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表面波トモグラフィーによるモンゴル地域の上部マントル構造
No full textInvestigations of seismic structures of the upper mantle based on surface wave analysis can be useful for clarifying the regional tectonics and mantle dynamics, but such studies have still been limited in the Mongolian region. Although some local areas in Mongolia have been the targets of several earlier seismological studies, surface-wave tomography across the nationwide areas of Mongolia with the enhanced coverage of seismic stations has yet to be investigated. Over the past decade, a number of seismic stations have been installed in Mongolia. Between 2011 and 2013, 69 temporary broadband seismic stations were installed in central-south Mongolia as a part of a collaborative project between China and Mongolia. From 2012 to 2016, several temporary broadband networks of IRIS-PASSCAL (Incorporated Research Institutions for Seismology – Program for the Array Seismic Studies of the Continental Lithosphere) were sporadically installed in western Mongolia. Since 2015, the nationwide regional broadband seismic network in Mongolia has also been in operation. These seismic networks have enabled us to carry out surfacewave dispersion measurements, which can be the basis for the construction of a 3-D S-wave model of the entire Mongolian region. In this study, we employ the three-stage inversion technique of multimode surface waves. In the initial stage, we measured multimode phase speeds of Love and Rayleigh waves for a number of source-receiver pairs by using a fully nonlinear waveform fitting for individual seismograms based on the Neighborhood Algorithm. In the second stage, we retrieved multimode phase speed maps using the linearized inversions based on the method of surface-wave tomography incorporating approximate effects of finite frequency. In the third stage, localized multimode dispersion curves derived from the sets of multimode phase speed maps were used to construct local 1-D S-wave profiles, including radial anisotropy, which formed a final 3-D S-wave speed model beneath Eastern Eurasia including Mongolia. The dataset utilized in this study consists of seismic waveforms from over 1655 teleseismic events (Mw≥5.8) that were recorded at permanent and temporary stations in and around Mongolia between 2009 and 2021. We reconstructed phase speed maps with 2.0◦ × 2.0◦ grids (or greater size, depending on path coverage for each period) by covering the study region with many ray paths; e.g., about 70,000 paths for the fundamental-mode Rayleigh waves, 40,000 paths for the fundamental-mode Love waves at a period of 100 s, and about 5,000–40,000 paths for higher modes of both Rayleigh and Love waves. Broadband seismograms from the permanent and temporary seismic networks in Mongolia, as well as nearby stations of the Global Seismograph Network and temporary regional networks in Eurasia, were combined to retrieve a highresolution S-wave model covering entire Mongolia. The new 3-D model gave us new insight into the large-scale tectonics of the Mongolian region, including the western margin of the Amurian plate. The obtained 3-D S-wave model shows significant lateral variations of S-wave speeds in the uppermost mantle beneath Mongolia, indicating the structural differences between western and eastern Mongolia. In the radial anisotropy model, SH waves tend to be faster than SV waves in most areas of the Mongolian upper mantle above 100 km depth, except for the northeast of the Altay Mountains. The low-velocity anomalies are seen in western Mongolia beneath the Hangay Dome and the northern Altay Mountains. The low-velocity anomaly in the Altay Mountains persists to a depth of about 100 km, which may be linked to the northern extension of the collision tectonics between Asia and India. A large-scale low velocity beneath the northeast of the Hangay Dome persists to around 150 km depth, accompanied by significant radial anisotropy with slower SV velocity than SH in the top 100 km that may result from finely layered or laminated heterogeneity, possibly including partially molten layers. High-velocity anomalies corresponding to the lithosphere can be seen in the uppermost mantle of eastern Mongolia, reflecting the relatively stable tectonics in this region, in contrast to the tectonically active regions of central-western Mongolia. The differential motion between eastern and western Mongolia may be related to such regional variations of the upper mantle structure and dynamics beneath the Eurasian and Amurian plates
Clinical outcome, radiological findings, and genetic features of IDH-mutant brainstem glioma in adults
No full textBackground With the recent advent of genetic testing, IDH-mutant glioma has been found among adult brainstem gliomas. However, the clinical outcome and prognosis of IDH-mutant brainstem gliomas in adults have not been elucidated. This study aimed to investigate the clinical outcome, radiological findings, and genetic features of adult patients with IDH-mutant diffuse brainstem gliomas. Methods Data from adult patients with brainstem glioma at Hokkaido University Hospital between 2006 and 2022 were retrospectively analyzed. Patient characteristics, treatment methods, genetic features, and prognosis were evaluated. Results Of 12 patients with brainstem glioma with proven histopathology, 4 were identified with IDH mutation. All patients underwent local radiotherapy with 54 Gray in 27 fractions combined with chemotherapy with temozolomide. Three patients had IDH1 R132H mutation and one had IDH2 R172G mutation. The median progression-free survival and overall survival were 68.4 months and 85.2 months, respectively, longer than that for IDH-wildtype gliomas (5.6 months and 12.0 months, respectively). At the time of initial onset, contrast-enhanced lesions were observed in two of the four cases in magnetic resonance imaging. Conclusion As some adult brainstem gliomas have IDH mutations, and a clearly different prognosis from those with IDH-wildtype, biopsies are proactively considered to confirm the genotype
Aristotle's Natural Teleology : Compatibility between Simple Necessity and Hypothetical Necessity
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Singer's critique of Rawls' reflective equilibrium
No full textこの論文は，ピーターシンガー（Peter Singer）によるジョン・ロールズ（John Rawls）の反照的均衡の批判を論じている。ロールズが反照的均衡の概念を紹介して以来，今でも有力な道徳的正当化の方法の一つとして取り上げられている。シンガーは反照的均衡を批判する代表的な学者の一人であり，現在もこの立場を維持している。この論文では，熟考された判断（常識道徳），記述・当為（is-ought）の問題を中心にシンガーの立場を紹介する。次に，シジウィックの‘The Methods of Ethics’に対するシンガーとロールズの解釈の違い，そしてシンガーの‘The Expanding Circle: Ethics, Evolution, and Moral Progress’を主題とし，反照的均衡が正当化されない理由は何かを論じるのが本論文の要旨である
Rebuttal to the Levelling-Down Objection : A Reconsideration of “Slogan”
No full text本稿はDrake Parfitによる水準低下批判について分析し，先行研究による批判と筆者独自の批判を取り上げることで，水準低下批判（Leveling-Down Objection）およびその根底にあるSloganを批判し，平等主義を擁護した。水準低下批判はDerek Parfitが論文「平等か優先か」の中で論じた概念で，平等それ自体に価値があると考える目的論的平等主義への反論として考案されたものである。Parfitによれば，平等はそれ自体で価値を持つということは，不平等の消滅もそれ自体で価値を持つことを意味する。そのため，境遇の良い人の生活水準を境遇の悪い人のと同じ水準に下げること（水準低下）による不平等の消滅は最終的に悪い帰結をもたらすが，不平等が消滅し，何かしら道徳的善さが生じることになる。Parfitは目的論的平等主義はその批判を回避できないとし，代わりに優先主義を支持すべきだと論じた。しかし，水準低下批判及びその基礎にあるSloganのどれも理論的な基礎が欠けており，比例正義や非同一性問題をはじめとする反論に直面しなければならない。ゆえに，Parfitの平等主義批判は説得力のあるものではないと結論づける
One-sided and Unsuccessful Communication and The Analyst's Poosition in Communication Analisis : The case study of “My Broken Mariko”
No full text本稿は，コミュニケーション分析における分析者の立場の再考と，それを踏まえた，一方的で，失敗しているにもかかわらず外部からは成功しているかのように見える「不成功」なコミュニケーションについての記述を試みるものである。そのための具体例としてマンガ『マイ・ブロークン・マリコ』を取り上げ，作品内のコミュニケーションを追いながら，実際には成立していない会話が成立しているかのように描かれていることを示す。また，作品内のコミュニケーションに直接参加することができない一方で登場人物と視点や注意を共有する読者，分析者の立場を考えるにあたってマンガ表現における「視点」の問題が重要であることを指摘した上で，映画へのアダプテーションによってマンガで描かれていた視点やコミュニケーションの在り方が変化していることに触れる。まとめとして，発話の受け手でありながら直接的な参与者である話し手や受け手とは異なる階層に立つ分析者の立場を考えるにあたって，必然的にその立場に立たされるフィクションを使用した分析は有用であり，またそれを踏まえた上で，「不成功」なコミュニケーションのようなものからコミュニケーション分析の新たな視点が生まれる可能性があることを指摘する
Minimal cylinders in the three-dimensional Heisenberg group
Get PDFWe study minimal cylinders in the three-dimensional Heisenberg group Nil3 using the generalized Weierstrass type representation, the so-called loop group method. We characterize all non-vertical minimal cylinders in terms of pairs of two closed plane curves which have the same signed area. Moreover, as a byproduct of the construction, spacelike CMC cylinders in the three-dimensional Minkowski space can also be obtained