Institution
University of Central Florida
Education•Orlando, Florida, United States•
About: University of Central Florida is a education organization based out in Orlando, Florida, United States. It is known for research contribution in the topics: Laser & Population. The organization has 18822 authors who have published 48679 publications receiving 1234422 citations. The organization is also known as: UCF.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, it is shown that the nonlinear dispersion relation has a common form and can be understood in terms of the linear Kramers-Kronig relation applied to a new system consisting of the material plus some perturbation.
Abstract: We review dispersion relations, which relate the real part of the optical susceptibility (refraction) to the imaginary part (absorption). We derive and discuss these relations as applied to nonlinear optical systems. It is shown that in the nonlinear case, for self-action effects the correct form for such dispersion relations is nondegenerate, i.e. it is necessary to use multiple frequency arguments. Nonlinear dispersion relations have been shown to be very useful as they usually only require integration over a limited frequency range (corresponding to frequencies at which the absorption changes), unlike the conventional linear Kramers-Kronig relation which requires integration over all absorbing frequencies. Furthermore, calculation of refractive index changes using dispersion relations is easier than a direct calculation of the susceptibility, as transition rates (which give absorption coefficients) are, in general, far easier to calculate than the expectation value of the optical polarization. Both resonant (generation of some excitation that is long lived compared with an optical period) and nonresonant ‘instantaneous’ optical nonlinearities are discussed, and it is shown that the nonlinear dispersion relation has a common form and can be understood in terms of the linear Kramers-Kronig relation applied to a new system consisting of the material plus some ‘perturbation’. We present several examples of the form of this external perturbation, which can be viewed as the pump in a pump-probe experiment. We discuss the two-level saturated atom model and bandfilling in semiconductors among others for the resonant case. For the nonresonant case some recent work is included where the electronic nonlinear refractive coefficient,n2, is determined from the nonlinear absorption processes of two-photon absorption, Raman transitions and the a.c. Stark effect. We also review how the dispersion relations can be extended to give alternative forms for frequency summation which, for example, allows the real and imaginary parts ofχ(2) to be related.
355 citations
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TL;DR: In this paper, the authors reviewed the extended Cauchy model and the four-parameter model for describing the wavelength and temperature effects of liquid crystal (LC) refractive indices.
Abstract: This paper reviews the extended Cauchy model and the four-parameter model for describing the wavelength and temperature effects of liquid crystal (LC) refractive indices. The refractive indices of nine commercial LCs, MLC-9200-000, MLC-9200-100, MLC-6608, MLC-6241-000, 5PCH, 5CB, TL-216, E7, and E44 are measured by the Multi-wavelength Abbe Refractometer. These experimental data are used to validate the theoretical models. Excellent agreement between experiment and theory is obtained.
354 citations
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TL;DR: This paper examined the link between liquidity constraints and investment behavior for German firms of different sizes from 1970 to 1986 and found that medium sized firms appear to be more liquidity constrained in their investment behavior than either the smallest or largest firms in the study.
354 citations
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University of Oxford1, Ben-Gurion University of the Negev2, Tel Aviv University3, Bishop Museum4, Villanova University5, Imperial College London6, Zoological Society of London7, University of Valle8, University College London9, University of Brasília10, Technion – Israel Institute of Technology11, Universiti Malaysia Sarawak12, University of Central Florida13, La Sierra University14, Museu Paraense Emílio Goeldi15, University of Michigan16, University of São Paulo17, Royal Museum for Central Africa18, Royal Belgian Institute of Natural Sciences19, University of Lincoln20, Pontificia Universidad Católica del Ecuador21, Institut de recherche pour le développement22, Virginia Commonwealth University23, Chinese Academy of Sciences24, American Museum of Natural History25
TL;DR: It is shown that additional conservation actions are needed to effectively protect reptiles, particularly lizards and turtles, and that adding reptile knowledge to a global complementarity conservation priority scheme identifies many locations that consequently become important.
Abstract: The distributions of amphibians, birds and mammals have underpinned global and local conservation priorities, and have been fundamental to our understanding of the determinants of global biodiversity. In contrast, the global distributions of reptiles, representing a third of terrestrial vertebrate diversity, have been unavailable. This prevented the incorporation of reptiles into conservation planning and biased our understanding of the underlying processes governing global vertebrate biodiversity. Here, we present and analyse the global distribution of 10,064 reptile species (99% of extant terrestrial species). We show that richness patterns of the other three tetrapod classes are good spatial surrogates for species richness of all reptiles combined and of snakes, but characterize diversity patterns of lizards and turtles poorly. Hotspots of total and endemic lizard richness overlap very little with those of other taxa. Moreover, existing protected areas, sites of biodiversity significance and global conservation schemes represent birds and mammals better than reptiles. We show that additional conservation actions are needed to effectively protect reptiles, particularly lizards and turtles. Adding reptile knowledge to a global complementarity conservation priority scheme identifies many locations that consequently become important. Notably, investing resources in some of the world’s arid, grassland and savannah habitats might be necessary to represent all terrestrial vertebrates efficiently.
354 citations
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23 Jun 2013TL;DR: The extracted primary object regions are then used to build object models for optimized video segmentation and outperforms both unsupervised and supervised state-of-the-art methods.
Abstract: In this paper, we propose a novel approach to extract primary object segments in videos in the `object proposal' domain. The extracted primary object regions are then used to build object models for optimized video segmentation. The proposed approach has several contributions: First, a novel layered Directed Acyclic Graph (DAG) based framework is presented for detection and segmentation of the primary object in video. We exploit the fact that, in general, objects are spatially cohesive and characterized by locally smooth motion trajectories, to extract the primary object from the set of all available proposals based on motion, appearance and predicted-shape similarity across frames. Second, the DAG is initialized with an enhanced object proposal set where motion based proposal predictions (from adjacent frames) are used to expand the set of object proposals for a particular frame. Last, the paper presents a motion scoring function for selection of object proposals that emphasizes high optical flow gradients at proposal boundaries to discriminate between moving objects and the background. The proposed approach is evaluated using several challenging benchmark videos and it outperforms both unsupervised and supervised state-of-the-art methods.
354 citations
Authors
Showing all 19051 results
Name | H-index | Papers | Citations |
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Gang Chen | 167 | 3372 | 149819 |
Kevin M. Huffenberger | 138 | 402 | 93452 |
Eduardo Salas | 129 | 711 | 62259 |
Akihisa Inoue | 126 | 2652 | 93980 |
Allan H. MacDonald | 119 | 926 | 56221 |
Hagop S. Akiskal | 118 | 565 | 50869 |
Richard P. Van Duyne | 116 | 409 | 79671 |
Jun Wang | 106 | 1031 | 49206 |
Mubarak Shah | 106 | 614 | 56738 |
Larry L. Hench | 103 | 491 | 55633 |
Michael Walsh | 102 | 963 | 42231 |
Wei Liu | 102 | 2927 | 65228 |
Demetrios N. Christodoulides | 100 | 704 | 51093 |
Paul E. Spector | 99 | 325 | 52843 |
Eric A. Hoffman | 99 | 809 | 36891 |