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Differential Responses of Dinitrogen Fixation, Diazotrophic Cyanobacteria, and Ammonia Oxidation Reveal a Potential Warming-Induced Imbalance of the N-Cycle in Biological Soil Crusts

Description

N2 fixation and ammonia oxidation (AO) are the two most important processes in the nitrogen (N) cycle of biological soil crusts (BSCs). We studied the short-term response of acetylene reduction assay (ARA) rates, an indicator of potential N2 fixation, and

N2 fixation and ammonia oxidation (AO) are the two most important processes in the nitrogen (N) cycle of biological soil crusts (BSCs). We studied the short-term response of acetylene reduction assay (ARA) rates, an indicator of potential N2 fixation, and AO rates to temperature (T, -5°C to 35°C) in BSC of different successional stages along the BSC ecological succession and geographic origin (hot Chihuahuan and cooler Great Basin deserts). ARA in all BSCs increased with T until saturation occurred between 15 and 20°C, and declined at 30–35°C. Culture studies using cyanobacteria isolated from these crusts indicated that the saturating effect was traceable to their inability to grow well diazotrophically within the high temperature range. Below saturation, temperature response was exponential, with Q10 significantly different in the two areas (~ 5 for Great Basin BSCs; 2–3 for Chihuahuan BSCs), but similar between the two successional stages. However, in contrast to ARA, AO showed a steady increase to 30–35°C in Great Basin, and Chihuhuan BSCs showed no inhibition at any tested temperature. The T response of AO also differed significantly between Great Basin (Q10 of 4.5–4.8) and Chihuahuan (Q10 of 2.4–2.6) BSCs, but not between successional stages. Response of ARA rates to T did not differ from that of AO in either desert. Thus, while both processes scaled to T in unison until 20°C, they separated to an increasing degree at higher temperature. As future warming is likely to occur in the regions where BSCs are often the dominant living cover, this predicted decoupling is expected to result in higher proportion of nitrates in soil relative to ammonium. As nitrate is more easily lost as leachate or to be reduced to gaseous forms, this could mean a depletion of soil N over large landscapes globally.

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2016-10-24

Japanese-American Internment Camp Collection

Description

A presentation describing technical work, community reaction and publicity associated with an online collection of Arizona Japanese-American internment camp newsletters and related archival materials developed in 2017. The presentation was given at the Arizona Library Association conference in October 2017

A presentation describing technical work, community reaction and publicity associated with an online collection of Arizona Japanese-American internment camp newsletters and related archival materials developed in 2017. The presentation was given at the Arizona Library Association conference in October 2017 and this revised version was presented at the Arizona Archives Summit on February 1, 2018.

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2018-01-18

Phoenix Annexation Workshop

Description

Materials produced for the workshop hosted by the Humane Cities Initiative, Institute for Humanities Research, Arizona State University. Participants were sent this package of archival materials and links to brief online sources for advance readings. Also enclosed are PDF renderings

Materials produced for the workshop hosted by the Humane Cities Initiative, Institute for Humanities Research, Arizona State University. Participants were sent this package of archival materials and links to brief online sources for advance readings. Also enclosed are PDF renderings of introductory powerpoint files by Spindler and Pagan, and an audio recording of the discussion joined in progress.

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2018-03-13

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ASU in the Postwar Period: Victory Village

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Presentation slides regarding the history of Victory Village, the trailer park built in 1945-46 to provide housing for WWII Veterans and their families at Arizona State University's Tempe campus. A presentation of research from University Archives records conducted in the

Presentation slides regarding the history of Victory Village, the trailer park built in 1945-46 to provide housing for WWII Veterans and their families at Arizona State University's Tempe campus. A presentation of research from University Archives records conducted in the summer of 2018. The presentation was videotaped as a lecture for Professor Volker Benkert's online World War II history class.

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2019-09-30

In Search of Strategic Direction: Digital Preservation in the Academy

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Video recording of the NHPRC Electronic Records Fellowship Symposium keynote address, University of North Carolina at Chapel Hill, November 18, 2005.

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2005-11-18

ROTC Building Occupation at ASU, April 23-25, 1969

Description

Historical research produced for a portion of the exhibit entitled Civil Rights in Arizona, which was displayed at the Luhrs Gallery, Hayden Library in 2012-2013. The action at the ROTC Building was one of the largest protests in Arizona State

Historical research produced for a portion of the exhibit entitled Civil Rights in Arizona, which was displayed at the Luhrs Gallery, Hayden Library in 2012-2013. The action at the ROTC Building was one of the largest protests in Arizona State University history, resulting in the arrest of ten individuals. The second file, entitled "Who Were the Tempe Ten?", describes the arrested students and unaffiliated persons.

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2012

Selling Sunshine: ASU Solar Energy Research 1951-1980

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Original exhibit panel text and an associated interview with ASU faculty Charles Backus and Harvey Bryan for the exhibit presented at the Luhrs Gallery, Hayden Library, Fall, 2013.

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2013-07-01