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Institution

University of Oklahoma

EducationNorman, Oklahoma, United States
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.


Papers
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Journal ArticleDOI
TL;DR: In this article, a detailed analysis of a large published database of spectroscopic observations of Sr, Y, Zr, Ba, and Eu for Galactic stars at various metallicities, showing that the observed trends versus metallicity can be understood in light of a multiplicity of stellar neutron-capture components.
Abstract: In this paper we follow the Galactic enrichment of three easily observed light n-capture elements: Sr, Y, and Zr. Input stellar yields have been first separated into their respective main and weak s-process components and r-process component. The s-process yields from asymptotic giant branch (AGB) stars of low to intermediate mass are computed, exploring a wide range of efficiencies of the major neutron source, 13 C, and covering both disk and halo metallicities. AGB stars have been shown to reproduce the mains-component in the solar system, i.e., the s-process isotopic distribution of allheavy isotopes with atomic mass number A > 90, with a minor contribution to the light s-process isotopes up to A � 90. The concurrent weak s-process, which accounts for the major fraction of the light s-process isotopes in the solar system and occurs in massive stars by the operation of the 22 Ne neutron source, is discussed in detail. Neither the main s -n or the weaks-components are shown to contribute significantly to the neutron-capture element abundances observed in unevolved halo stars. Knowing the s-process distribution at the epoch of the solar system formation, we first employed the r-process residuals method to infer the isotopic distribution of the r-process. We assumed a primary r-process production in the Galaxy from moderately massive Type II supernovae that best reproduces the observational Galactic trend of metallicity versus Eu, an almost pure r-process element. We present a detailed analysis of a large published database of spectroscopic observations of Sr, Y, Zr, Ba, and Eu for Galactic stars at various metallicities, showing that the observed trends versus metallicity can be understood in light of a multiplicity of stellar neutron-capture components. Spectroscopic observations of the Sr, Y, and Zr to Ba and Eu abundance ratios versus metallicity provide useful diagnostics of the types of neutron-capture processes forming Sr, Y, and Zr. In particular, the observed [Sr, Y, Zr/Ba, Eu] ratio is clearly not flat at low metallicities, as we would expect if Ba, Eu and Sr, Y, Zr all had the same r-process nucleosynthetic origin. We discuss our chemical evolution predictions, taking into account the interplay between different processes to produce Sr-Y-Zr. Making use of the very r-process‐rich and very metal-poor stars like CS 22892� 052 and CS 31082� 001, we find hints and discuss the possibility of a primary process in low-metallicity massive stars, different from the ‘‘classical s-process’’ and from the ‘‘classical r-process’’ that we tentatively define LEPP (lighter element primary process). This allows us to revise the estimates of the r-process contributions to the solar Sr, Y, and Zr abundances, as well as of the contribution to the s-only isotopes 86 Sr, 87 Sr, and 96 Mo. Subject headings: Galaxy: abundances — Galaxy: evolution — nuclear reactions, nucleosynthesis, abundances — stars: abundances — stars: AGB and post-AGB

653 citations

Journal ArticleDOI
TL;DR: The dedicated work of numerous scholars has, over the last 10 years, led to some radical advances in our understanding of the nature and implications of creativity as discussed by the authors, which has been summarized in two recent handbooks-Mark Runco's Creativity Research Handbook and Robert Sternberg's Handbook of Creativity.
Abstract: The dedicated work of numerous scholars has, over the last 10 years, led to some radical advances in our understanding of the nature and implications of creativity. This work has been summarized in 2 recent handbooks-Mark Runco's Creativity Research Handbook and Robert Sternberg's Handbook of Creativity. In this article I use these handbooks as a starting point to take stock in both what has been accomplished and what still needs to be done in our attempts to understand creativity. I begin by noting that both handbooks clearly describe the major approaches being used in studies of creativity and the findings resulting from each approach. A careful review of the chapters presented in these handbooks, however, brings to the fore a number of issues. For example, we need critical comparative tests contrasting the merits of different methods and theories, elaboration and extension of our traditional samples and our traditional measures, and more attempts to develop integrative models. However, some topics, suc...

653 citations

Journal ArticleDOI
TL;DR: In this paper, a randomized, double-blind, placebo-controlled trial of convalescent plasma with high IgG titers against SARS-CoV-2 in older adult patients within 72 hours after the onset of mild Covid-19 symptoms was conducted.
Abstract: Background Therapies to interrupt the progression of early coronavirus disease 2019 (Covid-19) remain elusive. Among them, convalescent plasma administered to hospitalized patients has been unsuccessful, perhaps because antibodies should be administered earlier in the course of illness. Methods We conducted a randomized, double-blind, placebo-controlled trial of convalescent plasma with high IgG titers against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in older adult patients within 72 hours after the onset of mild Covid-19 symptoms. The primary end point was severe respiratory disease, defined as a respiratory rate of 30 breaths per minute or more, an oxygen saturation of less than 93% while the patient was breathing ambient air, or both. The trial was stopped early at 76% of its projected sample size because cases of Covid-19 in the trial region decreased considerably and steady enrollment of trial patients became virtually impossible. Results A total of 160 patients underwent randomization. In the intention-to-treat population, severe respiratory disease developed in 13 of 80 patients (16%) who received convalescent plasma and 25 of 80 patients (31%) who received placebo (relative risk, 0.52; 95% confidence interval [CI], 0.29 to 0.94; P = 0.03), with a relative risk reduction of 48%. A modified intention-to-treat analysis that excluded 6 patients who had a primary end-point event before infusion of convalescent plasma or placebo showed a larger effect size (relative risk, 0.40; 95% CI, 0.20 to 0.81). No solicited adverse events were observed. Conclusions Early administration of high-titer convalescent plasma against SARS-CoV-2 to mildly ill infected older adults reduced the progression of Covid-19. (Funded by the Bill and Melinda Gates Foundation and the Fundacion INFANT Pandemic Fund; Direccion de Sangre y Medicina Transfusional del Ministerio de Salud number, PAEPCC19, Plataforma de Registro Informatizado de Investigaciones en Salud number, 1421, and ClinicalTrials.gov number, NCT04479163.).

653 citations

Journal ArticleDOI
TL;DR: Rhizosphere networks were substantially more complex than those in surrounding soils, indicating the rhizosphere has a greater potential for interactions and niche-sharing and quorum-based signalling as one potential strategy.
Abstract: While interactions between roots and microorganisms have been intensively studied, we know little about interactions among root-associated microbes. We used random matrix theory-based network analysis of 16S rRNA genes to identify bacterial networks associated with wild oat (Avena fatua) over two seasons in greenhouse microcosms. Rhizosphere networks were substantially more complex than those in surrounding soils, indicating the rhizosphere has a greater potential for interactions and niche-sharing. Network complexity increased as plants grew, even as diversity decreased, highlighting that community organisation is not captured by univariate diversity. Covariations were predominantly positive (> 80%), suggesting that extensive mutualistic interactions may occur among rhizosphere bacteria; we identified quorum-based signalling as one potential strategy. Putative keystone taxa often had low relative abundances, suggesting low-abundance taxa may significantly contribute to rhizosphere function. Network complexity, a previously undescribed property of the rhizosphere microbiome, appears to be a defining characteristic of this habitat.

648 citations

Journal ArticleDOI
TL;DR: In this paper, the state of the art of membrane materials, including polymers and hybrid materials, as well as the current issues and barriers, and finally, future research directions in membrane science are outlined.
Abstract: Membrane gas separation is a mature and expanding technology. However, the availability of better membrane materials would promote faster growth. In this Perspective we analyze the state of the art of membrane materials, including polymers and hybrid materials, as well as the current issues and barriers, and finally, we outline future research directions in membrane science. Development of new membrane materials for large scale separations will rely on a multidisciplinary approach that embraces the broad fields of chemical and materials engineering, polymer science, and materials chemistry.

647 citations


Authors

Showing all 25490 results

NameH-indexPapersCitations
Ronald C. Kessler2741332328983
Michael A. Strauss1851688208506
Derek R. Lovley16858295315
Ashok Kumar1515654164086
Peter J. Schwartz147647107695
Peter Buchholz143118192101
Robert Hirosky1391697106626
Elizabeth Barrett-Connor13879373241
Brad Abbott137156698604
Lihong V. Wang136111872482
Itsuo Nakano135153997905
Phillip Gutierrez133139196205
P. Skubic133157397343
Elizaveta Shabalina133142192273
Richard Brenner133110887426
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202392
2022348
20212,425
20202,481
20192,433
20182,396