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112 results on '"Choi, E.J."'

12. Radiation from accelerated particles in relativistic jets with shocks, shear-flow, and reconnection

Author

Nishikawa K.-I., Hardee P., Mizuno Y., Duţan I., Zhang B., Medvedev M, Choi E.J., Min K. W., Niemiec J., Nordlund Å., Frederiksen J., Sol H., Pohl M., Hartmann D. H., Marscher A., and Gómez J. L.

Subjects
Physics, QC1-999
Abstract

We have investigated particle acceleration and shock structure associated with an unmagnetized relativistic jet propagating into an unmagnetized plasma for electron-positron and electron-ion plasmas. Strong magnetic fields generated in the trailing jet shock lead to transverse deflection and acceleration of the electrons. We have self-consistently calculated the radiation from the electrons accelerated in the turbulent magnetic fields for different jet Lorentz factors. We find that the synthetic spectra depend on the bulk Lorentz factor of the jet, the jet temperature, and the strength of the magnetic fields generated in the shock. We have investigated the generation of magnetic fields associated with velocity shear between an unmagnetized relativistic (core) jet and an unmagnetized sheath plasma. We discuss particle acceleration in collimation shocks for AGN jets formed by relativistic MHD simulations. Our calculated spectra should lead to a better understanding of the complex time evolution and/or spectral structure from gamma-ray bursts, relativistic jets, and supernova remnants.

Published
2013
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25. The Body in Packaging Culture: Researching Cosmetic Surgery within Korea’s Neo-Confucian Culture

Author

Choi, E.J., Korte, Prof. dr. Anne-Marie (Thesis Advisor), Choi, E.J., and Korte, Prof. dr. Anne-Marie (Thesis Advisor)

Abstract

Contemporary developments within the current global self-care regime have increased the potential of many individuals to control their own bodies, and to have their bodies surveilled by others (Shilling, 2003). The body is understood as a project that needs to be “worked at and accomplished as part of an individual’s self-identity” (Shilling, 2003:4) in this time of ‘high modernity’ (Giddens, 1991). The project of cosmetic surgery is one example of how modern individuals attribute significance both to their bodies and the way their bodies look. In a South Korean context, the cosmetic surgery scene is especially interesting to examine in the light of the uniquely Korean practice of giving cosmetic surgery as a gift, especially to daughters. Ironically, the body has to remain unaltered from how it has been received at birth according to the Neo-Confucian tradition, which continues to form the ideological base of contemporary Korean society. Moreover, this tradition teaches that inward goodness does not depend upon one’s outer appearance, something that is quite opposite to “popular physiognomic assumptions that the body, especially the face, is a reflection of the self” (Featherstone, 2010:195). This thesis specifically attempts to understand the practice of cosmetic surgery within Korean society, arguing that this practice is ironically supported by Korea’s remaining Neo-Confucian traditions as well as by contemporary global body-care regimes, which somehow interlock with Neo-Confucian ideas concerning body management.

Published
2015

29. Infrared optical absorption spectra of CuO single crystals: Fermion-spinon band and dimensional crossover of the antiferromagnetic order

Author

Jung S.H, Kim J., J. Choi E.J., Seiko Y., Kimura T., and Lorenzana J.

Subjects
Condensed Matter::Strongly Correlated Electrons
Abstract

We have obtained mid-infrared optical absorption spectra of the S=1/2 quasi-one-dimensional CuO using polarized transmission measurement and interpreted the spectra in terms of phonon-assisted magnetic excitations. When the electric field is parallel to the main antiferromagnetic direction a ? shaped peak is observed with the maximum at ?=0.23 eV which is attributed to spinons along Cu-O chains. At low temperatures in the antiferromagnetic phase another peak appears at ?=0.16 eV which is attributed to two-magnon absorption but the spinon peak remains. This behavior is interpreted as due to a dimensional crossover where the low-temperature three-dimensional magnetic phase keeps short-range characteristics of a one-dimensional magnet.

Published
2009

35. Radiation from accelerated particles in relativistic jets with shocks, shear-flow, and reconnection

Author

Nishikawa, K.-I., Zhang, B., Dutan, I., Medvedev, M., Hardee, P., Choi, E.J., Min, K.W., Niemiec, J., Mizuno, Y., Nordlund, Åke, Frederiksen, Jacob Trier, Sol, H., Pohl, M., Hartmann, D.H., Nishikawa, K.-I., Zhang, B., Dutan, I., Medvedev, M., Hardee, P., Choi, E.J., Min, K.W., Niemiec, J., Mizuno, Y., Nordlund, Åke, Frederiksen, Jacob Trier, Sol, H., Pohl, M., and Hartmann, D.H.

Published
2013

36. Magnetic field generation in a jet-sheath plasma via the kinetic Kelvin-Helmholtz instability

Author

Nishikawa, K.-I., Hardee, P., Zhang, B., Dutan, I., Medvedev, M., Choi, E.J., Min, K.W., Niemiec, J., Mizuno, Y., Nordlund, Åke, Frederiksen, Jacob Trier, Sol, H., Pohl, M., Hartmann, D.H., Nishikawa, K.-I., Hardee, P., Zhang, B., Dutan, I., Medvedev, M., Choi, E.J., Min, K.W., Niemiec, J., Mizuno, Y., Nordlund, Åke, Frederiksen, Jacob Trier, Sol, H., Pohl, M., and Hartmann, D.H.

Published
2013

39. Radiation from accelerated particles in relativistic jets with shocks, shear-flow, and reconnection

Author

Nishikawa, K.-I., primary, Zhang, B., additional, Dutan, I., additional, Medvedev, M., additional, Hardee, P., additional, Choi, E.J., additional, Min, K.W., additional, Niemiec, J., additional, Mizuno, Y., additional, Nordlund, A., additional, Frederiksen, J.T., additional, Sol, H., additional, Pohl, M., additional, and Hartmann, D.H., additional

Published
2013
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