Physical Sciences and Mathematics Commons^™

Diversity Of Methanogens And Other Archaea In Permanently Cold, Anoxic Marine Sediments, Melissa Mary Kendell

Dissertations and Theses

Little is known about the mechanism of methanogenic degradation of acetate or the fate of hydrogen and formate in cold marine sediments, or the ability of methanogens to grow and produce methane there. We used cultivation and molecular techniques to examine the microbes that produce methane from these substrates in permanently cold, anoxic marine sediments at Skan Bay, Alaska (57°N, 167°W, depth 65 m), at the Nankai Trough (32°21'N, 134°56'E, depth 247 m), and at Hydrate Ridge, Oregon (44°35'N, 125°10'W, depth 800 m). Most probable number (MPN) analyses were conducted for CO2-reducing, methylotrophic, and aceticlastic methanogens from Skan Bay and …

Mathematics, Meaning, And Identity : A Study Of The Practice Of Mathematics Education In A Rural High School, Rick Anderson

Dissertations and Theses

The purposes of this study were (1) to explore the relationship between mathematics education and the rural context and (2) to determine the usefulness of a social theory of learning (Wenger, 1998) to account for students' participation in advanced high school mathematics courses. Qualitative methods were used to gather data in a small, rural high school in the Pacific Northwest. Data gathered included a student survey, interviews with students and mathematics teachers, observations in mathematics classes, and documents related to the curriculum, the school, and the community.

The findings suggest that high school mathematics education is related to the rural …

First Season Effects Of Managed Flooding On The Invasive Species Phalaris Arundinacea L. And Shoreline Vegetation Communities In An Urban Wetland, Noah John Jenkins

Dissertations and Theses

Recent management efforts in the Smith and Bybee Lakes Wildlife Area (SBL), a 700-ha preserve in north Portland, Oregon, have included using a water control structure to suppress invasive reed canarygrass (Phalaris arundinacea L.) by flooding during spring and early summer growth periods. For the first year of managed flooding, I sought to determine: (a) the extent and distribution of reed canarygrass at SBL; (b) the effectiveness of the change in water level at suppressing reed canarygrass; and ( c) the effects of the change in water level on other plant species.

I established 30 vegetation transects throughout SBL …

A Tale Of Three Sisters: Reconstructing The Holocene Glacial History And Paleoclimate Record At Three Sisters Volcanoes, Oregon, United States, Shaun Andrew Marcott

Dissertations and Theses

At least four glacial stands occurred since 6.5 ka B.P. based on moraines located on the eastern flanks of the Three Sisters Volcanoes and the northern flanks of Broken Top Mountain in the Central Oregon Cascades. The youngest of these advances was the Little Ice Age (LIA) glaciation, which reached its maximum advance 150-200 yrs. B.P. and is defined by the large sharp crested and unvegetated moraines adjacent to the modern glaciers. In isolated locations less than 100 m downslope from these moraines, a second set of sparsely vegetated lateral moraines marks the Late-Neoglacial stand of the glaciers between 2.1 …