The electrical activity recorded from the human colon could play an important role in analyzing the pattern of contractions under different physiologic or experimental states. In general, the frequency of the electrical activity is extremely irregular and time-varying. Its analysis requires a technique that considers variations in both time and frequency domains. The research undertaken was to analyze time-frequency variations of the human colonic electrical activity, to implement positive time- frequency distribution techniques in a computer system and to analyze theoretical signals using this technique to characterize a kernel function. Our results show that the uncertainty coefficient together with the marginal conditions and the average of the conditional PTFD in time and also in frequency can be applied to determine which kernel function and c-value were appropriate for calculating the PTFD of a sinusoidal signal. The selected kernel function constituted a comparative template of signals with similar characteristics. We found that those results were useful in analyzing the time- frequency variations of the electrical activity recorded in the human colon. The comparison of relative contributions of frequency bands showed that the band with the highest values during the pre- and interprandial period was 30-40 cpm suggesting an important role in the generation of bursts of these signals. The numerical results suggested that a meal can induce changes in the relative importance of frequencies below 10 cpm and a significant change in the 30-40 cpm band. In addition, a computer program of the Chakravarti method was implemented to calculate the Fourier transform of nonperiodical signals. This program was part of the computer program system developed to compute the PTFD of theoretical and experimental signals. / Thesis / Master of Engineering (MEngr)

Bacteriophages are promising biosensing systems in bioactive paper application due to their specific detection of bacteria. Different chemicals including wet strength resins were used to improve paper properties. This work investigated the influence of wet strength resins (PAE and PVAm) on bacteriophage activity, and proposed another method of using Poly NIP AM microgel to separate bacteriophage from paper surface. Compared with filter paper, the cationic polymer PAE and PVAm treated paper exhibited high phage binding efficiency but low phage activity due to the electrostatic interaction. PVAm had strong phage adsorption and almost completely deactivated the phage particle. Streptavidin was coupled to PolyNIPAM microgel in the presence of EDC, and T4 bacteriophage genetically modified with biotin was immobilized to microgel particle which resulted in a 10-fold improvement in attachment when compared with T4 wild-type phage. The microgel-phage coupling efficiency was very low, there were more than 10^6 micro gel particle for every active phage. And micro gel supported phages were deactivated after coating on the PAE/PVAm treated paper. / Thesis / Master of Applied Science (MASc)

No description available.

The primary objective of this project was to determine if a walking program based on social cognitive theory and delivered via the Internet could improve fitness levels in women. Fifty-three women were randomized to either an Educational Only condition or a Social Cognitive theory (SCT) condition. The SCT condition emphasized personalized mastery steps and goals to increase walking pace while the Education Only condition primarily provided general physical activity and walking information. The One-Mile Walk Test (Kline et al., 1987), an objective measure of fitness, was conducted to determine if women in the SCT condition had greater improvements in their fitness levels. The psychosocial measures of knowledge, depression, self-efficacy, outcome expectations, social support, and decisional balance pros and cons were administered to determine if changes were evidenced in these psychosocial measures pre to post treatment. Results indicated that both conditions had significant improvements in their fitness levels as measured by their walk test times and estimated VO2max. The SCT condition improved their time on the walk test by 69 seconds at post-test with an increase in estimated VO2max of 2.65 ml/kg/min whereas the Education Only condition improved their time on the walk test by 37 seconds with an increase in estimated VO2max of 1.1 ml/kg/min. Both groups also evidenced change on the self-report measures of stage of change with the SCT condition advancing 1.25 stages and the Education Only condition advancing .76 stages. Total minutes walked per week in the SCT condition increased by 31 minutes to 94 minutes total per week and by 47 minutes to 82 minutes total per week in the Education Only condition. Few of the psychosocial measures evidenced change pre to post. Of note, however, was the significant decrease in self-efficacy seen in the Education Only condition. In summary, both programs were able to make improvements in participants' fitness levels and time spent walking per week. However, the SCT condition, with its guided mastery experiences, had greater fitness improvements that are likely to have a larger clinical health impact. / Ph. D.

Objective: To explore the relationship between individual factors (i.e. affect, self-efficacy, and self-regulation), social and environmental factors, and their effects on the level of participation in physical activity (PA). Design: Undergraduate and graduate students (N = 386) completed 11 online measures assessing physical activity level and reactions to physical activity participation at Time 1, 9 online measures at Time 2, and a measure of physical activity participation at Time 3. Measures included those assessing affective reactions to PA, outcome expectancy, self-efficacy, self-regulation, social support, and perceptions of the environment. Results: Affect had a small total effect on METs (Ã =.13, p=.03), which was partially mediated by self-regulation, a strong predictor of METs (Ã =.45, p<.01). The total effect of affect on METs was substantially reduced (Ã =.05, p=.34) when self-efficacy was added as a precursor in the model. Self-efficacy influenced both METs (Ã =.39, p<.01) and affect (Ã =.23, p<.01). Adding environment and social support as predictors of self-efficacy (Ã =.23, p<.01; Ã =.19, p<.01, respectively) further reduced the influence of affect on METs (Ã =.03, p=.63) as environment and social support influenced affect (Ã =.20, p<.01; Ã =.14, p=.02, respectively) and METs (Ã =.15, p=.02; Ã =.21, p<.01, respectively). Conclusion: As in earlier studies of acute affective response to PA, these results provide evidence that anticipatory affect is positively associated with behavioral decision-making related to PA participation. Although increasing an individual's self-efficacy for PA should increase their affective association with the behavior, affect may not influence PA decision-making independently of self-efficacy and ecological factors (i.e. environment and social support). / Master of Science

Objective: To examine associations between neighborhood characteristics and diet and physical activity in those of differing socio-economic status. Design: A cross-sectional study was conducted among US adults living in a small Southeast community, including individuals at lower income levels. Physical activity was self-reported and objectively measured with a pedometer. Diet, self-efficacy, and perception of neighborhood friendliness were self-reported. Main outcome measures: Minutes of physical activity, self-efficacy towards physical activity, where residents exercised, and perception of neighborhood friendliness towards physical activity. Statistical Analysis Performed: Associations between where participants exercise and their minutes of daily exercise were analyzed by independent t-tests (p < 0.05). Income level and minutes of daily activity were analyzed with t-tests and later with UNIANOVA, controlling for age. Income and where participants exercise was analyzed using Chi square. Distance to the park and minutes of daily activity was analyzed with Pearson's correlation (two-sided, p < 0.05). Results: Income was not associated with daily minutes of physical activity or where a person chose to be active. Age was the biggest predictor of physical activity. Living on a street with a hill was positively correlated with self-efficacy for physical activity but negatively correlated with perception of neighborhood friendliness towards physical activity. Conclusion: Both high and low SES residents, within the same neighborhood, having access to the same recreational opportunities, did not differ in levels of physical activity. Both income groups met the current recommendations for physical activity suggesting access to parks with walking/biking trails, as well as other facilities, increases actual energy expenditure, independent of SES. Applications: Health officials and urban planners could work together in creating more recreational opportunities, especially in low SES neighborhoods, to increase national levels of physical activity. / Master of Science

Previous research, such as 'exercise determinants', has primarily sampled minimally physically active and sedentary people. In turn, studies focused on correlates of and perceived barriers to minimal physical activity (PA). The present study focused on exercisers (N=247, mean age=34) to assess social cognitive variables associated with PA consistency. Participants were categorized as either inconsistent, or slightly, fairly, or highly consistent exercisers. A new preference construct (type of activity, environment, social setting, feedback) for exercise was developed, and its association with consistency was assessed. Online measures assessed PA levels, preferences, enjoyment, outcome expectancy, self-efficacy, social-support, self-regulation. Higher planning confidence (Ã =.333, p<.000) and frequency (Ã =.276, p<.000) was associated with higher levels of PA consistency. Planning preference influenced planning frequency (Ã =.498, p<.000). Planning confidence influenced planning preference (Ã =.187, p<.003), which mediated its effect on planning frequency (Ã =.220, p<.000). Goal-setting frequency influenced consistency (Ã =.279, p<.000). Goal-setting preference influenced goal-setting frequency (Ã =.668, p<.000). Tracking frequency influenced consistency (Ã =.216, p<.000). Tracking preference influenced tracking frequency (Ã =.696, p<.000). Tracking confidence influenced tracking preference (Ã =.517, p< .000). Age influenced planning confidence (Ã =-.147, p<.021) and goal-setting confidence (Ã =-.164, p<.01). Engaging in PA in one's preferred environment (Ã =.540, p<.000) or with preferred company (Ã =.220, p<.001) was higher among more consistent exercisers. Using strategies to offset perceived barriers to exercise was highly predictive of consistency (Ã =.458, p<.000). Results suggest interventions should assess and match people to PA preference dimensions (i.e. environment, company, and self-regulation strategies) which will increase their self-regulation and ultimately exercise consistency. / Master of Science

Animal activity, in combination with physiological factors, can be used for early disease detection in dairy cattle. An initial study determined the impact of flunixin meglumine (FM), a non-steroidal anti-inflammatory drug, on activity measures, dry matter intake (DMI) and milk production during experimentally induced Escherichia coli mastitis. A total of 24 primiparous and multiparous lactating dairy cows were challenged with E.coli 727 in one quarter. Of the 24 E.coli challenged animals, 12 were administered FM at 0.002 µg/45.5kg of body weight at the onset of clinical mastitis signs. The remaining 12 cows were untreated. An additional 11 cows were infused with 1 mL of sterile phosphate-buffered saline, and served as the control group. Activity measures were collected through the use of the Afi PedometerPlus© and HOBO® data loggers. E.coli mastitis altered animal activity and improvement in DMI and milk production of animals given FM was observed, thus providing evidence for the use of an NSAID as supportive therapy for mastitis. Additionally, activity and blood metabolites concentrations were collected and analyzed from periparturient dairy cows at the Virginia Tech Dairy Center to determine the likelihood of disease occurrence. Primiparous and multiparous Holstein, Jersey, and Crossbred dairy cows were monitored for daily rest bouts, rest duration, and rest time throughout the pre and postpartum periods. Activity measurements were collected using Afi PedometerPlus© pedometers. It was concluded that evaluation of activity changes, and comparison of deviations from healthy herdmates, could allow producers to utilize activity monitoring to proactively manage dairy herd health. / Master of Science

Regular physical activity during pregnancy provides both maternal and infant health benefits. The complexity of measuring physical activity during pregnancy hampers the determination of the optimal dose of habitual physical activity for pregnant women and has led to broad physical activity guidelines for pregnant women. Subjectively-determined physical activity levels by means of questionnaires may have contributed to these broad guidelines. However the ActiHeart®, a dual heart rate monitor and accelerometer, is an accurate and reliable measurement tool to determine physical activity levels during pregnancy. Maternal physical activity tends to decrease during pregnancy and may lead to various health risks, including excessive weight gain, risk for gestational diabetes, lower back pain and adverse foetal outcomes. Determining the influence of physical activity on foetal growth is confounded by various variables, therefore objectively-measured habitual physical activity is essential. This study aims to objectively determine habitual physical activity patterns of pregnant women and the relationship between habitual physical activity and foetal growth parameters. In a longitudinal, observational, cohort study design, 60 pregnant women were measured at four stages in their pregnancy: the first trimester (9 – 12 weeks), second trimester (20 – 22 weeks), third trimester (28 – 32 weeks) and three months postpartum. Demographic information was collected by means of a questionnaire specifically compiled for this study, followed by anthropometric measurements (height and weight). Assessment of the participants resting blood pressure, heart rate (Microlife® Semi-Automatic blood pressure and heart rate monitor) and metabolic rate (FitmateTM, Cosmed) was obtained. Thereafter, a step-test was performed for individualised calibration of the ActiHeart® device for assessment of habitual physical activity patterns over a 7-day period. Foetal growth parameters that included birth weight (kg), birth length (cm), abdominal circumference (cm) and head circumference (cm), were collected from medical records and from the mother post-partum. Habitual physical activity, presented as average Activity Energy Expenditure (AEE), physical Activity Level (PAL), activity counts and minutes spent in activity, declined from the first to the third trimester of pregnancy. The AEE during the first trimester averaged 803 ± 34 kCal/day and declined statistically significant to 592 ± 383 kCal/day in the third trimester. Minutes spent per week doing moderate activity declined from 103 ± 83 min/week in the first trimester to 55 ± 66 min/week in the third trimester. Average pregnancy AEE indicated a non-significant negative relationship with all foetal growth measurements - birth weight (r = - 0.39, p = 0.45), birth length (r = - 0.16, p = 0.77), Ponderal Index (r = - 0.34, p = 0.51) - and a non-significant positive relationship with head circumference at birth (r = 0.14, p = 0.79). In conclusion, the objectively-determined, habitual physical activity levels of the participants did not meet the stated guidelines for pregnant women. During the progression of pregnancy, the activity levels declined significantly at the third trimester. The habitual activity levels indicate no effect on the foetal growth parameters. / MSc (Biokinetics), North-West University, Potchefstroom Campus, 2014

Regular physical activity during pregnancy provides both maternal and infant health benefits. The complexity of measuring physical activity during pregnancy hampers the determination of the optimal dose of habitual physical activity for pregnant women and has led to broad physical activity guidelines for pregnant women. Subjectively-determined physical activity levels by means of questionnaires may have contributed to these broad guidelines. However the ActiHeart®, a dual heart rate monitor and accelerometer, is an accurate and reliable measurement tool to determine physical activity levels during pregnancy. Maternal physical activity tends to decrease during pregnancy and may lead to various health risks, including excessive weight gain, risk for gestational diabetes, lower back pain and adverse foetal outcomes. Determining the influence of physical activity on foetal growth is confounded by various variables, therefore objectively-measured habitual physical activity is essential. This study aims to objectively determine habitual physical activity patterns of pregnant women and the relationship between habitual physical activity and foetal growth parameters. In a longitudinal, observational, cohort study design, 60 pregnant women were measured at four stages in their pregnancy: the first trimester (9 – 12 weeks), second trimester (20 – 22 weeks), third trimester (28 – 32 weeks) and three months postpartum. Demographic information was collected by means of a questionnaire specifically compiled for this study, followed by anthropometric measurements (height and weight). Assessment of the participants resting blood pressure, heart rate (Microlife® Semi-Automatic blood pressure and heart rate monitor) and metabolic rate (FitmateTM, Cosmed) was obtained. Thereafter, a step-test was performed for individualised calibration of the ActiHeart® device for assessment of habitual physical activity patterns over a 7-day period. Foetal growth parameters that included birth weight (kg), birth length (cm), abdominal circumference (cm) and head circumference (cm), were collected from medical records and from the mother post-partum. Habitual physical activity, presented as average Activity Energy Expenditure (AEE), physical Activity Level (PAL), activity counts and minutes spent in activity, declined from the first to the third trimester of pregnancy. The AEE during the first trimester averaged 803 ± 34 kCal/day and declined statistically significant to 592 ± 383 kCal/day in the third trimester. Minutes spent per week doing moderate activity declined from 103 ± 83 min/week in the first trimester to 55 ± 66 min/week in the third trimester. Average pregnancy AEE indicated a non-significant negative relationship with all foetal growth measurements - birth weight (r = - 0.39, p = 0.45), birth length (r = - 0.16, p = 0.77), Ponderal Index (r = - 0.34, p = 0.51) - and a non-significant positive relationship with head circumference at birth (r = 0.14, p = 0.79). In conclusion, the objectively-determined, habitual physical activity levels of the participants did not meet the stated guidelines for pregnant women. During the progression of pregnancy, the activity levels declined significantly at the third trimester. The habitual activity levels indicate no effect on the foetal growth parameters. / MSc (Biokinetics), North-West University, Potchefstroom Campus, 2014