The Redshift Evolution of the Relation between Stellar Mass, Star Formation Rate, and Gas Metallicity of Galaxies

We investigate the relation between stellar mass ($M_\star$), star formation rate (SFR), and metallicity ($Z$) of galaxies, so called the fundamental metallicity relation, in the galaxy sample of the Sloan Digital Sky Survey Data Release 7. We separate the galaxies into narrow redshift bins and compare the relation at different redshifts, and find statistically significant ($> 99$%) evolution. We test various observational effects that might cause seeming $Z$ evolution, and find it difficult to explain the evolution of the relation only by the observational effects. In the current sample of low redshift galaxies, galaxies with different $M_\star$ and SFR are sampled from different redshifts, and there is degeneracy between $M_\star$/SFR and redshift. Hence it is not straightforward to distinguish a relation between $Z$ and SFR from a relation between $Z$ and redshift. The separation of the intrinsic relation from the redshift evolution effect is a crucial issue to understand evolution of galaxies.Comment: 8 pages, 12 figures, 1 table, accepted for publication in ApJ, added discussions about the noise in the galaxy spectr

Simple Stratification of Hepatocellular Carcinoma Surveillance after Direct-acting Antiviral Therapy for Chronic Hepatitis C

Reports on surveillance systems useful for determining the risk of developing hepatocellular carcinoma （HCC） after direct-acting antiviral （DAA） treatment for hepatitis C have been published. Liver cirrhosis （LC） is a high-risk factor for HCC, but the evaluation frequency necessary for patients with chronic hepatitis （CH） remains unknown. Here, we aimed to identify how frequent CH patients should be evaluated for HCC, with particular emphasis on patients achieving a sustained virological response （SVR） with DAA treatment. Data were collected pre-treatment （Pre） and at the time of SVR for 141 patients with hepatitis C receiving DAA treatment. We defined LC by a platelet （PLT） count ≤10×104/µl, and CH was defined by a PLT count of ＞10×104/µl. The incidence of HCC in patients with CH after achieving SVR was retrospectively evaluated. In total, 128 patients （CH, n＝102; LC, n＝26） achieved SVR, and 13 developed HCC after SVR during the follow-up period （mean, 748 days）. Although fibrosis-4 （FIB-4） index, the presence of α-fetoprotein, and prothrombin time were significant risk factors for HCC in patients with CH in the univariate analysis, only the Pre-FIB-4 index was an independent predictive factor for HCC development in the multivariate analysis （p＝0.04）. An FIB-4 index ≥3 was a significant risk factor for HCC （p＝0.005）. The cumulative risk for HCC at 1000 days was 2.6％ and 24.2％ in the FIB-4 index ＜3 and FIB-4 index ≥3 groups, respectively （p＝0.004）. Frequent HCC examination is recommended for FIB-4 index ≥3 CH patients who obtain SVR after DAA treatment

Persistence of Cryoglobulinemia in Patients with Chronic Hepatitis C after Successful Treatment with Direct-acting Antivirals

Hepatitis C virus（HCV）infection can cause chronic liver disease; it has also been associated with lymphoproliferative disorders（LPDs）, such as cryoglobulinemia and B-cell non-Hodgkin’s lymphoma. Our previous studies suggested that cryoglobulinemia, high titer of rheumatoid factor（RF）, and hypocomplementemia are immunological markers of LPDs. In addition, recent therapies with direct-acting antivirals（DAAs）have achieved high rates of sustained virological response（SVR）in patients with chronic hepatitis C（CH-C）. This study analyzed the efficacy of DAA therapy in CH-C patients with cryoglobulinemia, and the association of biochemical and other immune markers for LPDs with persistence of cryoglobulinemia in patients after DAA therapy. Of 226 patients tested, 31（13.7％）had cryoglobulinemia prior to receiving DAAs, and these individuals showed lower complement 4 levels, decreased complement hemolytic activity, and higher IgM than patients without cryoglobulinemia. Of the 24 cryoglobulinemia-positive patients（83％）who could be followed for 24 weeks, 20 became cryoglobulinemia negative after the therapy. The remaining four patients retained the abnormal LPD markers, indicating the possibility of long-term LPD persistence even following successful eradication of HCV in CH-C patients. Thus, long-term follow-up is recommended to avoid exacerbation of extrahepatic manifestations as well as new events

ダイキボ マルチエージェント シミュレーション ニ ヨル オクガイ ヒナン ジッケン ノ カクチョウ

京都大学0048新制・課程博士博士(情報学)甲第14767号情博第342号新制||情||64(附属図書館)UT51-2009-D479京都大学大学院情報学研究科社会情報学専攻(主査)教授 石田 亨, 教授 喜多 一, 教授 多々納 裕一学位規則第4条第1項該当Doctor of InformaticsKyoto UniversityDA

Learning From Humans: Agent Modeling With Individual Human Behaviors

Multiagent-based simulation (MABS) is a very active interdisciplinary area bridging multiagent research and social science. The key technology to conduct truly useful MABS is agent modeling for reproducing realistic behaviors. In order to make agent models realistic, it seems natural to learn from human behavior in the real world. The challenge presented in this paper is to obtain an individual behavior model by using participatory modeling in the traffic domain. We show a methodology that can elicit prior knowledge for explaining human driving behavior in specific environments, and then construct a driving behavior model based on the set of prior knowledge. In the real world, human drivers often perform unintentional actions, and occasionally, they have no logical reason for their actions. In these cases, we cannot rely on prior knowledge to explain them. We are forced to construct a behavior model with an insufficient amount of knowledge to reproduce the driving behavior. To construct such individual driving behavior model, we take the approach of using knowledge from others to complement the lack of knowledge from the target. To clarify that the behavior model including prior knowledge from others offers individuality in driving behavior, we experimentally confirm that the driving behaviors reproduced by the hybrid model correlate reasonably well with human behavior

GaAs dot-wire coupled structures grown by selective area metalorganic vapor phase epitaxy and their application to single electron devices

We describe a method for fabricating GaAs dot arrays and dot-wire coupled structures having periodic nanofacets which uses selective area metalorganic vapor phase epitaxy. First, a thin GaAs buffer layer and an AlGaAs layer are grown on a masked substrate having wirelike openings with periodic width modulation. The width of AlGaAs wirelike structure is naturally squeezed by the periodic combination of nanofacets, and its top (001) surface is partially isolated by a self-limited region. Next, an AlGaAs/GaAs quantum well structure is fabricated on the substrate to form dots on the narrower top terraces, wires on the wider terraces, and ridge wires in the self-limited region. Cathodoluminescence images clearly showed dot arrays and dot-wire coupled structures were formed using this method. A single electron transistor with the same structure was also fabricated, and clear Coulomb blockade oscillation was observed. We also describe single electron tunneling devices with these dot arrays and dot-wire coupled structures