University of Oklahoma

About: University of Oklahoma is a education organization based out in Norman, Oklahoma, United States. It is known for research contribution in the topics: Population & Radar. The organization has 25269 authors who have published 52609 publications receiving 1821706 citations. The organization is also known as: OU & Oklahoma University.

Carbon-Nitrogen Interactions in Terrestrial Ecosystems in Response to Rising Atmospheric Carbon Dioxide

Abstract: Interactions involving carbon (C) and nitrogen (N) likely modulate terrestrial ecosystem responses to elevated atmospheric carbon dioxide (CO2) levels at scales from the leaf to the globe and from the second to the century. In particular, response to elevated CO2 may generally be smaller at low relative to high soil N supply and, in turn, elevated CO2 may influence soil N processes that regulate N availability to plants. Such responses could constrain the capacity of terrestrial ecosystems to acquire and store C under rising elevated CO2 levels. This review highlights the theory and empirical evidence behind these potential interactions. We address effects on photosynthesis, primary production, biogeochemistry, trophic interactions, and interactions with other resources and environmental factors, focusing as much as possible on evidence from long-term field experiments.

Assessment of QT interval and QT dispersion for prediction of all-cause and cardiovascular mortality in American Indians: The Strong Heart Study.

Abstract: Background—Both a prolonged QT interval and increased QT interval dispersion (QTD) have been proposed as surface ECG markers of vulnerability to ventricular arrhythmias and potential predictors of ...

Unification of Luminous Type 1 Quasars through CIV Emission

Abstract: Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of properties exhibited by high-ionization, broad emission lines, such as CIV 1549. Specifically we investigate the anti-correlation between L_UV and emission line EQW (the Baldwin Effect) and the "blueshifting" of high-ionization emission lines. The blueshift of the CIV emission line is nearly ubiquitous, with a mean shift of 810 km/s for radio-quiet (RQ) quasars and 360 km/s for radio-loud (RL) quasars, and the Baldwin Effect is present in both RQ and RL samples. Composite spectra are constructed as a function of CIV emission line properties in attempt to reveal empirical relationships between different line species and the SED. Within a two-component disk+wind model of the broad emission line region (BELR), where the wind filters the continuum seen by the disk component, we find that RL quasars are consistent with being dominated by the disk component, while BALQSOs are consistent with being dominated by the wind component. Some RQ objects have emission line features similar to RL quasars; they may simply have insufficient black hole (BH) spin to form radio jets. Our results suggest that there could be significant systematic errors in the determination of L_bol and BH mass that make it difficult to place these findings in a more physical context. However, it is possible to classify quasars in a paradigm where the diversity of BELR parameters are due to differences in an accretion disk wind between quasars (and over time); these differences are underlain primarily by the SED, which ultimately must be tied to BH mass and accretion rate.

Identification and Functional Analysis of in Vivo Phosphorylation Sites of the Arabidopsis BRASSINOSTEROID-INSENSITIVE1 Receptor Kinase

Abstract: Brassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID-INSENSITIVE1 (BRI1) and BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1) for hormone perception and signal transduction. Many animal receptor kinases exhibit ligand-dependent oligomerization followed by autophosphorylation and activation of the intracellular kinase domain. To determine if early events in BR signaling share this mechanism, we used coimmunoprecipitation of epitope-tagged proteins to show that in vivo association of BRI1 and BAK1 was affected by endogenous and exogenous BR levels and that phosphorylation of both BRI1 and BAK1 on Thr residues was BR dependent. Immunoprecipitation of epitope-tagged BRI1 from Arabidopsis thaliana followed by liquid chromatography–tandem mass spectrometry (LC/MS/MS) identified S-838, S-858, T-872, and T-880 in the juxtamembrane region, T-982 in the kinase domain, and S-1168 in C-terminal region as in vivo phosphorylation sites of BRI1. MS analysis also strongly suggested that an additional two residues in the juxtamembrane region and three sites in the activation loop of kinase subdomain VII/VIII were phosphorylated in vivo. We also identified four specific BAK1 autophosphorylation sites in vitro using LC/MS/MS. Site-directed mutagenesis of identified and predicted BRI1 phosphorylation sites revealed that the highly conserved activation loop residue T-1049 and either S-1044 or T-1045 were essential for kinase function in vitro and normal BRI1 signaling in planta. Mutations in the juxtamembrane or C-terminal regions had only small observable effects on autophosphorylation and in planta signaling but dramatically affected phosphorylation of a peptide substrate in vitro. These findings are consistent with many aspects of the animal receptor kinase model in which ligand-dependent autophosphorylation of the activation loop generates a functional kinase, whereas phosphorylation of noncatalytic intracellular domains is required for recognition and/or phosphorylation of downstream substrates.