A unified model of the thermal history of icy planetesimals : Evolution of their temperature, chemical composition and mechanical properties

The present thesis discusses evolution of the temperature, chemical composition, tensile stress and strength of icy planetesimals. The physical properties relevant to the evolution are examined in §2 including 1) the thermal conductivity, 2) the density and 3) the tensile strength. The physical properties of the ice discussed here include the activation energy of evolving processes of volatile molecules, and the effective latent heat of crystallization of amorphous H2O ice. The ice composition in the planetesimal is assumed to be amorphous H2O ice containing CO and CO2 as impurities. The basic equations and results of the numerical calculations are presented in §3. It is revealed that evolution forks into three ways depending on the initial chemical composition of the ice in the planetesimals. They are: 1) Endothermic case, where both CO and CO2 are contained in the ice in significant amount (∼ 10%): The crystallization degree of amorphous H2O ice is 40%, and CO trapped in the fraction of the ice is evolved at the final stage; this CO escapes outside of the planetesimal. On the other hand, CO2 condenses on the surfaces of the dust grains immediately after crystallization of amorphous H2O ice and is preserved. As the crystallization proceeds, sintering of CO2 and H2O takes place, and as a result the tensile strength is enhanced by three orders of magnitude. 2) Exothermic case, where the contents of both CO and CO2 are smaller (∼ 1%) than that of 1): Complete crystallization of the amorphous H2O ice takes place and runaway temperature increase occurs up to about 140K with increasing pressure gradient of CO and CO2 vapors released from the ice. Sintering of CO2 and H2O leads to the tensile strength increased by three orders of magnitude as in the case of 1). 3) No CO2 case, where CO is contained with considerable amount (∼ 1%), but the CO2 content is small (∼ 0%). The evolution in this case is essentially the same as in the case 2) but disruption of the planetesimal occurs depending on the magnitude of the activation energy of surface diffusion of H2O. If the activation energy is large, sintering of H2O proceeds slowly. Consequently the pressure gradient due to CO vapors exceeds the tensile strength at some point, leading to disruption of the planetesimals. Discussion is given in §4 on the implications of the results obtained in the previous sections. It is suggested that emergence of the diversity of planetary systems originates from the diversity of the composition of the ices in molecular clouds from which the plan- etary systems are formed. Namely, difference in the interstellar ice composition leads to different evolution described above. Discussion is given on the influences of the evolution of the tensile strength on collisional accretion to the cores of the Jovian planets. Condi- tions of the growth of the icy planetesimal are presented, and it is shown that the increase in the tensile strength in the icy planetesimals is necessary for forming the cores of the Jovian planets.北海道大学博士学位論文 学位の種類:博士(理学) (課程) 学位授与年月日:平成10年3月25日doctoral thesi

Measurement of the Branching Fraction, Polarization, and CP Asymmetry for B0→ρ+ρ- Decays, and Determination of the Cabibbo-Kobayashi-Maskawa Phase ϕ2

journal articl

Report of the Katsurane Oil Field

東京帝国大学工学部種別:卒業論文改姓改名：高橋竹蔵thesi

A thioacetamide-induced liver fibrosis model for pre-clinical studies in microminipig

Abstract Drug-induced liver fibrosis models are used in normal and immunosuppressed small animals for transplantation and regenerative medicine to improve liver fibrosis. Although large animal models are needed for pre-clinical studies, they are yet to be established owing to drug sensitivity in animal species and difficulty in setting doses. In this study, we evaluated liver fibrosis by administering thioacetamide (TA) to normal microminipig and thymectomized microminipig; 3 times for 1 week (total duration: 8 weeks). The pigs treated with TA showed elevated blood cytokine levels and a continuous liver injury at 8 weeks. RNA-seq of the liver showed increased expression of fibrosis-related genes after TA treatment. Histopathological examination showed degenerative necrosis of hepatocytes around the central vein, and revealed fibrogenesis and hepatocyte proliferation. TA treatment caused CD3-positive T cells and macrophages scattered within the hepatic lobule to congregate near the center of the lobule and increased αSMA-positive cells. Thymectomized pigs showed liver fibrosis similar to that of normal pigs, although the clinical signs tended to be milder. This model is similar to pathogenesis of liver fibrosis reported in other animal models. Therefore, it is expected to contribute to research as a drug discovery and pre-clinical transplantation models

Supplementary Data from Association of CD4⁺ Radiation-Induced Lymphocyte Apoptosis with Fibrosis and Telangiectasia after Radiotherapy in 272 Breast Cancer Patients with >10-Year Follow-up

Supplementary Tables and Figures</p

Supplementary Table 2 from Polymorphisms in Genes Related to Oxidative Stress (<i>CAT, MnSOD, MPO</i>, and <i>eNOS</i>) and Acute Toxicities from Radiation Therapy following Lumpectomy for Breast Cancer

Supplementary Table 2 from Polymorphisms in Genes Related to Oxidative Stress (CAT, MnSOD, MPO, and eNOS) and Acute Toxicities from Radiation Therapy following Lumpectomy for Breast Cance

材料力学教育資料調査分科会報告(工業教育特集号)

rights: 社団法人日本機械学会 rights: 本文データは学協会の許諾に基づきCiNiiから複製したものである relation: IsVersionOf: http://ci.nii.ac.jp/naid/110002470416/textapplication/pdfjournal articl

Association of radiation-induced normal tissue toxicity with a high genetic risk for rheumatoid arthritis

Abstract Background Overlapping genes are involved with rheumatoid arthritis (RA) and DNA repair pathways. Therefore, we hypothesized that patients with a high polygenic risk score for RA will have an increased risk of radiotherapy toxicity given the involvement of DNA repair. Methods Primary analysis was performed on 1494 prostate cancer, 483 lung cancer, and 1820 breast cancer patients assessed for development of radiotherapy toxicity in the REQUITE (validating pREdictive models and biomarkers of radiotherapy toxicity to reduce side effects and improve QUalITy of lifE in cancer survivors) study. Validation cohorts were available from the Radiogenomics Consortium. All patients had undergone curative-intent radiotherapy and were assessed prospectively for toxicity. Germline genomic data was available for all patients, allowing a polygenic risk score to be calculated using 101 RA risk variants. Polygenic risk score was analyzed as a continuous variable and with a more than 90th percentile cutoff. Associations with acute and late standardized total average toxicity (STAT) scores and individual toxicity endpoints were analyzed in multivariable models with preselected adjustment variables. Results Increasing polygenic risk score for RA did not increase the risk of STAT-acute or STAT-late in any cohort. There was an increased risk of late esophagitis in the lung cancer cohort (coefficient = 0.018, P = .01), however this was not validated (P = .79). No individual acute or late toxicity endpoints were statistically significantly associated with polygenic risk score for the prostate or breast cohorts. No statistically significant results were found in the validation cohorts in multivariable models. Conclusions Patients with a high genetic risk for RA do not show increased levels of toxicity after radiotherapy suggesting treatment planning does not need to be modified for such patients