• Title/Summary/Keyword: Harvard University

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Application of a non-equilibrium ionization model to rapidly heated solar plasmas

  • Lee, Jin-Yi;Raymond, John C.;Reeves, Katharine K.;Shen, Chengcai;Moon, Yong-Jae;Kim, Yeon-Han
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.53.1-53.1
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    • 2019
  • We apply a non-equilibrium ionization (NEI) model to a supra-arcade plasma sheet, shocked plasma, and current sheet. The model assumes that the plasma is initially in ionization equilibrium at low temperature, and it is heated rapidly by a shock or magnetic reconnection. The model presents the temperature and characteristic timescale responses of the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory and X-ray Telescope (XRT) on board Hinode. We compare the model ratios of the responses between different passbands with the observed ratios of a supra-arcade plasma sheet on 2012 January 27. We find that most of observations are able to be described by using a combination of temperatures in equilibrium and the plasma closer to the arcade may be close to equilibrium ionization. We also utilize the set of responses to estimate the temperature and density for shocked plasma associated with a coronal mass ejection on 2010 June 13. The temperature, density, and the line of sight depth ranges we obtain are in reasonable agreement with previous works. However, a detailed model of the spherical shock is needed to fit the observations. We also compare the model ratios with the observations of a current sheet feature on 2017 September 10. The long extended current sheet above the solar limb makes it easy to analyze the sheet without background corona. We find that the sheet feature is far from equilibrium ionization while the background plasma is close to equilibrium. We discuss our results with the previous studies assuming equilibrium ionization.

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What Is New in the 2017 World Health Organization Classification and 8th American Joint Committee on Cancer Staging System for Pancreatic Neuroendocrine Neoplasms?

  • Jooae Choe;Kyung Won Kim;Hyoung Jung Kim;Dong Wook Kim;Kyu Pyo Kim;Seung-Mo Hong;Jin-Sook Ryu;Sree Harsha Tirumani;Katherine Krajewski;Nikhil Ramaiya
    • Korean Journal of Radiology
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    • v.20 no.1
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    • pp.5-17
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    • 2019
  • The diagnosis and management of pancreatic neuroendocrine neoplasms (NENs) have evolved significantly in recent years. There are several diagnostic and therapeutic challenges and controversies regarding the management of these lesions. In this review, we focus on the recent significant changes and controversial issues regarding the diagnosis and management of NENs and discuss the role of imaging in the multidisciplinary team approach.

A Direct Utility Model with Dynamic Constraint

  • Kim, Byungyeon;Satomura, Takuya;Kim, Jaehwan
    • Asia Marketing Journal
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    • v.18 no.4
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    • pp.125-138
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    • 2017
  • The goal of the study is to understand how consumers' constraint as opposed to utility structure gives rise to final decision when consumers purchase more than one variant of product at a time, i.e., horizontal variety seeking or multiple-discreteness. Purchase and consumption decision not only produces utility but also involves some sort of cognitive pressure. Past consumption or last purchase is likely to be linked to this burden we face such as concern for obesity, risk of harm, and guilt for mischief. In this research, the existence and the role of dynamic constraint are investigated through a microeconomic utility model with multiple dynamic constraint. The model is applied to the salty snacks data collected from field study where burden for spiciness serves as a constraint. The results are compared to the conventional multiple discreteness choice models of static constraints, and policy implications on price discounts is explored. The major findings are that first, one would underestimate the level of consumer preference for product offerings when ignoring the carry-over of the concern from the past consumption, and second, the impact of price promotion on demand would be properly evaluated when the model allows for the role of constraint as both multiple and dynamic. The current study is different from the existing studies in two ways. First, it captures the effect of 'mental constraint' on demand in formal economic model. Second, unlike the state dependence well documented in the literature, the study proposes the notion of state dependence in different way, via constraint rather than utility.