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Browsing by Subject "University of Minnesota - Duluth"

Now showing 1 - 4 of 4
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    Exercise and Psychological Stress: How Does Exercise Promote the Alleviation of Stress?
    (2011-04-13) Smith, Melissa
    Stress is an inevitable aspect of life, so how does one handle it on a daily basis? Exercise is an excellent coping mechanism for many. But how does exercise reduce stress? Previous research indicates a difference in cortisol levels, reactivity to, and recovery from stress (Jackson & Dishman, 2006).The purpose of this study was to examine cortisol levels between high and low fit groups as well as differences in reactivity to and recovery from stress. First, a fitness questionnaire was given to participants to assess total number of hours per week of exercise. Saliva samples were used to analyze cortisol levels and were obtained using a Salivette collection device. A saliva sample was first taken to establish baseline cortisol levels. Then, the participant completed a series of tasks in the following order: public speaking, mental arithmetic, and a cold pressor task followed by another saliva sample. Lastly, saliva samples were taken following a recovery period. An immunosorbent assay kit was used to measure cortisol levels in the saliva (IBL America, Minneapolis, MN). Following cortisol analysis, the fitness questionnaire was evaluated. Participants were divided into two groups based on a five hour per week median. Five or less hours was considered low fit (N=21) and more than five hours was considered high fit (N=24). A 2x7 ANOVA was used to analyze the differences in cortisol levels, reactivity, and recovery between high and low fit. A significant difference was found in cortisol levels between high and low fit participants (F4.1, 174=2.595, p= 0.036). High fit participants were also found to have greater reactivity to a stressor (F1, 42=3.780, p=0.059) as well as faster recovery from a stressor (F1, 42=7.656, p=0.008). These results imply that high fit individuals have lower overall cortisol levels and greater reactivity to and recovery from a stressor.
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    Investigation of Variable Exercise Intensities on Coincidence Anticipation Timing
    (2011-04-13) Smith, Melissa
    Coincidence anticipation timing is the ability to track a moving stimulus and correctly perform a coincident action at the exact moment the stimulus arrives at a target area. For example, a baseball hitter uses his coincidence anticipation timing skills while tracking a baseball from a pitcher’s hand to the exact moment he strikes the ball with his bat. He uses his ability to determine how and when to swing his bat in order to make contact with the ball. Past vision research studies have examined the effects of different exercise intensities on a subject’s dynamic visual acuity, the ability to track a moving object. Since dynamic visual acuity has been one of the only aspects of visual ability examined, the purpose of this study was to examine the effect of varying levels of exercise intensities on a performer’s coincidence anticipation timing. Twenty college-aged students’ coincident anticipation ability was tested at rest and during cycling across three varying exercise intensity levels: 30%, 60%, and 90% of maximal heart rate. Coincidence anticipation timing for each of the four experimental conditions was recorded in milliseconds. Each subject's coincident anticipation timing scores were calculated in terms of absolute (magnitude), constant (bias), and variable errors (consistency). Three separate one-way ANOVA analyses were performed for each type of error to determine the effects of the different experimental conditions on coincidence anticipation timing. The results of the study determined if exercise intensity affects one’s ability to accurately perform receptive skills such as hitting or catching with little bias and high reliability.
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    Protein Synthesis Is Required for Recovery of Escherichia coli from Desiccation Stress
    (2009-04-08) Grunewald, Justin
    The stress of desiccation is fatal to many cells and can induce significant water loss, which can impact the structure and function of membranes. When put under the stress of desiccation, E. coli cells are thought to enter a Viable But Nonculturable state (VBNC). The VBNC state is brought on by various stresses and leads to absence of cell division, reduced activity, but cells remain viable. By adding chloramphenicol to cells, the importance of protein synthesis during desiccation and rehydration was investigated. Understanding the mechanism required for recovery from the VBNC state is important in determining ways to improve microbial inhabitants in clinical and agricultural settings.
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    Pumped Hydro Energy Storage (PHES) Using Abandoned Mine Pits on the Mesabi Iron Range of Minnesota – the Range of Opportunities and Issues
    (2011-11) Fosnacht, Donald
    Using the 48 GIS coverages collected for this study, and total of 27 sites along the 120 mile long Mesabi Iron Range (MIR) were evaluated as potential PHES site. A set of pass/fail criteria were used by the four teams to evaluate and rank 14 of the most promising sites.