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.

Substrate regulation of soil respiration in a tallgrass prairie: Results of a clipping and shading experiment

Abstract: [1] Changes in soil respiration, one of the major fluxes of global carbon cycling, could significantly slow down or accelerate the increase in atmospheric CO2, with consequent feedbacks to climate change. It is critical to understand how substrate availability regulates soil respiration in projecting the response of carbon cycling to changed climate. We conducted a clipping and shading experiment for 1 year in a tallgrass prairie of the Great Plains, United States, to manipulate substrate supply to soil respiration. Our results showed that reduced substrate supply under clipping and/or shading significantly decreased soil respiration at all the timescales (diurnal, transient, and annual) irrespective of the minor concurrent changes in soil temperature and moisture. Annual mean soil respiration decreased significantly by 33, 23, and 43% for the clipping, shading, and clipping plus shading treatments, respectively. Temperature sensitivity of soil respiration decreased from 1.93 in the control plots to 1.88, 1.75, and 1.83 in the clipped, shaded, and clipped plus shaded plots, respectively. Rhizosphere respiration, respiration from decomposition of aboveground litter, and respiration from oxidation of soil organic matter and dead roots accounted for 30, 14, and 56% of annual mean soil respiration, respectively. Rhizosphere respiration was more sensitive to temperature than the other two components. Our results suggest a critical role of substrate supply in regulating soil respiration and its temperature sensitivity.

Turbulent blood flow in the ascending aorta of humans with normal and diseased aortic valves.

Abstract: Turbulent blood flow may contribute to a variety of pathophysiological effects Because of its postulated importance, this study was undertaken to determine whether turbulent flow does in fact occur in the human body In 15 persons (seven normal, seven aortic valvular disease, one prosthetic aortic valve), point velocity was measured in the ascending aorta with a hot-film anemometer probe In one normal individual with a high cardiac output, turbulent flow occurred above the aortic valve during peak flow which corresponded to a peak Reynolds number of 10,000 In the other six normal subjects (peak Reynolds numbers of 5,700-8,900), flow was highly disturbed during peak ejection Each of the subjects with aortic valvular disease and the subject with a prosthetic aortic valve showed turbulent flow during nearly the entire period of ejection, with Fourier components of velocity of significant magnitude up to 320 Hz (the maximum frequency we could evaluate with the equipment available) The turbulence energy density was higher in subjects with abnormal valves (32-146 ergs/cm3), than in normal subjects (06-29 ergs/cm3) In subjects with aortic stenosis, turbulence was observed throughout the ascending aorta and in the innominate artery In others, the turbulence dissipated more proximally The results of this study indicate that turbulent flow can occur in the ascending aorta of subjects with normal cardiac function; and it occurs consistently in the ascending aorta of individuals with abnormal aortic valves

The CLEO-II detector

Abstract: The new detector for data recording by the CLEO collaboration at the Cornell Electron Storage Ring is described. This detector has been designed to optimize studying e+ e− annihilation into hadronic matter at a total energy of 10 GeV. It consists of high precesion charged particle tracking chambers and an electromagnetic calorimeter together with systems for particle identification. The design of the detector and its performance over the first year and a half of operation are presented.

Generation of fibrinolytic activity by infusion of activated protein C into dogs.

Abstract: A B S T R A C T Bovine-activated protein C, administered intravenously to dogs, increases the rate oflysis of whole blood clots. Protein C, bovine prothrombin, and diisopropylfluorophosphate-inactivated protein Ca do not increase the rate of lysis. Repeated infusions of protein Ca sustain rapid blood clot lysis, but neither elevate circulating fibrin-split products nor decrease circulating plasminogen levels. The administration of protein Ca results in the elevation ofthe levels oflysineadsorbable plasminogen activator activity in the plasma. When partially purified concentrates of this activator are added to normal dog blood at the levels seen following protein Ca injection, the rate ofclot lysis is similar to that seen after protein Ca injection. The addition of protein Ca to citrated whole blood in vitro, with the subsequent neutralization of protein Ca with antibodies, results in increased rates of lysis when plasma made from the treated blood is reinjected into the animal. The generation of fibrinolytic activity is dependent on both cellular and plasma components of blood. A model of protein Ca fibrinolytic activity has a minimum of two components: a secondary messenger formed by protein Ca action on blood cells and plasma, and the subsequent appearance of plasminogen activator in the animal in response to that messenger.

Results of the Brugge Benchmark Study for Flooding Optimization and History Matching

Abstract: In preparation for the SPE Applied Technology Workshop (ATW) held in Brugge in June 2008, a unique benchmark project was organized to test the combined use of waterflooding-optimization and history-matching methods in a closed-loop workflow. The benchmark was organized in the form of an interactive competition during the months preceding the ATW. The goal set for the exercise was to create a set of history-matched reservoir models and then to find an optimal waterflooding strategy for an oil field containing 20 producers and 10 injectors that can each be controlled by three inflow-control valves (ICVs). A synthetic data set was made available to the participants by TNO, consisting of well-log data, the structure of the reservoir, 10 years of production data, inverted time-lapse seismic data, and other information necessary for the exercise. The parameters to be estimated during the history match were permeability, porosity, and net-to gross-(NTG) thickness ratio. The optimized production strategy was tested on a synthetic truth model developed by TNO, which was also used to generate the production data and inverted time-lapse seismic. Because of time and practical constraints, a full closed-loop exercise was not possible; however, the participants could obtain the response to their production strategy after 10 years, update their models, and resubmit a revised production strategy for the final 10 years of production. In total, nine groups participated in the exercise. The spread of the net present value (NPV) obtained by the different participants is on the order of 10%. The highest result that was obtained is only 3% below the optimized case determined for the known truth field. Although not an objective of this exercise, it was shown that the increase in NPV as a result of having three control intervals per well instead of one was considerable (approximately 20%). The results also showed that the NPV achieved with the flooding strategy that was updated after additional production data became available was consistently higher than before the data became available.