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.

Unification of luminous type 1 quasars through c iv emission

Abstract: Using a sample of ~30,000 quasars from the 7th Data Release of the Sloan Digital Sky Survey, we explore the range of properties exhibited by high-ionization, broad emission lines, such as C IV λ1549. Specifically, we investigate the anti-correlation between continuum luminosity and emission-line equivalent width (the Baldwin Effect (BEff)) and the blueshifting of the high-ionization emission lines with respect to low-ionization emission lines. Employing improved redshift determinations from Hewett & Wild, the blueshift of the C IV emission line is found to be nearly ubiquitous, with a mean shift of ~810 km s–1 for radio-quiet (RQ) quasars and ~360 km s–1 for radio-loud (RL) quasars. The BEff is present in both RQ and RL samples. We consider these phenomena within the context of an accretion disk-wind model that is modulated by the nonlinear correlation between ultraviolet and X-ray continuum luminosity. Composite spectra are constructed as a function of C IV emission-line properties in an attempt to reveal empirical relationships between different line species and the continuum. 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 broad absorption line quasars 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 is due to differences in an accretion disk wind between quasars (and over time); these differences are underlain primarily by the spectral energy distribution, which ultimately must be tied to BH mass and accretion rate.

Technology on the Move: Recent and Forthcoming Innovations for Tracking Migratory Birds

Abstract: Basic questions about the life histories of migratory birds have confounded scientists for generations, yet we are nearing an era of historic discovery as new tracking technologies make it possible to determine the timing and routes of an increasing number of bird migrations. Tracking small flying animals as they travel over continental-scale distances is a difficult logistical and engineering challenge. Although no tracking system works well with all species, improvements to traditional technologies, such as satellite tracking, along with innovations related to global positioning systems, cellular networks, solar geolocation, radar, and information technology are improving our understanding of when and where birds go during their annual cycles and informing numerous scientific disciplines, including evolutionary biology, population ecology, and global change. The recent developments described in this article will help us answer many long-standing questions about animal behavior and life histories.

Entrepreneurial Risk and Strategic Decision Making It’s a Matter of Perspective

Abstract: Risk taking has long been a central theme of the entrepreneurship literature. However, research on the risk propensity of entrepreneurs has met with virtually no empirical support even though entre...

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

Abstract: This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.

Managerial Empire Building and Firm Disclosure

Abstract: This study tests the agency cost hypothesis in the context of geographic earnings disclosures. The agency cost hypothesis predicts that managers, when not monitored by shareholders, make self-maximizing decisions that may not necessarily be in the best interest of shareholders. These decisions include aggressively growing the firm, which reduces profitability and destroys firm value. Geographic earnings disclosures provide an interesting context to examine this issue. Beginning with Statement of Financial Accounting Standards No. 131 (SFAS 131), most U.S. multinational firms are no longer required to disclose earnings by geographic area (e.g., net income in Mexico or net income in East Asia). Such nondisclosure potentially reduces the ability of shareholders to monitor managers' decisions related to foreign operations. Using a sample of U.S. multinationals with substantial foreign operations, we find that nondisclosing firms, relative to firms that continue to disclose geographic earnings, experience greater expansion of foreign sales, produce lower foreign profit margins, and have lower firm value in the post–SFAS 131 period. Our conclusions are strengthened by the fact that these differences do not exist in the pre–SFAS 131 period and do not relate to domestic operations. We find differences in the predicted direction only for foreign operations and only after adoption of SFAS 131. Our results are robust to the inclusion of an extensive set of control variables related to alternative corporate governance mechanisms, operating performance, and the firm's information environment. Overall, the results are consistent with the agency cost hypothesis and the important role of financial disclosures in monitoring managers.