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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.
271

Root dynamics and carbon accumulation of six willow clones in Saskatchewan

Stadnyk, Christine Noelle 09 August 2010
Short rotation woody crops have gained global interest as an alternative energy source to fossil fuels. The availability of this resource is, however, dependent on successful research trials and the identification and quantification of the environmental controls on rapid growth. Knowledge of willow root dynamics is required to determine belowground and aboveground growth relationships, and to provide valuable inputs for the development of a willow carbon model. The objectives of this study were to 1) determine fine root turnover, biomass, and productivity of six willow clones over two growing seasons at four locations in Saskatchewan using the minirhizotron method; 2) determine fine root biomass and fine root carbon sequestration of six willow clones over one growing season at four locations in Saskatchewan using the soil coring method; and 3) determine lateral coarse root structure of six willow clones at two locations in Saskatchewan.<p> Monthly fine root biomass and production was estimated for six willow clones in Saskatoon, Saskatchewan using repeated minirhizotron observations from May to September of 2008 and 2009. Fine root biomass increased from 0.78 Mg ha-1 in May 2008 to 25.75 Mg ha-1 in September 2009. Significant differences were seen between months throughout each growing season, but not between the clones. Mean monthly productivity reached its peak of 8.00 Mg ha-1 in July 2009. Mean turnover for all the clones was 0.96 yr-1 and mean longevity was 1.04 yr-1. The high fine root biomass estimates determined by the minirhizotron method in Saskatoon suggest that this method is not suitable for use in a Vertisolic soil. There was no significant effect of clone on fine root productivity, biomass, turnover or longevity (P < 0.05).<p> Fine root biomass estimates from the soil cores were lower than those from the minirhizotron method. The mean fine root biomass value in Saskatoon for September 2008 was 0.298 Mg ha-1. Mean fine root biomass at each site from September 2007 to September 2008 ranged from 0.022 Mg ha-1 to 0.915 Mg ha-1. Mean root carbon content ranged from 0.010 to 0.426 Mg C ha-1. Fine root biomass and root carbon content were significantly different between each site, with the exception of Saskatoon and Estevan (P < 0.05). Differences in fine root estimates between the sites are suggested to be a function of the soil texture and moisture accessibility at each site. This research indicates that willow roots in Saskatchewan find initial establishment difficult in low moisture, fine textured soils. Also, approximately 44.6 % of fine root biomass is comprised of C, and decomposes to form soil organic matter. Therefore, fine roots have potential to store substantial amounts of carbon if growing conditions are suitable.
272

Root dynamics and carbon accumulation of six willow clones in Saskatchewan

Stadnyk, Christine Noelle 09 August 2010 (has links)
Short rotation woody crops have gained global interest as an alternative energy source to fossil fuels. The availability of this resource is, however, dependent on successful research trials and the identification and quantification of the environmental controls on rapid growth. Knowledge of willow root dynamics is required to determine belowground and aboveground growth relationships, and to provide valuable inputs for the development of a willow carbon model. The objectives of this study were to 1) determine fine root turnover, biomass, and productivity of six willow clones over two growing seasons at four locations in Saskatchewan using the minirhizotron method; 2) determine fine root biomass and fine root carbon sequestration of six willow clones over one growing season at four locations in Saskatchewan using the soil coring method; and 3) determine lateral coarse root structure of six willow clones at two locations in Saskatchewan.<p> Monthly fine root biomass and production was estimated for six willow clones in Saskatoon, Saskatchewan using repeated minirhizotron observations from May to September of 2008 and 2009. Fine root biomass increased from 0.78 Mg ha-1 in May 2008 to 25.75 Mg ha-1 in September 2009. Significant differences were seen between months throughout each growing season, but not between the clones. Mean monthly productivity reached its peak of 8.00 Mg ha-1 in July 2009. Mean turnover for all the clones was 0.96 yr-1 and mean longevity was 1.04 yr-1. The high fine root biomass estimates determined by the minirhizotron method in Saskatoon suggest that this method is not suitable for use in a Vertisolic soil. There was no significant effect of clone on fine root productivity, biomass, turnover or longevity (P < 0.05).<p> Fine root biomass estimates from the soil cores were lower than those from the minirhizotron method. The mean fine root biomass value in Saskatoon for September 2008 was 0.298 Mg ha-1. Mean fine root biomass at each site from September 2007 to September 2008 ranged from 0.022 Mg ha-1 to 0.915 Mg ha-1. Mean root carbon content ranged from 0.010 to 0.426 Mg C ha-1. Fine root biomass and root carbon content were significantly different between each site, with the exception of Saskatoon and Estevan (P < 0.05). Differences in fine root estimates between the sites are suggested to be a function of the soil texture and moisture accessibility at each site. This research indicates that willow roots in Saskatchewan find initial establishment difficult in low moisture, fine textured soils. Also, approximately 44.6 % of fine root biomass is comprised of C, and decomposes to form soil organic matter. Therefore, fine roots have potential to store substantial amounts of carbon if growing conditions are suitable.
273

Chinese Americans in China: Ethnicity, Transnationalism, and Roots Tourism

Ueda (Maruyama), Naho 2009 May 1900 (has links)
In the era of advanced communication and transportation technology, immigrants and their descendents can be reunited with their ancestral land from where they or their forebears once were displaced. Visiting the ancestral land as tourists, or "roots tourism," is a major and easily accessible means through which people can recreate and retain the social ties with their ancestral communities. Roots tourism is loosely defined as a type of tourism in which ethnic minorities visit their ancestral lands to discover ethnic roots and culture. Despite the recent popularity of this type of tourism, many gaps remain in the research of roots tourism especially about its influence on ones' identity and sense of home among second generation of immigrants. Therefore, the purpose of this dissertation is to explore the experiences of visiting ancestral land among second generation immigrants. For the purpose of this study, I focus on experiences of roots tourism among Chinese Americans. By investigating their motivation to visit their ancestral land, experiences and encounters in their ancestral land, and feelings toward the ancestral land and toward the United States after the visit, I attempt to explore how roots tourism influences ways in which second generation define and redefine who they are and where they belong under the transnationalism. Face-to-face, in-depth interviews with forty Chinese Americans revealed that, contrary to the idea that roots tourism generates strong feelings of belonging to one's ancestral land, a majority of the interviewees in this study felt foreign in their ancestral land. Although they felt a certain sense of connection to China or Taiwan, the feeling was overwhelmed by the differences in language, norms, class, culture, upbringing, citizenship, and family and gender composition. Analysis indicated that among forty interviewees, only three interviewees felt a sense of belonging to their ancestral society after their visit, and the rest of the interviewees realized their home is the United States. This study revealed the limitation of roots tourism as a tool to foster an identity and sense of home attached to the tourists' ancestral land. At the same time, the findings also suggest that roots tourism played a significant role to assist the interviewees to develop a positive sense of being Chinese Americans.
274

Re-examining the Permanent Income Hypothesis by Stochastic Cointegration¡Xthe Evidence from Taiwan Data

Liu, Kai-Chi 15 July 2005 (has links)
Keynes (1936) first brought up the relationship between consumption and national income, but Kuznets¡¦observation about the U.S. data was not supported by the Keynes consumption function form. So there are many macroeconomic theories trying to explain the phenomenon observed by Kuznets. This paper uses the way developed by Campbell (1987) to test the permanent income hypothesis suggested by Friedman with Taiwan data. In addition, this paper uses the stochastic cointegration developed by Harris, McCabe, and Leybourne (2002) to re-examine the relationship between consum-ption and national income because the traditional non-stochastic cointegration assumes that the error term is linear and homogeneous, which may be too strong to fit the real world. Besides, this paper compares the nonstochastic cointegration with the stochastic cointegration, and the evidence founded is that the permanent income hypothesis is not supported by Taiwan data with these two methods.
275

Dynamic Intervertebral Foramen Narrowing During Whiplash

Maak, Travis Gardner 15 November 2006 (has links)
A biomechanical study of intervertebral foraminal narrowing during simulated automotive head-forward and head-turned rear impacts. The objective of this study was to quantify foraminal width, height and area narrowing during head-forward and head-turned rear impacts, and evaluate the potential for nerve root and ganglion impingement. Muscle weakness and paresthesias, documented in whiplash patients, have been associated with neural compression within the cervical intervertebral foramen. Rotated head posture at the time of rear impact has been correlated with increased frequency and severity of chronic radicular symptoms, as compared to facing forward. No studies have quantified dynamic changes in foramen dimensions during head-forward or head-turned rear impacts. Six whole cervical spine specimens with muscle force replication and surrogate head underwent simulated whiplash at 3.5, 5, 6.5 and 8 g, following non-injurious baseline 2 g acceleration. Continuous dynamic foraminal width, height and area narrowing were recorded, and the peaks were determined during each impact and statistically compared to baseline narrowing. During head-forward rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline were observed at C5-C6 beginning with 3.5 g impact. No significant increases in average peak foraminal height narrowing were observed, while average peak foraminal areas were significantly narrower than baseline at C4-C5 at 3.5, 5 and 6.5 g. During head-turned rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline of up to 1.8 mm in the left C5-C6 foramen at 8 g were observed. Average peak dynamic foraminal height was significantly narrower than baseline at right C2-C3 foramen at 5 g and 6.5 g, while no significant increases in foraminal area were observed. Extrapolation of the present head-forward rear impact results indicated that the greatest potential for ganglia compression injury was at the lower cervical spine, C5-C6 and C6-C7. The present head-turned rear impact results indicated that the greatest potential ganglia compression injury exists at C5-C6 and C6-C7. Greater potential for ganglia compression injury exists at C3-C4 and C4-C5 due to head-turned rear impact, as compared to head-forward rear impact. Acute ganglia compression may produce a sensitized neural response to repeat compression leading to chronic radiculopathy following head-forward and head-turned rear impacts. Dynamic ganglion or nerve root compression may also lead to chronic radiculopathy.
276

The GIST model for selection and modification of scientific research for the college teaching laboratory based on root competition investigations

Elliott, Shannon Snyder. January 2007 (has links)
Thesis (Ed.D.)--University of West Florida, 2007. / Title from title page of source document. Document formatted into pages; contains 252 pages. Includes bibliographical references.
277

Sur les propriétés générales des racines d'équations synectiques

Méray, Charles January 1900 (has links)
Thèse de doctorat : Sciences mathématiques : Paris, Faculté des sciences : 1858. / Titre provenant de l'écran-titre.
278

Cell production, expansion and the role of auxin in the response of the root of Arabidopsis thaliana exposed to water deficit /

Van der Weele, Cornelia Maria, January 2001 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.
279

Cell production, expansion and the role of auxin in the response of the root of Arabidopsis thaliana exposed to water deficit

Van der Weele, Cornelia Maria, January 2001 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.
280

Sur les propriétés générales des racines d'équations synectiques

Méray, Charles, January 1858 (has links)
Thèse--Paris.

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