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Who's Who Among the NSO Postdocs (1Mar96) (from NSO, NOAO Newsletter No. 45, March 1996) Sydney D'Silva received his PhD from the Indian Institute of Science in Bangalore, India. His thesis topic was on the "Dynamics of Rising Magnetic Flux Tubes in the Convection Zone of the Sun." Sydney is a theorist, working in Tucson, who is currently devoting his efforts toward a deeper understanding of the structure and formation of magnetic fields in the deep interior of the Sun, through magnetohydrodynamic and helioseismic studies. His work has included explaining the dynamics of sunspots and studying the accretion of magnetic flux tubes within accretion disks around black holes; his recent work is on the theoretical aspects of time-distance helioseismology and helioseismic tomography. These represent new approaches to the study of the solar interior that complement conventional helioseismology. Yuhong Fan received her PhD in Astronomy in October 1993 at the Institute for Astronomy, University of Hawaii. Her dissertation was on the numerical simulations of the dynamic evolution of emerging magnetic flux tubes in the solar convection zone. As a postdoc at NSO/Tucson, Yuhong has continued her collaboration with G. Fisher (UC Berkeley) to carry out theoretical modeling of the buoyant rise of thin magnetic flux tubes from the base of the solar convection zone to the solar surface, and to compare the properties of the emerging flux tubes with the observed properties of sunspot groups and active regions. In addition, Yuhong is collaborating with D. Braun (SPRC/NSO) and D.-Y. Chou (National Tsing-Hua Univ., Taiwan) in the modeling of the scattering of solar acoustic waves by localized magnetic inhomogeneities (such as sunspot flux tubes). The primary goal of this effort is to interpret the observational results of acoustic scattering by sunspots and hence to infer the subsurface conditions of these magnetic structures. Yeming Gu received his PhD at the Physics Department of the University of Arizona in 1992. His thesis topic in solar seismology was entitled "Inverse Problem with Continuous Parameters for Solar Oscillations." Yeming's current research interests include stochastic radiative transfer and its applications to the solar atmosphere, solar seismology and data analysis. In collaboration with John Jefferies, Charles Lindsey, and E. H. Avrett, he is currently working in Tucson on the interpretation of continuous infrared and microwave data from the Sun using a stochastic two-component model for the solar atmosphere. The work is a new approach to solar atmospheric modeling. It utilizes the center-to-limb data in the spectral range 2-1200 um as a powerful diagnostic tool for inhomogeneous structures in the low solar atmosphere. Haosheng Lin received his PhD from Michigan State University, working with Jeff Kuhn on problems related to solar irradiance variability, solar vector magnetic field measurements, photometric detection schemes, and IR array instrumentation. Haosheng spent two years at Caltech and Big Bear before coming to NSO/SP. He is presently supported by the RISE project and maintains active observing programs at the VTT (IR measurements of the photospheric magnetic field) and the Evans Facility (coronal spectral observations). Louis Strous received his PhD from Utrecht University in 1994. He developed new methods for the measurement of horizontal flows in the solar atmosphere and applied his measurements to the identification and interpretation of magnetic-flux emergence and evolution. Louis worked in collaboration with Kees Zwaan, his thesis advisor, and with the Lockheed Palo Alto Research Laboratory. Presently resident at Sacramento Peak and supported by the New Jersey Institute of Technology, Louis is working with Phil Goode and Tuck Stebbins on observations that try to identify the sources of acoustic flux responsible for the global helioseismic p-modes. John Varsik received his PhD from the University of Hawaii in 1987, working with Jim Heasley on variability in the K-line in F stars. For his thesis he studied stellar activity versus age in F and G stars. After receiving his PhD, he went to Big Bear Solar Observatory as instrumentation scientist. There he obtained expertise in the operation, calibration, and scientific interpretation of solar vector magnetic field measurements. John's observational interests include solar oscillations in the K-line and chromospheric acoustic waves, and solar polar magnetic fields. His activities at NSO/SP include quantitative measurements of airborne particulates in support of the CLEAR study. [Photos not included] Tucson Postdocs Yeming Gu, Sydney D'Silva, Yuhong Fan Sacramento Peak Postdocs Haosheng Lin and John Varsik Mark Giampapa, Larry November
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