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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.
481

Environmental modeling study of water adequacy and yield from an irrigated rice field in Mali.

Tedla, Amhagiyorgis January 2015 (has links)
A process oriented modeling of an irrigated rice field in a semi arid area of Mali has been done with the help of computational tool CoupModel. The model has been used to simulate two levels of irrigation rates, in an attempt to test and see adequacy of a recommended irrigation rate and its environmental impact over the current management. A simpler simulation to represent less water demanding crops like sorghum or millet has also been done to indicate extent of the excess water and as alternative crop cultivation. Important processes and parameters to represent a rice cropping system have been identified and simulation was run for a 12 year period. Results show an irrigation amount of 916 mm delivers an overall 6 % increased yield. Results from the reduced irrigation also show a better output in surface runoff, nitrogen leaching and uptake, photosynthetic water use efficiency and fertilizer efficiency. Soil nitrogen and carbon storage shows nearly the same trend. Only nitrous oxide (N2O) emission rate increased by 13 % in the case of reduced irrigation. Simulation done for the other crops also shows a reasonable yield of sorghum or millet can be obtained with 46 % of water used for current rice irrigation.
482

Pre-Columbian Cultivation of Agave Species Through Rock Mulching: Potential for Modern Applications

Ortiz Cano, Hector Genaro 30 July 2021 (has links)
As global temperatures rise, cultivation of C3 and C4 crops in arid and semi-arid regions will face major challenges in producing biomass for billions of people. Conventional agricultural techniques that require copious irrigation will need to be complemented with dryland-farming techniques and drought-tolerant crops, such as those from the Agave genus, which use CAM photosynthesis. In the past and present, humans from arid and semi-arid regions of America have maintained a symbiotic relationship using and cultivating Agave (Agavoideae, Asparagaceae). In pre-Columbian times, Native Americans from arid regions relied on Agave cultivation as a subsistence crop to produce food, medicine, and fiber. The Hohokam in the Sonoran Desert cultivated Agave plants using rock mulching, also known as rock piles. This technique enabled the Hohokam to extensively cultivate Agave despite the limited rainwater available in the harsh Sonoran Desert. Although there are several decades of archaeological research for documenting the history of rock piles and Agave in the region beginning in the late 1970s, few studies have addressed the modern application of rock piles to cultivate Agave. Our research employed a multidisciplinary approach to bridge the historic use of rock piles to cultivate Agave with the potential application of rock piles for modern cultivation. In addition to summarizing what is known about the archaeology of Hohokam rock piles, we compiled an extensive review of the literature available on the agroecology, physiology, and natural history of Agave. We described key aspects associated with the hydrology and physical properties of Hohokam rock piles that can bolster Agave CAM photosynthesis in dry regions. We found that the use of rock piles is a feasible means of cultivating Agave under hot and dry conditions in arid regions. In addition, we used an ecological niche modeling approach and field data from Hohokam rock-pile sites and current Agave fields to assess the potential environments where rock piles could be used to cultivate Agave plants in Arizona, USA and Sonora, Mexico. We also combined an experimental archaeology approach with experimental plant physiology where we surveyed Hohokam rock-pile fields at archaeological sites to collect information about the composition of rock piles. We then created a rock-pile field where we evaluated and observed the effects of rock piles on Agave CAM utilization, mainly nocturnal CO2 uptake of Agave. Our results indicated that rock piles provide direct insulation to root systems, which indirectly benefited Agave carbon uptake and reduced temperature and drought stress. Although more agronomic research about rock pile use is needed, our research suggests that rock piles can be applied to cultivate Agave because of the physiological benefits provided such as increasing nocturnal total CO2 uptake. In addition, the suitability of rock piles in the U.S borderlands indicates that rock piles can be applied beyond the regions where they were used by the Hohokam in pre-historic times.
483

Hemin Utilization in Rhizobium leguminosarum ATCC 14479

Lusby, John 01 May 2021 (has links)
Rhizobium leguminosarum is a Gram negative, motile, nitrogen-fixing soil bacterium. Due to the scarcity of iron in the soil bacteria have developed a wide range of iron scavenging systems. The two types of iron scavenging systems used are indirect and direct. In-silico analysis of the genome identified a unique direct iron scavenging system the Hmu operon. This system has been identified in other closely related rhizobium species and is believed to be involved in utilizing heme compounds as a sole source of iron. We have attempted to characterize the role of the Hmu operon in iron utilization by monitoring the growth of R. leguminosarum ATCC 14479 in hemin supplemented media. Growth curves show that it is capable of using hemin as a sole source of iron. The outer membrane profiles were analyzed for the presence of hemin binding proteins.
484

CRBP-TS - evaluation of a home-based training and health care program for colorectal, breast, and prostate cancer using telemonitoring and self-management: study protocol for a randomized controlled trial

Falz, Roberto, Thieme, René, Tegtbur, Uwe, Bischoff, Christian, Leps, Christian, Hillemanns, Peter, Kohlhaw, Kay, Klempnauer, Jürgen, Lordick, Florian, Stolzenburg, Jens-Uwe, Aktas, Bahriye, Weitz, Jürgen, Bork, Ulrich, Wimberger, Pauline, Thomas, Christian, Biemann, Ronald, Jansen-Winkeln, Boris, Schulze, Antina, Gockel, Ines, Busse, Martin 06 March 2022 (has links)
Background: Physical training is recommended in various national and international guidelines for patients with cancer. Observational studies have shown that physical activity leads to reduced recurrence and mortality rates by 20–40% in colorectal, breast, and prostate cancer. Despite existing evidence, a systematic care structure is still lacking. The primary aim of this study is to implement and evaluate an online training platform to strengthen physical performance and patient empowerment after cancer surgery. Methods: The evaluation will be conducted as a prospective multicenter randomized controlled trial with three subgroups (colorectal-, breast-, and prostate cancer). Each group will include 100 patients (total 300 patients including dropouts; clinical stages T1–3 and/or N+; M0 after surgery intervention) and the primary endpoint (13% increase in the maximal oxygen consumption during exercise) will be examined. The intervention group will receive a 6-month home-based online training (2–3 times per week strength-endurance training using video presentations), bidirectional activity feedback information, online communication, and online counseling. The control group (usual care) will be advised lifestyle improvement. In-hospital testing will be performed before, during, and after the intervention. In addition to cardiopulmonary capacity, tumor specific diagnostics (liquid biopsy, depression and fatigue assessment, metabolic and endothelial screening) will be applied. Discussion: Due to the increasing incidence of cancer, associated with considerable mortality, morbidity and impaired quality of life, there is an imperative requirement for improved cancer care, of which structured physical training may become an integral component.
485

Phytates Reduce Uptake of Leucine and Glutamate but Not Lysine and Glucose From the Intestinal Lumen of Chickens: Short Communication

Onyango, Edward, Asem, Elikplimi K., Adeola, Olayiwola 01 December 2008 (has links)
An investigation into the influence of phytates on the in situ absorption of amino acids (lysine, glutamate and leucine) and glucose from the intestinal lumen of 3-week-old chickens was carried out. Birds were anaesthetised and the intestines exteriorised. Uptake of 5 mM of each nutrient over a 4-min period was measured in the presence of four phytate concentrations (0, 50, 250 and 500 mM). Five birds were used for each nutrient at each concentration of phytate tested. Leucine uptake decreased linearly (P < 0.001) and that of glutamate showed a tendency to decrease (P = 0.055) as the phytate concentration increased. Absorption of lysine and glucose were unaffected by the presence of phytate. In conclusion, phytate in the small intestinal lumen exerted a depressive effect on the absorption of specific free amino acids from the lumen. Its depressive effect was greatest for leucine followed by glutamate, and phytate had little effect on the absorption of lysine.
486

Reconsidering Illegal Hunting as a Crime of Dissent: Implication for Justice and Deliberative Uptake

von Essen, Erica, Allen, Michael P. 01 June 2017 (has links)
In this paper, we determine whether illegal hunting should be construed as a crime of dissent. Using the Nordic countries as a case study where protest-driven, illegal hunting of protected wolves is on the rise, we reconsider the crime using principles of civil disobedience. We invoke the conditions of intentionality, nonevasion, dialogic effort, non-violence and appeal to parameters of reasonable disagreement about justice and situate the Nordic illegal hunting phenomenon at a nexus between conscientious objection, assisted disobedience and everyday resistance. This examination leads us to contend that the crime has heretofore received an inadequate response limited to punishment and deterrence. This contention finds support in the worsening predicaments of illegal hunting following harsh sanctions and stigmatization. Although hunters publicize injustices through their crimes, we find that killing wolves as a means to deliberative ends disqualifies hunters’ dissent as legitimate disobedience, creating an obligation of deliberative uptake on the part of society. Nonetheless, in a critical contribution to the field of criminal justice, we argue that it is instead the conditions of deliberative suboptimality experienced by hunters that create this obligation of uptake. Hence, in order to fulfill this obligation, we contend that the burden falls on regulatory agencies to better articulate the justifications for the policies that coerce hunters. We also advocate creating novel institutions to provide hunters with effective opportunities for contesting wildlife conservation directives.
487

The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa

Mndela, Mthunzi 12 August 2020 (has links)
The encroachment of rangelands by woody plants causes an imbalance in the grass:bush ratio leading to decline in ecosystem services including grazing capacity, biodiversity, and water yield. This study assessed the historical changes in woody cover, and the effects of bush clearing on water loss, atmospheric carbon uptake, herbaceous vegetation, and soil seed bank (SSB) dynamics. The study was conducted at Makapanstad (Radi and Maseding) and Kgomokgomo rangelands, North-West Province, South Africa. Landsat imagery was used to assess woody cover over 34 years (1984 - 2018) in a total area of 16 397 ha. Evapotranspiration (ET) and gross primary productivity (GPP) were assessed in cleared sites and their adjacent uncleared sites from 2013 to 2018. Woody plant densities, herbaceous composition, ground cover and biomass production were assessed in 24, 5×5-m plots distributed equally in three 2500-m2 bush-encroached blocks in each rangeland in February 2016. Three samples for soil nutrient analysis were collected 20-cm deep in each plot. Thereafter, half (1250-m2) of each block was mechanically cleared to make three replicates of cleared and uncleared microsites. Post-treatment survey of vegetation was conducted in February 2017. SSB was assessed for samples collected in April 2016 before bush clearing and in August, October and December 2016, and April and August 2017 in paired microsites. In 1984, herbaceous cover (humid + arid grasslands) dominated, accounting for 36% of the total area followed by woody cover (shrublands + bushlands) and unvegetated cover (bare soils + abandoned croplands), with respective proportions of 33 and 31%. There were substantial land cover changes over time, with shrub cover increasing linearly (r2 = 0.94, p < 0.05) at a rate of 0.26% year-1, increasing the total woody cover (TWC) to 38% in 2018. Cropland abandonment was the main driver of increase in shrub cover in the study area. Herbaceous cover declined with increase in TWC (r2 = 0.69), whereas bare soil cover increased (r2 = 0.70) with TWC over time. The main encroachers were Vachellia tenuispina at Radi, Vachellia tortilis at Maseding and Dichrostachys cinerea and V. tortilis at Kgomokgomo. Most of the woody species correlated with total N and clay content (r = 0.96; p < 0.05) in black vertic clay soils of Radi and Maseding, whereas non-leguminous species correlated with total N and C:N in the red-yellow apedal soils of Kgomokgomo. ET and GPP varied interannually in all rangelands and both declined significantly (p < 0.05) after bush clearing at Radi and Kgomokgomo but not at Maseding. ET increased with GPP in cleared (r2 = 0.50-0.59) and uncleared sites (r2 = 0.82-0.93) at Radi and they showed a strong relationship (r2 >0.70) in both sites at Maseding and Kgomokgomo. ET ranged from 0.26-0.46 and 0.48-0.97 Kg H2O m-2 day-1 in cleared and uncleared sites, respectively, at Radi and from 0.44-0.98 and 0.63-1.24 Kg H2O m-2 day-1 at Kgomokgomo. Total SSB densities (constituted mostly by early successional species) increased significantly (p < 0.05) to 2470, 1872 and 693 seeds m-2 at Radi, Maseding and Kgomokgomo, respectively, in cleared microsites in August 2017. Similarly, biomass production (BP) and basal cover (BC) were highest in cleared relative to uncleared microsites. Overall, increase in woody cover reduced herbaceous cover and this calls for bush control in the studied rangelands. The decline in ET after bush clearing suggested that bush clearing could be used to increase rangeland water yield. Increased SSB densities, BP and BC indicated that bush clearing facilitates passive restoration. / Thesis (PhD (Pasture Science))--University of Pretoria, 2020. / Agricultural Research Council / National Research Foundation / Plant Production and Soil Science / PhD (Pasture Science) / Unrestricted
488

Kdp-dependent Kplus homeostasis of the halophilic archaeon Halobacterium salinarum

Strahl, Henrik 14 December 2007 (has links)
Halobacteria balance high external osmolality by the accumulation of almost equimolar amounts of KCl. Thus, steady Kplus supply is a vital prerequisite for life of these extreme halophiles. So far, Kplus was supposed to enter the cell only passively by use of potential-driven uniporters. However, the genome of the extreme halophilic archaeon Halobacterium sp. NRC-1 comprises one single operon containing the genes kdpFABC coding for homologs of the bacterial ATP-driven Kplus uptake system KdpFABC, together with an additional ORF so far annotated as cat3. Deletion of the kdpFABCcat3 genes led to a reduced ability to grow under limiting Kplus concentrations, whereas real-time RT-PCR measurements revealed both high induction rates and a transcriptional regulation of the Kdp system dependent on external Kplus concentration and growth phase. The synthesis of the high-affinity KdpFABC complex enables H. salinarum to grow under extreme potassium-limiting conditions of down to 20 µM Kplus. These results provide the first experimental evidence of ATP-driven Kplus uptake in halobacteria. The current opinion that Kplus homeostasis of H. salinarum is solely mediated via membrane potential-driven Kplus uniporters is obviously only one aspect of a more complex system.
489

Rapid Effects of 25-Hydroxyvitamin D<sub>3</sub> on Calcium Uptake in Isolated Chick Enterocytes

Phadnis, Ruta 01 May 2003 (has links)
25-Hydroxyvitamin D3[25(OH)D3] is a metabolite of vitamin D3 that has long been considered to be an inactive precursor of the hormonally active metabolite 1,25- dihydroxyvitamin D3[l,25(OH)2D3]; consequently very few studies have addressed the potential biological activity of 25(OH)2D3. However, it is known that 100 nM 25(OH)2D3 increases calcium transport in the perfused duodenal loop of the chicken to 200% of controls within 20 minutes. The hypothesis of the current study is that 25(OH)2D3 may be a hormonally active metabolite and its effects can be studied in isolated chick enterocytes. To begin testing this postulate, time course studies of 45Ca uptake were undertaken in isolated intestinal cells (from 7 wk chicks). After establishing the basal uptake of 45Ca for 5 minutes, cells were treated with vehicle(< 0.01% v/v ethanol, final concentration) or 25 nM, 50 nM, 100 nM, or 300 nM 25(OH)2D3 and samples were taken at T = 1, 3, 5, 7, and 10 min. With increasing concentrations of steroid, the enterocyte 45Ca decreased. The optimal concentration of 100 nM 25(OH)2D3 induced the most rapid response: within 1 min 45Ca decreased to 54% of controls (P < 0.001) and 70% of the controls at T= 3, 5, and 7 min (P < 0.01 to < 0.05, relative to controls). Comparison of the 7- min time points for 25 nM, 50 nM, 100 nM, and 300 nM 25(OH)2D3 appeared to yield a biphasic dose response curve with values of 45Ca observed at 99% (NS, not significant), 75% (P < 0.05), 70%(P < 0.01%), and 80% (NS) of corresponding controls, respectively. Physiological levels of 24,25(OH)2D3 (6.5 nM) inhibited the action of 100 nM 25(OH)2D3 in isolated chick enterocytes. Time course studies with isolated enterocytes from 14 wk and 28 wk chickens treated with 100 nM 25(OH)2D3 also showed decreased responsiveness: at T= 1 min 45Ca levels in 7 wk, 14 wk, and 28 wk were 54% (P < 0.01), 83% (NS), and 80% (NS) of corresponding controls, respectively. Experiments with the calcium channel activator BAY K8644 (2 μM) and protein kinase A (PKA) activator forskolin (20 μM) revealed enhanced levels of 45Ca at T= 10 min that were 132% and 140% of corresponding controls, respectively (each, P < 0.05). Phorbol ester treatment of the cells resulted in significant increases in the levels of 45Ca between the treated cells and corresponding controls at T=7 and 10 min. Cells treated with 100 nM 25(OH)2D3 revealed 89.8% and 78.4% increases above controls in PKA activity at T =1 min (P < 0.05) and T=3 min, relative to corresponding controls. However, there was no evidence for the activation of PKC by 25(OH)2D3 during the time period studied.
490

Duckweed Uptake of Phosphorus and Five Pharmaceuticals: Microcosm and Wastewater Lagoon Studies

Farrell, Jonathan Bay 01 May 2012 (has links)
Duckweed species L. turionifera and W. borealis grow on Wellsville Municipal Sewage Lagoons in northern Utah and, when harvested, contribute to the removal of phosphorus and pharmaceuticals from wastewater. Microcosm studies showed that duckweed contains an average of 1% phosphorus (dry weight) and removes 113 mg-P/m2day under 200 μmol/m2sec light. Duckweed in laboratory experiments reduced influent phosphorus ranging from 3.88 to 5.2 mg-TP/L to effluent concentrations of 0.88 mg-P/L in 3 days to 0.16 mg-P/L (0.32 mg-TP/L) with continual harvesting and a liquid retention time of 46 days. Duckweed removal of pharmaceuticals was comparable to removal by membrane bio-reactors. Duckweed removed 99% acetaminophen mainly by plant uptake; 98% progesterone primarily by absorption to plant tissue; 90% fluoxetine by adsorption with some biological removal attributed to plants; and sulfamethoxazole removal varied between 25 to 90% depending on polarity. Carbamazepine did not react with duckweed. Typical influent wastewater concentrations of the five pharmaceuticals in this study were not toxic to duckweed with an EC50 value of 614 μg/L per compound. HPLC/MS detection of pharmaceuticals in liquid samples using solid phase extraction at a neutral pH and silanized glassware produced 92-102% recoveries. Analysis of extracted solids produced lower recoveries. Solid extraction efficiencies ranged from 56-70% for samples stored for 24 hours and decreased with increasing storage time. Field growth studies showed higher than expected duckweed growth rates in the spring compared to three models due to turion germination after the ice melts. The growth rates decreased in the fall due to turion formation in preparation for winter. Harvesting duckweed from the Wellsville Municipal Sewage Lagoons should begin after full surface coverage around June 17th and end when temperatures fall below 15 °C around September 15th. Bi-weekly harvests with a starting plant density of 75 g-dry duckweed/m2 for the lagoons operating at 0.547 MGD and 5 mg-TP/L are required to physically remove enough phosphorus in order to meet the city’s 432 kg-P/yr discharge permit. A duckweed phosphorus harvesting system in Wellsville was estimated to produce enough biomass to meet the P-discharge limit until the flow increases above 0.656 MGD around the Year 2017.

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