小児髄芽腫における永久脱毛防止のための頭皮線量閾値と照射技法の研究

京都大学新制・課程博士博士(医学)甲第25195号医博第5081号京都大学大学院医学研究科医学専攻(主査)教授 鈴木 実, 教授 椛島 健治, 教授 中本 裕士学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Periodic Vortex Structures in Superfluid 3He-A

We discuss the general properties of periodic vortex arrangements in rotating superfluids. The different possible structures are classified according to the symmetry space-groups and the circulation number. We calculate numerically several types of vortex structures in superfluid 3He-A. The calculations are done in the Ginzburg-Landau region, but the method is applicable at all temperatures. A phase diagram of vortices is constructed in the plane formed by the magnetic field and the rotation velocity. The characteristics of the six equilibrium vortex solutions are discussed. One of these, the locked vortex 3, has not been considered in the literature before. The vortex sheet forms the equilibrium state of rotating 3He-A at rotation velocities exceeding 2.6 rad/s. The results are in qualitative agreement with experiments.Comment: 13 pages, 7 figures, http://boojum.hut.fi/research/theory/diagram.htm

Low-cost and sustainable organic thermoelectrics based on low-dimensional molecular metals

More than 70 % of the primary energy consumed world-wide is wasted, mostly as heat below 100 °C[1]. Thermoelectric generators may convert a substantial amount of this energy into electrical power but high production costs and scarcity of efficient thermoelectric materials operating in this temperature regime have limited large-scale applications so far. Recently, conducting polymers have been proposed as potential candidates to meet these challenges showing appreciable low-temperature thermoelectric performance, but unfortunately suffering from low electrical conductivity due to inherent disorder[2–5]. Herein, crystalline low-dimensional molecular metals are demonstrated as an alternative class of thermoelectric materials combining the advantages of low weight, chemical variety, sustainability and high charge carrier mobility with reduced electronic dimensionality. For the first time determining all relevant thermoelectric quantities on individual organic crystals of both, p-type TTT2I3 and n-type DCNQI2Cu conductors, high power factors and promising figures of merit surpassing values of zT≥0.15 below 40 K are disclosed in this study. The cost-defining power output per active area of a prototypical, all-organic TEG takes unprecedented values of ~mW/cm2 at RT. Violation of the Wiedemann-Franz law and phonon drag effects emerge from the materials’ low-dimensionality and are expected to deliver further thermoelectric enhancement feasible in near future

Observation of Dispersion in the J=2+ Collective Modes of He-3-B by Nonlinear Acoustic Spectroscopy

Parametric excitation yields new results, which cannot be obtained by conventional linear spectroscopy, on the collective modes in superfluid He-3-B. In our ultrasonic experiments, performed in a chamber with four quartz crystals, we have excited the real squashing (J = 2+) modes by two simultaneous sound waves which are mutually either parallel, orthogonal, or antiparallel. Qualitatively these results are in agreement with the theoretical dispersion relation of the J = 2+ modes, and quantitatively we have been able to extract the collective-mode velocities from the line splittings in zero magnetic field

Anomalous Resonance Absorption in Cobalt Ferrite and Co-Zn Binary Ferrites

Microwave resonance absorption in Co-ferrite and Co-Zn binary ferrites at 3.22cm wave-length were observed at high temperature and from room temperature to -195℃, respectively. Resonance absorption in Co-ferrite could not be detected at the temperature below 40℃, because of a large anisotropic energy in Co-ferrite. Such phenomena had not been found in other ferrites, so the resonance experiment was undertaken at high temperatures ranging from 40° to Curie point. In Co-Zn binary ferrites, the absorption disappeared below the temperature of -90℃ and -140℃ in 4CoOZnO5Fe_2O_3 and 3CoO2ZnO5Fe_2O_3, respectively, but the absorption in CoO4ZnO5Fe_2O_3 could be observed down to -186℃. The resonance fields corresponding to the maximum absorption were observed as a function of the temperature. In the case of Co-ferrite, the resonance field corresponding to the maximum absorption gradually decreased with increasing temperature up to ca. 250℃ and then rapidly increased to the Curie point. On the other hand, the absorption amount at first increased linearly with increasing temperature, afterwards passed through a maximum and then decreased rapidly up to the Curie point. The half line widths and g-factor were also obtained as functions of temperature up to the Curie point ; the half line width monotonously decreased with increase of temperature up to the Curie temperature, at which the absorption disappeared. The g-factor increased with the rise of temperature, afterwards passed through broad maximum and then decreased rapidly to the Curie point ; the value of the reonance field just about at the Curie point was found to be within 3300±100 Oe, for which g-factor was determined to be 2.02±0.06 by using the paramagnetic resonance condition

Dosimetric comparison among dynamic conformal arc therapy, coplanar and non-coplanar volumetric modulated arc therapy for single brain metastasis

In the delivery of stereotactic radiosurgery (SRS) by linear accelerator (LINAC), dynamic conformal arc therapy (DCAT) with non-coplanar beams is conventionally used. However, volumetric modulated arc therapy (VMAT) can improve target conformity, thereby decreasing the dose to organs at risk by inversed planning methods, but few studies have directly compared DCAT and VMAT with and without non-coplanar beams in patients with single brain metastasis. We therefore conducted a planning study to compare the dose distribution in DCAT, VMAT using only a coplanar arc (CoVMAT) and VMAT with non-coplanar arcs (NcVMAT) in the treatment of single brain metastasis. DCAT, CoVMAT and NcVMAT plans were created for 15 patients. The three modalities were compared in terms of target conformity, target coverage, the dose to normal brain tissue, monitor units (MUs) and beam-on time. Both conformity indices (RTOG-CI and IP-CI) as well as the D98% of the gross target volume (GTV) were significantly better in the NcVMAT plans than in the DCAT plans. Comparisons of the doses to normal brain tissue revealed that the V20Gy, V15Gy, V12Gy, V10Gy and V5Gy were significantly smaller in the NcVMAT plans than in the plans based on the other two modalities. The MUs of the DCAT and NcVMAT plans were larger than those of the CoVMAT plans, and the beam-on time was longer in the NcVMAT and CoVMAT plans than in the DCAT plans. Compared to the CoVMAT and DCAT plans, NcVMAT plans significantly improved target conformity and reduced the doses to normal brain tissue at V20Gy, V15Gy, V12Gy, V10Gy and V5Gy

Anaplastic Transformation of Follicular Thyroid Carcinoma in Pulmonary Metastasis With Gradually Progressive Intra-tumoral Cavitation: A Case Report

Anaplastic transformation of differentiated thyroid cancer is rare but clinically important because of the dismal prognosis after anaplastic transformation. Therefore, cases and findings of anaplastic transformation must be accumulated, which could ultimately lead to an earlier diagnosis and an improved prognosis. Here, we present a case of anaplastic transformation of follicular thyroid carcinoma (FTC) in a pulmonary metastatic lesion associated with gradually progressive tumor cavitation. The patient with FTC was diagnosed with multiple lung metastases three years after surgery for the primary tumor and metastatic neck lymph nodes. Annual treatment with radioactive iodine resulted in disease stability for 10 years. However, one lung metastasis in the left lower lobe gradually enlarged and was associated with intra-tumoral cavitation. The growing lung nodule was resected and pathologically diagnosed as an anaplastic transformation of FTC. Fourteen months after diagnosis, the patient died of pneumothorax caused by pleural dissemination despite multiple treatment interventions. This case highlights pulmonary metastasis with progressive cavitary lesions as a potential early sign of the anaplastic transformation of differentiated thyroid cancer

Research on the Specific Heat and the Hall Effect of Magnetite

In the present paper, the specific heats and the Hall effects of the artificial and the natural magnetite have been measured at various low temperatures by means of Sykes\u27 method. The specific heats on various heat treated magnetites were measured and it has been confirmed experimentally that the peak appearing on the curves of specific heat versus temperature changes by the heat treatment, if the specimen is heated above 1000°. From the measurement of Hall effect, it has been found that the electric current in magnetite is contributed to only the conduction electron on impurity level ; furthermore, the curve of the Hall constant against temperature has knick points at the transformation temperature at which the intensity of magnetization abruptly decreases