Medicine finally has discovered fatigue. Recent articles about various diseases conclude that fatigue has been underrecognized, underdiagnosed, and undertreated. Scholars in the social sciences and ...humanities have also ignored the phenomenon. As a result, we know little about what it means to live with this condition, especially given its diverse symptoms and causes. Emily K. Abel offers the first history of fatigue, one that is scrupulously researched but also informed by her own experiences as a cancer survivor. Abel reveals how the limits of medicine and the American cultural emphasis on productivity intersect to stigmatize those with fatigue. Without an agreed-upon approach to confirm the problem through medical diagnosis, it is difficult to convince others that it is real. When fatigue limits our ability to work, our society sees us as burdens or worse. With her engaging and informative style, Abel gives us a synthetic history of fatigue and elucidates how it has been ignored or misunderstood, not only by medical professionals but also by American society as a whole.
Abstract Objective The Chalder Fatigue Scale (CFQ) is a widely used instrument to assess fatigue in both clinical and nonclinical settings. Psychometric properties of the scale and discriminative ...abilities were examined. Methods A total of 361 patients with CFS and 1615 individuals in the community were assessed with the CFQ. Principal component analysis (PCA) was used to explore the structure of the scale. Receiver-operating characteristic curve (ROC) was used to investigate the discriminative properties. Results Two components, physical and mental fatigue, were identified in the CFS patient group and in the general population samples. Area under the curve for ROC was .91. The fatigue scale effectively discriminates, at high scores, between CFS patients and the general population. Conclusion Physical and mental fatigue are clearly separable components of fatigue. The CFQ can discriminate reliably between clinical and nonclinical conditions.
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•The corrosive environment accelerates failure at stresses two thirds of in-air fatigue limit.•A conditional probability density function is used for the statistical assessment of fatigue life.•The ...environmentally induced cracks tend to initiate from localized corrosion pitting.•The theoretical fatigue limit is obtained based on a low probability event.
The effects of environment (in air and 3.5 wt% NaCl solution) and artificially-induced surface scratches are investigated on the fatigue properties of railway EA4T (also called 25CrMo4) alloy steel. This steel is found to be markedly sensitive to the chloride-containing environment, with cracking at stresses two thirds of the in-air fatigue limit (+/−326 MPa) under rotating bending (Wöhler) tests. The scratched specimens show even shorter lifetime at stresses below 300 MPa and no fatigue limit is found down to 100 MPa. The fracture surfaces are characterized by the initiation of cracks from multiple sources and intergranular cracking. The fatigue failure of smooth specimens tends to initiate from localized corrosion pitting, while the corrosive environment facilitates crack initiation without pitting for scratched specimens. The fatigue crack growth rate in NaCl solution is slightly higher than that in air. Within the framework of defect-tolerant design, El-Haddad modified Kitagawa-Takahashi (KT) diagrams are constructed to explore the variation in fatigue strength and the defect assessment for both conditions. The modified KT model, which takes the short crack behavior into account, is in better agreement with the experimental results than the original KT diagrams.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Introduction
Fatigue from sleep loss and circadian misalignment causes automobile driving performance impairment. Metrics based on steering wheel angle, which is straightforward to measure, ...could be used to quantify this impairment. As the tail of the distribution of steering wheel angles (absolute magnitude of deviation from center) increases with fatigue, we investigated whether driving performance impairment could be quantified based on the prevalence of steering wheel excursions beyond a given angle threshold. We used data from two published laboratory studies of simulated shift work, in which fatigue remained low during day shifts but increased across time awake during night shifts.
Methods
N=37 healthy adults (ages 26.8±5.2y; 25 men) were assigned to a simulated night shift schedule (awake 20:00-10:00) or day shift schedule (awake 08:00-22:00; study 1 only). After an adaptation period, participants underwent two 5-day shift cycles with an intervening rest period. Driving performance was measured on a high-fidelity simulator during adaptation (data not used) and four times at 3h intervals during each shift day. Every drive involved 30min driving at 55mph, including ten 0.5mi uneventful straightaways being considered here. Steering wheel angle was measured at 72Hz (study 1) or 60Hz (study 2). A total of 1,471 drives (31,394,498 angle measurements) were available for analysis.
Results
We investigated angle thresholds across 0.01-0.25rad in 0.01rad intervals and counted the corresponding number of threshold excursions in each drive for each participant. For study 1, we applied mixed-effects ANOVA with fixed effects for condition and time awake, and their interaction, and determined the local effect size for interaction. A 0.03rad (1.7°) threshold yielded the greatest effect size, f²=0.031 (small). For this threshold, we repeated the analysis using the data from both studies, controlling for study. The interaction was significant (F3,1428=13.23, p<0.001), showing low driving impairment across time awake during day shifts but increasing impairment across time awake during night shifts.
Conclusion
The prevalence of steering wheel excursions beyond a 1.7° angle threshold yielded sensitivity to fatigue-related driving performance impairment during simulated night shifts. Further research will extend our results to driving through curves and with greater fatigue levels.
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Coronavirus 2 is responsible for Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2), and the main sequela is persistent fatigue. Post-viral fatigue is common and affects patients with mild, ...asymptomatic coronavirus disease-2019 (COVID-19). However, the exact mechanisms involved in developing post-COVID-19 fatigue remain unclear. Furthermore, physical and cognitive impairments in these individuals have been widely described. Therefore, this review aims to summarize and propose tools from a multifaceted perspective to assess COVID-19 infection. Herein, we point out the instruments that can be used to assess fatigue in long-term COVID-19: fatigue in a subjective manner or fatigability in an objective manner. For physical and mental fatigue, structured questionnaires were used to assess perceived symptoms, and physical and cognitive performance assessment tests were used to measure fatigability using reduced performance.
•Fatigue is the main sequela of long COVID-19 and needs follow-up.•There are physical and mental manifestations of fatigue in long COVID-19.•This review presents the most used instruments in assessing fatigue in long COVID-19.•Muscle strength, walking, and functional tests assess physical fatigue in long COVID-19.•Executive function psychological tests assess mental fatigue in long COVID-19.
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Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Institute of Medicine; Board on the Health of Select Populations; Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome
02/2015
eBook
Open access
Myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) are serious, debilitating conditions that affect millions of people in the United States and around the world. ME/CFS can cause ...significant impairment and disability. Despite substantial efforts by researchers to better understand ME/CFS, there is no known cause or effective treatment. Diagnosing the disease remains a challenge, and patients often struggle with their illness for years before an identification is made. Some health care providers have been skeptical about the serious physiological - rather than psychological - nature of the illness. Once diagnosed, patients often complain of receiving hostility from their health care provider as well as being subjected to treatment strategies that exacerbate their symptoms.
Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome proposes new diagnostic clinical criteria for ME/CFS and a new term for the illness - systemic exertion intolerance disease(SEID). According to this report, the term myalgic encephalomyelitis does not accurately describe this illness, and the term chronic fatigue syndrome can result in trivialization and stigmatization for patients afflicted with this illness. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome stresses that SEID is a medical - not a psychiatric or psychological - illness. This report lists the major symptoms of SEID and recommends a diagnostic process.One of the report's most important conclusions is that a thorough history, physical examination, and targeted work-up are necessary and often sufficient for diagnosis. The new criteria will allow a large percentage of undiagnosed patients to receive an accurate diagnosis and appropriate care.
Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome will be a valuable resource to promote the prompt diagnosis of patients with this complex, multisystem, and often devastating disorder; enhance public understanding; and provide a firm foundation for future improvements in diagnosis and treatment.
The Handbook of Operator Fatigue provides a comprehensive account of this subject to serve as the definitive reference work for researchers, students and practitioners alike. The volume features 30 ...chapters written by experts to address each important facet of fatigue, including: the scale of the fatigue problem, the nature of fatigue, how to assess fatigue, the impact of fatigue on health, fatigue in the workplace, the neurological basis of fatigue, sleep disorders, and the design of countermeasures to fatigue.
•The separate S-N curves are firstly detected in additively manufactured metals.•Fatigue cracks originate from gas pores, lack of fusions, and columnar grains.•ΔK at the border of rough area ...corresponds to propagation threshold for long cracks.•Fatigue sensitivity of maximal micro-crack type, size, and location increase successively.
Ultrasonic fatigue tests were performed to investigate high and very high cycle fatigue behaviors of a laser additively manufactured Inconel 718 (IN718) alloy in the as-deposited condition. The results indicate that the competition failure behavior between the surface and interior crack initiation results in the separate S-N curve. Both manufacturing defects (e.g., gas pore, lack of fusion) and columnar grains (matrix) observed in the microstructure could act as the original fatigue micro-cracks due to the effective restriction on manufacturing defects. The fatigue sensitivity levels increase successively in terms of the type, size, and location of the maximal micro-crack.
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•Uniaxial strain- and force-controlled fatigue tests are conducted on LB-PBF 304L SS.•Specimens in machined/polished and as-built surface conditions are characterized.•Locational and ...directional effects on surface roughness of specimens are minimal.•The effect of surface roughness is more significant on stress-life behavior.•Fatigue life of as-built specimens can be estimated using their surface topography.
The fatigue strength of additively manufactured metallic parts in their as-built surface condition is mainly dominated by the surface roughness. Post-processing is often inevitable to reduce surface roughness effects even though post-processing diminishes the main advantage of additive manufacturing, which is net-shaped direct-to-service production. This study investigates the underlying mechanisms responsible for fatigue failure of additively manufactured 304L stainless steel parts in as-built and machined/polished surface conditions. Both strain- and force-controlled, fully reversed fatigue tests were conducted to gain a comprehensive understanding of surface roughness effects on fatigue behavior. The sensitivity to surface roughness is shown to be dependent on the control mode, with stress-based fatigue tests showing greater sensitivity than strain-based fatigue tests. Moreover, the fatigue life estimation for as-built specimens was performed based on surface roughness parameters as well as the fatigue properties of the specimens in machined/polished surface condition of the material without using any fatigue data of specimens in as-built surface condition. Accordingly, the effect of surface roughness on the fatigue behavior could be estimated reasonably well in both strain-life and stress-life approaches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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