Heat stress is a common physical agent associated with many occupations. The most commonly used method of assessing heat stress exposure is an empirical method using the Wet Bulb Globe Temperature Index but his method is limited in its ability to parse out individual contributors to the heat stress. The International Organization for Standardization (ISO) published a rational model called Predicted Heat Strain (PHS) in 2004, and rational methods have the advantage of separating out the individual pathways for heat exchange. The objective of this research was a performance assessment of the current PHS model. This experimental design consisted of 15 trials (3 clothing ensembles and 5 heat stress levels) involving 12 men and women. The clothing ensembles were work clothes, NexGen® (microporous) coveralls, and Tychem® QC (vaporbarrier) coveralls. The heat stress levels were 1.0 , 2.0 , 3.5 , 5.5 and 9.0 °CWBGT above the average critical environment for each ensemble determined in prior studies. The metabolic rate was 190 W/m2. The two outcomes of each trial were an exposure time when core temperature reached 38 °C (ET38) and a Safe Exposure Time (SET) defined as the amount of time required to reach either a core temperature (Tre) = 38.5 ºC, a heart rate of 85% age-estimated maximum, or fatigue. ix Trial data for environment, metabolic rate and clothing were inputs to the (PHS) model to determine a predicted amount of time for the participants to reach a Tre = 38 ºC, which was the limiting condition in PHS for acute exposures. The first consideration was predictive validity for which PHS-Time was compared to ET38. The expectation would be that PHS-Time would predict the mean ET response. Results for predictive validity indicated a moderate agreement between ET38 and PHS-Time (r2 of 0.34 and Intraclass Correlation Coefficient at 0.33). When the method for accounting for clothing was changed to that recommended by ISO, the PHS predicted times moved systematically toward a shorter exposure time and modest agreement (r2 of 0.39 and Intraclass Correlation Coefficient at 0.31). Protective validity was the ability of the PHSTime to predict an exposure time that would be safe for most people. In this case, PHS-Time was compared to SET. The PHS was protective for 73% of the cases. When it was modified to account for clothing following the ISO method, the protective outcomes were 98%. In addition, the PHS model examined with respect to starting core temperature and fixed height and weight. Using the actual core temperature improved the outcomes somewhat, but changing from 36.8 to 37.0 would be sufficient. There is a strong tendency to over-predict PHS-Time for individuals with a low body surface area, usually short and lower than average weight.

The present study drew on Agnew's General Strain Theory (GST) to examine the relationship between strain, race, and delinquent behavior. To address this possible association, five hypotheses were tested to examine if different types of strain and stress exposure influence delinquent coping and if these relationships are conditioned by race and ethnicity. Using data from the Add Health Study, White, African American, and Hispanic adolescents, the present study attempts to generalize GST to different racial and ethnic groups. Results from OLS and negative binomial regression analyses indicate that some support was found for GST, in that indicators of strain to varying degrees predicted negative emotionality and youth involvement in nonserious and serious delinquency. Negative emotionality, however, did not mediate the relationship between strain and nonserious and serious delinquency. While, White, African American, and Hispanic youth did experience certain types of strain that lead to delinquent coping, these groups overall were not statistically different from one another. Furthermore, race and ethnicity were directly related to delinquent coping mechanisms, providing evidence that GST cannot fully explain the overrepresentation of minorities as delinquent offenders. A discussion of the findings, theoretical implications and directions for future research are highlighted.

The impact of stress on the health of postpartum mothers is poorly understood. Although the postpartum period increases risk for stress related diseases such as depression and autoimmune disorders, little qualitative research has focused on women’s perceptions of postpartum stressors. A constant comparative content analysis using Atlas.Ti was done on data collected by Groer (NIH R01 NR05000“Influence of Lactation on Postpartum Stress & Immunity) from 2001 to 2005. Women (n=127) answered the prompt, “Think of any one incident, thought, or feeling that stands out as very stressful to you and describe in as much detail as you choose.” Researcher triangulation was provided by independent coding of data by two qualitative researchers. The women were predominantly white (91%), married (72%), and not yet working following the baby’s birth (70%). Only 28% had family incomes greater than $40,000 per year. Vaginal births were experienced by 66%, 83% without complications. Forty-seven percent were breastfeeding exclusively with 43% bottle feeding. Slightly less than half (48%) were first time mothers. Eighty-nine percent claimed no recent major life event, such as a death in the family. Twenty-seven postpartum stressors were identified that were grouped into five themes: 1) environmental stressors, 2) symptoms of depression, 3) infant health and safety issues, 4) maternal role strain, and 5) lack of support. Seventeen women identified fatigue or lack of sleep as stressful and each questioned her ability to parent a newborn. Though these women would seem low risk for stress (having had an uncomplicated birth, being married and not yet back at work postpartum), 27 different postpartum stressors were identified. Stressors such as lack of sleep may be known by maternal-child nurses, but women are unprepared for them. Interventions need to be designed to provide anticipatory guidance for new mothers regarding postpartum stressors. Tools should be developed for use by clinicians to assess maternal stress in the postpartum period. Prenatal preparation anticipating stressors and postpartum vigilance in assessing stressors could ease the transition into motherhood.

Excessive exposure to heat stress can cause a host of heat-related illnesses. For laborers, job specific work demands and protective garments greatly increase the risk of succumbing to the effects of heat stress. Microclimate cooling has been used to control heat stress exposure where administrative or engineering controls are not adequate. This study tested the performance of four personal cooling vests for use with insulated protective clothing (gas extraction coveralls) in warm-humid (35 ° C, 50% relative humidity) and hot-dry (40°C, 30% relative humidity) conditions. On 10 separate occasions, 5 male volunteers walked on a treadmill to elicit a target metabolic rate of 300 watts, for 120 minutes, while wearing a (a) water cooled vest, (b) air cooled vest, (c) frozen polymer vest (FP) (d) liquid CO2 cooling (LCO2) vest, or (e) no cooling (NC). A three-way mixed effects ANOVA was used to assess the results and a Tukey's Honestly Significant Difference multiple comparison test was used to identify where significant differences occurred ( < 0.05). The air, water, and FP systems produced significantly lower heat storage rates compared to NC. To the extent that the gas extraction coverall is worn in an environment between 30°C and 45°C and the rate of work is moderate, the FP, air and water vest were shown to manage heat storage well, reducing storage rate by about 48%, 56% and 65% respectively.

Dynamic abnormal grain growth (DAGG) in commercial-purity molybdenum sheets was investigated through a series of tensile tests at temperatures between 1450°C and 1800°C. DAGG is abnormal grain growth (AGG) which requires the presence of concurrent plastic strain. Most AGG phenomena previously documented in the literature can be categorized as static abnormal grain growth (SAGG) because they occur during static annealing, sometimes following plastic strain, but do not occur during plastic deformation. The DAGG boundary migration rate is much faster than the SAGG boundary migration rate, and DAGG may be utilized to obtain large single crystals in the solid state. Dynamic abnormal grains were found to exhibit a crystallographic orientation preference with respect to the specimen geometry, generally described as derivative from a <101> fiber texture. DAGG was found to prefer growth on the surface of the specimen rather than the interior. The growth of dynamic abnormal grains, which initiated and grew during plastic straining, generally ceased when the application of plastic strain was removed. The DAGG boundary migration rate was found to be a direct function of plastic strain accumulation, regardless of the strain-rate. Therefore, it is hypothesized that the rapid boundary migration rate during DAGG results from an enhanced mobility of certain boundaries. A model is proposed based on the rate of boundary unpinning, as mediated by the emission of dislocations from pinning sites. / text

Body dissatisfaction is a growing problem in the gay male population, with serious implications for psychological and social well-being. Gay men tend to be at higher risk of body dissatisfaction than their heterosexual counterparts. They report lower levels of body satisfaction and have higher rates of risky behaviors such as anabolic steroid use, eating disorders, and over-exercising (Gil, 2007; Willoughby et al., 2008; Kaminski et al., 2004). It is difficult to determine the cause of this issue in the gay community; however, two theories have been proposed to help explain this phenomenon. Minority stress theory posits that it relates to added stress involved with being part of a minority group. Gender role strain theory identifies these concerns with the strain to conform to masculine gender roles. A common link to bridge the two theories together may be visibility management, which is the way gay men carefully disclose behaviors that would identify their sexual orientation (Lasser & Tharinger, 2003). The proposed method will include participants that will be approximately 130 gay men 18-23 years of age. Participants will be sought through online collection from universities in the United States. Participants will respond to empirically validated measures in regards to Minority Stress, Gender Role Strain, Visibility Management, and Body Dissatisfaction to help determine if what links there are between these variables. / text

Laboratory test of reinforced and prestressed concrete structures have been used widely to explore the behavior of reinforced and prestressed concrete components and structures; Such tests are often time-consuming and costly. However, numerical models have been shown to compare favorably with experiments. Thus, computations are viewed nowadays as efficient alternatives to tests, time-wise and cost-wise. In the research reported in this thesis, finite-element model were used in a study of pretressed structural components in order to correlate levels of pretension with deflection and strain measurements. The two main objectives were to develop a suitable finite element model of prestressed concrete beams and to forecast beam prestension on the basis of deformations resulting from specified simple load, e.g., a uniformly distributed transverse load. A commercial finite-element analysis package (ANSYS 12) was used to set up, use and evaluate the computational model. Furthermore, a finite-difference model was employed in order to ascertain the validity of ANSYS results by comparison with engineering beam theory taking into account the applied pretension. This study demonstrates the potential usefulness of deflection and strain measurements as indicators of the pretension applied or remaining in prestressed concrete beams. / text

The 2004 Sumatra-Andaman and the 2011 Tohoku-Oki earthquakes demonstrate the importance of understanding subduction zone earthquakes and the faults that produce them. Faults that produce earthquakes and/or tsunamis in these systems include plate boundary megathrusts, splay faults (out of sequence thrusts), and strike-slip faults from strain partitioning. Offshore Japan, IODP Exp. 314 collected logging while drilling (LWD) data across several seismically-imaged fault splays in the Nankai Trough accretionary prism. I combine LWD resistivity data with a model of fluid invasion to compare the permeabilities of sands. My results indicate that sands within faulted zones are 2-3 orders of magnitude more permeable than similar undisturbed sands. Therefore fault zones are likely to be fluid conduits within the accretionary wedge. Fluids can affect the physical and chemical properties of the faulted material, increasing pore pressures and effectively lubricating the faults. Fluids play an important role in fault slip, but hazard analysis also requires an understanding of fault geometry and slip direction. Both Japan and Sumatra exhibit strain partitioning, where oblique convergence between tectonic plates is partitioned between the megathrust and strike-slip faults proximal to the arc. Offshore Sumatra, I combine profiles from a 2D seismic survey (SUMUT) with previous bathymetry and active seismic surveys to characterize the West Andaman Fault adjacent to the Aceh forearc Basin. Along this fault I interpret transpressional flower structures that cut older thrust faults. These flower structures indicate that the modern West Andaman Fault is a right lateral strike-slip fault and thus helps to accommodate the translational component of strain in this highly oblique subduction zone. Offshore the Kii Peninsula, Japan, I analyze a trench-parallel depression that forms a notch in the seafloor just landward of the megasplay fault system, along the seaward edge of the forearc Kumano Basin. Using a 12 km wide, 3D seismic volume, I observe vertical faults and faults which dip toward the central axis of the depression, forming apparent flower structures. The along-strike geometry of the vertical faults makes predominantly normal or thrust motion unlikely. I conclude, therefore, that this linear depression is the bathymetric expression of a transtensional fault system. While the obliquity of convergence in the Nankai Trough is small (~15 degrees), this Kumano Basin Edge Fault Zone could be due to partitioning of the plate convergent strain. The location of the West Andaman Fault and KBEFZ within the forearc may be controlled by the rheology contrast between active accretionary wedges and the more stable crust beneath forearc basins. / text

Graphene is a promising material for flexible electronics due to its extraordinary electrical, mechanical, and optical properties. One of the biggest challenges today is to transfer large-scale graphene sheet to flexible substrates with minimal quality degradation. In this thesis, a bilayer polymer support for graphene transfer is proposed. Liquid PDMS (polydimethylsiloxane) is first coated on graphene to conform to its surface morphology. A flexible plastic substrate is then pressed on PDMS as a durable support. After PDMS is cured, electrochemical delamination is used to separate graphene from the copper foil. Due to the extremely low work of adhesion between graphene and PDMS, the graphene film on PDMS can be further transferred onto silicon wafer or other flexible substrates by simple adhesion. An added benefit of the PDMS layer is its strain isolation effect, which could protect graphene-based devices from breaking under external loads applied on the flexible substrate. The strain isolation effect of PDMS is verified with an analytical model and finite element analysis. The design of a prototype roll-to-roll graphene transfer machine is also presented. / text

Estimates indicate that by 2010 RN demand will exceed supply by over 400,000 full-time equivalents and by 2020 the RN shortage will increase to over 1 million. Turnover is a major contributor to the nursing shortage and job dissatisfaction is a well-established cause of nursing turnover. Understanding RN job satisfaction is an objective that is critical to keeping experienced nurses working in nursing and minimizing RN turnover. Many facets of RN job satisfaction have been examined in previous studies; however, much of the variance in job satisfaction remains unexplained. The purpose of this study was to explore job strain, body mass index, and background information variables (age, education, ethnicity, number of years in nursing, and perceived general health) as possible predictors of job satisfaction among hospital staff nurses. Resilience was examined for its mediating and moderating effects on the relationships between job strain and job satisfaction and body mass index and job satisfaction. The research design was cross-sectional and correlational. Surveys were mailed to RNs across the state of Texas. Reliable instruments were used to measure hospital staff RN job satisfaction, job strain, and resilience. Body mass index was calculated based on self-reported height and weight. From a sampling frame of full-time, hospital staff RNs purchased from the Texas Board of Nursing, a random sample of 556 RNs was obtained. The response rate was 27.6% (n = 147). Results showed that 25.2% of the RNs sampled reported high job strain. Job strain was significantly related to body mass index, and high job strain was significantly negatively related to job satisfaction. High job strain explained 24.7% of the variance in job satisfaction. None of the background information variables were significantly related to job satisfaction. Resilience had a moderating effect on the relationship between job strain and job satisfaction. Resilience did not mediate or moderate the relationship between body mass index and job satisfaction. Future research should focus on creating a nurse-specific instrument that measures job strain in hospital staff RNs. Intervention studies that investigate the effects of resilience training on the job satisfaction of hospital staff RNs should also be conducted. / text