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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

THE EFFECTS OF URBANIZATION ON THE WATER QUALITY AND HYDROLOGY IN THE KASKASKIA RIVER WATERSHED IN SOUTHERN ILLINOIS, UNITED STATES

Hwang, Charnsmorn 01 December 2010 (has links)
The Kaskaskia River is a large river system situated in central and southwestern Illinois serving as a tributary to the Mississippi River. Within the Lower Kaskaskia River Watershed (LKRW), an active urban-rural gradient currently exists in the Metro East area of St. Louis. Such areas of urbanization are particularly vulnerable to stream degradation. This study focuses on the effects of urbanization on water quality parameters within Silver and Richland Creeks, both of which are tributaries to the LKRW. Forty-three catchments within Silver and Richland Creeks were identified as study catchments. Stream water samples were collected within these catchments every two weeks in the dormant season and monthly in the growing season from January 2008 to August 2009. Stream storm samples were collected and stage was recorded within 4 intensively sampled catchments, which were representative of urban, village and agriculture watersheds. Stream samples were measured and analyzed for total suspended solids (TSS), turbidity, pH, specific conductance, total coliform, bacteria coliforms (as total coliform, fecal coliform (FC), and Escherichia coli (EC)), nutrients (orthophosphate, ammonium-N, nitrate-N, chloride, sulfate), and caffeine. GIS was utilized to identify percent urban land cover (LC) at the whole catchment scale and percent impervious surfaces (IS) at the riparian buffer scale. Whole catchment urban land cover (WCULC) was used to designate land cover categories of urban, village, and agriculture watersheds (>10.5%, >1% to 10.5%, and 0% to 1% WCULC, respectively). IS were identified at the riparian scale through manual digitization and classification of structures (i.e. buildings, houses) and roads (i.e. highways, streets) within 10, 30, and 50 m buffer widths. Correlations of water quality variables to percent whole catchment urban LC were comparable to that of riparian-scale IS (RIS). Whole storm Event Mean Concentrations (EMCs) for nitrate-N, orthophosphate, and sulfate were generally significantly lower in urban watersheds compared to village and agriculture watersheds. Stream water levels of EC, FC, and orthophosphate were relatively high. Levels of FC at both baseflow and stormflow and EC at stormflow far exceeded US EPA and IL EPA Review criteria, respectively. During baseflow, stream orthophosphate and nitrate concentrations within urban watersheds were significantly higher than in village and agricultural watersheds. The significant nutrient and bacteria levels in urban streams may be due to inputs via stormwater runoff, wastewater treatment effluent, and home septic systems. Although hydrometric data showed no significant differences among the intensively sampled catchments, the village watershed had much higher mean and larger maximum stream discharge compared to the urban and agriculture watersheds. Caffeine concentration in streams was not a useful indicator of anthropogenic impacts within the LKRW study area. Results from this study demonstrate that watershed managers can utilize WCULC since it is comparable to RIS. In addition, results further illustrate the need for urban best management practices to reduce water quality impacts, such as storm water management, improved wastewater treatment, and maintaining or developing vegetated riparian buffers.
32

Kinetics and equilibria of tea infusion

Price, William Evan January 1985 (has links)
No description available.
33

Caffeine as a hypertensive reagent

Crichlow, Eugene Chinloy January 1960 (has links)
Caffeine has been shown to induce a transient hypertensive state in Wistar rats. The height to which the blood pressure rises in this caffeine-induced hypertension, and the duration of this hypertensive state was found to be dependent on the concentration of caffeine administered. Caffeine exposed to negatively ionized air was shown to undergo a loss in its pressor activity. This loss in pressor activity was found to be greater when the caffeine was exposed in solution than when it was exposed in the crystalline state. Once the blood pressures of Wistar rats were elevated with injections of caffeine and had again returned to normal levels there were no further rises in blood pressures with the administration of an equal number of injections of this drug. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate
34

Synergistic effect of the carcinogen 4-nitroquinoline 1-oxide and the mutagen caffeine on mammalian cells.

White, James Franklin January 1971 (has links)
Numerous studies on bacterial systems have shown that cell survival following exposure to various mutagens is greatly influenced by the capacity of the cells to repair the induced DNA lesions. Caffeine (1-3-7-trimethyI xanthine), has been shown to reduce this repair-capacity thereby producing mutagenic, and cytotoxic effects. The question was raised as to whether or not caffeine might reduce the repair-capacity of mammalian cells by interacting with the DNA lesions produced by either the carcinogenic, and oncogenic 4-nitroquinoIine l-oxide, or ultraviolet light (UV) irradiation. This was of interest due to the potential applications that synergistic relationships may hold for chemotherapy. An established line of Syrian-hamster cells (BHK-21, clone 13), was used throughout the experiments. Arginine deprivation was employed to arrest the cultured cells at G₁-phase. The mutagenic 4NQO, UV, and caffeine were applied to these non-dividing cells. The caffeine exposure was at varying time intervals prior to, during, and after 4NQO-induced DNA-repair synthesis (unscheduled DNA synthesis). Similarly, caffeine was added to cells immediately following UV-induced DNA-repair synthesis. Exposure of BHK-21 cells to caffeine, and 4NQO appeared to reduce their colony-forming ability to a greater extent than when the cells were exposed to either chemical alone. The addition of caffeine combined with 4NQO to cells, in G₁-phase, did not appear to significantly influence their rate of flow into S-phase, or through to metaphase. The effect of caffeine on 4NQO- (but not UV-) induced DNA-repair synthesis, using isotope labelling, and autoradiography suggested a reduction in the amount of DNA-repair synthesis. This reduction appeared to be dependent on the caffeine concentration, and on the time of exposure of the cells to this chemical. An initial inquiry was made into whether or not this synergistic effect between caffeine and 4NQO-induced DNA-repair synthesis could be detected in human lymphocytes in vitro. However, very low levels of 4NQO-induced DNA-repair synthesis were observed in these cells. It was therefore not conducive for the autoradiographic analysis of DNA-repair synthesis following 4NQO exposure. A model explaining the apparent caffeine suppression of 4NQO-induced DNA-repair synthesis is postulated. The potential medical implications are discussed. / Medicine, Faculty of / Medical Genetics, Department of / Graduate
35

A novel tablet design for zero-order sustained-release

Sundy, Erica 28 January 2002 (has links)
Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Medicine in the branch of Pharmacy / A coated doughnut-shaped tablet is evaluated as its ability to release model drugs at a zero-order rate for 8 to 12 hours. The doughnut-shape tablets were compressed using special designed punches.Automated technology is thus feasible for this system. The coating material , 10% w /w gelatin in HPMC K15M was directly compressed and adhered to the tablet core . / IT2018
36

Controlling for Acute Caffeine Intake in Cardiovascular Reactivity Research

Grant, Shara Soyini 16 June 2016 (has links)
Caffeine substantially affects cardiovascular functioning, yet wide variability exists in caffeine control procedures in cardiovascular reactivity (CVR) research. This study was conducted in order to identify a minimal abstention duration in habitual coffee consumers whereby CVR is unconfounded by caffeine; Six hours was hypothesized (average half-life). Thirty nine subjects (mean age: 20.9; 20 Women) completed a repeated measures study involving hand cold pressor (CP) and memory tasks. Caffeinated and decaffeinated coffee were administered. The following CV indices were acquired during baseline, task, and recovery epochs prior to coffee intake, 30 minutes-, and six hours post-intake: Heart rate (HR), high frequency heart rate variability (hfHRV), root mean squared successive differences (RMSSD), systolic and diastolic blood pressures (SBP, DBP), mean arterial pressure (MAP), pre-ejection period (PEP), left ventricular ejection time (LVET), and total peripheral resistance (TPR). Results support the adequacy of a six-hour abstention in controlling for caffeine-elicited CVR changes. The current study contributes to methodological endeavors in psychophysiology. Further investigations are crucial in establishing ideal caffeine controls, which would promote increasingly valid and reliable cross-study results. / Master of Science
37

The effect of caffeine on blood pressure at rest and during submaximal exercise

Martin, Cynthia A. 03 June 2011 (has links)
The purpose of this investigation was to quantify the acute pressor response to caffeine at rest and during exercise, and to compare responses for different reportings of caffeine consumption and sensitivity. Eight young men with high use (HU) consumption patterns (<600 mg/day) and eight with low use (LU) patterns (<90 mg/day) participated. Caffeine (C) (4.5 mg/kg fat free mass) and placebo (P) were administered, double-blind and counterbalanced. Systolic (SBP), diastolic blood pressure (DBP) and heart rate (HR) were monitored during baseline, 40 minutes of absorption and graded treadmill walking. Oxygen consumption (V02) and rating of perceived exertion (RPE) were monitored during exercise. No significant differences were found for the responses to C between HU and LU nor between sensitive and not sensitive groups. Following a 12 hour abstinence, caffeine significantly increase SBP and DBP at absorption compared to P (11/9 mm Hg). The increase was additive with exercise for SBP but not DBP. Caffeine significantly increased VO2 compared to P. No significant differences were found for HR nor RPE between C and P trials. The present data indicate chronic caffeine consumption does not build tolerance to the acute pressor response to caffeine ingestion, the resting pressor response is additive with the pressor response to exercise for SBP, and individual perceptions of caffeine sensitivity are not accurate predictors of pressor responses. / School of Physical Education
38

The effect of consumption pattern on tolerance to caffeine

Zajakowki, Susan M. January 1995 (has links)
The effect of caffeine consumption on blood pressure has been widely studied. Robertson et al. (J Clin Invest 67: 1111-1117, 1981) cited findings of tolerance to humoral and hemodynamic effects from caffeine within four days when caffeine is consumed with each meal. These findings of tolerance have not been verified. The purpose of this study was to determine the effect of caffeine intake pattern on the development of tolerance to hemodynamic effects of caffeine. Fourteen volunteers were randomly assigned to two groups of seven. One group received 250 mg of caffeine in the morning only (MO), the other group received 250 mg of caffeine in the morning, afternoon, and evening (All Day-AD). Subjects underwent a seven day trial during which blood pressure (BP) and heart rate (HR) were assessed; morning beverage (250 mg of caffeine) was ingested and BP and HR assessments were obtained every 10 minutes for 50 minutes at rest, and after 10 minutes of cycling at 100 Watts. Afternoon and evening beverages were consumed which contained 250 mg caffeine each or placebo. No significant change in SBP, DBP, or HR from rest to 40 minutes post-caffeine absorption or between caffeine dosing pattern across trial days was found. A main effect was found for SBP post caffeine consumption (MO=5.4 vs. AD= 1.3). Mean values for DBP were stable across days 3-7 (M0=3.14-4.7 mmHg) but decreased from (3.86-.14 mmHg) from days 3 to 7 (AD). SBP revealed a significant interaction during exercise and across trial days. SBP and HR for the morning only group was higher than the all day caffeine consumption group across days. However DBP was lower across days for the morning only vs. the all day intake pattern. Therefore, caffeine dosing pattern does not appear to have an effect on tolerance to the hemodynamic effects of caffeine at rest or during exercise. / School of Physical Education
39

The liking for chocolate : attitudes, mood and psychopharmacological effects

Smit, Hendrick Jan January 1998 (has links)
No description available.
40

The risk for injury: investigating the roles of alcohol, caffeine, risk-taking propensity, and gender

Roemer, Audra 30 July 2019 (has links)
The combined use of alcohol and caffeine has been identified as a public health concern, and yet, our knowledge of this type of use and how it relates to the risk of incurring an alcohol-related injury remains limited. Study 1 is a systematic review examining and critically analyzing the literature on the combined use of alcohol with energy drinks and the risk of injury. Studies 2 and 3 use data from a controlled Emergency Department (ED) study that was collected over 1.5 years from 3 separate hospitals in British Columbia. There was a total of 2804 participants across the ages of 18-98. Given the strengths and limitations of these different methodologies, both case-crossover and case-control analyses were performed in order to test for consistency of results. Study 2 examined the temporal association between alcohol and caffeine and use (Alc+Caff) and the risk of injury, as well as the potential moderating role of risk-taking propensity and mediating role of Alc+Caff between risk-taking propensity and injury risk. The combined use of alcohol and caffeine was found to be associated with a higher risk of injury, even after controlling for dose of alcohol and caffeine, other substance use, location at time of injury, risk-taking propensity, and sociodemographic variables. Alcohol and caffeine use was also found to partially mediate the relationship between risk-taking propensity and injury. Study 3 examined gender differences in the risk-relationship of Alc+Caff use and injury by testing the interaction between gender and Alc+Caff use and then examining the risk of injury following Alc+Caff use separately for men and women. Women were found to have a significantly higher risk of injury following alcohol use and Alc+Caff use relative to men. These results were found in both the case-crossover and case-control analyses. The findings from these studies indicate a relationship between Alc+Caff use and an increased risk of injury, especially for women, which is supported by previous research. The results are supportive of differential low-risk drinking guidelines for men and women. The findings also offer a significant contribution to our knowledge base, as the use of standardized measures and inclusion of multiple confounding variables allowed for the examination of the unique effect of Alc+Caff use. Alc+Caff use is associated with an increased risk of injury that cannot solely be explained by increased alcohol consumption, other substance use, risk-taking propensity, location at time of injury, or sociodemographic factors. Based on the epidemiological criteria of causation, the findings contribute evidence supportive of an inference of causality between Alc+Caff use and injury. The results of the current studies also offer suggestions for future research needed in this area, and provide recommendations for policy prevention and intervention efforts to reduce the harm associated with this type of consumption. / Graduate / 2020-07-01

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