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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.
1

Fitness and Management of Site-specific Fungicide Resistant Cercospora beticola Isolates from Sugar Beet

Liu, Yangxi January 2020 (has links)
Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is one of the most destructive foliar diseases on sugar beet. It severely affects productivity and profitability of the sugar beet industry. CLS is managed by using resistant cultivars, rotating with non-host crops, and applying effective fungicides in a timely manner. In North Dakota and Minnesota, site-specific fungicides, such as quinone outside inhibitors (QoIs) and demethylation inhibitors (DMIs), had been widely and extensively applied to control C. beticola which has developed resistances to these fungicides. The mycelial growth, spore production, spore germination, and aggressiveness of QoI and/or DMI resistant isolates were compared to sensitive isolates in a laboratory and greenhouse study. Results indicated that the QoI and/or DMI resistant isolates had a relatively slower disease development on sugar beet leaves due to their fitness penalty in sporulation and mycelial growth but still caused high disease severities as sensitive isolates. Fungicides were evaluated to manage the QoI and/or DMI resistant C. beticola isolates in a sensitivity study and a greenhouse and field study. Copper-based multisite activity fungicides were evaluated for controlling fungicide resistant C. beticola. The mean EC50 values for nine copper-based chemicals ranged from 1 to 10 ug/ml using a spore germination assay. In a greenhouse study, Fertileader (a copper-based fertilizer) caused leaf injury and was not evaluated, but the other tested chemicals provided significantly better control of CLS compared to the control check with Badge X2, Champion, Cuprofix, COCS and Ridomil having significantly small AUDPC. Newer site specific fungicides with different modes of action that have never been used for CLS management in North Dakota and Minnesota were also tested. The mean EC50 values were 4.9, 33.1, 99.4, and 481.6 ug/ml using mycelial growth assay and 5.7, 4.1, 9.2, and 4.2 ug/ml using spore germination assay for cyprodinil, fluazinam, pydiflumetofen, and Chlorothalonil, respectively. In a two-year field study, all the fungicides resulted in significantly better disease control, significantly higher beet tonnage, and recovered sucrose compared to the nontreated check. However, none of tested fungicide treatments performed better than the industry?s standard fungicide, triphenyltin hydroxide.
2

Intercultural experiential learning through international internships: the case of medical education

Rychener, Melissa Anne 29 September 2004 (has links)
No description available.
3

Assessing orientations to cultural difference of the faculty of a university foundation programme in the Gulf Cooperation Council : a mixed-methods approach informed by the Intercultural Development Continuum and using the Intercultural Development Inventory

McKay, Ian Ross January 2013 (has links)
This study examined the orientations to cultural difference of sojourner educators in the Foundation Program at Qatar University to determine if orientations were correlated with select demographic and experiential variables, including gender, age, time overseas, education level, formative region, ethnic minority status, job position, length of time in Qatar, intercultural marriage, default language, formal teacher training, and overseas development organization experience. This study used a sequential mixed-method design. Perceived and Developmental Orientations were measured using the Intercultural Development Inventory© (V.3), which produced a measure of each respondent’s orientation to cultural difference. Focus group interviews were conducted to engage participants in explaining and interpreting the findings. Five focus groups of three to six participants each were conducted. Most of the teachers were found to operate from within the transitional orientation of Minimization, although individual scores ranged from Denial to Adaptation. On average, the educators were found to overestimate their orientations by 31 points. A positive correlation between orientation and formative region was found, with participants from North America showing the highest orientation. Statistically significant differences emerged for orientations when comparing Middle East and North African (MENA) and North American formative regions. Formative region was found to account for 4.8% of the variance in orientation and is a significant fit of the data. Focus groups participants speculated that (a) core differences regarding multiculturalism in MENA and North American cultures help explain the results, (b) aspects of the workplace culture and both the broader MENA and local Qatari culture encourage a sense of exclusion, and (c) external events further complicate cross-cultural relations. The study findings add to the literature by providing baseline orientation data on sojourner educators in post-secondary education in the GCC region, and by confirming some of the findings of similar studies. The study provides practitioners with suggestions for staffing and professional development. Future research should focus on the measurement of orientations in broader samples of educators, changes in orientation over time in Qatar and other cultural contexts, differences in orientation among short-term vs. long-term expatriates, the impact of employment systems and societal structures on orientations in sojourner educators, the impact of educator orientation to cultural difference on student achievement, and the design of effective cross-cultural professional development for educators.
4

Flexible machine tool control for direct, in-process dimensional part inspection

Davis, Tyler Addison 08 July 2004 (has links) (PDF)
For some time now coordinate measuring machines have been an integral part of the shop floor. The goal has been to make coordinate measuring machines (CMMs) into tools that can easily be used by machinists to improve their manufacturing capabilities. The value of a CMM as a quality control tool is undisputed. Now efforts are being made to further reduce the time and cost of measurement by reducing the physical distance between machining and measuring processes. The ability to reduce that distance to zero and measure a part directly on the chip-making machine has been a goal for many years. Dimensional inspection of parts is primarily conducted by coordinate measuring machines operating on motion instructions from task planning software. The research in direct machining and control (DMAC) at BYU has identified a potential application of CMM technologies on existing machine tools. To prove that a machine tool can be controlled as a CMM with the DMAC controller, this research will integrate the software package PC-DMIS provided by Wilcox Associates, Inc. with a DMAC controller provided by Direct Controls, Inc. to conduct in-process dimensional inspection of parts as they are being machined. This process is referred to as DirectCMM because it will link the DMAC controller directly to PC-DMIS without need for post-processing. This thesis will lay the groundwork for future efforts at developing systems that utilize in-process part inspection to dynamically correct computer aided manufacturing (CAM) process plans. To aid future efforts at dynamic CAM process updating, a software interface specification will be created for passing measurement data between CMM and CAD/CAM software packages. A CMM control specification will also be created to provide a standard method for controlling coordinate measuring machines with the DMAC controller. Possible methods for dynamic CAD/CAM updating will be explored.

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