Bearingless helicopter main rotor development. Volume 2: Combined load fatigue evaluation of weathered graphite/epoxy composite

NASA Technical Reports Server (NTRS)

Rackiewicz, J. J.

1977-01-01

Small scale combined load fatigue tests were conducted on six artificially and six naturally weathered test specimens. The test specimen material was unidirectionally oriented A-S graphite - woven glass scrim epoxy resin laminate.

Feasibility, Validity, and Reliability of the Italian Pediatric Quality of Life Inventory Multidimensional Fatigue Scale for Adults in Inpatients with Severe Obesity.

PubMed

Manzoni, Gian Mauro; Rossi, Alessandro; Marazzi, Nicoletta; Agosti, Fiorenza; De Col, Alessandra; Pietrabissa, Giada; Castelnuovo, Gianluca; Molinari, Enrico; Sartorio, Allessandro

2018-01-01

This study was aimed to examine the feasibility, validity, and reliability of the Italian Pediatric Quality of Life Inventory Multidimensional Fatigue Scale (PedsQL™ MFS) for adult inpatients with severe obesity. 200 inpatients (81% females) with severe obesity (BMI ≥ 35 kg/m2) completed the PedsQL MFS (General Fatigue, Sleep/Rest Fatigue and Cognitive Fatigue domains), the Fatigue Severity Scale, and the Center for Epidemiologic Studies Depression Scale immediately after admission to a 3-week residential body weight reduction program. A randomized subsample of 48 patients re-completed the PedsQL MFS after 3 days. Confirmatory factor analysis showed that a modified hierarchical model with two items moved from the Sleep/Rest Fatigue domain to the General Fatigue domain and a second-order latent factor best fitted the data. Internal consistency and test-retest reliabilities were acceptable to high in all scales, and small to high statistically significant correlations were found with all convergent measures, with the exception of BMI. Significant floor effects were found in two scales (Cognitive Fatigue and Sleep/Rest Fatigue). The Italian modified PedsQL MFS for adults showed to be a valid and reliable tool for the assessment of fatigue in inpatients with severe obesity. Future studies should assess its discriminant validity as well as its responsiveness to weight reduction. © 2018 The Author(s) Published by S. Karger GmbH, Freiburg.

Validity and reliability of the Traditional Chinese version of the Multidimensional Fatigue Inventory in general population.

PubMed

Chuang, Li-Ling; Chuang, Yu-Fen; Hsu, Miao-Ju; Huang, Ying-Zu; Wong, Alice M K; Chang, Ya-Ju

2018-01-01

Fatigue is a common symptom in the general population and has a substantial effect on individuals' quality of life. The Multidimensional Fatigue Inventory (MFI) has been widely used to quantify the impact of fatigue, but no Traditional Chinese translation has yet been validated. The goal of this study was to translate the MFI from English into Traditional Chinese ('the MFI-TC') and subsequently to examine its validity and reliability. The study recruited a convenience sample of 123 people from various age groups in Taiwan. The MFI was examined using a two-step process: (1) translation and back-translation of the instrument; and (2) examination of construct validity, convergent validity, internal consistency, test-retest reliability, and measurement error. The validity and reliability of the MFI-TC were assessed by factor analysis, Spearman rho correlation coefficient, Cronbach's alpha coefficient, intraclass correlation coefficient (ICC), minimal detectable change (MDC), and Bland-Altman analysis. All participants completed the Short-Form-36 Health Survey Taiwan Form (SF-36-T) and the Chinese version of the Pittsburgh Sleep Quality Index (PSQI) concurrently to test the convergent validity of the MFI-TC. Test-retest reliability was assessed by readministration of the MFI-TC after a 1-week interval. Factor analysis confirmed the four dimensions of fatigue: general/physical fatigue, reduced activity, reduced motivation, and mental fatigue. A four-factor model was extracted, combining general fatigue and physical fatigue as one factor. The results demonstrated moderate convergent validity when correlating fatigue (MFI-TC) with quality of life (SF-36-T) and sleep disturbances (PSQI) (Spearman's rho = 0.68 and 0.47, respectively). Cronbach's alpha for the MFI-TC total scale and subscales ranged from 0.73 (mental fatigue subscale) to 0.92 (MFI-TC total scale). ICCs ranged from 0.85 (reduced motivation) to 0.94 (MFI-TC total scale), and the MDC ranged from 2.33 points (mental fatigue) to 9.5 points (MFI-TC total scale). The Bland-Altman analyses showed no significant systematic bias between the repeated assessments. The results support the use of the Traditional Chinese version of the MFI as a comprehensive instrument for measuring specific aspects of fatigue. Clinicians and researchers should consider interpreting general fatigue and physical fatigue as one subscale when measuring fatigue in Traditional Chinese-speaking populations.

Validity and reliability of the Traditional Chinese version of the Multidimensional Fatigue Inventory in general population

PubMed Central

Chuang, Li-Ling; Chuang, Yu-Fen; Hsu, Miao-Ju; Huang, Ying-Zu; Wong, Alice M. K.

2018-01-01

Background Fatigue is a common symptom in the general population and has a substantial effect on individuals’ quality of life. The Multidimensional Fatigue Inventory (MFI) has been widely used to quantify the impact of fatigue, but no Traditional Chinese translation has yet been validated. The goal of this study was to translate the MFI from English into Traditional Chinese (‘the MFI-TC’) and subsequently to examine its validity and reliability. Methods The study recruited a convenience sample of 123 people from various age groups in Taiwan. The MFI was examined using a two-step process: (1) translation and back-translation of the instrument; and (2) examination of construct validity, convergent validity, internal consistency, test-retest reliability, and measurement error. The validity and reliability of the MFI-TC were assessed by factor analysis, Spearman rho correlation coefficient, Cronbach’s alpha coefficient, intraclass correlation coefficient (ICC), minimal detectable change (MDC), and Bland-Altman analysis. All participants completed the Short-Form-36 Health Survey Taiwan Form (SF-36-T) and the Chinese version of the Pittsburgh Sleep Quality Index (PSQI) concurrently to test the convergent validity of the MFI-TC. Test-retest reliability was assessed by readministration of the MFI-TC after a 1-week interval. Results Factor analysis confirmed the four dimensions of fatigue: general/physical fatigue, reduced activity, reduced motivation, and mental fatigue. A four-factor model was extracted, combining general fatigue and physical fatigue as one factor. The results demonstrated moderate convergent validity when correlating fatigue (MFI-TC) with quality of life (SF-36-T) and sleep disturbances (PSQI) (Spearman's rho = 0.68 and 0.47, respectively). Cronbach’s alpha for the MFI-TC total scale and subscales ranged from 0.73 (mental fatigue subscale) to 0.92 (MFI-TC total scale). ICCs ranged from 0.85 (reduced motivation) to 0.94 (MFI-TC total scale), and the MDC ranged from 2.33 points (mental fatigue) to 9.5 points (MFI-TC total scale). The Bland-Altman analyses showed no significant systematic bias between the repeated assessments. Conclusions The results support the use of the Traditional Chinese version of the MFI as a comprehensive instrument for measuring specific aspects of fatigue. Clinicians and researchers should consider interpreting general fatigue and physical fatigue as one subscale when measuring fatigue in Traditional Chinese-speaking populations. PMID:29746466

Scaling phenomena in fatigue and fracture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barenblatt, G.I.

2004-12-01

The general classification of scaling laws will be presented and the basic concepts of modern similarity analysis--intermediate asymptotics, complete and incomplete similarity--will be introduced and discussed. The examples of scaling laws corresponding to complete similarity will be given. The Paris scaling law in fatigue will be discussed as an instructive example of incomplete similarity. It will be emphasized that in the Paris law the powers are not the material constants. Therefore, the evaluation of the life-time of structures using the data obtained from standard fatigue tests requires some precautions.

Construct validity of the Swedish version of the revised piper fatigue scale in an oncology sample--a Rasch analysis.

PubMed

Lundgren-Nilsson, Asa; Dencker, Anna; Jakobsson, Sofie; Taft, Charles; Tennant, Alan

2014-06-01

Fatigue is a common and distressing symptom in cancer patients due to both the disease and its treatments. The concept of fatigue is multidimensional and includes both physical and mental components. The 22-item Revised Piper Fatigue Scale (RPFS) is a multidimensional instrument developed to assess cancer-related fatigue. This study reports on the construct validity of the Swedish version of the RPFS from the perspective of Rasch measurement. The Swedish version of the RPFS was answered by 196 cancer patients fatigued after 4 to 5 weeks of curative radiation therapy. Data from the scale were fitted to the Rasch measurement model. This involved testing a series of assumptions, including the stochastic ordering of items, local response dependency, and unidimensionality. A series of fit statistics were computed, differential item functioning (DIF) was tested, and local response dependency was accommodated through testlets. The Behavioral, Affective and Sensory domains all satisfied the Rasch model expectations. No DIF was observed, and all domains were found to be unidimensional. The Mood/Cognitive scale failed to fit the model, and substantial multidimensionality was found. Splitting the scale between Mood and Cognitive items resolved fit to the Rasch model, and new domains were unidimensional without DIF. The current Rasch analyses add to the evidence of measurement properties of the scale and show that the RPFS has good psychometric properties and works well to measure fatigue. The original four-factor structure, however, was not supported. Copyright © 2014 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

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

PubMed

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 aspects of fatigue of the population of interest are covered.

The Development and Preliminary Testing of an Instrument for Assessing Fatigue Self-management Outcomes in Patients With Advanced Cancer.

PubMed

Chan, Raymond Javan; Yates, Patsy; McCarthy, Alexandra L

Fatigue is one of the most distressing and commonly experienced symptoms in patients with advanced cancer. Although the self-management (SM) of cancer-related symptoms has received increasing attention, no research instrument assessing fatigue SM outcomes for patients with advanced cancer is available. The aim of this study was to describe the development and preliminary testing of an interviewer-administered instrument for assessing the frequency and perceived levels of effectiveness and self-efficacy associated with fatigue SM behaviors in patients with advanced cancer. The development and testing of the Self-efficacy in Managing Symptoms Scale-Fatigue Subscale for Patients With Advanced Cancer (SMSFS-A) involved a number of procedures: item generation using a comprehensive literature review and semistructured interviews, content validity evaluation using expert panel reviews, and face validity and test-retest reliability evaluation using pilot testing. Initially, 23 items (22 specific behaviors with 1 global item) were generated from the literature review and semistructured interviews. After 2 rounds of expert panel review, the final scale was reduced to 17 items (16 behaviors with 1 global item). Participants in the pilot test (n = 10) confirmed that the questions in this scale were clear and easy to understand. Bland-Altman analysis showed agreement of results over a 1-week interval. The SMSFS-A items were generated using multiple sources. This tool demonstrated preliminary validity and reliability. The SMSFS-A has the potential to be used for clinical and research purposes. Nurses can use this instrument for collecting data to inform the initiation of appropriate fatigue SM support for this population.

Fatigue analysis and testing of wind turbine blades

NASA Astrophysics Data System (ADS)

Greaves, Peter Robert

This thesis focuses on fatigue analysis and testing of large, multi MW wind turbine blades. The blades are one of the most expensive components of a wind turbine, and their mass has cost implications for the hub, nacelle, tower and foundations of the turbine so it is important that they are not unnecessarily strong. Fatigue is often an important design driver, but fatigue of composites is poorly understood and so large safety factors are often applied to the loads. This has implications for the weight of the blade. Full scale fatigue testing of blades is required by the design standards, and provides manufacturers with confidence that the blade will be able to survive its service life. This testing is usually performed by resonating the blade in the flapwise and edgewise directions separately, but in service these two loads occur at the same time.. A fatigue testing method developed at Narec (the National Renewable Energy Centre) in the UK in which the flapwise and edgewise directions are excited simultaneously has been evaluated by comparing the Palmgren-Miner damage sum around the blade cross section after testing with the damage distribution caused by the service life. A method to obtain the resonant test configuration that will result in the optimum mode shapes for the flapwise and edgewise directions was then developed, and simulation software was designed to allow the blade test to be simulated so that realistic comparisons between the damage distributions after different test types could be obtained. During the course of this work the shortcomings with conventional fatigue analysis methods became apparent, and a novel method of fatigue analysis based on multi-continuum theory and the kinetic theory of fracture was developed. This method was benchmarked using physical test data from the OPTIDAT database and was applied to the analysis of a complete blade. A full scale fatigue test method based on this new analysis approach is also discussed..

Psychometric Properties of the Fatigue Severity Scale in Polio Survivors

ERIC Educational Resources Information Center

Burger, Helena; Franchignoni, Franco; Puzic, Natasa; Giordano, Andrea

2010-01-01

The objective of this study was to evaluate by means of classical test theory and Rasch analysis the scaling characteristics and psychometric properties of the Fatigue Severity Scale (FSS) in polio survivors. A questionnaire, consisting of five general questions (sex, age, age at time of acute polio, sequelae of polio, and new symptoms), the FSS,…

Fatigue Damage Assessment Leveraging Nondestructive Evaluation Data

NASA Astrophysics Data System (ADS)

Mazur, K.; Wisner, B.; Kontsos, A.

2018-05-01

Fatigue in materials depends on several microstructural parameters. The length and time scales involved in such processes have been investigated by characterization methods that target microstructural effects or that rely on specimen-level observations. Combinations of in situ and ex situ techniques are also used to correlate microstructural changes to bulk properties. We present herein an effort to directly link local changes with specimen-level fatigue damage assessment. To achieve this goal, grain-scale observations in an aluminum alloy are linked with deformation measurements made by digital image correlation and with acoustic emission monitoring obtained from inside the scanning electron microscope. Damage assessment is attempted using a data-processing framework that involves noise removal, data reduction, and classification. The results demonstrate that nondestructive evaluation combined with small-scale testing can provide a means for fatigue damage assessment applicable to a broad range of materials and testing conditions.

Structural Area Inspection Frequency Evaluation (SAIFE). Volume III. Demonstration Input, Inspection Survey, and MRR Data

DTIC Science & Technology

1978-04-01

3 1.7 Production Rate Change Time . . . . 3 1.8 Time of Fatigue Test Start . ..... 3 1.9 Fatigue Test Acceleration Factor . 3 1.10 Corrosion...simulation logic. SAIFE accounts for the following factors : (1) aircraft design analysis; (2) component and full-scale fatigue testing; (3) production ...reliability; production , servi ce,Information Service, Springfield, and corrosion defects; crack or corrosi on Virginia 22151 detection probability; crack

A psychometric study of the multidimensional fatigue inventory to assess fatigue in patients with schizophrenia spectrum disorders.

PubMed

Hedlund, Lena; Gyllensten, Amanda Lundvik; Hansson, Lars

2015-04-01

Fatigue is frequently reported by patients with mental illness. The multidimensional fatigue inventory (MFI-20) is a self-assessment instrument with 20 items including five dimensions of fatigue. The purpose of this study was to examine the test-retest reliability, internal consistency, convergent construct validity and feasibility of using MFI-20 in patients with schizophrenia spectrum disorders. Patients completed two self-assessment instruments, MFI-20 (n = 93) and Visual Analogue Scale (n = 79), twice within 1 week ± 2 days. Fifty-three patients also rated the feasibility of responding to the MFI-20 with a Likert scale. The test-retest reliability and validity were analysed by using Spearman's correlations and internal consistency by calculating Cronbach's α. The test-retest showed a correlation between .66 and .91 for all subscales of MFI. The internal consistency was .92. The analysis of convergent construct validity showed a correlation of .68 (time 1) and .77 (time 2). No item was systematically identified as being difficult to answer.

Fatigue in children: reliability and validity of the Dutch PedsQL™ Multidimensional Fatigue Scale.

PubMed

Gordijn, M Suzanne; Suzanne Gordijn, M; Cremers, Eline M P; Kaspers, Gertjan J L; Gemke, Reinoud J B J

2011-09-01

The aim of the study is to report on the feasibility, reliability, validity, and the norm-references of the Dutch version of the PedsQL™ Multidimensional Fatigue Scale. The study participants are four hundred and ninety-seven parents of children aged 2-18 years and 366 children aged 5-18 years from various day care facilities, elementary schools, and a high school who completed the Dutch version of the PedsQL™ Multidimensional Fatigue Scale. The number of missing items was minimal. All scales showed satisfactory internal consistency reliability, with Cronbach's coefficient alpha exceeding 0.70. Test-retest reliability was good to excellent (ICCs 0.68-0.84) and inter-observer reliability varied from moderate to excellent (ICCs 0.56-0.93) for total scores. Parent/child concordance for total scores was poor to good (ICCs 0.25-0.68). The PedsQL™ Multidimensional Fatigue Scale was able to distinguish between healthy children and children with an impaired health condition. The Dutch version of the PedsQL™ Multidimensional Fatigue Scale demonstrates an adequate feasibility, reliability, and validity in another sociocultural context. With the obtained norm-references, it can be utilized as a tool in the evaluation of fatigue in healthy and chronically ill children aged 2-18 years.

Association among measures of mobility-related disability and self-perceived fatigue among older people: a population-based study

PubMed Central

Soares, Wuber J. S.; Lima, Camila A.; Bilton, Tereza L.; Ferrioli, Eduardo; Dias, Rosângela C.; Perracini, Monica R.

2015-01-01

Objective: To investigate the relationship between self-perceived fatigue with different physical functioning tests and functional performance scales used for evaluating mobility-related disability among community-dwelling older persons. Method: This is a cross-sectional, population-based study. The sample was composed of older persons with 65 years of age or more living in Cuiabá, MT, and Barueri, SP, Brazil. The data for this study is from the FIBRA Network Study. The presence of self-perceived fatigue was assessed using self-reports based on the Center for Epidemiologic Studies-Depression Scale. The Lawton instrumental activities of daily living scale (IADL) and the advanced activities of daily living scale (AADL) were used to assess performance and participation restriction. The following physical functioning tests were used: five-step test (FST), the Short Physical Performance Battery (SPPB), and usual gait speed (UGS). Three models of logistic regression analysis were conducted, and a significance level of α<0.05 was adopted. Results: The sample was composed of 776 older adults with a mean age (SD) of 71.9 (5.9) years, of whom the majority were women (74%). The prevalence of self-perceived fatigue within the participants was 20%. After adjusting for covariates, SPPB, UGS, IADL, and AADL remained associated with self-perceived fatigue in the final multivariate regression model. Conclusion: Our results suggest that there is an association between self-perceived fatigue and lower extremity function, usual gait speed and activity limitation and participation restriction in older adults. Further cohort studies are needed to investigate which physical performance measure may be able to predict the negative impact of fatigue in older adults. PMID:26039035

Development and validation of a fatigue assessment scale for U.S. construction workers.

PubMed

Zhang, Mingzong; Sparer, Emily H; Murphy, Lauren A; Dennerlein, Jack T; Fang, Dongping; Katz, Jeffrey N; Caban-Martinez, Alberto J

2015-02-01

To develop a fatigue assessment scale and test its reliability and validity for commercial construction workers. Using a two-phased approach, we first identified items (first phase) for the development of a Fatigue Assessment Scale for Construction Workers (FASCW) through review of existing scales in the scientific literature, key informant interviews (n = 11) and focus groups (three groups with six workers each) with construction workers. The second phase included assessment for the reliability, validity, and sensitivity of the new scale using a repeated-measures study design with a convenience sample of construction workers (n = 144). Phase one resulted in a 16-item preliminary scale that after factor analysis yielded a final 10-item scale with two sub-scales ("Lethargy" and "Bodily Ailment"). During phase two, the FASCW and its subscales demonstrated satisfactory internal consistency (alpha coefficients were FASCW [0.91], Lethargy [0.86] and Bodily Ailment [0.84]) and acceptable test-retest reliability (Pearson Correlations Coefficients: 0.59-0.68; Intraclass Correlation Coefficients: 0.74-0.80). Correlation analysis substantiated concurrent and convergent validity. A discriminant analysis demonstrated that the FASCW differentiated between groups with arthritis status and different work hours. The 10-item FASCW with good reliability and validity is an effective tool for assessing the severity of fatigue among construction workers. © 2015 Wiley Periodicals, Inc.

OTEC riser cable model and prototype testing

NASA Astrophysics Data System (ADS)

Kurt, J. P.; Schultz, J. A.; Roblee, L. H. S.

1981-12-01

Two different OTEC riser cables have been developed to span the distance between a floating OTEC power plant and the ocean floor. The major design concerns for a riser cable in the dynamic OTEC environment are fatigue, corrosion, and electrical/mechanical aging of the cable components. The basic properties of the cable materials were studied through tests on model cables and on samples of cable materials. Full-scale prototype cables were manufactured and were tested to measure their electrical and mechanical properties and performance. The full-scale testing was culminated by the electrical/mechanical fatigue test, which exposes full-scale cables to simultaneous tension, bending and electrical loads, all in a natural seawater environment.

Is the impact of fatigue related to walking capacity and perceived ability in persons with multiple sclerosis? A multicenter study.

PubMed

Dalgas, U; Langeskov-Christensen, M; Skjerbæk, A; Jensen, E; Baert, I; Romberg, A; Santoyo Medina, C; Gebara, B; Maertens de Noordhout, B; Knuts, K; Béthoux, F; Rasova, K; Severijns, D; Bibby, B M; Kalron, A; Norman, B; Van Geel, F; Wens, I; Feys, P

2018-04-15

The relationship between fatigue impact and walking capacity and perceived ability in patients with multiple sclerosis (MS) is inconclusive in the existing literature. A better understanding might guide new treatment avenues for fatigue and/or walking capacity in patients with MS. To investigate the relationship between the subjective impact of fatigue and objective walking capacity as well as subjective walking ability in MS patients. A cross-sectional multicenter study design was applied. Ambulatory MS patients (n = 189, age: 47.6 ± 10.5 years; gender: 115/74 women/men; Expanded Disability Status Scale (EDSS): 4.1 ± 1.8 [range: 0-6.5]) were tested at 11 sites. Objective tests of walking capacity included short walking tests (Timed 25-Foot Walk (T25FW), 10-Metre Walk Test (10mWT) at usual and fastest speed and the timed up and go (TUG)), and long walking tests (2- and 6-Minute Walk Tests (MWT). Subjective walking ability was tested applying the Multiple Sclerosis Walking Scale-12 (MSWS-12). Fatigue impact was measured by the self-reported modified fatigue impact scale (MFIS) consisting of a total score (MFIS total ) and three subscales (MFIS physical , MFIS cognitive and MFIS psychosocial ). Uni- and multivariate regression analysis were performed to evaluate the relation between walking and fatigue impact. MFIS total was negatively related with long (6MWT, r = -0.14, p = 0.05) and short composite (TUG, r = -0.22, p = 0.003) walking measures. MFIS physical showed a significant albeit weak relationship to walking speed in all walking capacity tests (r = -0.22 to -0.33, p < .0001), which persisted in the multivariate linear regression analysis. Subjective walking ability (MSWS-12) was related to MFIS total (r = 0.49, p < 0.0001), as well as to all other subscales of MFIS (r = 0.24-0.63, p < 0.001), showing stronger relationships than objective measures of walking. The physical impact of fatigue is weakly related to objective walking capacity, while general, physical, cognitive and psychosocial fatigue impact are weakly to moderately related to subjective walking ability, when analysed in a large heterogeneous sample of MS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Ferrographic analysis of wear debris from full-scale bearing fatigue tests

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Loewenthal, S. H.

1979-01-01

The Ferrograph was used to determine the types and quantities of wear particles generated during full scale bearing fatigue tests. Deep-groove ball bearings made from steel were used. A tetraester lubricant was used in a recirculating lubricant system containing a 49 micrometers absolute filter. Test conditions include a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm, and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the Ferrograph was more sensitive (up to 23 hr) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis. Four particle types were observed: normal rubbing weather particles, spheres, nonferrous particles, and severe wear (spall) fragments.

Analysis of wear-debris from full-scale bearing fatigue tests using the ferrograph

NASA Technical Reports Server (NTRS)

Jones, W. R.; Loewenthal, S. H.

1980-01-01

The ferrograph was used to determine the types and quantities of wear particles generated during full-scale bearing fatigue tests. Deep-groove ball bearings made from AISI 52100 steel were used. A MIL-L-23699 tetraester lubricant was used in a recirculating lubrication system containing a 49 mm absolute filter. Test conditions included a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm, and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the ferrograph was more sensitive (up to 23 hr) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis. Four particle types were observed: normal rubbing wear particles, spheres, nonferrous particles, and severe wear (spall) fragments.

Oxidation- and Creep-Enhanced Fatigue of Haynes 188 Alloy-Oxide Scale System Under Simulated Pulse Detonation Engine Conditions

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Miller, Robert A.

2002-01-01

The development of the pulse detonation engine (PDE) requires robust design of the engine components that are capable of enduring harsh detonation environments. In this study, a high cycle thermal fatigue test rig was developed for evaluating candidate PDE combustor materials using a CO2 laser. The high cycle thermal fatigue behavior of Haynes 188 alloy was investigated under an enhanced pulsed laser test condition of 30 Hz cycle frequency (33 ms pulse period, and 10 ms pulse width including 0.2 ms pulse spike). The temperature swings generated by the laser pulses near the specimen surface were characterized by using one-dimensional finite difference modeling combined with experimental measurements. The temperature swings resulted in significant thermal cyclic stresses in the oxide scale/alloy system, and induced extensive surface cracking. Striations of various sizes were observed at the cracked surfaces and oxide/alloy interfaces under the cyclic stresses. The test results indicated that oxidation and creep-enhanced fatigue at the oxide scale/alloy interface was an important mechanism for the surface crack initiation and propagation under the simulated PDE condition.

Occupation-specific screening for future sickness absence: criterion validity of the trucker strain monitor (TSM).

PubMed

De Croon, Einar M; Blonk, Roland W B; Sluiter, Judith K; Frings-Dresen, Monique H W

2005-02-01

Monitoring psychological job strain may help occupational physicians to take preventive action at the appropriate time. For this purpose, the 10-item trucker strain monitor (TSM) assessing work-related fatigue and sleeping problems in truck drivers was developed. This study examined (1) test-retest reliability, (2) criterion validity of the TSM with respect to future sickness absence due to psychological health complaints and (3) usefulness of the TSM two-scales structure. The TSM and self-administered questionnaires, providing information about stressful working conditions (job control and job demands) and sickness absence, were sent to a random sample of 2000 drivers in 1998. Of the 1123 responders, 820 returned a completed questionnaire 2 years later (response: 72%). The TSM work-related fatigue scale, the TSM sleeping problems scale and the TSM composite scale showed satisfactory 2-year test-retest reliability (coefficient r=0.62, 0.66 and 0.67, respectively). The work-related fatigue, sleeping problems scale and composite scale had sensitivities of 61, 65 and 61%, respectively in identifying drivers with future sickness absence due to psychological health complaints. The specificity and positive predictive value of the TSM composite scale were 77 and 11%, respectively. The work-related fatigue scale and the sleeping problems scale were moderately strong correlated (r=0.62). However, stressful working conditions were differentially associated with the two scales. The results support the test-retest reliability, criterion validity and two-factor structure of the TSM. In general, the results suggest that the use of occupation-specific psychological job strain questionnaires is fruitful.

Validation of an Arabic version of Fatigue Severity Scale

PubMed Central

Al-Sobayel, Hana I.; Al-Hugail, Hind A.; AlSaif, Ranyah M.; Albawardi, Nada M.; Alnahdi, Ali H.; Daif, Abdulkader M.; Al-Arfaj, Hussein F.

2016-01-01

Objectives: To develop and test the psychometric properties of an Arabic version of Fatigue Severity Scale (FSS-Ar) that can be used to measure fatigue in Arabic patients with disorders where fatigue is a major symptom. Methods: Forward and backward translations of FSS were undertaken to develop an Arabic version. The validity and reliability of the FSS-Ar was then tested on 28 patients with systemic lupus erythematosus (SLE), 24 patients with multiple sclerosis (MS), and 31 healthy subjects. Exploratory factor analysis and hypothesis testing methods were used to examine construct validity. The correlation between FSS-Ar and the vitality domain of the RAND 36-Item Health was examined to test construct validity. The study was conducted at the King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia between February and June 2012. Results: Using a score of ≥4.05 to define fatigue, 39 of 52 (75%) participants were fatigued compared with 10 out of 31 (32%) healthy participants. The correlation between the FSS-Ar and the vitality domain of the RAND-36 was acceptable (r = -0.46). Factor analysis showed that items of the FSS-Ar measured one underlying construct, namely, fatigue. Test-retest reliability and internal consistency of the FSS-Ar was acceptable (intraclass correlation coefficient model 2,1 = 0.80; Cronbach’s alpha = 0.84). Conclusion: The Arabic version of the FSS demonstrated acceptable psychometric properties and was able to differentiate between patients with SLE or MS, and healthy subjects. PMID:26739978

Very high-cycle fatigue failure in micron-scale polycrystalline silicon films: Effects of environment and surface oxide thickness

NASA Astrophysics Data System (ADS)

Alsem, D. H.; Timmerman, R.; Boyce, B. L.; Stach, E. A.; De Hosson, J. Th. M.; Ritchie, R. O.

2007-01-01

Fatigue failure in micron-scale polycrystalline silicon structural films, a phenomenon that is not observed in bulk silicon, can severely impact the durability and reliability of microelectromechanical system devices. Despite several studies on the very high-cycle fatigue behavior of these films (up to 1012cycles), there is still an on-going debate on the precise mechanisms involved. We show here that for devices fabricated in the multiuser microelectromechanical system process (MUMPs) foundry and Sandia Ultra-planar, Multi-level MEMS Technology (SUMMiT V™) process and tested under equi-tension/compression loading at ˜40kHz in different environments, stress-lifetime data exhibit similar trends in fatigue behavior in ambient room air, shorter lifetimes in higher relative humidity environments, and no fatigue failure at all in high vacuum. The transmission electron microscopy of the surface oxides in the test samples shows a four- to sixfold thickening of the surface oxide at stress concentrations after fatigue failure, but no thickening after overload fracture in air or after fatigue cycling in vacuo. We find that such oxide thickening and premature fatigue failure (in air) occur in devices with initial oxide thicknesses of ˜4nm (SUMMiT V™) as well as in devices with much thicker initial oxides ˜20nm (MUMPs). Such results are interpreted and explained by a reaction-layer fatigue mechanism. Specifically, moisture-assisted subcritical cracking within a cyclic stress-assisted thickened oxide layer occurs until the crack reaches a critical size to cause catastrophic failure of the entire device. The entirety of the evidence presented here strongly indicates that the reaction-layer fatigue mechanism is the governing mechanism for fatigue failure in micron-scale polycrystalline silicon thin films.

Associations of perceived social support and positive psychological resources with fatigue symptom in patients with rheumatoid arthritis

PubMed Central

Xu, NeiLi; Zhao, Shuai; Xue, HongXia; Fu, WenYi; Liu, Li; Zhang, TianQi; Huang, Rui; Zhang, Ning

2017-01-01

Objective This study aimed to assess the association between perceived social support (PSS) and fatigue and the roles of hope, optimism, general self-efficacy and resilience as mediators or moderators on PSS-fatigue association among Rheumatoid Arthritis (RA) patients in China. Methods A multi-center, cross-sectional study was conducted withinpatients diagnosed with RA in northeast China, in which 305 eligible inpatients were enrolled. The Multidimensional Fatigue Inventory, Multidimensional Scale of Perceived Social Support, Herth Hope Index, Life Orientation Test Revised, General Self-Efficacy Scale and Ego-Resiliency Scale were completed. The associations of PSS, hope, optimism, general self-efficacy and resilience with fatigue and the moderating roles of these positive psychological constructs were tested by hierarchical linear regression. Asymptotic and resampling strategies were utilized to assess the mediating roles of hope, optimism, general self-efficacy and resilience. Results The mean score of the MFI was 57.88 (SD = 9.50). PSS, hope, optimism and resilience were negatively associated with RA-related fatigue, whereas DAS28-CRP was positively associated. Only resilience positively moderated the PSS-fatigue association (B = 0.03, β = 0.13, P<0.01). Hope, optimism and resilience may act as partial mediators in the association between PSS and fatigue symptoms (hope: a*b = -0.16, BCa 95%CI: -0.27, -0.03; optimism: a*b = -0.20, BCa 95%CI: -0.30, -0.10; resilience: a*b = -0.12, BCa 95%CI: -0.21–0.04). Conclusions Fatigue is a severe symptom among RA patients. Resilience may positively moderate the PSS-fatigue association. Hope, optimism and resilience may act as partial mediators in the association. PSS, hope, optimism and resilience may contribute as effective recourses to alleviate fatigue, upon which PSS probably has the greatest effect. PMID:28291837

Associations of perceived social support and positive psychological resources with fatigue symptom in patients with rheumatoid arthritis.

PubMed

Xu, NeiLi; Zhao, Shuai; Xue, HongXia; Fu, WenYi; Liu, Li; Zhang, TianQi; Huang, Rui; Zhang, Ning

2017-01-01

This study aimed to assess the association between perceived social support (PSS) and fatigue and the roles of hope, optimism, general self-efficacy and resilience as mediators or moderators on PSS-fatigue association among Rheumatoid Arthritis (RA) patients in China. A multi-center, cross-sectional study was conducted withinpatients diagnosed with RA in northeast China, in which 305 eligible inpatients were enrolled. The Multidimensional Fatigue Inventory, Multidimensional Scale of Perceived Social Support, Herth Hope Index, Life Orientation Test Revised, General Self-Efficacy Scale and Ego-Resiliency Scale were completed. The associations of PSS, hope, optimism, general self-efficacy and resilience with fatigue and the moderating roles of these positive psychological constructs were tested by hierarchical linear regression. Asymptotic and resampling strategies were utilized to assess the mediating roles of hope, optimism, general self-efficacy and resilience. The mean score of the MFI was 57.88 (SD = 9.50). PSS, hope, optimism and resilience were negatively associated with RA-related fatigue, whereas DAS28-CRP was positively associated. Only resilience positively moderated the PSS-fatigue association (B = 0.03, β = 0.13, P<0.01). Hope, optimism and resilience may act as partial mediators in the association between PSS and fatigue symptoms (hope: a*b = -0.16, BCa 95%CI: -0.27, -0.03; optimism: a*b = -0.20, BCa 95%CI: -0.30, -0.10; resilience: a*b = -0.12, BCa 95%CI: -0.21-0.04). Fatigue is a severe symptom among RA patients. Resilience may positively moderate the PSS-fatigue association. Hope, optimism and resilience may act as partial mediators in the association. PSS, hope, optimism and resilience may contribute as effective recourses to alleviate fatigue, upon which PSS probably has the greatest effect.

An index for breathlessness and leg fatigue.

PubMed

Borg, E; Borg, G; Larsson, K; Letzter, M; Sundblad, B-M

2010-08-01

The features of perceived symptoms causing discontinuation of strenuous exercise have been scarcely studied. The aim was to characterize the two main symptoms causing the discontinuation of heavy work in healthy persons as well as describe the growth of symptoms during exercise. Breathlessness (b) and leg fatigue (l) were assessed using the Borg CR10 Scale and the Borg CR100 (centiMax) Scale, during a standardized exercise test in 38 healthy subjects (24-71 years). The b/l-relationships were calculated for terminal perceptions (ERI(b/l)), and the growth of symptoms determined by power functions for the whole test, as well as by growth response indexes (GRI). This latter index was constructed as a ratio between power levels corresponding to a very strong and a moderate perception. In the majority (71%) of the test subjects, leg fatigue was the dominant symptom at the conclusion of exercise (P<0.001) and the b/l ratio was 0.77 (CR10) and 0.75 (CR100), respectively. The GRI for breathlessness and leg fatigue was similar, with good correlations between GRI and the power function exponent (P<0.005). In healthy subjects, leg fatigue is the most common cause for discontinuing an incremental exercise test. The growth functions for breathlessness and leg fatigue during work are, however, almost parallel.

Dynamic MEMS devices for multi-axial fatigue and elastic modulus measurement

NASA Astrophysics Data System (ADS)

White, Carolyn D.; Xu, Rui; Sun, Xiaotian; Komvopoulos, Kyriakos

2003-01-01

For reliable MEMS device fabrication and operation, there is a continued demand for precise characterization of materials at the micron scale. This paper presents a novel material characterization device for fatigue lifetime testing. The fatigue specimen is subjected to multi-axial loading, which is typical of most MEMS devices. Polycrystalline silicon (polysilicon) fatigue devices were fabricated using the MUMPS process with a three layer mask process ground plane, anchor, and structural layer of polysilicon. A fatigue device consists of two or three beams, attached to a rotating ring and anchored to the substrate on each end. In order to generate a sufficiently large stress, the fatigue devices were tested in resonance to produce a von Mises equivalent stress as high as 1 GPa, which is in the fracture strength range reported for polysilicon. A further increase of the stress in the beam specimens was obtained by introducing a notch with a focused ion beam. The notch resulted into a stress concentration factor of about 3.8, thereby producing maximum von Mises equivalent stress in the range of 1 through 4 GPa. This study provides insight into multi-axial fatigue testing under typical MEMS conditions and additional information about micron-scale polysilicon mechanical behavior, which is the current basic building material for MEMS devices.

A tension-torsional fatigue testing apparatus for micro-scale components.

PubMed

Fu, Sichao; Wang, Lei; Chen, Gang; Yu, Dunji; Chen, Xu

2016-01-01

Mechanical characterization of micro-scale components under complex loading conditions is a great challenge. To meet such a challenge, a microtension-torsional fatigue testing apparatus is developed in this study that specializes in the evaluation of multiaxial fatigue behavior of thin stent wires. The actuation and measurement in two controlled directions are incorporated in the tensile and torsional load frames, respectively, and a thrust air bearing is applied for the coupling of the two frames. The axial deformation of specimens measured by a grating sensor built in the linear motor and by a non-contact displacement detect system is compared and corrected. The accuracy of the torque measurement is proved by torsion tests on thin wires of 316L stainless steel in nominal diameters of 100 μm. Multistep torsion test, multiaxial ratcheting test, and a fully strain controlled multiaxial cyclic test are performed on 100 μm and 200 μm-diameter 316L wires using this apparatus. The capability of the equipment in tension-torsional cyclic tests for micro-scale specimens is demonstrated by the experimental results.

A tension-torsional fatigue testing apparatus for micro-scale components

NASA Astrophysics Data System (ADS)

Fu, Sichao; Wang, Lei; Chen, Gang; Yu, Dunji; Chen, Xu

2016-01-01

Mechanical characterization of micro-scale components under complex loading conditions is a great challenge. To meet such a challenge, a microtension-torsional fatigue testing apparatus is developed in this study that specializes in the evaluation of multiaxial fatigue behavior of thin stent wires. The actuation and measurement in two controlled directions are incorporated in the tensile and torsional load frames, respectively, and a thrust air bearing is applied for the coupling of the two frames. The axial deformation of specimens measured by a grating sensor built in the linear motor and by a non-contact displacement detect system is compared and corrected. The accuracy of the torque measurement is proved by torsion tests on thin wires of 316L stainless steel in nominal diameters of 100 μm. Multistep torsion test, multiaxial ratcheting test, and a fully strain controlled multiaxial cyclic test are performed on 100 μm and 200 μm-diameter 316L wires using this apparatus. The capability of the equipment in tension-torsional cyclic tests for micro-scale specimens is demonstrated by the experimental results.

Development of a clinician-administered National Institutes of Health-Brief Fatigue Inventory: A measure of fatigue in the context of depressive disorders.

PubMed

Saligan, Leorey N; Luckenbaugh, David A; Slonena, Elizabeth E; Machado-Vieira, Rodrigo; Zarate, Carlos A

2015-09-01

Fatigue is a complex, multidimensional condition. Although it is often associated with depression, it is not known whether it has a distinct network from depression or whether it can be clinically evaluated, separately. This study describes preliminary findings in the development of a brief, clinician-administered instrument to measure fatigue in the context of depressive disorders using items from existing clinician-administered depression and mania scales. Based on items from prior fatigue measurements, items were selected from the Hamilton Depression Rating Scale (HDRS), Montgomery-Asberg Depression Rating Scale (MADRS), Young Mania Rating Scale, and Structured Interview Guide for HDRS with Atypical Depression. The final items composed the NIH-Brief Fatigue Inventory (NIH-BFI). Responses from 89 depressed adults collected pre- and post-antidepressant therapy (ADT) determined the reliability and consistency of the NIH-BFI using Cronbach's alpha and principal components analysis (PCA). Correlations of the NIH-BFI and fatigue items from other scales before and after ADT explored validity. The 7-item NIH-BFI had Cronbach alphas ranging from 0.81 to 0.88 and PCA indicating a single dimension. The NIH-BFI score was strongly correlated (r = 0.73, p < 0.001) with fatigue items from Beck Depression Index, with MADRS without fatigue items (r = 0.77, p < 0.001), and HDRS without fatigue items (pre: r = 0.69, p < 0.001). Preliminary findings show support for internal consistency reliability and validity of the NIH-BFI, a clinician-administered measure of fatigue. Further testing in other clinical populations is recommended to obtain additional information on reliability and validity. The NIH-BFI provides a method for clinician-rated fatigue that may be a separate from depression. Published by Elsevier Ltd.

Explanatory factors and predictors of fatigue in persons with rheumatoid arthritis: A longitudinal study.

PubMed

Feldthusen, Caroline; Grimby-Ekman, Anna; Forsblad-d'Elia, Helena; Jacobsson, Lennart; Mannerkorpi, Kaisa

2016-04-28

To investigate the impact of disease-related aspects on long-term variations in fatigue in persons with rheumatoid arthritis. Observational longitudinal study. Sixty-five persons with rheumatoid arthritis, age range 20-65 years, were invited to a clinical examination at 4 time-points during the 4 seasons. Outcome measures were: general fatigue rated on visual analogue scale (0-100) and aspects of fatigue assessed by the Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire. Disease-related variables were: disease activity (erythrocyte sedimentation rate), pain threshold (pressure algometer), physical capacity (six-minute walk test), pain (visual analogue scale (0-100)), depressive mood (Hospital Anxiety and Depression scale, depression subscale), personal factors (age, sex, body mass index) and season. Multivariable regression analysis, linear mixed effects models were applied. The strongest explanatory factors for all fatigue outcomes, when recorded at the same time-point as fatigue, were pain threshold and depressive mood. Self-reported pain was an explanatory factor for physical aspects of fatigue and body mass index contributed to explaining the consequences of fatigue on everyday living. For predicting later fatigue pain threshold and depressive mood were the strongest predictors. Pain threshold and depressive mood were the most important factors for fatigue in persons with rheumatoid arthritis.

Fatigue in patients with Juvenile Idiopathic Arthritis: relationship to perceived health, physical health, self-efficacy, and participation.

PubMed

Armbrust, Wineke; Lelieveld, Otto H T M; Tuinstra, Jolanda; Wulffraat, Nico M; Bos, G J F Joyce; Cappon, Jeannette; van Rossum, Marion A J; Sauer, Pieter J J; Hagedoorn, Mariët

2016-12-06

Fatigue is common in patients with JIA and affects daily life negatively. We assessed the presence and severity of fatigue in patients with JIA, including factors presumed associated with fatigue (e.g., disease activity, disability, pain, physical activity, exercise capacity, and self-efficacy), and whether fatigue is related to participation in physical education classes, school attendance, and sports frequency. The current study used baseline data of 80 patients with JIA (age 8-13) who participated in an intervention aimed at promoting physical activity. Primary outcome measurements were fatigue, assessed using the Pediatric-Quality-of-Life-Inventory (PedsQl)-Fatigue-scale and energy level assessed using a VAS scale. Other outcome measurements were disease activity (VAS Physician Global Assessment Scale), disability (Childhood Health Assessment Questionnaire), physical activity (accelerometer), exercise capacity (Bruce treadmill test), self-efficacy (Childhood Arthritis Self-Efficacy Scale), and participation (self-report). Sixty percent of patients with JIA suffered from daily low-energy levels; 27% suffered from very low-energy levels more than half the week. Low energy levels were best predicted by disability and low physical activity. Fatigue measured with the PEDsQL was higher compared to the control-population. Disability and low self-efficacy were main predictors of fatigue. Self-efficacy was a predictor of fatigue but did not act as moderator. Fatigue was a predictor for sports frequency but not for school attendance. Fatigue is a significant problem for JIA patients. Interventions aimed at reducing perceived disability, stimulating physical activity, and enhancing self-efficacy might reduce fatigue and thereby enhance participation. Trial number ISRCTN92733069.

Development of load spectra for Airbus A330/A340 full scale fatigue tests

NASA Technical Reports Server (NTRS)

Schmidt, H.-J.; Nielsen, Thomas

1994-01-01

For substantiation of the recently certified medium range Airbus A330 and long range A340 the full scale fatigue tests are in progress. The airframe structures of both aircraft types are tested by one set of A340 specimens. The development of the fatigue test spectra for the two major test specimens which are the center fuselage and wing test and the rear fuselage test is described. The applied test load spectra allow a realistic simulation of flight, ground and pressurization loads and the finalization of the tests within the pre-defined test period. The paper contains details about the 1 g and incremental flight and ground loads and the establishment of the flight-by-flight test program, i.e., the definition of flight types, distribution of loads within the flights and randomization of flight types in repeated blocks. Special attention is given to procedures applied for acceleration of the tests, e.g. omission of lower spectrum loads and a general increase of all loads by ten percent.

A proposed USAF fatigue evaluation program based upon recent systems experience

NASA Technical Reports Server (NTRS)

Haviland, G. P.; Purkey, G. F.

1972-01-01

The United States Air Force has published a document entitled Aircraft Structural Integrity Program. One phase of the program is concerned with the fatigue life certification of all types of military aircraft. The document describes the criteria, analyses, and tests that are necessary in order to satisfy the USAF fatigue life requirement. Some recent and valid criticism has been directed toward the document, particularly the fatigue-life requirements contained in it. Some changes are proposed based on surveys conducted in the United States and abroad as well as some recent systems' experience. The surveys covered both military and civilian organizations. The fatigue certification case histories of selected military and commercial aircraft are presented. The design development element tests, preproduction design verification tests, and full-scale fatigue tests of each are described. A brief status report on the revisions to the MIL-A-008860 series specifications is included.

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

PubMed Central

2011-01-01

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. PMID:21672212

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

PubMed

Mizuno, Kei; Tanaka, Masaaki; Fukuda, Sanae; Yamano, Emi; Shigihara, Yoshihito; Imai-Matsumura, Kyoko; Watanabe, Yasuyoshi

2011-06-14

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. 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. 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. Reduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students. © 2011 Mizuno et al; licensee BioMed Central Ltd.

Preliminary metallographic studies of ball fatigue under rolling-contact conditions

NASA Technical Reports Server (NTRS)

Bear, H Robert; Butler, Robert H

1957-01-01

The metallurgical results produced on balls tested in the rolling-contact fatigue spin rig were studied by metallographic examination. Origin and progression of fatigue failures were observed. These evaluations were made on SAE 52100 and AISI M-1 balls fatigue tested at room temperature (80 F) and 200 to 250 F. Most failures originated subsurface in shear; inclusions, structure changes, and directionalism adversely affected ball fatigue life. Structures in the maximum-shear-stress region of the balls of both materials were stable at room temperature and unstable at 200 to 250 F. Failures were of the same type as those found in full-scale bearings.

Real-Time Assessment of Fatigue in Patients With Multiple Sclerosis: How Does It Relate to Commonly Used Self-Report Fatigue Questionnaires?

PubMed

Heine, Martin; van den Akker, Lizanne Eva; Blikman, Lyan; Hoekstra, Trynke; van Munster, Erik; Verschuren, Olaf; Visser-Meily, Anne; Kwakkel, Gert

2016-11-01

(1) To assess real-time patterns of fatigue; (2) to assess the association between a real-time fatigue score and 3 commonly used questionnaires (Checklist Individual Strength [CIS] fatigue subscale, Modified Fatigue Impact Scale (MFIS), and Fatigue Severity Scale [FSS]); and (3) to establish factors that confound the association between the real-time fatigue score and the conventional fatigue questionnaires in patients with multiple sclerosis (MS). Cross-sectional study. MS-specialized outpatient facility. Ambulant patients with MS (N=165) experiencing severe self-reported fatigue. Not applicable. A real-time fatigue score was assessed by sending participants 4 text messages on a particular day (How fatigued do you feel at this moment?; score range, 0-10). Latent class growth mixed modeling was used to determine diurnal patterns of fatigue. Regression analyses were used to assess the association between the mean real-time fatigue score and the CIS fatigue subscale, MFIS, and FSS. Significant associations were tested for candidate confounders (eg, disease severity, work status, sleepiness). Four significantly different fatigue profiles were identified by the real-time fatigue score, namely a stable high (n=79), increasing (n=57), stable low (n=16), and decreasing (n=13). The conventional questionnaires correlated poorly (r<.300) with the real-time fatigue score. The Epworth Sleepiness Scale significantly reduced the regression coefficient between the real-time fatigue score and conventional questionnaires, ranging from 15.4% to 35%. Perceived fatigue showed 4 different diurnal patterns in patients with MS. Severity of sleepiness is an important confounder to take into account in the assessment of fatigue. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Analysis of wear debris from full-scale bearing fatigue tests using the Ferrograph

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Loewenthal, S. H.

1980-01-01

The Ferrograph was used to determine the types of quantities of wear particles generated during full-scale bearing fatigue tests. Deep-groove ball bearings made from AISI 52100 steel were used. A MIL-L-23699 tetraester lubricant was used in a recirculating lubrication system containing a 49-micron absolute filter. Test conditions included a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the Ferrograph was more sensitive (up to 23 h) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis (SOAP). Four particle types were observed: normal rubbing wear particles, spheres, nonferrous particles, and severe wear (spall) fragments.

The effect of reflexology applied on haemodialysis patients with fatigue, pain and cramps.

PubMed

Ozdemir, Gülistan; Ovayolu, Nimet; Ovayolu, Ozlem

2013-06-01

The research was conducted to evaluate the effect of foot reflexology on fatigue, pain and cramps in haemodialysis patients. The sample consisted of 80 patients in total, 40 intervention and 40 control patients, receiving treatment in the haemodialysis units of two institutions. Data were collected by using a questionnaire, Piper Fatigue Scale and visual analogue scale for measuring the severity of cramp and pain. The intervention group received reflexology treatment for 1 week in three sessions following haemodialysis, each session lasting approximately 30 min. Parametric and non-parametric tests were used in data analysis. It was determined that reflexology reduced the fatigue subscale scores and total scale scores as well as pain and cramp mean scores in the intervention group. The research results revealed that the severity of fatigue, pain and cramp decreased in patients receiving reflexology. © 2013 Wiley Publishing Asia Pty Ltd.

Development and Validation of a Fatigue Assessment Scale for U.S. Construction Workers

PubMed Central

Zhang, Mingzong; Sparer, Emily H.; Murphy, Lauren A.; Dennerlein, Jack T.; Fang, Dongping; Katz, Jeffrey N.; Caban-Martinez, Alberto J.

2015-01-01

Objective To develop a fatigue assessment scale and test its reliability and validity for commercial construction workers. Methods Using a two-phased approach, we first identified items for the development of a Fatigue Assessment Scale for Construction Workers (FASCW) through review of existing scales in the scientific literature, key informant interviews (n=11) and focus groups (3 groups with 6 workers each) with construction workers. The second phase included assessment for the reliability, validity and sensitivity of the new scale using a repeated-measures study design with a convenience sample of construction workers (n=144). Results Phase one resulted in a 16-item preliminary scale that after factor analysis yielded a final 10-item scale with two sub-scales (“Lethargy” and “Bodily Ailment”).. During phase two, the FASCW and its subscales demonstrated satisfactory internal consistency (alpha coefficients were FASCW (0.91), Lethargy (0.86) and Bodily Ailment (0.84)) and acceptable test-retest reliability (Pearson Correlations Coefficients: 0.59–0.68; Intraclass Correlation Coefficients: 0.74–0.80). Correlation analysis substantiated concurrent and convergent validity. A discriminant analysis demonstrated that the FASCW differentiated between groups with arthritis status and different work hours. Conclusions The 10-item FASCW with good reliability and validity is an effective tool for assessing the severity of fatigue among construction workers. PMID:25603944

Sensing sheets based on large area electronics for fatigue crack detection

NASA Astrophysics Data System (ADS)

Yao, Yao; Glisic, Branko

2015-03-01

Reliable early-stage damage detection requires continuous structural health monitoring (SHM) over large areas of structure, and with high spatial resolution of sensors. This paper presents the development stage of prototype strain sensing sheets based on Large Area Electronics (LAE), in which thin-film strain gauges and control circuits are integrated on the flexible electronics and deposited on a polyimide sheet that can cover large areas. These sensing sheets were applied for fatigue crack detection on small-scale steel plates. Two types of sensing-sheet interconnects were designed and manufactured, and dense arrays of strain gauge sensors were assembled onto the interconnects. In total, four (two for each design type) strain sensing sheets were created and tested, which were sensitive to strain at virtually every point over the whole sensing sheet area. The sensing sheets were bonded to small-scale steel plates, which had a notch on the boundary so that fatigue cracks could be generated under cyclic loading. The fatigue tests were carried out at the Carleton Laboratory of Columbia University, and the steel plates were attached through a fixture to the loading machine that applied cyclic fatigue load. Fatigue cracks then occurred and propagated across the steel plates, leading to the failure of these test samples. The strain sensor that was close to the notch successfully detected the initialization of fatigue crack and localized the damage on the plate. The strain sensor that was away from the crack successfully detected the propagation of fatigue crack based on the time history of measured strain. Overall, the results of the fatigue tests validated general principles of the strain sensing sheets for crack detection.

Fatigue in the general population of Colombia - normative values for the multidimensional fatigue inventory MFI-20.

PubMed

Hinz, Andreas; Barboza, Carolyn Finck; Barradas, Susana; Körner, Annett; Beierlein, Volker; Singer, Susanne

2013-01-01

Fatigue is a frequent symptom in cancer patients. In Europe and Northern America fatigue questionnaires were developed and tested, but their generalizability to other cultural contexts is largely unknown. The aim of this study is to provide normative values for the Multidimensional Fatigue Inventory (MFI-20) based on a representative sample of the general population in Colombia and to test psychometric properties. 1,500 individuals completed a questionnaire that contained the MFI-20, as well as other questionnaires, and questions on sociodemographic variables and chronic diseases. The mean values of the scales were marginally higher than those for 2 European samples. The mean value of the total score was 44.3 ± 14.1. Women were affected by fatigue more than men, and there was an almost linear age trend, with higher mean scores for older subjects. People with chronic diseases were affected by fatigue more than people without chronic conditions. The best psychometric properties were obtained for the total scale (sum score) of the MFI-20. The normative values presented here can help us to assess the individual burden of fatigue in a Latin American context. Psychometric properties of the MFI-20 in Colombia are similar to those obtained in Europe. © 2013 S. Karger GmbH, Freiburg.

Associations Between Fatigue and Disability, Functional Mobility, Depression, and Quality of Life in People with Multiple Sclerosis

PubMed Central

Bush, Steffani; Gappmaier, Eduard

2016-01-01

Background: Fatigue is a common symptom in people with multiple sclerosis (MS), but its associations with disability, functional mobility, depression, and quality of life (QOL) remain unclear. We aimed to determine the associations between different levels of fatigue and disability, functional mobility, depression, and physical and mental QOL in people with MS. Methods: Eighty-nine individuals with MS (mean [SD] disease duration = 13.6 [9.8] years, mean [SD] Expanded Disability Status Scale [EDSS] score = 5.3 [1.5]) and no concurrent relapses were retrospectively analyzed. Participants were divided into two groups based on five-item Modified Fatigue Impact Scale (MFIS-5) scores: group LF (n = 32, MFIS-5 score ≤10 [low levels of fatigue]) and group HF (n = 57, MFIS-5 score >10 [high levels of fatigue]). Results: Sixty-four percent of the sample reported high levels of fatigue. Compared with group LF, group HF demonstrated significantly (P < .05) greater impairments in the Timed Up and Go test, Activities-specific Balance Confidence scale, and 12-item Multiple Sclerosis Walking Scale scores; depression; and QOL but not in the EDSS scores, which were not significantly different between groups. Conclusions: Fatigue was found to be a predominant symptom in the study participants. Individuals reporting higher levels of fatigue concomitantly exhibited greater impairments in functional mobility, depression, and physical and mental QOL. Disability was not found to be related to level of fatigue. These findings can be important for appropriate assessment and management of individuals with MS with fatigue. PMID:27134580

The assessment of fatigue: Psychometric qualities and norms for the Checklist individual strength.

PubMed

Worm-Smeitink, M; Gielissen, M; Bloot, L; van Laarhoven, H W M; van Engelen, B G M; van Riel, P; Bleijenberg, G; Nikolaus, S; Knoop, H

2017-07-01

The Checklist Individual Strength (CIS) measures four dimensions of fatigue: Fatigue severity, concentration problems, reduced motivation and activity. On the fatigue severity subscale, a cut-off score of 35 is used. This study 1) investigated the psychometric qualities of the CIS; 2) validated the cut-off score for severe fatigue and 3) provided norms. Representatives of the Dutch general population (n=2288) completed the CIS. The factor structure was investigated using an exploratory factor analysis. Internal consistency and test-retest reliability were determined. Concurrent validity was assessed in two additional samples by correlating the CIS with other fatigue scales (Chalder Fatigue Questionnaire, MOS Short form-36 Vitality subscale, EORTC QLQ-C30 fatigue subscale). To validate the fatigue severity cut-off score, a Receiver Operating Characteristics analysis was performed with patients referred to a chronic fatigue treatment centre (n=5243) and a healthy group (n=1906). Norm scores for CIS subscales were calculated for the general population, patients with chronic fatigue syndrome (CFS; n=1407) and eight groups with other medical conditions (n=1411). The original four-factor structure of the CIS was replicated. Internal consistency (α=0.84-0.95) and test-retest reliability (r=0.74-0.86) of the subscales were high. Correlations with other fatigue scales were moderate to high. The 35 points cut-off score for severe fatigue is appropriate, but, given the 17% false positive rate, should be adjusted to 40 for research in CFS. The CIS is a valid and reliable tool for the assessment of fatigue, with a validated cut-off score for severe fatigue that can be used in clinical practice. Copyright © 2017. Published by Elsevier Inc.

High rates of fatigue and sleep disturbances in dystonia.

PubMed

Wagle Shukla, A; Brown, R; Heese, K; Jones, J; Rodriguez, R L; Malaty, I M; Okun, M S; Kluger, B M

2016-10-01

Nonmotor symptoms in dystonia are increasingly recognized to impair the quality of life. The primary objective of this study was to determine the prevalence of fatigue and sleep disturbances in dystonia and to ascertain their impact on quality of life using standardized questionnaires. Dystonia patients presenting to a Botulinum toxin clinic were prospectively administered Fatigue Severity Scale (FSS), Multidimensional Fatigue Inventory (MFI), Epworth Sleepiness Scale (ESS) and Parkinson's Disease Sleep Scale (PDSS) for assessment of fatigue and sleep disturbances. Health-related Quality of life (HRQOL) was determined using MOS SF-36 scale and depressive symptoms were assessed using the Beck Depression Inventory II. Ninety-one patients with dystonia participated (66 women, 25 men, mean age 60 ± 17 years). Nine subjects had generalized dystonia, 18 segmental dystonia and 64 had focal dystonia. Moderate to severe fatigue was present in 43% of the cohort (FSS), excessive daytime somnolence in 27% (ESS) and other sleep disturbances in 26% (PDSS). FSS and MFI scores correlated significantly with HRQOL even when controlled for depression and sleep disturbances. Excessive daytime somnolence and nocturnal sleep disturbances correlated significantly with the HRQOL; however, these effects were not seen for daytime somnolence when controlled for depression. Psychometric testing found adequate reliabilities and convergent validities for both fatigue and sleep scales. Fatigue and sleep disturbances revealed high prevalence rates in this large, first of its dystonia study. They negatively impacted the quality of life even when controlled for comorbid depression.

A novel method of strain - bending moment calibration for blade testing

NASA Astrophysics Data System (ADS)

Greaves, P.; Prieto, R.; Gaffing, J.; van Beveren, C.; Dominy, R.; Ingram, G.

2016-09-01

A new method of interpreting strain data in full scale static and fatigue tests has been implemented as part of the Offshore Renewable Energy Catapult's ongoing development of biaxial fatigue testing of wind turbine blades. During bi-axial fatigue tests, it is necessary to be able to distinguish strains arising from the flapwise motion of the blade from strains arising from the edgewise motion. The method exploits the beam-like structure of blades and is derived using the equations of beam theory. It offers several advantages over the current state of the art method of calibrating strain gauges.

The Piper Fatigue Scale-12 (PFS-12): psychometric findings and item reduction in a cohort of breast cancer survivors.

PubMed

Reeve, Bryce B; Stover, Angela M; Alfano, Catherine M; Smith, Ashley Wilder; Ballard-Barbash, Rachel; Bernstein, Leslie; McTiernan, Anne; Baumgartner, Kathy B; Piper, Barbara F

2012-11-01

Brief, valid measures of fatigue, a prevalent and distressing cancer symptom, are needed for use in research. This study's primary aim was to create a shortened version of the revised Piper Fatigue Scale (PFS-R) based on data from a diverse cohort of breast cancer survivors. A secondary aim was to determine whether the PFS captured multiple distinct aspects of fatigue (a multidimensional model) or a single overall fatigue factor (a unidimensional model). Breast cancer survivors (n = 799; stages in situ through IIIa; ages 29-86 years) were recruited through three SEER registries (New Mexico, Western Washington, and Los Angeles, CA) as part of the Health, Eating, Activity, and Lifestyle (HEAL) study. Fatigue was measured approximately 3 years post-diagnosis using the 22-item PFS-R that has four subscales (Behavior, Affect, Sensory, and Cognition). Confirmatory factor analysis was used to compare unidimensional and multidimensional models. Six criteria were used to make item selections to shorten the PFS-R: scale's content validity, items' relationship with fatigue, content redundancy, differential item functioning by race and/or education, scale reliability, and literacy demand. Factor analyses supported the original 4-factor structure. There was also evidence from the bi-factor model for a dominant underlying fatigue factor. Six items tested positive for differential item functioning between African-American and Caucasian survivors. Four additional items either showed poor association, local dependence, or content validity concerns. After removing these 10 items, the reliability of the PFS-12 subscales ranged from 0.87 to 0.89, compared to 0.90-0.94 prior to item removal. The newly developed PFS-12 can be used to assess fatigue in African-American and Caucasian breast cancer survivors and reduces response burden without compromising reliability or validity. This is the first study to determine PFS literacy demand and to compare PFS-R responses in African-Americans and Caucasian breast cancer survivors. Further testing in diverse populations is warranted.

Fatigue and physical fitness of mildly disabled persons with multiple sclerosis: a cross-sectional study.

PubMed

Valet, Maxime; Lejeune, Thierry; Glibert, Yumiko; Hakizimana, Jean C; Van Pesch, Vincent; El Sankari, Souraya; Detrembleur, Christine; Stoquart, Gaëtan

2017-09-01

Fatigue is frequent and disabling in persons with multiple sclerosis (pwMS) with mild neurological disability. These patients also have impaired physical fitness. Whether mildly disabled pwMS are deconditioned, and this deconditioning is linked to fatigue, remains unknown. Our aim is to determine the physical fitness of mildly disabled patients with multiple sclerosis and study its relationship with perceived fatigue and to link perceived fatigue with other parameters. Twenty patients (14 women; mean age: 45.5 years) with mild disability (Expanded Disability Status Scale 0-4) underwent a 2-min walking test, Timed Up-and-Go test, aerobic capacity testing, and isometric knee extension testing to assess strength and neuromuscular fatigability. They completed questionnaires assessing perceived fatigue, psychological status, and physical activity. Correlation coefficients and multivariate regression were used to analyze the relationships among variables. Seventeen (85%) patients reported a high level of fatigue. Thirteen (65%) patients had subnormal aerobic capacity. Fatigue was weakly to moderately associated with aerobic capacity, mobility, walking capacity, depression, and neuromuscular fatigability. An association of disease duration, aerobic capacity, and the neuromuscular fatigability index explained 65.1% of fatigue. A high proportion of pwMS with mild neurological disability are fatigued and deconditioned. Perceived fatigue is linked to aerobic capacity, neuromuscular fatigability, depression, mobility, and walking capacity. Focusing on these parameters could help in the management of fatigue.

Probabilistic Flexural Fatigue in Plain and Fiber-Reinforced Concrete

PubMed Central

Ríos, José D.

2017-01-01

The objective of this work is two-fold. First, we attempt to fit the experimental data on the flexural fatigue of plain and fiber-reinforced concrete with a probabilistic model (Saucedo, Yu, Medeiros, Zhang and Ruiz, Int. J. Fatigue, 2013, 48, 308–318). This model was validated for compressive fatigue at various loading frequencies, but not for flexural fatigue. Since the model is probabilistic, it is not necessarily related to the specific mechanism of fatigue damage, but rather generically explains the fatigue distribution in concrete (plain or reinforced with fibers) for damage under compression, tension or flexion. In this work, more than 100 series of flexural fatigue tests in the literature are fit with excellent results. Since the distribution of monotonic tests was not available in the majority of cases, a two-step procedure is established to estimate the model parameters based solely on fatigue tests. The coefficient of regression was more than 0.90 except for particular cases where not all tests were strictly performed under the same loading conditions, which confirms the applicability of the model to flexural fatigue data analysis. Moreover, the model parameters are closely related to fatigue performance, which demonstrates the predictive capacity of the model. For instance, the scale parameter is related to flexural strength, which improves with the addition of fibers. Similarly, fiber increases the scattering of fatigue life, which is reflected by the decreasing shape parameter. PMID:28773123

Probabilistic Flexural Fatigue in Plain and Fiber-Reinforced Concrete.

PubMed

Ríos, José D; Cifuentes, Héctor; Yu, Rena C; Ruiz, Gonzalo

2017-07-07

The objective of this work is two-fold. First, we attempt to fit the experimental data on the flexural fatigue of plain and fiber-reinforced concrete with a probabilistic model (Saucedo, Yu, Medeiros, Zhang and Ruiz, Int. J. Fatigue, 2013, 48, 308-318). This model was validated for compressive fatigue at various loading frequencies, but not for flexural fatigue. Since the model is probabilistic, it is not necessarily related to the specific mechanism of fatigue damage, but rather generically explains the fatigue distribution in concrete (plain or reinforced with fibers) for damage under compression, tension or flexion. In this work, more than 100 series of flexural fatigue tests in the literature are fit with excellent results. Since the distribution of monotonic tests was not available in the majority of cases, a two-step procedure is established to estimate the model parameters based solely on fatigue tests. The coefficient of regression was more than 0.90 except for particular cases where not all tests were strictly performed under the same loading conditions, which confirms the applicability of the model to flexural fatigue data analysis. Moreover, the model parameters are closely related to fatigue performance, which demonstrates the predictive capacity of the model. For instance, the scale parameter is related to flexural strength, which improves with the addition of fibers. Similarly, fiber increases the scattering of fatigue life, which is reflected by the decreasing shape parameter.

A validity and reliability study of the Turkish Multidimensional Assessment of Fatigue (MAF) scale in chronic musculoskeletal physical therapy patients.

PubMed

Yildirim, Yücel; Ergin, Gülbin

2013-01-01

Fatigue is primarily a subjective experience and self-report is the most common approach used to measure fatigue. Numerous self-report instruments have been developed to measure fatigue. Unfortunately, each of these measures was tailored for the situation in which fatigue was studied. Therefore, the aim of this study was to determine the reliability and validity of the Turkish language version of the Multidimensional Assessment of Fatigue Scale (MAF-T) in chronic musculoskeletal physical therapy patients. The MAF-T was supplied by the MAPI Research Institute, and 69 chronic musculoskeletal physical therapy patients were evaluated. To validate MAF-T, all participants completed the MAF-T and Short Form-36 (SF-36). The MAF was administered again one week later to assess test-retest reliability. Using Cronbach α, the internal consistency reliability of the MAF-T was 0.90, the Intraclass Correlation Coefficient (ICC) reliability was 0.96. Item-discriminant validity was calculated between r=0.14 and r=0.82. The correlations between the total scores of the MAF-T scale and the subscale scores of SF-36 were negative and significant (p< 0.01). The MAF-T is a valid and reliable scale for assessing fatigue in chronic musculoskeletal physical therapy patients.

75 FR 9811 - Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model ERJ 170 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-04

... 170 airplane full scale fatigue test, cracks were found in some structural components of the airplane... timely detection of fatigue cracks. Undetected fatigue cracks in these areas could adversely affect the...., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service...

Evaluation of the psychometric properties of the PROMIS Cancer Fatigue Short Form with cancer patients.

PubMed

Cessna, Julie M; Jim, Heather S L; Sutton, Steven K; Asvat, Yasmin; Small, Brent J; Salsman, John M; Zachariah, Babu; Fishman, Mayer; Field, Teresa; Fernandez, Hugo; Perez, Lia; Jacobsen, Paul B

2016-02-01

Fatigue is common among cancer patients and adversely impacts quality of life. As such, it is important to measure fatigue accurately in a way that is not burdensome to patients. The 7-item Patient Reported Outcome Measurement Information System (PROMIS) Cancer Fatigue Short Form scale was recently developed using item response theory (IRT). The current study evaluated the psychometric properties of this scale in two samples of cancer patients using classical test theory (CTT). Two samples were used: 121 men with prostate cancer and 136 patients scheduled to undergo hematopoietic cell transplantation (HCT) for hematologic cancer. All participants completed the PROMIS Cancer Fatigue Short Form as well as validated measures of fatigue, vitality, and depression. HCT patients also completed measures of anxiety, perceived stress, and a clinical interview designed to identify cases of cancer-related fatigue. PROMIS Cancer Fatigue Short Form items loaded on a single factor (CFI=0.948) and the scale demonstrated good internal consistency reliability in both samples (Cronbach's alphas>0.86). Correlations with psychosocial measures were significant (p values<.0001) and in the expected direction, offering evidence for convergent and concurrent validity. PROMIS Fatigue scores were significantly higher in patients who met case definition criteria for cancer-related fatigue (p<.0001), demonstrating criterion validity. The current study provides evidence that the PROMIS Cancer Fatigue Short Form is a reliable and valid measure of fatigue in cancer patients. Copyright © 2015 Elsevier Inc. All rights reserved.

Evaluation of the Psychometric Properties of the PROMIS Cancer Fatigue Short Form with Cancer Patients

PubMed Central

Cessna, Julie M.; Jim, Heather S.L.; Sutton, Steven K.; Asvat, Yasmin; Small, Brent J.; Salsman, John M.; Zachariah, Babu; Fishman, Mayer; Field, Teresa; Fernandez, Hugo; Perez, Lia; Jacobsen, Paul B.

2016-01-01

Objective Fatigue is common among cancer patients and adversely impacts quality of life. As such, it is important to measure fatigue accurately in a way that is not burdensome to patients. The 7-item Patient Reported Outcome Measurement Information System (PROMIS) Cancer Fatigue Short Form scale was recently developed using item response theory (IRT). The current study evaluated the psychometric properties of this scale in two samples of cancer patients using classical test theory (CTT). Methods Two samples were used: 121 men with prostate cancer and 136 patients scheduled to undergo hematopoietic cell transplantation (HCT) for hematologic cancer. All participants completed the PROMIS Cancer Fatigue Short Form as well as validated measures of fatigue, vitality, and depression. HCT patients also completed measures of anxiety, perceived stress, and a clinical interview designed to identify cases of cancer -related fatigue. Results PROMIS Cancer Fatigue Short Form items loaded on a single factor (CFI = 0.948) and the scale demonstrated good internal consistency reliability in both samples (Cronbach’s alphas > 0.86). Correlations with psychosocial measures were significant (p-values < .0001) and in the expected direction, offering evidence for convergent and concurrent validity. PROMIS Fatigue scores were significantly higher in patients who met case definition criteria for cancer-related fatigue (p < .0001), demonstrating criterion validity. Conclusion The current study provides evidence that the PROMIS Cancer Fatigue Short Form is a reliable and valid measure of fatigue in cancer patients. PMID:26800633

Psychometric evaluation of the fatigue severity scale for use in chronic hepatitis C.

PubMed

Kleinman, L; Zodet, M W; Hakim, Z; Aledort, J; Barker, C; Chan, K; Krupp, L; Revicki, D

2000-01-01

Evidence exists demonstrating that infection with hepatitis C virus impairs health-related quality of life, but less is known about the effect of fatigue, a common symptom, on everyday life. The psychometric properties of the fatigue severity scale (FSS) were explored to determine suitability as an outcome measure in clinical trials. The FSS includes nine items developed to measure disabling fatigue and a visual analog scale (VAS) to measure overall fatigue. Using baseline data from three clinical trials (n = 1225) involving chronic hepatitis C patients, scaling and psychometric characteristics of the FSS were assessed. The SF-36 was also used in the trials. Item response theory analysis demonstrated that the FSS items can be placed along a single homogenous domain, fatigue. Internal consistency reliability was 0.94. Test-retest reliability was 0.82 for the total score and 0.80 for the VAS. The total score and the VAS were significantly correlated with the SF-36 vitality subscale (r = -0.76 and r = -0.76 respectively). Correlations with other SF-36 subscales were moderate (r = -0.46 to r = -0.67, all p < 0.0001). In summary, the FSS possesses good psychometric properties.

Effects of an individual 12-week community-located "start-to-run" program on physical capacity, walking, fatigue, cognitive function, brain volumes, and structures in persons with multiple sclerosis.

PubMed

Feys, Peter; Moumdjian, Lousin; Van Halewyck, Florian; Wens, Inez; Eijnde, Bert O; Van Wijmeersch, Bart; Popescu, Veronica; Van Asch, Paul

2017-11-01

Exercise therapy studies in persons with multiple sclerosis (pwMS) primarily focused on motor outcomes in mid disease stage, while cognitive function and neural correlates were only limitedly addressed. This pragmatic randomized controlled study investigated the effects of a remotely supervised community-located "start-to-run" program on physical and cognitive function, fatigue, quality of life, brain volume, and connectivity. In all, 42 pwMS were randomized to either experimental (EXP) or waiting list control (WLC) group. The EXP group received individualized training instructions during 12 weeks (3×/week), to be performed in their community aiming to participate in a running event. Measures were physical (VO 2max , sit-to-stand test, Six-Minute Walk Test (6MWT), Multiple Sclerosis Walking Scale-12 (MSWS-12)) and cognitive function (Rao's Brief Repeatable Battery (BRB), Paced Auditory Serial Attention Test (PASAT)), fatigue (Fatigue Scale for Motor and Cognitive Function (FSMC)), quality of life (Multiple Sclerosis Impact Scale-29 (MSIS-29)), and imaging. Brain volumes and diffusion tensor imaging (DTI) were quantified using FSL-SIENA/FIRST and FSL-TBSS. In all, 35 pwMS completed the trial. Interaction effects in favor of the EXP group were found for VO 2max , sit-to-stand test, MSWS-12, Spatial Recall Test, FSMC, MSIS-29, and pallidum volume. VO 2max improved by 1.5 mL/kg/min, MSWS-12 by 4, FSMC by 11, and MSIS-29 by 14 points. The Spatial Recall Test improved by more than 10%. Community-located run training improved aerobic capacity, functional mobility, visuospatial memory, fatigue, and quality of life and pallidum volume in pwMS.

Translation and adaptation of the fatigue severity scale for use in Portugal.

PubMed

Laranjeira, Carlos António

2012-08-01

The Fatigue Severity Scale (FSS) is a widely used instrument to measure the impact of fatigue on specific types of functioning. This study aims to translate and test the reliability and validity of the Portuguese version of the FSS. The questionnaire was administered to a worker sample of 424 nurses. Reliability analysis showed satisfactory results (Cronbach's alpha coefficient = .87). The test-retest reliability was .85. The principal component analysis showed that the FSS was a measure with a one-factor structure. The construct validity of the total FSS score was assessed by correlation with Maslach Burnout Inventory (MBI) score, Depression Anxiety Stress Scale (DASS) score, and Visual Analogue Scale (VAS) score. Each of the corresponding correlation coefficients among the total FSS score and MBI score, DASS score, and perceived fatigue score (VAS) were .55 (p < .01), .62 (p < .01), and .68 (p < .01), respectively, which shows sufficient construct validity. To measure the discriminant validity of FSS, we examined the differences in scores between groups in terms of the number of hours of sleep and overtime. The less nurses slept and the longer they worked, the higher their total FSS score became. This preliminary validation study of the Portuguese version of FSS proved that it is an acceptable, reliable, and valid measure of fatigue in the working population. Copyright © 2012 Elsevier Inc. All rights reserved.

Fatigue crack monitoring with coupled piezoelectric film acoustic emission sensors

NASA Astrophysics Data System (ADS)

Zhou, Changjiang

Fatigue-induced cracking is a commonly seen problem in civil infrastructures reaching their original design life. A number of high-profile accidents have been reported in the past that involved fatigue damage in structures. Such incidences often happen without prior warnings due to lack of proper crack monitoring technique. In order to detect and monitor the fatigue crack, acoustic emission (AE) technique, has been receiving growing interests recently. AE can provide continuous and real-time monitoring data on damage progression in structures. Piezoelectric film AE sensor measures stress-wave induced strain in ultrasonic frequency range and its feasibility for AE signal monitoring has been demonstrated recently. However, extensive work in AE monitoring system development based on piezoelectric film AE sensor and sensor characterization on full-scale structures with fatigue cracks, have not been done. A lack of theoretical formulations for understanding the AE signals also hinders the use of piezoelectric film AE sensors. Additionally, crack detection and source localization with AE signals is a very important area yet to be explored for this new type of AE sensor. This dissertation presents the results of both analytical and experimental study on the signal characteristics of surface stress-wave induced AE strain signals measured by piezoelectric film AE sensors in near-field and an AE source localization method based on sensor couple theory. Based on moment tensor theory, generalized expression for AE strain signal is formulated. A special case involving the response of piezoelectric film AE sensor to surface load is also studied, which could potentially be used for sensor calibration of this type of sensor. A new concept of sensor couple theory based AE source localization technique is proposed and validated with both simulated and experimental data from fatigue test and field monitoring. Two series of fatigue tests were conducted to perform fatigue crack monitoring on large-scale steel test specimens using piezoelectric film AE sensors. Continuous monitoring of fatigue crack growth in steel structures is demonstrated in these fatigue test specimens. The use of piezoelectric film AE sensor for field monitoring of existing fatigue crack is also demonstrated in a real steel I-girder bridge located in Maryland. The sensor couple theory based AE source localization is validated using a limited number of piezoelectric film AE sensor data from both fatigue test specimens and field monitoring bridge. Through both laboratory fatigue test and field monitoring of steel structures with active fatigue cracks, the signal characteristics of piezoelectric film AE sensor have been studied in real-world environment.

14 CFR Appendix H to Part 25 - Instructions for Continued Airworthiness

Code of Federal Regulations, 2013 CFR

2013-01-01

..., approved under § 25.571. Until the full-scale fatigue testing is completed and the FAA has approved the LOV... accumulated on the fatigue test article. (b) If the Instructions for Continued Airworthiness consist of... identifying any changes to EWIS under § 25.1711. (5) Electrical load data and instructions for updating that...

14 CFR Appendix H to Part 25 - Instructions for Continued Airworthiness

Code of Federal Regulations, 2014 CFR

2014-01-01

..., approved under § 25.571. Until the full-scale fatigue testing is completed and the FAA has approved the LOV... accumulated on the fatigue test article. (b) If the Instructions for Continued Airworthiness consist of... identifying any changes to EWIS under § 25.1711. (5) Electrical load data and instructions for updating that...

14 CFR Appendix H to Part 25 - Instructions for Continued Airworthiness

Code of Federal Regulations, 2012 CFR

2012-01-01

..., approved under § 25.571. Until the full-scale fatigue testing is completed and the FAA has approved the LOV... accumulated on the fatigue test article. (b) If the Instructions for Continued Airworthiness consist of... identifying any changes to EWIS under § 25.1711. (5) Electrical load data and instructions for updating that...

A Model of Fatigue Following Traumatic Brain Injury.

PubMed

Ponsford, Jennie; Schönberger, Michael; Rajaratnam, Shantha M W

2015-01-01

Fatigue is one of the most frequent sequelae of traumatic brain injury (TBI), although its causes are poorly understood. This study investigated the interrelationships between fatigue and sleepiness, vigilance performance, depression, and anxiety, using a structural equation modeling approach. Seventy-two participants with moderate to severe TBI (78% males) were recruited a median of 305 days postinjury. They completed the Fatigue Severity Scale, a vigilance task, the Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale. A model of the interrelationships between the study variables was developed, tested, and modified with path analysis. The modified model had a good overall fit (χ2 = 1.3, P = .54; comparative fit index = 1.0; root-mean square error of approximation = 0.0; standardized root-mean square residual = 0.02). Most paths in this model were significant (P < .05). Fatigue predicted anxiety, depression, and daytime sleepiness. Depression predicted daytime sleepiness and poor vigilance, whereas anxiety tended to predict reduced daytime sleepiness. This model confirms the complexity of fatigue experience. It supports the hypothesis that fatigue after TBI is a cause, not a consequence, of anxiety, depression, and daytime sleepiness, which, in turn (especially depression), may exacerbate fatigue by affecting cognitive functioning. These findings suggest that to alleviate fatigue, it is important to address each of these factors. However, the findings need to be confirmed with a longitudinal research design.

Balance as a measurement of fatigue in postcall residents.

PubMed

Cuthbertson, David W; Bershad, Eric M; Sangi-Haghpeykar, Haleh; Cohen, Helen S

2015-02-01

To determine the degree to which balance is impaired by fatigue in postcall medical residents and to assess the validity of posturography in quantifying that impairment. Prospective study. Medical residents underwent the following tests before and immediately after overnight call: 1) computerized dynamic posturography (CDP) using the Equitest force platform (Natus Medical Inc., Clackamas, OR); 2) Clinical Test of Sensory Interaction and Balance, in which the residents stood on a compliant foam mat with closed eyes and flexed and extended their necks; 3) a computerized reaction time test (available at www.humanbenchmark.com). All tests were performed before and after call at approximately the same time of day to exclude circadian rhythm influence on fatigue. The residents also completed questionnaires, including the Stanford Sleepiness Scale, describing their level of fatigue before and after call. A statistically significant difference was found between a resident's pre- and postcall test with regard to reaction time (P = .01), Stanford Sleepiness Scale score (P = .001), and preference for the visual system as measured by CDP (P = .05). Linear regression analysis showed a statistically significant relationship between sleep deprivation and multiple performance variables measured by CDP. With the growing attention paid to resident duty hours, there is an increasing need for research involving fatigue and practical ways to measure it. This study shows that residents who are measurably fatigued (both objectively and subjectively) may have difficulty utilizing vestibular input during quiet standing but can compensate by means of somatosensory and visual input. NA. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Could Objective Tests Be Used to Measure Fatigue in Patients With Advanced Cancer?

PubMed

Schvartsman, Gustavo; Park, Minjeong; Liu, Diane D; Yennu, Sriram; Bruera, Eduardo; Hui, David

2017-08-01

Assessment of cancer-related fatigue is currently based on patient-reported outcomes. We asked whether objective assessments, such as muscle strength and nutritional markers, can be used as surrogate measures of cancer-related fatigue. We examined the association among three fatigue scales, muscle strength, and nutritional markers in patients with advanced cancer. In this prospective study, we enrolled hospitalized cancer patients who had been seen in palliative care consultation at MD Anderson Cancer Center. We assessed fatigue using three fatigue scales-the Brief Fatigue Inventory (BFI), the Edmonton Symptom Assessment System (ESAS), and the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire 30 (EORTC QLQ-C30)-and determined their association with objective assessments, including handgrip strength, maximal inspiratory pressure, lean body mass, phase angle, and albumin. Spearman's correlation test was used to assess associations. Among 222 patients, the mean age was 55 years; 59% were women. The median overall survival was 106 days. The total BFI score had weak association with handgrip strength (ρ = -0.18, P = 0.007) and no association with the remaining objective measures. ESAS fatigue and EORTC fatigue showed similar findings. Total BFI had moderate-to-strong association with ESAS (ρ = 0.54, P < 0.0001) and EORTC (ρ = 0.60, P < 0.0001) fatigue. Our study showed that subjective assessment of fatigue based on patient-reported outcomes correlates only weakly with muscle strength and nutritional markers; thus, patient-reported outcomes remain the gold standard for fatigue assessment. Copyright © 2017 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Performance evaluation of thin wearing courses through scaled accelerated trafficking.

DOT National Transportation Integrated Search

2014-01-01

The primary objective of this study was to evaluate the permanent deformation (rutting) and fatigue performance of : several thin asphalt concrete wearing courses using a scaled-down accelerated pavement testing device. The accelerated testing : was ...

Performance Evaluation of Thin Wearing Courses Through Scaled Accelerated Trafficking.

DOT National Transportation Integrated Search

2014-01-01

"The primary objective of this study was to evaluate the permanent deformation (rutting) and fatigue performance of : several thin asphalt concrete wearing courses using a scaled-down accelerated pavement testing device. The accelerated testing : was...

Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue and Physical Fatigue in People with Fibromyalgia

PubMed Central

Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A

2014-01-01

Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (p<0.01). People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583

Clinical, laboratory, and neuroimaging characteristics of fatigue in HIV-infected individuals.

PubMed

Schifitto, Giovanni; Deng, Lijuan; Yeh, Tzu-Min; Evans, Scott R; Ernst, Thomas; Zhong, Jianhui; Clifford, David

2011-02-01

Fatigue is among the most common symptoms reported by HIV-infected individuals. Previous reports suggest that the prevalence of fatigue varies by disease status with rates close to 80% in patients with AIDS. However, most studies have not been conducted in the setting of a controlled trial and have not assessed the association of fatigue with cellular markers of brain activity. Data for this study were derived from baseline and longitudinal evaluations in ACTG A5090, a randomized, double-blind, placebo-controlled trial of the Selegiline Transdermal System for the treatment of HIV-associated cognitive impairment. Fatigue was assessed using the Fatigue Severity Scale with scores of >4 considered "fatigued". Participants in a substudy underwent brain magnetic resonance spectroscopy (MRS) imaging, an in vivo method for assessing brain metabolites associated with neuronal and glia activity. Differences between fatigued and non-fatigued participants were evaluated with respect to demographics and clinical characteristics, plasma and CSF HIV-1 RNA concentration, CD4 counts, and brain metabolites. One hundred and twenty-eight participants were enrolled (88% male, median age = 45 years) and 82 participants (64%, 95% confidence interval 55%, 72%) were fatigued at baseline. MRS was conducted in 62 of the 128 participants. Fatigued participants were significantly younger (p = 0.011), had lower Karnofsky scores (p = 0.032), and had higher levels of depressive symptoms on the Center for Epidemiologic Studies Depression (CES-D) scale (p < 0.001) than non-fatigued participants. Statistically significant differences between fatigued and non-fatigued groups were not detected for plasma and CSF HIV-1RNA concentration, CD4 counts, or on neuropsychological tests. MRS revealed significantly lower levels of the cellular energy marker total creatine (p = 0.002) in the basal ganglia of fatigued participants. Statistically significant differences in other brain metabolites were not detected. Longitudinal data showed that fatigue persisted and worse fatigue at baseline was predictor of future fatigue. Among the cognitive tests, baseline Stroop score was associated with future fatigue. Fatigue was present in 64% of A5090 study participants and persisted during the 24 weeks of follow-up. Fatigue was associated with worse functional performance and depressive mood. Lower cellular energy levels in the basal ganglia, as measured by MRS total creatine concentration, suggest energy dysmetabolism in this brain region. This observation, taken together with the association between fatigue and neuropsychological tests of frontal lobe performance is consistent with the hypothesis of a striatal-cortical circuitry involvement in the symptoms of fatigue.

The effect of rhythmic-cued motor imagery on walking, fatigue and quality of life in people with multiple sclerosis: A randomised controlled trial.

PubMed

Seebacher, Barbara; Kuisma, Raija; Glynn, Angela; Berger, Thomas

2017-02-01

Motor imagery and rhythmic auditory stimulation are physiotherapy strategies for walking rehabilitation. To investigate the effect of motor imagery combined with rhythmic cueing on walking, fatigue and quality of life (QoL) in people with multiple sclerosis (MS). Individuals with MS and Expanded Disability Status Scale scores of 1.5-4.5 were randomised into one of three groups: 17 minutes of motor imagery, six times per week, for 4 weeks, with music (A) or metronome cues (B), both with verbal cueing, and (C) controls. Primary outcomes were walking speed (Timed 25-Foot Walk) and distance (6-Minute Walk Test). Secondary outcomes were walking perception (Multiple Sclerosis Walking Scale-12), fatigue (Modified Fatigue Impact Scale) and QoL (Short Form-36 Health Survey, Multiple Sclerosis Impact Scale-29, Euroquol-5D-3L Questionnaire). Of the 112 participants randomised, 101 completed the study. Compared to controls, both interventions significantly improved walking speed, distance and perception. Significant improvements in cognitive but not psychosocial fatigue were seen in the intervention groups, and physical fatigue improved only in the music-based group. Both interventions improved QoL; however, music-cued motor imagery was superior at improving health-related QoL. Rhythmic-cued motor imagery improves walking, fatigue and QoL in people with MS, with music-cued motor imagery being more effective.

The characterization of widespread fatigue damage in fuselage structure

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.; Miller, Matthew

1994-01-01

The characteristics of widespread fatigue damage (WSFD) in fuselage riveted structure were established by detailed nondestructive and destructive examinations of fatigue damage contained in a full size fuselage test article. The objectives of this were to establish an experimental data base for validating emerging WSFD analytical prediction methodology and to identify first order effects that contribute to fatigue crack initiation and growth. Detailed examinations were performed on a test panel containing four bays of a riveted lap splice joint. The panel was removed from a full scale fuselage test article after receiving 60,000 full pressurization cycles. The results of in situ examinations document the progression of fuselage skin fatigue crack growth through crack linkup. Detailed tear down examinations and fractography of the lap splice joint region revealed fatigue crack initiation sites, crack morphology, and crack linkup geometry. From this large data base, distributions of crack size and locations are presented and discussions of operative damage mechanisms are offered.

The characterization of widespread fatigue damage in fuselage structure

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.; Miller, Matthew

1994-01-01

The characteristics of widespread fatigue damage (WSFD) in fuselage riveted structure were established by detailed nondestructive and destructive examinations of fatigue damage contained in a full size fuselage test article. The objectives of this work were to establish an experimental data base for validating emerging WSFD analytical prediction methodology and to identify first order effects that contribute to fatigue crack initiation and growth. Detailed examinations were performed on a test panel containing four bays of a riveted lap splice joint. The panel was removed from a full scale fuselage test article after receiving 60,000 full pressurization cycles. The results of in situ examinations document the progression of fuselage skin fatigue crack growth through crack linkup. Detailed tear down examinations and fractography of the lap splice joint region revealed fatigue crack initiation sites, crack morphology and crack linkup geometry. From this large data base, distributions of crack size and locations are presented and discussions of operative damage mechanisms are offered.

Clinical, laboratory, and neuroimaging characteristics of fatigue in HIV-infected individuals

PubMed Central

Schifitto, Giovanni; Deng, Lijuan; Yeh, Tzu-min; Evans, Scott R.; Ernst, Thomas; Zhong, Jianhui; Clifford, David

2011-01-01

Fatigue is among the most common symptoms reported by HIV-infected individuals. Previous reports suggest that the prevalence of fatigue varies by disease status with rates close to 80% in patients with AIDS. However, most studies have not been conducted in the setting of a controlled trial and have not assessed the association of fatigue with cellular markers of brain activity. Data for this study were derived from baseline and longitudinal evaluations in ACTG A5090, a randomized, double-blind, placebo-controlled trial of the Selegiline Transdermal System for the treatment of HIV-associated cognitive impairment. Fatigue was assessed using the Fatigue Severity Scale with scores of >4 considered “fatigued”. Participants in a substudy underwent brain magnetic resonance spectroscopy (MRS) imaging, an in vivo method for assessing brain metabolites associated with neuronal and glia activity. Differences between fatigued and non-fatigued participants were evaluated with respect to demographics and clinical characteristics, plasma and CSF HIV-1 RNA concentration, CD4 counts, and brain metabolites. One hundred and twenty-eight participants were enrolled (88% male, median age=45 years) and 82 participants (64%, 95% confidence interval 55%, 72%) were fatigued at baseline. MRS was conducted in 62 of the 128 participants. Fatigued participants were significantly younger (p=0.011), had lower Karnofsky scores (p=0.032), and had higher levels of depressive symptoms on the Center for Epidemiologic Studies Depression (CES-D) scale (p<0.001) than non-fatigued participants. Statistically significant differences between fatigued and non-fatigued groups were not detected for plasma and CSF HIV-1RNA concentration, CD4 counts, or on neuropsychological tests. MRS revealed significantly lower levels of the cellular energy marker total creatine (p=0.002) in the basal ganglia of fatigued participants. Statistically significant differences in other brain metabolites were not detected. Longitudinal data showed that fatigue persisted and worse fatigue at baseline was predictor of future fatigue. Among the cognitive tests, baseline Stroop score was associated with future fatigue. Fatigue was present in 64% of A5090 study participants and persisted during the 24 weeks of follow-up. Fatigue was associated with worse functional performance and depressive mood. Lower cellular energy levels in the basal ganglia, as measured by MRS total creatine concentration, suggest energy dysmetabolism in this brain region. This observation, taken together with the association between fatigue and neuropsychological tests of frontal lobe performance is consistent with the hypothesis of a striatal–cortical circuitry involvement in the symptoms of fatigue. PMID:21181521

Reliability and validity of Short Form 36 Version 2 to measure health perceptions in a sub-group of individuals with fatigue.

PubMed

Davenport, Todd E; Stevens, Staci R; Baroni, Katie; Van Ness, J Mark; Snell, Christopher R

2011-01-01

To determine the validity and reliability of Short Form 36 Version 2 (SF36v2) in sub-groups of individuals with fatigue. Thirty subjects participated in this study, including n = 16 subjects who met case definition criteria for chronic fatigue syndrome (CFS) and n = 14 non-disabled sedentary matched control subjects. SF36v2 and Multidimensional Fatigue Inventory (MFI-20) were administered before two maximal cardiopulmonary exercise tests (CPETs) administered 24 h apart and an open-ended recovery questionnaire was administered 7 days after CPET challenge. The main outcome measures were self-reported time to recover to pre-challenge functional and symptom status, frequency of post-exertional symptoms and SF36v2 sub-scale scores. Individuals with CFS demonstrated significantly lower SF36v2 and MFI-20 sub-scale scores prior to CPET. Between-group differences remained significant post-CPET, however, there were no significant group by test interaction effects. Subjects with CFS reported significantly more total symptoms (p < 0.001), as well as reports of fatigue (p < 0.001), neuroendocrine (p < 0.001), immune (p < 0.01), pain (p < 0.01) and sleep disturbance (p < 0.01) symptoms than control subjects as a result of CPET. Many symptom counts demonstrated significant relationships with SF36v2 sub-scale scores (p < 0.05). SF36v2 and MFI-20 sub-scale scores demonstrated significant correlations (p < 0.05). Various SF36v2 sub-scale scores demonstrated significant predictive validity to identify subjects who recovered from CPET challenge within 1 day and 7 days (p < 0.05). Potential floor effects were observed for both questionnaires for individuals with CFS. Various sub-scales of SF36v2 demonstrated adequate reliability and validity for clinical and research applications. Adequacy of sensitivity to change of SF36v2 as a result of a fatiguing stressor should be the subject of additional study.

Measuring Fatigue in Persons with Spinal Cord Injury

PubMed Central

Anton, Hubert A.; Miller, William C.; Townson, Andrea F.

2013-01-01

Objective To evaluate the psychometric properties of the Fatigue Severity Scale (FSS) in persons with spinal cord injury (SCI). Design A two week methodological study was conducted to assess the internal consistency, reliability and the construct validity of the FSS. Setting A tertiary spinal cord rehabilitation facility. Participants 48 community living individuals at least one year post SCI with ASIA A or B SCI and no medical conditions causing fatigue. Main Outcome Measures The ASIA Impairment Scale; the FSS; a Visual Analogue Scale for Fatigue (VAS-F), the SF-36 vitality scale, and the Centre for Epidemiological Studies Depression – Scale (CES-D) Results Our sample was predominantly male (n=31, 65%) with tetraplegia (n=26, 54%) and ASIA A injuries (n=30, 63%). The mean FSS score at baseline was 4.4 (SD=1.4) with 54% (N=26) scoring greater than 4. The internal consistency of the FSS was Cronbach’s alpha = 0.89. Two-week test-retest reliability was ICC=0.84 (95% CI 0.74 – 0.90). The magnitude of the relationship was as hypothesized for the VAS-F(r=.67) and CES-D (r=.58) and lower than hypothesized for the vitality subscore (r=−.48) of the SF-36. Conclusions The FSS has acceptable reliability with regard to internal consistency, test-retest reliability, and validity in persons with motor complete SCI. PMID:18295634

The PedsQL Multidimensional Fatigue Scale in pediatric rheumatology: reliability and validity.

PubMed

Varni, James W; Burwinkle, Tasha M; Szer, Ilona S

2004-12-01

. The PedsQL (Pediatric Quality of Life Inventory) is a modular instrument designed to measure health related quality of life (HRQOL) in children and adolescents ages 2-18 years. The recently developed 18-item PedsQL Multidimensional Fatigue Scale was designed to measure fatigue in pediatric patients and comprises the General Fatigue Scale (6 items), Sleep/Rest Fatigue Scale (6 items), and Cognitive Fatigue Scale (6 items). The PedsQL 4.0 Generic Core Scales were developed as the generic core measure to be integrated with the PedsQL Disease-Specific Modules. The PedsQL 3.0 Rheumatology Module was designed to measure pediatric rheumatology-specific HRQOL. Methods. The PedsQL Multidimensional Fatigue Scale, Generic Core Scales, and Rheumatology Module were administered to 163 children and 154 parents (183 families accrued overall) recruited from a pediatric rheumatology clinic. Results. Internal consistency reliability for the PedsQL Multidimensional Fatigue Scale Total Score (a = 0.95 child, 0.95 parent report), General Fatigue Scale (a = 0.93 child, 0.92 parent), Sleep/Rest Fatigue Scale (a = 0.88 child, 0.90 parent), and Cognitive Fatigue Scale (a = 0.93 child, 0.96 parent) were excellent for group and individual comparisons. The validity of the PedsQL Multidimensional Fatigue Scale was confirmed through hypothesized intercorrelations with dimensions of generic and rheumatology-specific HRQOL. The PedsQL Multidimensional Fatigue Scale distinguished between healthy children and children with rheumatic diseases as a group, and was associated with greater disease severity. Children with fibromyalgia manifested greater fatigue than children with other rheumatic diseases. The results confirm the initial reliability and validity of the PedsQL Multidimensional Fatigue Scale in pediatric rheumatology.

Perceived stress and fatigue among students in a doctor of chiropractic training program.

PubMed

Kizhakkeveettil, Anupama; Vosko, Andrew M; Brash, Marissa; Ph, Dr; Philips, Michael A

2017-03-01

High levels of stress and fatigue are associated with decreased academic success, well-being, and quality of life. The objective of this research was to quantify levels of perceived stress and fatigue among chiropractic students to identify sources of and student coping mechanisms for perceived stress and fatigue and to identify the relationship between students' perceived stress and fatigue. A survey comprised of the Perceived Stress Scale, the Undergraduate Sources of Stress Survey, and the Piper Fatigue Scale was administered to chiropractic students in their 2nd, 5th, and 8th trimesters of doctoral study. Data were analyzed by descriptive statistics, 1-way analysis of variance, and linear correlation tests. Students reported having moderate to high levels of stress and fatigue, with higher levels of stress and fatigue seen in women than in men. A nonsignificant difference among stress scores and a significant difference among fatigue scores were observed based on program term. Levels of stress predicted levels of fatigue, and stress was strongly correlated with psychological health, relationships with family members, mood, and need for learning accommodations. Fatigue was strongly correlated with psychological health, academic demands, and conflicts between studies and other activities. There are differences in the reporting of perceived stress and fatigue levels in this chiropractic student population based on gender. The correlation between fatigue and stress also suggests that measures that may alleviate one may likely affect the other.

[The effects of foot reflexology on fatigue and insomnia in patients suffering from coal workers' pneumoconiosis].

PubMed

Lee, Young-Mee; Sohng, Kyeong-Yae

2005-12-01

The purpose of this study was to determine the effects of foot reflexology on fatigue and insomnia in patients suffering from coal workers' pneumoconiosis. This study was a quasi-experimental study of pre-test and post-test design in a non-equivalent control group. The subjects of this study consisted of both the experimental group of twenty-nine and the control group of thirty coal workers' pneumoconiosis patients. Data was collected from December 10, 2002 to February 15, 2003. Foot reflexology was performed for 60 minutes twice a week through five weeks in the experimental group, but none in the control group. To evaluate the effects of foot reflexology, the scores of fatigue and insomnia were measured before and after the experiment in both groups. Fatigue was evaluated by Fatigue Symptoms Inventory. Insomnia was measured with the visual analogue scale (VAS). Data of this experiment was analyzed by Chi-square test, t-test, unpaired t-test and Repeated Measures ANOVA with the SAS Program. The scores of fatigue and insomnia decreased in the experimental group but not in the control group. There was a significant difference of fatigue and insomnia between the two groups. It is suggested that foot reflexology might have beneficial effects on reducing fatigue and insomnia in patients suffering from coal workers' pneumoconiosis, and can be recommended as a nursing intervention program for patients with coal workers' pneumoconiosis.

Long-term cognitive impairments and attentional deficits in patients with Cushing's disease and cortisol-producing adrenal adenoma in remission.

PubMed

Ragnarsson, Oskar; Berglund, Peter; Eder, Derek N; Johannsson, Gudmundur

2012-09-01

Cognitive function is impaired in patients with active Cushing's syndrome (CS). The aim was to study cognitive function in patients with CS in long-term remission. We conducted a cross-sectional, case-controlled, single center study. Fifty-five patients previously treated for Cushing's disease (n = 43) and cortisol-producing adrenal adenoma (n = 12) and 55 controls matched for age, gender, and educational level participated in the study. Working memory, attention, information-processing speed, verbal fluency, and reading speed were studied using standardized neuropsychological testing and alerting, orienting, and executive control using the Attentional Network Test. Fatigue impact scale and the comprehensive psychopathological rating scale were used to evaluate fatigue and affective disorder. Median (interquartile range) duration of remission was 13 (5-19) yr and the mean ± SD age at follow-up was 54 ± 14 yr. Compared to controls, patients had a higher score on the fatigue impact scale, indicating greater burdens of fatigue, and a higher score on the comprehensive psychopathological rating scale subscales for depression and anxiety. In a multivariate analysis, attention, spatial orienting, alerting, working memory, verbal fluency, and reading speed were all diminished in comparison to controls, independent of scores for affective disorder and fatigue. No overall difference in outcome was seen between patients in long-term remission for Cushing's disease and cortisol-producing adrenal adenoma. Patients with CS in remission have impaired cognitive function that cannot be explained by the coexistence of affective disorder or chronic fatigue. The pattern of cognitive and attentional deficits suggests a more global involvement of the brain function than has previously been suggested.

Crack propagation monitoring in a full-scale aircraft fatigue test based on guided wave-Gaussian mixture model

NASA Astrophysics Data System (ADS)

Qiu, Lei; Yuan, Shenfang; Bao, Qiao; Mei, Hanfei; Ren, Yuanqiang

2016-05-01

For aerospace application of structural health monitoring (SHM) technology, the problem of reliable damage monitoring under time-varying conditions must be addressed and the SHM technology has to be fully validated on real aircraft structures under realistic load conditions on ground before it can reach the status of flight test. In this paper, the guided wave (GW) based SHM method is applied to a full-scale aircraft fatigue test which is one of the most similar test status to the flight test. To deal with the time-varying problem, a GW-Gaussian mixture model (GW-GMM) is proposed. The probability characteristic of GW features, which is introduced by time-varying conditions is modeled by GW-GMM. The weak cumulative variation trend of the crack propagation, which is mixed in time-varying influence can be tracked by the GW-GMM migration during on-line damage monitoring process. A best match based Kullback-Leibler divergence is proposed to measure the GW-GMM migration degree to reveal the crack propagation. The method is validated in the full-scale aircraft fatigue test. The validation results indicate that the reliable crack propagation monitoring of the left landing gear spar and the right wing panel under realistic load conditions are achieved.

Disk Alloy Development

NASA Technical Reports Server (NTRS)

Gabb, Tim; Gayda, John; Telesman, Jack

2001-01-01

The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA HSR/EPM disk program to have extended durability at 1150 to 1250 "Fin large disks. Scaled-up disks of this alloy were produced at the conclusion of this program to demonstrate these properties in realistic disk shapes. The objective of the UEET disk program was to assess the mechanical properties of these ME3 disks as functions of temperature, in order to estimate the maximum temperature capabilities of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor / Turbine Disk program were sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. Additional sub-scale disks and blanks were processed and tested to explore the effects of several processing variations on mechanical properties. Scaled-up disks of an advanced regional disk alloy, Alloy 10, were used to evaluate dual microstructure heat treatments. This allowed demonstration of an improved balance of properties in disks with higher strength and fatigue resistance in the bores and higher creep and dwell fatigue crack growth resistance in the rims. Results indicate the baseline ME3 alloy and process has 1300 to 1350 O F temperature capabilities, dependent on detailed disk and engine design property requirements. Chemistry and process enhancements show promise for further increasing temperature capabilities.

The effects of a home-based arm ergometry exercise programme on physical fitness, fatigue and activity in Polio survivors: a randomised controlled trial.

PubMed

Murray, D; Hardiman, O; Campion, A; Vance, R; Horgan, F; Meldrum, D

2017-07-01

To investigate the effect of an eight-week home-based arm ergometry aerobic exercise programme on physical fitness, fatigue, activity and quality of life in Polio Survivors. An assessor blinded randomised controlled trial. Home-based exercise. Fifty-five Polio survivors randomised to exercise or control groups. Home-based arm ergometry at an intensity of 50%-70% maximum heart rate, compared with usual physiotherapy care. The Six-minute Arm Test, Fatigue Severity Scale, Physical Activity Scale for Individuals with Physical Disabilities and SF-36. Assessments were completed at baseline and at eight weeks. There was no significant difference in the primary outcome, exercising heart rate during the Six-minute Arm Test, between the groups at follow-up [97.6 (SD10.1) compared to 102.4 (SD13.7) beats per minute ( P=0.20)]. Blood pressure was significantly lower in the intervention group at follow-up [systolic blood pressure 132(18.6)mmHg compared to 144.1(14.6)mmHg ( P=0.002)]. There were no between group differences in the Fatigue Severity Scale ( P=0.25) or Physical Activity Scale for Individuals with Physical Disabilities ( P=0.49), with a small difference in SF-36 physical component score ( P=0.04). This home-based arm ergometry programme successfully facilitated aerobic exercise in Polio Survivors, but did not result in a significant change in physical fitness, measured by the Six-minute Arm Test.

Cross-cultural adaptation, reliability, and validity of the Turkish version of the Cancer Fatigue Scale in patients with breast cancer

PubMed

Şahin, Sedef; Huri, Meral; Aran, Orkun Tahir; Uyanık, Mine

2018-02-23

Background/aim: The Cancer Fatigue Scale (CFS) was developed to evaluate the severity of fatigue in patients with breast cancer. The aim of this study is to translate and culturally adapt a Turkish version and investigate the validity and reliability of the CFS in Turkish patients with fatigue symptoms. Materials and methods: Eighty participants completed the Turkish version of the CFS for breast cancer and the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire ″Core 30″ (EORTC QLQ-C30). Test-retest reliability was evaluated by repeating the CFS with a 7-day interval. Results: The CFS demonstrated high test-retest reliability (ICC = 0.95) and good internal consistency (Cronbach′s alpha = 0.74) for all domains. The Kaiser-Meyer-Olkin measure of sampling adequacy was found to be 0.819, which is considered to be satisfactory (>0.5). Correlations between domains of CFS physical and EORTC physical (r: 0.77), CFS cognitive and EORTC cognitive (r: 0.70), and CFS physical and EORTC fatigue (r: 0.80) were found to be significant. Conclusion: The Turkish version of the CFS is a reliable and valid instrument to assess physical, effective, and cognitive dimensions of fatigue. The CFS may be used to evaluate the severity of fatigue in Turkish-speaking breast cancer patients.

Exercise training in adults with Pompe disease: the effects on pain, fatigue, and functioning.

PubMed

Favejee, Marein M; van den Berg, Linda E M; Kruijshaar, Michelle E; Wens, Stephan C A; Praet, Stephan F E; Pim Pijnappel, W W M; van Doorn, Pieter A; Bussmann, Johannes B J; van der Ploeg, Ans T

2015-05-01

To assess if a 12-week exercise intervention to improve aerobic fitness, muscle strength, and core stability also had an impact on fatigue, pain, activity, and participation in adults with Pompe disease, an inherited neuromuscular disorder. Open-label trial. Change was assessed by the chi-square test and Wilcoxon signed-rank test. Physiotherapy practices. Mildly affected adult patients with Pompe disease who were not dependent on ventilators and/or walking devices and were receiving enzyme replacement therapy. Patients participated in a 12-week exercise program, which included 36 sessions of standardized aerobic, resistance, and core stability exercises. Before and after the training program we evaluated fatigue (Fatigue Severity Scale), pain (yes/no), motor function (Quantitative Muscle Function Test, Rasch-built Pompe-specific Activity Scale), amount of physical activity (activity monitor), and health status (Medical Outcomes Study 36-Item Short-Form Health Survey). Of the 25 patients enrolled, 23 completed the program. At the end of the program, levels of fatigue (median, 5.33 to 4.78, P=.01) and pain (56.5% to 21.7%, P=.04) improved. The quality of motor function and the amount of physical activity patients engaged in did not change. Changes in pain and fatigue were not related to improvements in aerobic fitness or muscle strength. This study in mildly affected adult patients with Pompe disease suggests that a combined training program aiming to increase aerobic fitness, muscle strength, and core stability also leads to improvements in fatigue and pain. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

The Characteristics of Fatigue Damage in the Fuselage Riveted Lap Splice Joint

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.

1997-01-01

An extensive data base has been developed to form the physical basis for new analytical methodology to predict the onset of widespread fatigue damage in the fuselage lap splice joint. The results of detailed destructive examinations have been cataloged to describe the physical nature of MSD in the lap splice joint. ne catalog includes a detailed description, e.g., crack initiation, growth rates, size, location, and fracture morphology, of fatigue damage in the fuselage lap splice joint structure. Detailed examinations were conducted on a lap splice joint panel removed from a full scale fuselage test article after completing a 60,000 cycle pressure test. The panel contained a four bay region that exhibited visible outer skin cracks and regions of crack link-up along the upper rivet row. Destructive examinations revealed undetected fatigue damage in the outer skin, inner skin, and tear strap regions. Outer skin fatigue cracks were found to initiate by fretting damage along the faying surface. The cracks grew along the faying surface to a length equivalent to two to three skin thicknesses before penetrating the outboard surface of the outer skin. Analysis of fracture surface marker bands produced during full scale testing revealed that all upper rivet row fatigue cracks contained in a dim bay region grow at similar rates; this important result suggests that fracture mechanics based methods can be used to predict the growth of outer skin fatigue cracks in lap splice structure. Results are presented showing the affects of MSD and out-of-plane pressure loads on outer skin crack link-up.

The PedsQL multidimensional fatigue scale in pediatric obesity: feasibility, reliability and validity.

PubMed

Varni, James W; Limbers, Christine A; Bryant, William P; Wilson, Don P

2010-01-01

The PedsQL (Pediatric Quality of Life Inventory) is a modular instrument designed to measure health-related quality of life (HRQOL) and disease-specific symptoms in children and adolescents. The PedsQL Multidimensional Fatigue Scale was designed as a child self-report and parent proxy-report generic symptom-specific instrument to measure fatigue in pediatric patients. The objective of the present study was to determine the feasibility, reliability, and validity of the PedsQL Multidimensional Fatigue Scale in pediatric obesity. The 18-item PedsQL Multidimensional Fatigue Scale (General Fatigue, Sleep/Rest Fatigue, and Cognitive Fatigue domains) and the PedsQL 4.0 Generic Core Scales were completed by 41 pediatric patients with a physician-diagnosis of obesity and 43 parents from a hospital-based Pediatric Endocrinology Clinic. The PedsQL Multidimensional Fatigue Scale evidenced minimal missing responses (1.6%, child report; 0.5%, parent report), achieved excellent reliability for the Total Fatigue Scale Score (alpha = 0.90 child report, 0.90 parent report), distinguished between pediatric patients with obesity and healthy children, and was significantly correlated with the PedsQL 4.0 Generic Core Scales supporting construct validity. Pediatric patients with obesity experienced fatigue comparable with pediatric patients receiving cancer treatment, demonstrating the relative severity of their fatigue symptoms. The results demonstrate the measurement properties of the PedsQL Multidimensional Fatigue Scale in pediatric obesity. The findings suggest that the PedsQL Multidimensional Fatigue Scale may be utilized in the standardized evaluation of fatigue in pediatric patients with obesity.

Fatigue Effect on Low-Frequency Force Fluctuations and Muscular Oscillations during Rhythmic Isometric Contraction

PubMed Central

Lin, Yen-Ting; Kuo, Chia-Hua; Hwang, Ing-Shiou

2014-01-01

Continuous force output containing numerous intermittent force pulses is not completely smooth. By characterizing force fluctuation properties and force pulse metrics, this study investigated adaptive changes in trajectory control, both force-generating capacity and force fluctuations, as fatigue progresses. Sixteen healthy subjects (20–24 years old) completed rhythmic isometric gripping with the non-dominant hand to volitional failure. Before and immediately following the fatigue intervention, we measured the gripping force to couple a 0.5 Hz sinusoidal target in the range of 50–100% maximal voluntary contraction. Dynamic force output was off-line decomposed into 1) an ideal force trajectory spectrally identical to the target rate; and 2) a force pulse trace pertaining to force fluctuations and error-correction attempts. The amplitude of ideal force trajectory regarding to force-generating capacity was more suppressed than that of the force pulse trace with increasing fatigue, which also shifted the force pulse trace to lower frequency bands. Multi-scale entropy analysis revealed that the complexity of the force pulse trace at high time scales increased with fatigue, contrary to the decrease in complexity of the force pulse trace at low time scales. Statistical properties of individual force pulses in the spatial and temporal domains varied with muscular fatigue, concurrent with marked suppression of gamma muscular oscillations (40–60 Hz) in the post-fatigue test. In conclusion, this study first reveals that muscular fatigue impairs the amplitude modulation of force pattern generation more than it affects the amplitude responsiveness of fine-tuning a force trajectory. Besides, motor fatigue results disadvantageously in enhancement of motor noises, simplification of short-term force-tuning strategy, and slow responsiveness to force errors, pertaining to dimensional changes in force fluctuations, scaling properties of force pulse, and muscular oscillation. PMID:24465605

Evaluation of the fuselage lap joint fatigue and terminating action repair

NASA Technical Reports Server (NTRS)

Samavedam, Gopal; Thomson, Douglas; Jeong, David Y.

1994-01-01

Terminating action is a remedial repair which entails the replacement of shear head countersunk rivets with universal head rivets which have a larger shank diameter. The procedure was developed to eliminate the risk of widespread fatigue damage (WFD) in the upper rivet row of a fuselage lap joint. A test and evaluation program has been conducted by Foster-Miller, Inc. (FMI) to evaluate the terminating action repair of the upper rivet row of a commercial aircraft fuselage lap splice. Two full scale fatigue tests were conducted on fuselage panels using the growth of fatigue cracks in the lap joint. The second test was performed to evaluate the effectiveness of the terminating action repair. In both tests, cyclic pressurization loading was applied to the panels while crack propagation was recorded at all rivet locations at regular intervals to generate detailed data on conditions of fatigue crack initiation, ligament link-up, and fuselage fracture. This program demonstrated that the terminating action repair substantially increases the fatigue life of a fuselage panel structure and effectively eliminates the occurrence of cracking in the upper rivet row of the lap joint. While high cycle crack growth was recorded in the middle rivet row during the second test, failure was not imminent when the test was terminated after cycling to well beyond the service life. The program also demonstrated that the initiation, propagation, and linkup of WFD in full-scale fuselage structures can be simulated and quantitatively studied in the laboratory. This paper presents an overview of the testing program and provides a detailed discussion of the data analysis and results. Crack distribution and propagation rates and directions as well as frequency of cracking are presented for both tests. The progression of damage to linkup of adjacent cracks and to eventual overall panel failure is discussed. In addition, an assessment of the effectiveness of the terminating action repair and the occurrence of cracking in the middle rivet row is provided, and conclusions of practical interest are drawn.

Development of an Image-based Multi-Scale Finite Element Approach to Predict Fatigue Damage in Asphalt Mixtures

NASA Astrophysics Data System (ADS)

Arshadi, Amir

Image-based simulation of complex materials is a very important tool for understanding their mechanical behavior and an effective tool for successful design of composite materials. In this thesis an image-based multi-scale finite element approach is developed to predict the mechanical properties of asphalt mixtures. In this approach the "up-scaling" and homogenization of each scale to the next is critically designed to improve accuracy. In addition to this multi-scale efficiency, this study introduces an approach for consideration of particle contacts at each of the scales in which mineral particles exist. One of the most important pavement distresses which seriously affects the pavement performance is fatigue cracking. As this cracking generally takes place in the binder phase of the asphalt mixture, the binder fatigue behavior is assumed to be one of the main factors influencing the overall pavement fatigue performance. It is also known that aggregate gradation, mixture volumetric properties, and filler type and concentration can affect damage initiation and progression in the asphalt mixtures. This study was conducted to develop a tool to characterize the damage properties of the asphalt mixtures at all scales. In the present study the Viscoelastic continuum damage model is implemented into the well-known finite element software ABAQUS via the user material subroutine (UMAT) in order to simulate the state of damage in the binder phase under the repeated uniaxial sinusoidal loading. The inputs are based on the experimentally derived measurements for the binder properties. For the scales of mastic and mortar, the artificially 2-Dimensional images of mastic and mortar scales were generated and used to characterize the properties of those scales. Finally, the 2D scanned images of asphalt mixtures are used to study the asphalt mixture fatigue behavior under loading. In order to validate the proposed model, the experimental test results and the simulation results were compared. Indirect tensile fatigue tests were conducted on asphalt mixture samples. A comparison between experimental results and the results from simulation shows that the model developed in this study is capable of predicting the effect of asphalt binder properties and aggregate micro-structure on mechanical behavior of asphalt concrete under loading.

Functional assessment of chronic illness therapy—the fatigue scale exhibits stronger associations with clinical parameters in chronic dialysis patients compared to other fatigue-assessing instruments

PubMed Central

Chao, Chia-Ter; Huang, Jenq-Wen

2016-01-01

Background. Patients with end-stage renal disease (ESRD) have a high symptom burden, among which fatigue is highly prevalent. Many fatigue-assessing instruments exist, but comparisons among instruments in this patient population have yet to be investigated. Methods. ESRD patients under chronic hemodialysis were prospectively enrolled and seven types of fatigue instruments were administered: Brief Fatigue Inventory (BFI), Functional Assessment of Chronic Illness Therapy–Fatigue (FACIT-F), Fatigue Severity Scale (FSS), Lee Fatigue Scale (LFS), Fatigue Questionnaire (FQ), Fatigue Symptom Inventory (FSI), and Short-Form 36-Vitality (SF36-V). Using these instruments, we investigated the correlation between fatigue severity and clinical/biochemical parameters, including demographic/comorbidity profile, dialysis-related complications, and frailty severity. We used regression analysis with serum albumin and frailty severity as the dependent variables to investigate the independent correlations. Results. A total of 46 ESRD patients were enrolled (average age of 67 ± 11.6 years), and 50% of them had type 2 diabetes mellitus. Results from the seven tested instruments showed high correlation with each other. We found that the fatigue severity by FACIT-F was significantly associated with age (p = 0.03), serum albumin (p = 0.003) and creatinine (p = 0.02) levels, while SF36-V scores were also significantly associated with age (p = 0.02) and serum creatinine levels (p = 0.04). However, the fatigue severity measured by the FSS, FSI, FQ, BFI, and LFS did not exhibit these associations. Moreover, regression analysis showed that only FACIT-F scores were independently associated with serum albumin levels and frailty severity in ESRD patients. Conclusion. Among the seven fatigue-assessing instruments, only the FACIT-F yielded results that demonstrated significant and independent associations with important outcome-related features in ESRD patients. PMID:26998414

Different types of exercise in Multiple Sclerosis: Aerobic exercise or Pilates, a single-blind clinical study.

PubMed

Kara, Bilge; Küçük, Fadime; Poyraz, Esra Coşkuner; Tomruk, Melda Soysal; İdıman, Egemen

2017-01-01

The aim of our study is to examine effects of aerobic and Pilates exercises on disability, cognition, physical performance, balance, depression and fatigue in relapsing-remitting Multiple Sclerosis (MS) patients as compared to healthy controls. The subjects were divided as aerobic exercise (n = 26), Pilates (n = 9), and the healthy control group (n = 21). We used MSFC, physical performance, Berg balance scale, Beck depression scale, fatigue impact scale. All evaluations were performed before and after exercise training. There are statistically meaningful differences between Nine hole testing, PASAT 3, physical performance and fatique impact scale before and after aerobic exercise. Also we found significant difference for physical performance in the Pilates group. There are no significant differences in measures of fatique impact scale and depression between aerobic exercise group and the healthy controls after exercise. We found significant differences between Pilates and control group's after measurements except depression. There were significant differences between the Pilates and aerobic group for cognitive tests in favor of the Pilates group. Aerobic exercise and clinical Pilates exercises revealed moderate changes in levels of cognitive, physical performance, balance, depression, fatigue in MS patients.

The PedsQL Multidimensional Fatigue Scale in type 1 diabetes: feasibility, reliability, and validity.

PubMed

Varni, James W; Limbers, Christine A; Bryant, William P; Wilson, Don P

2009-08-01

The Pediatric Quality of Life Inventory (PedsQL, Mapi Research Trust, Lyon, France; www.pedsql.org) is a modular instrument designed to measure health-related quality of life and disease-specific symptoms in children and adolescents. The PedsQL Multidimensional Fatigue Scale was designed as a child self-report and parent proxy-report generic symptom-specific instrument to measure fatigue in pediatric patients. The objective of the present study was to determine the feasibility, reliability, and validity of the PedsQL Multidimensional Fatigue Scale in type 1 diabetes. The 18-item PedsQL Multidimensional Fatigue Scale (General Fatigue, Sleep/Rest Fatigue, and Cognitive Fatigue domains) and the PedsQL 4.0 Generic Core Scales were administered to 83 pediatric patients with type 1 diabetes and 84 parents. The PedsQL Multidimensional Fatigue Scale evidenced minimal missing responses (0.3% child report and 0.3% parent report), achieved excellent reliability for the Total Fatigue Scale score (alpha= 0.92 child report, 0.94 parent report), distinguished between pediatric patients with diabetes and healthy children, and was significantly correlated with the PedsQL 4.0 Generic Core Scales supporting construct validity. Pediatric patients with diabetes experienced fatigue that was comparable to pediatric patients with cancer on treatment, demonstrating the relative severity of their fatigue symptoms. The results demonstrate the measurement properties of the PedsQL Multidimensional Fatigue Scale in type 1 diabetes. The findings suggest that the PedsQL Multidimensional Fatigue Scale may be utilized in the standardized evaluation of fatigue in pediatric patients with type 1 diabetes.

Pharmacological treatments for fatigue in patients with multiple sclerosis: A systematic review and meta-analysis.

PubMed

Yang, Ting-Ting; Wang, Li; Deng, Xiao-Yang; Yu, Gang

2017-09-15

Multiple sclerosis (MS) is a chronic immune-mediated inflammatory disease. Fatigue is the most common symptom of MS patients, affecting >80% subjects. Medical treatment is an important method for managing fatigue. Currently, although many drugs have been tested in treatment of MS fatigue, the efficacy of these drugs remain largely unclear. We researched available literatures in PubMed, Embase, Medline, Google Scholar, Cochrane Library (August 31, 2016). Search terms included multiple sclerosis, fatigue, medication treatments, amantadine, modafinil, aspirin, acetyl-l-carnitine, pemoline, 4-aminopyridine and randomized controlled trial (RCT). Two researchers were required to independently assess the quality of literatures, and finish data extraction. Meta-analysis was conducted using RevMan 5.3 software. A total of 11 RCTs involving 723 patients were included. The therapeutic effects were quantified by different scales, such as Modified Fatigue Impact Scale (MFIS) or Fatigue Severity Scale (FSS). Here, meta-analysis suggested that amantadine, not modafinil, was effective for treating the fatigue in MS. Moreover, two studies implied that l-carnitine might have similar therapeutic effect with amantadine. However, the reliability of this finding was greatly weakened by the limited sample sizes. Additionally, current data could not answer whether treatment of MS fatigue using aspirin or 4-aminopyridine was beneficial. Finally, we found that all drugs except pemoline were relatively safe for treating MS fatigue. Current limited data suggest that amantadine may be the only drug that has relatively sufficient evidences in treatment of fatigue symptoms in MS. Further RCT studies recruiting larger samples sizes are required to validate the therapeutic effect of these candidate drugs. Copyright © 2017. Published by Elsevier B.V.

Multidimensional fatigue inventory and post-polio syndrome - a Rasch analysis.

PubMed

Dencker, Anna; Sunnerhagen, Katharina S; Taft, Charles; Lundgren-Nilsson, Åsa

2015-02-12

Fatigue is a common symptom in post-polio syndrome (PPS) and can have a substantial impact on patients. There is a need for validated questionnaires to assess fatigue in PPS for use in clinical practice and research. The aim with this study was to assess the validity and reliability of the Swedish version of Multidimensional Fatigue Inventory (MFI-20) in patients with PPS using the Rasch model. A total of 231 patients diagnosed with PPS completed the Swedish MFI-20 questionnaire at post-polio out-patient clinics in Sweden. The mean age of participants was 62 years and 61% were females. Data were tested against assumptions of the Rasch measurement model (i.e. unidimensionality of the scale, good item fit, independency of items and absence of differential item functioning). Reliability was tested with the person separation index (PSI). A transformation of the ordinal total scale scores into an interval scale for use in parametric analysis was performed. Dummy cases with minimum and maximum scoring were used for the transformation table to achieve interval scores between 20 and 100, which are comprehensive limits for the MFI-20 scale. An initial Rasch analysis of the full scale with 20 items showed misfit to the Rasch model (p < 0.001). Seven items showed slightly disordered thresholds and person estimates were not significantly improved by rescoring items. Analysis of MFI-20 scale with the 5 MFI-20 subscales as testlets showed good fit with a non-significant x (2) value (p = 0.089). PSI for the testlet solution was 0.86. Local dependency was present in all subscales and fit to the Rasch model was solved with testlets within each subscale. PSI ranged from 0.52 to 0.82 in the subscales. This study shows that the Swedish MFI-20 total scale and subscale scores yield valid and reliable measures of fatigue in persons with post-polio syndrome. The Rasch transformed total scores can be used for parametric statistical analyses in future clinical studies.

Translation and validation of the Cancer-Related Fatigue Scale in Greek in a sample of patients with advanced prostate cancer.

PubMed

Charalambous, Andreas; Kaite, Charis; Constantinou, Marianna; Kouta, Christiana

2016-12-02

To translate and validate the Cancer-Related Fatigue (CRF) Scale in the Greek language. A cross-sectional descriptive design was used in order to translate and validate the CRF Scale in Greek. Factor analyses were performed to understand the psychometric properties of the scale and to establish construct, criterion and convergent validity. Outpatients' oncology clinics of two public hospitals in Cyprus. 148 patients with advanced prostate cancer undergoing chemotherapy. The Cancer Fatigue Scale (CFS) had good stability (test-retest reliability r=0.79, p<0.001) and good internal consistency (Cronbach's α coefficient for all 15 items α=0.916). Furthermore, the Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO value) was found to be 0.743 and considered to be satisfactory (>0.5). The correlations between the CFS physical scale (CFS-FS scale) and the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 physical subscales were found to be significant (r=-0.715). The same occurred between CFS cognitive and EORTC cognitive subscale (r=-0.579). Overall, the criterion validity was verified. The same occurs for the convergent validity of the CFS since all correlations with the Global Health Status (q29-q30) were found to be significant. This is the first validation study of the CRF Scale in Greek and warrant of its use in the assessment of prostate cancer patient's related fatigue. However, further testing and validation is needed in the early stages of the disease and in patients in later chemotherapy cycles. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Exercise capacity, muscle strength and fatigue in sarcoidosis.

PubMed

Marcellis, R G J; Lenssen, A F; Elfferich, M D P; De Vries, J; Kassim, S; Foerster, K; Drent, M

2011-09-01

The aim of this case-control study was to investigate the prevalence of exercise intolerance, muscle weakness and fatigue in sarcoidosis patients. Additionally, we evaluated whether fatigue can be explained by exercise capacity, muscle strength or other clinical characteristics (lung function tests, radiographic stages, prednisone usage and inflammatory markers). 124 sarcoidosis patients (80 males) referred to the Maastricht University Medical Centre (Maastricht, the Netherlands) were included (mean age 46.6±10.2 yrs). Patients performed a 6-min walk test (6MWT) and handgrip force (HGF), elbow flexor muscle strength (EFMS), quadriceps peak torque (QPT) and hamstring peak torque (HPT) tests. Maximal inspiratory pressure (P(I,max)) was recorded. All patients completed the Fatigue Assessment Scale (FAS) questionnaire. The 6MWT was reduced in 45% of the population, while HGF, EFMS, QPT and HPT muscle strength were reduced in 15, 12, 27 and 18%, respectively. P(I,max) was reduced in 43% of the population. The majority of the patients (81%) reported fatigue (FAS ≥22). Patients with reduced peripheral muscle strength of the upper and/or lower extremities were more fatigued and demonstrated impaired lung functions, fat-free mass, P(I,max), 6MWT and quality of life. Fatigue was neither predicted by exercise capacity, nor by muscle strength. Besides fatigue, exercise intolerance and muscle weakness are frequent problems in sarcoidosis. We therefore recommend physical tests in the multidisciplinary management of sarcoidosis patients, even in nonfatigued patients.

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox.

PubMed

Harris, R J D; Doolette, D J; Wilkinson, D C; Williams, D J

2003-01-01

Many divers report less fatigue following diving breathing oxygen rich N2-O2 mixtures compared with breathing air. In this double blinded, randomized controlled study 11 divers breathed either air or Enriched Air Nitrox 36% (oxygen 36%, nitrogen 64%) during an 18 msw (281 kPa(a)) dry chamber dive for a bottom time of 40 minutes. Two periods of exercise were performed during the dive. Divers were assessed before and after each dive using the Multidimensional Fatigue Inventory-20, a visual analogue scale, Digit Span Tests, Stroop Tests, and Divers Health Survey (DHS). Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas.

A combined inspiratory and expiratory muscle training program improves respiratory muscle strength and fatigue in multiple sclerosis.

PubMed

Ray, Andrew D; Udhoji, Supriya; Mashtare, Terry L; Fisher, Nadine M

2013-10-01

To determine the effects of a short-duration, combined (inspiratory and expiratory), progressive resistance respiratory muscle training (RMT) protocol on respiratory muscle strength, fatigue, health-related quality of life, and functional performance in individuals with mild-to-moderate multiple sclerosis (MS). Quasi-experimental before-after trial. University rehabilitation research laboratory. Volunteers with MS (N=21) were divided into 2 groups: RMT (n=11; 9 women, 2 men; mean age ± SD, 50.9 ± 5.7y, mean Expanded Disability Status Scale score ± SD, 3.2 ± 1.9) and a control group that did not train (n=10; 7 women, 3 men; mean age ± SD, 56.2 ± 8.8y, mean Expanded Disability Status Scale score ± SD, 4.4 ± 2.1). Expanded Disability Status Scale scores ranged from 1 to ≤6.5. No patients withdrew from the study. Training was a 5-week combined progressive resistance RMT program, 3d/wk, 30 minutes per session. The primary outcome measures were maximal inspiratory pressure and expiratory pressure and the Modified Fatigue Impact Scale. All subjects completed secondary measures of pulmonary function, the six-minute walk test, the timed stair climb, the Multiple Sclerosis Self-Efficacy Scale, the Medical Outcomes Study 36-Item Short-Form Health Survey, and the Physical Activity Disability Scale. Maximal inspiratory pressure and expiratory pressure (mean ± SD) increased 35% ± 22% (P<.001) and 26% ± 17% (P<.001), respectively, whereas no changes were noted in the control group (12% ± 23% and -4% ± 17%, respectively). RMT improved fatigue (Modified Fatigue Impact Scale, P<.029), with no change or worsening in the control group. No changes were noted in the six-minute walk test, stair climb, Multiple Sclerosis Self-Efficacy Scale, or Physical Activity Disability Scale in the RMT group. The control group had decreases in emotional well-being and general health (Medical Outcomes Study 36-Item Short-Form Health Survey). A short-duration, combined RMT program improved inspiratory and expiratory muscle strength and reduced fatigue in patients with mild to moderate MS. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Psychometric properties of instruments used to measure fatigue in children and adolescents with cancer: a systematic review.

PubMed

Tomlinson, Deborah; Hinds, Pamela S; Ethier, Marie-Chantal; Ness, Kirsten K; Zupanec, Sue; Sung, Lillian

2013-01-01

Despite the recognized distressing symptom of fatigue in children with cancer, little information is available to assist in the selection of an instrument to be used to measure fatigue. The objectives of this study were to 1) describe the instruments that have been used to measure cancer-related fatigue in children and adolescents and 2) summarize the psychometric properties of the most commonly used instruments used to measure fatigue in children and adolescents with cancer. Five major electronic databases were systematically searched for studies using a fatigue measurement scale in a population of children or adolescents with cancer. Fatigue scales used in those studies were included in the review. From a total of 1753 articles, 25 were included. We identified two main fatigue measurement instruments used in a pediatric oncology population: 1) the Fatigue Scale-Child/Fatigue Scale-Adolescent and the proxy report versions for parents and staff and 2) the PedsQL™ Multidimensional Fatigue Scale. These two scales show similar attributes with reasonably good internal consistency and responsiveness. Either the Fatigue Scale or PedsQL Multidimensional Fatigue Scale can be incorporated into clinical research. Future research should focus on identifying specific fatigue measures more suited to different purposes such as comparative trials or identification of high-risk groups. Copyright © 2013 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

Thermomechanical fatigue life prediction for several solders

NASA Astrophysics Data System (ADS)

Wen, Shengmin

Since solder connections operate at high homologous temperature, solders are high temperature materials. This feature makes their mechanical behavior and fatigue phenomena unique. Based on experimental findings, a physical damage mechanism is introduced for solders. The mechanism views the damage process as a series of independent local damage events characterized by the failure of individual grains, while the structural damage is the eventual percolation result of such local events. Fine's dislocation energy density concept and Mura's microcrack initiation theory are adopted to derive the fatigue formula for an individual grain. A physical damage metric is introduced to describe the material with damage. A unified creep and plasticity constitutive model is adopted to simulate the mechanical behavior of solders. The model is cast into a continuum damage mechanics framework to simulate material with damage. The model gives good agreement with the experimental results of 96.5Pb-3.5Sn and 96.5Sn-3.5Ag solders under uniaxial strain-controlled cyclic loading. The model is convenient for implementation into commercial computational packages. Also presented is a fatigue theory with its failure criterion for solders based on physical damage mechanism. By introducing grain orientation into the fatigue formula, an m-N curve (m is Schmid factor) at constant loading condition is suggested for fatigue of grains with different orientations. A solder structure is defined as fatigued when the damage metric reaches a critical threshold, since at this threshold the failed grains may form a cluster and percolate through the structure according to percolation theory. Fatigue data of 96.5Pb-3.5Sn solder bulk specimens under various uniaxial tension tests were analyzed. Results show that the theory gives consistent predictions under broad conditions, while inelastic strain theory does not. The theory is anisotropic with no size limitation to its application, which could be suitable for anisotropic small-scale (micron or nano scale) solder joints. More importantly, the theory is materials science based so that the parameters of the fatigue formula can be worked out by testing of bulk specimens while the formula can be applicable to small-scale structures. The theory suggests metallurgical control in the manufacturing process to optimize the fatigue life of solder structures.

Multidisciplinary pain facility treatment outcome for pain-associated fatigue.

PubMed

Fishbain, David A; Lewis, John; Cole, Brandly; Cutler, Brian; Smets, Eve; Rosomoff, Hubert; Rosomoff, Rennee Steele

2005-01-01

Fatigue is frequently found in chronic pain patients (CPPs) and may be etiologically related to the presence of pain. Fishbain et al. have recently demonstrated that chronic low back pain (LBP) and chronic neck pain patients are more fatigued than controls. The purpose of this study was to determine whether chronic LBP- and chronic neck pain-associated fatigue responded to multidisciplinary multimodal treatment not specifically targeted to the treatment of fatigue. A total of 85 chronic LBP and 33 chronic neck pain patients completed the Multidimensional Fatigue Inventory (MFI), Neuropathic Pain Scale (NPS), and Beck Depression Inventory on admission. In addition, an information tool was completed on each CPP by the senior author. This tool listed demographic information, primary and secondary pain diagnoses, Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) psychiatric diagnoses assigned, pain location, pain precipitating event, type of injury, years in pain, number of surgeries, type of surgery, type of pain pattern, opioids consumed per day in morphine equivalents, worker compensation status, and whether, according to the clinical examination, the CPP had a neuropathic pain component. At completion of the multidisciplinary multimodal treatment, each CPP again completed the MFI. Student's t-test was utilized to test for statistical changes on the MFI five scales from pre- to post-treatment. Pearson and point-biserial correlations were utilized to determine which variables significantly correlated with MFI change scores. Variables found significant at less than or equal to 0.01 were utilized in a stepwise aggression analysis to find variables predictive of change in MFI scores. Multidisciplinary pain facility. Chronic LBP and chronic neck pain patients. Multidisciplinary multimodal treatment significantly improved CPP fatigue as measured by the MFI. The available variables utilized to predict fatigue best explained only a small percentage (28.9%) of the variance. Improvement in fatigue was related to NPS-10 scale scores (neuropathic pain) and a previous diagnosis of fibromyalgia. Multidisciplinary multimodal pain facility treatment improves chronic LBP- and neck pain-associated fatigue. At the present time we cannot predict this improvement with significant accuracy.

Evaluation of Orientation Dependence of Fracture Toughness and Fatigue Crack Propagation Behavior of As-Deposited ARCAM EBM Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Seifi, Mohsen; Dahar, Matthew; Aman, Ron; Harrysson, Ola; Beuth, Jack; Lewandowski, John J.

2015-03-01

This preliminary work documents the effects of test orientation with respect to build and beam raster directions on the fracture toughness and fatigue crack growth behavior of as-deposited EBM Ti-6Al-4V. Although ASTM/ISO standards exist for determining the orientation dependence of various mechanical properties in both cast and wrought materials, these standards are evolving for materials produced via additive manufacturing (AM) techniques. The current work was conducted as part of a larger America Makes funded project to begin to examine the effects of process variables on the microstructure and fracture and fatigue behavior of AM Ti-6Al-4V. In the fatigue crack growth tests, the fatigue threshold, Paris law slope, and overload toughness were determined at different load ratios, R, whereas fatigue precracked samples were tested to determine the fracture toughness. The as-deposited material exhibited a fine-scale basket-weave microstructure throughout the build, and although fracture surface examination revealed the presence of unmelted powders, disbonded regions, and isolated porosity, the resulting mechanical properties were in the range of those reported for cast and wrought Ti-6Al-4V. Remote access and control of testing was also developed at Case Western Reserve University to improve efficiency of fatigue crack growth testing.

Psychometric properties and Dutch norm data of the PedsQL Multidimensional Fatigue Scale for Young Adults.

PubMed

Haverman, Lotte; Limperg, Perrine F; van Oers, Hedy A; van Rossum, Marion A J; Maurice-Stam, Heleen; Grootenhuis, Martha A

2014-12-01

The aim of this study was to assess internal consistency and construct validity (known-groups validity) and to provide Dutch norm data for the Dutch Pediatric Quality of Life Inventory Multidimensional Fatigue Scale for Young Adults ages 18-30 years (PedsQL fatigue_YA). A Dutch sample of 649 young adults completed online a sociodemographic questionnaire and the PedsQL fatigue_YA including three subscales: general fatigue, sleep/rest fatigue and cognitive fatigue (0-100: Higher scores indicate less fatigue symptoms). The PedsQL fatigue_YA showed satisfactory to good internal consistency (Cronbach's alpha = .70-.94), except for one scale (.68). The mean scale scores were 68.23 (SD 19.15) for 'general fatigue,' 67.04 (SD 15.54) for 'sleep/rest fatigue' and 74.62 (SD 19.02) for 'cognitive fatigue.' Men reported significantly higher scores on 'general fatigue' and 'sleep/rest fatigue' than women. The PedsQL fatigue_YA distinguished between healthy young adults and young adults with chronic health conditions, with higher scores on all scales in healthy young adults than in those with a chronic health condition. The results demonstrate good psychometric properties of the PedsQL fatigue_YA in a sample of Dutch young adults. With the current norms available, it is possible to evaluate fatigue in the Netherlands from childhood to adulthood with the PedsQL Multidimensional Fatigue Scale.

Effect of an amorphous titania nanotubes coating on the fatigue and corrosion behaviors of the biomedical Ti-6Al-4V and Ti-6Al-7Nb alloys.

PubMed

Campanelli, Leonardo Contri; Bortolan, Carolina Catanio; da Silva, Paulo Sergio Carvalho Pereira; Bolfarini, Claudemiro; Oliveira, Nilson Tadeu Camarinho

2017-01-01

An array of self-organized TiO 2 nanotubes with an amorphous structure was produced on the biomedical Ti-6Al-4V and Ti-6Al-7Nb alloys, and the resulting fatigue and corrosion behaviors were studied. The electrochemical response of the nanotubular oxide surfaces was investigated in Ringer physiological solution through potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The absence of transpassivation in the chloride-containing solution, in addition to the micron-scale values of the passivation current density, indicated the excellent corrosion behavior of the coating and the satisfactory protection against the creation of potential stress concentrators in the surface. Axial fatigue tests were performed in physiological solution on polished and coated conditions, with characterization of the treated surfaces by scanning electron microscopy before and after the tests. The surface modification was not deleterious to the fatigue response of both alloys mainly due to the nano-scale dimension of the nanotubes layer. An estimation based on fracture mechanics revealed that a circumferential crack in the range of 5μm depth would be necessary to affect the fatigue performance, which is far from the thickness of the studied coating, although no cracks were actually observed in the oxide surfaces after the tests. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fatigue Failure of Space Shuttle Main Engine Turbine Blades

NASA Technical Reports Server (NTRS)

Swanson, Gregrory R.; Arakere, Nagaraj K.

2000-01-01

Experimental validation of finite element modeling of single crystal turbine blades is presented. Experimental results from uniaxial high cycle fatigue (HCF) test specimens and full scale Space Shuttle Main Engine test firings with the High Pressure Fuel Turbopump Alternate Turbopump (HPFTP/AT) provide the data used for the validation. The conclusions show the significant contribution of the crystal orientation within the blade on the resulting life of the component, that the analysis can predict this variation, and that experimental testing demonstrates it.

Modafinil treatment for fatigue in HIV+ patients: a pilot study.

PubMed

Rabkin, Judith G; McElhiney, Martin C; Rabkin, Richard; Ferrando, Stephen J

2004-12-01

Fatigue is widespread among human immunodeficiency virus-positive (HIV+) patients, yet few studies have assessed effective treatments. The authors conducted a pilot study to evaluate the efficacy of modafinil for fatigue in this clinical population. Response was evaluated after a 4-week open-label trial. Data were collected from February 2003 through January 2004. Responders were offered 8 additional weeks of modafinil. Inclusion criteria included written approval from the primary care physician, clinically significant fatigue, current use of anti-retroviral medications, and the absence of treatable medical conditions known to cause fatigue. Exclusion criteria included untreated major depression and current substance abuse. Major outcome measures were the Fatigue Severity Scale, Chalder Fatigue Scale, Hamilton Rating Scale for Depression, Beck Depression Inventory, and neuropsychological tests assessing verbal memory, speed of processing, and executive function. Immunologic and virologic measures were performed at baseline and week 4 to assess safety of treatment. All 30 patients who enrolled completed 4 weeks of treatment; 24 (80%) were rated as responders. Responders showed statistically significant improvement on all measures of fatigue, depressive symptoms, and executive function, while nonresponders did not. Mean values of CD4 cell count and HIV RNA viral load did not change. The most common side effect was headache, followed by irritability and feeling "hyper." This pilot study shows encouraging results for modafinil in alleviation of fatigue in HIV+ patients. In addition, depressive symptoms were substantially reduced. Improvements on measures of verbal memory and executive function were significant, but in the absence of a placebo control, the magnitude of effect due to practice cannot be determined.

Physical activity is Associated with Reduced Fatigue in Adults Living with HIV/AIDS

PubMed Central

Perazzo, Joe; Decker, Michael; Horvat-Davey, Christine; Sattar, Abdus; Voss, Joachim

2016-01-01

Aims To describe the relationships among home-based physical activity, fatigue, sleep, gender and quality of life in people living with HIV/AIDS Background Fatigue is a common and distressing symptom among people living with HIV/AIDS. Few interventions exist that effectively reduce fatigue in this population. Physical activity has shown promise to reduce fatigue in other populations, but its impact on fatigue in HIV/AIDS has not yet been explored. Design This study was conducted using a prospective, descriptive cohort design. Methods Overall, 90 adults living with HIV/AIDS completed cross-sectional measures. Home-based physical activity was measured using a seven-day self-report diary. Fatigue was measured using the self-reported HIV-Related Fatigue Scale. Sleep was assessed using wrist actigraphy and quality of life was assessed using the HIV-Associated Quality of Life Scale. Data were collected from December 2012 – April 2013 and analyzed using correlations and multiple linear regression. Results The number of minutes of home-based physical activity was significantly associated with reduced fatigue among people living with HIV/AIDS. Additionally, increased fatigue was associated with decreased quality of life. No associations were found among fatigue, sleep or gender. Conclusions Our study demonstrates that physical activity in the home setting is an effective strategy to reduce fatigue among people living with HIV/AIDS. Future work developing and testing interventions to improve home-based physical activity in this population is needed. PMID:27485463

The association of fatigue with depression and insomnia in HIV-seropositive patients: a pilot study.

PubMed

Low, Yinghui; Preud'homme, Xavier; Goforth, Harold W; Omonuwa, Toma; Krystal, Andrew D

2011-12-01

Fatigue is a pervasive symptom associated with HIV, resulting in significant functioning impairment; but little is known about its etiology or treatment. In patients with primary insomnia, data have shown improvement in fatigue following successful treatment of insomnia. However, little is known about the role of insomnia in patients with fatigue in HIV. This manuscript seeks to test the hypothesis that insomnia severity is correlated with increased fatigue in HIV-seropositive patients. Fifty-seven ambulatory HIV-seropositive patients, aged 18-60 years, with a DSM-IV-TR diagnosis of insomnia, were administered the Insomnia Severity Index (ISI), Piper Fatigue Scale (PFS), Hospital Anxiety and Depression scale, and Hamilton Depression Rating Scale (HAM-D). Their most recent CD4 count and time since diagnosis of HIV were recorded. Regression analysis was carried out with PFS as the dependent variable. A higher ISI score correlated with higher PFS score, (R2 = 0.1713, P = 0.0042). Overall depression severity was not significantly correlated with PFS score, except in the most severely depressed subgroup, in which the HADS depression score was the strongest predictor of PFS (R2 = 0.182, P = 0.0009). In participants without depression, ISI accounted for most of the variance in fatigue (R2 = 0.6035, P = 0.0011). Greater insomnia severity is associated with greater fatigue severity in HIV seropositive patients. Depression may contribute to both fatigue and insomnia. In the absence of depression, the treatment of insomnia may emerge as a treatment strategy to help alleviate fatigue. Further studies are needed to confirm these data. Clinical Trials.Gov: The Treatment of Insomnia in Patients with HIV Disease. Registry Number: NCT00465972. URL: http://www.clinicaltrials.gov/ct2/show/NCT00465972?term = HIV+insomnia&rank = 1.

Comparing older and younger Japanese primiparae: fatigue, depression and biomarkers of stress.

PubMed

Mori, Emi; Maehara, Kunie; Iwata, Hiroko; Sakajo, Akiko; Tsuchiya, Miyako; Ozawa, Harumi; Morita, Akiko; Maekawa, Tomoko; Saeki, Akiko

2015-03-01

This cohort study of primiparae was conducted to answer the following questions: Do older (≧ 35 years) and younger (20-29 years) Japanese primiparous mothers differ when comparing biomarkers of stress and measures of fatigue and depression? Are there changes in fatigue, depression and stress biomarkers when comparing older and younger mothers during the postpartum period? The Postnatal Accumulated Fatigue Scale and the Edinburgh Postnatal Depression Scale were administered in a time-series method four times: shortly after birth and monthly afterwards. Assays to measure biomarkers of stress, urinary 17-ketosteroids, urinary 17-hydroxycorticosteroids and salivary chromogranin-A, were collected shortly after delivery and at 1 month postpartum in both groups and a third time in older mothers at the 4th month. Statistical testing showed very little difference in fatigue, depression or stress biomarkers between older and younger mothers shortly after birth or 1 month later. Accumulated fatigue and depression scores of older mothers were highest 1 month after delivery. Additional cohort studies are required to characterize physical/psychological well-being of older Japanese primiparae. © 2015 Wiley Publishing Asia Pty Ltd.

Mental Fatigue and Physical and Cognitive Performance During a 2-Bout Exercise Test.

PubMed

Vrijkotte, Susan; Meeusen, Romain; Vandervaeren, Cloe; Buyse, Luk; Cutsem, Jeroen van; Pattyn, Nathalie; Roelands, Bart

2018-04-01

The 2-bout exercise protocol has been developed to diagnose nonfunctional overreaching and the "overtraining syndrome." It consists of 2 maximal exercise bouts separated by 4 hours. Mental fatigue negatively influences performance, but the effects of its occurrence during the 2-bout exercise protocol have never been investigated. The aim of this study was to examine whether mental fatigue (induced during the rest period) influences physical and cognitive performance during/after the second exercise bout of the 2-bout exercise protocol. Nine healthy, well-trained male cyclists participated in a single-blind, randomized, placebo-controlled crossover study. The intervention consisted of either 1.5-hour rest (control) or performing a computer-based Stroop task to induce mental fatigue. Cognitive (Eriksen Flanker task), physiological (lactate, maximum heart rate, and maximum wattage), and subjective data (mental fatigue-visual analog scale, Profile of Mood States, and rating of perceived exertion) were gathered. Ratings of fatigue, tension, and mental fatigue were affected in the mental fatigue condition (P < .05). Neither physiological nor cognitive differences were found between conditions. Ratings of mental fatigue were already affected after the first maximum exercise test (P < .05). Neither physical nor cognitive performance was affected by mental fatigue, but subjective ratings did reveal significant differences. It is recommended to exclude mentally challenging tasks during the 2-bout exercise protocol rest period to ascertain unaffected subjective test results. This study should be repeated in athletes diagnosed with nonfunctional overreaching/overtraining syndrome.

Development and Characterization of Embedded Sensory Particles Using Multi-Scale 3D Digital Image Correlation

NASA Technical Reports Server (NTRS)

Cornell, Stephen R.; Leser, William P.; Hochhalter, Jacob D.; Newman, John A.; Hartl, Darren J.

2014-01-01

A method for detecting fatigue cracks has been explored at NASA Langley Research Center. Microscopic NiTi shape memory alloy (sensory) particles were embedded in a 7050 aluminum alloy matrix to detect the presence of fatigue cracks. Cracks exhibit an elevated stress field near their tip inducing a martensitic phase transformation in nearby sensory particles. Detectable levels of acoustic energy are emitted upon particle phase transformation such that the existence and location of fatigue cracks can be detected. To test this concept, a fatigue crack was grown in a mode-I single-edge notch fatigue crack growth specimen containing sensory particles. As the crack approached the sensory particles, measurements of particle strain, matrix-particle debonding, and phase transformation behavior of the sensory particles were performed. Full-field deformation measurements were performed using a novel multi-scale optical 3D digital image correlation (DIC) system. This information will be used in a finite element-based study to determine optimal sensory material behavior and density.

Fatigue Life Assessment of 65Si7 Leaf Springs: A Comparative Study

PubMed Central

Arora, Vinkel Kumar; Bhushan, Gian; Aggarwal, M. L.

2014-01-01

The experimental fatigue life prediction of leaf springs is a time consuming process. The engineers working in the field of leaf springs always face a challenge to formulate alternate methods of fatigue life assessment. The work presented in this paper provides alternate methods for fatigue life assessment of leaf springs. A 65Si7 light commercial vehicle leaf spring is chosen for this study. The experimental fatigue life and load rate are determined on a full scale leaf spring testing machine. Four alternate methods of fatigue life assessment have been depicted. Firstly by SAE spring design manual approach the fatigue test stroke is established and by the intersection of maximum and initial stress the fatigue life is predicted. The second method constitutes a graphical method based on modified Goodman's criteria. In the third method codes are written in FORTRAN for fatigue life assessment based on analytical technique. The fourth method consists of computer aided engineering tools. The CAD model of the leaf spring has been prepared in solid works and analyzed using ANSYS. Using CAE tools, ideal type of contact and meshing elements have been proposed. The method which provides fatigue life closer to experimental value and consumes less time is suggested. PMID:27379327

The role of helplessness as mediator between neurological disability, emotional instability, experienced fatigue and depression in patients with multiple sclerosis.

PubMed

van der Werf, S P; Evers, A; Jongen, P J H; Bleijenberg, G

2003-02-01

The aim of this study was to test, in patients with multiple sclerosis (MS), whether the concept of helplessness might improve the understanding of the relationship between disease severity (neurological impairment) and personality characteristics (emotional instability) on one hand, and depressive mood and fatigue severity on the other hand. Data pertain to 89 patients with a definite diagnosis of MS (Expanded Disability Status Scale [EDSS] ratings: 1-8). Helplessness, fatigue severity, depressive mood and emotional instability were rated with validated questionnaires. Model testing revealed that more neurological impairment and more emotional instability were associated with more helplessness, while higher levels of helplessness were associated with more fatigue and depressive mood. The initially observed direct relationship between EDSS and fatigue disappeared. Emotional instability also had a direct significant relationship with depressive mood, and depressive mood had only a small relationship with fatigue severity. The results indicated that helplessness affected both depressive mood and fatigue severity and that fatigue was not merely a symptom of depressive mood. The correlation between neurological impairment and fatigue severity was largely explained by the mediating effect of helplessness. These findings suggest that MS patients troubled by disabling fatigue might benefit from a psychological intervention targeting unfavourable illness cognitions.

Foil system fatigue load environments for commercial hydrofoil operation

NASA Technical Reports Server (NTRS)

Graves, D. L.

1979-01-01

The hydrofoil fatigue loads environment in the open sea is examined. The random nature of wave orbital velocities, periods and heights plus boat heading, speed and control system design are considered in the assessment of structural fatigue requirements. Major nonlinear load events such as hull slamming and foil unwetting are included in the fatigue environment. Full scale rough water load tests, field experience plus analytical loads work on the model 929 Jetfoil commercial hydrofoil are discussed. The problem of developing an overall sea environment for design is defined. State of the art analytical approaches are examined.

The Growth of Multi-Site Fatigue Damage in Fuselage Lap Joints

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.

1999-01-01

Destructive examinations were performed to document the progression of multi-site damage (MSD) in three lap joint panels that were removed from a full scale fuselage test article that was tested to 60,000 full pressurization cycles. Similar fatigue crack growth characteristics were observed for small cracks (50 microns to 10 mm) emanating from counter bore rivets, straight shank rivets, and 100 deg counter sink rivets. Good correlation of the fatigue crack growth data base obtained in this study and FASTRAN Code predictions show that the growth of MSD in the fuselage lap joint structure can be predicted by fracture mechanics based methods.

Effectiveness of aerobic gymnastic exercise on stress, fatigue, and sleep quality during postpartum: A pilot randomized controlled trial.

PubMed

Yang, Chiu-Ling; Chen, Chung-Hey

2018-01-01

Gymnastics is a preferable safe exercise for postnatal women performing regularly. The aim of this pilot randomized controlled trial was to determine whether the aerobic gymnastic exercise improves stress, fatigue, sleep quality and depression in postpartum women. Single-blinded, randomized controlled trial held from December 2014 until September 2015. Postnatal clinic of a medical center in southern Taiwan. 140 eligible postnatal women were systematically assigned, with a random start to experimental (n=70) or a control (n=70) group. Engage in aerobic gymnastic exercise at least three times (15min per section) a week for three months using compact disc in the home. Perceived Stress Scale, Postpartum Fatigue Scale, Postpartum Sleep Quality Scale, and Edinburgh Postnatal Depression Scale. In a two-way ANOVA with repeated measures, the aerobic gymnastic exercise group showed significant decrease in fatigue after practicing exercise 4 weeks and the positive effects extended to the 12-week posttests. Paired t-tests revealed that aerobic gymnastic exercise participants had improved significantly in perceived stress and fatigue after 4 weeks gymnastic exercise; these positive effects extended to the 12-week posttests. In addition, the changes in physical symptoms-related sleep inefficiency after 12 weeks gymnastic exercise were significantly decreased in the experimental group compared with the control group. The findings can be used to encourage postnatal women to perform moderate-intensity gymnastic exercise in their daily life to reduce their stress, fatigue and improve sleep quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multi-mode evaluation of power-maximizing cross-flow turbine controllers

DOE PAGES

Forbush, Dominic; Cavagnaro, Robert J.; Donegan, James; ...

2017-09-21

A general method for predicting and evaluating the performance of three candidate cross-flow turbine power-maximizing controllers is presented in this paper using low-order dynamic simulation, scaled laboratory experiments, and full-scale field testing. For each testing mode and candidate controller, performance metrics quantifying energy capture (ability of a controller to maximize power), variation in torque and rotation rate (related to drive train fatigue), and variation in thrust loads (related to structural fatigue) are quantified for two purposes. First, for metrics that could be evaluated across all testing modes, we considered the accuracy with which simulation or laboratory experiments could predict performancemore » at full scale. Second, we explored the utility of these metrics to contrast candidate controller performance. For these turbines and set of candidate controllers, energy capture was found to only differentiate controller performance in simulation, while the other explored metrics were able to predict performance of the full-scale turbine in the field with various degrees of success. Finally, effects of scale between laboratory and full-scale testing are considered, along with recommendations for future improvements to dynamic simulations and controller evaluation.« less

Multi-mode evaluation of power-maximizing cross-flow turbine controllers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forbush, Dominic; Cavagnaro, Robert J.; Donegan, James

A general method for predicting and evaluating the performance of three candidate cross-flow turbine power-maximizing controllers is presented in this paper using low-order dynamic simulation, scaled laboratory experiments, and full-scale field testing. For each testing mode and candidate controller, performance metrics quantifying energy capture (ability of a controller to maximize power), variation in torque and rotation rate (related to drive train fatigue), and variation in thrust loads (related to structural fatigue) are quantified for two purposes. First, for metrics that could be evaluated across all testing modes, we considered the accuracy with which simulation or laboratory experiments could predict performancemore » at full scale. Second, we explored the utility of these metrics to contrast candidate controller performance. For these turbines and set of candidate controllers, energy capture was found to only differentiate controller performance in simulation, while the other explored metrics were able to predict performance of the full-scale turbine in the field with various degrees of success. Finally, effects of scale between laboratory and full-scale testing are considered, along with recommendations for future improvements to dynamic simulations and controller evaluation.« less

The Piper Fatigue Scale-12 (PFS-12): Psychometric Findings and Item Reduction in a Cohort of Breast Cancer Survivors

PubMed Central

Reeve, Bryce B.; Stover, Angela M.; Alfano, Catherine M.; Smith, Ashley Wilder; Ballard-Barbash, Rachel; Bernstein, Leslie; McTiernan, Anne; Baumgartner, Kathy B.; Piper, Barbara F.

2013-01-01

Purpose Brief, valid measures of fatigue, a prevalent and distressing cancer symptom, are needed for use in research. This study’s primary aim was to create a shortened version of the revised Piper Fatigue Scale (PFS-R) based on data from a diverse cohort of breast cancer survivors. A secondary aim was to determine whether the PFS captured multiple distinct aspects of fatigue (a multidimensional model) or a single overall fatigue factor (a unidimensional model). Methods Breast cancer survivors (n=799; stages in situ through IIIa; ages 29–86 yrs) were recruited through 3 SEER registries (New Mexico, Western Washington, and Los Angeles, CA) as part of the Health, Eating, Activity, and Lifestyle (HEAL) study. Fatigue was measured approximately 3 years post-diagnosis using the 22-item PFS-R that has 4 subscales (Behavior, Affect, Sensory, and Cognition). Confirmatory factor analysis was used to compare unidimensional and multidimensional models. Six criteria were used to make item selections to shorten the PFS-R: scale’s content validity, items’ relationship with fatigue, content redundancy, differential item functioning by race and/or education, scale reliability, and literacy demand. Results Factor analyses supported the original 4-factor structure. There was also evidence from the bi-factor model for a dominant underlying fatigue factor. Six items tested positive for differential item functioning between African-American and Caucasian survivors. Four additional items either showed poor association, local dependence, or content validity concerns. After removing these 10 items, the reliability of the PFS-12 subscales ranged from 0.87–0.89, compared to 0.90–0.94 prior to item removal. Conclusion The newly developed PFS-12 can be used to assess fatigue in African-American and Caucasian breast cancer survivors and reduces response burden without compromising reliability or validity. This is the first study to determine PFS literacy demand and to compare PFS-R responses in African-Americans and Caucasian breast cancer survivors. Further testing in diverse populations is warranted. PMID:22933027

The PedsQL Multidimensional Fatigue Scale in young adults: feasibility, reliability and validity in a University student population.

PubMed

Varni, James W; Limbers, Christine A

2008-02-01

The PedsQL (Pediatric Quality of Life Inventory) is a modular instrument designed to measure health-related quality of life (HRQOL) and disease-specific symptoms in children and adolescents ages 2-18. The PedsQL Multidimensional Fatigue Scale was designed as a generic symptom-specific instrument to measure fatigue in pediatric patients ages 2-18. Since a sizeable number of pediatric patients prefer to remain with their pediatric providers after age 18, the objective of the present study was to determine the feasibility, reliability, and validity of the PedsQL Multidimensional Fatigue Scale in young adults. The 18-item PedsQL Multidimensional Fatigue Scale (General Fatigue, Sleep/Rest Fatigue, and Cognitive Fatigue domains), the PedsQL 4.0 Generic Core Scales Young Adult Version, and the SF-8 Health Survey were completed by 423 university students ages 18-25. The PedsQL Multidimensional Fatigue Scale evidenced minimal missing responses, achieved excellent reliability for the Total Scale Score (alpha = 0.90), distinguished between healthy young adults and young adults with chronic health conditions, was significantly correlated with the relevant PedsQL 4.0 Generic Core Scales and the SF-8 standardized scores, and demonstrated a factor-derived structure largely consistent with the a priori conceptual model. The results demonstrate the measurement properties of the PedsQL Multidimensional Fatigue Scale in a convenience sample of young adult university students. The findings suggest that the PedsQL Multidimensional Fatigue Scale may be utilized in the evaluation of fatigue for a broad age range.

Development of composite carrythrough bulkhead

NASA Technical Reports Server (NTRS)

Ehlen, R. J.; Libeskind, M.

1992-01-01

A structural development program was recently completed in which the weight and fatigue advantages of an all composite major load carrying bulkhead was successfully demonstrated. Fabrication of a full scale article, including static and fatigue testing of the carry-through beam portion verified the producibility, strength and durability of this design, thereby presenting the opportunity for use on aircraft upgrades and new aircraft. A 15% weight saving is achievable and, more importantly, the fatigue problems that normally plague metal bulkheads are virtually eliminated.

Fatigue qualification of high thickness composite rotor components

NASA Astrophysics Data System (ADS)

Raggi, M.; Mariani, U.; Zaffaroni, G.

Fatigue qualification aspects of composite rotor components are presented according with the safe life procedure usually applied by helicopter manufacturers. Test activities are identified at three levels of specimen complexity: coupon, structural element and full scale component. Particular attention is given to high thickness laminates qualification as far as environmental exposure is concerned. A practical approach for an accelerated conditioning procedure is described. The application to a main rotor tension link is presented showing the negligible effect of the moisture absorption on its fatigue strength.

The impact of subjective cognitive fatigue and depression on cognitive function in patients with multiple sclerosis.

PubMed

Golan, Daniel; Doniger, Glen M; Wissemann, Karl; Zarif, Myassar; Bumstead, Barbara; Buhse, Marijean; Fafard, Lori; Lavi, Idit; Wilken, Jeffrey; Gudesblatt, Mark

2018-02-01

The association between subjective cognitive fatigue and objective cognitive dysfunction in patients with multiple sclerosis (PwMS) has been studied, with conflicting results. To explore the impact of fatigue on cognitive function, while controlling for the influence of depression, disability, comorbidities, and psychotropic medications. PwMS completed a computerized cognitive testing battery with age- and education-adjusted cognitive domain scores. Disability (Expanded Disability Status Scale (EDSS)), cognitive fatigue, and depression were concurrently evaluated. In all, 699 PwMS were included. Both cognitive fatigue and depression were significantly and negatively correlated with the same cognitive domains: information processing speed, executive function, attention, motor function, and memory (-0.15 ⩽ r ⩽ -0.14 for cognitive fatigue; -0.24 ⩽ r ⩽ -0.19 for depression). Multivariate analysis revealed significant but small independent correlations only between depression and neuropsychological test results, while cognitive fatigue had no independent correlation with objective cognitive function except for a trend toward impaired motor function in highly fatigued PwMS. Depression and cognitive fatigue accounted for no more than 6% of the variance in objective cognitive domain scores. Cognitive fatigue is not independently related to objective cognitive impairment. Depression may influence cognitive function of PwMS primarily when it is severe. Cognitive impairment in PwMS should not be ascribed to fatigue or mild depression.

Analysis of Global Ultrasonic Sensor Data from a Full Scale Wing Panel Test

NASA Astrophysics Data System (ADS)

Michaels, Jennifer E.; Michaels, Thomas E.; Martin, Ramaldo S.

2009-03-01

A full scale wing panel fatigue test was undertaken in 2007 as a part of the DARPA Structural Integrity Prognosis System (SIPS) program. Both local and global ultrasonic sensors were installed on the wing panel and data were recorded periodically over a period of about seven weeks. The local ultrasonic sensors interrogated a small number of selected fastener holes, and the global ultrasonic sensors were arranged in a spatially distributed array surrounding an area encompassing multiple fastener holes of interest. The global ultrasonic sensor data is the focus of the work reported here. Waveforms were recorded from all pitch-catch sensor pairs as a function of static load while fatiguing was paused. The time windows over which the waveforms were recorded were long enough to include most of the reverberating energy. Partway through the test simulated defects were temporarily introduced by gluing masses onto the surface of the wing panel, and waveforms were recorded immediately before their attachment and after their removal. The overall fatigue test was terminated while cracks originating from the fastener holes were still relatively small and before they reached the surface of the wing panel. Both detection and localization results are shown for the artificial damage, and the overall repeatability and stability of the signals are analyzed. Also shown is an analysis of how the reverberating signals change as a function of applied load. The fastener hole fatigue cracks were not detected by the global transducer array, which is not surprising given the final sizes of the cracks as determined by later destructive analysis. However, signals were stable throughout the entire fatigue test, and effects of load on the received signals were significant, both in the short-time and long-time signal regimes.

Ryan Beach | NREL

Science.gov Websites

team. His primary responsibilities include mechanical component design, test instrumentation and layout design, and data analysis for static and fatigue tests on full-scale wind turbine blades. Education B.S

Measuring fatigue in people living with HIV/AIDS: psychometric characteristics of the HIV-Related Fatigue Scale

PubMed Central

BW, Pence; Barroso, J.; Leserman, J.; Harmon, J.L.; Salahuddin, N.

2008-01-01

In the era of life-prolonging antiretroviral therapy, chronic fatigue is one of the most prevalent and disabling symptoms of people living with HIV/AIDS, yet its measurement remains challenging. No instruments have been developed specifically to describe HIV-related fatigue. We assessed the reliability and construct validity of the HIV-Related Fatigue Scale (HRFS), a 56-item self-report instrument developed through formative qualitative research and designed to measure the intensity and consequences of fatigue as well as the circumstances surrounding fatigue in people living with HIV. The HRFS has three main scales, which measure fatigue intensity, the responsiveness of fatigue to circumstances and fatigue-related impairment of functioning. The functioning scale can be further divided into subscales measuring impairment of activities of daily living, impairment of mental functioning and impairment of social functioning. Each scale demonstrated high internal consistency (Cronbach’s alpha=0.93, 0.91 and 0.97 for the intensity, responsiveness and functioning scales, respectively). The HRFS scales also demonstrated satisfactory convergent validity when compared to other fatigue measures. HIV-Related Fatigue Scales were moderately correlated with quality of nighttime sleep (rho = 0.46, 0.47 and 0.35) but showed only weak correlations with daytime sleepiness (rho = 0.20, 0.33 and 0.18). The scales were also moderately correlated with general mental and physical health as measured by the SF-36 Health Survey (rho ranged from 0.30 to 0.68 across the 8 SF-36 subscales with most >0.40). The HRFS is a promising tool to help facilitate research on the prevalence, etiology and consequences of fatigue in people living with HIV. PMID:18608084

Measuring fatigue in people living with HIV/AIDS: psychometric characteristics of the HIV-related fatigue scale.

PubMed

Pence, B W; Barroso, J; Leserman, J; Harmon, J L; Salahuddin, N

2008-08-01

In the era of life-prolonging antiretroviral therapy, chronic fatigue is one of the most prevalent and disabling symptoms of people living with HIV/AIDS, yet its measurement remains challenging. No instruments have been developed specifically to describe HIV-related fatigue. We assessed the reliability and construct validity of the HIV-Related Fatigue Scale (HRFS), a 56-item self-report instrument developed through formative qualitative research and designed to measure the intensity and consequences of fatigue as well as the circumstances surrounding fatigue in people living with HIV. The HRFS has three main scales, which measure fatigue intensity, the responsiveness of fatigue to circumstances and fatigue-related impairment of functioning. The functioning scale can be further divided into subscales measuring impairment of activities of daily living, impairment of mental functioning and impairment of social functioning. Each scale demonstrated high internal consistency (Cronbach's alpha=0.93, 0.91 and 0.97 for the intensity, responsiveness and functioning scales, respectively). The HRFS scales also demonstrated satisfactory convergent validity when compared to other fatigue measures. HIV-Related Fatigue Scales were moderately correlated with quality of nighttime sleep (rho=0.46, 0.47 and 0.35) but showed only weak correlations with daytime sleepiness (rho=0.20, 0.33 and 0.18). The scales were also moderately correlated with general mental and physical health as measured by the SF-36 Health Survey (rho ranged from 0.30 to 0.68 across the 8 SF-36 subscales with most >0.40). The HRFS is a promising tool to help facilitate research on the prevalence, etiology and consequences of fatigue in people living with HIV.

Using the bedside wellness system during chemotherapy decreases fatigue and emesis in cancer patients.

PubMed

Oyama, H; Kaneda, M; Katsumata, N; Akechi, T; Ohsuga, M

2000-06-01

The bedside wellness system (BSW) is effective for decreasing stress and improving mental well-being and should help relieve the side effects and mental disorders of patients during cancer chemotherapy. The study was a randomized clinical trial. After giving informed consent, patients were randomly assigned to the BSW intervention or control groups. The patients were given the Hospital Anxiety and Depression Scale (HADS) test before the trial to evaluate their emotional baseline. The Cancer Fatigue Scale, which was developed at our institute, and face visual analog scale were used to measure the emotional state and subjective feelings before and after the trial. The degree of emesis was measured using a visual analogue scale after the experience. We set up the system in a room in the outpatient clinic of the National Cancer Center New Hospital Building. The decreases in the fatigue score and emesis score 3-5 days after chemotherapy were statistically significant (both p < 0.05) and carry-over effects were detected. BSW intervention therapy is an effective way to treat fatigue and emesis. This virtual reality system is a new therapeutic method that can be used in palliative medicine.

Creep-Fatigue Damage Investigation and Modeling of Alloy 617 at High Temperatures

NASA Astrophysics Data System (ADS)

Tahir, Fraaz

The Very High Temperature Reactor (VHTR) is one of six conceptual designs proposed for Generation IV nuclear reactors. Alloy 617, a solid solution strengthened Ni-base superalloy, is currently the primary candidate material for the tubing of the Intermediate Heat Exchanger (IHX) in the VHTR design. Steady-state operation of the nuclear power plant at elevated temperatures leads to creep deformation, whereas loading transients including startup and shutdown generate fatigue. A detailed understanding of the creep-fatigue interaction in Alloy 617 is necessary before it can be considered as a material for nuclear construction in ASME Boiler and Pressure Vessel Code. Current design codes for components undergoing creep-fatigue interaction at elevated temperatures require creep-fatigue testing data covering the entire range from fatigue-dominant to creep-dominant loading. Classical strain-controlled tests, which produce stress relaxation during the hold period, show a saturation in cycle life with increasing hold periods due to the rapid stress-relaxation of Alloy 617 at high temperatures. Therefore, applying longer hold time in these tests cannot generate creep-dominated failure. In this study, uniaxial isothermal creep-fatigue tests with non-traditional loading waveforms were designed and performed at 850 and 950°C, with an objective of generating test data in the creep-dominant regime. The new loading waveforms are hybrid strain-controlled and force-controlled testing which avoid stress relaxation during the creep hold. The experimental data showed varying proportions of creep and fatigue damage, and provided evidence for the inadequacy of the widely-used time fraction rule for estimating creep damage under creep-fatigue conditions. Micro-scale damage features in failed test specimens, such as fatigue cracks and creep voids, were quantified using a Scanning Electron Microscope (SEM) to find a correlation between creep and fatigue damage. Quantitative statistical imaging analysis showed that the microstructural damage features (cracks and voids) are correlated with a new mechanical driving force parameter. The results from this image-based damage analysis were used to develop a phenomenological life-prediction methodology called the effective time fraction approach. Finally, the constitutive creep-fatigue response of the material at 950°C was modeled using a unified viscoplastic model coupled with a damage accumulation model. The simulation results were used to validate an energy-based constitutive life-prediction model, as a mechanistic model for potential component and structure level creep-fatigue analysis.

Three-Dimensional BEM and FEM Submodelling in a Cracked FML Full Scale Aeronautic Panel

NASA Astrophysics Data System (ADS)

Citarella, R.; Cricrì, G.

2014-06-01

This paper concerns the numerical characterization of the fatigue strength of a flat stiffened panel, designed as a fiber metal laminate (FML) and made of Aluminum alloy and Fiber Glass FRP. The panel is full scale and was tested (in a previous work) under fatigue biaxial loads, applied by means of a multi-axial fatigue machine: an initial through the thickness notch was created in the panel and the aforementioned biaxial fatigue load applied, causing a crack initiation and propagation in the Aluminum layers. Moreover, (still in a previous work), the fatigue test was simulated by the Dual Boundary Element Method (DBEM) in a bidimensional approach. Now, in order to validate the assumptions made in the aforementioned DBEM approach and concerning the delamination area size and the fiber integrity during crack propagation, three-dimensional BEM and FEM submodelling analyses are realized. Due to the lack of experimental data on the delamination area size (normally increasing as the crack propagates), such area is calculated by iterative three-dimensional BEM or FEM analyses, considering the inter-laminar stresses and a delamination criterion. Such three-dimensional analyses, but in particular the FEM proposed model, can also provide insights into the fiber rupture problem. These DBEM-BEM or DBEM-FEM approaches aims at providing a general purpose evaluation tool for a better understanding of the fatigue resistance of FML panels, providing a deeper insight into the role of fiber stiffness and of delamination extension on the stress intensity factors.

A Study on the Effects of Ball Defects on the Fatigue Life in Hybrid Bearings

NASA Technical Reports Server (NTRS)

Tang, Ching-Yao; Foerster, Chad E.; O'Brien, Michael J.; Hardy, Brian S.; Goyal, Vinay K.; Nelson, Benjamin A.; Robinson, Ernest Y.; Ward, Peter C.; Hilton, Michael R.

2014-01-01

Hybrid ball bearings using silicon nitride ceramic balls with steel rings are increasingly being used in space mechanism applications due to their high wear resistance and long rolling contact fatigue life. However, qualitative and quantitative reports of the effects of ball defects that cause early fatigue failure are rare. We report on our approach to study these effects. Our strategy includes characterization of defects encountered in use, generation of similar defects in a laboratory setting, execution of full-scale bearing tests to obtain lifetimes, post-test characterization, and related finite-element modeling to understand the stress concentration of these defects. We have confirmed that at least one type of defect of appropriate size can significantly reduce fatigue life. Our method can be used to evaluate other defects as they occur or are encountered.

Walking energetics, fatigability, and fatigue in older adults: the study of energy and aging pilot.

PubMed

Richardson, Catherine A; Glynn, Nancy W; Ferrucci, Luigi G; Mackey, Dawn C

2015-04-01

Slow gait speed increases morbidity and mortality in older adults. We examined how preferred gait speed is associated with energetic requirements of walking, fatigability, and fatigue. Older adults (n = 36, 70-89 years) were categorized as slow or fast walkers based on median 400-m gait speed. We measured VO2peak by graded treadmill exercise test and VO2 during 5-minute treadmill walking tests at standard (0.72 m/s) and preferred gait speeds. Fatigability was assessed with the Situational Fatigue Scale and the Borg rating of perceived exertion at the end of walking tests. Fatigue was assessed by questionnaire. Preferred gait speed over 400 m (range: 0.75-1.58 m/s) averaged 1.34 m/s for fast walkers versus 1.05 m/s for slow walkers (p < .001). VO2peak was 26% lower (18.5 vs 25.1ml/kg/min, p = .001) in slow walkers than fast walkers. To walk at 0.72 m/s, slow walkers used a larger percentage of VO2peak (59% vs 42%, p < .001). To walk at preferred gait speed, slow walkers used more energy per unit distance (0.211 vs 0.186ml/kg/m, p = .047). Slow walkers reported higher rating of perceived exertion during walking and greater overall fatigability on the Situational Fatigue Scale, but no differences in fatigue. Slow walking was associated with reduced aerobic capacity, greater energetic cost of walking, and greater fatigability. Interventions to improve aerobic capacity or decrease energetic cost of walking may prevent slowing of gait speed and promote mobility in older adults. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Walking Energetics, Fatigability, and Fatigue in Older Adults: The Study of Energy and Aging Pilot

PubMed Central

Richardson, Catherine A.; Glynn, Nancy W.; Ferrucci, Luigi G.

2015-01-01

Background. Slow gait speed increases morbidity and mortality in older adults. We examined how preferred gait speed is associated with energetic requirements of walking, fatigability, and fatigue. Methods. Older adults (n = 36, 70–89 years) were categorized as slow or fast walkers based on median 400-m gait speed. We measured VO2peak by graded treadmill exercise test and VO2 during 5-minute treadmill walking tests at standard (0.72 m/s) and preferred gait speeds. Fatigability was assessed with the Situational Fatigue Scale and the Borg rating of perceived exertion at the end of walking tests. Fatigue was assessed by questionnaire. Results. Preferred gait speed over 400 m (range: 0.75–1.58 m/s) averaged 1.34 m/s for fast walkers versus 1.05 m/s for slow walkers (p < .001). VO2peak was 26% lower (18.5 vs 25.1ml/kg/min, p = .001) in slow walkers than fast walkers. To walk at 0.72 m/s, slow walkers used a larger percentage of VO2peak (59% vs 42%, p < .001). To walk at preferred gait speed, slow walkers used more energy per unit distance (0.211 vs 0.186ml/kg/m, p = .047). Slow walkers reported higher rating of perceived exertion during walking and greater overall fatigability on the Situational Fatigue Scale, but no differences in fatigue. Conclusions. Slow walking was associated with reduced aerobic capacity, greater energetic cost of walking, and greater fatigability. Interventions to improve aerobic capacity or decrease energetic cost of walking may prevent slowing of gait speed and promote mobility in older adults. PMID:25190069

Measurement of fatigue: Comparison of the reliability and validity of single-item and short measures to a comprehensive measure.

PubMed

Kim, Hee-Ju; Abraham, Ivo

2017-01-01

Evidence is needed on the clinicometric properties of single-item or short measures as alternatives to comprehensive measures. We examined whether two single-item fatigue measures (i.e., Likert scale, numeric rating scale) or a short fatigue measure were comparable to a comprehensive measure in reliability (i.e., internal consistency and test-retest reliability) and validity (i.e., convergent, concurrent, and predictive validity) in Korean young adults. For this quantitative study, we selected the Functional Assessment of Chronic Illness Therapy-Fatigue for the comprehensive measure and the Profile of Mood States-Brief, Fatigue subscale for the short measure; and constructed two single-item measures. A total of 368 students from four nursing colleges in South Korea participated. We used Cronbach's alpha and item-total correlation for internal consistency reliability and intraclass correlation coefficient for test-retest reliability. We assessed Pearson's correlation with a comprehensive measure for convergent validity, with perceived stress level and sleep quality for concurrent validity and the receiver operating characteristic curve for predictive validity. The short measure was comparable to the comprehensive measure in internal consistency reliability (Cronbach's alpha=0.81 vs. 0.88); test-retest reliability (intraclass correlation coefficient=0.66 vs. 0.61); convergent validity (r with comprehensive measure=0.79); concurrent validity (r with perceived stress=0.55, r with sleep quality=0.39) and predictive validity (area under curve=0.88). Single-item measures were not comparable to the comprehensive measure. A short fatigue measure exhibited similar levels of reliability and validity to the comprehensive measure in Korean young adults. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lee Fatigue and Energy Scales: Exploring aspects of validity in a sample of women with HIV using an application of a Rasch model

PubMed Central

Lerdal, Anners; Kottorp, Anders; Gay, Caryl L.; Lee, Kathryn A.

2012-01-01

This study examines the psychometric properties of the Lee Fatigue and Energy Scales (visual analog version) using a Rasch model application. The relationship between fatigue and energy is also described for a convenience sample of 102 women with HIV/AIDS who completed the Lee Fatigue and Energy Scales in the morning and evening. Both scales were assessed for internal scale validity, unidimensionality, and uniform differential item functioning in relation to morning and evening ratings. Analyses confirmed that both the Fatigue and Energy Scales demonstrated evidence of internal scale validity and unidimensionality. Mean fatigue measures were also higher in the evening than in the morning and mean energy measures were higher in the morning than in the evening (both p<0.001), indicating that time of day is an important consideration. Fatigue and energy measures were moderately correlated with each other in the morning but not in the evening. The concepts of energy and fatigue were inversely related, but not polar opposites in this sample. Fatigue and energy may therefore be distinct constructs that should not be used interchangeably, either in measurement or when interpreting outcomes for research or clinical purposes. PMID:22985544

Using Wii Fit to reduce fatigue among African American women with systemic lupus erythematosus: a pilot study.

PubMed

Yuen, H K; Holthaus, K; Kamen, D L; Sword, D O; Breland, H L

2011-10-01

Fatigue and physical deconditioning are common, difficult to treat conditions among patients with systemic lupus erythematosus (SLE). The aim of this pilot study was to evaluate the effectiveness of a home-based exercise program using the Wii Fit system in patients with SLE. Fifteen sedentary African American women with SLE experiencing moderate to severe fatigue participated in a home exercise program using the Wii Fit 3 days a week for 30 minutes each for 10 weeks. A one-group pretest-post test design was used to evaluate the effectiveness of this program. Primary outcome measure was severity of fatigue. Secondary outcome measures were body weight, waist circumference, fatigue-related symptoms of distress, activity level, and physical fitness. At the completion of the 10-week Wii Fit exercise program, participants perceived fatigue severity as measured by the Fatigue Severity Scale to be significantly decreased (p = 0.002), and body weight and waist circumference were significantly reduced (p = 0.01). In addition, anxiety level, as measured by Hospital Anxiety and Depression Scale, and overall intensity of total pain experience, as measured by Short-form of the McGill Pain Questionnaire, were also significantly reduced (p < 0.05). Findings provide preliminary evidence that the Wii Fit motivates this population to exercise, which leads to alleviation of fatigue and reduced body weight, waist circumference, anxiety level, and overall intensity of total pain experience.

Reference values for fatigued versus non-fatigued limb symmetry index measured by a newly designed single-leg hop test battery in healthy subjects: a pilot study.

PubMed

Leister, Iris; Mattiassich, Georg; Kindermann, Harald; Ortmaier, Reinhold; Barthofer, Jürgen; Vasvary, Imre; Katzensteiner, Klaus; Stelzhammer, Christine; Kulnik, Stefan Tino

2018-01-01

There is sparse evidence for return to sport criteria after knee injury. Functional performance deficits, particularly in fatigued muscular condition, should be verified prior to the attempt to return to high-risk pivoting sports. The purpose of this study was to generate reference values for the limb symmetry index (LSI) of healthy subjects in fatigued and non-fatigued muscular condition in a newly designed test battery. Forty-two healthy subjects [22 females, 20 males; mean (SD) age 30.4 (6.6) years] were evaluated using a test battery consisting of an isometric strength test, a series of five single-leg hop tests and an integrated fatigue protocol. Subjective physical activity was assessed with the Tegner Activity Scale (TAS). The cut-off values for healthy subjects were calculated considering the fifth percentile as the minimum reference value for the LSI and single-leg hop distance. The mean (SD) overall LSI was 98.8% (4.6). No significant gender or age specific differences in limb symmetry were observed. The comparison of the non-fatigued LSI with the overall LSI revealed no clinically relevant change due to muscular fatigue. Repeated measures ANOVA revealed a significant within effect on fatigue/non-fatigue condition ( F (1,38)  = 18.000; p  < 0.001, η 2  = 0.321) on absolute single-leg hop distance. Moreover, a significant between effect on the TAS-parameter ( F (1,38)  = 5.928; p  = 0.020, η 2  = 0.135 between: TAS ≤ 5/TAS > 5) and on gender ( F (1,38)  = 23.956; p  < 0.001, η 2  = 0.387) could be detected. The absolute jumping distance in the single-leg hop for distance was significantly reduced due to fatigue. No clinically relevant effect of muscular fatigue was observed on limb symmetry in our study sample. Gender and physical activity are important factors to be considered when interpreting reference values.

Computational Modeling Develops Ultra-Hard Steel

NASA Technical Reports Server (NTRS)

2007-01-01

Glenn Research Center's Mechanical Components Branch developed a spiral bevel or face gear test rig for testing thermal behavior, surface fatigue, strain, vibration, and noise; a full-scale, 500-horsepower helicopter main-rotor transmission testing stand; a gear rig that allows fundamental studies of the dynamic behavior of gear systems and gear noise; and a high-speed helical gear test for analyzing thermal behavior for rotorcraft. The test rig provides accelerated fatigue life testing for standard spur gears at speeds of up to 10,000 rotations per minute. The test rig enables engineers to investigate the effects of materials, heat treat, shot peen, lubricants, and other factors on the gear's performance. QuesTek Innovations LLC, based in Evanston, Illinois, recently developed a carburized, martensitic gear steel with an ultra-hard case using its computational design methodology, but needed to verify surface fatigue, lifecycle performance, and overall reliability. The Battelle Memorial Institute introduced the company to researchers at Glenn's Mechanical Components Branch and facilitated a partnership allowing researchers at the NASA Center to conduct spur gear fatigue testing for the company. Testing revealed that QuesTek's gear steel outperforms the current state-of-the-art alloys used for aviation gears in contact fatigue by almost 300 percent. With the confidence and credibility provided by the NASA testing, QuesTek is commercializing two new steel alloys. Uses for this new class of steel are limitless in areas that demand exceptional strength for high throughput applications.

Application of ultrasonic signature analysis for fatigue detection in complex structures

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.

1974-01-01

Ultrasonic signature analysis shows promise of being a singularly well-suited method for detecting fatigue in structures as complex as aircraft. The method employs instrumentation centered about a Fourier analyzer system, which features analog-to-digital conversion, digital data processing, and digital display of cross-correlation functions and cross-spectra. These features are essential to the analysis of ultrasonic signatures according to the procedure described here. In order to establish the feasibility of the method, the initial experiments were confined to simple plates with simulated and fatigue-induced defects respectively. In the first test the signature proved sensitive to the size of a small hole drilled into the plate. In the second test, performed on a series of fatigue-loaded plates, the signature proved capable of indicating both the initial appearance and subsequent growth of a fatigue crack. In view of these encouraging results it is concluded that the method has reached a sufficiently advanced stage of development to warrant application to small-scale structures or even actual aircraft.

Bidirectional Relationships Between Fatigue and Everyday Experiences in Persons Living With HIV.

PubMed

Cook, Paul F; Hartson, Kimberly R; Schmiege, Sarah J; Jankowski, Catherine; Starr, Whitney; Meek, Paula

2016-06-01

Fatigue symptoms are very common among persons living with HIV (PLWH). Fatigue is related to functional and psychological problems and to treatment nonadherence. Using secondary data from ecological momentary assessment, we examined fatigue as a predictor of PLWH everyday experiences. In bidirectional analyses based on the shape shifters model, we also examined these experiences as predictors of fatigue. Data were examined from 67 PLWH who completed daily surveys on a handheld computer. Brief validated scales were used to assess participants' control beliefs, mood, stress, coping, social support, experience of stigma, and motivation. At the beginning and end of the study, fatigue was measured with two CES-D items that have been used in past HIV symptom research. Multilevel models and logistic regression were used to test reciprocal predictive relationships between variables. Moderate to severe fatigue affected 45% of PLWH in the study. Initial fatigue predicted PLWH subsequent overall level of control beliefs, mood, stress, coping, and social support, all p < .05. These state variables remained relatively constant over time, regardless of participants' initial fatigue. In tests for reciprocal relationships with 33 PLWH, average daily stress, OR = 4.74, and stigma, OR = 4.86, also predicted later fatigue. Fatigue predicted several daily survey variables including stress and social support. Stress and support in turn predicted fatigue at a later time, suggesting a self-perpetuating cycle but also a possible avenue for intervention. Future studies should examine daily variation in fatigue among PLWH and its relation to other everyday experiences and behaviors. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Dietary supplementation with a superoxide dismutase-melon concentrate reduces stress, physical and mental fatigue in healthy people: a randomised, double-blind, placebo-controlled trial.

PubMed

Carillon, Julie; Notin, Claire; Schmitt, Karine; Simoneau, Guy; Lacan, Dominique

2014-06-19

We aimed to investigate effects of superoxide dismutase (SOD)-melon concentrate supplementation on psychological stress, physical and mental fatigue in healthy people. A randomized, double-blind, placebo-controlled trial was performed on 61 people divided in two groups: active supplement (n = 32) and placebo (n = 29) for 12 weeks. Volunteers were given one small hard capsule per day. One capsule contained 10 mg of SOD-melon concentrate (140 U of SOD) and starch for the active supplement and starch only for the placebo. Stress and fatigue were evaluated using four psychometric scales: PSS-14; SF-36; Stroop tests and Prevost scale. The supplementation with SOD-melon concentrate significantly decreased perceived stress, compared to placebo. Moreover, quality of life was improved and physical and mental fatigue were reduced with SOD-melon concentrate supplementation. SOD-melon concentrate supplementation appears to be an effective and natural way to reduce stress and fatigue. trial approved by the ethical committee of Poitiers (France), and the ClinicalTrials.gov Identifier is NCT01767922.

An investigation of depression and fatigue post West Nile virus infection.

PubMed

Berg, Patti J; Smallfield, Stacy; Svien, Lana

2010-04-01

The purpose of this study was to examine depression and fatigue in individuals with a seropositive confirmed history of West Nile virus (WNV) infection. The South Dakota State Epidemiologist sent 218 letters inviting residents with a diagnosis of WNV to participate in the study. Forty-five subjects were tested. An occupational therapist and a physical therapist met with each participant to assess performance parameters, including depression and fatigue levels. Subjects (n=42) completed the Revised Center for Epidemiologic Studies Depression Scale (CES-D) during the assessment. The Modified Fatigue Impact Scale (MFIS) was sent to participants as a follow-up questionnaire, and 29 were returned. Subjects were placed within one of three diagnosis groups: West Nile Fever (WNF), West Nile Neuroinvasive Disease (WNND) and WNV without fever or neuroinvasive disease (clinical/unspecified). Frequency of those reporting low risk of depression was similar between diagnosis groups (each approximating 75 percent). Depression severity differences were noted, with subjects diagnosed with WNND more likely to report "severe" risk for depression. Low correlations between depression and overall fatigue, depression and cognitive fatigue, and depression and psychosocial fatigue indicators were found. There was little if any correlation between depression and physical fatigue indicators. Mean CES-D scores for subjects between 13 to 18 months post infection fell within the mild-moderate risk for depression category. Identifying depression risk is useful for patient referral purposes and may help minimize symptoms of depression correlated with fatigue, especially following hospitalization for WNV infection.

Clinical study on constitutional herbal tea for treating chronic fatigue.

PubMed

Park, Soo-Jung; Bae, Young-Chun; Choi, Na-Rae; Ryu, Seung-Yeob; Kwon, Young-Mi; Joo, Jong-Cheon

2014-12-01

This study was designed to evaluate the efficacy and the safety of constitutional herbal tea for treating chronic fatigue with no diagnosed cause, which is called Mibyeong in Korea. Males and females with ages between 40 and 59 years who had complained of fatigue for 1 month consistently or for 6 months intermittently without a definite cause were recruited. At the same time, a Chalder fatigue scale (CFS) score of 19 was essential for participation in this study. Sixty five subjects completed the entire process, including blood tests and tests with medical devices. Five assessments of health status were accomplished over 8 weeks by using the CFS and the visual analogue scale (VAS). To ensure that the constitutional herbal tea was being safely used, we conducted and analyzed renal function and liver function tests. For the diagnosis of the Sasang constitution, the Sasang Constitutional Analysis Tool (SCAT) was used, and a specialist in Sasang constitutional medicine made the final diagnosis based on the SCAT result. Constitutional herbal tea was served four weeks after the first visit. The subjects took the constitutional herbal tea twice a day for one month. The results are as follows: The CFS and the VAS scores were significantly improved for the subjects in the constitutional herbal tea. No abnormalities were found on the blood tests to evaluate safety after taking the constitutional herbal tea. The improvements in the CFS and the VAS scores due to the constitutional herbal tea had no significant differences according to the Sasang constitution. Constitutional herbal tea may be used to reduce fatigue and improve health and has no adverse effect on either the kidney or the liver.

Clinical Study on Constitutional Herbal Tea for Treating Chronic Fatigue

PubMed Central

Park, Soo-Jung; Bae, Young-Chun; Choi, Na-Rae; Ryu, Seung-Yeob; Kwon, Young-Mi; Joo, Jong-Cheon

2014-01-01

Objectives: This study was designed to evaluate the efficacy and the safety of constitutional herbal tea for treating chronic fatigue with no diagnosed cause, which is called Mibyeong in Korea. Methods: Males and females with ages between 40 and 59 years who had complained of fatigue for 1 month consistently or for 6 months intermittently without a definite cause were recruited. At the same time, a Chalder fatigue scale (CFS) score of 19 was essential for participation in this study. Sixty five subjects completed the entire process, including blood tests and tests with medical devices. Five assessments of health status were accomplished over 8 weeks by using the CFS and the visual analogue scale (VAS). To ensure that the constitutional herbal tea was being safely used, we conducted and analyzed renal function and liver function tests. For the diagnosis of the Sasang constitution, the Sasang Constitutional Analysis Tool (SCAT) was used, and a specialist in Sasang constitutional medicine made the final diagnosis based on the SCAT result. Constitutional herbal tea was served four weeks after the first visit. The subjects took the constitutional herbal tea twice a day for one month. Results: The results are as follows: The CFS and the VAS scores were significantly improved for the subjects in the constitutional herbal tea. No abnormalities were found on the blood tests to evaluate safety after taking the constitutional herbal tea. The improvements in the CFS and the VAS scores due to the constitutional herbal tea had no significant differences according to the Sasang constitution. Conclusion: Constitutional herbal tea may be used to reduce fatigue and improve health and has no adverse effect on either the kidney or the liver. PMID:25780720

Flight service evaluation of composite helicopter components

NASA Technical Reports Server (NTRS)

Mardoian, George H.; Ezzo, Maureen B.

1990-01-01

An assessment is presented of ten composite tail rotor spars and four horizontal stabilizers exposed to the effects of in-flight commercial service for up to nine years to establish realistic environmental factors for use in future designs. This evaluation is supported by test results of helicopter components and panels which have been exposed to outdoor environmental effects since 1979. Full scale static and fatigue tests were conducted on graphite/epoxy and Kevlar/epoxy composite components removed from Sikorsky Model S-76 helicopters in commercial operations off the Gulf Coast of Louisiana. Small scale static and fatigue tests were conducted on coupons obtained from panels exposed to outdoor conditions in Stratford, CT and West Palm Beach, Florida. The panel materials and ply configurations were representative of the S-76 components. The results are discussed of moisture analyses and strength tests on both the S-76 components and composite panels after up to nine years of outdoor exposure. Full scale tests performed on the helicopter components did not disclose any significant reductions from the baseline strengths. The results increased confidence in the long term durability of advanced composite materials in helicopter structural applications.

PedsQL™ Multidimensional Fatigue Scale in sickle cell disease: feasibility, reliability, and validity.

PubMed

Panepinto, Julie A; Torres, Sylvia; Bendo, Cristiane B; McCavit, Timothy L; Dinu, Bogdan; Sherman-Bien, Sandra; Bemrich-Stolz, Christy; Varni, James W

2014-01-01

Sickle cell disease (SCD) is an inherited blood disorder characterized by a chronic hemolytic anemia that can contribute to fatigue and global cognitive impairment in patients. The study objective was to report on the feasibility, reliability, and validity of the PedsQL™ Multidimensional Fatigue Scale in SCD for pediatric patient self-report ages 5-18 years and parent proxy-report for ages 2-18 years. This was a cross-sectional multi-site study whereby 240 pediatric patients with SCD and 303 parents completed the 18-item PedsQL™ Multidimensional Fatigue Scale. Participants also completed the PedsQL™ 4.0 Generic Core Scales. The PedsQL™ Multidimensional Fatigue Scale evidenced excellent feasibility, excellent reliability for the Total Scale Scores (patient self-report α = 0.90; parent proxy-report α = 0.95), and acceptable reliability for the three individual scales (patient self-report α = 0.77-0.84; parent proxy-report α = 0.90-0.97). Intercorrelations of the PedsQL™ Multidimensional Fatigue Scale with the PedsQL™ Generic Core Scales were predominantly in the large (≥0.50) range, supporting construct validity. PedsQL™ Multidimensional Fatigue Scale Scores were significantly worse with large effects sizes (≥0.80) for patients with SCD than for a comparison sample of healthy children, supporting known-groups discriminant validity. Confirmatory factor analysis demonstrated an acceptable to excellent model fit in SCD. The PedsQL™ Multidimensional Fatigue Scale demonstrated acceptable to excellent measurement properties in SCD. The results demonstrate the relative severity of fatigue symptoms in pediatric patients with SCD, indicating the potential clinical utility of multidimensional assessment of fatigue in patients with SCD in clinical research and practice. © 2013 Wiley Periodicals, Inc.

PedsQL™ Multidimensional Fatigue Scale in Sickle Cell Disease: Feasibility, Reliability and Validity

PubMed Central

Panepinto, Julie A.; Torres, Sylvia; Bendo, Cristiane B.; McCavit, Timothy L.; Dinu, Bogdan; Sherman-Bien, Sandra; Bemrich-Stolz, Christy; Varni, James W.

2013-01-01

Background Sickle cell disease (SCD) is an inherited blood disorder characterized by a chronic hemolytic anemia that can contribute to fatigue and global cognitive impairment in patients. The study objective was to report on the feasibility, reliability, and validity of the PedsQL™ Multidimensional Fatigue Scale in SCD for pediatric patient self-report ages 5–18 years and parent proxy-report for ages 2–18 years. Procedure This was a cross-sectional multi-site study whereby 240 pediatric patients with SCD and 303 parents completed the 18-item PedsQL™ Multidimensional Fatigue Scale. Participants also completed the PedsQL™ 4.0 Generic Core Scales. Results The PedsQL™ Multidimensional Fatigue Scale evidenced excellent feasibility, excellent reliability for the Total Scale Scores (patient self-report α = 0.90; parent proxy-report α = 0.95), and acceptable reliability for the three individual scales (patient self-report α = 0.77–0.84; parent proxy-report α = 0.90–0.97). Intercorrelations of the PedsQL™ Multidimensional Fatigue Scale with the PedsQL™ Generic Core Scales were predominantly in the large (≥ 0.50) range, supporting construct validity. PedsQL™ Multidimensional Fatigue Scale Scores were significantly worse with large effects sizes (≥0.80) for patients with SCD than for a comparison sample of healthy children, supporting known-groups discriminant validity. Confirmatory factor analysis demonstrated an acceptable to excellent model fit in SCD. Conclusions The PedsQL™ Multidimensional Fatigue Scale demonstrated acceptable to excellent measurement properties in SCD. The results demonstrate the relative severity of fatigue symptoms in pediatric patients with SCD, indicating the potential clinical utility of multidimensional assessment of fatigue in patients with SCD in clinical research and practice. PMID:24038960

Restless leg syndrome, sleep quality and fatigue in multiple sclerosis patients.

PubMed

Moreira, N C V; Damasceno, R S; Medeiros, C A M; Bruin, P F C de; Teixeira, C A C; Horta, W G; Bruin, V M S de

2008-10-01

We have tested the hypothesis that restless leg syndrome (RLS) is related to quality of sleep, fatigue and clinical disability in multiple sclerosis (MS). The diagnosis of RLS used the four minimum criteria defined by the International Restless Legs Syndrome Study Group. Fatigue was assessed by the Fatigue Severity Scale (FSS >27), quality of sleep by the Pittsburgh Sleep Quality Index (PSQI >6), excessive daytime sleepiness by the Epworth Sleepiness Scale (ESS >10) and clinical disability by the Expanded Disability Status Scale (EDSS). Forty-four patients (32 women) aged 14 to 64 years (43 +/- 14) with disease from 0.4 to 23 years (6.7 +/- 5.9) were evaluated. Thirty-five were classified as relapsing-remitting, 5 as primary progressive and 4 as secondary progressive. EDSS varied from 0 to 8.0 (3.6 +/- 2.0). RLS was detected in 12 cases (27%). Patients with RLS presented greater disability (P = 0.01), poorer sleep (P = 0.02) and greater levels of fatigue (P = 0.03). Impaired sleep was present in 23 (52%) and excessive daytime sleepiness in 3 cases (6.8%). Fatigue was present in 32 subjects (73%) and was associated with clinical disability (P = 0.000) and sleep quality (P = 0.002). Age, gender, disease duration, MS pattern, excessive daytime sleepiness and the presence of upper motor neuron signs were not associated with the presence of RLS. Fatigue was best explained by clinical disability and poor sleep quality. Awareness of RLS among health care professionals may contribute to improvement in MS management.

Flight service evaluation of composite helicopter components

NASA Technical Reports Server (NTRS)

Mardoian, G. H.; Ezzo, M. B.

1986-01-01

This report presents an assessment of composite helicopter tail rotor spars and horizontal stabilizers, exposed to the effects of the environment, after up to five and a half years of commercial service. This evaluation is supported by test results of helicopter components and panels which have been exposed to outdoor environmental effects since September 1979. Full scale static and fatigue tests have been conducted on graphite/epoxy and Kevlar/epoxy composite components obtained from Sikorsky Model S-76 helicopters in commercial operations in the Gulf Coast region of Louisiana. Small scale static and fatigue tests are being conducted on coupons obtained from panels under exposure to outdoor conditions in Stratford, Connecticut and West Palm, Florida. The panel layups are representative of the S-76 components. Additionally, this report discusses the results of moisture absorption evaluations and strength tests on the S-76 components and composite panels with up to five years of outdoor exposure.

Assessment of fatigue using the Identity-Consequence Fatigue Scale in patients with lung cancer.

PubMed

Nogueira, Ingrid Correia; Araújo, Amanda Souza; Morano, Maria Tereza; Cavalcante, Antonio George; Bruin, Pedro Felipe de; Paddison, Johana Susan; Silva, Guilherme Pinheiro da; Pereira, Eanes Delgado

2017-01-01

To evaluate the properties of the Identity-Consequence Fatigue Scale (ICFS) in patients with lung cancer (LC), assessing the intensity of fatigue and associated factors. This was a cross-sectional study involving LC patients, treated at a teaching hospital in Brazil, who completed the ICFS. Patients with chronic heart disease (CHD) and healthy controls, matched for age and gender, also completed the scale. Initially, a Brazilian Portuguese-language version of the ICFS was administered to 50 LC patients by two independent interviewers; to test for reproducibility, it was readministered to those same patients. At baseline, the LC patients were submitted to spirometry and the six-minute walk test, as well as completing the Epworth Sleepiness Scale (ESS), Hospital Anxiety and Depression Scale (HADS), Medical Outcomes Study 36-item Short-Form Health Survey (SF-36), and Fatigue Severity Scale (FSS). Inflammatory status was assessed by blood C-reactive protein (CRP) levels. To validate the ICFS, we assessed the correlations of its scores with those variables. The sample comprised 50 patients in each group (LC, CHD, and control). In the LC group, the intraclass correlation coefficients for intra-rater and inter-rater reliability regarding ICFS summary variables ranged from 0.94 to 0.76 and from 0.94 to 0.79, respectively. The ICFS presented excellent internal consistency, and Bland-Altman plots showed good test-retest reliability. The ICFS correlated significantly with FSS, HADS, and SF-36 scores, as well as with CRP levels. Mean ICFS scores in the LC group differed significantly from those in the CHD and control groups. The ICFS is a valid, reliable instrument for evaluating LC patients, in whom depression, quality of life, and CRP levels seem to be significantly associated with fatigue. Avaliar as propriedades da Escala de Identificação e Consequências da Fadiga (EICF) em pacientes com câncer de pulmão (CP), analisando a intensidade da fadiga e fatores associados. Estudo transversal com pacientes com CP, atendidos em um hospital-escola no Brasil, que preencheram a EICF. Pacientes com doenças cardíacas crônicas (DCC) e controles saudáveis, pareados por idade e sexo, também preencheram a escala. Inicialmente, uma versão brasileira da escala foi aplicada a 50 pacientes com CP por dois entrevistadores independentes; para testar a reprodutibilidade, ela foi reaplicada aos mesmos pacientes. No momento basal, os pacientes com CP realizaram espirometria e teste de caminhada de seis minutos, bem como preencheram a Epworth Sleepiness Scale (ESS), Hospital Anxiety and Depression Scale (HADS), Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) e Fatigue Severity Scale (FSS). O estado inflamatório foi avaliado pelos níveis de proteína C reativa (PCR) no sangue. Para validar a EICF, avaliamos as correlações entre as pontuações na mesma e essas variáveis. A amostra foi composta por 50 pacientes em cada grupo (CP, DCC e controle). No grupo CP, os coeficientes de correlação intraclasse para confiabilidade intra e interobservador para as variáveis resumidas da EICF variaram de 0,94 a 0,76 e de 0,94 a 0,79, respectivamente. A EICF apresentou excelente consistência interna, e as disposições gráficas de Bland-Altman demonstraram boa confiabilidade teste-reteste. A EICF apresentou correlações significativas com as pontuações na FSS, HADS e SF-36, bem como com os níveis de PCR. As médias das pontuações na EICF do grupo CP diferiram significativamente das dos grupos DCC e controle. A EICF é um instrumento válido e confiável para a avaliação de pacientes com CP, nos quais depressão, qualidade de vida e níveis de PCR parecem estar significativamente associados à fadiga.

Development of a patient reported outcome scale for fatigue in multiple sclerosis: The Neurological Fatigue Index (NFI-MS)

PubMed Central

2010-01-01

Background Fatigue is a common and debilitating symptom in multiple sclerosis (MS). Best-practice guidelines suggest that health services should repeatedly assess fatigue in persons with MS. Several fatigue scales are available but concern has been expressed about their validity. The objective of this study was to examine the reliability and validity of a new scale for MS fatigue, the Neurological Fatigue Index (NFI-MS). Methods Qualitative analysis of 40 MS patient interviews had previously contributed to a coherent definition of fatigue, and a potential 52 item set representing the salient themes. A draft questionnaire was mailed out to 1223 people with MS, and the resulting data subjected to both factor and Rasch analysis. Results Data from 635 (51.9% response) respondents were split randomly into an 'evaluation' and 'validation' sample. Exploratory factor analysis identified four potential subscales: 'physical', 'cognitive', 'relief by diurnal sleep or rest' and 'abnormal nocturnal sleep and sleepiness'. Rasch analysis led to further item reduction and the generation of a Summary scale comprising items from the Physical and Cognitive subscales. The scales were shown to fit Rasch model expectations, across both the evaluation and validation samples. Conclusion A simple 10-item Summary scale, together with scales measuring the physical and cognitive components of fatigue, were validated for MS fatigue. PMID:20152031

Evaluation of Delamination Onset and Growth Characterization Methods under Mode I Fatigue Loading

NASA Technical Reports Server (NTRS)

Murri, Gretchen B.

2013-01-01

Double-cantilevered beam specimens of IM7/8552 graphite/epoxy from two different manufacturers were tested in static and fatigue to compare the material characterization data and to evaluate a proposed ASTM standard for generating Paris Law equations for delamination growth. Static results were used to generate compliance calibration constants for reducing the fatigue data, and a delamination resistance curve, GIR, for each material. Specimens were tested in fatigue at different initial cyclic GImax levels to determine a delamination onset curve and the delamination growth rate. The delamination onset curve equations were similar for the two sources. Delamination growth rate was calculated by plotting da/dN versus GImax on a log-log scale and fitting a Paris Law. Two different data reduction methods were used to calculate da/dN. To determine the effects of fiber-bridging, growth results were normalized by the delamination resistance curves. Paris Law exponents decreased by 31% to 37% after normalizing the data. Visual data records from the fatigue tests were used to calculate individual compliance constants from the fatigue data. The resulting da/dN versus GImax plots showed improved repeatability for each source, compared to using averaged static data. The Paris Law expressions for the two sources showed the closest agreement using the individually fit compliance data.

Fatigue and neuromuscular diseases.

PubMed

Féasson, L; Camdessanché, J-P; El Mandhi, L; Calmels, P; Millet, G-Y

2006-07-01

To identify the role of fatigue, its evaluation and its causes in the pathophysiology context of acquired or hereditary neuromuscular diseases of the spinal anterior horn cell, peripheral nerve, neuromuscular junction and muscle. A literature review has been done on Medline with the following keywords: neuromuscular disease, peripheral neuropathy, myopathy, fatigue assessment, exercise intolerance, force assessment, fatigue scale and questionnaire, then with the terms: Fatigue Severity Scale, Chalder Fatigue Scale, Fatigue Questionnaire, Piper Fatigue Scale, electromyography and the combination of the word Fatigue with the following terms: Amyotrophic Lateral Sclerosis (ALS), Post-Polio Syndrome (PPS), Guillain-Barre Syndrome, Immune Neuropathy, Charcot-Marie-Tooth Disease, Myasthenia Gravis (MG), Metabolic Myopathy, Mitochondrial Myopathy, Muscular Dystrophy, Facioscapulohumeral Dystrophy, Myotonic Dystrophy. Fatigue is a symptom very frequently reported by patients. Fatigue is mainly evaluated by strength loss after an exercise, by change in electromyographic activity during a given exercise and by questionnaires that takes into account the subjective (psychological) part of fatigue. Due to the large diversity of motor disorders, there are multiple clinical expressions of fatigue that differ in their presentation, consequences and therapeutic approach. This review shows that fatigue has to be taken into account in patients with neuromuscular diseases. In this context, pathophysiology of fatigue often implies the motor component but the disease evolution and the physical obligates of daily life also induce an important psychological component.

Impact of a 10-Week Individualized Exercise Program on Physical Function and Fatigue of People with Multiple Sclerosis

PubMed Central

Elgelid, Staffan; Bolger, Shannon; Parsons, Caroline; Quashnoc, Rachel; Raymor, Johanna

2011-01-01

Research has found that people with multiple sclerosis (MS) who engage in exercise programs experience improvements in physical and psychological health, resulting in enhanced quality of life. These studies have involved structured exercise protocols, but few have examined the effects of an individualized exercise program allowing for peer socialization. The purpose of this study was to investigate the effects of a 10-week individualized exercise program offering opportunities to socialize with peers on fatigue and physical functioning in people with MS. Thirteen individuals with a physician diagnosis of MS were enrolled in a 10-week exercise program at Nazareth College in Rochester, New York. Eleven participants (9 female, 2 male; mean ± SD age, 55.0 ± 7.06 years) completed the study. The following qualitative and quantitative measures were used for evaluation before and after the exercise program: Multiple Sclerosis Quality of Life–54 (MSQOL-54), Activities-specific Balance Confidence (ABC) scale, Modified Fatigue Impact Scale (MFIS), Timed Up and Go (TUG) test, Timed 10-Meter Walk (T10MW) test, functional reach test, and single-leg stance (SLS) test. Statistically significant differences were found for the TUG (P = .005), T10MW (P = .014), and MFIS physical functioning subscore (P = .039). The results showed significant increases in gait speed and mobility as well as decreased impact of fatigue on physical functioning after the 10-week exercise program. PMID:24453715

Applications of infrared thermography for nondestructive testing of fatigue cracks in steel bridges

NASA Astrophysics Data System (ADS)

Sakagami, Takahide; Izumi, Yui; Kobayashi, Yoshihiro; Mizokami, Yoshiaki; Kawabata, Sunao

2014-05-01

In recent years, fatigue crack propagations in aged steel bridge which may lead to catastrophic structural failures have become a serious problem. For large-scale steel structures such as orthotropic steel decks in highway bridges, nondestructive inspection of deteriorations and fatigue damages are indispensable for securing their safety and for estimating their remaining strength. As conventional NDT techniques for steel bridges, visual testing, magnetic particle testing and ultrasonic testing have been commonly employed. However, these techniques are time- and labor- consuming techniques, because special equipment is required for inspection, such as scaffolding or a truck mount aerial work platform. In this paper, a new thermography NDT technique, which is based on temperature gap appeared on the surface of structural members due to thermal insulation effect of the crack, is developed for detection of fatigue cracks. The practicability of the developed technique is demonstrated by the field experiments for highway steel bridges in service. Detectable crack size and factors such as measurement time, season or spatial resolution which influence crack detectability are investigated.

Effect of Fordyce Happiness Model on depression, stress, anxiety, and fatigue in patients with multiple sclerosis.

PubMed

Khayeri, Fereydoon; Rabiei, Leili; Shamsalinia, Abbas; Masoudi, Reza

2016-11-01

This study was conducted to investigate the effect of Fordyce Happiness Model (FHM) on depression, stress, anxiety, and fatigue in MS patients. In this clinical trial, 140 MS patients assigned to experimental and control groups. Depression, anxiety, stress, and fatigue were measured by Depression Anxiety Stress Scale-21 and Piper Standard Scale before and immediately and three months after the implementation of FHM. The data were analyzed by SPSS 18. Independent t-test indicated that total scores of stress, depression, and fatigue of the two groups were not significantly different before the intervention but were significantly different after the intervention (P˂0.05). Moreover, anxiety scores of the two were not significantly different after the intervention (P˃0.05). FHM can assist MS patients to manage their disease and associated problems in life. Besides that, since FHM is efficient and costless, it can be incorporated into the health interventions for MS patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fatigue Experiences Among OCD Outpatients.

PubMed

Pasquini, Massimo; Piacentino, Daria; Berardelli, Isabella; Roselli, Valentina; Maraone, Annalisa; Tarsitani, Lorenzo; Biondi, Massimo

2015-12-01

Patients with OCD are impaired in multiple domains of functioning and quality of life. While associated psychopathology complaints and neuropsychological deficits were reported, the subjective experience of general fatigue and mental fatigue was scarcely investigated. In this single-center case-control study we compared 50 non-depressed OCD outpatients consecutively recruited and 50 panic disorder (PD) outpatients, to determine whether they experienced fatigue differently. Assessment consisted of structured clinical interview for DSM-IV criteria by using the SCID-I and the SCID-II. Symptom severity was assessed using the Yale-Brown Obsessive-Compulsive Scale, the Hamilton Anxiety Rating Scale, the Hamilton Depression Rating Scale, the Clinical Global Impressions Scale, severity and the Global Assessment of Functioning Scale. Fatigue was assessed by using the Multidimensional Fatigue Inventory (MFI). Regarding MFI physical fatigue, an OR of 0.196 (95 % CI 0.080-0.478) was found, suggesting that its presence is associated with lower odds of OCD compared to PD. The same can be said for MFI mental fatigue, as an OR of 0.138 (95 % CI 0.049-0.326) was found, suggesting that its presence is associated with lower odds of OCD. Notably, OCD patients with OCDP co-morbidity reported higher scores of mental fatigue. In this study fatigue, including mental fatigue, seems not to be a prominent experience among adult non-depressed OCD patients.

Visual analogue scales for interstitial lung disease: a prospective validation study.

PubMed

Yates, Helen; Adamali, Huzaifa I; Maskell, Nick; Barratt, Shaney; Sharp, Charles

2018-05-16

Visual analogue scales (VAS) are simple symptom assessment tools which have not been validated in interstitial lung disease (ILD). Simple measures of ILD disease burden would be valuable for non-specialist clinicians monitoring disease away from ILD specialist centres. To validate VAS to assess change in dyspnoea, cough and fatigue in ILD, and to define the minimal clinically important difference (MCID) for change in these. 64 patients with ILD completed VAS for dyspnoea, cough and fatigue. Baseline King's Brief ILD questionnaire (K-BILD) scores, lung function and 6-minute walk test results were collected. Tests were repeated 3-6 months later, in addition to a 7-point Likert scale. The MCID was estimated using median change in VAS in patients who reported "small but just worthwhile change" in symptoms at follow-up. Methods were repeated in a validation cohort of 31 ILD patients to confirm findings. VAS scores were significantly higher for patients who reported a "small but just worthwhile change" in symptoms versus "no change" or "not worthwhile change" (p < 0.01). The MCID for VAS Dyspnoea was estimated as 22.0mm and 14.5mm for VAS Fatigue. These results were reproducible in the validation cohort. Results were not significant for VAS Cough. Change in VAS Dyspnoea correlated with change in K-BILD (r=-0.51, p < 0.01), forced vital capacity (r=-0.32, p = 0.01) and 6-minute walking distance (r=-0.37, p = 0.01). The VAS is valid for assessing change in dyspnoea and fatigue in ILD. The MCID is estimated as 22.0mm for dyspnoea and 14.5mm for fatigue. This could be used to monitor disease in settings away from ILD specialist review.

Fatigue reduces the complexity of knee extensor torque fluctuations during maximal and submaximal intermittent isometric contractions in man

PubMed Central

Pethick, Jamie; Winter, Samantha L; Burnley, Mark

2015-01-01

Neuromuscular fatigue increases the amplitude of fluctuations in torque output during isometric contractions, but the effect of fatigue on the temporal structure, or complexity, of these fluctuations is not known. We hypothesised that fatigue would result in a loss of temporal complexity and a change in fractal scaling of the torque signal during isometric knee extensor exercise. Eleven healthy participants performed a maximal test (5 min of intermittent maximal voluntary contractions, MVCs), and a submaximal test (contractions at a target of 40% MVC performed until task failure), each with a 60% duty factor (6 s contraction, 4 s rest). Torque and surface EMG signals were sampled continuously. Complexity and fractal scaling of torque were quantified by calculating approximate entropy (ApEn), sample entropy (SampEn) and the detrended fluctuation analysis (DFA) scaling exponent α. Fresh submaximal contractions were more complex than maximal contractions (mean ± SEM, submaximal vs. maximal: ApEn 0.65 ± 0.09 vs. 0.15 ± 0.02; SampEn 0.62 ± 0.09 vs. 0.14 ± 0.02; DFA α 1.35 ± 0.04 vs. 1.55 ± 0.03; all P < 0.005). Fatigue reduced the complexity of submaximal contractions (ApEn to 0.24 ± 0.05; SampEn to 0.22 ± 0.04; DFA α to 1.55 ± 0.03; all P < 0.005) and maximal contractions (ApEn to 0.10 ± 0.02; SampEn to 0.10 ± 0.02; DFA α to 1.63 ± 0.02; all P < 0.01). This loss of complexity and shift towards Brownian-like noise suggests that as well as reducing the capacity to produce torque, fatigue reduces the neuromuscular system's adaptability to external perturbations. PMID:25664928

Associations among musculoskeletal impairments, depression, body image and fatigue in breast cancer survivors within the first year after treatment.

PubMed

Cantarero-Villanueva, I; Fernández-Lao, C; Fernández-DE-Las-Peñas, C; Díaz-Rodríguez, L; Sanchez-Cantalejo, E; Arroyo-Morales, M

2011-09-01

The aim of the current study was to investigate the relationship between pressure pain thresholds, shoulder movement, mood state, pain perception, muscle endurance, quality of life and fatigue in breast cancer survivors (BCS). Fifty-nine BCS reporting fatigue were examined at 6 months post-treatment. Women completed the Piper Fatigue Scale, the Breast Cancer-Specific Quality of Life Questionnaire, the Profile of Mood State, and neck-shoulder visual analogue scale. Additionally, shoulder flexion range of motion, the McQuade test (trunk flexor endurance) and pressure pain thresholds over the C5-C6 joint, the deltoid muscle, the second metacarpal and tibialis anterior muscle were assessed. Fatigue was greater in those patients with higher depression (r= 0.45, P < 0.05), higher shoulder pain (r= 0.39, P < 0.05), higher neck pain (r= 0.46, P < 0.01), lower body image (r=-0.34, P < 0.05) and reduced shoulder movement (r=-0.32, P < 0.05). Regression analyses demonstrated that depression, cervical pain intensity, body image and shoulder mobility were associated with fatigue (r= 0.55, P < 0.001). A psychological state characterised with higher depression and reduced body image and a physical impairment with higher cervical pain intensity and reduced shoulder mobility confirm multidimensional character of fatigue in BCS. © 2011 Blackwell Publishing Ltd.

From monoscale to multiscale modeling of fatigue crack growth: Stress and energy density factor

NASA Astrophysics Data System (ADS)

Sih, G. C.

2014-01-01

The formalism of the earlier fatigue crack growth models is retained to account for multiscaling of the fatigue process that involves the creation of macrocracks from the accumulation of micro damage. The effects of at least two scales, say micro to macro, must be accounted for. The same data can thus be reinterpreted by the invariancy of the transitional stress intensity factors such that the microcracking and macrocracking data would lie on a straight line. The threshold associated with the sigmoid curve disappears. Scale segmentation is shown to be a necessity for addressing multiscale energy dissipative processes such as fatigue and creep. Path independency and energy release rate are monoscale criteria that can lead to unphysical results, violating the first principles. Application of monoscale failure or fracture criteria to nanomaterials is taking toll at the expense of manufacturing super strength and light materials and structural components. This brief view is offered in the spirit of much needed additional research for the reinforcement of materials by creating nanoscale interfaces with sustainable time in service. The step by step consideraton at the different scales may offer a better understanding of the test data and their limitations with reference to space and time.

Objective assessment of motor fatigue in multiple sclerosis using kinematic gait analysis: a pilot study

PubMed Central

2011-01-01

Background Fatigue is a frequent and serious symptom in patients with Multiple Sclerosis (MS). However, to date there are only few methods for the objective assessment of fatigue. The aim of this study was to develop a method for the objective assessment of motor fatigue using kinematic gait analysis based on treadmill walking and an infrared-guided system. Patients and methods Fourteen patients with clinically definite MS participated in this study. Fatigue was defined according to the Fatigue Scale for Motor and Cognition (FSMC). Patients underwent a physical exertion test involving walking at their pre-determined patient-specific preferred walking speed until they reached complete exhaustion. Gait was recorded using a video camera, a three line-scanning camera system with 11 infrared sensors. Step length, width and height, maximum circumduction with the right and left leg, maximum knee flexion angle of the right and left leg, and trunk sway were measured and compared using paired t-tests (α = 0.005). In addition, variability in these parameters during one-minute intervals was examined. The fatigue index was defined as the number of significant mean and SD changes from the beginning to the end of the exertion test relative to the total number of gait kinematic parameters. Results Clearly, for some patients the mean gait parameters were more affected than the variability of their movements while other patients had smaller differences in mean gait parameters with greater increases in variability. Finally, for other patients gait changes with physical exertion manifested both in changes in mean gait parameters and in altered variability. The variability and fatigue indices correlated significantly with the motoric but not with the cognitive dimension of the FSMC score (R = -0.602 and R = -0.592, respectively; P < 0.026). Conclusions Changes in gait patterns following a physical exertion test in patients with MS suffering from motor fatigue can be measured objectively. These changes in gait patterns can be described using the motor fatigue index and represent an objective measure to assess motor fatigue in MS patients. The results of this study have important implications for the assessments and treatment evaluations of fatigue in MS. PMID:22029427

Protocol for a pilot randomised controlled trial of an online intervention for post-treatment cancer survivors with persistent fatigue

PubMed Central

Corbett, Teresa; Walsh, Jane C; Groarke, AnnMarie; Moss-Morris, Rona; McGuire, Brian E

2016-01-01

Introduction Many post-treatment cancer survivors experience persistent fatigue that can disrupt attempts to resume normal everyday activities after treatment. Theoretical models that aim to explain contributory factors that initiate and sustain fatigue symptoms, or that influence the efficacy of interventions for cancer-related fatigue (CrF) require testing. Adjustment to fatigue is likely to be influenced by coping behaviours that are guided by the representations of the symptom. Objectives This paper describes the protocol for a pilot trial of a systematically and theoretically designed online intervention to enable self-management of CrF after cancer treatment. Methods and analysis This 2-armed randomised controlled pilot trial will study the feasibility and potential effectiveness of an online intervention. Participants will be allocated to either the online intervention (REFRESH (Recovery from Cancer-Related Fatigue)), or a leaflet comparator. Participants 80 post-treatment cancer survivors will be recruited for the study. Interventions An 8-week online intervention based on cognitive–behavioural therapy. Primary and secondary outcome measures The primary outcome is a change in fatigue as measured by the Piper Fatigue Scale (revised). Quality of life will be measured using the Quality of Life in Adult Survivors of Cancer Scale. Outcome measures will be collected at baseline, and at completion of intervention. Results The feasibility of trial procedures will be tested, as well as the effect of the intervention on the outcomes. Conclusions This study may lead to the development of a supportive resource to target representations and coping strategies of cancer survivors with CrF post-treatment. Setting Recruitment from general public in Ireland. Ethics and dissemination This trial was approved by the Research Ethics Committee at National University of Ireland Galway in January 2013. Trial results will be communicated in a peer-reviewed journal. Trial registration number ISRCTN55763085; Pre-results. PMID:27288384

Full-Scale Testing and Analysis of Curved Aircraft Fuselage Panels.

DOT National Transportation Integrated Search

1993-12-01

The report presents data on (1) residual strength of aircraft panels containing Multiple-Site Damage (MSD) in lap splices, and (2) fatigue strength of panels subjected to cyclic pressure loading. The testing was conducted using the dedicated Aging Ai...

Factorial invariance of pediatric patient self-reported fatigue across age and gender: a multigroup confirmatory factor analysis approach utilizing the PedsQL™ Multidimensional Fatigue Scale.

PubMed

Varni, James W; Beaujean, A Alexander; Limbers, Christine A

2013-11-01

In order to compare multidimensional fatigue research findings across age and gender subpopulations, it is important to demonstrate measurement invariance, that is, that the items from an instrument have equivalent meaning across the groups studied. This study examined the factorial invariance of the 18-item PedsQL™ Multidimensional Fatigue Scale items across age and gender and tested a bifactor model. Multigroup confirmatory factor analysis (MG-CFA) was performed specifying a three-factor model across three age groups (5-7, 8-12, and 13-18 years) and gender. MG-CFA models were proposed in order to compare the factor structure, metric, scalar, and error variance across age groups and gender. The analyses were based on 837 children and adolescents recruited from general pediatric clinics, subspecialty clinics, and hospitals in which children were being seen for well-child checks, mild acute illness, or chronic illness care. A bifactor model of the items with one general factor influencing all the items and three domain-specific factors representing the General, Sleep/Rest, and Cognitive Fatigue domains fit the data better than oblique factor models. Based on the multiple measures of model fit, configural, metric, and scalar invariance were found for almost all items across the age and gender groups, as was invariance in the factor covariances. The PedsQL™ Multidimensional Fatigue Scale demonstrated strict factorial invariance for child and adolescent self-report across gender and strong factorial invariance across age subpopulations. The findings support an equivalent three-factor structure across the age and gender groups studied. Based on these data, it can be concluded that pediatric patients across the groups interpreted the items in a similar manner regardless of their age or gender, supporting the multidimensional factor structure interpretation of the PedsQL™ Multidimensional Fatigue Scale.

The Association between Daytime Napping and Cognitive Functioning in Chronic Fatigue Syndrome

PubMed Central

Gotts, Zoe M.; Ellis, Jason G.; Deary, Vincent; Barclay, Nicola; Newton, Julia L.

2015-01-01

Objectives The precise relationship between sleep and physical and mental functioning in chronic fatigue syndrome (CFS) has not been examined directly, nor has the impact of daytime napping. This study aimed to examine self-reported sleep in patients with CFS and explore whether sleep quality and daytime napping, specific patient characteristics (gender, illness length) and levels of anxiety and depression, predicted daytime fatigue severity, levels of daytime sleepiness and cognitive functioning, all key dimensions of the illness experience. Methods 118 adults meeting the 1994 CDC case criteria for CFS completed a standardised sleep diary over 14 days. Momentary functional assessments of fatigue, sleepiness, cognition and mood were completed by patients as part of usual care. Levels of daytime functioning and disability were quantified using symptom assessment tools, measuring fatigue (Chalder Fatigue Scale), sleepiness (Epworth Sleepiness Scale), cognitive functioning (Trail Making Test, Cognitive Failures Questionnaire), and mood (Hospital Anxiety and Depression Scale). Results Hierarchical Regressions demonstrated that a shorter time since diagnosis, higher depression and longer wake time after sleep onset predicted 23.4% of the variance in fatigue severity (p <.001). Being male, higher depression and more afternoon naps predicted 25.6% of the variance in objective cognitive dysfunction (p <.001). Higher anxiety and depression and morning napping predicted 32.2% of the variance in subjective cognitive dysfunction (p <.001). When patients were classified into groups of mild and moderate sleepiness, those with longer daytime naps, those who mainly napped in the afternoon, and those with higher levels of anxiety, were more likely to be in the moderately sleepy group. Conclusions Napping, particularly in the afternoon is associated with poorer cognitive functioning and more daytime sleepiness in CFS. These findings have clinical implications for symptom management strategies. PMID:25575044

The association between daytime napping and cognitive functioning in chronic fatigue syndrome.

PubMed

Gotts, Zoe M; Ellis, Jason G; Deary, Vincent; Barclay, Nicola; Newton, Julia L

2015-01-01

The precise relationship between sleep and physical and mental functioning in chronic fatigue syndrome (CFS) has not been examined directly, nor has the impact of daytime napping. This study aimed to examine self-reported sleep in patients with CFS and explore whether sleep quality and daytime napping, specific patient characteristics (gender, illness length) and levels of anxiety and depression, predicted daytime fatigue severity, levels of daytime sleepiness and cognitive functioning, all key dimensions of the illness experience. 118 adults meeting the 1994 CDC case criteria for CFS completed a standardised sleep diary over 14 days. Momentary functional assessments of fatigue, sleepiness, cognition and mood were completed by patients as part of usual care. Levels of daytime functioning and disability were quantified using symptom assessment tools, measuring fatigue (Chalder Fatigue Scale), sleepiness (Epworth Sleepiness Scale), cognitive functioning (Trail Making Test, Cognitive Failures Questionnaire), and mood (Hospital Anxiety and Depression Scale). Hierarchical Regressions demonstrated that a shorter time since diagnosis, higher depression and longer wake time after sleep onset predicted 23.4% of the variance in fatigue severity (p <.001). Being male, higher depression and more afternoon naps predicted 25.6% of the variance in objective cognitive dysfunction (p <.001). Higher anxiety and depression and morning napping predicted 32.2% of the variance in subjective cognitive dysfunction (p <.001). When patients were classified into groups of mild and moderate sleepiness, those with longer daytime naps, those who mainly napped in the afternoon, and those with higher levels of anxiety, were more likely to be in the moderately sleepy group. Napping, particularly in the afternoon is associated with poorer cognitive functioning and more daytime sleepiness in CFS. These findings have clinical implications for symptom management strategies.

Rotorcraft fatigue life-prediction: Past, present, and future

NASA Technical Reports Server (NTRS)

Everett, Richard A., Jr.; Elber, W.

1994-01-01

In this paper the methods used for calculating the fatigue life of metallic dynamic components in rotorcraft is reviewed. In the past, rotorcraft fatigue design has combined constant amplitude tests of full-scale parts with flight loads and usage data in a conservative manner to provide 'safe life' component replacement times. This is in contrast to other industries, such as the automobile industry, where spectrum loading in fatigue testing is a part of the design procedure. Traditionally, the linear cumulative damage rule has been used in a deterministic manner using a conservative value for fatigue strength based on a one in a thousand probability of failure. Conservatism on load and usage are also often employed. This procedure will be discussed along with the current U.S. Army fatigue life specification for new rotorcraft which is the so-called 'six nines' reliability requirement. In order to achieve the six nines reliability requirement the exploration and adoption of new approaches in design and fleet management may also be necessary if this requirement is to be met with a minimum impact on structural weight. To this end a fracture mechanics approach to fatigue life design may be required in order to provide a more accurate estimate of damage progression. Also reviewed in this paper is a fracture mechanics approach for calculating total fatigue life which is based on a crack-closure small crack considerations.

[Indicators of dynamic work tolerability in healthy subjects].

PubMed

Capodaglio, E M; Capodaglio, P

1997-01-01

This paper reports a study on the dynamics of tolerability in performing dynamic cycling in healthy subjects. Data on individually tolerable levels (power x duration) was obtained from 9 subjects by means of three submaximal tests on an ergometric bicycle lasting < or = 40 minutes, with constant load (50%, 65% and 80% of maximum VO2 reached during a previous test of increasing difficulty within the limits of the symptoms). During performance of the test we monitored heart rate and subjective perception of fatigue (Borg's 10-point scale). We then defined the individual functions of "isoperception", which expressed the individual trend of the product "power x duration" at identical subjective perception score. On the basis of the metabolic parameters monitored, the individual isoperceptive functions at a "moderate" level of fatigue (3 on the Borg scale) were defined as "tolerability) threshold" for prolonged dynamic cycling. The product "power x duration" defined by the isoperceptive curves at a "moderate" level of fatigue does in fact reflect the individual aerobic capacity that can be sustained for prolonged dynamic activity (under 60 minutes). In order to validate the hypothesis of tolerability of the functions identified, three further short tests were performed (duration < or = 8.5 minutes) on an ergometric bicycle, with measurement of ventilatory and metabolic parameters.

Structural qualification testing and operational loading on a fiberglass rotor blade for the Mod-OA wind turbine

NASA Technical Reports Server (NTRS)

Sullivan, T. L.

1983-01-01

Fatigue tests were performed on full- and half-scale root end sections, first to qualify the root retention design, and second to induce failure. Test methodology and results are presented. Two operational blades were proof tested to design limit load to ascertain buckling resistance. Measurements of natural frequency, damping ratio, and deflection under load made on the operational blades are documented. The tests showed that all structural design requirements were met or exceeded. Blade loads measured during 3000 hr of field operation were close to those expected. The measured loads validated the loads used in the fatigue tests and gave high confidence in the ability of the blades to achieve design life.

Oxidative stress is involved in fatigue induced by overnight deskwork as assessed by increase in plasma tocopherylhydroqinone and hydroxycholesterol.

PubMed

Shichiri, Mototada; Harada, Nobuyoshi; Ishida, Noriko; Komaba, Lilian Kaede; Iwaki, Sunao; Hagihara, Yoshihisa; Niki, Etsuo; Yoshida, Yasukazu

2013-12-01

In this study, we examined the relationship between fatigue and plasma concentrations of antioxidants and lipid peroxidation products. Fourteen healthy volunteers performed overnight desk work for 18h then took a nap for 4h. Participants answered questionnaires of subjective symptoms of fatigue (QSSF) and completed a self-assessment of fatigue using a visual analog scale (VAS). At each test time, they underwent a critical flicker frequency (CFF) test and blood samples were collected. Plasma levels of α-tocopherol (αT) decreased and α-tocopherylquinone (αTQ), the oxidation product of αT, increased. The ratio of 7β-hydroxycholesterol (7β-OHCh), the oxidation product of cholesterol, against total cholesterol increased until the end of experiment. αTQ levels correlated with VAS and QSSF scores. The ratio of 7β-OHCh to total cholesterol and the value of CFF showed a significant correlation. From these results, plasma levels of αTQ and 7β-OHCh are useful and objective indicators of fatigue induced by overnight deskwork. Copyright © 2013 Elsevier B.V. All rights reserved.

Evidence for sensitized fatigue pathways in patients with chronic fatigue syndrome.

PubMed

Staud, Roland; Mokthech, Meriem; Price, Donald D; Robinson, Michael E

2015-04-01

Patients with chronic fatigue syndrome (CFS) frequently demonstrate intolerance to physical exertion that is often reported as increased and long-lasting fatigue. Because no specific metabolic alterations have been identified in CFS patients, we hypothesized that sensitized fatigue pathways become activated during exercise corresponding with increased fatigue. After exhausting handgrip exercise, muscle metabolites were trapped in the forearm tissues of 39 CFS patients and 29 normal control (NC) by sudden occlusion for up to 5 minutes. A nonocclusive condition of similar duration was used as control. Repeated fatigue and pain ratings were obtained before and after exercise. Mechanical and heat hyperalgesia were assessed by quantitative sensory testing. All subjects fulfilled the 1994 Fukuda Criteria for CFS. Normal control and CFS subjects exercised for 6.6 (2.4) and 7.0 (2.7) minutes (P > 0.05). Forearm occlusion lasted for 4.7 (1.3) and 4.9 (1.8) minutes in NC and CFS subjects, respectively (P > 0.05). Although fatigue ratings of CFS subjects increased from 4.8 (2.0) to 5.6 (2.1) visual analogue scale (VAS) units during forearm occlusion, they decreased from 5.0 (1.8) to 4.8 (2.0) VAS units during the control condition without occlusion (P = 0.04). A similar time course of fatigue ratings was observed in NC (P > 0.05), although their ratings were significantly lower than those of CFS subjects (P < 0.001). Quantitative sensory testing demonstrated heat and mechanical hyperalgesia in CFS subjects. Our findings provide indirect evidence for significant contributions of peripheral tissues to the increased exercise-related fatigue in CFS patients consistent with sensitization of fatigue pathways. Future interventions that reduce sensitization of fatigue pathways in CFS patients may be of therapeutic benefit.

Evaluation of the effect of progressive relaxation exercises on fatigue and sleep quality in patients with multiple sclerosis.

PubMed

Dayapoğlu, Nuray; Tan, Mehtap

2012-10-01

Fatigue and sleep problems are very commonly observed in patients with multiple sclerosis (MS). The Progressive Muscle Relaxation Technique (PMRT), used as one of the alternative methods in recent years, is reported to have benefits such as facilitating sleep and reducing sensitivity against fatigue. This research was conducted to investigate the effect of PMRT on fatigue and sleep quality in patients with MS. This research was performed as a single-group pretest/post-test pretrial model. The research was conducted between March 2008 and December 2009 in the neurology polyclinic. The study was conducted with 32 patients who met the research criteria and agreed to participate in the study. A Personal Information Form was used as a data collection tool, Fatigue Severity Scale was used for measuring fatigue, and the Pittsburgh Sleep Quality Index was used for evaluating the sleep quality. PMRT was applied to the sample group once a day for 6 weeks. Percentage, paired t-test, and Pearson's correlation analysis were used in the assessment of data. It was determined that PMRT decreased patients' fatigue level and improved their sleep quality, and this difference was observed to be statistically significant. Moreover, patients' fatigue level increased as their sleep quality decreased. This study supports the effect of PMRT on fatigue and sleep quality in patients with MS, and it is recommended that further studies be conducted on this subject in the future.

Evaluation of multidimensional COPD-related subjective fatigue following a pulmonary rehabilitation programme.

PubMed

Lewko, Agnieszka; Bidgood, Penelope L; Jewell, Andy; Garrod, Rachel

2014-01-01

Subjective fatigue has been recognised as an important, multi-component symptom in COPD. Pulmonary Rehabilitation (PR) improves fatigue component of the Chronic Respiratory Questionnaire, a quality of life (QoL) measure. However, it is not clear if all fatigue dimensions are affected equally. This study aims to evaluate changes in subjective multidimensional fatigue among people with COPD who participated in PR. Thirty seven stable COPD patients were recruited; 23 patients (15 male) mean age 68.5 (range 49-86) yrs, mean (SD) %predicted FEV1 45.3 (19.8); completed 7 weeks of PR. Assessments (pre and post PR) consisted of the Multidimensional Fatigue Inventory (MFI-20), QoL (SGRQ), Anxiety and Depression (HADS), the London Chest Activity of Daily Living Scale (LCADL), muscle strength, incremental (ISWT) and endurance (ESWT) shuttle walk tests. The differences between pre and post PR fatigue were tested using Wilcoxon's test and relationships with other outcomes were examined using Spearman's correlation. There were statistically significant improvements in Reduced Activity (RA) (p = 0.01), General (GF) (p < 0.01) and Physical Fatigue (PF) (p = 0.03) components of MFI-20 after PR, but there were no differences in Motivation or Mental Fatigue (p > 0.05). There were significant improvements in ISWT (p < 0.05), ESWT (p < 0.01) and muscle strength (p = 0.03). Statistically significant correlations (p < 0.05) were found between changes in GF and in both ISWT (r = -0.43) and SGRQ impact (r = 0.46); and between RA and ESWT changes (r = -0.45). Some dimensions of fatigue in COPD are modifiable by a 7-week PR programme. Change in fatigue dimensions in COPD may be associated with a change in maximal or endurance walking distances or QoL. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of the minimal clinically important difference for seven measures of fatigue in Swedish patients with systemic lupus erythematosus.

PubMed

Pettersson, S; Lundberg, I E; Liang, M H; Pouchot, J; Henriksson, E Welin

2015-05-01

To estimate the minimal clinically important difference (MCID) in seven self-administered measures assessing fatigue in Swedish patients with systemic lupus erythematosus (SLE). The participants (n = 51, women 98%, age 52.8 ± 12.1 years, disease duration 18.7 ± 13.6 years) met in groups of six to nine persons. After completing seven fatigue questionnaires [the Fatigue Severity Scale (FSS); the Multidimensional Assessment of Fatigue (MAF) scale; the 20-item Multidimensional Fatigue Inventory (MFI); the Chalder Fatigue Scale (CFS); the Short Form-36 Vitality subscale (VT); the Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F) scale; and the Numeric Rating Scale (NRS)], each respondent had a minimum of five face-to-face discussions, followed by an individual comparative assessment of their own level of fatigue (seven-grade scale). This method resulted in 260 contrasting assessments; MCIDs were first calculated using the paired differences and then established by a regression approach. Patients were asked to comment on their experience with the questionnaires and whether they captured their fatigue adequately. The paired approach (using 'little more fatigue' as an anchor for MCID during the face-to-face comparative assessments) provided estimates of 4.6-17.0; the regression approach provided estimates of 4.3-10.8. Estimates using the regression approach were consistently lower than those using the paired model. The MCID estimates were least favourable and fewer respondents supported the use of the NRS compared to the other self-reported questionnaires. All seven instruments detect MCIDs for fatigue in Swedish patients with SLE. However, the single-question measure was not supported by the MCID estimates or by comments from the respondents.

Exertion fatigue and chronic fatigue are two distinct constructs in people post-stroke.

PubMed

Tseng, Benjamin Y; Billinger, Sandra A; Gajewski, Byron J; Kluding, Patricia M

2010-12-01

Post-stroke fatigue is a common and neglected issue despite the fact that it impacts daily functions, quality of life, and has been linked with a higher mortality rate because of its association with a sedentary lifestyle. The purpose of this study was to identify the contributing factors of exertion fatigue and chronic fatigue in people post-stroke. Twenty-one post-stroke people (12 males, 9 females; 59.5 ± 10.3 years of age; time after stroke 4.1 ± 3.5 years) participated in the study. The response variables included exertion fatigue and chronic fatigue. Participants underwent a standardized fatigue-inducing exercise on a recumbent stepper. Exertion fatigue level was assessed at rest and immediately after exercise using the Visual Analog Fatigue Scale. Chronic fatigue was measured by the Fatigue Severity Scale. The explanatory variables included aerobic fitness, motor control, and depressive symptoms measured by peak oxygen uptake, Fugl-Meyer motor score, and the Geriatric Depression Scale, respectively. Using forward stepwise regression, we found that peak oxygen uptake was an independent predictor of exertion fatigue (P = 0.006), whereas depression was an independent predictor of chronic fatigue (P = 0.002). Exertion fatigue and chronic fatigue are 2 distinct fatigue constructs, as identified by 2 different contributing factors.

A Subject-Independent Method for Automatically Grading Electromyographic Features During a Fatiguing Contraction

PubMed Central

Jesunathadas, Mark; Poston, Brach; Santello, Marco; Ye, Jieping; Panchanathan, Sethuraman

2014-01-01

Many studies have attempted to monitor fatigue from electromyogram (EMG) signals. However, fatigue affects EMG in a subject-specific manner. We present here a subject-independent framework for monitoring the changes in EMG features that accompany muscle fatigue based on principal component analysis and factor analysis. The proposed framework is based on several time- and frequency-domain features, unlike most of the existing work, which is based on two to three features. Results show that latent factors obtained from factor analysis on these features provide a robust and unified framework. This framework learns a model from EMG signals of multiple subjects, that form a reference group, and monitors the changes in EMG features during a sustained submaximal contraction on a test subject on a scale from zero to one. The framework was tested on EMG signals collected from 12 muscles of eight healthy subjects. The distribution of factor scores of the test subject, when mapped onto the framework was similar for both the subject-specific and subject-independent cases. PMID:22498666

A Rasch Analysis of Assessments of Morning and Evening Fatigue in Oncology Patients Using the Lee Fatigue Scale.

PubMed

Lerdal, Anners; Kottorp, Anders; Gay, Caryl; Aouizerat, Bradley E; Lee, Kathryn A; Miaskowski, Christine

2016-06-01

To accurately investigate diurnal variations in fatigue, a measure needs to be psychometrically sound and demonstrate stable item function in relationship to time of day. Rasch analysis is a modern psychometric approach that can be used to evaluate these characteristics. To evaluate, using Rasch analysis, the psychometric properties of the Lee Fatigue Scale (LFS) in a sample of oncology patients. The sample comprised 587 patients (mean age 57.3 ± 11.9 years, 80% women) undergoing chemotherapy for breast, gastrointestinal, gynecological, or lung cancer. Patients completed the 13-item LFS within 30 minutes of awakening (i.e., morning fatigue) and before going to bed (i.e., evening fatigue). Rasch analysis was used to assess validity and reliability. In initial analyses of differential item function, eight of the 13 items functioned differently depending on whether the LFS was completed in the morning or in the evening. Subsequent analyses were conducted separately for the morning and evening fatigue assessments. Nine of the morning fatigue items and 10 of the evening fatigue items demonstrated acceptable goodness-of-fit to the Rasch model. Principal components analyses indicated that both morning and evening assessments demonstrated unidimensionality. Person-separation indices indicated that both morning and evening fatigue scales were able to distinguish four distinct strata of fatigue severity. Excluding four items from the morning fatigue scale and three items from the evening fatigue scale improved the psychometric properties of the LFS for assessing diurnal variations in fatigue severity in oncology patients. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

A comparison of muscle strength and endurance, exercise capacity, fatigue perception and quality of life in patients with chronic obstructive pulmonary disease and healthy subjects: a cross-sectional study.

PubMed

Calik-Kutukcu, Ebru; Savci, Sema; Saglam, Melda; Vardar-Yagli, Naciye; Inal-Ince, Deniz; Arikan, Hulya; Aribas, Zeynep; Ozer, Ozge; Bosnak-Guclu, Meral; Coplu, Lutfi

2014-01-27

Chronic obstructive pulmonary disease (COPD) has significant systemic effects that substantially impact quality of life and survival. The purpose of this study was to assess and compare peripheral muscle strength and endurance, exercise capacity, fatigue perception and quality of life between patients with COPD and healthy subjects. Twenty COPD patients (mean FEV1 49.3 ± 19.2%) and 20 healthy subjects were included in the study. Pulmonary function testing and six-minute walk test (6MWT) were performed. Peripheral muscle strength was measured with a hand-held dynamometer, peripheral muscle endurance was evaluated with sit-ups, squats and modified push-ups tests. Fatigue perception was assessed using the Fatigue Impact Scale (FIS) and Fatigue Severity Scale (FSS). General quality of life was determined with the Nottingham Health Profile (NHP), and cough-specific quality of life was evaluated with the Leicester Cough Questionnaire (LCQ). Pulmonary functions, strength of shoulder abductor and flexor muscles, numbers of sit-ups and squats, 6MWT distance and 6MWT% were significantly lower in COPD patients than in healthy subjects (p < 0.05). FIS psychosocial sub-dimension and total scores, NHP scores for all sub-dimensions except pain sub-dimension of the COPD group were significantly higher than those of healthy subjects (p < 0.05). The LCQ physical, psychological and social sub-dimensions and total scores were significantly lower in COPD patients than in healthy subjects (p < 0.05). Pulmonary functions, peripheral muscle strength and endurance, exercise capacity and quality of life were adversely affected in patients with COPD. There are greater effect of fatigue on psychosocial functioning and general daily life activities and effect of cough on the quality of life in patients with COPD. This study supports the idea that COPD patients must be evaluated in a comprehensive manner for planning pulmonary rehabilitation programs.

A comparison of muscle strength and endurance, exercise capacity, fatigue perception and quality of life in patients with chronic obstructive pulmonary disease and healthy subjects: a cross-sectional study

PubMed Central

2014-01-01

Background Chronic obstructive pulmonary disease (COPD) has significant systemic effects that substantially impact quality of life and survival. The purpose of this study was to assess and compare peripheral muscle strength and endurance, exercise capacity, fatigue perception and quality of life between patients with COPD and healthy subjects. Methods Twenty COPD patients (mean FEV1 49.3 ± 19.2%) and 20 healthy subjects were included in the study. Pulmonary function testing and six-minute walk test (6MWT) were performed. Peripheral muscle strength was measured with a hand-held dynamometer, peripheral muscle endurance was evaluated with sit-ups, squats and modified push-ups tests. Fatigue perception was assessed using the Fatigue Impact Scale (FIS) and Fatigue Severity Scale (FSS). General quality of life was determined with the Nottingham Health Profile (NHP), and cough-specific quality of life was evaluated with the Leicester Cough Questionnaire (LCQ). Results Pulmonary functions, strength of shoulder abductor and flexor muscles, numbers of sit-ups and squats, 6MWT distance and 6MWT% were significantly lower in COPD patients than in healthy subjects (p < 0.05). FIS psychosocial sub-dimension and total scores, NHP scores for all sub-dimensions except pain sub-dimension of the COPD group were significantly higher than those of healthy subjects (p < 0.05). The LCQ physical, psychological and social sub-dimensions and total scores were significantly lower in COPD patients than in healthy subjects (p < 0.05). Conclusions Pulmonary functions, peripheral muscle strength and endurance, exercise capacity and quality of life were adversely affected in patients with COPD. There are greater effect of fatigue on psychosocial functioning and general daily life activities and effect of cough on the quality of life in patients with COPD. This study supports the idea that COPD patients must be evaluated in a comprehensive manner for planning pulmonary rehabilitation programs. PMID:24468029

Comparison of SF-36 vitality scale and Fatigue Symptom Inventory in assessing cancer-related fatigue.

PubMed

Brown, Linda F; Kroenke, Kurt; Theobald, Dale E; Wu, Jingwei

2011-08-01

Cancer-related fatigue (CRF) is an important symptom in clinical practice and research. The best way to measure it, however, remains unsettled. The SF-36 vitality scale, a general measure of energy/fatigue, is a frequently cited measure. With only four items, however, its ability to adequately represent multiple CRF facets has been questioned. The 13-item Fatigue Symptom Inventory (FSI) was developed to assess multidimensional aspects of CRF. Our objectives were to assess the convergent validity and to compare the sensitivity to change of the two scales. We administered both scales at 1 month (n = 68) and 6 months (n = 96) to a subset of heterogeneous patients receiving treatment in 16 cancer centers who were enrolled in a clinical trial of pain and depression. Distributions of standardized response means (SRMs) were compared to assess sensitivity to change. Results of both scales were compared to scores on a single fatigue item from the Patient Health Questionnaire (PHQ). Mean scores for both the FSI and the vitality scale demonstrated clinically significant fatigue in the sample. The vitality scale was strongly correlated with all three FSI scales (r = -0.68 to -0.77). The vitality and FSI scales also correlated strongly with the PHQ fatigue item. Moreover, distributions of SRMs for both scales were approximately normal. Both the FSI and the vitality scale are supported as valid measures of CRF. Both demonstrated sensitivity to change across a range of effect sizes. The vitality scale may be an excellent choice when brevity is paramount; the FSI may be more appropriate when tapping specific dimensions is warranted.

Translation and validation of the Cancer-Related Fatigue Scale in Greek in a sample of patients with advanced prostate cancer

PubMed Central

Kaite, Charis; Constantinou, Marianna; Kouta, Christiana

2016-01-01

Objective To translate and validate the Cancer-Related Fatigue (CRF) Scale in the Greek language. Design A cross-sectional descriptive design was used in order to translate and validate the CRF Scale in Greek. Factor analyses were performed to understand the psychometric properties of the scale and to establish construct, criterion and convergent validity. Setting Outpatients' oncology clinics of two public hospitals in Cyprus. Participants 148 patients with advanced prostate cancer undergoing chemotherapy. Results The Cancer Fatigue Scale (CFS) had good stability (test–retest reliability r=0.79, p<0.001) and good internal consistency (Cronbach's α coefficient for all 15 items α=0.916). Furthermore, the Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO value) was found to be 0.743 and considered to be satisfactory (>0.5). The correlations between the CFS physical scale (CFS-FS scale) and the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 physical subscales were found to be significant (r=−0.715). The same occurred between CFS cognitive and EORTC cognitive subscale (r=−0.579). Overall, the criterion validity was verified. The same occurs for the convergent validity of the CFS since all correlations with the Global Health Status (q29–q30) were found to be significant. Conclusions This is the first validation study of the CRF Scale in Greek and warrant of its use in the assessment of prostate cancer patient's related fatigue. However, further testing and validation is needed in the early stages of the disease and in patients in later chemotherapy cycles. PMID:27913557

Oxidation and the Effects of High Temperature Exposures on Notched Fatigue Life of an Advanced Powder Metallurgy Disk Superalloy

NASA Technical Reports Server (NTRS)

Sudbrack, Chantal K.; Draper, Susan L.; Gorman, Timothy T.; Telesman, Jack; Gab, Timothy P.; Hull, David R.

2012-01-01

Oxidation and the effects of high temperature exposures on notched fatigue life were considered for a powder metallurgy processed supersolvus heat-treated ME3 disk superalloy. The isothermal static oxidation response at 704 C, 760 C, and 815 C was consistent with other chromia forming nickel-based superalloys: a TiO2-Cr2O3 external oxide formed with a branched Al2O3 internal subscale that extended into a recrystallized - dissolution layer. These surface changes can potentially impact disk durability, making layer growth rates important. Growth of the external scales and dissolution layers followed a cubic rate law, while Al2O3 subscales followed a parabolic rate law. Cr- rich M23C6 carbides at the grain boundaries dissolved to help sustain Cr2O3 growth to depths about 12 times thicker than the scale. The effect of prior exposures was examined through notched low cycle fatigue tests performed to failure in air at 704 C. Prior exposures led to pronounced debits of up to 99 % in fatigue life, where fatigue life decreased inversely with exposure time. Exposures that produced roughly equivalent 1 m thick external scales at the various isotherms showed statistically equivalent fatigue lives, establishing that surface damage drives fatigue debit, not exposure temperature. Fractographic evaluation indicated the failure mode for the pre-exposed specimens involved surface crack initiations that shifted with exposure from predominately single intergranular initiations with transgranular propagation to multi-initiations from the cracked external oxide with intergranular propagation. Weakened grain boundaries at the surface resulting from the M23C6 carbide dissolution are partially responsible for the intergranular cracking. Removing the scale and subscale while leaving a layer where M23C6 carbides were dissolved did not lead to a significant fatigue life improvement, however, also removing the M23C6 carbide dissolution layer led to nearly full recovery of life, with a transgranular initiation typical to that observed in unexposed specimens.

Learning to control an SSVEP-based BCI speller in naïve subjects.

PubMed

Zhihua Tang; Yijun Wang; Guoya Dong; Weihua Pei; Hongda Chen

2017-07-01

High-speed steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) has been demonstrated in several recent studies. This study aimed to investigate some issues regarding feasibility of learning to control an SSVEP-based BCI speller in naïve subjects. An experiment with new BCI users was designed to answer the following questions: (1) How many people can use the SSVEP-BCI speller? (2) How much time is required to train the user? (3) Does continuous system use lead to user fatigue and deteriorated BCI performance? The experiment consisted of three tasks including a 40-class BCI spelling task, a psychomotor vigilance test (PVT) task, and a test of sleepiness scale. Subjects' reaction time (RT) in the PVT task and the fatigue rank in the sleepiness scale test were used as objective and subjective parameters to evaluate subjects' alertness level. Among 11 naïve subjects, 10 of them fulfilled the 9-block experiment. Four of them showed clear learning effects (i.e., an increasing trend of classification accuracy and information transfer rate (ITR)) over time. The remaining subjects showed stable BCI performance during the whole experiment. The results of RT and fatigue rank showed a gradually increasing trend, which is not significant across blocks. In summary, the results of this study suggest that controlling an SSVEP-based BCI speller is in general feasible to learn by naïve subjects after a short training procedure, showing no clear performance deterioration related to fatigue.

The effects of fatigue and pain on daily life activities in systemic lupus erythematosus.

PubMed

Özel, Filiz; Argon, Gülümser

2015-01-01

The aim of this study was to determine the effects of pain and fatigue on daily life activities of systemic lupus erythematosus (SLE) patients. The study sample included 74 SLE patients who presented to outpatient departments of a university hospital and two local hospitals between 30.9.2009 and 15.5.2010. Data was collected using the Fatigue Severity Scale, Katz's Activity's Daily Living Index, Lawton and Brody's Instrumental Activities of Daily Living, and the McGill Pain Questionnaire. The mean scores were 6.0 (fatigue) on the Fatigue Severity Scale, 18.0 (independent) on the Daily Life Activities Index, 24.0 (independent) on the Instrumental Daily Life Activities Index, and 1.56 (discomforting) on the McGill Pain Scale for pain felt at the moment of questioning. A low-level negative relationship was observed between the scores on the Fatigue Severity Scale and the Daily Life Activities Index (p<0.05, r=-0.298), and between Fatigue and Instrumental Daily Life Activities scores (p<0.05, r=-0.354). A medium-level positive relationship was observed between the scores on the Fatigue Severity Scale and the McGill Pain Scale (p<0.05, r=0.478). This study determined that pain and fatigue affected the daily lives of SLE patients. The study should be repeated on a larger sample.

3D-FE Modeling of 316 SS under Strain-Controlled Fatigue Loading and CFD Simulation of PWR Surge Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohanty, Subhasish; Barua, Bipul; Listwan, Joseph

In financial year 2017, we are focusing on developing a mechanistic fatigue model of surge line pipes for pressurized water reactors (PWRs). To that end, we plan to perform the following tasks: (1) conduct stress- and strain-controlled fatigue testing of surge-line base metal such as 316 stainless steel (SS) under constant, variable, and random fatigue loading, (2) develop cyclic plasticity material models of 316 SS, (3) develop one-dimensional (1D) analytical or closed-form model to validate the material models and to understand the mechanics associated with 316 SS cyclic hardening and/or softening, (4) develop three-dimensional (3D) finite element (FE) models withmore » implementation of evolutionary cyclic plasticity, and (5) develop computational fluid dynamics (CFD) model for thermal stratification, thermal-mechanical stress, and fatigue of example reactor components, such as a PWR surge line under plant heat-up, cool-down, and normal operation with/without grid-load-following. This semi-annual progress report presents the work completed on the above tasks for a 316 SS laboratory-scale specimen subjected to strain-controlled cyclic loading with constant, variable, and random amplitude. This is the first time that the accurate 3D-FE modeling of the specimen for its entire fatigue life, including the hardening and softening behavior, has been achieved. We anticipate that this work will pave the way for the development of a fully mechanistic-computer model that can be used for fatigue evaluation of safety-critical metallic components, which are traditionally evaluated by heavy reliance on time-consuming and costly test-based approaches. This basic research will not only help the nuclear reactor industry for fatigue evaluation of reactor components in a cost effective and less time-consuming way, but will also help other safety-related industries, such as aerospace, which is heavily dependent on test-based approaches, where a single full-scale fatigue test can cost millions of dollars and require years of effort to conduct. Toward our goal of demonstration of fully mechanistic fatigue evaluation of reactor components, we also started work on developing a component-level computer model of reactor components, such as 316 SS surge line pipe. This requires developing a thermal-mechanical stress analysis model of the reactor surge line, which, in turn, requires time-dependent temperature and stratification information along the boundary of the pipe. Toward that goal, CFD models of surge lines are being developed. In this report, we also present some preliminary results showing the temperature conditions along the surge line wall under reactor heat-up, cool-down, and steady-state power operation.« less

Long-term benefits of exercising on quality of life and fatigue in multiple sclerosis patients with mild disability: a pilot study.

PubMed

McCullagh, Ruth; Fitzgerald, Anthony P; Murphy, Raymond P; Cooke, Grace

2008-03-01

To determine if exercise benefits patients with multiple sclerosis. Randomized controlled trial. Participants exercised at home and also attended exercise classes held in a hospital physiotherapy gym. Thirty patients, diagnosed and independently mobile, were recruited in the Dublin area. For three months, classes were held twice-weekly and participants exercised independently once-weekly. The control group was monitored monthly and management remained unchanged. Measurements were taken at baseline, three and six months. The Modified Fatigue Impact Scale (MFIS), Multiple Sclerosis Impact Scale-29 (MSIS-29) and Functional Assessment of Multiple Sclerosis (FAMS) were used to measure fatigue and quality of life (QOL). Heart rate (HR) and the Borg's Rating of Perceived Exertion (RPE) were recorded during an incremental exercise test. The change from baseline scores between groups was compared using the Mann-Whitney U-test. Twenty-four participants completed the programme (n = 12 in each group). Based on the change in scores at three months, the exercise group had significantly greater improvements in exercise capacity (HR: -14 [-18.5, -2.5] versus 0.5 [-4, 5.5], P= 0.009), QOL (FAMS: 23 [9.5, 42.5] versus -3.5 [-16, 5], P=0.006) and fatigue (MFIS: -13 [-20, -3] versus 1 [-4, 4.5], P=0.02). At six months, the difference in change scores remained significant for FAMS (19 [14, 31] versus -4.5 [-25, 8], P=0.002) and MFIS (-8.5 [-19.5, -1] versus 0.5 [-2.5, 6.5], P=0.02) only. A three-month exercise programme improved participants' exercise capacity, QOL and fatigue, with the improvements in QOL and fatigue lasting beyond the programme.

Preliminary results on the fracture analysis of multi-site cracking of lap joints in aircraft skins

NASA Astrophysics Data System (ADS)

Beuth, J. L., Jr.; Hutchinson, John W.

1992-07-01

Results of a fracture mechanics analysis relevant to fatigue crack growth at rivets in lap joints of aircraft skins are presented. Multi-site damage (MSD) is receiving increased attention within the context of problems of aging aircraft. Fracture analyses previously carried out include small-scale modeling of rivet/skin interactions, larger-scale two-dimensional models of lap joints similar to that developed here, and full scale three-dimensional models of large portions of the aircraft fuselage. Fatigue testing efforts have included flat coupon specimens, two-dimensional lap joint tests, and full scale tests on specimens designed to closely duplicate aircraft sections. Most of this work is documented in the proceedings of previous symposia on the aging aircraft problem. The effect MSD has on the ability of skin stiffeners to arrest the growth of long skin cracks is a particularly important topic that remains to be addressed. One of the most striking features of MSD observed in joints of some test sections and in the joints of some of the older aircraft fuselages is the relative uniformity of the fatigue cracks from rivet to rivet along an extended row of rivets. This regularity suggests that nucleation of the cracks must not be overly difficult. Moreover, it indicates that there is some mechanism which keeps longer cracks from running away from shorter ones, or, equivalently, a mechanism for shorter cracks to catch-up with longer cracks. This basic mechanism has not been identified, and one of the objectives of the work is to see to what extent the mechanism is revealed by a fracture analysis of the MSD cracks. Another related aim is to present accurate stress intensity factor variations with crack length which can be used to estimate fatigue crack growth lifetimes once cracks have been initiated. Results are presented which illustrate the influence of load shedding from rivets with long cracks to neighboring rivets with shorter cracks. Results are also included for the effect of residual stress due to the riveting process itself.

Preliminary results on the fracture analysis of multi-site cracking of lap joints in aircraft skins

NASA Technical Reports Server (NTRS)

Beuth, J. L., Jr.; Hutchinson, John W.

1992-01-01

Results of a fracture mechanics analysis relevant to fatigue crack growth at rivets in lap joints of aircraft skins are presented. Multi-site damage (MSD) is receiving increased attention within the context of problems of aging aircraft. Fracture analyses previously carried out include small-scale modeling of rivet/skin interactions, larger-scale two-dimensional models of lap joints similar to that developed here, and full scale three-dimensional models of large portions of the aircraft fuselage. Fatigue testing efforts have included flat coupon specimens, two-dimensional lap joint tests, and full scale tests on specimens designed to closely duplicate aircraft sections. Most of this work is documented in the proceedings of previous symposia on the aging aircraft problem. The effect MSD has on the ability of skin stiffeners to arrest the growth of long skin cracks is a particularly important topic that remains to be addressed. One of the most striking features of MSD observed in joints of some test sections and in the joints of some of the older aircraft fuselages is the relative uniformity of the fatigue cracks from rivet to rivet along an extended row of rivets. This regularity suggests that nucleation of the cracks must not be overly difficult. Moreover, it indicates that there is some mechanism which keeps longer cracks from running away from shorter ones, or, equivalently, a mechanism for shorter cracks to catch-up with longer cracks. This basic mechanism has not been identified, and one of the objectives of the work is to see to what extent the mechanism is revealed by a fracture analysis of the MSD cracks. Another related aim is to present accurate stress intensity factor variations with crack length which can be used to estimate fatigue crack growth lifetimes once cracks have been initiated. Results are presented which illustrate the influence of load shedding from rivets with long cracks to neighboring rivets with shorter cracks. Results are also included for the effect of residual stress due to the riveting process itself.

Increased Th17/Treg Ratio in Poststroke Fatigue

PubMed Central

Liu, Xinjing; Kenkare, Komal; Li, Shanshan; Desai, Varsha; Wong, John; Luo, Xun; Wood, Lisa J.; Xu, Yuming; Wang, Qing Mei

2015-01-01

Fatigue is a major debilitating symptom after stroke. The biological mechanisms underlying poststroke fatigue (PFS) are unknown. We hypothesized that PSF is associated with an alteration in the balance between Th17 and Treg cells. To test this hypothesis we assessed fatigue in 30 stroke survivors using the Fatigue Scale for Motor and Cognitive Functions (FSMC). Peripheral blood was collected for assessment of Th17 and Treg cell populations and measurement of interleukin-10 (IL-10). Participants were dichotomized into severe fatigue (n = 14) and low-moderate fatigue (n = 16) groups by K-mean cluster analysis of FSMC scores. There were no group differences in age, gender, stroke type, stroke severity, or time since stroke. Stroke survivors in the severe fatigue group reported greater anxiety (p = 0.004) and depression (p = 0.001) than in the low-moderate fatigue group. The ratio of Th17 to Treg cells was significantly increased in the severe fatigue group relative to the mild-moderate fatigue group (p = 0.035). Serum levels of IL-10 negatively correlated withTh17/Treg ratio (r = −0.408,  p = 0.025). Our preliminary findings suggest that an imbalance in the Th17/Treg ratio is associated with the severity of PSF. PMID:26166952

[Study on relationship between fatigue and work ability in chemistry workers].

PubMed

Wu, Si-Ying; Wang, Mian-Zhen; Wang, Zhi-Ming; Lan, Ya-Jia

2005-01-01

Explore the relationship between fatigue and work ability in 976 chemistry workers. A test of fatigue and work ability was carried out with fatigue scale and work ability index (WAI) for 976 workers, other influence factors of the work ability (such as work environment, labor load, job factors) were investigated with questionnaire. (1) The frequency of fatigue of the unmarried workers was significantly lower than that of the married workers and other marital status workers, while the score of WAI of the unmarried was significantly higher than that of those( P < 0.05); (2) the frequency of fatigue of the mental workers was significantly lower than that of the mixed physical and mental workers, while the score of WAI of the mental workers was significantly higher than that of physical workers and mixed physical and mental workers ( P < 0.05); (3) compared with the workers free of fatigue, the other workers had lower WAI scores; (4) the fatigue score correlated negatively to the WAI score (r = -0.499, P < 0.01); (5) Cumulative odds model analysis showed that after controlling the other risk factors, fatigue was an important risk factor of work ability (OR = 4.005). Fatigue has affected work ability in chemistry workers, the frequency of fatigue is higher, the score of WAI is lower.

Extrapulmonary features of bronchiectasis: muscle function, exercise capacity, fatigue, and health status.

PubMed

Ozalp, Ozge; Inal-Ince, Deniz; Calik, Ebru; Vardar-Yagli, Naciye; Saglam, Melda; Savci, Sema; Arikan, Hulya; Bosnak-Guclu, Meral; Coplu, Lutfi

2012-06-11

There are limited number of studies investigating extrapulmonary manifestations of bronchiectasis. The purpose of this study was to compare peripheral muscle function, exercise capacity, fatigue, and health status between patients with bronchiectasis and healthy subjects in order to provide documented differences in these characteristics for individuals with and without bronchiectasis. Twenty patients with bronchiectasis (43.5 ± 14.1 years) and 20 healthy subjects (43.0 ± 10.9 years) participated in the study. Pulmonary function, respiratory muscle strength (maximal expiratory pressure - MIP - and maximal expiratory pressure - MEP), and dyspnea perception using the Modified Medical Research Council Dyspnea Scale (MMRC) were determined. A six-minute walk test (6MWT) was performed. Quadriceps muscle, shoulder abductor, and hand grip strength (QMS, SAS, and HGS, respectively) using a hand held dynamometer and peripheral muscle endurance by a squat test were measured. Fatigue perception and health status were determined using the Fatigue Severity Scale (FSS) and the Leicester Cough Questionnaire (LCQ), respectively. Number of squats, 6MWT distance, and LCQ scores as well as lung function testing values and respiratory muscle strength were significantly lower and MMRC and FSS scores were significantly higher in patients with bronchiectasis than those of healthy subjects (p < 0.05). In bronchiectasis patients, QMS was significantly associated with HGS, MIP and MEP (p < 0.05). The 6MWT distance was significantly correlated to LCQ psychological score (p < 0.05). The FSS score was significantly associated with LCQ physical and total and MMRC scores (p < 0.05). The LCQ psychological score was significantly associated with MEP and 6MWT distance (p < 0.05). Peripheral muscle endurance, exercise capacity, fatigue and health status were adversely affected by the presence of bronchiectasis. Fatigue was associated with dyspnea and health status. Respiratory muscle strength was related to peripheral muscle strength and health status, but not to fatigue, peripheral muscle endurance or exercise capacity. These findings may provide insight for outcome measures for pulmonary rehabilitation programs for patients with bronchiectasis.

Fatigue during breast cancer radiotherapy: an initial randomized study of cognitive-behavioral therapy plus hypnosis.

PubMed

Montgomery, Guy H; Kangas, Maria; David, Daniel; Hallquist, Michael N; Green, Sheryl; Bovbjerg, Dana H; Schnur, Julie B

2009-05-01

The study purpose was to test the effectiveness of a psychological intervention combining cognitive-behavioral therapy and hypnosis (CBTH) to treat radiotherapy-related fatigue. Women (n = 42) scheduled for breast cancer radiotherapy were randomly assigned to receive standard medical care (SMC) (n = 20) or a CBTH intervention (n = 22) in addition to SMC. Participants assigned to receive CBTH met individually with a clinical psychologist. CBTH participants received training in hypnosis and CBT. Participants assigned to the SMC control condition did not meet with a study psychologist. Fatigue was measured on a weekly basis by using the fatigue subscale of the Functional Assessment of Chronic Illness Therapy (FACIT) and daily using visual analogue scales. Multilevel modeling indicated that for weekly FACIT fatigue data, there was a significant effect of the CBTH intervention on the rate of change in fatigue (p < .05), such that on average, CBTH participants' fatigue did not increase over the course of treatment, whereas control group participants' fatigue increased linearly. Daily data corroborated the analyses of weekly data. The results suggest that CBTH is an effective means for controlling and potentially preventing fatigue in breast cancer radiotherapy patients.

Local Muscle Fatigue and 3D Kinematics of the Cervical Spine in Healthy Subjects.

PubMed

Niederer, Daniel; Vogt, Lutz; Pippig, Torsten; Wall, Rudolf; Banzer, Winfried

2016-01-01

The authors aimed to further explore the effects of local muscle fatigue on cervical 3D kinematics and the interrelationship between these kinematic characteristics and local muscle endurance capacity in the unimpaired cervical spine. Twenty healthy subjects (38 ± 10 years; 5 women) performed 2 × 10 maximal cervical flexion-extension movements. Isometric muscle endurance tests (prone/supine lying) were applied between sets to induce local muscle fatigue quantified by Borg scale rates of perceived exertion (RPE) and slope in mean power frequency (MPF; surface electromyography; m. sternocleidomastoideus, m. splenius capitis). Cervical motion characteristics (maximal range of motion [ROM], coefficient of variation of the 10 repetitive movements, mean angular velocity, conjunct movements in transversal and frontal plane) were calculated from raw 3D ultrasonic movement data. Average isometric strength testing duration for flexion and extension correlated to the cervical ROM (r = .49/r = .48; p < .05). However, Student's t test demonstrated no significant alterations in any kinematic parameter following local muscle fatigue (p > .05). Although subjects' cervical muscle endurance capacity and motor output seems to be conjugated, no impact of local cervical muscle fatigue on motor function was shown. These findings underline the importance of complementary measures to address muscular performance and kinematic characteristics in outcome assessment and functional rehabilitation of the cervical spine.

Polyphasic Temporal Behavior of Finger-Tapping Performance: A Measure of Motor Skills and Fatigue.

PubMed

Aydin, Leyla; Kiziltan, Erhan; Gundogan, Nimet Unay

2016-01-01

Successive voluntary motor movement involves a number of physiological mechanisms and may reflect motor skill development and neuromuscular fatigue. In this study, the temporal behavior of finger tapping was investigated in relation to motor skills and fatigue by using a long-term computer-based test. The finger-tapping performances of 29 healthy male volunteers were analyzed using linear and nonlinear regression models established for inter-tapping interval. The results suggest that finger-tapping performance exhibits a polyphasic nature, and has several characteristic time points, which may be directly related to muscle dynamics and energy consumption. In conclusion, we believe that future studies evaluating the polyphasic nature of the maximal voluntary movement will lead to the definition of objective scales that can be used in the follow up of some neuromuscular diseases, as well as, the determination of motor skills, individual ability, and peripheral fatigue through the use of a low cost, easy-to-use computer-based finger-tapping test.

Micromechanical Fatigue Visco-Damage Model for Short Glass Fiber Reinforced Polyamide-66

NASA Astrophysics Data System (ADS)

Despringre, N.; Chemisky, Y.; Robert, G.; Meraghni, F.

This work presents a micromechanical fatigue damage model developed for short glass fiber reinforced PA66. It has been developed to predict the high cycle fatigue behavior of PA66/GF30. The model is based on an extended Mori-Tanaka method which includes coated inclusions, matrix viscoelasticity and the evolution of micro-scale damage. The developed model accounts for the nonlinear matrix viscoelasticity and the reinforcement orientation. The description of the damage processes is based on the experimental investigation of damage mechanisms previously performed through in-situ SEM tests and X-ray micro-computed tomography observations. Damage chronologies have been proposed involving three different processes: interface debonding/coating, matrix micro-cracking and fiber breakages. Their occurrence strongly depends on the microstructure and the relative humidity. Each damage mechanism is introduced through an evolution law coupled to local stress fields. The developed model is implemented using a UMAT subroutine. Its experimental validation is achieved under stress or strain controlled fatigue tests.

Prevalence of fatigue in a group of airline pilots.

PubMed

Reis, Cátia; Mestre, Catarina; Canhão, Helena

2013-08-01

Fatigue is a common phenomenon in airline pilots that can impair alertness and ability of crewmembers to safely operate an aircraft and perform safety related tasks. Fatigue can increase the risk of an incident or even an accident. This study provides the first prevalence values for clinically significant fatigue in Portuguese airline pilots. The hypothesis that medium/short-haul pilots may currently present different levels of fatigue than long-haul pilots was also tested. A survey was conducted by requesting Portuguese airline pilots to complete questionnaires placed in the pilots' personal lockers from 1 April until 15 May 2012. The questionnaire included the self-response Fatigue Severity Scale (FSS) to measure subjective fatigue and some additional questions concerning perception of fatigue by pilots. The prevalence values for total and mental fatigue achieved in the Portuguese airline pilots were: 89.3% (FSS > or = 4) and 94.1% (FSS > or = 4) when splitting the sample in two subsamples, long- and medium/short-haul pilots. Levels of total and mental fatigue were higher for medium/short-haul pilots. The analysis of fatigue levels in each type of aviator showed that medium/short-haul pilots presented the highest levels of total and mental fatigue. This study produced the first prevalence values of total and mental fatigue among Portuguese airline pilots, which represents a great step to understanding and addressing this critical phenomenon.

Crew fatigue safety performance indicators for fatigue risk management systems.

PubMed

Gander, Philippa H; Mangie, Jim; Van Den Berg, Margo J; Smith, A Alexander T; Mulrine, Hannah M; Signal, T Leigh

2014-02-01

Implementation of Fatigue Risk Management Systems (FRMS) is gaining momentum; however, agreed safety performance indicators (SPIs) are lacking. This paper proposes an initial set of SPIs based on measures of crewmember sleep, performance, and subjective fatigue and sleepiness, together with methods for interpreting them. Data were included from 133 landing crewmembers on 2 long-range and 3 ultra-long-range trips (4-person crews, 3 airlines, 220 flights). Studies had airline, labor, and regulatory support, and underwent independent ethical review. SPIs evaluated preflight and at top of descent (TOD) were: total sleep in the prior 24 h and time awake at duty start and at TOD (actigraphy); subjective sleepiness (Karolinska Sleepiness Scale) and fatigue (Samn-Perelli scale); and psychomotor vigilance task (PVT) performance. Kruskal-Wallis nonparametric ANOVA with post hoc tests was used to identify significant differences between flights for each SPI. Visual and preliminary quantitative comparisons of SPIs between flights were made using box plots and bar graphs. Statistical analyses identified significant differences between flights across a range of SPls. In an FRMS, crew fatigue SPIs are envisaged as a decision aid alongside operational SPIs, which need to reflect the relevant causes of fatigue in different operations. We advocate comparing multiple SPIs between flights rather than defining safe/unsafe thresholds on individual SPIs. More comprehensive data sets are needed to identify the operational and biological factors contributing to the differences between flights reported here. Global sharing of an agreed core set of SPIs would greatly facilitate implementation and improvement of FRMS.

Validity and Reliability of a New Instrument to Measure Cancer-Related Fatigue in Adolescents

PubMed Central

Hinds, Pamela S.; Hockenberry, Marilyn; Tong, Xin; Rai, Shesh N.; Gattuso, Jamie S.; McCarthy, Kathleen; Pui, Ching-Hon; Srivastava, Deo Kumar

2008-01-01

Adolescents undergoing treatment for cancer rate fatigue as their most prevalent and intense cancer- and treatment-related effect. Parents and staff rate it similarly. Despite its reported prevalence, intensity, and distressing effects, cancer-related fatigue in adolescents is not routinely assessed during or after cancer treatment. We contend that the insufficient clinical attention is primarily due to the lack of a reliable and valid self-report instrument with which adolescent cancer-related fatigue can be measured. Our aim was to determine the reliability and construct validity of a new instrument and its ability to measure change in fatigue over time. Initial testing involved 64 adolescents undergoing curative treatment of cancer who completed the Fatigue Scale-Adolescent (FS-A) at two to four key points in treatment in one of four studies. Internal consistency estimates ranged from 0.67 to 0.95. Validity estimates involving the FS-A with the parent version ranged from 0.13 to 0.76; estimates involving the staff version and the Reynolds Depression Scale were 0.27 and 0.87 respectively. Additional validity findings included significant fatigue differences between anemic and non-anemic patients (P = 0.042) and the emergence of four factors in an exploratory factor analysis. Findings further indicate that the FS-A can be used to measure change over time (t = 2.55, P <0.01). In summary, the FS-A has moderate to strong reliability and impressive validity coefficients for a new research instrument. PMID:17629669

Test-retest reliability of lower limb isokinetic endurance in COPD: A comparison of angular velocities

PubMed Central

Ribeiro, Fernanda; Lépine, Pierre-Alexis; Garceau-Bolduc, Corine; Coats, Valérie; Allard, Étienne; Maltais, François; Saey, Didier

2015-01-01

Background The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD). Methods After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV1) 55%±18% predicted) performed two quadriceps isokinetic endurance tests on two separate occasions within a 5–7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV1 for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated. Results High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities. Conclusion Despite a limited sample size, our findings support the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work) at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index could also be assessed reliably at 90° per second. Evaluation of dyspnea and leg fatigue using the modified Borg scale of perceived exertion was poorly reliable and its clinical usefulness is questionable. These results should be useful in the design and interpretation of future interventions aimed at improving muscle endurance in COPD. PMID:26124656

Validation of the Compassion Fatigue Short Scale among Chinese medical workers and firefighters: a cross-sectional study

PubMed Central

Sun, Binghai; Hu, Mengna; Yu, Shitian; Jiang, Yiru; Lou, Baona

2016-01-01

Objectives To examine the psychometric properties of the Chinese version of the C-Compassion Fatigue (CF)-Short Scale among 4 independent samples of Chinese emergency workers (medical workers and firefighters). Design Cross-sectional. Setting 6 hospitals in Zhejiang Province and 12 fire stations in Shanghai. Participants Emergency workers (medical and firefighters) were consecutively recruited and divided into 4 groups: the MW1 group (medical workers, n=167), the FF1 group (firefighters, n=157), the MW2 group (medical workers, n=265) and the FF2 group (firefighters, n=231). Interventions All patients completed the C-CF-Short Scale to identify factors associated with compassion fatigue. The MW1 and FF1 groups were used for the exploratory analyses. The MW2 and FF2 groups were used for the confirmatory factor analyses. Primary and secondary outcome measures Factor loading, correlations with previously validated questionnaires (the Ego-Resiliency Scale, the Social Support Questionnaire and the Job Pressure Scale) and Cronbach's α coefficient were tested for each factor. Results The C-CF-Short Scale demonstrated excellent construct validity and good internal consistency. Specifically, the results of exploratory factor analyses in the MW1 and FF1 groups showed that secondary trauma and job burnout were associated with compassion fatigue in these emergency workers. The confirmatory factor analyses in the MW2 and FF2 groups indicated that all the fit indices of the 2-factor model were satisfactory. Finally, the Cronbach's α coefficient of each factor was excellent. Conclusions The findings suggest that the C-CF-Short Scale has good psychometric properties and can be applied to study Chinese emergency workers. PMID:27363817

E-Readers and Visual Fatigue

PubMed Central

Benedetto, Simone; Drai-Zerbib, Véronique; Pedrotti, Marco; Tissier, Geoffrey; Baccino, Thierry

2013-01-01

The mass digitization of books is changing the way information is created, disseminated and displayed. Electronic book readers (e-readers) generally refer to two main display technologies: the electronic ink (E-ink) and the liquid crystal display (LCD). Both technologies have advantages and disadvantages, but the question whether one or the other triggers less visual fatigue is still open. The aim of the present research was to study the effects of the display technology on visual fatigue. To this end, participants performed a longitudinal study in which two last generation e-readers (LCD, E-ink) and paper book were tested in three different prolonged reading sessions separated by - on average - ten days. Results from both objective (Blinks per second) and subjective (Visual Fatigue Scale) measures suggested that reading on the LCD (Kindle Fire HD) triggers higher visual fatigue with respect to both the E-ink (Kindle Paperwhite) and the paper book. The absence of differences between E-ink and paper suggests that, concerning visual fatigue, the E-ink is indeed very similar to the paper. PMID:24386252

The effect of histamine on changes in mental energy and fatigue after a single bout of exercise.

PubMed

Loy, Bryan D; O'Connor, Patrick J

2016-01-01

The purpose of this research was to determine if histamine, acting on brain H1 receptors, influences changes in feelings of energy and fatigue or cognitive test performance after acute exercise. Women (n=20) with low vigor and high fatigue were administered the H1 antagonist drug doxepin hydrocholoride (6 mg) in tomato juice and tomato juice alone (placebo) in a randomized, double-blinded, cross-over experiment before performing 30 min of light intensity cycling exercise and completing energy, fatigue, sleepiness, and motivation scales, and cognitive tasks. After exercise, mental fatigue increased for the doxepin condition (p=0.014) but not placebo (p=0.700), while mental energy decreased for both PLA and DOX (p<0.001) and cognitive task performance was unaffected. It is inferred that histamine binding to H1 receptors in the brain has a role in exercise-induced reductions in mental fatigue, but not increases in energy. Copyright © 2015 Elsevier Inc. All rights reserved.

Effectiveness of online and face-to-face fatigue self-management programmes for adults with neurological conditions.

PubMed

Ghahari, Setareh; Packer, Tanya

2012-01-01

To evaluate effectiveness of a face-to-face and an online fatigue self-management programme and to compare these to two control groups (information-only and no-intervention) in a sample of adults (n = 115) with neurological conditions reporting extreme fatigue. Non-equivalent pre-test post-test control group design using the Fatigue Impact Scale, Personal Wellbeing Index and Activity Card Sort as primary outcome measures. Participants in the two intervention groups and the information-only group showed clinically significant improvements in fatigue over time (p < 0.05). When compared to the no-intervention group, face-to-face participants showed significantly greater improvement in overall and cognitive fatigue, while participants in the online group showed significant improvement in self-efficacy and stress. Participation in either the online or face-to-face programme appears to result in improved self-management, however, with different potency depending on outcomes. The improvement in the online information only group further complicates the understanding of the results. With few other comparisons of online and face-to-face self-management protocols available, further research is needed to understand differential impacts which may be related to the delivery format, the rural versus urban split of participants or other unknown factors.

Experimental study of crack initiation and propagation in high- and gigacycle fatigue in titanium alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bannikov, Mikhail, E-mail: mbannikov@icmm.ru, E-mail: oborin@icmm.ru, E-mail: naimark@icmm.ru; Oborin, Vladimir, E-mail: mbannikov@icmm.ru, E-mail: oborin@icmm.ru, E-mail: naimark@icmm.ru; Naimark, Oleg, E-mail: mbannikov@icmm.ru, E-mail: oborin@icmm.ru, E-mail: naimark@icmm.ru

Fatigue (high- and gigacycle) crack initiation and its propagation in titanium alloys with coarse and fine grain structure are studied by fractography analysis of fracture surface. Fractured specimens were analyzed by interferometer microscope and SEM to improve methods of monitoring of damage accumulation during fatigue test and to verify the models for fatigue crack kinetics. Fatigue strength was estimated for high cycle fatigue regime using the Luong method [1] by “in-situ” infrared scanning of the sample surface for the step-wise loading history for different grain size metals. Fine grain alloys demonstrated higher fatigue resistance for both high cycle fatigue andmore » gigacycle fatigue regimes. Fracture surface analysis for plane and cylindrical samples was carried out using optical and electronic microscopy method. High resolution profilometry (interferometer-profiler New View 5010) data of fracture surface roughness allowed us to estimate scale invariance (the Hurst exponent) and to establish the existence of two characteristic areas of damage localization (different values of the Hurst exponent). Area 1 with diameter ∼300 μm has the pronounced roughness and is associated with damage localization hotspot. Area 2 shows less amplitude roughness, occupies the rest fracture surface and considered as the trace of the fatigue crack path corresponding to the Paris kinetics.« less

The impact of fatigue and energy on work functioning and impairment in patients with major depressive disorder treated with desvenlafaxine.

PubMed

Sarfati, David; Evans, Vanessa C; Tam, Edwin M; Woo, Cindy; Iverson, Grant L; Yatham, Lakshmi N; Lam, Raymond W

2017-11-01

Fatigue and low energy are cardinal symptoms of major depressive disorder (MDD) that have an impact on work functioning. Antidepressants with noradrenergic activity have been hypothesized to improve symptoms of fatigue and low energy. We examined the impact of these symptoms on work functioning in patients with MDD treated with the serotonin and noradrenaline reuptake inhibitor, desvenlafaxine. A secondary analysis was carried out from a study of employed adult outpatients (n=35) with MDD and subjective cognitive complaints treated with desvenlafaxine 50-100 mg/day for 8 weeks. Multiple regression analyses modeled improvement in work functioning measures (Lam Employment Absence and Productivity Scale, Health and Work Performance Questionnaire, Sheehan Disability Scale) with measures of fatigue (Patient-Reported Outcomes Measurement Information System Fatigue scale and 20-item Hopkins Symptom Check List Energy scale). Patients showed a significant improvement in Montgomery-Åsberg Depression Rating Scale scores as well as in fatigue and work functioning measures following treatment. Fatigue measures were significantly associated with improvement in some (Lam Employment Absence and Productivity Scale, Sheehan Disability Scale), but not all (Health and Work Performance Questionnaire) work functioning measures, independent of improvement in overall depressive symptoms. The limitations of this study include the small sample size and the lack of a placebo or a comparison group. Fatigue and low energy are important symptoms that are associated with occupational impairment in MDD. Treatments that improve these symptoms are likely to improve work functioning.

The PedsQL in pediatric cancer: reliability and validity of the Pediatric Quality of Life Inventory Generic Core Scales, Multidimensional Fatigue Scale, and Cancer Module.

PubMed

Varni, James W; Burwinkle, Tasha M; Katz, Ernest R; Meeske, Kathy; Dickinson, Paige

2002-04-01

The Pediatric Quality of Life Inventory (PedsQL) is a modular instrument designed to measure health-related quality of life (HRQOL) in children and adolescents ages 2-18 years. The PedsQL 4.0 Generic Core Scales are multidimensional child self-report and parent proxy-report scales developed as the generic core measure to be integrated with the PedsQL disease specific modules. The PedsQL Multidimensional Fatigue Scale was designed to measure fatigue in pediatric patients. The PedsQL 3.0 Cancer Module was designed to measure pediatric cancer specific HRQOL. The PedsQL Generic Core Scales, Multidimensional Fatigue Scale, and Cancer Module were administered to 339 families (220 child self-reports; 337 parent proxy-reports). Internal consistency reliability for the PedsQL Generic Core Total Scale Score (alpha = 0.88 child, 0.93 parent report), Multidimensional Fatigue Total Scale Score (alpha = 0.89 child, 0.92 parent report) and most Cancer Module Scales (average alpha = 0.72 child, 0.87 parent report) demonstrated reliability acceptable for group comparisons. Validity was demonstrated using the known-groups method. The PedsQL distinguished between healthy children and children with cancer as a group, and among children on-treatment versus off-treatment. The validity of the PedsQL Multidimensional Fatigue Scale was further demonstrated through hypothesized intercorrelations with dimensions of generic and cancer specific HRQOL. The results demonstrate the reliability and validity of the PedsQL Generic Core Scales, Multidimensional Fatigue Scale, and Cancer Module in pediatric cancer. The PedsQL may be utilized as an outcome measure in clinical trials, research, and clinical practice. Copyright 2002 American Cancer Society.

Computational micromechanics of fatigue of microstructures in the HCF–VHCF regimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castelluccio, Gustavo M.; Musinski, William D.; McDowell, David L.

Advances in higher resolution experimental techniques have shown that metallic materials can develop fatigue cracks under cyclic loading levels significantly below the yield stress. Indeed, the traditional notion of a fatigue limit can be recast in terms of limits associated with nucleation and arrest of fatigue cracks at the microstructural scale. Though fatigue damage characteristically emerges from irreversible dislocation processes at sub-grain scales, the specific microstructure attributes, environment, and loading conditions can strongly affect the apparent failure mode and surface to subsurface transitions. This paper discusses multiple mechanisms that occur during fatigue loading in the high cycle fatigue (HCF) tomore » very high cycle fatigue (VHCF) regimes. We compare these regimes, focusing on strategies to bridge experimental and modeling approaches exercised at multiple length scales and discussing particular challenges to modeling and simulation regarding microstructure-sensitive fatigue driving forces and thresholds. Finally, we discuss some of the challenges in predicting the transition of failure mechanisms at different stress and strain amplitudes.« less

Computational micromechanics of fatigue of microstructures in the HCF–VHCF regimes

DOE PAGES

Castelluccio, Gustavo M.; Musinski, William D.; McDowell, David L.

2016-05-19

Advances in higher resolution experimental techniques have shown that metallic materials can develop fatigue cracks under cyclic loading levels significantly below the yield stress. Indeed, the traditional notion of a fatigue limit can be recast in terms of limits associated with nucleation and arrest of fatigue cracks at the microstructural scale. Though fatigue damage characteristically emerges from irreversible dislocation processes at sub-grain scales, the specific microstructure attributes, environment, and loading conditions can strongly affect the apparent failure mode and surface to subsurface transitions. This paper discusses multiple mechanisms that occur during fatigue loading in the high cycle fatigue (HCF) tomore » very high cycle fatigue (VHCF) regimes. We compare these regimes, focusing on strategies to bridge experimental and modeling approaches exercised at multiple length scales and discussing particular challenges to modeling and simulation regarding microstructure-sensitive fatigue driving forces and thresholds. Finally, we discuss some of the challenges in predicting the transition of failure mechanisms at different stress and strain amplitudes.« less

Fracture morphologies of carbon-black-loaded SBR (styrene-butadiene rubber) subjected to low-cycle, high-stress fatigue. [Styrene-butadiene rubber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, A.; Lesuer, D.R.; Patt, J.

Experimental results, together with an analytical model, related to the loss in tensile strength of styrene-butadiene rubber (SBR) loaded with carbon black (CB) that had been subjected to low-cycle, high-stress fatigue tests were presented in a prior paper. The drop in tensile strength relative to that of a virgin sample was considered to be a measure of damage induced during the fatigue test. The present paper is a continuation of this study dealing with the morphological interpretations of the fractured surfaces, whereby the cyclic-tearing behavior, resulting in the damage, is related to the test and material parameters. It was foundmore » that failure is almost always initiated in the bulk of a sample at a material flaw. The size and definition of a flaw increase with an increase in carbon-black loading. Initiation flaw sites are enveloped by fan-shaped or penny-shaped regions which develop during cycling. The size and morphology of a fatigue-tear region appears to be independent of the fatigue load or the extent of the damage (strength loss). By contrast, either an increase in cycling load or an increase in damage at constant load increases the definition of the fatigue-region morphology for all formulations of carbon-black. On the finest scale, the morphology can be described in terms of tearing of individual groups of rubber strands, collapsing to form a cell-like structure. 18 refs., 13 figs.« less

Fatigue in Patients With Advanced Terminal Cancer Correlates With Inflammation, Poor Quality of Life and Sleep, and Anxiety/Depression.

PubMed

Rodrigues, Alex Rua; Trufelli, Damila Cristina; Fonseca, Fernando; de Paula, Larissa Carvalho; Giglio, Auro Del

2016-12-01

To assess which laboratory and clinical factors are associated with fatigue in patients with terminal cancer. We evaluated 51 patients with advanced incurable solid tumors using the Chalder Fatigue Questionnaire (CFQ) and the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale for fatigue; the Pittsburgh Sleep Quality Index (PSQI-BR) for sleep quality; the Hospital Anxiety and Depression Scale (HADS) for anxiety and depression; the European Organization for Research and Treatment of Cancer (EORTC) Core Quality of Life Questionnaire, Version 3.0 (QLQ C-30); and Functional Assessment of Cancer Therapy (FACT) for quality of life. We also analyzed several inflammatory markers and the modified Glasgow prognostic score (mGPS). We observed severe fatigue in 19 (38%) patients (FACIT-F score >36). There was a significant correlation between fatigue as evaluated by the CFQ and quality of sleep and between the CFQ mental fatigue subscale scores and TNF-α level. When fatigue was evaluated using the FACIT-F scale, we observed a significant association between fatigue and anxiety/depression, quality of sleep, mGPS, and hemoglobin levels. Fatigue measured both with the CFQ and FACIT-F scale correlated with poor quality of life according to the EORTC QLQ C-30. In patients with advanced cancer, fatigue is a common symptom associated with the presence of inflammation, poor quality of sleep, depression/anxiety, and poor quality of life. © The Author(s) 2015.

[Effects of vibrotherapy on postural control, functionality and fatigue in multiple sclerosis patients. A randomised clinical trial].

PubMed

Alguacil Diego, I M; Pedrero Hernández, C; Molina Rueda, F; Cano de la Cuerda, R

2012-04-01

Postural and balance disorders, functionality impairment and fatigue, are the most incapacitating problems in multiple sclerosis (MS) patients. Whole Body Vibration (WBV), through the transmission of mechanical stimuli, appears to be a useful therapeutic tool in the treatment of neurological diseases. The objective of this study is to assess the effect of the WBV on postural control, balance, functionality and fatigue in patients with MS. A total of 34 patients with mild-moderate MS were randomised into a control group and an intervention group. For the intervention group, the protocol consisted of 5 consecutive days, daily series of 5 periods of 1 minute of duration of WBV at a frequency of 6 Hz. Posturographic assessment using the Sensory Organization Test (SOT) and Motor Control Test (MCT), the Timed Get Up and Go Test, 10 metres Test, the Berg Balance Scale and Krupp's Fatigue Severity Scale were used before and after intervention. The analysis showed improvements in the intervention group for conditions SOT 1, SOT 3 and latency in MCT. In the comparison between groups, only the latency or reaction time in MCT improved significantly in favour of the intervention group (from 173.78±12.46 to 161.25±13.64 ms; P=.04). No side-effects were found. The results of this pilot study show that WBV can improve, in the short-term, the time of response to recover the uprightness after sudden disturbances, appearing as a possible therapeutic tool maintaining balance and posture. Copyright © 2011 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

Risk factors for fatigue in patients with epilepsy.

PubMed

Yan, Song; Wu, Yuanbin; Deng, Yanchun; Liu, Yonghong; Zhao, Jingjing; Ma, Lei

2016-11-01

Fatigue is highly prevalent in patients with epilepsy and has a major impact on quality of life, but little data is available on its effects and management in epilepsy. To identify the incidence and risk factors of fatigue in patients with epilepsy, 105 epilepsy patients (45 women and 60 men) were enrolled in our study. Demographic and clinical data were collected and psychological variables including fatigue, sleep quality, excess daytime sleepiness, anxiety, and depression were measured by Fatigue Severity Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale, respectively. Of 105 patients, 29.5% exhibited fatigue (FSS score ⩾4). We found no correlation between the occurrence of fatigue and any of our demographic or clinical variables. Fatigue is correlated with low sleep quality, anxiety, and depression, but not with excess daytime sleepiness. Thus, we concluded that fatigue is highly prevalent in patients with epilepsy, and that low sleep quality, anxiety, and depression are significantly correlated with fatigue in epileptics, while excess daytime sleepiness not. Copyright © 2016. Published by Elsevier Ltd.

Design and evaluation of a 3 million DN series-hybrid thrust bearing. [stability tests and fatigue tests

NASA Technical Reports Server (NTRS)

Scibbe, H. W.; Winn, L. W.; Eusepi, M.

1976-01-01

The bearing, consisting of a 150-mm ball bearing and a centrifugally actuated, conical, fluid-film bearing, was fatigue tested. Test conditions were representative of a mainshaft ball bearing in a gas turbine engine operating at maximum thrust load to simulate aircraft takeoff conditions. Tests were conducted up to 16000 rpm and at this speed an axial load of 15568 newtons (3500 lb) was safely supported by the hybrid bearing system. Through the series-hybrid bearing principle, the effective ball bearing speed was reduced to approximately one-half of the shaft speed. It was concluded that a speed reduction of this magnitude results in a ten-fold increase in the ball bearing fatigue life. A successful evaluation of fluid-film bearing lubricant supply failure was performed repeatedly at an operating speed of 10,000 rpm. A complete and smooth changeover to full-scale ball bearing operation was effected when the oil supply to the fluid-film bearing was cut off. Reactivation of the fluid-film oil supply system resulted in a flawless return to the original mode of hybrid operation.

Fatigue and fracture assessment of cracks in steel elements using acoustic emission

NASA Astrophysics Data System (ADS)

Nemati, Navid; Metrovich, Brian; Nanni, Antonio

2011-04-01

Single edge notches provide a very well defined load and fatigue crack size and shape environment for estimation of the stress intensity factor K, which is not found in welded elements. ASTM SE(T) specimens do not appear to provide ideal boundary conditions for proper recording of acoustic wave propagation and crack growth behavior observed in steel bridges, but do provide standard fatigue crack growth rate data. A modified versions of the SE(T) specimen has been examined to provide small scale specimens with improved acoustic emission(AE) characteristics while still maintaining accuracy of fatigue crack growth rate (da/dN) versus stress intensity factor (ΔK). The specimens intend to represent a steel beam flange subjected to pure tension, with a surface crack growing transverse to a uniform stress field. Fatigue test is conducted at low R ratio. Analytical and numerical studies of stress intensity factor are developed for single edge notch test specimens consistent with the experimental program. ABAQUS finite element software is utilized for stress analysis of crack tips. Analytical, experimental and numerical analysis were compared to assess the abilities of AE to capture a growing crack.

Psychometric properties of the Multidimensional Assessment of Fatigue scale in traumatic brain injury: an NIDRR Traumatic Brain Injury Model Systems study.

PubMed

Lequerica, Anthony; Bushnik, Tamara; Wright, Jerry; Kolakowsky-Hayner, Stephanie A; Hammond, Flora M; Dijkers, Marcel P; Cantor, Joshua

2012-01-01

To investigate the psychometric properties of the Multidimensional Assessment of Fatigue (MAF) scale in a traumatic brain injury (TBI) sample. Prospective survey study. Community. One hundred sixty-seven individuals with TBI admitted for inpatient rehabilitation, enrolled into the TBI Model Systems national database, and followed up at either the first or second year postinjury. Not applicable. Multidimensional Assessment of Fatigue. The initial analysis, using items 1 to 14, which are based on a 10-point rating scale, found that only 1 item ("walking") misfit the overall construct of fatigue in this TBI population. However, this 10-point rating scale was found to have disordered thresholds. When ratings were collapsed into 4 response categories, all MAF items used to calculate the Global Fatigue Index formed a unidimensional scale. Findings generally support the unidimensionality of the MAF when used in a TBI population but call into question the use of a 10-point rating scale for items 1 to 14. Further study is needed to investigate the use of a 4-category rating scale across all items and the fit of the "walking" item for a measure of fatigue among individuals with TBI.

Psychometric properties of the multidimensional fatigue inventory in Brazilian Hodgkin's lymphoma survivors.

PubMed

Baptista, Renata Lyrio R; Biasoli, Irene; Scheliga, Adriana; Soares, Andrea; Brabo, Eloa; Morais, José Carlos; Werneck, Guilherme Loureiro; Spector, Nelson

2012-12-01

Fatigue is the most common symptom among Hodgkin's lymphoma survivors. To evaluate the psychometric properties of the Brazilian version of the Multidimensional Fatigue Inventory (MFI). The MFI was translated into Brazilian Portuguese using established forward-backward translation procedures, and the psychometric properties were evaluated in a sample of 200 Hodgkin's lymphoma survivors. The psychometric properties evaluated included internal consistency and construct validity. The MFI was administered along with the informed consent form. The overall Cronbach's alpha coefficient for the 20 items was 0.84, ranging from 0.59 to 0.81 for each of the five scales. Correlations between items and scales ranged from 0.32 to 0.72. The factor analysis yielded a five-factor solution that explained 65% of the variance. The first factor merged the original "general fatigue" and "physical fatigue" scales, as has been previously reported. The second factor identified the original "mental fatigue" scale and the fifth factor identified the original "reduced activity" scale. Questions from the original "reduced motivation" scale were represented in both factors three and four. The Brazilian version of the MFI showed satisfactory psychometric properties and can be considered a valid research tool for assessing cancer-related fatigue. Copyright © 2012 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

Relationship of fatigue and exercise capacity with emotional and physical state in patients with coronary artery disease admitted for rehabilitation program.

PubMed

Bunevicius, Adomas; Stankus, Albinas; Brozaitiene, Julija; Girdler, Susan S; Bunevicius, Robertas

2011-08-01

The relationship between subjective fatigue, exercise capacity, and symptoms of depression and anxiety in patients with coronary artery disease (CAD) needs to be specified. In this cross-sectional study, a total of 1,470 (64% men; mean age 57 ± 11 years) consecutive CAD patients admitted for cardiac rehabilitation after treatment of acute cardiac events were evaluated for demographic characteristics, for past and current diagnosis and treatment, for New York Heart Association (NYHA) class, for symptoms of depression and for symptoms of anxiety using the Hospital Anxiety and Depression Scale, and for subjective fatigue using the Multidimensional Fatigue Inventory. On the next day, all patients underwent exercise capacity evaluation using a standard bicycle ergometer testing procedure. In univariate regression analyses, there was the strongest positive association between scores on all Multidimensional Fatigue Inventory subscales and scores on the Hospital Anxiety and Depression Scale depression and anxiety subscales and between exercise capacity and NYHA class. Multivariate regression analyses revealed that symptoms of depression were the strongest positive determinants of all dimensions of subjective fatigue and, together with other significant variables, accounted for 17% to 29% of the variance. However, neither depressive nor anxious symptoms were significant determinants of exercise capacity. The association between subjective fatigue and exercise capacity and vice versa was minimal. Subjective fatigue in CAD patients is strongly related to symptoms of depression and symptoms of anxiety. In contrast, exercise capacity in CAD patients is strongly related to NYHA functional class, with no relationship to symptoms of depression and anxiety. Copyright © 2011 Mosby, Inc. All rights reserved.

Motor fatigability in persons with multiple sclerosis: Relation between different upper limb muscles, and with fatigue and the perceived use of the arm in daily life.

PubMed

Severijns, Deborah; Van Geel, Fanny; Feys, Peter

2018-01-01

Motor fatigability is increasingly acknowledged in persons with MS (pwMS). It is unknown whether fatigability is generalized across upper limb muscles and relates to fatigue and perceived difficulties in upper limb use. This observational case-controlled study included twenty PwMS (median EDSS = 3, range 1.5-6.5) and twenty healthy controls who performed 30″ sustained maximal muscle contractions for index finger abduction, hand grip, elbow flexion and shoulder abduction. A static fatigue index (SFI) was calculated to assess motor fatigability for each muscle group. PwMS completed the Fatigue Severity Scale (FSS) and Modified Fatigue Index Scale (MFIS), to quantify severity and perceived impact of fatigue and the Manual Ability Measure (MAM-36) reflecting perceived difficulty in using the upper limbs. Comparisons between groups and muscles was made by t-tests. Associations between outcomes were calculated with correlation coefficients. Fatigue was highest in pwMS. PwMS showed preserved muscle strength and a greater motor fatigability in elbow flexors compared to healthy controls. SFI of elbow flexors and shoulder abductors were associated, and contributed to FSS and MFIS. SFI of elbow flexors and finger abductors predicted half of the variation in MAM-36. Increased motor fatigability was only present in elbow flexors of PwMS, indicating that expression of motor fatigability is not generalized. Fatigability was associated with perceived fatigue (impact) and daily life upper limb use. Results are preliminary given the small sample size with predominantly persons with mild MS. Copyright © 2017 Elsevier B.V. All rights reserved.

Effort-Reward Imbalance for Learning Is Associated with Fatigue in School Children

ERIC Educational Resources Information Center

Fukuda, Sanae; Yamano, Emi; Joudoi, Takako; Mizuno, Kei; Tanaka, Masaaki; Kawatani, Junko; Takano, Miyuki; Tomoda, Akemi; Imai-Matsumura, Kyoko; Miike, Teruhisa; Watanabe, Yasuyoshi

2010-01-01

We examined relationships among fatigue, sleep quality, and effort-reward imbalance for learning in school children. We developed an effort-reward for learning scale in school students and examined its reliability and validity. Self-administered surveys, including the effort reward for leaning scale and fatigue scale, were completed by 1,023…

Application of the multidimensional fatigue inventory (MFI-20) in cancer patients receiving radiotherapy.

PubMed Central

Smets, E. M.; Garssen, B.; Cull, A.; de Haes, J. C.

1996-01-01

In this paper the psychometric properties of the multidimensional fatigue inventory (MFI-20) are established further in cancer patients. The MFI is a 20-item self-report instrument designed to measure fatigue. It covers the following dimensions: general fatigue, physical fatigue, reduced activity, reduced motivation and mental fatigue. The instrument was used in a Dutch and Scottish sample of cancer patients receiving radiotherapy. The dimensional structure was assessed using confirmatory factor analyses (Lisrel's unweighted least-squares method). The hypothesised five-factor model appeared to fit the data in both samples (adjusted goodness of fit; AGFI: 0.97 and 0.98). Internal consistency of the separate scales was good in both the Dutch and Scottish samples with Cronbach's alpha coefficients ranging from 0.79 to 0.93. Construct validity was assessed by correlating the MFI-20 to activities of daily living, anxiety and depression. Significant relations were assumed. Convergent validity was investigated by correlating the MFI scales with a visual analogue scale measuring fatigue and with a fatigue-scale derived from the Rotterdam Symptom Checklist. Results support the validity of the MFI-20. The highly similar results in the Dutch and Scottish sample suggest that the portrayal of fatigue using the MFI-20 is quite robust. PMID:8546913

Matching initial torque with different stimulation parameters influences skeletal muscle fatigue.

PubMed

Bickel, C Scott; Gregory, Chris M; Azuero, Andres

2012-01-01

A fundamental barrier to using electrical stimulation in the clinical setting is an inability to maintain torque production secondary to muscle fatigue. Electrical stimulation parameters are manipulated to influence muscle torque production, and they may also influence fatigability during repetitive stimulation. Our purpose was to determine the response of the quadriceps femoris to three different fatigue protocols using the same initial torque obtained by altering stimulator parameter settings. Participants underwent fatigue protocols in which either pulse frequency (lowHz), pulse duration (lowPD), or voltage (lowV) was manipulated to obtain an initial torque that equaled 25% of maximum voluntary isometric contraction. Muscle soreness was reported on a visual analog scale 48 h after each fatigue test. The lowHz protocol resulted in the least fatigue (25% +/- 14%); the lowPD (50% +/- 13%) and lowV (48% +/- 14%) protocols had similar levels of fatigue. The lowHz protocol resulted in significantly less muscle soreness than the higher frequency protocols. Stimulation protocols that use a lower frequency coupled with long pulse durations and high voltages result in lesser amounts of muscle fatigue and perceived soreness. The identification of optimal stimulation patterns to maximize muscle performance will reduce the effect of muscle fatigue and potentially improve clinical efficacy.

Psychometric evaluation of the Multidimensional Assessment of Fatigue scale for use with pregnant and postpartum women.

PubMed

Fairbrother, Nichole; Hutton, Eileen K; Stoll, Kathrin; Hall, Wendy; Kluka, Sandy

2008-06-01

Although fatigue is a common experience for pregnant women and new mothers, few measures of fatigue have been validated for use with this population. To address this gap, the authors assessed psychometric properties of the Multidimensional Assessment of Fatigue (MAF) scale, which was used in 2 independent samples of pregnant women. Results indicated that the psychometric properties of the scale were very similar across samples and time points. The scale possesses a high level of internal consistency, has good convergent validity with measures of sleep quality and depression, and discriminates well from a measure of social support. Contrary to previous evaluations of the MAF, data strongly suggest that the scale represents a unidimensional construct best represented by a single factor. Results indicate that the MAF is a useful measure of fatigue among pregnant and postpartum women.

Psychometric Evaluation of the Multidimensional Assessment of Fatigue Scale for Use with Pregnant and Postpartum Women

ERIC Educational Resources Information Center

Fairbrother, Nichole; Hutton, Eileen K.; Stoll, Kathrin; Hall, Wendy; Kluka, Sandy

2008-01-01

Although fatigue is a common experience for pregnant women and new mothers, few measures of fatigue have been validated for use with this population. To address this gap, the authors assessed psychometric properties of the Multidimensional Assessment of Fatigue (MAF) scale, which was used in 2 independent samples of pregnant women. Results…

Validity and everyday clinical applicability of lumbar muscle fatigue assessment methods in patients with chronic non-specific low back pain: a systematic review.

PubMed

Villafañe, Jorge H; Gobbo, Massimiliano; Peranzoni, Matteo; Naik, Ganesh; Imperio, Grace; Cleland, Joshua A; Negrini, Stefano

2016-09-01

This systematic literature review aimed at examining the validity and applicability in everyday clinical rehabilitation practise of methods for the assessment of back muscle fatiguability in patients with chronic non-specific low back pain (CNSLBP). Extensive research was performed in MEDLINE, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Embase, Physiotherapy Evidence Database (PEDro) and Cochrane Central Register of Controlled Trials (CENTRAL) databases from their inception to September 2014. Potentially relevant articles were also manually looked for in the reference lists of the identified publications. Studies examining lumbar muscle fatigue in people with CNSLBP were selected. Two reviewers independently selected the articles, carried out the study quality assessment and extracted the results. A modified Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) scale was used to evaluate the scientific rigour of the selected works. Twenty-four studies fulfilled the selection criteria and were included in the systematic review. We found conflicting data regarding the validity of methods used to examine back muscle fatigue. The Biering-Sorensen test, performed in conjunction with surface electromyography spectral analysis, turned out to be the most widely used and comparatively, the most optimal modality currently available to assess objective back muscle fatigue in daily clinical practise, even though critical limitations are discussed. Future research should address the identification of an advanced method for lower back fatigue assessment in patients with CNSLBP which, eventually, might provide physical therapists with an objective and reliable test usable in everyday clinical practise. Implications for Rehabilitation Despite its limitations, the Biering-Sorensen test is currently the most used, convenient and easily available fatiguing test for lumbar muscles. To increase validity and reliability of the Biering-Sorensen test, concomitant activation of synergistic muscles should be taken into account. Pooled mean frequency and half-width of the spectrum are currently the most valid electromyographic parameters to assess fatigue in chronic non-specific low back pain. Body mass index, grading of pain and level of disability of the study population should be reported to enhance research quality.

Sleep Quality and Vigilance Differ Among Inpatient Nurses Based on the Unit Setting and Shift Worked.

PubMed

Surani, Salim; Hesselbacher, Sean; Guntupalli, Bharat; Surani, Sara; Subramanian, Shyam

2015-12-01

Sleepiness in nurses has been shown to impact patient care and safety. The objectives of this study are to measure sleep quality, sleepiness, fatigue, and vigilance in inpatient nurses and to assess how setting (intensive care unit versus the general floor) and shift worked (day versus night) affect these measures. Nurses from both the ICU and floor were included in the study. Participants completed questionnaires assessing self-reported sleep quality (Pittsburgh Sleep Quality Index, PSQI), sleepiness (Stanford Sleepiness Scale and Epworth Sleepiness Scale, ESS), and fatigue (Fatigue Severity Scale, FSS). Vigilance was measured by means of the psychomotor vigilance test (PVT), before and after a 12-hour duty shift. The ESS was abnormal in 22% of all nurses, the FSS was abnormal in 33%, and the global PSQI was abnormal in 63%. More ICU nurses than floor nurses reported abnormal sleep quality (component 5) on the PSQI. Sleep medication use (PSQI component 6) was higher in night shift nurses. The FSS was greater in night shift nurses. On preshift PVT testing, day-shift nurses overall provided faster mean reaction time (RT) than night-shift nurses. ICU nurses working the day shift made more than twice as many total errors and false starts than day shift floor nurses. Floor nurses demonstrated a significant decrease from preshift to postshift in the mean of the fastest 10% RT. Our data indicate that a significant number of inpatient nurses have impaired sleep quality, excessive sleepiness, and abnormal fatigue, which may place them at a greater risk of making medical errors and harming patients; these problems are especially pronounced in night shift workers. PVT results were inconsistent, but floor and day shift nurses performed better on some tasks than ICU and night shift nurses.

A Cycling Movement Based System for Real-Time Muscle Fatigue and Cardiac Stress Monitoring and Analysis

PubMed Central

Chen, Szi-Wen; Liaw, Jiunn-Woei; Chang, Ya-Ju; Chan, Hsiao-Lung; Chiu, Li-Yu

2015-01-01

In this study, we defined a new parameter, referred to as the cardiac stress index (CSI), using a nonlinear detrended fluctuation analysis (DFA) of heart rate (HR). Our study aimed to incorporate the CSI into a cycling based fatigue monitoring system developed in our previous work so the muscle fatigue and cardiac stress can be both continuously and quantitatively assessed for subjects undergoing the cycling exercise. By collecting electrocardiogram (ECG) signals, the DFA scaling exponent α was evaluated on the RR time series extracted from a windowed ECG segment. We then obtained the running estimate of α by shifting a one-minute window by a step of 20 seconds so the CSI, defined as the percentage of all the less-than-one α values, can be synchronously updated every 20 seconds. Since the rating of perceived exertion (RPE) scale is considered as a convenient index which is commonly used to monitor subjective perceived exercise intensity, we then related the Borg RPE scale value to the CSI in order to investigate and quantitatively characterize the relationship between exercise-induced fatigue and cardiac stress. Twenty-two young healthy participants were recruited in our study. Each participant was asked to maintain a fixed pedaling speed at a constant load during the cycling exercise. Experimental results showed that a decrease in DFA scaling exponent α or an increase in CSI was observed during the exercise. In addition, the Borg RPE scale and CSI were positively correlated, suggesting that the factors due to cardiac stress might also contribute to fatigue state during physical exercise. Since the CSI can effectively quantify the cardiac stress status during physical exercise, our system may be used in sports medicine, or used by cardiologists who carried out stress tests for monitoring heart condition in patients with heart diseases. PMID:26115515

The Effect of Fatigue and Fatigue Intensity on Exercise Tolerance in Moderate COPD.

PubMed

Al-Shair, Khaled; Kolsum, Umme; Singh, Dave; Vestbo, Jørgen

2016-12-01

Fatigue is one of the most disabling symptoms in COPD, but little is known about the impact of fatigue on functional disability. We explored the impact of fatigue and fatigue intensity on exercise tolerance after adjusting for other factors using multivariate analysis and compared it to that of dyspnoea. A total of 119 patients with mainly moderate-severe stable COPD (38 % women, mean age 66 years) were enrolled. We used the Medical Research Council dyspnoea scores (MRC), Manchester COPD fatigue scale (MCFS) and its three dimensions, Borg scales for fatigue and dyspnoea, six-minute walk distance (6MWD), St George's Respiratory Questionnaire, the BODE index, and the Centre for Epidemiological Study on Depression scale (CES-D), and we measured spirometry, blood gases, systemic inflammatory markers and fat-free mass index (FFMI). Fatigue measured using the MCFS was associated with 6MWD and explained 22 % of the variability in 6MWD (p < 0.001). Fatigue remained associated with 6MWD after adjusting for MRC dyspnoea, FFMI and FEV 1 , FVC, PaO 2 , PaCO 2 , CES-D, TNF-alpha, smoking status, age and gender. We found that 33, 50 and 23 % of patients reported an increase by 2 scores on Borg scales for fatigue, dyspnoea or both at the end of the 6MWT. Fatigue scores (both before and after the 6MWT) were negatively correlated with 6MWD after adjusting for FEV 1 , FFMI, CES-D score and age (p = 0.007 and 0.001, respectively). In moderate stable COPD, fatigue may be a central driver of functional disability, to the same extent as dyspnoea.

Validation of the Modified Fatigue Impact Scale in mild to moderate traumatic brain injury.

PubMed

Schiehser, Dawn M; Delano-Wood, Lisa; Jak, Amy J; Matthews, Scott C; Simmons, Alan N; Jacobson, Mark W; Filoteo, J Vincent; Bondi, Mark W; Orff, Henry J; Liu, Lin

2015-01-01

To evaluate the validity of the Modified Fatigue Impact Scale (MFIS) in veterans with a history of mild to moderate traumatic brain injury (TBI). Veterans (N = 106) with mild (92%) or moderate (8%) TBI. Veterans Administration Health System. Factor structure, internal consistency, convergent validity, sensitivity, and specificity of the MFIS were examined. Principal component analysis identified 2 viable MFIS factors: a Cognitive subscale and a Physical/Activities subscale. Item analysis revealed high internal consistency of the MFIS Total scale and subscale items. Strong convergent validity of the MFIS scales was established with 2 Beck Depression Inventory II fatigue items. Receiver operating characteristic curve analysis revealed good to excellent accuracy of the MFIS in classifying fatigued versus nonfatigued individuals. The MFIS is a valid multidimensional measure that can be used to evaluate the impact of fatigue on cognitive and physical functioning in individuals with mild to moderate TBI. The psychometric properties of the MFIS make it useful for evaluating fatigue and provide the potential for improving research on fatigue in this population.

Metabolic Rate and Perceived Exertion of Walking in Older Adults With Idiopathic Chronic Fatigue

PubMed Central

Corbett, Duane B.; Knaggs, Jeffrey D.; Manini, Todd M.

2016-01-01

Abstract Background: Fatigue is a common complaint in older adults, often not associated with underlying medical conditions. The purpose of this study was to investigate metabolic rate (MR) of walking, walking performance, and perception-based exertion during walking in older adults with and without idiopathic chronic fatigue (ICF). Methods: 20 older adults (aged 70.8±4.9 years), reporting 2 SD above normative values of the Functional Assessment of Chronic Illness Therapy-Fatigue scale and without overt health conditions that explained their symptoms, were compared with 25 age-matched older adults (73.2±5.1 years) without fatigue symptoms. Participants walked 400 m at a rapid pace on a 20-m course. On a separate visit, oxygen consumption was measured during treadmill test at standard (40.2 m/min), preferred paces (40–83 m/min) and peak capacity. Ratings of perceived exertion (RPE) were measured at each treadmill stage and after each lap of the 400-m walk test. Results: During the 400-m walk test, individuals with ICF showed lower overall walking speed and reported a steady increase in RPE with no change observed in non-fatigued group (1.63±1.72 vs 0.27±0.68, p < .01). Similar findings on RPE were noted on treadmill test. Gross MR, mass-specific MR, mass-specific net MR, and MR as a percent of peak oxygen consumption of walking were similar between groups during standard, preferred paces and peak capacity on treadmill. Conclusions: This study suggests that ICF in older adults is not related to elevated metabolic cost of walking. Higher RPE without concomitant decreases in performance indicate a potential disconnect between metabolic output and sensations during movement. PMID:27271253

Systematic review of the multidimensional fatigue symptom inventory-short form.

PubMed

Donovan, Kristine A; Stein, Kevin D; Lee, Morgan; Leach, Corinne R; Ilozumba, Onaedo; Jacobsen, Paul B

2015-01-01

Fatigue is a subjective complaint that is believed to be multifactorial in its etiology and multidimensional in its expression. Fatigue may be experienced by individuals in different dimensions as physical, mental, and emotional tiredness. The purposes of this study were to review and characterize the use of the 30-item Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF) in published studies and to evaluate the available evidence for its psychometric properties. A systematic review was conducted to identify published articles reporting results for the MFSI-SF. Data were analyzed to characterize internal consistency reliability of multi-item MFSI-SF scales and test-retest reliability. Correlation coefficients were summarized to characterize concurrent, convergent, and divergent validity. Standardized effect sizes were calculated to characterize the discriminative validity of the MFSI-SF and its sensitivity to change. Seventy articles were identified. Sample sizes reported ranged from 10 to 529 and nearly half consisted exclusively of females. More than half the samples were composed of cancer patients; of those, 59% were breast cancer patients. Mean alpha coefficients for MFSI-SF fatigue subscales ranged from 0.84 for physical fatigue to 0.93 for general fatigue. The MFSI-SF demonstrated moderate test-retest reliability in a small number of studies. Correlations with other fatigue and vitality measures were moderate to large in size and in the expected direction. The MFSI-SF fatigue subscales were positively correlated with measures of distress, depressive, and anxious symptoms. Effect sizes for discriminative validity ranged from medium to large, while effect sizes for sensitivity to change ranged from small to large. Findings demonstrate the positive psychometric properties of the MFSI-SF, provide evidence for its usefulness in medically ill and nonmedically ill individuals, and support its use in future studies.

Fatigue - but not mTBI history, PTSD, or sleep quality - directly contributes to reduced prospective memory performance in Iraq and Afghanistan era Veterans.

PubMed

Rau, Holly K; Hendrickson, Rebecca; Roggenkamp, Hannah C; Peterson, Sarah; Parmenter, Brett; Cook, David G; Peskind, Elaine; Pagulayan, Kathleen F

2017-10-13

Memory problems that affect daily functioning are a frequent complaint among Veterans reporting a history of repetitive mild traumatic brain injury (mTBI), especially in cohorts with comorbid PTSD. Here, we test the degree to which subjective sleep impairment and daytime fatigue account for the association of PTSD and self-reported mTBI history with prospective memory. 82 Veterans with and without personal history of repeated blast-related mTBI during deployment were administered the Clinician Administered PTSD Scale (CAPS), Memory for Intentions Test (MIST), Patient Health Questionnaire-9 (PHQ-9), Neurobehavioral Symptom Inventory (NSI), and the Pittsburgh Sleep Quality Index (PSQI). Relationships between self-reported mTBI, PTSD, self-reported poor sleep and daytime fatigue, and MIST performance were modeled using partial least squares structural equation modeling (PLS-SEM). Reported daytime fatigue was strongly associated with poorer prospective memory performance. Poor subjective sleep quality was strongly and positively associated with reported daytime fatigue, but had no significant direct effect on prospective memory performance. PTSD diagnosis and self-reported mTBI history were only associated with prospective memory via their impact on subjective sleep quality and daytime fatigue. Results suggest that daytime fatigue may be a mediating factor by which both mTBI and PTSD can interfere with prospective memory. Additional attention should be given to complaints of daytime fatigue, independent of subjective sleep quality, in the clinical care of those with a self-reported history of mTBI, and/or PTSD. Further research into whether interventions that decrease daytime fatigue lead to improvement in prospective memory and subjective cognitive functioning is warranted.

Persistent Symptoms and Objectively Measured Balance Performance Among OEF/OIF Veterans With Remote Mild Traumatic Brain Injury.

PubMed

Hebert, Jeffrey R; Forster, Jeri E; Stearns-Yoder, Kelly A; Penzenik, Molly E; Brenner, Lisa A

2018-01-30

To investigate linear relationships between dizziness, fatigue, and depression and posttraumatic stress disorder (PTSD) and objectively measured balance performance in Veterans with remote mild traumatic brain injury (mTBI). Academic laboratory; Veterans Affairs Medical Center. Thirty Veterans (28 men) who served in Iraq/Afghanistan and whose most recent mTBI was sustained more than 6 months prior to enrollment. Cross-sectional, observational trial. The Computerized Dynamic Posturography-Sensory Organization Test (CDP-SOT) and the Community Balance and Mobility (CB&M) scale measured balance. Dizziness (Dizziness Handicap Inventory), fatigue (Modified Fatigue Impact Scale), depression-related symptoms (Beck Depression Inventory-II), and PTSD-related symptoms (PTSD Checklist 5) were also measured. Objectively measured balance, CDP-SOT composite, was impaired (mean score of 67.9). CDP-SOT scores correlated with dizziness (r = -0.53; P = .002), fatigue (r = -0.38; P = .03), depression (r = -0.55; P = .001), and PTSD symptoms (r = -0.53; P = .002). Dizziness, time since most recent mTBI, and PTSD symptoms and depression combined explained significant variability in CDP-SOT scores (R = 0.46; P = .003), as did fatigue depression and PTSD symptoms (R = 0.33; P = .01). Impaired balance was identified among the cohort. Findings suggest that dizziness, fatigue, depression and PTSD, and time since most recent mTBI may influence balance performance. Additional research is needed to identify the potentially interrelated natural histories of these co-occurring symptoms.

Mediators of the effects on fatigue of pragmatic rehabilitation for chronic fatigue syndrome.

PubMed

Wearden, Alison J; Emsley, Richard

2013-10-01

To examine potential mediators of the effect of pragmatic rehabilitation on improvements in fatigue following a randomized controlled trial for patients with chronic fatigue syndrome (CFS/ME) in primary care (IRCTN 74156610). Patients fulfilled the Oxford criteria for CFS. Ninety-five patients were randomized to pragmatic rehabilitation and 100 to general practitioner (GP) treatment as usual. The outcome was the Chalder fatigue scale score (0123 scoring) at end of treatment (20 weeks) and 1-year follow up (70 weeks). First, the effect of treatment on potential mediators was assessed. Then fatigue was regressed on significant mediators, treatment allocation, and baseline measures of fatigue and significant mediators. Reduction in limiting activities at 20 weeks mediated the positive effect of pragmatic rehabilitation on fatigue at 70 weeks (mediated effect size = -2.64, SE = 0.81, p = .001, proportion of effect mediated = 82.0%). Reduction in catastrophizing at 20 weeks mediated the positive effect of pragmatic rehabilitation on fatigue at 70 weeks (mediated effect size = -1.39, SE = 0.61, p = .023, proportion of effect mediated = 43.2%). Reductions in 70-week measures of fear avoidance, embarrassment avoidance, limiting activities, and all-or-nothing behavior all mediated improvement in fatigue at 70 weeks, although the causal direction of these cross-sectional effects cannot be determined. There were no between-group differences on measures of exercise capacity (a timed step test). Improvements in fatigue following pragmatic rehabilitation are related to changes in behavioral responses to and beliefs about fatigue.

Fatigue in Multiple Sclerosis: Is it related to cytokines and hypothalamic-pituitary-adrenal axis?

PubMed

Akcali, Aylin; Zengin, Fatma; Aksoy, Sefika Nur; Zengin, Orhan

2017-07-01

Fatigue is a common symptom of Multiple Sclerosis (MS) that diminishes the quality of life of patients, but its exact mechanism remains poorly understood. There is not a generally adopted scale to determine MS fatigue. Studies that investigated physiopathology of fatigue symptom have shown dysregulation of hypothalamic-pituitaryadrenal (HPA) axis. In the current study, we aimed to compare the results obtained with two separate scales, namely the Fatigue Severity Scale (FSS) and the Neurological Fatigue Index-Multiple Sclerosis (NFI-MS), and assess the relationship between fatigue and serum IL-1β, TNF-α, IL-35, IL-2, IL-10, ACTH, cortisol, α-MSH, β-MSH, γ-MSH and CLIP (Corticotropinlike intermediate lobe peptide) in MS patients categorized as fatigued and non-fatigued on the basis of FSS scores. For the study, a total of 54 (29 females, 25 males) patients diagnosed with RRMS including 26 with fatigue symptom (48.1%), and 26 healthy controls (13 females, 13 males) were enrolled. A FSS score ≥36 was considered as cut-off score to separate fatigued patients from nonfatigued patients. A significant positive correlation was determined between FSS score and NFI-MS scale, NFI-MS 1, NFI-MS 2, NFI-MS 3 and NFI-MS 4 scores. IL-1β, IL-10 and TNF-α levels did not differ between patient and control groups. IL-35 and IL-2 levels were significantly higher among MS patients (p<0.01). However, no difference was observed between fatigued and nonfatigued patients in the cytokines and HPA parameters studied. ACTH, cortisol and α-MSH were significantly higher in MS group (p=0.02, p<0.01 and p<0.01, respectively). CLIP level was significantly low in MS patient group (p<0.01). NFI-MS scale is equally sensitive as FSS scale for assessment of MS fatigue; thus, it may also be widely used to evaluate that symptom. Generally HPA axis is hyperactive in MS patients, but it is not correlated with fatigue in our study. For the first time, levels of CLIP (a type of melanocortin) are studied, and determined to be lower among MS patients. Elevated levels of IL-35 and IL-2 suggest that these cytokines may have a prominent role in MS pathophysiology and can be investigated as potential targets for development of novel therapies. Copyright © 2017 Elsevier B.V. All rights reserved.

Fatigue as a cause, not a consequence of depression and daytime sleepiness: a cross-lagged analysis.

PubMed

Schönberger, Michael; Herrberg, Marlene; Ponsford, Jennie

2014-01-01

To examine the temporal relation between fatigue, depression, and daytime sleepiness after traumatic brain injury. Fatigue is a frequent and disabling consequence of traumatic brain injury (TBI). However, it is unclear whether fatigue is a primary consequence of the structural brain injury or a secondary consequence of injury-related sequelae such as depression and daytime sleepiness. Eighty-eight adults with complicated mild-severe TBI (69% male). Fatigue Severity Scale; depression subscale of the Hospital Anxiety and Depression Scale; Epworth Sleepiness scale at baseline and 6-month follow-up. A cross-lagged path analysis computed within a structural equation modeling framework revealed that fatigue was predictive of depression (β = .20, P < .05) and sleepiness (β = .25, P < .05). However, depression and sleepiness did not predict fatigue (P > .05). The results support the view of fatigue after TBI as "primary fatigue"-that is, a consequence of the structural brain injury rather than a secondary consequence of depression or daytime sleepiness. A rehabilitation approach that assists individuals with brain injury in learning to cope with their neuropsychological and physical limitations in everyday life might attenuate their experience with fatigue.

AB117. An exploration of Australasian genetic counsellors’ attitudes towards compassion fatigue, mindfulness and genetic counselling

PubMed Central

Burgess, Matthew; Tai, Geneieve; Martinek, Nathalie; Menezes, Melody; Delatycki, Martin

2015-01-01

Genetic counselling is a caring profession. It has been known for some time that genetic counsellors are susceptible to clinical burnout and/or compassion fatigue. Recent studies have shown that mindfulness may help health care professionals with their experience of burnout. It is hypothesised that mindful awareness may be useful in ameliorating these symptoms of burnout in genetic counsellors. The present study aims to collect information about the experiences of Australasian genetic counsellors in relation to compassion fatigue and mindfulness. This study is an online questionnaire open to practicing Australasian genetic counsellors. The survey is in three parts. The first part collects demographic information about the genetic counsellor completing the questionnaire. The second part of the survey is the Professional Quality of Life Scale, Compassion Satisfaction and Fatigue Subscales-Revision IV. The final part of the questionnaire is the Mindful Attention Awareness Scale. Both scales are validated. Descriptive analyses will generate frequency data to elicit a description of participants and the responses obtained. Analysis of categorical measures will be undertaken using χ2 (chi-squared) analysis to determine if there are any differences in responses. For continuous variables, differences in means between groups will be assessed using t-tests. Qualitative content analysis (inductive approach) will be utilised to analyse open ended responses. The results of this questionnaire will provide important data about clinical burnout and compassion fatigue among genetic counsellors and will enable recommendations about the use of mindfulness to minimise the impact of these on those in this profession.

Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance.

PubMed

Al-Khudairi, Othman; Hadavinia, Homayoun; Little, Christian; Gillmore, Gavin; Greaves, Peter; Dyer, Kirsten

2017-10-03

In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i) as received blade (ii) when a crack of 200 mm was introduced between the web and the spar cap and (iii) when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM) which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure.

Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance

PubMed Central

Al-Khudairi, Othman; Little, Christian; Gillmore, Gavin; Greaves, Peter; Dyer, Kirsten

2017-01-01

In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i) as received blade (ii) when a crack of 200 mm was introduced between the web and the spar cap and (iii) when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM) which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure. PMID:28972548

Compassion Satisfaction and Compassion Fatigue Among Critical Care Nurses.

PubMed

Sacco, Tara L; Ciurzynski, Susan M; Harvey, Megan Elizabeth; Ingersoll, Gail L

2015-08-01

Although critical care nurses gain satisfaction from providing compassionate care to patients and patients' families, the nurses are also at risk for fatigue. The balance between satisfaction and fatigue is considered professional quality of life. To establish the prevalence of compassion satisfaction and compassion fatigue in adult, pediatric, and neonatal critical care nurses and to describe potential contributing demographic, unit, and organizational characteristics. In a cross-sectional design, nurses were surveyed by using a demographic questionnaire and the Professional Quality of Life Scale to measure levels of compassion fatigue and compassion satisfaction. Nurses (n = 221) reported significant differences in compassion satisfaction and compassion fatigue on the basis of sex, age, educational level, unit, acuity, change in nursing management, and major systems change. Understanding the elements of professional quality of life can have a positive effect on work environment. The relationship between professional quality of life and the standards for a healthy work environment requires further investigation. Once this relationship is fully understood, interventions to improve this balance can be developed and tested. ©2015 American Association of Critical-Care Nurses.

Visual fatigue modeling for stereoscopic video shot based on camera motion

NASA Astrophysics Data System (ADS)

Shi, Guozhong; Sang, Xinzhu; Yu, Xunbo; Liu, Yangdong; Liu, Jing

2014-11-01

As three-dimensional television (3-DTV) and 3-D movie become popular, the discomfort of visual feeling limits further applications of 3D display technology. The cause of visual discomfort from stereoscopic video conflicts between accommodation and convergence, excessive binocular parallax, fast motion of objects and so on. Here, a novel method for evaluating visual fatigue is demonstrated. Influence factors including spatial structure, motion scale and comfortable zone are analyzed. According to the human visual system (HVS), people only need to converge their eyes to the specific objects for static cameras and background. Relative motion should be considered for different camera conditions determining different factor coefficients and weights. Compared with the traditional visual fatigue prediction model, a novel visual fatigue predicting model is presented. Visual fatigue degree is predicted using multiple linear regression method combining with the subjective evaluation. Consequently, each factor can reflect the characteristics of the scene, and the total visual fatigue score can be indicated according to the proposed algorithm. Compared with conventional algorithms which ignored the status of the camera, our approach exhibits reliable performance in terms of correlation with subjective test results.

A Chronic Fatigue Syndrome (CFS) severity score based on case designation criteria.

PubMed

Baraniuk, James N; Adewuyi, Oluwatoyin; Merck, Samantha Jean; Ali, Mushtaq; Ravindran, Murugan K; Timbol, Christian R; Rayhan, Rakib; Zheng, Yin; Le, Uyenphuong; Esteitie, Rania; Petrie, Kristina N

2013-01-01

Chronic Fatigue Syndrome case designation criteria are scored as physicians' subjective, nominal interpretations of patient fatigue, pain (headaches, myalgia, arthralgia, sore throat and lymph nodes), cognitive dysfunction, sleep and exertional exhaustion. Subjects self-reported symptoms using an anchored ordinal scale of 0 (no symptom), 1 (trivial complaints), 2 (mild), 3 (moderate), and 4 (severe). Fatigue of 3 or 4 distinguished "Fatigued" from "Not Fatigued" subjects. The sum of the 8(Sum8) ancillary criteria was tested as a proxy for fatigue. All subjects had history and physical examinations to exclude medical fatigue, and ensure categorization as healthy or CFS subjects. Fatigued subjects were divided into CFS with ≥4 symptoms or Chronic Idiopathic Fatigue (CIF) with ≤3 symptoms. ROC of Sum8 for CFS and Not Fatigued subjects generated a threshold of 14 (specificity=0.934; sensitivity=0.928). CFS (n=256) and CIF (n=55) criteria were refined to include Sum8≥14 and ≤13, respectively. Not Fatigued subjects had highly skewed Sum8 responses. Healthy Controls (HC; n=269) were defined by fatigue≤2 and Sum8≤13. Those with Sum8≥14 were defined as CFS-Like With Insufficient Fatigue Syndrome (CFSLWIFS; n=20). Sum8 and Fatigue were highly correlated (R(2)=0.977; Cronbach's alpha=0.924) indicating an intimate relationship between symptom constructs. Cluster analysis suggested 4 clades each in CFS and HC. Translational utility was inferred from the clustering of proteomics from cerebrospinal fluid. Plotting Fatigue severity versus Sum8 produced an internally consistent classifying system. This is a necessary step for translating symptom profiles into fatigue phenotypes and their pathophysiological mechanisms.

Minimal clinically important difference of the Modified Fatigue Impact Scale in Parkinson's disease.

PubMed

Kluger, Benzi M; Garimella, Sanjana; Garvan, Cynthia

2017-10-01

Fatigue is a common and debilitating symptom of Parkinson's disease (PD) with no evidence-based treatments. While several fatigue scales are partially validated in PD the minimal clinically important difference (MCID) is unknown for any scale but is an important psychometric value to design and interpret therapeutic trials. We thus sought to determine the MCID for the Modified Fatigue Impact Scale (MFIS). This is a secondary data analysis from 94 PD participants in an acupuncture trial for PD fatigue. Standard psychometric approaches were used to establish validity and an anchor-based approach was used to determine the MCID. The MFIS demonstrated good concurrent validity with other outcome measures and high internal consistency. MCIDs values were found to be 13.8, 6.8 and 6.2 for the MFIS total, MFIS cognitive, and MFIS physical subscores respectively. The MFIS is a valid multidimensional measure of fatigue in PD with demonstrable MCID. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reduced DNA methylation and psychopathology following endogenous hypercortisolism - a genome-wide study.

PubMed

Glad, Camilla A M; Andersson-Assarsson, Johanna C; Berglund, Peter; Bergthorsdottir, Ragnhildur; Ragnarsson, Oskar; Johannsson, Gudmundur

2017-03-16

Patients with Cushing's Syndrome (CS) in remission were used as a model to test the hypothesis that long-standing excessive cortisol exposure induces changes in DNA methylation that are associated with persisting neuropsychological consequences. Genome-wide DNA methylation was assessed in 48 women with CS in long-term remission (cases) and 16 controls matched for age, gender and education. The Fatigue impact scale and the comprehensive psychopathological rating scale were used to evaluate fatigue, depression and anxiety. Cases had lower average global DNA methylation than controls (81.2% vs 82.7%; p = 0.002). Four hundred and sixty-one differentially methylated regions, containing 3,246 probes mapping to 337 genes were identified. After adjustment for age and smoking, 731 probes in 236 genes were associated with psychopathology (fatigue, depression and/or anxiety). Twenty-four gene ontology terms were associated with psychopathology; terms related to retinoic acid receptor signalling were the most common (adjusted p = 0.0007). One gene in particular, COL11A2, was associated with fatigue following a false discovery rate correction. Our findings indicate that hypomethylation of FKBP5 and retinoic acid receptor related genes serve a potential mechanistic explanation for long-lasting GC-induced psychopathology.

Self-reported post-exertional fatigue in Gulf War veterans: roles of autonomic testing

PubMed Central

Li, Mian; Xu, Changqing; Yao, Wenguo; Mahan, Clare M.; Kang, Han K.; Sandbrink, Friedhelm; Zhai, Ping; Karasik, Pamela A.

2014-01-01

To determine if objective evidence of autonomic dysfunction exists from a group of Gulf War veterans with self-reported post-exertional fatigue, we evaluated 16 Gulf War ill veterans and 12 Gulf War controls. Participants of the ill group had self- reported, unexplained chronic post-exertional fatigue and the illness symptoms had persisted for years until the current clinical study. The controls had no self-reported post-exertional fatigue either at the time of initial survey nor at the time of the current study. We intended to identify clinical autonomic disorders using autonomic and neurophysiologic testing in the clinical context. We compared the autonomic measures between the 2 groups on cardiovascular function at both baseline and head-up tilt, and sudomotor function. We identified 1 participant with orthostatic hypotension, 1 posture orthostatic tachycardia syndrome, 2 distal small fiber neuropathy, and 1 length dependent distal neuropathy affecting both large and small fiber in the ill group; whereas none of above definable diagnoses was noted in the controls. The ill group had a significantly higher baseline heart rate compared to controls. Compound autonomic scoring scale showed a significant higher score (95% CI of mean: 1.72–2.67) among ill group compared to controls (0.58–1.59). We conclude that objective autonomic testing is necessary for the evaluation of self-reported, unexplained post-exertional fatigue among some Gulf War veterans with multi-symptom illnesses. Our observation that ill veterans with self-reported post-exertional fatigue had objective autonomic measures that were worse than controls warrants validation in a larger clinical series. PMID:24431987

The Effect of Shoulder Muscle Fatigue on Acromiohumeral Distance and Scapular Dyskinesis in Women With Generalized Joint Hypermobility.

PubMed

Alibazi, Razie J; Moghadam, Afsun Nodehi; Cools, Ann M; Bakhshi, Enayatollah; Ahari, Alireza Aziz

2017-12-01

Muscle fatigue is considered to be one cause of shoulder pain, and subjects with generalized joint hypermobility (GJH) are affected more by shoulder pain. The purpose of this study was to examine the effects of muscle fatigue on acromiohumeral distance (AHD) and scapular dyskinesis in women with GJH. Thirty-six asymptomatic participants were assigned to either a GJH (n = 20) or control group (n = 16) using the Beighton scale. Before and after elevation fatigue trials, AHD was measured with ultrasonography at rest and when the arm was in 90° active elevation. A scapular dyskinesis test was used to visually observe alterations in scapular movement. Our results showed that in both groups, the fatigue reduced AHD in the 90° elevation position and increased the presence of scapular dyskinesis; however, no differences were found between the two groups. Although GJH has been identified as a factor for developing musculoskeletal disorders, generalized joint hypermobility did not result in changes to scapular dyskinesis or AHD, even after an elevation fatigue task. More studies are needed to evaluate the effects of muscle fatigue in subjects with GJH and a history of shoulder instability.

Assessment of fatigue in rheumatoid arthritis: a psychometric comparison of single-item, multiitem, and multidimensional measures.

PubMed

Oude Voshaar, Martijn A H; Ten Klooster, Peter M; Bode, Christina; Vonkeman, Harald E; Glas, Cees A W; Jansen, Tim; van Albada-Kuipers, Iet; van Riel, Piet L C M; van de Laar, Mart A F J

2015-03-01

To compare the psychometric functioning of multidimensional disease-specific, multiitem generic, and single-item measures of fatigue in patients with rheumatoid arthritis (RA). Confirmatory factor analysis (CFA) and longitudinal item response theory (IRT) modeling were used to evaluate the measurement structure and local reliability of the Bristol RA Fatigue Multi-Dimensional Questionnaire (BRAF-MDQ), the Medical Outcomes Study Short Form-36 (SF-36) vitality scale, and the BRAF Numerical Rating Scales (BRAF-NRS) in a sample of 588 patients with RA. A 1-factor CFA model yielded a similar fit to a 5-factor model with subscale-specific dimensions, and the items from the different instruments adequately fit the IRT model, suggesting essential unidimensionality in measurement. The SF-36 vitality scale outperformed the BRAF-MDQ at lower levels of fatigue, but was less precise at moderate to higher levels of fatigue. At these levels of fatigue, the living, cognition, and emotion subscales of the BRAF-MDQ provide additional precision. The BRAF-NRS showed a limited measurement range with its highest precision centered on average levels of fatigue. The different instruments appear to access a common underlying domain of fatigue severity, but differ considerably in their measurement precision along the continuum. The SF-36 vitality scale can be used to measure fatigue severity in samples with relatively mild fatigue. For samples expected to have higher levels of fatigue, the multidimensional BRAF-MDQ appears to be a better choice. The BRAF-NRS are not recommended if precise assessment is required, for instance in longitudinal settings.

A systematic review of the scales used for the measurement of cancer-related fatigue (CRF).

PubMed

Minton, O; Stone, P

2009-01-01

Fatigue in cancer is very common and can be experienced at all stages of disease and in survivors. There is no accepted definition of cancer-related fatigue (CRF) and no agreement on how it should be measured. A number of scales have been developed to quantify the phenomenon of CRF. These vary in the quality of psychometric properties, ease of administration, dimensions of CRF covered and extent of use in studies of cancer patients. This review seeks to identify the available tools for measuring CRF and to make recommendations for ongoing research into CRF. A systematic review methodology was used to identify scales that have been validated to measure CRF. The inclusion criteria required the scale to have been validated for use in cancer patients and/or widely used in this population. Scales also had to meet a minimum quality score for inclusion. The reviewers identified 14 scales that met the inclusion criteria. The most commonly used scales and best validated were the Functional Assessment of Cancer Therapy Fatigue (FACT F), the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ C30) (fatigue subscale) and the Fatigue Questionnaire (FQ). Unidimensional scales are the easiest to administer and have been most widely used. The authors recommend the use of the EORTC QLQ C30 fatigue subscale or the FACT F. The FQ gives a multidimensional assessment and has also been widely used. A substantial minority of the scales identified have not been used extensively or sufficiently validated in cancer patients and cannot be recommended for routine use without further validation.

Full-scale fatigue tests of CX-100 wind turbine blades. Part I: testing

NASA Astrophysics Data System (ADS)

Farinholt, Kevin M.; Taylor, Stuart G.; Park, Gyuhae; Ammerman, Curtt M.

2012-04-01

This paper overviews the test setup and experimental methods for structural health monitoring (SHM) of two 9-meter CX-100 wind turbine blades that underwent fatigue loading at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC). The first blade was a pristine blade, which was manufactured to standard specifications for the CX-100 design. The second blade was manufactured for the University of Massachusetts, Lowell with intentional simulated defects within the fabric layup. Each blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. The blades underwent harmonic excitation at their first natural frequency using the Universal Resonant Excitation (UREX) system at NREL. Blades were initially excited at 25% of their design load, and then with steadily increasing loads until each blade reached failure. Data from the sensors were collected between and during fatigue loading sessions. The data were measured over multi-scale frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed at Los Alamos National Laboratory (LANL). The hardware systems were evaluated for their aptness in data collection for effective application of SHM methods to the blades. The results of this assessment will inform the selection of acquisition hardware and sensor types to be deployed on a CX-100 flight test to be conducted in collaboration with Sandia National Laboratory at the U.S. Department of Agriculture's (USDA) Conservation and Production Research Laboratory (CPRL) in Bushland, Texas.

Uphill and Downhill Walking in Multiple Sclerosis

PubMed Central

Samaei, Afshin; Hajihasani, Abdolhamid; Fatemi, Elham; Motaharinezhad, Fatemeh

2016-01-01

Background: Various exercise protocols have been recommended for patients with multiple sclerosis (MS). We investigated the effects of uphill and downhill walking exercise on mobility, functional activities, and muscle strength in MS patients. Methods: Thirty-four MS patients were randomly allocated to either the downhill or uphill treadmill walking group for 12 sessions (3 times/wk) of 30 minutes' walking on a 10% negative slope (n = 17) or a 10% positive slope (n = 17), respectively. Measurements were taken before and after the intervention and after 4-week follow-up and included fatigue by Modified Fatigue Impact Scale; mobility by Modified Rivermead Mobility Index; disability by Guy's Neurological Disability Scale; functional activities by 2-Minute Walk Test, Timed 25-Foot Walk test, and Timed Up and Go test; balance indices by Biodex Balance System; and quadriceps and hamstring isometric muscles by torque of left and right knee joints. Analysis of variance with repeated measures was used to investigate the intervention effects on the measurements. Results: After the intervention, significant improvement was found in the downhill group versus the uphill group in terms of fatigue, mobility, and disability indices; functional activities; balance indices; and quadriceps isometric torque (P < .05). The results were stable at 4-week follow-up. Conclusions: Downhill walking on a treadmill may improve muscle performance, functional activity, and balance control in MS patients. These findings support the idea of using eccentric exercise training in MS rehabilitation protocols. PMID:26917996

The Prediction of ADL and IADL Disability Using Six Physical Indicators of Frailty: A Longitudinal Study in the Netherlands

PubMed Central

Gobbens, Robbert J. J.; van Assen, Marcel A. L. M.

2014-01-01

Frailty is a predictor of disability. A proper understanding of the contribution of individual indicators of frailty in the prediction of disability is a requisite for preventive interventions. The aim of this study was to determine the predictive power of the individual physical frailty indicators: gait speed, physical activity, hand grip strength, Body Mass Index (BMI), fatigue, and balance, for ADL and IADL disability. The sample consisted of 505 community-dwelling persons (≥75 years, response rate 35.1%). Respondents first participated between November 2007 and June 2008, and a subset of all respondents participated again one year later (N = 264, 52.3% response rate). ADL and IADL disability were assessed by the Groningen Activity Restriction Scale. BMI was assessed by self-report, and the other physical frailty indicators were assessed with the TUG test (gait speed), the LAPAQ (physical activity), a hand grip strength test, the SFQ (fatigue), and the Four-test balance scale. All six physical frailty indicators were associated with ADL and IADL disability. After controlling for previous disability, sociodemographic characteristics, self-perceived lifestyle, and chronic diseases, only gait speed was predictive of both ADL and IADL disability, whereas there was a small effect of fatigue on IADL disability. Hence, these physical frailty indicators should be included in frailty assessment when predicting future disability. PMID:24782894

BEMER Therapy Combined with Physiotherapy in Patients with Musculoskeletal Diseases: A Randomised, Controlled Double Blind Follow-Up Pilot Study

PubMed Central

Gyulai, Franciska; Rába, Katalin; Baranyai, Ildikó; Berkes, Enikő; Bender, Tamás

2015-01-01

Background. This study evaluates the effect of adjuvant BEMER therapy in patients with knee arthrosis and chronic low back pain in a randomized double blind design. Methods. A total of 50 patients with chronic low back pain and 50 patients with osteoarthritis of knee took part in this study and were randomized into 4 groups. Hospitalized patients received a standardized physiotherapy package for 3 weeks followed by BEMER therapy or placebo. Results. In patients with low back pain, the comparison of the results obtained at the first and second visit showed a significant improvement in resting VAS scores and Fatigue Scale scores. The Oswestry scores and Quality of Life Scale scores showed no change. In patients with knee arthrosis, the comparison of the first and second measurements showed no significant improvement in the abovementioned parameters, while the comparison of the first and third scores revealed a significant improvement in the Fatigue Scale scores and in the vitality test on the Quality of Life Scale. Conclusions. Our study showed that BEMER physical vascular therapy reduced pain and fatigue in the short term in patients with chronic low back pain, while long-term therapy appears to be beneficial in patients with osteoarthritis of knee. PMID:26078768

Reliability and validity of the PedsQL™ Multidimensional Fatigue Scale in Japan.

PubMed

Kobayashi, Kyoko; Okano, Yoshiyuki; Hohashi, Naohiro

2011-09-01

To examine the reliability and validity of the Japanese-language version of the PedsQL™ Multidimensional Fatigue Scale and to investigate the agreement between child self-reported fatigue and parent proxy-reported fatigue. The Japanese-language version of the PedsQL™ Multidimensional Fatigue Scale was administered to 652 preschoolers and schoolchildren aged 5-12 and their parents, and to 91 parents of preschool children aged 1-4. Internal consistency reliability was 0.62-0.87 for children and 0.81-0.93 for parents. Known-group validity was examined between a group of healthy samples (n = 530) and chronic condition sample (n = 102); the chronically ill group reported a significantly higher perceived fatigue problem. Correlations between child self- and parent proxy reports ranged from poor to fair. In subgroups identified by cluster analysis based on child self-reported scores, the greatest agreement between child and parent reports was seen in the good HRQOL group, while the least occurred in the poor HRQOL group. The parents overestimated their child's fatigue more when the child's HRQOL was low. The Japanese-language version of the PedsQL™ Multidimensional Fatigue Scale demonstrated good reliability and validity and could be useful in evaluating Japanese children in school and health care settings.

Descriptive study of burnout, compassion fatigue and compassion satisfaction in undergraduate nursing students at a tertiary education institution in KwaZulu-Natal.

PubMed

Mathias, Christina T; Wentzel, Dorien L

2017-09-22

Studies have investigated burnout and compassion fatigue among nurses and effects in the nursing profession. However, there are limited investigations of burnout and compassion fatigue among undergraduate nursing students in South Africa, as nursing students may experience distressful situations during their nursing education course, which may have an impact during their training and in their profession as they graduate. The purpose of this descriptive study was to describe compassion satisfaction, compassion fatigue and burnout among undergraduate nursing students at a tertiary nursing institution. A quantitative descriptive study was conducted to describe compassion satisfaction, compassion fatigue and burnout among undergraduate nursing students at a tertiary nursing institution in KwaZulu-Natal. Convenience sampling was used. Sixty-seven undergraduate students (26 third-year and 41 fourth-year nursing students) took the self-test Professional Quality of Life Scale (ProQOL). The study results indicate that undergraduate students experienced average levels of compassion fatigue, burnout and compassion satisfaction. As shown in the study, some of the undergraduate students are experiencing compassion fatigue and burnout, associated with relieving suffering of others. Therefore, knowledge of compassion fatigue and burnout and the coping strategies should be part of nursing training.

Relationship between cognitive functions and prevalence of fatigue in elementary and junior high school students.

PubMed

Mizuno, Kei; Tanaka, Masaaki; Fukuda, Sanae; Imai-Matsumura, Kyoko; Watanabe, Yasuyoshi

2011-06-01

Fatigue is a common complaint among elementary and junior high school students, and is related to poor academic performance. Since grade-dependent development of cognitive functions also influences academic performance, we attempted to determine whether cognitive functions were associated with the prevalence of fatigue. Participants were 148 elementary school students from 4th- to 6th-grades and 152 junior high school students from 7th- to 9th-grades. Participants completed a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale) and paper-and-pencil and computerized cognitive tests which could evaluate the abilities of motor processing, immediate, delayed and working memory, selective, divided and alternative attention, retrieve learned material, and spatial construction. We found that in multivariate logistic regression analyses adjusted for grade and gender, slow motor processing was positively correlated with the prevalence of fatigue in the elementary school students and decreases in working memory and divided and alternative attention processing were positively correlated with the prevalence of fatigue in the junior high school students. The grade-dependent development of cognitive function influences the severity of fatigue in elementary and junior high school students. Copyright © 2010 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

The Nottingham Fatigue After Stroke (NotFAST) study: results from follow-up six months after stroke.

PubMed

Hawkins, Louise; Lincoln, Nadina B; Sprigg, Nikola; Ward, Nick S; Mistri, Amit; Tyrrell, Pippa; Worthington, Esme; Drummond, Avril

2017-12-01

Background Post-stroke fatigue is common and disabling. Objectives The aim of NotFAST was to examine factors associated with fatigue in stroke survivors without depression, six months after stroke. Methods Participants were recruited from four UK stroke units. Those with high levels of depressive symptoms (score ≥7 on Brief Assessment Schedule Depression Cards) or aphasia were excluded. Follow-up assessment was conducted at six months after stroke. They were assessed on the Fatigue Severity Scale, Rivermead Mobility Index, Nottingham Extended Activities of Daily Living scale, Barthel Index, Beck Anxiety Index, Brief Assessment Schedule Depression Cards, Impact of Event Scale-Revised, and Sleep Hygiene Index. Results Of the 371 participants recruited, 263 (71%) were contacted at six months after stroke and 213 (57%) returned questionnaires. Approximately half (n = 109, 51%) reported fatigue at six months. Of those reporting fatigue initially (n = 88), 61 (69%) continued to report fatigue. 'De novo' (new) fatigue was reported by 48 (38%) of those not fatigued initially. Lower Nottingham Extended Activities of Daily Living scores and higher Beck Anxiety Index scores were independently associated with fatigue at six months. Conclusions Half the stroke survivors reported fatigue at six months post-stroke. Reduced independence in activities of daily living and higher anxiety levels were associated with the level of fatigue. Persistent and delayed onset fatigue may affect independence and participation in rehabilitation, and these findings should be used to inform the development of appropriate interventions.

The Relationships Between Fatigue, Quality of Life, and Family Impact Among Children With Special Health Care Needs

PubMed Central

Anderson, Mary; Gandhi, Pranav; Tuli, Sanjeev; Krull, Kevin; Lai, Jin-Shei; Nackashi, John; Shenkman, Elizabeth

2013-01-01

Objective To examine the relationships among pediatric fatigue, health-related quality of life (HRQOL), and family impact among children with special health care needs (CSHCNs), specifically whether HRQOL mediates the influence of fatigue on family impact. Methods 266 caregivers of CSHCNs were studied. The Pediatric Quality of Life Inventory Multidimensional Fatigue Scale, Pediatric Quality of Life Inventory Generic Scale, and Impact on Family Scale were used to measure fatigue, HRQOL, and family impact, respectively. Linear regressions were used to analyze the designated relationships; path analyses were performed to quantify the mediating effects of HRQOL on fatigue–family impact relationship. Results Although greater fatigue was associated with family impact (p < .05), the association was not significant after accounting for HRQOL. Path analyses indicated the direct effect of fatigue on family impact was not significant (p > .05), whereas physical and emotional functioning significantly mediated the fatigue–family impact relationship (p < .001). Conclusion Fatigue is related to family impact among CSHCNs, acting through the impairment in HRQOL. PMID:23584707

The minimally important difference for the fatigue visual analog scale in patients with rheumatoid arthritis followed in an academic clinical practice.

PubMed

Khanna, Dinesh; Pope, Janet E; Khanna, Puja P; Maloney, Michelle; Samedi, Nooshin; Norrie, Debbie; Ouimet, Gillian; Hays, Ron D

2008-12-01

To estimate the minimally important difference (MID) for a fatigue visual analog scale (VAS) using patient-reported anchors (fatigue, pain, and overall health). Patients with rheumatoid arthritis (RA; n = 307) had 2 clinic visits at a median of 5.9 months apart. They completed a fatigue VAS (0-10 scale) and the retrospective anchor items, "How would you describe your overall fatigue/pain/overall health since the last visit?" with response options: Much worsened, Somewhat worsened, Same, Somewhat better, or Much better. The fatigue anchor was used for primary analysis and the pain/overall health anchors for sensitivity analyses. The minimally changed group was defined by those reporting they were somewhat better or somewhat worsened. The mean [standard deviation (SD)] age was 59.4 (13.2) years, disease duration was 14.1 (11.5) years, and 83% of patients were women. The baseline mean (SD) Health Assessment Questionnaire-Disability Index score was 0.84 (0.75). The baseline fatigue VAS score was 4.2 (2.9) and at followup was 4.3 (2.8) [mean change of -0.07 (2.5); p = not significant]. The fatigue change score (0-10 scale) for Somewhat better and Somewhat worsened for the fatigue anchor averaged -1.12 and 1.26, respectively. Using the pain anchor, the fatigue change score for Somewhat better and Somewhat worsened averaged -0.87 and 1.13; and using the global anchor, the fatigue change score for Somewhat better and Somewhat worsened averaged -0.82 and 1.17, respectively. Effect size estimates using 3 anchors were small for the Somewhat better (range 0.27-0.39) and Somewhat worsened (0.40-0.44) groups, but larger than for the no-change group (0.03-0.08). The MID for fatigue VAS is between -0.82 for -1.12 for improvement and is 1.13 to 1.26 for worsening on a 0-10 scale in a large RA clinical practice, and is similar to that seen in RA clinical trials. This information can aid in interpreting fatigue VAS in day-to-day care in clinical practice.

Sleep inertia during a simulated 6-h on/6-h off fixed split duty schedule.

PubMed

Hilditch, Cassie J; Short, Michelle; Van Dongen, Hans P A; Centofanti, Stephanie A; Dorrian, Jillian; Kohler, Mark; Banks, Siobhan

Sleep inertia is a safety concern for shift workers returning to work soon after waking up. Split duty schedules offer an alternative to longer shift periods, but introduce additional wake-ups and may therefore increase risk of sleep inertia. This study investigated sleep inertia across a split duty schedule. Sixteen participants (age range 21-36 years; 10 females) participated in a 9-day laboratory study with two baseline nights (10 h time in bed, [TIB]), four 24-h periods of a 6-h on/6-h off split duty schedule (5-h TIB in off period; 10-h TIB per 24 h) and two recovery nights. Two complementary rosters were evaluated, with the timing of sleep and wake alternating between the two rosters (2 am/2 pm wake-up roster versus 8 am/8 pm wake-up roster). At 2, 17, 32 and 47 min after scheduled awakening, participants completed an 8-min inertia test bout, which included a 3-min psychomotor vigilance test (PVT-B), a 3-min Digit-Symbol Substitution Task (DSST), the Karolinska Sleepiness Scale (KSS), and the Samn-Perelli Fatigue Scale (SP-Fatigue). Further testing occurred every 2 h during scheduled wakefulness. Performance was consistently degraded and subjective sleepiness/fatigue was consistently increased during the inertia testing period as compared to other testing times. Morning wake-ups (2 am and 8 am) were associated with higher levels of sleep inertia than later wake-ups (2 pm and 8 pm). These results suggest that split duty workers should recognise the potential for sleep inertia after waking, especially during the morning hours.

Fatigue in Type 2 Diabetes: Impact on Quality of Life and Predictors.

PubMed

Singh, Rupali; Teel, Cynthia; Sabus, Carla; McGinnis, Patricia; Kluding, Patricia

2016-01-01

Fatigue is a persistent symptom, impacting quality of life (QoL) and functional status in people with type 2 diabetes, yet the symptom of fatigue has not been fully explored. The purpose of this study was to explore the relationship between fatigue, QoL functional status and to investigate the predictors of fatigue. These possible predictors included body mass index (BMI), Hemoglobin A1C (HbA1C), sleep quality, pain, number of complications from diabetes, years since diagnosis and depression. Forty-eight individuals with type 2 diabetes (22 females, 26 males; 59.66±7.24 years of age; 10.45 ±7.38 years since diagnosis) participated in the study. Fatigue was assessed by using Multidimensional Fatigue Inventory (MFI-20). Other outcomes included: QoL (Audit of Diabetes Dependent QoL), and functional status (6 minute walk test), BMI, HbA1c, sleep (Pittsburg sleep quality index, PSQI), pain (Visual Analog Scale), number of complications, years since diagnosis, and depression (Beck's depression Inventory-2). The Pearson correlation analysis followed by multivariable linear regression model was used. Fatigue was negatively related to quality of life and functional status. Multivariable linear regression analysis revealed sleep, pain and BMI as the independent predictors of fatigue signaling the presence of physiological (sleep, pain, BMI) phenomenon that could undermine health outcomes.

Fatigue in Type 2 Diabetes: Impact on Quality of Life and Predictors

PubMed Central

Teel, Cynthia; Sabus, Carla; McGinnis, Patricia; Kluding, Patricia

2016-01-01

Fatigue is a persistent symptom, impacting quality of life (QoL) and functional status in people with type 2 diabetes, yet the symptom of fatigue has not been fully explored. The purpose of this study was to explore the relationship between fatigue, QoL functional status and to investigate the predictors of fatigue. These possible predictors included body mass index (BMI), Hemoglobin A1C (HbA1C), sleep quality, pain, number of complications from diabetes, years since diagnosis and depression. Forty-eight individuals with type 2 diabetes (22 females, 26 males; 59.66±7.24 years of age; 10.45 ±7.38 years since diagnosis) participated in the study. Fatigue was assessed by using Multidimensional Fatigue Inventory (MFI-20). Other outcomes included: QoL (Audit of Diabetes Dependent QoL), and functional status (6 minute walk test), BMI, HbA1c, sleep (Pittsburg sleep quality index, PSQI), pain (Visual Analog Scale), number of complications, years since diagnosis, and depression (Beck’s depression Inventory-2). The Pearson correlation analysis followed by multivariable linear regression model was used. Fatigue was negatively related to quality of life and functional status. Multivariable linear regression analysis revealed sleep, pain and BMI as the independent predictors of fatigue signaling the presence of physiological (sleep, pain, BMI) phenomenon that could undermine health outcomes. PMID:27824886

Effects of Pilates exercises on sensory interaction, postural control and fatigue in patients with multiple sclerosis.

PubMed

Soysal Tomruk, Melda; Uz, Muhammed Zahid; Kara, Bilge; İdiman, Egemen

2016-05-01

Decreased postural control, sensory integration deficits and fatigue are important problems that cause functional impairments in patients with multiple sclerosis (pwMS). To examine the effect of modified clinical Pilates exercises on sensory interaction and balance, postural control and fatigue in pwMS. Eleven patients with multiple sclerosis and 12 healthy matched controls were recruited in this study. Limits of stability and postural stability tests were used to evaluate postural control by Biodex Balance System and sensory interaction assessed. Fatigue was assessed by Modified Fatigue Impact Scale. Pilates exercises were applied two times a week for 10 weeks and measurements were repeated to pwMS after exercise training. Postural control and fatigue (except psychosocial parameter) of pwMS were significantly worser than healthy controls (p<0.05). Significant improvements occurred in sensory interaction (eyes open, foam surface) and total, physical and cognitive scores of fatigue after 10-week modified clinical Pilates training (p<0.05). No significant changes were detected in postural control after the pilates exercises (p>0.05). Ten-week Pilates training is effective to improve sensory interaction and to decrease fatigue. Pilates exercises can be applied safely in ambulatory pwMS for enhance sensory interaction and balance and combat fatigue. More investigations are needed. Copyright © 2016 Elsevier B.V. All rights reserved.

Analytical Methodology for Predicting the Onset of Widespread Fatigue Damage in Fuselage Structure

NASA Technical Reports Server (NTRS)

Harris, Charles E.; Newman, James C., Jr.; Piascik, Robert S.; Starnes, James H., Jr.

1996-01-01

NASA has developed a comprehensive analytical methodology for predicting the onset of widespread fatigue damage in fuselage structure. The determination of the number of flights and operational hours of aircraft service life that are related to the onset of widespread fatigue damage includes analyses for crack initiation, fatigue crack growth, and residual strength. Therefore, the computational capability required to predict analytically the onset of widespread fatigue damage must be able to represent a wide range of crack sizes from the material (microscale) level to the global structural-scale level. NASA studies indicate that the fatigue crack behavior in aircraft structure can be represented conveniently by the following three analysis scales: small three-dimensional cracks at the microscale level, through-the-thickness two-dimensional cracks at the local structural level, and long cracks at the global structural level. The computational requirements for each of these three analysis scales are described in this paper.

Stimulated peripheral production of interferon-gamma is related to fatigue and depression in multiple sclerosis.

PubMed

Pokryszko-Dragan, A; Frydecka, I; Kosmaczewska, A; Ciszak, L; Bilińska, M; Gruszka, E; Podemski, R; Frydecka, D

2012-10-01

The aim of the study was to evaluate the stimulated production of interferon-gamma (IFNγ) by peripheral CD3+CD4+ T lymphocytes in patients with multiple sclerosis (MS) with regard to the degree of fatigue, and to investigate relationships between immunological parameters, level of depression and clinical variables. Forty MS patients (30 women, 10 men, aged 22-60 years): 20 fatigued and 20 non-fatigued were involved in the study. Fatigue was evaluated using the Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS), depression level - using Beck Depression Inventory (BDI). Production of IFNγ by stimulated peripheral blood CD3+CD4+ T lymphocytes, assessed using flow cytometry, was compared between MS patients with different levels of fatigue and controls. Correlations were searched out between immunological findings and BDI, age, duration and course of MS, relapse rate, disability (assessed in Expanded Disability Status Scale - EDSS) and its progression. Stimulated production of IFNγ by CD3+CD4+ T lymphocytes was higher in severely fatigued patients in comparison with non-fatigued ones and controls, tended to correlate with FSS and MFIS, and correlated with BDI. No relationships were found between immunological findings and disease-related variables. Stimulated production of IFNγ by peripheral CD3+CD4+ T lymphocytes is related to fatigue and depression in MS patients. Copyright © 2012 Elsevier B.V. All rights reserved.

Fatigue correlates with the decrease in parasympathetic sinus modulation induced by a cognitive challenge

PubMed Central

2014-01-01

Background It is known that enhancement of sympathetic nerve activity based on a decrease in parasympathetic nerve activity is associated with fatigue induced by mental tasks lasting more than 30 min. However, to measure autonomic nerve function and assess fatigue levels in both clinical and industrial settings, shorter experimental durations and more sensitive measurement methods are needed. The aim of the present study was to establish an improved method for inducing fatigue and evaluating the association between it and autonomic nerve activity. Methods Twenty-eight healthy female college students participated in the study. We used a kana pick-out test (KPT) as a brief verbal cognitive task and recorded electrocardiography (ECG) to measure autonomic nerve activity. The experimental design consisted of a 16-min period of ECG: A pre-task resting state with eyes open for 3 min and eyes closed for 3 min, the 4-min KPT, and a post-task resting state with eyes open for 3 min and eyes closed for 3 min. Results Baseline fatigue sensation, measured by a visual analogue scale before the experiment, was associated with the decrease in parasympathetic sinus modulation, as indicated the by ratio of low-frequency component power (LF) to high-frequency component power (HF), during the KPT. The LF/HF ratio during the post-KPT rest with eyes open tended to be greater than the ratio during the KPT and correlated with fatigue sensation. Fatigue sensation was correlated negatively with log-transformed HF, which is an index of parasympathetic sinus modulation, during the post-KPT rest with eyes open. Conclusions The methods described here are useful for assessing the association between fatigue sensation and autonomic nerve activity using a brief cognitive test in healthy females. PMID:25069864

Patterns of morning and evening fatigue among adults with HIV/AIDS.

PubMed

Lerdal, Anners; Gay, Caryl L; Aouizerat, Bradley E; Portillo, Carmen J; Lee, Kathryn A

2011-08-01

Describe patterns of morning and evening fatigue in adults with HIV and examine their relationship to demographic and clinical factors and other symptoms. Most studies of HIV-related fatigue assess average levels of fatigue and do not address its diurnal fluctuations. Patterns of fatigue over the course of the day may have important implications for assessment and treatment. A cross-sectional, correlational design was used with six repeated measures over 72 hours. A convenience sample of 318 HIV-infected adults was recruited in San Francisco. Socio-demographic, clinical and symptom data were collected with questionnaires. CD4+ T-cell count and viral load were obtained from medical records. Participants completed a four-item version of the Lee Fatigue Scale each morning and evening for three consecutive days. Participants were grouped based on their diurnal pattern of fatigue (high evening only, high morning only, high morning and evening and low morning and evening). Group comparisons and logistic regression were used to determine the unique predictors of each fatigue pattern. The high evening fatigue pattern was associated with anxiety and the high morning pattern was associated with anxiety and depression. The morning fatigue pattern showed very little fluctuation between morning and evening, the evening pattern showed the largest fluctuation. The high morning and evening pattern was associated with anxiety, depression and sleep disturbance and this group reported the most fatigue-related distress and interference in functioning. These results provide initial evidence for the importance of assessing the patient's daily pattern of fatigue fluctuation, as different patterns were associated with different symptom experiences and perhaps different aetiologies. Different fatigue patterns may benefit from tailored intervention strategies. Management of depressive symptoms could be tested in patients who experience high levels of morning fatigue. © 2011 Blackwell Publishing Ltd.

A Chronic Fatigue Syndrome (CFS) severity score based on case designation criteria

PubMed Central

Baraniuk, James N; Adewuyi, Oluwatoyin; Merck, Samantha Jean; Ali, Mushtaq; Ravindran, Murugan K; Timbol, Christian R; Rayhan, Rakib; Zheng, Yin; Le, Uyenphuong; Esteitie, Rania; Petrie, Kristina N

2013-01-01

Background: Chronic Fatigue Syndrome case designation criteria are scored as physicians’ subjective, nominal interpretations of patient fatigue, pain (headaches, myalgia, arthralgia, sore throat and lymph nodes), cognitive dysfunction, sleep and exertional exhaustion. Methods: Subjects self-reported symptoms using an anchored ordinal scale of 0 (no symptom), 1 (trivial complaints), 2 (mild), 3 (moderate), and 4 (severe). Fatigue of 3 or 4 distinguished “Fatigued” from “Not Fatigued” subjects. The sum of the 8(Sum8) ancillary criteria was tested as a proxy for fatigue. All subjects had history and physical examinations to exclude medical fatigue, and ensure categorization as healthy or CFS subjects. Results: Fatigued subjects were divided into CFS with ≥4 symptoms or Chronic Idiopathic Fatigue (CIF) with ≤3 symptoms. ROC of Sum8 for CFS and Not Fatigued subjects generated a threshold of 14 (specificity=0.934; sensitivity=0.928). CFS (n=256) and CIF (n=55) criteria were refined to include Sum8≥14 and ≤13, respectively. Not Fatigued subjects had highly skewed Sum8 responses. Healthy Controls (HC; n=269) were defined by fatigue≤2 and Sum8≤13. Those with Sum8≥14 were defined as CFS–Like With Insufficient Fatigue Syndrome (CFSLWIFS; n=20). Sum8 and Fatigue were highly correlated (R2=0.977; Cronbach’s alpha=0.924) indicating an intimate relationship between symptom constructs. Cluster analysis suggested 4 clades each in CFS and HC. Translational utility was inferred from the clustering of proteomics from cerebrospinal fluid. Conclusions: Plotting Fatigue severity versus Sum8 produced an internally consistent classifying system. This is a necessary step for translating symptom profiles into fatigue phenotypes and their pathophysiological mechanisms. PMID:23390566

Can Cognitive Activities during Breaks in Repetitive Manual Work Accelerate Recovery from Fatigue? A Controlled Experiment

PubMed Central

Mathiassen, Svend Erik; Hallman, David M.; Lyskov, Eugene; Hygge, Staffan

2014-01-01

Neurophysiologic theory and some empirical evidence suggest that fatigue caused by physical work may be more effectively recovered during “diverting” periods of cognitive activity than during passive rest; a phenomenon of great interest in working life. We investigated the extent to which development and recovery of fatigue during repeated bouts of an occupationally relevant reaching task was influenced by the difficulty of a cognitive activity between these bouts. Eighteen male volunteers performed three experimental sessions, consisting of six 7-min bouts of reaching alternating with 3 minutes of a memory test differing in difficulty between sessions. Throughout each session, recordings were made of upper trapezius muscle activity using electromyography (EMG), heart rate and heart rate variability (HRV) using electrocardiography, arterial blood pressure, and perceived fatigue (Borg CR10 scale and SOFI). A test battery before, immediately after and 1 hour after the work period included measurements of maximal shoulder elevation strength (MVC), pressure pain threshold (PPT) over the trapezius muscles, and a submaximal isometric contraction. As expected, perceived fatigue and EMG amplitude increased during the physical work bouts. Recovery did occur between the bouts, but fatigue accumulated throughout the work period. Neither EMG changes nor recovery of perceived fatigue during breaks were influenced by cognitive task difficulty, while heart rate and HRV recovered the most during breaks with the most difficult task. Recovery of perceived fatigue after the 1 hour work period was also most pronounced for the most difficult cognitive condition, while MVC and PPT showed ambiguous patterns, and EMG recovered similarly after all three cognitive protocols. Thus, we could confirm that cognitive tasks between bouts of fatiguing physical work can, indeed, accelerate recovery of some factors associated with fatigue, even if benefits may be moderate and some responses may be equivocal. Our results encourage further research into combinations of physical and mental tasks in an occupational context. PMID:25375644

Anti-polymer antibodies are correlated with pain and fatigue severity in patients with fibromyalgia syndrome.

PubMed

Sarzi-Puttini, Piercarlo; Atzeni, Fabiola; Di Franco, Manuela; Lama, Nicola; Batticciotto, Alberto; Iannuccelli, Cristina; Dell'Acqua, Donata; de Portu, Simona; Riccieri, Valeria; Carrabba, Mario; Buskila, Dan; Doria, Andrea; Valesini, Guido

2008-02-01

To investigate the prevalence of antipolymer antibody (APA) in patients with fibromyalgia (FM) and to examine its association with FM severity symptoms. The study population consisted of 79 FM patients and 75 controls: 32 with psoriatic arthritis and 43 with rheumatoid arthritis APA levels were indirectly assayed using a commercial ELISA kit from Corgenix (Westmister, Colorado, USA). Optical density (OD) values were recorded on duplicates of each of the reference and patient samples. Among clinical variables we investigated pain, measured according to visual analog scales (VAS: 0-100), fatigue, stiffness, anxiety, depression, all measured by VAS (0-100), and health status measured by Fibromyalgia Impact Questionnaire (FIQ). Sixteen of the 79 FM patients (20.3%) and 12/78 controls (15.4%) were positive for APAs (P = 0.536). Following ROC analysis, area under curve (AUC) was 0.49 (95% CI: 0.40, 0.58). Focusing on FM patients, we observed a correlation between APA titre and pain (tau: - 0.221; P = 0.020) and fatigue (tau: - 0.205; P = 0.032) at univariate analysis. Binomial regression analysis, controlling for clinical and demographic variables, showed that pain (PPR: 0.923; P = 0.007) and fatigue (PPR: 0.948; P = 0.024) were significantly associated with APA test sensitivity. APA test exhibited a low sensitivity in FM patients and it did not distinguish this group of patients from the controls enrolled in this study. Interestingly, positive APA test prevalence increased with less severe pain or fatigue.

Diagnostic Reasoning for ST-Segment Elevation Myocardial Infarction (STEMI) Interpretation Is Preserved Despite Fatigue

PubMed Central

Kellogg, Adam R.; Coute, Ryan A.; Garra, Gregory

2015-01-01

Background Fatigue and sleepiness contribute to medical errors, although the effect of circadian disruption and fatigue on diagnostic reasoning skills is largely unknown. Objective To determine whether circadian disruption and fatigue negatively affect the emergency medicine (EM) resident's ability to make important clinical decisions based on electrocardiogram (ECG) interpretation. Methods Senior EM residents at 2 programs completed a questionnaire consisting of various measures of fatigue followed by an ECG test packet of ST-segment elevation myocardial infarction (STEMI) and STEMI mimics. Participants were asked to examine each ECG and determine whether cardiac catheterization laboratory activation (CLA) was indicated, and to report their confidence in their decision making on an 11-point, numeric rating scale. The primary outcome measured was a pairwise difference in accuracy of CLA between daytime and overnight testing. Results A total of 23 residents were enrolled in 2011 and 2012. Subjects demonstrated significant differences in multiple measures of sleepiness and fatigue during overnight periods. The median (interquartile range [IQR]) accuracy of CLA was not significantly different between daytime and overnight (70% [IQR, 50–80] versus 70% [IQR, 60–70], P  =  .82). There were no significant differences in the median number of overcalls (CLA when not a STEMI) and undercalls (no CLA when a STEMI was present; P  =  .57 and .37, respectively). Diagnostic confidence and confidence in CLA were not statistically different between daytime and overnight. Conclusions Despite a measurable degree of fatigue, senior EM residents experienced no decrease in their ability to accurately make CLA decisions based on ECG interpretation. PMID:26217418

Diagnostic Reasoning for ST-Segment Elevation Myocardial Infarction (STEMI) Interpretation Is Preserved Despite Fatigue.

PubMed

Kellogg, Adam R; Coute, Ryan A; Garra, Gregory

2015-03-01

Fatigue and sleepiness contribute to medical errors, although the effect of circadian disruption and fatigue on diagnostic reasoning skills is largely unknown. To determine whether circadian disruption and fatigue negatively affect the emergency medicine (EM) resident's ability to make important clinical decisions based on electrocardiogram (ECG) interpretation. Senior EM residents at 2 programs completed a questionnaire consisting of various measures of fatigue followed by an ECG test packet of ST-segment elevation myocardial infarction (STEMI) and STEMI mimics. Participants were asked to examine each ECG and determine whether cardiac catheterization laboratory activation (CLA) was indicated, and to report their confidence in their decision making on an 11-point, numeric rating scale. The primary outcome measured was a pairwise difference in accuracy of CLA between daytime and overnight testing. A total of 23 residents were enrolled in 2011 and 2012. Subjects demonstrated significant differences in multiple measures of sleepiness and fatigue during overnight periods. The median (interquartile range [IQR]) accuracy of CLA was not significantly different between daytime and overnight (70% [IQR, 50-80] versus 70% [IQR, 60-70], P  =  .82). There were no significant differences in the median number of overcalls (CLA when not a STEMI) and undercalls (no CLA when a STEMI was present; P  =  .57 and .37, respectively). Diagnostic confidence and confidence in CLA were not statistically different between daytime and overnight. Despite a measurable degree of fatigue, senior EM residents experienced no decrease in their ability to accurately make CLA decisions based on ECG interpretation.

Flexure fatigue testing of 90 deg graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Peck, Ann Nancy W.

1995-01-01

A great deal of research has been performed characterizing the in-plane fiber-dominated properties, under both static and fatigue loading, of advanced composite materials. To the author's knowledge, no study has been performed to date investigating fatigue characteristics in the transverse direction. This information is important in the design of bonded composite airframe structure where repeated, cyclic out-of-plane bending may occur. Recent tests characterizing skin/stringer debond failures in reinforced composite panels where the dominant loading in the skin is flexure along the edge of the frame indicate failure initiated either in the skin or else the flange, near the flange tip. When failure initiated in the skin, transverse matrix cracks formed in the surface skin ply closest to the flange and either initiated delaminations or created matrix cracks in the next lower ply, which in turn initiated delaminations. When failure initiated in the flanges, transverse cracks formed in the flange angle ply closest to the skin and initiated delamination. In no configuration did failure propagate through the adhesive bond layer. For the examined skin/flange configurations, the maximum transverse tension stress at failure correlates very well with the transverse tension strength of the composites. Transverse tension strength (static) data of graphite epoxy composites have been shown to vary with the volume of material stressed. As the volume of material stressed increased, the strength decreased. A volumetric scaling law based on Weibull statistics can be used to predict the transverse strength measurements. The volume dependence reflects the presence of inherent flaws in the microstructure of the lamina. A similar approach may be taken to determine a volume scale effect on the transverse tension fatigue behavior of graphite/epoxy composites. The objective of this work is to generate transverse tension strength and fatigue S-N characteristics for composite materials using 3-point flexure tests of 90 deg graphite/epoxy specimens. Investigations will include the volume scale effect as well as frequency and span-to-thickness ratio effects. Prior to the start of the experimental study, an analytical study using finite element modeling will be performed to investigate the span-to-thickness effect. The ratio of transverse flexure stress to shear stress will be monitored and its values predicted by the FEM analysis compared with the value obtained using a 'strength of materials' based approach.

Validation of the Modified Fatigue Impact Scale and the relationships among fatigue, pain and serum interleukin-6 levels in patients with neuromyelitis optica spectrum disorder.

PubMed

Masuda, Hiroki; Mori, Masahiro; Uzawa, Akiyuki; Uchida, Tomohiko; Ohtani, Ryohei; Kobayashi, Shigeo; Kuwabara, Satoshi

2018-02-15

Fatigue and pain are disabling symptoms in patients with neuromyelitis optica spectrum disorder (NMOSD). The Modified Fatigue Impact Scale (MFIS) has not yet been validated in patients with NMOSD, and anti-interleukin-6 (IL-6) receptor antibody was reported to decrease pain and fatigue in patients with NMOSD. The aim of this study was to validate MFIS and to investigate the relationships among fatigue, pain and serum IL-6 levels in patients with NMOSD. MFIS and the Multidimensional Fatigue Inventory (MFI), an established scale for fatigue, were administered to patients with NMOSD and age- and sex-matched healthy controls (HCs). The Pain Effects Scale score and serum IL-6 levels were also measured in patients with NMOSD. Correlations among clinical characteristics, laboratory data and each score were investigated. To validate MFIS in patients with NMOSD, MFIS was administered twice within 4days from the first administration. Fifty-one patients answered the first MFIS, and 26 patients answered the second MFIS. There was no difference between the first and second MFIS scores. Patients with NMOSD had higher MFIS and MFI scores than HCs. No correlations were observed between serum IL-6 levels and either score. MFIS was validated in patients with NMOSD. Serum IL-6 levels may not be involved in the pathogenesis of fatigue and pain in patients with NMOSD. Copyright © 2017 Elsevier B.V. All rights reserved.

Factors related to fatigue after paediatric acquired brain injury (ABI).

PubMed

van Markus-Doornbosch, F; de Kloet, A J; Berger, M A M; Lambregts, S A M; Wolterbeek, R; Vliet Vlieland, T P M

2016-01-01

To assess the degree of fatigue in children and youth after traumatic and non-traumatic brain injury (TBI and NTBI) and related factors. Follow-up study including patients with a hospital-based diagnosis of acquired brain injury (ABI), aged 4-20 years at onset and their parents. Parents and children (dependent on age) completed the Paediatric Quality of Life Inventory™ Multidimensional Fatigue Scale (PedsQL™ MFS), which measures general fatigue (GF), sleep/rest fatigue (SRF) and cognitive fatigue (CF). Additional assessments included the Child & Family Follow-up Survey (CFFS) and PedsQL™ 4.0 General Core Scales and sociodemographic and disease characteristics. Eighty-eight parents completed the PedsQL™ MFS 24-30 months after diagnosis, with 49/88 patients (56%) completing the child version. The median age of the patients was 11 years (interquartile range [IQR] = 7). There were 69 patients with TBI (16% moderate/severe TBI) and 19 patients with NTBI (16% moderate/severe NTBI). The median parent-reported and child-reported PedsQL™ MFS Total Scale Scores were 76.5 (SD = 16.4) and 78.5 (12.9), respectively (Spearman r = 0.450, p = 0.001). Apart from NTBI, increasing age and a single-parent household were significantly associated with more fatigue according to the parent-reported PedsQL™ MFS Total Score (and/or one or more sub-scale scores). Two years after onset, in particular, the parent-reported fatigue after NTBI was considerable. Moreover, older children and children from a single-parent household were found to have higher fatigue levels.

Evaluation of a compassion fatigue resiliency program for oncology nurses.

PubMed

Potter, Patricia; Deshields, Teresa; Berger, Julia Allen; Clarke, Marty; Olsen, Sarah; Chen, Ling

2013-03-01

To evaluate a resiliency program designed to educate oncology nurses about compassion fatigue. Descriptive pilot study. A National Cancer Institute-designated comprehensive cancer center in the midwestern United States. 13 oncology nurses employed in an outpatient infusion center. Nurses attended a five-week program involving five 90-minute sessions on compassion fatigue resiliency. A pre- and post-test design, using repeated measures, was conducted over six months. Scores on the Professional Quality of Life (ProQOL) IV, Maslach Burnout Inventory-Human Services Survey, Impact of Event Scale-Revised (IES-R), and the Nursing Job Satisfaction Scale. Long-term benefits were realized from the program. Secondary traumatization scores on the ProQOL IV declined immediately after the program, remained down at three months, and then dropped again at six months, with a statistically significant mean difference compared with baseline. The average IES-R total scores improved significantly overall and for each of the three postintervention time points. Participants evaluated the program positively with respect to their ability to apply and benefit from resiliency techniques. This is the first reported study to show benefits gained from a compassion fatigue intervention program. Participants received useful strategies for managing stress at work and home. Compassion fatigue is a prevalent condition among healthcare providers. Development of resiliency to compassion fatigue may improve decision making, clarity of communication, and patient and nurse satisfaction. Self-regulation offers an approach to reduce stress during a perceived threat. Working by intention reduces reactivity in the workplace and makes communication more intentional and, therefore, effective.

Full-scale transmission testing to evaluate advanced lubricants

NASA Technical Reports Server (NTRS)

Lewicki, David G.; Decker, Harry J.; Shimski, John T.

1992-01-01

Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500 hp helicopter transmission test stand. The testing was part of a lubrication program. The objectives are to develop and show a separate lubricant for gearboxes with improved performance in life and load carrying capacity. The goal was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 based reference oil and then to run identical tests with improved lubricants and show improved performance. The tests were directed at parts that failed due to marginal lubrication from Navy field experience. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hrs of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring.

The proposal of a clinical protocol to assess central and peripheral fatigue in myotonic dystrophy type 1.

PubMed

Baldanzi, S; Ricci, G; Bottari, M; Chico, L; Simoncini, C; Siciliano, G

2017-07-01

DM1 is an autosomal-dominant disorder characterized by muscle weakness, myotonia, and multisystemic involvement. According to current literature fatigue and daytime sleepiness are among the main symptoms of DM1. Oxidative stress has been proposed to be one of the pathogenic factors of fatigue consequent to DM1. In this study, we investigated the dimensions of experienced fatigue and  physiological fatigue in a sample of 26 DM1 patients (17 males, 9 females, mean age 41.6 years, SD±12.7); experienced fatigue has been studied through Fatigue Severity Scale (FSS), and physiological fatigue was measured through an intermittent incremental exercise of the forearm muscles using a myometer; oxidative stress balance markers trend during aerobic exercise test have been collected. The occurrence of central fatigue in the sample means that central activation worsens during the motor contraction; interestingly FSS score was significantly correlated to MVC (before and after the effort, r-before=-0.583, p<0.01, r-after= -0.534, p<0.05), and to motor disability measured by MRC (r=-0.496, p<0.05); moreover we found a strong tendency towards significance in the association to lactate baseline (r=0.378, p=0.057).Results are discussed to define whether or not, based on clinical and laboratory grounds, such exercise training protocol may be suitable for proper management of DM1 patients; proper assessment of fatigue should be included in algorithms for data collection in DM1 patient registries.

The Minimally Important Difference for the Fatigue Visual Analog Scale in Patients with Rheumatoid Arthritis followed in an Academic Clinical Practice

PubMed Central

Khanna, Dinesh; Pope, Janet; Khanna, Puja P.; Maloney, Michelle; Samedi, Nooshin; Norrie, Debbie; Ouimet, Gillian; Hays, Ron D

2011-01-01

Introduction Fatigue is a common symptom in RA and used as an outcome measure in RA clinical trials. We studied a large academic clinical practice to estimate the minimally important difference (MID) for a fatigue visual analog scale using patient-reported anchors (fatigue, pain and overall health). Methods RA patients (N=307) had clinic visits at 2 time points at a median of 5.9 months apart. They completed fatigue visual analog scale (VAS; 0–10) and retrospective anchor items, “How would you describe your overall fatigue/pain/overall health since the last visit?” Much worsened, Somewhat worsened, Same, Somewhat better, or Much better. The fatigue anchor was used for primary analysis and the pain/ overall health anchors for sensitivity analyses. The minimally changed group was defined by those reporting they were somewhat better or somewhat worsened. Results The mean (SD) age was 59.4 (13.2) years, disease duration was 14.1 (11.5) years, and 83% of patients were women. The baseline mean (SD) HAQ-DI score was 0.84 (0.75). The baseline fatigue VAS score was 4.2 (2.9) and at follow up was 4.3 (2.8) (mean change of −0.07 [2.5], p=NS). The fatigue change score (0–10 scale) for somewhat better and somewhat worsened for fatigue anchor averaged −1.12 and 1.26, respectively. Using pain anchor, the fatigue changed score for somewhat better and somewhat worsened averaged −0.87 and 1.13 and using global anchor, the fatigue changed score for somewhat better and somewhat worsened averaged −0.82 and 1.17, respectively. Effect size (ES) estimates using 3 anchors were small for somewhat better (range: 0.27 to 0.39) and somewhat worsened (range: 0.40 to 0.44) groups but larger than the no-change group (range: 0.03 to 0.08). Conclusions The MID for fatigue VAS is between −0.82 to −1.12 for improvement and 1.13 to 1.26 for worsening on 0–10 scale in a large RA clinical practice and similar to that seen in RA clinical trials. This information can aid in interpreting fatigue VAS in day-to-day care in clinical practice. PMID:19004044

Implementing the Fatigue Guidelines at One NCCN Member Institution: Process and Outcomes

PubMed Central

Borneman, Tami; Piper, Barbara F.; Sun, Virginia Chih-Yi; Koczywas, Marianna; Uman, Gwen; Ferrell, Betty

2008-01-01

Fatigue, despite being the most common and distressing symptom in cancer, is often unrelieved because of numerous patient provider, and system barriers. The overall purpose of this 5-year prospective clinical trial is to translate the NCCN Cancer-Related Fatigue Clinical Practice Guidelines in Oncology and NCCN Adult Cancer Pain Clinical Practice Guidelines in Oncology into practice and develop a translational interventional model that can be replicated across settings. This article focuses on one NCCN member institution’s experience related to the first phase of the NCCN Cancer-Related Fatigue Guidelines implementation, describing usual care compared with evidence-based guidelines. Phase 1 of this 3-phased clinical trial compared the usual care of fatigue with that administered according to the NCCN guidelines. Eligibility criteria included age 18 years or older; English-speaking; diagnosed with breast, lung, colon, or prostate cancer; and fatigue and/or pain ratings of 4 or more on a 0 to 10 screening scale. Research nurses screened all available subjects in a cancer center medical oncology clinic to identify those meeting these criteria. Instruments included the Piper Fatigue Scale, a Fatigue Barriers Scale, a Fatigue Knowledge Scale, and a Fatigue Chart Audit Tool. Descriptive and inferential statistics were used in data analysis. At baseline, 45 patients had fatigue only (≥4) and 24 had both fatigue and pain (≥4). This combined sample (N = 69) was predominantly Caucasian (65%), female (63%), an average of 60 years old, diagnosed with stage 3 or 4 breast cancer, and undergoing treatment (82%). The most common barriers noted were patients’ belief that physicians would introduce the subject of fatigue if it was important (patient barrier); lack of fatigue documentation (professional barrier); and lack of supportive care referrals (system barrier). Findings showed several patient, professional, and system barriers that distinguish usual care from that recommended by the NCCN Cancer-Related Fatigue Guidelines. Phase 2, the intervention model, is designed to decrease these barriers and improve patient outcomes overtime, and is in progress. PMID:18053431

Psychological stress impairs short-term muscular recovery from resistance exercise.

PubMed

Stults-Kolehmainen, Matthew A; Bartholomew, John B

2012-11-01

The primary aim of this study was to determine whether chronic mental stress moderates recovery of muscular function, perceived energy, fatigue, and soreness in the first hour after a bout of strenuous resistance exercise. Thirty-one undergraduate resistance training students (age = 20.26 ± 1.34 yr) completed the Perceived Stress Scale and Undergraduate Stress Questionnaire (USQ; a measure of life event stress) and completed fitness testing. After 5 to 14 d of recovery, they performed an acute heavy-resistance exercise protocol (10-repetition maximum (RM) leg press test plus six sets: 80%-100% of 10 RM). Maximal isometric force (MIF) was assessed before exercise, after exercise, and at 20, 40, and 60 min postexercise. Participants also reported their levels of perceived energy, fatigue, and soreness. Recovery data were analyzed with hierarchical linear modeling growth curve analysis. Life event stress significantly moderated linear (P = 0.013) and squared (P = 0.05) recovery of MIF. This relationship held even when the model was adjusted for fitness, workload, and training experience. Likewise, perceived stress moderated linear recovery of MIF (P = 0.023). Neither USQ nor Perceived Stress Scale significantly moderated changes in energy, fatigue, or soreness. Life event stress and perceived stress both moderated the recovery of muscular function, but not psychological responses, in the first hour after strenuous resistance exercise.

Numerical determination of Paris law constants for carbon steel using a two-scale model

NASA Astrophysics Data System (ADS)

Mlikota, M.; Staib, S.; Schmauder, S.; Božić, Ž.

2017-05-01

For most engineering alloys, the long fatigue crack growth under a certain stress level can be described by the Paris law. The law provides a correlation between the fatigue crack growth rate (FCGR or da/dN), the range of stress intensity factor (ΔK), and the material constants C and m. A well-established test procedure is typically used to determine the Paris law constants C and m, considering standard specimens, notched and pre-cracked. Definition of all the details necessary to obtain feasible and comparable Paris law constants are covered by standards. However, these cost-expensive tests can be replaced by appropriate numerical calculations. In this respect, this paper deals with the numerical determination of Paris law constants for carbon steel using a two-scale model. A micro-model containing the microstructure of a material is generated using the Finite Element Method (FEM) to calculate the fatigue crack growth rate at a crack tip. The model is based on the Tanaka-Mura equation. On the other side, a macro-model serves for the calculation of the stress intensity factor. The analysis yields a relationship between the crack growth rates and the stress intensity factors for defined crack lengths which is then used to determine the Paris law constants.

Short-Term Effect of Aerobic Exercise on Symptoms in Multiple Sclerosis and Chronic Fatigue Syndrome

PubMed Central

Paul, Lorna; McFadyen, Angus K.; Marshall-McKenna, Rebecca; Mattison, Paul; Miller, Linda; McFarlane, Niall G.

2014-01-01

Background: This pilot study was conducted to determine whether a 15-minute bout of moderate-intensity aerobic cycling exercise would affect symptoms (pain and fatigue) and function (Timed 25-Foot Walk test [T25FW] and Timed Up and Go test [TUG]) in people with multiple sclerosis (MS) or chronic fatigue syndrome (CFS), and to compare these results with those of a healthy control group. Methods: Eight people with MS (Expanded Disability Status Scale score 5–6; Karnofsky score 50–80), eight people with CFS (Karnofsky score 50–80), and eight healthy volunteers participated in the study. Pain and fatigue levels and results of the T25FW and TUG were established at baseline as well as at 30 minutes, 2 hours, and 24 hours following a 15-minute stationary cycling aerobic exercise test. Repeated-measures analysis of variance (ANOVA) and covariance (ANCOVA) were used to analyze the findings over time. Results: At baseline there were statistically significant differences between groups in fatigue (P = .039), T25FW (P = .034), and TUG (P = .010). A significant group/time interaction emerged for fatigue levels (P= .005). We found no significant group/time interaction for pain levels or function. Conclusions: Undertaking 15 minutes of moderate-intensity aerobic cycling exercise had no significant adverse effects on pain or function in people with MS and CFS (with a Karnofsky score of 50–80) within a 24-hour time period. These initial results suggest that people with MS or CFS may undertake 15 minutes of cycling as moderate aerobic exercise with no expected negative impact on pain or function. PMID:25061431

Failure probability of three designs of zirconia crowns

PubMed Central

Ramos, G. Freitas; Monteiro, E. Barbosa Carmona; Bottino, M.A.; Zhang, Y.; de Melo, R. Marques

2015-01-01

Objectives This study utilized a 2-parameter Weibull analysis for evaluation of lifetime of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. Methods Sixty first molars were selected and prepared for full-coverage crowns with three different designs(n = 20): Traditional –crowns with zirconia framework covered with feldspathic porcelain; Modified– crowns partially covered with veneering porcelain; and Monolithic–full-contour zirconia crowns. All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100N, 3Hz) with a piston with hemispherical tip (Ø=6 mm) until the specimens failed or up to 2×106 cycles. Every 500,000 cycles intervals, the fatigue tests were interrupted, and stereomicroscopy (10 X) was used to inspect the specimens for damage. We performed Weibull analysis of interval data to calculate the number of failures in each interval. Results The types and number of failures according to the groups were: cracking (Traditional-13, Modified-6) and chipping (Traditional-4) of the feldspathic porcelain, followed by delamination (Traditional-1) at the veneer/core interface and debonding (Monollithic-2) at the cementation interface. Weibull parameters (beta, scale; and eta, shape), with a two-sided confidence interval of 95%, were: Traditional – 1.25 and 0.9 × 106cycles; Modified– 0.58 and 11.7 × 106 cycles; and Monolithic – 1.05 and 16.5 × 106 cycles. Traditional crowns showed greater susceptibility to fatigue, the Modified group presented higher propensity to early failures, and the Monolithic group showed no susceptibility to fatigue. The Modified and Monolithic groups presented the highest number of crowns with no failures after the fatigue test. Conclusions The three crown designs presented significantly different behaviors under fatigue. The Modified and the Monolithic groups presented less probability to failure after 2×106cycles. PMID:26509988

Bearing fatigue investigation 3

NASA Technical Reports Server (NTRS)

Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

1982-01-01

The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

Validation of a Smartphone-Based Approach to In Situ Cognitive Fatigue Assessment

PubMed Central

Linden, Mark

2017-01-01

Background Acquired Brain Injuries (ABIs) can result in multiple detrimental cognitive effects, such as reduced memory capability, concentration, and planning. These effects can lead to cognitive fatigue, which can exacerbate the symptoms of ABIs and hinder management and recovery. Assessing cognitive fatigue is difficult due to the largely subjective nature of the condition and existing assessment approaches. Traditional methods of assessment use self-assessment questionnaires delivered in a medical setting, but recent work has attempted to employ more objective cognitive tests as a way of evaluating cognitive fatigue. However, these tests are still predominantly delivered within a medical environment, limiting their utility and efficacy. Objective The aim of this research was to investigate how cognitive fatigue can be accurately assessed in situ, during the quotidian activities of life. It was hypothesized that this assessment could be achieved through the use of mobile assistive technology to assess working memory, sustained attention, information processing speed, reaction time, and cognitive throughput. Methods The study used a bespoke smartphone app to track daily cognitive performance, in order to assess potential levels of cognitive fatigue. Twenty-one participants with no prior reported brain injuries took place in a two-week study, resulting in 81 individual testing instances being collected. The smartphone app delivered three cognitive tests on a daily basis: (1) Spatial Span to measure visuospatial working memory; (2) Psychomotor Vigilance Task (PVT) to measure sustained attention, information processing speed, and reaction time; and (3) a Mental Arithmetic Test to measure cognitive throughput. A smartphone-optimized version of the Mental Fatigue Scale (MFS) self-assessment questionnaire was used as a baseline to assess the validity of the three cognitive tests, as the questionnaire has already been validated in multiple peer-reviewed studies. Results The most highly correlated results were from the PVT, which showed a positive correlation with those from the prevalidated MFS, measuring 0.342 (P<.008). Scores from the cognitive tests were entered into a regression model and showed that only reaction time in the PVT was a significant predictor of fatigue (P=.016, F=2.682, 95% CI 9.0-84.2). Higher scores on the MFS were related to increases in reaction time during our mobile variant of the PVT. Conclusions The results show that the PVT mobile cognitive test developed for this study could be used as a valid and reliable method for measuring cognitive fatigue in situ. This test would remove the subjectivity associated with established self-assessment approaches and the need for assessments to be performed in a medical setting. Based on our findings, future work could explore delivering a small set of tests with increased duration to further improve measurement reliability. Moreover, as the smartphone assessment tool can be used as part of everyday life, additional sources of data relating to physiological, psychological, and environmental context could be included within the analysis to improve the nature and precision of the assessment process. PMID:28818818

Patient confidence and quality of life in idiopathic pulmonary fibrosis and sarcoidosis.

PubMed

Kotecha, Jalpa; Atkins, Christopher; Wilson, Andrew

2016-12-23

Idiopathic pulmonary fibrosis (IPF) and sarcoidosis impact significantly on health-related quality of life (HRQOL). There are few studies on the impact of patient confidence on HRQOL in these conditions. 1. To investigate whether patient confidence is associated with HRQOL, anxiety, depression, dyspnoea or fatigue. 2. To assess if patient confidence is associated with inpatient admissions, access to community healthcare and, for IPF patients, mortality and disease severity. Study participants self-completed seven questionnaires: Hospital Anxiety and Depression Scale, EuroQol 5D (EQ5D), King's Brief Interstitial Lung Disease questionnaire, St George's Respiratory Questionnaire, MRC dyspnoea scale, Fatigue Assessment Scale and a non-validated questionnaire assessing patient confidence, symptom duration and access to community healthcare. Lung function and follow-up data were collected from hospital electronic databases. Spearman's rank correlation coefficients were calculated to assess for correlation between patient confidence, questionnaire variables and inpatient admissions. Chi-square tests were performed to assess for association between patient confidence, mortality and disease severity. 75 IPF patients and 69 sarcoidosis patients were recruited to the study. Patient confidence in IPF was significantly negatively correlated with depression and fatigue, and significantly positively correlated with EQ5D scores, but not healthcare outcomes. No associations were found between confidence and any of the variables assessed in sarcoidosis. Lower levels of confidence in IPF patients are associated with higher levels of depression and fatigue and worse HRQOL. Efforts should be made to improve patient confidence to assess the impact on HRQOL.

Hydraulic Fatigue-Testing Machine

NASA Technical Reports Server (NTRS)

Hodo, James D.; Moore, Dennis R.; Morris, Thomas F.; Tiller, Newton G.

1987-01-01

Fatigue-testing machine applies fluctuating tension to number of specimens at same time. When sample breaks, machine continues to test remaining specimens. Series of tensile tests needed to determine fatigue properties of materials performed more rapidly than in conventional fatigue-testing machine.

Oxidative stress and fatigue in systemic lupus erythematosus.

PubMed

Segal, B M; Thomas, W; Zhu, X; Diebes, A; McElvain, G; Baechler, E; Gross, M

2012-08-01

The objective of this study is to investigate the relationship of oxidative stress to fatigue in systemic lupus erythematosus (SLE). Patients with a confirmed diagnosis of SLE by ACR criteria and healthy controls completed validated questionnaires to assess depression and fatigue. Fatigue was measured with the Fatigue Severity Scale (FSS) and the Profile of Fatigue (Prof-F). Visual analogue scales (VAS) were also used to assess fatigue and pain. Depression was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). Plasma F(2)-isoprostane was measured with gas chromatography/mass spectroscopy to assess oxidative stress. Evaluation included medical record review, physical exam and calculation of body mass index (BMI), disease activity (SLEDAI) and damage (SLICC) in the SLE patients. Seventy-one SLE patients with low disease activity (mean SLEDAI = 1.62 standard error (SE) 0.37, range 0-8) were compared to 51 controls. Fatigue-limiting physical activity (defined as FSS ≥ 4) was present in 56% of patients and 12% of controls. F(2)-isoprostane was higher in SLE patients with fatigue compared to not-fatigued SLE subjects (p = .0076) who were otherwise similar in ethnicity, disease activity and cardiovascular risk factors. Plasma F(2)-isoprostane was strongly correlated with FSS and Profile of Somatic Fatigue (Prof-S) (p < .0001), VAS fatigue (p = .005), CES-D (p = .008) and with BMI (p = .0001.) In a multivariate model, F(2)-isoprostane was a significant predictor of FSS after adjustment for age, BMI, pain and depression (p = .0002). Fatigue in SLE patients with low disease activity is associated with increased F(2)-isoprostane. F2-isoprostane could provide a useful biomarker to explore mitochondrial function and the regulation of oxidative pathways in patients with SLE in whom fatigue is a debilitating symptom.

An Experimental Investigation of Transverse Tension Fatigue Characterization of IM6/3501-6 Composite Materials Using a Three-Point Bend Test

NASA Technical Reports Server (NTRS)

Peck, Ann W.

1998-01-01

As composites are introduced into more complex structures with out-of-plane loadings, a better understanding is needed of the out-of-plane, matrix-dominated failure mechanisms. This work investigates the transverse tension fatigue characteristics of IM6/3501 composite materials. To test the 90 degree laminae, a three-point bend test was chosen, potentially minimizing handling and gripping issues associated with tension tests. A finite element analysis was performed of a particular specimen configuration to investigate the influence of specimen size on the stress distribution for a three-point bend test. Static testing of 50 specimens of 9 different sized configurations produced a mean transverse tensile strength of 61.3 Mpa (8.0 ksi). The smallest configuration (10.2 mm wide, Span-to-thickness ratio of 3) consistently exhibited transverse tensile failures. A volume scale effect was difficult to discern due to the large scatter of the data. Static testing of 10 different specimens taken from a second panel produced a mean transverse tensile strength of 82.7 Mpa (12.0 ksi). Weibull parameterization of the data was possible, but due to variability in raw material and/or manufacturing, more replicates are needed for greater confidence. Three-point flex fatigue testing of the smallest configuration was performed on 59 specimens at various levels of the mean static transverse tensile strength using an R ratio of 0.1 and a frequency of 20 Hz. A great deal of scatter was seen in the data. The majority of specimens failed near the center loading roller. To determine whether the scatter in the fatigue data is due to variability in raw material and/or the manufacturing process, additional testing should be performed on panels manufactured from different sources.

Clinical Determinants of Incremental Shuttle Walk Test in Adults with Bronchiectasis.

PubMed

Yildiz, Sulenur; Inal-Ince, Deniz; Calik-Kutukcu, Ebru; Vardar-Yagli, Naciye; Saglam, Melda; Arikan, Hulya; Coplu, Lutfi

2018-06-01

Exercise capacity is impaired in patients with bronchiectasis. Incremental shuttle walk test (ISWT) stresses cardiorespiratory system physiologically to symptom-limited maximal exercise capacity. The purpose of this study was to investigate the clinical determinants of ISWT in adults with non-cystic fibrosis (CF) bronchiectasis. Forty-one clinically stable bronchiectasis patients aged 18-72 years (27 females, 14 males) participated in the study. Subjects' demographics and physical characteristics were recorded. Bronchiectasis Severity Index was used to identify disease severity. Pulmonary function test was performed. Dyspnea perception was assessed using the modified Medical Research Council Dyspnea Scale. Maximum inspiratory and expiratory pressures were measured. Peripheral muscle strength using a hand held dynamometer was measured. ISWT was performed to determine exercise capacity. Fatigue Severity Scale, Hospital Anxiety and Depression Scale, Leicester Cough Questionnaire were used to determine fatigue, psychosocial status, and quality of life. Patients' mean ISWT distance was 469.5 m. The ISWT distance was significantly related with age (r = - 0.472), height (r = 0.469), gender (r = 0.520), FEV 1 (r = 0.651), and FVC (r = 0.545, p < 0.05). Quadriceps muscle strength was higher in males (p = 0.001) as compared to females. Age and gender were identified as independent predictors of the ISWT, explaining 42% of variance in ISWT distance (r = 0.649, r 2  = 0.421, F (2,38)  = 13.794, p < 0.001). The clinical determinants of ISWT in clinically stable patients with non-CF bronchiectasis are age and gender. Pulmonary function, dyspnea perception, muscle strength, disease severity, fatigue, psychosocial factors, and health-related quality of life seems to have an independent effect on ISWT in this group of patients with bronchiectasis.

Fatigue and its associated factors in liver transplant recipients in Beijing: a cross-sectional study

PubMed Central

Lin, Xiao-Hong; Teng, Sha; Wang, Lu; Zhang, Jing; Shang, Ya-Bin; Liu, Hong-Xia; Zang, Yun-Jin

2017-01-01

Objectives Fatigue is a highly prevalent symptom experienced by patients who underwent the liver transplantation. However, the influencing factors of fatigue are poorly understood by healthcare professionals. The aim of this study was to examine the intensity, interference, duration and prevalence of fatigue in liver transplantation recipients and to explore the influencing factors of post-transplantation fatigue. Design A cross-sectional design was used in this study. Methods A convenience sample of liver transplant recipients was recruited at an outpatient transplant clinic of a general hospital in Beijing, China. Self-report survey data were provided by liver transplant recipients using the Fatigue Symptom Inventory (FSI), the Hospital Anxiety and Depression Scale (HADS), the Perceived Social Support Scale (PSSS) and the Athens Insomnia Scale (AIS). Demographic, clinical and psychosocial parameters were evaluated as fatigue influencing factors. Results Participants (n=285) included 69 women and 216 men. Fatigue was found in 87.0% of liver transplant recipients. Mean scores of fatigue intensity items were 4.47±2.85, 1.93±1.97, 3.15±2.13 and 2.73±2.42 (most fatigue, least fatigue, average fatigue in the week prior to assessment and fatigue at the point of assessment). The mean score of fatigue interference was 2.27±2.09.The number of days fatigued in the week prior to assessment was 2.26±2.02 and the amount of time fatigued each day was 2.75±2.44. Spearman's correlation analysis showed that fatigue intensity was positively associated with anxiety, depression and insomnia (p<0.001 for all), while fatigue interference was positively associated with gender, anxiety, depression and insomnia (p<0.05 for all). In the multiple linear regression analysis, anxiety and insomnia were positively associated with fatigue intensity (p<0.001), and insomnia, depression and anxiety were positively associated with fatigue interference (p<0.001). Conclusions Fatigue is common in liver transplant recipients, and it is strongly associated with insomnia, anxiety and depression. PMID:28235963

[Guidelines for monitoring late-onset Pompe disease.Sociedad Española de Medicina Interna (SEMI), Sociedad Española de Neurología (SEN) y Sociedad Española de Neumología y CirugíaTorácica (SEPAR)].

PubMed

Gutiérrez-Rivas, Eduardo; Illa, Isabel; Pascual-Pascual, Samuel I; Pérez-López, Jordi; Vílchez-Padilla, Juan J; Bautista-Lorite, Juan; Barrot, Emilia; López de Munain, Adolfo

2015-04-01

Although treatment with alglucosidase alfa has helped improve the prognosis of patients with late-onset Pompe disease, both the development of the disease and the effectiveness of the treatment need to be monitored on a regular basis. This is the reason that has led a committee of Spanish experts to draw up a series of guidelines on how to follow up these patients. The committee proposes a model of follow-up tests for late-onset Pompe disease. First of all, the nutritional status and swallowing function must be evaluated. Second, and due to the variability of the clinical features, the committee recommends the simultaneous use of several scales to measure different functions and parameters. Thus, muscular force is assessed with the Medical Research Council scale; motor functioning, with the six-minute walk test and timed tests; disability, with the Rasch-built Pompe-specific Activity scale; respiratory functioning, with measurement of the forced vital capacity and oxygen saturation; and fatigue, with the fatigue intensity scale. Lastly, the safety and tolerability of enzyme replacement therapy are controlled by registering and treating the potential side effects and measurement of the anti-alglucosidase alfa antibodies. A number of different general recommendations are also included.

Muscle fatigue evaluation of astronaut upper limb based on sEMG and subjective assessment

NASA Astrophysics Data System (ADS)

Zu, Xiaoqi; Zhou, Qianxiang; Li, Yun

2012-07-01

All movements are driven by muscle contraction, and it is easy to cause muscle fatigue. Evaluation of muscle fatigue is a hot topic in the area of astronaut life support training and rehabilitation. If muscle gets into fatigue condition, it may reduce work efficiency and has an impact on psychological performance. Therefore it is necessary to develop an accurate and usable method on muscle fatigue evaluation of astronaut upper limb. In this study, we developed a method based on surface electromyography (sEMG) and subjective assessment (Borg scale) to evaluate local muscle fatigue. Fifteen healthy young male subjects participated in the experiment. They performed isometric muscle contractions of the upper limb. sEMG of the biceps brachii were recorded during the entire process of isotonic muscle contraction and Borg scales of muscle fatigue were collected in certain times. sEMG were divided into several parts, and then mean energy of each parts were calculated by the one-twelfth band octave method. Equations were derived based on the relationship between the mean energy of sEMG and Borg scale. The results showed that cubic curve could describe the degree of local muscle fatigue, and could be used to evaluate and monitor local muscle fatigue during the entire process.

Modafinil In Debilitating fatigue After Stroke (MIDAS): study protocol for a randomised, double-blinded, placebo-controlled, crossover trial.

PubMed

Lillicrap, Thomas; Krishnamurthy, Venkatesh; Attia, John; Nilsson, Michael; Levi, Christopher R; Parsons, Mark W; Bivard, Andrew

2016-08-17

Fatigue is a common symptom in stroke survivors for which there is currently no proven therapy. Modafinil is a wakefulness-promoting agent with established benefits in other disease models. We aim to test if modafinil will improve patient's self-reported fatigue scores when compared to placebo and if therapy results in increased quality of life. MIDAS is a phase II, single-centre, prospective, double-blinded, randomised, crossover trial of modafinil for the treatment of persistent fatigue in survivors of ischaemic stroke. The inclusion criteria will require an average score of 12 or more across all domains of the Multi-dimensional Fatigue Inventory (MFI-20) and the diagnosis of a stroke more than 6 months prior. Patients will be randomised 1:1 to receive either modafinil 200 mg daily or placebo for a period of 6 weeks, after which a crossover will occur where patients who are on modafinil will begin taking placebo and vice versa. The primary outcome will be improvement in fatigue as measured by the MFI-20. Secondary outcomes will include changes in the Fatigue Severity Scale, improved cognition measured using the Montreal Cognitive Assessment, improvement in mood as determined by the Depression, Anxiety and Stress Scale and improvement in each patient's stroke-specific quality of life score. All participants will also undergo magnetic resonance imaging (MRI) at baseline, crossover and study conclusion to measure cerebral blood flow on arterial spin labelling and brain activity on resting state functional MRI. This study will comply with the CONSORT guidelines. The projected sample size requirement is 36 participants in a crossover trial giving a power of 80 % and a type-1 error rate of 0.05. MIDAS seeks to enhance the quality of life in stroke survivors by assisting or resolving stroke-associated fatigue. ACTRN12615000350527 , registered on the 17 April 2015. Protocol version 3, approved 16 June 2015.

Muscle fatigue effects can be anticipated to reproduce a movement kinematics learned without fatigue.

PubMed

Monjo, Florian; Forestier, Nicolas

2016-12-17

Muscle fatigue modifies the gain between motor command magnitude and the mechanical muscular response. In other words, post-fatigue, central drives to the muscles must increase to maintain a particular submaximum mechanical output. In this study, we tested the hypothesis that this modified gain can be predicted by the central nervous system (CNS) during discrete ballistic movements. In two separate experiments, subjects were required to perform shoulder flexions in standing and sitting positions at submaximum target peak accelerations. They were assisted with visual feedback informing them on their performance after each trial. Shoulder flexions were performed before and after fatiguing protocols of the focal muscles. Acceleration signals, focal and postural muscle electromyograms (EMGs) were recorded. The results demonstrated that participants were able to reach with precision the target acceleration during the first movements post-fatigue at the cost of significant increase in focal motor command magnitude. Decreased variance of peak accelerations associated with increased focal command variability was observed post-fatigue. During the standing experiment, postural muscle EMGs revealed that anticipatory postural adjustments (APAs) scaled to focal movement acceleration post-fatigue. All these results support that fatigue effects are taken into account during movement planning. Indeed, given that no feedback could enable participants to adjust acceleration during movement, this capacity to anticipate fatigue effects is the exclusive result of feedforward processes. To account for this prediction capacity, we discuss the role of fatigue-related modifications in sensory inputs from the working muscles. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Effects of Multidisciplinary Rehabilitation on Chronic Fatigue in Multiple Sclerosis: A Randomized Controlled Trial

PubMed Central

Rietberg, Marc B.; van Wegen, Erwin E. H.; Eyssen, Isaline C. J. M.; Kwakkel, Gert

2014-01-01

Background Several rehabilitation programmes aim at reducing the impact of fatigue in MS patients. Acute and chronic fatigue should require different management. Objectives To assess the effects of individually tailored, multidisciplinary outpatient rehabilitation (MDR) on chronic fatigue. Methods Forty-eight ambulatory MS patients with chronic fatigue were randomized to MDR or to MS–nurse consultation. Fatigue was assessed by the Checklist Individual Strength (CIS-20R). Secondary outcomes included the Modified Fatigue Impact Scale, Fatigue Severity Scale, Functional Independence Measure, Disability and Impact Profile (DIP), Multiple Sclerosis Impact Scale and the Impact on Participation and Autonomy (IPA). Results The primary outcome measure CIS-20R overall score showed no significant differences between groups at 12 weeks (P = 0.39) and 24 weeks follow-up (P = 0.14), nor for subscales (t = 12 and t = 24, 0.19≤P≤0.88). No significant within-group effects were found for both groups with respect to the primary (0.57≤p≤0.97) and secondary (0.11≤p≤0.92) outcome measures from baseline to 12 or 24 weeks. Conclusion Multidisciplinary rehabilitation was not more effective in terms of reducing self-reported fatigue in MS patients compared to MS-nurse consultation. Our results suggest that chronic fatigue in patients with MS may be highly invariant over time, irrespective of interventions. Trial Registration controlled-trials.com ISRCTN05017507 PMID:25232955

Fatigue is correlated with disease activity but not with the type of organ involvement in Behçet's syndrome: a comparative clinical survey.

PubMed

Buyuktas, Deram; Hatemi, Gulen; Yuksel-Findikoglu, Sukran; Ugurlu, Serdal; Yazici, Hasan; Yurdakul, Sebahattin

2015-01-01

Fatigue is an important problem in inflammatory diseases and affects the quality of life (QoL). We aimed to evaluate the severity and impact of fatigue in Behçet's syndrome (BS) and to determine its association with type of organ involvement and gender. One hundred and fifty-two BS, 51 rheumatoid arthritis (RA), 51 systemic lupus erythematosus (SLE), 51 ankylosing spondylitis (AS) patients and 65 healthy controls were evaluated by the fatigue severity scale, fatigue impact scale, fibromyalgia impact questionnaire (FIQ), RAPID3, SF-36 and Behçet's syndrome activity scale (the latter only in BS patients). We also analysed subgroups of BS patients with predominantly eye, vascular, joint and mucocutaneous involvement and did an additional gender analysis. Fatigue severity and fatigue impact scores were similar among BS, RA, SLE and AS patients and significantly higher than that in healthy controls (F4df=8.51; p<0.001 and F4df=8.67; p<0.001, respectively). The fatigue severity and fatigue impact scores were similarly high in BS subgroups with different types of organ involvement, and in both genders. Fatigue is an important problem in BS, as it is in other inflammatory conditions. It is similarly severe in subgroups of patients with eye, vascular, joint and mucocutaneous involvement and in either gender. Fatigue is a candidate outcome measure for clinical trials, to assess the life impact of Behçet's syndrome.

AISI/DOE Technology Roadmap Program: Cold Work Embrittlement of Interstitial Free Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

John T Bowker; Pierre Martin

2002-10-31

This work addresses the issues of measurement of secondary cold work embrittlement (SCWE) of an IF steel in deep-drawn parts using laboratory tests, and its correlation with real part fracture. It aimed at evaluating the influence of the steel chemistry and processing condition, microstructure, and test conditions, on SCWE as well as the effect of SCWE on fatigue properties. Size 6-in. cups produced with various draw ratios or trimmed at different heights were tested to determine the ductile-to-brittle-transition temperature (DBTT) as a function of strain. The 2-in. cup/expansion test, bend test and fracture of notched specimens were also used tomore » generate information complementary to that provided by the 6-inch cup/expansion test. The relationship between laboratory tests and fracture in real parts was established by testing large-scale parts. The fatigue behavior was investigated in the as-rolled and deep drawn (high stain) conditions, using prestrained specimens taken from the wall of a formed part.« less

Supervised exercise reduces cancer-related fatigue: a systematic review.

PubMed

Meneses-Echávez, José F; González-Jiménez, Emilio; Ramírez-Vélez, Robinson

2015-01-01

Does supervised physical activity reduce cancer-related fatigue? Systematic review with meta-analysis of randomised trials. People diagnosed with any type of cancer, without restriction to a particular stage of diagnosis or treatment. Supervised physical activity interventions (eg, aerobic, resistance and stretching exercise), defined as any planned or structured body movement causing an increase in energy expenditure, designed to maintain or enhance health-related outcomes, and performed with systematic frequency, intensity and duration. The primary outcome measure was fatigue. Secondary outcomes were physical and functional wellbeing assessed using the Functional Assessment of Cancer Therapy Fatigue Scale, European Organisation for Research and Treatment of Cancer Quality of Life QUESTIONnaire, Piper Fatigue Scale, Schwartz Cancer Fatigue Scale and the Multidimensional Fatigue Inventory. Methodological quality, including risk of bias of the studies, was evaluated using the PEDro Scale. Eleven studies involving 1530 participants were included in the review. The assessment of quality showed a mean score of 6.5 (SD 1.1), indicating a low overall risk of bias. The pooled effect on fatigue, calculated as a standardised mean difference (SMD) using a random-effects model, was -1.69 (95% CI -2.99 to -0.39). Beneficial reductions in fatigue were also found with combined aerobic and resistance training with supervision (SMD=-0.41, 95% CI -0.70 to -0.13) and with combined aerobic, resistance and stretching training with supervision (SMD=-0.67, 95% CI -1.17 to -0.17). Supervised physical activity interventions reduce cancer-related fatigue. These findings suggest that combined aerobic and resistance exercise regimens with or without stretching should be included as part of rehabilitation programs for people who have been diagnosed with cancer. PROSPERO CRD42013005803. Copyright © 2014 Australian Physiotherapy Association. Published by Elsevier B.V. All rights reserved.

Full-scale fatigue tests of CX-100 wind turbine blades. Part II: analysis

NASA Astrophysics Data System (ADS)

Taylor, Stuart G.; Jeong, Hyomi; Jang, Jae Kyeong; Park, Gyuhae; Farinholt, Kevin M.; Todd, Michael D.; Ammerman, Curtt M.

2012-04-01

This paper presents the initial analysis results of several structural health monitoring (SHM) methods applied to two 9- meter CX-100 wind turbine blades subjected to fatigue loading at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC). The first blade was a pristine blade, manufactured to standard CX-100 design specifications. The second blade was manufactured for the University of Massachusetts, Lowell (UMass), with intentional simulated defects within the fabric layup. Each blade was instrumented with a variety of sensors on its surface. The blades were subject to harmonic excitation at their first natural frequency with steadily increasing loading until ultimately reaching failure. Data from the sensors were collected between and during fatigue loading sessions. The data were measured at multi-scale frequency ranges using a variety of data acquisition equipment, including off-the-shelf systems and prototype data acquisition hardware. The data were analyzed to identify fatigue damage initiation and to assess damage progression. Modal response, diffuse wave-field transfer functions in time and frequency domains, and wave propagation methods were applied to assess the condition of the turbine blade. The analysis methods implemented were evaluated in conjunction with hardware-specific performance for their efficacy in enabling the assessment of damage progression in the blade. The results of this assessment will inform the selection of specific data to be collected and analysis methods to be implemented for a CX-100 flight test to be conducted in collaboration with Sandia National Laboratory at the U.S. Department of Agriculture's (USDA) Conservation and Production Research Laboratory (CPRL) in Bushland, Texas.

Contributors to fatigue in patients receiving mechanical ventilatory support: A descriptive correlational study.

PubMed

Chlan, Linda L; Savik, Kay

2015-10-01

To describe levels of fatigue and explore clinical factors that might contribute to fatigue in critically ill patients receiving mechanical ventilation. Descriptive, correlational design. Sample was a sub-set of patients enrolled in a randomised clinical trial testing patient-directed music for anxiety self-management. Clinical factors included age, gender, length of ICU stay, length of ventilatory support, illness severity (APACHE III), and sedative exposure (sedation intensity and frequency). Descriptive statistics and mixed models were used to address the study objectives. Medical and surgical intensive care units in the Midwestern United States. Fatigue was measured daily via a 100-mm Visual Analogue Scale, up to 25 days. A sample of 80 patients (50% female) receiving ventilatory support for a median 7.9 days (range 1-46) with a mean age of 61.2 years (SD 14.8) provided daily fatigue ratings. ICU admission APACHE III was 61.5 (SD 19.8). Baseline mean fatigue ratings were 60.7 (SD 27.9), with fluctuations over time indicating a general trend upward. Mixed models analysis implicated illness severity (β(se(β))=.27(.12)) and sedation frequency (β(se(β))=1.2(.52)) as significant contributors to fatigue ratings. Illness severity and more frequent sedative administration were related to higher fatigue ratings in these mechanically ventilated patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

CONTRIBUTORS TO FATIGUE IN PATIENTS RECEIVING MECHANICAL VENTILATORY SUPPORT: A DESCRIPTIVE CORRELATIONAL STUDY

PubMed Central

Chlan, Linda L.; Savik, Kay

2015-01-01

Objectives To describe levels of fatigue and explore clinical factors that might contribute to fatigue in critically ill patients receiving mechanical ventilation. Research Methodology/Design Descriptive, correlational design. Sample was a sub-set of patients enrolled in a randomized clinical trial testing patient-directed music for anxiety self-management. Clinical factors included age, gender, length of ICU stay, length of ventilatory support, illness severity (APACHE III), and sedative exposure (sedation intensity and frequency). Descriptive statistics and mixed models were used to address the study objectives. Setting Medical and surgical intensive care units in the Midwestern U.S.A. Main Outcome Measures Fatigue was measured daily via a 100-mm Visual Analog Scale, up to 25 days. Results A sample of 80 patients (50% female) receiving ventilatory support for a median 7.9 days (range 1-46) with a mean age of 61.2 years (SD 14.8) provided daily fatigue ratings. ICU admission APACHE III was 61.5 (SD 19.8). Baseline mean fatigue ratings were 60.7 (SD 27.9), with fluctuations over time indicating a general trend upward. Mixed models analysis implicated illness severity (β(se(β)) = .27(.12)) and sedation frequency (β(se(β)) = 1.2(.52)) as significant contributors to fatigue ratings. Conclusion Illness severity and more frequent sedative administration were related to higher fatigue ratings in these mechanically ventilated patients. PMID:26005034

Does Oral Coenzyme Q10 Plus NADH Supplementation Improve Fatigue and Biochemical Parameters in Chronic Fatigue Syndrome?

PubMed Central

Cordero, Mario D.; Segundo, María José; Sáez-Francàs, Naia; Calvo, Natalia; Román-Malo, Lourdes; Aliste, Luisa; Fernández de Sevilla, Tomás; Alegre, José

2015-01-01

Abstract Chronic fatigue syndrome (CFS) is a chronic and extremely debilitating illness characterized by prolonged fatigue and multiple symptoms with unknown cause, diagnostic test, or universally effective treatment. Inflammation, oxidative stress, mitochondrial dysfunction, and CoQ10 deficiency have been well documented in CFS. We conducted an 8-week, randomized, double-blind placebo-controlled trial to evaluate the benefits of oral CoQ10 (200 mg/day) plus NADH (20 mg/day) supplementation on fatigue and biochemical parameters in 73 Spanish CFS patients. This study was registered in ClinicalTrials.gov (NCT02063126). A significant improvement of fatigue showing a reduction in fatigue impact scale total score (p<0.05) was reported in treated group versus placebo. In addition, a recovery of the biochemical parameters was also reported. NAD+/NADH (p<0.001), CoQ10 (p<0.05), ATP (p<0.05), and citrate synthase (p<0.05) were significantly higher, and lipoperoxides (p<0.05) were significantly lower in blood mononuclear cells of the treated group. These observations lead to the hypothesis that the oral CoQ10 plus NADH supplementation could confer potential therapeutic benefits on fatigue and biochemical parameters in CFS. Larger sample trials are warranted to confirm these findings. Antioxid. Redox Signal. 22, 679–685. PMID:25386668

The effects of fatigue on robotic surgical skill training in Urology residents.

PubMed

Mark, James R; Kelly, Douglas C; Trabulsi, Edouard J; Shenot, Patrick J; Lallas, Costas D

2014-09-01

This study reports on the effect of fatigue on Urology residents using the daVinci surgical skills simulator (dVSS). Seven Urology residents performed a series of selected exercises on the dVSS while pre-call and post-call. Prior to dVSS performance a survey of subjective fatigue was taken and residents were tested with the Epworth Sleepiness Scale (ESS). Using the metrics available in the dVSS software, the performance of each resident was evaluated. The Urology residents slept an average of 4.07 h (range 2.5-6 h) while on call compared to an average of 5.43 h while not on call (range 3-7 h, p = 0.08). Post-call residents were significantly more likely to be identified as fatigued by the Epworth Sleepiness Score than pre-call residents (p = 0.01). Significant differences were observed in fatigued residents performing the exercises, Tubes and Match Board 2 (p = 0.05, 0.02). Additionally, there were significant differences in the total number of critical errors during the training session (9.29 vs. 3.14, p = 0.04). Fatigue in post-call Urology residents leads to poorer performance on the dVSS simulator. The dVSS may become a useful instrument in the education of fatigued residents and a tool to identify fatigue in trainees.

Stereoscopic visual fatigue assessment and modeling

NASA Astrophysics Data System (ADS)

Wang, Danli; Wang, Tingting; Gong, Yue

2014-03-01

Evaluation of stereoscopic visual fatigue is one of the focuses in the user experience research. It is measured in either subjective or objective methods. Objective measures are more preferred for their capability to quantify the degree of human visual fatigue without being affected by individual variation. However, little research has been conducted on the integration of objective indicators, or the sensibility of each objective indicator in reflecting subjective fatigue. The paper proposes a simply effective method to evaluate visual fatigue more objectively. The stereoscopic viewing process is divided into series of sessions, after each of which viewers rate their visual fatigue with subjective scores (SS) according to a five-grading scale, followed by tests of the punctum maximum accommodation (PMA) and visual reaction time (VRT). Throughout the entire viewing process, their eye movements are recorded by an infrared camera. The pupil size (PS) and percentage of eyelid closure over the pupil over time (PERCLOS) are extracted from the videos processed by the algorithm. Based on the method, an experiment with 14 subjects was conducted to assess visual fatigue induced by 3D images on polarized 3D display. The experiment consisted of 10 sessions (5min per session), each containing the same 75 images displayed randomly. The results show that PMA, VRT and PERCLOS are the most efficient indicators of subjective visual fatigue and finally a predictive model is derived from the stepwise multiple regressions.

Reduction of Burnout in Mental Health Care Providers Using the Provider Resilience Mobile Application.

PubMed

Wood, Amanda Ernst; Prins, Annabel; Bush, Nigel E; Hsia, Jennifer F; Bourn, Laura E; Earley, Michael D; Walser, Robyn D; Ruzek, Josef

2017-05-01

This pilot study examined the usability, acceptability, and effectiveness of a free Provider Resilience (PR) mobile application (app) designed by the National Center for Telehealth and Technology to reduce provider burnout. Outpatient mental health providers (N = 30) used the PR app for 1 month. Participants rated the PR app on the System Usability Scale with an overall score of 79.7, which is in the top quartile for usability. Results of paired sample t tests on the Professional Quality of Life Scale indicated significant decreases on the Burnout (t = 3.65, p < .001) and Compassion Fatigue (t = 4.54, p < .001) subscales. The Provider Resilience app shows promise in reducing burnout and compassion fatigue in mental health care providers.

Major Effects of Nonmetallic Inclusions on the Fatigue Life of Disk Superalloy Demonstrated

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; Bonacuse, Peter J.; Barrie, Robert L.

2002-01-01

The fatigue properties of modern powder metallurgy disk alloys can vary because of the different steps of materials and component processing and machining. Among these variables, the effects of nonmetallic inclusions introduced during the powder atomization and handling processes have been shown to significantly degrade low-cycle fatigue life. The levels of inclusion contamination have, therefore, been reduced to less than 1 part per million in state-of-the-art nickel disk powder-processing facilities. Yet the large quantities of compressor and turbine disks weighing from 100 to over 1000 lb have enough total volume and surface area for these rare inclusions to still be present and limit fatigue life. The objective of this study was to investigate the effects on fatigue life of these inclusions, as part of the Crack Resistant Disk Materials task within the Ultra Safe Propulsion Project. Inclusions were carefully introduced at elevated levels in a nickel-base disk superalloy, U720, produced using powder metallurgy processing. Multiple strain-controlled fatigue tests were then performed on extracted test specimens at 650 C. Analyses were performed to compare the low-cycle fatigue lives and failure initiation sites as functions of inclusion content and fatigue conditions. Powder of the nickel-base superalloy U720 was atomized in argon at Special Metals Corporation, Inc., using production-scale high-cleanliness powder-processing facilities and handling practices. The powder was then passed through a 270-mesh screen. One portion of this powder was set aside for subsequent consolidation without introduced inclusions. Two other portions of this powder were seeded with alumina inclusions. Small, polycrystalline soft (Type 2) inclusions of about 50 mm diameter were carefully prepared and blended into one powder lot, and larger hard (Type 1) inclusions of about 150 mm mean diameter were introduced into the other seeded portion of powder. All three portions of powder were then sealed in separate containers, hot isostatically pressurized, extruded, forged into subscale disks, and heat treated. Low-cycle-fatigue specimens were then extracted, machined, and tested. Fatigue tests were performed at 650 C in closed-loop servohydraulic testing machines using induction heating and axial extensometers. All tests were continued to failure, and fractographic evaluations were performed on all specimens to determine the crack initiation sites. A large majority of the failures in specimens with introduced inclusions occurred at cracks initiating from inclusions at the specimen surface, as shown for each type of inclusion in the following bar chart. The inclusions significantly reduced fatigue life from unseeded material levels, as shown in the bar chart. These effects were found to depend on the strain range, strain ratio, and inclusion size. Tests at lower strain ranges and higher strain ratios resulted in larger effects of inclusions on life. Inclusion effects on life were thereby maximized in tests at the lowest strain range of 0.6 percent and the most positive strain ratio of 0.5. Under these conditions, small Type 2 inclusions reduced life substantially-- about 20 times, whereas large Type 1 inclusions dramatically reduced life 100 times. These results clearly demonstrate that it is essential to include the effects of inclusions for realistic predictions of disk fatigue life. Important issues, including temperature dependence, crack initiation versus propagation, surface treatments, realistic disk features and machining, and realistic disk spin testing will be addressed to accurately model inclusion effects on disk fatigue life. Fatigue life varied from well over 105 cycles for no inclusions to a little over 103 cycles for 100-micrometer inclusions. A single crack initiating at a surface-connected seeded inclusion caused failure in each case.

Effect of environment on low-cycle fatigue of a nickel-titanium instrument.

PubMed

Cheung, Gary S P; Shen, Ya; Darvell, Brian W

2007-12-01

This study examined the low-cycle fatigue (LCF) behavior of a nickel-titanium (NiTi) engine-file under various environmental conditions. One brand of NiTi instrument was subjected to rotational-bending fatigue in air, deionized water, sodium hypochlorite, or silicone oil. The curvature of each instrument, diameter of the fracture cross-section, and the number of rotations to failure were determined. The strain-life relationship in the LCF region was examined by using one-way analysis of variance, and the number of crack origins with chi2, for differences between groups. The results showed a linear relationship, on logarithmic scales, between the LCF life and the surface strain amplitude; regression line slopes were significantly different between noncorrosive (air, silicone oil) and corrosive (water, hypochlorite) environments (P < .05), as well as number of crack origins (P < .05). Hypochlorite was more detrimental to fatigue life than water. In conclusion, environmental conditions significantly affect the LCF behavior of NiTi rotary instruments. Fatigue testing of NiTi engine-files should be in a service-like environment.

Microstructurally-sensitive fatigue crack nucleation in Ni-based single and oligo crystals

NASA Astrophysics Data System (ADS)

Chen, Bo; Jiang, Jun; Dunne, Fionn P. E.

2017-09-01

An integrated experimental, characterisation and computational crystal plasticity study of cyclic plastic beam loading has been carried out for nickel single crystal (CMSX4) and oligocrystal (MAR002) alloys in order to assess quantitatively the mechanistic drivers for fatigue crack nucleation. The experimentally validated modelling provides knowledge of key microstructural quantities (accumulated slip, stress and GND density) at experimentally observed fatigue crack nucleation sites and it is shown that while each of these quantities is potentially important in crack nucleation, none of them in its own right is sufficient to be predictive. However, the local (elastic) stored energy density, measured over a length scale determined by the density of SSDs and GNDs, has been shown to predict crack nucleation sites in the single and oligocrystals tests. In addition, once primary nucleated cracks develop and are represented in the crystal model using XFEM, the stored energy correctly identifies where secondary fatigue cracks are observed to nucleate in experiments. This (Griffith-Stroh type) quantity also correctly differentiates and explains intergranular and transgranular fatigue crack nucleation.

Effects of meditation on anxiety, depression, fatigue, and quality of life of women undergoing radiation therapy for breast cancer.

PubMed

Kim, Yeon Hee; Kim, Hwa Jung; Ahn, Seung Do; Seo, Yun Jeong; Kim, So Hee

2013-08-01

To investigate the effects of meditation on anxiety, depression, fatigue, and quality of life in women who are receiving radiation therapy for breast cancer. Randomized, non-program controlled, parallel intervention clinical trial. The ASAN Cancer Center located in Seoul, Korea. The subjects of this study included 102 female breast cancer patients who had undergone breast-conserving surgery; these female patients were randomized into equally assigned meditation control groups, with each group consisting of 51 patients. The test group received a total of 12 meditation therapy sessions during their 6-week radiation therapy period, and the control group underwent only a conventional radiation therapy. The tools used to evaluate the effects of meditation were Hospital Anxiety and Depression scale, Revised Piper Fatigue scale, and European Organization for Research and Treatment of Cancer-Quality of Life Core-30. The results were analyzed based on the principles of intention-to-treat analysis, and, as a corollary analysis, per-protocol analysis was conducted. The breast cancer patients who received meditation therapy compared with the non-intervention group saw improvements in reduction of anxiety (p=.032), fatigue (p=.030), and improvement in global quality of life (p=.028). Based on the results of this study, an affirmation can be made that meditation can be used as a non-invasive intervention treatment for improving fatigue, anxiety, quality of life, and emotional faculties of women with breast cancer. Copyright © 2013 Elsevier Ltd. All rights reserved.

The impact of depression on fatigue in patients with haemodialysis: a correlational study.

PubMed

Bai, Yu-Ling; Lai, Liu-Yuan; Lee, Bih-O; Chang, Yong-Yuan; Chiou, Chou-Ping

2015-07-01

To investigate the fatigue levels and important fatigue predictors for patients undergoing haemodialysis. Fatigue is a common symptom for haemodialysis patients. With its debilitating and distressing effects, it impacts patients in terms of their quality of life while also increasing their mortality rate. A descriptive correlational study. Convenience sampling was conducted at six chosen haemodialysis centres in Southern Taiwan. Data were collected via a structured questionnaire from 193 haemodialysis patients. The scales involved in this study were socio-demographic details, the Center for Epidemiologic Studies Depression Scale, and the Fatigue Scale for haemodialysis patients. Data analysis included percentages, means, standard deviations and hierarchical multiple regression analysis. The fatigue level for haemodialysis patients was in the moderate range. Results from the hierarchical multiple regression analysis indicated that age, employment status, types of medications, physical activity and depression were significant. Of those variables, depression had the greatest impact on the patients' fatigue level, accounting for up to 30·6% of the explanatory power. The total explanatory power of the regression model was 64·2%. This study determined that for haemodialysis patients, unemployment, increased age, taking more medications or lower exercise frequencies resulted in more severe depression, which translated in turn to higher levels of fatigue. Among all these factors, depression had the greatest impact on the patients' fatigue levels. Not only is this finding beneficial to future studies on fatigue as a source of reference, it is also helpful in our understanding of important predictors relating to fatigue in the everyday lives of haemodialysis patients. It is recommended that when caring for fatigued patients, more care should be dedicated to their psychological states, and assistance should be provided in a timely way so as to reduce the amount of fatigue suffered. © 2015 John Wiley & Sons Ltd.

The association of sociodemographic and objectively-assessed disease variables with fatigue in systemic sclerosis: an analysis of 785 Canadian Scleroderma Research Group Registry patients.

PubMed

Levis, Brooke; Kwakkenbos, Linda; Hudson, Marie; Baron, Murray; Thombs, Brett D

2017-02-01

Fatigue is prevalent among patients with systemic sclerosis (SSc). To date, studies investigating fatigue in SSc have been hampered by the instruments used to measure fatigue in SSc and have included patient-reported rather than objectively-rated measures of disease. The Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale is a validated measure for assessing fatigue in SSc that, compared to other instruments, provides good coverage of the full range of the fatigue spectrum. The objective of this study was to assess sociodemographic and objectively-rated disease-related associates of fatigue, as measured by the FACIT-F, in a large sample of patients with SSc. Fatigue was assessed using the FACIT-F scale. Disease severity was assessed using Medsger's severity scale. Multivariable linear regression was performed to assess the independent associations between sociodemographic and medical variables and fatigue. Among 785 patients, the mean FACIT-F score was 32.2 (SD = 12.1). Being age 40-49 (reference = 60+; standardized regression coefficient (β) = -0.11), less than post-secondary education (β = 0.07), having more medical comorbidities (β = -0.11) and more severe muscle (β = -0.10), gastrointestinal (β = -0.15), lung (β = -0.13), and general system disease severity (β = -0.13) were independently associated with more fatigue (p < 0.05). Fatigue in SSc was independently associated with more severe disease. These data contribute to a better understanding of fatigue in SSc and help inform patient-centered research in SSc.

Dysphagia-related quality of life in oculopharyngeal muscular dystrophy: Psychometric properties of the SWAL-QOL instrument.

PubMed

Youssof, Sarah; Romero-Clark, Carol; Warner, Teddy; Plowman, Emily

2017-07-01

The Swallowing Quality of Life instrument (SWAL-QOL) is a patient-reported outcome measure of swallowing-related quality of life (SR-QoL). Its psychometric properties in oculopharyngeal muscular dystrophy (OPMD) are not known. We administered the SWAL-QOL to U.S. OPMD Registry participants. We described SR-QoL profiles and assessed reliability and validity. The mean composite score in 113 individuals with OPMD was 54.4 ± 20.7, indicating moderate impairment. Severe impairments were observed in eating duration, burden, and fatigue scales. Internal consistency reliability of all scales was found to be satisfactory, and 9 of 10 scales demonstrated adequate test-retest reliability. Data confirmed 86% of hypotheses, supporting construct validity. The SWAL-QOL limitations in OPMD include: floor/ceiling effects in 7 of 10 scales and low specificity of sleep, fatigue, and communication scales for dysphagia. SR-QoL is reduced in OPMD. Given several limitations of the SWAL-QOL, development of an improved dysphagia-specific QoL instrument for OPMD is warranted. Muscle Nerve 56: 28-35, 2017. © 2016 Wiley Periodicals, Inc.

Fatigue Life Estimation under Cumulative Cyclic Loading Conditions

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh; McGaw, Michael A; Halford, Gary R.

1999-01-01

The cumulative fatigue behavior of a cobalt-base superalloy, Haynes 188 was investigated at 760 C in air. Initially strain-controlled tests were conducted on solid cylindrical gauge section specimens of Haynes 188 under fully-reversed, tensile and compressive mean strain-controlled fatigue tests. Fatigue data from these tests were used to establish the baseline fatigue behavior of the alloy with 1) a total strain range type fatigue life relation and 2) the Smith-Wastson-Topper (SWT) parameter. Subsequently, two load-level multi-block fatigue tests were conducted on similar specimens of Haynes 188 at the same temperature. Fatigue lives of the multi-block tests were estimated with 1) the Linear Damage Rule (LDR) and 2) the nonlinear Damage Curve Approach (DCA) both with and without the consideration of mean stresses generated during the cumulative fatigue tests. Fatigue life predictions by the nonlinear DCA were much closer to the experimentally observed lives than those obtained by the LDR. In the presence of mean stresses, the SWT parameter estimated the fatigue lives more accurately under tensile conditions than under compressive conditions.

A population-based study of associations between current posttraumatic stress symptoms and current fatigue.

PubMed

Lerdal, Anners; Lee, Kathryn A; Rokne, Berit; Knudsen, Øistein; Wahl, Astrid K; Dahl, Alv A

2010-10-01

This study explores current experience with posttraumatic stress disorder (PTSD) symptoms and other variables (sociodemographic, mental distress, somatic morbidity, self-rated health, and quality of life [QoL]) in relation to fatigue. A representative sample of the Norwegian population (N = 3,944) was invited to participate in a mailed survey, and 1,857 (47%) returned valid responses on the questionnaire that included the Fatigue Severity Scale and the Posttraumatic Symptom Scale-10. Posttraumatic stress disorder symptoms showed a strong association with fatigue in univariate (β = .41) and multivariate analyses (β = .33). Associations between psychosocial health variables, QoL, and fatigue were confirmed. However, PTSD symptoms showed the strongest association with fatigue in the analyses. Findings need to be replicated in other population samples and in clinical samples with PTSD and fatigue.

A Micro-Mechanism-Based Continuum Corrosion Fatigue Damage Model for Steels

NASA Astrophysics Data System (ADS)

Sun, Bin; Li, Zhaoxia

2018-05-01

A micro-mechanism-based corrosion fatigue damage model is developed for studying the high-cycle corrosion fatigue of steel from multi-scale viewpoint. The developed physical corrosion fatigue damage model establishes micro-macro relationships between macroscopic continuum damage evolution and collective evolution behavior of microscopic pits and cracks, which can be used to describe the multi-scale corrosion fatigue process of steel. As a case study, the model is used to predict continuum damage evolution and number density of the corrosion pit and short crack of steel component in 5% NaCl water under constant stress amplitude at 20 kHz, and the numerical results are compared with experimental results. It shows that the model is effective and can be used to evaluate the continuum macroscopic corrosion fatigue damage and study microscopic corrosion fatigue mechanisms of steel.

A Micro-Mechanism-Based Continuum Corrosion Fatigue Damage Model for Steels

NASA Astrophysics Data System (ADS)

Sun, Bin; Li, Zhaoxia

2018-04-01

A micro-mechanism-based corrosion fatigue damage model is developed for studying the high-cycle corrosion fatigue of steel from multi-scale viewpoint. The developed physical corrosion fatigue damage model establishes micro-macro relationships between macroscopic continuum damage evolution and collective evolution behavior of microscopic pits and cracks, which can be used to describe the multi-scale corrosion fatigue process of steel. As a case study, the model is used to predict continuum damage evolution and number density of the corrosion pit and short crack of steel component in 5% NaCl water under constant stress amplitude at 20 kHz, and the numerical results are compared with experimental results. It shows that the model is effective and can be used to evaluate the continuum macroscopic corrosion fatigue damage and study microscopic corrosion fatigue mechanisms of steel.

Thermo-elastic nondestructive evaluation of fatigue damage in PMR-15 resin

NASA Astrophysics Data System (ADS)

Welter, J. T.; Sathish, S.; Tandon, G. P.; Schehl, N.; Cherry, M.; Nalladega, V.; Lindgren, E. A.; Hall, R.

2012-05-01

Thermoset polyimide resins are used as the polymer matrix in high temperature composites for aerospace applications such as engine shrouds. At these locations the components have to withstand high temperatures and significant vibration. A number of studies have investigated the effects of thermal exposure on mechanical properties of polyimide resins, and the effects of fatigue on thermoplastics have been discussed at length. However, the effects of fatigue on thermosets, in particular polyimides, have largely been overlooked. In this paper we present studies of nondestructive evaluation of fatigue damage in a thermoset polyimide resin, PMR-15, performed by measuring the changes in the evolution of heat in the samples during cyclic loading. The temperature changes are measured using a high sensitivity IR camera as a function of number of fatigue cycles. Interrupted fatigue tests were performed on four samples. The temperature rise during an increment of fatigue cycling shows two linear regions each with a different slope (region 1 and region 2). Region 1 remains constant for every increment of fatigue, while region 2 increases. The onset of region 2 occurs at the same increase in temperature due to hysteretic heating for all samples. Experimental observations are explained using a phenomenological two phase model based on crosslinking density variations in observed in other thermoset resins at microscopic scales. The results of these experiments are discussed in reference to utilizing this technique for detection and evaluation of fatigue in PMR-15 resin and composites.

Prevalence of iron deficiency on ICU discharge and its relation with fatigue: a multicenter prospective study.

PubMed

Lasocki, Sigismond; Chudeau, Nicolas; Papet, Thibaut; Tartiere, Deborah; Roquilly, Antoine; Carlier, Laurence; Mimoz, Olivier; Seguin, Philippe; Malledant, Yannick; Asehnoune, Karim; Hamel, Jean François

2014-09-30

Prevalence of iron deficiency (ID) at intensive care (ICU) admission is around 25 to 40%. Blood losses are important during ICU stay, leading to iron losses, but prevalence of ID at ICU discharge is unknown. ID has been associated with fatigue and muscular weakness, and may thus impair post-ICU rehabilitation. This study assessed ID prevalence at ICU discharge, day 28 (D28) and six months (M6) after and its relation with fatigue. We conducted this prospective, multicenter observational study at four University hospitals ICUs. Anemic (hemoglobin (Hb) less than 13 g/dL in male and less than 12 g/dL in female) critically ill adult patients hospitalized for at least five days had an iron profile taken at discharge, D28 and M6. ID was defined as ferritin less than 100 ng/L or less than 300 ng/L together with a transferrin saturation less than 20%. Fatigue was assessed by numerical scale and the Multidimensional Fatigue Inventory-20 questionnaire at D28 and M6 and muscular weakness by a hand grip test at ICU discharge. Among 107 patients (men 77%, median (IQR) age 63 (48 to 73) years) who had a complete iron profile at ICU discharge, 9 (8.4%) had ID. At ICU discharge, their hemoglobin concentration (9.5 (87.7 to 10.3) versus 10.2 (92.2 to 11.7) g/dL, P =0.09), hand grip strength (52.5 (30 to 65) versus 49.5 (15.5 to 67.7)% of normal value, P =0.61) and visual analog scale fatigue scale (57 (40 to 80) versus 60 (47.5 to 80)/100, P =0.82) were not different from non-ID patients. At D28 (n =80 patients) and M6 (n =78 patients), ID prevalence increased (to 25 and 35% respectively) while anemia prevalence decreased (from 100% to 80 and 25% respectively, P <0.0001). ID was associated with increased fatigue at D28, after adjustment for main confounding factors, including anemia (regression coefficient (95%CI), 3.19 (0.74 to 5.64), P =0.012). At M6, this association disappeared. The prevalence of ID increases from 8% at discharge to 35% six months after prolonged ICU stay (more than five days). ID was associated with increased fatigue, independently of anemia, at D28.

Fatigue, Creep-Fatigue, and Thermomechanical Fatigue Life Testing of Alloys

NASA Technical Reports Server (NTRS)

Halford, Gary R.; Lerch, Bradley A.; McGaw, Michael A.

2000-01-01

The fatigue crack initiation resistance of an alloy is determined by conducting a series of tests over a range of values of stress amplitude or strain range. The observed number of cycles to failure is plotted against the stress amplitude or strain range to obtain a fatigue curve. The fatigue properties quoted for an alloy are typically the constants used in the equation(s) that describe the fatigue curve. Fatigue lives of interest may be as low as 10(exp 2) or higher than 10(exp 9) cycles. Because of the enormous scatter associated with fatigue, dozens of tests may be needed to confidently establish a fatigue curve, and the cost may run into several thousands of dollars. To further establish the effects on fatigue life of the test temperature, environment, alloy condition, mean stress effects, creep-fatigue effects, thermomechanical cycling, etc. requires an extraordinarily large and usually very costly test matrix. The total effort required to establish the fatigue resistance of an alloy should not be taken lightly. Fatigue crack initiation tests are conducted on relatively small and presumed to be initially crack-free, samples of an alloy that are intended to be representative of the alloy's metallurgical and physical condition. Generally, samples are smooth and have uniformly polished surfaces within the test section. Some may have intentionally machined notches of well-controlled geometry, but the surface at the root of the notch is usually not polished. The purpose of polishing is to attain a reproducible surface finish. This is to eliminate surface finish as an uncontrolled variable. Representative test specimen geometries will be discussed later. Test specimens are cyclically loaded until macroscopically observable cracks initiate and eventually grow to failure. Normally, the fatigue failure life of a specimen is defined as the number of cycles to separation of the specimen into two pieces. Alternative definitions are becoming more common, particularly for low-cycle fatigue testing, wherein some prescribed indication of impending failure due to cracking is adopted. Specific criteria will be described later. As a rule, cracks that develop during testing are not measured nor are the test parameters intentionally altered owing to the presence of cracking.

Systematic content evaluation and review of measurement properties of questionnaires for measuring self-reported fatigue among older people.

PubMed

Egerton, Thorlene; Riphagen, Ingrid I; Nygård, Arnhild J; Thingstad, Pernille; Helbostad, Jorunn L

2015-09-01

The assessment of fatigue in older people requires simple and user-friendly questionnaires that capture the phenomenon, yet are free from items indistinguishable from other disorders and experiences. This study aimed to evaluate the content, and systematically review and rate the measurement properties of self-report questionnaires for measuring fatigue, in order to identify the most suitable questionnaires for older people. This study firstly involved identification of questionnaires that purport to measure self-reported fatigue, and evaluation of the content using a rating scale developed for the purpose from contemporary understanding of the construct. Secondly, for the questionnaires that had acceptable content, we identified studies reporting measurement properties and rated the methodological quality of those studies according to the COSMIN system. Finally, we extracted and synthesised the results of the studies to give an overall rating for each questionnaire for each measurement property. The protocol was registered with PROSPERO (CRD42013005589). Of the 77 identified questionnaires, twelve were selected for review after content evaluation. Methodological quality varied, and there was a lack of information on measurement error and responsiveness. The PROMIS-Fatigue item bank and short forms perform the best. The FACIT-Fatigue scale, Parkinsons Fatigue Scale, Perform Questionnaire, and Uni-dimensional Fatigue Impact Scale also perform well and can be recommended. Minor modifications to improve performance are suggested. Further evaluation of unresolved measurement properties, particularly with samples including older people, is needed for all the recommended questionnaires.

High validity and reliability of the PedsQL™ Multidimensional Fatigue Scale for Brazilian children with cancer.

PubMed

Nascimento, Lucila Castanheira; Nunes, Michelle Darezzo Rodrigues; Rocha, Ester Leonardo; Bomfim, Emiliana Omena; Floria-Santos, Milena; Dos Santos, Claudia Benedita; Dos Santos, Danielle Maria de Souza Serio; de Lima, Regina Aparecida Garcia

2015-01-01

Among the main factors that affect patients' quality of life, fatigue is a significant symptom experienced by children during treatment. Despite the high incidence, there has been no validated scale to evaluate fatigue in children with cancer in Brazil. The purpose of this study was to examine the psychometric properties of the PedsQL™ Multidimensional Fatigue Scale, using self-reports of Brazilian children, 8 to 18 years of age, and proxy reports. A cross-sectional method was used to collect data from 216 subjects over an 18-month period. Reliability ranged from .70 to .90 except for sleep/rest fatigue, self-report (α = .55). No floor or ceiling effects were found in any dimension. Convergent validity was higher than .40 and divergent validity had 100% adjustment. The root mean square error of approximation was acceptable. The comparative fit index was lower than expected. The agreement between self and proxy responses was weak and moderate. The results demonstrate the reliability and validity of the Brazilian version in children with cancer. This is the first validated scale that assesses fatigue in Brazilian children and adolescents with cancer. © 2014 by Association of Pediatric Hematology/Oncology Nurses.

Fatigue in Intensive Care Nurses and Related Factors.

PubMed

Çelik, Sevim; Taşdemir, Nurten; Kurt, Aylin; İlgezdi, Ebru; Kubalas, Özge

2017-10-01

Fatigue negatively affects the performance of intensive care nurses. Factors contributing to the fatigue experienced by nurses include lifestyle, psychological status, work organization and sleep problems. To determine the level of fatigue among nurses working in intensive care units and the related factors. This descriptive study was conducted with 102 nurses working in intensive care units in the West Black Sea Region of Turkey. Data were collected between February and May 2014 using a personal information form, the Visual Analogue Scale for Fatigue (VAS-F), the Hospital Anxiety and Depression Scale and the Pittsburg Sleep Quality Index. The intensive care nurses in the study were found to be experiencing fatigue. Significant correlations were observed between scores on the VAS-F Fatigue and anxiety (p=0.01), depression (p=0.002), and sleep quality (p<0.001). Anxiety, depression and quality of sleep were significantly affected by the intensive care nurses' levels of fatigue. These results can be of benefit in taking measures which may be used to reduce fatigue in nurses, especially the fatigue related to work organization and social life.

[Counseling in the prevention of fatigue in psychiatric nurses].

PubMed

Greeff, M; Poggenpoel, M

1991-12-01

Nursing is a stressful activity and therefore it is necessary for nurses to develop effective coping mechanisms, or to strengthen existing ones in a healthy manner, in order to be capable of dealing with stress, arising from their personal and professional lives. It is, however, not solely stress itself which predisposes nurses to fatigue (physical, psychological and emotional exhaustion) but rather the chronic nature and excessive amount of stressors which place excessive demands on the energy resources and coping, mechanisms of nurses resulting in the ineffective handling of stress which in turn leads to the eventual development of fatigue. The detrimental results of this experience are, however, not confined to the nurse herself, but extends further to the patient and the organization. Thus, if fatigue is not controlled or dealt with, all parties and organizations concerned could suffer. This research covers the accompaniment function of the psychiatric nurse specialist in the prevention of fatigue in psychiatric nurses by strengthening their mental preparedness. As a possible solution to the experience of fatigue, a structured, accompanied program of three days was offered to a group of psychiatric nurses. The Solomon four group design was followed in order to eliminate influences on the subjects resulting from the completion of the self-evaluation scale as pre-test. The data which was obtained from the test results was statistically compared. Results showed that there was a definite decrease in the levels of fatigue experienced by the experimental group that received the structured accompanied programme, but no real change occurred in the control group that had merely been provided with relevant literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Cumulative fatigue damage behavior of MAR M-247

NASA Technical Reports Server (NTRS)

Mcgaw, Michael A.; Halford, Gary R.; Kalluri, Sreeramesh

1991-01-01

The objective was to examine the room temperature fatigue and nonlinear cumulative fatigue damage behavior of the cast nickel-based superalloy, MAR M-247. The fatigue test matrix consisted of single-level, fully reversed fatigue experiments. Two series of tests were performed: one of the two baseline fatigue LCF (Low-Cycle Fatigue) life levels was used in the first loading block, and the HCF (High-Cycle Fatigue) baseline loading level was used in the second block in each series. For each series, duplicate tests were performed at each applied LCF life fraction.

Effect of outdoor exposure at ambient and elevated temperatures on fatigue life of Ti-6Al-4V titanium alloy sheet in the annealed and the solution treated and aged condition

NASA Technical Reports Server (NTRS)

Phillips, E. P.

1974-01-01

Specimens of Ti-6Al-4V titanium alloy sheet in the annealed and the solution-treated and aged heat-treatment condition were exposed outdoors at ambient and 560 K (550 F) temperatures to determine the effect of outdoor exposure on fatigue life. Effects of exposure were determined by comparing fatigue lives of exposed specimens to those of unexpected specimens. Two procedures for fatigue testing the exposed specimens were evaluated: (1) fatigue tests conducted outdoors by applying 1200 load cycles per week until failure occurred and (2) conventional fatigue tests (continuous cycling until failure occurred) conducted indoors after outdoor exposure under static load. The exposure period ranged from 9 to 28 months for the outdoor fatigue-test group and was 24 months for the static-load group. All fatigue tests were constant-amplitude bending of specimens containing a drilled hole (stress concentration factor of 1.6). The results of the tests indicate that the fatigue lives of solution-treated and aged specimens were significantly reduced by the outdoor exposure at 560 K but not by the exposure at ambient temperature. Fatigue lives of the annealed specimens were essentially unaffected by the outdoor exposure at either temperature. The two test procedures - outdoor fatigue test and indoor fatigue test after outdoor exposure - led to the same conclusions about exposure effects.

The effectiveness of exercise-based rehabilitation to patients with myeloproliferative neoplasms-An explorative study.

PubMed

Pedersen, Kasper Mønsted; Zangger, Graziella; Brochmann, Nana; Grønfeldt, Birk Mygind; Zwisler, Ann-Dorthe; Hasselbalch, Hans Carl; Tang, Lars Hermann

2018-06-11

The aim of the study was to determine the impact of an interdisciplinary exercise-based rehabilitation intervention on fatigue and quality of life (QOL) in patients with Philadelphia-negative myeloproliferative neoplasms (MPNs). At the Danish Knowledge Centre for Rehabilitation and Palliative Care, a 5-day interdisciplinary exercise-based rehabilitation intervention was carried out on 48 patients with MPN. It was followed by 12 weeks of self-exercising prior to follow-up. Initially and at follow-up, participants filled out validated questionnaires; Brief Fatigue Inventory, Multidimensional Fatigue Inventory, European Organization for Research and Treatment of Cancer Quality-of-Life questionnaire, Myeloproliferative Neoplasm Symptom Assessment Form and Hospital Anxiety and Depression Scale. Maximal oxygen uptake and muscular strength were tested as well. Paired t test was used to compare scores between baseline and follow-up. In total, 45 participants (94%) completed the follow-up. No significant differences were observed on fatigue or QOL when comparing baseline and follow-up. Mean maximal oxygen uptake increased from 27.2 to 33.6 ml O 2 · kg -1  ·min -1 (p < 0.001). Handgrip strength (p = 0.01) and the 30-s chair-stand test (p < 0.001) improved as well. No changes were found regarding levels of fatigue and QOL. However, we observed a significant increase in the physical capacity. Our observations call for further studies investigating the effects of non-pharmacological approaches in patients with MPN. © 2018 John Wiley & Sons Ltd.

[Cancer related fatigue in patients with breast cancer after chemotherapy and coping style].

PubMed

Jiang, Pinglan; Wang, Shuhong; Jiang, Dongmei; Yu, Lingli

2011-04-01

To study the relevance between cancer related fatigue and coping styles in breast cancer patients after chemotherapy. A survey was conducted in 396 patients with breast cancer after chemotherapy on cancer related fatigue scale and Jalowiec coping scale, and the relation was analyzed. The rate of overall fatigue in breast cancer patients was 96.97%, mostly moderate fatigue. The rate of fatigue dimensions from high to low was physical fatigue, feeling fatigue and cognitive fatigue, respectively. The score of coping styles in patients with breast cancer after chemotherapy from high to low was optimistic coping, facing bravely, support seeking, self-reliance, emotional catharsis, avoidance, fatalism, and conservation. The most widely used coping style was optimistic coping style, and the least was emotional catharisis. There was a positive correlation between coping style of emotional catharsis and cancer related fatigue of all dimensions (P<0.01). There was a negative correlation between emotional fatigue and optimistic,facing bravely, support seeking, self-reliance, or conservation (P<0.05). There was also a negative correlation between physical fatigue and optimistic or support seeking (P<0.05), but there was a positive correlation between avoidance or fatalism and the dimensions of general fatigue, physical fatigue, and cognitive fatigue (P<0.05). There is prevalent cancer related fatigue in patients with breast cancer after chemotherapy. We should guide the patients to more active coping styles, to enhance the ability of psychological adaption in patients, reduce cancer related fatigue, and improve the quality of life.

The Relationship Among Change Fatigue, Resilience, and Job Satisfaction of Hospital Staff Nurses.

PubMed

Brown, Robin; Wey, Howard; Foland, Kay

2018-05-01

The purpose of this study was to examine relationships between change fatigue, resilience, and job satisfaction among novice and seasoned hospital staff nurses. Health care is typified by change. Frequent and vast changes in acute care hospitals can take a toll on nurses and cause change fatigue, which has been largely overlooked and under-researched. A descriptive correlational design was employed with 521 hospital staff nurses in one midwestern state. Participants completed three online surveys: (a) Change Fatigue Scale, (b) Connor-Davidson Resilience Scale, and (c) McCloskey/Mueller Satisfaction Scale. In a multiple regression model, job satisfaction had a statistically significant negative association with change fatigue (p < .001) and significant positive association with resilience (p < .001). A linear trend was found with hospital size (number of beds) and change fatigue (p = .001) and education level and resilience (p = .03). The results are consistent with job satisfaction among hospital nursing staff being negatively influenced by change fatigue and positively influenced by resilience, although reverse causal connections are also possible. Change fatigue may be increased by larger hospital size (number of beds), and resilience may be increased by higher educational level of hospital staff nurses. The study advanced the nursing knowledge on change fatigue, resilience, and job satisfaction of staff nurses working in acute care hospitals. Engaging in strategies aimed at preventing change fatigue in nursing staff can enhance workplace environments, job satisfaction, and retention of nurses. © 2018 Sigma Theta Tau International.

Development of a high-frequency and large-stroke fatigue testing system for rubber

NASA Astrophysics Data System (ADS)

Chen, Gang; Wu, Hao; Gao, Jianwen; Lin, Qiang

2017-04-01

The limited capabilities of current fatigue testing machines have resulted in studies on the fatigue behavior of rubber under large-displacement amplitude and high frequency being very sparse. In this study, a fatigue testing system that can carry out large-displacement amplitude and high-frequency fatigue tests on rubber was developed using a moving magnet voice coil motor (MMVCM) actuator, with finite element analysis applied to analyze the thrust of the MMVCM actuator. The results of a series of cyclic tension tests conducted on vulcanized natural rubber specimens using the developed fatigue testing system verify that it has high precision, low noise, large-stroke, and high-frequency characteristics. Further, the load frame with the developed MMVCM actuator is feasible for material testing, especially for large-stroke and high-frequency fatigue tests.

The associations between fatigue, apathy, and depression in Parkinson's disease.

PubMed

Skorvanek, M; Gdovinova, Z; Rosenberger, J; Saeedian, R Ghorbani; Nagyova, I; Groothoff, J W; van Dijk, J P

2015-02-01

Fatigue and apathy are two of the most common and most disabling non-motor symptoms of Parkinson's disease (PD). They have a high coincidence and can often be confused; moreover, their relationship is not fully understood. The aim of our study was to describe the coincidence of apathy with different fatigue domains in the presence/absence of depression and to separately describe the associations of different aspects of primary and secondary fatigue with apathy and other clinical and disease-related factors. A total of 151 non-demented patients with PD were examined using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Starkstein Apathy Scale, Multidimensional Fatigue Inventory (MFI), Beck Depression Inventory-II, and Epworth Sleepiness Scale. The prevalence and severity of fatigue and apathy were significantly higher in depressed PD patients. However, our results show that depression, fatigue, and apathy can be clearly distinguished in PD. Apathy was associated with the MFI's-reduced motivation domain in both depressed and non-depressed patients. However, apathy was associated with mental fatigue aspects only in non-depressed patients, and it was not related to the physical aspects of fatigue in any of the studied groups. Although the pathophysiology of fatigue and apathy in PD is clearly multifactorial, in a proportion of PD patients, these symptoms are associated with depression, dopaminergic depletion in the mesocorticolimbic structures, and disruption of the prefrontal cortex-basal ganglia axis. Therefore, in some PD patients, adequate management of depression and optimal dopaminergic medication may improve both fatigue and apathy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effects of exercise, patient education, and resource support on women with fibromyalgia: An extended long-term study.

PubMed

Karper, William B

2016-01-01

This research examined whether a long-term, multi-component program positively affected physical fitness, pain and fatigue in seven women with fibromyalgia syndrome. These women lived independently in the community. They attended a university-based program 3 days per week, 1 hour per session, year-around for many years. They were evaluated periodically with a fitness test and rating scale regarding pain and fatigue. Results from when they began the program versus most recently are provided. All of these women showed various positive results from participation in the program.

Modafinil May Alleviate Poststroke Fatigue: A Randomized, Placebo-Controlled, Double-Blinded Trial.

PubMed

Poulsen, Mai Bang; Damgaard, Bodil; Zerahn, Bo; Overgaard, Karsten; Rasmussen, Rune Skovgaard

2015-12-01

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. The trial was randomized, double-blinded, and placebo-controlled. Patients were treated with 400-mg modafinil or placebo for 90 days. Assessments were done at inclusion, 30, 90, and 180 days. The primary end point was fatigue at 90 days measured by the Multidimensional Fatigue Inventory-20 general fatigue domain. Secondary end points included the Fatigue Severity Scale, the Montreal Cognitive Assessment, the modified Rankin Scale and the Stroke-specific quality of Life questionnaire. Adult patients with a recent stroke achieving a score of ≥12 on the Multidimensional Fatigue Inventory-20 general fatigue domain were consecutively included. Exclusion criteria were severe cognitive disabilities and contraindications for modafinil treatment. One thousand one hundred twenty-one patients with stroke were screened and 41 patients included, 21 received modafinil. The primary end point, the Multidimensional Fatigue Inventory-20 general fatigue score, did not differ between groups. Patients in the modafinil group obtained better scores on the Fatigue Severity Scale (P=0.02) and in some subscales of the stroke-specific quality of life questionnaire (0.001

Fatigue tests on big structure assemblies of concorde aircraft

NASA Technical Reports Server (NTRS)

Nguyen, V. P.; Perrais, J. P.

1972-01-01

Fatigue tests on structural assemblies of the Concorde supersonic transport aircraft are reported. Two main sections of the aircraft were subjected to pressure, mechanical load, and thermal static tests. The types of fatigue tests conducted and the results obtained are discussed. It was concluded that on a supersonic aircraft whose structural weight is a significant part of the weight analysis, many fatigue and static strength development tests should be made and fatigue and thermal tests of the structures are absolutely necessary.

A path analysis: a model of depression in Korean women with breast cancer-mediating effects of self-esteem and hope.

PubMed

Tae, Young Sook; Heitkemper, Margaret; Kim, Mi Yea

2012-01-01

To test a hypothetical model of depression in Korean women with breast cancer and to test the mediating effects of self-esteem and hope. Cross-sectional design. Participants were recruited from three general hospitals and one cancer hospital in Busan, South Korea. 214 Korean women diagnosed with breast cancer (stages I-III). All participants completed questionnaires (e.g., Zung Self-Rating Depression scale, Herth Hope Scale, Rosenberg Self-Esteem Scale, Health Self-Rating Scale in Health and Activity survey, Kang's Family Support Scale). Based on the literature, Mplus, version 3.0, was used to determine the best depression model with path analysis. Depression, self-esteem, hope, perceived health status, religious beliefs, family support, economic status, and fatigue. Self-esteem was directly affected by perceived health status, religious beliefs, family support, economic status, and fatigue. Hope was directly affected by family support, self-esteem, and how patients perceived their health status. Depression was directly affected by self-esteem and hope. The path analysis model explained 31% of the variance in depression in Korean women with breast cancer. A model of depression in Korean women with breast cancer was developed, and self-esteem and hope were mediating factors of depression. Self-esteem and hope must be considered when developing services to reduce depression in Korean women with breast cancer.

A psychological intervention reduces inflammatory markers by alleviating depressive symptoms: secondary analysis of a randomized controlled trial.

PubMed

Thornton, Lisa M; Andersen, Barbara L; Schuler, Tammy A; Carson, William E

2009-09-01

To test experimentally whether a psychological intervention reduces depression-related symptoms and markers of inflammation among cancer patients and to test one mechanism for the intervention effects. Depression and inflammation are common among cancer patients. Data suggest that inflammation can contribute to depressive symptoms, although the converse remains untested. As part of a randomized clinical trial, newly diagnosed breast cancer patients (n = 45) with clinically significant depressive symptoms were evaluated and randomized to psychological intervention with assessment or assessment only study arms. The intervention spanned 12 months, with assessments at baseline, 4, 8, and 12 months. Mixed-effects modeling tested the hypothesis that the intervention reduced self-reported depressive symptoms (Center for Epidemiological Studies Depression scale, Profile of Mood States Depression and Fatigue subscales, and Medical Outcomes Study-Short Form 36 Bodily Pain subscale) and immune cell numbers that are elevated in the presence of inflammation (white blood cell count, neutrophil count, and helper/suppressor ratio). Mediation analyses tested whether change in depressive symptoms, pain, or fatigue predicted change in white blood cell count, neutrophil count, or the helper/suppressor ratio. The intervention reduced significantly depressive symptoms, pain, fatigue, and inflammation markers. Moreover, the intervention effect on inflammation was mediated by its effect on depressive symptoms. This is the first experiment to test whether psychological treatment effective in reducing depressive symptoms would also reduce indicators of inflammation. Data show that the intervention reduced directly depressive symptoms and reduced indirectly inflammation. Psychological treatment may treat effectively depressive symptoms, pain, and fatigue among cancer patients.

[Treatment on fatigue of patients with postpolio syndrome. A systematic review].

PubMed

Aguila-Maturana, Ana M; Alegre-De Miquel, Cayetano

2010-05-16

Fatigue is the most common symptom and the most disabling in patients with post-polio syndrome. To analyze the effectiveness of various treatments used to improve fatigue syndrome patients post-polio. Systematic review. Is defined a bibliographic search strategy in Medline (from 1961), EMBASE (from 1980), ISI Web of Knowledge and Cochrane Library, Cochrane Central Register of Controlled Trials (CENTRAL), AMED (January 1985), EMI and Physiotherapy Evidence Database (PEDro) until February 2008, the population defined (post-polio syndrome patients) and intervention (any treatment for fatigue in these patients). Outcome were selected as different scales of fatigue and fatigue or vitality dimension scales quality of life. Clinical trials were selected. We retrieved 396 articles, of which 23 were analyzed in detail. Finally, 19 were included in the analysis, a total of 705 patients. Lamotrigine, bromocriptine, aerobics and flexibility exercises, hydrokinesitherapy and technical aids are treatment techniques that reduce more fatigue in these patients.

Psychometric analysis of the Multidimensional Fatigue Inventory in a sample of persons treated for myocardial infarction.

PubMed

Fredriksson-Larsson, Ulla; Brink, Eva; Alsén, Pia; Falk, Kristin; Lundgren-Nilsson, Åsa

2015-01-01

Fatigue after myocardial infarction is a frequent and distressing symptom in the early recovery phase. The purpose of this study is to psychometrically evaluate the Multidimensional Fatigue Inventory (MFI-20). The MFI-20 was evaluated using Rasch analysis. The result showed that the MFI-20 can be used to obtain a global score reflecting an underlying unidimensional trait of fatigue; a transformation of the summarized raw scale scores into interval scale scores could be made. Also, 4 of the 5 original dimensions separately fitted the Rasch model. Calculation of a global score increases the possibility of identifying persons experiencing fatigue after myocardial infarction, and using the MFI-20 dimension scores increases the possibility of determining each person's specific fatigue profile.

The Effects of Hot Corrosion Pits on the Fatigue Resistance of a Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Hazel, Brian; Mourer, David P.

2009-01-01

The effects of hot corrosion pits on low cycle fatigue life and failure modes of the disk superalloy ME3 were investigated. Low cycle fatigue specimens were subjected to hot corrosion exposures producing pits, then tested at low and high temperatures. Fatigue lives and failure initiation points were compared to those of specimens without corrosion pits. Several tests were interrupted to estimate the fraction of fatigue life that fatigue cracks initiated at pits. Corrosion pits significantly reduced fatigue life by 60 to 98 percent. Fatigue cracks initiated at a very small fraction of life for high temperature tests, but initiated at higher fractions in tests at low temperature. Critical pit sizes required to promote fatigue cracking were estimated, based on measurements of pits initiating cracks on fracture surfaces.

Assessment of fatigue in routine care on a Multidimensional Health Assessment Questionnaire (MDHAQ): a cross-sectional study of associations with RAPID3 and other variables in different rheumatic diseases.

PubMed

Castrejon, Isabel; Nikiphorou, Elena; Jain, Ruchi; Huang, Annie; Block, Joel A; Pincus, Theodore

2016-01-01

To characterise associations of fatigue with other variables within a multidimensional health assessment questionnaire (MDHAQ) in routine care of patients with different rheumatic diagnoses. All patients complete MDHAQ, which includes fatigue on a 0-10 visual analogue scale (VAS), and routine assessment of patient index data (RAPID3), a composite of function, pain, and patient global. Physicians complete a RheuMetric checklist which includes 4 VAS for overall global status (DOCGL), inflammation, damage, and distress. Median score for fatigue and other MDHAQ and RheuMetric scores were compared in 4 diagnosis groups: rheumatoid arthritis (RA), osteoarthritis (OA), systemic lupus erythematosus (SLE), and fibromyalgia (FM), using a Kruskall-Wallis test. Associations of fatigue with other variables were analysed using Spearman correlations and multivariate regressions. 612 patients were included: 173 RA, 199 with OA, 146 with SLE, and 94 with FM. Median fatigue was significantly higher in FM (7) than in RA (4), OA (5), and SLE (5). Fatigue was correlated significantly with all other MDHAQ scores, at higher levels in RA and SLE versus OA and FM. Fatigue was correlated significantly with DOCGL in RA, OA, SLE, but not FM. In multivariate analyses, fatigue scores were explained independently by higher pain and symptom number in RA; lower age and higher symptom number in OA; only higher pain in SLE; and none of the variables in FM. Fatigue is common in rheumatic diseases and strongly associated with higher pain and number of symptoms. The MDHAQ provides a useful tool to assess fatigue in clinical settings.

Reliability and validity of a Chinese version of the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF-C).

PubMed

Pien, Li-Chung; Chu, Hsin; Chen, Wen-Chun; Chang, Yu-Shiun; Liao, Yuan-Mei; Chen, Chiung-Hua; Chou, Kuei-Ru

2011-08-01

To examine the psychometric properties of the Chinese version of the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF-C) for use in Chinese-speaking countries. The assessment of fatigue is a challenging task for most researchers because culture may influence perceptions of meaning of fatigue. The lack of examination of the psychometric properties of the fatigue measures across studies limits the scientific rigour for generating additional research on the concept of 'fatigue.' A cross-sectional study. The study recruited 107 cancer inpatients from two medical centres in Taiwan. The MFSI-SF-C was examined using a two step process: (1) Translation and back-translation of the instrument; and (2) Examination of internal consistency reliability, test-retest reliability, content validity and construct validity. The results showed that the Cronbach's α of MFSI-SF-C total scale and subscales ranged between 0·83-0·92. The content validity index was 0·93. The difference between the fatigue of cancer patients and the comparison group of healthy people in the community was significant. The results demonstrated good convergent validity when comparing fatigue with depression and quality of life. Factor analysis confirmed the four dimensions of fatigue: physical, emotional, mental and vigour. It showed moderate intercorrelation between subscales and high factor loadings also helped to clarify the psychometric meaning. The reliability and validity information presented in this article support the use of the Chinese version of the MFSI-SF as a research instrument for measuring fatigue in Chinese populations. This study also provides evidence that the MFSI-SF possesses robust psychometric properties. The MFSI-SF-C is an effective and comprehensive tool for measuring fatigue in Chinese patients with cancer. © 2011 Blackwell Publishing Ltd.

Fatigue in children with juvenile idiopathic arthritis: reliability of the "Pediatric Quality of Life Inventory-Multidimensional Fatigue Scale".

PubMed

Paulo, Luciana Tudech S P; Len, Claudio A; Hilario, Maria Odete E; Pedroso, Soraya A; Vitalle, Maria Sylvia S; Terreri, Maria Teresa

2015-01-01

The aim of the study was (1) to translate the "Pediatric Quality of Life Inventory-Multidimensional Fatigue Scale" (PedsQL-Fatigue) into Brazilian Portuguese language and culture and evaluate its reliability and (2) to measure fatigue among patients with juvenile idiopathic arthritis (JIA): (1) Translation of the PedsQL-Fatigue by two bilingual researchers; (2) Backtranslation into English assessed by the authors of the original version; (3) Pilot study with five patients followed in the Pediatric Rheumatology Outpatient Clinic and their parents; and (4) Field study and assessment of measurement properties (internal consistency, reproducibility, and construct validity). In this stage, the scale was administered to 67 patients with JIA and 63 healthy individuals, aged from 2 to 18 years old, matched by age (from 2 to 4, 5 to 7, 8 to 12, and from 13 to 18 years old). Cronbach's alpha coefficient ranged from 0.6 to 0.8 for children and parents, indicating the instrument's good internal consistency. The scale's construct validity was confirmed by a satisfactory Spearman's coefficient between the PedsQL-Fatigue and the generic PedsQL 4.0 (0.840 for the children and 0.742 for the parents). Reproducibility was also adequate (0.764 for the children and 0.938 for the parents). No differences were found between the scores obtained by the JIA group and control group, though lower scores were observed among patients with clinically active JIA when compared to those without clinical activity. The PedsQL-Fatigue is a valid and reliable tool, and that can be used to measure fatigue among patients with JIA.

Randomized Controlled Trial to Examine the Impact of Aquatic Exercise Training on Functional Capacity, Balance, and Perceptions of Fatigue in Female Patients With Multiple Sclerosis.

PubMed

Kargarfard, Mehdi; Shariat, Ardalan; Ingle, Lee; Cleland, Joshua A; Kargarfard, Mina

2018-02-01

To assess the effects of an 8-week aquatic exercise training program on functional capacity, balance, and perceptions of fatigue in women with multiple sclerosis (MS). Randomized controlled design. Referral center of an MS society. Women (N=32; mean age ± SD, 36.4±8.2y) with diagnosed relapsing-remitting MS. After undergoing baseline testing by a neurologist, participants were allocated to either an intervention (aquatic training program, n=17) or a control group (n=15). The intervention consisted of an 8-week aquatic training program (3 supervised training sessions per week; session duration, 45-60min; 50%-75% estimated maximum heart rate). Six-minute walk test (6-MWT), balance (Berg Balance Scale [BBS]), and perceptions of fatigue (Modified Fatigue Impact Scale; [MFIS]) at baseline and after the 8-week intervention. Differences over time between the experimental and control groups were assessed by a 2×2 (group by time) repeated-measures analysis of variance. Thirty-two women completed the 8-week aquatic training intervention (experimental group, n=17; control group, n=15). All outcome measures improved in the experimental group: 6-MWT performance (pretest mean ± SD, 451±58m; posttest mean ± SD, 503±57m; P<.001); BBS (pretest mean ± SD, 53.59±1.70; posttest mean ± SD, 55.18±1.18; P<.001), and MFIS (pretest mean ± SD, 43.1±14.6; posttest mean ± SD, 32.8±5.9; P<.01). A significant group-by-time interaction was evident between the experimental and control groups for 6-MWT (P<.001, partial eta 2 [η p 2 ]=.551), BBS (P<.001, η p 2 =.423), and MFIS (P<.001, η p 2 =.679). Aquatic exercise training improved functional capacity, balance, and perceptions of fatigue in women with MS. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Subjective Fatigue in Children With Hearing Loss: Some Preliminary Findings

PubMed Central

Hornsby, Benjamin W. Y.; Werfel, Krystal; Camarata, Stephen; Bess, Fred H.

2014-01-01

Purpose In this study, the authors examined the effect of hearing loss on subjective reports of fatigue in school-age children using a standardized measure. Methods As part of a larger ongoing study, the authors obtained subjective ratings of fatigue using the Pediatric Quality of Life Inventory (PedsQL) Multidimensional Fatigue Scale (Varni, Burwinkle, Katz, Meeske, & Dickinson, 2002). This standardized scale provides a measure of general fatigue, sleep/rest fatigue, cognitive fatigue, and an overall composite measure of fatigue. To date, data from 10 children with hearing loss (CHL) and 10 age-matched children with normal hearing (CNH) have been analyzed. Results These preliminary results show that subjective fatigue is increased in school-age children with hearing loss (Cohen's d = 0.78–1.90). In addition, the impact of hearing loss on fatigue in school-age children appears pervasive across multiple domains (general, sleep/rest, and cognitive fatigue). Conclusion School-age CHL reported significantly more fatigue than did CNH. These preliminary data are important given the negative academic and psychosocial consequences associated with fatigue. Further research is needed to determine the underlying mechanisms responsible for this increased fatigue in school-age children with hearing loss, and to identify factors that may modulate (e.g., degree of loss) and mediate (e.g., hearing aid or cochlear implant use) its impact. PMID:23824428

Chronic fatigue in Hodgkin lymphoma survivors and associations with anxiety, depression and comorbidity

PubMed Central

Daniëls, L A; Oerlemans, S; Krol, A D G; Creutzberg, C L; van de Poll-Franse, L V

2014-01-01

Background: Fatigue is a frequent and persistent problem among Hodgkin lymphoma (HL) survivors. We investigated the prevalence of clinically relevant fatigue in HL survivors and the relation between fatigue and anxiety and depression. Methods: Fatigue was measured through the generic European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30) and Fatigue Assessment Scale (FAS). Anxiety and depression were measured with the Hospital Anxiety and Depression Scale. Questionnaires were mailed to 267 HL survivors. Results were compared with a Dutch age-matched normative population. Results: Response rate was 68% (median age 46 years, mean time since diagnosis 4.6 years). Prevalence of fatigue was significantly higher among HL survivors than in the norm population (FAS 41% vs 23%, QLQ-C30 43% vs 28%), as were fatigue levels. There was a significant association between fatigue, anxiety and depression. Of the HL survivors with high symptom levels of depression, 97% also reported fatigue. In multivariate analysis, depression was strongly associated with high levels of fatigue and, to a lesser extent, anxiety and comorbidity. Conclusions: Prevalence rates of fatigue are significantly higher in HL survivors than in the general population and differences are clinically relevant. Depression and anxiety were strongly associated with high levels of fatigue. Reducing fatigue levels by treatment of depression and anxiety should be further explored. PMID:24434433

Influence of type D personality on job stress and job satisfaction in clinical nurses: the mediating effects of compassion fatigue, burnout, and compassion satisfaction.

PubMed

Kim, Yeon Hee; Kim, Sung Reul; Kim, Yeo Ok; Kim, Ji Young; Kim, Hyun Kyung; Kim, Hye Young

2017-04-01

To test a hypothetical path model evaluating the influence of type D personality on job stress and job satisfaction and to identify the mediating effects of compassion fatigue, burnout, and compassion satisfaction among clinical nurses in South Korea. Personalities susceptible to stress, compassion fatigue, and burnout in clinical nurses have negative effects on the job stress and job satisfaction. A correlational, cross-sectional design was used. A convenience sample of 875 clinical nurses was recruited between December 2014 - February 2015. The structured questionnaires included the Type D personality scale-14, Professional Quality of Life, job stress, job satisfaction, and general characteristics. To test the hypothetical path model, we performed a path analysis by using the AMOS 18·0 program. Based on the path model, type D personality was significantly associated with compassion fatigue, burnout, and compassion satisfaction in our study subjects. Type D personality was significantly associated with job stress and job satisfaction via the effect of burnout, compassion satisfaction, and job stress. Since type D personality is associated with job stress and job satisfaction, identifying personalities vulnerable to stress would help to address job stress and to enhance job satisfaction when nurses have a high level of compassion fatigue and burnout and a low level of compassion satisfaction. The development of interventions that can reduce negative affect and social inhibition of nurses with type D personality and investigation of methods to decrease their compassion fatigue and burnout and to increase compassion satisfaction should be encouraged. © 2016 John Wiley & Sons Ltd.

Feasibility, reliability, and validity of the Pediatric Quality of Life Inventory ™ generic core scales, cancer module, and multidimensional fatigue scale in long-term adult survivors of pediatric cancer.

PubMed

Robert, Rhonda S; Paxton, Raheem J; Palla, Shana L; Yang, Grace; Askins, Martha A; Joy, Shaini E; Ater, Joann L

2012-10-01

Most health-related quality of life assessments are designed for either children or adults and have not been evaluated for adolescent and young adult survivors of pediatric cancer. The objective of this study was to examine the feasibility, reliability, and validity of the Pediatric Quality of Life Inventory (PedsQL ™ Generic Core Scales, Cancer Module, and Multidimensional Fatigue Scale in adult survivors of pediatric cancer. Adult survivors (n = 64; Mean age 35 year old; >2 years after treatment) completed the PedsQL™ Generic Core Scales, Cancer Module, and Multidimensional Fatigue Scale. Feasibility was examined with floor and ceiling effects; and internal consistency was determined by Cronbach's coefficient alpha calculations. Inter-factor correlations were also assessed. Significant ceiling effects were observed for the scales of social function, nausea, procedural anxiety, treatment anxiety, and communication. Internal consistency for all subscales was within the recommended ranges (α ≥ 0.70). Moderate to strong correlations between most Cancer Module and Generic Core Scales (r = 0.25 to r = 0.76) and between the Multidimensional Fatigue Scale and Generic Core Scales (r = 0.37 to r = 0.73). The PedsQL™ Generic Core Scales, Cancer Module, and Multidimensional Fatigue Scale appear to be feasible for an older population of pediatric cancer survivors; however, some of the Cancer Module Scales (nausea, procedural/treatment anxiety, and communication) were deemed not relevant for long-term survivors. More information is needed to determine whether the issues addressed by these modules are meaningful to long-term adult survivors of pediatric cancers. Copyright © 2012 Wiley Periodicals, Inc.

Fatigue Characterization of Alloy 10: a 1300F Disk Alloy for Small Gas Turbine Engines

NASA Technical Reports Server (NTRS)

Gayda, John

2000-01-01

A detailed fatigue characterization of Alloy 10, a high strength nickel-based disk alloy, was conducted on test coupons machined from a 'pancake' forging. Smooth bar, strain controlled fatigue testing at various R-ratios was run at representative bore, 750 F, and rim, 1300 F, temperatures. This was followed by notch fatigue testing (Kt=2) run under load control. Analysis of the fatigue data using a Smith-Watson-Topper approach and finite element analysis of the notch root was employed to understand material behavior in these tests. Smooth bar fatigue data showed a significant R-ratio dependence at either test temperature which could be accounted for using a Smith-Watson-Topper parameter (SWT). In general, fatigue life was longer at 750 F than 1300 F for a given SWT. For notch fatigue tests, life was longer at 750 F than 1300 F but only at higher stresses. This was attributed to differences in alloy strength. At lower stresses, finite element analysis suggested that convergence of fatigue life at both temperatures resulted from relaxation of stresses at the notch root in the 1300 F tests.

The Boeing 747 fatigue integrity program

NASA Technical Reports Server (NTRS)

Spencer, M. M.

1972-01-01

The fatigue integrity program which was established to insure economic operations and to provide foundation data for inspection and maintenance is discussed. Significant features of the 747 fatigue integrity program are: (1) fatigue analyses which are continually updated to reflect design changes, fatigue test results, and static and flight load survey measurements; (2) material selection and detail design by using initial fatigue analyses, service experience, and testing; and (3) fatigue testing to check detail design quality and to verify the analyses, culminated by the test of a structurally complete airframe. Fatigue stress analyses were performed with the aid of experimental as well as analytical procedures. Extensive application was made of the stress severity factor, developed at Boeing, for evaluating peak stresses in complex joints. A frame of reference was established by families of structural fatigue performance curves (S-N curves) encompassing the range of materials and fatigue qualities anticipated for the 747 airplane design.

Patterns of Morning and Evening Fatigue Among Adults with HIV/AIDS

PubMed Central

Lerdal, Anners; Gay, Caryl L.; Aouizerat, Bradley E.; Portillo, Carmen J.; Lee, Kathryn A.

2011-01-01

Aims and objectives Describe patterns of morning and evening fatigue in adults with HIV and examine their relationship to demographic and clinical factors and other symptoms. Background Most studies of HIV-related fatigue assess average levels of fatigue and do not address its diurnal fluctuations. Patterns of fatigue over the course of the day may have important implications for assessment and treatment. Design A cross-sectional, correlational design was used with six repeated measures over 72 hours. Method A convenience sample of 318 HIV-infected adults was recruited in San Francisco. Socio-demographic, clinical and symptom data were collected with questionnaires. CD4+ T-cell count and viral load were obtained from medical records. Participants completed a four-item version of the Lee Fatigue Scale each morning and evening for three consecutive days. Participants were grouped based on their diurnal pattern of fatigue (high evening only, high morning only, high morning and evening and low morning and evening). Group comparisons and logistic regression were used to determine the unique predictors of each fatigue pattern. Results The high evening fatigue pattern was associated with anxiety and the high morning pattern was associated with anxiety and depression. The morning fatigue pattern showed very little fluctuation between morning and evening, the evening pattern showed the largest fluctuation. The high morning and evening pattern was associated with anxiety, depression and sleep disturbance and this group reported the most fatigue-related distress and interference in functioning. Conclusions These results provide initial evidence for the importance of assessing the patient’s daily pattern of fatigue fluctuation, as different patterns were associated with different symptom experiences and perhaps different etiologies. Relevance to clinical practice Different fatigue patterns may benefit from tailored intervention strategies. Management of depressive symptoms could be tested in patients who experience high levels of morning fatigue. PMID:21752119

Fatigue after stroke: frequency and effect on daily life.

PubMed

Crosby, Gail A; Munshi, Sunil; Karat, Aaron Sanjit; Worthington, Esme; Lincoln, Nadina B

2012-01-01

An audit was conducted to assess the frequency of fatigue after stroke, to determine the impact on daily life, and whether it was discussed with clinicians. Patients were recruited from Nottingham University Hospitals NHS Trust stroke service. Patients were interviewed about their fatigue, and the Fatigue Severity Subscale (FSS-FAI), Brief Assessment Schedule for Depression Cards (BASDEC), Barthel Index and Nottingham Extended Activities of Daily Living (EADL) Scale were administered. 64 patients were recruited, with a mean age 73.5 years (SD 14.0, range 37-94 years), 37 (58%) as in-patients and 27 (42%) as outpatients. There were 41 (64%) who reported significant levels of fatigue and 31 (48%) with significant fatigue on the Fatigue Severity Scale. Demographic and clinical variables were not significantly related to fatigue (p > 0.05), apart from gender, with women reporting significantly more fatigue than men (p = 0.006). There was a moderate correlation between the BASDEC and FSS (r(s) = 0.41, p = 0.002). Of the 41 participants who reported fatigue, 33 (81%) had not discussed this with their clinician. Fatigue was a common problem after stroke. There was a lack of awareness in both patients and clinicians and little advice being given to patients with fatigue.

Validation of a Smartphone-Based Approach to In Situ Cognitive Fatigue Assessment.

PubMed

Price, Edward; Moore, George; Galway, Leo; Linden, Mark

2017-08-17

Acquired Brain Injuries (ABIs) can result in multiple detrimental cognitive effects, such as reduced memory capability, concentration, and planning. These effects can lead to cognitive fatigue, which can exacerbate the symptoms of ABIs and hinder management and recovery. Assessing cognitive fatigue is difficult due to the largely subjective nature of the condition and existing assessment approaches. Traditional methods of assessment use self-assessment questionnaires delivered in a medical setting, but recent work has attempted to employ more objective cognitive tests as a way of evaluating cognitive fatigue. However, these tests are still predominantly delivered within a medical environment, limiting their utility and efficacy. The aim of this research was to investigate how cognitive fatigue can be accurately assessed in situ, during the quotidian activities of life. It was hypothesized that this assessment could be achieved through the use of mobile assistive technology to assess working memory, sustained attention, information processing speed, reaction time, and cognitive throughput. The study used a bespoke smartphone app to track daily cognitive performance, in order to assess potential levels of cognitive fatigue. Twenty-one participants with no prior reported brain injuries took place in a two-week study, resulting in 81 individual testing instances being collected. The smartphone app delivered three cognitive tests on a daily basis: (1) Spatial Span to measure visuospatial working memory; (2) Psychomotor Vigilance Task (PVT) to measure sustained attention, information processing speed, and reaction time; and (3) a Mental Arithmetic Test to measure cognitive throughput. A smartphone-optimized version of the Mental Fatigue Scale (MFS) self-assessment questionnaire was used as a baseline to assess the validity of the three cognitive tests, as the questionnaire has already been validated in multiple peer-reviewed studies. The most highly correlated results were from the PVT, which showed a positive correlation with those from the prevalidated MFS, measuring 0.342 (P<.008). Scores from the cognitive tests were entered into a regression model and showed that only reaction time in the PVT was a significant predictor of fatigue (P=.016, F=2.682, 95% CI 9.0-84.2). Higher scores on the MFS were related to increases in reaction time during our mobile variant of the PVT. The results show that the PVT mobile cognitive test developed for this study could be used as a valid and reliable method for measuring cognitive fatigue in situ. This test would remove the subjectivity associated with established self-assessment approaches and the need for assessments to be performed in a medical setting. Based on our findings, future work could explore delivering a small set of tests with increased duration to further improve measurement reliability. Moreover, as the smartphone assessment tool can be used as part of everyday life, additional sources of data relating to physiological, psychological, and environmental context could be included within the analysis to improve the nature and precision of the assessment process. ©Edward Price, George Moore, Leo Galway, Mark Linden. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 17.08.2017.

Evaluation of the numeric rating scale for perception of effort during isometric elbow flexion exercise.

PubMed

Lampropoulou, Sofia; Nowicky, Alexander V

2012-03-01

The aim of the study was to examine the reliability and validity of the numerical rating scale (0-10 NRS) for rating perception of effort during isometric elbow flexion in healthy people. 33 individuals (32 ± 8 years) participated in the study. Three re-test measurements within one session and three weekly sessions were undertaken to determine the reliability of the scale. The sensitivity of the scale following 10 min isometric fatiguing exercise of the elbow flexors as well as the correlation of the effort with the electromyographic (EMG) activity of the flexor muscles were tested. Perception of effort was tested during isometric elbow flexion at 10, 30, 50, 70, 90, and 100% MVC. The 0-10 NRS demonstrated an excellent test-retest reliability [intra class correlation (ICC) = 0.99 between measurements taken within a session and 0.96 between 3 consecutive weekly sessions]. Exploratory curve fitting for the relationship between effort ratings and voluntary force, and underlying EMG showed that both are best described by power functions (y = ax ( b )). There were also strong correlations (range 0.89-0.95) between effort ratings and EMG recordings of all flexor muscles supporting the concurrent criterion validity of the measure. The 0-10 NRS was sensitive enough to detect changes in the perceived effort following fatigue and significantly increased at the level of voluntary contraction used in its assessment (p < 0.001). These findings suggest the 0-10 NRS is a valid and reliable scale for rating perception of effort in healthy individuals. Future research should seek to establish the validity of the 0-10 NRS in clinical settings.

Depression and fatigue in patients with multiple sclerosis.

PubMed

Greeke, Emily E; Chua, Alicia S; Healy, Brian C; Rintell, David J; Chitnis, Tanuja; Glanz, Bonnie I

2017-09-15

Previous research has examined the components of depression and fatigue in multiple sclerosis (MS), but the findings have been inconsistent. The aim of this study was to explore the associations between overall and subscale scores of the Center for Epidemiologic Studies-Depression Scale (CES-D) and the Modified Fatigue Impact Scale (MFIS) as well as the longitudinal changes in scores in a large cohort of MS patients. MS subjects who completed a battery of patient reported outcome (PRO) measures including the CES-D and MFIS (N=435) were included in our analysis. At the first available MFIS measurement, Pearson's correlation coefficient was used to estimate the association between the CES-D and MFIS in terms of both total scores and subscale scores. In addition, the longitudinal change in each total score and subscale score was estimated using a linear mixed model, and the association between the measures in terms of longitudinal change was estimated using Pearson's correlation coefficient and linear mixed models. At baseline, 15% of subjects were classified as high on both depression and fatigue scales, 16% were classified as high on the fatigue scale only, and 9% were classified as high on the depression scale only. There was a high correlation between CES-D and MFIS total scores (r=0.62). High correlations were also observed between the somatic and retarded activity subscales of the CES-D and each of the MFIS subscales (r≥0.60). In terms of longitudinal change, the change over the first year between the CES-D and MFIS total scores showed a moderate correlation (r=0.49). Subjects with high fatigue scores but low depression scores at baseline were more likely than subjects with low baseline fatigue and depression scores to develop high depression scores at follow-up. Our study demonstrated that depression and fatigue in MS share several features and have a similar longitudinal course. But using cut-off scores to define depression and fatigue, our study also found that non-depressed subjects with high fatigue may be at a greater risk for developing depression. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skochko, G.W.; Herrmann, T.P.

Axial load cycling fatigue tests of threaded fasteners are useful in determining fastener fatigue failure or design properties. By using appropriate design factors between the failure and design fatigue strengths, such tests are used to establish fatigue failure and design parameters of fasteners for axial and bending cyclic load conditions. This paper reviews the factors which influence the fatigue strength of low Alloy steel threaded fasteners, identifies those most significant to fatigue strength, and provides design guidelines based on the direct evaluation of fatigue tests of threaded fasteners. Influences on fatigue strength of thread manufacturing process (machining and rolling ofmore » threads), effect of fastener membrane and bending stresses, thread root radii, fastener sizes, fastener tensile strength, stress relaxation, mean stress, and test temperature are discussed.« less

Treatment of HIV-related fatigue with armodafinil: a placebo-controlled randomized trial.

PubMed

Rabkin, Judith G; McElhiney, Martin C; Rabkin, Richard

2011-01-01

To evaluate the efficacy and safety of armodafinil in the treatment of fatigue in HIV+ patients, and to assess its effect on depressive symptoms and behavior once fatigue remitted. HIV+ patients with clinically significant fatigue were treated in a placebo-controlled randomized double-blind trial for 4 weeks. Armodafinil responders and placebo non-responders or relapsers were treated openly for a total of 16 weeks with armodafinil. The primary outcome measure for fatigue and depression was the Clinical Global Impressions-Improvement Scale, supplemented by the Fatigue Severity Scale, the Hamilton Depression Rating Scale, and the Beck Depression Inventory. Safety was assessed with assays of CD4 cell count and HIV RNA viral load and the SAFTEE side effects rating scale. Maximum trial dose of armodafinil was 250 mg/d. Seventy patients were enrolled. Attrition was 9%. In intention-to-treat analyses, fatigue response rate to armodafinil was 75% and to placebo, 26%. Armodafinil did not reduce depressive symptoms in the absence of improved energy, but of those patients with an Axis I depressive disorder at study entry whose energy improved, 82% experienced improved mood as well. Markers of immunologic suppression did not change during treatment. At 6 months, those still taking armodafinil had more energy and fewer depressive symptoms than those who were no longer taking it. As we found in our RCT of modafinil, armodafinil appears effective and well tolerated in treating fatigue in HIV+ patients. Side effects were minimal and most patients reported substantially improved energy and mood. Copyright © 2011 The Academy of Psychosomatic Medicine. Published by Elsevier Inc. All rights reserved.

Treatment of HIV-Related Fatigue with Armodafinil: A Placebo-controlled Randomized Trial

PubMed Central

Rabkin, Judith G.; McElhiney, Martin C.; Rabkin, Richard

2011-01-01

Objective To evaluate the efficacy and safety of armodafinil in the treatment of fatigue in HIV+ patients, and to assess effect on depressive symptoms and behavior once fatigue remitted. Method HIV+ patients with clinically significant fatigue were treated in a placebo controlled randomized double-blind trial for 4 weeks. Armodafinil responders and placebo non-responders or relapsers were treated openly for a total of 16 weeks of armodafinil. The primary outcome measure for fatigue and depression was the Clinical Global Impressions-Improvement Scale, supplemented by the Fatigue Severity Scale, Hamilton Depression Rating Scale and Beck Depression Inventory. Safety was assessed with assays of CD4 cell count and HIV RNA viral load and the SAFTEE side effects rating scale. Maximum trial dose of armodafinil was 250 mg/day. Results 70 patients were enrolled. Attrition was 9%. In Intention-to-treat analyses, fatigue response rate to armodafinil was 75% and to placebo, 26%. Armodafinil did not reduce depressive symptoms in the absence of improved energy, but of those patients with an Axis I depressive disorder at study entry whose energy improved, 82% experienced improved mood as well. Markers of immunologic suppression did not change during treatment. At 6 months, those still taking armodafinil had more energy and fewer depressive symptoms than those who were no longer taking it. Conclusions As we found in our RCT of modafinil, armodafinil appears effective and well tolerated in treating fatigue in HIV+ patients. Side effects were minimal and most patients reported substantially improved energy and mood. PMID:21777715

Validation of the Modified Fatigue Impact Scale in Parkinson's disease.

PubMed

Schiehser, Dawn M; Ayers, Catherine R; Liu, Lin; Lessig, Stephanie; Song, David S; Filoteo, J Vincent

2013-03-01

Fatigue is a common symptom in Parkinson's disease (PD); however, a multidimensional scale that measures the impact of fatigue on functioning has yet to be validated in this population. The aim of this study was to examine the validity of the Modified Fatigue Impact Scale (MFIS), a self-report measure that assesses the effects of fatigue on physical, cognitive, and psychosocial functioning, in a sample of nondemented PD patients. PD patients (N = 100) completed the MFIS, the Positive and Negative Affect Schedule (PANAS-X), and several additional measures of psychosocial, cognitive, and motor functioning. A Principal Component Analysis (PCA) and item analysis using Cronbach's alpha were conducted to determine structural validity and internal consistency of the MFIS. Correlational analyses were performed between the MFIS and the PANAS-X fatigue subscale to evaluate convergent validity and between the MFIS and measures of depression, anxiety, apathy, and disease-related symptoms to determine divergent validity. The PCA identified two viable MFIS subscales: a cognitive subscale and a combination of the original scale's physical and psychosocial subscales as one factor. Item analysis revealed high internal consistency of all 21 items and the items within the two subscales. The MFIS had strong convergent validity with the PANAS-X fatigue subscale and adequate divergent validity with measures of disease stage, motor function, and cognition. Overall, this study demonstrates that the MFIS is a valid multidimensional measure that can be used to evaluate the impact of fatigue on cognitive and physical/social functioning in PD patients without dementia. Published by Elsevier Ltd.

Development of a full-scale transmission testing procedure to evaluate advanced lubricants

NASA Technical Reports Server (NTRS)

Lewicki, David G.; Decker, Harry J.; Shimski, John T.

1992-01-01

Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500-hp Helicopter Transmission Test Stand. The testing was part of a joint Navy/NASA/Army lubrication program. The objective of the program was to develop a separate lubricant for gearboxes and demonstrate an improved performance in life and load-carrying capacity. The goal of the experiments was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 base reference oil, then run identical tests with improved lubricants and demonstrate performance. The tests were directed at failing components that the Navy has had problems with due to marginal lubrication. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hours of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring.

Mild traumatic brain injury and fatigue: a prospective longitudinal study.

PubMed

Norrie, Joan; Heitger, Marcus; Leathem, Janet; Anderson, Tim; Jones, Richard; Flett, Ross

2010-01-01

To examine fatigue prevalence, severity, predictors and co-variates over 6 months post-mild traumatic brain injury (MTBI). Longitudinal prospective study including 263 adults with MTBI. Participants completed the Fatigue Severity Scale (FSS), Rivermead Post-concussion Symptoms Questionnaire (RPSQ), Hospital Anxiety and Depression Scale (HADS) and the Short Form 36 Health Survey-Version 2 (SF-36v2). Complete data were available for 159 participants. Key measures; prevalence--RPSQ Item 6: severity--FSS. The effect of time on fatigue prevalence and severity was examined using ANOVA. Multiple regression analysis identified statistically significant covariates. Post-MTBI fatigue prevalence was 68%, 38% and 34% at 1 week, 3 and 6 months, respectively. There was a strong effect for time over the first 3 months and moderate-to-high correlations between fatigue prevalence and severity. Early fatigue strongly predicted later fatigue; depression, but not anxiety was a predictor. Fatigue was seen as laziness by family or friends in 30% of cases. Post-MTBI fatigue is a persistent post-concussion symptom, exacerbated by depression but not anxiety. It diminishes in the first 3 months and then becomes relatively stable, suggesting the optimum intervention placement is at 3 months or more post-MTBI.

Improvement in multiple dimensions of fatigue in patients with fibromyalgia treated with duloxetine: secondary analysis of a randomized, placebo-controlled trial.

PubMed

Arnold, Lesley M; Wang, Fujun; Ahl, Jonna; Gaynor, Paula J; Wohlreich, Madelaine M

2011-06-13

Fatigue is one of the most disabling symptoms associated with fibromyalgia that greatly impacts quality of life. Fatigue was assessed as a secondary objective in a 2-phase, 24-week study in outpatients with American College of Rheumatology-defined fibromyalgia. Patients were randomized to duloxetine 60-120 mg/d (N = 263) or placebo (N = 267) for the 12-week acute phase. At Week 12, all placebo-treated patients were switched to double-blind treatment with duloxetine for the extension phase. Fatigue was assessed at baseline and every 4 weeks with the Multidimensional Fatigue Inventory (MFI) scales: General Fatigue, Physical Fatigue, Mental Fatigue, Reduced Activity, and Reduced Motivation. Other assessments that may be associated with fatigue included Brief Pain Inventory (BPI) average pain, numerical scales to rate anxiety, depressed mood, bothered by sleep difficulties, and musculoskeletal stiffness. Treatment-emergent fatigue-related events were also assessed. Changes from baseline to Week 12, and from Week 12 to Week 24, were analyzed by mixed-effects model repeated measures analysis. At Week 12, duloxetine versus placebo significantly (all p < .05) reduced ratings on each MFI scale, BPI pain, anxiety, depressed mood, and stiffness. Improvement in ratings of being bothered by sleep difficulties was significant only at Weeks 4 and 8. At Week 24, mean changes in all measures indicated improvement was maintained for patients who received duloxetine for all 24 weeks (n = 176). Placebo-treated patients switched to duloxetine (n = 187) had significant within-group improvement in Physical Fatigue (Weeks 16, 20, and 24); General Fatigue (Weeks 20 and 24); Mental Fatigue (Week 20); and Reduced Activity (Weeks 20 and 24). These patients also experienced significant within-group improvement in BPI pain, anxiety, depressed mood, bothered by sleep difficulties, and stiffness. Overall, the most common (> 5% incidence) fatigue-related treatment-emergent adverse events were fatigue, somnolence, and insomnia. Treatment with duloxetine significantly improved multiple dimensions of fatigue in patients with fibromyalgia, and improvement was maintained for up to 24 weeks. ClinicalTrials.gov registry NCT00673452.

Low cycle fatigue and creep-fatigue behavior of Ni-based alloy 230 at 850 C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xiang; Yang, Zhiqing; Sokolov, Mikhail A

Strain-controlled low cycle fatigue (LCF) and creep-fatigue testing of Ni-based alloy 230 were carried out at 850 C. The material creep-fatigue life decreased compared with its low cycle fatigue life at the same total strain range. Longer hold time at peak tensile strain further reduced the material creep-fatigue life. Based on the electron backscatter diffraction, a novel material deformation characterization method was applied, which revealed that in low cycle fatigue testing as the total strain range increased, the deformation was segregated to grain boundaries since the test temperature was higher than the material equicohesive temperature and grain boundaries became weakermore » regions compared with grains. Creep-fatigue tests enhanced the localized deformation, resulting in material interior intergranular cracking, and accelerated material damage. Precipitation in alloy 230 helped slip dispersion, favorable for fatigue property, but grain boundary cellular precipitates formed after material exposure to the elevated temperature had a deleterious effect on the material low cycle fatigue and creep-fatigue property.« less

Cancer-related fatigue management: evaluation of a patient education program with a large-scale randomised controlled trial, the PEPs fatigue study.

PubMed

Bourmaud, A; Anota, A; Moncharmont, C; Tinquaut, F; Oriol, M; Trillet-Lenoir, V; Bajard, A; Parnalland, S; Rotonda, C; Bonnetain, F; Pérol, D; Chauvin, F

2017-03-28

To assess the efficacy of a patient educational program built according to guidelines that aims at reducing cancer-related fatigue (CRF). Randomised controlled trial, multicentre, comparing a patient education program, vs the standard of care. Patients were adult cancer outpatients with any tumour site. The primary outcome was fatigue severity assessed with a visual analogical scale (VAS), between the day of randomisation and week 7. Secondary outcomes were fatigue assessed with other scales, health-related quality of life, anxiety and depression. The time to fatigue severity deterioration was assessed. Analyses were performed in a modified intent-to-treat way, that is, including all patients with at least one baseline and 1 week 7 score. A total of 212 patients were included. Fatigue severity assessment was made on 79 patients in the experimental group and 65 in the control group. Between randomisation and week 7, the fatigue (VAS) improved by 0.96 (2.85) points in the experimental group vs 1.63 (2.63) points in the control group (P=0.15). No differences with the secondary outcomes were highlighted between two groups. No other factors were found to be associated with fatigue severity deterioration. Despite rigorous methodology, this study failed to highlight the program efficacy in fatigue reduction for cancer patients. Other assessment tools should be developed to measure the effect of the program on CRF and behaviour. The implementation of the program should also be explored in order to identify its mechanisms and longer-term impact.

Cross-Cultural Validation of the Korean Version of the Chalder Fatigue Scale.

PubMed

Ha, Hyeju; Jeong, Donghee; Hahm, Bong-Jin; Shim, Eun-Jung

2018-06-01

University students are vulnerable to fatigue. If not adequately dealt with, fatigue might develop into various health problems and negatively affect quality of life (QOL). The present study examined psychometric properties of the Korean version of the Chalder Fatigue Scale (K-CFQ) in university students. Data were obtained from two samples of undergraduate students in Korea. The first dataset (N = 557) was collected in a cross-sectional survey in 2015 and the second dataset (N = 338) from a longitudinal survey with three time points over a semester period in 2016. Participants completed measures of fatigue, QOL, depression, anxiety, and sleep quality. Three-factor model (physical fatigue, low energy, and mental fatigue) rather than the original two-factor model (physical and mental fatigue) provided a better goodness of fit indices to the data. Internal consistency of the K-CFQ was satisfactory, with Cronbach's α value of 0.88 for the total scale and those of subscales ranging from 0.73 to 0.87. Its convergent validity was supported by its significant association with anxiety, depression, sleep quality, and QOL. Significant association between T1 K-CFQ with physical QOL at T2 and T3 supported its predictive validity. Its known-group validity was proven with higher K-CFQ scores observed in the participants with depression and those with poor sleep quality. Current results suggest that K-CFQ is a valid and reliable measure of fatigue, and a better model fit of the three-factor structure of the K-CFQ implies potential cross-cultural differences in the dimensionality of fatigue.

Cancer-related fatigue management: evaluation of a patient education program with a large-scale randomised controlled trial, the PEPs fatigue study

PubMed Central

Bourmaud, A; Anota, A; Moncharmont, C; Tinquaut, F; Oriol, M; Trillet-Lenoir, V; Bajard, A; Parnalland, S; Rotonda, C; Bonnetain, F; Pérol, D; Chauvin, F

2017-01-01

Background: To assess the efficacy of a patient educational program built according to guidelines that aims at reducing cancer-related fatigue (CRF). Methods: Randomised controlled trial, multicentre, comparing a patient education program, vs the standard of care. Patients were adult cancer outpatients with any tumour site. The primary outcome was fatigue severity assessed with a visual analogical scale (VAS), between the day of randomisation and week 7. Secondary outcomes were fatigue assessed with other scales, health-related quality of life, anxiety and depression. The time to fatigue severity deterioration was assessed. Analyses were performed in a modified intent-to-treat way, that is, including all patients with at least one baseline and 1 week 7 score. Results: A total of 212 patients were included. Fatigue severity assessment was made on 79 patients in the experimental group and 65 in the control group. Between randomisation and week 7, the fatigue (VAS) improved by 0.96 (2.85) points in the experimental group vs 1.63 (2.63) points in the control group (P=0.15). No differences with the secondary outcomes were highlighted between two groups. No other factors were found to be associated with fatigue severity deterioration. Conclusions: Despite rigorous methodology, this study failed to highlight the program efficacy in fatigue reduction for cancer patients. Other assessment tools should be developed to measure the effect of the program on CRF and behaviour. The implementation of the program should also be explored in order to identify its mechanisms and longer-term impact. PMID:28196066

Screening Poststroke Fatigue; Feasibility and Validation of an Instrument for the Screening of Poststroke Fatigue throughout the Rehabilitation Process.

PubMed

Kruithof, Nena; Van Cleef, Melanie Hubertina Maria; Rasquin, Sascha Maria Cornelia; Bovend'Eerdt, Thamar Johannes Henricus

2016-01-01

Our objective is to investigate the feasibility and validity of a new instrument to screen for determinants of poststroke fatigue during the rehabilitation process. This prospective cohort study was conducted within the stroke department of a rehabilitation center. The participants in the study were postacute adult stroke patients. The Detection List Fatigue (DLF)was administered 2 weeks after the start of the rehabilitation program and again 6 weeks later. To determine the construct validity, the Hospital Anxiety and Depression Scale, the Checklist Individual Strength subscale fatigue, and the Fatigue Severity Scale--7-item version were administered. A fatigue rating scale was used to measure the patients' fatigue experience. Frequency analyses of the number of patients reporting poststroke fatigue determinants according to the DLF were performed. One hundred seven patients (mean age 60 years) without severe communication difficulties were included in the study. The DLF was easy to understand and quick to administer. The DLF showed good internal consistency (Cronbach's alpha: .79 and .87), high convergent validity (rs = .85 and rs = .79), and good divergent validity (rs = .31 and rs = .45). The majority of the patients (88.4%-90.2%) experienced at least 2 poststroke fatigue (PSF) determinants,of which "sleeping problem" was most frequently reported. The DLF is a feasible and valid instrument for the screening of PSF determinants throughout the rehabilitation process in stroke patients. Future studies should investigate whether the use of the list in determining a treatment plan prevents the development of PSF.

Effect of Different Levels of Localized Muscle Fatigue on Knee Position Sense

PubMed Central

Gear, William S.

2011-01-01

There is little information available regarding how proprioceptive abilities decline as the amount of exertion increases during exercise. The purpose of this study was to determine the role of different levels of fatigue on knee joint position sense. A repeated measures design was used to examine changes in active joint reposition sense (AJRS) prior to and following three levels of fatigue. Eighteen participants performed knee extension and flexion isokinetic exercise until torque output was 90%, 70%, or 50% of the peak hamstring torque for three consecutive repetitions. Active joint reposition sense at 15, 30, or 45 degrees was tested following the isokinetic exercise session. Following testing of the first independent measure, participants were given a 20 minute rest period. Testing procedures were repeated for two more exercise sessions following the other levels of fatigue. Testing of each AJRS test angle was conducted on three separate days with 48 hours between test days. Significant main effect for fatigue was indicated (p = 0.001). Pairwise comparisons indicated a significant difference between the pre-test and following 90% of peak hamstring torque (p = 0.02) and between the pre-test and following 50% of peak hamstring torque (p = 0.02). Fatigue has long been theorized to be a contributing factor in decreased proprioceptive acuity, and therefore a contributing factor to joint injury. The findings of the present study indicate that fatigue may have an effect on proprioception following mild and maximum fatigue. Key points A repeated measures design was used to examine the effect of different levels of fatigue on active joint reposition sense (AJRS) of the knee at joint angles of 15°, 30° and 45° of flexion. A statistically significant main effect for fatigue was found, specifically between no fatigue and mild fatigue and no fatigue and maximum fatigue. A statistically significant interaction effect between AJRS and fatigue was not found. Secondary analysis of the results indicated a potential plateau effect of AJRS as fatigue continues to increase. Further investigation of the effect of increasing levels of fatigue on proprioception is warranted. PMID:24149565

Effect of different levels of localized muscle fatigue on knee position sense.

PubMed

Gear, William S

2011-01-01

There is little information available regarding how proprioceptive abilities decline as the amount of exertion increases during exercise. The purpose of this study was to determine the role of different levels of fatigue on knee joint position sense. A repeated measures design was used to examine changes in active joint reposition sense (AJRS) prior to and following three levels of fatigue. Eighteen participants performed knee extension and flexion isokinetic exercise until torque output was 90%, 70%, or 50% of the peak hamstring torque for three consecutive repetitions. Active joint reposition sense at 15, 30, or 45 degrees was tested following the isokinetic exercise session. Following testing of the first independent measure, participants were given a 20 minute rest period. Testing procedures were repeated for two more exercise sessions following the other levels of fatigue. Testing of each AJRS test angle was conducted on three separate days with 48 hours between test days. Significant main effect for fatigue was indicated (p = 0.001). Pairwise comparisons indicated a significant difference between the pre-test and following 90% of peak hamstring torque (p = 0.02) and between the pre-test and following 50% of peak hamstring torque (p = 0.02). Fatigue has long been theorized to be a contributing factor in decreased proprioceptive acuity, and therefore a contributing factor to joint injury. The findings of the present study indicate that fatigue may have an effect on proprioception following mild and maximum fatigue. Key pointsA repeated measures design was used to examine the effect of different levels of fatigue on active joint reposition sense (AJRS) of the knee at joint angles of 15°, 30° and 45° of flexion.A statistically significant main effect for fatigue was found, specifically between no fatigue and mild fatigue and no fatigue and maximum fatigue.A statistically significant interaction effect between AJRS and fatigue was not found.Secondary analysis of the results indicated a potential plateau effect of AJRS as fatigue continues to increase.Further investigation of the effect of increasing levels of fatigue on proprioception is warranted.

Fatigue data for polyether ether ketone (PEEK) under fully-reversed cyclic loading

PubMed Central

Shrestha, Rakish; Simsiriwong, Jutima; Shamsaei, Nima

2016-01-01

In this article, the data obtained from the uniaxial fully-reversed fatigue experiments conducted on polyether ether ketone (PEEK), a semi-crystalline thermoplastic, are presented. The tests were performed in either strain-controlled or load-controlled mode under various levels of loading. The data are categorized into four subsets according to the type of tests, including (1) strain-controlled fatigue tests with adjusted frequency to obtain the nominal temperature rise of the specimen surface, (2) strain-controlled fatigue tests with various frequencies, (3) load-controlled fatigue tests without step loadings, and (4) load-controlled fatigue tests with step loadings. Accompanied data for each test include the fatigue life, the maximum (peak) and minimum (valley) stress–strain responses for each cycle, and the hysteresis stress–strain responses for each collected cycle in a logarithmic increment. A brief description of the experimental method is also given. PMID:26937465

Fatigue data for polyether ether ketone (PEEK) under fully-reversed cyclic loading.

PubMed

Shrestha, Rakish; Simsiriwong, Jutima; Shamsaei, Nima

2016-03-01

In this article, the data obtained from the uniaxial fully-reversed fatigue experiments conducted on polyether ether ketone (PEEK), a semi-crystalline thermoplastic, are presented. The tests were performed in either strain-controlled or load-controlled mode under various levels of loading. The data are categorized into four subsets according to the type of tests, including (1) strain-controlled fatigue tests with adjusted frequency to obtain the nominal temperature rise of the specimen surface, (2) strain-controlled fatigue tests with various frequencies, (3) load-controlled fatigue tests without step loadings, and (4) load-controlled fatigue tests with step loadings. Accompanied data for each test include the fatigue life, the maximum (peak) and minimum (valley) stress-strain responses for each cycle, and the hysteresis stress-strain responses for each collected cycle in a logarithmic increment. A brief description of the experimental method is also given.

Measurement of Fatigue in Cancer, Stroke, and HIV Using the Functional Assessment of Chronic Illness Therapy – Fatigue (FACIT-F) Scale

PubMed Central

Butt, Zeeshan; Lai, Jin-shei; Rao, Deepa; Heinemann, Allen W.; Bill, Alex; Cella, David

2012-01-01

Objective Given the importance of fatigue in cancer, stroke and HIV, we sought to assess the measurement properties of a single, well-described fatigue scale in these populations. We hypothesized that the psychometric properties of the Functional Assessment of Chronic Illness Therapy – Fatigue (FACIT-F) subscale would be favorable and that the scale could serve as a useful indicator of fatigue in these populations. Methods Patients were eligible for the study if they were outpatients, aged 18 or older, with a diagnosis of cancer (n=297), stroke (n=51), or HIV/AIDS (n=51). All participants were able to understand and speak English. Patients answered study-related questions, including the FACIT-F using a touch-screen laptop, assisted by the research assistant as necessary. Clinical information was abstracted from patients’ medical records. Results Item-level statistics on the FACIT-F were similar across the groups and internal consistency reliability was uniformly high (α>0.91). Correlations with performance status ratings were statistically significant across the groups (range r=−0.28 to −0.80). Fatigue scores were moderately to highly correlated with general quality of life (range r=0.66–0.80) in patients with cancer, stroke, and HIV. Divergent validity was supported in low correlations with variables not expected to correlate with fatigue. Conclusions Originally developed to assess cancer-related fatigue, the FACIT-F has utility as a measure of fatigue in other populations, such as stroke and HIV. Ongoing research will soon allow for comparison of FACIT-F scores to those obtained using the fatigue measures from the Patient-Reported Outcomes Measurement Information System (PROMIS®; www.nihpromis.org) initiative. PMID:23272990

Dynamic Postural Control in Female Athletes and Nonathletes After a Whole-Body Fatigue Protocol.

PubMed

Baghbani, Fatemeh; Woodhouse, Linda J; Gaeini, Abbas A

2016-07-01

Baghbani, F, Woodhouse, LJ, and Gaeini, AA. Dynamic postural control in female athletes and nonathletes after a whole-body fatigue protocol. J Strength Cond Res 30(7): 1942-1947, 2016-Postural control is a crucial element in regular training of athletes, development of complex technical movement, and injury prevention; however, distributing factor of the postural control such as fatigue has been neglected by athletic trainers in novice and inexperienced athletes. The objective of this study was to compare changes in dynamic postural control of young female athletes and nonathletes after a fatigue protocol. Thirty females (15 athletes and 15 nonathletes) with no orthopedic problems were recruited to participate in this study. All participants completed the pre-SEBT (star excursion balance test) in 8 directions at baseline; then, they performed a 20-minute fatigue protocol after which post-SEBT was measured. Rating of perceived exertion was measured using the Borg scale immediately before, mid-way through (i.e., after the third station), and after performing the fatigue protocol (i.e., immediately before the post-SEBT). Female nonathlete groups had significant differences in dynamic balance performance after fatigue in the medial, posteromedial, and posterior directions (p < 0.01) measured by SEBT. Athletes, however, showed no significant changes after the fatigue protocol. Our results indicates the importance of evaluation and monitoring of dynamic postural control of the novice with progressing the exercise time. Our findings could also help coaches to develop trainings focused on the 3 directions of medial, posteromedial, and posterior directions and aimed at exercises increasing fatigue resistance.

Reliability analysis applied to structural tests

NASA Technical Reports Server (NTRS)

Diamond, P.; Payne, A. O.

1972-01-01

The application of reliability theory to predict, from structural fatigue test data, the risk of failure of a structure under service conditions because its load-carrying capability is progressively reduced by the extension of a fatigue crack, is considered. The procedure is applicable to both safe-life and fail-safe structures and, for a prescribed safety level, it will enable an inspection procedure to be planned or, if inspection is not feasible, it will evaluate the life to replacement. The theory has been further developed to cope with the case of structures with initial cracks, such as can occur in modern high-strength materials which are susceptible to the formation of small flaws during the production process. The method has been applied to a structure of high-strength steel and the results are compared with those obtained by the current life estimation procedures. This has shown that the conventional methods can be unconservative in certain cases, depending on the characteristics of the structure and the design operating conditions. The suitability of the probabilistic approach to the interpretation of the results from full-scale fatigue testing of aircraft structures is discussed and the assumptions involved are examined.

Predicting Fatigue Lives Of Metal-Matrix/Fiber Composites

NASA Technical Reports Server (NTRS)

Bartolotta, Paul A.

1994-01-01

Method of prediction of fatigue lives of intermetallic-matrix/fiber composite parts at high temperatures styled after method of universal slopes. It suffices to perform relatively small numbers of fatigue tests. Data from fatigue tests correlated with tensile-test data by fitting universal-slopes equation to both sets of data. Thereafter, universal-slopes equation used to predict fatigue lives from tensile properties.

Experimental and modeling results of creep fatigue life of Inconel 617 and Haynes 230 at 850 C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xiang; Sokolov, Mikhail A; Sham, Sam

Creep fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure formore » both materials decreased under creep fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep fatigue life. The linear damage summation could predict the creep fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep fatigue life prediction results for both materials.« less

Evaluation of fatigue life of CRM-reinforced SMA and its relationship to dynamic stiffness.

PubMed

Mashaan, Nuha Salim; Karim, Mohamed Rehan; Abdel Aziz, Mahrez; Ibrahim, Mohd Rasdan; Katman, Herda Yati; Koting, Suhana

2014-01-01

Fatigue cracking is an essential problem of asphalt concrete that contributes to pavement damage. Although stone matrix asphalt (SMA) has significantly provided resistance to rutting failure, its resistance to fatigue failure is yet to be fully addressed. The aim of this study is to evaluate the effect of crumb rubber modifier (CRM) on stiffness and fatigue properties of SMA mixtures at optimum binder content, using four different modification levels, namely, 6%, 8%, 10%, and 12% CRM by weight of the bitumen. The testing undertaken on the asphalt mix comprises the dynamic stiffness (indirect tensile test), dynamic creep (repeated load creep), and fatigue test (indirect tensile fatigue test) at temperature of 25°C. The indirect tensile fatigue test was conducted at three different stress levels (200, 300, and 400 kPa). Experimental results indicate that CRM-reinforced SMA mixtures exhibit significantly higher fatigue life compared to the mixtures without CRM. Further, higher correlation coefficient was obtained between the fatigue life and resilient modulus as compared to permanent strain; thus resilient modulus might be a more reliable indicator in evaluating the fatigue life of asphalt mixture.

Experimental and modeling results of creep-fatigue life of Inconel 617 and Haynes 230 at 850 °C

NASA Astrophysics Data System (ADS)

Chen, Xiang; Sokolov, Mikhail A.; Sham, Sam; Erdman, Donald L., III; Busby, Jeremy T.; Mo, Kun; Stubbins, James F.

2013-01-01

Creep-fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 °C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep-fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep-fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep-fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep-fatigue life. The linear damage summation could predict the creep-fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep-fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep-fatigue life prediction results for both materials.

Validation of the Neurological Fatigue Index for stroke (NFI-Stroke)

PubMed Central

2012-01-01

Background Fatigue is a common symptom in Stroke. Several self-report scales are available to measure this debilitating symptom but concern has been expressed about their construct validity. Objective To examine the reliability and validity of a recently developed scale for multiple sclerosis (MS) fatigue, the Neurological Fatigue Index (NFI-MS), in a sample of stroke patients. Method Six patients with stroke participated in qualitative interviews which were analysed and the themes compared for equivalence to those derived from existing data on MS fatigue. 999 questionnaire packs were sent to those with a stroke within the past four years. Data from the four subscales, and the Summary scale of the NFI-MS were fitted to the Rasch measurement model. Results Themes identified by stroke patients were consistent with those identified by those with MS. 282 questionnaires were returned and respondents had a mean age of 67.3 years; 62% were male, and were on average 17.2 (SD 11.4, range 2–50) months post stroke. The Physical, Cognitive and Summary scales all showed good fit to the model, were unidimensional, and free of differential item functioning by age, sex and time. The sleep scales failed to show adequate fit in their current format. Conclusion Post stroke fatigue appears to be represented by a combination of physical and cognitive components, confirmed by both qualitative and quantitative processes. The NFI-Stroke, comprising a Physical and Cognitive subscale, and a 10-item Summary scale, meets the strictest measurement requirements. Fit to the Rasch model allows conversion of ordinal raw scores to a linear metric. PMID:22587411

Effects of acupressure on fatigue and depression in hepatocellular carcinoma patients treated with transcatheter arterial chemoembolization: a quasi-experimental study.

PubMed

Lan, Su-Chen; Lin, Yueh-E; Chen, Shu-Ching; Lin, Yu-Fang; Wang, Yu-Jen

2015-01-01

This study was to examine the effects of acupressure on fatigue and depression in HCC patients undergoing TACE. A quasiexperimental study design was used. Patients were evaluated at five time points: before treatment (T1) and 2, 3, 4, and 5 days after treating TACE (T2, T3, T4, and T5). Fatigue and depression were assessed by a VAS fatigue scale and a VAS depression scale at each time point. TFRS and BDI were administered at T1 and T5. Patients' fatigue and depression were significantly higher at T5 than at T1 in two groups. Fatigue and depression increased in both the experimental and control groups' patients over the five days of hospitalization during which TACE and chemotherapy were administered. The experimental group had significantly less fatigue than the control group, with lower subscale scores on physical, psychosocial, daily, and overall fatigue. There were no differences between the groups on depression. At posttest, the experimental group experienced lower physical, psychosocial, daily, and overall fatigue than the control group. Acupressure can improve fatigue in HCC patients during treatment with TACE but did not alleviate depression. Discharge planning should include home care for management of fatigue and depression.

Effects of Acupressure on Fatigue and Depression in Hepatocellular Carcinoma Patients Treated with Transcatheter Arterial Chemoembolization: A Quasi-Experimental Study

PubMed Central

Lan, Su-Chen; Lin, Yueh-E; Chen, Shu-Ching; Lin, Yu-Fang; Wang, Yu-Jen

2015-01-01

This study was to examine the effects of acupressure on fatigue and depression in HCC patients undergoing TACE. A quasiexperimental study design was used. Patients were evaluated at five time points: before treatment (T1) and 2, 3, 4, and 5 days after treating TACE (T2, T3, T4, and T5). Fatigue and depression were assessed by a VAS fatigue scale and a VAS depression scale at each time point. TFRS and BDI were administered at T1 and T5. Patients' fatigue and depression were significantly higher at T5 than at T1 in two groups. Fatigue and depression increased in both the experimental and control groups' patients over the five days of hospitalization during which TACE and chemotherapy were administered. The experimental group had significantly less fatigue than the control group, with lower subscale scores on physical, psychosocial, daily, and overall fatigue. There were no differences between the groups on depression. At posttest, the experimental group experienced lower physical, psychosocial, daily, and overall fatigue than the control group. Acupressure can improve fatigue in HCC patients during treatment with TACE but did not alleviate depression. Discharge planning should include home care for management of fatigue and depression. PMID:25802540

Enzyme replacement therapy and fatigue in adults with Pompe disease.

PubMed

Güngör, Deniz; de Vries, Juna M; Brusse, Esther; Kruijshaar, Michelle E; Hop, Wim C J; Murawska, Magda; van den Berg, Linda E M; Reuser, Arnold J J; van Doorn, Pieter A; Hagemans, Marloes L C; Plug, Iris; van der Ploeg, Ans T

2013-06-01

Pompe disease is a hereditary metabolic myopathy, for which enzyme replacement therapy (ERT) has been available since 2006. We investigated whether ERT reduces fatigue in adult patients with Pompe disease. In this prospective international observational survey, we used the Fatigue Severity Scale (FSS) to measure fatigue. Repeated measures ANOVA was used to analyze the data over time. In a subgroup of patients, we also evaluated muscle strength using the Medical Research Council Scale, measured pulmonary function as Forced Vital Capacity, and assessed depression using the Hospital Anxiety and Depression Scale. We followed 163 patients for a median period of 4 years before ERT and for 3 years during ERT. Before ERT, the mean FSS score remained stable at around 5.3 score points; during ERT, scores improved significantly by 0.13 score points per year (p < 0.001). Fatigue decreased mainly in women, in older patients and in those with shorter disease duration. Patients' improvements in fatigue were moderately correlated with the effect of ERT on depression (r 0.55; CI 95% 0.07 to 0.70) but not with the effect of ERT on muscle strength or pulmonary function. Fatigue is a common and disabling problem in patients with early and advanced stages of Pompe disease. Our finding that ERT helps to reduce fatigue is therefore important for this patient population, irrespective of the mechanisms underlying this effect. Copyright © 2013 Elsevier Inc. All rights reserved.

A longitudinal study to explain the pain-depression link in older adults with osteoarthritis.

PubMed

Hawker, Gillian A; Gignac, Monique A M; Badley, Elizabeth; Davis, Aileen M; French, Melissa R; Li, Ye; Perruccio, Anthony V; Power, J Denise; Sale, Joanna; Lou, Wendy

2011-10-01

To evaluate whether osteoarthritis (OA) pain determines depressed mood, taking into consideration fatigue and disability and controlling for other factors. In a community cohort with hip/knee OA, telephone interviews assessed OA pain and disability (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), fatigue (Multidimensional Fatigue Symptom Inventory), depressed mood (Center for Epidemiologic Studies Depression Scale), and covariates (demographics, self-rated health, comorbidity, pain coping, pain catastrophizing, and social support) at 3 time points over 2 years. Drawing on previous research, a path model was developed to test the interrelationships among the key concepts (pain, depression, fatigue, disability) over time, controlling for covariates. The baseline mean age was 75.4 years; 78.5% of the subjects were women, 37.2% were living alone, and 15.5% had ≥3 comorbid conditions. WOMAC scores indicated moderate OA symptoms and disability. From the final model with 529 subjects, adjusting for covariates, we found that current OA pain strongly predicted future fatigue and disability (both short and long term), that fatigue and disability in turn predicted future depressed mood, that depressed mood and fatigue were interrelated such that depressed mood exacerbated fatigue and vice versa, and that fatigue and disability, but not depressed mood, led to worsening of OA pain. Controlling for other factors, OA pain determined subsequent depressed mood through its effect on fatigue and disability. These effects led to worsening of pain and disability over time. These results support the need for improved pain management in OA to prevent or attenuate the downstream effects of pain on disability and mood. Copyright © 2011 by the American College of Rheumatology.

Fatigue crack identification method based on strain amplitude changing

NASA Astrophysics Data System (ADS)

Guo, Tiancai; Gao, Jun; Wang, Yonghong; Xu, Youliang

2017-09-01

Aiming at the difficulties in identifying the location and time of crack initiation in the castings of helicopter transmission system during fatigue tests, by introducing the classification diagnostic criteria of similar failure mode to find out the similarity of fatigue crack initiation among castings, an engineering method and quantitative criterion for detecting fatigue cracks based on strain amplitude changing is proposed. This method is applied on the fatigue test of a gearbox housing, whose results indicates: during the fatigue test, the system alarms when SC strain meter reaches the quantitative criterion. The afterwards check shows that a fatigue crack less than 5mm is found at the corresponding location of SC strain meter. The test result proves that the method can provide accurate test data for strength life analysis.

Static and fatigue testing of full-scale fuselage panels fabricated using a Therm-X(R) process

NASA Technical Reports Server (NTRS)

Dinicola, Albert J.; Kassapoglou, Christos; Chou, Jack C.

1992-01-01

Large, curved, integrally stiffened composite panels representative of an aircraft fuselage structure were fabricated using a Therm-X process, an alternative concept to conventional two-sided hard tooling and contour vacuum bagging. Panels subsequently were tested under pure shear loading in both static and fatigue regimes to assess the adequacy of the manufacturing process, the effectiveness of damage tolerant design features co-cured with the structure, and the accuracy of finite element and closed-form predictions of postbuckling capability and failure load. Test results indicated the process yielded panels of high quality and increased damage tolerance through suppression of common failure modes such as skin-stiffener separation and frame-stiffener corner failure. Finite element analyses generally produced good predictions of postbuckled shape, and a global-local modelling technique yielded failure load predictions that were within 7% of the experimental mean.

Evaluation of graphite composite materials for bearingless helicopter rotor application

NASA Technical Reports Server (NTRS)

Ulitchny, M. G.; Lucas, J. J.

1974-01-01

Small scale combined load fatigue tests were conducted on twelve unidirectional graphite-glass scrim-epoxy composite specimens. The specimens were 1 in. (2.54 cm) wide by 0.1 in. (.25 cm) thick by 5 in. (12.70 cm) long. The fatigue data was developed for the preliminary design of the spar for a bearingless helicopter main rotor. Three loading conditions were tested. Combinations of steady axial, vibratory torsion, and vibratory bending stresses were chosen to simulate the calculated stresses which exist at the root and at the outboard end of the pitch change section of the spar. Calculated loads for 150 knots (77.1 m/sec) level flight were chosen as the baseline condition. Test stresses were varied up to 4.4 times the baseline stress levels. Damage resulted in reduced stiffness; however, in no case was complete fracture of the specimen experienced.

Sleep and fatigue in multiple sclerosis: A questionnaire-based, cross-sectional, cohort study.

PubMed

Nociti, Viviana; Losavio, Francesco Antonio; Gnoni, Valentina; Losurdo, Anna; Testani, Elisa; Vollono, Catello; Frisullo, Giovanni; Brunetti, Valerio; Mirabella, Massimiliano; Della Marca, Giacomo

2017-01-15

Fatigue and sleep disorders are frequently reported in patients affected by Multiple Sclerosis (MS) but the causes and the relationship are not yet fully understood. This study aimed at evaluating their prevalence, at determining the relationships between clinical findings of MS and the occurrence of sleep disorders and at investigating the relations between sleep disorders and fatigue. One hundred and two MS patients were enrolled in the study. They were analyzed on both their clinical features (type of MS, disease duration, clinical severity, type of treatment, presence of spinal demyelinating lesions) and specific scales scores (Expanded Disability Status Scale, Modified Fatigue Impact Scale - MFIS, Self-Administered Anxiety Scale - SAS, Beck's Depression Inventory - BDI, Pittsburgh Sleep Quality Index - PSQI, Epworth Sleepiness Scale - ESS, and the Berlin's questionnaire for Obstruction Sleep Apnea Syndrome - OSAS). Patients with poor sleep quality are more frequently fatigued (p=0.001), have higher MFIS global scores (p<0.001), higher prevalence of RLS symptoms (p=0.049), and show higher scores at BDI (p=0.017) and SAS (p≤0.001). Conversely patients with fatigue show older age (p=0.005), higher prevalence of sleepiness (p=0.021), higher prevalence of RLS symptoms (p=0.030), higher prevalence of poor sleep quality (p<0.001) with higher PSQI scores (p<0.001), higher scores on the BDI (p<0.001) and SAS (p≤0.001). This study shows that MS is associated with a high prevalence of sleep complaints, including subjectively poor sleep quality, excessive daytime sleepiness, RLS and symptoms of OSAS. Further, it demonstrated a strict relation between fatigue and sleep disorders. Finally, it underlines their relationship with anxiety and depression in MS patients. Copyright © 2016 Elsevier B.V. All rights reserved.

Brain lesion correlates of fatigue in individuals with traumatic brain injury.

PubMed

Schönberger, Michael; Reutens, David; Beare, Richard; O'Sullivan, Richard; Rajaratnam, Shantha M W; Ponsford, Jennie

2017-10-01

The purpose of this study was to investigate the neurological correlates of both subjective fatigue as well as objective fatigability in individuals with traumatic brain injury (TBI). The study has a cross-sectional design. Participants (N = 53) with TBI (77% male, mean age at injury 38 years, mean time since injury 1.8 years) underwent a structural magnetic resonance imaging (MRI) scan and completed the Fatigue Severity Scale (FSS), while a subsample (N = 36) was also tested with a vigilance task. While subjective fatigue (FSS) was not related to measures of brain lesions, multilevel analyses showed that a change in the participants' decision time was significantly predicted by grey matter (GM) lesions in the right frontal lobe. The time-dependent development of the participants' error rate was predicted by total brain white matter (WM) lesion volumes, as well as right temporal GM and WM lesion volumes. These findings could be explained by decreased functional connectivity of attentional networks, which results in accelerated exhaustion during cognitive task performance. The disparate nature of objectively measurable fatigability on the one hand and the subjective experience of fatigue on the other needs further investigation.

Prefrontal tDCS Decreases Pain in Patients with Multiple Sclerosis

PubMed Central

Ayache, Samar S.; Palm, Ulrich; Chalah, Moussa A.; Al-Ani, Tarik; Brignol, Arnaud; Abdellaoui, Mohamed; Dimitri, Dalia; Sorel, Marc; Créange, Alain; Lefaucheur, Jean-Pascal

2016-01-01

Background: In the last few years, transcranial direct current stimulation (tDCS) has emerged as an appealing therapeutic option to improve brain functions. Promising data support the role of prefrontal tDCS in augmenting cognitive performance and ameliorating several neuropsychiatric symptoms, namely pain, fatigue, mood disturbances, and attentional impairment. Such symptoms are commonly encountered in patients with multiple sclerosis (MS). Objective: The main objective of the current work was to evaluate the tDCS effects over the left dorsolateral prefrontal cortex (DLPFC) on pain in MS patients.Our secondary outcomes were to study its influence on attention, fatigue, and mood. Materials and Methods: Sixteen MS patients with chronic neuropathic pain were enrolled in a randomized, sham-controlled, and cross-over study.Patients randomly received two anodal tDCS blocks (active or sham), each consisting of three consecutive daily tDCS sessions, and held apart by 3 weeks. Evaluations took place before and after each block. To evaluate pain, we used the Brief Pain Inventory (BPI) and the Visual Analog Scale (VAS). Attention was assessed using neurophysiological parameters and the Attention Network Test (ANT). Changes in mood and fatigue were measured using various scales. Results: Compared to sham, active tDCS yielded significant analgesic effects according to VAS and BPI global scales.There were no effects of any block on mood, fatigue, or attention. Conclusion: Based on our results, anodal tDCS over the left DLPFC appears to act in a selective manner and would ameliorate specific symptoms, particularly neuropathic pain. Analgesia might have occurred through the modulation of the emotional pain network. Attention, mood, and fatigue were not improved in this work. This could be partly attributed to the short protocol duration, the small sample size, and the heterogeneity of our MS cohort. Future large-scale studies can benefit from comparing the tDCS effects over different cortical sites, changing the stimulation montage, prolonging the duration of protocol, and coupling tDCS with neuroimaging techniques for a better understanding of its possible mechanism of action. PMID:27092048

Recent Developments in Assessing Microstructure-Sensitive Early Stage Fatigue of Polycrystals (Postprint)

DTIC Science & Technology

2014-04-01

can strongly affect formation of fatigue cracks. El Bartali et al. [7] quantified plastic strain at the grain scale in a duplex stainless steel and mea... Fatigue Fract Eng Mater Struct 2013. [7] El Bartali A, Aubin V, Degallaix S. Fatigue damage analysis in a duplex stainless steel by digital image...S. Surface observation and measurement techniques to study the fatigue damage micromechanisms in a duplex stainless steel . Int J Fatigue 2009;31:2049

Fatigue Following Traumatic Brain Injury in Children and Adolescents: A Longitudinal Follow-Up 6 to 12 Months After Injury.

PubMed

Crichton, Alison; Anderson, Vicki; Oakley, Ed; Greenham, Mardee; Hearps, Stephen; Delzoppo, Carmel; Beauchamp, Miriam H; Hutchison, James S; Guerguerian, Anne-Marie; Boutis, Kathy; Babl, Franz E

Longitudinal fatigue data in children suffering from traumatic brain injury (TBI) are lacking. To examine the effects of time postinjury (6-12 months) and injury severity on fatigue after childhood TBI. Secondarily, we compared fatigue 12 months postinjury against published control data. Three tertiary children's hospitals across Australia (n = 1) and Canada (n = 2). Parents (n = 109) of children (mean [M] = 9.9 years at injury; range, 1.0-16.9 years) admitted to one of 3 participating hospitals with mild (n = 69) or moderate/severe (n = 37) TBI. Longitudinal prospective study. Primary: Pediatric Quality of Life Multidimensional Fatigue Scale (total, general, sleep/rest, and cognitive), rated by parents 6 and 12 months postinjury. Secondary: Pediatric Injury Functional Outcome Scale (fatigue and sleep items, rated on recruitment and 6 and 12 months postinjury). Demographic and children data were collected at recruitment. Mixed-models analysis demonstrated nonsignificant effects of time (6 vs 12 months postinjury) on multidimensional fatigue scores. Cognitive fatigue worsened over time. Moderate/severe TBI was associated with worse fatigue 12 months postinjury (general, P = .03; cognitive, P = .02). Across all severities, fatigue 12 months postinjury was significantly worse compared with control data (total fatigue, P < .001; all domains, all Ps < .025). Fatigue remains significant at 12 months since injury, particularly for those with moderate/severe TBI.

Improvements in Depression and Changes in Fatigue: Results from the SLAM DUNC Depression Treatment Trial

PubMed Central

Bengtson, Angela M.; Gaynes, Bradley N.; McGuinness, Teena; Quinlivan, Evelyn B.; Ogle, Michelle; Heine, Amy; Thielman, Nathan M.; Pence, Brian W.

2016-01-01

Fatigue and depression are common co-morbid conditions among people with HIV infection. We analyzed a population of HIV-infected adults with depression, who were enrolled in a depression treatment trial, to examine the extent to which improvements in depression over time were associated with improvements in HIV-related fatigue. Data for this analysis come from a randomized controlled trial to evaluate the effectiveness of improved depression treatment on antiretroviral adherence. Fatigue was measured using the HIV-Related Fatigue Scale, and depressive symptoms were measured with the Hamilton Depression Rating Scale. Participants (n = 234) were on average nearly 44 years of age and predominantly male, black or African American, and unemployed. Individuals who experienced stronger depression response (i.e., greater improvement in depression score) had larger decreases in fatigue. However, even among those who demonstrated a full depression response, nearly three-quarters continued to have either moderate or severe fatigue at 6 and 12 months. PMID:26525221

Correlates of residual fatigue in patients with major depressive disorder: The role of psychotropic medication.

PubMed

Chung, Ka-Fai; Yu, Yee-Man; Yeung, Wing-Fai

2015-11-01

Fatigue is not only a core symptom of major depressive disorder (MDD), but also a common residual symptom. We determined the sociodemographic, clinical, and pharmacologic factors that were associated with fatigue in patients with remission or partial remission of MDD. Data was derived from a randomized controlled trial of acupuncture in 137 MDD patients with residual symptoms. Fatigue was measured by Multidimensional Fatigue Inventory (MFI-20). Self-report and clinician-rated scales were used to assess psychopathology. 17-item Hamilton Depression Rating Scale (HDRS17) score≤7 denoted MDD remission. Participants' average HDRS17 score was 10.5; 29.2% were in remission. The average MFI-20 score was 71.8; 83.2% had severe fatigue, defined as MFI-20 score≥60. Fifty-two of 137 participants (38%) were using sedating psychotropic medications. Antidepressant dosage ranged from 1-90mg fluoxetine equivalent and sedatives/hypnotics from 1-60mg diazepam equivalent. There were significant correlations between MFI-20 score and HDRS17 depression and anxiety subscores, Hospital Anxiety and Depression Scale (HADS) depression and anxiety subscores, and Pain Catastrophizing Scale score, but insomnia and daytime sleepiness, sociodemographics, current medical conditions, and psychotropic medication use were not significant correlates. Upon multiple regression, HADS and HDRS17 depression scores independently predicted MFI-20 score. In remission and partial remission subgroups, HADS depression score was an independent predictor. Participants were recruited from specialty psychiatric units; hence the findings may not be applicable in non-specialized settings. Fatigue was predicted by depression severity in remitted or partially remitted MDD. Psychotropic medication and higher dosage were not associated with greater fatigue. Copyright © 2015 Elsevier B.V. All rights reserved.

A Randomized Controlled Trial of Home-Based Exercise for Cancer-Related Fatigue in Women during and after Chemotherapy with or without Radiation Therapy

PubMed Central

Dodd, Marylin J.; Cho, Maria H.; Miaskowski, Christine; Painter, Patricia L.; Paul, Steven M.; Cooper, Bruce A.; Duda, John; Krasnoff, Joanne; Bank, Kayee A.

2010-01-01

Background Few studies have evaluated an individualized home-based exercise prescription during and after cancer treatment. Objective The purpose was to evaluate the effectiveness of a home-based exercise training intervention, the PRO-SELF FATIGUE CONTROL PROGRAM on the management of cancer related fatigue. Interventions/Methods Participants (N=119) were randomized into one of three groups: Group 1 (EE) received the exercise prescription throughout the study; Group 2 (CE) received their exercise prescription after completing cancer treatment; Group 3 (CC) received usual care. Patients completed the Piper Fatigue Scale, General Sleep Disturbance Scale, Center for Epidemiological Studies-Depression scale, and Worst Pain Intensity Scale. Results All groups reported mild fatigue levels, sleep disturbance and mild pain, but not depression. Using multilevel regression analysis significant linear and quadratic trends were found for change in fatigue and pain (i.e., scores increased, then decreased over time). No group differences were found in the changing scores over time. A significant quadratic effect for the trajectory of sleep disturbance was found, but no group differences were detected over time. No significant time or group effects were found for depression. Conclusions Our home-based exercise intervention had no effect on fatigue or related symptoms associated with cancer treatment. The optimal timing of exercise remains to be determined. Implications for practice Clinicians need to be aware that some physical activity is better than none, and there is no harm in exercise as tolerated during cancer treatment. Further analysis is needed to examine the adherence to exercise. More frequent assessments of fatigue, sleep disturbance, depression, and pain may capture the effect of exercise. PMID:20467301

Influence of Austenite Stability on Steel Low Cycle Fatigue Response

NASA Astrophysics Data System (ADS)

Lehnhoff, G. R.; Findley, K. O.

Austenitic steels were subjected to tensile and total strain controlled, fully reversed axial low cycle fatigue (LCF) testing to determine the influence of stacking fault energy on austenite stability, or resistance to strain induced martensitic transformation during tensile and fatigue deformation. Expected differences in stacking fault energy were achieved by modifying alloys with different amounts of silicon and aluminum. Al alloying was found to promote martensite formation during both tensile and LCF loading, while Si was found to stabilize austenite. Martensite formation increases tensile work hardening rates, though Si additions also increase the work hardening rate without martensite transformation. Similarly, secondary cyclic strain hardening during LCF is attributed to strain induced martensite formation, but Si alloying resulted in less secondary cyclic strain hardening. The amount of secondary cyclic hardening scales linearly with martensite fraction and depends only on the martensite fraction achieved and not on the martensite (i.e. parent austenite) chemistry. Martensite formation was detrimental to LCF lives at all strain amplitudes tested, although the total amount of martensitic transformation during LCF did not always monotonically increase with strain amplitude nor correlate to the amount of tensile transformation.

Damage mechanisms in PBT-GF30 under thermo-mechanical cyclic loading

NASA Astrophysics Data System (ADS)

Schaaf, A.; De Monte, M.; Hoffmann, C.; Vormwald, M.; Quaresimin, M.

2014-05-01

The scope of this paper is the investigation of damage mechanisms at microscopic scale on a short glass fiber reinforced polybutylene terephthalate (PBT-GF30) under thermo-mechanical cyclic loading. In addition the principal mechanisms are verified through micro mechanical FE models. In order to investigate the fatigue behavior of the material both isothermal strain controlled fatigue (ISCF) tests at three different temperatures and thermo-mechanical fatigue (TMF) tests were conducted on plain and notched specimens, manufactured by injection molding. The goal of the work is to determine the damage mechanisms occurring under TMF conditions and to compare them with the mechanisms occurring under ISCF. For this reason fracture surfaces of TMF and ISCF samples loaded at different temperature levels were analyzed using scanning electron microscopy. Furthermore, specimens that failed under TMF were examined on microsections revealing insight into both crack initiation and crack propagation. The findings of this investigation give valuable information about the main damage mechanisms of PBT-GF30 under TMF loading and serve as basis for the development of a TMF life estimation methodology.

Effects of Acute Fatigue of the Hip Flexor Muscles on Hamstring Muscle Extensibility.

PubMed

Muyor, José M; Arrabal-Campos, Francisco M

2016-12-01

The purpose of the present study was to evaluate the influence of acute fatigue of the hip flexor muscles on scores attained in tests frequently used in literature to measure hamstring muscle extensibility, namely the passive straight leg raise (PSLR), active straight leg raise (ASLR), passive knee extension (PKE), active knee extension (AKE), sit-and-reach (SR) and toe-touch (TT) tests. A total of seventy-five healthy and recreationally active adults voluntarily participated in this study. To reach fatigue, the participants actively lifted their legs alternately as many times as possible. In the passive tests, the results were 7.10 ± 5.21° and 5.68 ± 4.54° higher (p < 0.01) for PSLR and PKE tests, respectively, after acute fatigue. However, in the ASLR test, the results were lower post-fatigue than pre-fatigue (mean difference = -5.30° ± 9.51°; p < 0.01). The AKE, SR and TT tests did not show significant differences between pre- and post-fatigue (p > 0.05). Moderate (r = 0.40) to high (r = 0.97) correlation coefficients were found, which were statistically significant among all the measured flexibility tests both pre- and post-fatigue. In conclusion, the active implication of the hip flexor muscles until reaching fatigue had acute influences on the results of the PSLR, PKE and ASLR tests, but not on the results of the AKE, SR and TT tests. It is recommended to use the AKE test to assess hamstring muscle extensibility in situations where athletes show fatigue in their hip flexor muscles.

Multiscale Fatigue Life Prediction for Composite Panels

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Yarrington, Phillip W.; Arnold, Steven M.

2012-01-01

Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer s coupling with NASA s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.

Hearing Handicap and Speech Recognition Correlate With Self-Reported Listening Effort and Fatigue.

PubMed

Alhanbali, Sara; Dawes, Piers; Lloyd, Simon; Munro, Kevin J

To investigate the correlations between hearing handicap, speech recognition, listening effort, and fatigue. Eighty-four adults with hearing loss (65 to 85 years) completed three self-report questionnaires: the Fatigue Assessment Scale, the Effort Assessment Scale, and the Hearing Handicap Inventory for Elderly. Audiometric assessment included pure-tone audiometry and speech recognition in noise. There was a significant positive correlation between handicap and fatigue (r = 0.39, p < 0.05) and handicap and effort (r = 0.73, p < 0.05). There were significant (but lower) correlations between speech recognition and fatigue (r = 0.22, p < 0.05) or effort (r = 0.32, p< 0.05). There was no significant correlation between hearing level and fatigue or effort. Hearing handicap and speech recognition both correlate with self-reported listening effort and fatigue, which is consistent with a model of listening effort and fatigue where perceived difficulty is related to sustained effort and fatigue for unrewarding tasks over which the listener has low control. A clinical implication is that encouraging clients to recognize and focus on the pleasure and positive experiences of listening may result in greater satisfaction and benefit from hearing aid use.

Strain energy release rate as a function of temperature and preloading history utilizing the edge delamination fatique test method

NASA Technical Reports Server (NTRS)

Zimmerman, Richard S.; Adams, Donald F.

1989-01-01

Static laminate and tension-tension fatigue tests of IM7/8551-7 composite materials was performed. The Edge Delamination Test (EDT) was utilized to evaluate the temperature and preloading history effect on the critical strain energy release rate. Static and fatigue testing was performed at room temperature and 180 F (82 C). Three preloading schemes were used to precondition fatigue test specimens prior to performing the normal tension-tension fatigue EDT testing. Computer software was written to perform all fatigue testing while monitoring the dynamic modulus to detect the onset of delamination and record the test information for later retrieval and reduction.

Resilience and positive affect contribute to lower cancer-related fatigue among Chinese patients with gastric cancer.

PubMed

Zou, Guiyuan; Li, Ye; Xu, Ruicai; Li, Ping

2018-04-01

To investigate the prevalence of cancer-related fatigue and explore the relationship between resilience, positive affect, and fatigue among Chinese patients with gastric cancer. Cancer-related fatigue is the most distressing symptom reported frequently by cancer patients during both treatment and survival phases. Resilience and positive affect as vital protective factors against cancer-related fatigue have been examined, but the underlying psychological mechanisms are not well understood. A cross-sectional study. Two hundred and three gastric cancer patients were enrolled from three hospitals in China. The Cancer Fatigue Scale, the positive affect subscale of the Positive and Negative Affect Schedule and the Connor-Davidson Resilience Scale (CD-RISC10) were administered. Hierarchical linear regression modelling was conducted to examine the association between resilience and cancer-related fatigue, and the mediating effect of positive affect. The incidence of clinically relevant fatigue among patients with gastric cancer was 91.6%. Regression analysis showed that resilience was negatively associated with cancer-related fatigue, explaining 15.4% of variance in cancer-related fatigue. Mediation analysis showed that high resilience was associated with increased positive affect, which was associated with decreased cancer-related fatigue. Cancer-related fatigue is prevalent among patients with gastric cancer. Positive affect may mediate the relationship between resilience and cancer-related fatigue. Interventions that attend to resilience training and promotion of positive affect may be the focus for future clinical and research endeavours. © 2017 John Wiley & Sons Ltd.

Is the Sørensen test valid to assess muscle fatigue of the trunk extensor muscles?

PubMed

Demoulin, Christophe; Boyer, Mathieu; Duchateau, Jacques; Grosdent, Stéphanie; Jidovtseff, Boris; Crielaard, Jean-Michel; Vanderthommen, Marc

2016-01-01

Very few studies have quantified the degree of fatigue characterized by the decline in the maximal voluntary contraction (MVC) force of the trunk extensors induced by the widely used Sørensen test. Measure the degree of fatigue of the trunk extensor muscles induced by the Sørensen test. Eighty young healthy subjects were randomly divided into a control group (CG) and an experimental group (EG), each including 50% of the two genders. The EG performed an isometric MVC of the trunk extensors (pre-fatigue test) followed by the Sørensen test, the latter being immediately followed by another MVC (post-fatigue test). The CG performed only the pre- and post-fatigue tests without any exertion in between. The comparison of the pre- and post-fatigue tests revealed a significant (P< 0.05) decrease in MVC force normalized by body mass (-13%) in the EG, whereas a small increase occurred in the CG (+2.7%, P= 0.001). This study shows that the Sørensen test performed until failure in a young healthy population results in a reduced ability of the trunk extensor muscles to generate maximal force, and indicates that this test is valid for the assessment of fatigue in trunk extensor muscles.

Effect of Pitching Consecutive Days in Youth Fast-Pitch Softball Tournaments on Objective Shoulder Strength and Subjective Shoulder Symptoms.

PubMed

Skillington, S Andrew; Brophy, Robert H; Wright, Rick W; Smith, Matthew V

2017-05-01

The windmill pitching motion has been associated with risk for shoulder injury. Because there are no pitching limits on youth fast-pitch softball pitchers, these athletes often pitch multiple games across consecutive days. Strength changes, fatigue levels, and shoulder pain that develop among female fast-pitch pitchers over the course of consecutive days of pitching have not been investigated. Over the course of 2- and 3-day fast-pitch softball tournaments, pitchers will develop progressive objective weakness and increased subjective shoulder fatigue and pain without complete recovery between days. Cross-sectional study; Level of evidence, 3. Fourteen female fast-pitch softball pitchers between the ages of 14 and 18 years were evaluated for strength and fatigue changes across 2- and 3-day tournaments. At the beginning and end of each day of tournament play, pitchers were asked to quantify shoulder fatigue and shoulder pain levels of their dominant throwing arm using a 10-point visual analog scale (VAS). Shoulder abduction, flexion, external rotation, internal rotation, elbow flexion, and elbow extension strength measurements were gathered using a handheld dynamometer. Over the course of an average single day of tournament participation, pitchers developed significant increases in VAS scores for shoulder fatigue (median, 2.0; 95% CI, 1.3-3.0) and pain (median, 1.3; 95% CI, 0.5-2.3) and significant strength loss in all tested motions. Pitchers also developed significant increases in VAS shoulder fatigue (median, 3.5; 95% CI, 1.5-5.5), VAS shoulder pain (median, 2.5; 95% CI, 1.0-4.5), and strength loss in all tested motions over the entire tournament. Shoulder pain, fatigue, and strength do not fully recover between days. The accumulation of subjective shoulder pain and fatigue over the course of tournament play were closely correlated. Among youth female fast-pitch softball pitchers, there is a progressive increase in shoulder fatigue, pain, and weakness over the course of 2- and 3-day tournaments without full recovery between consecutive days of pitching.

Effects of a selective educational system on fatigue, sleep problems, daytime sleepiness, and depression among senior high school adolescents in Taiwan.

PubMed

Chen, Tien-Yu; Chou, Yu-Ching; Tzeng, Nian-Sheng; Chang, Hsin-An; Kuo, Shin-Chang; Pan, Pei-Yin; Yeh, Yi-Wei; Yeh, Chin-Bin; Mao, Wei-Chung

2015-01-01

The aim of the study reported here was to clarify the effects of academic pressure on fatigue, sleep problems, daytime sleepiness, and depression among senior high school adolescents in Taiwan. This cross-sectional study enrolled 757 senior high school adolescents who were classified into four groups: Grade 1 (n=261), Grade 2 (n=228), Grade 3T (n=199; Grade 3 students who had another college entrance test to take), and Grade 3S (n=69; Grade 3 students who had succeeded in their college application). Fatigue, sleep quality, daytime sleepiness, and depression were assessed using the Chinese version of the Multidimensional Fatigue Symptom Inventory - Short Form, Pittsburgh Sleep Quality Index-Taiwan Form, the Chinese version of the Epworth Sleepiness Scale, and the Chinese version of the Beck Depression Inventory(®)-II (BDI-II), respectively. Physical, emotional, and mental fatigue scores were all higher in higher-grade groups. The Grade 3T (test) students had the worst fatigue severity, and the Grade 3S (success) students had the least fatigue severity. More than half of the students (60.9%) went to bed after 12 am, and they had on average 6.0 hours of sleep per night. More than 30% of the students in Grade 2 (37.3%) and Grades 3T/S (30.2%/30.4%) possibly had daily sleepiness problems. The students in Grade 3T had the worst BDI-II score (13.27±9.24), and the Grade 3S students had a much lower BDI-II score (7.91±6.13). Relatively high proportions of fatigue, sleep problems, daytime sleepiness, and depression among senior high school adolescents were found in our study. The severities of fatigue, sleep problems, and depression were significantly diminished in the group under less academic stress (Grade 3S). Our findings may increase the understanding of the mental health of senior high school students under academic pressure in Taiwan. Further large sample size and population-based study should be done for better understanding about this topic.

Fatigue and health related quality of life in children and adolescents with cancer.

PubMed

Nunes, Michelle Darezzo Rodrigues; Jacob, Eufemia; Bomfim, Emiliana Omena; Lopes-Junior, Luis Carlos; de Lima, Regina Aparecida Garcia; Floria-Santos, Milena; Nascimento, Lucila Castanheira

2017-08-01

The study examined the different dimensions of fatigue (general, sleep/rest, cognitive), health related quality of life (HRQL) (physical, emotional, cognitive, social), and the relationships between fatigue and HRQL in hospitalized children and adolescents with cancer in Brazil. Participants were recruited from a pediatric oncology inpatient unit in a comprehensive cancer care hospital in southeast Brazil. They completed the PedsQL Multidimensional Fatigue Scale and the PedsQL Inventory of Quality of Life (Generic and Cancer module) once during hospitalization. The majority (66.7%) of the participants (n = 38; mean age 12.1 ± 2.9 years) had total fatigue scores < 75 on 0 to 100 scale; with the mean total fatigue score of 63.8 ± 18.5. The majority (72.2% generic; 83.3% cancer modules) had total PedsQL scores < 75 on 0 to 100 scale. The mean PedsQL score on generic module (61.1 ± 17.0) was similar to the mean PedsQL score cancer module (59.1 ± 16.7). Significant correlations were found between total fatigue and quality of life generic (r = 0.63, p = 0.000) and cancer module (r = 0.74, p = 0.000). The study is the first to report fatigue and health related quality of life in hospitalized children and adolescents with cancer in Brazil. Similar to experiences of other children in the world, our findings indicate that children and adolescents with cancer had problems with fatigue that were associated with low HRQL. Future studies are recommended to examine interventions (exercise, leisurely activities) that may alleviate fatigue and improve HRQL in pediatric patients with cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Whole-body cryostimulation (cryotherapy) provides benefits for fatigue and functional status in multiple sclerosis patients. A case-control study.

PubMed

Miller, E; Kostka, J; Włodarczyk, T; Dugué, B

2016-12-01

To study the effects of whole-body cryostimulation (WBC) on fatigue and functional status in multiple sclerosis (MS) patients with different levels of fatigue. Two groups of 24 MS patients with fatigue were studied. At the beginning of the study, the first group presented a Fatigue Severity Scale (FSS) score between 38 and 42 (low-fatigue (LF) group), and the second group had an FSS score between 48 and 52 (high-fatigue (HF) group). Both groups were matched for age and sex. All patients were exposed to 10.3-min session of WBC (one exposure per day at -110°C or lower). Functional status was assessed before and after the series of WBC exposures using the Rivermead Motor Assessment (RMA), the Multiple Sclerosis Impact Scale (MSIS-29), and the Expanded Disability Status Scale (EDSS). The RMA was estimated in three sections: gross function (RMA1), leg and trunk (RMA2), and arm (RMA3). MSIS-29 consists of two subscales assessing the physical (MSIS-29-PHYS) and psychological (MSIS-29-PSYCH) status. In both groups, the WBC sessions induced a significant improvement in the functional status and in the feeling of fatigue. However, the changes observed in HF patients were significantly greater than those observed in LF patients, especially in the MSIS-29-PHYS, MSIS-29-PSYCH, RMA1, and RMA3. The changes observed in the EDSS, RMA2, and FSS were similar in both groups. WBC appears to be effective in improving functional status and the feeling of fatigue in patients with MS and especially in those who are the most fatigued. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A New Zealand pilot randomized controlled trial of a web-based interactive self-management programme (MSInvigor8) with and without email support for the treatment of multiple sclerosis fatigue.

PubMed

van Kessel, Kirsten; Wouldes, Trecia; Moss-Morris, Rona

2016-05-01

To pilot and compare the efficacy of an internet-based cognitive behavioural therapy self-management programme with (MSInvigor8-Plus) and without (MSInvigor8-Only) the use of email support in reducing fatigue severity and impact (primary outcomes), and depressed and anxious mood (secondary outcomes). Randomized controlled trial using an independent randomization system built into the website and intention-to-treat analysis. Participants were recruited through the local Multiple Sclerosis Society and hospital neurological services in New Zealand. A total of 39 people (aged 31-63 years), experiencing multiple sclerosis fatigue, able to walk with and without walking aids, were randomized to MSInvigor8-Only (n = 20) or to MSInvigor8-Plus (n = 19). MSInvigor8 is an eight-session programme based on cognitive behaviour therapy principles including psycho-education, self-monitoring, and changing unhelpful activity and thought patterns. Outcome measures included fatigue severity (Chalder Fatigue Scale) and impact (Modified Fatigue Impact Scale), and anxiety and depression (Hospital Anxiety and Depression Scale). Assessments were performed at baseline and at 10 weeks. The MSInvigor8-Plus condition resulted in significantly greater reductions in fatigue severity (F [1,36] = 9.09, p < 0.01) and impact (F [1,36] = 6.03, p < 0.02) compared with the MSInvigor8-Only condition. Large between-group effect sizes for fatigue severity (d = 0.99) and fatigue impact (d = 0.81) were obtained. No significant differences were found between the groups on changes in anxiety and depression. MSInvigor8 delivered with email-based support is a potentially promising, acceptable, and cost-effective approach to treating fatigue in people with multiple sclerosis in New Zealand. © The Author(s) 2015.

Evaluation of Fatigue Life of CRM-Reinforced SMA and Its Relationship to Dynamic Stiffness

PubMed Central

Mashaan, Nuha Salim; Karim, Mohamed Rehan; Abdel Aziz, Mahrez; Ibrahim, Mohd Rasdan; Katman, Herda Yati

2014-01-01

Fatigue cracking is an essential problem of asphalt concrete that contributes to pavement damage. Although stone matrix asphalt (SMA) has significantly provided resistance to rutting failure, its resistance to fatigue failure is yet to be fully addressed. The aim of this study is to evaluate the effect of crumb rubber modifier (CRM) on stiffness and fatigue properties of SMA mixtures at optimum binder content, using four different modification levels, namely, 6%, 8%, 10%, and 12% CRM by weight of the bitumen. The testing undertaken on the asphalt mix comprises the dynamic stiffness (indirect tensile test), dynamic creep (repeated load creep), and fatigue test (indirect tensile fatigue test) at temperature of 25°C. The indirect tensile fatigue test was conducted at three different stress levels (200, 300, and 400 kPa). Experimental results indicate that CRM-reinforced SMA mixtures exhibit significantly higher fatigue life compared to the mixtures without CRM. Further, higher correlation coefficient was obtained between the fatigue life and resilient modulus as compared to permanent strain; thus resilient modulus might be a more reliable indicator in evaluating the fatigue life of asphalt mixture. PMID:25050406

The effect of allergic rhinitis on the degree of stress, fatigue and quality of life in OSA patients.

PubMed

Park, Cheol Eon; Shin, Seung Youp; Lee, Kun Hee; Cho, Joong Saeng; Kim, Sung Wan

2012-09-01

Both allergic rhinitis (AR) and obstructive sleep apnea (OSA) are known to increase stress and fatigue, but the result of their coexistence has not been studied. The objective of this study was to evaluate the amount of stress and fatigue when AR is combined with OSA. One hundred and twelve patients diagnosed with OSA by polysomnography were enrolled. Among them, 37 patients were diagnosed with AR by a skin prick test and symptoms (OSA-AR group) and 75 patients were classified into the OSA group since they tested negative for allergies. We evaluated the Epworth sleepiness scale (ESS), stress score, fatigue score, ability to cope with stress, and rhinosinusitis quality of life questionnaire (RQLQ) with questionnaires and statistically compared the scores of both groups. There were no significant differences in BMI and sleep parameters such as LSAT, AHI, and RERA between the two groups. However, the OSA-AR group showed a significantly higher ESS score compared to the OSA group (13.7 ± 4.7 vs. 9.3 ± 4.8). Fatigue scores were also significantly higher in the OSA-AR group than in the OSA group (39.8 ± 11.0 vs. 30.6 ± 5.4). The OSA-AR group had a significantly higher stress score (60.4 ± 18.6 vs. 51.2 ± 10.4). The ability to cope with stress was higher in the OSA group, although this difference was not statistically significant. RQLQ scores were higher in the OSA-AR group (60.2 ± 16.7 compared to 25.1 ± 13.9). In conclusion, management of allergic rhinitis is very important in treating OSA patients in order to eliminate stress and fatigue and to minimize daytime sleepiness and quality of life.

Fatigue Strength and Related Characteristics of Aircraft Joints I : Comparison of Spot-Weld and Rivet Patterns in 24s-t Alclad and 75s-t Alclad

NASA Technical Reports Server (NTRS)

Russell, H W; Jackson, L R; Grover, H J; Beaver, W W

1944-01-01

Report contains detailed results of a number of fatigue tests on spot-welded joints in aluminum alloys. The tests described include: (1) fatigue tests on spot-welded lap joints in sheets of unequal thickness of alclad 24s-t. These tests indicate that the fatigue strength of a spot-welded joint in sheets of two different gages is slightly higher than that of a similar joint in two sheets of the thinner gage but definitely lower than that of a similar joint in two sheets of the thicker gage. (2) Fatigue tests on spot-welded alclad 75s-t spot-welded lap-joint specimens of alclad 75s-t were not any stronger in fatigue than similar specimens of alclad 24s-t. (3) Fatigue tests on lap-joint specimens spot -welded after various surface preparations--these included ac welding wire-brushed surfaces, dc welding wire-brushed surfaces, and dc welding chemically cleaned surfaces. While the ac welds were strongest statically, the dc welds on wire-brushed surfaces were strongest in fatigue. Specimens prepared in this way were very nearly as strong as the best riveted specimens tested for comparison. (4) Fatigue tests on specimens spot-welded with varying voltage so as to include a wide range of static spot-weld strengths. The fatigue strengths were in the same order as the static strengths but showed less range. (author)

Simulation of Fatigue Crack Initiation at Corrosion Pits With EDM Notches

NASA Technical Reports Server (NTRS)

Smith, Stephen W.; Newman, John A.; Piascik, Robert S.

2003-01-01

Uniaxial fatigue tests were conducted to compare the fatigue life of laboratory produced corrosion pits, similar to those observed in the shuttle main landing gear wheel bolt-hole, and an electro-discharged-machined (EDM) flaw. EDM Jaws are used to simulate corrosion pits during shuttle wheel (dynamometer) testing. The aluminum alloy, (AA 7050) laboratory fatigue tests were conducted to simulate the local stress level contained in the wheel bolt-hole. Under this high local stress condition, the EDM notch produced a fatigue life similar to test specimens containing corrosion pits of similar size. Based on the laboratory fatigue test results, the EDM Jaw (semi-circular disc shaped) produces a local stress state similar to corrosion pits and can be used to simulate a corrosion pit during the shuttle wheel dynamometer tests.

Effect of Play-based Occupational Therapy on Symptoms of Hospitalized Children with Cancer: A Single-subject Study.

PubMed

Mohammadi, Ahmad; Mehraban, Afsoon Hassani; Damavandi, Shahla A

2017-01-01

Cancer is one of the four leading causes of death in children. Its courses of diagnosis and treatment can cause physiologic symptoms and psychological distress that secondarily affect children's quality of life and participation in daily activities. The aim of this study was to investigate the effect of play-based occupational therapy on pain, anxiety, and fatigue in hospitalized children with cancer who were receiving chemotherapy. Two hospitalized children with acute lymphoblastic leukemia at least 4 months after diagnoses who received two courses of chemotherapy participated in this pilot study. Takata Play History and Iranian Children Participation Assessment Scale were used to develop intervention protocol. Nine, 30-45 min play-based occupational therapy sessions took place for each child. Children filled out the Faces Pain Scale, Visual Fatigue Scale, and Faces Anxiety Scale before and after each intervention session. Pain, anxiety, and fatigue levels decreased in both participants. Furthermore, the results showed a relationship between pain, anxiety, and fatigue variables in these children. Play-based occupational therapy can be effective in improving pain, anxiety, and fatigue levels in hospitalized children with cancer receiving chemotherapy.

Chronic Stress and Fatigue-Related Quality of Life after Mild-to-Moderate Traumatic Brain Injury (TBI)

PubMed Central

Bay, Esther; de-Leon, Marita B.

2010-01-01

Objective To determine relationships between chronic stress, fatigue-related quality of life (QOL-F) and related covariates after mild-to-moderate traumatic brain injury (TBI). Design Observational and cross-sectional Participants A total of 84 community-dwelling individuals with mild-to-moderate TBI recruited from multiple out-patient rehabilitation clinics assessed on average 15 months after injury. Method Data were collected with self-report surveys and chart abstraction. Measures Neurofunctional Behavioral Inventory, Perceived Stress Scale-14, Impact of Events Scale, McGill Pain Short-form Scale, and modified version of the Fatigue Impact Scale. Results Fatigue-related quality of life was associated with somatic symptoms, perceived situational stress, but not with event-related stress (PTSD symptoms) related to index TBI, pre-injury demographic, or post-injury characteristics. Somatic symptoms and chronic situational stress accounted for 42% of the variance in QOL (F). Conclusions QOL (F) in community-dwelling individuals with mild-to- moderate TBI is associated with chronic situational stress and somatic symptoms. Symptom management strategies may need to include general stress management to reduce fatigue burden and improve quality of life. PMID:21169862

Effect of Play-based Occupational Therapy on Symptoms of Hospitalized Children with Cancer: A Single-subject Study

PubMed Central

Mohammadi, Ahmad; Mehraban, Afsoon Hassani; Damavandi, Shahla A.

2017-01-01

Objective: Cancer is one of the four leading causes of death in children. Its courses of diagnosis and treatment can cause physiologic symptoms and psychological distress that secondarily affect children's quality of life and participation in daily activities. The aim of this study was to investigate the effect of play-based occupational therapy on pain, anxiety, and fatigue in hospitalized children with cancer who were receiving chemotherapy. Methods: Two hospitalized children with acute lymphoblastic leukemia at least 4 months after diagnoses who received two courses of chemotherapy participated in this pilot study. Takata Play History and Iranian Children Participation Assessment Scale were used to develop intervention protocol. Nine, 30–45 min play-based occupational therapy sessions took place for each child. Children filled out the Faces Pain Scale, Visual Fatigue Scale, and Faces Anxiety Scale before and after each intervention session. Results: Pain, anxiety, and fatigue levels decreased in both participants. Furthermore, the results showed a relationship between pain, anxiety, and fatigue variables in these children. Conclusions: Play-based occupational therapy can be effective in improving pain, anxiety, and fatigue levels in hospitalized children with cancer receiving chemotherapy. PMID:28503651

A Multi-Scale Structural Health Monitoring Approach for Damage Detection, Diagnosis and Prognosis in Aerospace Structures

DTIC Science & Technology

2012-01-20

ultrasonic Lamb waves to plastic strain and fatigue life. Theory was developed and validated to predict second harmonic generation for specific mode... Fatigue and damage generation and progression are processes consisting of a series of interrelated events that span large scales of space and time...strain and fatigue life A set of experiments were completed that worked to relate the acoustic nonlinearity measured with Lamb waves to both the

Two-time scale fatigue modelling: application to damage

NASA Astrophysics Data System (ADS)

Devulder, Anne; Aubry, Denis; Puel, Guillaume

2010-05-01

A temporal multiscale modelling applied to fatigue damage evolution in cortical bone is presented. Microdamage accumulation in cortical bone, ensued from daily activities, leads to impaired mechanical properties, in particular by reducing the bone stiffness and inducing fatigue. However, bone damage is also known as a stimulus to bone remodelling, whose aim is to repair and generate new bone, adapted to its environment. This biological process by removing fatigue damage seems essential to the skeleton lifetime. As daily activities induce high frequency cycles (about 10,000 cycles a day), identifying two-time scale is very fruitful: a fast one connected with the high frequency cyclic loading and a slow one related to a quasi-static loading. A scaling parameter is defined between the intrinsic time (bone lifetime of several years) and the high frequency loading (few seconds). An asymptotic approach allows to decouple the two scales and to take into account history effects (Guennouni and Aubry in CR Acad Sci Paris Ser II 20:1765-1767, 1986). The method is here applied to a simple case of fatigue damage and a real cortical bone microstructure. A significant reduction in the amount of computation time in addition to a small computational error between time homogenized and non homogenized models are obtained. This method seems thus to give new perspectives to assess fatigue damage and, with regard to bone, to give a better understanding of bone remodelling.

Development and initial validation of a cessation fatigue scale.

PubMed

Mathew, Amanda R; Heckman, Bryan W; Meier, Ellen; Carpenter, Matthew J

2017-07-01

Smoking cessation fatigue, or tiredness of attempting to quit smoking, has been posited as a latent construct encompassing loss of motivation, loss of hope in cessation success, decreased self-efficacy, and exhaustion of self-control resources. Despite the potential clinical impact of characterizing cessation fatigue, there is currently no validated measure to assess it. Using a rational scale development approach, we developed a cessation fatigue measure and examined its reliability and construct validity in relation to a) smokers' experience of a recently failed quit attempt (QA) and b) readiness to engage in a subsequent QA. Data were drawn from an online cross-sectional survey of 484 smokers who relapsed from a QA within the past 30days. Exploratory factor analysis identified three factors within the 17-item Cessation Fatigue Scale (CFS), which we labeled: emotional exhaustion, pessimism, and devaluation. High internal consistency was observed for each factor and across the full scale. As expected, CFS overall was positively associated with withdrawal severity and difficulty quitting. CFS was negatively associated with previously validated measures of intention to quit, self-efficacy, and abstinence-related motivational engagement, even after adjusting for nicotine dependence. Findings provide initial validation for a new tool to assess cessation fatigue and contribute needed information on a theory-driven component of cessation-related motivation and relapse risk. Copyright © 2017. Published by Elsevier B.V.

The association of fatigue, pain, depression and anxiety with work and activity impairment in immune mediated inflammatory diseases.

PubMed

Enns, Murray W; Bernstein, Charles N; Kroeker, Kristine; Graff, Lesley; Walker, John R; Lix, Lisa M; Hitchon, Carol A; El-Gabalawy, Renée; Fisk, John D; Marrie, Ruth Ann

2018-01-01

Impairment in work function is a frequent outcome in patients with chronic conditions such as immune-mediated inflammatory diseases (IMID), depression and anxiety disorders. The personal and economic costs of work impairment in these disorders are immense. Symptoms of pain, fatigue, depression and anxiety are potentially remediable forms of distress that may contribute to work impairment in chronic health conditions such as IMID. The present study evaluated the association between pain [Medical Outcomes Study Pain Effects Scale], fatigue [Daily Fatigue Impact Scale], depression and anxiety [Hospital Anxiety and Depression Scale] and work impairment [Work Productivity and Activity Impairment Scale] in four patient populations: multiple sclerosis (n = 255), inflammatory bowel disease (n = 248, rheumatoid arthritis (n = 154) and a depression and anxiety group (n = 307), using quantile regression, controlling for the effects of sociodemographic factors, physical disability, and cognitive deficits. Each of pain, depression symptoms, anxiety symptoms, and fatigue individually showed significant associations with work absenteeism, presenteeism, and general activity impairment (quantile regression standardized estimates ranging from 0.3 to 1.0). When the distress variables were entered concurrently into the regression models, fatigue was a significant predictor of work and activity impairment in all models (quantile regression standardized estimates ranging from 0.2 to 0.5). These findings have important clinical implications for understanding the determinants of work impairment and for improving work-related outcomes in chronic disease.

High temperature, low-cycle fatigue of copper-base alloys for rocket nozzles. Part 2: Strainrange partitioning and low-cycle fatigue results at 538 deg C

NASA Technical Reports Server (NTRS)

Conway, J. B.; Stentz, R. H.; Berling, J. T.

1976-01-01

Low-cycle fatigue tests of 1/2 Hard AMZIRC Copper and NARloy Z were performed in argon at 538 C to determine partitioned strain range versus life relationships. Strain-controlled low-cycle fatigue tests of a Zr-Cr-Mg copper-base alloy were also performed. Strain ranges, lower than those employed in previous tests, were imposed in order to extend the fatigue life curve out to approximately 400,000 cycles. An experimental copper alloy and an experimental silver alloy were also studied. Tensile tests were performed in air at room temperature and in argon at 538 C. Strain-controlled low-cycle fatigue tests were performed at 538 C in argon to define the fatigue life over the regime from 300 to 3,000 cycles. For the silver alloy, three additional heat treatments were introduced, and a limited evaluation of the short-term tensile and low-cycle fatigue behavior at 538 C was performed.

Can the Fatigue Severity Scale 7-item version be used across different patient populations as a generic fatigue measure - a comparative study using a Rasch model approach

PubMed Central

2014-01-01

Background Fatigue is a disabling symptom associated with reduced quality of life in various populations living with chronic illnesses. The transfer of knowledge about fatigue from one group to another is crucial in both research and healthcare. Outcomes should be validly and reliably comparable between groups and should not be unduly influenced by diagnostic variations. The present study evaluates whether the Fatigue Severity Scale 7-item version (FSS-7) demonstrates similar item hierarchy across people with multiple sclerosis, stroke or HIV/AIDS to ensure valid comparisons between groups, and provide further evidence of internal scale validity. Methods A secondary comparative analysis was performed using data from three different studies of three different chronic illnesses: multiple sclerosis, stroke and HIV/AIDS. Each of these studies had previously concluded that the FSS-7 has better psychometric properties than the original FSS for measuring fatigue interference. Data from 224 people with multiple sclerosis, 104 people with stroke and 316 people with HIV/AIDS were examined. Item response theory and a Rasch model were chosen to analyze the similarity of the FSS-7 item hierarchy across the three diagnostic groups Results Cross-sample differences were found for items #3, #5, #6 and #9 for two of the three samples, which raise questions about item validity across groups. However, disease-specific and disease-generic Rasch measures were similar across samples, indicating that individual fatigue interference measures in these three chronic illnesses might still be reliably comparable using the FSS-7. Conclusions Some items performed differently between the three samples but did not bias person measures, thereby indicating that fatigue interference in these illnesses might still be reliably compared using FSS-7 scores. However, caution is warranted when comparing fatigue raw sum scores directly across diagnostic groups using the FSS-7. Further studies of the scale are needed in other types of chronic illnesses. PMID:24559076

Notched fatigue of single crystal PWA 1480 at turbine attachment temperatures

NASA Technical Reports Server (NTRS)

Meyer, T. G.; Nissley, D. M.; Swanson, G. A.

1989-01-01

The focus is on the lower temperature, uncoated and notched features of gas turbine blades. Constitutive and fatigue life prediction models applicable to these regions are being developed. Fatigue results are presented which were obtained thus far. Fatigue tests are being conducted on PWA 1480 single crystal material using smooth strain controlled specimens and three different notched specimens. Isothermal fatigue tests were conducted at 1200, 1400, and 1600 F. The bulk of the tests were conducted at 1200 F. The strain controlled tests were conducted at 0.4 percent per second strain rate and the notched tests were cycled at 1.0 cycle per second. A clear orientation dependence is observed in the smooth strain controlled fatigue results. The fatigue lifes of the thin, mild notched specimens agree fairly well with this smooth data when elastic stress range is used as a correlating parameter. Finite element analyses were used to calculate notch stresses. Fatigue testing will continue to further explore the trends observed thus far. Constitutive and life prediction models are being developed.

Prediction of Mean and Design Fatigue Lives of Self Compacting Concrete Beams in Flexure

NASA Astrophysics Data System (ADS)

Goel, S.; Singh, S. P.; Singh, P.; Kaushik, S. K.

2012-02-01

In this paper, result of an investigation conducted to study the flexural fatigue characteristics of self compacting concrete (SCC) beams in flexure are presented. An experimental programme was planned in which approximately 60 SCC beam specimens of size 100 × 100 × 500 mm were tested under flexural fatigue loading. Approximately 45 static flexural tests were also conducted to facilitate fatigue testing. The flexural fatigue and static flexural strength tests were conducted on a 100 kN servo-controlled actuator. The fatigue life data thus obtained have been used to establish the probability distributions of fatigue life of SCC using two-parameter Weibull distribution. The parameters of the Weibull distribution have been obtained by different methods of analysis. Using the distribution parameters, the mean and design fatigue lives of SCC have been estimated and compared with Normally vibrated concrete (NVC), the data for which have been taken from literature. It has been observed that SCC exhibits higher mean and design fatigue lives compared to NVC.

A task-oriented circuit training in multiple sclerosis: a feasibility study

PubMed Central

2014-01-01

Background The aim of this study was to evaluate the safety, feasibility and preliminary effects of a high-intensity rehabilitative task-oriented circuit training (TOCT) in a sample of multiple sclerosis (MS) subjects on walking competency, mobility, fatigue and health-related quality of life (HRQoL). Methods 24 MS subjects (EDSS 4.89 ± 0.54, 17 female and 7 male, 52.58 ± 11.21 years, MS duration 15.21 ± 8.68 years) have been enrolled and randomly assigned to 2 treatment groups: (i) experimental group received 10 TOCT sessions over 2 weeks (2 hours/each session) followed by a 3 months home exercise program, whereas control group did not receive any specific rehabilitation intervention. A feasibility patient-reported questionnaire was administered after TOCT. Functional outcome measures were: walking endurance (Six Minute Walk Test), gait speed (10 Meter Walk Test), mobility (Timed Up and Go test) and balance (Dynamic Gait Index). Furthermore, self-reported questionnaire of motor fatigue (Fatigue Severity Scale), walking ability (Multiple Sclerosis Walking Scale – 12) and health-related quality of life (Multiple Sclerosis Impact Scale – 29) were included. Subjects’ assessments were delivered at baseline (T0), after TOCT (T1) and 3 months of home-based exercise program (T2). Results After TOCT subjects reported a positive global rating on the received treatment. At 3 months, we found a 58.33% of adherence to the home-exercise program. After TOCT, walking ability and health-related quality of life were improved (p < 0.05) with minor retention after 3 months. The control group showed no significant changes in any variables. Conclusions This two weeks high-intensity task-oriented circuit class training followed by a three months home-based exercise program seems feasible and safe in MS people with moderate mobility impairments; moreover it might improve walking abilities. Trial registration NCT01464749 PMID:24906545

Sleep Disturbance, Daytime Symptoms, and Functional Performance in Patients With Stable Heart Failure: A Mediation Analysis.

PubMed

Jeon, Sangchoon; Redeker, Nancy S

2016-01-01

Sleep disturbance is common among patients with heart failure (HF) who also experience symptom burden and poor functional performance. We evaluated the extent to which sleep-related, daytime symptoms (fatigue, excessive daytime sleepiness, and depressive symptoms) mediate the relationship between sleep disturbance and functional performance among patients with stable HF. We recruited patients with stable HF for this secondary analysis of data from a cross-sectional, observational study. Participants completed unattended ambulatory polysomnography from which the Respiratory Disturbance Index was calculated, along with a Six-Minute Walk Test, questionnaires to elicit sleep disturbance (Pittsburgh Sleep Quality Index, Insomnia Symptoms from the Sleep Habits Questionnaire), daytime symptoms (Center for Epidemiologic Studies Depression Scale, Global Fatigue Index, Epworth Sleepiness Scale), and self-reported functional performance (Medical Outcomes Study SF36 V2 Physical Function Scale). We used structural equation modeling with latent variables for the key analysis. Follow-up, exploratory regression analysis with bootstrapped samples was used to examine the extent to which individual daytime symptoms mediated effects of sleep disturbance on functional performance after controlling for clinical and demographic covariates. The sample included 173 New York Heart Association Class I-IV HF patients (n = 60/34.7% women; M = 60.7, SD = 16.07 years of age). Daytime symptoms mediated the relationship between sleep disturbance and functional performance. Fatigue and depression mediated the relationship between insomnia symptoms and self-reported functional performance, whereas fatigue and sleepiness mediated the relationship between sleep quality and functional performance. Sleepiness mediated the relationship between the respiratory index and self-reported functional performance only in people who did not report insomnia. Daytime symptoms explain the relationships between sleep disturbance and functional performance in stable HF.

Bending fatigue of electron-beam-welded foils. Application to a hydrodynamic air bearing in the Chrysler/DOE upgraded automotive gas tubine engine

NASA Technical Reports Server (NTRS)

Saltsman, J. F.; Halford, G. R.

1984-01-01

A hydrodynamic air bearing with a compliment surface is used in the gas generator of an upgraded automotive gas turbine engine. In the prototype design, the compliant surface is a thin foil spot welded at one end to the bearing cartridge. During operation, the foil failed along the line of spot welds which acted as a series of stress concentrators. Because of its higher degree of geometric uniformity, electron beam welding of the foil was selected as an alternative to spot welding. Room temperature bending fatigue tests were conducted to determine the fatigue resistance of the electron beam welded foils. Equations were determined relating cycles to crack initiation and cycles to failure to nominal total strain range. A scaling procedure is presented for estimating the reduction in cyclic life when the foil is at its normal operating temperature of 260 C (500 F).

Relations between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy.

PubMed

Eken, Maaike M; Houdijk, Han; Doorenbosch, Caroline A M; Kiezebrink, Francisca E M; van Bennekom, Coen A M; Harlaar, Jaap; Dallmeijer, Annet J

2016-08-01

To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. In this case-control study, knee extensor muscle endurance was estimated from individual load-endurance curves as the load corresponding to a 15-repetition maximum in 17 adolescents with spastic CP (six males, 11 females; age 12-19y) and 18 adolescents with typical development (eight males, 10 females; age 13-19y). Questionnaires were used to assess subjectively reported fatigue (Pediatric Quality of Life Inventory Multidimensional Fatigue Scale) and participation (Life-Habits questionnaire). Walking capacity was assessed using the 6-minute walk test. Relations were determined using multiple regression analyses. Muscle endurance related significantly to subjectively reported fatigue and walking capacity in adolescents with CP, while no relations were found for adolescents with typical development (subjectively reported fatigue: regression coefficient β [95% confidence intervals] for CP=23.72 [6.26 to 41.18], for controls=2.72 [-10.26 to 15.69]; walking capacity β for CP=125m [-87 to 337], for controls=2m [-86 to 89]). The 15-repetition maximum did not relate to participation in adolescents with CP. Subjectively reported fatigue and reduced walking capacity in adolescents with CP are partly caused by lower muscle endurance of knee extensors. Training of muscle endurance might contribute to reducing the experience of fatigue and improving walking capacity. Reduced muscle endurance seems to have no effect on participation. © 2016 Mac Keith Press.

Detecting Gear Tooth Fatigue Cracks in Advance of Complete Fracture

NASA Technical Reports Server (NTRS)

Zakrajsek, James J.; Lewicki, David G.

1996-01-01

Results of using vibration-based methods to detect gear tooth fatigue cracks are presented. An experimental test rig was used to fail a number of spur gear specimens through bending fatigue. The gear tooth fatigue crack in each test was initiated through a small notch in the fillet area of a tooth on the gear. The primary purpose of these tests was to verify analytical predictions of fatigue crack propagation direction and rate as a function of gear rim thickness. The vibration signal from a total of three tests was monitored and recorded for gear fault detection research. The damage consisted of complete rim fracture on the two thin rim gears and single tooth fracture on the standard full rim test gear. Vibration-based fault detection methods were applied to the vibration signal both on-line and after the tests were completed. The objectives of this effort were to identify methods capable of detecting the fatigue crack and to determine how far in advance of total failure positive detection was given. Results show that the fault detection methods failed to respond to the fatigue crack prior to complete rim fracture in the thin rim gear tests. In the standard full rim gear test all of the methods responded to the fatigue crack in advance of tooth fracture; however, only three of the methods responded to the fatigue crack in the early stages of crack propagation.

Subjective Fatigue in Children with Hearing Loss: Some Preliminary Findings

ERIC Educational Resources Information Center

Hornsby, Benjamin W. Y.; Werfel, Krystal; Camarata, Stephen; Bess, Fred H.

2014-01-01

Purpose: In this study, the authors examined the effect of hearing loss on subjective reports of fatigue in school-age children using a standardized measure. Methods: As part of a larger ongoing study, the authors obtained subjective ratings of fatigue using the Pediatric Quality of Life Inventory (PedsQL) Multidimensional Fatigue Scale (Varni,…

Cognitive Behavior Therapy to Treat Sleep Disturbance and Fatigue After Traumatic Brain Injury: A Pilot Randomized Controlled Trial.

PubMed

Nguyen, Sylvia; McKay, Adam; Wong, Dana; Rajaratnam, Shantha M; Spitz, Gershon; Williams, Gavin; Mansfield, Darren; Ponsford, Jennie L

2017-08-01

To evaluate the efficacy of adapted cognitive behavioral therapy (CBT) for sleep disturbance and fatigue in individuals with traumatic brain injury (TBI). Parallel 2-group randomized controlled trial. Outpatient therapy. Adults (N=24) with history of TBI and clinically significant sleep and/or fatigue complaints were randomly allocated to an 8-session adapted CBT intervention or a treatment as usual (TAU) condition. Cognitive behavior therapy. The primary outcome was the Pittsburgh Sleep Quality Index (PSQI) posttreatment and at 2-month follow-up. Secondary measures included the Insomnia Severity Index, Fatigue Severity Scale, Brief Fatigue Inventory (BFI), Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale. At follow-up, CBT recipients reported better sleep quality than those receiving TAU (PSQI mean difference, 4.85; 95% confidence interval [CI], 2.56-7.14). Daily fatigue levels were significantly reduced in the CBT group (BFI difference, 1.54; 95% CI, 0.66-2.42). Secondary improvements were significant for depression. Large within-group effect sizes were evident across measures (Hedges g=1.14-1.93), with maintenance of gains 2 months after therapy cessation. Adapted CBT produced greater and sustained improvements in sleep, daily fatigue levels, and depression compared with TAU. These pilot findings suggest that CBT is a promising treatment for sleep disturbance and fatigue after TBI. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Physiological signal analysis for fatigue level of experienced and inexperienced drivers.

PubMed

Li, Rui; Su, Wencheng; Lu, Zhangping

2017-02-17

We studied the changes in driving fatigue levels of experienced and inexperienced drivers at 3 periods of the day: 9:00 a.m.-12:00 p.m., 12:00 p.m.-2:00 p.m., and 4:00 p.m.-6:00 p.m. Thirty drivers were involved in 120-min real-car driving, and sleepiness ratings (Stanford Sleepiness Scale, SSS; Hoddes et al. 1973 ), electroencephalogram (EEG) signals, and heart rates (HRs) were recorded. Together with principal component analysis, the relationship between EEG signals and HR was explored and used to determine a comprehensive indicator of driving fatigue. Then the comprehensive indicator was assessed via paired t test. Experienced and inexperienced drivers behaved significantly differently in terms of subjective fatigue during preliminary trials. At the beginning of trials and after termination, subjective fatigue level was aggravated with prolonged continuous driving. Moreover, we discussed the changing rules of EEG signals and HR and found that with prolonged time, the ratios of δ and β waves significantly declined, whereas that of the θ wave significantly rose. The ratio of (α + θ)/β significantly rose both before trials and after termination, but HR dropped significantly. However, one-factor analysis of variance shows that driving experience significantly affects the θ wave, (α + θ)/β ratio, and HR. We found that in a monotonous road environment, fatigue symptoms occurred in inexperienced drivers and experienced drivers after about 60 and 80 min of continuous driving, respectively. Therefore, as for drivers with different experiences, restriction on continuous driving time would avoid fatigued driving and thereby eliminate traffic accidents. We find that the comprehensive indicator changes significantly with fatigue level. The integration of different indicators improves the recognition accuracy of different driving fatigue levels.

Benefits of interval-training on fatigue and functional capacities in Charcot-Marie-Tooth disease.

PubMed

El Mhandi, Lhassan; Millet, Guillaume Y; Calmels, Paul; Richard, Antoine; Oullion, Roger; Gautheron, Vincent; Féasson, Léonard

2008-05-01

Exercise intolerance and undue fatigue are common complaints in patients with Charcot-Marie-Tooth (CMT) disease. Reduced physical ability is due directly to the disease, but it is also due to physical deconditioning. The aim of this study was to test whether 24 weeks of interval-training exercise (ITE) cycling can significantly improve physiological, neuromuscular, and functional capacities and alleviate fatigue in CMT patients. Eight CMT patients (4 CMT1A and 4 CMT2) participated in ITE for 3 nonconsecutive days per week. Cardiovascular fitness, muscle strength, fatigue resistance, and functional capacities were measured before and after 12 weeks of supervised hospital training and again after another 12 weeks of unsupervised home training. Training was well tolerated. There were significant improvements in cardiorespiratory capacities, isokinetic concentric strength, and functional ability measurements. All patients experienced an improvement in their self-reported visual analogic scale for fatigue and pain during training. However, there was no significant change in their isometric force production and indices of fatigue resistance after training. Although the improvement in exercise tolerance may be due in part to reversal of the deconditioning effect of their related sedentary lifestyle, this clinical trial suggests that ITE can benefit CMT patients especially in their functional performance and subjective perception of pain and fatigue. Moreover, the improvement observed at the end of the first supervised period ITE was maintained after the second unsupervised home period, although there was no further improvement in performance and tolerance.

Combined modality treatment of aromatherapy, footsoak, and reflexology relieves fatigue in patients with cancer.

PubMed

Kohara, Hiroyuki; Miyauchi, Takako; Suehiro, Yoko; Ueoka, Hiroshi; Takeyama, Hiroyasu; Morita, Tatsuya

2004-12-01

Fatigue is one of the most distressful symptoms experienced by patients with advanced cancer. Aromatherapy, footsoak, and reflexology are popular health care modality treatments in Japan, however, the effectiveness of each treatment for cancer-related fatigue has not been fully established. To investigate the effectiveness of combined modality treatment consisting of aromatherapy, footsoak, and reflexology against fatigue, an open study was performed in 20 terminally ill patients with cancer. After a patch test was performed, patients received aromatherapy that was accompanied with footsoak in warm water containing lavender essential oil for 3 minutes, followed by reflexology treatment with jojoba oil containing lavender for 10 min. Fatigue was evaluated using the Cancer Fatigue Scale (CFS) before, 1 hour after, and 4 hours after treatment. Total CFS scores improved significantly after this treatment (from 25.6 +/- 11.0 to 18.1 +/- 10.0, p < 0.001). Among three CFS subscales, physical and cognitive subscale scores were reduced significantly (11.3 +/- 6.1 to 6.7 +/- 6.1, p < 0.001; 4.5 +/- 3.2 to 2.4 +/- 2.4, p < 0.001). No adverse effects were experienced. Because all patients desired to continue this treatment, they received treatment eight times on average. Combined modality treatment consisting of aromatherapy, footsoak, and reflexology appears to be effective for alleviating fatigue in terminally ill cancer patients. To confirm safety and effectiveness of this combined modality treatment, further investigation including randomized treatment assignment is warranted.

Fatigue, self-efficacy, physical activity, and quality of life in women with breast cancer.

PubMed

Haas, Barbara K

2011-01-01

More than 192 000 US women faced the challenge of living with breast cancer in 2009. Although exercise may help combat treatment-related symptoms, cancer-related fatigue has been identified as a potential barrier to engaging in physical activity. Self-efficacy has been proposed to mediate the impact of cancer-related fatigue on physical activity and subsequently improve quality of life (QOL). The purpose of this study was to determine the linkages among the concepts of an introductory model of fatigue related to cancer, self-efficacy for physical activity, physical activity, and QOL in women being treated for breast cancer. Women currently receiving treatment for breast cancer were asked to complete 5 instruments: demographic profile, Piper Fatigue Scale, Physical Activity Assessment Inventory, Human Activity Profile, and McGill QOL Questionnaire. Structural equation modeling of the data was performed to determine the direct and indirect influences of study variables on QOL. The model was tested based on responses of 73 participants. All paths between variables were significant. The model explained 53% of the variance in QOL scores, 28% of the variance in physical activity, and 31% of the variance in self-efficacy. Although fatigue is most commonly thought of as a physical problem requiring physical intervention, this study provides emerging evidence to suggest there may be potential interventions to improve self-efficacy that may mediate the effect of fatigue on QOL. Interventions to improve self-efficacy may contribute to increased physical activity and improved QOL in this population.

Investigating the effects of maximal anaerobic fatigue on dynamic postural control using the Y-Balance Test.

PubMed

Johnston, William; Dolan, Kara; Reid, Niamh; Coughlan, Garrett F; Caulfield, Brian

2018-01-01

The Y Balance Test is one of the most commonly used dynamic balance assessments, providing an insight into the integration of the sensorimotor subsystems. In recent times, there has been an increase in interest surrounding it's use in various clinical populations demonstrating alterations in motor function. Therefore, it is important to examine the effect physiological influences such as fatigue play in dynamic postural control, and establish a timeframe for its recovery. Descriptive laboratory study. Twenty male and female (age 23.75±4.79years, height 174.12±8.45cm, mass 69.32±8.76kg) partaking in competitive sport, completed the Y Balance Test protocol at 0, 10 and 20min, prior to a modified 60s Wingate fatiguing protocol. Post-fatigue assessments were then completed at 0, 10 and 20 min post-fatiguing intervention. Intraclass correlation coefficients demonstrated excellent intra-session reliability (0.976-0.982) across the three pre-fatigue YBT tests. Post-hoc paired sample t-tests demonstrated that all three reach directions demonstrated statistically significant differences between pre-fatigue and the first post-fatigue measurement (anterior; p=0.019, posteromedial; p=0.019 & posterolateral; p=0.003). The anterior reach direction returned to pre-fatigue levels within 10min (p=0.632). The posteromedial reach direction returned to pre-fatigue levels within 20min (p=0.236), while the posterolateral direction maintained a statistically significant difference at 20min (p=0.023). Maximal anaerobic fatigue has a negative effect on normalised Y balance test scores in all three directions. Following the fatiguing protocol, dynamic postural control returns to pre-fatigue levels for the anterior (<10min), posteromedial (<20min) and posterolateral (>20min). Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Test evaluation of a laminated wood wind turbine blade concept

NASA Technical Reports Server (NTRS)

Faddoul, J. R.

1981-01-01

A series of tests conducted on a root end section of a laminated wood wind turbine blade are reported. The blade to hub transition of the wood blade uses steel studs cast into the wood D spar with a filled epoxy. Both individual studs and a full scale, short length, root section were tested. Results indicate that the bonded stud concept is more than adequate for both the 30 year life fatigue loads and for the high wind or hurricane gust loads.

Comments on the origin of acoustic emission in fatigue testing of aluminum alloys

NASA Astrophysics Data System (ADS)

Heiple, C. R.; Carpenter, S. H.; Armentrout, D. L.

The size of acoustic emission (AE) signals expected from inclusion fracture during fatigue testing of 7075 aluminum has been estimated on the basis of previous measurements of AE produced by the fracture of boron particles incorporated into 2219 aluminum. The AF signal size expected from deformation in the plastic zone ahead of the fatigue crack was estimated from the results of tensile tests on 7075 aluminum. The signals predicted from both processes are near or below the noise level in the fatigue experiments and are therefore far too small to account for the signals actually observed. Nearly simultaneous fracture of multiple inclusions could produce signals as large as those observed in fatigue tests of 7075 aluminum, however, fatigue tests of 7050 aluminum produced signals as large or larger than in 7075. Since 7050 has substantially fewer inclusions than 7075, the simultaneous failure of multiple inclusions is unlikely to be a major AE source in fatigue testing of either aluminum alloy. Thus, the most probable source of acoustic emission during fatigue testing of 7075 and 7050 aluminum is the crack advance itself. The measured crack advance per cycle is large enough to release sufficient elastic energy to account for the AE signals observed.

Telehealth system (e-CUIDATE) to improve quality of life in breast cancer survivors: rationale and study protocol for a randomized clinical trial

PubMed Central

2013-01-01

Background Breast cancer survivors suffer physical impairment after oncology treatment. This impairment reduces quality of life (QoL) and increase the prevalence of handicaps associated to unhealthy lifestyle (for example, decreased aerobic capacity and strength, weight gain, and fatigue). Recent work has shown that exercise adapted to individual characteristics of patients is related to improved overall and disease-free survival. Nowadays, technological support using telerehabilitation systems is a promising strategy with great advantage of a quick and efficient contact with the health professional. It is not known the role of telerehabilitation through therapeutic exercise as a support tool to implement an active lifestyle which has been shown as an effective resource to improve fitness and reduce musculoskeletal disorders of these women. Methods / Design This study will use a two-arm, assessor blinded, parallel randomized controlled trial design. People will be eligible if: their diagnosis is of stages I, II, or IIIA breast cancer; they are without chronic disease or orthopedic issues that would interfere with ability to participate in a physical activity program; they had access to the Internet and basic knowledge of computer use or living with a relative who has this knowledge; they had completed adjuvant therapy except for hormone therapy and not have a history of cancer recurrence; and they have an interest in improving lifestyle. Participants will be randomized into e-CUIDATE or usual care groups. E-CUIDATE give participants access to a range of contents: planning exercise arranged in series with breathing exercises, mobility, strength, and stretching. All of these exercises will be assigned to women in the telerehabilitation group according to perceived needs. The control group will be asked to maintain their usual routine. Study endpoints will be assessed after 8 weeks (immediate effects) and after 6 months. The primary outcome will be QoL measured by The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 version 3.0 and breast module called The European Organization for Research and Treatment of Cancer Breast Cancer-Specific Quality of Life questionnaire. The secondary outcomes: pain (algometry, Visual Analogue Scale, Brief Pain Inventory short form); body composition; physical measurement (abdominal test, handgrip strength, back muscle strength, and multiple sit-to-stand test); cardiorespiratory fitness (International Fitness Scale, 6-minute walk test, International Physical Activity Questionnaire-Short Form); fatigue (Piper Fatigue Scale and Borg Fatigue Scale); anxiety and depression (Hospital Anxiety and Depression Scale); cognitive function (Trail Making Test and Auditory Consonant Trigram); accelerometry; lymphedema; and anthropometric perimeters. Discussion This study investigates the feasibility and effectiveness of a telerehabilitation system during adjuvant treatment of patients with breast cancer. If this treatment option is effective, telehealth systems could offer a choice of supportive care to cancer patients during the survivorship phase. Trial registration ClinicalTrials.gov Identifier: NCT01801527 PMID:23799886

Telehealth system (e-CUIDATE) to improve quality of life in breast cancer survivors: rationale and study protocol for a randomized clinical trial.

PubMed

Galiano-Castillo, Noelia; Ariza-García, Angelica; Cantarero-Villanueva, Irene; Fernández-Lao, Carolina; Díaz-Rodríguez, Lourdes; Legerén-Alvarez, Marta; Sánchez-Salado, Carmen; Del-Moral-Avila, Rosario; Arroyo-Morales, Manuel

2013-06-22

Breast cancer survivors suffer physical impairment after oncology treatment. This impairment reduces quality of life (QoL) and increase the prevalence of handicaps associated to unhealthy lifestyle (for example, decreased aerobic capacity and strength, weight gain, and fatigue). Recent work has shown that exercise adapted to individual characteristics of patients is related to improved overall and disease-free survival. Nowadays, technological support using telerehabilitation systems is a promising strategy with great advantage of a quick and efficient contact with the health professional. It is not known the role of telerehabilitation through therapeutic exercise as a support tool to implement an active lifestyle which has been shown as an effective resource to improve fitness and reduce musculoskeletal disorders of these women. This study will use a two-arm, assessor blinded, parallel randomized controlled trial design. People will be eligible if: their diagnosis is of stages I, II, or IIIA breast cancer; they are without chronic disease or orthopedic issues that would interfere with ability to participate in a physical activity program; they had access to the Internet and basic knowledge of computer use or living with a relative who has this knowledge; they had completed adjuvant therapy except for hormone therapy and not have a history of cancer recurrence; and they have an interest in improving lifestyle. Participants will be randomized into e-CUIDATE or usual care groups. E-CUIDATE give participants access to a range of contents: planning exercise arranged in series with breathing exercises, mobility, strength, and stretching. All of these exercises will be assigned to women in the telerehabilitation group according to perceived needs. The control group will be asked to maintain their usual routine. Study endpoints will be assessed after 8 weeks (immediate effects) and after 6 months. The primary outcome will be QoL measured by The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 version 3.0 and breast module called The European Organization for Research and Treatment of Cancer Breast Cancer-Specific Quality of Life questionnaire. The secondary outcomes: pain (algometry, Visual Analogue Scale, Brief Pain Inventory short form); body composition; physical measurement (abdominal test, handgrip strength, back muscle strength, and multiple sit-to-stand test); cardiorespiratory fitness (International Fitness Scale, 6-minute walk test, International Physical Activity Questionnaire-Short Form); fatigue (Piper Fatigue Scale and Borg Fatigue Scale); anxiety and depression (Hospital Anxiety and Depression Scale); cognitive function (Trail Making Test and Auditory Consonant Trigram); accelerometry; lymphedema; and anthropometric perimeters. This study investigates the feasibility and effectiveness of a telerehabilitation system during adjuvant treatment of patients with breast cancer. If this treatment option is effective, telehealth systems could offer a choice of supportive care to cancer patients during the survivorship phase. ClinicalTrials.gov Identifier: NCT01801527.

Flight Attendant Fatigue. Part 6: Fatigue Countermeasure Training and Potential Benefits

DTIC Science & Technology

2009-10-01

large. scale. surveys.of. shiftwork.facilities.have. linked.fatigue. and. shiftwork. training. to. reduced. turnover,. reduced. absenteeism ...dubas,.k ..(1986) ..The shiftworkers guide to better sleep, health and family/social relations. lincoln,. ne:.synchrotech . 14 .. saskatchewan. labour

Development of a remote-controlled fatigue test machine using a laser extensometer for investigation of irradiation effect on fatigue properties

NASA Astrophysics Data System (ADS)

Yonekawa, M.; Ishii, T.; Ohmi, M.; Takada, F.; Hoshiya, T.; Niimi, M.; Ioka, I.; Miwa, Y.; Tsuji, H.

2002-12-01

In order to investigate effects of neutron irradiation on fatigue properties of nuclear materials, a remote-controlled high temperature fatigue test machine was developed at the hot laboratory of the Japan Materials Testing Reactor (JMTR) in the Japan Atomic Energy Research Institute (JAERI). A small-sized fatigue specimen having double blades to measure strain with a laser extensometer was designed for this machine. A strain amplitude in fatigue tests of a completely reversed push-pull type using a triangular wave was controlled with an accuracy of ±3% of the total strain range during test. Low cycle fatigue tests of type 304 stainless steel irradiated in JMTR at 823 K up to a fast neutron fluence of 1×10 25 n/m 2 ( E>1 MeV) were performed in total strain ranges of 0.7-1.4% at 823 K using the designed small-sized specimens.

The role of appraisal and coping style in relation with societal participation in fatigued patients with multiple sclerosis: a cross-sectional multiple mediator analysis.

PubMed

van den Akker, Lizanne Eva; Beckerman, Heleen; Collette, Emma Hubertine; Bleijenberg, Gijs; Dekker, Joost; Knoop, Hans; de Groot, Vincent

2016-10-01

To determine the relationship between appraisal and societal participation in fatigued patients with Multiple Sclerosis (MS), and whether this relation is mediated by coping styles. 265 severely-fatigued MS patients. Appraisal, a latent construct, was created from the General Self-Efficacy Scale and the helplessness and acceptance subscales of the Illness Cognition Questionnaire. Coping styles were assessed using the Coping Inventory Stressful Situations (CISS21) and societal participation was assessed using the Impact on Participation and Autonomy. A multiple mediator model was developed and tested by structural equation modeling on cross-sectional data. We corrected for confounding by disease-related factors. Mediation was determined using a product-of-coefficients approach. A significant relationship existed between appraisal and participation (β = 0.21, 95 % CI 0.04-0.39). The pathways via coping styles were not significant. In patients with severe MS-related fatigue, appraisal and societal participation show a positive relationship that is not mediated by coping styles.

Insomnia and Sleepiness in Parkinson Disease: Associations with Symptoms and Comorbidities

PubMed Central

Chung, Seockhoon; Bohnen, Nicolaas I.; Albin, Roger L.; Frey, Kirk A.; Müller, Martijn L. T. M.; Chervin, Ronald D.

2013-01-01

Study Objectives: Insomnia and daytime sleepiness are common complaints in Parkinson disease (PD), but the main causes remain unclear. We examined the potential impact of both motor and non-motor symptoms of PD on sleep problems. Methods: Patients with PD (n = 128) were assessed using the Insomnia Severity Index, Epworth Sleepiness Scale, Unified Parkinson Disease Rating Scale, Beck Depression Inventory, Fatigue Severity Scale, Survey of Autonomic Symptoms, and the 39-item Parkinson Disease Questionnaire. A subset of subjects (n = 38, 30%) also completed nocturnal polysomnography and a multiple sleep latency test (MSLT). Results: Multivariate stepwise logistic regression models revealed that subjective insomnia was independently associated with depressed mood (odds ratio [OR] = 1.79; 95% confidence interval (CI) [1.01-3.19]), autonomic symptoms (1.77 [1.08-2.90]), fatigue (1.19 [1.02-1.38]), and age (0.61 [0.39-0.96]). Subjective daytime sleepiness was associated with dosage of dopaminergic medication (1.74 [1.08-2.80]) and fatigue (1.14 [1.02-1.28]). On polysomnography, longer sleep latency correlated with autonomic symptoms (rho = 0.40, p = 0.01) and part I (non-motor symptoms) of the Unified PD Rating Scale (rho = 0.38, p = 0.02). Decreased sleep efficiency correlated with autonomic symptoms (rho = -0.42, p < 0.0001). However, no significant difference emerged on polysomnography and MSLTs between patients with or without insomnia or daytime sleepiness. Higher rates of apneic events did predict shorter sleep latencies on the MSLTs. Conclusions: Non-motor symptoms appear to be associated with subjective insomnia, whereas fatigue and dopaminergic medication are associated with subjective daytime sleepiness. Objective sleep laboratory data provided little insight into complaints of insomnia and sleepiness, though obstructive sleep apnea predicted worsened sleepiness when measured objectively. Citation: Chung S; Bohnen NI; Albin RL; Frey KA; Müller MLTM; Chervin RD. Insomnia and sleepiness in Parkinson disease: associations with symptoms and comorbidities. J Clin Sleep Med 2013;9(11):1131-1137. PMID:24235893

Evaluation of the durability of composite tidal turbine blades.

PubMed

Davies, Peter; Germain, Grégory; Gaurier, Benoît; Boisseau, Amélie; Perreux, Dominique

2013-02-28

The long-term reliability of tidal turbines is critical if these structures are to be cost effective. Optimized design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades, but there are few data available to predict material behaviour under coupled environmental and cycling loading. The present study addresses this problem, by introducing a multi-level framework for turbine blade qualification. At the material scale, static and cyclic tests have been performed, both in air and in sea water. The influence of ageing in sea water on fatigue performance is then quantified, and much lower fatigue lives are measured after ageing. At a higher level, flume tank tests have been performed on three-blade tidal turbines. Strain gauging of blades has provided data to compare with numerical models.

75 FR 75882 - Airworthiness Directives; British Aerospace Regional Aircraft Models Jetstream Series 3101 and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-07

... describes the unsafe condition as: As a result of the fatigue-testing programme on the Jetstream fatigue... result of the fatigue-testing programme on the Jetstream fatigue test specimen, it has been identified....S. registry. We also estimate that it will take about 15 work-hours per product to comply with the...

A literature review and inventory of the effects of environment on the fatigue behavior of metals

NASA Technical Reports Server (NTRS)

Hudson, C. M.; Seward, S. K.

1976-01-01

The current state of knowledge of the effects of gas environments (at atmospheric pressure and below) on the fatigue behavior of metals is reviewed. Among the topics considered are the mechanisms proposed to explain the differences observed in the fatigue behavior of vacuum- and air-tested specimens, the effects of environment on the surface topography of fatigue cycled specimens, the effect of environment on the various phases of the fatigue phenomenon, the effect of prolonged exposure to vacuum on fatigue life, the variation of fatigue life with decreasing gas pressure, and gas evolution during fatigue cycling. Analysis of the findings of this review indicates that hydrogen embrittlement is primarily responsible for decreased fatigue resistance in humid environments, and that dislocations move more easily during tests in vacuum than during test in air. It was found that fatigue cracks generally initiated and propagated more rapidly in air than in vacuum. Prolonged exposure to vacuum does not adversely affect fatigue resistance. The variation of fatigue life with decreasing gas pressure is sometimes stepped and sometimes continuous.

Association between work ability and fatigue in Brazilian nursing workers.

PubMed

da Silva, Fabio José; Felli, Vanda Elisa Andres; Martinez, Maria Carmen; Mininel, Vivian Aline; Ratier, Ana Paula Pelegrini

2015-01-01

Impaired work ability is associated with work-related illnesses, early retirement and rising pension costs. To investigate the association between work ability and fatigue in nursing workers. Cross-sectional study conducted with 100 nursing workers from two inpatient units at a public teaching hospital in Sao Paulo, Brazil. The data were collected by means of a socio-demographic profile questionnaire, Work Ability Index (WAI) and Chalder Fatigue Scale. The data were analyzed by means of descriptive and analytical statistical methods, tests of association and multiple linear regression. The study population was mainly composed of women (88% ), exhibited a high educational level (76% ), average age 39.4 years old (SD = 9.5) and 15 years of professional experience, on average. The average score on WAI was good (39.4 points, SD = 6.0) but surprisingly, 35% of the participants exhibited moderate to poor work ability. Fatigue was found in 52% of the participants. The score on WAI decreased in association with fatigue (p <  0.001) and longer length of work in the same workplace (p = 0.001), as well as among nursing technicians compared to nurses (p = 0.040). Fatigue, longer length of work in the same workplace and work category nursing technician were associated with decreased work ability, which emphasizes the need for investment in health and quality of work life.

Group versus individual stress management intervention in breast cancer patients for fatigue and emotional reactivity: a randomised intervention study.

PubMed

Rissanen, Ritva; Arving, Cecilia; Ahlgren, Johan; Nordin, Karin

2014-09-01

Fatigue and emotional reactivity are common among women suffering from breast cancer and might detrimentally affect these women's quality of life. This study evaluates if the stress management delivered either in a group or individual setting would improve fatigue and emotional reactivity among women with a newly diagnosed breast cancer. Participants (n = 304) who reported elevated levels of distress at three-month post-inclusion were randomised between stress management in a group (GSM) (n = 77) or individual (ISM) (n = 78) setting. Participation was declined by 149 women. Participants completed the Multidimensional Fatigue Inventory (MFI-20) and the Everyday Life Stress Scale (ELSS) at the time of inclusion, 3- and 12-month post-inclusion. Analyses were made according to intention to treat and per-protocol principles. Mann-Whitney tests were used to examine differences between the two intervention groups. No significant differences were detected between the GSM and ISM groups on fatigue or emotional reactivity. In addition, there were no changes over time for these outcomes. There were no differences between the two intervention arms with reference to fatigue or emotional reactivity; however, a clinically interesting finding was the low number of women who were interested in participating in a psychosocial intervention. This finding may have clinical implications when psychosocial support is offered to women with a newly diagnosed breast cancer and also in the planning of future studies.

Fatigue Behavior of Steel Fiber Reinforced High-Strength Concrete under Different Stress Levels

NASA Astrophysics Data System (ADS)

Zhang, Chong; Gao, Danying; Gu, Zhiqiang

2017-12-01

The investigation was conducted to study the fatigue behavior of steel fiber reinforced high-strength concrete (SFRHSC) beams. A series of 5 SFRHSC beams was conducted flexural fatigue tests at different stress level S of 0.5, 0.55, 0.6, 0.7 and 0.8 respectively. Static test was conducted to determine the ultimate static capacity prior to fatigue tests. Fatigue modes and S-N curves were analyzed. Besides, two fatige life prediction model were analyzed and compared. It was found that stress level S significantly influenced the fatigue life of SFRHSC beams and the fatigue behavior of SFRHSC beams was mainly determined by the tensile reinforcement.

Tension and fatigue behavior of 316LVM 1x7 multi-strand cables used as implantable electrodes.

PubMed

Lewandowski, John J; Varadarajan, Ravikumar; Smith, Brian; Tuma, Chris; Shazly, Mostafa; Vatamanu, Luciano O

2008-07-15

The mechanical behavior of 316LVM 1x7 cables were evaluated in uniaxial tension, and in cyclic strain-controlled fatigue with the use of a Flex tester operated to provide fully reversed bending fatigue. The magnitude of cyclic strains imparted to each cable tested was controlled via the use of different diameter mandrels. Smaller diameter mandrels produced higher values of cyclic strain and lower fatigue life. Multiple samples were tested and analyzed via scanning electron microscopy. The fatigue results were analyzed via a Coffin-Manson-Basquin approach and compared to fatigue data obtained from the literature where testing was conducted on similar materials, but under rotating bending fatigue conditions.

Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations

NASA Technical Reports Server (NTRS)

Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin; Minguet, Pierre J.

2001-01-01

A methodology is presented for determining the fatigue life of composite structures based on fatigue characterization data and geometric nonlinear finite element (FE) analyses. To demonstrate the approach, predicted results were compared to fatigue tests performed on specimens which represented a tapered composite flange bonded onto a composite skin. In a first step, tension tests were performed to evaluate the debonding mechanisms between the flange and the skin. In a second step, a 2D FE model was developed to analyze the tests. To predict matrix cracking onset, the relationship between the tension load and the maximum principal stresses transverse to the fiber direction was determined through FE analysis. Transverse tension fatigue life data were used to -enerate an onset fatigue life P-N curve for matrix cracking. The resulting prediction was in good agreement with data from the fatigue tests. In a third step, a fracture mechanics approach based on FE analysis was used to determine the relationship between the tension load and the critical energy release rate. Mixed mode energy release rate fatigue life data were used to create a fatigue life onset G-N curve for delamination. The resulting prediction was in good agreement with data from the fatigue tests. Further, the prediction curve for cumulative life to failure was generated from the previous onset fatigue life curves. The results showed that the methodology offers a significant potential to Predict cumulative fatigue life of composite structures.

Flight service evaluation of composite helicopter components

NASA Technical Reports Server (NTRS)

Rich, M. J.; Lowry, D. W.

1985-01-01

An assessment of composite helicopter structures, exposed to environmental effects, after four years of commercial service is presented. This assessment is supported by test results of helicopter components and test panels which have been exposed to environmental effects since late 1979. Full scale static and fatigue tests are being conducted on composite components obtained from S-76 helicopters in commercial operations in the Gulf Coast region of Louisiana. Small scale tests are being conducted on coupons obtained from panels being exposed to outdoor conditions in Stratford, Connecticut and West Palm Beach, Florida. The panel layups represent S-76 components. Moisture evaluations and strength tests are being conducted, on the S-76 components and panels, over a period of eight years. Results are discussed for components and panels with up to four years of exposure.

Energy-based fatigue model for shape memory alloys including thermomechanical coupling

NASA Astrophysics Data System (ADS)

Zhang, Yahui; Zhu, Jihong; Moumni, Ziad; Van Herpen, Alain; Zhang, Weihong

2016-03-01

This paper is aimed at developing a low cycle fatigue criterion for pseudoelastic shape memory alloys to take into account thermomechanical coupling. To this end, fatigue tests are carried out at different loading rates under strain control at room temperature using NiTi wires. Temperature distribution on the specimen is measured using a high speed thermal camera. Specimens are tested to failure and fatigue lifetimes of specimens are measured. Test results show that the fatigue lifetime is greatly influenced by the loading rate: as the strain rate increases, the fatigue lifetime decreases. Furthermore, it is shown that the fatigue cracks initiate when the stored energy inside the material reaches a critical value. An energy-based fatigue criterion is thus proposed as a function of the irreversible hysteresis energy of the stabilized cycle and the loading rate. Fatigue life is calculated using the proposed model. The experimental and computational results compare well.

Spectrum Fatigue of 7075-T651 Aluminum Alloy under Overloading and Underloading

DTIC Science & Technology

2016-03-15

underload, stress ratio, and environment on fatigue crack growth. Fatigue crack growth tests were conducted with a 7075-T651 aluminum alloy under constant...the UniGrow equation, the variation of crack length with number of loading cycle was predicted. The prediction and the fatigue test life were found to...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39-18 REPORT NO. NAWCADPAX/TIM-2015/282 ii SUMMARY Fatigue tests of 7075-T651

Multidimensional Fatigue Inventory: Spanish adaptation and psychometric properties for fibromyalgia patients. The Al-Andalus study.

PubMed

Munguía-Izquierdo, Diego; Segura-Jiménez, Victor; Camiletti-Moirón, Daniel; Pulido-Martos, Manuel; Alvarez-Gallardo, Inmaculada C; Romero, Alejandro; Aparicio, Virginia A; Carbonell-Baeza, Ana; Delgado-Fernández, Manuel

2012-01-01

The aim of this study was to assess the psychometric properties and transcultural adaptation into Spanish of the Multidimensional Fatigue Inventory in fibromyalgia patients. The Spanish version of the Multidimensional Fatigue Inventory (MFI-S) was translated and cognitively pretested following cross-cultural adaptation guidelines. Test-retest reliability, convergent validity, and operational qualities were evaluated in a total of 116 fibromyalgia patients. Convergent validity was assessed comparing MFI-S with a visual analogue scale for global fatigue. The intra-class correlation coefficients varied from moderate to excellent (from 0.64 to 0.91) and the standard errors of the mean ranged from 0.5 to 1.1 points for the five MFI-S domains. The coefficient of repeatability was less than 2 standard deviations and the limits of agreement ranged from 2 to 4 points for the MFI-S domains. A weak to fair significant relationship was found between each MFI-S domain and the visual analogue scale (from 0.21 to 0.32). The mean time required to complete the MFI-S was 3.2±2.0 minutes. None of the patients needed external help to complete the MFI-S, and there were very few missing values. The MFI-S developed in this study presents a good reliability and reasonable construct validity for Spanish fibromyalgia patients unaffected by cognitive dysfunction and severe depression. This questionnaire is quick, easy to administer and interpret.

Investigation of Gear and Bearing Fatigue Damage Using Debris Particle Distributions

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Lewicki, David G.; Decker, Harry J.

2004-01-01

A diagnostic tool was developed for detecting fatigue damage to spur gears, spiral bevel gears, and rolling element bearings. This diagnostic tool was developed and evaluated experimentally by collecting oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig, Spiral Bevel Gear Test Facility, and the 500hp Helicopter Transmission Test Stand. During each test, data from an online, in-line, inductance type oil debris sensor was monitored and recorded for the occurrence of pitting damage. Results indicate oil debris alone cannot discriminate between bearing and gear fatigue damage.

Relationship between social support and fatigue in patients with type 2 diabetes mellitus in the east of Turkey.

PubMed

Aylaz, Rukuye; Karadağ, Ezgi; Işik, Kevser; Yildirim, Melek

2015-10-01

This study was planned to assess the levels of fatigue and social support in patients with diabetes and to determine the relationship between fatigue and social support in these patients. A descriptive design was used in this research. The study was conducted between March and June 2013 with 300 sampled patients from 1657 studied participants with type 2 diabetes who presented to the diabetes polyclinics of Malatya State Hospital and Inonu University, Turgut Ozal Medical Center. The Multidimensional Scale of Perceived Social Support and the Fatigue Severity Scale were used in the study. When the correlation analysis carried out between fatigue severity and social support in patients with diabetes was examined, a significant relationship was found in the negative direction between fatigue severity and family support (r = -0.145, P < 0.05) as well as overall support (r = -0.132, P < 0.05). A statistically significant difference was found between the Fatigue Severity Scale score and sex, education status, occupation, cohabitation, presence of complications, and hemoglobin A1c (P < 0.05). Family support was significant only with respect to marital status, occupation, and being employed (P < 0.05). It was seen at the end of this research that social support reduced the level of fatigue in a number of patients with type 2 diabetes. Nurses of diabetes patients should carry out fatigue assessments routinely and reflect these in nursing care plans by also associating them with the social support sources of the patient. © 2015 The Authors. Japan Journal of Nursing Science © 2015 Japan Academy of Nursing Science.

Influence of sustained submaximal clenching fatigue test on electromyographic activity and maximum voluntary bite forces in healthy subjects and patients with temporomandibular disorders.

PubMed

Xu, L; Fan, S; Cai, B; Fang, Z; Jiang, X

2017-05-01

This study aimed to investigate whether the fatigue induced by sustained motor task in the jaw elevator muscles differed between healthy subjects and patients with temporomandibular disorder (TMD). Fifteen patients with TMD and thirteen age- and sex-matched healthy controls performed a fatigue test consisting of sustained clenching contractions at 30% maximal voluntary clenching intensity until test failure (the criterion for terminating the fatigue test was when the biting force decreased by 10% or more from the target force consecutively for >3 s). The pre- and post-maximal bite forces (MBFs) were measured. Surface electromyographic signals were recorded from the superficial masseter muscles and anterior temporal muscles bilaterally, and the median frequency at the beginning, middle and end of the fatigue test was calculated. The duration of the fatigue test was also quantified. Both pre- and post-MBFs were lower in patients with TMD than in controls (P < 0·01). No significant difference was found in the percentage change in MBF between groups. The duration of the fatigue test in TMD patients was significantly shorter than that of the controls (P < 0·05). Our results suggest that, compared to healthy subjects, patients with TMD become more easily fatigued, but the electromyographic activation process during the fatigue test is similar between healthy subjects and patients with TMD. However, the mechanisms involved in this process remain unclear, and further research is warranted. © 2017 John Wiley & Sons Ltd.

Fatigue damage assessment of high-usage in-service aircraft fuselage structure

NASA Astrophysics Data System (ADS)

Mosinyi, Bao Rasebolai

As the commercial and military aircraft fleets continue to age, there is a growing concern that multiple-site damage (MSD) can compromise structural integrity. Multiple site damage is the simultaneous occurrence of many small cracks at independent structural locations, and is the natural result of fatigue, corrosion, fretting and other possible damage mechanisms. These MSD cracks may linkup and form a fatigue lead crack of critical length. The presence of MSD also reduces the structure's ability to withstand longer cracks. The objective of the current study is to assess, both experimentally and analytically, MSD formation and growth in the lap joint of curved panels removed from a retired aircraft. A Boeing 727-232 airplane owned and operated by Delta Air Lines, and retired at its design service goal, was selected for the study. Two panels removed from the left-hand side of the fuselage crown, near stringer 4L, were subjected to extended fatigue testing using the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration (FAA) William J. Hughes Technical Center. The state of MSD was continuously assessed using several nondestructive inspection (NDI) methods. Damage to the load attachment points of the first panel resulted in termination of the fatigue test at 43,500 fatigue cycles, before cracks had developed in the lap joint. The fatigue test for the second panel was initially conducted under simulated in-service loading conditions for 120,000 cycles, and no cracks were detected in the skin of the panel test section. Artificial damage was then introduced into the panel at selected rivets in the critical (lower) rivet row, and the fatigue loads were increased. Visually detectable crack growth from the artificial notches was first seen after 133,000 cycles. The resulting lead crack grew along the lower rivet row, eventually forming an 11.8" long unstable crack after 141,771 cycles, at which point the test was terminated. Posttest fractograpic examinations of the crack surfaces were conducted, revealing the presence of subsurface MSD at the critical rivet row of the lap joint. Special attention was also given to the stringer clips that attach the fuselage frames to the stringers, since they also experienced cracking during the fatigue tests. The performance of the different conventional and emerging NDI methods was also assessed, and some of the emerging NDI methods were quite effective in detecting and measuring the length of subsurface cracks. Delta Air Lines conducted a separate destructive investigation on the state of damage along the right-hand side of the fuselage, near stringer 4R. A comparison of these two studies showed that the lap joint on the left hand-side of the aircraft, along stringer 4L, had better fatigue life than the one on the opposite side, along stringer 4R. The cause of the difference in fatigue life was investigated by close examination of the rivet installation qualities, and was found to be a result of better rivet installation along the lap joint at stringer 4L. Finite element models for both the skin and substructures of the panels were developed and geometrically nonlinear finite element analyses were conducted to verify the loading conditions and to determine near-field parameters governing MSD initiation and growth. Fatigue crack growth predictions based on the NASGRO equation were in good agreement with the experimental crack growth data for through-the-thickness cracks. For subsurface cracks, simulation of crack growth was found to correlate better with fractography data when an empirical crack growth model was used. The results of the study contribute to the understanding of the initiation and growth of MSD in the inner skin layer of a lap joint, and provide valuable data for the evaluation and validation of analytical methodologies to predict MSD initiation and growth and a better understanding on the effect of manufacturing quality on damage accumulation along the lap joint.

Impact of Depression, Fatigue, and Global Measure of Cortical Volume on Cognitive Impairment in Multiple Sclerosis

PubMed Central

De Cola, Maria Cristina; D'Aleo, Giangaetano; Sessa, Edoardo; Marino, Silvia

2015-01-01

Objective. To investigate the influence of demographic and clinical variables, such as depression, fatigue, and quantitative MRI marker on cognitive performances in a sample of patients affected by multiple sclerosis (MS). Methods. 60 MS patients (52 relapsing remitting and 8 primary progressive) underwent neuropsychological assessments using Rao's Brief Repeatable Battery of Neuropsychological Tests (BRB-N), the Beck Depression Inventory-second edition (BDI-II), and the Fatigue Severity Scale (FSS). We performed magnetic resonance imaging to all subjects using a 3 T scanner and obtained tissue-specific volumes (normalized brain volume and cortical brain volume). We used Student's t-test to compare depressed and nondepressed MS patients. Finally, we performed a multivariate regression analysis in order to assess possible predictors of patients' cognitive outcome among demographic and clinical variables. Results. 27.12% of the sample (16/59) was cognitively impaired, especially in tasks requiring attention and information processing speed. From between group comparison, we find that depressed patients had worse performances on BRB-N score, greater disability and disease duration, and brain volume decrease. According to multiple regression analysis, the BDI-II score was a significant predictor for most of the neuropsychological tests. Conclusions. Our findings suggest that the presence of depressive symptoms is an important determinant of cognitive performance in MS patients. PMID:25861633

The measured contribution of whipping and springing on the fatigue and extreme loading of container vessels

NASA Astrophysics Data System (ADS)

Storhaug, Gaute

2014-12-01

Whipping/springing research started in the 50'ies. In the 60'ies inland water vessels design rules became stricter due to whipping/springing. The research during the 70-90'ies may be regarded as academic. In 2000 a large ore carrier was strengthened due to severe cracking from North Atlantic operation, and whipping/springing contributed to half of the fatigue damage. Measurement campaigns on blunt and slender vessels were initiated. A few blunt ships were designed to account for whipping/springing. Based on the measurements, the focus shifted from fatigue to extreme loading. In 2005 model tests of a 4,400 TEU container vessel included extreme whipping scenarios. In 2007 the 4400 TEU vessel MSC Napoli broke in two under similar conditions. In 2009 model tests of an 8,600 TEU container vessel container vessel included extreme whipping scenarios. In 2013 the 8,100 TEU vessel MOL COMFORT broke in two under similar conditions. Several classification societies have published voluntary guidelines, which have been used to include whipping/springing in the design of several container vessels. This paper covers results from model tests and full scale measurements used as background for the DNV Legacy guideline. Uncertainties are discussed and recommendations are given in order to obtain useful data. Whipping/springing is no longer academic.

Thermal-Mechanical Fatigue Testing of a Titanium-Aluminide Alloy.

DTIC Science & Technology

1987-12-01

DIMSTRIBUTION STA Approved for pubi robing e% dQ *- AFIT/GAB/AA/87D-18 THERMAL-MECHANICAL FATIGUE TESTING OF A TITANIUM - ALUMINIDE ALLOY THESIS John J...THERMAL-MECHANICAL FATIGUE TESTING OF A TITANIUM - ALUMINIDE ALLOY THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute...develop a Thermal-Mechanical Fatigue (TMF) testing system for titanium - aluminide compact tension specimens. I could not have accomplished this without the

Single-leg hop testing following fatiguing exercise: reliability and biomechanical analysis.

PubMed

Augustsson, J; Thomeé, R; Lindén, C; Folkesson, M; Tranberg, R; Karlsson, J

2006-04-01

A fatiguing exercise protocol was combined with single-leg hop testing to improve the possibilities of evaluating the effects of training or rehabilitation interventions. In the first test-retest experiment, 11 healthy male subjects performed two trials of single-leg hops under three different test conditions: non-fatigued and following fatiguing exercise, which consisted of unilateral weight machine knee extensions at 80% and 50%, respectively, of 1 repetition maximum (1 RM) strength. Intraclass correlation coefficients ranged from 0.75 to 0.98 for different hop test conditions, indicating that all tests were reliable. For the second experiment, eight healthy male subjects performed the fatiguing exercise protocol to investigate how fatigue influences lower-extremity joint kinematics and kinetics during single-leg hops. Hip, knee and ankle joint angles, moments and powers, as well as ground-reaction forces were recorded with a six-camera, motion-capture system and a force platform. Recovery of hop performance following the fatiguing exercise was also measured. During the take-off for the single-leg hops, hip and knee flexion angles, generated powers for the knee and ankle joints, and ground-reaction forces decreased for the fatigued hop conditions compared with the non-fatigued condition (P<0.05). Compared with landing during the non-fatigued condition, hip moments and ground-reaction forces were lower for the fatigued hop conditions (P<0.05). The negative joint power was two to three times greater for the knee than for the hip and five to 10 times greater for the knee than for the ankle during landing for all test conditions (P<0.05). Most measured variables had recovered three minutes post-exercise. It is concluded that the fatiguing exercise protocol combined with single-leg hop testing was a reliable method for investigating functional performance under fatigued test conditions. Further, subjects utilized an adapted hop strategy, which employed less hip and knee flexion and generated powers for the knee and ankle joints during take-off, and less hip joint moments during landing under fatigued conditions. The large negative power values observed at the knee joint during the landing phase of the single-leg hop, during which the quadriceps muscle activates eccentrically, indicate that not only hop distance but also the ability to perform successful landings should be investigated when assessing dynamic knee function.

Solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses

PubMed Central

Launey, Maximilien E.; Hofmann, Douglas C.; Johnson, William L.; Ritchie, Robert O.

2009-01-01

The recent development of metallic glass-matrix composites represents a particular milestone in engineering materials for structural applications owing to their remarkable combination of strength and toughness. However, metallic glasses are highly susceptible to cyclic fatigue damage, and previous attempts to solve this problem have been largely disappointing. Here, we propose and demonstrate a microstructural design strategy to overcome this limitation by matching the microstructural length scales (of the second phase) to mechanical crack-length scales. Specifically, semisolid processing is used to optimize the volume fraction, morphology, and size of second-phase dendrites to confine any initial deformation (shear banding) to the glassy regions separating dendrite arms having length scales of ≈2 μm, i.e., to less than the critical crack size for failure. Confinement of the damage to such interdendritic regions results in enhancement of fatigue lifetimes and increases the fatigue limit by an order of magnitude, making these “designed” composites as resistant to fatigue damage as high-strength steels and aluminum alloys. These design strategies can be universally applied to any other metallic glass systems. PMID:19289820

Experimental Investigation and Finite Element Analysis on Fatigue Behavior of Aluminum Alloy 7050 Single-Lap Joints

NASA Astrophysics Data System (ADS)

Zhou, Bing; Cui, Hao; Liu, Haibo; Li, Yang; Liu, Gaofeng; Li, Shujun; Zhang, Shangzhou

2018-03-01

The fatigue behavior of single-lap four-riveted aluminum alloy 7050 joints was investigated by using high-frequency fatigue test and scanning electron microscope (SEM). Stress distributions obtained by finite element (FE) analysis help explain the fatigue performance. The fatigue test results showed that the fatigue lives of the joints depend on cold expansion and applied cyclic loads. FE analysis and fractography indicated that the improved fatigue lives can be attributed to the reduction in maximum stress and evolution of fatigue damage at the critical location. The beneficial effects of strengthening techniques result in tearing ridges or lamellar structure on fracture surface, decrease in fatigue striations spacing, delay of fatigue crack initiation, crack deflection in fatigue crack propagation and plasticity-induced crack closure.

Fatigue Lives Of Laser-Cut Metals

NASA Technical Reports Server (NTRS)

Martin, Michael R.

1988-01-01

Fatigue lives made to approach those attainable by traditional grinding methods. Fatigue-test specimens prepared from four metallic alloys, and material removed from specimens by manual grinding, by Nd:glass laser, and by Nd:YAG laser. Results of fatigue tests of all specimens indicated reduction of fatigue strengths of laser-fired specimens. Laser machining holds promise for improved balancing of components of gas turbines.

The impact of physical complaints, social environment, and psychological functioning on IBS patients' health perceptions: looking beyond GI symptom severity.

PubMed

Lackner, Jeffrey M; Gudleski, Gregory D; Thakur, Elyse R; Stewart, Travis J; Iacobucci, Gary J; Spiegel, Brennan Mr

2014-02-01

In the absence of a reliable biomarker, clinical decisions for a functional gastrointestinal (GI) disorder like irritable bowel syndrome (IBS) depend on asking patients to appraise and communicate their health status. Self-ratings of health (SRH) have proven a powerful and consistent predictor of health outcomes, but little is known about how they relate to those relevant to IBS (e.g., quality of life (QOL), IBS symptom severity). This study examined what psychosocial factors, if any, predict SRH among a cohort of more severe IBS patients. Subjects included 234 Rome III-positive IBS patients (mean age=41 years, female=78%) without comorbid organic GI disease. Subjects were administered a test battery that included the IBS Symptom Severity Scale, Screening for Somatoform Symptoms, IBS Medical Comorbidity Inventory, SF-12 Vitality Scale, Perceived Stress Scale, Beck Depression Inventory, Trait Anxiety Inventory, and Negative Interactions Scale. Partial correlations identified somatization, depression, fatigue, stress, anxiety, and medical comorbidities as variables with the strongest correlations with SRH (r values=0.36-0.41, P values <0.05). IBS symptom severity was weakly associated with SRH (r=0.18, P<0.05). The final regression model explained 41.3% of the variance in SRH scores (F=8.49, P<0.001) with significant predictors including fatigue, medical comorbidities, somatization, and negative social interactions. SRH are associated with psychological (anxiety, stress, depression), social (negative interactions), and extraintestinal somatic factors (fatigue, somatization, medical comorbidities). The severity of IBS symptoms appears to have a relatively modest role in how IBS patients describe their health in general.

Fatigue life prediction of liquid rocket engine combustor with subscale test verification

NASA Astrophysics Data System (ADS)

Sung, In-Kyung

Reusable rocket systems such as the Space Shuttle introduced a new era in propulsion system design for economic feasibility. Practical reusable systems require an order of magnitude increase in life. To achieve this improved methods are needed to assess failure mechanisms and to predict life cycles of rocket combustor. A general goal of the research was to demonstrate the use of subscale rocket combustor prototype in a cost-effective test program. Life limiting factors and metal behaviors under repeated loads were surveyed and reviewed. The life prediction theories are presented, with an emphasis on studies that used subscale test hardware for model validation. From this review, low cycle fatigue (LCF) and creep-fatigue interaction (ratcheting) were identified as the main life limiting factors of the combustor. Several life prediction methods such as conventional and advanced viscoplastic models were used to predict life cycle due to low cycle thermal stress, transient effects, and creep rupture damage. Creep-fatigue interaction and cyclic hardening were also investigated. A prediction method based on 2D beam theory was modified using 3D plate deformation theory to provide an extended prediction method. For experimental validation two small scale annular plug nozzle thrusters were designed, built and tested. The test article was composed of a water-cooled liner, plug annular nozzle and 200 psia precombustor that used decomposed hydrogen peroxide as the oxidizer and JP-8 as the fuel. The first combustor was tested cyclically at the Advanced Propellants and Combustion Laboratory at Purdue University. Testing was stopped after 140 cycles due to an unpredicted failure mechanism due to an increasing hot spot in the location where failure was predicted. A second combustor was designed to avoid the previous failure, however, it was over pressurized and deformed beyond repair during cold-flow test. The test results are discussed and compared to the analytical and numerical predictions. A detailed comparison was not performed, however, due to the lack of test data resulting from a failure of the test article. Some theoretical and experimental aspects such as fin effect and round corner were found to reduce the discrepancy between prediction and test results.

Determining the minimal clinically important difference criteria for the Multidimensional Fatigue Inventory in a radiotherapy population.

PubMed

Purcell, Amanda; Fleming, Jennifer; Bennett, Sally; Burmeister, Bryan; Haines, Terry

2010-03-01

The Multidimensional Fatigue Inventory (MFI) is a commonly used cancer-related fatigue assessment tool. Unlike other fatigue assessments, there are no published minimal clinically important difference (MCID) criteria for the MFI in cancer populations. MCID criteria determine the smallest change in scores that can be regarded as important, allowing clinicians and researchers to interpret the meaning of changes in patient's fatigue scores. This research aims to improve the clinical utility of the MFI by establishing MCID criteria for the MFI sub-scales in a radiotherapy population. Two hundred ten patients undergoing radiotherapy were recruited to a single-centre prospective cohort study. Patients were assessed at three time points, at the start of radiotherapy, the end of radiotherapy and 6 weeks after radiotherapy completion. Assessment consisted of four clinically relevant constructs: (1) treatment impact on fatigue, (2) health-related quality of life, (3) performance status and (4) occupational productivity. These constructs were used as external or anchor-based measures to determine MCIDs for each sub-scale of the MFI. Multiple MCIDs were identified, each from a different perspective based on the constructs cited. Researchers seeking to use a generic MCID may wish to use a two-point reference for each MFI sub-scale as it was consistent across the pre- and post-radiotherapy comparison and occupational productivity anchors. MCIDs validated in this study allow better interpretation of changes in MFI sub-scale scores and allow effect size calculations for determining sample size in future studies.

Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequencing Effects

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh; Bonacuse, Peter J.

2000-01-01

Cumulative fatigue behavior of a wrought cobalt-base superalloy, Haynes 188 was investigated at 538 C under various single-step sequences of axial and torsional loading conditions. Initially, fully-reversed, axial and torsional fatigue tests were conducted under strain control at 538 C on thin-walled tubular specimens to establish baseline fatigue life relationships. Subsequently, four sequences (axial/axial, torsional/torsional, axial/torsional, and torsional/axial) of two load-level fatigue tests were conducted to characterize both the load-order (high/low) and load-type sequencing effects. For the two load-level tests, summations of life fractions and the remaining fatigue lives at the second load-level were computed by the Miner's Linear Damage Rule (LDR) and a nonlinear Damage Curve Approach (DCA). In general, for all four cases predictions by LDR were unconservative. Predictions by the DCA were within a factor of two of the experimentally observed fatigue lives for a majority of the cumulative axial and torsional fatigue tests.

Rolling-element fatigue life of AMS 5749 corrosion resistant, high temperature bearing steel

NASA Technical Reports Server (NTRS)

Parker, R. J.; Hodder, R. S.

1977-01-01

The rolling element fatigue lives of AMS 5749 and AISI M-50 were compared in tests run in the five ball fatigue tester and the rolling contact fatigue tester. The effects of double vacuum melting and retained austenite on the life of AMS 5749 were determined in five ball fatigue tests. The double vacuum melting process consisted of induction vacuum melting followed by vacuum arc remelting (VIM-VAR). In the five ball tests, VIM-VAR AMS 5749 gave lives at least six times that of VIM-VAR AISI M-50. Similar tests in the rolling contact fatigue tester showed no significant difference in the lives of the two materials. The rolling element fatigue life of VIM-VAR AMS 5749 was at least 14 times that of vacuum induction melted AMS 5749. A trend toward increased rolling element fatigue life with decreased retained austenite is apparent, but the confidence that all experimental differences are significant is not great.

A preliminary placebo-controlled crossover trial of fludrocortisone for chronic fatigue syndrome.

PubMed

Peterson, P K; Pheley, A; Schroeppel, J; Schenck, C; Marshall, P; Kind, A; Haugland, J M; Lambrecht, L J; Swan, S; Goldsmith, S

1998-04-27

To provide a preliminary assessment of the efficacy and safety of fludrocortisone acetate treatment of chronic fatigue syndrome. A placebo-controlled, double-blind, random-allocation crossover trial of 6 weeks of fludrocortisone. An outpatient clinical trials unit. Twenty-five participants with chronic fatigue syndrome (mean age, 40 years; 19 [76%] women; mean duration of illness, 7.0 years) were recruited from a research and clinic registry. Five patients withdrew from the trial. All participants were scheduled to receive fludrocortisone acetate (0.1-0.2 mg) or a placebo for 6 weeks in each treatment. Self-administered questionnaires were completed at the beginning and end of each treatment arm that asked patients to rate the severity of their symptoms on a visual analogue scale. The Medical Outcomes Study 36-Item Short-Form Health Survey, a reaction time test, and a treadmill exercise test were used to assess functional status. Blood pressure, heart rate, and plasma norepinephrine levels were obtained at baseline. Blood pressure and heart rate were recorded at the end of the exercise test and monitored at all subsequent visits. At baseline, the study participants reported symptom severity greater than 5 for most symptoms, and all had evidence of marked functional impairments. No improvement was observed in the severity of any symptom or in any test of function for the 20 participants who completed both arms of the trial. Blood pressure and heart rate readings were unaffected by treatment, and plasma norepinephrine levels did not differ from those of a healthy control group. The incidence of adverse experiences was similar in the fludrocortisone and placebo arms of the trial. Low-dose fludrocortisone does not provide sufficient benefit to be evident in a preliminary blinded trial of unselected patients with chronic fatigue syndrome.

A double-blind pilot study of the effect of Prokarin on fatigue in multiple sclerosis.

PubMed

Gillson, G; Richard, T L; Smith, R B; Wright, J V

2002-02-01

In this 12-week study with 29 subjects, the effect of Prokarin (n=22), a proprietary blend of histamine and caffeine, was compared to placebo group (n=7) for the following outcomes: 1) fatigue as measured by the Modified Fatigue Impact Scale (MFIS); 2) lower limb function as measured by timed walk test; 3) upper limb function as measured by the pegboard test; 4) cognitive function as measured by the Paced Auditory Serial Additions Test (PASAT); 5) serum caffeine level; 6) change in brain chemistry as measured by quantitative magnetic resonance spectroscopy assay of N-acetyl aspartate (NAA); and 7) safety as measured by routine blood chemistry, TSH and urinalysis. Data were acquired at baseline, 4, 8 and 12 weeks. The Prokarin group MFIS mean was significantly different rom the mean of the placebo group at 12 weeks (df=24, t=2.08, P=<0.02), with respective means of 37.40, SD=15.18, for the Prokarin group and 53.2, SD=11.39 for the controls. For the secondary endpoints (PASAT, 25 foot timed walk, peg test, and magnetic resonance spectroscopy [MRS]), there were no significant differences between the Prokarin-treated group and the placebo group. However, there were significant improvements within the Prokarin group for each of these measures for the pre- versus posttreatment comparison at 12 weeks. Serum caffeine data indicated that caffeine exerted no independent effect on performance. No laboratory abnormalities were seen, and the treatment was well tolerated. There was a modest-size statistical effect of Prokarin on fatigue in multiple sderosis (MS) compared with the placebo group. A larger trial is warranted, based on this pilot study.

Relationship between social support and fatigue in geriatric patients receiving outpatient chemotherapy.

PubMed

Karakoç, Tuğba; Yurtsever, Sabire

2010-02-01

This descriptive study was conducted with the purpose of determining the relationship between fatigue and social support in elderly individuals receiving chemotherapy. It was conducted in the oncology outpatient chemotherapy units of two university hospitals and one research hospital. A total of 71 patients who were 60 years old and older and receiving outpatient chemotherapy were included. Data were collected using a "Personal Information Form," "Social Support Scale in Cancer Patients," and "Visual Analogue Scale for Fatigue." Fatigue was the most common symptom (93%) in elderly patients receiving chemotherapy. The elderly individuals' perceived level of social support was found to be "good", the main form of support they received from those around them was "security" and the area most lacking was felt to be "information." As the individuals' level of social support increased, the severity of the fatigue they experienced decreased. The data demonstrate that social support was imperative in coping with fatigue. Copyright 2009 Elsevier Ltd. All rights reserved.

Research on the Fatigue Flexural Performance of RC Beams Attacked by Salt Spray

NASA Astrophysics Data System (ADS)

Mao, Jiang-hong; Xu, Fang-yuan; Jin, Wei-liang; Zhang, Jun; Wu, Xi-xi; Chen, Cai-sheng

2018-04-01

The fatigue flexural performance of RC beams attacked by salt spray was studied. A testing method involving electro osmosis, electrical accelerated corrosion and salt spray was proposed. This corrosion process method effectively simulates real-world salt spray and fatigue loading exerted by RC components on sea bridges. Four RC beams that have different stress amplitudes were tested. It is found that deterioration by corrosion and fatigue loading reduces the fatigue life of the RC and decreases the ability of deformation. The fatigue life and deflection ability could be reduced by increasing the stress amplitude and the corrosion duration time. The test result demonstrates that this experimental method can couple corrosion deterioration and fatigue loading reasonably. This procedure may be applied to evaluate the fatigue life and concrete durability of RC components located in a natural salt spray environment.

Assessment of corrosion fatigue damage by acoustic emission and periodic proof tests

NASA Astrophysics Data System (ADS)

Mehdizadeh, P.

1976-03-01

The development of a better nondestructive inspection method for detecting corrosion fatigue damage based on acoustic emission (AE) and periodic proof testing (PPT) is studied for corrosion fatigue tests in salt water solution under tension-tension loading. It is shown that PPT combined with AE monitoring can be a sensitive method for assessing the progress of corrosion fatigue damage as the continuous AE monitoring method. The AE-PPT technique is shown to be dependent on the geometry and size of the crack relative to the test specimen. A qualitative method based on plateauing of acoustic emission counts during proof tests due to changes in the fracture mode is used to predict the remaining fatigue life up to 70% of the actual values. PPT is shown to have no adverse effect on fatigue performance in salt water.

Conducting High Cycle Fatigue Strength Step Tests on Gamma TiAl

NASA Technical Reports Server (NTRS)

Lerch, Brad; Draper, Sue; Pereira, J. Mike

2002-01-01

High cycle fatigue strength testing of gamma TiAl by the step test method is investigated. A design of experiments was implemented to determine if the coaxing effect occurred during testing. Since coaxing was not observed, step testing was deemed a suitable method to define the fatigue strength at 106 cycles.

Health status among long-term breast cancer survivors suffering from higher levels of fatigue: a cross-sectional study.

PubMed

Álvarez-Salvago, Francisco; Galiano-Castillo, Noelia; Arroyo-Morales, Manuel; Cruz-Fernández, Mayra; Lozano-Lozano, Mario; Cantarero-Villanueva, Irene

2018-05-05

The aims of this study were to evaluate the health status of long-term breast cancer survivors (LTBCS) suffering from higher levels of fatigue, to highlight their needs, and to establish the key points of intervention support programs. A cross-sectional observational study was conducted at the Sport and Health Joint University Institute (iMUDS) between September 2016 and July 2017 with 80 LTBCS that were classified into non-fatigued (≤ 3.9) or fatigued (≥ 4) according to the Piper Fatigue Scale (PFS) total score. The instruments used were the European Organization for Research and Treatment of Cancer Core 30 and its breast cancer (BC) module, the Visual Analog Scale (VAS), the Brief Pain Inventory (BPI), the Scale for Mood Assessment (EVEA), the International Fitness Scale (IFIS), and the Charlson Comorbidity Index. The analysis revealed that 41.2% of LTBCS were considered moderately fatigued and showed significantly higher levels for the categories of "nausea and vomiting" (P = .005), "pain," "dyspnea" and "insomnia" (P < .001), "appetite loss" (P = .002), "financial difficulties" (P = .010), "systemic therapy side effects" (P < .001), "breast symptoms" and "arm symptoms" (P = .002), and "upset by hair loss" (P = .016). In addition, LTBCS presented significantly higher levels of pain in the affected and non-affected arm, "sadness-depression." "anxiety," "anger/hostility" (All: P < .001), and lower general physical fitness (P < .001). The rest of the variables did not show significant differences. LTBCS suffering from higher levels of fatigue had lower QoL, higher level of pain, worse mood state, and lower physical fitness.

Pain, Fatigue, and Psychological Impact on Health-Related Quality of Life in Childhood-Onset Lupus.

PubMed

Jones, Jordan T; Cunningham, Natoshia; Kashikar-Zuck, SusmitA; Brunner, Hermine I

2016-01-01

To evaluate pain, fatigue, and psychological functioning of childhood-onset systemic lupus erythematosus (SLE) patients and examine how these factors impact health-related quality of life (HRQOL). At a tertiary rheumatology clinic, 60 childhood-onset SLE patients completed the following: a visual analog scale (VAS) of pain intensity (0-10), the Pediatric Quality of Life (PedsQL) multidimensional fatigue scale, Pain Coping Questionnaire, Pain Catastrophizing Scale (PCS), Children's Depression Inventory I (CDI-I), the Screen for Child Anxiety Related Emotional Disorders (SCARED) questionnaire, and the PedsQL generic core (GC) scale and rheumatology module (RM). Sociodemographics and multiple disease activity indicators were recorded. Fatigue was present in 65% of the patients. Clinically relevant pain (pain-VAS >3), anxiety (SCARED ≥25), and depressive symptoms (CDI-I >12) were observed in 40%, 37%, and 30% of the patients, respectively; 22% had high catastrophizing (PCS ≥26). On average, the PedsQL-GC and -RM scores for childhood-onset SLE were lower than in healthy norms. Reduced PedsQL-GC and -RM scores were highly correlated with greater levels of fatigue, anxiety, and depressive symptoms (Pearson's r > 0.65), but had weak correlation with disease activity (Pearson's r < 0.25). Regression analysis demonstrated HRQOL was most impacted by fatigue, pain, and anxiety when evaluating all factors concurrently (P < 0.001). Childhood-onset SLE is associated with decreased HRQOL, and psychological aspects of health contribute substantially to low HRQOL, whereas measures of childhood-onset SLE activity seem less relevant. Fatigue, pain, mood, and anxiety symptoms are present in a large subgroup of patients and need medical attention to achieve optimal health outcomes. © 2016, American College of Rheumatology.

Oxygen uptake during peak graded exercise and single-stage fatigue tests of wheelchair propulsion in manual wheelchair users and the able-bodied.

PubMed

Keyser, R E; Rodgers, M M; Gardner, E R; Russell, P J

1999-10-01

To determine if a single-stage, submaximal fatigue test on a wheelchair ergometer would result in higher than expected energy expenditure. An experimental survey design contrasting physiologic responses during peak graded exercise tests and fatigue tests. A rehabilitation science laboratory that included a prototypical wheelchair ergometer, open-circuit spirometry system, and heart rate monitor. Nine able-bodied non-wheelchair users (the NWC group: 6 men and 3 women, mean +/- SD age 30 +/- 7yrs) and 15 manual wheelchair users (the WC group: 12 men and 3 women, age 40 +/- 9yrs, time in wheelchair 16 +/- 9yrs). No subject had any disease, medication regimen, or upper body neurologic, orthopedic, or other condition that would limit wheelchair exercise. Peak oxygen uptake (VO2) for graded exercise testing and during fatigue testing, using a power output corresponding to 75% peak aerobic capacity on graded exercise test. In the WC group, VO2 at 6 minutes of fatigue testing was not significantly different from peak VO2. In the NWC group, VO2 was similar to the expected level throughout fatigue testing. Energy expenditure was higher than expected in the WC group but not in the NWC group. Fatigue testing may provide a useful evaluation of cardiorespiratory status in manual wheelchair users.

Effectiveness of a Scaled-Up Arthritis Self-Management Program in Oregon: Walk With Ease.

PubMed

Conte, Kathleen P; Odden, Michelle C; Linton, Natalie M; Harvey, S Marie

2016-12-01

To evaluate the effectiveness of Walk With Ease (WWE), an evidence-based arthritis self-management program that was scaled up in Oregon in 2012 to 2014. Guided by the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework, we collected participant surveys and attendance records and conducted observations. Preprogram and postprogram, participants self-reported pain and fatigue (scale: 0-10 points; high scores indicate more pain and fatigue) and estimated episodes of physical activity per week in the last month. Recruitment successfully reached the targeted population-sedentary adults with arthritis (n = 598). Participants reported significant reduction in pain (-0.47 points; P = .006) and fatigue (-0.58 points; P = .021) and increased physical activity (0.86 days/week; P < .001). WWE was adopted by workplaces and medical, community, faith, and retirement centers. Most WWE programs were delivered with high fidelity; average attendance was 47%. WWE is suitable for implementation by diverse organizations. Effect sizes for pain and fatigue were less than those in the original WWE studies, but this is to be expected for a large-scale implementation. Public Health Implications. WWE can be effectively translated to diverse, real-world contexts to help sedentary adults increase physical activity and reduce pain and fatigue.