The Experts below are selected from a list of 195741 Experts worldwide ranked by ideXlab platform
Trujillo J Bueno - One of the best experts on this subject based on the ideXlab platform.
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the transfer of resonance line polarization with partial frequency redistribution and j state interference Theoretical Approach and numerical methods
Astronomy and Astrophysics, 2014Co-Authors: L Belluzzi, Trujillo J BuenoAbstract:The linear polarization signals produced by scattering processes in strong resonance lines are rich in information on the magnetic and thermal structure of the chromosphere and transition region of the Sun and of other stars. A correct modeling of these signals requires accounting for partial frequency redistribution effects, as well as for the impact of quantum interference between different fine structure levels (J-state interference). In this paper, we present a Theoretical Approach suitable for modeling the transfer of resonance line polarization when taking these effects into account, along with an accurate numerical method of solution of the problem’s equations. We consider a two-term atom with unpolarized lower term and infinitely sharp lower levels, in the absence of magnetic fields. We show that by making simple formal substitutions on the quantum numbers, the Theoretical Approach derived here for a two-term atom can also be applied to describe a two-level atom with hyperfine structure. An illustrative application to the Mg ii doublet around 2800 A is presented.
Benjamin Flesch - One of the best experts on this subject based on the ideXlab platform.
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Social Set Analysis: A Set Theoretical Approach to Big Data Analytics
IEEE Access, 2016Co-Authors: Ravi Vatrapu, Raghava Rao Mukkamala, Abid Hussain, Benjamin FleschAbstract:Current analytical Approaches in computational social science can be characterized by four dominant paradigms: text analysis (information extraction and classification), social network analysis (graph theory), social complexity analysis (complex systems science), and social simulations (cellular automata and agent-based modeling). However, when it comes to organizational and societal units of analysis, there exists no Approach to conceptualize, model, analyze, explain, and predict social media interactions as individuals' associations with ideas, values, identities, and so on. To address this limitation, based on the sociology of associations and the mathematics of set theory, this paper presents a new Approach to big data analytics called social set analysis. Social set analysis consists of a generative framework for the philosophies of computational social science, theory of social data, conceptual and formal models of social data, and an analytical framework for combining big social data sets with organizational and societal data sets. Three empirical studies of big social data are presented to illustrate and demonstrate social set analysis in terms of fuzzy set-Theoretical sentiment analysis, crisp set-Theoretical interaction analysis, and event-studies-oriented set-Theoretical visualizations. Implications for big data analytics, current limitations of the set-Theoretical Approach, and future directions are outlined.
L Belluzzi - One of the best experts on this subject based on the ideXlab platform.
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the transfer of resonance line polarization with partial frequency redistribution and j state interference Theoretical Approach and numerical methods
Astronomy and Astrophysics, 2014Co-Authors: L Belluzzi, Trujillo J BuenoAbstract:The linear polarization signals produced by scattering processes in strong resonance lines are rich in information on the magnetic and thermal structure of the chromosphere and transition region of the Sun and of other stars. A correct modeling of these signals requires accounting for partial frequency redistribution effects, as well as for the impact of quantum interference between different fine structure levels (J-state interference). In this paper, we present a Theoretical Approach suitable for modeling the transfer of resonance line polarization when taking these effects into account, along with an accurate numerical method of solution of the problem’s equations. We consider a two-term atom with unpolarized lower term and infinitely sharp lower levels, in the absence of magnetic fields. We show that by making simple formal substitutions on the quantum numbers, the Theoretical Approach derived here for a two-term atom can also be applied to describe a two-level atom with hyperfine structure. An illustrative application to the Mg ii doublet around 2800 A is presented.
Ravi Vatrapu - One of the best experts on this subject based on the ideXlab platform.
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Social Set Analysis: A Set Theoretical Approach to Big Data Analytics
IEEE Access, 2016Co-Authors: Ravi Vatrapu, Raghava Rao Mukkamala, Abid Hussain, Benjamin FleschAbstract:Current analytical Approaches in computational social science can be characterized by four dominant paradigms: text analysis (information extraction and classification), social network analysis (graph theory), social complexity analysis (complex systems science), and social simulations (cellular automata and agent-based modeling). However, when it comes to organizational and societal units of analysis, there exists no Approach to conceptualize, model, analyze, explain, and predict social media interactions as individuals' associations with ideas, values, identities, and so on. To address this limitation, based on the sociology of associations and the mathematics of set theory, this paper presents a new Approach to big data analytics called social set analysis. Social set analysis consists of a generative framework for the philosophies of computational social science, theory of social data, conceptual and formal models of social data, and an analytical framework for combining big social data sets with organizational and societal data sets. Three empirical studies of big social data are presented to illustrate and demonstrate social set analysis in terms of fuzzy set-Theoretical sentiment analysis, crisp set-Theoretical interaction analysis, and event-studies-oriented set-Theoretical visualizations. Implications for big data analytics, current limitations of the set-Theoretical Approach, and future directions are outlined.
Dirk J Faber - One of the best experts on this subject based on the ideXlab platform.
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a literature review and novel Theoretical Approach on the optical properties of whole blood
Lasers in Medical Science, 2014Co-Authors: Nienke Bosschaart, Gerda Edelman, Maurice C G Aalders, Ton G Van Leeuwen, Dirk J FaberAbstract:Optical property measurements on blood are influenced by a large variety of factors of both physical and methodological origin. The aim of this review is to list these factors of influence and to provide the reader with optical property spectra (250-2,500 nm) for whole blood that can be used in the practice of biomedical optics (tabulated in the appendix). Hereto, we perform a critical examination and selec- tion of the available optical property spectra of blood in litera- ture, from which we compile average spectra for the absorption coefficient (μa), scattering coefficient (μs) and scattering anisot- ropy (g). From this, we calculate the reduced scattering coeffi- cient (μs') and the effective attenuation coefficient (μeff). In the compilation of μa and μs, we incorporate the influences of absorption flattening and dependent scattering (i.e. spatial cor- relations between positions of red blood cells), respectively. For the influence of dependent scattering on μs ,w e present an ovel, Theoretically derived formula that can be used for practical rescaling of μs to other haematocrits. Since the measurement of the scattering properties of blood has been proven to be challenging, we apply an alternative, Theoretical Approach to calculate spectra for μs and g. Hereto, we combine Kramers- Kronig analysis with analytical scattering theory, extended with Percus-Yevick structure factors that take into account the effect of dependent scattering in whole blood. We argue that our calculated spectra may provide a better estimation for μs and g (and hence μsand μeff) than the compiled spectra from literature for wavelengths between 300 and 600 nm.
