Letteratura scientifica selezionata sul tema "Fatigue"

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Articoli di riviste sul tema "Fatigue"

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Duan, Zhihao, Jinliang Xu, Han Ru e Menghui Li. "Classification of Driving Fatigue in High-Altitude Areas". Sustainability 11, n. 3 (4 febbraio 2019): 817. http://dx.doi.org/10.3390/su11030817.

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Abstract (sommario):
Driving fatigue is one of the main causes of traffic accidents. Thus, to prevent traffic accidents and ensure traffic safety, the properties of driving fatigue at the wheel must be determined. The Qinghai–Tibet Plateau in China is known for its high elevation, causing hypoxia, and presence of severely cold areas; all these easily lead to fatigue during driving. This, in turn, seriously affects the traffic safety on the high-altitude highway. Therefore, the factors leading to driving fatigue and the influence of high-altitude on driving fatigue affecting the driver must be further studied. In this study, we classified and quantified driving fatigue according to the driving fatigue degree. We determined three levels of driving fatigues (i.e., mild, moderate, and severe fatigues) to present their influence on drivers. Our study shows that in this high-altitude area, drivers became fatigued within a significantly shorter time.
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Palotai, Miklos, Michele Cavallari, Brian C. Healy e Charles RG Guttmann. "A novel classification of fatigue in multiple sclerosis based on longitudinal assessments". Multiple Sclerosis Journal 26, n. 6 (23 gennaio 2020): 725–34. http://dx.doi.org/10.1177/1352458519898112.

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Background: Magnetic resonance imaging (MRI) studies of multiple sclerosis–related fatigue had limited reproducibility. Temporal fatigue fluctuations have not been considered. Objective: To investigate whether a novel group allocation that reflects temporal dynamics of fatigue improves our ability to detect fatigue-associated structural brain abnormalities. Methods: Patient stratification based on biennial fatigue assessments: sustained fatigue (SF, n = 29, fatigued at the latest ⩾2 assessments), one time-point fatigue (1F, n = 15, fatigued at the latest, but non-fatigued at the penultimate assessment), reversible fatigue (RF, n = 31, non-fatigued at the latest assessment, but reported fatigue previously), and never fatigued (NF, n = 54). Brain parenchymal fraction (BPF) and T2 lesion volume (T2LV) were compared between these groups and were derived using a conventional, single time-point fatigued versus non-fatigued stratification. Results: The SF versus NF stratification yielded improved power. SF ( p = 0.005) and RF ( p = 0.043) showed significantly higher T2LV than NF. T2LV showed no significant differences in SF versus 1F, SF versus RF, or 1F versus RF. Fatigued versus non-fatigued patients showed significantly higher T2LV ( p = 0.030). We found no significant differences in BPF between the groups. Conclusion: Taking into account temporal fatigue dynamics increases the statistical power with respect to T2LV and may improve characterization of brain pathological correlates of MS-related fatigue.
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Andreasen, AK, J. Jakobsen, T. Petersen e H. Andersen. "Fatigued patients with multiple sclerosis have impaired central muscle activation". Multiple Sclerosis Journal 15, n. 7 (22 maggio 2009): 818–27. http://dx.doi.org/10.1177/1352458509105383.

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Background The pathogenesis of fatigue in multiple sclerosis (MS) is poorly understood. Objective To elucidate the role of central motor activation we hypothesized that patients with primary fatigue have impaired central motor function and increased fatigability as compared to secondary fatigued and non-fatigued patients. Methods Sixty patients with relapsing remitting MS and an Expanded Disability Status Scale score ≤ 3.5 were recruited and grouped as fatigued (Fatigue Severity Scale (FSS) ≥ 5.0) or non-fatigued (FSS ≤ 4.0). Nineteen patients were primary fatigued, 20 secondary fatigued and 21 non-fatigued. Maximal voluntary contraction, central activation and peripheral activation were determined by percutaneous twitch interpolation of the right quadriceps muscle. Results Maximal voluntary contraction was similar between groups but did relate to scores of fatigue. Peripheral activation was similar in all groups. Central activation was impaired in both groups of fatigued patients compared to non-fatigued patients being 0.96(0.05) in primary fatigued and 0.96(0.04) in secondary fatigued versus 0.99(0.1) in non-fatigued patients. The impairment of central motor activation was related to degree of fatigue in all patients. During fatiguing exercise there was a similar loss of strength, without any time differences between the three groups. Conclusion We conclude that impaired central motor activation is involved in MS-fatigue.
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Cauch-Dudek, K., S. Abbey, D. E. Stewart e E. J. Heathcote. "Fatigue in primary biliary cirrhosis". Gut 43, n. 5 (1 novembre 1998): 705–10. http://dx.doi.org/10.1136/gut.43.5.705.

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Background—Fatigue is a frequent and debilitating symptom in patients with primary biliary cirrhosis (PBC).Aims—To study fatigue in relation to sleep, depression, and liver disease severity.Methods—Patients with PBC completed validated self report questionnaires measuring fatigue, sleep quality, depression, and functional capacity. Verbally reported fatigue and observer rated measure of depression and ursodeoxycholic acid (UDCA) use were recorded. Liver biochemistry and tests to rule out metabolic causes of fatigue were performed.Results—Mean age of the 88 patients enrolled was 57 years; 86% were female and mean duration of disease was 6.6 years. Median bilirubin was 13 μmol/l (mean 18.6). Verbally reported fatigue (for more than six months) was present in 60 patients (68%). The self rated Fatigue Severity Score (FSS) correlated well with verbally reported fatigue (p=0.0001). The FSS did not correlate with age, duration of disease, serum bilirubin, Mayo Risk Score, or UDCA use, but correlation was seen with sleep quality. Fatigued patients had more sleep problems and higher depression scores than non-fatigued patients. Self rated depression was present in 28% (17/60) of fatigued compared with 4% (1/28) of non-fatigued patients.Conclusions—Long term fatigue affected 68% of the patients with PBC but it was not related to the severity of their liver disease. Poor sleep quality and depression were commonly associated with fatigue.
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Malekzadeh, Arjan, Wietske Van de Geer-Peeters, Vincent De Groot, Charlotte Elisabeth Teunissen, Heleen Beckerman e TREFAMS-ACE Study Group. "Fatigue in Patients with Multiple Sclerosis: Is It Related to Pro- and Anti-Inflammatory Cytokines?" Disease Markers 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/758314.

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Objective. To investigate the pathophysiological role of pro- and anti-inflammatory cytokines in primary multiple sclerosis-related fatigue.Methods. Fatigued and non-fatigued patients with multiple sclerosis (MS) were recruited and their cytokine profiles compared. Patients with secondary fatigue were excluded. Fatigue was assessed with the self-reported Checklist Individual Strength (CIS20r), subscale fatigue. A CIS20r fatigue cut-off score of 35 was applied to differentiate between non-fatigued (CIS20r fatigue≤34) and fatigued (CIS20r fatigue≥35) patients with MS. Blood was collected to determine the serum concentrations of pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IL-8, IL-12p70, IL-17, TNFα, and IFN-γ) and anti-inflammatory cytokines (IL-4, IL-5, IL-10, and IL-13). We controlled for the confounding effect of age, gender, duration of MS, disease severity, type of MS, and use of immunomodulatory drugs.Results. Similar cytokine levels were observed between MS patients with(n=21)and without fatigue(n=14). Adjusted multiple regression analyses showed a single significant positive relationship, that of IL-6 with CIS20r fatigue score. The explained variance of the IL-6 model was 21.1%, once adjusted for the confounding effect of age.Conclusion. The pro-inflammatory cytokine interleukin-6 (IL-6) may play a role in the pathophysiology of primary fatigue in patients with MS.Trial Registrations.ISRCTN69520623,ISRCTN58583714, andISRCTN82353628.
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Martin, Tristan, Rosie Twomey, Mary E. Medysky, John Temesi, S. Nicole Culos-Reed e Guillaume Y. Millet. "The Relationship between Fatigue and Actigraphy-Derived Sleep and Rest–Activity Patterns in Cancer Survivors". Current Oncology 28, n. 2 (10 marzo 2021): 1170–82. http://dx.doi.org/10.3390/curroncol28020113.

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Cancer-related fatigue can continue long after curative cancer treatment. The aim of this study was to investigate sleep and rest–activity cycles in fatigued and non-fatigued cancer survivors. We hypothesized that sleep and rest–activity cycles would be more disturbed in people experiencing clinically-relevant fatigue, and that objective measures of sleep would be associated with the severity of fatigue in cancer survivors. Cancer survivors (n = 87) completed a 14-day wrist actigraphy measurement to estimate their sleep and rest–activity cycles. Fatigue was measured using the Functional Assessment of Chronic Illness Therapy Fatigue Scale (FACIT-F). Participants were dichotomised into two groups using a previously validated score (fatigued n = 51 and non-fatigued n = 36). The participant’s perception of sleep was measured using the Insomnia Severity Index (ISI). FACIT-F score was correlated with wake after sleep onset (r = −0.28; p = 0.010), sleep efficiency (r = 0.26; p = 0.016), sleep onset latency (r = −0.31; p = 0.044) and Insomnia Severity Index (ISI) score (r = −0.56; p < 0.001). The relative amplitude of the rest–activity cycles was lower in the fatigued vs. the non-fatigued group (p = 0.017; d = 0.58). After treatment for cancer, the severity of cancer-related fatigue is correlated with specific objective measures of sleep, and there is evidence of rest–activity cycle disruption in people experiencing clinically-relevant fatigue.
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Moll, I., J. M. N. Essers, R. G. J. Marcellis, R. H. J. Senden, Y. J. M. Janssen-Potten, R. J. Vermeulen e K. Meijer. "Lower limb muscle fatigue after uphill walking in children with unilateral spastic cerebral palsy". PLOS ONE 17, n. 12 (6 dicembre 2022): e0278657. http://dx.doi.org/10.1371/journal.pone.0278657.

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Fatigue during walking is a common complaint in cerebral palsy (CP). The primary purpose of this study is to investigate muscle fatigue from surface electromyography (sEMG) measurements after a treadmill-based fatigue protocol with increasing incline and speed in children with CP with drop foot. The secondary purpose is to investigate whether changes in sagittal kinematics of hip, knee and ankle occur after fatigue. Eighteen subjects with unilateral spastic CP performed the protocol while wearing their ankle-foot orthosis and scored their fatigue on the OMNI scale of perceived exertion. The median frequency (MF) and root mean square (RMS) were used as sEMG measures for fatigue and linear mixed effects model were applied. The MF was significantly decreased in fatigued condition, especially in the affected leg and in the tibialis anterior and peroneus longus muscle. The RMS did not change significantly in fatigued condition, while the OMNI fatigue score indicated patients felt really fatigued. No changes in sagittal kinematics of hip, knee and ankle were found using statistical non-parametric mapping. In conclusion, the current fatigue protocol seems promising in inducing fatigue in a population with CP with drop foot and it could be used to expand knowledge on muscle fatigue during walking in CP.
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Stanzl-Tschegg, Stefanie E. "OS11W0385 Gigacycle fatigue and fatigue crack growth". Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2003.2 (2003): _OS11W0385. http://dx.doi.org/10.1299/jsmeatem.2003.2._os11w0385.

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Road, J., R. Vahi, P. del Rio e A. Grassino. "In vivo contractile properties of fatigued diaphragm". Journal of Applied Physiology 63, n. 2 (1 agosto 1987): 471–78. http://dx.doi.org/10.1152/jappl.1987.63.2.471.

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The effects of fatigue on diaphragmatic contractility in vivo are unknown. In this study we used sonomicrometry to examine the velocity of shortening and lengthening and the amount of shortening in the fresh and fatigued canine hemidiaphragm (8 dogs) including the force generated. Fatigue was produced by epiphrenic stimulation of the left phrenic nerve; the right hemidiaphragm acted as the control. We found that 1) hemidiaphragmatic fatigue caused an increase in frequency with reduced tidal volume; 2) fatigue resulted in a near complete cessation of tidal shortening during spontaneous breathing; 3) there was an initial decrease in central activation (electromyogram) to the fatigued hemidiaphragm, an indication of central fatigue; 4) force-frequency curves showed a considerable and prolonged loss of the amount of shortening, velocity, and force generated by the fatigued hemidiaphragm during supramaximal stimulation, an indication of peripheral fatigue; and 5) during spontaneous breathing in the fatigued hemidiaphragm, tidal shortening remained reduced for up to 3 h, whereas in the right right hemidiaphragm tidal shortening and electromyographic activity did not change. We conclude that fatigue of a hemidiaphragm alters the spontaneous breathing pattern and produces profound modifications in its contractile properties without altering contralateral hemidiaphragmatic performance.
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Kumamoto, Tsuneo, Toshiaki Seko, Ryo Matsuda e Sayo Miura. "Repeated standing back extension exercise: Influence on muscle shear modulus change after lumbodorsal muscle fatigue". Work 68, n. 4 (27 aprile 2021): 1229–37. http://dx.doi.org/10.3233/wor-213452.

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BACKGROUND: In low back pain, multifidus muscle fibers reportedly exhibit increased stiffness. Low back pain was associated with lumbodorsal muscle fatigue. There is no report of using shear modulus to verify the mechanism of an immediate effect of exercise on low back pain. Here, temporary lumbodorsal muscle fatigue was created, simulating fatigue-related nonspecific low back pain. OBJECTIVE: To assess the effect of standing back extension exercise on fatigued lumbodorsal muscle based on the results of multifidus muscle elasticity measured using shear wave elastography. METHODS: Thirty-three healthy subjects were randomly divided into three groups. The subjects performed the Biering-Sorensen test as the fatigue-task of the lumbodorsal muscle before the standing back extension exercise. The fatigue-exercise group exercised five sets after completing the fatigue-task. The fatigue-non-exercise group remained standing for the same duration as the fatigue-exercise group without doing the exercise after the fatigue-task. The non-fatigue-exercise group exercised five sets of without performing the fatigue-task. As intra-group and inter-group factors, the shear modulus of the multifidus muscle was compared before and after the exercise. RESULTS: The shear modulus of the multifidus muscle after the standing back extension exercise was significantly lower in the fatigue-exercise group, and no significant decrease was observed in the fatigue-non-exercise and non-fatigue-exercise group. CONCLUSIONS: The standing back extension exercise improved the shear modulus of the fatigued multifidus muscle. Therefore, it was suggested that the change in the elasticity of fatigued muscle might lead to the prevention of low back pain caused by muscle fatigue.
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Tesi sul tema "Fatigue"

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Swalla, Dana Ray. "Fretting fatigue damage prediction using multiaxial fatigue criteria". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17033.

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Krinsky, Robin S. "Fatigue and Alarm Fatigue in Critical Care Nurses". Case Western Reserve University Doctor of Nursing Practice / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=casednp1428102757.

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Lester, Charles Gilbert IV. "Analysis of fatigue behavior, fatigue damage and fatigue fracture surfaces of two high strength steels". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42795.

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Abstract (sommario):
Building fuel efficient automobiles is increasingly important due to the rising cost of energy. One way to improve fuel efficiency is to reduce the overall automobile weight. Weight reductions using steel components are desirable because of easy integration into existing manufacturing systems. Designing components with Advanced High Strength Steels (AHSS) has allowed for material reductions, while maintaining strength requirements. Two Advanced High Strength steel microstructures investigated in this research utilize different strengthening mechanisms to obtain a desired tensile strength grade of 590MPa. One steel, HR590, utilizes precipitation strengthening to refine the grain size and harden the steel. The other steel, HR590DP, utilizes a dual phase microstructure consisting of hardened martensite constituents in a ferrite matrix. The steels are processed to have the same tensile strength grade, but exhibit different fatigue behavior. The central objective of this research is to characterize and compare the fatigue behavior of these two steels. The results show the dual phase steel work hardens at a low fatigue life. The precipitation strengthened microstructure shows hardening at low strain amplitudes, softening at intermediate strain amplitudes and little to no effect at high strain amplitudes. These different fatigue responses are characterized and quantified in this research. Additionally, observations showing the fracture surfaces and the bulk microstructure are analyzed.
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Russell, Alice Elizabeth. "Fatigue and inflammation : a psychoneuroimmunological approach o chronic fatigue". Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/fatigue-and-inflammation(f592a66f-ddd9-4a29-a375-2295953a86d6).html.

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Chronic Fatigue Syndrome (CFS) is characterised by severe fatigue, endured for at least six months, together with symptoms including impaired cognitive function, sleep disturbance, and musculoskeletal pain. The pathogenesis is still unknown, resulting in a lack of treatment options and the stigmatization of patients. Both psychological and biological factors have been implicated in the development of CFS. To date, evidence has come largely from cross-sectional studies, and there have been a paucity of longitudinal studies. The aim of this study was to explore interferon-alpha (IFN-α) induced persistent fatigue as a proxy model of CFS. IFN-α is an immunotherapy for chronic Hepatitis C Virus (HCV) infection. It induces a range of side effects including fatigue, which in some patients persists post-treatment. This model allows for the identification of risk factors and monitoring of biological and behavioural changes from the perspective of the trigger, to determine factors relevant to the persistence of fatigue after the original stimulus is no longer present. Fifty-five patients undergoing IFN-α treatment for chronic HCV were assessed at baseline, during treatment, and six-months post-treatment. Clinical, inflammatory and cortisol measures were obtained. Fifty-four CFS patients and 57 healthy volunteers completed the same measures at a one-off assessment, which were compared with post-treatment measures from HCV persistent and resolved fatigue patients. IFN-α induced persistent fatigue was associated with an exaggerated response to IFN-α, with increased fatigue, depressive symptoms, and perceived stress, a greater decline in health status, and higher inflammation. This higher symptomatology during treatment put these patients at a disadvantage for their subsequent recovery. Neither IFN-α induced persistent fatigue nor CFS was associated with continued peripheral inflammation, emphasising the importance of the response to the initial trigger. Future studies are needed to elucidate the mechanisms behind the exaggerated response, and the ‘conversion’ to chronic illness in the absence of peripheral immune activation.
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Hu, Haiyun. "Fatigue and corrosion fatigue crack growth resistance of RQT501 steel". Thesis, University of Sheffield, 1997. http://etheses.whiterose.ac.uk/5999/.

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This project is concerned with the fatigue response of roller quenched and tempered (RQT50I) steels. Three closely related aspects are considered: (i) the relationship between the microstructure and fatigue properties, (ii) the influence of the environment on fatigue properties, (iii) theoretical modelling of fatigue crack growth. The material used is an RQT501 grade steel. Two steels have been chosen: (A) without Mo and V additions, (B) with Mo and V additions. The second condition is chosen to evaluate the role of these elements, as hydrogen traps, on the resistance to corrosion fatigue crack growth. In order to evaluate these effects, tests have been carried out under freely corroding conditions and applied cathodic polarisation (-9 . SO mV/SCE). Metallographic examination has been carried out to evaluate grain size and inclusion distribution, size and morphology. To enable a comparison between short and long fatigue crack growth, smooth shallow hour-glass specimens have been used to study initiation and growth of short fatigue cracks, and compact tension specimens were used to monitor propagation of long fatigue cracks. The fatigue response (S - Nf curve) and fatigue crack growth rate behaviour has been studied in air (5 - 10 biz) and in 3.5%NaCI solution (0.2 Hz) or artificial seawater (0.2 Hz) with an applied stress ratio of 0. I and sinusoidal waveform. The generation and growth behaviour of cracks from smooth hour-glass specimens has been investigated through successive observation using the plastic replication method. Long fatigue crack lengths were measured using a Direct Current Potential Drop (DCPD) technique and monitored via a chart recorder. Based upon the results of these tests a fatigue crack growth model was developed based on non-equilibrium statistical theory incorporating a consideration of the influence of microstructure, e. g. grain boundaries and hydrogen embrittlement. A stochastic theory of corrosion has also been developed for the use with corrosion fatigue test data.
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Russell, Charlotte. "The relationship between sleep and fatigue in Chronic Fatigue Syndrome". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/the-relationship-between-sleep-and-fatigue-in-chronic-fatigue-syndrome(ea68da56-797b-40ae-ab27-a620da7aee6d).html.

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This thesis has been prepared in a paper based format and includes an empirical paper, a systematic review and critical reflection. As a whole, the thesis focuses on the importance of sleep in Chronic Fatigue Syndrome (CFS). The systematic review is prepared for submission to 'Sleep Medicine Reviews'. The empirical paper is prepared for submission to the 'Journal of Consulting and Clinical Psychology'. Paper 1 is a systematic review and narrative synthesis of the current evidence for the effectiveness of Cognitive Behavioural Therapy (CBT) and Graded Exercise Therapy (GET) on sleep in CFS. Eight studies were found and their methodological quality varied. To understand heterogeneity in findings, information regarding intervention delivery, including the presence of sleep management components, methodology and sleep outcome measures was extracted and synthesised. We conclude that GET can improve sleep, when delivered by experienced therapists in outpatient settings. The evidence for CBT on sleep is limited, moreover, at present we know little about the effectiveness of adding sleep management components to interventions. We suggest that sleep outcomes used previously have not been sufficiently comprehensive and sensitive to measure change in sleep difficulties experienced in CFS. Implications for further research are discussed. Paper 2 presents an empirical study examining the relationship between sleep and fatigue in CFS using a daily diary approach. Sleep was measured objectively using actigraphy, and subjectively, using sleep diaries, in order to test which parameters better predict next-day fatigue. We also examined whether negative mood could mediate these relationships and whether subjective sleep variables were predicted by pre-sleep arousal. Using multilevel modelling, we found that subjective sleep, and not objective sleep, predicted next-day fatigue and these relationships were partially mediated by negative mood on waking. Pre-sleep cognitive and somatic arousal predicted subjective sleep variables including sleep efficiency and quality. Based on these findings, we suggest that interventions targeting subjective sleep, such as CBT for insomnia, may be useful in improving experiences of fatigue in CFS. Paper 3 is a critical reflection on the systematic review and empirical research, and on the process as a whole. Strengths and weakness of Paper 1 and Paper 2 are discussed, in addition to consideration of their contribution to wider research, and clinical practice.
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Ndiaye, Mamadou. "Simulation de la fatigue par chocs, par la fatigue conventionnelle". Metz, 1994. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1994/Ndiaye.Mamadou.SMZ9423.pdf.

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Le but de cette thèse est d'étudier la simulation de la fatigue par chocs, par la fatigue conventionnelle, à partir des matériaux suivants: 30 NCD 16, Marval 18H, composite Al/SiC. Dans une première approche, nous avions examiné l'évolution de la vitesse de propagation des fissures en fonction uniquement du pic maximal de chaque chargement. Cette étude a permis de montrer que l'influence de la vitesse de déformation propre à ces deux modes de chargements, n'est pas significative. L'ensemble des pics du chargement de fatigue par chocs, a été considérée dans une seconde approche cela a nécessité l'utilisation des méthodes de comptage pour transformer ce chargement, en plusieurs cycles d'amplitude constante. Le calcul de la vitesse de fissuration à partir des résultats de cette décomposition, a été faite par le biais du cumul des progressions de la fissure et du chargement équivalent. L'application de ces deux concepts, révèle l'effet négligeable des petites oscillations du signal de fatigue par chocs sur cette vitesse. Par ailleurs, les essais d'amorçage font apparaître que les nombres de cycles d'amorçage correspondant respectivement, au chargement équivalent et au chargement programme, sont assez proches. Enfin, les résultats d'amorçage ont été dépouillés selon le nouveau critère base sur le facteur d'intensité de contraintes d'entaille une dispersion des résultats relativement faible par rapport à celle obtenue par le critère lié au facteur d'intensité de contraintes, a été observée de ce point de vue, la validité de ce nouveau critère se trouve justifiée
The aim of this thesis is to study the simulation of impact fatigue with the help of conventionnal fatigue, on the following materials : 30 NCD 16 steel, Marval 18 h steel, Al/SiC composite. In a first step, we have examined the evolution of crack growth rate with respect to the maximum peak value of each loading. This study has shown that the influence of the strain rate of both kinds of fatigue loadings, is no significant. All the loading peaks for impact fatigue has been considered in a second step. It has been necessary to make use of counting methods in order to transform this loading in a constant amplitude loading cycles. The computation of the crack growth rate from these results, has been made using cumulative growth length and equivalent loading methods. The application of both concepts, reveals that small oscillations in the amplitude of the impact fatigue signal has no effect on the crack growth rate. On another hand, initiation tests has shown that the numbers of cycles to initiation corresponding respectively to the equivalent loading and the programmed loading, are quite similar. Last, the results of initiation tests has been analysed using a new criterion based on the notch stress intensity factor. A quite reasonnable scattering of results with respect to that observed with an analysis using the crack stress intensity factor, has been noticed. From this point of view, the validity of this criterion has been emphasised
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Ndiaye, Mamadou Pluvinage Guy. "SIMULATION DE LA FATIGUE PAR CHOCS, PAR LA FATIGUE CONVENTIONNELLE /". [S.l.] : [s.n.], 1994. ftp://ftp.scd.univ-metz.fr/pub/Theses/1994/Ndiaye.Mamadou.SMZ9423.pdf.

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Kaemingk, Kristine Lynn. "Cardiovascular reflex function, fatigue and depression in chronic fatigue syndrome". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185968.

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Abstract (sommario):
Recently there has been increased interest in chronic fatigue syndrome (CFS), a syndrome of nonspecific symptoms and unknown etiology. The relationship between cardiovascular reflex function, fatigue, and depression in CFS was examined. Findings were as follows: First, there was no evidence of abnormal cardiovascular reflex function in the CFS group. Second, the CFS group had significantly higher systolic and diastolic blood pressure than the control group. Third, the CFS group scored higher on psychological measures of depression, fatigue, and confusion than the control group; the control group scored higher on a measure of vigor than the CFS group. Finally, the CFS group reported more CFS-related symptoms, but some members of the control group did endorse symptoms on a CFS symptom checklist. The possibility that increased peripheral resistance accounts for the elevated blood pressure in the CFS group, and the merits of exploring the role of interleukin-1 and other hormones or "hormone-like" substances in the etiology or maintenance of CFS symptomatology are discussed.
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Warneboldt, Iona. "Multiaxial fatigue design of elastomeric parts using Equivalent Fatigue Loads". Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0002.

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Abstract (sommario):
Trois étapes sont mises en oeuvre ici : la méthode de localisation, la fonction de dommage matériau et le processus de détermination des chargements équivalents en fatigue (CEF). De nombreux essais de fatigue ont été réalisés (415 au total) pour étudier le comportement en fatigue sous chargement multiaxial relaxant et non relaxant sur des éprouvettes de caoutchouc naturel. La durée de vie et les caractéristiques des fissures sont analysées pour finalement introduire un critère de fatigue approprié basé sur le plan critique et permettant de rendre compte de l'effet de déformation moyenne. Ce critère est généralisé à travers une méthode originale de recherche du plan critique. Pour estimer la réponse mécanique locale (méthode de localisation), une méthode de couplage des axes adaptée à la nature non linéaire des structures élastomères est proposée. Elle est basée sur la décomposition multiplicative des tenseurs du gradient de la déformation. Ces deux étapes sont ensuite mises en oeuvre dans le cadre du processus de détermination du CEF. Pour cela, une méthode d'optimisation globale est ajoutée pour déterminer les chargements simplifiés, induisant partout localement le même endommagement en fatigue dans la structure étudiée que le RLD. Le temps de calcul de cette optimisation est réduit en ne considérant qu'un sous-ensemble de points matériels, les plus endommagés, pour la détermination du CEF. Enfin, la méthode a été testée sur une éprouvette afin de souligner ses capacités et de valider l'approche
This thesis introduces an Equivalent Fatigue Load (EFL) approach for the multiaxial fatigue design of elastomeric parts. As direct Finite Element Analysis (FEA) calculations of automotive in-service loads (Road Load Data (RLD)) are too expensive, the objective is to derive simplified load blocks as a realistic input for numerical damage calculations. Three streps are applied for this method: the localization method, the material damage function and the EFL determination process. Various fatigue tests have been conducted (415 samples) to study the fatigue behavior of this complex type of relaxing and non-relaxing multiaxial loading on natural rubber specimens. Lifetime and crack features are analyzed to eventually introduce an appropriate critical planebased fatigue measure and to establish a novel mean strain effect model. This criterion is generalized throughout an original critical plane search method. To estimate the local mechanical response (localization method), this thesis identifies an axes-coupling method that is fitted for the nonlinear nature of elastomeric structures. It is based on the multiplicative decomposition of the deformation gradient tensors. These two steps are then implemented in the framework of the EFLdetermination process. For this, a global optimization method is added to determine the simplified load blocks, causing locally the same fatigue behavior in the given structure. The computational costs of this optimization are reduced by only considering a subset of the most damaged material points for EFLdetermination. Finally, the method has been challenged on a specimen to outline its capabilities and to validate the approach
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Libri sul tema "Fatigue"

1

Solomon, Neil. Fatigué d'être fatiguée. Montréal: Québecor, 1989.

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2

Gandevia, Simon C., Roger M. Enoka, Alan J. McComas, Douglas G. Stuart, Christine K. Thomas e Patricia A. Pierce, a cura di. Fatigue. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1016-5.

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3

Toyos, Isabel, Pierre-Yves Ledilicocq e Simon St John Bailey. Fatigue. Saint-Constant, PQ: Broquet, 2006.

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4

Krupp, Lauren B. Fatigue. Philadelphia, Pa: Butterworth-Heinermann, 2003.

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5

Serratrice, Georges, e Jean-Louis Vildé, a cura di. Syndrome de Fatigue Chronique / Chronic Fatigue Syndrome. Paris: Springer Paris, 1991. http://dx.doi.org/10.1007/978-2-8178-0868-0.

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6

Brighthope, Ian. Fighting fatigue and the Chronic Fatigue Syndrome. Sydney: Allen & Unwin, 1991.

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7

François, Caroli, Serratrice Georges e Vildé Jean-Louis, a cura di. Syndrome de fatigue chronique =: Chronic fatigue syndrome. Paris ; New York: Springer-Verlag, 1991.

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8

Socie, Darrell. Multiaxial Fatigue. Warrendale, PA: SAE International, 1999. http://dx.doi.org/10.4271/r-234.

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9

Sosnovskiy, Leonid A. Tribo-Fatigue. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/978-3-540-27027-0.

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10

Miller, KJ, e MW Brown, a cura di. Multiaxial Fatigue. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 1985. http://dx.doi.org/10.1520/stp853-eb.

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Capitoli di libri sul tema "Fatigue"

1

John, Vernon. "Fatigue and Fatigue Testing". In Testing of Materials, 69–77. London: Macmillan Education UK, 1992. http://dx.doi.org/10.1007/978-1-349-21969-8_6.

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Miannay, Dominique P. "Fatigue and Creep Fatigue". In Mechanical Engineering Series, 401–39. New York, NY: Springer New York, 2001. http://dx.doi.org/10.1007/978-1-4613-0155-4_8.

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3

Theisler, Charles. "Fatigue/Chronic Fatigue Syndrome". In Adjuvant Medical Care, 127–28. New York: CRC Press, 2022. http://dx.doi.org/10.1201/b22898-137.

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4

Lerdal, Anners. "Fatigue". In Encyclopedia of Quality of Life and Well-Being Research, 2216–18. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-0753-5_1016.

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5

Mücke, Martin, e Dmitrij Kravchenko. "Fatigue". In Textbook of Palliative Care, 191–205. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-77740-5_12.

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6

Grover-Manthey, Benjamin. "Fatigue". In Encyclopedia of Clinical Neuropsychology, 1407–8. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-57111-9_241.

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7

Bhaduri, Amit. "Fatigue". In Mechanical Properties and Working of Metals and Alloys, 317–71. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7209-3_8.

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Jacocks, Connie. "Fatigue". In Practical Psychology in Medical Rehabilitation, 303–10. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-34034-0_33.

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Sourati, Ainaz, Ahmad Ameri e Mona Malekzadeh. "Fatigue". In Acute Side Effects of Radiation Therapy, 173–89. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-55950-6_18.

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10

François, Dominique, André Pineau e André Zaoui. "Fatigue". In Mechanical Behaviour of Materials, 307–62. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-4930-6_6.

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Atti di convegni sul tema "Fatigue"

1

Landgraf, Ronald W. "Fatigue Technology in Vehicle Development". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4081.

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2

Ellis, Fred V. "Fatigue and Corrosion Fatigue Failures". In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71051.

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Abstract (sommario):
A metallurgical failure analysis was performed for a hanger rod and a waterwall tube sample. The hanger is a rigid type and supports a long vertical run of piping. The fracture is in one of the threaded ends and the fracture surface consists of three regions. The outermost portion adjacent to the thread root has ratchet marks that are an indication of fatigue crack initiation. The center portion has concentric, oval shaped beachmarks. The oval shape is consistent with an applied loading due to two bending moments. The inner portion is the final fracture and is approximately 1/4 of the thread root area indicating relatively low remote stresses. The failure mechanism is fatigue based on the beachmarks on the fracture surface and the transgranular cracking. The lower slope waterwall tube failure had a window opening fracture appearance. The axial fractures forming the window are located at the edge of the membrane welds on the cold or backside. There are shallow toe cracks at the membrane weld on the tube outside surface. The fracture surface had multiple, thumbnail-shaped fatigue cracks connected to the inside surface. These fatigue cracks are due to the corrosion fatigue mechanism based on two factors: (1) the stress responsible for their growth is related to the unit thermal cycling and the welded panel geometry near the corner of the boiler, and (2) they are oxidized indicating a corrosion contribution.
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De Jesus Falcão, César Augusto, Waldek Wladimir Bose Filho e Dirceu Spinelli. "Thermomechanical Fatigue: Testing Methods and Application". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4068.

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Miranda, A. C. O., L. F. Martha, M. A. Meggiolaro, J. T. P. Castro e T. N. Bittencourt. "Curved Fatigue Cracks Under Complex Loading". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4069.

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Bignonnet, André, e Jean Jacques Thomas. "Fatigue assessment and reliability in automotive design". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4061.

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6

Ramos, M. S., M. V. Pereira, S. H. Motta e M. A. Carneiro. "Fatigue Life Extension in a Structural Steel". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4078.

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Da Silva, Eraldo Jannone, Eduardo Carlos Bianchi, Paulo Robero De Aguiar e Rodrigo Eduardo Catai. "The Improvement in Grinding of Inlet Engine Valves by the Adoption of the Most Effective Cuting Fluid Type". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-3209.

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8

Cruz, Ivan, e Nestor Zouain. "A Shakedown Fatigue Model Tested in Torsion-Bending". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4059.

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9

Mcevily, Arthur J., e Sotomi Ishihara. "On the Retardation in Fatigue Crack Growth Rate due to an Overload; a Review". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4050.

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Zhou, Yang, Xinian Lu, Guangjiang Yuan, Daming Cheng e Xueren Wu. "Dynamic Observation of Fracture Process in Laminated Ceramic Matrix Composites". In SAE Brasil International Conference on Fatigue. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-4051.

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Rapporti di organizzazioni sul tema "Fatigue"

1

Carlin, Bruce Ian, e Florian Ederer. Search Fatigue. Cambridge, MA: National Bureau of Economic Research, marzo 2012. http://dx.doi.org/10.3386/w17895.

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2

Lesuer, D. ,. LLNL. Isothermal fatigue. Office of Scientific and Technical Information (OSTI), giugno 1998. http://dx.doi.org/10.2172/16735.

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3

Harrison, Richard, Scott Chaiken, Donald Harville, Joseph Fischer, Dion Fisher e Jeff Whitmore. The Identification of Fatigue Resistant and Fatigue Susceptible Individuals. Fort Belvoir, VA: Defense Technical Information Center, maggio 2008. http://dx.doi.org/10.21236/ada489879.

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Ferguson, Dr Kathleen, Dr Felicity Howard, Dr Chris Idzikowski, Dr Barry Nicholls, Dr Mike Peters e Dr Felicity Plaat. Fatigue and anaesthetists. The Association of Anaesthetists of Great Britain and Ireland, ottobre 2014. http://dx.doi.org/10.21466/g.faa.2014.

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5

Ritchie, R. O., W. W. Gerberich e J. H. Underwood. Fracture and Fatigue. Fort Belvoir, VA: Defense Technical Information Center, aprile 1988. http://dx.doi.org/10.21236/ada197310.

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6

Marshak, Ronni. Daily Deal Fatigue. Boston, MA: Patricia Seybold Group, dicembre 2012. http://dx.doi.org/10.1571/vs12-06-12cc.

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7

Brooks, C. L., S. A. Prost-Domasky, K. T. Honeycutt, T. B. Mills e N. Young. Fretting Fatigue Model. Fort Belvoir, VA: Defense Technical Information Center, febbraio 2003. http://dx.doi.org/10.21236/ada412736.

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8

Wei, Robert P. Fatigue 2002 Conference. Fort Belvoir, VA: Defense Technical Information Center, dicembre 2002. http://dx.doi.org/10.21236/ada413359.

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9

Lemaitre, Jean, e Rene Billardon. Micromechanics of Fatigue. Fort Belvoir, VA: Defense Technical Information Center, maggio 1990. http://dx.doi.org/10.21236/ada229403.

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10

Stern, John A., e Timothy B. Brown. Detection of Human Fatigue. Fort Belvoir, VA: Defense Technical Information Center, agosto 2005. http://dx.doi.org/10.21236/ada437371.

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