Scale (MFIS/MFISmod). N200 and P300 components of auditory ERP were analyzed. Cognition was evaluated by means of Brief Repeatable Battery of Neuropsychological Tests (BRBNT). The results of ERP and BRBNT were compared between non-fatigued, moderately and severely fatigued MS patients and controls. P300 latency was significantly longer in the whole MS group and in the fatigued patients than in the controls. A positive correlation was found between P300 latency and MFIS/MFISmod results, independent from age and MS-related variables. The fatigued patients scored less than non-fatigued ones in tests evaluating memory, visuomotor abilities and attention. Results of these tests correlated significantly with fatigue measures, independently from MS-related variables. Fatigue in MS patients showed significant relationships with impairment within the memory and attention domains. Parameters of auditory ERP, as electrophysiological biomarkers of cognitive performance, were not independently linked to fatigue.

  10. Seafarer fatigue

    DEFF Research Database (Denmark)

    Jepsen, Jørgen Riis; Zhao, Zhiwei; van Leeuwen, Wessel M. A.

    2015-01-01

    Background: The consequences of fatigue for the health and safety of seafarers has caused concern in the industry and among academics, and indicates the importance of further research into risk factors and preventive interventions at sea. This review gives an overview of the key issues relating...

  11. Corrosion Fatigue

    Science.gov (United States)

    1981-10-01

    the applied protection systems, (2) crevices for moisture entrapment, (3) galvanic couples when steel or titanium fasteners are used, and (4) fatigue...Activ Material Structure Exposed Normal Environment* Unexposed Atmosphere Aluminum alloys Steel 1.25 2.0 4.0 Titanium " Magnesium " (4.0) (8.0) (10.0...APPRNDIX - Chromic Acid Anodizing The surface treatment consists in the following process : D egreasing with trichlorethylene vapor, * Pickling , Composition

  12. MANAGING FATIGUE IN SPORTS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Fatigue is a multifactorial process. Depletion of energy sources, including adenosine triphosphate (ATP), phosphocreatine (PCr), plus carbohydrates (CHO) like muscle glycogen and blood glucose can contribute to fatigue.

  13. Auditory Integration Training

    Directory of Open Access Journals (Sweden)

    Zahra Jafari

    2002-07-01

    Full Text Available Auditory integration training (AIT is a hearing enhancement training process for sensory input anomalies found in individuals with autism, attention deficit hyperactive disorder, dyslexia, hyperactivity, learning disability, language impairments, pervasive developmental disorder, central auditory processing disorder, attention deficit disorder, depressin, and hyperacute hearing. AIT, recently introduced in the United States, and has received much notice of late following the release of The Sound of a Moracle, by Annabel Stehli. In her book, Mrs. Stehli describes before and after auditory integration training experiences with her daughter, who was diagnosed at age four as having autism.

  14. Auditory Responses of Infants

    Science.gov (United States)

    Watrous, Betty Springer; And Others

    1975-01-01

    Forty infants, 3- to 12-months-old, participated in a study designed to differentiate the auditory response characteristics of normally developing infants in the age ranges 3 - 5 months, 6 - 8 months, and 9 - 12 months. (Author)

  15. Fatigue life extension

    Science.gov (United States)

    Matejczyk, D. E.; Lin, J.

    1985-01-01

    Potential fatigue rejuvenation processes were carried out on fatigue-damaged material both with and without observable surface-connected fatigue cracks. The fatigue life of fatigue-damaged MAR-M246(Hf)(DS), a directionally solidified nickel-base superalloy used in turbine airfoils, was extended by reheat treatment. The fatigue life of fatigue-cracked Inconel 718, a wrought nickel-base superalloy used in a wide variety of advanced rocket engine components, was extended by electron-beam welding to close off the surface-connected crack, followed by hot isostatic pressing and reheat treatment.

  16. Auditory and Visual Sensations

    CERN Document Server

    Ando, Yoichi

    2010-01-01

    Professor Yoichi Ando, acoustic architectural designer of the Kirishima International Concert Hall in Japan, presents a comprehensive rational-scientific approach to designing performance spaces. His theory is based on systematic psychoacoustical observations of spatial hearing and listener preferences, whose neuronal correlates are observed in the neurophysiology of the human brain. A correlation-based model of neuronal signal processing in the central auditory system is proposed in which temporal sensations (pitch, timbre, loudness, duration) are represented by an internal autocorrelation representation, and spatial sensations (sound location, size, diffuseness related to envelopment) are represented by an internal interaural crosscorrelation function. Together these two internal central auditory representations account for the basic auditory qualities that are relevant for listening to music and speech in indoor performance spaces. Observed psychological and neurophysiological commonalities between auditor...

  17. New Mom Fatigue

    Science.gov (United States)

    ... X Home > Pregnancy > Postpartum care > New mom fatigue New mom fatigue E-mail to a friend Please ... to your dashboard . You've welcomed your beautiful new baby to the world and have now brought ...

  18. Thermal Acoustic Fatigue Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — The Thermal Acoustic Fatigue Apparatus (TAFA) is a progressive wave tube test facility that is used to test structures for dynamic response and sonic fatigue due to...

  19. Optimal Fatigue Testing

    DEFF Research Database (Denmark)

    Faber, M. H.; Sørensen, John Dalsgaard; Kroon, I. B.

    1993-01-01

    This paper considers the reassessment of the reliability of tubular joints subjected to fatigue load. The reassessment is considered in two parts namely the task of utilizing new experimental data on fatigue life to update the reliability of the tubular joint ant the task of planning new fatigue ...

  20. Auditory evacuation beacons

    NARCIS (Netherlands)

    Wijngaarden, S.J. van; Bronkhorst, A.W.; Boer, L.C.

    2005-01-01

    Auditory evacuation beacons can be used to guide people to safe exits, even when vision is totally obscured by smoke. Conventional beacons make use of modulated noise signals. Controlled evacuation experiments show that such signals require explicit instructions and are often misunderstood. A new si

  1. Virtual Auditory Displays

    Science.gov (United States)

    2000-01-01

    timbre , intensity, distance, room modeling, radio communication Virtual Environments Handbook Chapter 4 Virtual Auditory Displays Russell D... musical note “A” as a pure sinusoid, there will be 440 condensations and rarefactions per second. The distance between two adjacent condensations or...and complexity are pitch, loudness, and timbre respectively. This distinction between physical and perceptual measures of sound properties is an

  2. The neglected neglect: auditory neglect.

    Science.gov (United States)

    Gokhale, Sankalp; Lahoti, Sourabh; Caplan, Louis R

    2013-08-01

    Whereas visual and somatosensory forms of neglect are commonly recognized by clinicians, auditory neglect is often not assessed and therefore neglected. The auditory cortical processing system can be functionally classified into 2 distinct pathways. These 2 distinct functional pathways deal with recognition of sound ("what" pathway) and the directional attributes of the sound ("where" pathway). Lesions of higher auditory pathways produce distinct clinical features. Clinical bedside evaluation of auditory neglect is often difficult because of coexisting neurological deficits and the binaural nature of auditory inputs. In addition, auditory neglect and auditory extinction may show varying degrees of overlap, which makes the assessment even harder. Shielding one ear from the other as well as separating the ear from space is therefore critical for accurate assessment of auditory neglect. This can be achieved by use of specialized auditory tests (dichotic tasks and sound localization tests) for accurate interpretation of deficits. Herein, we have reviewed auditory neglect with an emphasis on the functional anatomy, clinical evaluation, and basic principles of specialized auditory tests.

  3. Fatigue Damage in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben;

    1996-01-01

    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Fatigue failure is found to depend both on the total time under load and on the number of cycles.Recent accelerated fatigue research on wood is reviewed, and a discrepancy between...... failure explanation under fatigue and static load conditions is observed. In the present study small clear specimens of spruce are taken to failure in square wave formed fatigue loading at a stress excitation level corresponding to 80% of the short term strength. Four frequencies ranging from 0.01 Hz...... to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation between stiffness reduction...

  4. Auditory pathways: anatomy and physiology.

    Science.gov (United States)

    Pickles, James O

    2015-01-01

    This chapter outlines the anatomy and physiology of the auditory pathways. After a brief analysis of the external, middle ears, and cochlea, the responses of auditory nerve fibers are described. The central nervous system is analyzed in more detail. A scheme is provided to help understand the complex and multiple auditory pathways running through the brainstem. The multiple pathways are based on the need to preserve accurate timing while extracting complex spectral patterns in the auditory input. The auditory nerve fibers branch to give two pathways, a ventral sound-localizing stream, and a dorsal mainly pattern recognition stream, which innervate the different divisions of the cochlear nucleus. The outputs of the two streams, with their two types of analysis, are progressively combined in the inferior colliculus and onwards, to produce the representation of what can be called the "auditory objects" in the external world. The progressive extraction of critical features in the auditory stimulus in the different levels of the central auditory system, from cochlear nucleus to auditory cortex, is described. In addition, the auditory centrifugal system, running from cortex in multiple stages to the organ of Corti of the cochlea, is described.

  5. Animal models for auditory streaming.

    Science.gov (United States)

    Itatani, Naoya; Klump, Georg M

    2017-02-19

    Sounds in the natural environment need to be assigned to acoustic sources to evaluate complex auditory scenes. Separating sources will affect the analysis of auditory features of sounds. As the benefits of assigning sounds to specific sources accrue to all species communicating acoustically, the ability for auditory scene analysis is widespread among different animals. Animal studies allow for a deeper insight into the neuronal mechanisms underlying auditory scene analysis. Here, we will review the paradigms applied in the study of auditory scene analysis and streaming of sequential sounds in animal models. We will compare the psychophysical results from the animal studies to the evidence obtained in human psychophysics of auditory streaming, i.e. in a task commonly used for measuring the capability for auditory scene analysis. Furthermore, the neuronal correlates of auditory streaming will be reviewed in different animal models and the observations of the neurons' response measures will be related to perception. The across-species comparison will reveal whether similar demands in the analysis of acoustic scenes have resulted in similar perceptual and neuronal processing mechanisms in the wide range of species being capable of auditory scene analysis.This article is part of the themed issue 'Auditory and visual scene analysis'.

  6. Resizing Auditory Communities

    DEFF Research Database (Denmark)

    Kreutzfeldt, Jacob

    2012-01-01

    Heard through the ears of the Canadian composer and music teacher R. Murray Schafer the ideal auditory community had the shape of a village. Schafer’s work with the World Soundscape Project in the 70s represent an attempt to interpret contemporary environments through musical and auditory...... parameters highlighting harmonious and balanced qualities while criticizing the noisy and cacophonous qualities of modern urban settings. This paper present a reaffirmation of Schafer’s central methodological claim: that environments can be analyzed through their sound, but offers considerations on the role...... musicalized through electro acoustic equipment installed in shops, shopping streets, transit areas etc. Urban noise no longer acts only as disturbance, but also structure and shape the places and spaces in which urban life enfold. Based on research done in Japanese shopping streets and in Copenhagen the paper...

  7. Multiaxial fatigue low cycle fatigue testing

    Science.gov (United States)

    Zamrik, S. Y.

    1985-01-01

    Multiaxial testing methods are reviewed. Advantages and disadvantages of each type test is discussed. Significant multiaxial data available in the literature is analyzed. The yield theories are compared for multiaxial fatigue analysis.

  8. Behind the Scenes of Auditory Perception

    OpenAIRE

    Shamma, Shihab A.; Micheyl, Christophe

    2010-01-01

    Auditory scenes” often contain contributions from multiple acoustic sources. These are usually heard as separate auditory “streams”, which can be selectively followed over time. How and where these auditory streams are formed in the auditory system is one of the most fascinating questions facing auditory scientists today. Findings published within the last two years indicate that both cortical and sub-cortical processes contribute to the formation of auditory streams, and they raise importan...

  9. Chronic Fatigue Syndrome (CFS): Symptoms

    Science.gov (United States)

    ... CDC.gov . Chronic Fatigue Syndrome (CFS) Share Compartir Symptoms On this Page Primary Symptoms Other Symptoms What's ... a doctor distinguish CFS from other illnesses. Primary Symptoms As the name chronic fatigue syndrome suggests , fatigue ...

  10. Auditory and non-auditory effects of noise on health

    NARCIS (Netherlands)

    Basner, M.; Babisch, W.; Davis, A.; Brink, M.; Clark, C.; Janssen, S.A.; Stansfeld, S.

    2013-01-01

    Noise is pervasive in everyday life and can cause both auditory and non-auditory health eff ects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mec

  11. Partial Epilepsy with Auditory Features

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-07-01

    Full Text Available The clinical characteristics of 53 sporadic (S cases of idiopathic partial epilepsy with auditory features (IPEAF were analyzed and compared to previously reported familial (F cases of autosomal dominant partial epilepsy with auditory features (ADPEAF in a study at the University of Bologna, Italy.

  12. Word Recognition in Auditory Cortex

    Science.gov (United States)

    DeWitt, Iain D. J.

    2013-01-01

    Although spoken word recognition is more fundamental to human communication than text recognition, knowledge of word-processing in auditory cortex is comparatively impoverished. This dissertation synthesizes current models of auditory cortex, models of cortical pattern recognition, models of single-word reading, results in phonetics and results in…

  13. Examining fatigue in COPD

    DEFF Research Database (Denmark)

    Al-Shair, Khaled; Muellerova, Hana; Yorke, Janelle

    2012-01-01

    ABSTRACT: INTRODUCTION: Fatigue is a disruptive symptom that inhibits normal functional performance of COPD patients in daily activities. The availability of a short, simple, reliable and valid scale would improve assessment of the characteristics and influence of fatigue in COPD. METHODS......: At baseline, 2107 COPD patients from the ECLIPSE cohort completed the Functional Assessment of Chronic Illness Therapy Fatigue (FACIT-F) scale. We used well-structured classic method, the principal components analysis (PCA) and Rasch analysis for structurally examining the 13-item FACIT-F. RESULTS: Four items...... were less able to capture fatigue characteristics in COPD and were deleted. PCA was applied to the remaining 9 items of the modified FACIT-F and resulted in three interpretable dimensions: i) general (5 items); ii) functional ability (2 items); and iii) psychosocial fatigue (2 items). The modified...

  14. Compressive Fatigue in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben;

    1999-01-01

    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Small clear specimens of spruce are taken to failure in square wave formed fatigue loading at a stress excitation level corresponding to 80% of the short term strength. Four...... frequencies ranging from 0.01 Hz to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation...... is observed between stiffness reduction and accumulated creep. A failure model based on the total work during the fatigue life is rejected, and a modified work model based on elastic, viscous and non-recovered viscoelastic work is experimentally supported, and an explanation at a microstructural level...

  15. Peripheral Auditory Mechanisms

    CERN Document Server

    Hall, J; Hubbard, A; Neely, S; Tubis, A

    1986-01-01

    How weIl can we model experimental observations of the peripheral auditory system'? What theoretical predictions can we make that might be tested'? It was with these questions in mind that we organized the 1985 Mechanics of Hearing Workshop, to bring together auditory researchers to compare models with experimental observations. Tbe workshop forum was inspired by the very successful 1983 Mechanics of Hearing Workshop in Delft [1]. Boston University was chosen as the site of our meeting because of the Boston area's role as a center for hearing research in this country. We made a special effort at this meeting to attract students from around the world, because without students this field will not progress. Financial support for the workshop was provided in part by grant BNS- 8412878 from the National Science Foundation. Modeling is a traditional strategy in science and plays an important role in the scientific method. Models are the bridge between theory and experiment. Tbey test the assumptions made in experim...

  16. Experiences of Fatigue at Sea

    DEFF Research Database (Denmark)

    Zhao, Zhiwei; Jepsen, Jørgen Riis; Chen, Zhonglong;

    2016-01-01

    Fatigue has negative impacts on the general working population as well as on seafarers. In order to study seafarers’ fatigue, a questionnaire-base survey was conducted to gain information about potential risk factors for fatigue and construct indexes indicating fatigue. The study applies T...

  17. Prolonged unexplained fatigue in paediatrics

    NARCIS (Netherlands)

    Bakker, R.J.

    2010-01-01

    Prolonged Unexplained Fatigue in Paediatrics. Fatigue, as the result of mental or physical exertion, will disappear after rest, drinks and food. Fatigue as a symptom of illness will recover with the recovering of the illness. But when fatigue is ongoing for a long time, and not the result of exertio

  18. Fatigue Management (La Gestion de la Fatigue)

    Science.gov (United States)

    1991-12-01

    Management Pre’face Etant donne la tenidance de plus en plus marque ~e vets le maintien en service des aironefs au-delak des dates lintites...transport aircraft designed prototype sade its first flight one year about 20 years ago; from the fatigue point later. The results of the flight testing

  19. Fatigue evaluation algorithms: Review

    Energy Technology Data Exchange (ETDEWEB)

    Passipoularidis, V.A.; Broendsted, P.

    2009-11-15

    A progressive damage fatigue simulator for variable amplitude loads named FADAS is discussed in this work. FADAS (Fatigue Damage Simulator) performs ply by ply stress analysis using classical lamination theory and implements adequate stiffness discount tactics based on the failure criterion of Puck, to model the degradation caused by failure events in ply level. Residual strength is incorporated as fatigue damage accumulation metric. Once the typical fatigue and static properties of the constitutive ply are determined,the performance of an arbitrary lay-up under uniaxial and/or multiaxial load time series can be simulated. The predictions are validated against fatigue life data both from repeated block tests at a single stress ratio as well as against spectral fatigue using the WISPER, WISPERX and NEW WISPER load sequences on a Glass/Epoxy multidirectional laminate typical of a wind turbine rotor blade construction. Two versions of the algorithm, the one using single-step and the other using incremental application of each load cycle (in case of ply failure) are implemented and compared. Simulation results confirm the ability of the algorithm to take into account load sequence effects. In general, FADAS performs well in predicting life under both spectral and block loading fatigue. (author)

  20. Fatigue 󈨛. Volume 2,

    Science.gov (United States)

    1987-06-01

    fatigue cracks grown in a nominally elastic field. EXPERIMENTAL DETAILS A low alloy steel (QIN) with a composition closely similar to HY80 , i.e. 2.5...Prediction of Steel Cords - A. PRAKASH, 645 G.A. COSTELLO, R.M. SHEMENSKI AND D.K. KIM Effect of Hold Time on Fatigue of Lead Rich 655 PbSn Solder...S. VAYNMAN, M.E. FINE AND D.A. JEANNOTTE On Cleavage in Fatigue for Rail Steels - 667 ZHU DONG, CAI QIGONG and YAO HENG Influence of Cleavage on

  1. Metabolic Factors in Fatigue

    Institute of Scientific and Technical Information of China (English)

    Mark Hargreaves

    2006-01-01

    Increased non-oxidative and oxidative ATP production via metabolic pathways in skeletal muscle is essential for the maintenance of force and power production during exercise. However, substrate depletion and accumulation of metabolic byproducts are potential causes of fatigue. Reduced PCr availability can limit power production during sprint exercise, whereas carbohydrate depletion is a major limitation to endurance performance. During sprint exercise increased Pi and H+ may contribute to fatigue, and during prolonged strenuous exercise, the accumulation of NH3, reactive oxygen species, and heat can limit performance. Appropriate training programs and nutritional interventions are potential strategies to enhance fatigue resistance and exercise performance.

  2. Auditory short-term memory in the primate auditory cortex.

    Science.gov (United States)

    Scott, Brian H; Mishkin, Mortimer

    2016-06-01

    Sounds are fleeting, and assembling the sequence of inputs at the ear into a coherent percept requires auditory memory across various time scales. Auditory short-term memory comprises at least two components: an active ׳working memory' bolstered by rehearsal, and a sensory trace that may be passively retained. Working memory relies on representations recalled from long-term memory, and their rehearsal may require phonological mechanisms unique to humans. The sensory component, passive short-term memory (pSTM), is tractable to study in nonhuman primates, whose brain architecture and behavioral repertoire are comparable to our own. This review discusses recent advances in the behavioral and neurophysiological study of auditory memory with a focus on single-unit recordings from macaque monkeys performing delayed-match-to-sample (DMS) tasks. Monkeys appear to employ pSTM to solve these tasks, as evidenced by the impact of interfering stimuli on memory performance. In several regards, pSTM in monkeys resembles pitch memory in humans, and may engage similar neural mechanisms. Neural correlates of DMS performance have been observed throughout the auditory and prefrontal cortex, defining a network of areas supporting auditory STM with parallels to that supporting visual STM. These correlates include persistent neural firing, or a suppression of firing, during the delay period of the memory task, as well as suppression or (less commonly) enhancement of sensory responses when a sound is repeated as a ׳match' stimulus. Auditory STM is supported by a distributed temporo-frontal network in which sensitivity to stimulus history is an intrinsic feature of auditory processing. This article is part of a Special Issue entitled SI: Auditory working memory.

  3. Auditory display as a prosthetic hand sensory feedback for reaching and grasping tasks.

    Science.gov (United States)

    Gonzalez, Jose; Suzuki, Hiroyuki; Natsumi, Nakayama; Sekine, Masashi; Yu, Wenwei

    2012-01-01

    Upper limb amputees have to rely extensively on visual feedback in order to monitor and manipulate successfully their prosthetic device. This situation leads to high consciousness burden, which generates fatigue and frustration. Therefore, in order to enhance motor-sensory performance and awareness, an auditory display was used as a sensory feedback system for the prosthetic hand's spatio-temporal and force information in a complete reaching and grasping setting. The main objective of this study was to explore the effects of using the auditory display to monitor the prosthetic hand during a complete reaching and grasping motion. The results presented in this paper point out that the usage of an auditory display to monitor and control a robot hand improves the temporal and grasping performance greatly, while reducing mental effort and improving their confidence.

  4. Auditory Neuropathy - A Case of Auditory Neuropathy after Hyperbilirubinemia

    Directory of Open Access Journals (Sweden)

    Maliheh Mazaher Yazdi

    2007-12-01

    Full Text Available Background and Aim: Auditory neuropathy is an hearing disorder in which peripheral hearing is normal, but the eighth nerve and brainstem are abnormal. By clinical definition, patient with this disorder have normal OAE, but exhibit an absent or severely abnormal ABR. Auditory neuropathy was first reported in the late 1970s as different methods could identify discrepancy between absent ABR and present hearing threshold. Speech understanding difficulties are worse than can be predicted from other tests of hearing function. Auditory neuropathy may also affect vestibular function. Case Report: This article presents electrophysiological and behavioral data from a case of auditory neuropathy in a child with normal hearing after bilirubinemia in a 5 years follow-up. Audiological findings demonstrate remarkable changes after multidisciplinary rehabilitation. Conclusion: auditory neuropathy may involve damage to the inner hair cells-specialized sensory cells in the inner ear that transmit information about sound through the nervous system to the brain. Other causes may include faulty connections between the inner hair cells and the nerve leading from the inner ear to the brain or damage to the nerve itself. People with auditory neuropathy have OAEs response but absent ABR and hearing loss threshold that can be permanent, get worse or get better.

  5. Fatigue Evaluation Algorithms: Review

    DEFF Research Database (Denmark)

    Passipoularidis, Vaggelis; Brøndsted, Povl

    A progressive damage fatigue simulator for variable amplitude loads named FADAS is discussed in this work. FADAS (Fatigue Damage Simulator) performs ply by ply stress analysis using classical lamination theory and implements adequate stiffness discount tactics based on the failure criterion of Puck......, to model the degradation caused by failure events in ply level. Residual strength is incorporated as fatigue damage accumulation metric. Once the typical fatigue and static properties of the constitutive ply are determined,the performance of an arbitrary lay-up under uniaxial and/or multiaxial load time...... blade construction. Two versions of the algorithm, the one using single-step and the other using incremental application of each load cycle (in case of ply failure) are implemented and compared. Simulation results confirm the ability of the algorithm to take into account load sequence effects...

  6. Fatigue in soccer

    DEFF Research Database (Denmark)

    Mohr, Magni; Krustrup, Peter; Bangsbo, Jens

    2005-01-01

    This review describes when fatigue may develop during soccer games and the potential physiological mechanisms that cause fatigue in soccer. According to time?-?motion analyses and performance measures during match-play, fatigue or reduced performance seems to occur at three different stages......, acidity or the breakdown of creatine phosphate. Instead, it may be related to disturbances in muscle ion homeostasis and an impaired excitation of the sarcolemma. Soccer players' ability to perform maximally is inhibited in the initial phase of the second half, which may be due to lower muscle...... concentrations in a considerable number of individual muscle fibres. In a hot and humid environment, dehydration and a reduced cerebral function may also contribute to the deterioration in performance. In conclusion, fatigue or impaired performance in soccer occurs during various phases in a game, and different...

  7. Hyperthermia and fatigue

    DEFF Research Database (Denmark)

    Nybo, Lars

    2008-01-01

    of the cardiovascular function, which eventually reduces arterial oxygen delivery to the exercising muscles. Accordingly, aerobic energy turnover is impaired and anaerobic metabolism provokes peripheral fatigue. In contrast, metabolic disturbances of muscle homeostasis are less important during prolonged exercise......The present review addresses mechanisms of importance for hyperthermia-induced fatigue during short intense activities and prolonged exercise in the heat. Inferior performance during physical activities with intensities that elicit maximal oxygen uptake is to a large extent related to perturbation...... of the dopaminergic system, but may primarily relate to inhibitory signals from the hypothalamus arising secondary to an increase in brain temperature. Fatigue is an integrated phenomenon, and psychological factors, including the anticipation of fatigue, should not be neglected and the interaction between central...

  8. Auditory Processing Disorder (For Parents)

    Science.gov (United States)

    ... CAPD often have trouble maintaining attention, although health, motivation, and attitude also can play a role. Auditory ... programs. Several computer-assisted programs are geared toward children with APD. They mainly help the brain do ...

  9. The Recognition Of Fatigue

    DEFF Research Database (Denmark)

    Elsass, Peter; Jensen, Bodil; Mørup, Rikke;

    2007-01-01

    Elsass P., Jensen B., Morup R., Thogersen M.H. (2007). The Recognition Of Fatigue: A qualitative study of life-stories from rehabilitation clients. International Journal of Psychosocial Rehabilitation. 11 (2), 75-87......Elsass P., Jensen B., Morup R., Thogersen M.H. (2007). The Recognition Of Fatigue: A qualitative study of life-stories from rehabilitation clients. International Journal of Psychosocial Rehabilitation. 11 (2), 75-87...

  10. Fatigue Crack Topography.

    Science.gov (United States)

    1984-01-01

    evaluating ciack initiation time and crack propagation, prgram I was used for performing the major fatigue test with the aircraft structure. In...advantage to begin with the end of the fracture, this is especially so in the case of the quantitative evaluation of striations. The overload fracture...Select the Measuring Line for Quantitative Evaluation Actually, the fatigue fracture should be inspected completely from the point of origin to the

  11. Driver Fatigue Features Extraction

    Directory of Open Access Journals (Sweden)

    Gengtian Niu

    2014-01-01

    Full Text Available Driver fatigue is the main cause of traffic accidents. How to extract the effective features of fatigue is important for recognition accuracy and traffic safety. To solve the problem, this paper proposes a new method of driver fatigue features extraction based on the facial image sequence. In this method, first, each facial image in the sequence is divided into nonoverlapping blocks of the same size, and Gabor wavelets are employed to extract multiscale and multiorientation features. Then the mean value and standard deviation of each block’s features are calculated, respectively. Considering the facial performance of human fatigue is a dynamic process that developed over time, each block’s features are analyzed in the sequence. Finally, Adaboost algorithm is applied to select the most discriminating fatigue features. The proposed method was tested on a self-built database which includes a wide range of human subjects of different genders, poses, and illuminations in real-life fatigue conditions. Experimental results show the effectiveness of the proposed method.

  12. Mental workload measurement: Event-related potentials and ratings of workload and fatigue

    Science.gov (United States)

    Biferno, M. A.

    1985-01-01

    Event-related potentials were elicited when a digitized word representing a pilot's call-sign was presented. This auditory probe was presented during 27 workload conditions in a 3x3x3 design where the following variables were manipulated: short-term load, tracking task difficulty, and time-on-task. Ratings of workload and fatigue were obtained between each trial of a 2.5-hour test. The data of each subject were analyzed individually to determine whether significant correlations existed between subjective ratings and ERP component measures. Results indicated that a significant number of subjects had positive correlations between: (1) ratings of workload and P300 amplitude, (2) ratings of workload and N400 amplitude, and (3) ratings of fatigue and P300 amplitude. These data are the first to show correlations between ratings of workload or fatigue and ERP components thereby reinforcing their validity as measures of mental workload and fatigue.

  13. Auditory Neuropathy in Two Patients with Generalized Neuropathic Disorder: A Case Report

    Directory of Open Access Journals (Sweden)

    P Ahmadi

    2008-06-01

    Full Text Available Background: Although it is not a new disorder, in recent times we have attained a greater understanding of auditory neuropathy (AN. In this type of hearing impairment, cochlear hair cells function but AN victims suffer from disordered neural transmission in the auditory pathway. The auditory neuropathy result profile often occurs as a part of that of the generalized neuropathic disorders, indicated in approximately 30-40% of all reported auditory neuropathy/auditory dyssynchrony (AN/AD cases, with approximately 80% of patients reporting symptom onset over the age of 15 years. In the present report, the results of audiologic tests (behavioral, physiologic and evoked potentials on two young patients with generalized neuropathy are discussed.Case report: Two brothers, 26 and 17 years old, presented with speech perception weakness and movement difficulties that started at 12 years of age and progressed as time passed. In their last examination, there was a moderate to severe flat audiogram in the older patient and mild low tone loss in the younger one. The major difficulty of the patients was severe speech perception impairment that was not compatible with their hearing thresholds. Paresthesia, sural muscle contraction and pain, and balance disorder were the first symptoms of the older brother. Now he can only move with crutches and his finger muscle tonicity has decreased remarkably, with marked fatigue after a short period of walking. Increasing movement difficulties were noted in his last visit. Visual neuropathy had been reported in repeated visual system examinations for the older brother, with similar, albeit less severe, symptoms in the younger brother.In the present study of these patients, behavioral investigations included pure-tone audiometry and speech discrimination scoring. Physiologic studies consisted Transient Evoked Otoacoustic Emission (TEOAE and acoustic reflexes. Electrophysiologic auditory tests were also performed to determine

  14. Thermal fatigue of beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Deksnis, E.; Ciric, D.; Falter, H. [JET Joint undertaking, Abingdon (United Kingdom)] [and others

    1995-09-01

    Thermal fatigue life of S65c beryllium castellated to a geometry 6 x 6 x (8-10)mm deep has been tested for steady heat fluxes of 3 MW/m{sup 2} to 5 MW/m{sup 2} and under pulsed heat fluxes (10-20 MW/m{sup 2}) for which the time averaged heat flux is 5 MW/m{sup 2}. These tests were carried out in the JET neutral beam test facility A test sequence with peak surface temperatures {le} 600{degrees}C produced no visible fatigue cracks. In the second series of tests, with T{sub max} {le} 750{degrees}C evidence for fatigue appeared after a minimum of 1350 stress cycles. These fatigue data are discussed in view of the observed lack of thermal fatigue in JET plasma operations with beryllium PFC. JET experience with S65b and S65c is reviewed; recent operations with {Phi} = 25 MW/m{sup 2} and sustained melting/resolidification are also presented. The need for a failure criterion for finite element analyses of Be PFC lifetimes is discussed.

  15. Fatigue design 1998

    Energy Technology Data Exchange (ETDEWEB)

    Marquis, G.; Solin, J. [eds.] [VTT Manufacturing Technology, Espoo (Finland)

    1998-12-31

    These preprints contain the presentations to be delivered at the Fatigue Design 1998 symposium held on May 26-29, 1998 in Espoo. Fatigue Design 1998 is the tenth in a series of VTT symposia addressing the challenge of fatigue of materials, components and structures. Previous international events were in 1992 and 1995. The key theme of the current meeting is `RELIABILITY`. The two volumes (VTT symposium 181-182) represent 56 contributions by authors representing 26 countries. Emphasis has been given to application oriented research topics that report new technologies, new uses of existing methods and case studies. The objective of the symposium is to bring together researchers and engineers to share experiences and new innovations in designing reliable components to resist alternating loads. (orig.)

  16. Fatigue in primary biliary cirrhosis

    OpenAIRE

    Cauch-Dudek, K; Abbey, S; Stewart, D; Heathcote, E

    1998-01-01

    Background—Fatigue is a frequent and debilitating symptom in patients with primary biliary cirrhosis (PBC). 
Aims—To study fatigue in relation to sleep, depression, and liver disease severity. 
Methods—Patients with PBC completed validated self report questionnaires measuring fatigue, sleep quality, depression, and functional capacity. Verbally reported fatigue and observer rated measure of depression and ursodeoxycholic acid (UDCA) use were recorded. Liver biochemistry and ...

  17. Auditory Hallucinations in Acute Stroke

    Directory of Open Access Journals (Sweden)

    Yair Lampl

    2005-01-01

    Full Text Available Auditory hallucinations are uncommon phenomena which can be directly caused by acute stroke, mostly described after lesions of the brain stem, very rarely reported after cortical strokes. The purpose of this study is to determine the frequency of this phenomenon. In a cross sectional study, 641 stroke patients were followed in the period between 1996–2000. Each patient underwent comprehensive investigation and follow-up. Four patients were found to have post cortical stroke auditory hallucinations. All of them occurred after an ischemic lesion of the right temporal lobe. After no more than four months, all patients were symptom-free and without therapy. The fact the auditory hallucinations may be of cortical origin must be taken into consideration in the treatment of stroke patients. The phenomenon may be completely reversible after a couple of months.

  18. Fatigue approach for addressing environmental effects in fatigue usage calculation

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelm, Paul; Rudolph, Juergen [AREVA GmbH, Erlangen (Germany); Steinmann, Paul [Erlangen-Nuremberg Univ., erlangen (Germany). Chair of Applied Mechanics

    2015-04-15

    Laboratory tests consider simple trapezoidal, triangle, and sinusoidal signals. However, actual plant components are characterized by complex loading patterns and periods of holds. Fatigue tests in water environment show, that the damage from a realistic strain variation or the presence of hold-times within cyclic loading results in an environmental reduction factor (Fen) only half that of a simple waveform. This study proposes a new fatigue approach for addressing environmental effects in fatigue usage calculation for class 1 boiler and pressure vessel reactor components. The currently accepted method of fatigue assessment has been used as a base model and all cycles, which have been comparable with realistic fatigue tests, have been excluded from the code-based fatigue calculation and evaluated directly with the test data. The results presented show that the engineering approach can successfully be integrated in the code-based fatigue assessment. The cumulative usage factor can be reduced considerably.

  19. Fatigue modelling for gas nitriding

    Directory of Open Access Journals (Sweden)

    H. Weil

    2016-10-01

    Full Text Available The present study aims to develop an algorithm able to predict the fatigue lifetime of nitrided steels. Linear multi-axial fatigue criteria are used to take into account the gradients of mechanical properties provided by the nitriding process. Simulations on rotating bending fatigue specimens are made in order to test the nitrided surfaces. The fatigue model is applied to the cyclic loading of a gear from a simulation using the finite element software Ansys. Results show the positive contributions of nitriding on the fatigue strength

  20. Muscle Deoxygenation Causes Muscle Fatigue

    Science.gov (United States)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D.

    1999-01-01

    Muscle fatigue is a common musculoskeletal disorder in the work place, and may be a harbinger for more disabling cumulative trauma disorders. Although the cause of fatigue is multifactorial, reduced blood flow and muscle oxygenation may be the primary factor in causing muscle fatigue during low intensity muscle exertion. Muscle fatigue is defined as a reduction in muscle force production, and also occurs among astronauts who are subjected to postural constraints while performing lengthy, repetitive tasks. The objectives of this research are to: 1) develop an objective tool to study the role of decreased muscle oxygenation on muscle force production, and 2) to evaluate muscle fatigue during prolonged glovebox work.

  1. Incompatibility and Mental Fatigue

    Science.gov (United States)

    Herzog, Thomas R.; Hayes, Lauren J.; Applin, Rebecca C.; Weatherly, Anna M.

    2011-01-01

    A straightforward prediction from attention restoration theory is that the level of incompatibility in a person's life should be positively correlated with that person's level of mental (or directed attention) fatigue. The authors tested this prediction by developing a new self-report measure of incompatibility in which they attempted to isolate…

  2. Cumulative fatigue damage models

    Science.gov (United States)

    Mcgaw, Michael A.

    1988-01-01

    The problem of calculating expected component life under fatigue loading conditions is complicated by the fact that component loading histories contain, in many cases, cyclic loads of widely varying amplitudes. In such a case a cumulative damage model is required, in addition to a fatigue damage criterion, or life relationship, in order to compute the expected fatigue life. The traditional cumulative damage model used in design is the linear damage rule. This model, while being simple to use, can yield grossly unconservative results under certain loading conditions. Research at the NASA Lewis Research Center has led to the development of a nonlinear cumulative damage model, named the double damage curve approach (DDCA), that has greatly improved predictive capability. This model, which considers the life (or loading) level dependence of damage evolution, was applied successfully to two polycrystalline materials, 316 stainless steel and Haynes 188. The cumulative fatigue behavior of the PWA 1480 single-crystal material is currently being measured to determine the applicability of the DDCA for this material.

  3. Caffeine, fatigue, and cognition

    NARCIS (Netherlands)

    Lorist, MM; Tops, M

    2003-01-01

    Effects of caffeine and fatigue are discussed with special attention to adenosine-dopamine interactions. Effects of caffeine on human cognition are diverse. Behavioural measurements indicate a general improvement in the efficiency of information processing after caffeine, while the EEG data support

  4. Determinants of fatigue and stress

    Directory of Open Access Journals (Sweden)

    Brähler Elmar

    2011-07-01

    Full Text Available Abstract Background Fatigue can be triggered by previous perceived stress which may lead to impairment of performance and function. The purpose of the study was to investigate the relationship between fatigue and perceived stress. Method Health determinants including sociodemographic factors for associations between fatigue and perceived stress in the general population (N = 2,483 are outlined. Fatigue and stress were assessed with the Chalder Fatigue Scale (CFS and the Perceived Stress Questionnaire (PSQ. Results Within the general population, 25.9% of male and 34.5% of female respondents reported moderate fatigue during the last six months; 9.7% of subjects reported substantial fatigue lasting six months or longer. An adjusted regression analysis (R2corr = .28, p Conclusion We conclude that the two conditions overlap most in terms of socio-economic status and self-perceived health status.

  5. Fatigue Strength of Weathering Steel

    Directory of Open Access Journals (Sweden)

    Ludvík KUNZ

    2012-03-01

    Full Text Available Fatigue behaviour of Atmofix 52 steel (comparable to COR-TENâ steel exposed to atmospheric corrosion for 20 years was investigated. S-N curves for load symmetrical cycling and cycling with stress ratio R = 0 were determined on specimens detracted from a failed transmission tower. The data were compared with those on material without a rust layer. The fracture surfaces and, in particular, the sites of fatigue crack initiation were analyzed. Substantial decrease of fatigue life and fatigue limit due to corrosion exposition was found. Based on observation of surface layer with corrosion products and on fractographic analysis of failed specimens conclusions on fatigue damage mechanism were drawn. No grain boundary corrosion, which can be responsible for fatigue crack initiation, was observed. Initiation of fatigue cracks was related to surface roughness and took place exclusively on corrosion dimples.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1335

  6. Auditory and audio-visual processing in patients with cochlear, auditory brainstem, and auditory midbrain implants: An EEG study.

    Science.gov (United States)

    Schierholz, Irina; Finke, Mareike; Kral, Andrej; Büchner, Andreas; Rach, Stefan; Lenarz, Thomas; Dengler, Reinhard; Sandmann, Pascale

    2017-04-01

    There is substantial variability in speech recognition ability across patients with cochlear implants (CIs), auditory brainstem implants (ABIs), and auditory midbrain implants (AMIs). To better understand how this variability is related to central processing differences, the current electroencephalography (EEG) study compared hearing abilities and auditory-cortex activation in patients with electrical stimulation at different sites of the auditory pathway. Three different groups of patients with auditory implants (Hannover Medical School; ABI: n = 6, CI: n = 6; AMI: n = 2) performed a speeded response task and a speech recognition test with auditory, visual, and audio-visual stimuli. Behavioral performance and cortical processing of auditory and audio-visual stimuli were compared between groups. ABI and AMI patients showed prolonged response times on auditory and audio-visual stimuli compared with NH listeners and CI patients. This was confirmed by prolonged N1 latencies and reduced N1 amplitudes in ABI and AMI patients. However, patients with central auditory implants showed a remarkable gain in performance when visual and auditory input was combined, in both speech and non-speech conditions, which was reflected by a strong visual modulation of auditory-cortex activation in these individuals. In sum, the results suggest that the behavioral improvement for audio-visual conditions in central auditory implant patients is based on enhanced audio-visual interactions in the auditory cortex. Their findings may provide important implications for the optimization of electrical stimulation and rehabilitation strategies in patients with central auditory prostheses. Hum Brain Mapp 38:2206-2225, 2017. © 2017 Wiley Periodicals, Inc.

  7. Auditory Hallucinations Nomenclature and Classification

    NARCIS (Netherlands)

    Blom, Jan Dirk; Sommer, Iris E. C.

    2010-01-01

    Introduction: The literature on the possible neurobiologic correlates of auditory hallucinations is expanding rapidly. For an adequate understanding and linking of this emerging knowledge, a clear and uniform nomenclature is a prerequisite. The primary purpose of the present article is to provide an

  8. Nigel: A Severe Auditory Dyslexic

    Science.gov (United States)

    Cotterell, Gill

    1976-01-01

    Reported is the case study of a boy with severe auditory dyslexia who received remedial treatment from the age of four and progressed through courses at a technical college and a 3-year apprenticeship course in mechanics by the age of eighteen. (IM)

  9. Chronic fatigue and chronic fatigue syndrome: shifting boundaries and attributions.

    Science.gov (United States)

    Lloyd, A R

    1998-09-28

    The subjective symptom of "fatigue" is one of the most widespread in the general population and is a major source of healthcare utilization. Prolonged fatigue is often associated with neuropsychological and musculoskeletal symptoms that form the basis of several syndromal diagnoses including chronic fatigue syndrome, fibromyalgia, and neurasthenia, and is clearly not simply the result of a lack of force generation from the muscle. Current epidemiologic research in this area relies predominantly on self-report data to document the prevalence and associations of chronic fatigue. Of necessity, this subjective data source gives rise to uncertain diagnostic boundaries and consequent divergent epidemiologic, clinical, and pathophysiologic research findings. This review will highlight the impact of the case definition and ascertainment methods on the varying prevalence estimates of chronic fatigue syndrome and patterns of reported psychological comorbidty. It will also evaluate the evidence for a true postinfective fatigue syndrome.

  10. Helicopter Fatigue Design Guide

    Science.gov (United States)

    1983-11-01

    de nouveaux materiaux ou technologies accentue I’importance que presente pour les forces de I’O.T.A.N. ce probleme de la maitrise des phenomenes de...fatigue interessant les helicopteres. La commission Structures et Materiaux de I’AGARD a ete conduite a proposer et developper une serie de reflexions...service life for the suspension components due to their vulnerabihty to darnage at high speeds. Spectrum No. 2 led to limitations being applied to

  11. Adaptation in the auditory system: an overview

    Directory of Open Access Journals (Sweden)

    David ePérez-González

    2014-02-01

    Full Text Available The early stages of the auditory system need to preserve the timing information of sounds in order to extract the basic features of acoustic stimuli. At the same time, different processes of neuronal adaptation occur at several levels to further process the auditory information. For instance, auditory nerve fiber responses already experience adaptation of their firing rates, a type of response that can be found in many other auditory nuclei and may be useful for emphasizing the onset of the stimuli. However, it is at higher levels in the auditory hierarchy where more sophisticated types of neuronal processing take place. For example, stimulus-specific adaptation, where neurons show adaptation to frequent, repetitive stimuli, but maintain their responsiveness to stimuli with different physical characteristics, thus representing a distinct kind of processing that may play a role in change and deviance detection. In the auditory cortex, adaptation takes more elaborate forms, and contributes to the processing of complex sequences, auditory scene analysis and attention. Here we review the multiple types of adaptation that occur in the auditory system, which are part of the pool of resources that the neurons employ to process the auditory scene, and are critical to a proper understanding of the neuronal mechanisms that govern auditory perception.

  12. Auditory adaptation improves tactile frequency perception.

    Science.gov (United States)

    Crommett, Lexi E; Pérez-Bellido, Alexis; Yau, Jeffrey M

    2017-01-11

    Our ability to process temporal frequency information by touch underlies our capacity to perceive and discriminate surface textures. Auditory signals, which also provide extensive temporal frequency information, can systematically alter the perception of vibrations on the hand. How auditory signals shape tactile processing is unclear: perceptual interactions between contemporaneous sounds and vibrations are consistent with multiple neural mechanisms. Here we used a crossmodal adaptation paradigm, which separated auditory and tactile stimulation in time, to test the hypothesis that tactile frequency perception depends on neural circuits that also process auditory frequency. We reasoned that auditory adaptation effects would transfer to touch only if signals from both senses converge on common representations. We found that auditory adaptation can improve tactile frequency discrimination thresholds. This occurred only when adaptor and test frequencies overlapped. In contrast, auditory adaptation did not influence tactile intensity judgments. Thus, auditory adaptation enhances touch in a frequency- and feature-specific manner. A simple network model in which tactile frequency information is decoded from sensory neurons that are susceptible to auditory adaptation recapitulates these behavioral results. Our results imply that the neural circuits supporting tactile frequency perception also process auditory signals. This finding is consistent with the notion of supramodal operators performing canonical operations, like temporal frequency processing, regardless of input modality.

  13. Auditory Dysfunction in Patients with Cerebrovascular Disease

    Directory of Open Access Journals (Sweden)

    Sadaharu Tabuchi

    2014-01-01

    Full Text Available Auditory dysfunction is a common clinical symptom that can induce profound effects on the quality of life of those affected. Cerebrovascular disease (CVD is the most prevalent neurological disorder today, but it has generally been considered a rare cause of auditory dysfunction. However, a substantial proportion of patients with stroke might have auditory dysfunction that has been underestimated due to difficulties with evaluation. The present study reviews relationships between auditory dysfunction and types of CVD including cerebral infarction, intracerebral hemorrhage, subarachnoid hemorrhage, cerebrovascular malformation, moyamoya disease, and superficial siderosis. Recent advances in the etiology, anatomy, and strategies to diagnose and treat these conditions are described. The numbers of patients with CVD accompanied by auditory dysfunction will increase as the population ages. Cerebrovascular diseases often include the auditory system, resulting in various types of auditory dysfunctions, such as unilateral or bilateral deafness, cortical deafness, pure word deafness, auditory agnosia, and auditory hallucinations, some of which are subtle and can only be detected by precise psychoacoustic and electrophysiological testing. The contribution of CVD to auditory dysfunction needs to be understood because CVD can be fatal if overlooked.

  14. The auditory brainstem is a barometer of rapid auditory learning.

    Science.gov (United States)

    Skoe, E; Krizman, J; Spitzer, E; Kraus, N

    2013-07-23

    To capture patterns in the environment, neurons in the auditory brainstem rapidly alter their firing based on the statistical properties of the soundscape. How this neural sensitivity relates to behavior is unclear. We tackled this question by combining neural and behavioral measures of statistical learning, a general-purpose learning mechanism governing many complex behaviors including language acquisition. We recorded complex auditory brainstem responses (cABRs) while human adults implicitly learned to segment patterns embedded in an uninterrupted sound sequence based on their statistical characteristics. The brainstem's sensitivity to statistical structure was measured as the change in the cABR between a patterned and a pseudo-randomized sequence composed from the same set of sounds but differing in their sound-to-sound probabilities. Using this methodology, we provide the first demonstration that behavioral-indices of rapid learning relate to individual differences in brainstem physiology. We found that neural sensitivity to statistical structure manifested along a continuum, from adaptation to enhancement, where cABR enhancement (patterned>pseudo-random) tracked with greater rapid statistical learning than adaptation. Short- and long-term auditory experiences (days to years) are known to promote brainstem plasticity and here we provide a conceptual advance by showing that the brainstem is also integral to rapid learning occurring over minutes.

  15. Fatigue syndrome in sarcoidosis.

    Science.gov (United States)

    Górski, Witold; Piotrowski, Wojciech J

    2016-01-01

    Sarcoidosis is an inflammatory disease of unknown etiology. Most commonly it results in the formation of non-caseating granulomas in intrathoracic lymph nodes and lung parenchyma, but the clinical course and picture may be complicated by extrapulmonary involvement and many non-respiratory signs and symptoms which are directly related to the disease. In addition, sarcoidosis patients may suffer from a plethora of symptoms of uncertain or unknown origin. Fatigue is one of these symptoms, and according to some authors it is reported by the majority of patients with active sarcoidosis, but also by a smaller proportion of patients with inactive sarcoidosis, or even with complete clinical and radiological remission. Therefore the term fatigue syndrome is frequently used to name this clinical problem. The definition of fatigue syndrome in sarcoidosis is imprecise and the syndrome is usually recognized by use of validated questionnaires. In this review the uptodate knowledge in this field was presented and different challenges connected with this syndrome were described.

  16. Fatigue in systemic lupus erythematosus.

    Science.gov (United States)

    Ahn, Grace E; Ramsey-Goldman, Rosalind

    2012-04-01

    Systemic lupus erythematosus is a chronic inflammatory autoimmune disease often characterized by fatigue, with significant effects on physical functioning and wellbeing. The definition, prevalence and factors associated with fatigue, including physical activity, obesity, sleep, depression, anxiety, mood, cognitive dysfunction, vitamin D deficiency/insufficiency, pain, effects of medications and comorbidities, as well as potential therapeutic options of fatigue in the systemic lupus erythematosus population are reviewed. Due to variability in the reliability and validity of various fatigue measures used in clinical studies, clinical trial data have been challenging to interpret. Further investigation into the relationships between these risk factors and fatigue, and improved measures of fatigue, may lead to an improvement in the management of this chronic inflammatory disease.

  17. Probabilistic Fatigue Damage Program (FATIG)

    Science.gov (United States)

    Michalopoulos, Constantine

    2012-01-01

    FATIG computes fatigue damage/fatigue life using the stress rms (root mean square) value, the total number of cycles, and S-N curve parameters. The damage is computed by the following methods: (a) traditional method using Miner s rule with stress cycles determined from a Rayleigh distribution up to 3*sigma; and (b) classical fatigue damage formula involving the Gamma function, which is derived from the integral version of Miner's rule. The integration is carried out over all stress amplitudes. This software solves the problem of probabilistic fatigue damage using the integral form of the Palmgren-Miner rule. The software computes fatigue life using an approach involving all stress amplitudes, up to N*sigma, as specified by the user. It can be used in the design of structural components subjected to random dynamic loading, or by any stress analyst with minimal training for fatigue life estimates of structural components.

  18. Neural mechanisms of mental fatigue.

    Science.gov (United States)

    Ishii, Akira; Tanaka, Masaaki; Watanabe, Yasuyoshi

    2014-01-01

    Fatigue is defined as a decline in the ability and efficiency of mental and/or physical activities that is caused by excessive mental and/or physical activities. Fatigue can be classified as physical or mental. Mental fatigue manifests as potentially impaired cognitive function and is one of the most significant causes of accidents in modern society. Recently, it has been shown that the neural mechanisms of mental fatigue related to cognitive task performance are more complex than previously thought and that mental fatigue is not caused only by impaired activity in task-related brain regions. There is accumulating evidence supporting the existence of mental facilitation and inhibition systems. These systems are involved in the neural mechanisms of mental fatigue, modulating the activity of task-related brain regions to regulate cognitive task performance. In this review, we propose a new conceptual model: the dual regulation system of mental fatigue. This model contributes to our understanding of the neural mechanisms of mental fatigue and the regulatory mechanisms of cognitive task performance in the presence of mental fatigue.

  19. Cryogenic fatigue data developed for Inconel 718

    Science.gov (United States)

    Schmidt, E. H.

    1967-01-01

    Data were obtained on the cryogenic fatigue properties of Inconel 718 bar using axial loading and rotating beam fatigue tests. Results also disclosed the fatigue properties of Inconel 718 sheet materials.

  20. Auditory Motion Elicits a Visual Motion Aftereffect

    Directory of Open Access Journals (Sweden)

    Christopher C. Berger

    2016-12-01

    Full Text Available The visual motion aftereffect is a visual illusion in which exposure to continuous motion in one direction leads to a subsequent illusion of visual motion in the opposite direction. Previous findings have been mixed with regard to whether this visual illusion can be induced cross-modally by auditory stimuli. Based on research on multisensory perception demonstrating the profound influence auditory perception can have on the interpretation and perceived motion of visual stimuli, we hypothesized that exposure to auditory stimuli with strong directional motion cues should induce a visual motion aftereffect. Here, we demonstrate that horizontally moving auditory stimuli induced a significant visual motion aftereffect—an effect that was driven primarily by a change in visual motion perception following exposure to leftward moving auditory stimuli. This finding is consistent with the notion that visual and auditory motion perception rely on at least partially overlapping neural substrates.

  1. Speech distortion measure based on auditory properties

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo; HU Xiulin; ZHANG Yunyu; ZHU Yaoting

    2000-01-01

    The Perceptual Spectrum Distortion (PSD), based on auditory properties of human being, is presented to measure speech distortion. The PSD measure calculates the speech distortion distance by simulating the auditory properties of human being and converting short-time speech power spectrum to auditory perceptual spectrum. Preliminary simulative experiments in comparison with the Itakura measure have been done. The results show that the PSD measure is a perferable speech distortion measure and more consistent with subjective assessment of speech quality.

  2. Auditory evoked potentials and multiple sclerosis

    OpenAIRE

    Carla Gentile Matas; Sandro Luiz de Andrade Matas; Caroline Rondina Salzano de Oliveira; Isabela Crivellaro Gonçalves

    2010-01-01

    Multiple sclerosis (MS) is an inflammatory, demyelinating disease that can affect several areas of the central nervous system. Damage along the auditory pathway can alter its integrity significantly. Therefore, it is important to investigate the auditory pathway, from the brainstem to the cortex, in individuals with MS. OBJECTIVE: The aim of this study was to characterize auditory evoked potentials in adults with MS of the remittent-recurrent type. METHOD: The study comprised 25 individuals w...

  3. Seeing the song: left auditory structures may track auditory-visual dynamic alignment.

    Directory of Open Access Journals (Sweden)

    Julia A Mossbridge

    Full Text Available Auditory and visual signals generated by a single source tend to be temporally correlated, such as the synchronous sounds of footsteps and the limb movements of a walker. Continuous tracking and comparison of the dynamics of auditory-visual streams is thus useful for the perceptual binding of information arising from a common source. Although language-related mechanisms have been implicated in the tracking of speech-related auditory-visual signals (e.g., speech sounds and lip movements, it is not well known what sensory mechanisms generally track ongoing auditory-visual synchrony for non-speech signals in a complex auditory-visual environment. To begin to address this question, we used music and visual displays that varied in the dynamics of multiple features (e.g., auditory loudness and pitch; visual luminance, color, size, motion, and organization across multiple time scales. Auditory activity (monitored using auditory steady-state responses, ASSR was selectively reduced in the left hemisphere when the music and dynamic visual displays were temporally misaligned. Importantly, ASSR was not affected when attentional engagement with the music was reduced, or when visual displays presented dynamics clearly dissimilar to the music. These results appear to suggest that left-lateralized auditory mechanisms are sensitive to auditory-visual temporal alignment, but perhaps only when the dynamics of auditory and visual streams are similar. These mechanisms may contribute to correct auditory-visual binding in a busy sensory environment.

  4. Auditory Training and Its Effects upon the Auditory Discrimination and Reading Readiness of Kindergarten Children.

    Science.gov (United States)

    Cullen, Minga Mustard

    The purpose of this investigation was to evaluate the effects of a systematic auditory training program on the auditory discrimination ability and reading readiness of 55 white, middle/upper middle class kindergarten students. Following pretesting with the "Wepman Auditory Discrimination Test,""The Clymer-Barrett Prereading Battery," and the…

  5. Effects of Methylphenidate (Ritalin) on Auditory Performance in Children with Attention and Auditory Processing Disorders.

    Science.gov (United States)

    Tillery, Kim L.; Katz, Jack; Keller, Warren D.

    2000-01-01

    A double-blind, placebo-controlled study examined effects of methylphenidate (Ritalin) on auditory processing in 32 children with both attention deficit hyperactivity disorder and central auditory processing (CAP) disorder. Analyses revealed that Ritalin did not have a significant effect on any of the central auditory processing measures, although…

  6. Multidimensional fatigue and its correlates in hospitalised advanced cancer patients.

    NARCIS (Netherlands)

    Echteld, M.A.; Passchier, J.; Teunissen, S.; Claessen, S.; Wit, R. de; Rijt, C.C.D. van der

    2007-01-01

    Although fatigue is a multidimensional concept, multidimensional fatigue is rarely investigated in hospitalised cancer patients. We determined the levels and correlates of multidimensional fatigue in 100 advanced cancer patients admitted for symptom control. Fatigue dimensions were general fatigue (

  7. Nonlinear cumulative damage model for multiaxial fatigue

    Institute of Scientific and Technical Information of China (English)

    SHANG De-guang; SUN Guo-qin; DENG Jing; YAN Chu-liang

    2006-01-01

    On the basis of the continuum fatigue damage theory,a nonlinear uniaxial fatigue cumulative damage model is first proposed.In order to describe multiaxial fatigue damage characteristics,a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach,The proposed model can consider the multiaxial fatigue limit,mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters.The recurrence formula of fatigue damage model was derived under multilevel loading,which is used to predict multiaxial fatigue life.The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner's rule.

  8. Central auditory function of deafness genes.

    Science.gov (United States)

    Willaredt, Marc A; Ebbers, Lena; Nothwang, Hans Gerd

    2014-06-01

    The highly variable benefit of hearing devices is a serious challenge in auditory rehabilitation. Various factors contribute to this phenomenon such as the diversity in ear defects, the different extent of auditory nerve hypoplasia, the age of intervention, and cognitive abilities. Recent analyses indicate that, in addition, central auditory functions of deafness genes have to be considered in this context. Since reduced neuronal activity acts as the common denominator in deafness, it is widely assumed that peripheral deafness influences development and function of the central auditory system in a stereotypical manner. However, functional characterization of transgenic mice with mutated deafness genes demonstrated gene-specific abnormalities in the central auditory system as well. A frequent function of deafness genes in the central auditory system is supported by a genome-wide expression study that revealed significant enrichment of these genes in the transcriptome of the auditory brainstem compared to the entire brain. Here, we will summarize current knowledge of the diverse central auditory functions of deafness genes. We furthermore propose the intimately interwoven gene regulatory networks governing development of the otic placode and the hindbrain as a mechanistic explanation for the widespread expression of these genes beyond the cochlea. We conclude that better knowledge of central auditory dysfunction caused by genetic alterations in deafness genes is required. In combination with improved genetic diagnostics becoming currently available through novel sequencing technologies, this information will likely contribute to better outcome prediction of hearing devices.

  9. Effect of mental fatigue caused by mobile 3D viewing on selective attention: an ERP study.

    Science.gov (United States)

    Mun, Sungchul; Kim, Eun-Soo; Park, Min-Chul

    2014-12-01

    This study investigated behavioral responses to and auditory event-related potential (ERP) correlates of mental fatigue caused by mobile three-dimensional (3D) viewing. Twenty-six participants (14 women) performed a selective attention task in which they were asked to respond to the sounds presented at the attended side while ignoring sounds at the ignored side before and after mobile 3D viewing. Considering different individual susceptibilities to 3D, participants' subjective fatigue data were used to categorize them into two groups: fatigued and unfatigued. The amplitudes of d-ERP components were defined as differences in amplitudes between time-locked brain oscillations of the attended and ignored sounds, and these values were used to calculate the degree to which spatial selective attention was impaired by 3D mental fatigue. The fatigued group showed significantly longer response times after mobile 3D viewing compared to before the viewing. However, response accuracy did not significantly change between the two conditions, implying that the participants used a behavioral strategy to cope with their performance accuracy decrement by increasing their response times. No significant differences were observed for the unfatigued group. Analysis of covariance revealed group differences with significant and trends toward significant decreases in the d-P200 and d-late positive potential (LPP) amplitudes at the occipital electrodes of the fatigued and unfatigued groups. Our findings indicate that mentally fatigued participants did not effectively block out distractors in their information processing mechanism, providing support for the hypothesis that 3D mental fatigue impairs spatial selective attention and is characterized by changes in d-P200 and d-LPP amplitudes.

  10. Fatigue 󈨛. Volume 1,

    Science.gov (United States)

    1987-06-01

    5] in their studies on HY80 steel . For a long crack, the value of AK., deter~ined using a careful wind-down sequence, at R = 0.35, wast4.6 MPam . In...with a value of AK = 4.8 MPam obtained by James and Knott [5] for HY80 steel quenched and tempered to similar yield strength, and R = 0.2. In the latter...of Fatigue-Crack Nucleation 53 in a Low-Alloy Steel under Fretting Conditions - J. BEARD AND P.F. THOMASON The Effects of Thin Anodic Films on the 63

  11. Fatigue Reliability under Random Loads

    DEFF Research Database (Denmark)

    Talreja, R.

    1979-01-01

    , with the application of random loads, the initial homogeneous distribution of strength changes to a two-component distribution, reflecting the two-stage fatigue damage. In the crack initiation stage, the strength increases initially and then decreases, while an abrupt decrease of strength is seen in the crack...... propagation stage. The consequences of this behaviour on the fatigue reliability are discussed....

  12. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2004-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  13. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2005-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  14. Fatigue of Concrete Armour Units

    DEFF Research Database (Denmark)

    Sørensen, N. B.; Burcharth, H. F.; Liu, Z.

    1995-01-01

    In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed.......In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed....

  15. Modafinil May Alleviate Poststroke Fatigue

    DEFF Research Database (Denmark)

    Poulsen, Mai Bang; Damgaard, Bodil; Zerahn, Bo

    2015-01-01

    BACKGROUND AND PURPOSE: Poststroke fatigue is common and reduces quality of life. Current evidence for intervention is limited, and this is the first placebo-controlled trial to investigate treatment of poststroke fatigue with the wakefulness promoting drug modafinil. METHODS: The trial was rando......: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01800097....

  16. Fatigue monitoring in Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ware, A.G.; Shah, V.N. [Idaho National Engineering Laboratory, Idaho Falls, ID (United States)

    1995-04-01

    This paper summarizes fatigue monitoring methods and surveys their application in the nuclear power industry. The paper is based on a review of the technical literature. Two main reasons for fatigue monitoring are more frequent occurrence of some transients than that assumed in the fatigue design analysis and the discovery of stressors that were not included in the fatigue design analysis but may cause significant fatigue damage at some locations. One fatigue monitoring method involves use of plant operating data and procedures to update the fatigue usage. Another method involves monitoring of plant operating parameters using existing, or if needed, supplementary plant instrumentation for online computation of fatigue usage. Use of fatigue monitoring has better defined the operational transients. Most operational transients have been found less severe and fewer in numbers than anticipated in the design fatigue analysis. Use of fatigue monitoring has assisted in quantifying newly discovered stressors and has helped in detecting the presence of thermal stratification of unsuspected locations.

  17. Low visual information-processing speed and attention are predictors of fatigue in elementary and junior high school students

    Directory of Open Access Journals (Sweden)

    Yamano Emi

    2011-06-01

    Full Text Available Abstract Background Fatigue is a common complaint among elementary and junior high school students, and is known to be associated with reduced academic performance. Recently, we demonstrated that fatigue was correlated with decreased cognitive function in these students. However, no studies have identified cognitive predictors of fatigue. Therefore, we attempted to determine independent cognitive predictors of fatigue in these students. Methods We performed a prospective cohort study. One hundred and forty-two elementary and junior high school students without fatigue participated. They completed a variety of paper-and-pencil tests, including list learning and list recall tests, kana pick-out test, semantic fluency test, figure copying test, digit span forward test, and symbol digit modalities test. The participants also completed computerized cognitive tests (tasks A to E on the modified advanced trail making test. These cognitive tests were used to evaluate motor- and information-processing speed, immediate and delayed memory function, auditory and visual attention, divided and switching attention, retrieval of learned material, and spatial construction. One year after the tests, a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale was administered to all the participants. Results After the follow-up period, we confirmed 40 cases of fatigue among 118 students. In multivariate logistic regression analyses adjusted for grades and gender, poorer performance on visual information-processing speed and attention tasks was associated with increased risk of fatigue. Conclusions Reduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students.

  18. Autosomal recessive hereditary auditory neuropathy

    Institute of Scientific and Technical Information of China (English)

    王秋菊; 顾瑞; 曹菊阳

    2003-01-01

    Objectives: Auditory neuropathy (AN) is a sensorineural hearing disorder characterized by absent or abnormal auditory brainstem responses (ABRs) and normal cochlear outer hair cell function as measured by otoacoustic emissions (OAEs). Many risk factors are thought to be involved in its etiology and pathophysiology. Three Chinese pedigrees with familial AN are presented herein to demonstrate involvement of genetic factors in AN etiology. Methods: Probands of the above - mentioned pedigrees, who had been diagnosed with AN, were evaluated and followed up in the Department of Otolaryngology Head and Neck Surgery, China PLA General Hospital. Their family members were studied and the pedigree diagrams were established. History of illness, physical examination,pure tone audiometry, acoustic reflex, ABRs and transient evoked and distortion- product otoacoustic emissions (TEOAEs and DPOAEs) were obtained from members of these families. DPOAE changes under the influence of contralateral sound stimuli were observed by presenting a set of continuous white noise to the non - recording ear to exam the function of auditory efferent system. Some subjects received vestibular caloric test, computed tomography (CT)scan of the temporal bone and electrocardiography (ECG) to exclude other possible neuropathy disorders. Results: In most affected subjects, hearing loss of various degrees and speech discrimination difficulties started at 10 to16 years of age. Their audiological evaluation showed absence of acoustic reflex and ABRs. As expected in AN, these subjects exhibited near normal cochlear outer hair cell function as shown in TEOAE & DPOAE recordings. Pure- tone audiometry revealed hearing loss ranging from mild to severe in these patients. Autosomal recessive inheritance patterns were observed in the three families. In Pedigree Ⅰ and Ⅱ, two affected brothers were found respectively, while in pedigree Ⅲ, 2 sisters were affected. All the patients were otherwise normal without

  19. Auditory hallucinations in nonverbal quadriplegics.

    Science.gov (United States)

    Hamilton, J

    1985-11-01

    When a system for communicating with nonverbal, quadriplegic, institutionalized residents was developed, it was discovered that many were experiencing auditory hallucinations. Nine cases are presented in this study. The "voices" described have many similar characteristics, the primary one being that they give authoritarian commands that tell the residents how to behave and to which the residents feel compelled to respond. Both the relationship of this phenomenon to the theoretical work of Julian Jaynes and its effect on the lives of the residents are discussed.

  20. Narrow, duplicated internal auditory canal

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, T. [Servico de Neurorradiologia, Hospital Garcia de Orta, Avenida Torrado da Silva, 2801-951, Almada (Portugal); Shayestehfar, B. [Department of Radiology, UCLA Oliveview School of Medicine, Los Angeles, California (United States); Lufkin, R. [Department of Radiology, UCLA School of Medicine, Los Angeles, California (United States)

    2003-05-01

    A narrow internal auditory canal (IAC) constitutes a relative contraindication to cochlear implantation because it is associated with aplasia or hypoplasia of the vestibulocochlear nerve or its cochlear branch. We report an unusual case of a narrow, duplicated IAC, divided by a bony septum into a superior relatively large portion and an inferior stenotic portion, in which we could identify only the facial nerve. This case adds support to the association between a narrow IAC and aplasia or hypoplasia of the vestibulocochlear nerve. The normal facial nerve argues against the hypothesis that the narrow IAC is the result of a primary bony defect which inhibits the growth of the vestibulocochlear nerve. (orig.)

  1. Mapping tonotopy in human auditory cortex

    NARCIS (Netherlands)

    van Dijk, Pim; Langers, Dave R M; Moore, BCJ; Patterson, RD; Winter, IM; Carlyon, RP; Gockel, HE

    2013-01-01

    Tonotopy is arguably the most prominent organizational principle in the auditory pathway. Nevertheless, the layout of tonotopic maps in humans is still debated. We present neuroimaging data that robustly identify multiple tonotopic maps in the bilateral auditory cortex. In contrast with some earlier

  2. Bilateral duplication of the internal auditory canal

    Energy Technology Data Exchange (ETDEWEB)

    Weon, Young Cheol; Kim, Jae Hyoung; Choi, Sung Kyu [Seoul National University College of Medicine, Department of Radiology, Seoul National University Bundang Hospital, Seongnam-si (Korea); Koo, Ja-Won [Seoul National University College of Medicine, Department of Otolaryngology, Seoul National University Bundang Hospital, Seongnam-si (Korea)

    2007-10-15

    Duplication of the internal auditory canal is an extremely rare temporal bone anomaly that is believed to result from aplasia or hypoplasia of the vestibulocochlear nerve. We report bilateral duplication of the internal auditory canal in a 28-month-old boy with developmental delay and sensorineural hearing loss. (orig.)

  3. Primary Auditory Cortex Regulates Threat Memory Specificity

    Science.gov (United States)

    Wigestrand, Mattis B.; Schiff, Hillary C.; Fyhn, Marianne; LeDoux, Joseph E.; Sears, Robert M.

    2017-01-01

    Distinguishing threatening from nonthreatening stimuli is essential for survival and stimulus generalization is a hallmark of anxiety disorders. While auditory threat learning produces long-lasting plasticity in primary auditory cortex (Au1), it is not clear whether such Au1 plasticity regulates memory specificity or generalization. We used…

  4. Further Evidence of Auditory Extinction in Aphasia

    Science.gov (United States)

    Marshall, Rebecca Shisler; Basilakos, Alexandra; Love-Myers, Kim

    2013-01-01

    Purpose: Preliminary research ( Shisler, 2005) suggests that auditory extinction in individuals with aphasia (IWA) may be connected to binding and attention. In this study, the authors expanded on previous findings on auditory extinction to determine the source of extinction deficits in IWA. Method: Seventeen IWA (M[subscript age] = 53.19 years)…

  5. Auditory Processing Disorder and Foreign Language Acquisition

    Science.gov (United States)

    Veselovska, Ganna

    2015-01-01

    This article aims at exploring various strategies for coping with the auditory processing disorder in the light of foreign language acquisition. The techniques relevant to dealing with the auditory processing disorder can be attributed to environmental and compensatory approaches. The environmental one involves actions directed at creating a…

  6. Speech perception as complex auditory categorization

    Science.gov (United States)

    Holt, Lori L.

    2002-05-01

    Despite a long and rich history of categorization research in cognitive psychology, very little work has addressed the issue of complex auditory category formation. This is especially unfortunate because the general underlying cognitive and perceptual mechanisms that guide auditory category formation are of great importance to understanding speech perception. I will discuss a new methodological approach to examining complex auditory category formation that specifically addresses issues relevant to speech perception. This approach utilizes novel nonspeech sound stimuli to gain full experimental control over listeners' history of experience. As such, the course of learning is readily measurable. Results from this methodology indicate that the structure and formation of auditory categories are a function of the statistical input distributions of sound that listeners hear, aspects of the operating characteristics of the auditory system, and characteristics of the perceptual categorization system. These results have important implications for phonetic acquisition and speech perception.

  7. Fatigue management in the workplace

    Directory of Open Access Journals (Sweden)

    Khosro Sadeghniiat-Haghighi

    2015-01-01

    Full Text Available Workers′ fatigue is a significant problem in modern industry, largely because of high demand jobs, long duty periods, disruption of circadian rhythms, and accumulative sleep debt that are common in many industries. Fatigue is the end result of integration of multiple factors such as time awake, time of day, and workload. Then, the full understanding of circadian biologic clock, dynamics of transient and cumulative sleep loss, and recovery is required for effective management of workplace fatigue. It can be more investigated in a new field of sleep medicine called occupational sleep medicine. Occupational sleep medicine is concerned with maintaining best productivity and safety in the industrial settings. The fatigue risk management system (FRMS is a comprehensive approach that is based on applying scientific evidence of sleep knowledge to manage workers fatigue. It is developing rapidly in the highly safety demand jobs; especially truck drivers, pilots, and power plant workers. The objective of this review is to explain about fatigue in the workplace with emphasis on its association work performance and errors/accidents. Also, we discussed about different methods of fatigue measurement and management.

  8. THE EFFECTS OF SALICYLATE ON AUDITORY EVOKED POTENTIAL AMPLITWDE FROM THE AUDITORY CORTEX AND AUDITORY BRAINSTEM

    Institute of Scientific and Technical Information of China (English)

    Brian Sawka; SUN Wei

    2014-01-01

    Tinnitus has often been studied using salicylate in animal models as they are capable of inducing tempo-rary hearing loss and tinnitus. Studies have recently observed enhancement of auditory evoked responses of the auditory cortex (AC) post salicylate treatment which is also shown to be related to tinnitus like behavior in rats. The aim of this study was to observe if enhancements of the AC post salicylate treatment are also present at structures in the brainstem. Four male Sprague Dawley rats with AC implanted electrodes were tested for both AC and auditory brainstem response (ABR) recordings pre and post 250 mg/kg intraperitone-al injections of salicylate. The responses were recorded as the peak to trough amplitudes of P1-N1 (AC), ABR wave V, and ABR waveⅡ. AC responses resulted in statistically significant enhancement of ampli-tude at 2 hours post salicylate with 90 dB stimuli tone bursts of 4, 8, 12, and 20 kHz. Wave V of ABR re-sponses at 90 dB resulted in a statistically significant reduction of amplitude 2 hours post salicylate and a mean decrease of amplitude of 31%for 16 kHz. WaveⅡamplitudes at 2 hours post treatment were signifi-cantly reduced for 4, 12, and 20 kHz stimuli at 90 dB SPL. Our results suggest that the enhancement chang-es of the AC related to salicylate induced tinnitus are generated superior to the level of the inferior colliculus and may originate in the AC.

  9. Fatigue of Dental Implants: Facts and Fallacies

    OpenAIRE

    Keren Shemtov-Yona; Daniel Rittel

    2016-01-01

    Dental implants experience rare yet problematic mechanical failures such as fracture that are caused, most often, by (time-dependent) metal fatigue. This paper surveys basic evidence about fatigue failure, its identification and the implant’s fatigue performance during service. We first discuss the concept of dental implant fatigue, starting with a review of basic concepts related to this failure mechanism. The identification of fatigue failures using scanning electron microscopy follows, to ...

  10. Relationship between Sympathetic Skin Responses and Auditory Hypersensitivity to Different Auditory Stimuli.

    Science.gov (United States)

    Kato, Fumi; Iwanaga, Ryoichiro; Chono, Mami; Fujihara, Saori; Tokunaga, Akiko; Murata, Jun; Tanaka, Koji; Nakane, Hideyuki; Tanaka, Goro

    2014-07-01

    [Purpose] Auditory hypersensitivity has been widely reported in patients with autism spectrum disorders. However, the neurological background of auditory hypersensitivity is currently not clear. The present study examined the relationship between sympathetic nervous system responses and auditory hypersensitivity induced by different types of auditory stimuli. [Methods] We exposed 20 healthy young adults to six different types of auditory stimuli. The amounts of palmar sweating resulting from the auditory stimuli were compared between groups with (hypersensitive) and without (non-hypersensitive) auditory hypersensitivity. [Results] Although no group × type of stimulus × first stimulus interaction was observed for the extent of reaction, significant type of stimulus × first stimulus interaction was noted for the extent of reaction. For an 80 dB-6,000 Hz stimulus, the trends for palmar sweating differed between the groups. For the first stimulus, the variance became larger in the hypersensitive group than in the non-hypersensitive group. [Conclusion] Subjects who regularly felt excessive reactions to auditory stimuli tended to have excessive sympathetic responses to repeated loud noises compared with subjects who did not feel excessive reactions. People with auditory hypersensitivity may be classified into several subtypes depending on their reaction patterns to auditory stimuli.

  11. Fatigue, burnout, and chronic fatigue syndrome among employees on sick leave: do attributions make the difference?

    NARCIS (Netherlands)

    Huibers, M.J.H.; Beurskens, A.J.H.M.; Prins, J.B.; Kant, I.J.; Bazelmans, H.M.; Schayck, C.P. van; Knottnerus, J.A.; Bleijenberg, G.

    2003-01-01

    BACKGROUND: Persistent fatigue among employees, burnout, and chronic fatigue syndrome (CFS) are three fatigue conditions that share some characteristics in theory. However, these conditions have not been compared in empirical research, despite conceptual similarities. METHODS: This cross sectional s

  12. Fatigue reliability for LNG carrier

    Institute of Scientific and Technical Information of China (English)

    Xiao Taoyun; Zhang Qin; Jin Wulei; Xu Shuai

    2011-01-01

    The procedure of reliability-based fatigue analysis of liquefied natural gas (LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method (FEM). Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis, Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory, fatigue damage is characterized by an S-N relationship, and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.

  13. Fatigue in primary Sjogren's syndrome

    NARCIS (Netherlands)

    P.J. Barendregt (Pieternella); M.R. Visser (Mechteld); E.M.A. Smets (Ellen); J.H.M. Tulen (Joke); A.H. van den Meiracker (Anton); F. Boomsma (Frans); H.M. Markusse

    1998-01-01

    textabstractOBJECTIVE: To assess fatigue in relation to depression, blood pressure, and plasma catecholamines in patients with primary Sjogren's syndrome (SS), in comparison with healthy controls and patients with rheumatoid arthritis. METHODS: For the assessment of fat

  14. Fatigue and Corrosion in Metals

    CERN Document Server

    Milella, Pietro Paolo

    2013-01-01

    This textbook, suitable for students, researchers and engineers, gathers the experience of more than 20 years of teaching fracture mechanics, fatigue and corrosion to professional engineers and running experimental tests and verifications to solve practical problems in engineering applications. As such, it is a comprehensive blend of fundamental knowledge and technical tools to address the issues of fatigue and corrosion. The book initiates with a systematic description of fatigue from a phenomenological point of view, since the early signs of submicroscopic damage in few surface grains and continues describing, step by step, how these precursors develop to become mechanically small cracks and, eventually, macrocracks whose growth is governed by fracture mechanics. But fracture mechanics is also introduced to analyze stress corrosion and corrosion assisted fatigue in a rather advanced fashion. The author dedicates a particular attention to corrosion starting with an electrochemical treatment that mechanical e...

  15. Resolving the frustration of fatigue.

    Science.gov (United States)

    Harpham, W S

    1999-01-01

    Fatigue is a ubiquitous side effect of many cancer therapies. Nevertheless, after treatment is complete, many survivors continue to feel a profound tiredness that affects almost all aspects of life. Even after recovery, patients are often frustrated by their continuing need for extra rest. In this deeply personal, first-person account, a physician relates the various ways that cancer-related fatigue can affect family dynamics, job responsibilities, social interactions, finances, and intimacy. Clinicians can help by searching for treatable medical conditions, but also by taking cancer-related fatigue, and the frustrations it causes, seriously. Patients should be reassured that the fatigue they feel is real, and that by learning personal energy conservation, they should be able to improve their abilities to function, to socialize, to interact with others, and ultimately to adjust to a "new normal" baseline.

  16. Fatigue damage detection using cyclostationarity

    Science.gov (United States)

    Boungou, D.; Guillet, F.; Badaoui, M. El; Lyonnet, P.; Rosario, T.

    2015-06-01

    In this paper, we present the second-order of cyclostationarity to detect and diagnose the fatigue damage of the stainless steel 316l subjected to low cycle fatigue (LCF). LCF is defined by repetitive cycling in a low stress and a short period. The vibration response of material subjected to LCF provides information linked to the solicitation and to the fatigue damage. Thus, we considered a cantilever beam with breathing cracks and assumed that under the solicitation, breathing cracks generates non-linearity in the stiffness of the material and this one decreases with the damage. We used the second-order of the cyclostationarity to reveal this non-linearity and showed that the fatigue provide a random component in the signal, which increases with the fatigue damage. Thus, in the specific case of a material subjected to LCF, with a non-linear stiffness, we propose a new methodology to detect and diagnose the fatigue damage using a vibration signal. This methodology is based on the second order of the cyclostationarity.

  17. Automotive stamped part fatigue design

    Directory of Open Access Journals (Sweden)

    Caudoux Mélanie

    2014-06-01

    Full Text Available Fatigue design of automotive axle parts is of prior concern because of these are high safety parts and they are expected to drive the overall vehicle mass reduction. In this framework, the stamping process is widely used to form axle parts, before assembling them by welding. Consequently, the mechanical and physical characteristics of the blank sheet are modified, having a strong influence on the fatigue behavior. In this paper, we address the consequences of the stamped process on the fatigue design and how they may be effectively taken into account in the automotive industry. Actually, the coupling between the stamping process and the fatigue design is under development at PSA Peugeot Citroën Company since several years. Such an analysis deals with some major topics: thickness variation, plastic hardening and deformation, and residual stress. All of these ingredients result in fatigue criteria evolutions: it is important to stress that the stamping process can have advantageous or disadvantageous consequences on the fatigue design. This is here highlighted on some examples, dealing with front and rear axles.

  18. Auditory filters at low-frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Møller, Henrik

    2009-01-01

    Prediction and assessment of low-frequency noise problems requires information about the auditory filter characteristics at low-frequencies. Unfortunately, data at low-frequencies is scarce and practically no results have been published for frequencies below 100 Hz. Extrapolation of ERB results......-ear transfer function), the asymmetry of the auditory filter changed from steeper high-frequency slopes at 1000 Hz to steeper low-frequency slopes below 100 Hz. Increasing steepness at low-frequencies of the middle-ear high-pass filter is thought to cause this effect. The dynamic range of the auditory filter...

  19. Assessing the aging effect on auditory-verbal memory by Persian version of dichotic auditory verbal memory test

    Directory of Open Access Journals (Sweden)

    Zahra Shahidipour

    2014-01-01

    Conclusion: Based on the obtained results, significant reduction in auditory memory was seen in aged group and the Persian version of dichotic auditory-verbal memory test, like many other auditory verbal memory tests, showed the aging effects on auditory verbal memory performance.

  20. MODELS OF FATIGUE LIFE CURVES IN FATIGUE LIFE CALCULATIONS OF MACHINE ELEMENTS – EXAMPLES OF RESEARCH

    Directory of Open Access Journals (Sweden)

    Grzegorz SZALA

    2014-03-01

    Full Text Available In the paper there was attempted to analyse models of fatigue life curves possible to apply in calculations of fatigue life of machine elements. The analysis was limited to fatigue life curves in stress approach enabling cyclic stresses from the range of low cycle fatigue (LCF, high cycle fatigue (HCF, fatigue limit (FL and giga cycle fatigue (GCF appearing in the loading spectrum at the same time. Chosen models of the analysed fatigue live curves will be illustrated with test results of steel and aluminium alloys.

  1. Meditation and auditory attention: An ERP study of meditators and non-meditators.

    Science.gov (United States)

    Biedermann, Britta; de Lissa, Peter; Mahajan, Yatin; Polito, Vince; Badcock, Nicolas; Connors, Michael H; Quinto, Lena; Larsen, Linda; McArthur, Genevieve

    2016-11-01

    The findings of a study by Cahn and Polich (2009) suggests that there is an effect of a meditative state on three event-related potential (ERP) brain markers of "low-level" auditory attention (i.e., acoustic representations in sensory memory) in expert meditators: the N1, the P2, and the P3a. The current study built on these findings by examining trait and state effects of meditation on the passive auditory mismatch negativity (MMN), N1, and P2 ERPs. We found that the MMN was significantly larger in meditators than non-meditators regardless of whether they were meditating or not (a trait effect), and that N1 amplitude was significantly attenuated during meditation in non-meditators but not expert meditators (an interaction between trait and state). These outcomes suggest that low-level attention is superior in long-term meditators in general. In contrast, low-level attention is reduced in non-meditators when they are asked to meditate for the first time, possibly due to auditory fatigue or cognitive overload.

  2. Use of auditory learning to manage listening problems in children

    OpenAIRE

    Moore, David R.; Halliday, Lorna F.; Amitay, Sygal

    2008-01-01

    This paper reviews recent studies that have used adaptive auditory training to address communication problems experienced by some children in their everyday life. It considers the auditory contribution to developmental listening and language problems and the underlying principles of auditory learning that may drive further refinement of auditory learning applications. Following strong claims that language and listening skills in children could be improved by auditory learning, researchers hav...

  3. Biaxial fatigue of metals the present understanding

    CERN Document Server

    Schijve, Jaap

    2016-01-01

    Problems of fatigue under multiaxial fatigue loads have been addressed in a very large number of research publications. The present publication is primarily a survey of biaxial fatigue under constant amplitude loading on metal specimens. It starts with the physical understanding of the fatigue phenomenon under biaxial fatigue loads. Various types of proportional and non-proportional biaxial fatigue loads and biaxial stress distributions in a material are specified. Attention is paid to the fatigue limit, crack nucleation, initial micro crack growth and subsequent macro-crack in different modes of crack growth. The interference between the upper and lower surfaces of a fatigue crack is discussed. Possibilities for predictions of biaxial fatigue properties are analysed with reference to the similarity concept. The significance of the present understanding for structural design problems is considered. The book is completed with a summary of major observations.

  4. Fatigue after Stroke: The Patient's Perspective

    Directory of Open Access Journals (Sweden)

    Victoria Louise Barbour

    2012-01-01

    Full Text Available Background. Fatigue after stroke is common and distressing to patients. Aims. Our aims were to explore patients' perceptions of post-stroke fatigue, including the causes of fatigue and the factors that alleviate fatigue, in a mixed methods study. Results. We interviewed 15 patients who had had a stroke and were inpatients on stroke rehabilitation wards. A substantial proportion of patients reported that their fatigue started at the time of their stroke. Various different factors were reported to improve fatigue, including exercise, good sleep, rehabilitation and rest. Fatigue influences patients' sense of “control” after their stroke. Conclusion. Our results are consistent with the possibility that poststroke fatigue might be triggered by factors that occur at the time of the stroke (e.g., the stroke lesion itself, or admission to hospital and then exacerbated by poor sleep and boredom. These factors should be considered when developing complex interventions to improve post-stroke fatigue.

  5. Auditory-visual spatial interaction and modularity

    Science.gov (United States)

    Radeau, M

    1994-02-01

    The results of dealing with the conditions for pairing visual and auditory data coming from spatially separate locations argue for cognitive impenetrability and computational autonomy, the pairing rules being the Gestalt principles of common fate and proximity. Other data provide evidence for pairing with several properties of modular functioning. Arguments for domain specificity are inferred from comparison with audio-visual speech. Suggestion of innate specification can be found in developmental data indicating that the grouping of visual and auditory signals is supported very early in life by the same principles that operate in adults. Support for a specific neural architecture comes from neurophysiological studies of the bimodal (auditory-visual) neurons of the cat superior colliculus. Auditory-visual pairing thus seems to present the four main properties of the Fodorian module.

  6. [Approaches to therapy of auditory agnosia].

    Science.gov (United States)

    Fechtelpeter, A; Göddenhenrich, S; Huber, W; Springer, L

    1990-01-01

    In a 41-year-old stroke patient with bitemporal brain damage, we found severe signs of auditory agnosia 6 months after onset. Recognition of environmental sounds was extremely impaired when tested in a multiple choice sound-picture matching task, whereas auditory discrimination between sounds and picture identifications by written names was almost undisturbed. In a therapy experiment, we tried to enhance sound recognition via semantic categorization and association, imitation of sound and analysis of auditory features, respectively. The stimulation of conscious auditory analysis proved to be increasingly effective over a 4-week period of therapy. We were able to show that the patient's improvement was not only a simple effect of practicing, but it was stable and carried over to nontrained items.

  7. Environment for Auditory Research Facility (EAR)

    Data.gov (United States)

    Federal Laboratory Consortium — EAR is an auditory perception and communication research center enabling state-of-the-art simulation of various indoor and outdoor acoustic environments. The heart...

  8. Effect of omega-3 on auditory system

    Directory of Open Access Journals (Sweden)

    Vida Rahimi

    2014-01-01

    Full Text Available Background and Aim: Omega-3 fatty acid have structural and biological roles in the body 's various systems . Numerous studies have tried to research about it. Auditory system is affected a s well. The aim of this article was to review the researches about the effect of omega-3 on auditory system.Methods: We searched Medline , Google Scholar, PubMed, Cochrane Library and SID search engines with the "auditory" and "omega-3" keywords and read textbooks about this subject between 19 70 and 20 13.Conclusion: Both excess and deficient amounts of dietary omega-3 fatty acid can cause harmful effects on fetal and infant growth and development of brain and central nervous system esspesially auditory system. It is important to determine the adequate dosage of omega-3.

  9. Fatigue analysis of aluminum drill pipes

    Directory of Open Access Journals (Sweden)

    João Carlos Ribeiro Plácido

    2005-12-01

    Full Text Available An experimental program was performed to investigate the fundamental fatigue mechanisms of aluminum drill pipes. Initially, the fatigue properties were determined through small-scale tests performed in an optic-mechanical fatigue apparatus. Additionally, full-scale fatigue tests were carried out with three aluminum drill pipe specimens under combined loading of cyclic bending and constant axial tension. Finally, a finite element model was developed to simulate the stress field along the aluminum drill pipe during the fatigue tests and to estimate the stress concentration factors inside the tool joints. By this way, it was possible to estimate the stress values in regions not monitored during the fatigue tests.

  10. Fatigue Properties of Supersteel for Automobiles

    Institute of Scientific and Technical Information of China (English)

    DU Lin-xiu; ZHANG Zhong-ping; TIAN Yu-wei; LIU Xiang-hua; WANG Guo-dong

    2006-01-01

    The fatigue properties of 400 MPa grade supersteel, plain low carbon steel SS400 and microalloyed steel Q340TM were investigated through tensile-compression fatigue experiment with R=-1. The results indicate that the fatigue limit of the 400 MPa supersteel is higher than that of SS400 steel and close to that of the 340TM steel. According to the analysis of fatigue fracture, the fatigue striations of supersteel SS400 is thinner than that of SS400 steel and 340TM steel, and grain refinement can increase the fatigue limit.

  11. Sleep complaints and fatigue of airline pilots.

    Science.gov (United States)

    Reis, Cátia; Mestre, Catarina; Canhão, Helena; Gradwell, David; Paiva, Teresa

    2016-01-01

    This work aimed to determine daytime sleepiness and sleep complaints prevalence and the corresponding influence on perceived fatigue and to evaluate the influence of sociodemographic parameters and labour variables on sleep complaints, sleepiness and fatigue. A questionnaire was developed including socio-economic and labour issues and instruments, focused in sleep and fatigue. The response rate was 32% and the final sample had 435 pilots. The prevalence of sleep complaints was 34.9%, daytime sleepiness 59.3% and fatigue 90.6%. The high prevalence of sleep complaints, sleepiness and fatigue was disclosed in pilots, with those who fly short/medium having an added risk of fatigue.

  12. A critical period for auditory thalamocortical connectivity

    DEFF Research Database (Denmark)

    Rinaldi Barkat, Tania; Polley, Daniel B; Hensch, Takao K

    2011-01-01

    connectivity by in vivo recordings and day-by-day voltage-sensitive dye imaging in an acute brain slice preparation. Passive tone-rearing modified response strength and topography in mouse primary auditory cortex (A1) during a brief, 3-d window, but did not alter tonotopic maps in the thalamus. Gene...... locus of change for the tonotopic plasticity. The evolving postnatal connectivity between thalamus and cortex in the days following hearing onset may therefore determine a critical period for auditory processing....

  13. Speech Evoked Auditory Brainstem Response in Stuttering

    Directory of Open Access Journals (Sweden)

    Ali Akbar Tahaei

    2014-01-01

    Full Text Available Auditory processing deficits have been hypothesized as an underlying mechanism for stuttering. Previous studies have demonstrated abnormal responses in subjects with persistent developmental stuttering (PDS at the higher level of the central auditory system using speech stimuli. Recently, the potential usefulness of speech evoked auditory brainstem responses in central auditory processing disorders has been emphasized. The current study used the speech evoked ABR to investigate the hypothesis that subjects with PDS have specific auditory perceptual dysfunction. Objectives. To determine whether brainstem responses to speech stimuli differ between PDS subjects and normal fluent speakers. Methods. Twenty-five subjects with PDS participated in this study. The speech-ABRs were elicited by the 5-formant synthesized syllable/da/, with duration of 40 ms. Results. There were significant group differences for the onset and offset transient peaks. Subjects with PDS had longer latencies for the onset and offset peaks relative to the control group. Conclusions. Subjects with PDS showed a deficient neural timing in the early stages of the auditory pathway consistent with temporal processing deficits and their abnormal timing may underlie to their disfluency.

  14. Auditory processing in fragile x syndrome.

    Science.gov (United States)

    Rotschafer, Sarah E; Razak, Khaleel A

    2014-01-01

    Fragile X syndrome (FXS) is an inherited form of intellectual disability and autism. Among other symptoms, FXS patients demonstrate abnormalities in sensory processing and communication. Clinical, behavioral, and electrophysiological studies consistently show auditory hypersensitivity in humans with FXS. Consistent with observations in humans, the Fmr1 KO mouse model of FXS also shows evidence of altered auditory processing and communication deficiencies. A well-known and commonly used phenotype in pre-clinical studies of FXS is audiogenic seizures. In addition, increased acoustic startle response is seen in the Fmr1 KO mice. In vivo electrophysiological recordings indicate hyper-excitable responses, broader frequency tuning, and abnormal spectrotemporal processing in primary auditory cortex of Fmr1 KO mice. Thus, auditory hyper-excitability is a robust, reliable, and translatable biomarker in Fmr1 KO mice. Abnormal auditory evoked responses have been used as outcome measures to test therapeutics in FXS patients. Given that similarly abnormal responses are present in Fmr1 KO mice suggests that cellular mechanisms can be addressed. Sensory cortical deficits are relatively more tractable from a mechanistic perspective than more complex social behaviors that are typically studied in autism and FXS. The focus of this review is to bring together clinical, functional, and structural studies in humans with electrophysiological and behavioral studies in mice to make the case that auditory hypersensitivity provides a unique opportunity to integrate molecular, cellular, circuit level studies with behavioral outcomes in the search for therapeutics for FXS and other autism spectrum disorders.

  15. Auditory Processing in Fragile X Syndrome

    Directory of Open Access Journals (Sweden)

    Sarah E Rotschafer

    2014-02-01

    Full Text Available Fragile X syndrome (FXS is an inherited form of intellectual disability and autism. Among other symptoms, FXS patients demonstrate abnormalities in sensory processing and communication. Clinical, behavioral and electrophysiological studies consistently show auditory hypersensitivity in humans with FXS. Consistent with observations in humans, the Fmr1 KO mouse model of FXS also shows evidence of altered auditory processing and communication deficiencies. A well-known and commonly used phenotype in pre-clinical studies of FXS is audiogenic seizures. In addition, increased acoustic startle is also seen in the Fmr1 KO mice. In vivo electrophysiological recordings indicate hyper-excitable responses, broader frequency tuning and abnormal spectrotemporal processing in primary auditory cortex of Fmr1 KO mice. Thus, auditory hyper-excitability is a robust, reliable and translatable biomarker in Fmr1 KO mice. Abnormal auditory evoked responses have been used as outcome measures to test therapeutics in FXS patients. Given that similarly abnormal responses are present in Fmr1 KO mice suggests that cellular mechanisms can be addressed. Sensory cortical deficits are relatively more tractable from a mechanistic perspective than more complex social behaviors that are typically studied in autism and FXS. The focus of this review is to bring together clinical, functional and structural studies in humans with electrophysiological and behavioral studies in mice to make the case that auditory hypersensitivity provides a unique opportunity to integrate molecular, cellular, circuit level studies with behavioral outcomes in the search for therapeutics for FXS and other autism spectrum disorders.

  16. Auditory model inversion and its application

    Institute of Scientific and Technical Information of China (English)

    ZHAO Heming; WANG Yongqi; CHEN Xueqin

    2005-01-01

    Auditory model has been applied to several aspects of speech signal processing field, and appears to be effective in performance. This paper presents the inverse transform of each stage of one widely used auditory model. First of all it is necessary to invert correlogram and reconstruct phase information by repetitious iterations in order to get auditory-nerve firing rate. The next step is to obtain the negative parts of the signal via the reverse process of the HWR (Half Wave Rectification). Finally the functions of inner hair cell/synapse model and Gammatone filters have to be inverted. Thus the whole auditory model inversion has been achieved. An application of noisy speech enhancement based on auditory model inversion algorithm is proposed. Many experiments show that this method is effective in reducing noise.Especially when SNR of noisy speech is low it is more effective than other methods. Thus this auditory model inversion method given in this paper is applicable to speech enhancement field.

  17. Auditory dysfunction associated with solvent exposure

    Directory of Open Access Journals (Sweden)

    Fuente Adrian

    2013-01-01

    Full Text Available Abstract Background A number of studies have demonstrated that solvents may induce auditory dysfunction. However, there is still little knowledge regarding the main signs and symptoms of solvent-induced hearing loss (SIHL. The aim of this research was to investigate the association between solvent exposure and adverse effects on peripheral and central auditory functioning with a comprehensive audiological test battery. Methods Seventy-two solvent-exposed workers and 72 non-exposed workers were selected to participate in the study. The test battery comprised pure-tone audiometry (PTA, transient evoked otoacoustic emissions (TEOAE, Random Gap Detection (RGD and Hearing-in-Noise test (HINT. Results Solvent-exposed subjects presented with poorer mean test results than non-exposed subjects. A bivariate and multivariate linear regression model analysis was performed. One model for each auditory outcome (PTA, TEOAE, RGD and HINT was independently constructed. For all of the models solvent exposure was significantly associated with the auditory outcome. Age also appeared significantly associated with some auditory outcomes. Conclusions This study provides further evidence of the possible adverse effect of solvents on the peripheral and central auditory functioning. A discussion of these effects and the utility of selected hearing tests to assess SIHL is addressed.

  18. Long Latency Auditory Evoked Potentials during Meditation.

    Science.gov (United States)

    Telles, Shirley; Deepeshwar, Singh; Naveen, Kalkuni Visweswaraiah; Pailoor, Subramanya

    2015-10-01

    The auditory sensory pathway has been studied in meditators, using midlatency and short latency auditory evoked potentials. The present study evaluated long latency auditory evoked potentials (LLAEPs) during meditation. Sixty male participants, aged between 18 and 31 years (group mean±SD, 20.5±3.8 years), were assessed in 4 mental states based on descriptions in the traditional texts. They were (a) random thinking, (b) nonmeditative focusing, (c) meditative focusing, and (d) meditation. The order of the sessions was randomly assigned. The LLAEP components studied were P1 (40-60 ms), N1 (75-115 ms), P2 (120-180 ms), and N2 (180-280 ms). For each component, the peak amplitude and peak latency were measured from the prestimulus baseline. There was significant decrease in the peak latency of the P2 component during and after meditation (Pmeditation facilitates the processing of information in the auditory association cortex, whereas the number of neurons recruited was smaller in random thinking and non-meditative focused thinking, at the level of the secondary auditory cortex, auditory association cortex and anterior cingulate cortex.

  19. Fatigue as it Affects Nursing.

    Science.gov (United States)

    2016-08-01

    : Editor's note: From its first issue in 1900 through to the present day, AJN has unparalleled archives detailing nurses' work and lives over more than a century. These articles not only chronicle nursing's growth as a profession within the context of the events of the day, but they also reveal prevailing societal attitudes about women, health care, and human rights. Today's nursing school curricula rarely include nursing's history, but it's a history worth knowing. To this end, From the AJN Archives highlights articles selected to fit today's topics and times.In this month's article from the January 1935 issue, Lillian M. Gilbreth, a highly respected psychologist and industrial engineer, examines the problem of fatigue in nursing. A nonnurse expert, Gilbreth notes the negative effects of fatigue on skills, a problem "enormously more serious when the product of the work is human comfort and sometimes even human life, as it often is with the work of the nurse." In their article in this issue, "Health Care Worker Fatigue," Lea Anne Gardner and Deborah Dubeck of the Pennsylvania Patient Safety Authority share examples of fatigue-related adverse events and discuss the need for both personal and institutional fatigue risk management strategies.

  20. Ischemia causes muscle fatigue

    Science.gov (United States)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D. M.

    2001-01-01

    The purpose of this investigation was to determine whether ischemia, which reduces oxygenation in the extensor carpi radialis (ECR) muscle, causes a reduction in muscle force production. In eight subjects, muscle oxygenation (TO2) of the right ECR was measured noninvasively and continuously using near infrared spectroscopy (NIRS) while muscle twitch force was elicited by transcutaneous electrical stimulation (1 Hz, 0.1 ms). Baseline measurements of blood volume, muscle oxygenation and twitch force were recorded continuously, then a tourniquet on the upper arm was inflated to one of five different pressure levels: 20, 40, 60 mm Hg (randomized order) and diastolic (69 +/- 9.8 mm Hg) and systolic (106 +/- 12.8 mm Hg) blood pressures. Each pressure level was maintained for 3-5 min, and was followed by a recovery period sufficient to allow measurements to return to baseline. For each respective tourniquet pressure level, mean TO2 decreased from resting baseline (100% TO2) to 99 +/- 1.2% (SEM), 96 +/- 1.9%, 93 +/- 2.8%, 90 +/- 2.5%, and 86 +/- 2.7%, and mean twitch force decreased from resting baseline (100% force) to 99 +/- 0.7% (SEM), 96 +/- 2.7%, 93 +/- 3.1%, 88 +/- 3.2%, and 86 +/- 2.6%. Muscle oxygenation and twitch force at 60 mm Hg tourniquet compression and above were significantly lower (P ischemia leading to a 7% or greater reduction in muscle oxygenation causes decreased muscle force production in the forearm extensor muscle. Thus, ischemia associated with a modest decline in TO2 causes muscle fatigue.

  1. Ischemia causes muscle fatigue

    Science.gov (United States)

    Murthy, G.; Hargens, A. R.; Lehman, S.; Rempel, D. M.

    2001-01-01

    The purpose of this investigation was to determine whether ischemia, which reduces oxygenation in the extensor carpi radialis (ECR) muscle, causes a reduction in muscle force production. In eight subjects, muscle oxygenation (TO2) of the right ECR was measured noninvasively and continuously using near infrared spectroscopy (NIRS) while muscle twitch force was elicited by transcutaneous electrical stimulation (1 Hz, 0.1 ms). Baseline measurements of blood volume, muscle oxygenation and twitch force were recorded continuously, then a tourniquet on the upper arm was inflated to one of five different pressure levels: 20, 40, 60 mm Hg (randomized order) and diastolic (69 +/- 9.8 mm Hg) and systolic (106 +/- 12.8 mm Hg) blood pressures. Each pressure level was maintained for 3-5 min, and was followed by a recovery period sufficient to allow measurements to return to baseline. For each respective tourniquet pressure level, mean TO2 decreased from resting baseline (100% TO2) to 99 +/- 1.2% (SEM), 96 +/- 1.9%, 93 +/- 2.8%, 90 +/- 2.5%, and 86 +/- 2.7%, and mean twitch force decreased from resting baseline (100% force) to 99 +/- 0.7% (SEM), 96 +/- 2.7%, 93 +/- 3.1%, 88 +/- 3.2%, and 86 +/- 2.6%. Muscle oxygenation and twitch force at 60 mm Hg tourniquet compression and above were significantly lower (P < 0.05) than baseline value. Reduced twitch force was correlated in a dose-dependent manner with reduced muscle oxygenation (r = 0.78, P < 0.001). Although the correlation does not prove causation, the results indicate that ischemia leading to a 7% or greater reduction in muscle oxygenation causes decreased muscle force production in the forearm extensor muscle. Thus, ischemia associated with a modest decline in TO2 causes muscle fatigue.

  2. Fatigue Strain and Damage Analysis of Concrete in Reinforced Concrete Beams under Constant Amplitude Fatigue Loading

    Directory of Open Access Journals (Sweden)

    Fangping Liu

    2016-01-01

    Full Text Available Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equations, the level-S nonlinear evolution model of fatigue strain was constructed, and the physical meaning of the parameters was discussed. Finally, the evolution of fatigue strain and fatigue damage of concrete in the compression zone of the experimental beam was analyzed based on the level-S nonlinear evolution model. The results show that, initially, fatigue strain grows rapidly. In the middle stages, fatigue strain is nearly a linear change. Because the experimental data for the third stage are relatively scarce, the evolution of the strain therefore degenerated into two phases. The model has strong adaptability and high accuracy and can reflect the evolution of fatigue strain. The fatigue damage evolution expression based on fatigue strain shows that fatigue strain and fatigue damage have similar variations, and, with the same load cycles, the greater the load level, the larger the damage, in line with the general rules of damage.

  3. Fatigue and fatigue-related symptoms in patients treated for different causes of hypothyroidism

    NARCIS (Netherlands)

    J.W.K. Louwerens; B.C. Appelhof (Bente); H. Verloop (Herman); M. Medici (Marco); R.P. Peeters (Robin); T.J. Visser (Ton); A. Boelen (Anita); E. Fliers (Eric); J.W.A. Smit (Jan); O.M. Dekkers (Olaf)

    2012-01-01

    textabstractObjective: Research on determinants of well-being in patients on thyroid hormone replacement therapy is warranted, as persistent fatigue-related complaints are common in this population. In this study, we evaluated the impact of different states of hypothyroidism on fatigue and fatigue-r

  4. Fatigue behavior of the magnesium alloy ZK60 in high cycle fatigue

    NARCIS (Netherlands)

    Constantinescu, D.M.; Moldovan, P.; Sillekens, W.H.; Sandu, M.; Apostol, D.A.; Miron, M.C.

    2009-01-01

    Not too much information is available in the literature for establishing fatigue properties of magnesium alloys. A compilation of existing fatigue and fatigue crack growth data of different Mg-alloys has been published by ASM International. One can underline that fatigue properties of some of the st

  5. Chronic Fatigue Syndrome in Gulf War Veterans

    Science.gov (United States)

    ... Enter ZIP code here Enter ZIP code here Chronic Fatigue Syndrome in Gulf War Veterans Gulf War ... and be at least 10 percent disabling. About Chronic Fatigue Syndrome CFS is an unexplained, severe and ...

  6. Peridynamic model for fatigue cracking.

    Energy Technology Data Exchange (ETDEWEB)

    Silling, Stewart Andrew; Abe Askari (Boeing)

    2014-10-01

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the "remaining life" of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  7. Advanced methods of fatigue assessment

    CERN Document Server

    Radaj, Dieter

    2013-01-01

    The book in hand presents advanced methods of brittle fracture and fatigue assessment. The Neuber concept of fictitious notch rounding is enhanced with regard to theory and application. The stress intensity factor concept for cracks is extended to pointed and rounded corner notches as well as to locally elastic-plastic material behaviour. The averaged strain energy density within a circular sector volume around the notch tip is shown to be suitable for strength-assessments. Finally, the various implications of cyclic plasticity on fatigue crack growth are explained with emphasis being laid on the DJ-integral approach.   This book continues the expositions of the authors’ well known reference work in German language ‘Ermüdungsfestigkeit – Grundlagen für Ingenieure’ (Fatigue strength – fundamentals for engineers).

  8. PROBABILISTIC METHODOLOGY OF LOW CYCLE FATIGUE ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    Jin Hui; Wang Jinnuo; Wang Libin

    2003-01-01

    The cyclic stress-strain responses (CSSR), Neuber's rule (NR) and cyclic strain-life relation (CSLR) are treated as probabilistic curves in local stress and strain method of low cycle fatigue analy sis. The randomness of loading and the theory of fatigue damage accumulation (TOFDA) are consid ered. The probabilistic analysis of local stress, local strain and fatigue life are constructed based on the first-order Taylor's series expansions. Through this method proposed fatigue reliability analysis can be accomplished.

  9. Simulation of Stochastic Loads for Fatigue Experiments

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Brincker, Rune

    A simple direct simulation method for stochastic fatigue load generation is described in this paper. The simulation method is based on the assumption that only the peaks of the load process significantly affect the fatigue life. The method requires the conditional distribution functions of load...... second using an IBM PC. Finally the proposed simulation method for fatigue load generation is tested by comparing some fatigue damage measures obtained by the simulation methods....

  10. Fatigue behavior of ADI: Some specific features

    Energy Technology Data Exchange (ETDEWEB)

    Svejcar, J.; Vechet, S.; Pokluda, J. [Technical Univ. of Brno (Czech Republic). Faculty of Mechanical Engineering

    1997-12-31

    The paper summarizes the results of fatigue tests on austempered ductile iron. Attention is mainly focused on the effect of graphite on crack propagation and on some irregularities exhibited by ADI and other ductile irons, e.g., some specific features of fatigue fracture (especially the occurrence of fatigue striations on intergranular facets), decrease of fatigue limit with increasing UTS, and anomalous dependence of loading cycle amplitude on mean cycle stress.

  11. Auditory function in vestibular migraine

    Directory of Open Access Journals (Sweden)

    John Mathew

    2016-01-01

    Full Text Available Introduction: Vestibular migraine (VM is a vestibular syndrome seen in patients with migraine and is characterized by short spells of spontaneous or positional vertigo which lasts between a few seconds to weeks. Migraine and VM are considered to be a result of chemical abnormalities in the serotonin pathway. Neuhauser′s diagnostic criteria for vestibular migraine is widely accepted. Research on VM is still limited and there are few studies which have been published on this topic. Materials and Methods: This study has two parts. In the first part, we did a retrospective chart review of eighty consecutive patients who were diagnosed with vestibular migraine and determined the frequency of auditory dysfunction in these patients. The second part was a prospective case control study in which we compared the audiological parameters of thirty patients diagnosed with VM with thirty normal controls to look for any significant differences. Results: The frequency of vestibular migraine in our population is 22%. The frequency of hearing loss in VM is 33%. Conclusion: There is a significant difference between cases and controls with regards to the presence of distortion product otoacoustic emissions in both ears. This finding suggests that the hearing loss in VM is cochlear in origin.

  12. Auditory sustained field responses to periodic noise

    Directory of Open Access Journals (Sweden)

    Keceli Sumru

    2012-01-01

    Full Text Available Abstract Background Auditory sustained responses have been recently suggested to reflect neural processing of speech sounds in the auditory cortex. As periodic fluctuations below the pitch range are important for speech perception, it is necessary to investigate how low frequency periodic sounds are processed in the human auditory cortex. Auditory sustained responses have been shown to be sensitive to temporal regularity but the relationship between the amplitudes of auditory evoked sustained responses and the repetitive rates of auditory inputs remains elusive. As the temporal and spectral features of sounds enhance different components of sustained responses, previous studies with click trains and vowel stimuli presented diverging results. In order to investigate the effect of repetition rate on cortical responses, we analyzed the auditory sustained fields evoked by periodic and aperiodic noises using magnetoencephalography. Results Sustained fields were elicited by white noise and repeating frozen noise stimuli with repetition rates of 5-, 10-, 50-, 200- and 500 Hz. The sustained field amplitudes were significantly larger for all the periodic stimuli than for white noise. Although the sustained field amplitudes showed a rising and falling pattern within the repetition rate range, the response amplitudes to 5 Hz repetition rate were significantly larger than to 500 Hz. Conclusions The enhanced sustained field responses to periodic noises show that cortical sensitivity to periodic sounds is maintained for a wide range of repetition rates. Persistence of periodicity sensitivity below the pitch range suggests that in addition to processing the fundamental frequency of voice, sustained field generators can also resolve low frequency temporal modulations in speech envelope.

  13. SIMULATION OF COMPLEX THERMOMECHANICAL FATIGUE

    Institute of Scientific and Technical Information of China (English)

    R.Bardenheier; G.Rogers

    2004-01-01

    Two different types of experimental techniques to perform non-isothermal, unicxial and biaxial fatigue testa were described. A new miniaturised electrothermalmechanical test rig was presented and discussed. It enables testing of small specimens under complex thermomechanical loading conditions. In order to cope with the simulation of well defined biaxial proportional and non-proportional loadings with in-phase and out-of-phase superposition of thermal loads a cruciform biaxial fatigue testing machine has been developed. Special design features of both machines, and the specimens tested, as well as typical test results were discussed.

  14. Risk Based Optimal Fatigue Testing

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Faber, M.H.; Kroon, I.B.

    1992-01-01

    Optimal fatigue life testing of materials is considered. Based on minimization of the total expected costs of a mechanical component a strategy is suggested to determine the optimal stress range levels for which additional experiments are to be performed together with an optimal value of the maxi......Optimal fatigue life testing of materials is considered. Based on minimization of the total expected costs of a mechanical component a strategy is suggested to determine the optimal stress range levels for which additional experiments are to be performed together with an optimal value...

  15. Strain Measurement Technology for Corrosion Fatigue Specimen

    Institute of Scientific and Technical Information of China (English)

    ZHONG; Wei-hua; NING; Guang-sheng; ZHANG; Chang-yi; TONG; Zhen-feng; YANG; Wen

    2015-01-01

    Main pipeline is the key component of nuclear power plants(NPPs).Under the first loop water and low-cyclic load condition,the main pipeline may be induced to corrosion fatigue failure.Thus,it’s necessary to test and get the corrosion fatigue property of main pipeline material.During the corrosion fatigue test,the strain

  16. Fatigue in traffic : causes and effects.

    NARCIS (Netherlands)

    2006-01-01

    The role of fatigue must not be underestimated when studying the causes of crashes. Crashes in which driver fatigue plays a role are not only a matter of having spent too long behind the wheel; fatigue can also be caused by too little sleep, stress, or the time of the day. According to a conservativ

  17. Fatigue, depression and progression in multiple sclerosis

    NARCIS (Netherlands)

    Koch, M.; Uyttenboogaart, Maarten; van Harten, A.; Heerings, M.; De Keyser, J.

    2008-01-01

    Objective To investigate the effect of fatigue and depression on disease progression in multiple sclerosis (MS), and the long-term prognosis of these symptoms. Methods 228 patients with MS were investigated for fatigue and depression with the Fatigue Severity Scale (FSS) and Center for Epidemiologic

  18. Study of the Neurophysiology of Central Fatigue

    Science.gov (United States)

    2014-11-05

    objective cognitive fatigue using event related potentials ( ERPs ). 2) To determine the neurophysiologic mechanisms underlying objective cognitive fatigue...with objective cognitive fatigue using event related potentials ( ERPs ). 2) To determine the neurophysiologic mechanisms underlying objective...performance changes. (Abstract published, manuscript under review) 4) Single trial ERP analyses reveal that noise (jitter) and amplitude changes

  19. The probability distribution of fatigue damage and the statistical moment of fatigue life

    Institute of Scientific and Technical Information of China (English)

    熊峻江; 高镇同

    1997-01-01

    The randomization of deterministic fatigue damage equation leads to the stochastic differential equation and the Fokker-Planck equation affected by random fluctuation. By means of the solution of equation, the probability distribution of fatigue damage with the change of time is obtained. Then the statistical moment of fatigue life in consideration of the stationary random fluctuation is derived. Finally, the damage probability distributions during the fatigue crack initiation and fatigue crack growth are given

  20. Fatigue Analysis and Life Prediction of Dumpers with Cumulative Fatigue Damage Approach

    Institute of Scientific and Technical Information of China (English)

    LI Shouju; LIU Yingxi; SUN Huiling

    2004-01-01

    A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element analysis is carried out for assessing stress distribution and strength characteristics of dumpers. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule. The investigation shows that fatigue notch factor has a significant influence on the calculation of fatigue damage of dumpers.

  1. Current status of auditory aging and anti-aging research.

    Science.gov (United States)

    Ruan, Qingwei; Ma, Cheng; Zhang, Ruxin; Yu, Zhuowei

    2014-01-01

    The development of presbycusis, or age-related hearing loss, is determined by a combination of genetic and environmental factors. The auditory periphery exhibits a progressive bilateral, symmetrical reduction of auditory sensitivity to sound from high to low frequencies. The central auditory nervous system shows symptoms of decline in age-related cognitive abilities, including difficulties in speech discrimination and reduced central auditory processing, ultimately resulting in auditory perceptual abnormalities. The pathophysiological mechanisms of presbycusis include excitotoxicity, oxidative stress, inflammation, aging and oxidative stress-induced DNA damage that results in apoptosis in the auditory pathway. However, the originating signals that trigger these mechanisms remain unclear. For instance, it is still unknown whether insulin is involved in auditory aging. Auditory aging has preclinical lesions, which manifest as asymptomatic loss of periphery auditory nerves and changes in the plasticity of the central auditory nervous system. Currently, the diagnosis of preclinical, reversible lesions depends on the detection of auditory impairment by functional imaging, and the identification of physiological and molecular biological markers. However, despite recent improvements in the application of these markers, they remain under-utilized in clinical practice. The application of antisenescent approaches to the prevention of auditory aging has produced inconsistent results. Future research will focus on the identification of markers for the diagnosis of preclinical auditory aging and the development of effective interventions.

  2. Experience and information loss in auditory and visual memory.

    Science.gov (United States)

    Gloede, Michele E; Paulauskas, Emily E; Gregg, Melissa K

    2017-07-01

    Recent studies show that recognition memory for sounds is inferior to memory for pictures. Four experiments were conducted to examine the nature of auditory and visual memory. Experiments 1-3 were conducted to evaluate the role of experience in auditory and visual memory. Participants received a study phase with pictures/sounds, followed by a recognition memory test. Participants then completed auditory training with each of the sounds, followed by a second memory test. Despite auditory training in Experiments 1 and 2, visual memory was superior to auditory memory. In Experiment 3, we found that it is possible to improve auditory memory, but only after 3 days of specific auditory training and 3 days of visual memory decay. We examined the time course of information loss in auditory and visual memory in Experiment 4 and found a trade-off between visual and auditory recognition memory: Visual memory appears to have a larger capacity, while auditory memory is more enduring. Our results indicate that visual and auditory memory are inherently different memory systems and that differences in visual and auditory recognition memory performance may be due to the different amounts of experience with visual and auditory information, as well as structurally different neural circuitry specialized for information retention.

  3. The specificity of stimulus-specific adaptation in human auditory cortex increases with repeated exposure to the adapting stimulus.

    Science.gov (United States)

    Briley, Paul M; Krumbholz, Katrin

    2013-12-01

    The neural response to a sensory stimulus tends to be more strongly reduced when the stimulus is preceded by the same, rather than a different, stimulus. This stimulus-specific adaptation (SSA) is ubiquitous across the senses. In hearing, SSA has been suggested to play a role in change detection as indexed by the mismatch negativity. This study sought to test whether SSA, measured in human auditory cortex, is caused by neural fatigue (reduction in neural responsiveness) or by sharpening of neural tuning to the adapting stimulus. For that, we measured event-related cortical potentials to pairs of pure tones with varying frequency separation and stimulus onset asynchrony (SOA). This enabled us to examine the relationship between the degree of specificity of adaptation as a function of frequency separation and the rate of decay of adaptation with increasing SOA. Using simulations of tonotopic neuron populations, we demonstrate that the fatigue model predicts independence of adaptation specificity and decay rate, whereas the sharpening model predicts interdependence. The data showed independence and thus supported the fatigue model. In a second experiment, we measured adaptation specificity after multiple presentations of the adapting stimulus. The multiple adapters produced more adaptation overall, but the effect was more specific to the adapting frequency. Within the context of the fatigue model, the observed increase in adaptation specificity could be explained by assuming a 2.5-fold increase in neural frequency selectivity. We discuss possible bottom-up and top-down mechanisms of this effect.

  4. Effects of Caffeine on Auditory Brainstem Response

    Directory of Open Access Journals (Sweden)

    Saleheh Soleimanian

    2008-06-01

    Full Text Available Background and Aim: Blocking of the adenosine receptor in central nervous system by caffeine can lead to increasing the level of neurotransmitters like glutamate. As the adenosine receptors are present in almost all brain areas like central auditory pathway, it seems caffeine can change conduction in this way. The purpose of this study was to evaluate the effects of caffeine on latency and amplitude of auditory brainstem response(ABR.Materials and Methods: In this clinical trial study 43 normal 18-25 years old male students were participated. The subjects consumed 0, 2 and 3 mg/kg BW caffeine in three different sessions. Auditory brainstem responses were recorded before and 30 minute after caffeine consumption. The results were analyzed by Friedman and Wilcoxone test to assess the effects of caffeine on auditory brainstem response.Results: Compared to control group the latencies of waves III,V and I-V interpeak interval of the cases decreased significantly after 2 and 3mg/kg BW caffeine consumption. Wave I latency significantly decreased after 3mg/kg BW caffeine consumption(p<0.01. Conclusion: Increasing of the glutamate level resulted from the adenosine receptor blocking brings about changes in conduction in the central auditory pathway.

  5. Facilitated auditory detection for speech sounds.

    Science.gov (United States)

    Signoret, Carine; Gaudrain, Etienne; Tillmann, Barbara; Grimault, Nicolas; Perrin, Fabien

    2011-01-01

    If it is well known that knowledge facilitates higher cognitive functions, such as visual and auditory word recognition, little is known about the influence of knowledge on detection, particularly in the auditory modality. Our study tested the influence of phonological and lexical knowledge on auditory detection. Words, pseudo-words, and complex non-phonological sounds, energetically matched as closely as possible, were presented at a range of presentation levels from sub-threshold to clearly audible. The participants performed a detection task (Experiments 1 and 2) that was followed by a two alternative forced-choice recognition task in Experiment 2. The results of this second task in Experiment 2 suggest a correct recognition of words in the absence of detection with a subjective threshold approach. In the detection task of both experiments, phonological stimuli (words and pseudo-words) were better detected than non-phonological stimuli (complex sounds), presented close to the auditory threshold. This finding suggests an advantage of speech for signal detection. An additional advantage of words over pseudo-words was observed in Experiment 2, suggesting that lexical knowledge could also improve auditory detection when listeners had to recognize the stimulus in a subsequent task. Two simulations of detection performance performed on the sound signals confirmed that the advantage of speech over non-speech processing could not be attributed to energetic differences in the stimuli.

  6. Facilitated auditory detection for speech sounds

    Directory of Open Access Journals (Sweden)

    Carine eSignoret

    2011-07-01

    Full Text Available If it is well known that knowledge facilitates higher cognitive functions, such as visual and auditory word recognition, little is known about the influence of knowledge on detection, particularly in the auditory modality. Our study tested the influence of phonological and lexical knowledge on auditory detection. Words, pseudo words and complex non phonological sounds, energetically matched as closely as possible, were presented at a range of presentation levels from sub threshold to clearly audible. The participants performed a detection task (Experiments 1 and 2 that was followed by a two alternative forced choice recognition task in Experiment 2. The results of this second task in Experiment 2 suggest a correct recognition of words in the absence of detection with a subjective threshold approach. In the detection task of both experiments, phonological stimuli (words and pseudo words were better detected than non phonological stimuli (complex sounds, presented close to the auditory threshold. This finding suggests an advantage of speech for signal detection. An additional advantage of words over pseudo words was observed in Experiment 2, suggesting that lexical knowledge could also improve auditory detection when listeners had to recognize the stimulus in a subsequent task. Two simulations of detection performance performed on the sound signals confirmed that the advantage of speech over non speech processing could not be attributed to energetic differences in the stimuli.

  7. Absence of auditory 'global interference' in autism.

    Science.gov (United States)

    Foxton, Jessica M; Stewart, Mary E; Barnard, Louise; Rodgers, Jacqui; Young, Allan H; O'Brien, Gregory; Griffiths, Timothy D

    2003-12-01

    There has been considerable recent interest in the cognitive style of individuals with Autism Spectrum Disorder (ASD). One theory, that of weak central coherence, concerns an inability to combine stimulus details into a coherent whole. Here we test this theory in the case of sound patterns, using a new definition of the details (local structure) and the coherent whole (global structure). Thirteen individuals with a diagnosis of autism or Asperger's syndrome and 15 control participants were administered auditory tests, where they were required to match local pitch direction changes between two auditory sequences. When the other local features of the sequence pairs were altered (the actual pitches and relative time points of pitch direction change), the control participants obtained lower scores compared with when these details were left unchanged. This can be attributed to interference from the global structure, defined as the combination of the local auditory details. In contrast, the participants with ASD did not obtain lower scores in the presence of such mismatches. This was attributed to the absence of interference from an auditory coherent whole. The results are consistent with the presence of abnormal interactions between local and global auditory perception in ASD.

  8. Fatigue Reliability of Offshore Wind Turbine Systems

    DEFF Research Database (Denmark)

    Marquez-Dominguez, Sergio; Sørensen, John Dalsgaard

    2012-01-01

    Optimization of the design of offshore wind turbine substructures with respect to fatigue loads is an important issue in offshore wind energy. A stochastic model is developed for assessing the fatigue failure reliability. This model can be used for direct probabilistic design and for calibration...... of appropriate partial safety factors / fatigue design factors (FDF) for steel substructures of offshore wind turbines (OWTs). The fatigue life is modeled by the SN approach. Design and limit state equations are established based on the accumulated fatigue damage. The acceptable reliability level for optimal...

  9. How surface damage removal affects fatigue life

    Science.gov (United States)

    Jeelani, S.; Scott, M. A.

    1988-01-01

    The effect of the removal of work hardened surface layers from specimens of 2024-T4 aluminum alloy and AISI-4130 steel on their fatigue lives has been investigated. Specimens were fatigued at selected stress levels for a given number of cycles, and the surface layer was removed followed by subsequent fatigue cycling. Results confirm that when a material is subjected to fatigue loading, damage accumulates in the surface layers in the form of work hardening. Removal of the surface layer brings the specimen back to its pre-fatigued condition.

  10. Assessing Fatigue in Late-Midlife

    DEFF Research Database (Denmark)

    Fieo, Robert A; Mortensen, Erik Lykke; Lund, Rikke

    2014-01-01

    late-midlife subjects. Five subdimensions of perceived fatigue were examined in n = 7,233 subjects: general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue. Fatigue burden was compared across age groups (aged 48-52 vs. 57-63) and gender. Mokken item response theory...... was used to investigate dimensionality, monotonicity, and invariant item ordering (IIO). In both age groups, as well as by gender, the Motivation domain presented with weak scalability, suggesting that caution be exercised when interpreting sum scores. For all groupings, the strongest scaling properties...

  11. The effect of background music in auditory health persuasion

    NARCIS (Netherlands)

    Elbert, Sarah; Dijkstra, Arie

    2013-01-01

    In auditory health persuasion, threatening information regarding health is communicated by voice only. One relevant context of auditory persuasion is the addition of background music. There are different mechanisms through which background music might influence persuasion, for example through mood (

  12. The role of temporal coherence in auditory stream segregation

    DEFF Research Database (Denmark)

    Christiansen, Simon Krogholt

    The ability to perceptually segregate concurrent sound sources and focus one’s attention on a single source at a time is essential for the ability to use acoustic information. While perceptual experiments have determined a range of acoustic cues that help facilitate auditory stream segregation......, it is not clear how the auditory system realizes the task. This thesis presents a study of the mechanisms involved in auditory stream segregation. Through a combination of psychoacoustic experiments, designed to characterize the influence of acoustic cues on auditory stream formation, and computational models...... of auditory processing, the role of auditory preprocessing and temporal coherence in auditory stream formation was evaluated. The computational model presented in this study assumes that auditory stream segregation occurs when sounds stimulate non-overlapping neural populations in a temporally incoherent...

  13. Auditory imagery and the poor-pitch singer.

    Science.gov (United States)

    Pfordresher, Peter Q; Halpern, Andrea R

    2013-08-01

    The vocal imitation of pitch by singing requires one to plan laryngeal movements on the basis of anticipated target pitch events. This process may rely on auditory imagery, which has been shown to activate motor planning areas. As such, we hypothesized that poor-pitch singing, although not typically associated with deficient pitch perception, may be associated with deficient auditory imagery. Participants vocally imitated simple pitch sequences by singing, discriminated pitch pairs on the basis of pitch height, and completed an auditory imagery self-report questionnaire (the Bucknell Auditory Imagery Scale). The percentage of trials participants sung in tune correlated significantly with self-reports of vividness for auditory imagery, although not with the ability to control auditory imagery. Pitch discrimination was not predicted by auditory imagery scores. The results thus support a link between auditory imagery and vocal imitation.

  14. Intradermal melanocytic nevus of the external auditory canal.

    Science.gov (United States)

    Alves, Renato V; Brandão, Fabiano H; Aquino, José E P; Carvalho, Maria R M S; Giancoli, Suzana M; Younes, Eduado A P

    2005-01-01

    Intradermal nevi are common benign pigmented skin tumors. Their occurrence within the external auditory canal is uncommon. The clinical and pathologic features of an intradermal nevus arising within the external auditory canal are presented, and the literature reviewed.

  15. What determines auditory distraction? On the roles of local auditory changes and expectation violations.

    Directory of Open Access Journals (Sweden)

    Jan P Röer

    Full Text Available Both the acoustic variability of a distractor sequence and the degree to which it violates expectations are important determinants of auditory distraction. In four experiments we examined the relative contribution of local auditory changes on the one hand and expectation violations on the other hand in the disruption of serial recall by irrelevant sound. We present evidence for a greater disruption by auditory sequences ending in unexpected steady state distractor repetitions compared to auditory sequences with expected changing state endings even though the former contained fewer local changes. This effect was demonstrated with piano melodies (Experiment 1 and speech distractors (Experiment 2. Furthermore, it was replicated when the expectation violation occurred after the encoding of the target items (Experiment 3, indicating that the items' maintenance in short-term memory was disrupted by attentional capture and not their encoding. This seems to be primarily due to the violation of a model of the specific auditory distractor sequences because the effect vanishes and even reverses when the experiment provides no opportunity to build up a specific neural model about the distractor sequence (Experiment 4. Nevertheless, the violation of abstract long-term knowledge about auditory regularities seems to cause a small and transient capture effect: Disruption decreased markedly over the course of the experiments indicating that participants habituated to the unexpected distractor repetitions across trials. The overall pattern of results adds to the growing literature that the degree to which auditory distractors violate situation-specific expectations is a more important determinant of auditory distraction than the degree to which a distractor sequence contains local auditory changes.

  16. ABR and auditory P300 findings inchildren with ADHD

    OpenAIRE

    Schochat Eliane; Scheuer Claudia Ines; Andrade Ênio Roberto de

    2002-01-01

    Auditory processing disorders (APD), also referred as central auditory processing disorders (CAPD) and attention deficit hyperactivity disorders (ADHD) have become popular diagnostic entities for school age children. It has been demonstrated a high incidence of comorbid ADHD with communication disorders and auditory processing disorder. The aim of this study was to investigate ABR and P300 auditory evoked potentials in children with ADHD, in a double-blind study. Twenty-one children, ages bet...

  17. Auditory and motor imagery modulate learning in music performance

    Directory of Open Access Journals (Sweden)

    Rachel M. Brown

    2013-07-01

    Full Text Available Skilled performers such as athletes or musicians can improve their performance by imagining the actions or sensory outcomes associated with their skill. Performers vary widely in their auditory and motor imagery abilities, and these individual differences influence sensorimotor learning. It is unknown whether imagery abilities influence both memory encoding and retrieval. We examined how auditory and motor imagery abilities influence musicians’ encoding (during Learning, as they practiced novel melodies, and retrieval (during Recall of those melodies. Pianists learned melodies by listening without performing (auditory learning or performing without sound (motor learning; following Learning, pianists performed the melodies from memory with auditory feedback (Recall. During either Learning (Experiment 1 or Recall (Experiment 2, pianists experienced either auditory interference, motor interference, or no interference. Pitch accuracy (percentage of correct pitches produced and temporal regularity (variability of quarter-note interonset intervals were measured at Recall. Independent tests measured auditory and motor imagery skills. Pianists’ pitch accuracy was higher following auditory learning than following motor learning and lower in motor interference conditions (Experiments 1 and 2. Both auditory and motor imagery skills improved pitch accuracy overall. Auditory imagery skills modulated pitch accuracy encoding (Experiment 1: Higher auditory imagery skill corresponded to higher pitch accuracy following auditory learning with auditory or motor interference, and following motor learning with motor or no interference. These findings suggest that auditory imagery abilities decrease vulnerability to interference and compensate for missing auditory feedback at encoding. Auditory imagery skills also influenced temporal regularity at retrieval (Experiment 2: Higher auditory imagery skill predicted greater temporal regularity during Recall in the

  18. Are auditory percepts determined by experience?

    Science.gov (United States)

    Monson, Brian B; Han, Shui'Er; Purves, Dale

    2013-01-01

    Audition--what listeners hear--is generally studied in terms of the physical properties of sound stimuli and physiological properties of the auditory system. Based on recent work in vision, we here consider an alternative perspective that sensory percepts are based on past experience. In this framework, basic auditory qualities (e.g., loudness and pitch) are based on the frequency of occurrence of stimulus patterns in natural acoustic stimuli. To explore this concept of audition, we examined five well-documented psychophysical functions. The frequency of occurrence of acoustic patterns in a database of natural sound stimuli (speech) predicts some qualitative aspects of these functions, but with substantial quantitative discrepancies. This approach may offer a rationale for auditory phenomena that are difficult to explain in terms of the physical attributes of the stimuli as such.

  19. Are auditory percepts determined by experience?

    Directory of Open Access Journals (Sweden)

    Brian B Monson

    Full Text Available Audition--what listeners hear--is generally studied in terms of the physical properties of sound stimuli and physiological properties of the auditory system. Based on recent work in vision, we here consider an alternative perspective that sensory percepts are based on past experience. In this framework, basic auditory qualities (e.g., loudness and pitch are based on the frequency of occurrence of stimulus patterns in natural acoustic stimuli. To explore this concept of audition, we examined five well-documented psychophysical functions. The frequency of occurrence of acoustic patterns in a database of natural sound stimuli (speech predicts some qualitative aspects of these functions, but with substantial quantitative discrepancies. This approach may offer a rationale for auditory phenomena that are difficult to explain in terms of the physical attributes of the stimuli as such.

  20. Phonetic categorization in auditory word perception.

    Science.gov (United States)

    Ganong, W F

    1980-02-01

    To investigate the interaction in speech perception of auditory information and lexical knowledge (in particular, knowledge of which phonetic sequences are words), acoustic continua varying in voice onset time were constructed so that for each acoustic continuum, one of the two possible phonetic categorizations made a word and the other did not. For example, one continuum ranged between the word dash and the nonword tash; another used the nonword dask and the word task. In two experiments, subjects showed a significant lexical effect--that is, a tendency to make phonetic categorizations that make words. This lexical effect was greater at the phoneme boundary (where auditory information is ambiguous) than at the ends of the condinua. Hence the lexical effect must arise at a stage of processing sensitive to both lexical knowledge and auditory information.

  1. [Functional neuroimaging of auditory hallucinations in schizophrenia].

    Science.gov (United States)

    Font, M; Parellada, E; Fernández-Egea, E; Bernardo, M; Lomeña, F

    2003-01-01

    The neurobiological bases underlying the generation of auditory hallucinations, a distressing and paradigmatic symptom of schizophrenia, are still unknown in spite of in-depth phenomenological descriptions. This work aims to make a critical review of the latest published literature in recent years, focusing on functional neuroimaging studies (PET, SPECT, fMRI) of auditory hallucinations. Thus, the studies are classified according to whether they are sensory activation, trait and state. The two main hypotheses proposed to explain the phenomenon, external speech vs. subvocal or inner speech, are also explained. Finally, the latest unitary theory as well as the limitations the studies published are commented on. The need to continue investigating in this field, that is still underdeveloped, is posed in order to understand better the etiopathogenesis of auditory hallucinations in schizophrenia.

  2. The mitochondrial connection in auditory neuropathy.

    Science.gov (United States)

    Cacace, Anthony T; Pinheiro, Joaquim M B

    2011-01-01

    'Auditory neuropathy' (AN), the term used to codify a primary degeneration of the auditory nerve, can be linked directly or indirectly to mitochondrial dysfunction. These observations are based on the expression of AN in known mitochondrial-based neurological diseases (Friedreich's ataxia, Mohr-Tranebjærg syndrome), in conditions where defects in axonal transport, protein trafficking, and fusion processes perturb and/or disrupt mitochondrial dynamics (Charcot-Marie-Tooth disease, autosomal dominant optic atrophy), in a common neonatal condition known to be toxic to mitochondria (hyperbilirubinemia), and where respiratory chain deficiencies produce reductions in oxidative phosphorylation that adversely affect peripheral auditory mechanisms. This body of evidence is solidified by data derived from temporal bone and genetic studies, biochemical, molecular biologic, behavioral, electroacoustic, and electrophysiological investigations.

  3. The auditory hallucination: a phenomenological survey.

    Science.gov (United States)

    Nayani, T H; David, A S

    1996-01-01

    A comprehensive semi-structured questionnaire was administered to 100 psychotic patients who had experienced auditory hallucinations. The aim was to extend the phenomenology of the hallucination into areas of both form and content and also to guide future theoretical development. All subjects heard 'voices' talking to or about them. The location of the voice, its characteristics and the nature of address were described. Precipitants and alleviating factors plus the effect of the hallucinations on the sufferer were identified. Other hallucinatory experiences, thought insertion and insight were examined for their inter-relationships. A pattern emerged of increasing complexity of the auditory-verbal hallucination over time by a process of accretion, with the addition of more voices and extended dialogues, and more intimacy between subject and voice. Such evolution seemed to relate to the lessening of distress and improved coping. These findings should inform both neurological and cognitive accounts of the pathogenesis of auditory hallucinations in psychotic disorders.

  4. Cooperative dynamics in auditory brain response

    CERN Document Server

    Kwapien, J; Liu, L C; Ioannides, A A

    1998-01-01

    Simultaneous estimates of the activity in the left and right auditory cortex of five normal human subjects were extracted from Multichannel Magnetoencephalography recordings. Left, right and binaural stimulation were used, in separate runs, for each subject. The resulting time-series of left and right auditory cortex activity were analysed using the concept of mutual information. The analysis constitutes an objective method to address the nature of inter-hemispheric correlations in response to auditory stimulations. The results provide a clear evidence for the occurrence of such correlations mediated by a direct information transport, with clear laterality effects: as a rule, the contralateral hemisphere leads by 10-20ms, as can be seen in the average signal. The strength of the inter-hemispheric coupling, which cannot be extracted from the average data, is found to be highly variable from subject to subject, but remarkably stable for each subject.

  5. Auditory temporal processes in the elderly

    Directory of Open Access Journals (Sweden)

    E. Ben-Artzi

    2011-03-01

    Full Text Available Several studies have reported age-related decline in auditory temporal resolution and in working memory. However, earlier studies did not provide evidence as to whether these declines reflect overall changes in the same mechanisms, or reflect age-related changes in two independent mechanisms. In the current study we examined whether the age-related decline in auditory temporal resolution and in working memory would remain significant even after controlling for their shared variance. Eighty-two participants, aged 21-82 performed the dichotic temporal order judgment task and the backward digit span task. The findings indicate that age-related decline in auditory temporal resolution and in working memory are two independent processes.

  6. Titanium in fatigue critical military aircraft structure

    Energy Technology Data Exchange (ETDEWEB)

    Gillespie, F.

    1999-07-01

    This paper discusses the effect of fatigue requirements on titanium structure in military aircraft applications, specifically, fighter aircraft. The discussion covers how fatigue affects the design and analysis of detail parts, and how manufacturing processes affect the fatigue performance of titanium structure. Criteria for designing fighter aircraft have evolved from simple strength calculations to extremely complex computer generated analyses involving strength, durability, damage tolerance and fatigue. Fatigue life prediction is an important part of these analyses and dramatically affects the design and weight of fighter aircraft. Manufacturing processes affect fatigue performance both in a positive and negative manner. Designers must allow for the effect of these processes on titanium structure and consider the efficiency and economy of adding processes that increase fatigue life.

  7. Adults living with heart failure and fatigue

    DEFF Research Database (Denmark)

    Schjødt, Inge; Sommer, Irene; Bjerrum, Merete

    Background Fatigue is one of the most common symptoms reported by patients with heart failure (HF). Fatigue negatively impacts on patients’ everyday life, prognosis and quality of life. No specific cure or effective interventions to alleviate fatigue are available. Over the past decade, qualitative...... To synthesise the best available evidence related to the lived experiences and management of fatigue in everyday life in adult patients with stable heart failure to develop effective interventions to support self-care. Specific questions on the patients’ lived experiences included: • How do patients with HF...... describe their experiences of fatigue? • How do patients with HF perceive the impact of fatigue in everyday life? • How do patients with HF manage fatigue and its consequences in everyday life? Methods A systematic literature search for published and unpublished studies 1995-2012 was carried out from...

  8. Fatigue and Depressive Symptoms in Older People

    DEFF Research Database (Denmark)

    Mänty, Minna; Rantanen, Taina; Era, Pertti

    2014-01-01

    Fatigue is considered an important indicator of aging-related declines in health and functional abilities. Previous studies have indicated strong associations between fatigue and depressive symptoms among younger populations and in patient groups with specific diseases. However, it is not known how...... different measures of fatigue are associated with depressive symptoms among general older populations. The purpose of this study is to describe the prevalence of depressive symptoms among community-dwelling older adults reporting mobility-related or general feelings fatigue. The study population consisted...... of 75-year-old community-living individuals (n = 561). Both, mobility-related and general fatigue, were associated in a stepwise relationship with depressive symptoms: a higher level of fatigue was related to higher level of depressive symptoms. Especially major general fatigue was strongly associated...

  9. Fatigue processes in thermoplastic fibres; Les mecanismes de fatigue dans les fibres thermoplastiques

    Energy Technology Data Exchange (ETDEWEB)

    Herrera Ramirez, J.M.

    2004-09-15

    The present study examines and compares the behaviour of the two types of PA66 fibres and two types of PET fibres under fatigue loading up to failure, and the correlation between the fibres (nano)structures and their structural heterogeneities, with fatigue lifetimes. Several techniques have been used to analyze the materials, such as scanning electron microscopy (SEM), microanalysis (EDS), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and micro-Raman spectroscopy. A meticulous analysis by scanning electron microscopy of the fracture morphology of fibres broken in tension and in fatigue, as well as a study of the fatigue life, were undertaken. The fatigue process occurs when the cyclic load amplitude is sufficiently large, however a condition for fatigue failure is that the minimum load each cycle must be lower than a threshold stress level. Failure under fatigue conditions leads to distinctive fracture morphologies which are very different from those seen after tensile or creep failure and this allows easy identification of the fatigue process. The fibres have been analyzed in the as received state and after fatigue failure in order to observe the microstructural changes resulting from the fatigue loading. The results will be compared with those obtained for fibres loaded under conditions where the fatigue process was hindered. The role of the microstructure of the fibres in determining fatigue will be discussed in this work and the possibility of improving their resistance to fatigue or eliminating the fatigue process will be discussed. (author)

  10. Do dyslexics have auditory input processing difficulties?

    DEFF Research Database (Denmark)

    Poulsen, Mads

    2011-01-01

    Word production difficulties are well documented in dyslexia, whereas the results are mixed for receptive phonological processing. This asymmetry raises the possibility that the core phonological deficit of dyslexia is restricted to output processing stages. The present study investigated whether...... a group of dyslexics had word level receptive difficulties using an auditory lexical decision task with long words and nonsense words. The dyslexics were slower and less accurate than chronological age controls in an auditory lexical decision task, with disproportionate low performance on nonsense words...

  11. The many facets of auditory display

    Science.gov (United States)

    Blattner, Meera M.

    1995-01-01

    In this presentation we will examine some of the ways sound can be used in a virtual world. We make the case that many different types of audio experience are available to us. A full range of audio experiences include: music, speech, real-world sounds, auditory displays, and auditory cues or messages. The technology of recreating real-world sounds through physical modeling has advanced in the past few years allowing better simulation of virtual worlds. Three-dimensional audio has further enriched our sensory experiences.

  12. Transient auditory hallucinations in an adolescent.

    Science.gov (United States)

    Skokauskas, Norbert; Pillay, Devina; Moran, Tom; Kahn, David A

    2010-05-01

    In adolescents, hallucinations can be a transient illness or can be associated with non-psychotic psychopathology, psychosocial adversity, or a physical illness. We present the case of a 15-year-old secondary-school student who presented with a 1-month history of first onset auditory hallucinations, which had been increasing in frequency and severity, and mild paranoid ideation. Over a 10-week period, there was a gradual diminution, followed by a complete resolution, of symptoms. We discuss issues regarding the diagnosis and prognosis of auditory hallucinations in adolescents.

  13. Frequency dependence of fatigue and corrosion fatigue crack growth rate

    Energy Technology Data Exchange (ETDEWEB)

    Marvasti, Mohammad Hassan; Chen, Weixing [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB (Canada); Kania, Richard; Worthingham, Robert [TransCanada Pipelines Limited, Calgary, AB (Canada); Van Boven, Gregory [Spectra Energy Transmission Limited, Vancouver, BC (Canada)

    2010-07-01

    It was in the mid-1980s that stress corrosion cracking (SCC) was first found in near-neutral pH conditions on the TransCanada pipeline system. Since then, there have been many reports of pipeline cracking in Canada in these conditions. The huge quantity of pipelines in Canada and the number of failures have brought great interest in investigation of this cracking. A study was conducted on one X52 pipeline steel. It used compact tension specimens for corrosion fatigue and fatigue tests in air. The following conclusions were drawn: 1) crack growth in near-neutral pH conditions can be explained by a factor, which reflects the combined action of the mechanical driving force and the hydrogen effects; 2) mechanical dormancy can be common when oil and gas pipelines are in operation; 3) hydrogen is a determining factor of crack growth when pipeline steels are exposed to near-neutral pH conditions.

  14. Fatigue of Dental Implants: Facts and Fallacies

    Directory of Open Access Journals (Sweden)

    Keren Shemtov-Yona

    2016-05-01

    Full Text Available Dental implants experience rare yet problematic mechanical failures such as fracture that are caused, most often, by (time-dependent metal fatigue. This paper surveys basic evidence about fatigue failure, its identification and the implant’s fatigue performance during service. We first discuss the concept of dental implant fatigue, starting with a review of basic concepts related to this failure mechanism. The identification of fatigue failures using scanning electron microscopy follows, to show that this stage is fairly well defined. We reiterate that fatigue failure is related to the implant design and its surface condition, together with the widely varying service conditions. The latter are shown to vary to an extent that precludes devising average or representative conditions. The statistical nature of the fatigue test results is emphasized throughout the survey to illustrate the complexity in evaluating the fatigue behavior of dental implants from a design perspective. Today’s fatigue testing of dental implants is limited to ISO 14801 standard requirements, which ensures certification but does not provide any insight for design purposes due to its limited requirements. We introduce and discuss the random spectrum loading procedure as an alternative to evaluate the implant’s performance under more realistic conditions. The concept is illustrated by random fatigue testing in 0.9% saline solution.

  15. Fatigue in cancer: A review of literature

    Directory of Open Access Journals (Sweden)

    Vijayakumar Narayanan

    2009-01-01

    Full Text Available Fatigue is a common symptom of advanced cancer limiting one′s activity and affecting the quality of life. It is a multidimensional symptom complex with subjective and objective components. Hence, its definition and assessment seems arbitrary, incomplete, and elusive. Components of fatigue often merge with other ′disease states′ as anemia, depression and so on, compounding difficulty to assess it separately. Fatigue has a high prevalence rate, and lasts longer in chronic diseases like cancer. Its association with treatment modalities like chemotherapy, radiotherapy alongside the primary disease process makes it seemingly ubiquitous in many cases. Systemic manifestation of cancer causes excess demand on body resources on cell repair, uncontrolled growth with metabolite accumulation causing fatigue. Co-morbid conditions of organic and psychological nature causes fatigue. There are many assessment tools for fatigue with different uses and objectives, simple and reproducible tools like Brief Fatigue Inventory, Edmonton Symptom assessment scale seem feasible in everyday practice. Management of fatigue is not straightforward and rewarding. Although treatment of cause appears to be an attractive option, it is not possible in all cases. Therapeutic agents targeting cytokine load is in early stages of study and available results are not favorable. Specific measures aimed at pain relief, prevention/treatment of sepsis, management of depression, avoidance of drugs causing fatigue, restoring the metabolic profile are important. Methyl phenidate, megestrol, and modafinil are some drugs with promising effect to treat fatigue, though confirmatory studies are yet to be established. Non-pharmacological methods are also helpful. Forewarning patients on upcoming fatigue, active regular exercise, and stress management are some of them. Fatigue being a multidimensional entity, single mode of therapy is insufficient. Combined modality tailored to individual

  16. Neurodynamics, tonality, and the auditory brainstem response.

    Science.gov (United States)

    Large, Edward W; Almonte, Felix V

    2012-04-01

    Tonal relationships are foundational in music, providing the basis upon which musical structures, such as melodies, are constructed and perceived. A recent dynamic theory of musical tonality predicts that networks of auditory neurons resonate nonlinearly to musical stimuli. Nonlinear resonance leads to stability and attraction relationships among neural frequencies, and these neural dynamics give rise to the perception of relationships among tones that we collectively refer to as tonal cognition. Because this model describes the dynamics of neural populations, it makes specific predictions about human auditory neurophysiology. Here, we show how predictions about the auditory brainstem response (ABR) are derived from the model. To illustrate, we derive a prediction about population responses to musical intervals that has been observed in the human brainstem. Our modeled ABR shows qualitative agreement with important features of the human ABR. This provides a source of evidence that fundamental principles of auditory neurodynamics might underlie the perception of tonal relationships, and forces reevaluation of the role of learning and enculturation in tonal cognition.

  17. Reading adn Auditory-Visual Equivalences

    Science.gov (United States)

    Sidman, Murray

    1971-01-01

    A retarded boy, unable to read orally or with comprehension, was taught to match spoken to printed words and was then capable of reading comprehension (matching printed words to picture) and oral reading (naming printed words aloud), demonstrating that certain learned auditory-visual equivalences are sufficient prerequisites for reading…

  18. Tuning up the developing auditory CNS.

    Science.gov (United States)

    Sanes, Dan H; Bao, Shaowen

    2009-04-01

    Although the auditory system has limited information processing resources, the acoustic environment is infinitely variable. To properly encode the natural environment, the developing central auditory system becomes somewhat specialized through experience-dependent adaptive mechanisms that operate during a sensitive time window. Recent studies have demonstrated that cellular and synaptic plasticity occurs throughout the central auditory pathway. Acoustic-rearing experiments can lead to an over-representation of the exposed sound frequency, and this is associated with specific changes in frequency discrimination. These forms of cellular plasticity are manifest in brain regions, such as midbrain and cortex, which interact through feed-forward and feedback pathways. Hearing loss leads to a profound re-weighting of excitatory and inhibitory synaptic gain throughout the auditory CNS, and this is associated with an over-excitability that is observed in vivo. Further behavioral and computational analyses may provide insights into how theses cellular and systems plasticity effects underlie the development of cognitive functions such as speech perception.

  19. Auditory Integration Training: The Magical Mystery Cure.

    Science.gov (United States)

    Tharpe, Anne Marie

    1999-01-01

    This article notes the enthusiastic reception received by auditory integration training (AIT) for children with a wide variety of disorders including autism but raises concerns about this alternative treatment practice. It offers reasons for cautious evaluation of AIT prior to clinical implementation and summarizes current research findings. (DB)

  20. Integration and segregation in auditory scene analysis

    Science.gov (United States)

    Sussman, Elyse S.

    2005-03-01

    Assessment of the neural correlates of auditory scene analysis, using an index of sound change detection that does not require the listener to attend to the sounds [a component of event-related brain potentials called the mismatch negativity (MMN)], has previously demonstrated that segregation processes can occur without attention focused on the sounds and that within-stream contextual factors influence how sound elements are integrated and represented in auditory memory. The current study investigated the relationship between the segregation and integration processes when they were called upon to function together. The pattern of MMN results showed that the integration of sound elements within a sound stream occurred after the segregation of sounds into independent streams and, further, that the individual streams were subject to contextual effects. These results are consistent with a view of auditory processing that suggests that the auditory scene is rapidly organized into distinct streams and the integration of sequential elements to perceptual units takes place on the already formed streams. This would allow for the flexibility required to identify changing within-stream sound patterns, needed to appreciate music or comprehend speech..

  1. Development of Receiver Stimulator for Auditory Prosthesis

    Directory of Open Access Journals (Sweden)

    K. Raja Kumar

    2010-05-01

    Full Text Available The Auditory Prosthesis (AP is an electronic device that can provide hearing sensations to people who are profoundly deaf by stimulating the auditory nerve via an array of electrodes with an electric current allowing them to understand the speech. The AP system consists of two hardware functional units such as Body Worn Speech Processor (BWSP and Receiver Stimulator. The prototype model of Receiver Stimulator for Auditory Prosthesis (RSAP consists of Speech Data Decoder, DAC, ADC, constant current generator, electrode selection logic, switch matrix and simulated electrode resistance array. The laboratory model of speech processor is designed to implement the Continuous Interleaved Sampling (CIS speech processing algorithm which generates the information required for electrode stimulation based on the speech / audio data. Speech Data Decoder receives the encoded speech data via an inductive RF transcutaneous link from speech processor. Twelve channels of auditory Prosthesis with selectable eight electrodes for stimulation of simulated electrode resistance array are used for testing. The RSAP is validated by using the test data generated by the laboratory prototype of speech processor. The experimental results are obtained from specific speech/sound tests using a high-speed data acquisition system and found satisfactory.

  2. Auditory Processing Disorder: School Psychologist Beware?

    Science.gov (United States)

    Lovett, Benjamin J.

    2011-01-01

    An increasing number of students are being diagnosed with auditory processing disorder (APD), but the school psychology literature has largely neglected this controversial condition. This article reviews research on APD, revealing substantial concerns with assessment tools and diagnostic practices, as well as insufficient research regarding many…

  3. The Goldilocks Effect in Infant Auditory Attention

    Science.gov (United States)

    Kidd, Celeste; Piantadosi, Steven T.; Aslin, Richard N.

    2014-01-01

    Infants must learn about many cognitive domains (e.g., language, music) from auditory statistics, yet capacity limits on their cognitive resources restrict the quantity that they can encode. Previous research has established that infants can attend to only a subset of available acoustic input. Yet few previous studies have directly examined infant…

  4. Auditory Training with Frequent Communication Partners

    Science.gov (United States)

    Tye-Murray, Nancy; Spehar, Brent; Sommers, Mitchell; Barcroft, Joe

    2016-01-01

    Purpose: Individuals with hearing loss engage in auditory training to improve their speech recognition. They typically practice listening to utterances spoken by unfamiliar talkers but never to utterances spoken by their most frequent communication partner (FCP)--speech they most likely desire to recognize--under the assumption that familiarity…

  5. Auditory and visual scene analysis: an overview

    Science.gov (United States)

    2017-01-01

    We perceive the world as stable and composed of discrete objects even though auditory and visual inputs are often ambiguous owing to spatial and temporal occluders and changes in the conditions of observation. This raises important questions regarding where and how ‘scene analysis’ is performed in the brain. Recent advances from both auditory and visual research suggest that the brain does not simply process the incoming scene properties. Rather, top-down processes such as attention, expectations and prior knowledge facilitate scene perception. Thus, scene analysis is linked not only with the extraction of stimulus features and formation and selection of perceptual objects, but also with selective attention, perceptual binding and awareness. This special issue covers novel advances in scene-analysis research obtained using a combination of psychophysics, computational modelling, neuroimaging and neurophysiology, and presents new empirical and theoretical approaches. For integrative understanding of scene analysis beyond and across sensory modalities, we provide a collection of 15 articles that enable comparison and integration of recent findings in auditory and visual scene analysis. This article is part of the themed issue ‘Auditory and visual scene analysis’. PMID:28044011

  6. Affective Priming with Auditory Speech Stimuli

    Science.gov (United States)

    Degner, Juliane

    2011-01-01

    Four experiments explored the applicability of auditory stimulus presentation in affective priming tasks. In Experiment 1, it was found that standard affective priming effects occur when prime and target words are presented simultaneously via headphones similar to a dichotic listening procedure. In Experiment 2, stimulus onset asynchrony (SOA) was…

  7. Affective priming with auditory speech stimuli

    NARCIS (Netherlands)

    Degner, J.

    2011-01-01

    Four experiments explored the applicability of auditory stimulus presentation in affective priming tasks. In Experiment 1, it was found that standard affective priming effects occur when prime and target words are presented simultaneously via headphones similar to a dichotic listening procedure. In

  8. Auditory pathology in cri-du-chat (5p-) syndrome: phenotypic evidence for auditory neuropathy.

    Science.gov (United States)

    Swanepoel, D

    2007-10-01

    5p-(cri-du-chat syndrome) is a well-defined clinical entity presenting with phenotypic and cytogenetic variability. Despite recognition that abnormalities in audition are common, limited reports on auditory functioning in affected individuals are available. The current study presents a case illustrating the auditory functioning in a 22-month-old patient diagnosed with 5p- syndrome, karyotype 46,XX,del(5)(p13). Auditory neuropathy was diagnosed based on abnormal auditory evoked potentials with neural components suggesting severe to profound hearing loss in the presence of cochlear microphonic responses and behavioral reactions to sound at mild to moderate hearing levels. The current case and a review of available reports indicate that auditory neuropathy or neural dys-synchrony may be another phenotype of the condition possibly related to abnormal expression of the protein beta-catenin mapped to 5p. Implications are for routine and diagnostic specific assessments of auditory functioning and for employment of non-verbal communication methods in early intervention.

  9. Interhemispheric auditory connectivity: structure and function related to auditory verbal hallucinations.

    Science.gov (United States)

    Steinmann, Saskia; Leicht, Gregor; Mulert, Christoph

    2014-01-01

    Auditory verbal hallucinations (AVH) are one of the most common and most distressing symptoms of schizophrenia. Despite fundamental research, the underlying neurocognitive and neurobiological mechanisms are still a matter of debate. Previous studies suggested that "hearing voices" is associated with a number of factors including local deficits in the left auditory cortex and a disturbed connectivity of frontal and temporoparietal language-related areas. In addition, it is hypothesized that the interhemispheric pathways connecting right and left auditory cortices might be involved in the pathogenesis of AVH. Findings based on Diffusion-Tensor-Imaging (DTI) measurements revealed a remarkable interindividual variability in size and shape of the interhemispheric auditory pathways. Interestingly, schizophrenia patients suffering from AVH exhibited increased fractional anisotropy (FA) in the interhemispheric fibers than non-hallucinating patients. Thus, higher FA-values indicate an increased severity of AVH. Moreover, a dichotic listening (DL) task showed that the interindividual variability in the interhemispheric auditory pathways was reflected in the behavioral outcome: stronger pathways supported a better information transfer and consequently improved speech perception. This detection indicates a specific structure-function relationship, which seems to be interindividually variable. This review focuses on recent findings concerning the structure-function relationship of the interhemispheric pathways in controls, hallucinating and non-hallucinating schizophrenia patients and concludes that changes in the structural and functional connectivity of auditory areas are involved in the pathophysiology of AVH.

  10. Biological impact of auditory expertise across the life span: musicians as a model of auditory learning.

    Science.gov (United States)

    Strait, Dana L; Kraus, Nina

    2014-02-01

    Experience-dependent characteristics of auditory function, especially with regard to speech-evoked auditory neurophysiology, have garnered increasing attention in recent years. This interest stems from both pragmatic and theoretical concerns as it bears implications for the prevention and remediation of language-based learning impairment in addition to providing insight into mechanisms engendering experience-dependent changes in human sensory function. Musicians provide an attractive model for studying the experience-dependency of auditory processing in humans due to their distinctive neural enhancements compared to nonmusicians. We have only recently begun to address whether these enhancements are observable early in life, during the initial years of music training when the auditory system is under rapid development, as well as later in life, after the onset of the aging process. Here we review neural enhancements in musically trained individuals across the life span in the context of cellular mechanisms that underlie learning, identified in animal models. Musicians' subcortical physiologic enhancements are interpreted according to a cognitive framework for auditory learning, providing a model in which to study mechanisms of experience-dependent changes in human auditory function.

  11. Mental fatigue: costs and benefits.

    Science.gov (United States)

    Boksem, Maarten A S; Tops, Mattie

    2008-11-01

    A framework for mental fatigue is proposed, that involves an integrated evaluation of both expected rewards and energetical costs associated with continued performance. Adequate evaluation of predicted rewards and potential risks of actions is essential for successful adaptive behaviour. However, while both rewards and punishments can motivate to engage in activities, both types of motivated behaviour are associated with energetical costs. We will review findings that suggest that the nucleus accumbens, orbitofrontal cortex, amygdala, insula and anterior cingulate cortex are involved evaluating both the potential rewards associated with performing a task, as well as assessing the energetical demands involved in task performance. Behaviour will only proceed if this evaluation turns out favourably towards spending (additional) energy. We propose that this evaluation of predicted rewards and energetical costs is central to the phenomenon of mental fatigue: people will no longer be motivated to engage in task performance when energetical costs are perceived to outweigh predicted rewards.

  12. Creep-Fatigue Failure Diagnosis

    Directory of Open Access Journals (Sweden)

    Stuart Holdsworth

    2015-11-01

    Full Text Available Failure diagnosis invariably involves consideration of both associated material condition and the results of a mechanical analysis of prior operating history. This Review focuses on these aspects with particular reference to creep-fatigue failure diagnosis. Creep-fatigue cracking can be due to a spectrum of loading conditions ranging from pure cyclic to mainly steady loading with infrequent off-load transients. These require a range of mechanical analysis approaches, a number of which are reviewed. The microstructural information revealing material condition can vary with alloy class. In practice, the detail of the consequent cracking mechanism(s can be camouflaged by oxidation at high temperatures, although the presence of oxide on fracture surfaces can be used to date events leading to failure. Routine laboratory specimen post-test examination is strongly recommended to characterise the detail of deformation and damage accumulation under known and well-controlled loading conditions to improve the effectiveness and efficiency of failure diagnosis.

  13. Representation of Reward Feedback in Primate Auditory Cortex

    Directory of Open Access Journals (Sweden)

    Michael eBrosch

    2011-02-01

    Full Text Available It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1 the reward expectancy for each trial, (2 the reward size received and (3 the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

  14. Representation of reward feedback in primate auditory cortex.

    Science.gov (United States)

    Brosch, Michael; Selezneva, Elena; Scheich, Henning

    2011-01-01

    It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

  15. Aircrew fatigue and circadian rhythmicity

    Science.gov (United States)

    Graeber, R. Curtis

    1988-01-01

    Recent statistical and experimental studies on the role of circadian rhythms in aircrew fatigue and aviation accidents are reviewed from a human-factors perspective, and typical data are presented in extensive graphs. Consideration is given to the biological clock and the limits of endurance, circadian desynchronization, sleep and sleepiness, short-haul and long-haul operational studies, and the potential advantages of cockpit automation.

  16. Gear Fatigue Diagnostics and Prognostics

    Science.gov (United States)

    2013-01-01

    The first objective was to collect meaningful gear fault progression data starting from healthy NASA-designed spur test gears and ending with failed...and D. P. Townsend, "Analysis of the effects of surface pitting and wear on the vibration of a gear transmission system," Tribology International...Reporting Period: April 15, 2012 to September 27, 2012 Attached is the Gear Fatigue Diagnostics and Prognostics project progress report for the

  17. Biaxial Fatigue Cracking from Notch

    Science.gov (United States)

    2013-03-04

    Leevers (reference 11) noticed that the variation in  from 0 to 2 has little effect on the da/dN in PVC ( polyvinyl - chloride ), but reduces the da/dN...under biaxial rotating and bending. Ahmad (reference 2) formulated a model for the biaxial fatigue crack growth in aggressive environment, outlined by...1962, Vol. 90, pp. 238-239. 20. ASM Handbook , Vol. 12 Fractography: 1992, p. 430, 438. 21. Metals Handbook , Vol. 9 Fractography and Atlas of

  18. Fatigue Management in Spaceflight Operations

    Science.gov (United States)

    Whitmire, Alexandra

    2011-01-01

    Sleep loss and fatigue remain an issue for crewmembers working on the International Space Station, and the ground crews who support them. Schedule shifts on the ISS are required for conducting mission operations. These shifts lead to tasks being performed during the biological night, and sleep scheduled during the biological day, for flight crews and the ground teams who support them. Other stressors have been recognized as hindering sleep in space; these include workload, thinking about upcoming tasks, environmental factors, and inadequate day/night cues. It is unknown if and how other factors such as microgravity, carbon dioxide levels, or increased radiation, may also play a part. Efforts are underway to standardize and provide care for crewmembers, ground controllers and other support personnel. Through collaborations between research and operations, evidenced-based clinical practice guidelines are being developed to equip flight surgeons with the tools and processes needed for treating circadian desynchrony (and subsequent sleep loss) caused by jet lag and shift work. The proper implementation of countermeasures such as schedules, lighting protocols, and cognitive behavioral education can hasten phase shifting, enhance sleep and optimize performance. This panel will focus on Fatigue Management in Spaceflight Operations. Speakers will present on research-based recommendations and technologies aimed at mitigating sleep loss, circadian desynchronization and fatigue on-orbit. Gaps in current mitigations and future recommendations will also be discussed.

  19. Mental fatigue impairs emotion regulation.

    Science.gov (United States)

    Grillon, Christian; Quispe-Escudero, David; Mathur, Ambika; Ernst, Monique

    2015-06-01

    Because healthy physical and mental functioning depends on the ability to regulate emotions, it is important to identify moderators of such regulations. Whether mental fatigue, subsequent to the depletion of cognitive resources, impairs explicit emotion regulation to negative stimuli is currently unknown. This study explored this possibility. In a within-subject design over 2 separate sessions, healthy individuals performed easy (control session) or difficult (depletion session) cognitive tasks. Subsequently, they were presented with neutral and negative pictures, with instructions to either maintain or regulate (i.e., reduce) the emotions evoked by the pictures. Emotional reactivity was probed with the startle reflex. The negative pictures evoked a similar aversive state in the control and depletion sessions as measured by startle potentiation. However, subjects were able to down-regulate their aversive state only in the control session, not in the depletion session. These results indicate that mental fatigue following performance of cognitive tasks impairs emotion regulation without affecting emotional reactivity. These findings suggest that mental fatigue needs to be incorporated into models of emotion regulation.

  20. Measuring Auditory Selective Attention using Frequency Tagging

    Directory of Open Access Journals (Sweden)

    Hari M Bharadwaj

    2014-02-01

    Full Text Available Frequency tagging of sensory inputs (presenting stimuli that fluctuate periodically at rates to which the cortex can phase lock has been used to study attentional modulation of neural responses to inputs in different sensory modalities. For visual inputs, the visual steady-state response (VSSR at the frequency modulating an attended object is enhanced, while the VSSR to a distracting object is suppressed. In contrast, the effect of attention on the auditory steady-state response (ASSR is inconsistent across studies. However, most auditory studies analyzed results at the sensor level or used only a small number of equivalent current dipoles to fit cortical responses. In addition, most studies of auditory spatial attention used dichotic stimuli (independent signals at the ears rather than more natural, binaural stimuli. Here, we asked whether these methodological choices help explain discrepant results. Listeners attended to one of two competing speech streams, one simulated from the left and one from the right, that were modulated at different frequencies. Using distributed source modeling of magnetoencephalography results, we estimate how spatially directed attention modulates the ASSR in neural regions across the whole brain. Attention enhances the ASSR power at the frequency of the attended stream in the contralateral auditory cortex. The attended-stream modulation frequency also drives phase-locked responses in the left (but not right precentral sulcus (lPCS, a region implicated in control of eye gaze and visual spatial attention. Importantly, this region shows no phase locking to the distracting stream suggesting that the lPCS in engaged in an attention-specific manner. Modeling results that take account of the geometry and phases of the cortical sources phase locked to the two streams (including hemispheric asymmetry of lPCS activity help partly explain why past ASSR studies of auditory spatial attention yield seemingly contradictory

  1. Comparison of Electrophysiological Auditory Measures in Fishes.

    Science.gov (United States)

    Maruska, Karen P; Sisneros, Joseph A

    2016-01-01

    Sounds provide fishes with important information used to mediate behaviors such as predator avoidance, prey detection, and social communication. How we measure auditory capabilities in fishes, therefore, has crucial implications for interpreting how individual species use acoustic information in their natural habitat. Recent analyses have highlighted differences between behavioral and electrophysiologically determined hearing thresholds, but less is known about how physiological measures at different auditory processing levels compare within a single species. Here we provide one of the first comparisons of auditory threshold curves determined by different recording methods in a single fish species, the soniferous Hawaiian sergeant fish Abudefduf abdominalis, and review past studies on representative fish species with tuning curves determined by different methods. The Hawaiian sergeant is a colonial benthic-spawning damselfish (Pomacentridae) that produces low-frequency, low-intensity sounds associated with reproductive and agonistic behaviors. We compared saccular potentials, auditory evoked potentials (AEP), and single neuron recordings from acoustic nuclei of the hindbrain and midbrain torus semicircularis. We found that hearing thresholds were lowest at low frequencies (~75-300 Hz) for all methods, which matches the spectral components of sounds produced by this species. However, thresholds at best frequency determined via single cell recordings were ~15-25 dB lower than those measured by AEP and saccular potential techniques. While none of these physiological techniques gives us a true measure of the auditory "perceptual" abilities of a naturally behaving fish, this study highlights that different methodologies can reveal similar detectable range of frequencies for a given species, but absolute hearing sensitivity may vary considerably.

  2. Mechanisms underlying fatigue: a voxel-based morphometric study of chronic fatigue syndrome

    Directory of Open Access Journals (Sweden)

    Watanabe Yasuyoshi

    2004-10-01

    Full Text Available Abstract Background Fatigue is a crucial sensation that triggers rest, yet its underlying neuronal mechanisms remain unclear. Intense long-term fatigue is a symptom of chronic fatigue syndrome, which is used as a model to study the mechanisms underlying fatigue. Methods Using magnetic resonance imaging, we conducted voxel-based morphometry of 16 patients and 49 age-matched healthy control subjects. Results We found that patients with chronic fatigue syndrome had reduced gray-matter volume in the bilateral prefrontal cortex. Within these areas, the volume reduction in the right prefrontal cortex paralleled the severity of the fatigue of the subjects. Conclusion These results are consistent with previous reports of an abnormal distribution of acetyl-L-carnitine uptake, which is one of the biochemical markers of chronic fatigue syndrome, in the prefrontal cortex. Thus, the prefrontal cortex might be an important element of the neural system that regulates sensations of fatigue.

  3. Low cycle fatigue of irradiated LMFBR materials

    Energy Technology Data Exchange (ETDEWEB)

    Blackburn, L D

    1976-01-01

    A review of low cycle fatigue data on irradiated LMFBR materials was conducted and extensive graphical representations of available data are presented. Representative postirradiation tensile properties of annealed 304 and 316 SS are selected and employed in several predictive methods to estimate irradiated material fatigue curves. Experimental fatigue data confirm the use of predictive methods for establishing conservative design curves over the range of service conditions relevant to such CRBRP components as core former, fixed radial shielding, core barrel, lower inlet module and upper internals structures. New experimental data on fatigue curves and creep-fatigue interaction in irradiated 20 percent cold worked (CW) 316 SS and Alloy 718 would support the design of removable radial shielding and upper internals in CRBRP. New experimental information on notched fatigue behavior and cyclic stress-strain curves of all these materials in the irradiated condition could provide significant design data.

  4. Fatigue In Tension Perpendicular to the Grain

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Uhre; Hoffmeyer, Preben;

    2004-01-01

    mechanism and a mechanism connected to damage introduced in the loading sequences. The purpose of the present study is to disentangle the effect of duration of load from the effect of load oscillation in fatigue in tension perpendicular to the grain. Fatigue experiments are made on small specimens...... and on dowel type joints with slotted in steel plates. In series of ten, the small specimens are taken to fatigue failure in uniform tension at square wave shaped load cycles at 0.01 Hz and 0.1 Hz. In arder to test the predictive validity of the result from the small tension specimens, fatigue experiments......Traditionally fatigue resistance is quantified as number of cycles to failure at a given stress level. A previous study by the authors showed that fatigue in compression parallel to the grain is governed partly by duration of load and partly by an effect of loading, i.e. a combination of a creep...

  5. Fatigue in tension perpendicular to the grain

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben;

    1999-01-01

    mechanism and a mechanism connected to damage introduce in the loading sequences. The purpose of the present study is to disentangle the effect of duration of load from the effect of load oscillation in fatigue in tension perpendicular to the grain. Fatigue experiments are made on small specimens...... and on dowel type joints with slotted in steel plates. In series of ten, the small specimens are taken to fatigue failure in uniform tension at square wave shaped load cycles at 0.01 Hz and 0.1 Hz. In order to test the predictive validity of the result from the small tension specimens, fatigue experiments......Traditinally fatigue resistance is quantified as number of cycles to failure at a given stress level. A previous study by the authors showed that fatigue in compression parallel to the grain is governed partly by duration of load and partly by an effect of loading, i.e. a combination of a creep...

  6. EVAPRED - A CODE FOR FATIGUE ANALYSIS OPTIMIZATION

    Directory of Open Access Journals (Sweden)

    Dorin LOZICI-BRÎNZEI

    2010-03-01

    Full Text Available The fatigue can be, in fact, defined as: “failure under a repeated or otherwise varying load, which never reaches a level sufficient to cause failure in a single application”.Physical testing is clearly unrealistic for every design component. In most applications, fatigue-safe life design requires the prediction of the component fatigue life that accounts for predicted service loads and materials. The primary tool for both understanding and being able to predict and avoid fatigue has proven to be the finite element analysis (FEA. Computer-aided engineering (CAE programs use three major methods to determine the total fatigue life: Stress life (SN, Strain life (EN and Fracture Mechanics (FM. FEA can predict stress concentration areas and can help design engineers to predict how long their designs are likely to last before experiencing the onset of fatigue.

  7. Countering compassion fatigue: a requisite nursing agenda.

    Science.gov (United States)

    Boyle, Deborah A

    2011-01-31

    Nurses have a longstanding history of witnessing the tragedy experienced by patients and families; however, their own reactions to profound loss and premature death have not been systematically addressed. There is a paucity of research describing interventions to prevent or minimize the ramifications of repeated exposure to traumatic events in the clinical workplace. Compassion fatigue is a contemporary label affixed to the concept of personal vicarious exposure to trauma on a regular basis. Yet this phenomenon of compassion fatigue lacks clarity. In this article, the author begins by describing compassion fatigue and distinguishing compassion fatigue from burnout. Next she discusses risk factors for, and the assessment of compassion fatigue. The need to support nurses who witness tragedy and workplace interventions to confront compassion fatigue are described.

  8. Impairments of auditory scene analysis in Alzheimer's disease.

    Science.gov (United States)

    Goll, Johanna C; Kim, Lois G; Ridgway, Gerard R; Hailstone, Julia C; Lehmann, Manja; Buckley, Aisling H; Crutch, Sebastian J; Warren, Jason D

    2012-01-01

    Parsing of sound sources in the auditory environment or 'auditory scene analysis' is a computationally demanding cognitive operation that is likely to be vulnerable to the neurodegenerative process in Alzheimer's disease. However, little information is available concerning auditory scene analysis in Alzheimer's disease. Here we undertook a detailed neuropsychological and neuroanatomical characterization of auditory scene analysis in a cohort of 21 patients with clinically typical Alzheimer's disease versus age-matched healthy control subjects. We designed a novel auditory dual stream paradigm based on synthetic sound sequences to assess two key generic operations in auditory scene analysis (object segregation and grouping) in relation to simpler auditory perceptual, task and general neuropsychological factors. In order to assess neuroanatomical associations of performance on auditory scene analysis tasks, structural brain magnetic resonance imaging data from the patient cohort were analysed using voxel-based morphometry. Compared with healthy controls, patients with Alzheimer's disease had impairments of auditory scene analysis, and segregation and grouping operations were comparably affected. Auditory scene analysis impairments in Alzheimer's disease were not wholly attributable to simple auditory perceptual or task factors; however, the between-group difference relative to healthy controls was attenuated after accounting for non-verbal (visuospatial) working memory capacity. These findings demonstrate that clinically typical Alzheimer's disease is associated with a generic deficit of auditory scene analysis. Neuroanatomical associations of auditory scene analysis performance were identified in posterior cortical areas including the posterior superior temporal lobes and posterior cingulate. This work suggests a basis for understanding a class of clinical symptoms in Alzheimer's disease and for delineating cognitive mechanisms that mediate auditory scene analysis

  9. Fatigue damage mechanisms in polymer matrix composites

    OpenAIRE

    1997-01-01

    Polymer matrix composites are finding increased use in structural applications, in particular for aerospace and automotive purposes. Mechanical fatigue is the most common type of failure of structures in service. The relative importance of fatigue has yet to be reflected in design where static conditions still prevail. The fatigue behavior of composite materials is conventionally characterized by a Wöhler or S-N curve. For every new material with a new lay-up, altered constituents or differen...

  10. Sleep complaints and fatigue of airline pilots

    OpenAIRE

    Reis, Cátia; Mestre, Catarina; Canhão, Helena; Gradwell, David; Paiva, Teresa

    2016-01-01

    This work aimed to determine daytime sleepiness and sleep complaints prevalence and the corresponding influence on perceived fatigue and to evaluate the influence of sociodemographic parameters and labour variables on sleep complaints, sleepiness and fatigue. A questionnaire was developed including socio-economic and labour issues and instruments, focused in sleep and fatigue. The response rate was 32% and the final sample had 435 pilots. The prevalence of sleep complaints was 34.9%, daytime ...

  11. The concept of fatigue fracture toughness in fatigue delamination growth behavior

    NARCIS (Netherlands)

    Yao, L.; Alderliesten, R.C.; Benedictus, R.

    2015-01-01

    This paper provides a study on mode I fatigue delamination growth in composite laminates using energy principles. Experimental data has been obtained from fatigue tests conducted on Double Cantilever Beam (DCB) specimens at various stress ratios. A concept of fatigue fracture toughness is proposed t

  12. Low-Cycle Fatigue Life and Fatigue Crack Propagation of Sintered Ag Nanoparticles

    Science.gov (United States)

    Shioda, Ryutaro; Kariya, Yoshiharu; Mizumura, Noritsuka; Sasaki, Koji

    2017-02-01

    The low-cycle fatigue life and fatigue crack propagation behavior of sintered silver nanoparticles were investigated using miniature specimens sintered at two different temperatures. The fatigue crack initiation life and fatigue crack propagation rate of sintered Ag nanoparticles were extremely sensitive to changes in the range of inelastic energy density and the cyclic J integral, exhibiting brittle characteristics, in contrast to tin-based lead-free solder alloys. With increasing sintering temperature, the fatigue crack propagation rate decreased. On the other hand, the effect of sintering temperature on the fatigue crack initiation life differed depending on the use of either a smooth specimen (low-cycle fatigue test) or notched specimen (fatigue crack propagation test). For the notched specimens, the probability of grain boundaries around the notch decreased due to increased sintering temperature. Therefore, the fatigue crack initiation life was increased with an increase in sintering temperature in the fatigue crack propagation test. In the smooth specimen, however, the fatigue life decreased with an increase in sintering temperature, as the elastic modulus of the specimen increased with increasing sintering temperature. In the low-cycle fatigue test, the specimen sintered with high internal stress started to develop crack initiation early, causing a decrease in the crack initiation life.

  13. Fatigue and fatigue-related symptoms in patients treated for different causes of hypothyroidism

    NARCIS (Netherlands)

    Louwerens, M.; Appelhof, B.C.; Verloop, H.; Medici, M.; Peeters, R.P.; Visser, T.J.; Boelen, A.; Fliers, E.; Smit, J.W.A.; Dekkers, O.M.

    2012-01-01

    OBJECTIVE: Research on determinants of well-being in patients on thyroid hormone replacement therapy is warranted, as persistent fatigue-related complaints are common in this population. In this study, we evaluated the impact of different states of hypothyroidism on fatigue and fatigue-related sympt

  14. [Research Progress on the Interaction Effects and Its Neural Mechanisms between Physical Fatigue and Mental Fatigue].

    Science.gov (United States)

    Zhang, Lixin; Zhang, Chuncui; He, Feng; Zhao, Xin; Qi, Hongzhi; Wan, Baikun; Ming, Dong

    2015-10-01

    Fatigue is an exhaustion state caused by prolonged physical work and mental work, which can reduce working efficiency and even cause industrial accidents. Fatigue is a complex concept involving both physiological and psychological factors. Fatigue can cause a decline of concentration and work performance and induce chronic diseases. Prolonged fatigue may endanger life safety. In most of the scenarios, physical and mental workloads co-lead operator into fatigue state. Thus, it is very important to study the interaction influence and its neural mechanisms between physical and mental fatigues. This paper introduces recent progresses on the interaction effects and discusses some research challenges and future development directions. It is believed that mutual influence between physical fatigue and mental fatigue may occur in the central nervous system. Revealing the basal ganglia function and dopamine release may be important to explore the neural mechanisms between physical fatigue and mental fatigue. Future effort is to optimize fatigue models, to evaluate parameters and to explore the neural mechanisms so as to provide scientific basis and theoretical guidance for complex task designs and fatigue monitoring.

  15. Fatigue Reliability under Multiple-Amplitude Loads

    DEFF Research Database (Denmark)

    Talreja, R.

    1979-01-01

    A method to determine the fatigue of structures subjected to multiple-amplitude loads is presented. Unlike the more common cumulative damage methods, which are usually based on fatigue life data, the proposed method is based on tensile strength data. Assuming the Weibull distribution...... for the initial tensile strength and the fatigue life, the probability distributions for the residual tensile strength in both the crack initiation and the crack propagation stages of fatigue are determined. The method is illustrated for two-amplitude loads by means of experimental results obtained by testing...

  16. Research progress of exercise-induced fatigue

    Directory of Open Access Journals (Sweden)

    Peng-yi DAI

    2016-12-01

    Full Text Available Exercise-induced fatigue is a comprehensive response to a variety of physiological and biochemical changes in the body, and can affect people's quality of life to different extents. If no timely recovery after occurrence of fatigue, accumulated gradually, it can lead to "burnout", a "overtraining syndrome", "chronic fatigue syndrome", etc., which will cause endocrine disturbance, immune suppression, even physical illness. Exercise-induced fatigue becomes an important factor endangering human health. In recent years, many experts and scholars at home and abroad are committed to the research of exercise-induced fatigue, and have put forward a variety of hypothesis to explain the cause of exercise-induced fatigue. They expect to find out the methods for preventing and eliminating exercise-induced fatigue. This article discusses mainly the pathogenesis, model building, elimination/ relief, etc. of exercise-induced fatigue to point out the research achievements of exercise-induced fatigue and its existing problems. DOI: 10.11855/j.issn.0577-7402.2016.11.14

  17. Fatigue in Breakwater Concrete Armour Units

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    1985-01-01

    made of unreinforced and steel fibre reinforced flyash concrete are presented. Moreover universal graphs for fatigue in armour units made of conventional unreinforced concrete exposed to impact load and pulsating load are presented. The effect of fibre reinforcement and the implementation of fatigue......The reliability of rubble mound breakwaters depends on the hydraulic stability and the mechanical strength of the armour units. The paper deals with the important aspect of fatigue related to the strength of concrete armour units. Results showing significant fatigue from impact tests with Dolosse...

  18. Fatigue Performance of Bridge Deck Pavement Materials

    Institute of Scientific and Technical Information of China (English)

    WU Shaopeng; ZHANG Guang; HAN Jun; LIU Gang; ZHOU Jie

    2009-01-01

    Three beam samplesof bridge deck pavementwere prepared, with gradationtypes of AC-13, and AC-16 and combined AC-13+AC-16. Four-point bending test was adopted to investigate the fatigue performance of these beam samples. The experimental results indicate that the initial bending stiffness is related to the type of beam sample and testing temperature. Fatigue life of these samples decreases as the increase of the controlled strain level. The AC-13 beam sample exhibits better fatigue resistance and bigger limiting bending strain at the given strain level and temperature. Com-pared with single beam sample, the fatigue performance of combining beam sample is relatively poor.

  19. How do women with lupus manage fatigue?

    DEFF Research Database (Denmark)

    Kier, Anne Ørnholt; Midtgaard, Julie; Hougaard, Karin Sørig

    2016-01-01

    , and learning to accept fatigue) and six sub-themes (i.e., the search for recognition, legitimization, planning and prioritizing, the body’s limits and self-indulgence, adjusting life to comply with resources, and acceptance of dependence). Conclusion: Fatigue is the controlling element in everyday life...... of women with SLE. Patients try to integrate fatigue into their everyday lives by attempting to control it and meet the challenges of structure and planning. This study indicates a need for clinicians to acknowledge patients’ fatigue, including supporting patients’ own resources, offering information...

  20. Fatigue in Multiple Sclerosis: (An update

    Directory of Open Access Journals (Sweden)

    Hossein Zarei

    2007-10-01

    Full Text Available BACKGROUND:To study the dimensions of fatigue in multiple sclerosis, its pathophysiology, the efficacy, tolerability and safety of drug and non-drug treatments and measurement of fatigue. METHODS: Relevant articles from PubMed and Google scholar search engines from January 1987 until September 2006 were studied to compose a short clinical update (not a systematic review and make the required clinical information available for the clinicians. RESULTS: There is evidence that fatigue is very common in all types and stages of multiple sclerosis, but its pathophysiology is not well explained. Consequently, few drug options have been offered for its treatment. Amantadine is the bestknown drug, though its efficacy and duration of action are limited. Pemoline and modafinil are alternatives and have
    some effects on fatigue. DAP (diaminopyridine, ASA (acetylsalicylic acid, methylphenidate and fluoxetine are other possible options but await further confirmation. Neurorehabilitation, regular exercise and cooling are confirmed to be of value in MS treatment. Measurement of fatigue is a complicated issue. At present fatigue does not have a laboratory marker. CONCLUSIONS: The results of this short clinical update provide guidelines for diagnosing MS-related fatigue and differentiating
    it from other similar physical and psychological conditions. It also examines prescription drug options and other therapies for MS patients with fatigue.
    KEYWORDS: Multiple sclerosis, fatigue, pathophysiology, treatment, measurement.

  1. Fatigue tests on the ITER PF jacket

    Science.gov (United States)

    Qin, Jinggang; Weiss, Klaus-Peter; Wu, Yu; Wu, Zhixiong; Li, Laifeng; Liu, Sheng

    2012-10-01

    This paper focuses on fatigue tests on the ITER Poloidal Field (PF) jacket made of 316L stainless steel material. During manufacture, the conductor will be compacted and spooled after cable insertion. Therefore, sample jackets were prepared under compaction, bending and straightening in order to simulate the status of PF conductor during manufacturing and winding. The fatigue properties of materials were measured at T fatigue crack growth rate (FCGR). The testing results show that the present Chinese PF jacket has good fatigue properties, which conclude that the results are accordant with the requirements of ITER.

  2. Attention Modulates the Auditory Cortical Processing of Spatial and Category Cues in Naturalistic Auditory Scenes

    Science.gov (United States)

    Renvall, Hanna; Staeren, Noël; Barz, Claudia S.; Ley, Anke; Formisano, Elia

    2016-01-01

    This combined fMRI and MEG study investigated brain activations during listening and attending to natural auditory scenes. We first recorded, using in-ear microphones, vocal non-speech sounds, and environmental sounds that were mixed to construct auditory scenes containing two concurrent sound streams. During the brain measurements, subjects attended to one of the streams while spatial acoustic information of the scene was either preserved (stereophonic sounds) or removed (monophonic sounds). Compared to monophonic sounds, stereophonic sounds evoked larger blood-oxygenation-level-dependent (BOLD) fMRI responses in the bilateral posterior superior temporal areas, independent of which stimulus attribute the subject was attending to. This finding is consistent with the functional role of these regions in the (automatic) processing of auditory spatial cues. Additionally, significant differences in the cortical activation patterns depending on the target of attention were observed. Bilateral planum temporale and inferior frontal gyrus were preferentially activated when attending to stereophonic environmental sounds, whereas when subjects attended to stereophonic voice sounds, the BOLD responses were larger at the bilateral middle superior temporal gyrus and sulcus, previously reported to show voice sensitivity. In contrast, the time-resolved MEG responses were stronger for mono- than stereophonic sounds in the bilateral auditory cortices at ~360 ms after the stimulus onset when attending to the voice excerpts within the combined sounds. The observed effects suggest that during the segregation of auditory objects from the auditory background, spatial sound cues together with other relevant temporal and spectral cues are processed in an attention-dependent manner at the cortical locations generally involved in sound recognition. More synchronous neuronal activation during monophonic than stereophonic sound processing, as well as (local) neuronal inhibitory mechanisms in

  3. Uncertainty on Fatigue Damage Accumulation for Composite Materials

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2009-01-01

    In the present paper stochastic models for fatigue damage accumulation for composite materials are presented based on public available constant and variable amplitude fatigue tests. The methods used for estimating the SN-curve and accumulated fatigue damage are presented.......In the present paper stochastic models for fatigue damage accumulation for composite materials are presented based on public available constant and variable amplitude fatigue tests. The methods used for estimating the SN-curve and accumulated fatigue damage are presented....

  4. Fatigue in the Presence of Corrosion (Fatigue sous corrosion)

    Science.gov (United States)

    1999-03-01

    riennes et de la maintenance des a~ronefs. Cette rencontre a 6t6 A l’origine de discussions soutenues. L’ atelier avait pour objectifs: "* faciliter...of Corrosion/Fatigue Interaction in the Development of Multiple 20 Site Damage in Longitudinal Fuselage Skin Splices by G.F. Eastaugh, A.A. Merati, D.L... site damage in the considerations prevented him from attending. He had planned attachment to the fuselage. He noted that the cracking found to present

  5. Fatigue in osteoarthritis: a qualitative study

    Directory of Open Access Journals (Sweden)

    French Melissa R

    2008-05-01

    Full Text Available Abstract Background Fatigue is recognized as a disabling symptom in many chronic conditions including rheumatic disorders such as rheumatoid arthritis (RA and lupus. Fatigue in osteoarthritis (OA is not routinely evaluated and has only been considered in a very limited number of studies. To date, these studies have focused primarily on patients with OA under rheumatological care, which represent the minority of people living with OA. The purpose of this study was to increase our understanding of the fatigue experience in community dwelling people with OA. Methods In 2004, 8 focus groups were conducted with 28 men and 18 women (mean age 72.3 with symptomatic hip or knee OA recruited from a population-based cohort. Participants completed a self-administered questionnaire, which included demographics, measures of OA severity (WOMAC, depression (CES-D and fatigue (FACIT. Sessions were audio taped and transcribed verbatim. Two researchers independently reviewed the transcripts to identify themes. Findings were compared and consensus reached. Results Mean pain, disability, depression and fatigue scores were 8.7/20, 27.8/68, 15.4/60, and 30.9/52, respectively. Participants described their fatigue as exhaustion, being tired and "coming up against a brick wall". Participants generally perceived fatigue as different from sleepiness and distinguished physical from mental fatigue. Factors believed to increase fatigue included OA pain and pain medications, aging, various types of weather and poor sleep. Mental health was identified as both affecting fatigue and being affected by fatigue. Participants described fatigue as impacting physical function, and their ability to participate in social activities and to do household chores. Rest, exercise, and avoiding or getting assistance with activities were cited as ways of coping. Participants generally did not discuss their fatigue with anyone except their spouses. Conclusion Participants with OA described

  6. Exercise and fatigue in rheumatoid arthritis.

    Science.gov (United States)

    Balsamo, Sandor; Diniz, Leonardo R; dos Santos-Neto, Leopoldo L; da Mota, Licia M H

    2014-01-01

    Fatigue, the enduring sensation of weakness, lack of energy, tiredness or exhaustion, is described by 40%-80% of patients with rheumatoid arthritis as their most disabling symptom with wide-ranging consequences for quality of life. Little attention has been paid to its multidimensional nature or to its reliability as a measure to evaluate progression of the disease. Low impact aerobic exercise affects the level of fatigue, and this same level of fatigue influences the exercise itself. We searched Medline, Cochrane Collaboration Register of Controlled Trials (CCRCT), Lilacs, PubMed and Scopus databases for randomized controlled trials (with appropriate description of methods, materials and results) on the assessment of fatigue and exercise. Review articles, case reports, letters to the editor and editorials were excluded. Of 121 references initially identified, 4 randomized controlled trials met the inclusion criteria. Two studies used the MAF scale (Multidimensional Assessment of Fatigue), one used the MAC (Mental Adjustment to Cancer) fatigue scale, and all trials used POMS (Profile of Mood States) to assess fatigue. All four trials conducted a 12 week program of two to three times/ week and different periods of follow-up. Two studies used low impact aerobic exercise, one used dance-based exercise, and another study followed a home cardiopulmonary conditioning program using a stationary bicycle. While fatigue appears to be a reliable outcome measure in the clinical management of RA, especially when related to exercise prescription, further research is needed to evaluate the correlation between exercise, fatigue and quality of life, using fatigue scales validated to explore the different components of fatigue and its wide-ranging consequences.

  7. Fatigue Analysis of Large-scale Wind turbine

    Directory of Open Access Journals (Sweden)

    Zhu Yongli

    2017-01-01

    Full Text Available The paper does research on top flange fatigue damage of large-scale wind turbine generator. It establishes finite element model of top flange connection system with finite element analysis software MSC. Marc/Mentat, analyzes its fatigue strain, implements load simulation of flange fatigue working condition with Bladed software, acquires flange fatigue load spectrum with rain-flow counting method, finally, it realizes fatigue analysis of top flange with fatigue analysis software MSC. Fatigue and Palmgren-Miner linear cumulative damage theory. The analysis result indicates that its result provides new thinking for flange fatigue analysis of large-scale wind turbine generator, and possesses some practical engineering value.

  8. The effect of fatigue and fibromyalgia on sexual dysfunction in women with chronic fatigue syndrome.

    Science.gov (United States)

    Blazquez, Alicia; Ruiz, Eva; Aliste, Luisa; García-Quintana, Ana; Alegre, José

    2015-01-01

    Sexual dysfunction in patients with chronic fatigue syndrome is attracting growing interest but, to date, few studies have analyzed it. For this reason, the authors evaluated sexual dysfunction in women with chronic fatigue syndrome (using the Golombok Rust Inventory of Sexual Satisfaction) and explore correlations with fatigue and other symptoms. Sexual dysfunction was greater in patients with chronic fatigue syndrome (n = 615) with a higher number of cognitive, neurological, and neurovegetative symptoms, concomitant fibromyalgia, Sjögren's syndrome, or myofascial pain syndrome, and more intense fatigue (p <.05).

  9. Shaping the aging brain: Role of auditory input patterns in the emergence of auditory cortical impairments

    Directory of Open Access Journals (Sweden)

    Brishna Soraya Kamal

    2013-09-01

    Full Text Available Age-related impairments in the primary auditory cortex (A1 include poor tuning selectivity, neural desynchronization and degraded responses to low-probability sounds. These changes have been largely attributed to reduced inhibition in the aged brain, and are thought to contribute to substantial hearing impairment in both humans and animals. Since many of these changes can be partially reversed with auditory training, it has been speculated that they might not be purely degenerative, but might rather represent negative plastic adjustments to noisy or distorted auditory signals reaching the brain. To test this hypothesis, we examined the impact of exposing young adult rats to 8 weeks of low-grade broadband noise on several aspects of A1 function and structure. We then characterized the same A1 elements in aging rats for comparison. We found that the impact of noise exposure on A1 tuning selectivity, temporal processing of auditory signal and responses to oddball tones was almost indistinguishable from the effect of natural aging. Moreover, noise exposure resulted in a reduction in the population of parvalbumin inhibitory interneurons and cortical myelin as previously documented in the aged group. Most of these changes reversed after returning the rats to a quiet environment. These results support the hypothesis that age-related changes in A1 have a strong activity-dependent component and indicate that the presence or absence of clear auditory input patterns might be a key factor in sustaining adult A1 function.

  10. Selective memory retrieval of auditory what and auditory where involves the ventrolateral prefrontal cortex.

    Science.gov (United States)

    Kostopoulos, Penelope; Petrides, Michael

    2016-02-16

    There is evidence from the visual, verbal, and tactile memory domains that the midventrolateral prefrontal cortex plays a critical role in the top-down modulation of activity within posterior cortical areas for the selective retrieval of specific aspects of a memorized experience, a functional process often referred to as active controlled retrieval. In the present functional neuroimaging study, we explore the neural bases of active retrieval for auditory nonverbal information, about which almost nothing is known. Human participants were scanned with functional magnetic resonance imaging (fMRI) in a task in which they were presented with short melodies from different locations in a simulated virtual acoustic environment within the scanner and were then instructed to retrieve selectively either the particular melody presented or its location. There were significant activity increases specifically within the midventrolateral prefrontal region during the selective retrieval of nonverbal auditory information. During the selective retrieval of information from auditory memory, the right midventrolateral prefrontal region increased its interaction with the auditory temporal region and the inferior parietal lobule in the right hemisphere. These findings provide evidence that the midventrolateral prefrontal cortical region interacts with specific posterior cortical areas in the human cerebral cortex for the selective retrieval of object and location features of an auditory memory experience.

  11. An Auditory Model with Hearing Loss

    DEFF Research Database (Denmark)

    Nielsen, Lars Bramsløw

    An auditory model based on the psychophysics of hearing has been developed and tested. The model simulates the normal ear or an impaired ear with a given hearing loss. Based on reviews of the current literature, the frequency selectivity and loudness growth as functions of threshold and stimulus...... level have been found and implemented in the model. The auditory model was verified against selected results from the literature, and it was confirmed that the normal spread of masking and loudness growth could be simulated in the model. The effects of hearing loss on these parameters was also...... in qualitative agreement with recent findings. The temporal properties of the ear have currently not been included in the model. As an example of a real-world application of the model, loudness spectrograms for a speech utterance were presented. By introducing hearing loss, the speech sounds became less audible...

  12. Deafness in cochlear and auditory nerve disorders.

    Science.gov (United States)

    Hopkins, Kathryn

    2015-01-01

    Sensorineural hearing loss is the most common type of hearing impairment worldwide. It arises as a consequence of damage to the cochlea or auditory nerve, and several structures are often affected simultaneously. There are many causes, including genetic mutations affecting the structures of the inner ear, and environmental insults such as noise, ototoxic substances, and hypoxia. The prevalence increases dramatically with age. Clinical diagnosis is most commonly accomplished by measuring detection thresholds and comparing these to normative values to determine the degree of hearing loss. In addition to causing insensitivity to weak sounds, sensorineural hearing loss has a number of adverse perceptual consequences, including loudness recruitment, poor perception of pitch and auditory space, and difficulty understanding speech, particularly in the presence of background noise. The condition is usually incurable; treatment focuses on restoring the audibility of sounds made inaudible by hearing loss using either hearing aids or cochlear implants.

  13. Anatomy and Physiology of the Auditory Tracts

    Directory of Open Access Journals (Sweden)

    Mohammad hosein Hekmat Ara

    1999-03-01

    Full Text Available Hearing is one of the excel sense of human being. Sound waves travel through the medium of air and enter the ear canal and then hit the tympanic membrane. Middle ear transfer almost 60-80% of this mechanical energy to the inner ear by means of “impedance matching”. Then, the sound energy changes to traveling wave and is transferred based on its specific frequency and stimulates organ of corti. Receptors in this organ and their synapses transform mechanical waves to the neural waves and transfer them to the brain. The central nervous system tract of conducting the auditory signals in the auditory cortex will be explained here briefly.

  14. Modeling auditory evoked potentials to complex stimuli

    DEFF Research Database (Denmark)

    Rønne, Filip Munch

    The auditory evoked potential (AEP) is an electrical signal that can be recorded from electrodes attached to the scalp of a human subject when a sound is presented. The signal is considered to reflect neural activity in response to the acoustic stimulation and is a well established clinical...... clinically and in research towards using realistic and complex stimuli, such as speech, to electrophysiologically assess the human hearing. However, to interpret the AEP generation to complex sounds, the potential patterns in response to simple stimuli needs to be understood. Therefore, the model was used...... to simulate auditory brainstem responses (ABRs) evoked by classic stimuli like clicks, tone bursts and chirps. The ABRs to these simple stimuli were compared to literature data and the model was shown to predict the frequency dependence of tone-burst ABR wave-V latency and the level-dependence of ABR wave...

  15. Neurophysiological mechanisms involved in auditory perceptual organization

    Directory of Open Access Journals (Sweden)

    Aurélie Bidet-Caulet

    2009-09-01

    Full Text Available In our complex acoustic environment, we are confronted with a mixture of sounds produced by several simultaneous sources. However, we rarely perceive these sounds as incomprehensible noise. Our brain uses perceptual organization processes to independently follow the emission of each sound source over time. If the acoustic properties exploited in these processes are well-established, the neurophysiological mechanisms involved in auditory scene analysis have raised interest only recently. Here, we review the studies investigating these mechanisms using electrophysiological recordings from the cochlear nucleus to the auditory cortex, in animals and humans. Their findings reveal that basic mechanisms such as frequency selectivity, forward suppression and multi-second habituation shape the automatic brain responses to sounds in a way that can account for several important characteristics of perceptual organization of both simultaneous and successive sounds. One challenging question remains unresolved: how are the resulting activity patterns integrated to yield the corresponding conscious perceptsµ

  16. Cognitive mechanisms associated with auditory sensory gating.

    Science.gov (United States)

    Jones, L A; Hills, P J; Dick, K M; Jones, S P; Bright, P

    2016-02-01

    Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants additionally completed a paired-stimulus paradigm as a measure of auditory sensory gating. A correlational analysis revealed that several tasks correlated significantly with sensory gating. However once fluid intelligence and working memory were accounted for, only a measure of latent inhibition and accuracy scores on the continuous performance task showed significant sensitivity to sensory gating. We conclude that sensory gating reflects the identification of goal-irrelevant information at the encoding (input) stage and the subsequent ability to selectively attend to goal-relevant information based on that previous identification.

  17. Coverage of multiaxial fatigue criteria in fatigue limit region

    Directory of Open Access Journals (Sweden)

    Papuga J.

    2007-11-01

    Full Text Available There is a power of methods aimed at calculation of equivalent fatigue limit for arbitrary multiaxial loading. Although there are so many ways of computation, their thorough mutual comparison in a larger scale is missing. The database project presented in this paper comprise of several databases crowned with the FatLim database, which comprise of a huge number of experimental results and of 18 computational method working in the category mentioned before. The great block of data was acquired using in-house fatigue software PragTic, which is offered as a freeware application. The FatLim database follows its philosophy of a simple and non-paid accessibility. Its query tool written in MySQL and PhP allows to users to evaluate a practical usability of tested methods on load cases, which the users define. All the issues covered within this paper are available on the website www.pragtic.com, structure of which is described here.

  18. Fatigue Performance under Multiaxial Loading

    Science.gov (United States)

    1990-01-01

    to 1 1/2-inches were included. In the case of 3/4 and 1 1/2-inch specimens of HY80 4-42 steel , greater lives were obtained for the 1 1/2-inch material...COMMITTEE MARITIME COLLEGE Dr. William Sandberg Dr. W. R. Porter AMERICAN IRON AND STEEL INSTITUTE WELDING RESEARCH COUNCIL Mr. Alexander D. Wilson Dr...Various Specimen Types ...... .4-14 4-4 HY Steel Test Members Used to Investigate Multiaxial Fatigue Response ..... ............. .4-28 4-5 Effect of Mean

  19. Lesions in the external auditory canal

    Directory of Open Access Journals (Sweden)

    Priyank S Chatra

    2011-01-01

    Full Text Available The external auditory canal is an S- shaped osseo-cartilaginous structure that extends from the auricle to the tympanic membrane. Congenital, inflammatory, neoplastic, and traumatic lesions can affect the EAC. High-resolution CT is well suited for the evaluation of the temporal bone, which has a complex anatomy with multiple small structures. In this study, we describe the various lesions affecting the EAC.

  20. Midbrain auditory selectivity to natural sounds.

    Science.gov (United States)

    Wohlgemuth, Melville J; Moss, Cynthia F

    2016-03-01

    This study investigated auditory stimulus selectivity in the midbrain superior colliculus (SC) of the echolocating bat, an animal that relies on hearing to guide its orienting behaviors. Multichannel, single-unit recordings were taken across laminae of the midbrain SC of the awake, passively listening big brown bat, Eptesicus fuscus. Species-specific frequency-modulated (FM) echolocation sound sequences with dynamic spectrotemporal features served as acoustic stimuli along with artificial sound sequences matched in bandwidth, amplitude, and duration but differing in spectrotemporal structure. Neurons in dorsal sensory regions of the bat SC responded selectively to elements within the FM sound sequences, whereas neurons in ventral sensorimotor regions showed broad response profiles to natural and artificial stimuli. Moreover, a generalized linear model (GLM) constructed on responses in the dorsal SC to artificial linear FM stimuli failed to predict responses to natural sounds and vice versa, but the GLM produced accurate response predictions in ventral SC neurons. This result suggests that auditory selectivity in the dorsal extent of the bat SC arises through nonlinear mechanisms, which extract species-specific sensory information. Importantly, auditory selectivity appeared only in responses to stimuli containing the natural statistics of acoustic signals used by the bat for spatial orientation-sonar vocalizations-offering support for the hypothesis that sensory selectivity enables rapid species-specific orienting behaviors. The results of this study are the first, to our knowledge, to show auditory spectrotemporal selectivity to natural stimuli in SC neurons and serve to inform a more general understanding of mechanisms guiding sensory selectivity for natural, goal-directed orienting behaviors.

  1. Response recovery in the locust auditory pathway.

    Science.gov (United States)

    Wirtssohn, Sarah; Ronacher, Bernhard

    2016-01-01

    Temporal resolution and the time courses of recovery from acute adaptation of neurons in the auditory pathway of the grasshopper Locusta migratoria were investigated with a response recovery paradigm. We stimulated with a series of single click and click pair stimuli while performing intracellular recordings from neurons at three processing stages: receptors and first and second order interneurons. The response to the second click was expressed relative to the single click response. This allowed the uncovering of the basic temporal resolution in these neurons. The effect of adaptation increased with processing layer. While neurons in the auditory periphery displayed a steady response recovery after a short initial adaptation, many interneurons showed nonlinear effects: most prominent a long-lasting suppression of the response to the second click in a pair, as well as a gain in response if a click was preceded by a click a few milliseconds before. Our results reveal a distributed temporal filtering of input at an early auditory processing stage. This set of specified filters is very likely homologous across grasshopper species and thus forms the neurophysiological basis for extracting relevant information from a variety of different temporal signals. Interestingly, in terms of spike timing precision neurons at all three processing layers recovered very fast, within 20 ms. Spike waveform analysis of several neuron types did not sufficiently explain the response recovery profiles implemented in these neurons, indicating that temporal resolution in neurons located at several processing layers of the auditory pathway is not necessarily limited by the spike duration and refractory period.

  2. Brainstem auditory evoked response: application in neurology

    Directory of Open Access Journals (Sweden)

    Carlos A. M. Guerreiro

    1982-03-01

    Full Text Available The tecnique that we use for eliciting brainstem auditory evoked responses (BAERs is described. BAERs are a non-invasive and reliable clinical test when carefully performed. This test is indicated in the evaluation of disorders which may potentially involve the brainstem such as coma, multiple sclerosis posterior fossa tumors and others. Unsuspected lesions with normal radiologic studies (including CT-scan can be revealed by the BAER.

  3. Cognitive mechanisms associated with auditory sensory gating

    OpenAIRE

    Jones, L. A.; Hills, P.J.; Dick, K.M.; Jones, S. P.; Bright, P

    2015-01-01

    Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants addit...

  4. Thermal Fatigue Analysis of Takeover Pipeline

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    This article uses the finite element analysis software ANSYS to analyze the fatigue life of the three links pipeline with different angles in the first level pipe of experimental fast reactor. The fatigue analysis is operated following the startup and shutdown process which has two load step,

  5. Cancer-Related Fatigue: a multidimensional approach

    NARCIS (Netherlands)

    P.J. de Raaf (Pleun)

    2013-01-01

    textabstractFatigue is experienced by cancer patients in all stages of the disease trajectory: from before diagnosis to years after completing treatment and also in advanced cancer. Fatigue has a greater negative influence on quality of life and daily activities than any other cancer-related symptom

  6. Common Mathematical Model of Fatigue Characteristics

    Directory of Open Access Journals (Sweden)

    Z. Maléř

    2004-01-01

    Full Text Available This paper presents a new common mathematical model which is able to describe fatigue characteristics in the whole necessary range by one equation only:log N = A(R + B(R ∙ log Sawhere A(R = AR2 + BR + C and B(R = DR2 + AR + F.This model was verified by five sets of fatigue data taken from the literature and by our own three additional original fatigue sets. The fatigue data usually described the region of N 104 to 3 x 106 and stress ratio of R = -2 to 0.5. In all these cases the proposed model described fatigue results with small scatter. Studying this model, following knowledge was obtained:– the parameter ”stress ratio R” was a good physical characteristic– the proposed model provided a good description of the eight collections of fatigue test results by one equation only– the scatter of the results through the whole scope is only a little greater than that round the individual S/N curve– using this model while testing may reduce the number of test samples and shorten the test time– as the proposed model represents a common form of the S/N curve, it may be used for processing uniform objective fatigue life results, which may enable mutual comparison of fatigue characteristics.

  7. Exercise therapy for fatigue in multiple sclerosis

    NARCIS (Netherlands)

    Heine, Martin; van de Port, Ingrid; Rietberg, Marc B; van Wegen, Erwin Eh; Kwakkel, Gert

    2015-01-01

    BACKGROUND: Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system affecting an estimated 1.3 million people worldwide. It is characterised by a variety of disabling symptoms of which excessive fatigue is the most frequent. Fatigue is often reported as the most invalidat

  8. 14 CFR 23.627 - Fatigue strength.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fatigue strength. 23.627 Section 23.627 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of...

  9. Cancer related fatigue syndrome in neoplastic diseases

    Directory of Open Access Journals (Sweden)

    Magdalena Franc

    2014-12-01

    Full Text Available Fatigue is one of the most important factors which has a considerable influence on treatment and the life quality of oncological patients. The fatigue syndrome is often diagnosed during cancer treatment and this syndrome is not related to the physical effort. Cancer related fatigue is a patient’s subjective, psychologically, physically and emotionally based feeling. It is disproportionate to patient’s daily activity. The pathogenesis of this syndrome remains still unknown. However, on the basis of various questionnaires, it is possible to test the disease’s complex nature. Cancer related fatigue causes deterioration of patient’s life along with lower motivation to struggle with the disease. It is thought that the factor which increases the incidence of cancer related fatigue is a long-term use of drugs such as opioids, benzodiazepine, and medicines containing codeine, tranquilizers, anxiolytics and antidepressants. On the basis of the results, one can choose an appropriate treatment method for cancer related fatigue such as rehabilitation, psychotherapy or public assistance. A great number of patients consider excessive fatigue a typical concomitant symptom in neoplastic disease; therefore, they do not report it. It is of a paramount importance to make patients aware of the fact that cancer related fatigue is a serious disease which can be treated.

  10. Stroke caused auditory attention deficits in children

    Directory of Open Access Journals (Sweden)

    Karla Maria Ibraim da Freiria Elias

    2013-01-01

    Full Text Available OBJECTIVE: To verify the auditory selective attention in children with stroke. METHODS: Dichotic tests of binaural separation (non-verbal and consonant-vowel and binaural integration - digits and Staggered Spondaic Words Test (SSW - were applied in 13 children (7 boys, from 7 to 16 years, with unilateral stroke confirmed by neurological examination and neuroimaging. RESULTS: The attention performance showed significant differences in comparison to the control group in both kinds of tests. In the non-verbal test, identifications the ear opposite the lesion in the free recall stage was diminished and, in the following stages, a difficulty in directing attention was detected. In the consonant- vowel test, a modification in perceptual asymmetry and difficulty in focusing in the attended stages was found. In the digits and SSW tests, ipsilateral, contralateral and bilateral deficits were detected, depending on the characteristics of the lesions and demand of the task. CONCLUSION: Stroke caused auditory attention deficits when dealing with simultaneous sources of auditory information.

  11. Auditory perception of a human walker.

    Science.gov (United States)

    Cottrell, David; Campbell, Megan E J

    2014-01-01

    When one hears footsteps in the hall, one is able to instantly recognise it as a person: this is an everyday example of auditory biological motion perception. Despite the familiarity of this experience, research into this phenomenon is in its infancy compared with visual biological motion perception. Here, two experiments explored sensitivity to, and recognition of, auditory stimuli of biological and nonbiological origin. We hypothesised that the cadence of a walker gives rise to a temporal pattern of impact sounds that facilitates the recognition of human motion from auditory stimuli alone. First a series of detection tasks compared sensitivity with three carefully matched impact sounds: footsteps, a ball bouncing, and drumbeats. Unexpectedly, participants were no more sensitive to footsteps than to impact sounds of nonbiological origin. In the second experiment participants made discriminations between pairs of the same stimuli, in a series of recognition tasks in which the temporal pattern of impact sounds was manipulated to be either that of a walker or the pattern more typical of the source event (a ball bouncing or a drumbeat). Under these conditions, there was evidence that both temporal and nontemporal cues were important in recognising theses stimuli. It is proposed that the interval between footsteps, which reflects a walker's cadence, is a cue for the recognition of the sounds of a human walking.

  12. Hierarchical processing of auditory objects in humans.

    Directory of Open Access Journals (Sweden)

    Sukhbinder Kumar

    2007-06-01

    Full Text Available This work examines the computational architecture used by the brain during the analysis of the spectral envelope of sounds, an important acoustic feature for defining auditory objects. Dynamic causal modelling and Bayesian model selection were used to evaluate a family of 16 network models explaining functional magnetic resonance imaging responses in the right temporal lobe during spectral envelope analysis. The models encode different hypotheses about the effective connectivity between Heschl's Gyrus (HG, containing the primary auditory cortex, planum temporale (PT, and superior temporal sulcus (STS, and the modulation of that coupling during spectral envelope analysis. In particular, we aimed to determine whether information processing during spectral envelope analysis takes place in a serial or parallel fashion. The analysis provides strong support for a serial architecture with connections from HG to PT and from PT to STS and an increase of the HG to PT connection during spectral envelope analysis. The work supports a computational model of auditory object processing, based on the abstraction of spectro-temporal "templates" in the PT before further analysis of the abstracted form in anterior temporal lobe areas.

  13. Visual speech gestures modulate efferent auditory system.

    Science.gov (United States)

    Namasivayam, Aravind Kumar; Wong, Wing Yiu Stephanie; Sharma, Dinaay; van Lieshout, Pascal

    2015-03-01

    Visual and auditory systems interact at both cortical and subcortical levels. Studies suggest a highly context-specific cross-modal modulation of the auditory system by the visual system. The present study builds on this work by sampling data from 17 young healthy adults to test whether visual speech stimuli evoke different responses in the auditory efferent system compared to visual non-speech stimuli. The descending cortical influences on medial olivocochlear (MOC) activity were indirectly assessed by examining the effects of contralateral suppression of transient-evoked otoacoustic emissions (TEOAEs) at 1, 2, 3 and 4 kHz under three conditions: (a) in the absence of any contralateral noise (Baseline), (b) contralateral noise + observing facial speech gestures related to productions of vowels /a/ and /u/ and (c) contralateral noise + observing facial non-speech gestures related to smiling and frowning. The results are based on 7 individuals whose data met strict recording criteria and indicated a significant difference in TEOAE suppression between observing speech gestures relative to the non-speech gestures, but only at the 1 kHz frequency. These results suggest that observing a speech gesture compared to a non-speech gesture may trigger a difference in MOC activity, possibly to enhance peripheral neural encoding. If such findings can be reproduced in future research, sensory perception models and theories positing the downstream convergence of unisensory streams of information in the cortex may need to be revised.

  14. Auditory temporal processing skills in musicians with dyslexia.

    Science.gov (United States)

    Bishop-Liebler, Paula; Welch, Graham; Huss, Martina; Thomson, Jennifer M; Goswami, Usha

    2014-08-01

    The core cognitive difficulty in developmental dyslexia involves phonological processing, but adults and children with dyslexia also have sensory impairments. Impairments in basic auditory processing show particular links with phonological impairments, and recent studies with dyslexic children across languages reveal a relationship between auditory temporal processing and sensitivity to rhythmic timing and speech rhythm. As rhythm is explicit in music, musical training might have a beneficial effect on the auditory perception of acoustic cues to rhythm in dyslexia. Here we took advantage of the presence of musicians with and without dyslexia in musical conservatoires, comparing their auditory temporal processing abilities with those of dyslexic non-musicians matched for cognitive ability. Musicians with dyslexia showed equivalent auditory sensitivity to musicians without dyslexia and also showed equivalent rhythm perception. The data support the view that extensive rhythmic experience initiated during childhood (here in the form of music training) can affect basic auditory processing skills which are found to be deficient in individuals with dyslexia.

  15. Auditory evoked potentials in peripheral vestibular disorder individuals

    Directory of Open Access Journals (Sweden)

    Matas, Carla Gentile

    2011-07-01

    Full Text Available Introduction: The auditory and vestibular systems are located in the same peripheral receptor, however they enter the CNS and go through different ways, thus creating a number of connections and reaching a wide area of the encephalon. Despite going through different ways, some changes can impair both systems. Such tests as Auditory Evoked Potentials can help find a diagnosis when vestibular alterations are seen. Objective: describe the Auditory Evoked Potential results in individuals complaining about dizziness or vertigo with Peripheral Vestibular Disorders and in normal individuals having the same complaint. Methods: Short, middle and long latency Auditory Evoked Potentials were performed as a transversal prospective study. Conclusion: individuals complaining about dizziness or vertigo can show some changes in BAEP (Brainstem Auditory Evoked Potential, MLAEP (Medium Latency Auditory Evoked Potential and P300.

  16. Work fatigue in urban bus drivers

    Directory of Open Access Journals (Sweden)

    Teresa Makowiec-Dąbrowska

    2015-10-01

    Full Text Available Background: Bus drivers are a special group of professional drivers who are at a very high risk of fatigue. The aim of the study was to examine whether the driver’s subjective assessment of fatigue allows for the determination of its level and identification of its causes. Material and Methods: The study group comprised 45 randomly selected bus drivers (mean age – 43.7±7.9 years, period of employment as drivers – 14.7±8.6 years. Examinations were performed in all subjects four times – before and after work on the “easy” route (outside the city center, small traffic intensity and before and after work on the “difficult” route (city center, heavy traffic. The fatigue test questionnaire, based on the list of symptoms of fatigue prepared by the Japan Research Committee of Fatigue, was used in the study. Results: The rating of fatigue after the work was significantly higher than that before the work. The profile of fatigue after work was not influenced by the type of route, but the assessment of most symptoms of fatigue reached a higher level after the “difficult” routes and the differences were statistically significant for 7 symptoms. Only the ratings of leg fatigue, feeling of heaviness, and the necessity to squint eyes and gaze with effort reached the higher levels after driving the “easy” routes. It has been found that the level of fatigue was significantly correlated with the job characteristics (driving time, the length of the route, number of stops, etc. and with the abundance of food ingested and type of beverage (coffee vs. others drunk prior to driving. Conclusions: The questionnaire used in our study to assess the subjective feeling of fatigue has proved to be a sensitive and useful tool for indicating the level and causes of fatigue. The relationship between the symptoms of fatigue and the characteristics of job and lifestyle shows that actions must be taken by both the employers and employees to prevent fatigue

  17. Fatigue Minimization Work Shift Scheduling for Air Traffic Controllers

    Directory of Open Access Journals (Sweden)

    Ta-Chung Wang

    2013-05-01

    Full Text Available It is common for Air Traffic Controllers to control air traffic during the night and to experience fatigue. Although fatigue is not the direct cause of aviation accidents, 21 percent of accidents are fatigue-related. Therefore countries and companies have tried to regulate work hours to avoid extreme fatigue, thus decreasing human error resulting from fatigue. However, these regulations may not reflect that actual fatigue variation and fatigue levels can be decreased still more by scheduling appropriately. This paper focuses on optimal work shift scheduling to reduce air traffic controller fatigue. First, a mathematical model is established to describe fatigue levels. The objective function is to reduce the fatigue peak produced by work shifts as much as possible. Various constraints, such as holidays and manpower requirements are considered. The optimization problem is then solved using integer programming. We take a sample schedule and draw conclusions by comparing our results with the original fatigue levels.

  18. Auditory cortical processing in real-world listening: the auditory system going real.

    Science.gov (United States)

    Nelken, Israel; Bizley, Jennifer; Shamma, Shihab A; Wang, Xiaoqin

    2014-11-12

    The auditory sense of humans transforms intrinsically senseless pressure waveforms into spectacularly rich perceptual phenomena: the music of Bach or the Beatles, the poetry of Li Bai or Omar Khayyam, or more prosaically the sense of the world filled with objects emitting sounds that is so important for those of us lucky enough to have hearing. Whereas the early representations of sounds in the auditory system are based on their physical structure, higher auditory centers are thought to represent sounds in terms of their perceptual attributes. In this symposium, we will illustrate the current research into this process, using four case studies. We will illustrate how the spectral and temporal properties of sounds are used to bind together, segregate, categorize, and interpret sound patterns on their way to acquire meaning, with important lessons to other sensory systems as well.

  19. Fatigue in adults with traumatic brain injury

    DEFF Research Database (Denmark)

    Mollayeva, Tatyana; Kendzerska, Tetyana; Mollayeva, Shirin;

    2013-01-01

    . CONCLUSIONS: The review will summarize the current knowledge in the field with the aim of increasing understanding and guiding future research on the associations between fatigue and clinically important factors, as well as the consequences of fatigue in traumatic brain injury. PROSPERO registry number: CRD......BACKGROUND: Despite strong indications that fatigue is the most common and debilitating symptom after traumatic brain injury, little is known about its frequency, natural history, or relation to other factors. The current protocol outlines a strategy for a systematic review that will identify......, assess, and critically appraise studies that assessed predictors for fatigue and the consequences of fatigue on at least two separate time points following traumatic brain injury. METHODS/DESIGN: MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews, CINAHL, and PsycINFO will be systematically...

  20. Thermal fatigue behavior of K465 superalloy

    Institute of Scientific and Technical Information of China (English)

    YANG Jinxia; ZHENG Qi; SUN Xiaofeng; GUAN Hengrong; HU Zhuangqi

    2006-01-01

    The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy (SEM) and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast (named as K465) and solution heat treatment (named as SK465) conditions.In K465 alloy, most thermal fatigue cracks nucleate at (Nb,W,Ti)C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode,and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.

  1. Damage identity in fatigue assessment of structures

    Directory of Open Access Journals (Sweden)

    S.V. Petinov

    2016-04-01

    Full Text Available The modified strain criterion-based method for fatigue assessment of structures is discussed. The damage is estimated based on the specified parameters of the criterion and the damage summation procedure by employing the finite-element method. With a reasonably fine mesh of the finiteelement model of the ‘critical location’ structure, the condition of the identity of damage in the material of the test specimen and the structure is provided and, respectively, the effect of uncertainty on the fatigue life assessment of the structure is reduced. The implementation of this version of the method is using the example of the fatigue life evaluation of a ship hull and superstructure detail at expansion joint. For comparison, the fatigue life of the detail is estimated using the standard S-N approach. The results are in approximate agreement; however, reducing the computational uncertainties with the help of the deformation criterion shows more physically reasonable fatigue properties of the detail.

  2. Parallel monostrand stay cable bending fatigue

    DEFF Research Database (Denmark)

    Winkler, Jan Pawel

    of damage and replacement of bridge stay cables due to wind and traffic-induced fatigue. The understanding of fatigue mechanisms in most steel structures is well established. However, in the case of cables composed of steel strands, many important aspects related with bending fatigue remain to be clarified......This dissertation investigates the bending fatigue response of high-strength steel monostrands and multistrand stay cables to cyclic transverse deformations. Increasing bridge stock numbers and a push for longer cable-supported span lengths have led to an increased number of reported incidents...... associated with variable loading, and different testing procedures. As most of the contemporary stay cables are comprised of a number of individual highstrength steel monostrands, the research study started with an extensive experimental work on the fatigue response of a single monostrand to cyclic flexural...

  3. Fatigue in Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    1999-01-01

    types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel with a yield stress of ~ 360-410 MPa or high-strength steel with a yield stress of ~ 810-1010 MPa. The fatigue tests and the fracture mechanics analyses......Fatigue damage accumulation in steel structures under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series have been carried through on various...... have been carried out using load histories, which are realistic in relation to the types of structures studied, i.e. primarily bridges, offshore structures and chimneys. In general, the test series carried through show a significant difference between constant amplitude and variable amplitude fatigue...

  4. On the Fatigue Analysis of Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, Herbert J.

    1999-06-01

    Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

  5. Binaural technology for e.g. rendering auditory virtual environments

    DEFF Research Database (Denmark)

    Hammershøi, Dorte

    2008-01-01

    , helped mediate the understanding that if the transfer functions could be mastered, then important dimensions of the auditory percept could also be controlled. He early understood the potential of using the HRTFs and numerical sound transmission analysis programs for rendering auditory virtual...... environments. Jens Blauert participated in many European cooperation projects exploring  this field (and others), among other the SCATIS project addressing the auditory-tactile dimensions in the absence of visual information....

  6. Depth-Dependent Temporal Response Properties in Core Auditory Cortex

    OpenAIRE

    Christianson, G. Björn; Sahani, Maneesh; Linden, Jennifer F.

    2011-01-01

    The computational role of cortical layers within auditory cortex has proven difficult to establish. One hypothesis is that interlaminar cortical processing might be dedicated to analyzing temporal properties of sounds; if so, then there should be systematic depth-dependent changes in cortical sensitivity to the temporal context in which a stimulus occurs. We recorded neural responses simultaneously across cortical depth in primary auditory cortex and anterior auditory field of CBA/Ca mice, an...

  7. [Auditory guidance systems for the visually impaired people].

    Science.gov (United States)

    He, Jing; Nie, Min; Luo, Lan; Tong, Shanbao; Niu, Jinhai; Zhu, Yisheng

    2010-04-01

    Visually impaired people face many inconveniences because of the loss of vision. Therefore, scientists are trying to design various guidance systems for improving the lives of the blind. Based on sensory substitution, auditory guidance has become an interesting topic in the field of biomedical engineering. In this paper, we made a state-of-technique review of the auditory guidance system. Although there have been many technical challenges, the auditory guidance system would be a useful alternative for the visually impaired people.

  8. Auditory cortex basal activity modulates cochlear responses in chinchillas.

    Directory of Open Access Journals (Sweden)

    Alex León

    Full Text Available BACKGROUND: The auditory efferent system has unique neuroanatomical pathways that connect the cerebral cortex with sensory receptor cells. Pyramidal neurons located in layers V and VI of the primary auditory cortex constitute descending projections to the thalamus, inferior colliculus, and even directly to the superior olivary complex and to the cochlear nucleus. Efferent pathways are connected to the cochlear receptor by the olivocochlear system, which innervates outer hair cells and auditory nerve fibers. The functional role of the cortico-olivocochlear efferent system remains debated. We hypothesized that auditory cortex basal activity modulates cochlear and auditory-nerve afferent responses through the efferent system. METHODOLOGY/PRINCIPAL FINDINGS: Cochlear microphonics (CM, auditory-nerve compound action potentials (CAP and auditory cortex evoked potentials (ACEP were recorded in twenty anesthetized chinchillas, before, during and after auditory cortex deactivation by two methods: lidocaine microinjections or cortical cooling with cryoloops. Auditory cortex deactivation induced a transient reduction in ACEP amplitudes in fifteen animals (deactivation experiments and a permanent reduction in five chinchillas (lesion experiments. We found significant changes in the amplitude of CM in both types of experiments, being the most common effect a CM decrease found in fifteen animals. Concomitantly to CM amplitude changes, we found CAP increases in seven chinchillas and CAP reductions in thirteen animals. Although ACEP amplitudes were completely recovered after ninety minutes in deactivation experiments, only partial recovery was observed in the magnitudes of cochlear responses. CONCLUSIONS/SIGNIFICANCE: These results show that blocking ongoing auditory cortex activity modulates CM and CAP responses, demonstrating that cortico-olivocochlear circuits regulate auditory nerve and cochlear responses through a basal efferent tone. The diversity of the

  9. Using Facebook to Reach People Who Experience Auditory Hallucinations

    OpenAIRE

    Crosier, Benjamin Sage; Brian, Rachel Marie; Ben-Zeev, Dror

    2016-01-01

    Background Auditory hallucinations (eg, hearing voices) are relatively common and underreported false sensory experiences that may produce distress and impairment. A large proportion of those who experience auditory hallucinations go unidentified and untreated. Traditional engagement methods oftentimes fall short in reaching the diverse population of people who experience auditory hallucinations. Objective The objective of this proof-of-concept study was to examine the viability of leveraging...

  10. Myosin VIIA, important for human auditory function, is necessary for Drosophila auditory organ development.

    Directory of Open Access Journals (Sweden)

    Sokol V Todi

    Full Text Available BACKGROUND: Myosin VIIA (MyoVIIA is an unconventional myosin necessary for vertebrate audition [1]-[5]. Human auditory transduction occurs in sensory hair cells with a staircase-like arrangement of apical protrusions called stereocilia. In these hair cells, MyoVIIA maintains stereocilia organization [6]. Severe mutations in the Drosophila MyoVIIA orthologue, crinkled (ck, are semi-lethal [7] and lead to deafness by disrupting antennal auditory organ (Johnston's Organ, JO organization [8]. ck/MyoVIIA mutations result in apical detachment of auditory transduction units (scolopidia from the cuticle that transmits antennal vibrations as mechanical stimuli to JO. PRINCIPAL FINDINGS: Using flies expressing GFP-tagged NompA, a protein required for auditory organ organization in Drosophila, we examined the role of ck/MyoVIIA in JO development and maintenance through confocal microscopy and extracellular electrophysiology. Here we show that ck/MyoVIIA is necessary early in the developing antenna for initial apical attachment of the scolopidia to the articulating joint. ck/MyoVIIA is also necessary to maintain scolopidial attachment throughout adulthood. Moreover, in the adult JO, ck/MyoVIIA genetically interacts with the non-muscle myosin II (through its regulatory light chain protein and the myosin binding subunit of myosin II phosphatase. Such genetic interactions have not previously been observed in scolopidia. These factors are therefore candidates for modulating MyoVIIA activity in vertebrates. CONCLUSIONS: Our findings indicate that MyoVIIA plays evolutionarily conserved roles in auditory organ development and maintenance in invertebrates and vertebrates, enhancing our understanding of auditory organ development and function, as well as providing significant clues for future research.

  11. Effect of auditory training on the middle latency response in children with (central) auditory processing disorder.

    Science.gov (United States)

    Schochat, E; Musiek, F E; Alonso, R; Ogata, J

    2010-08-01

    The purpose of this study was to determine the middle latency response (MLR) characteristics (latency and amplitude) in children with (central) auditory processing disorder [(C)APD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (C)APD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (C)APD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (C)APD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 microV (mean), 0.39 (SD--standard deviation) for the (C)APD group and 1.18 microV (mean), 0.65 (SD) for the control group; C3-A2, 0.69 microV (mean), 0.31 (SD) for the (C)APD group and 1.00 microV (mean), 0.46 (SD) for the control group]. After training, the MLR C3-A1 [1.59 microV (mean), 0.82 (SD)] and C3-A2 [1.24 microV (mean), 0.73 (SD)] wave amplitudes of the (C)APD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (C)APD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (C)APD.

  12. Effect of auditory training on the middle latency response in children with (central auditory processing disorder

    Directory of Open Access Journals (Sweden)

    E. Schochat

    2010-08-01

    Full Text Available The purpose of this study was to determine the middle latency response (MLR characteristics (latency and amplitude in children with (central auditory processing disorder [(CAPD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (CAPD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (CAPD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (CAPD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 µV (mean, 0.39 (SD - standard deviation for the (CAPD group and 1.18 µV (mean, 0.65 (SD for the control group; C3-A2, 0.69 µV (mean, 0.31 (SD for the (CAPD group and 1.00 µV (mean, 0.46 (SD for the control group]. After training, the MLR C3-A1 [1.59 µV (mean, 0.82 (SD] and C3-A2 [1.24 µV (mean, 0.73 (SD] wave amplitudes of the (CAPD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (CAPD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (CAPD.

  13. Mental fatigue modulates dynamic adaptation to perceptual demand in speeded detection.

    Directory of Open Access Journals (Sweden)

    Robert Langner

    Full Text Available When stimulus intensity in simple reaction-time tasks randomly varies across trials, detection speed usually improves after a low-intensity trial. With auditory stimuli, this improvement was often found to be asymmetric, being greater on current low-intensity trials. Our study investigated (1 whether asymmetric sequential intensity adaptation also occurs with visual stimuli; (2 whether these adjustments reflect decision-criterion shifts or, rather, a modulation of perceptual sensitivity; and (3 how sequential intensity adaptation and its underlying mechanisms are affected by mental fatigue induced through prolonged performance. In a continuous speeded detection task with randomly alternating high- and low-intensity visual stimuli, the reaction-time benefit after low-intensity trials was greater on subsequent low- than high-intensity trials. This asymmetry, however, only developed with time on task (TOT. Signal-detection analyses showed that the decision criterion transiently became more liberal after a low-intensity trial, whereas observer sensitivity increased when the preceding and current stimulus were of equal intensity. TOT-induced mental fatigue only affected sensitivity, which dropped more on low- than on high-intensity trials. This differential fatigue-related sensitivity decrease selectively enhanced the impact of criterion down-shifts on low-intensity trials, revealing how the interplay of two perceptual mechanisms and their modulation by fatigue combine to produce the observed overall pattern of asymmetric performance adjustments to varying visual intensity in continuous speeded detection. Our results have implications for similar patterns of sequential demand adaptation in other cognitive domains as well as for real-world prolonged detection performance.

  14. Temperament vs. chronic fatigue in police officers

    Directory of Open Access Journals (Sweden)

    Ewa Stępka

    2015-12-01

    Full Text Available Background: Chronic fatigue is a problem affecting a still growing number of people. Among them there are representatives of different professions who are forced to cope not only with occupational stress, but also with the problem of fatigue. The police is one of such occupational groups, in which exposure to stressful and often traumatic situations, contact with those who violate the law, shift work and contact with superiors can play a key role in the development of chronic fatigue. However, chronic fatigue, induced by the above mentioned factors, does not affect all police officers since its occurrence also depends on many personal traits, including temperament. Material and methods: We studied a group of 61 police officers of the Kuyavian-Pomeranian garrison. The study was conducted using the Buss and Plomin EAS (emotionality, activity, sociability Temperament Questionnaire, CIS-20R (community, innovation, survey Questionnaire, developed by Vercoulen et al. and a questionnaire on socio-demographic data. Results: The results indicated the relationship between chronic fatigue and emotionality. Statistical analyses showed a negative correlation between the nature of emotional components, distress, fear, anger, and the general rate of chronic fatigue. There was no statistically significant correlation between age, and service experience and the level of chronic fatigue. Conclusions: The results indicate that the officers of the study group show dramatically high levels of chronic fatigue. The results also revealed that temperament characteristics, such as sociability and activity, reported in the literature as factors reducing fatigue and stress, did not show relevance to chronic fatigue in the study group. Med Pr 2015;66(6:793–801

  15. Sound objects – Auditory objects – Musical objects

    DEFF Research Database (Denmark)

    Hjortkjær, Jens

    2015-01-01

    The auditory system transforms patterns of sound energy into perceptual objects but the precise definition of an ‘auditory object’ is much debated. In the context of music listening, Pierre Schaeffer argued that ‘sound objects’ are the fundamental perceptual units in ‘musical objects......’. In this paper, I review recent neurocognitive research suggesting that the auditory system is sensitive to structural information about real-world objects. Instead of focusing solely on perceptual sound features as determinants of auditory objects, I propose that real-world object properties are inherent...

  16. Sound objects – Auditory objects – Musical objects

    DEFF Research Database (Denmark)

    Hjortkjær, Jens

    2016-01-01

    The auditory system transforms patterns of sound energy into perceptual objects but the precise definition of an ‘auditory object’ is much debated. In the context of music listening, Pierre Schaeffer argued that ‘sound objects’ are the fundamental perceptual units in ‘musical objects......’. In this paper, I review recent neurocognitive research suggesting that the auditory system is sensitive to structural information about real-world objects. Instead of focusing solely on perceptual sound features as determinants of auditory objects, I propose that real-world object properties are inherent...

  17. Extrinsic sound stimulations and development of periphery auditory synapses

    Institute of Scientific and Technical Information of China (English)

    Kun Hou; Shiming Yang; Ke Liu

    2015-01-01

    The development of auditory synapses is a key process for the maturation of hearing function. However, it is still on debate regarding whether the development of auditory synapses is dominated by acquired sound stimulations. In this review, we summarize relevant publications in recent decades to address this issue. Most reported data suggest that extrinsic sound stimulations do affect, but not govern the development of periphery auditory synapses. Overall, periphery auditory synapses develop and mature according to its intrinsic mechanism to build up the synaptic connections between sensory neurons and/or interneurons.

  18. Evaluation of peripheral compression and auditory nerve fiber intensity coding using auditory steady-state responses

    DEFF Research Database (Denmark)

    Encina Llamas, Gerard; M. Harte, James; Epp, Bastian

    2015-01-01

    The compressive nonlinearity of the auditory system is assumed to be an epiphenomenon of a healthy cochlea and, particularly, of outer-hair cell function. Another ability of the healthy auditory system is to enable communication in acoustical environments with high-level background noises....... Evaluation of these properties provides information about the health state of the system. It has been shown that a loss of outer hair cells leads to a reduction in peripheral compression. It has also recently been shown in animal studies that noise over-exposure, producing temporary threshold shifts, can...

  19. Organization of the auditory brainstem in a lizard, Gekko gecko. I. Auditory nerve, cochlear nuclei, and superior olivary nuclei

    DEFF Research Database (Denmark)

    Tang, Y. Z.; Christensen-Dalsgaard, J.; Carr, C. E.

    2012-01-01

    We used tract tracing to reveal the connections of the auditory brainstem in the Tokay gecko (Gekko gecko). The auditory nerve has two divisions, a rostroventrally directed projection of mid- to high best-frequency fibers to the nucleus angularis (NA) and a more dorsal and caudal projection of lo...... of auditory connections in lizards and archosaurs but also different processing of low- and high-frequency information in the brainstem. J. Comp. Neurol. 520:17841799, 2012. (C) 2011 Wiley Periodicals, Inc...

  20. Weak responses to auditory feedback perturbation during articulation in persons who stutter: evidence for abnormal auditory-motor transformation.

    Directory of Open Access Journals (Sweden)

    Shanqing Cai

    Full Text Available Previous empirical observations have led researchers to propose that auditory feedback (the auditory perception of self-produced sounds when speaking functions abnormally in the speech motor systems of persons who stutter (PWS. Researchers have theorized that an important neural basis of stuttering is the aberrant integration of auditory information into incipient speech motor commands. Because of the circumstantial support for these hypotheses and the differences and contradictions between them, there is a need for carefully designed experiments that directly examine auditory-motor integration during speech production in PWS. In the current study, we used real-time manipulation of auditory feedback to directly investigate whether the speech motor system of PWS utilizes auditory feedback abnormally during articulation and to characterize potential deficits of this auditory-motor integration. Twenty-one PWS and 18 fluent control participants were recruited. Using a short-latency formant-perturbation system, we examined participants' compensatory responses to unanticipated perturbation of auditory feedback of the first formant frequency during the production of the monophthong [ε]. The PWS showed compensatory responses that were qualitatively similar to the controls' and had close-to-normal latencies (∼150 ms, but the magnitudes of their responses were substantially and significantly smaller than those of the control participants (by 47% on average, p<0.05. Measurements of auditory acuity indicate that the weaker-than-normal compensatory responses in PWS were not attributable to a deficit in low-level auditory processing. These findings are consistent with the hypothesis that stuttering is associated with functional defects in the inverse models responsible for the transformation from the domain of auditory targets and auditory error information into the domain of speech motor commands.

  1. Random non-proportional fatigue tests with planar tri-axial fatigue testing machine

    Directory of Open Access Journals (Sweden)

    T. Inoue

    2016-10-01

    Full Text Available Complex stresses, which occur on the mechanical surfaces of transport machinery in service, bring a drastic degradation in fatigue life. However, it is hard to reproduce such complex stress states for evaluating the fatigue life with conventional multiaxial fatigue machines. We have developed a fatigue testing machine that enables reproduction of such complex stresses. The testing machine can reproduce arbitrary in-plane stress states by applying three independent loads to the test specimen using actuators which apply loads in the 0, 45, and 90 degree directions. The reproduction was tested with complex stress data obtained from the actual operation of transport machinery. As a result, it was found that the reproduced stress corresponded to the measured stress with an error range of less than 10 %. Then, we made a comparison between measured fatigue lives under random non-proportional loading conditions and predicted fatigue lives. It was found that predicted fatigue lives with cr, stress on critical plane, were over a factor of 10 against measured fatigue lives. On the other hand, predicted fatigue lives with ma, stress in consideration of a non-proportional level evaluated by using amplitude and direction of principal stress, were within a factor of 3 against measured fatigue lives

  2. The measurement of fatigue in chronic illness: a systematic review of unidimensional and multidimensional fatigue measures.

    Science.gov (United States)

    Whitehead, Lisa

    2009-01-01

    Fatigue is a common symptom associated with a wide range of chronic diseases. A large number of instruments have been developed to measure fatigue. An assessment regarding the reliability, validity, and utility of fatigue measures is time-consuming for the clinician and researcher, and few reviews exist on which to draw such information. The aim of this article is to present a critical review of fatigue measures, the populations in which the scales have been used, and the extent to which the psychometric properties of each instrument have been evaluated to provide clinicians and researchers with information on which to base decisions. Seven databases were searched for all articles that measured fatigue and offered an insight into the psychometric properties of the scales used over the period 1980-2007. Criteria for judging the "ideal" measure were developed to encompass scale usability, clinical/research utility, and the robustness of psychometric properties. Twenty-two fatigue measures met the inclusion criteria and were evaluated. A further 17 measures met some of the criteria, but have not been tested beyond initial development, and are reviewed briefly at the end of the article. The review did not identify any instrument that met all the criteria of an ideal instrument. However, a small number of short instruments demonstrated good psychometric properties (Fatigue Severity Scale [FSS], Fatigue Impact Scale [FIS], and Brief Fatigue Inventory [BFI]), and three comprehensive instruments demonstrated the same (Fatigue Symptom Inventory [FSI], Multidimensional Assessment of Fatigue [MAF], and Multidimensional Fatigue Symptom Inventory [MFSI]). Only four measures (BFI, FSS, FSI, and MAF) demonstrated the ability to detect change over time. The clinician and researcher also should consider the populations in which the scale has been used previously to assess its validity with their own patient group, and assess the content of a scale to ensure that the key qualitative

  3. Predictors and Trajectories of Morning Fatigue Are Distinct from Evening Fatigue

    Science.gov (United States)

    Wright, Fay; Melkus, Gail D’Eramo; Hammer, Marilyn; Schmidt, Brian L.; Knobf, M. Tish; Paul, Steven M.; Cartwright, Frances; Mastick, Judy; Cooper, Bruce A.; Chen, Lee-May; Melisko, Michelle; Levine, Jon D.; Kober, Kord; Aouizerat, Bradley E.; Miaskowski, Christine

    2015-01-01

    Context Fatigue is the most common symptom in oncology patients during chemotherapy (CTX). Little is known about the predictors of interindividual variability in initial levels and trajectories of morning fatigue severity in these patients. Objectives An evaluation was done to determine which demographic, clinical, and symptom characteristics were associated with initial levels as well as the trajectories of morning fatigue and to compare findings with our companion paper on evening fatigue. Methods A sample of outpatients with breast, gastrointestinal, gynecological, and lung cancer (N=586) completed demographic and symptom questionnaires a total of six times over two cycles of CTX. Fatigue severity was evaluated using the Lee Fatigue Scale. Hierarchical linear modeling (HLM) was used to answer the study objectives. Results A large amount of interindividual variability was found in the morning fatigue trajectories. A piecewise model fit the data best. Patients with higher body mass index (BMI), who did not exercise regularly, with a lower functional status, and who had higher levels of state anxiety, sleep disturbance and depressive symptoms, reported higher levels of morning fatigue at enrollment. Variations in the trajectories of morning fatigue were predicted by the patients’ ethnicity and younger age. Conclusion The modifiable risk factors that were associated with only morning fatigue were BMI, exercise, and state anxiety. Modifiable risk factors that were associated with both morning and evening fatigue included functional status, depressive symptoms, and sleep disturbance. Using this information, clinicians can identify patients at higher risk for more severe morning fatigue and evening fatigue, provide individualized patient education, and tailor interventions to address the modifiable risk factors. PMID:25828559

  4. Fatigue

    Science.gov (United States)

    ... Taking certain medicines, such as antidepressants, antihistamines, and medicines for nausea and pain Having medical treatments, like chemotherapy and radiation Recovering from major surgery Anxiety, stress, or depression Staying up too late Drinking too much alcohol ...

  5. Visual cortex and auditory cortex activation in early binocularly blind macaques: A BOLD-fMRI study using auditory stimuli.

    Science.gov (United States)

    Wang, Rong; Wu, Lingjie; Tang, Zuohua; Sun, Xinghuai; Feng, Xiaoyuan; Tang, Weijun; Qian, Wen; Wang, Jie; Jin, Lixin; Zhong, Yufeng; Xiao, Zebin

    2017-04-15

    Cross-modal plasticity within the visual and auditory cortices of early binocularly blind macaques is not well studied. In this study, four healthy neonatal macaques were assigned to group A (control group) or group B (binocularly blind group). Sixteen months later, blood oxygenation level-dependent functional imaging (BOLD-fMRI) was conducted to examine the activation in the visual and auditory cortices of each macaque while being tested using pure tones as auditory stimuli. The changes in the BOLD response in the visual and auditory cortices of all macaques were compared with immunofluorescence staining findings. Compared with group A, greater BOLD activity was observed in the bilateral visual cortices of group B, and this effect was particularly obvious in the right visual cortex. In addition, more activated volumes were found in the bilateral auditory cortices of group B than of group A, especially in the right auditory cortex. These findings were consistent with the fact that there were more c-Fos-positive cells in the bilateral visual and auditory cortices of group B compared with group A (p visual cortices of binocularly blind macaques can be reorganized to process auditory stimuli after visual deprivation, and this effect is more obvious in the right than the left visual cortex. These results indicate the establishment of cross-modal plasticity within the visual and auditory cortices.

  6. THE FREQUANCY DEPENDANCE OF THE FATIGUE FRACTURE CRITERION

    Directory of Open Access Journals (Sweden)

    Arutyunyan A. R.

    2007-03-01

    Full Text Available Some recent fatigue tests [1, 2] indicate that the fatigue curves have two fatigue limits. Experiments [3] also indicate the strong frequency dependence of the fatigue fracture process. These two effects are the main topics of the paper.

  7. Fatigue performance of welded aluminum deck structures

    Energy Technology Data Exchange (ETDEWEB)

    Haagensen, P.J.; Ranes, M.; Kluken, A.O.; Kvale, I.

    1996-12-01

    Aluminum alloys are used increasingly in load carrying structures where low weight and low maintenance costs are at a premium. Helicopter decks, structures for living quarters and personnel transfer bridges between platforms are examples of offshore applications. While these structures are not usually subjected to high fatigue loads, the increasing use of aluminum in high speed ships, and more recently in highway bridge structures, makes the question of fatigue performance more important. In this paper the fatigue properties of small scale weldments in an AA6005 alloy are compared with the results of fatigue tests on full scale sections of welded extrusions in the same material, which were used in an aluminum bridge deck structure. The fatigue performance is also compared with the fatigue clauses in the new British design code BS8118 for aluminium structures and the proposed Eurocode 9. The prospects of using a new joining technique, friction stir welding (FSW), in the production of large scale panels for deck and ship hull structures is discussed. The FSW process is described briefly, and some fatigue test data are presented.

  8. COGNITIVE FATIGUE FACILITATES PROCEDURAL SEQUENCE LEARNING

    Directory of Open Access Journals (Sweden)

    Guillermo eBorragán

    2016-03-01

    Full Text Available Enhanced procedural learning has been evidenced in conditions where cognitive control is diminished, including hypnosis, disruption of prefrontal activity and non-optimal time of the day. Another condition depleting the availability of controlled resources is cognitive fatigue. We tested the hypothesis that cognitive fatigue, eventually leading to diminished cognitive control, facilitates procedural sequence learning. In a two-day experiment, twenty-three young healthy adults were administered a serial reaction time task (SRTT following the induction of high or low levels of cognitive fatigue, in a counterbalanced order. Cognitive fatigue was induced using the Time load Dual-back (TloadDback paradigm, a dual working memory task that allows tailoring cognitive load levels to the individual's optimal performance capacity. In line with our hypothesis, reaction times in the SRTT were faster in the high- than in the low-level fatigue condition, and performance improvement showed more of a benefit from the sequential components than from motor. Altogether, our results suggest a paradoxical, facilitating impact of cognitive fatigue on procedural motor sequence learning. We propose that facilitated learning in the high-level fatigue condition stems from a reduction in the cognitive resources devoted to cognitive control processes that normally oppose automatic procedural acquisition mechanisms.

  9. Fatigue and cardiorespiratory function following abdominal surgery.

    Science.gov (United States)

    Christensen, T; Bendix, T; Kehlet, H

    1982-07-01

    Subjective feelings of fatigue were assessed before operation and 10, 20 and 30 days after uncomplicated elective abdominal surgery in 16 otherwise healthy patients, using a constructed fatigue scale model. In addition, all patients had an orthostatic stress test performed at the same times. Six of the patients also underwent a bicycle ergometer test measuring heart rate and oxygen consumption. Subjective feelings of fatigue were increased (P less than 0.01) at all three postoperative observations, and only 5 of 16 patients returned to their preoperative level. The increased subjective feeling of fatigue correlated positively (RS = 0.53, P less than 0.001) with the increased pulse rate seen during orthostatic stress after operation. Heart rate was about 5 per cent higher (n.s.) after operation when bicycling at the same work loads, while oxygen consumption decreased by about 2 per cent (P less than 0.01) at all three postoperative bicycle tests. It is concluded that even electric uncomplicated abdominal surgery is followed by a pronounced feeling of fatigue, which may persist 1 month after surgery in about one-third of patients. The fatigue scale model seems applicable for future studies on the pathogenesis and treatment of the postoperative fatigue syndrome.

  10. Fatigue crack propagation analysis of plaque rupture.

    Science.gov (United States)

    Pei, Xuan; Wu, Baijian; Li, Zhi-Yong

    2013-10-01

    Rupture of atheromatous plaque is the major cause of stroke or heart attack. Considering that the cardiovascular system is a classic fatigue environment, plaque rupture was treated as a chronic fatigue crack growth process in this study. Fracture mechanics theory was introduced to describe the stress status at the crack tip and Paris' law was used to calculate the crack growth rate. The effect of anatomical variation of an idealized plaque cross-section model was investigated. The crack initiation was considered to be either at the maximum circumferential stress location or at any other possible locations around the lumen. Although the crack automatically initialized at the maximum circumferential stress location usually propagated faster than others, it was not necessarily the most critical location where the fatigue life reached its minimum. We found that the fatigue life was minimum for cracks initialized in the following three regions: the midcap zone, the shoulder zone, and the backside zone. The anatomical variation has a significant influence on the fatigue life. Either a decrease in cap thickness or an increase in lipid pool size resulted in a significant decrease in fatigue life. Comparing to the previously used stress analysis, this fatigue model provides some possible explanations of plaque rupture at a low stress level in a pulsatile cardiovascular environment, and the method proposed here may be useful for further investigation of the mechanism of plaque rupture based on in vivo patient data.

  11. Probabilistic fatigue methodology and wind turbine reliability

    Energy Technology Data Exchange (ETDEWEB)

    Lange, C.H. [Stanford Univ., CA (United States)

    1996-05-01

    Wind turbines subjected to highly irregular loadings due to wind, gravity, and gyroscopic effects are especially vulnerable to fatigue damage. The objective of this study is to develop and illustrate methods for the probabilistic analysis and design of fatigue-sensitive wind turbine components. A computer program (CYCLES) that estimates fatigue reliability of structural and mechanical components has been developed. A FORM/SORM analysis is used to compute failure probabilities and importance factors of the random variables. The limit state equation includes uncertainty in environmental loading, gross structural response, and local fatigue properties. Several techniques are shown to better study fatigue loads data. Common one-parameter models, such as the Rayleigh and exponential models are shown to produce dramatically different estimates of load distributions and fatigue damage. Improved fits may be achieved with the two-parameter Weibull model. High b values require better modeling of relatively large stress ranges; this is effectively done by matching at least two moments (Weibull) and better by matching still higher moments. For this purpose, a new, four-moment {open_quotes}generalized Weibull{close_quotes} model is introduced. Load and resistance factor design (LRFD) methodology for design against fatigue is proposed and demonstrated using data from two horizontal-axis wind turbines. To estimate fatigue damage, wind turbine blade loads have been represented by their first three statistical moments across a range of wind conditions. Based on the moments {mu}{sub 1}{hor_ellipsis}{mu}{sub 3}, new {open_quotes}quadratic Weibull{close_quotes} load distribution models are introduced. The fatigue reliability is found to be notably affected by the choice of load distribution model.

  12. Low-cycle fatigue of surgical cements

    Directory of Open Access Journals (Sweden)

    A. Balin

    2007-01-01

    Full Text Available Purpose: In case when surgical cement is used to fix endoprostheses of joints the fatigue character of mechanicalinterraction in the cement seems to be a significant importance. The paper suggests to adapt the research methodof low cycle fatigue for modelling the loads on surgical cements in an artificial hip joint. Surgical cements havealso been modified in order to improve their functional properties.Design/methodology/approach: Low cycle fatigue tests were conducted on samples made from Palamedcement without an addition and on samples modified with glassy carbon and titanium. The tests were conductedon a servohydraulic fatigue testing machine, MTS-810, with displacement control.Findings: Fatigue tests proved viscoelastic character of all the tested materials. During the fatigue tests, thephenomenon of stress cyclic relaxation was observed.Research limitations/implications: Modelling the loadings of cement in endoprostheses of joints with the lowcycle fatigue method takes into account all high value stresses, while cement is being used for endoprosthesesfor many years in the conditions of random stress and deformation courses. Therefore the obtained stress anddeformation values are bigger than those which would have been obtained in real conditions in the same time.Practical implications: The low cycle fatigue tests carried out showed how important is the factor of timefor the behavior of surgical cement in the conditions of changeable loadings. This fact is essential to assessits usability for endoprosthesoplasty of joints, specially of a hip joint. Post deformation return which is acharacteristic feature for material viscoelasticity enables its regeneration conditioning expected durability ofendoprosthesis of joints.Originality/value: Low cycle fatigue testing method for modelling of loads on surgical cement in artificial hipjoint enables to carry out the tests in a shorter period of time.

  13. Biomarkers of peripheral muscle fatigue during exercise

    Directory of Open Access Journals (Sweden)

    Finsterer Josef

    2012-11-01

    Full Text Available Abstract Background Biomarkers of peripheral muscle fatigue (BPMFs are used to offer insights into mechanisms of exhaustion during exercise in order to detect abnormal fatigue or to detect defective metabolic pathways. This review aims at describing recent advances and future perspectives concerning the most important biomarkers of muscle fatigue during exercise. Results BPMFs are classified according to the mechanism of fatigue related to adenosine-triphosphate-metabolism, acidosis, or oxidative-metabolism. Muscle fatigue is also related to an immunological response. impaired calcium handling, disturbances in bioenergetic pathways, and genetic responses. The immunological and genetic response may make the muscle susceptible to fatigue but may not directly cause muscle fatigue. Production of BPMFs is predominantly dependent on the type of exercise. BPMFs need to change as a function of the process being monitored, be stable without appreciable diurnal variations, correlate well with exercise intensity, and be present in detectable amounts in easily accessible biological fluids. The most well-known BPMFs are serum lactate and interleukin-6. The most widely applied clinical application is screening for defective oxidative metabolism in mitochondrial disorders by means of the lactate stress test. The clinical relevance of most other BPMFs, however, is under debate, since they often depend on age, gender, physical fitness, the energy supply during exercise, the type of exercise needed to produce the BPMF, and whether healthy or diseased subjects are investigated. Conclusions Though the role of BPMFs during fatigue is poorly understood, measuring BPMFs under specific, standardised conditions appears to be helpful for assessing biological states or processes during exercise and fatigue.

  14. Auditory excitation patterns : the significance of the pulsation threshold method for the measurement of auditory nonlinearity

    NARCIS (Netherlands)

    H. Verschuure (Hans)

    1978-01-01

    textabstractThe auditory system is the toto[ of organs that translates an acoustical signal into the perception of a sound. An acoustic signal is a vibration. It is decribed by physical parameters. The perception of sound is the awareness of a signal being present and the attribution of certain qual

  15. Development of auditory localization accuracy and auditory spatial discrimination in children and adolescents.

    Science.gov (United States)

    Kühnle, S; Ludwig, A A; Meuret, S; Küttner, C; Witte, C; Scholbach, J; Fuchs, M; Rübsamen, R

    2013-01-01

    The present study investigated the development of two parameters of spatial acoustic perception in children and adolescents with normal hearing, aged 6-18 years. Auditory localization accuracy was quantified by means of a sound source identification task and auditory spatial discrimination acuity by measuring minimum audible angles (MAA). Both low- and high-frequency noise bursts were employed in the tests, thereby separately addressing auditory processing based on interaural time and intensity differences. Setup consisted of 47 loudspeakers mounted in the frontal azimuthal hemifield, ranging from 90° left to 90° right (-90°, +90°). Target signals were presented from 8 loudspeaker positions in the left and right hemifields (±4°, ±30°, ±60° and ±90°). Localization accuracy and spatial discrimination acuity showed different developmental courses. Localization accuracy remained stable from the age of 6 onwards. In contrast, MAA thresholds and interindividual variability of spatial discrimination decreased significantly with increasing age. Across all age groups, localization was most accurate and MAA thresholds were lower for frontal than for lateral sound sources, and for low-frequency compared to high-frequency noise bursts. The study also shows better performance in spatial hearing based on interaural time differences rather than on intensity differences throughout development. These findings confirm that specific aspects of central auditory processing show continuous development during childhood up to adolescence.

  16. Effects of sequential streaming on auditory masking using psychoacoustics and auditory evoked potentials.

    Science.gov (United States)

    Verhey, Jesko L; Ernst, Stephan M A; Yasin, Ifat

    2012-03-01

    The present study was aimed at investigating the relationship between the mismatch negativity (MMN) and psychoacoustical effects of sequential streaming on comodulation masking release (CMR). The influence of sequential streaming on CMR was investigated using a psychoacoustical alternative forced-choice procedure and electroencephalography (EEG) for the same group of subjects. The psychoacoustical data showed, that adding precursors comprising of only off-signal-frequency maskers abolished the CMR. Complementary EEG data showed an MMN irrespective of the masker envelope correlation across frequency when only the off-signal-frequency masker components were present. The addition of such precursors promotes a separation of the on- and off-frequency masker components into distinct auditory objects preventing the auditory system from using comodulation as an additional cue. A frequency-specific adaptation changing the representation of the flanking bands in the streaming conditions may also contribute to the reduction of CMR in the stream conditions, however, it is unlikely that adaptation is the primary reason for the streaming effect. A neurophysiological correlate of sequential streaming was found in EEG data using MMN, but the magnitude of the MMN was not correlated with the audibility of the signal in CMR experiments. Dipole source analysis indicated different cortical regions involved in processing auditory streaming and modulation detection. In particular, neural sources for processing auditory streaming include cortical regions involved in decision-making.

  17. Fatigue crack growth detect, assess, avoid

    CERN Document Server

    Richard, Hans Albert

    2016-01-01

    This book offers a concise introduction to fatigue crack growth, based on practical examples. It discusses the essential concepts of fracture mechanics, fatigue crack growth under constant and variable amplitude loading and the determination of the fracture-mechanical material parameters. The book also introduces the analytical and numerical simulation of fatigue crack growth as well as crack initiation. It concludes with a detailed description of several practical case studies and some exercises. The target group includes graduate students, researchers at universities and practicing engineers.

  18. Modified low-cycle fatigue (LCF test

    Directory of Open Access Journals (Sweden)

    M. Maj

    2015-01-01

    Full Text Available The fatigue test results obtained by the common low-cycle fatigue test (LCF and its modified MLCF counterpart were presented. A satisfactory agreement of results was achieved for the two selected materials. With the MLCF method it is possible to examine from ten to twenty parameters using one single sample only. These parameters characterise the tested material in terms of its mechanical properties under the conditions of mechanical loads. Simultaneously, the study shows the implementation of the modified low-cycle fatigue test in practice.

  19. Corrosion Fatigue in District Heating Water Tanks

    DEFF Research Database (Denmark)

    Maahn, Ernst Emanuel

    1996-01-01

    Three candidate materials for construction of buffer tanks for district heating water have been tested for corrosion fatigue properties in a district heating water environment. The investigation included Slow Strain Rate Testing of plain tensile specimens, crack initiation testing by corrosion...... fatigue of plain tensile specimens and crack growth rate determination for Compact Tensile Specimens under corrosion fatigue conditions. The three materials are equal with respect to stress corrosion sensibility and crack initiation. Crack growth rate is increased with a factor of 4-6 relative to an inert...

  20. SEAFARER FATIGUE: A REVIEW OF RISK FACTORS

    DEFF Research Database (Denmark)

    Jepsen, Jørgen Riis; Zhao, Zhiwei; Tu, Mingshan;

    2016-01-01

    Background: The widespread occurrence of fatigue in the maritime industry and the consequences for the health and safety of seafarers have caused concern, and indicates the importance of research into risk factors at sea. This review gives an overview of the currently recognized key determinants...... of seafarer fatigue. Methods: A literature study was conducted aiming to collect publications that address work-related risk factors for fatigue. Due to the limited number of publications that deals with seafarers, experiences from other populations sharing the same exposures (e.g. shift work) were also...

  1. System for estimating fatigue damage

    Energy Technology Data Exchange (ETDEWEB)

    LeMonds, Jeffrey; Guzzo, Judith Ann; Liu, Shaopeng; Dani, Uttara Ashwin

    2017-03-14

    In one aspect, a system for estimating fatigue damage in a riser string is provided. The system includes a plurality of accelerometers which can be deployed along a riser string and a communications link to transmit accelerometer data from the plurality of accelerometers to one or more data processors in real time. With data from a limited number of accelerometers located at sensor locations, the system estimates an optimized current profile along the entire length of the riser including riser locations where no accelerometer is present. The optimized current profile is then used to estimate damage rates to individual riser components and to update a total accumulated damage to individual riser components. The number of sensor locations is small relative to the length of a deepwater riser string, and a riser string several miles long can be reliably monitored along its entire length by fewer than twenty sensor locations.

  2. Does Corruption Cause Aid Fatigue?

    DEFF Research Database (Denmark)

    Bauhr, Monika; Charron, Nicholas; Nasiritousi, Naghmeh

    2013-01-01

    Does perceived corruption in recipient countries reduce support for foreign aid in donor countries? This under-explored yet salient question is examined using the 2009 Eurobarometer survey for the 27 EU countries. We suggest that perceived corruption can cause aid fatigue but that this relationship...... is highly contextualized. The results show that perceptions about corruption in developing countries reduce overall support for aid among respondents in donor countries. However, this effect is mitigated by country and contextual-level effects and different understandings of what we call the “aid-corruption...... paradox,” namely that the need for foreign aid is often the greatest in corrupt environments. Three different dynamics of the aid-corruption paradox influence support for aid: moral, pragmatic, and strategic understandings. In EU-15 countries, the effect of perceived corruption in recipient states on aid...

  3. Muscle glycogen stores and fatigue

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Westerblad, Håkan; Nielsen, Joachim

    2013-01-01

      Studies performed at the beginning of the last century revealed the importance of carbohydrate as a fuel during exercise, and the importance of muscle glycogen on performance has subsequently been confirmed in numerous studies. However, the link between glycogen depletion and impaired muscle...... function during fatigue is not well understood and a direct cause-and-effect relationship between glycogen and muscle function remains to be established. The use of electron microscopy has revealed that glycogen is not homogeneously distributed in skeletal muscle fibres, but rather localized in distinct...... pools. Furthermore, each glycogen granule has its own metabolic machinery with glycolytic enzymes and regulating proteins. One pool of such glycogenolytic complexes is localized within the myofibrils in close contact with key proteins involved in the excitation-contraction coupling and Ca2+ release from...

  4. Time computations in anuran auditory systems

    Directory of Open Access Journals (Sweden)

    Gary J Rose

    2014-05-01

    Full Text Available Temporal computations are important in the acoustic communication of anurans. In many cases, calls between closely related species are nearly identical spectrally but differ markedly in temporal structure. Depending on the species, calls can differ in pulse duration, shape and/or rate (i.e., amplitude modulation, direction and rate of frequency modulation, and overall call duration. Also, behavioral studies have shown that anurans are able to discriminate between calls that differ in temporal structure. In the peripheral auditory system, temporal information is coded primarily in the spatiotemporal patterns of activity of auditory-nerve fibers. However, major transformations in the representation of temporal information occur in the central auditory system. In this review I summarize recent advances in understanding how temporal information is represented in the anuran midbrain, with particular emphasis on mechanisms that underlie selectivity for pulse duration and pulse rate (i.e., intervals between onsets of successive pulses. Two types of neurons have been identified that show selectivity for pulse rate: long-interval cells respond well to slow pulse rates but fail to spike or respond phasically to fast pulse rates; conversely, interval-counting neurons respond to intermediate or fast pulse rates, but only after a threshold number of pulses, presented at optimal intervals, have occurred. Duration-selectivity is manifest as short-pass, band-pass or long-pass tuning. Whole-cell patch recordings, in vivo, suggest that excitation and inhibition are integrated in diverse ways to generate temporal selectivity. In many cases, activity-related enhancement or depression of excitatory or inhibitory processes appear to contribute to selective responses.

  5. Fatigue Test Design: Scenarios for Biaxial Fatigue Testing of a 60-Meter Wind Turbine Blade

    Energy Technology Data Exchange (ETDEWEB)

    Post, Nathan [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-07-01

    Current practice in commercial certification of wind turbine blades is to perform separate flap and lead-lag fatigue tests. The National Renewable Energy Laboratory has been researching and evaluating biaxial fatigue testing techniques and demonstrating various options, typically on smaller-scale test articles at the National Wind Technology Center. This report evaluates some of these biaxial fatigue options in the context of application to a multimegawatt blade certification test program at the Wind Technology Testing Center in Charlestown, Massachusetts.

  6. The Corrosion Fatigue Properties of High Performance Concrete

    Institute of Scientific and Technical Information of China (English)

    CHEN Shuanfa; ZHENG Mulian; LIAO Weidong; WANG Binggang

    2005-01-01

    With the loading test equipment of corrosion fatigue specially designed, the corrosion fatigue characteristics of high performance concrete (HPC) withstanding the interaction of third point fatigue loading and Na2SO4 solution were investigated and analyzed. The experimental results indicate that water-binder ratio evidently influences the corrosion fatigue characteristics of HPC, and a moderate quantitative fine mineral admixture enhances the corrosion fatigue resistance of HPC. The effect is more significant when fly ash and silica fume are added.

  7. From ear to hand: the role of the auditory-motor loop in pointing to an auditory source

    Directory of Open Access Journals (Sweden)

    Eric Olivier Boyer

    2013-04-01

    Full Text Available Studies of the nature of the neural mechanisms involved in goal-directed movements tend to concentrate on the role of vision. We present here an attempt to address the mechanisms whereby an auditory input is transformed into a motor command. The spatial and temporal organization of hand movements were studied in normal human subjects as they pointed towards unseen auditory targets located in a horizontal plane in front of them. Positions and movements of the hand were measured by a six infrared camera tracking system. In one condition, we assessed the role of auditory information about target position in correcting the trajectory of the hand. To accomplish this, the duration of the target presentation was varied. In another condition, subjects received continuous auditory feedback of their hand movement while pointing to the auditory targets. Online auditory control of the direction of pointing movements was assessed by evaluating how subjects reacted to shifts in heard hand position. Localization errors were exacerbated by short duration of target presentation but not modified by auditory feedback of hand position. Long duration of target presentation gave rise to a higher level of accuracy and was accompanied by early automatic head orienting movements consistently related to target direction. These results highlight the efficiency of auditory feedback processing in online motor control and suggest that the auditory system takes advantages of dynamic changes of the acoustic cues due to changes in head orientation in order to process online motor control. How to design an informative acoustic feedback needs to be carefully studied to demonstrate that auditory feedback of the hand could assist the monitoring of movements directed at objects in auditory space.

  8. From ear to hand: the role of the auditory-motor loop in pointing to an auditory source

    Science.gov (United States)

    Boyer, Eric O.; Babayan, Bénédicte M.; Bevilacqua, Frédéric; Noisternig, Markus; Warusfel, Olivier; Roby-Brami, Agnes; Hanneton, Sylvain; Viaud-Delmon, Isabelle

    2013-01-01

    Studies of the nature of the neural mechanisms involved in goal-directed movements tend to concentrate on the role of vision. We present here an attempt to address the mechanisms whereby an auditory input is transformed into a motor command. The spatial and temporal organization of hand movements were studied in normal human subjects as they pointed toward unseen auditory targets located in a horizontal plane in front of them. Positions and movements of the hand were measured by a six infrared camera tracking system. In one condition, we assessed the role of auditory information about target position in correcting the trajectory of the hand. To accomplish this, the duration of the target presentation was varied. In another condition, subjects received continuous auditory feedback of their hand movement while pointing to the auditory targets. Online auditory control of the direction of pointing movements was assessed by evaluating how subjects reacted to shifts in heard hand position. Localization errors were exacerbated by short duration of target presentation but not modified by auditory feedback of hand position. Long duration of target presentation gave rise to a higher level of accuracy and was accompanied by early automatic head orienting movements consistently related to target direction. These results highlight the efficiency of auditory feedback processing in online motor control and suggest that the auditory system takes advantages of dynamic changes of the acoustic cues due to changes in head orientation in order to process online motor control. How to design an informative acoustic feedback needs to be carefully studied to demonstrate that auditory feedback of the hand could assist the monitoring of movements directed at objects in auditory space. PMID:23626532

  9. Multiprofessional committee on auditory health: COMUSA.

    Science.gov (United States)

    Lewis, Doris Ruthy; Marone, Silvio Antonio Monteiro; Mendes, Beatriz C A; Cruz, Oswaldo Laercio Mendonça; Nóbrega, Manoel de

    2010-01-01

    Created in 2007, COMUSA is a multiprofessional committee comprising speech therapy, otology, otorhinolaryngology and pediatrics with the aim of debating and countersigning auditory health actions for neonatal, lactating, preschool and school children, adolescents, adults and elderly persons. COMUSA includes representatives of the Brazilian Audiology Academy (Academia Brasileira de Audiologia or ABA), the Brazilian Otorhinolaryngology and Cervicofacial Surgery Association (Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico Facial or ABORL), the Brazilian Phonoaudiology Society (Sociedade Brasileira de Fonoaudiologia or SBFa), the Brazilian Otology Society (Sociedade Brasileira de Otologia or SBO), and the Brazilian Pediatrics Society (Sociedade Brasileira de Pediatria or SBP).

  10. Musical and auditory hallucinations: A spectrum.

    Science.gov (United States)

    E Fischer, Corinne; Marchie, Anthony; Norris, Mireille

    2004-02-01

    Musical hallucinosis is a rare and poorly understood clinical phenomenon. While an association appears to exist between this phenomenon and organic brain pathology, aging and sensory impairment the precise association remains unclear. The authors present two cases of musical hallucinosis, both in elderly patients with mild-moderate cognitive impairment and mild-moderate hearing loss, who subsequently developed auditory hallucinations and in one case command hallucinations. The literature in reference to musical hallucinosis will be reviewed and a theory relating to the development of musical hallucinations will be proposed.

  11. Cancer of the external auditory canal

    DEFF Research Database (Denmark)

    Nyrop, Mette; Grøntved, Aksel

    2002-01-01

    OBJECTIVE: To evaluate the outcome of surgery for cancer of the external auditory canal and relate this to the Pittsburgh staging system used both on squamous cell carcinoma and non-squamous cell carcinoma. DESIGN: Retrospective case series of all patients who had surgery between 1979 and 2000....... PATIENTS: Ten women and 10 men with previously untreated primary cancer. Median age at diagnosis was 67 years (range, 31-87 years). Survival data included 18 patients with at least 2 years of follow-up or recurrence. INTERVENTION: Local canal resection or partial temporal bone resection. MAIN OUTCOME...

  12. CAVERNOUS HEMANGIOMA OF THE INTERNAL AUDITORY CANAL

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Hekmatara

    1993-06-01

    Full Text Available Cavernous hemangioma is a rare benign tumor of the internal auditory canal (IAC of which fourteen cases have been reported so far."nTinnitus and progressive sensorineural hearing loss (SNHL are the chief complaints of the patients. Audiological and radiological planes, CTScan, and magnetic resonance image (MRI studies are helpful in diagnosis. The only choice of treatment is surgery with elective transmastoid trans¬labyrinthine approach. And if tumor is very large, the method of choice will be retrosigmoid approach.

  13. PLASTICITY IN THE ADULT CENTRAL AUDITORY SYSTEM.

    Science.gov (United States)

    Irvine, Dexter R F; Fallon, James B; Kamke, Marc R

    2006-04-01

    The central auditory system retains into adulthood a remarkable capacity for plastic changes in the response characteristics of single neurons and the functional organization of groups of neurons. The most dramatic examples of this plasticity are provided by changes in frequency selectivity and organization as a consequence of either partial hearing loss or procedures that alter the significance of particular frequencies for the organism. Changes in temporal resolution are also seen as a consequence of altered experience. These forms of plasticity are likely to contribute to the improvements exhibited by cochlear implant users in the post-implantation period.

  14. PLASTICITY IN THE ADULT CENTRAL AUDITORY SYSTEM

    Science.gov (United States)

    Irvine, Dexter R. F.; Fallon, James B.; Kamke, Marc R.

    2007-01-01

    The central auditory system retains into adulthood a remarkable capacity for plastic changes in the response characteristics of single neurons and the functional organization of groups of neurons. The most dramatic examples of this plasticity are provided by changes in frequency selectivity and organization as a consequence of either partial hearing loss or procedures that alter the significance of particular frequencies for the organism. Changes in temporal resolution are also seen as a consequence of altered experience. These forms of plasticity are likely to contribute to the improvements exhibited by cochlear implant users in the post-implantation period. PMID:17572797

  15. Comparison of auditory hallucinations across different disorders and syndromes

    NARCIS (Netherlands)

    Sommer, Iris E. C.; Koops, Sanne; Blom, Jan Dirk

    2012-01-01

    Auditory hallucinations can be experienced in the context of many different disorders and syndromes. The differential diagnosis basically rests on the presence or absence of accompanying symptoms. In terms of clinical relevance, the most important distinction to be made is between auditory hallucina

  16. Development of a central auditory test battery for adults.

    NARCIS (Netherlands)

    Neijenhuis, C.A.M.; Stollman, M.H.P.; Snik, A.F.M.; Broek, P. van den

    2001-01-01

    There is little standardized test material in Dutch to document central auditory processing disorders (CAPDs). Therefore, a new central auditory test battery was composed and standardized for use with adult populations and older children. The test battery comprised seven tests (words in noise, filte

  17. Deactivation of the Parahippocampal Gyrus Preceding Auditory Hallucinations in Schizophrenia

    NARCIS (Netherlands)

    Diederen, Kelly M. J.; Neggers, Sebastiaan F. W.; Daalman, Kirstin; Blom, Jan Dirk; Goekoop, Rutger; Kahn, Rene S.; Sommer, Iris E. C.

    2010-01-01

    Objective: Activation in a network of language-related regions has been reported during auditory verbal hallucinations. It remains unclear, however, how this activation is triggered. Identifying brain regions that show significant signal changes preceding auditory hallucinations might reveal the ori

  18. Impact of Educational Level on Performance on Auditory Processing Tests.

    Science.gov (United States)

    Murphy, Cristina F B; Rabelo, Camila M; Silagi, Marcela L; Mansur, Letícia L; Schochat, Eliane

    2016-01-01

    Research has demonstrated that a higher level of education is associated with better performance on cognitive tests among middle-aged and elderly people. However, the effects of education on auditory processing skills have not yet been evaluated. Previous demonstrations of sensory-cognitive interactions in the aging process indicate the potential importance of this topic. Therefore, the primary purpose of this study was to investigate the performance of middle-aged and elderly people with different levels of formal education on auditory processing tests. A total of 177 adults with no evidence of cognitive, psychological or neurological conditions took part in the research. The participants completed a series of auditory assessments, including dichotic digit, frequency pattern and speech-in-noise tests. A working memory test was also performed to investigate the extent to which auditory processing and cognitive performance were associated. The results demonstrated positive but weak correlations between years of schooling and performance on all of the tests applied. The factor "years of schooling" was also one of the best predictors of frequency pattern and speech-in-noise test performance. Additionally, performance on the working memory, frequency pattern and dichotic digit tests was also correlated, suggesting that the influence of educational level on auditory processing performance might be associated with the cognitive demand of the auditory processing tests rather than auditory sensory aspects itself. Longitudinal research is required to investigate the causal relationship between educational level and auditory processing skills.

  19. Auditory Processing Theories of Language Disorders: Past, Present, and Future

    Science.gov (United States)

    Miller, Carol A.

    2011-01-01

    Purpose: The purpose of this article is to provide information that will assist readers in understanding and interpreting research literature on the role of auditory processing in communication disorders. Method: A narrative review was used to summarize and synthesize the literature on auditory processing deficits in children with auditory…

  20. Source reliability in auditory health persuasion : Its antecedents and consequences

    NARCIS (Netherlands)

    Elbert, Sarah P.; Dijkstra, Arie

    2015-01-01

    Persuasive health messages can be presented through an auditory channel, thereby enhancing the salience of the source, making it fundamentally different from written or pictorial information. We focused on the determinants of perceived source reliability in auditory health persuasion by investigatin

  1. Preparation and Culture of Chicken Auditory Brainstem Slices

    OpenAIRE

    Sanchez, Jason T.; Seidl, Armin H.; Rubel, Edwin W; Barria, Andres

    2011-01-01

    The chicken auditory brainstem is a well-established model system that has been widely used to study the anatomy and physiology of auditory processing at discreet periods of development 1-4 as well as mechanisms for temporal coding in the central nervous system 5-7.

  2. Strategy choice mediates the link between auditory processing and spelling.

    Science.gov (United States)

    Kwong, Tru E; Brachman, Kyle J

    2014-01-01

    Relations among linguistic auditory processing, nonlinguistic auditory processing, spelling ability, and spelling strategy choice were examined. Sixty-three undergraduate students completed measures of auditory processing (one involving distinguishing similar tones, one involving distinguishing similar phonemes, and one involving selecting appropriate spellings for individual phonemes). Participants also completed a modified version of a standardized spelling test, and a secondary spelling test with retrospective strategy reports. Once testing was completed, participants were divided into phonological versus nonphonological spellers on the basis of the number of words they spelled using phonological strategies only. Results indicated a) moderate to strong positive correlations among the different auditory processing tasks in terms of reaction time, but not accuracy levels, and b) weak to moderate positive correlations between measures of linguistic auditory processing (phoneme distinction and phoneme spelling choice in the presence of foils) and spelling ability for phonological spellers, but not for nonphonological spellers. These results suggest a possible explanation for past contradictory research on auditory processing and spelling, which has been divided in terms of whether or not disabled spellers seemed to have poorer auditory processing than did typically developing spellers, and suggest implications for teaching spelling to children with good versus poor auditory processing abilities.

  3. Entrainment to an auditory signal: Is attention involved?

    NARCIS (Netherlands)

    Kunert, R.; Jongman, S.R.

    2017-01-01

    Many natural auditory signals, including music and language, change periodically. The effect of such auditory rhythms on the brain is unclear however. One widely held view, dynamic attending theory, proposes that the attentional system entrains to the rhythm and increases attention at moments of rhy

  4. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    Science.gov (United States)

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  5. Auditory signal design for automatic number plate recognition system

    NARCIS (Netherlands)

    Heydra, C.G.; Jansen, R.J.; Van Egmond, R.

    2014-01-01

    This paper focuses on the design of an auditory signal for the Automatic Number Plate Recognition system of Dutch national police. The auditory signal is designed to alert police officers of suspicious cars in their proximity, communicating priority level and location of the suspicious car and takin

  6. Modeling auditory evoked brainstem responses to transient stimuli

    DEFF Research Database (Denmark)

    Rønne, Filip Munch; Dau, Torsten; Harte, James;

    2012-01-01

    A quantitative model is presented that describes the formation of auditory brainstem responses (ABR) to tone pulses, clicks and rising chirps as a function of stimulation level. The model computes the convolution of the instantaneous discharge rates using the “humanized” nonlinear auditory-nerve ...

  7. Tinnitus intensity dependent gamma oscillations of the contralateral auditory cortex.

    Directory of Open Access Journals (Sweden)

    Elsa van der Loo

    Full Text Available BACKGROUND: Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. METHODS AND FINDINGS: In unilateral tinnitus patients (N = 15; 10 right, 5 left source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05. CONCLUSION: Auditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception.

  8. Functional outcome of auditory implants in hearing loss.

    Science.gov (United States)

    Di Girolamo, S; Saccoccio, A; Giacomini, P G; Ottaviani, F

    2007-01-01

    The auditory implant provides a new mechanism for hearing when a hearing aid is not enough. It is the only medical technology able to functionally restore a human sense i.e. hearing. The auditory implant is very different from a hearing aid. Hearing aids amplify sound. Auditory implants compensate for damaged or non-working parts of the inner ear because they can directly stimulate the acoustic nerve. There are two principal types of auditory implant: the cochlear implant and the auditory brainstem implant. They have common basic characteristics, but different applications. A cochlear implant attempts to replace a function lost by the cochlea, usually due to an absence of functioning hair cells; the auditory brainstem implant (ABI) is a modification of the cochlear implant, in which the electrode array is placed directly into the brain when the acoustic nerve is not anymore able to carry the auditory signal. Different types of deaf or severely hearing-impaired patients choose auditory implants. Both children and adults can be candidates for implants. The best age for implantation is still being debated, but most children who receive implants are between 2 and 6 years old. Earlier implantation seems to perform better thanks to neural plasticity. The decision to receive an implant should involve a discussion with many medical specialists and an experienced surgeon.

  9. Auditory Processing Learning Disability, Suicidal Ideation, and Transformational Faith

    Science.gov (United States)

    Bailey, Frank S.; Yocum, Russell G.

    2015-01-01

    The purpose of this personal experience as a narrative investigation is to describe how an auditory processing learning disability exacerbated--and how spirituality and religiosity relieved--suicidal ideation, through the lived experiences of an individual born and raised in the United States. The study addresses: (a) how an auditory processing…

  10. Functional sex differences in human primary auditory cortex

    NARCIS (Netherlands)

    Ruytjens, Liesbet; Georgiadis, Janniko R.; Holstege, Gert; Wit, Hero P.; Albers, Frans W. J.; Willemsen, Antoon T. M.

    2007-01-01

    Background We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a bas

  11. Auditory Dysfunction and Its Communicative Impact in the Classroom.

    Science.gov (United States)

    Friedrich, Brad W.

    1982-01-01

    The origins and nature of auditory dysfunction in school age children and the role of the audiologist in the evaluation of the learning disabled child are reviewed. Specific structures and mechanisms responsible for the reception and perception of auditory signals are specified. (Author/SEW)

  12. Auditory perceptual simulation: Simulating speech rates or accents?

    Science.gov (United States)

    Zhou, Peiyun; Christianson, Kiel

    2016-07-01

    When readers engage in Auditory Perceptual Simulation (APS) during silent reading, they mentally simulate characteristics of voices attributed to a particular speaker or a character depicted in the text. Previous research found that auditory perceptual simulation of a faster native English speaker during silent reading led to shorter reading times that auditory perceptual simulation of a slower non-native English speaker. Yet, it was uncertain whether this difference was triggered by the different speech rates of the speakers, or by the difficulty of simulating an unfamiliar accent. The current study investigates this question by comparing faster Indian-English speech and slower American-English speech in the auditory perceptual simulation paradigm. Analyses of reading times of individual words and the full sentence reveal that the auditory perceptual simulation effect again modulated reading rate, and auditory perceptual simulation of the faster Indian-English speech led to faster reading rates compared to auditory perceptual simulation of the slower American-English speech. The comparison between this experiment and the data from Zhou and Christianson (2016) demonstrate further that the "speakers'" speech rates, rather than the difficulty of simulating a non-native accent, is the primary mechanism underlying auditory perceptual simulation effects.

  13. Use of auditory learning to manage listening problems in children.

    Science.gov (United States)

    Moore, David R; Halliday, Lorna F; Amitay, Sygal

    2009-02-12

    This paper reviews recent studies that have used adaptive auditory training to address communication problems experienced by some children in their everyday life. It considers the auditory contribution to developmental listening and language problems and the underlying principles of auditory learning that may drive further refinement of auditory learning applications. Following strong claims that language and listening skills in children could be improved by auditory learning, researchers have debated what aspect of training contributed to the improvement and even whether the claimed improvements reflect primarily a retest effect on the skill measures. Key to understanding this research have been more circumscribed studies of the transfer of learning and the use of multiple control groups to examine auditory and non-auditory contributions to the learning. Significant auditory learning can occur during relatively brief periods of training. As children mature, their ability to train improves, but the relation between the duration of training, amount of learning and benefit remains unclear. Individual differences in initial performance and amount of subsequent learning advocate tailoring training to individual learners. The mechanisms of learning remain obscure, especially in children, but it appears that the development of cognitive skills is of at least equal importance to the refinement of sensory processing. Promotion of retention and transfer of learning are major goals for further research.

  14. Auditory Backward Masking Deficits in Children with Reading Disabilities

    Science.gov (United States)

    Montgomery, Christine R.; Morris, Robin D.; Sevcik, Rose A.; Clarkson, Marsha G.

    2005-01-01

    Studies evaluating temporal auditory processing among individuals with reading and other language deficits have yielded inconsistent findings due to methodological problems (Studdert-Kennedy & Mody, 1995) and sample differences. In the current study, seven auditory masking thresholds were measured in fifty-two 7- to 10-year-old children (26…

  15. A Pilot Study of Auditory Integration Training in Autism.

    Science.gov (United States)

    Rimland, Bernard; Edelson, Stephen M.

    1995-01-01

    The effectiveness of Auditory Integration Training (AIT) in 8 autistic individuals (ages 4-21) was evaluated using repeated multiple criteria assessment over a 3-month period. Compared to matched controls, subjects' scores improved on the Aberrant Behavior Checklist and Fisher's Auditory Problems Checklist. AIT did not decrease sound sensitivity.…

  16. Quantification of the auditory startle reflex in children

    NARCIS (Netherlands)

    Bakker, Mirte J.; Boer, Frits; van der Meer, Johan N.; Koelman, Johannes H. T. M.; Boeree, Thijs; Bour, Lo; Tijssen, Marina A. J.

    2009-01-01

    Objective: To find an adequate tool to assess the auditory startle reflex (ASR) in children. Methods: We investigated the effect of stimulus repetition, gender and age on several quantifications of the ASR. ASR's were elicited by eight consecutive auditory stimuli in 27 healthy children. Electromyog

  17. Auditory and visual spatial impression: Recent studies of three auditoria

    Science.gov (United States)

    Nguyen, Andy; Cabrera, Densil

    2004-10-01

    Auditory spatial impression is widely studied for its contribution to auditorium acoustical quality. By contrast, visual spatial impression in auditoria has received relatively little attention in formal studies. This paper reports results from a series of experiments investigating the auditory and visual spatial impression of concert auditoria. For auditory stimuli, a fragment of an anechoic recording of orchestral music was convolved with calibrated binaural impulse responses, which had been made with the dummy head microphone at a wide range of positions in three auditoria and the sound source on the stage. For visual stimuli, greyscale photographs were used, taken at the same positions in the three auditoria, with a visual target on the stage. Subjective experiments were conducted with auditory stimuli alone, visual stimuli alone, and visual and auditory stimuli combined. In these experiments, subjects rated apparent source width, listener envelopment, intimacy and source distance (auditory stimuli), and spaciousness, envelopment, stage dominance, intimacy and target distance (visual stimuli). Results show target distance to be of primary importance in auditory and visual spatial impression-thereby providing a basis for covariance between some attributes of auditory and visual spatial impression. Nevertheless, some attributes of spatial impression diverge between the senses.

  18. Linking topography to tonotopy in the mouse auditory thalamocortical circuit

    DEFF Research Database (Denmark)

    Hackett, Troy A; Rinaldi Barkat, Tania; O'Brien, Barbara M J;

    2011-01-01

    The mouse sensory neocortex is reported to lack several hallmark features of topographic organization such as ocular dominance and orientation columns in primary visual cortex or fine-scale tonotopy in primary auditory cortex (AI). Here, we re-examined the question of auditory functional topography...

  19. Perceptual Load Influences Auditory Space Perception in the Ventriloquist Aftereffect

    Science.gov (United States)

    Eramudugolla, Ranmalee; Kamke, Marc. R.; Soto-Faraco, Salvador; Mattingley, Jason B.

    2011-01-01

    A period of exposure to trains of simultaneous but spatially offset auditory and visual stimuli can induce a temporary shift in the perception of sound location. This phenomenon, known as the "ventriloquist aftereffect", reflects a realignment of auditory and visual spatial representations such that they approach perceptual alignment despite their…

  20. Fatigue and radiotherapy. A literature review; Fatigue et radiotherapie. Revue de la litterature

    Energy Technology Data Exchange (ETDEWEB)

    Dilhuydy, J.M.; Ouhtatou, F.; Laporte, C.; Nguyen, T.V.F.; Vendrely, V. [Institut Bergonie Centre Regional de Lutte Contre le Cancer, 33 - Bordeaux (France); Dilhuydy, J.M. [Federation Nationale des Centres de Lutte Contre le Cancer, FNCLCC, Groupe Rehabilitation, 75 - Paris (France); Dilhuydy, M.S. [Hopital Saint-Andre, Service de Medecine Interne, 33 - Bordeaux (France)

    2001-11-01

    Fatigue is a common complaint for the cancer patient during and after radiotherapy, according to the published studies. Fatigue is a subjective symptom mostly underestimated by oncologists and other care givers. Etiology is complex, poorly understood in spite of obvious causes like insomnia, nausea, pain, depression, psychological distress, anemia, hypothyroidism, menopause disturbances, treatment adverse effects. Fatigue presents multi-factorial and multidimensional aspects. To evaluate it, many tools can be used as single-item, unidimensional and multidimensional instruments. Practically, the open discussion with the patient throughout radiotherapy is essential to define it. Taking charge fatigue requires its acknowledgement by radiotherapist, treatment of associated symptoms with a multidisciplinary approach. (authors)

  1. Neural effect of mental fatigue on physical fatigue: a magnetoencephalography study.

    Science.gov (United States)

    Tanaka, Masaaki; Ishii, Akira; Watanabe, Yasuyoshi

    2014-01-13

    We sought to clarify the neural effect of mental fatigue on physical fatigue using magnetoencephalography (MEG) and classical conditioning techniques. Eleven right-handed volunteers participated in this study. On the first day, participants performed fatigue-inducing maximum handgrip trials for 10 min; metronome sounds were started 5 min after the beginning of the trials. We used metronome sounds as conditioned stimuli and maximum handgrip trials as unconditioned stimuli to cause physical fatigue. On the next day, MEG recordings during the imagery of maximum grips of the right hand guided by the metronome sounds were performed for 10 min just before (control session) and after (mental fatigue session) a 30-min fatigue-inducing mental task session. In the right anterior cingulate cortex (Brodmann's area 23), the alpha-band event-related synchronization of the mental fatigue session relative to the control session within the time window of 500–600 ms after the onset of handgrip cue sounds was identified. We demonstrated that mental fatigue suppresses activities in the right anterior cingulate cortex during physical fatigue.

  2. Investigation and analysis on fatigue status of military pilots

    Directory of Open Access Journals (Sweden)

    Jian-sheng GUO

    2012-03-01

    Full Text Available Objective To investigate the fatigue status and its characteristics and influential factors of military pilots. Methods Questionnaire survey was conducted on 924 military pilots by using Fatigue Assessment Instrument (FAI and Fatigue Scale (FS-14, χ2 test and Pearson correlation analysis were performed on the data results with SPSS 17.0 software. Results The findings of fatigue status indicated 343 subjects (37.1% with positive fatigue symptoms and 581 subjects (62.9% with negative fatigue symptoms. FAI factor 1 (severity of fatigue, factor 2 (mental fatigue factor, factor 3 (consequence of fatique and the total score, FS-14 factor 1 (physical fatigue factor and the total score in fatigue-positive group were all higher than those in fatiguenegative group, and the differences were all statistically significant (P 0.05 in the possibility of developing fatigue symptoms between subjects with different aircraft types. Age and flight time were positively correlated with factor 1 and total score in FAI and factor 1, factor 2 and total score in FS-14. However, the aircraft type was associated with neither the individual factors and total score in FAI nor the individual factors and total score in FS-14. Conclusion It is common for military pilots to develop fatigue symptoms, characterized by obvious manifestations of severity, environmental specificity, consequences of fatigue and physical fatigue, and the possibilities of developing fatigue symptoms for different ages and flight time were different.

  3. Across frequency processes involved in auditory detection of coloration

    DEFF Research Database (Denmark)

    Buchholz, Jörg; Kerketsos, P

    2008-01-01

    When an early wall reflection is added to a direct sound, a spectral modulation is introduced to the signal's power spectrum. This spectral modulation typically produces an auditory sensation of coloration or pitch. Throughout this study, auditory spectral-integration effects involved in coloration...... detection are investigated. Coloration detection thresholds were therefore measured as a function of reflection delay and stimulus bandwidth. In order to investigate the involved auditory mechanisms, an auditory model was employed that was conceptually similar to the peripheral weighting model [Yost, JASA......, 1982, 416-425]. When a “classical” gammatone filterbank was applied within this spectrum-based model, the model largely underestimated human performance at high signal frequencies. However, this limitation could be resolved by employing an auditory filterbank with narrower filters. This novel...

  4. Temporal expectation weights visual signals over auditory signals.

    Science.gov (United States)

    Menceloglu, Melisa; Grabowecky, Marcia; Suzuki, Satoru

    2017-04-01

    Temporal expectation is a process by which people use temporally structured sensory information to explicitly or implicitly predict the onset and/or the duration of future events. Because timing plays a critical role in crossmodal interactions, we investigated how temporal expectation influenced auditory-visual interaction, using an auditory-visual crossmodal congruity effect as a measure of crossmodal interaction. For auditory identification, an incongruent visual stimulus produced stronger interference when the crossmodal stimulus was presented with an expected rather than an unexpected timing. In contrast, for visual identification, an incongruent auditory stimulus produced weaker interference when the crossmodal stimulus was presented with an expected rather than an unexpected timing. The fact that temporal expectation made visual distractors more potent and visual targets less susceptible to auditory interference suggests that temporal expectation increases the perceptual weight of visual signals.

  5. Fatigue (PDQ®)—Health Professional Version

    Science.gov (United States)

    Expert-reviewed information summary about fatigue, a condition marked by extreme tiredness and inability to function because of lack of energy, often seen as a complication of cancer or its treatment.

  6. FATIGUE PROPERTIES OF SPRING REINFORCES POLYMER GEARS

    Directory of Open Access Journals (Sweden)

    Hilal CAN

    2005-03-01

    Full Text Available Failure of gears, occur surface pressure stress and fracture at base of teeth. For steel gears, it is known that process of carburizing increases fatigue strength. Internal stress on the surface increases of fracture fatigue strength. In this study fatigue properties of polypropylene gear reinforced with 1.2 mm wire diameter metallic springs was investigated. Extension springs were used as reinforcement element and placed into the mould and stretched before injection of polypropylene material into the mould. After injection of polypropylene, stretched springs were loosened in order to obtain pre-stressing. Fatigue tests were performed on the produced gear. Reinforcement increased the strength of gears. At result of experiments, pre-stressing increase in service life 12 times more than that of specimens without reinforcement.

  7. LIFE PREDICTION APPROACH FOR RANDOM MULTIAXIAL FATIGUE

    Institute of Scientific and Technical Information of China (English)

    Wang Lei; Wang Dejun

    2005-01-01

    According to the concept of critical plane, a life prediction approach for random multiaxial fatigue is presented. First, the critical plane under the multiaxial random loading is determined based on the concept of the weight-averaged maximum shear strain direction. Then the shear and normal strain histories on the determined critical plane are calculated and taken as the subject of multiaxial load simplifying and multiaxial cycle counting. Furthermore, a multiaxial fatigue life prediction model including the parameters resulted from multiaxial cycle counting is presented and applied to calculating the fatigue damage generated from each cycle. Finally, the cumulative damage is added up using Miner's linear rule, and the fatigue prediction life is given. The experiments under multiaxial loading blocks are used for the verification of the proposed method. The prediction has a good correction with the experimental results.

  8. Fatigue of stainless steel in hydrogen

    Science.gov (United States)

    Schuster, G.; Altstetter, C.

    1983-10-01

    The fatigue crack growth rates of two austenitic stainless steel alloys, AISI 301 and 302, were compared in air, argon, and hydrogen environments at atmospheric pressure and room temperature. Under the stresses at the crack tip the austenite in type 301 steel transformed martensitically to a’ to a greater extent than in type 302 steel. The steels were also tested in the cold worked condition under hydrogen or argon. Hydrogen was found to have a deleterious effect on both steels, but the effect was stronger in the unstable than in the stable alloy. Cold work decreased fatigue crack growth rates in argon and hydrogen, but the decrease was less marked in hydrogen than in argon. Metallographic, fractographic, and microhardness surveys in the vicinity of the fatigue crack were used to try to understand the reasons for the observed fatigue behavior.

  9. Recognising and combating compassion fatigue in nursing.

    Science.gov (United States)

    Mendes, Aysha

    In this monthly column, Aysha Mendes explores the reasons why nurses may feel compassion fatigue and ways NHS organisations and nurses themselves can engage in activities that will help them renew their emotional energy.

  10. Exercise Helps Counter Cancer-Linked Fatigue

    Science.gov (United States)

    ... similarly positive results, as did treatments that integrated exercise with mental health efforts. The team concluded that when it came to controlling cancer-related fatigue, the exercise and/or psychological therapy approaches appeared to outperform ...

  11. Human Muscle Fatigue Model in Dynamic Motions

    CERN Document Server

    Ma, Ruina; Bennis, Fouad; Ma, Liang

    2012-01-01

    Human muscle fatigue is considered to be one of the main reasons for Musculoskeletal Disorder (MSD). Recent models have been introduced to define muscle fatigue for static postures. However, the main drawbacks of these models are that the dynamic effect of the human and the external load are not taken into account. In this paper, each human joint is assumed to be controlled by two muscle groups to generate motions such as push/pull. The joint torques are computed using Lagrange's formulation to evaluate the dynamic factors of the muscle fatigue model. An experiment is defined to validate this assumption and the result for one person confirms its feasibility. The evaluation of this model can predict the fatigue and MSD risk in industry production quickly.

  12. Fatigue - corrosion of endoprosthesis titanium alloys.

    Science.gov (United States)

    Cornet, A; Muster, D; Jaeger, J H

    1979-01-01

    Commercial total hip prostheses often show certain metallurgical faults (porosities, coarse grains, growth dendrites, carbide networks). In order to investigate more accurately the role played by these different parameters in prostheses failure we performed a large number of systematic corrosion, fatigue and fatigue - corrosion tests on these materials and on commercial total hip prostheses. Ultimate strengthes seem to be reached for cast cobalt alloys, whereas titanium alloys, such as Ta 6 V, present very high fatigue limit under corrosion. Thus, rotative bending fatigue - corrosion tests in biological environment provide values about 50 DaN/mm2. This value, is nevertheless appreciably higher than those obtained with stellites and stainless steel. Titanium alloys, because of their mechanical performances, their weak Young's modulus (11000 DaN/mm2) and their relative lightness (4.5. g/cm3), which are associated with a good biocompatibility, seem very promising for permanent implants realisation.

  13. Formal auditory training in adult hearing aid users

    Directory of Open Access Journals (Sweden)

    Daniela Gil

    2010-01-01

    Full Text Available INTRODUCTION: Individuals with sensorineural hearing loss are often able to regain some lost auditory function with the help of hearing aids. However, hearing aids are not able to overcome auditory distortions such as impaired frequency resolution and speech understanding in noisy environments. The coexistence of peripheral hearing loss and a central auditory deficit may contribute to patient dissatisfaction with amplification, even when audiological tests indicate nearly normal hearing thresholds. OBJECTIVE: This study was designed to validate the effects of a formal auditory training program in adult hearing aid users with mild to moderate sensorineural hearing loss. METHODS: Fourteen bilateral hearing aid users were divided into two groups: seven who received auditory training and seven who did not. The training program was designed to improve auditory closure, figure-to-ground for verbal and nonverbal sounds and temporal processing (frequency and duration of sounds. Pre- and post-training evaluations included measuring electrophysiological and behavioral auditory processing and administration of the Abbreviated Profile of Hearing Aid Benefit (APHAB self-report scale. RESULTS: The post-training evaluation of the experimental group demonstrated a statistically significant reduction in P3 latency, improved performance in some of the behavioral auditory processing tests and higher hearing aid benefit in noisy situations (p-value < 0,05. No changes were noted for the control group (p-value <0,05. CONCLUSION: The results demonstrated that auditory training in adult hearing aid users can lead to a reduction in P3 latency, improvements in sound localization, memory for nonverbal sounds in sequence, auditory closure, figure-to-ground for verbal sounds and greater benefits in reverberant and noisy environments.

  14. The Effect of Gender on the N1-P2 Auditory Complex while Listening and Speaking with Altered Auditory Feedback

    Science.gov (United States)

    Swink, Shannon; Stuart, Andrew

    2012-01-01

    The effect of gender on the N1-P2 auditory complex was examined while listening and speaking with altered auditory feedback. Fifteen normal hearing adult males and 15 females participated. N1-P2 components were evoked while listening to self-produced nonaltered and frequency shifted /a/ tokens and during production of /a/ tokens during nonaltered…

  15. Middle components of the auditory evoked response in bilateral temporal lobe lesions. Report on a patient with auditory agnosia

    DEFF Research Database (Denmark)

    Parving, A; Salomon, G; Elberling, Claus

    1980-01-01

    An investigation of the middle components of the auditory evoked response (10--50 msec post-stimulus) in a patient with auditory agnosia is reported. Bilateral temporal lobe infarctions were proved by means of brain scintigraphy, CAT scanning, and regional cerebral blood flow measurements. The mi...

  16. Auditory Masking Effects on Speech Fluency in Apraxia of Speech and Aphasia: Comparison to Altered Auditory Feedback

    Science.gov (United States)

    Jacks, Adam; Haley, Katarina L.

    2015-01-01

    Purpose: To study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not…

  17. Cancer-related fatigue: central or peripheral?

    Science.gov (United States)

    Yavuzsen, Tugba; Davis, Mellar P; Ranganathan, Vinoth K; Walsh, Declan; Siemionow, Vlodek; Kirkova, Jordanka; Khoshknabi, Dilara; Lagman, Ruth; LeGrand, Susan; Yue, Guang H

    2009-10-01

    To evaluate cancer-related fatigue (CRF) by objective measurements to determine if CRF is a more centrally or peripherally mediated disorder, cancer patients and matched noncancer controls completed a Brief Fatigue Inventory (BFI) and underwent neuromuscular testing. Cancer patients had fatigue measured by the BFI, were off chemotherapy and radiation (for more than four weeks), had a hemoglobin level higher than 10 g/dL, and were neither receiving antidepressants nor were depressed on a screening question. The controls were screened for depression and matched by age, gender, and body mass index. Neuromuscular testing involved a sustained submaximal elbow flexion contraction (SC) at 30% maximal level (30% maximum elbow flexion force). Endurance time (ET) was measured from the beginning of the SC to the time when participants could not maintain the SC. Evoked twitch force (TF), a measure of muscle fatigue, and compound action potential (M-wave), an assessment of neuromuscular-junction transmission were performed during the SC. Compared with controls, the CRF group had a higher BFI score (Pcontrols, P<0.05). This indicated less muscle fatigue. There was a greater TF (P<0.05) at the end of the SC, indicating greater central fatigue, in the CRF group, which failed to recruit muscle (to continue the SC), as well as the controls. M-Wave amplitude was lower in the CRF group than in the controls (P<0.01), indicating impaired neuromuscular junction conduction with CRF unrelated to central fatigue (M-wave amplitude did not change with SC). These data demonstrate that CRF patients exhibited greater central fatigue, indicated by shorter ET and less voluntary muscle recruitment during an SC relative to controls.

  18. Material fatigue in high pressure piping

    Energy Technology Data Exchange (ETDEWEB)

    Brunne, W.C. [Pro Novum, Research and Technological Services, Ltd, Katowice, (Poland)

    1998-12-31

    The present paper describes a type of damage to four-way cross pieces on live steam and reheated steam pipelines. The results of metallographic examination and strength tests are presented. The occurring mechanisms of material degradation, i.e. low-cycle fatigue and hydrogen corrosion are discussed. The both mechanisms result in the corrosion fatigue of the material causing the failure of cross pieces. A new design of cross piece was proposed. (orig.) 5 refs.

  19. Fatigue Tests with Densit Cylinders - D4

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    This report contains descriptions and results of a series of fatigue tests performed during the autumn of 2005 at the Stuctural Research Laboratory, Aalborg University. Cylinders with a diameter of 45 mm and a height of 90 mm were used as test specimens; the material was Densit Ducorit D4. Four...... cylinders were tested statically under compression and the rest of the cylinders (30) were tested under fatigue conditions with a load varying sinusoidally....

  20. Fatigue associated with prolonged graded running.

    Science.gov (United States)

    Giandolini, Marlene; Vernillo, Gianluca; Samozino, Pierre; Horvais, Nicolas; Edwards, W Brent; Morin, Jean-Benoît; Millet, Guillaume Y

    2016-10-01

    Scientific experiments on running mainly consider level running. However, the magnitude and etiology of fatigue depend on the exercise under consideration, particularly the predominant type of contraction, which differs between level, uphill, and downhill running. The purpose of this review is to comprehensively summarize the neurophysiological and biomechanical changes due to fatigue in graded running. When comparing prolonged hilly running (i.e., a combination of uphill and downhill running) to level running, it is found that (1) the general shape of the neuromuscular fatigue-exercise duration curve as well as the etiology of fatigue in knee extensor and plantar flexor muscles are similar and (2) the biomechanical consequences are also relatively comparable, suggesting that duration rather than elevation changes affects neuromuscular function and running patterns. However, 'pure' uphill or downhill running has several fatigue-related intrinsic features compared with the level running. Downhill running induces severe lower limb tissue damage, indirectly evidenced by massive increases in plasma creatine kinase/myoglobin concentration or inflammatory markers. In addition, low-frequency fatigue (i.e., excitation-contraction coupling failure) is systematically observed after downhill running, although it has also been found in high-intensity uphill running for different reasons. Indeed, low-frequency fatigue in downhill running is attributed to mechanical stress at the interface sarcoplasmic reticulum/T-tubule, while the inorganic phosphate accumulation probably plays a central role in intense uphill running. Other fatigue-related specificities of graded running such as strategies to minimize the deleterious effects of downhill running on muscle function, the difference of energy cost versus heat storage or muscle activity changes in downhill, level, and uphill running are also discussed.

  1. Operational Risk Management of Fatigue Effects II

    Science.gov (United States)

    2008-08-01

    Class A mishaps from FY1972-FY2000 ( Luna , 2003). Fatigue was cited as a major or causal factor in 26 USAF Class A mishaps over that same period...is not acquired, it induces involuntary, unplanned sleep (i.e., falling asleep on the job and at the wheel). As individuals work across the day and...commander, supervisor and operator has a moral responsibility to protect our personnel from the possibility of fatigue-induced mishaps. The work we do with

  2. Mechanisms of exertional fatigue in muscle glycogenoses

    DEFF Research Database (Denmark)

    Vissing, John; Haller, Ronald G

    2012-01-01

    concentrations of extracellular potassium in exercising muscle and (3) exaggerated accumulation of ADP during exercise that may inhibit sodium-potassium and calcium-ATPases. Disorders of muscle glycogenolysis and glycolysis reveal the crucial role of these metabolic processes for supplying both anaerobic...... and aerobic energy for muscle contraction; and the pathological fatigue that occurs when glycogenolysis and/or glycolysis is blocked imply an important role for theses metabolic pathways in normal muscle fatigue....

  3. Diffraction Measurements on CPF Steel Fatigue Samples

    Science.gov (United States)

    1995-05-30

    I I I I I I I I I I I I I I I I I I I - 535 - Diffraction Measurements on CPF Steel Fatigue Samples by Percy Clark*, Tom...to the formation of a detectable fatigue crack, a series of hourglass shaped specimens were fabricated from 350WT steel , cyclically loaded to...were made between these experiments and earlier less successful similar experiments conducted on HY80 samples. The limitations and potential for the

  4. Auditory discrimination of force of impact.

    Science.gov (United States)

    Lutfi, Robert A; Liu, Ching-Ju; Stoelinga, Christophe N J

    2011-04-01

    The auditory discrimination of force of impact was measured for three groups of listeners using sounds synthesized according to first-order equations of motion for the homogenous, isotropic bar [Morse and Ingard (1968). Theoretical Acoustics pp. 175-191]. The three groups were professional percussionists, nonmusicians, and individuals recruited from the general population without regard to musical background. In the two-interval, forced-choice procedure, listeners chose the sound corresponding to the greater force of impact as the length of the bar varied from one presentation to the next. From the equations of motion, a maximum-likelihood test for the task was determined to be of the form Δlog A + αΔ log f > 0, where A and f are the amplitude and frequency of any one partial and α = 0.5. Relative decision weights on Δ log f were obtained from the trial-by-trial responses of listeners and compared to α. Percussionists generally outperformed the other groups; however, the obtained decision weights of all listeners deviated significantly from α and showed variability within groups far in excess of the variability associated with replication. Providing correct feedback after each trial had little effect on the decision weights. The variability in these measures was comparable to that seen in studies involving the auditory discrimination of other source attributes.

  5. Happiness increases distraction by auditory deviant stimuli.

    Science.gov (United States)

    Pacheco-Unguetti, Antonia Pilar; Parmentier, Fabrice B R

    2016-08-01

    Rare and unexpected changes (deviants) in an otherwise repeated stream of task-irrelevant auditory distractors (standards) capture attention and impair behavioural performance in an ongoing visual task. Recent evidence indicates that this effect is increased by sadness in a task involving neutral stimuli. We tested the hypothesis that such effect may not be limited to negative emotions but reflect a general depletion of attentional resources by examining whether a positive emotion (happiness) would increase deviance distraction too. Prior to performing an auditory-visual oddball task, happiness or a neutral mood was induced in participants by means of the exposure to music and the recollection of an autobiographical event. Results from the oddball task showed significantly larger deviance distraction following the induction of happiness. Interestingly, the small amount of distraction typically observed on the standard trial following a deviant trial (post-deviance distraction) was not increased by happiness. We speculate that happiness might interfere with the disengagement of attention from the deviant sound back towards the target stimulus (through the depletion of cognitive resources and/or mind wandering) but help subsequent cognitive control to recover from distraction.

  6. Intrinsic modulators of auditory thalamocortical transmission.

    Science.gov (United States)

    Lee, Charles C; Sherman, S Murray

    2012-05-01

    Neurons in layer 4 of the primary auditory cortex receive convergent glutamatergic inputs from thalamic and cortical projections that activate different groups of postsynaptic glutamate receptors. Of particular interest in layer 4 neurons are the Group II metabotropic glutamate receptors (mGluRs), which hyperpolarize neurons postsynaptically via the downstream opening of GIRK channels. This pronounced effect on membrane conductance could influence the neuronal processing of synaptic inputs, such as those from the thalamus, essentially modulating information flow through the thalamocortical pathway. To examine how Group II mGluRs affect thalamocortical transmission, we used an in vitro slice preparation of the auditory thalamocortical pathways in the mouse to examine synaptic transmission under conditions where Group II mGluRs were activated. We found that both pre- and post-synaptic Group II mGluRs are involved in the attenuation of thalamocortical EPSP/Cs. Thus, thalamocortical synaptic transmission is suppressed via the presynaptic reduction of thalamocortical neurotransmitter release and the postsynaptic inhibition of the layer 4 thalamorecipient neurons. This could enable the thalamocortical pathway to autoregulate transmission, via either a gating or gain control mechanism, or both.

  7. Auditory evoked potentials in postconcussive syndrome.

    Science.gov (United States)

    Drake, M E; Weate, S J; Newell, S A

    1996-12-01

    The neuropsychiatric sequelae of minor head trauma have been the source of controversy. Most clinical and imaging studies have shown no alteration after concussion, but neuropsychological and neuropathological abnormalities have been reported. Some changes in neurophysiologic diagnostic tests have been described in postconcussive syndrome. We recorded middle latency auditory evoked potentials (MLR) and slow vertex responses (SVR) in 20 individuals with prolonged cognitive difficulties, behavior changes, dizziness, and headache after concussion. MLR is utilized alternating polarity clicks presented monaurally at 70 dB SL at 4 per second, with 40 dB contralateral masking. Five hundred responses were recorded and replicated from Cz-A1 and Cz-A2, with 50 ms. analysis time and 20-1000 Hz filter band pass. SVRs were recorded with the same montage, but used rarefaction clicks, 0.5 Hz stimulus rate, 500 ms. analysis time, and 1-50 Hz filter band pass. Na and Pa MLR components were reduced in amplitude in postconcussion patients. Pa latency was significantly longer in patients than in controls. SVR amplitudes were longer in concussed individuals, but differences in latency and amplitude were not significant. These changes may reflect posttraumatic disturbance in presumed subcortical MLR generators, or in frontal or temporal cortical structures that modulate them. Middle and long-latency auditory evoked potentials may be helpful in the evaluation of postconcussive neuropsychiatric symptoms.

  8. Auditory verbal hallucinations: neuroimaging and treatment.

    Science.gov (United States)

    Bohlken, M M; Hugdahl, K; Sommer, I E C

    2017-01-01

    Auditory verbal hallucinations (AVH) are a frequently occurring phenomenon in the general population and are considered a psychotic symptom when presented in the context of a psychiatric disorder. Neuroimaging literature has shown that AVH are subserved by a variety of alterations in brain structure and function, which primarily concentrate around brain regions associated with the processing of auditory verbal stimuli and with executive control functions. However, the direction of association between AVH and brain function remains equivocal in certain research areas and needs to be carefully reviewed and interpreted. When AVH have significant impact on daily functioning, several efficacious treatments can be attempted such as antipsychotic medication, brain stimulation and cognitive-behavioural therapy. Interestingly, the neural correlates of these treatments largely overlap with brain regions involved in AVH. This suggests that the efficacy of treatment corresponds to a normalization of AVH-related brain activity. In this selected review, we give a compact yet comprehensive overview of the structural and functional neuroimaging literature on AVH, with a special focus on the neural correlates of efficacious treatment.

  9. Selective attention in an insect auditory neuron.

    Science.gov (United States)

    Pollack, G S

    1988-07-01

    Previous work (Pollack, 1986) showed that an identified auditory neuron of crickets, the omega neuron, selectively encodes the temporal structure of an ipsilateral sound stimulus when a contralateral stimulus is presented simultaneously, even though the contralateral stimulus is clearly encoded when it is presented alone. The present paper investigates the physiological basis for this selective response. The selectivity for the ipsilateral stimulus is a result of the apparent intensity difference of ipsi- and contralateral stimuli, which is imposed by auditory directionality; when simultaneous presentation of stimuli from the 2 sides is mimicked by presenting low- and high-intensity stimuli simultaneously from the ipsilateral side, the neuron responds selectively to the high-intensity stimulus, even though the low-intensity stimulus is effective when it is presented alone. The selective encoding of the more intense (= ipsilateral) stimulus is due to intensity-dependent inhibition, which is superimposed on the cell's excitatory response to sound. Because of the inhibition, the stimulus with lower intensity (i.e., the contralateral stimulus) is rendered subthreshold, while the stimulus with higher intensity (the ipsilateral stimulus) remains above threshold. Consequently, the temporal structure of the low-intensity stimulus is filtered out of the neuron's spike train. The source of the inhibition is not known. It is not a consequence of activation of the omega neuron. Its characteristics are not consistent with those of known inhibitory inputs to the omega neuron.

  10. Talker-specific auditory imagery during reading

    Science.gov (United States)

    Nygaard, Lynne C.; Duke, Jessica; Kawar, Kathleen; Queen, Jennifer S.

    2004-05-01

    The present experiment was designed to determine if auditory imagery during reading includes talker-specific characteristics such as speaking rate. Following Kosslyn and Matt (1977), participants were familiarized with two talkers during a brief prerecorded conversation. One talker spoke at a fast speaking rate and one spoke at a slow speaking rate. During familiarization, participants were taught to identify each talker by name. At test, participants were asked to read two passages and told that either the slow or fast talker wrote each passage. In one condition, participants were asked to read each passage aloud, and in a second condition, they were asked to read each passage silently. Participants pressed a key when they had completed reading the passage, and reading times were collected. Reading times were significantly slower when participants thought they were reading a passage written by the slow talker than when reading a passage written by the fast talker. However, the effects of speaking rate were only present in the reading-aloud condition. Additional experiments were conducted to investigate the role of attention to talker's voice during familiarization. These results suggest that readers may engage in auditory imagery while reading that preserves perceptual details of an author's voice.

  11. Understanding Muscle Dysfunction in Chronic Fatigue Syndrome

    Directory of Open Access Journals (Sweden)

    Gina Rutherford

    2016-01-01

    Full Text Available Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME.

  12. Understanding Muscle Dysfunction in Chronic Fatigue Syndrome.

    Science.gov (United States)

    Rutherford, Gina; Manning, Philip; Newton, Julia L

    2016-01-01

    Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME.

  13. [Fatigue and weight loss in Parkinson's disease].

    Science.gov (United States)

    Okuma, Yasuyuki

    2012-04-01

    Fatigue is a common, under recognized, and poorly understood nonmotor symptom in Parkinson's disease (PD). Fatigue frequently presents early in PD, and its prevalence increases with disease progression, affecting up to 60% of patients. Fatigue has a negative impact on quality of life. Fatigue is often associated with other nonmotor symptoms, including sleep disturbance, excessive daytime sleepiness, and depression. Only a few reports have been published on the treatment of fatigue in PD (methylphenidate, levodopa, and pramipexole). Further well-designed studies, including physiotherapy, are necessary to develop more effective treatments for PD-associated fatigue. A number of patients with PD lose weight because of loss of fat. However, the evolution and determinants of weight loss are not well established. Possible determinants of weight loss in PD include loss of appetite, impaired hand-mouth coordination, difficulty in chewing and dysphagia, nausea, intestinal hypomotility, and increased energy requirements because of muscular rigidity and involuntary movements. Noticeable weight gain has repeatedly been reported after subthalamic or pallidal deep brain stimulation. Because low body weight is associated with negative health effects and a poor prognosis, monitoring weight and nutritional status should be part of PD management.

  14. Neck muscle fatigue alters upper limb proprioception.

    Science.gov (United States)

    Zabihhosseinian, Mahboobeh; Holmes, Michael W R; Murphy, Bernadette

    2015-05-01

    Limb proprioception is an awareness by the central nervous system (CNS) of the location of a limb in three-dimensional space and is essential for movement and postural control. The CNS uses the position of the head and neck when interpreting the position of the upper limb, and altered input from neck muscles may affect the sensory inputs to the CNS and consequently may impair the awareness of upper limb joint position. The purpose of this study was to determine whether fatigue of the cervical extensors muscles (CEM) using a submaximal fatigue protocol alters the ability to recreate a previously presented elbow angle with the head in a neutral position. Twelve healthy individuals participated. CEM activity was examined bilaterally using surface electromyography, and kinematics of the elbow joint was measured. The fatigue protocol included an isometric neck extension task at 70 % of maximum until failure. Joint position error increased following fatigue, demonstrating a significant main effect of time (F 2, 18 = 19.41, p ≤ 0.0001) for absolute error. No significant differences were found for variable error (F 2, 18 = 0.27, p = 0.76) or constant error (F 2, 18 = 1.16 of time, p ≤ 0.33). This study confirms that fatigue of the CEM can reduce the accuracy of elbow joint position matching. This suggests that altered afferent input from the neck subsequent to fatigue may impair upper limb proprioception.

  15. Increased BOLD Signals Elicited by High Gamma Auditory Stimulation of the Left Auditory Cortex in Acute State Schizophrenia

    Directory of Open Access Journals (Sweden)

    Hironori Kuga, M.D.

    2016-10-01

    We acquired BOLD responses elicited by click trains of 20, 30, 40 and 80-Hz frequencies from 15 patients with acute episode schizophrenia (AESZ, 14 symptom-severity-matched patients with non-acute episode schizophrenia (NASZ, and 24 healthy controls (HC, assessed via a standard general linear-model-based analysis. The AESZ group showed significantly increased ASSR-BOLD signals to 80-Hz stimuli in the left auditory cortex compared with the HC and NASZ groups. In addition, enhanced 80-Hz ASSR-BOLD signals were associated with more severe auditory hallucination experiences in AESZ participants. The present results indicate that neural over activation occurs during 80-Hz auditory stimulation of the left auditory cortex in individuals with acute state schizophrenia. Given the possible association between abnormal gamma activity and increased glutamate levels, our data may reflect glutamate toxicity in the auditory cortex in the acute state of schizophrenia, which might lead to progressive changes in the left transverse temporal gyrus.

  16. Continuous fatigue crack monitoring of bridges: Long-Term Electrochemical Fatigue Sensor (LTEFS)

    Science.gov (United States)

    Moshier, Monty A.; Nelson, Levi; Brinkerhoff, Ryan; Miceli, Marybeth

    2016-04-01

    Fatigue cracks in steel bridges degrade the load-carrying capacity of these structures. Fatigue damage accumulation caused by the repetitive loading of everyday truck traffic can cause small fatigue cracks initiate. Understanding the growth of these fatigue cracks is critical to the safety and reliability of our transportation infrastructure. However, modeling fatigue in bridges is difficult due to the nature of the loading and variations in connection integrity. When fatigue cracks reach critical lengths failures occur causing partial or full closures, emergency repairs, and even full structural failure. Given the aging US highway and the trend towards asset management and life extension, the need for reliable, cost effective sensors and monitoring technologies to alert bridge owners when fatigue cracks are growing is higher than ever. In this study, an innovative Long-Term Electrochemical Fatigue Sensor (LTEFS) has been developed and introduced to meet the growing NDT marketplace demand for sensors that have the ability to continuously monitor fatigue cracks. The performance of the LTEFS has been studied in the laboratory and in the field. Data was collected using machined specimens with different lengths of naturally initiated fatigue cracks, applied stress levels, applied stress ratios, and for both sinusoidal and real-life bridge spectrum type loading. The laboratory data was evaluated and used to develop an empirically based algorithm used for crack detection. Additionally, beta-tests on a real bridge structure has been completed. These studies have conclusively demonstrated that LTEFS holds great potential for long-term monitoring of fatigue cracks in steel structures

  17. Auditory habituation to simple tones: reduced evidence for habituation in children compared to adults

    Directory of Open Access Journals (Sweden)

    Jana eMuenssinger

    2013-07-01

    Full Text Available Habituation – the response decrement to repetitively presented stimulation - is a basic cognitive capability and suited to investigate development and integrity of the human brain. To evaluate the developmental process of auditory habituation, the current study used magnetoencephalography to investigate auditory habituation, dishabituation and stimulus specificity in children and adults and compared the results between age groups. Twenty-nine children (Mage = 9.69 years, SD ± 0.47 and 14 adults (Mage = 29.29 years, SD ± 3.47 participated in the study and passively listened to a habituation paradigm consisting of 100 trains of tones which were composed of five 500Hz tones, one 750Hz tone (dishabituator and another two 500Hz tones, respectively while focusing their attention on a silent movie. Adults showed the expected habituation and stimulus specificity within-trains while no response decrement was found between trains. Sensory adaptation or fatigue as a source for response decrement in adults is unlikely due to the strong reaction to the dishabituator (stimulus specificity and strong mismatch negativity responses. However, in children neither habituation nor dishabituation or stimulus specificity could be found within-trains, response decrement was found across trains. It can be speculated that the differences between children and adults are linked to differences in stimulus processing due to attentional processes. This study shows developmental differences in task-related brain activation and discusses the possible influence of broader concepts such as attention, which should be taken into account when comparing performance in an identical task between age groups.

  18. Fatigue Analysis of a Mono-Tower Platform

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Brincker, Rune

    In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed thro...... of the natural period, damping ratio, current, stress Spectrum and parameters describing the fatigue strength. Further, soil damping is shown to be significant for the Mono-tower.......In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed...

  19. Fatigue Reliability Analysis of a Mono-Tower Platform

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Brincker, Rune

    1991-01-01

    In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed thro...... of the natural period, damping ratio, current, stress spectrum and parameters describing the fatigue strength. Further, soil damping is shown to be significant for the Mono-tower.......In this paper, a fatigue reliability analysis of a Mono-tower platform is presented. The failure mode, fatigue failure in the butt welds, is investigated with two different models. The one with the fatigue strength expressed through SN relations, the other with the fatigue strength expressed...

  20. High cycle fatigue characteristics of 2124-T851 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    LI Xue; YIN Zhimin; NIE Bo; ZHONG Li; PAN Qinglin; JIANG Feng

    2007-01-01

    The fatigue crack growth rate, fracture toughness and fatigue S-N curve of 2124-T851 aluminum alloy at high cycle fatigue condition were measured and fatigue fracture process and fractography were studied using optical microscopy (OM), X-ray diffraction (XRD) technique, trans-mission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that at room tempera-ture and R = 0.1 conditions, the characteristics of fatigue fracture could be observed. Under those conditions, the fatigue strength and the fracture toughness of a 2124-T851 thick plate is 243 MPa and 29.64 MPa·m1/2,respectively.At high cycle fatigue condition, the higher the stress amplitude,the wider the space between fatigue striations, the faster the rate of fatigue crack developing and going into the intermittent fracture area, and the greater the ratio between the intermittent fracture area and the whole fracture area.

  1. Fatigue behavior of dental resin composites: flexural fatigue in vitro versus 6 years in vivo

    NARCIS (Netherlands)

    F. Garcia-Godoy; R. Frankenberger; U. Lohbauer; A.J. Feilzer; N. Krämer

    2012-01-01

    Objectives: To evaluate fatigue behavior of direct resin composite restorations (Tetric Ceram vs. Grandio) in vitro and in vivo over an observation period of 6 years. Methods: For the in vitro part, Young's moduli (YM) were calculated and both initial (FS: flexural strength) and fatigue flexural str

  2. A Verification and Analysis of the USAF/DoD Fatigue Model and Fatigue Management Technology

    Science.gov (United States)

    2005-11-01

    We Nap: Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep . Stampi, C. (ed) Birkhduser, Boston. Defense Acquisition...Windows® soffivare application of the Sleep , Activity, Fatigue, and Task Effectiveness (SAFTE) applied model. The application, the Fatigue Avoidance...Scheduling Tool (FASTTM) was re-engineered as a clone from the SAFTE specification. The verification considered nine sleep /wake schedules that were

  3. Fatigue Technology Assessment and Strategies for Fatigue Avoidance in Marine Structures

    Science.gov (United States)

    1992-06-01

    Endurance, cycles Figure 9-4 Comparison of Fatigue Strength Improvement Techniques (From Reference 9.7) I- CA a :, ., a , a MS M w a us 4-4 4. 4.1 4- M...1991 SSC-365 Marine Structural Integrity Programs ( MSIP ) by Robert G. Bea 1992 SSC-366 Threshold Corrosion Fatigue of Welded Shipbuilding Steels by G

  4. Integration of auditory and tactile inputs in musical meter perception.

    Science.gov (United States)

    Huang, Juan; Gamble, Darik; Sarnlertsophon, Kristine; Wang, Xiaoqin; Hsiao, Steven

    2013-01-01

    Musicians often say that they not only hear but also "feel" music. To explore the contribution of tactile information to "feeling" music, we investigated the degree that auditory and tactile inputs are integrated in humans performing a musical meter-recognition task. Subjects discriminated between two types of sequences, "duple" (march-like rhythms) and "triple" (waltz-like rhythms), presented in three conditions: (1) unimodal inputs (auditory or tactile alone); (2) various combinations of bimodal inputs, where sequences were distributed between the auditory and tactile channels such that a single channel did not produce coherent meter percepts; and (3) bimodal inputs where the two channels contained congruent or incongruent meter cues. We first show that meter is perceived similarly well (70-85 %) when tactile or auditory cues are presented alone. We next show in the bimodal experiments that auditory and tactile cues are integrated to produce coherent meter percepts. Performance is high (70-90 %) when all of the metrically important notes are assigned to one channel and is reduced to 60 % when half of these notes are assigned to one channel. When the important notes are presented simultaneously to both channels, congruent cues enhance meter recognition (90 %). Performance dropped dramatically when subjects were presented with incongruent auditory cues (10 %), as opposed to incongruent tactile cues (60 %), demonstrating that auditory input dominates meter perception. These observations support the notion that meter perception is a cross-modal percept with tactile inputs underlying the perception of "feeling" music.

  5. The Study of Frequency Self Care Strategies against Auditory Hallucinations

    Directory of Open Access Journals (Sweden)

    Mahin Nadem

    2012-03-01

    Full Text Available Background: In schizophrenic clients, self-care strategies against auditory hallucinations can decrease disturbances results in hallucination. This study was aimed to assess frequency of self-care strategies against auditory hallucinations in paranoid schizophrenic patients, hospitalized in Shafa Hospital.Materials and Method: This was a descriptive study on 201 patients with paranoid schizophrenia hospitalized in psychiatry unit with convenience sampling in Rasht. The gathered data consists of two parts, first unit demographic characteristic and the second part, self- report questionnaire include 38 items about self-care strategies.Results: There were statistically significant relationship between demographic variables and knowledg effect and self-care strategies against auditory hallucinaions. Sex with phisical domain p0.07, marriage status with cognitive domain (p>0.07 and life status with behavioural domain (p>0.01. 53.2% of reported type of our auditory hallucinations were command hallucinations, furtheremore the most effective self-care strategies against auditory hallucinations were from physical domain and substance abuse (82.1% was the most effective strategies in this domain.Conclusion: The client with paranoid schizophrenia used more than physical domain strategies against auditory hallucinaions and this result highlight need those to approprait nursing intervention. Instruction and leading about selection the effective self-care strategies against auditory ha

  6. Translation and adaptation of functional auditory performance indicators (FAPI

    Directory of Open Access Journals (Sweden)

    Karina Ferreira

    2011-12-01

    Full Text Available Work with deaf children has gained new attention since the expectation and goal of therapy has expanded to language development and subsequent language learning. Many clinical tests were developed for evaluation of speech sound perception in young children in response to the need for accurate assessment of hearing skills that developed from the use of individual hearing aids or cochlear implants. These tests also allow the evaluation of the rehabilitation program. However, few of these tests are available in Portuguese. Evaluation with the Functional Auditory Performance Indicators (FAPI generates a child's functional auditory skills profile, which lists auditory skills in an integrated and hierarchical order. It has seven hierarchical categories, including sound awareness, meaningful sound, auditory feedback, sound source localizing, auditory discrimination, short-term auditory memory, and linguistic auditory processing. FAPI evaluation allows the therapist to map the child's hearing profile performance, determine the target for increasing the hearing abilities, and develop an effective therapeutic plan. Objective: Since the FAPI is an American test, the inventory was adapted for application in the Brazilian population. Material and Methods: The translation was done following the steps of translation and back translation, and reproducibility was evaluated. Four translated versions (two originals and two back-translated were compared, and revisions were done to ensure language adaptation and grammatical and idiomatic equivalence. Results: The inventory was duly translated and adapted. Conclusion: Further studies about the application of the translated FAPI are necessary to make the test practicable in Brazilian clinical use.

  7. Auditory-perceptual learning improves speech motor adaptation in children.

    Science.gov (United States)

    Shiller, Douglas M; Rochon, Marie-Lyne

    2014-08-01

    Auditory feedback plays an important role in children's speech development by providing the child with information about speech outcomes that is used to learn and fine-tune speech motor plans. The use of auditory feedback in speech motor learning has been extensively studied in adults by examining oral motor responses to manipulations of auditory feedback during speech production. Children are also capable of adapting speech motor patterns to perceived changes in auditory feedback; however, it is not known whether their capacity for motor learning is limited by immature auditory-perceptual abilities. Here, the link between speech perceptual ability and the capacity for motor learning was explored in two groups of 5- to 7-year-old children who underwent a period of auditory perceptual training followed by tests of speech motor adaptation to altered auditory feedback. One group received perceptual training on a speech acoustic property relevant to the motor task while a control group received perceptual training on an irrelevant speech contrast. Learned perceptual improvements led to an enhancement in speech motor adaptation (proportional to the perceptual change) only for the experimental group. The results indicate that children's ability to perceive relevant speech acoustic properties has a direct influence on their capacity for sensory-based speech motor adaptation.

  8. Missing a trick: Auditory load modulates conscious awareness in audition.

    Science.gov (United States)

    Fairnie, Jake; Moore, Brian C J; Remington, Anna

    2016-07-01

    In the visual domain there is considerable evidence supporting the Load Theory of Attention and Cognitive Control, which holds that conscious perception of background stimuli depends on the level of perceptual load involved in a primary task. However, literature on the applicability of this theory to the auditory domain is limited and, in many cases, inconsistent. Here we present a novel "auditory search task" that allows systematic investigation of the impact of auditory load on auditory conscious perception. An array of simultaneous, spatially separated sounds was presented to participants. On half the trials, a critical stimulus was presented concurrently with the array. Participants were asked to detect which of 2 possible targets was present in the array (primary task), and whether the critical stimulus was present or absent (secondary task). Increasing the auditory load of the primary task (raising the number of sounds in the array) consistently reduced the ability to detect the critical stimulus. This indicates that, at least in certain situations, load theory applies in the auditory domain. The implications of this finding are discussed both with respect to our understanding of typical audition and for populations with altered auditory processing. (PsycINFO Database Record

  9. A corollary discharge maintains auditory sensitivity during sound production.

    Science.gov (United States)

    Poulet, James F A; Hedwig, Berthold

    2002-08-22

    Speaking and singing present the auditory system of the caller with two fundamental problems: discriminating between self-generated and external auditory signals and preventing desensitization. In humans and many other vertebrates, auditory neurons in the brain are inhibited during vocalization but little is known about the nature of the inhibition. Here we show, using intracellular recordings of auditory neurons in the singing cricket, that presynaptic inhibition of auditory afferents and postsynaptic inhibition of an identified auditory interneuron occur in phase with the song pattern. Presynaptic and postsynaptic inhibition persist in a fictively singing, isolated cricket central nervous system and are therefore the result of a corollary discharge from the singing motor network. Mimicking inhibition in the interneuron by injecting hyperpolarizing current suppresses its spiking response to a 100-dB sound pressure level (SPL) acoustic stimulus and maintains its response to subsequent, quieter stimuli. Inhibition by the corollary discharge reduces the neural response to self-generated sound and protects the cricket's auditory pathway from self-induced desensitization.

  10. Functional sex differences in human primary auditory cortex

    Energy Technology Data Exchange (ETDEWEB)

    Ruytjens, Liesbet [University Medical Center Groningen, Department of Otorhinolaryngology, Groningen (Netherlands); University Medical Center Utrecht, Department Otorhinolaryngology, P.O. Box 85500, Utrecht (Netherlands); Georgiadis, Janniko R. [University of Groningen, University Medical Center Groningen, Department of Anatomy and Embryology, Groningen (Netherlands); Holstege, Gert [University of Groningen, University Medical Center Groningen, Center for Uroneurology, Groningen (Netherlands); Wit, Hero P. [University Medical Center Groningen, Department of Otorhinolaryngology, Groningen (Netherlands); Albers, Frans W.J. [University Medical Center Utrecht, Department Otorhinolaryngology, P.O. Box 85500, Utrecht (Netherlands); Willemsen, Antoon T.M. [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen (Netherlands)

    2007-12-15

    We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a baseline (no auditory stimulation). We found a sex difference in activation of the left and right PAC when comparing music to noise. The PAC was more activated by music than by noise in both men and women. But this difference between the two stimuli was significantly higher in men than in women. To investigate whether this difference could be attributed to either music or noise, we compared both stimuli with the baseline and revealed that noise gave a significantly higher activation in the female PAC than in the male PAC. Moreover, the male group showed a deactivation in the right prefrontal cortex when comparing noise to the baseline, which was not present in the female group. Interestingly, the auditory and prefrontal regions are anatomically and functionally linked and the prefrontal cortex is known to be engaged in auditory tasks that involve sustained or selective auditory attention. Thus we hypothesize that differences in attention result in a different deactivation of the right prefrontal cortex, which in turn modulates the activation of the PAC and thus explains the sex differences found in the activation of the PAC. Our results suggest that sex is an important factor in auditory brain studies. (orig.)

  11. Cochlear Responses and Auditory Brainstem Response Functions in Adults with Auditory Neuropathy/ Dys-Synchrony and Individuals with Normal Hearing

    Directory of Open Access Journals (Sweden)

    Zahra Jafari

    2007-06-01

    Full Text Available Background and Aim: Physiologic measures of cochlear and auditory nerve function may be of assis¬tance in distinguishing between hearing disorders due primarily to auditory nerve impairment from those due primarily to cochlear hair cells dysfunction. The goal of present study was to measure of co-chlear responses (otoacoustic emissions and cochlear microphonics and auditory brainstem response in some adults with auditory neuropathy/ dys-synchrony and subjects with normal hearing. Materials and Methods: Patients were 16 adults (32 ears in age range of 14-30 years with auditory neu¬ropathy/ dys-synchrony and 16 individuals in age range of 16-30 years from both sexes. The results of transient otoacoustic emissions, cochlear microphonics and auditory brainstem response measures were compared in both groups and the effects of age, sex, ear and degree of hearing loss were studied. Results: The pure-tone average was 48.1 dB HL in auditory neuropathy/dys-synchrony group and the fre¬quency of low tone loss and flat audiograms were higher among other audiogram's shapes. Transient oto¬acoustic emissions were shown in all auditory neuropathy/dys-synchrony people except two cases and its average was near in both studied groups. The latency and amplitude of the biggest reversed co-chlear microphonics response were higher in auditory neuropathy/dys-synchrony patients than control peo¬ple significantly. The correlation between cochlear microphonics amplitude and degree of hearing loss was not significant, and age had significant effect in some cochlear microphonics measures. Audi-tory brainstem response had no response in auditory neuropathy/dys-synchrony patients even with low stim¬uli rates. Conclusion: In adults with speech understanding worsen than predicted from the degree of hearing loss that suspect to auditory neuropathy/ dys-synchrony, the frequency of low tone loss and flat audiograms are higher. Usually auditory brainstem response is absent in

  12. Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Dominguez, Sergio Marquez; Sørensen, John Dalsgaard

    2012-01-01

    Consequences of failure of offshore wind turbines (OWTs) are in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration...... is discussed and results are presented for calibrated optimal fatigue design factors. Further, the influence of inspections is considered in order to extend and maintain a given target safety level....... of appropriate partial safety factors/Fatigue Design Factors (FDF) for steel substructures for OWTs is the scope of this paper. A reliability-based approach is used and a probabilistic model has been developed, where design and limit state equations are established for fatigue failure. The strength and load...

  13. Diffusion tensor imaging and MR morphometry of the central auditory pathway and auditory cortex in aging.

    Science.gov (United States)

    Profant, O; Škoch, A; Balogová, Z; Tintěra, J; Hlinka, J; Syka, J

    2014-02-28

    Age-related hearing loss (presbycusis) is caused mainly by the hypofunction of the inner ear, but recent findings point also toward a central component of presbycusis. We used MR morphometry and diffusion tensor imaging (DTI) with a 3T MR system with the aim to study the state of the central auditory system in a group of elderly subjects (>65years) with mild presbycusis, in a group of elderly subjects with expressed presbycusis and in young controls. Cortical reconstruction, volumetric segmentation and auditory pathway tractography were performed. Three parameters were evaluated by morphometry: the volume of the gray matter, the surface area of the gyrus and the thickness of the cortex. In all experimental groups the surface area and gray matter volume were larger on the left side in Heschl's gyrus and planum temporale and slightly larger in the gyrus frontalis superior, whereas they were larger on the right side in the primary visual cortex. Almost all of the measured parameters were significantly smaller in the elderly subjects in Heschl's gyrus, planum temporale and gyrus frontalis superior. Aging did not change the side asymmetry (laterality) of the gyri. In the central part of the auditory pathway above the inferior colliculus, a trend toward an effect of aging was present in the axial vector of the diffusion (L1) variable of DTI, with increased values observed in elderly subjects. A trend toward a decrease of L1 on the left side, which was more pronounced in the elderly groups, was observed. The effect of hearing loss was present in subjects with expressed presbycusis as a trend toward an increase of the radial vectors (L2L3) in the white matter under Heschl's gyrus. These results suggest that in addition to peripheral changes, changes in the central part of the auditory system in elderly subjects are also present; however, the extent of hearing loss does not play a significant role in the central changes.

  14. Air pollution is associated with brainstem auditory nuclei pathology and delayed brainstem auditory evoked potentials

    OpenAIRE

    Calderón-Garcidueñas, Lilian; D’Angiulli, Amedeo; Kulesza, Randy J.; Torres-Jardón, Ricardo; Osnaya, Norma; Romero, Lina; Keefe, Sheyla; Herritt, Lou; Brooks, Diane M.; Avila-Ramirez, Jose; Delgado-Chávez, Ricardo; Medina-Cortina, Humberto; González-González, Luis Oscar

    2011-01-01

    We assessed brainstem inflammation in children exposed to air pollutants by comparing brainstem auditory evoked potentials (BAEPs) and blood inflammatory markers in children age 96.3± 8.5 months from highly polluted (n=34) versus a low polluted city (n=17). The brainstems of nine children with accidental deaths were also examined. Children from the highly polluted environment had significant delays in wave III (t(50)=17.038; p

  15. Psychophysical and Neural Correlates of Auditory Attraction and Aversion

    Science.gov (United States)

    Patten, Kristopher Jakob

    This study explores the psychophysical and neural processes associated with the perception of sounds as either pleasant or aversive. The underlying psychophysical theory is based on auditory scene analysis, the process through which listeners parse auditory signals into individual acoustic sources. The first experiment tests and confirms that a self-rated pleasantness continuum reliably exists for 20 various stimuli (r = .48). In addition, the pleasantness continuum correlated with the physical acoustic characteristics of consonance/dissonance (r = .78), which can facilitate auditory parsing processes. The second experiment uses an fMRI block design to test blood oxygen level dependent (BOLD) changes elicited by a subset of 5 exemplar stimuli chosen from Experiment 1 that are evenly distributed over the pleasantness continuum. Specifically, it tests and confirms that the pleasantness continuum produces systematic changes in brain activity for unpleasant acoustic stimuli beyond what occurs with pleasant auditory stimuli. Results revealed that the combination of two positively and two negatively valenced experimental sounds compared to one neutral baseline control elicited BOLD increases in the primary auditory cortex, specifically the bilateral superior temporal gyrus, and left dorsomedial prefrontal cortex; the latter being consistent with a frontal decision-making process common in identification tasks. The negatively-valenced stimuli yielded additional BOLD increases in the left insula, which typically indicates processing of visceral emotions. The positively-valenced stimuli did not yield any significant BOLD activation, consistent with consonant, harmonic stimuli being the prototypical acoustic pattern of auditory objects that is optimal for auditory scene analysis. Both the psychophysical findings of Experiment 1 and the neural processing findings of Experiment 2 support that consonance is an important dimension of sound that is processed in a manner that aids

  16. Continuity of visual and auditory rhythms influences sensorimotor coordination.

    Directory of Open Access Journals (Sweden)

    Manuel Varlet

    Full Text Available People often coordinate their movement with visual and auditory environmental rhythms. Previous research showed better performances when coordinating with auditory compared to visual stimuli, and with bimodal compared to unimodal stimuli. However, these results have been demonstrated with discrete rhythms and it is possible that such effects depend on the continuity of the stimulus rhythms (i.e., whether they are discrete or continuous. The aim of the current study was to investigate the influence of the continuity of visual and auditory rhythms on sensorimotor coordination. We examined the dynamics of synchronized oscillations of a wrist pendulum with auditory and visual rhythms at different frequencies, which were either unimodal or bimodal and discrete or continuous. Specifically, the stimuli used were a light flash, a fading light, a short tone and a frequency-modulated tone. The results demonstrate that the continuity of the stimulus rhythms strongly influences visual and auditory motor coordination. Participants' movement led continuous stimuli and followed discrete stimuli. Asymmetries between the half-cycles of the movement in term of duration and nonlinearity of the trajectory occurred with slower discrete rhythms. Furthermore, the results show that the differences of performance between visual and auditory modalities depend on the continuity of the stimulus rhythms as indicated by movements closer to the instructed coordination for the auditory modality when coordinating with discrete stimuli. The results also indicate that visual and auditory rhythms are integrated together in order to better coordinate irrespective of their continuity, as indicated by less variable coordination closer to the instructed pattern. Generally, the findings have important implications for understanding how we coordinate our movements with visual and auditory environmental rhythms in everyday life.

  17. Subsea rigid jumper design and ⅤⅣ fatigue evaluation

    Institute of Scientific and Technical Information of China (English)

    Wang Jun

    2013-01-01

    The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis.Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatigue damage caused by vortex induced vibration (ⅤⅣ).Jumper strength analysis is to determine the jumper configuration which can accommodate various load conditions and all possible span lengths driven by installation tolerances of connected subsea structures.Fatigue analysis includes two parts:thermal fatigue and ⅤⅣ fatigue.This paper presents the procedure of ⅤⅣ fatigue damage calculation.An example is given to illustrate above methodologies.

  18. Experimental and three-dimensional finite element investigation of fatigue

    Science.gov (United States)

    Bomidi, John A. R.

    Materials often fail at cyclic loads that are lower than their ultimate strength or even their yield strength due to progressive internal material degradation; commonly known as fatigue. Moreover, there is a wide scatter in observed fatigue lives of mechanical components operating under identical loading conditions. The randomness of fatigue failure is considered to be linked to basic microstructural effects such as random microstructure topology and the initiation/growth of cracks along inter/transgranular planes. Several modeling approaches have been previously presented ranging from 2D discrete element to 3D Finite Element methods with explicit representation of microstructure topology and continuum damage mechanics to capture dispersion in rolling contact fatigue life and fatigue spalling. There is, however, a need to compare the modeling approach with experimental fatigue test conditions in order to verify and as required enhance the modeling approach to capture observed fatigue failure. This dissertation presents experimental test results and three-dimensional modeling approach that capture fatigue failure. The three-dimensional modeling approach is enhanced according to the experimental observations to consider inter/trans granular failure, different modes of fatigue initiation and propagation and finally for considering effect of plasticity in fatigue of rolling contacts. The following phenomena have been investigated: (1) Fatigue of microbeams: (a )Results of fatigue life and failure from 3D modeling of intergranular fatigue in microbeams are compared with experimental observations reported in literature (2) Tensile fatigue of thin sheets: (a) A test rig with a new grip and alignment system is developed to address the challenges associated with thin sheet testing and conduct fatigue experiments. (b) The 3D fatigue model is enhanced to capture the dominant transgranular fatigue observed in the experiments. The observed and modeled fatigue life and failure

  19. A conceptual framework for interpretation of MMC fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Talreja, R. [Georgia Inst. of Tech., Atlanta (United States). School of Aerospace Engineering

    1995-09-01

    A previously developed conceptual framework for interpretation of fatigue of polymer matrix composites (PMCs) is revisited for the purpose of the interpretation of fatigue in metal matrix composites (MMCs). With appropriate modifications, the basic features in the mechanisms based fatigue life diagrams of PMCs are found to hold for MMCs as well. Fatigue data for different MMC systems are examined with the interpretative framework and some observed trends are clarified. Approaches to fatigue life modeling are discussed for the different regions of behavior interpreted by the fatigue life diagram concept. (orig.)

  20. The stability of source localization in a whole-head magnetoencephalography system demonstrated by auditory evoked field measurements

    Science.gov (United States)

    Chen, Kuen-Lin; Yang, Hong-Chang; Tsai, Sung-Ying; Liu, Yu-Wei; Liao, Shu-Hsien; Horng, Herng-Er; Lee, Yong-Ho; Kwon, Hyukchan

    2011-10-01

    Superconducting quantum interference device (SQUID), which is a very sensitive magnetic sensor, has been widely used to detect the ultra-small magnetic signals in many different territories, especially in the biomagnetic measurement. In this study, a 128-channel SQUID first-order axial gradiometer system for whole-head magnetoencephalography (MEG) measurements was setup to characterize the auditory evoked magnetic fields (AEFs). A 500 Hz monaural pure tone persisting 425 ms with the sound pressure level of 80 dB was randomly applied to the left ear of subject with the inter-stimulus interval of 1.5 ˜ 2.8 s to prevent fatigue of nerves. We demonstrated the characteristic waveforms of AEFs can be accurately recorded and analyzed. Using source localization processes, the origins of AEFs were successfully calculated to be at the auditory cortices which are brain areas known for responsive to sound stimulus. A phantom experiment also proved the good localization accuracy of the established MEG system and measurement procedures. The validated performance of the SQUID system suggests that this technique can also be employed in other brain research.

  1. Tactile stimulation and hemispheric asymmetries modulate auditory perception and neural responses in primary auditory cortex.

    Science.gov (United States)

    Hoefer, M; Tyll, S; Kanowski, M; Brosch, M; Schoenfeld, M A; Heinze, H-J; Noesselt, T

    2013-10-01

    Although multisensory integration has been an important area of recent research, most studies focused on audiovisual integration. Importantly, however, the combination of audition and touch can guide our behavior as effectively which we studied here using psychophysics and functional magnetic resonance imaging (fMRI). We tested whether task-irrelevant tactile stimuli would enhance auditory detection, and whether hemispheric asymmetries would modulate these audiotactile benefits using lateralized sounds. Spatially aligned task-irrelevant tactile stimuli could occur either synchronously or asynchronously with the sounds. Auditory detection was enhanced by non-informative synchronous and asynchronous tactile stimuli, if presented on the left side. Elevated fMRI-signals to left-sided synchronous bimodal stimulation were found in primary auditory cortex (A1). Adjacent regions (planum temporale, PT) expressed enhanced BOLD-responses for synchronous and asynchronous left-sided bimodal conditions. Additional connectivity analyses seeded in right-hemispheric A1 and PT for both bimodal conditions showed enhanced connectivity with right-hemispheric thalamic, somatosensory and multisensory areas that scaled with subjects' performance. Our results indicate that functional asymmetries interact with audiotactile interplay which can be observed for left-lateralized stimulation in the right hemisphere. There, audiotactile interplay recruits a functional network of unisensory cortices, and the strength of these functional network connections is directly related to subjects' perceptual sensitivity.

  2. Cortical oscillations in auditory perception and speech: evidence for two temporal windows in human auditory cortex

    Directory of Open Access Journals (Sweden)

    Huan eLuo

    2012-05-01

    Full Text Available Natural sounds, including vocal communication sounds, contain critical information at multiple time scales. Two essential temporal modulation rates in speech have been argued to be in the low gamma band (~20-80 ms duration information and the theta band (~150-300 ms, corresponding to segmental and syllabic modulation rates, respectively. On one hypothesis, auditory cortex implements temporal integration using time constants closely related to these values. The neural correlates of a proposed dual temporal window mechanism in human auditory cortex remain poorly understood. We recorded MEG responses from participants listening to non-speech auditory stimuli with different temporal structures, created by concatenating frequency-modulated segments of varied segment durations. We show that these non-speech stimuli with temporal structure matching speech-relevant scales (~25 ms and ~200 ms elicit reliable phase tracking in the corresponding associated oscillatory frequencies (low gamma and theta bands. In contrast, stimuli with non-matching temporal structure do not. Furthermore, the topography of theta band phase tracking shows rightward lateralization while gamma band phase tracking occurs bilaterally. The results support the hypothesis that there exists multi-time resolution processing in cortex on discontinuous scales and provide evidence for an asymmetric organization of temporal analysis (asymmetrical sampling in time, AST. The data argue for a macroscopic-level neural mechanism underlying multi-time resolution processing: the sliding and resetting of intrinsic temporal windows on privileged time scales.

  3. Comparison of Fatigue Properties and Fatigue Crack Growth Rates of Various Implantable Metals

    Directory of Open Access Journals (Sweden)

    Yoshimitsu Okazaki

    2012-12-01

    Full Text Available The fatigue strength, effects of a notch on the fatigue strength, and fatigue crack growth rate of Ti-15Zr-4Nb-4Ta alloy were compared with those of other implantable metals. Zr, Nb, and Ta are important alloying elements for Ti alloys for attaining superior long-term corrosion resistance and biocompatibility. The highly biocompatible Ti-15Zr-4Nb-4Ta alloy exhibited an excellent balance between strength and ductility. Its notched tensile strength was much higher than that of a smooth specimen. The strength of 20% cold-worked commercially pure (C.P. grade 4 Ti was close to that of Ti alloy. The tension-to-tension fatigue strength of an annealed Ti-15Zr-4Nb-4Ta rod at 107 cycles was approximately 740 MPa. The fatigue strength of this alloy was much improved by aging treatment after solution treatment. The fatigue strengths of C.P. grade 4 Ti and stainless steel were markedly improved by 20% cold working. The fatigue strength of Co-Cr-Mo alloy was markedly increased by hot forging. The notch fatigue strengths of 20% cold-worked C.P. grade 4 Ti, and annealed and aged Ti-15Zr-4Nb-4Ta, and annealed Ti-6Al-4V alloys were less than those of the smooth specimens. The fatigue crack growth rate of Ti-15Zr-4Nb-4Ta was the same as that of Ti-6Al-4V. The fatigue crack growth rate in 0.9% NaCl was the same as that in air. Stainless steel and Co-Cr-Mo-Ni-Fe alloy had a larger stress-intensity factor range (ΔK than Ti alloy.

  4. Tiapride for the treatment of auditory hallucinations in schizophrenia

    Directory of Open Access Journals (Sweden)

    Sagar Karia

    2013-01-01

    Full Text Available Hallucinations are considered as core symptoms of psychosis by both International Classification of Diseases-10 (ICD-10 and Diagnostic and Statistical Manual for the Classification of Psychiatric Disorders - 4 th edition text revised (DSM-IV TR. The most common types of hallucinations in patients with schizophrenia are auditory in nature followed by visual hallucinations. Few patients with schizophrenia have persisting auditory hallucinations despite all other features of schizophrenia having being improved. Here, we report two cases where tiapride was useful as an add-on drug for treating persistent auditory hallucinations.

  5. Human Auditory Processing: Insights from Cortical Event-related Potentials

    Directory of Open Access Journals (Sweden)

    Alexandra P. Key

    2016-04-01

    Full Text Available Human communication and language skills rely heavily on the ability to detect and process auditory inputs. This paper reviews possible applications of the event-related potential (ERP technique to the study of cortical mechanisms supporting human auditory processing, including speech stimuli. Following a brief introduction to the ERP methodology, the remaining sections focus on demonstrating how ERPs can be used in humans to address research questions related to cortical organization, maturation and plasticity, as well as the effects of sensory deprivation, and multisensory interactions. The review is intended to serve as a primer for researchers interested in using ERPs for the study of the human auditory system.

  6. Spatial Hearing with Incongruent Visual or Auditory Room Cues

    DEFF Research Database (Denmark)

    Gil Carvajal, Juan Camilo; Cubick, Jens; Santurette, Sébastien;

    2016-01-01

    whether a mismatch between playback and recording room reduces perceived distance, azimuthal direction, and compactness of the auditory image, and whether this is mostly due to incongruent auditory cues or to expectations generated from the visual impression of the room. Perceived distance ratings...... decreased significantly when collected in a more reverberant environment than the recording room, whereas azimuthal direction and compactness remained room independent. Moreover, modifying visual room-related cues had no effect on these three attributes, while incongruent auditory room-related cues between...

  7. A loudspeaker-based room auralization system for auditory research

    DEFF Research Database (Denmark)

    Favrot, Sylvain Emmanuel

    to systematically study the signal processing of realistic sounds by normal-hearing and hearing-impaired listeners, a flexible, reproducible and fully controllable auditory environment is needed. A loudspeaker-based room auralization (LoRA) system was developed in this thesis to provide virtual auditory...... environments (VAEs) with an array of loudspeakers. The LoRA system combines state-of-the-art acoustic room models with sound-field reproduction techniques. Limitations of these two techniques were taken into consideration together with the limitations of the human auditory system to localize sounds...

  8. Predictive uncertainty in auditory sequence processing

    DEFF Research Database (Denmark)

    Hansen, Niels Chr.; Pearce, Marcus T

    2014-01-01

    Previous studies of auditory expectation have focused on the expectedness perceived by listeners retrospectively in response to events. In contrast, this research examines predictive uncertainty—a property of listeners' prospective state of expectation prior to the onset of an event. We examine...... the information-theoretic concept of Shannon entropy as a model of predictive uncertainty in music cognition. This is motivated by the Statistical Learning Hypothesis, which proposes that schematic expectations reflect probabilistic relationships between sensory events learned implicitly through exposure. Using...... in the literature. The results show that listeners experience greater uncertainty in high-entropy musical contexts than low-entropy contexts. This effect is particularly apparent for inferred uncertainty and is stronger in musicians than non-musicians. Consistent with the Statistical Learning Hypothesis...

  9. A computer model of auditory stream segregation.

    Science.gov (United States)

    Beauvois, M W; Meddis, R

    1991-08-01

    A computer model is described which simulates some aspects of auditory stream segregation. The model emphasizes the explanatory power of simple physiological principles operating at a peripheral rather than a central level. The model consists of a multi-channel bandpass-filter bank with a "noisy" output and an attentional mechanism that responds selectively to the channel with the greatest activity. A "leaky integration" principle allows channel excitation to accumulate and dissipate over time. The model produces similar results to two experimental demonstrations of streaming phenomena, which are presented in detail. These results are discussed in terms of the "emergent properties" of a system governed by simple physiological principles. As such the model is contrasted with higher-level Gestalt explanations of the same phenomena while accepting that they may constitute complementary kinds of explanation.

  10. Hearing Restoration with Auditory Brainstem Implant

    Science.gov (United States)

    NAKATOMI, Hirofumi; MIYAWAKI, Satoru; KIN, Taichi; SAITO, Nobuhito

    2016-01-01

    Auditory brainstem implant (ABI) technology attempts to restore hearing in deaf patients caused by bilateral cochlear nerve injury through the direct stimulation of the brainstem, but many aspects of the related mechanisms remain unknown. The unresolved issues can be grouped into three topics: which patients are the best candidates; which type of electrode should be used; and how to improve restored hearing. We evaluated our experience with 11 cases of ABI placement. We found that if at least seven of eleven electrodes of the MED-EL ABI are effectively placed in a patient with no deformation of the fourth ventricle, open set sentence recognition of approximately 20% and closed set word recognition of approximately 65% can be achieved only with the ABI. Appropriate selection of patients for ABI placement can lead to good outcomes. Further investigation is required regarding patient selection criteria and methods of surgery for effective ABI placement. PMID:27464470

  11. Changes of brainstem auditory and somatosensory evoked

    Institute of Scientific and Technical Information of China (English)

    Yang Jian

    2000-01-01

    Objective: to investigate the characteristics and clinical value of evoked potentials in late infantile form of metachromatic leukodystrophy. Methods: Brainstem auditory, and somatosensory evoked potentials were recorded in 6 patients, and compared with the results of CT scan. Results: All of the 6 patients had abnormal results of BAEP and MNSEP. The main abnormal parameters in BAEP were latency prolongation in wave I, inter-peak latency prolongation in Ⅰ-Ⅲ and Ⅰ-Ⅴ. The abnormal features of MNSEP were low amplitude and absence of wave N9, inter-Peak latency prolongation in Ng-N13 and N13-N20, but no significant change of N20 amplitude. The results also revealed that abnormal changes in BAEP and MNSEP were earlier than that in CT. Conclusion: The detection of BAEP and MNSEP in late infantile form of metachromatic leukodystrophy might early reveal the abnormality of conductive function in nervous system and might be a useful method in diagnosis.

  12. Discrimination of auditory stimuli during isoflurane anesthesia.

    Science.gov (United States)

    Rojas, Manuel J; Navas, Jinna A; Greene, Stephen A; Rector, David M

    2008-10-01

    Deep isoflurane anesthesia initiates a burst suppression pattern in which high-amplitude bursts are preceded by periods of nearly silent electroencephalogram. The burst suppression ratio (BSR) is the percentage of suppression (silent electroencephalogram) during the burst suppression pattern and is one parameter used to assess anesthesia depth. We investigated cortical burst activity in rats in response to different auditory stimuli presented during the burst suppression state. We noted a rapid appearance of bursts and a significant decrease in the BSR during stimulation. The BSR changes were distinctive for the different stimuli applied, and the BSR decreased significantly more when stimulated with a voice familiar to the rat as compared with an unfamiliar voice. These results show that the cortex can show differential sensory responses during deep isoflurane anesthesia.

  13. Low power adder based auditory filter architecture.

    Science.gov (United States)

    Rahiman, P F Khaleelur; Jayanthi, V S

    2014-01-01

    Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT) based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%.

  14. Resting Heart Rate and Auditory Evoked Potential

    Directory of Open Access Journals (Sweden)

    Simone Fiuza Regaçone

    2015-01-01

    Full Text Available The objective of this study was to evaluate the association between rest heart rate (HR and the components of the auditory evoked-related potentials (ERPs at rest in women. We investigated 21 healthy female university students between 18 and 24 years old. We performed complete audiological evaluation and measurement of heart rate for 10 minutes at rest (heart rate monitor Polar RS800CX and performed ERPs analysis (discrepancy in frequency and duration. There was a moderate negative correlation of the N1 and P3a with rest HR and a strong positive correlation of the P2 and N2 components with rest HR. Larger components of the ERP are associated with higher rest HR.

  15. Biomedical Simulation Models of Human Auditory Processes

    Science.gov (United States)

    Bicak, Mehmet M. A.

    2012-01-01

    Detailed acoustic engineering models that explore noise propagation mechanisms associated with noise attenuation and transmission paths created when using hearing protectors such as earplugs and headsets in high noise environments. Biomedical finite element (FE) models are developed based on volume Computed Tomography scan data which provides explicit external ear, ear canal, middle ear ossicular bones and cochlea geometry. Results from these studies have enabled a greater understanding of hearing protector to flesh dynamics as well as prioritizing noise propagation mechanisms. Prioritization of noise mechanisms can form an essential framework for exploration of new design principles and methods in both earplug and earcup applications. These models are currently being used in development of a novel hearing protection evaluation system that can provide experimentally correlated psychoacoustic noise attenuation. Moreover, these FE models can be used to simulate the effects of blast related impulse noise on human auditory mechanisms and brain tissue.

  16. Tonotopic organization of human auditory association cortex.

    Science.gov (United States)

    Cansino, S; Williamson, S J; Karron, D

    1994-11-07

    Neuromagnetic studies of responses in human auditory association cortex for tone burst stimuli provide evidence for a tonotopic organization. The magnetic source image for the 100 ms component evoked by the onset of a tone is qualitatively similar to that of primary cortex, with responses lying deeper beneath the scalp for progressively higher tone frequencies. However, the tonotopic sequence of association cortex in three subjects is found largely within the superior temporal sulcus, although in the right hemisphere of one subject some sources may be closer to the inferior temporal sulcus. The locus of responses for individual subjects suggests a progression across the cortical surface that is approximately proportional to the logarithm of the tone frequency, as observed previously for primary cortex, with the span of 10 mm for each decade in frequency being comparable for the two areas.

  17. Genetics of auditory mechano-electrical transduction.

    Science.gov (United States)

    Michalski, Nicolas; Petit, Christine

    2015-01-01

    The hair bundles of cochlear hair cells play a central role in the auditory mechano-electrical transduction (MET) process. The identification of MET components and of associated molecular complexes by biochemical approaches is impeded by the very small number of hair cells within the cochlea. In contrast, human and mouse genetics have proven to be particularly powerful. The study of inherited forms of deafness led to the discovery of several essential proteins of the MET machinery, which are currently used as entry points to decipher the associated molecular networks. Notably, MET relies not only on the MET machinery but also on several elements ensuring the proper sound-induced oscillation of the hair bundle or the ionic environment necessary to drive the MET current. Here, we review the most significant advances in the molecular bases of the MET process that emerged from the genetics of hearing.

  18. Predictive uncertainty in auditory sequence processing.

    Science.gov (United States)

    Hansen, Niels Chr; Pearce, Marcus T

    2014-01-01

    Previous studies of auditory expectation have focused on the expectedness perceived by listeners retrospectively in response to events. In contrast, this research examines predictive uncertainty-a property of listeners' prospective state of expectation prior to the onset of an event. We examine the information-theoretic concept of Shannon entropy as a model of predictive uncertainty in music cognition. This is motivated by the Statistical Learning Hypothesis, which proposes that schematic expectations reflect probabilistic relationships between sensory events learned implicitly through exposure. Using probability estimates from an unsupervised, variable-order Markov model, 12 melodic contexts high in entropy and 12 melodic contexts low in entropy were selected from two musical repertoires differing in structural complexity (simple and complex). Musicians and non-musicians listened to the stimuli and provided explicit judgments of perceived uncertainty (explicit uncertainty). We also examined an indirect measure of uncertainty computed as the entropy of expectedness distributions obtained using a classical probe-tone paradigm where listeners rated the perceived expectedness of the final note in a melodic sequence (inferred uncertainty). Finally, we simulate listeners' perception of expectedness and uncertainty using computational models of auditory expectation. A detailed model comparison indicates which model parameters maximize fit to the data and how they compare to existing models in the literature. The results show that listeners experience greater uncertainty in high-entropy musical contexts than low-entropy contexts. This effect is particularly apparent for inferred uncertainty and is stronger in musicians than non-musicians. Consistent with the Statistical Learning Hypothesis, the results suggest that increased domain-relevant training is associated with an increasingly accurate cognitive model of probabilistic structure in music.

  19. Effects of pitch on auditory number comparisons.

    Science.gov (United States)

    Campbell, Jamie I D; Scheepers, Florence

    2015-05-01

    Three experiments investigated interactions between auditory pitch and the numerical quantities represented by spoken English number words. In Experiment 1, participants heard a pair of sequential auditory numbers in the range zero to ten. They pressed a left-side or right-side key to indicate if the second number was lower or higher in numerical value. The vocal pitches of the two numbers either ascended or descended so that pitch change was congruent or incongruent with number change. The error rate was higher when pitch and number were incongruent relative to congruent trials. The distance effect on RT (i.e., slower responses for numerically near than far number pairs) occurred with pitch ascending but not descending. In Experiment 2, to determine if these effects depended on the left/right spatial mapping of responses, participants responded "yes" if the second number was higher and "no" if it was lower. Again, participants made more number comparison errors when number and pitch were incongruent, but there was no distance × pitch order effect. To pursue the latter, in Experiment 3, participants were tested with response buttons assigned left-smaller and right-larger ("normal" spatial mapping) or the reverse mapping. Participants who received normal mapping first presented a distance effect with pitch ascending but not descending as in Experiment 1, whereas participants who received reverse mapping first presented a distance effect with pitch descending but not ascending. We propose that the number and pitch dimensions of stimuli both activated spatial representations and that strategy shifts from quantity comparison to order processing were induced by spatial incongruities.

  20. Fatigue in neuromuscular disorders: focus on Guillain–Barré syndrome and Pompe disease

    OpenAIRE

    2009-01-01

    textabstractFatigue accounts for an important part of the burden experienced by patients with neuromuscular disorders. Substantial high prevalence rates of fatigue are reported in a wide range of neuromuscular disorders, such as Guillain-Barré syndrome and Pompe disease. Fatigue can be subdivided into experienced fatigue and physiological fatigue. Physiological fatigue in turn can be of central or peripheral origin. Peripheral fatigue is an important contributor to fatigue in neuromuscular di...

  1. Piezoelectric Bolt Breakers and Bolt Fatigue Testers

    Science.gov (United States)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Barengoltz, Jack; Heckman, Vanessa

    2008-01-01

    A proposed family of devices for inducing fatigue in bolts in order to break the bolts would incorporate piezoelectric actuators into resonant fixtures as in ultrasonic/ sonic drills/corers and similar devices described in numerous prior NASA Tech Briefs articles. These devices were originally intended primarily for use as safer, more-reliable, more-versatile alternatives to explosive bolts heretofore used to fasten spacecraft structures that must subsequently be separated from each other quickly on command during flight. On Earth, these devices could be used for accelerated fatigue testing of bolts. Fatigue theory suggests that a bolt subjected to both a constant-amplitude dynamic (that is, oscillatory) stress and a static tensile stress below the ultimate strength of the bolt material will fail faster than will a bolt subjected to only the dynamic stress. This suggestion would be applied in a device of the proposed type. The device would be designed so that the device and the bolt to be fatigue-tested or broken would be integral parts of an assembly (see figure). The static tension in the tightened bolt would apply not only the clamping force to hold the joined structures (if any) together but also the compression necessary for proper operation of the piezoelectric actuators as parts of a resonant structural assembly. The constant-amplitude dynamic stress would be applied to the bolt by driving the piezoelectric actuators with a sinusoidal voltage at the resonance frequency of longitudinal vibration of the assembly. The amplitude of the excitation would be made large enough so that the vibration would induce fatigue in the bolt within an acceptably short time. In the spacecraft applications or in similar terrestrial structural-separation applications, devices of the proposed type would offer several advantages over explosive bolts: Unlike explosive bolts, the proposed devices would be reusable, could be tested before final use, and would not be subject to

  2. Improving Fatigue Performance of AHSS Welds

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Yu, Xinghua [ORNL; ERDMAN III, DONALD L [ORNL; Wang, Yanli [ORNL; Kelly, Steve [ArcelorMittal USA; Hou, Wenkao [ArcelorMittal USA; Yan, Benda [ArcelorMittal USA; Wang, Zhifeng [Colorado School of Mines, Golden; Yu, Zhenzhen [Colorado School of Mines, Golden; Liu, Stephen [Colorado School of Mines, Golden

    2015-03-01

    Reported herein is technical progress on a U.S. Department of Energy CRADA project with industry cost-share aimed at developing the technical basis and demonstrate the viability of innovative in-situ weld residual stresses mitigation technology that can substantially improve the weld fatigue performance and durability of auto-body structures. The developed technology would be costeffective and practical in high-volume vehicle production environment. Enhancing weld fatigue performance would address a critical technology gap that impedes the widespread use of advanced high-strength steels (AHSS) and other lightweight materials for auto body structure light-weighting. This means that the automotive industry can take full advantage of the AHSS in strength, durability and crashworthiness without the concern of the relatively weak weld fatigue performance. The project comprises both technological innovations in weld residual stress mitigation and due-diligence residual stress measurement and fatigue performance evaluation. Two approaches were investigated. The first one was the use of low temperature phase transformation (LTPT) weld filler wire, and the second focused on novel thermo-mechanical stress management technique. Both technical approaches have resulted in considerable improvement in fatigue lives of welded joints made of high-strength steels. Synchrotron diffraction measurement confirmed the reduction of high tensile weld residual stresses by the two weld residual stress mitigation techniques.

  3. Fretting fatigue in AISI 1015 steel

    Indian Academy of Sciences (India)

    R Gnanamoorthy; R Rosi Reddy

    2002-04-01

    A small osillatory movement between two contacting surfaces is termed as fretting and on many occasions it acts as the crack initiation site leading to catastrophic failure of the overall structure. The occurrence of fretting is observed in many engineering structures such as shaft flanges, gas turbines, steel ropes etc. An experimental facility, which can simulate the fretting fatigue in many engineering applications, is the primary requirement of the research program. A laboratory fretting fatigue test facility capable of varying many influencing parameters of fretting fatigue such as slip amplitutde, frequency, contact pressure, etc is designed and developed. Preliminary investigations on plain and fretting fatigue behaviour of AISI 1015 structural steel are reported in this paper. A strength reduction factor of about 1.30 was obtained due to fretting for the test material under the present experimental conditions. Influence of contact load on fretting was also studied. Increasing fretting contact load decreased the fatigue life in the range investigated. Failure analysis showed typical stage I oblique crack growth followed by stage II straight crack perpedicular to the fretting zone.

  4. Neurocognitive impairment in childhood chronic fatigue syndrome

    Directory of Open Access Journals (Sweden)

    Kei eMizuno

    2013-04-01

    Full Text Available Neurocognitive impairment is a feature of childhood chronic fatigue syndrome (CCFS. Several studies have demonstrated reduced attention control in CCFS patients in switching and divided attention tasks. In students, the extent of deterioration in task performance depends on the level of fatigue. Poor performance in switching and divided attention is common in both fatigued students and CCFS patients. Additionally, attentional functions show dramatic development from childhood to adolescence, suggesting that abnormal development of switching and divided attention may be induced by chronic fatigue. The brain structures associated with attentional control are situated in the frontal and parietal cortices, which are the last to mature, suggesting that severe fatigue in CCFS patients and students may inhibit normal structural and functional development in these regions. A combination of treatment with cognitive behavioral therapy and antidepressant medication is effective to improve attentional control processing in CCFS patients. Studies identifying the features of neurocognitive impairment in CCFS have improved our current understanding of the neurophysiological mechanisms of CCFS.

  5. Thermal fatigue of electrical fuses

    Directory of Open Access Journals (Sweden)

    Gelet Jean-Louis

    2014-06-01

    Full Text Available Electric Fuses have to respect different national or international standards such as IEC (International Electro-technical Commission 269. These standards define the characteristics of the fuses and describe the tests to be run in order to check fuse's ability to take up their main functions, i.e. current-conduction and operation under overloads and short-circuits. But fuses never carry current neither operate under standardized conditions. For example, rated current is evaluated under specified ambient temperature, without cooling air-flow, and with 1 meter-long connection-cables on both sides. In the field, temperature can reach up 80∘C, with or without air-flow and connection-parts are much more shorter. An issue is that current is never constant, often being cyclingly applied; equipments are frequently in use during the day and stopped in the night. ON-time and OFF-time generate alternative heating, then alternative stresses leading to thermal fatigue. MERSEN run many tests along the years, allowing to develop a method for choosing right fuses for each application. As a result, fuses don't melt unexpectedly in the field, but the method is supposed to be conservative and does not permit to get a better understanding of the phenomena neither an improvement of the products. The paper presents some specific ageing-tests run on conductive elements and tries to establish a correspondence between these tests and others carried out on complete fuses. Tests have been run on silver and copper, but their principle could be interesting for any structural material, especially because it underlines crack-opening.

  6. Multiaxial fatigue crack path prediction using critical plane concept

    Directory of Open Access Journals (Sweden)

    Jafar Albinmousa

    2016-01-01

    Full Text Available Prediction of fatigue crack orientation can be an essential step for estimating fatigue crack path. Critical plane concept is widely used due to its physical basis that fatigue failure is associated with certain plane(s. However, recent investigations suggest that critical plane concept might need revision. In this paper, fatigue experiments that involve careful measurement of fatigue crack were reviewed. Predictions of fatigue crack orientation using critical plane concept were examined. Projected length and angle were used to characterize fatigue crack. Considering the entire fatigue life, this average representation suggests that it is more reasonable to assume the plane of maximum normal strain as the critical plane even though fundamentally the plane of maximum shear strain is more likely to be the critical one at early initiation stage.

  7. Macroscopic cumulative fatigue damage of material under nonsymmetrical cycle

    Institute of Scientific and Technical Information of China (English)

    盖秉政

    2002-01-01

    Hashin's macroscopic theory of fatigue damage is further discussed and a new method has been proposed for prediction of cumulative fatigue damage of material and its lifetime under nonsymmetrical cyclic loading.

  8. Impaired cognitive control and reduced cingulate activity during mental fatigue

    NARCIS (Netherlands)

    Lorist, MM; Boksem, MAS; Ridderinkhof, KR

    2005-01-01

    Neurocognitive mechanisms underlying the effects of mental fatigue are poorly understood. Here, we examined whether error-related brain activity, indexing performance monitoring by the anterior cingulate cortex (ACC), and strategic behavioural adjustments were modulated by mental fatigue, as induced

  9. Practical Guideline for Fatigue Management in Inflammatory Bowel Disease.

    Science.gov (United States)

    Kreijne, J E; Lie, M R K L; Vogelaar, L; van der Woude, C J

    2016-01-01

    During active inflammatory bowel disease (IBD) fatigue is a common symptom, which seems related to active gut inflammation. However, even in remission many patients suffer from fatigue that negatively affects quality of life and work productivity. Currently, robust knowledge on the pathogenesis and treatment of IBD-related fatigue is lacking. In order to alleviate the burden of IBD-related fatigue, a systematic approach is mandatory. We propose a fatigue attention cycle to enhance identification, evaluation and management of fatigued IBD patients. The benefits of the cycle are twofold. Firstly, it allows the systematic and uniform identification of patients with severe fatigue, in turn allowing tailored non-pharmacological and pharmacological interventions. Secondly, uniform identification of such patients creates a well-defined patient base to investigate the underlying pathogenesis of fatigue, resulting in a greater understanding of this debilitating phenomenon and possibly resulting in the discovery of predictive factors and new treatment interventions.

  10. Towards a unified fatigue life prediction method for marine structures

    CERN Document Server

    Cui, Weicheng; Wang, Fang

    2014-01-01

    In order to apply the damage tolerance design philosophy to design marine structures, accurate prediction of fatigue crack growth under service conditions is required. Now, more and more people have realized that only a fatigue life prediction method based on fatigue crack propagation (FCP) theory has the potential to explain various fatigue phenomena observed. In this book, the issues leading towards the development of a unified fatigue life prediction (UFLP) method based on FCP theory are addressed. Based on the philosophy of the UFLP method, the current inconsistency between fatigue design and inspection of marine structures could be resolved. This book presents the state-of-the-art and recent advances, including those by the authors, in fatigue studies. It is designed to lead the future directions and to provide a useful tool in many practical applications. It is intended to address to engineers, naval architects, research staff, professionals and graduates engaged in fatigue prevention design and survey ...

  11. Number of teeth and fatigue in older adults

    DEFF Research Database (Denmark)

    Avlund, Kirsten; Schultz-Larsen, Kirsten; Christiansen, Niels

    2011-01-01

    To examine whether tooth loss at age 70 is associated with fatigue in a nondisabled community-dwelling population cross-sectionally at age 70 and with onset of fatigue longitudinally at 5-, 10-, and 15-year follow-ups....

  12. Cancer Fatigue: Why It Occurs and How to Cope

    Science.gov (United States)

    ... side effects — such as anemia, nausea, vomiting, pain, insomnia and changes in mood — also may cause fatigue. ... is frequently interrupted, you may experience fatigue. Poor nutrition. In order to work efficiently, you need the ...

  13. The effect of exercise therapy on fatigue in multiple sclerosis

    DEFF Research Database (Denmark)

    Andreasen, A; Stenager, E; Dalgas, U

    2011-01-01

    Fatigue occurs in the majority of patients with multiple sclerosis (MS) and therapeutic possibilities are few. Exercise therapy is a therapeutic option but no studies have systematically reviewed the existing literature evaluating the effect of exercise therapy on MS fatigue....

  14. Fatigue in Steel Highway Bridges under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, J.A.; Vejrum, Tina

    1997-01-01

    In the present investigation, fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis.In the experimental part of the investigation, fatigue test series...... to one week's traffic loading, determined by means of strain gage measurements on the orthotropic steel deck structure of the Farø Bridges in Denmark.The test series which have been carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...... the fatigue test results and the fracture mechanics analysis indicate that the linear fatigue damage accumulation formula, which is normally used in the design against fatigue in steel bridges, may give results, which are unconservative. The validity of the results obtained from the linear fatigue damage...

  15. Statistical representation of sound textures in the impaired auditory system

    DEFF Research Database (Denmark)

    McWalter, Richard Ian; Dau, Torsten

    2015-01-01

    Many challenges exist when it comes to understanding and compensating for hearing impairment. Traditional methods, such as pure tone audiometry and speech intelligibility tests, offer insight into the deficiencies of a hearingimpaired listener, but can only partially reveal the mechanisms...... that underlie the hearing loss. An alternative approach is to investigate the statistical representation of sounds for hearing-impaired listeners along the auditory pathway. Using models of the auditory periphery and sound synthesis, we aimed to probe hearing impaired perception for sound textures – temporally...... homogenous sounds such as rain, birds, or fire. It has been suggested that sound texture perception is mediated by time-averaged statistics measured from early auditory representations (McDermott et al., 2013). Changes to early auditory processing, such as broader “peripheral” filters or reduced compression...

  16. Oscillatory Cortical Network Involved in Auditory Verbal Hallucinations in Schizophrenia

    NARCIS (Netherlands)

    van Lutterveld, Remko; Hillebrand, Arjan; Diederen, Kelly M. J.; Daalman, Kirstin; Kahn, Rene S.; Stam, Cornelis J.; Sommer, Iris E. C.

    2012-01-01

    Background: Auditory verbal hallucinations (AVH), a prominent symptom of schizophrenia, are often highly distressing for patients. Better understanding of the pathogenesis of hallucinations could increase therapeutic options. Magnetoencephalography (MEG) provides direct measures of neuronal activity

  17. Ion channel noise can explain firing correlation in auditory nerves.

    Science.gov (United States)

    Moezzi, Bahar; Iannella, Nicolangelo; McDonnell, Mark D

    2016-10-01

    Neural spike trains are commonly characterized as a Poisson point process. However, the Poisson assumption is a poor model for spiking in auditory nerve fibres because it is known that interspike intervals display positive correlation over long time scales and negative correlation over shorter time scales. We have therefore developed a biophysical model based on the well-known Meddis model of the peripheral auditory system, to produce simulated auditory nerve fibre spiking statistics that more closely match the firing correlations observed in empirical data. We achieve this by introducing biophysically realistic ion channel noise to an inner hair cell membrane potential model that includes fractal fast potassium channels and deterministic slow potassium channels. We succeed in producing simulated spike train statistics that match empirically observed firing correlations. Our model thus replicates macro-scale stochastic spiking statistics in the auditory nerve fibres due to modeling stochasticity at the micro-scale of potassium channels.

  18. Auditory hallucinations in childhood : associations with adversity and delusional ideation

    NARCIS (Netherlands)

    Bartels-Velthuis, A. A.; van de Willige, G.; Jenner, J. A.; Wiersma, D.; van Os, J.

    2012-01-01

    Background. Previous work suggests that exposure to childhood adversity is associated with the combination of delusions and hallucinations. In the present study, associations between (severity of) auditory vocal hallucinations (AVH) and (i) social adversity [traumatic experiences (TE) and stressful

  19. Modality specific neural correlates of auditory and somatic hallucinations

    Science.gov (United States)

    Shergill, S; Cameron, L; Brammer, M; Williams, S; Murray, R; McGuire, P

    2001-01-01

    Somatic hallucinations occur in schizophrenia and other psychotic disorders, although auditory hallucinations are more common. Although the neural correlates of auditory hallucinations have been described in several neuroimaging studies, little is known of the pathophysiology of somatic hallucinations. Functional magnetic resonance imaging (fMRI) was used to compare the distribution of brain activity during somatic and auditory verbal hallucinations, occurring at different times in a 36 year old man with schizophrenia. Somatic hallucinations were associated with activation in the primary somatosensory and posterior parietal cortex, areas that normally mediate tactile perception. Auditory hallucinations were associated with activation in the middle and superior temporal cortex, areas involved in processing external speech. Hallucinations in a given modality seem to involve areas that normally process sensory information in that modality.

 PMID:11606687

  20. Music and the auditory brain: where is the connection?

    Directory of Open Access Journals (Sweden)

    Israel eNelken

    2011-09-01

    Full Text Available Sound processing by the auditory system is understood in unprecedented details, even compared with sensory coding in the visual system. Nevertheless, we don't understand yet the way in which some of the simplest perceptual properties of sounds are coded in neuronal activity. This poses serious difficulties for linking neuronal responses in the auditory system and music processing, since music operates on abstract representations of sounds. Paradoxically, although perceptual representations of sounds most probably occur high in auditory system or even beyond it, neuronal responses are strongly affected by the temporal organization of sound streams even in subcortical stations. Thus, to the extent that music is organized sound, it is the organization, rather than the sound, which is represented first in the auditory brain.

  1. Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines

    Directory of Open Access Journals (Sweden)

    Sergio Márquez-Domínguez

    2012-06-01

    Full Text Available Consequences of failure of offshore wind turbines (OWTs is in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration of appropriate partial safety factors/Fatigue Design Factors (FDF for steel substructures for OWTs is the scope of this paper. A reliability-based approach is used and a probabilistic model has been developed, where design and limit state equations are established for fatigue failure. The strength and load uncertainties are described by stochastic variables. SN and fracture mechanics approaches are considered for to model the fatigue life. Further, both linear and bi-linear SN-curves are formulated and various approximations are investigated. The acceptable reliability level for fatigue failure of OWTs is discussed and results are presented for calibrated optimal fatigue design factors. Further, the influence of inspections is considered in order to extend and maintain a given target safety level.

  2. Interpolated twitches in fatiguing single mouse muscle fibres: implications for the assessment of central fatigue.

    Science.gov (United States)

    Place, Nicolas; Yamada, Takashi; Bruton, Joseph D; Westerblad, Håkan

    2008-06-01

    An electrically evoked twitch during a maximal voluntary contraction (twitch interpolation) is frequently used to assess central fatigue. In this study we used intact single muscle fibres to determine if intramuscular mechanisms could affect the force increase with the twitch interpolation technique. Intact single fibres from flexor digitorum brevis of NMRI mice were dissected and mounted in a chamber equipped with a force transducer. Free myoplasmic [Ca2+] ([Ca2+](i)) was measured with the fluorescent Ca2+ indicator indo-1. Seven fibres were fatigued with repeated 70 Hz tetani until 40% initial force with an interpolated pulse evoked every fifth tetanus. Results showed that the force generated by the interpolated twitch increased throughout fatigue, being 9 +/- 1% of tetanic force at the start and 19 +/- 1% at the end (P twitch during fatigue but rather to the fact that the force-[Ca2+](i) relationship is sigmoidal and fibres entered a steeper part of the relationship during fatigue. In another set of experiments, we observed that repeated tetani evoked at 150 Hz resulted in more rapid fatigue development than at 70 Hz and there was a decrease in force ('sag') during contractions, which was not observed at 70 Hz. In conclusion, the extent of central fatigue is difficult to assess and it may be overestimated when using the twitch interpolation technique.

  3. Adaptations to isolated shoulder fatigue during simulated repetitive work. Part I: Fatigue.

    Science.gov (United States)

    Tse, Calvin T F; McDonald, Alison C; Keir, Peter J

    2016-08-01

    Upper extremity muscle fatigue is challenging to identify during industrial tasks and places changing demands on the shoulder complex that are not fully understood. The purpose of this investigation was to examine adaptation strategies in response to isolated anterior deltoid muscle fatigue while performing simulated repetitive work. Participants completed two blocks of simulated repetitive work separated by an anterior deltoid fatigue protocol; the first block had 20 work cycles and the post-fatigue block had 60 cycles. Each work cycle was 60s in duration and included 4 tasks: handle pull, cap rotation, drill press and handle push. Surface EMG of 14 muscles and upper body kinematics were recorded. Immediately following fatigue, glenohumeral flexion strength was reduced, rating of perceived exertion scores increased and signs of muscle fatigue (increased EMG amplitude, decreased EMG frequency) were present in anterior and posterior deltoids, latissimus dorsi and serratus anterior. Along with other kinematic and muscle activity changes, scapular reorientation occurred in all of the simulated tasks and generally served to increase the width of the subacromial space. These findings suggest that immediately following fatigue people adapt by repositioning joints to maintain task performance and may also prioritize maintaining subacromial space width.

  4. Crohn's disease, fatigue, and infliximab: Is there a role for cytokines in the pathogenesis of fatigue?

    Institute of Scientific and Technical Information of China (English)

    Itta M Minderhoud; Melvin Samsom; Bas Oldenburg

    2007-01-01

    AIM: To study the effect of infliximab on fatigue in relation to cytokine levels in Crohn's disease (CD) patients.METHODS: Fourteen CD patients were blinded for treatment and received placebo at baseline, and infliximab 2 wk later, with a follow-up of 4 wk. Blood samples were drawn on a regular basis, and questionnaires on fatigue,depression, quality of life, and clinical disease activity were completed at regular intervals.RESULTS: After placebo infusion, fatigue scores decreased within 3 d (3.5 points + 1.1, P ≤ 0.01), but returned to baseline values 14 d after this infusion.The drop of fatigue scores following infliximab infusion sustained until the end of the study (3.8 points ± 1.4, P ≤ 0.05). Quality of life was increased at the end of the study compared to baseline values (138.6 ± 9.4 vs179.4+ 6.7; P ≤ 0.005), whereas depression scores were decreased (20.4 ± 9.4 vs11.3 + 2.2; P ≤ 0.01). No correlation between the severity of fatigue and the level of cytokines was observed.CONCLUSION: The reduction of fatigue after infliximab infusion is subjective to a placebo effect. The effect of infliximab on fatigue, however, persists while the placebo effect disappears after a short period of time. A clear role of cytokines could not be substantiated.

  5. Fatigue-Prone Details in Steel Bridges

    Directory of Open Access Journals (Sweden)

    Mohsen Heshmati

    2012-11-01

    Full Text Available This paper reviews the results of a comprehensive investigation including more than 100 fatigue damage cases, reported for steel and composite bridges. The damage cases are categorized according to types of detail. The mechanisms behind fatigue damage in each category are identified and studied. It was found that more than 90% of all reported damage cases are of deformation-induced type and generated by some kind of unintentional or otherwise overlooked interaction between different load-carrying members or systems in the bridge. Poor detailing, with unstiffened gaps and abrupt changes in stiffness at the connections between different members were also found to contribute to fatigue cracking in many details.

  6. Fatigue modeling of materials with complex microstructures

    DEFF Research Database (Denmark)

    Qing, Hai; Mishnaevsky, Leon

    2011-01-01

    A new approach and method of the analysis of microstructure-lifetime relationships of materials with complex structures is presented. The micromechanical multiscale computational analysis of damage evolution in materials with complex hierarchical microstructures is combined with the phenomenologi......A new approach and method of the analysis of microstructure-lifetime relationships of materials with complex structures is presented. The micromechanical multiscale computational analysis of damage evolution in materials with complex hierarchical microstructures is combined...... with the phenomenological model of fatigue damage growth. As a result, the fatigue lifetime of materials with complex structures can be determined as a function of the parameters of their structures. As an example, the fatigue lifetimes of wood modeled as a cellular material with multilayered, fiber reinforced walls were...

  7. Workload and operational fatigue in helicopter pilots.

    Science.gov (United States)

    Rotondo, G

    1978-02-01

    In light of the modern aetiopathogenic views, a brief review was made concerning possible causes of operational fatigue to which flying personnel in general are exposed in the exercise of flying activity. The author then describes and analyzes the meaning and importance of the various stressing factors that constitute the physical and psychic workload to which the helicopter pilot is subjected in performing his professional activities. Also analyzed are the influences exercised, both separately and jointly, on the genesis of flight fatigue in helicopter pilots by stressing and fatiguing effects of vibrations, noise, and psycho-emotional and psycho-sensorial factors related to the variety and danger of utilization of this modern aircraft. Such an analytical investigation enables the author to conclude that one must admit that helicopter piloting involves a psycho-physical workload certainly no less than that required by more powerful and faster aircraft.

  8. Computer Simulations of the Fatigue Crack Propagation

    Directory of Open Access Journals (Sweden)

    A. Materna

    2000-01-01

    Full Text Available The following hypothesis for design of structures based on the damage tolerance philosophy is laid down: the perpendicular fatigue crack growth rate v in a certain point of a curved crack front is given by the local value of stress intensity factor per unit of nominal stress K' and the local triaxiality T which describes the constraint. The relationship v = f (K', T is supposed to be typical for a given loading spectrum and material. Such relationship for a 2024 Al alloy and the flight-simulation spectrum was derived from the fatigue test of the rectangular panel with the central hole and used for three-dimensional simulation of the corner fatigue crack propagation in the model of the wing spar flangeplate. Finite element and boundary element methods were used for these computations. The results of the simulation are in good agreement with the experiment.

  9. Decreased basal ganglia activation in subjects with chronic fatigue syndrome: association with symptoms of fatigue.

    Directory of Open Access Journals (Sweden)

    Andrew H Miller

    Full Text Available Reduced basal ganglia function has been associated with fatigue in neurologic disorders, as well as in patients exposed to chronic immune stimulation. Patients with chronic fatigue syndrome (CFS have been shown to exhibit symptoms suggestive of decreased basal ganglia function including psychomotor slowing, which in turn was correlated with fatigue. In addition, CFS patients have been found to exhibit increased markers of immune activation. In order to directly test the hypothesis of decreased basal ganglia function in CFS, we used functional magnetic resonance imaging to examine neural activation in the basal ganglia to a reward-processing (monetary gambling task in a community sample of 59 male and female subjects, including 18 patients diagnosed with CFS according to 1994 CDC criteria and 41 non-fatigued healthy controls. For each subject, the average effect of winning vs. losing during the gambling task in regions of interest (ROI corresponding to the caudate nucleus, putamen, and globus pallidus was extracted for group comparisons and correlational analyses. Compared to non-fatigued controls, patients with CFS exhibited significantly decreased activation in the right caudate (p = 0.01 and right globus pallidus (p = 0.02. Decreased activation in the right globus pallidus was significantly correlated with increased mental fatigue (r2 = 0.49, p = 0.001, general fatigue (r2 = 0.34, p = 0.01 and reduced activity (r2 = 0.29, p = 0.02 as measured by the Multidimensional Fatigue Inventory. No such relationships were found in control subjects. These data suggest that symptoms of fatigue in CFS subjects were associated with reduced responsivity of the basal ganglia, possibly involving the disruption of projections from the globus pallidus to thalamic and cortical networks.

  10. Auditory short-term memory activation during score reading.

    Directory of Open Access Journals (Sweden)

    Veerle L Simoens

    Full Text Available Performing music on the basis of reading a score requires reading ahead of what is being played in order to anticipate the necessary actions to produce the notes. Score reading thus not only involves the decoding of a visual score and the comparison to the auditory feedback, but also short-term storage of the musical information due to the delay of the auditory feedback during reading ahead. This study investigates the mechanisms of encoding of musical information in short-term memory during such a complicated procedure. There were three parts in this study. First, professional musicians participated in an electroencephalographic (EEG experiment to study the slow wave potentials during a time interval of short-term memory storage in a situation that requires cross-modal translation and short-term storage of visual material to be compared with delayed auditory material, as it is the case in music score reading. This delayed visual-to-auditory matching task was compared with delayed visual-visual and auditory-auditory matching tasks in terms of EEG topography and voltage amplitudes. Second, an additional behavioural experiment was performed to determine which type of distractor would be the most interfering with the score reading-like task. Third, the self-reported strategies of the participants were also analyzed. All three parts of this study point towards the same conclusion according to which during music score reading, the musician most likely first translates the visual score into an auditory cue, probably starting around 700 or 1300 ms, ready for storage and delayed comparison with the auditory feedback.

  11. Contextual modulation of primary visual cortex by auditory signals

    Science.gov (United States)

    Paton, A. T.

    2017-01-01

    Early visual cortex receives non-feedforward input from lateral and top-down connections (Muckli & Petro 2013 Curr. Opin. Neurobiol. 23, 195–201. (doi:10.1016/j.conb.2013.01.020)), including long-range projections from auditory areas. Early visual cortex can code for high-level auditory information, with neural patterns representing natural sound stimulation (Vetter et al. 2014 Curr. Biol. 24, 1256–1262. (doi:10.1016/j.cub.2014.04.020)). We discuss a number of questions arising from these findings. What is the adaptive function of bimodal representations in visual cortex? What type of information projects from auditory to visual cortex? What are the anatomical constraints of auditory information in V1, for example, periphery versus fovea, superficial versus deep cortical layers? Is there a putative neural mechanism we can infer from human neuroimaging data and recent theoretical accounts of cortex? We also present data showing we can read out high-level auditory information from the activation patterns of early visual cortex even when visual cortex receives simple visual stimulation, suggesting independent channels for visual and auditory signals in V1. We speculate which cellular mechanisms allow V1 to be contextually modulated by auditory input to facilitate perception, cognition and behaviour. Beyond cortical feedback that facilitates perception, we argue that there is also feedback serving counterfactual processing during imagery, dreaming and mind wandering, which is not relevant for immediate perception but for behaviour and cognition over a longer time frame. This article is part of the themed issue ‘Auditory and visual scene analysis’. PMID:28044015

  12. Presentation of dynamically overlapping auditory messages in user interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Papp, III, Albert Louis [Univ. of California, Davis, CA (United States)

    1997-09-01

    This dissertation describes a methodology and example implementation for the dynamic regulation of temporally overlapping auditory messages in computer-user interfaces. The regulation mechanism exists to schedule numerous overlapping auditory messages in such a way that each individual message remains perceptually distinct from all others. The method is based on the research conducted in the area of auditory scene analysis. While numerous applications have been engineered to present the user with temporally overlapped auditory output, they have generally been designed without any structured method of controlling the perceptual aspects of the sound. The method of scheduling temporally overlapping sounds has been extended to function in an environment where numerous applications can present sound independently of each other. The Centralized Audio Presentation System is a global regulation mechanism that controls all audio output requests made from all currently running applications. The notion of multimodal objects is explored in this system as well. Each audio request that represents a particular message can include numerous auditory representations, such as musical motives and voice. The Presentation System scheduling algorithm selects the best representation according to the current global auditory system state, and presents it to the user within the request constraints of priority and maximum acceptable latency. The perceptual conflicts between temporally overlapping audio messages are examined in depth through the Computational Auditory Scene Synthesizer. At the heart of this system is a heuristic-based auditory scene synthesis scheduling method. Different schedules of overlapped sounds are evaluated and assigned penalty scores. High scores represent presentations that include perceptual conflicts between over-lapping sounds. Low scores indicate fewer and less serious conflicts. A user study was conducted to validate that the perceptual difficulties predicted by

  13. Visual change detection recruits auditory cortices in early deafness.

    Science.gov (United States)

    Bottari, Davide; Heimler, Benedetta; Caclin, Anne; Dalmolin, Anna; Giard, Marie-Hélène; Pavani, Francesco

    2014-07-01

    Although cross-modal recruitment of early sensory areas in deafness and blindness is well established, the constraints and limits of these plastic changes remain to be understood. In the case of human deafness, for instance, it is known that visual, tactile or visuo-tactile stimuli can elicit a response within the auditory cortices. Nonetheless, both the timing of these evoked responses and the functional contribution of cross-modally recruited areas remain to be ascertained. In the present study, we examined to what extent auditory cortices of deaf humans participate in high-order visual processes, such as visual change detection. By measuring visual ERPs, in particular the visual MisMatch Negativity (vMMN), and performing source localization, we show that individuals with early deafness (N=12) recruit the auditory cortices when a change in motion direction during shape deformation occurs in a continuous visual motion stream. Remarkably this "auditory" response for visual events emerged with the same timing as the visual MMN in hearing controls (N=12), between 150 and 300 ms after the visual change. Furthermore, the recruitment of auditory cortices for visual change detection in early deaf was paired with a reduction of response within the visual system, indicating a shift from visual to auditory cortices of part of the computational process. The present study suggests that the deafened auditory cortices participate at extracting and storing the visual information and at comparing on-line the upcoming visual events, thus indicating that cross-modally recruited auditory cortices can reach this level of computation.

  14. Auditory Temporal Resolution in Individuals with Diabetes Mellitus Type 2

    OpenAIRE

    2016-01-01

    Introduction “Diabetes mellitus is a group of metabolic disorders characterized by elevated blood sugar and abnormalities in insulin secretion and action” (American Diabetes Association). Previous literature has reported connection between diabetes mellitus and hearing impairment. There is a dearth of literature on auditory temporal resolution ability in individuals with diabetes mellitus type 2. Objective The main objective of the present study was to assess auditory temporal resolution a...

  15. Auditory stream formation affects comodulation masking release retroactively

    DEFF Research Database (Denmark)

    Dau, Torsten; Ewert, Stephan; Oxenham, A. J.

    2009-01-01

    in terms of the sequence of "postcursor" flanking bands forming a perceptual stream with the original flanking bands, resulting in perceptual segregation of the flanking bands from the masker. The results are consistent with the idea that modulation analysis occurs within, not across, auditory objects......, and that across-frequency CMR only occurs if the on-frequency and flanking bands fall within the same auditory object or stream....

  16. Auditory neuropathy spectrum disorder in a child with albinism

    Directory of Open Access Journals (Sweden)

    Mayur Bhat

    2016-01-01

    Full Text Available Albinism is a congenital disorder characterized by complete or partial absence of pigments in the skin, eyes, and hair due to the absence or defective melanin production. As a result of that, there will be disruption seen in auditory pathways along with other areas. Therefore, the aim of the present study is to highlight the underlying auditory neural deficits seen in albinism and discuss the role of audiologist in these cases.

  17. The plastic ear and perceptual relearning in auditory spatial perception.

    Science.gov (United States)

    Carlile, Simon

    2014-01-01

    The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear molds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10-60 days) performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localization, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear molds or through virtual auditory space stimulation using non-individualized spectral cues. The work with ear molds demonstrates that a relatively short period of training involving audio-motor feedback (5-10 days) significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide spatial cues but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis.

  18. Auditory hypersensitivity in children and teenagers with autistic spectrum disorder

    OpenAIRE

    2004-01-01

    OBJECTIVE: To verify if the clinical behavior of auditory hypersensitivity, reported in interviews with parents/caregivers and therapists/teachers of 46 children and teenagers suffering from autistic spectrum disorder, correspond to audiological findings. METHOD: The clinical diagnosis for auditory hypersensitivity was investigated by means of an interview. Subsequently, a test of the acoustic stapedial reflex was conducted, and responses to intense acoustic stimulus in open field were observ...

  19. Auditory stream segregation in children with Asperger syndrome

    OpenAIRE

    Lepistö, T.; Kuitunen, A.; Sussman, E.; Saalasti, S.; Jansson-Verkasalo, E. (Eira); Nieminen-von Wendt, T.; Kujala, T. (Tiia)

    2009-01-01

    Individuals with Asperger syndrome (AS) often have difficulties in perceiving speech in noisy environments. The present study investigated whether this might be explained by deficient auditory stream segregation ability, that is, by a more basic difficulty in separating simultaneous sound sources from each other. To this end, auditory event-related brain potentials were recorded from a group of school-aged children with AS and a group of age-matched controls using a paradigm specifically deve...

  20. Contextual modulation of primary visual cortex by auditory signals.

    Science.gov (United States)

    Petro, L S; Paton, A T; Muckli, L

    2017-02-19

    Early visual cortex receives non-feedforward input from lateral and top-down connections (Muckli & Petro 2013 Curr. Opin. Neurobiol. 23, 195-201. (doi:10.1016/j.conb.2013.01.020)), including long-range projections from auditory areas. Early visual cortex can code for high-level auditory information, with neural patterns representing natural sound stimulation (Vetter et al. 2014 Curr. Biol. 24, 1256-1262. (doi:10.1016/j.cub.2014.04.020)). We discuss a number of questions arising from these findings. What is the adaptive function of bimodal representations in visual cortex? What type of information projects from auditory to visual cortex? What are the anatomical constraints of auditory information in V1, for example, periphery versus fovea, superficial versus deep cortical layers? Is there a putative neural mechanism we can infer from human neuroimaging data and recent theoretical accounts of cortex? We also present data showing we can read out high-level auditory information from the activation patterns of early visual cortex even when visual cortex receives simple visual stimulation, suggesting independent channels for visual and auditory signals in V1. We speculate which cellular mechanisms allow V1 to be contextually modulated by auditory input to facilitate perception, cognition and behaviour. Beyond cortical feedback that facilitates perception, we argue that there is also feedback serving counterfactual processing during imagery, dreaming and mind wandering, which is not relevant for immediate perception but for behaviour and cognition over a longer time frame.This article is part of the themed issue 'Auditory and visual scene analysis'.

  1. Motor Training: Comparison of Visual and Auditory Coded Proprioceptive Cues

    Directory of Open Access Journals (Sweden)

    Philip Jepson

    2012-05-01

    Full Text Available Self-perception of body posture and movement is achieved through multi-sensory integration, particularly the utilisation of vision, and proprioceptive information derived from muscles and joints. Disruption to these processes can occur following a neurological accident, such as stroke, leading to sensory and physical impairment. Rehabilitation can be helped through use of augmented visual and auditory biofeedback to stimulate neuro-plasticity, but the effective design and application of feedback, particularly in the auditory domain, is non-trivial. Simple auditory feedback was tested by comparing the stepping accuracy of normal subjects when given a visual spatial target (step length and an auditory temporal target (step duration. A baseline measurement of step length and duration was taken using optical motion capture. Subjects (n=20 took 20 ‘training’ steps (baseline ±25% using either an auditory target (950 Hz tone, bell-shaped gain envelope or visual target (spot marked on the floor and were then asked to replicate the target step (length or duration corresponding to training with all feedback removed. Visual cues (mean percentage error=11.5%; SD ± 7.0%; auditory cues (mean percentage error = 12.9%; SD ± 11.8%. Visual cues elicit a high degree of accuracy both in training and follow-up un-cued tasks; despite the novelty of the auditory cues present for subjects, the mean accuracy of subjects approached that for visual cues, and initial results suggest a limited amount of practice using auditory cues can improve performance.

  2. The plastic ear and perceptual relearning in auditory spatial perception.

    Directory of Open Access Journals (Sweden)

    Simon eCarlile

    2014-08-01

    Full Text Available The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear moulds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10-60 days performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localisation, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear moulds or through virtual auditory space stimulation using non-individualised spectral cues. The work with ear moulds demonstrates that a relatively short period of training involving sensory-motor feedback (5 – 10 days significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide a spatial code but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis.

  3. Fatigue Crack Initiation and Propagation of Aluminum Alloy Bearings

    Institute of Scientific and Technical Information of China (English)

    CHENG Xian-Hua; MA Yan-Yan

    2004-01-01

    Observation of fatigue crack initiation and propagation during fatigue test in ALSn20Cu bearing has been presented. Journal center orbit, oil film pressure and stress distribution in alloy layer have been calculated and are taken as the basis for theoretically simulating the bearing fatigue process. It is found that the calculated results are in good accordance with the experimental results, which provides a feasible way for investigation of fatigue crack propagation process in the bearing.

  4. A predictive fatigue life model for anodized 7050 aluminium alloy

    OpenAIRE

    Chaussumier, Michel; Mabru, Catherine; Shahzad, Majid; Chieragatti, Rémy; Rezaï-Aria, Farhad

    2013-01-01

    International audience; The objective of this study is to predict fatigue life of anodized 7050 aluminum alloy specimens. In the case of anodized 7050-T7451 alloy, fractographic observations of fatigue tested specimens showed that pickling pits were the predominant sites for crack nucleation and subsequent failure. It has been shown that fatigue failure was favored by the presence of multiple cracks. From these experimental results, a fatigue life predictive model has been developed including...

  5. A unique cellular scaling rule in the avian auditory system.

    Science.gov (United States)

    Corfield, Jeremy R; Long, Brendan; Krilow, Justin M; Wylie, Douglas R; Iwaniuk, Andrew N

    2016-06-01

    Although it is clear that neural structures scale with body size, the mechanisms of this relationship are not well understood. Several recent studies have shown that the relationship between neuron numbers and brain (or brain region) size are not only different across mammalian orders, but also across auditory and visual regions within the same brains. Among birds, similar cellular scaling rules have not been examined in any detail. Here, we examine the scaling of auditory structures in birds and show that the scaling rules that have been established in the mammalian auditory pathway do not necessarily apply to birds. In galliforms, neuronal densities decrease with increasing brain size, suggesting that auditory brainstem structures increase in size faster than neurons are added; smaller brains have relatively more neurons than larger brains. The cellular scaling rules that apply to auditory brainstem structures in galliforms are, therefore, different to that found in primate auditory pathway. It is likely that the factors driving this difference are associated with the anatomical specializations required for sound perception in birds, although there is a decoupling of neuron numbers in brain structures and hair cell numbers in the basilar papilla. This study provides significant insight into the allometric scaling of neural structures in birds and improves our understanding of the rules that govern neural scaling across vertebrates.

  6. Temporal factors affecting somatosensory-auditory interactions in speech processing

    Directory of Open Access Journals (Sweden)

    Takayuki eIto

    2014-11-01

    Full Text Available Speech perception is known to rely on both auditory and visual information. However, sound specific somatosensory input has been shown also to influence speech perceptual processing (Ito et al., 2009. In the present study we addressed further the relationship between somatosensory information and speech perceptual processing by addressing the hypothesis that the temporal relationship between orofacial movement and sound processing contributes to somatosensory-auditory interaction in speech perception. We examined the changes in event-related potentials in response to multisensory synchronous (simultaneous and asynchronous (90 ms lag and lead somatosensory and auditory stimulation compared to individual unisensory auditory and somatosensory stimulation alone. We used a robotic device to apply facial skin somatosensory deformations that were similar in timing and duration to those experienced in speech production. Following synchronous multisensory stimulation the amplitude of the event-related potential was reliably different from the two unisensory potentials. More importantly, the magnitude of the event-related potential difference varied as a function of the relative timing of the somatosensory-auditory stimulation. Event-related activity change due to stimulus timing was seen between 160-220 ms following somatosensory onset, mostly around the parietal area. The results demonstrate a dynamic modulation of somatosensory-auditory convergence and suggest the contribution of somatosensory information for speech processing process is dependent on the specific temporal order of sensory inputs in speech production.

  7. [Analysis of auditory information in the brain of the cetacean].

    Science.gov (United States)

    Popov, V V; Supin, A Ia

    2006-01-01

    The cetacean brain specifics involve an exceptional development of the auditory neural centres. The place of projection sensory areas including the auditory that in the cetacean brain cortex is essentially different from that in other mammals. The EP characteristics indicated presence of several functional divisions in the auditory cortex. Physiological studies of the cetacean auditory centres were mainly performed using the EP technique. Of several types of the EPs, the short-latency auditory EP was most thoroughly studied. In cetacean, it is characterised by exceptionally high temporal resolution with the integration time about 0.3 ms which corresponds to the cut-off frequency 1700 Hz. This much exceeds the temporal resolution of the hearing in terranstrial mammals. The frequency selectivity of hearing in cetacean was measured using a number of variants of the masking technique. The hearing frequency selectivity acuity in cetacean exceeds that of most terraneous mammals (excepting the bats). This acute frequency selectivity provides the differentiation among the finest spectral patterns of auditory signals.

  8. Auditory Neuropathy: Findings of Behavioral, Physiological and Neurophysiological Tests

    Directory of Open Access Journals (Sweden)

    Mohammad Farhadi

    2006-12-01

    Full Text Available Background and Aim: Auditory neuropathy (AN can be diagnosed by abnormal auditory brainstem response (ABR, in the presence of normal cochlear microphonic (CM and otoacoustic emissions (OAEs.The aim of this study was to investigate the ABR and other electrodiagnostic test results of 6 patients suspicious to AN with problems in speech recognition. Materials and Methods: this cross sectional study was conducted on 6 AN patients with different ages evaluated by pure tone audiometry, speech discrimination score (SDS , immittance audiometry. ElectroCochleoGraphy , ABR, middle latency response (MLR, Late latency response (LLR, and OAEs. Results: Behavioral pure tone audiometric tests showed moderate to profound hearing loss. SDS was so poor which is not in accordance with pure tone thresholds. All patients had normal tympanogram but absent acoustic reflexes. CMs and OAEs were within normal limits. There was no contra lateral suppression of OAEs. None of cases had normal ABR or MLR although LLR was recorded in 4. Conclusion: All patients in this study are typical cases of auditory neuropathy. Despite having abnormal input, LLR remains normal that indicates differences in auditory evoked potentials related to required neural synchrony. These findings show that auditory cortex may play a role in regulating presentation of deficient signals along auditory pathways in primary steps.

  9. Auditory function in individuals within Leber's hereditary optic neuropathy pedigrees.

    Science.gov (United States)

    Rance, Gary; Kearns, Lisa S; Tan, Johanna; Gravina, Anthony; Rosenfeld, Lisa; Henley, Lauren; Carew, Peter; Graydon, Kelley; O'Hare, Fleur; Mackey, David A

    2012-03-01

    The aims of this study are to investigate whether auditory dysfunction is part of the spectrum of neurological abnormalities associated with Leber's hereditary optic neuropathy (LHON) and to determine the perceptual consequences of auditory neuropathy (AN) in affected listeners. Forty-eight subjects confirmed by genetic testing as having one of four mitochondrial mutations associated with LHON (mt11778, mtDNA14484, mtDNA14482 and mtDNA3460) participated. Thirty-two of these had lost vision, and 16 were asymptomatic at the point of data collection. While the majority of individuals showed normal sound detection, >25% (of both symptomatic and asymptomatic participants) showed electrophysiological evidence of AN with either absent or severely delayed auditory brainstem potentials. Abnormalities were observed for each of the mutations, but subjects with the mtDNA11778 type were the most affected. Auditory perception was also abnormal in both symptomatic and asymptomatic subjects, with >20% of cases showing impaired detection of auditory temporal (timing) cues and >30% showing abnormal speech perception both in quiet and in the presence of background noise. The findings of this study indicate that a relatively high proportion of individuals with the LHON genetic profile may suffer functional hearing difficulties due to neural abnormality in the central auditory pathways.

  10. An anatomical and functional topography of human auditory cortical areas.

    Science.gov (United States)

    Moerel, Michelle; De Martino, Federico; Formisano, Elia

    2014-01-01

    While advances in magnetic resonance imaging (MRI) throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla). Importantly, we illustrate that-whereas a group-based approach to analyze functional (tonotopic) maps is appropriate to highlight the main tonotopic axis-the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e., myelination) as well as of functional properties (e.g., broadness of frequency tuning) is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post-mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions.

  11. Left hemispheric dominance during auditory processing in a noisy environment

    Directory of Open Access Journals (Sweden)

    Ross Bernhard

    2007-11-01

    Full Text Available Abstract Background In daily life, we are exposed to different sound inputs simultaneously. During neural encoding in the auditory pathway, neural activities elicited by these different sounds interact with each other. In the present study, we investigated neural interactions elicited by masker and amplitude-modulated test stimulus in primary and non-primary human auditory cortex during ipsi-lateral and contra-lateral masking by means of magnetoencephalography (MEG. Results We observed significant decrements of auditory evoked responses and a significant inter-hemispheric difference for the N1m response during both ipsi- and contra-lateral masking. Conclusion The decrements of auditory evoked neural activities during simultaneous masking can be explained by neural interactions evoked by masker and test stimulus in peripheral and central auditory systems. The inter-hemispheric differences of N1m decrements during ipsi- and contra-lateral masking reflect a basic hemispheric specialization contributing to the processing of complex auditory stimuli such as speech signals in noisy environments.

  12. An anatomical and functional topography of human auditory cortical areas

    Directory of Open Access Journals (Sweden)

    Michelle eMoerel

    2014-07-01

    Full Text Available While advances in magnetic resonance imaging (MRI throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla. Importantly, we illustrate that - whereas a group-based approach to analyze functional (tonotopic maps is appropriate to highlight the main tonotopic axis - the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e. myelination as well as of functional properties (e.g. broadness of frequency tuning is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions.

  13. Influence of Auditory and Haptic Stimulation in Visual Perception

    Directory of Open Access Journals (Sweden)

    Shunichi Kawabata

    2011-10-01

    Full Text Available While many studies have shown that visual information affects perception in the other modalities, little is known about how auditory and haptic information affect visual perception. In this study, we investigated how auditory, haptic, or auditory and haptic stimulation affects visual perception. We used a behavioral task based on the subjects observing the phenomenon of two identical visual objects moving toward each other, overlapping and then continuing their original motion. Subjects may perceive the objects as either streaming each other or bouncing and reversing their direction of motion. With only visual motion stimulus, subjects usually report the objects as streaming, whereas if a sound or flash is played when the objects touch each other, subjects report the objects as bouncing (Bounce-Inducing Effect. In this study, “auditory stimulation”, “haptic stimulation” or “haptic and auditory stimulation” were presented at various times relative to the visual overlap of objects. Our result shows the bouncing rate when haptic and auditory stimulation were presented were the highest. This result suggests that the Bounce-Inducing Effect is enhanced by simultaneous modality presentation to visual motion. In the future, a neuroscience approach (eg, TMS, fMRI may be required to elucidate the brain mechanism in this study.

  14. Verrucous Carcinoma in External Auditory Canal – A Rare Case

    Directory of Open Access Journals (Sweden)

    Md Zillur Rahman

    2013-05-01

    Full Text Available Verrucous carcinoma is a variant of squamous cell carcinoma. It is of low grade malignancy and rarely present with distant metastasis. Oral cavity is the commonest site of this tumour, other sites are larynx, oesophagus and genitalia. Verrucous carcinoma in external auditory canal is extremely rare. This is the presentation of a 45 years old woman who came to the ENT & Head Neck Surgery department of Delta medical college, Dhaka, Bangladesh with discharging left ear and impairment of hearing on the same side for 7 years. Otoscopic examination showed a mass occupying almost whole of the external auditory canal and the overlying skin was thickened, papillary and blackish. Cytology from external auditory canal scrap showed hyperkeratosis and parakeratosis. External auditory canal bone was found eroded at some parts. Excision of the mass was done under microscope. Split thickness skin grafting was done in external auditory canal. The mass was diagnosed as verrucous carcinoma on histopathological examination. Afterwards she was given radiotherapy. Six months follow up showed no recurrence and healthy epithelialization of external auditory canal.

  15. Are chronic fatigue and chronic fatigue syndrome valid clinical entities across countries and health-care settings?

    NARCIS (Netherlands)

    Hickie, I.; Davenport, T.; Vernon, S.D.; Nisenbaum, R.; Reeves, W.C.; Hadzi-Pavlovic, D.; Lloyd, A.; Bleijenberg, G.; Werf, S.P. van der; Prins, J.B.; Blenkiron, P.M.; Buchwald, D.; Smith, W.R.; Edwards, R.; Lynch, S.; Kirmayer, L.J.; Taillefer, S.S.; Lee, S.; Martin, N.G.; Gillespie, N.E.; McIlvenny, S.; Sartorius, N.; Ustun, T.B.; Skapinakis, P.; Wessely, S.; Chalder, T.; Hotopf, M.; Nimnuan, C.; Candy, B.; Darbishire, L.; Ridsdale, L.; White, P.D.; Thomas, J.M.; Wilhelm, K.; Wilson, A.

    2009-01-01

    OBJECTIVE: The validity of the diagnosis of chronic fatigue syndrome and related chronic fatigue states remains controversial, particularly in psychiatry. This project utilized international epidemiological and clinical research data to test construct validity across diagnostic categories, health-ca

  16. [Chronic fatigue syndrome: biochemical examination of blood].

    Science.gov (United States)

    Hakariya, Yukiko; Kuratsune, Hirohiko

    2007-06-01

    Though patients with chronic fatigue syndrome (CFS) have lots of complaints, abnormal findings cannot be detected by biochemical screening tests. However, some specialized blood tests have revealed neuroendocrine immune axis abnormalities, which is closely associated with each other. Recent studies indicate that CFS can be understood as a special condition based on abnormality of the psycho-neuro-endocrino-immunological system, with the distinguishing feature of CFS seeming to be the secondary brain dysfunction caused by several cytokines and/or autoantibodies. In this paper, we summarize these abnormalities found in CFS and show the neuro-molecular mechanism leading to chronic fatigue.

  17. Compassion fatigue in military healthcare teams.

    Science.gov (United States)

    Owen, Regina Peterson; Wanzer, Linda

    2014-02-01

    Since the onset of the Iraq war and Afghanistan conflicts, military healthcare teams have had increasing exposure to the traumatic effects of caring for wounded warriors, leading to a phenomenon termed compassion fatigue. The purpose of this integrative review was to develop a proposed definition for compassion fatigue in support of these teams. There is no current standardized formal definition, and this lack of clarity can inhibit intervention. Seven main themes evolved from the literature review and were integrated with the core elements of the Bandura Social Cognitive Theory Model as the first step in developing a uniformed definition.

  18. Fatigue Performance of Fiber Reinforced Concrete

    DEFF Research Database (Denmark)

    Jun, Zhang; Stang, Henrik

    1996-01-01

    The objective of the present study is to obtain basic data of fibre reinforced concrete under fatigue load and to set up a theoretical model based on micromechanics. In this study, the bridging stress in fiber reinforced concrete under cyclic tensile load was investigted in details. The damage...... mechanism of the interface between fiber and matrix was proposed and a rational model given. Finally, the response of a steel fiber reinforced concrete beam under fatigue loading was predicted based on this model and compared with experimental results....

  19. The monotonic and fatigue behavior of CFCCs

    Energy Technology Data Exchange (ETDEWEB)

    Miriyala, N.; Liaw, P.K.; McHargue, C.J. [Univ. of Tennessee, Knoxville, TN (United States); Snead, L.L. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Flexure tests were performed to study the fabric orientation effects on the monotonic and fatigue behavior of two commercially available continuous fiber reinforced ceramic composites (CFCCs), namely (i) Nicalon fiber fabric reinforced alumina (Al{sub 2}O{sub 3}) matrix composite fabricated by a direct molten metal oxidation (DIMOX) process and, (ii) Nicalon fiber fabric reinforced silicon carbide (SiC) matrix composite fabricated by an isothermal chemical vapor infiltration (ICVI) process. The fabric orientation effects on the monotonic and fatigue behavior were strong in the Nicalon/Al{sub 2}O{sub 3} composite, while they were relatively weak in the Nicalon/SiC composite.

  20. Thermomechanical Multiaxial Fatigue Testing Capability Developed

    Science.gov (United States)

    1996-01-01

    Structural components in aeronautical gas turbine engines typically experience multiaxial states of stress under nonisothermal conditions. To estimate the durability of the various components in the engine, one must characterize the cyclic deformation and fatigue behavior of the materials used under thermal and complex mechanical loading conditions. To this end, a testing protocol and associated test control software were developed at the NASA Lewis Research Center for thermomechanical axial-torsional fatigue tests. These tests are to be performed on thin-walled, tubular specimens fabricated from the cobalt-based superalloy Haynes 188. The software is written in C and runs on an MS-DOS based microcomputer.