• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1470
  • 517
  • 492
  • 327
  • 219
  • 181
  • 144
  • 31
  • 30
  • 24
  • 23
  • 23
  • 18
  • 18
  • 17
  • Tagged with
  • 4188
  • 414
  • 395
  • 378
  • 367
  • 359
  • 354
  • 329
  • 315
  • 308
  • 304
  • 299
  • 293
  • 288
  • 287
  • 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.
431

Loblolly Pine (Pinus taeda L.) Plantation Response to Mechanical Site Preparation in the South Carolina and Georgia Piedmont

Cerchiaro, Michael Paul 16 March 2004 (has links)
Site preparation is fundamental for establishing loblolly pine (Pinus taeda L.) plantations, but long-term sustainability of plantations established using mechanical treatments is in question because of concerns regarding soil tillage and the removal of harvest residue and soil organic matter. A study was installed in 1981 on 12 locations in northeastern Georgia and west-central South Carolina to evaluate pine plantation response to mechanical site preparation. Site preparation treatments induced gradients of organic matter manipulation and soil tillage. The treatments included: Control, Chop/Burn, Shear/Disc, Shear/V-Blade, Shear/Rake, and Shear/Rake/Pile. Research was conducted to address the following objectives: (i) compare rotation-age forest response to several intensive site preparation treatments used to establish pine plantations in the Piedmont of the southeastern United States; (ii) correlate growth response with the gradients of soil organic matter removal, soil tillage, and hardwood control; (iii) determine the influence of intensive management on the amount of carbon contained in pine plantations. All site preparation treatments increased year-18 volume accumulation compared to the control treatment. Chop/Burn and Shear/Disc treatments, with pine volumes of 214 m3 ha-1 and 232 m3 ha-1, respectively, conserved harvest residue and out-performed the Shear/Rake treatment (191 m3 ha-1), which completely removed harvest residue. Treatments that included tillage provided growth benefits that lasted throughout the rotation even when tillage was accompanied by complete organic matter removal. Hardwood competition had the greatest influence on pine volume accumulation, explaining over 54% of the variation in pine growth at age 18. Treatments that included tillage most effectively controlled hardwood competition. At year 18, site preparation treatments significantly affected soil organic matter (SOM) content; however, soil nitrogen, foliar nitrogen, bulk density, and macroporosity were not affected by site preparation. All treatments were equally deficient in foliar nitrogen. The Shear/Disc and Shear/Rake/Disc treatments had a significantly positive relationship between foliar nitrogen and pine volume. These treatments had lower hardwood basal areas (below 15%), indicating that once hardwoods were controlled, nitrogen became limiting to pine growth. Using pre-harvest characterization data, carbon accumulation during old-field succession increased fourfold compared to agricultural sites on the nearby Calhoun Experimental Forest. Carbon accumulation on these old-field loblolly pine sites reached quasi-equilibrium after 40 years as shown by uncut reference stands. Site preparation significantly affected the amount of soil C in the upper 20 cm of the soil. Those site preparation treatments that removed harvest residue and accelerated SOM decomposition through tillage had the lowest soil carbon levels. The Shear/Rake/Disc treatment had 10% lower soil carbon content than the Control and Shear/V-Blade treatments. / Master of Science
432

Design and Evaluation of a Mobile Instrumentation Platform for Unmanned Vehicle Testing

Gombar, Brett Anthony 28 July 2006 (has links)
Unmanned vehicle systems are becoming more important in the future of the military and in commercial applications. These systems are used to prevent humans from entering dangerous situations or to automate dull tasks. In order to facilitate rapid development of these systems, testing procedures and infrastructure need to be created. Once developed, the performance characteristics of unmanned vehicle systems can be determined and compared to similar systems. This information will be beneficial to system developers and potential customers. In order to provide the infrastructure and test procedures to the unmanned systems community, the Joint Robotics Program created the National Unmanned Systems Experimentation Environment (NUSE2). NUSE2 consists of a variety of military organizations and academic resources, including the Joint Unmanned Systems Test Experimentation and Research (JOUSTER) site at Virginia Tech. JOUSTER was tasked specifically with creating a mobile instrumentation platform capable of providing wireless communications, data collection, and video coverage of a testing site. This thesis presents the system designed and created to meet this need. For the first time, a mobile instrumentation platform has been created to specifically support unmanned systems research. Additionally, the performance characteristics of this system have been fully evaluated and will serve as a benchmark for future improvements to the system. / Master of Science
433

Présence du système de recombinaison spécifique de site Xer chez des espèces du groupe des bactéries lactiques

Teijeiro, Shona 02 1900 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal. / Chez les procaryotes, la réplication du chromosome peut entraîner la dimérisation des deux nouveaux chromosomes par recombinaison homologue. La fréquence de ce phénomène est particulièrement élevée dans la région du terminus de réplication du chromosome de E. coli, notamment aux sites Hot et TTiZ. Si le dimère chromosomique n'est pas résolu avant la partition dans les cellules-filles, il y aura filamentation cellulaire et aberration chromosomique. Pour contrer ce phénomène, E. coli a mis en place un système de résolution de dimères, soit le système de recombinaison spécifique de site Xer. Chez E. coli, ce système comprend les recombinases XerC et XerD et le site chromosomique dif situé dans la région du terminus de réplication. Les recombinases s'arriment d'abord aux sites dif des chromosomes formant le dimère, puis il y a coupure et échange des brins libérant ainsi les chromosomes à leurs formes monomères. La répartition de ce système de résolution de dimères est assez bien documentée parmi les bactéries Gram négatives. Cependant, peu d'études se sont penchées sur les bactéries Gram positives. Le but de notre étude est de détecter la présence de ce système chez treize espèces de bactéries Gram positives du groupe des bactéries lactiques, certaines étant très importantes dans l'industrie alimentaire. Plusieurs techniques ont été employées, dont l'hybridation Southern, l'amplification génique avec amorces dégénérées issues des séquences des recombinases déjà connues, l'amplification génique dite "inverse", ainsi que le séquençage. Nous avons également utilisé un programme informatique afin de dégager la phylogénie et les ressemblances entre les recombinases de Gram positives et entre celles-ci et les recombinases déjà connues des bactéries Gram négatives. Par hybridation Southern, nous avons réussi à démontrer la présence d'un site analogue au site dif de E. coli chez Lactobacillus casei. De plus, l'amplification génique avec amorces dégénérées a montré que cette dernière espèce ainsi que les espèces Lactobacillus plantarum souche 8014, Lactobacillus plantarum souche 14917 et Lactobacillus bulgaricus 737 possèdent toutes au moins une recombinase de type Xer. Nous n'avons pas obtenu de séquences pour les autres espèces de bactéries, peut-être à cause d'un manque d'homologie entre les amorces et l'ADN ciblé. Les régions amplifiées de ces quatre souches, correspondant à environ 430 pb du bout C-terminal de la recombinase, ont été séquencées, puis des amorces ont été fabriquées à partir de la séquence de L. casei. Ces amorces devaient amplifier les régions flanquant la séquence connue (amplification "inverse"), permettant ainsi d'obtenir une séquence complète du gène. Nous n'avons pas obtenu de résultats avec cette technique, peut-être à cause de la formation de boucles C-G dans l'ADN simple-brin lors de certains cycles de l'amplification. Les quatre séquences ont ensuite été comparées et une phylogénie a été établie. Nous avons trouvé que ces séquences formaient un groupe phylogénique fortement apparenté et qu'elles ressemblaient le plus aux séquences XerD des bactéries Gram négatives, ces dernières ressemblances surpassant même celles avec la recombinase XerD de la bactérie Gram positive B. subtilis. Ces derniers résultats suggèrent la possibilité d'une évolution différente des recombinases XerD à l'intérieur du groupe des Gram positives que nous avons examiné.
434

The bench deposits at Berger Bluff : Early Holocene-Late Pleistocene depositional and climatic history

Brown, Kenneth M. 12 August 2011 (has links)
Not available / text
435

Establishment of concentration ratios for riparian and shrub steppe areas of the eastern Washington Columbia basin

Napier, Jonathan Bamberger 12 September 2012 (has links)
Concentration ratios are used to determine the transfer of nuclides from soil to biota to fauna. Some nuclides have limited associated data though, this has not prevented predictions from being performed at sites without associated data. These ratios are site specific and are not fully applicable when applied to other locations. A recent literature review for a waste repository performance assessment determined that a significant portion of the environmental data was based on recursively published material. To address this deficiency neutron activation analysis (NAA) was used to determine concentration ratios of certain biota. Three sites, two riparian and one shrub steppe, were sampled in the eastern Washington Columbia basin, near the Hanford site. Two hundred and fifty eight samples of opportunity were collected. This included 15 soil samples, 10 water and sediment samples, 40 different species of biota, and 2 terrestrial animal species and 3 aquatic animal species. These samples were prepared for NAA by drying, weighing, and in certain cases ashing to improve detection efficiency. After activation, the samples were placed in a HPGe detector to perform spectral analysis. The concentration results of 26 elements of interest are presented, along with newly established concentration ratios for all of the species sampled. / Graduation date: 2013
436

A Proposed Methodology For Predicting The Carbon And Nitrogen Stable Isotope Measures Of K'inich Yax K'uk Mo', Copan Dynastic Founder

Edwards, Keith 01 January 2011 (has links)
The purpose of this thesis is to show that stable isotope analysis can be used to predict K’inich Yax K’uk Mo’s stable isotope measures based on Stuart’s (2007) hypothesis that K’inich Yax K’uk Mo’, the dynastic founder of the Copan royal lineage, was a Caracol lord. There is significant and convincing evidence that K’inich Yak K’uk Mo’ had a non-Copanec origin. Stable isotope analysis is a tested and reliable method for detailing diets and migratory paths of ancient humans and this theory is applied as a predictor of the stable isotope measures of K’inich Yax K’uk Mo’, if he did in fact originate in Caracol. The literature is rich with explanations of stable isotopes and the writings of a few stalwarts in the field were utilized to gain an understanding of the associated technologies and techniques utilized in its analysis. Data from the Copan (Whittington and Reed 1997) and Caracol (Chase and Chase 2001) stable isotope studies were utilized to show the application of stable isotope analysis in areas “associated” with K’inich Yax K’uk Mo’ and to illustrate how the palace diet identified by Chase and Chase (2001; Chase et al. 2001) could be aligned with the Stuart hypothesis to predict the stable isotope ranges for K’inich Yax K’uk Mo’.
437

三重県粥見井尻,筋違,内垣外遺跡から得られた14C年代値とその意義

Oku, Yoshiji, Kawasaki, Shino, Hondo, Hiroyuki, Nakamura, Toshio, Mori, Yuichi, 中村, 俊夫, 奥, 義次, 川崎, 志乃, 本堂, 弘之, 森, 勇一 03 1900 (has links)
名古屋大学年代測定総合研究センターシンポジウム報告
438

Skadeplatsarbete : Ambulanssjuksköterskors upplevelser från skadeplatsarbete / Working at the trauma scene : Ambulance nurses experiences from working at the trauma scene

Gudmundsson, Magnus, Rosén, Martin January 2010 (has links)
<p><strong>Syfte:</strong> Syftet med denna studie var att undersöka ambulanssjuksköterskors upplevelser av arbete på skadeplats med en till fyra drabbade personer. <strong>Metod:</strong> Fyra män och fyra kvinnor, med en erfarenhet mellan två och elva år av ambulanssjukvård, deltog i studien. Semistrukturerade intervjuer genomfördes och data analyserades med innehållsanalys. <strong>Resultat:</strong> Sju kategorier identifierades: Kommunikation, Ledarskap, Medicinskt omhändertagande, Rutiner och riktlinjer, Organisation, Personlighet och relationer, samt Samverkan. Skadeplatsarbetet sker utanför sjukhusets kontrollerade verksamhet. Att varje gång anpassa sig till situationen, omhänderta, leda och organisera arbetet är det som krävs av en ambulanssjuksköterska. Samtidigt ställs stora krav på den omkringliggande organisationen inklusive alla övriga resurser, på att kunna samarbeta och fungera som grupp.<strong> Slutsats:</strong> Skadeplatsarbetet kräver en organisation som måste fungera i minsta detalj och samtidigt alltid förbättra sig. Då många av de upplevda problemen ansågs bero på personlighet och relationer så kräver det dessutom att personalen är stresstålig, ödmjuk, social, kreativ och noggrann.</p> / <p><strong>Aim:</strong> The aim with this study was to analyze the ambulance nurses experiences from working at the trauma scene, with up to four injured patients. <strong>Method:</strong> four men and four women, with a two to eleven years time of experience in the ambulance service, participated. Data from qualitative interviews were analyzed with content analysis. <strong>Result:</strong> Seven categories were identified: Communication, Leadership, Medical treatment, Routines and guidelines, Organization, Personalities and relations, and finally Cooperation. An ambulance nurse needs to be able to adapt to any given situation. To nurse and treat, to lead and organize the activity at the trauma scene, is some things that could be asked from the nurse. A great requirement is also put on the surrounding organization, including all other resources, to cooperate and to function as a team. <strong>Conclusion:</strong> Professional work at the trauma scene demands an organization that needs to function in any unique situation. At the same time it’s just as important that this organization continuously improves. Experiences from problems in prehospital work could be related to personalities and relations between colleagues. This shows the importance of personnel that can handle stress, show humbleness, empathy and skills of being creative, social and precise.</p>
439

The Umpqua Eden site : the people, their smoking pipes and tobacco cultivation

Nelson, Nancy J. (Nancy Jo) 04 May 2000 (has links)
Located on the central Oregon coast, the Umpqua Eden site (35D083) yielded an artifact assemblage which is one of the five largest assemblages from the Oregon coast. The first aspect of the site that I looked at is the people who lived at the site, the ancestors of the Confederated Tribes of the Coos, Lower Umpqua and Siuslaw. In turn, I consulted with Patty Whereat, the Cultural Resources Director for the tribes, which resulted in a more holistic view of the site. Additionally, I attempted to uncover possible women's and men's activity areas of the Umpqua Eden site. A wealth of information on the native peoples of the Oregon coast was discovered, revealing that the sexual division of labor was not extremely rigid before Euro-American contact and the social category of "female" was expanded to more than two genders with consideration given to the two-spirited individual. I also attempted to engender the archaeological record by looking at the processes involved in the manufacture of smoking pipes and the cultivation of tobacco. During the ethnographic period, women were not smoking pipes; however, they were probably cultivating the tobacco and possibly gathering the clay for smoking pipes. I suggest that there was an agricultural element to the hunter-gatherer native populations of the central Oregon coast and challenge Western assumptions of individualism in precontact groups of the Oregon coast. I also provide a comparative analysis of clay, schist and steatite pipes of the Oregon coast. The smoking pipes are all straight and tubular (9% are shouldered) and the Umpqua Eden site pipes have the most artistic motifs. My analysis shows that the sandstone pipe dates to approximately 2,000 years ago and the clay smoking pipe may have replaced the sandstone pipe. Schist and steatite pipes were also used by the people of the Oregon coast and may have possibly been traded into the site from southern groups. Microscopic analysis of the pipes provided evidence that people were firing their clay pipes in a low temperature reducing atmosphere and using sand temper. In addition, I found a wide range of pipes being used on the Oregon coast given its relatively small geographic location. All of the this archaeological inquiry has helped in understanding the Umpqua Eden site and helped to give us a clearer picture of pre-contact Lower Umpqua life. / Graduation date: 2000
440

Paleoindian subsistence dynamics on the Northwestern Great Plains : zooarchaeology of the Agate Basin and Clary Ranch sites /

Hill, Matthew Glenn. January 2008 (has links)
Texte remanié de: Dissertation Ph. D.--Madison--University of Wisconsin, 2001. / Bibliogr. p. 107-121.

Page generated in 0.0841 seconds