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Description
Fibromyalgia (FM) is a chronic pain condition characterized by debilitating fatigue. This study examined the dynamic relation between interpersonal enjoyment and fatigue in 102 partnered and 74 unpartnered women with FM. Participants provided three daily ratings for 21 days. They rated their fatigue in late morning and at the end of the day. Both partnered and unpartnered participants reported their interpersonal enjoyment in the combined familial, friendship, and work domains (COMBINED domain) in the afternoon. Additionally, partnered participants reported their interpersonal enjoyment in the spousal domain. The study was guided by three hypotheses at the within-person level, based on daily diaries: (1) elevated late morning fatigue would predict diminished afternoon interpersonal enjoyment; (2) diminished interpersonal enjoyment would predict elevated end-of-day fatigue; (3) interpersonal enjoyment would mediate the late morning to end-of-day fatigue relationship. In cross-level models, the study explored whether individual differences (between-person) in late morning fatigue and afternoon interpersonal enjoyment would moderate within-person relations from late morning fatigue to afternoon interpersonal enjoyment, and from afternoon interpersonal enjoyment to end-of-day fatigue. Furthermore, it explored whether the hypothesized relationships at the within-person level would also emerge at the between-person level (between-person mediation models). Multilevel structural equation modeling and multilevel modeling were employed for model testing, separately for partnered and unpartnered participants. Within-person mediation models supported that on high fatigue mornings, afternoon interpersonal enjoyment was dampened in the spousal and combined domains in partnered and unpartnered samples. Moreover, low afternoon interpersonal enjoyment in both the spousal and combined domains predicted elevated end-of-day fatigue. Afternoon interpersonal enjoyment mediated the relationship of late morning to end-of-day fatigue in the combined domain but in not the spousal domain. Cross-level moderation analyses showed that individual differences in afternoon spousal enjoyment moderated the day-to-day relation between afternoon spousal enjoyment and end-of-day fatigue. Finally, the mediational chain was not observed at the between-person level. These findings suggest that preserving interpersonal enjoyment in non-spousal relations limits within-day increases in FM fatigue. They highlight the importance of examining domain-specificity in interpersonal enjoyment when studying fatigue, and suggest that targeting enjoyment in social relations may improve the efficacy of existing treatments.
ContributorsYeung, Wan (Author) / Aiken, Leona S. (Thesis advisor) / Davis, Mary C. (Thesis advisor) / Mackinnon, David P (Committee member) / Zautra, Alex J (Committee member) / Arizona State University (Publisher)
Created2013
Description
Eccentric muscle action (ECC) occurs when the force exerted by a working muscle is less than that of an outside resistance. This is characterized by muscle lengthening, despite actin-myosin crossbridge formation. Research has indicated that muscles acting eccentrically are capable of producing more force when compared to muscles acting concentrically. Further, research has shown ECC muscle actions may have different fatigue patterns that CON actions. The purpose of this study was to determine if a) ECC bench press yields greater strength than concentric (CON) as measured by one-repetition maximum (1RM), b) there is a difference between the number of repetitions that can be completed concentrically and eccentrically under the same relative intensities of 1RM (90%, 80%, 70%, 60%), c) a prediction model may be able to predict ECC 1RM from CON 1RM or CON repetitions to fatigue. For this study, 30 healthy males (age = 24.63 + 5.6 years) were tested for 1RM in CON and ECC bench press, as well as the number of repetitions they were able to complete at various intensities of mode-specific 1RM. A mechanical hoist was affixed to a gantry crane and placed over a standard weightlifting bench. The hoist was connected to 45lb plates that were loaded on a standard barbell, which allowed for mechanical raising and lowering of the barbell. For CON repetitions, the weight was mechanically lowered to the chest and the participant pressed it up. For ECC repetitions, the weight was mechanically raised and the participant lowered it. Paired t-tests showed that ECC 1RM was significantly (p < 0.05) greater than CON 1RM (ECC =255.17 + 68.37lbs, CON = 205.83 + 58.43lbs). There was a significant difference (p < 0.05) between the number of repetitions completed at 90% 1RM (CON = 4.57 + 2.21 repetitions, ECC = 7.67 + 3.24 repetitions). There were no differences in repetitions completed at any other intensity 1RM. CON 1RM and the number of repetitions completed with two different absolute loads (130-150lbs and 155-175lbs) concentrically and eccentrically were valid predictors of ECC 1RM. These data indicate that ECC actions yield increased force capabilities than CON actions, there is no difference in the rate of the fatigue, and ECC 1RM may be predicted from various CON tests.
ContributorsKelly, Stephen B., Jr (Author) / Hooker, Steven (Thesis advisor) / Brown, Lee (Committee member) / Buman, Matthew (Committee member) / Gaesser, Glenn (Committee member) / Swan, Pamela (Committee member) / Arizona State University (Publisher)
Created2013
Description
The use of electromyography (EMG) signals to characterize muscle fatigue has been widely accepted. Initial work on characterizing muscle fatigue during isometric contractions demonstrated that its frequency decreases while its amplitude increases with the onset of fatigue. More recent work concentrated on developing techniques to characterize dynamic contractions for use in clinical and training applications. Studies demonstrated that as fatigue progresses, the EMG signal undergoes a shift in frequency, and different physiological mechanisms on the possible cause of the shift were considered. Time-frequency processing, using the Wigner distribution or spectrogram, is one of the techniques used to estimate the instantaneous mean frequency and instantaneous median frequency of the EMG signal using a variety of techniques. However, these time-frequency methods suffer either from cross-term interference when processing signals with multiple components or time-frequency resolution due to the use of windowing. This study proposes the use of the matching pursuit decomposition (MPD) with a Gaussian dictionary to process EMG signals produced during both isometric and dynamic contractions. In particular, the MPD obtains unique time-frequency features that represent the EMG signal time-frequency dependence without suffering from cross-terms or loss in time-frequency resolution. As the MPD does not depend on an analysis window like the spectrogram, it is more robust in applying the timefrequency features to identify the spectral time-variation of the EGM signal.
ContributorsAustin, Hiroko (Author) / Papandreou-Suppappola, Antonia (Thesis advisor) / Kovvali, Narayan (Committee member) / Muthuswamy, Jitendran (Committee member) / Arizona State University (Publisher)
Created2012
Description
Aluminum alloys and their composites are attractive materials for applications requiring high strength-to-weight ratios and reasonable cost. Many of these applications, such as those in the aerospace industry, undergo fatigue loading. An understanding of the microstructural damage that occurs in these materials is critical in assessing their fatigue resistance. Two distinct experimental studies were performed to further the understanding of fatigue damage mechanisms in aluminum alloys and their composites, specifically fracture and plasticity. Fatigue resistance of metal matrix composites (MMCs) depends on many aspects of composite microstructure. Fatigue crack growth behavior is particularly dependent on the reinforcement characteristics and matrix microstructure. The goal of this work was to obtain a fundamental understanding of fatigue crack growth behavior in SiC particle-reinforced 2080 Al alloy composites. In situ X-ray synchrotron tomography was performed on two samples at low (R=0.1) and at high (R=0.6) R-ratios. The resulting reconstructed images were used to obtain three-dimensional (3D) rendering of the particles and fatigue crack. Behaviors of the particles and crack, as well as their interaction, were analyzed and quantified. Four-dimensional (4D) visual representations were constructed to aid in the overall understanding of damage evolution. During fatigue crack growth in ductile materials, a plastic zone is created in the region surrounding the crack tip. Knowledge of the plastic zone is important for the understanding of fatigue crack formation as well as subsequent growth behavior. The goal of this work was to quantify the 3D size and shape of the plastic zone in 7075 Al alloys. X-ray synchrotron tomography and Laue microdiffraction were used to non-destructively characterize the volume surrounding a fatigue crack tip. The precise 3D crack profile was segmented from the reconstructed tomography data. Depth-resolved Laue patterns were obtained using differential-aperture X-ray structural microscopy (DAXM), from which peak-broadening characteristics were quantified. Plasticity, as determined by the broadening of diffracted peaks, was mapped in 3D. Two-dimensional (2D) maps of plasticity were directly compared to the corresponding tomography slices. A 3D representation of the plastic zone surrounding the fatigue crack was generated by superimposing the mapped plasticity on the 3D crack profile.
ContributorsHruby, Peter (Author) / Chawla, Nikhilesh (Thesis advisor) / Solanki, Kiran (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2014
Description
One of the main requirements of designing perpetual pavements is to determine the endurance limit of Hot Mix Asphalt (HMA). The purpose of this study was to validate the endurance limit for HMA using laboratory beam fatigue tests. A mathematical procedure was developed to determine the endurance limit of HMA due to healing that occurs during the rest periods between loading cycles. Relating healing to endurance limit makes this procedure unique compared to previous research projects that investigated these concepts separately. An extensive laboratory testing program, including 468 beam tests, was conducted according to AASHTO T321-03 test procedure. Six factors that affect the fatigue response of HMA were evaluated: binder type, binder content, air voids, test temperature, rest period and applied strain. The endurance limit was determined when no accumulated damage occurred indicating complete healing. Based on the test results, a first generation predictive model was developed to relate stiffness ratio to material properties. A second generation stiffness ratio model was also developed by replacing four factors (binder type, binder content, air voids, and temperature) with the initial stiffness of the mixture, which is a basic material property. The model also accounts for the nonlinear effects of the rest period and the applied strain on the healing and endurance limit. A third generation model was then developed by incorporation the number of loading cycles at different locations along the fatigue degradation curve for each test in order to account for the nonlinearity between stiffness ratio and loading cycles. In addition to predicting endurance limit, the model has the ability to predict the number of cycles to failure at any rest period and stiffness combination. The model was used to predict fatigue relationship curves for tests with rest period and determining the K1, K2, and K3 fatigue cracking coefficients. The three generation models predicted close endurance limit values ranging from 22 to 204 micro strains. After developing the third generation stiffness ratio model, the predicted endurance limit values were integrated in the strain-Nf fatigue relationships as a step toward incorporating the endurance limit in the MEPDG software. The results of this study can be used to design perpetual pavements that can sustain a large number of loads if traffic volumes and vehicle weights are controlled.
ContributorsSouliman, Mena (Author) / Mamlouk, Michael S. (Thesis advisor) / Witczak, Matthew W. (Thesis advisor) / Kaloush, Kamil (Committee member) / Arizona State University (Publisher)
Created2012
Description
A full understanding of material behavior is important for the prediction of residual useful life of aerospace structures via computational modeling. In particular, the influence of rolling-induced anisotropy on fatigue properties has not been studied extensively and it is likely to have a meaningful effect. In this work, fatigue behavior of a wrought Al alloy (2024-T351) is studied using notched uniaxial samples with load axes along either the longitudinal or transverse direction, and center notched biaxial samples (cruciforms) with a uniaxial stress state of equivalent amplitude about the bore. Local composition and crystallography were quantified before testing using Energy Dispersive Spectroscopy and Electron Backscattering Diffraction. Interrupted fatigue testing at stresses close to yielding was performed on the samples to nucleate and propagate short cracks and nucleation sites were located and characterized using standard optical and Scanning Electron Microscopy. Results show that crack nucleation occurred due to fractured particles for longitudinal dogbone/cruciform samples; while transverse samples nucleated cracks by debonded and fractured particles. Change in crack nucleation mechanism is attributed to dimensional change of particles with respect to the material axes caused by global anisotropy. Crack nucleation from debonding reduced life till matrix fracture because debonded particles are sharper and generate matrix cracks sooner than their fractured counterparts. Longitudinal samples experienced multisite crack initiation because of reduced cross sectional areas of particles parallel to the loading direction. Conversely the favorable orientation of particles in transverse samples reduced instances of particle fracture eliminating multisite cracking and leading to increased fatigue life. Cyclic tests of cruciform samples showed that crack growth favors longitudinal and transverse directions with few instances of crack growth 45 degrees (diagonal) to the rolling direction. The diagonal crack growth is attributed to stronger influences of local anisotropy on crack nucleation. It was observed that majority of the time crack nucleation is governed by the mixed influences of global and local anisotropies. Measurements of crystal directions parallel to the load on main crack paths revealed directions clustered near the {110} planes and high index directions. This trend is attributed to environmental effects as a result of cyclic testing in air.
ContributorsMakaš, Admir (Author) / Peralta, Pedro D. (Thesis advisor) / Davidson, Joseph K. (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT Nursing physical fatigue is a critical issue that may lead to degradation of care delivery and ultimately result in medical errors. This issue is equally relevant due to the looming shortage of nurses, which has been linked to the physical demands and potential occupational hazards intrinsic to the profession; as well as to the graying of the nursing workforce who experiences gradual loss of strength and agility that accompanies aging as time in the career advances. In a hospital Emergency Department, the level of nursing physical fatigue can potentially reach its threshold in light of challenging workloads, scope of job assignments and demanding schedules. While in other safety-sensitive industries such as aviation and nuclear plants, similar concerns have been the object of systematic research and addressed with consequent regulations, just recently, the healthcare sector has been engaged in further investigations. This study proposed to explore the linkage between Emergency Department design-layout and nursing physical fatigue. It was expected that further understanding on this relationship would support evidence-based design propositions linking nursing wellness, job satisfaction, and performance to a higher quality of care and improved patient safety levels. To this end, data collection was performed during four weeks in a community-based hospital. A convenience sample of twenty-four eligible nurses was invited to participate in this two-part study. The first section consisted of the completion of a self-administered questionnaire, which assessed nurses' perception of the impact of working conditions on nursing physical fatigue. The second section included the monitoring, through the use of accelerometers, of nurses' actual activity intensity levels during three consecutive shifts. Among other findings, data demonstrated that nurses perceive several attributes or components of the built environment as potential contributors to physical fatigue. In addition, various operational practices and organizational protocols were linked to physical fatigue. Contrary to nurses' perception of physical fatigue, their actual physical activity levels fell mostly between sedentary or light intensity ranges. This paradox offers the opportunity for design interventions that, in alignment with operational practices and organizational protocols will enhance nurses' performance and improve nurses' retention.
ContributorsShakman, Karen (Author) / Bender, Diane (Thesis advisor) / Stein, Morris (Committee member) / Lamb, Gerri (Committee member) / Arizona State University (Publisher)
Created2011
Description
Perpetual Pavements, if properly designed and rehabilitated, it can last longer than 50 years without major structural rehabilitation. Fatigue endurance limit is a key parameter for designing perpetual pavements to mitigate bottom-up fatigue cracking. The endurance limit has not been implemented in the Mechanistic Empirical Pavement Design Guide software, currently known as DARWin-ME. This study was conducted as part of the National Cooperative Highway Research Program (NCHRP) Project 9-44A to develop a framework and mathematical methodology to determine the fatigue endurance limit using the uniaxial fatigue test. In this procedure, the endurance limit is defined as the allowable tensile strains at which a balance takes place between the fatigue damage during loading, and the healing during the rest periods between loading pulses. The viscoelastic continuum damage model was used to isolate time dependent damage and healing in hot mix asphalt from that due to fatigue. This study also included the development of a uniaxial fatigue test method and the associated data acquisition computer programs to conduct the test with and without rest period. Five factors that affect the fatigue and healing behavior of asphalt mixtures were evaluated: asphalt content, air voids, temperature, rest period and tensile strain. Based on the test results, two Pseudo Stiffness Ratio (PSR) regression models were developed. In the first model, the PSR was a function of the five factors and the number of loading cycles. In the second model, air voids, asphalt content, and temperature were replaced by the initial stiffness of the mix. In both models, the endurance limit was defined when PSR is equal to 1.0 (net damage is equal to zero). The results of the first model were compared to the results of a stiffness ratio model developed based on a parallel study using beam fatigue test (part of the same NCHRP 9-44A). The endurance limit values determined from uniaxial and beam fatigue tests showed very good correlation. A methodology was described on how to incorporate the second PSR model into fatigue analysis and damage using the DARWin-ME software. This would provide an effective and efficient methodology to design perpetual flexible pavements.
ContributorsZeiada, Waleed (Author) / Kaloush, Kamil (Thesis advisor) / Witczak, Matthew W. (Thesis advisor) / Zapata, Claudia (Committee member) / Mamlouk, Michael (Committee member) / Arizona State University (Publisher)
Created2012
Description
The popularization of energy drink use as a supplement to exercise is steadily increasing, especially among young adult males. However, the effects of energy drinks on muscular performance in young adults have yet to be clearly elucidated. Eight male subjects (mean age: 23.3 ± 4.3 yrs, height: 181.0 ± 5.3 cm, fat percent 17.8 ± 5.2%, and weight 85.3 ± 12.6 kg) completed this randomized double-blinded cross over study. The purpose of this study was to determine differences in acute muscular strength and endurance and Profile of Mood States (POMS) scores between three treatments (RockStar, sugar-free RockStar, and sugar-free caffeine-free Placebo). It was hypothesized that there would be no significant differences in acute peak torque and endurance of the knee extensors and flexors or on fatigue and vigor subscores from the POMS questionnaire. Each man was tested randomly at least 1 week apart. Diet and time of day were held constant across trials. Peak torque of knee extensors and flexors at 60, 180, 240 degress/second and fatigue index and total work were calculated by performing 50 repetitions at 240 degrees/second. There were no significant differences in peak torque, fatigue index, or total work measures or in subjective measures of fatigue or vigor from the POMS between the treatments. This study indicates that RockStar energy drinks have no acute ergogenic effects in young men performing isokinetic strength or endurance testing.
ContributorsHawley, Michelle (Author) / Swan, Pamela (Thesis advisor) / Campbell, Kathryn (Committee member) / Johnston, Carol (Committee member) / Arizona State University (Publisher)
Created2012
Description
This dissertation presents methods for addressing research problems that currently can only adequately be solved using Quality Reliability Engineering (QRE) approaches especially accelerated life testing (ALT) of electronic printed wiring boards with applications to avionics circuit boards. The methods presented in this research are generally applicable to circuit boards, but the data generated and their analysis is for high performance avionics. Avionics equipment typically requires 20 years expected life by aircraft equipment manufacturers and therefore ALT is the only practical way of performing life test estimates. Both thermal and vibration ALT induced failure are performed and analyzed to resolve industry questions relating to the introduction of lead-free solder product and processes into high reliability avionics. In chapter 2, thermal ALT using an industry standard failure machine implementing Interconnect Stress Test (IST) that simulates circuit board life data is compared to real production failure data by likelihood ratio tests to arrive at a mechanical theory. This mechanical theory results in a statistically equivalent energy bound such that failure distributions below a specific energy level are considered to be from the same distribution thus allowing testers to quantify parameter setting in IST prior to life testing. In chapter 3, vibration ALT comparing tin-lead and lead-free circuit board solder designs involves the use of the likelihood ratio (LR) test to assess both complete failure data and S-N curves to present methods for analyzing data. Failure data is analyzed using Regression and two-way analysis of variance (ANOVA) and reconciled with the LR test results that indicating that a costly aging pre-process may be eliminated in certain cases. In chapter 4, vibration ALT for side-by-side tin-lead and lead-free solder black box designs are life tested. Commercial models from strain data do not exist at the low levels associated with life testing and need to be developed because testing performed and presented here indicate that both tin-lead and lead-free solders are similar. In addition, earlier failures due to vibration like connector failure modes will occur before solder interconnect failures.
ContributorsJuarez, Joseph Moses (Author) / Montgomery, Douglas C. (Thesis advisor) / Borror, Connie M. (Thesis advisor) / Gel, Esma (Committee member) / Mignolet, Marc (Committee member) / Pan, Rong (Committee member) / Arizona State University (Publisher)
Created2012