University of Florida

About: University of Florida is a education organization based out in Gainesville, Florida, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 90112 authors who have published 200011 publications receiving 7130576 citations. The organization is also known as: UF & University of the State of Florida.

Modal Analysis of Fluid Flows: An Overview

Abstract: Simple aerodynamic configurations under even modest conditions can exhibit complex flows with a wide range of temporal and spatial features. It has become common practice in the analysis of these flows to look for and extract physically important features, or modes, as a first step in the analysis. This step typically starts with a modal decomposition of an experimental or numerical dataset of the flowfield, or of an operator relevant to the system. We describe herein some of the dominant techniques for accomplishing these modal decompositions and analyses that have seen a surge of activity in recent decades [1–8]. For a nonexpert, keeping track of recent developments can be daunting, and the intent of this document is to provide an introduction to modal analysis that is accessible to the larger fluid dynamics community. In particular, we present a brief overview of several of the well-established techniques and clearly lay the framework of these methods using familiar linear algebra. The modal analysis techniques covered in this paper include the proper orthogonal decomposition (POD), balanced proper orthogonal decomposition (balanced POD), dynamic mode decomposition (DMD), Koopman analysis, global linear stability analysis, and resolvent analysis.

The operating performance of firms conducting seasoned equity offerings

Abstract: Recent studies have documented that firms conducting seasoned equity offerings have inordinately low stock returns during the five years after the offering, following a sharp run-up in the year prior to the offering. This article documents that the operating performance of issuing firms shows substantial improvement prior to the offering, but then deteriorates. The multiples at the time of the offering, however, do not reflect an expectation of deteriorating performance. Issuing firms are disproportionately high-growth firms, but issuers have much lower subsequent stock returns than nonissuers with the same growth rate. SEVERAL RECENT EMPIRICAL STUDIES have documented the poor stock market performance of firms conducting seasoned equity offerings (SEOs) in the United States and other countries.1 Loughran and Ritter (1995) report that the average raw return for issuing firms is only 7 percent per year during the five years after the offering, compared to 15 percent per year for nonissuing firms of the same market capitalization. These low postissue returns follow extremely high returns in the year prior to the offering: 72 percent on average.2 This article links the stock price performance of these issuing firms to their operating performance, and in so doing, addresses four questions: 1) Does the postissue operating performance of issuers deteriorate relative to comparable nonissuing firms? 2) Are the patterns for large issuers different from those for small issuers? 3) Do the capital expenditure decisions of issuers suggest that the managers are just as overoptimistic as investors are? 4) Given that issuing firms tend to be rapidly growing, and rapidly growing firms display strong

The Role of Hybridization in Plant Speciation

Abstract: The importance of hybridization in plant speciation and evolution has been debated for decades, with opposing views of hybridization as either a creative evolutionary force or evolutionary noise. Hybrid speciation may occur at either the homoploid (i.e., between two species of the same ploidy) or the polyploid level, each with its attendant genetic and evolutionary consequences. Whereas allopolyploidy (i.e., resulting from hybridization and genome doubling) has long been recognized as an important mode of plant speciation, the implications of genome duplication have typically not been taken into account in most fields of plant biology. Recent developments in genomics are revolutionizing our views of angiosperm genomes, demonstrating that perhaps all angiosperms have likely undergone at least one round of polyploidization and that hybridization has been an important force in generating angiosperm species diversity. Hybridization and polyploid formation continue to generate species diversity, with several n...