688 research outputs found

    "Dynamic Optimality of Yield Curve Strategies"

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    This paper formulates and analyzes a dynamic optimization problem of bond portfolios within Markovian Heath-Jarrow-Morton term structure models. In particular, we investigate optimal yield curve strategies analytically and numerically, and provide theoretical justification for a typical strategy which is recommended in practice for an expected change in the shape of the yield curve. In the numerical analysis, we utilize a new technique based on the asymptotic expansion approach in order to increase efficiency in computation.

    Unboundedness of solutions of time-dependent differential systems of parabolic type

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    Unboundedness of matrix solutions of time-dependent differential systems of parabolic type is studied. The key tool is to use the Picone-type identity for strongly elliptic systems. The results about oscillations of solutions are also derived

    Nanoscale Infrared Imaging Analysis of Carbonaceous Chondrites to Understand Organic-Mineral Interactions During Aqueous Alteration

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    Organic matter in carbonaceous chondrites is distributed in fine-grained matrix. To understand pre- and postaccretion history of organic matter and its association with surrounding minerals, microscopic techniques are mandatory. Infrared (IR) spectroscopy is a useful technique, but the spatial resolution of IR is limited to a few micrometers, due to the diffraction limit. In this study, we applied the high spatial resolution IR imaging method to CM2 carbonaceous chondrites Murchison and Bells, which is based on an atomic force microscopy (AFM) with its tip detecting thermal expansion of a sample resulting from absorption of infrared radiation. We confirmed that this technique permits 30 nm spatial resolution organic analysis for the meteorite samples. The IR imaging results are consistent with the previously reported association of organic matter and phyllosilicates, but our results are at much higher spatial resolution. This observation of heterogeneous distributions of the functional groups of organic matter revealed its association with minerals at 30 nm spatial resolution in meteorite samples by IR spectroscopy

    Effect of pressure on the magnetic, transport, and thermal-transport properties of the electron-doped manganite CaMn1x_{1-x}Sbx_{x}O3_{3}

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    We have demonstrated the effect of hydrostatic pressure on magnetic and transport properties, and thermal transport properties in electron-doped manganites CaMn1x_{1-x}Sbx_{x}O3_{3}. The substitution of Sb5+^{5+} ion for Mn 4+^{4+}site of the parent matrix causes one-electron doping with the chemical formula CaMn12x4+^{4+}_{1-2x}Mnx3+^{3+}_{x}Sbx5+^{5+}_{x}O3_{3} accompanied by a monotonous increase in unit cell volume as a function of xx. Upon increasing the doping level of Sb, the magnitudes of both electrical resistivity and negative Seebeck coefficient are suppressed at high temperatures, indicating the electron doping. Anomalous diamagnetic behaviors at x=0.05x=0.05 and 0.08 are clearly observed in field cooled dc magnetization. The effect of hydrostatic pressure on dc magnetization is in contrast to the chemical pressure effect due to Sb doping. The dynamical effect of ac magnetic susceptibility measurement points to the formation of the magnetically frustrated clusters such as FM clusters embedded in canted AFM matrix.Comment: 12 pages,11 figures, 3 table

    Effect of pressure on the magnetic, transport, and thermal-transport properties of the electron-doped manganite CaMn1x_{1-x}Sbx_{x}O3_{3}

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    We have demonstrated the effect of hydrostatic pressure on magnetic and transport properties, and thermal transport properties in electron-doped manganites CaMn1x_{1-x}Sbx_{x}O3_{3}. The substitution of Sb5+^{5+} ion for Mn 4+^{4+}site of the parent matrix causes one-electron doping with the chemical formula CaMn12x4+^{4+}_{1-2x}Mnx3+^{3+}_{x}Sbx5+^{5+}_{x}O3_{3} accompanied by a monotonous increase in unit cell volume as a function of xx. Upon increasing the doping level of Sb, the magnitudes of both electrical resistivity and negative Seebeck coefficient are suppressed at high temperatures, indicating the electron doping. Anomalous diamagnetic behaviors at x=0.05x=0.05 and 0.08 are clearly observed in field cooled dc magnetization. The effect of hydrostatic pressure on dc magnetization is in contrast to the chemical pressure effect due to Sb doping. The dynamical effect of ac magnetic susceptibility measurement points to the formation of the magnetically frustrated clusters such as FM clusters embedded in canted AFM matrix.Comment: 12 pages,11 figures, 3 table

    Ettingshausen and Nernst effects in mixed state of YBa_2Cu_3O_<7-δ>(High Field Superconductors)

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    The dissipative behaviors under the Lorentz force and the thermal force are investigated for the same sample of QMG-YBa_2Cu_3O_ by measuring the Ettingshausen and the Nernst effects, respectively, and compared with each other. The value of S_φ(T) obtained from the Nernst effect is found to be smaller than that obtained from the Ettingshausen effect, which suggests that the viscosity is not the same for the vortex motions under the Lorentz force and the thermal force. The QMG-YBa_2Cu_3O_ always includes precipitates of Y_2BaCuO_5 phase which are finely dispersed by an addition of Pt. In order to investigate the effect of Y_2BaCuO_5 phase on the vortex motion, the Ettingshausen effect is also measured for the sample with 0.5 mass% Pt addition. The anisotropy of the dissipation under the thermal force is investigated by measuring the Nernst effect for the configurations; (1) H//c, (dT/dx)//ab, (2) H//ab, (dT/dr)//ab and (3) H//ab, (dT/dr)//c. For these vortex motions, viscosities are found to be in the ratio 30 : 1 : 100. The velocity of vortices is estimated from the Nernst field. Furthermore, using S_φ(T) the magnitude of viscosity is estimated to be 0.5-3×10^ N s/m^2 in the temperature range from 90 to 75 K and the magnetic field of 13 T parallel to the c-axis

    映画技術の側面から見た1080/24Pの必然性と将来性

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    現在1080/24P(またはHD24P)という技術が注目を浴びている。それはデジタルハイビジョン方式により十分な解像度を得たビデオテクノロジーと、毎秒24コマ(24fs=24 frame per second)という映画だけが持つフレームレートの世界を両立させる規格である。映像の世界において24fsは、ある意味では非常に中途半端な速度である。それにも拘らずなぜ、1080/24Pがこれほど注目されるのであろうか。その回答のひとつに「フィルムライク」という表現がある。フィルムライクという言葉にはどんな意味が存在するのだろうか。こうしたさまざまな疑問に対して、一般的なビデオ技術の側からでなく、映画技術および映画表現の側から捉えなおすことにより、より具体的な理解と、映画・ビデオを含む映像技術および表現の将来を描くことが本論のテーマである。24fsはいかにして構築されたか、それは理想的な数値なのか、そして映画とテレビと軸とする現代の映像世界は24fsとどのように拘わっているかを考察することにより、映像技術の「現在」を正確に把握していきたい。それはまさしく、24P以外の選択肢による新しい映画作りの可能性への示唆にもなると考えるからである。Nowadays, many people engaged in both video and film industry are paying attention to a ground-breaking video technology called the 1080/24P (1920 1080 square pixels and 24 progressive frames per second) format. This is a happy compromise from a video technology being able to reach enough resolution with 1080/60i digital Hi-Vision (HDTV) format and a characteristic frame-rate of 24fs (frame per second) in the movie world. The 24 frame-rate is a somewhat strange ratio from the viewpoint of 30 frame-rate video world, but the 1080/24P technology has recently become a major topic. One of the reasons is represented by one magic word, "film-like". This paper will discuss the relationship between the word of "film-like" and the specific number of 24fs by examining historical facts, events and also technical back-grounds. I believe this information will show us an actual visual world and suggest the possibility of another way of making films

    "Dynamic Optimality of Some Yield Curve Strategies" (in Japanese)

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    This paper formulates and analyzes a dynamic optimization problem of bond portfolios within the Markovian Heath-Jarrow-Morton term structure models. In particular we find the exact comdition under which the so-called barbell/bullet strategies become optimal relative to the forecasted term structure movements.
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