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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.
11

Post-dispersal seed fates in a Western Oregon native prairie

Clark, Deborah L. (Deborah Louise) 17 April 1996 (has links)
Knowledge of post-dispersal seed fates and other regeneration characteristics is crucial for predicting abundances and distributions of populations and, ultimately, community species composition and diversity. Seed fate studies, however, are rare primarily due to the difficulty of determining seed fates and causes of mortality. This thesis investigated post-dispersal seed fates for four species common to western Oregon native prairies: Bromus carinatus Hook and Am. var. carinatus, Cynosurus echinatus L., Daucus carota L., and Prunella vulgaris var. lanceolata (Barton) Fern. The general approach was to sow seeds of these species into experimentally manipulated field plots for each of two years, and to recover these seeds from the soil one year later to determine their fates (persistence, death, or establishment as seedlings). The effect of mowing on seedling establishment was also addressed. Additional studies focused on the effects of a single mortality factor, fungal disease, on seed and seedling deaths. The fate of most seeds was death (44%-80%). Few seeds established as seedlings (4%-17%), and mowing did not significantly increase seedling establishment. Only Daucus carota formed a persistent seed bank. Fungal disease generally caused less than 10% mortality. Pot studies corroborated these field results. Other investigators have suggested higher levels of disease in natural vegetation. Vertebrate predation significantly reduced seed numbers for only Bromus carinatus (21%). The largest cause of death for all species for both years was the combined group of other mortality causes (invertebrate predation, interference, and abiotic factors) (52%-73%). The components of this combined group, however, differed among species. The most likely components for Bromus carinatus and Cynosurus echinatus were interference (competition plus allelopathy) and abiotic factors, although invertebrate predation cannot be ruled out for Bromus carinatus. Seedling death due to abiotic factors was most likely the largest component for Daucus carota. The most probable components for Prunella vulgaris were invertebrate predation and abiotic factors. Implications of these findings for population patterns and for restoration of native prairies are discussed. / Graduation date: 1996
12

Viability Profile of ex vivo Corneal Epithelial Cell Samples

Cira, Daniel January 2011 (has links)
The corneal epithelium is a vital tissue which must retain its integrity to preserve vision and protect against harmful bacterial infections and other insults. Corneal disease represents the second most common cause of world blindness after cataract.1 Examination of this tissue is therefore important in any ophthalmic routine, and in particular in contact lens practice where an increased number of factors, such as lens material, lens fit, care solution and contamination may directly affect its integrity. The ocular surface cell collection apparatus (OSCCA) allows safe and efficacious collection of human corneal epithelial cells2 and may provide the ability to examine cytological changes to the human cornea during lens wear. The overall objective of this project was to demonstrate the efficacy and reliability of the OSCCA as a tool to collect human corneal epithelial cells and examine cytological changes to the human cornea. This was achieved by characterizing the phenotype and viability status of cells collected from the ocular surface using the OSCCA and by comparing the obtained results with samples collected using other non-invasive techniques. There was a high level of uncertainty whether or not the cells collected were in fact corneal or conjunctival epithelial cells. Chapter 2 and 3 showed the Hoechst and PI were not optimal stains to measure the viability status of cells collected with the OSCCA because there was an unanticipated overlap of the fluorescence from PI+ nucleated cells into the blue spectrum and the Hoechst stained both live and dead cells. Chapter 4 looked at other cytological stains and concluded that the LIVE⁄DEAD® Viability⁄Cytotoxicity Kit (calcein AM/ethidium homodimer-1) was the most appropriate stain to use with the OSCCA collected cells due to the lack of overlap between stains. Chapter 3 showed that cells that stained with sodium fluorescein stained with only Hoechst and not PI. Since Hoechst stains live and early apoptotic cells and PI stains cells that are late stage apoptotic, necrotic and dead cells, we can conclude that sodium fluorescein stains live and early apoptotic cells. Similarly in chapter 5 it was found that cells that stained with sodium fluorescein stained exclusively with calcein blue AM and not ethidium homodimer-1.
13

Factors affecting the germination of safflower seed (Carthamus tinctorius L.)

Bantayehu, Gelan, 1939- January 1965 (has links)
No description available.
14

Viability Profile of ex vivo Corneal Epithelial Cell Samples

Cira, Daniel January 2011 (has links)
The corneal epithelium is a vital tissue which must retain its integrity to preserve vision and protect against harmful bacterial infections and other insults. Corneal disease represents the second most common cause of world blindness after cataract.1 Examination of this tissue is therefore important in any ophthalmic routine, and in particular in contact lens practice where an increased number of factors, such as lens material, lens fit, care solution and contamination may directly affect its integrity. The ocular surface cell collection apparatus (OSCCA) allows safe and efficacious collection of human corneal epithelial cells2 and may provide the ability to examine cytological changes to the human cornea during lens wear. The overall objective of this project was to demonstrate the efficacy and reliability of the OSCCA as a tool to collect human corneal epithelial cells and examine cytological changes to the human cornea. This was achieved by characterizing the phenotype and viability status of cells collected from the ocular surface using the OSCCA and by comparing the obtained results with samples collected using other non-invasive techniques. There was a high level of uncertainty whether or not the cells collected were in fact corneal or conjunctival epithelial cells. Chapter 2 and 3 showed the Hoechst and PI were not optimal stains to measure the viability status of cells collected with the OSCCA because there was an unanticipated overlap of the fluorescence from PI+ nucleated cells into the blue spectrum and the Hoechst stained both live and dead cells. Chapter 4 looked at other cytological stains and concluded that the LIVE⁄DEAD® Viability⁄Cytotoxicity Kit (calcein AM/ethidium homodimer-1) was the most appropriate stain to use with the OSCCA collected cells due to the lack of overlap between stains. Chapter 3 showed that cells that stained with sodium fluorescein stained with only Hoechst and not PI. Since Hoechst stains live and early apoptotic cells and PI stains cells that are late stage apoptotic, necrotic and dead cells, we can conclude that sodium fluorescein stains live and early apoptotic cells. Similarly in chapter 5 it was found that cells that stained with sodium fluorescein stained exclusively with calcein blue AM and not ethidium homodimer-1.
15

Single Walled Carbon Nanohorns as Photothermal Absorbers, and Incorporation of Spatial Digital Image Analysis into Cancer Diagnostics and Therapy

Whitney, Jon R. 06 May 2013 (has links)
Background: Photothermal therapy is an actively researched cancer treatment alternative to chemotherapy and resection due to its potential as a minimally invasive treatment with fewer health complications than high energy radiation therapies. The effectiveness of photothermal therapy may be enhanced with the use of photoabsorbtive nanoparticles by increasing heat generation and improving spatial selectivity. While photothermal therapy is a spatially distributed treatment, traditional experimental analysis methods used to assess photothermal therapy have either lacked spatial assessment such as is the case with standard viability assays of cell monolayers, or they only provide macroscopic treatment information, such as the measurement of the diameters of implanted mice flank tumors post-treatment. Goals: This work aims to accomplish two major goals. The first is to determine the therapeutic impact of combining Single Walled Carbon Nanohorns (SWNHs) with photothermal therapy. The second is to advance the measurement tools used to assess photothermal therapy by developing viability measurement methods which incorporate detailed quantitative spatial information Methods: Photothermal therapy was tested with and without SWNHs in in vitro cell monolayers, in vitro tissue phantoms, and ex-vivo tissue. Digital image analysis methods were developed which allowed for the use of viability assays and histological information to be identified and organized spatially. These methods were then used to compare the impact of cellular microenvironment and heating method on Arrhenius parameters. Results: The inclusion of SWNHs dramatically increased the temperatures reached in each experiment. Digital image analysis methods were shown to quantify spatial viability with a high degree of accuracy and precision in 2D and 3D. Experimental data indicated that there were areas of collateral damage (partially treated tissue) surrounding areas of completely treated tissue ranging which were between 46% and 78% of the completely treated volume. In each case the heat transfer properties of the experimental system had a large impact on the area of treatment. Variation in the temperature and viability response of photothermal therapy for specific laser and nanoparticle treatment parameters was quantified. Conclusions: This research has brought an experimental cancer treatment procedure from experiments in cell monolayers to tests in ex-vivo tissue to analyze viability response. The strengths of photothermal therapy such as its minimally invasive nature, and effectiveness at killing cells were experimentally demonstrated. This research has also developed the tools necessary to assess the spatial impact in vitro and lay the foundations for assessing spatial impact in vivo. These tools may be used to assess other treatments beyond photothermal therapy, and serve as a basis for improving the analysis of biological systems both in vitro and in vivo. / Ph. D.
16

Factors influencing germination and establishment of Arizona cottontop, bush muhly, and plains lovegrass in southern Arizona.

Livingston, Margaret. January 1992 (has links)
Germination and establishment was evaluated in Arizona cottontop (Digitaria californica (Benth.) Chase), bush muhly (Muhlenbergia porteri Scribn.) and plains lovegrass (Eragrostis intermedia Hitchc.) from southern Arizona. Germination was determined in different aged seed harvested from native and irrigated plots of various populations. Results indicated variability in germination characteristics of study species that appeared unrelated to afterripening or dormancy. Germination ranged from 62 to 96% for Arizona cottontop, 34 to 99% for plains lovegrass, and 75 to 99% for bush muhly. Bush muhly had highest average velocity of germination (58.0 ± 4.1), followed by plains lovegrass (35.9 ± 1.91), and Arizona cottontop (31.4 ± 1.13). Effects of 3 surface treatments (furrows, gravel, litter) and 2 cultivation treatments on establishment of study species and yellow bluestem (Bothriochloa ischaemum (L.) Keng var. ischaemum) was investigated in the field. Bush muhly did not emerge and plains lovegrass had minimal emergence. Arizona cottontop had similar emergence in cultivated and uncultivated plots whereas yellow bluestem had greater emergence in cultivated plots. Litter promoted greater survival of Arizona cottontop. Lower survival in furrows may have resulted from fewer days with available soil moisture and interference from greater density of non-seeded species. Soil covers appear to positively influence survival rather than emergence. Effect of rainfall distribution on germination was investigated using 2 seed retrieval methods. Arizona cottontop and bush muhly germinated after at least 3 days of available soil moisture. Plains lovegrass seeds did not germinate in the field but retrieved seeds had 83% germination, possibly due to light exposure under laboratory conditions. Another study determined whether species have different density and cover under overstory species compared to open areas. Arizona cottontop had either greater, less, or no differences in density under canopied versus open areas. Cover of Arizona cottontop was greater or similar among canopied and open areas. Plains lovegrass had lower or similar density and cover under canopies than in open areas. Bush muhly had greater density and cover under canopies. Overall, studies suggested that species are easily germinated, but accept relatively narrow ranges of environmental conditions for establishment. Establishment may be enhanced by sowing species when rainfall is consistent, extending available moisture through use of soil covers, or mimicking microsites where a species occurs naturally.
17

Dielectric and precursor analysis to study metabolic effects on CHO cell viability and antibody glycosylation

Braasch, Katrin January 2015 (has links)
The main goal in biopharmaceutical production is achieving high volumetric productivity while maintaining product quality (i.e. glycosylation). The objectives of this project were to explore the use of dielectric analysis in the early detection of cell demise and to analyze the impact of nucleotide / nucleotide sugar precursor feedings in biopharmaceutical production and glycosylation. Measurements of changes in the polarizability of individual cells can be performed in a dielectrophoretic (DEP) cytometer designed at the University of Manitoba. In this instrument the trajectory of individual cells was tracked according to their polarizability and recorded as a force index (FI). The identified sub-populations from a batch bioreactor and apoptosis-induced cultures were correlated with the fluorescent markers of apoptosis analyzed in a flow cytometer. Discrete cell sub-populations were identified as cells passed through the various stages of apoptosis. In the batch and the starvation culture the early changes in the measured FI of cells correlated with the Annexin V fluorescent assay associated with early phase apoptosis. For the oligomycin and staurosporine cultures changes in the FI could be correlated to modifications in the mitochondrial metabolism linked with early apoptosis for both inducers. In fed-batch experiments 10 mM galactose alone or 20 mM galactose in combination with 1 mM uridine or 1 mM uridine + 8 μM MnCl2 was added to the basal and feed medium for two CHO cell lines to determine their impact on the biopharmaceutical production and the glycosylation process. The results showed that the addition of all three precursors combined increased UDP-Gal, which increased and maintained the galactosylation index during the bioprocess for CHO-EG2 and CHO-DP12 cultures by 25.4% and 37.9%, respectively, compared to the non-supplemented fed-batch culture. In both cell lines saturation was reached when a further increase in the UDP-Gal concentration did not increase the galactosylation. A negative impact on cell growth was observed with the uridine addition in the CHO-EG2 culture, which was linked to the CHO-EG2 cell line being DHFR-/-. This work presents a dielectric detection method to monitor early changes in the cell metabolism and information for shifting and maintaining galactosylation during biopharmaceutical production. / February 2016
18

Storage of pregerminated snapdragon (Antirrhinum majus) seed in three hydrogels

Frazier, Diamantina Cerda January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
19

COMPOST BEDDED PACK DAIRY HOUSING: ANIMAL PERFORMANCE AND WELL-BEING AND ECONOMIC VIABILITY IN A PASTURE-BASED SYSTEM

Kawonga, Betty 01 January 2018 (has links)
Improving housing for dairy cattle is of interest because hoof and udder health, which are associated with the housing environment, are important economic and welfare issues. The objectives were: 1) to assess the influence of housing––conventional cubicle (CCD) vs compost bedded pack (CBP),––and management (grazing vs semi-grazing) on the performance and welfare in dairy cows 2) describe the performance of the CBP under a grazing or semi-grazing system, and 3) to assess viability of CBP housing in a pasture-based system. This study mixes three research approaches, an analysis of existing and secondary data; an experiment, and a case-study. If taken out of context and used in isolation, this mix of methods would lead to ambiguity and confusion. But in the context of the Malawi dairy industry, it is by mixing these methods that we can best inform farmer’s decisions about the type of structures that best serve them individually and the Malawian dairy industry as a whole. Cows were evaluated weekly for udder, hock, and hoof health, under a grazing (cows kept at pasture for 33 to 42% of the day) and semi-grazing system (cows kept at pasture for 16.67% of the day). No difference was observed between grazing and semi-grazing system regarding milk yield, hoof, hock, and udder health. Sub-clinical high SCC and SCC were 22% and 48% lower in the CBP barn than in the CCD barn. Cows in the CBP produced 1.2 kg per cow/day more milk than cows in CCD. No difference in CBP performance was observed under a grazing or semi-grazing system. Partial budget analysis showed that CBP was viable with net returns of $881. The benefits of the CBP over CCD are $ 1425 per year, but it would take an investment of $5368. The farmer would be expected to pay back the investment in 3.77 years.
20

Studies on the Relationship of Moisture Content to Threshability and Viability of Pea Seeds

Roquia Y Dulalas, Filixberto 01 May 1960 (has links)
When in commercial practice seed peas (Pisum sativum) are harvested, the vines are cut and windrowed or bunched and allowed to cure for a week or longer, depending upon the moisture content of the crop and weather conditions. The sooner the crop can be threshed, the less is the chance of loss caused by rain and the often-necessary attendant operation of turning the windrow or bunch to facilitate drying. In general, growers wait until the vines, pods, and seeds are quite dry. To what extent this is necessary is not known.

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