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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.
51

Investigation of a Low-External-Input Sustainable Rice Production System to Identify Ecosystem Services towards Adoption Costs and Benefits

Firth, Alexandra Gwin 14 December 2018 (has links)
This study investigated a potentially sustainable rice production system in the Mississippi Alluvial Valley (MAV) that uses ecological principles to enhance environmental quality at the field scale. It was hypothesized annual flooding of rice fields to create waterbird habitat would benefit soil health, providing agronomic benefits to the farmer. Two sites were selected: a low-external-input-sustainable-agriculture (LEISA) system with flooded (LF) and nonlooded (LN) fields and a conventional site with flooded (CF) and nonlooded (CN) fields. Soil microbial diversity and nutrient content were quantified and compared. Camera traps were used to document bird activity for estimates of fecal matter input. Soil health variables linked LF high bird activity with soil health and pathogen detection. Evidence from the investigation provided a framework for other producers within the MAV to adopt similar management methods, ultimately improving the overall integrity of soil, water, and environmental quality.
52

Physiological characteristics and differences of national and international competitive cyclists /

Burke, Ed January 1979 (has links)
No description available.
53

The oxygen cost of cycling : upright versus recumbent position

Albert, Lee January 1997 (has links)
No description available.
54

The effect of Phosphoricum acidum 200CH on the adverse physiological effects induced by exercise in cyclists

Pantalone, Giovanni January 2011 (has links)
Dissertation submitted in partial compliance with the requirements for the Master’s Degree in Technology: Homoeopathy , Durban University of Technology, 2011. / The treatment with homoeopathic remedies, namely Phosphoricum acidum 200CH has proved to be effective in many clinical situations; however confirmation of its use within the sporting industry is limited. This study aimed to test Phosphoricum acidum 200CH efficacy in treating highly trained cyclists. This study was a superiority trial, in which the homoeopathic intervention was hypothesized to be superior to the placebo control group, in a statistically significant way (p < 0.05). Aim This study aimed to test the use of Phosphoricum acidum 200CH in treating the adverse physiological and psychological symptoms induced by exercise on cyclists. The aim for treating these adverse symptoms, induced by exercise, is to enhance performance and recovery of cyclists. Performance and recovery were tracked by assessing blood lactate concentration, oxygen consumption rate, heart rate, peak power output and emotional status. Methodology The study was a randomized controlled clinical trial, parallel group design. Participants were selected using convenience sampling of male road and mountain bike cyclists in the Western Cape. This study followed an explanatory Randomized Controlled Trial test, where the efficacy of the homoeopathic remedy (Phosphoricum acidum 200CH) was under investigation. The participants were selected with great care and testing was completed under highly controlled conditions. Thirty competitive male cyclists volunteered for this study. All participants were required to complete two cycling power to exhaustion interval tests, consisting of a ten minute warm-up at 100 Watts, followed by a five minute constant load at 150 Watts. The purpose of the constant load was to test cycling economy (CE). Thereafter the workload was increased to 200 W for 30 seconds and then the workload was increased by 20 Watts every 30 seconds. The test continued until the participant could no longer maintain the set repetitions per minute for that workload. The peak power output attained iv was recorded. The first test served as a baseline, after which a single dose of Phosphoricum acidum 200CH or identical placebo was administered, a 30 minute recovery period allowed for the remedy to take effect. The test interval was then repeated, the second test results were then compared to the first baseline test to determine the effect of treatment. The study took many different aspects of the remedies action on the cyclists into account, including mental and physiological effects. Breath-by-breath gases were continuously recorded. Expired gases, volumes and air flow were sampled through a flow meter and gas sampling line and heart rate was measured through telemetry (Polar®, Polar Electro, Oy, Finland) and analyzed by a cardio-pulmonary metabolic system (Quark CPET ® Cosmed, Rome, Italy, 2009). Data recorded was filtered for values outside the normal ranges and averaged for every five seconds. Oxygen consumption (vO2 mL.min-1) and heart rate (bpm) at different stages of each test interval were recorded. More specifically oxygen consumption and heart rates were averaged over the 5 minute section following the warm-up to determine cycling economy, directly after exhaustion for one minute and two minutes following exhaustion for another one minute period. Maximum attained heart rate was recorded for each interval test. Maximum oxygen consumption (vO2Max Absolute) was calculated as the mean of the highest three values attained, this mean was then divided by the participants body mass to determine maximum aerobic capacity (vO2Max Relative). Blood lactate levels were tested before, 15 minutes into and directly after each interval, to assess resting lactate status, cycling economy and to determine maximum lactate accumulation. Psychological testing included mood analysis, using a Stellenbosch mood scale (STEMS) questionnaire and further symptoms were analyzed using a Numerical rating scale (NRS) with symptomatic questions. Results From the results, it was clearly apparent that the control group proved to be of a higher calibre when comparing performance variables of the two groups namely:  Higher peak power output  Higher vO2Max  Lower economy lactate v  Lower resting lactate Despite the treatment group being the weaker of the two groups, they showed improvement in performance after administration of the remedy. This improvement was manifest through physiological alteration in the second test. More exclusively is the acceptance of the hypothesis concerning heart rate and oxygen consumption, whereby results showed that the administration of Phosphoricum acidum 200CH decreased heart rate and submaximal oxygen consumption rates during performance and recovery. There was no observable psychological effect during this study. The results suggest that Phosphoricum acidum 200CH primary demonstrated physiological effects on the cyclists. The researcher believes that this is due to insufficient time given for psychological alterations. Conclusion The Phosphoricum acidum 200CH has proven to be effective in enhancing cycling economy, reducing maximum heart rate and enhancing recovery to a large degree for the first minute following exhaustion. These positive effects are of great importance as the treatment group was the weaker of the two groups. Resulting in the possibility of even larger results being observable in repeated studies where both groups have similar performance abilities.
55

Factors influencing short duration, high-intensity endurance cycling

De Pao, Andrew T. (Andrew Thadeu) 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: A 5 km cycling time trial (TT) demands high, sustained muscle power output and substantial oxidative and glycolytic energy delivery. The aims of this study were to firstly use the novel approach of using Peak Sustained Power Output (PSPO) as a predictor of cycling performance for variable fixed-workload testing and 5 km time trialing and whether oral creatine supplementation would affect 5 km time trial performance and metabolism. The effect of oral creatine supplementation with 20 g/day for 7 days on 5 km time trial performance and metabolism after a random-variable workload protocol (stochastic test) was investigated in a single-blind placebo controlled study. Thirteen trained male cyclists volunteered for the study that was approved by the University of Stellenbosch Research Ethics Committee. We hypothesized that Cr supplementation would affect time trial performance as well as the appearance of breakdown products of adenine nucleotides in the plasma. Baseline: the subjects' peak power output was measured and they underwent a baseline stochastic test followed immediately by a 5 km time trial (STI) and on a different day, a single 5 km time trial test (Tl) was undertaken. Study 1: In the following week the subjects repeated the stochastic test with 5 km time trial (ST2) and on a different day a 5 km time trial (T2). During T2 blood samples were taken at regular intervals as well as during recovery. A muscle biopsy was taken after T2 in the recovered state. The major performance predictors were the 5-km time trials (TTl and TT2) with a coefficient of variation between the thirteen trained male cyclists of 0.6%. The 5 km time trials in the fatigued state (STI and ST2) had a coefficient of variation of 0.7%. Results: There was a significant difference between 5 km TT performed fresh and 5km TT performed fatigued (P=0.0001). The decrement in time ranged between 1.0 sec to 38.0 sec. The relationship between two different high intensity endurance performance tests: PSPO and 5 km TT (TT mean) had a correlation ofr=-0.79 P<O.OI. The correlation between PSPO and the 5 km TT performed in the fatigued condition (ST mean) was r= -0.60 P<0.05. There was also a relationship between age and PSPO (F 0.73; P<0.05). Age showed a good negative relationship with TT mean (F- 0.71; P<0.05). Mass and PSPO were also correlated (FO.85; P<O.OI). Plasma lactate concentrations were significantly different from rest at all other time points P<O.OOOIup to 20 minutes post-exercise. Hypoxanthine (P<O.OOOI)and urate (P=O.05) concentrations were also significantly different from rest at all other time points. There was a significant change in plasma hypoxanthine concentrations over time (P<0.0001). There was a significant correlation between plasma lactate concentration at time 0 in recovery and % Myosin Heavy Chain (MHC) I (FO.59, P<0.05) and % MHC na (F -0.61, P<0.05). Area under the curve for hypoxanthine showed significant relationships of F -0.53 (P=O.05) and F 0.56 (P<0.05) respectively for %MHC I and %MHC ITa. Study 2 - Supplementation: following T2 the subjects received Cr or placebo powder containing sachets to be ingested 4 times daily for the next week with carbohydrate also provided. Post-supplementation testing: the subjects returned and conducted another variable fixedworkload test with 5 km time trial (ST3) as well as a single 5 km time trial (T3). They once again underwent the same blood sampling routine and had another muscle biopsy in the rested state. The average of ST1 and ST2 was used as the major measure for performance under fatigued conditions and TTmean. Results: there was a significant difference between 5 km TT performed fresh and 5 km TT performed fatigued (P=0.0001). Plasma lactate, hypoxanthine and urate samples were taken at the postloading 5 km time trial (TT3). The levels of these plasma metabolites were compared to the concentrations of those sampled at TT2 and between the creatine and placebo groups. The plasma hypoxanthine levels were significantly different from rest for both the creatine and placebo groups (P<0.0001). Plasma urate had significant change in concentrations over the time points (P<0.005). Another significant difference was found between the creatine and placebo groups for the pre-and post tests conducted (P<0.005). The creatine group showed a non-significant increase (7%) in mean total intramuscular creatine concentration. No significant differences were found in the mean values for total nucleotide concentration pre- and post loading in the creatine and placebo groups. Conclusions: The 5 km performance test resulted in high values for plasma lactate, hypoxanthine and urate, an indication of fatigue induced by this performance test. Oral creatine supplementation did not improve performance significantly in the variable fixedworkload protocol 5 km time trials or the individual 5-km time trials and had an effect on adenine nucleotide metabolism in both the variable fixed-workload protocol 5-km time trial and individual 5 km time trial performance tests. / AFRIKAANSE OPSOMMING: Die 5 km fietsry tyd toets (TT) verg hoëvolgehoue, spierkrag en wesenlike oksidatiewe en glikolitiese energie verskaffing. Die doelwitte van hierdie tesis was eerstens om 'n nuwe fietsergometer toets te ontwerp vir die voorspelling van kompetisie prestasie. Die toets was 'n veranderlike, voorafvasgestelde werkladingstoets (VVWT). Dit is vergelyk met 'n maksimale volgehoue kraguitsetingstoets (MVKT) en 'n 5 km TT. Daarna is bepaal ofkreatien supplementasie 'n effek sou hê op enige van hierdie oefeningstoetse of metabolisme tydens die 5 km TT. Die supplementasie eksperiment was 'n enkelblinde, plasebo-gekontroleerde studie ontwerp. Dertien manlike fietsryers het vrywilliglik deelgeneem. Resultate: Daar was 'n statisties betekenisvolle verskil tussen die 5 km TT wat vars onderneem is en die wat direk na die VVWT onderneem is (P=O.OOOl). Daar was ook 'n betekenisvolle korrelasie tussen die twee verskillende hoë intensiteit korttydsvak oefeningstoetse (r=-0.79 P<O.Ol vir TT en MVKT). Plasma laktaat konsentrasies was betekenisvol verhoog met vergelyking van die monsters geneem tydens rus en all ander onteledings tydspunte (P<0.0001) tot en met 20 minute na oefening. Hypoxantien (P<O.OOOl) en uraat (P=0.05) konsentrasies was ook betekenisvol verskillend van rus by alle ander tysdpunte. Daar was 'n betekenisvolle korrelasie tussen plasma laktaat direk na oefening en die % Myosien Swaarketting (MIlC) I (r=0.59, P<0.05) en % MHC ITa (r= - 0.61, P<0.05). Studie 2 - Na supplementasie was daar geen verskil in oefeningsprestasie nie maar wel in plasma metaboliet waardes van nie. Gevolgtrekkings: Die 5 km TT het baie hoë waardes vir plasma laktaat tot gevolg gehad, asook hypoxantien en uraat, 'n indikasie van die hoë mate van vermoeienis deur hierdie oefeningtoets berwerkstellig. Kreatine supplementasie kon nie oefeningsprestasie verbeter nie.
56

Effects of Endurance Intensity and Rest Interval on Subsequent Strength Performance

Books, Gregory D. (Gregory Douglas) 05 1900 (has links)
The purpose of this study was to examine the acute effects of cycling exercise at different intensities and rest intervals on strength performance. Ten males, engaged in concurrent training for at least one month prior to testing, comprised the subject group for this study. Results show only leg press torque and leg press work to be decreased after cardiorespiratory exercise of moderate intensity. Leg extension average power, chest press torque, chest press power, and chest press work after cycling were not decreased from pre-exercise values. No significant effects were found for exercise intensity, testing times, or intensity by testing times. These results indicate that lower body strength is decreased by cycling and that one hour is not sufficient to restore leg strength.
57

Interactions between nitrogen fixation and methane cycling in boreal peat bogs

Warren, Melissa 08 June 2015 (has links)
Microbial nitrogen (N2) fixation supplies important nitrogen inputs to boreal peatlands, extremely oligotrophic ecosystems dominated by Sphagnum mosses. In this study, we coupled major and trace nutrient analyses and rate measurements to characterize interactions between N2 fixation and CH4 cycling at the S1 peat bog in Marcell Experimental Forest and the Zim bog (Minnesota, USA). Total dissolved inorganic nitrogen (NO3-+NO2-+NH4+) and phosphate were both consistently < 2 μM in the porewater of surface peat, indicating severe nutrient limitation. While dissolved Fe was fairly abundant (18-35 mM), Mo, V and Cu were scarce (2-40 nM), suggesting that alternative metalloenzymes containing Fe in place of other metals may be favored. Rates of diazotrophy measured by both 15N2 incorporation and the acetylene (C2H2) reduction assay (ARA) were 7-fold higher under anoxic vs. oxic incubations conducted at both 4°C and 25°C. No significant difference in N2 fixation rates measured by either method was observed with or without the amendment of 1% CH4 at 25 °C; however, a significant inhibitory effect by methane was seen at 4°C in material from the S1 bog hollows. Anoxic 15N2 incorporation was 3-4x higher in treatments lacking acetylene, suggesting that the ARA likely underestimates N2 fixation by inhibiting diazotrophs sensitive to C2H2. Aerobic methanotrophy was also inhibited by 1% C2H2 when incubated under oxic conditions. No observations for the production of ethane (C2H6) were detected during the ARA, a biomarker for alternative nitrogenase activity. Major differences in ARA rates were observed to vary locally within microhabitats and between two bogs. In June 2014, peat sampled from hollows incubated under anoxic conditions showed the highest ARA rates (94.9 ± 11.0 nmol C2H4 g-1 moss dry mass hr-1), while the lowest rates were observed in ix hummock samples incubated under oxic conditions (5.1 ± 0.8 nmol C2H4 g-1 moss dry mass hr-1) in the S1 bog (T3 site). Observed rates have the potential to be a function of oxygen concentrations and or water content. ARA rates in all microcosm treatments were significantly lower at Zim bog compared to the S1 bog. The developed conversion factor between the regression of 15N2 and ARA in this study was 3.9 and agrees with the theoretical conversion factor as well as previous studies of soils and forest mosses.
58

Lateral displacements of automobiles due to the presence of bicycles in a common right-of-way

Saccheri, John Basadassare, 1934- January 1975 (has links)
No description available.
59

Cyklistická doprava na území Středočeského kraje / Cycling in the Central Bohemia Region

Jandová, Michaela January 2009 (has links)
The aim of this thesis Cycling in the Central Bohemia Region is to analyse the state of cycling in selected microregion, to analyse preconditions for further development of cycling and to assess the state of cyclepaths in the microregion. The emphasis is put on the development of cycling as an equivalent means of transport. The other aim is to identify the key problems of cycling and to propose own solutions, which would lead to elimination of problems, which have been found. This thesis also includes a detailed analysis of parking cycling infrastructure and proposals for adequate measures for its improvement.
60

The effect of carbohydrate-loading and carbohydrate ingestion on fuel substrate kinetics during prolonged cycling

Bosch, Andrew Norman January 1995 (has links)
It has been well established that both carbohydrate-loading before and carbohydrate ingestion during exercise can enhance endurance performance by supplying carbohydrate for oxidation. However, the precise mechanism(s) underlying the proposed ergogenic effects of these procedures remain to be established. The studies in this thesis were therefore designed to examine the effects of carbohydrate-loading and carbohydrate ingestion on fuel substrate kinetics.

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