"Assessing the Consequences of a Horizontal Merger and its Remedies in a Dynamic Environment"

This paper estimates a dynamic oligopoly model to assess the economic consequences of a horizontal merger that took place in 1970 to create the second largest global producer of steel. The paper solves a Markov perfect Nash equilibrium for the model and simulates the welfare effects of the horizontal merger. Estimates reveal that the merger enhanced the production efficiency of the merging party by a magnitude of 4.1 %, while the exercise of market power was restrained primarily by the presence of fringe competitors. Our simulation result also indicates that structural remedies endorsed by the competition authority failed to promote competition. model.

現行英語カリキュラム体系とその運用

本報告書は､2002年の施行以来現在に至るまで神奈川大学経営学部で運用中である英語カリキュラムについて､その作成背景､科目体系の特徴､有効性､問題点といった角度から現時点での再検討を試みることによって､将来新たにカリキュラム改革が行われる場合に備える目的で作成されたものである｡現行カリキュラムの1言語選択必修制､週4回1年次集中型の履修方法､基礎･初級･中級･上級英語という習熟度別に設定された科目体系などの現行カリキュラムの大きな特徴が､経営学部の英語教育にどのような影響を及ぼしてきたかについて､毎年実施しているプレイスメントテストのデータの分析をもとに理学部との比較も交えながら考察した｡教育報告

Gravitational instability, spiral substructure, and modest grain growth in a typical protostellar disk: Modeling multi-wavelength dust continuum observation of TMC1A

Embedded, Class 0/I protostellar disks represent the initial condition for planet formation. This calls for better understandings of their bulk properties and the dust grains within them. We model multi-wavelength dust continuum observations of the disk surrounding the Class I protostar TMC1A to provide insight on these properties. The observations can be well fit by a gravitationally self-regulated (i.e., marginally gravitationally unstable and internally heated) disk model, with surface density $\Sigma \sim 1720 (R/10au)^{-1.96} g/cm^2$ and midplane temperature $T_{mid} \sim 185 (R/10au)^{-1.27} K$. The observed disk contains a $m=1$ spiral substructure; we use our model to predict the spiral's pitch angle and the prediction is consistent with the observations. This agreement serves as both a test of our model and strong evidence of the gravitational nature of the spiral. Our model estimates a maximum grain size $a_{max}\sim 196(R/10au)^{-2.45} \mu m$, which is consistent with grain growth being capped by a fragmentation barrier with threshold velocity $\sim 1 m/s$. We further demonstrate that observational properties of TMC1A are typical among the observed population of Class 0/I disks, which hints that traditional methods of disk data analyses based on Gaussian fitting and the assumption of the optically thin dust emission could have systematically underestimated disk size and mass and overestimated grain size.Comment: 16 pages, 8 figures, accepted for publication in Ap