Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope. I. Correlations between Flux, Color, and Polarization

We report on the correlation between the flux, color and polarization variations on time scales of days--months in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for >10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days--weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux--color correlation, the correlation of the flux and polarization degree was relatively weak; only 10 objects showed significant positive correlations. Rotations of polarization were detected only in three objects: PKS 1510-089, 3C 454.3, and PKS 1749+096, and possibly in S5 0716+714. We also investigated the dependence of the degree of variability on the luminosity and the synchrotron peak frequency, \nu_peak. As a result, we found that lower luminosity and higher \nu_peak objects had smaller variations in their amplitudes both in the flux, color, and polarization degree. Our observation suggests the presence of several distinct emitting sources, which have different variation time-scales, colors, and polarizations. We propose that the energy injection by, for example, internal shocks in relativistic shells is a major factor for blazar variations on time scales of both days and months.Comment: 39 pages, accepted for publication in PAS

Early Spectroscopy of the 2010 Outburst of U Scorpii

We present early spectroscopy of the recurrent nova U~Sco during the outburst in 2010. We successfully obtained time-series spectra at $t_{\rm d}=$0.37--0.44~d, where $t_{\rm d}$ denotes the time from the discovery of the present outburst. This is the first time-resolved spectroscopy on the first night of U Sco outbursts. At $t_{\rm d}\sim 0.4$~d the H$\alpha$ line consists of a blue-shifted ($-5000$ km s$^{-1}$) narrow absorption component and a wide emission component having triple peaks, a blue ($\sim -3000$ km s$^{-1}$), a central ($\sim 0$ km s$^{-1}$) and a red ($\sim +3000$ km s$^{-1}$) ones. The blue and red peaks developed more rapidly than the central one during the first night. This rapid variation would be caused by the growth of aspherical wind produced during the earliest stage of the outburst. At $t_{\rm d}=1.4$~d the H$\alpha$ line has a nearly flat-topped profile with weak blue and red peaks at $\sim \pm 3000$ km s$^{-1}$. This profile can be attributed to a nearly spherical shell, while the asphericity growing on the first night still remains. The wind asphericity is less significant after $t_{\rm d}=9$ d.Comment: 5 pages, 3 figures, Accepted for publication of PASJ Letter

Thalidomide Prevents the Progression of Peritoneal Fibrosis in Mice

Thalidomide is clinically recognized as a therapeutic agent for multiple myeloma and has been known to exert anti-angiogenic actions. Recent studies have suggested the involvement of angiogenesis in the progression of peritoneal fibrosis. The present study investigated the effects of thalidomide on the development of peritoneal fibrosis induced by injection of chlorhexidine gluconate (CG) into the mouse peritoneal cavity every other day for 3 weeks. Thalidomide was given orally every day. Peritoneal tissues were dissected out 21 days after CG injection. Expression of CD31 (as a marker of endothelial cells), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), α-smooth muscle actin (as a marker of myofibroblasts), type III collagen and transforming growth factor (TGF)-β was examined using immunohistochemistry. CG group showed thickening of the submesothelial zone and increased numbers of vessels and myofibroblasts. Large numbers of VEGF-, PCNA-, and TGF-β-positive cells were observed in the submesothelial area. Thalidomide treatment significantly ameliorated submesothelial thickening and angiogenesis, and decreased numbers of PCNA- and VEGF-expressing cells, myofibroblasts, and TGF-β-positive cells. Moreover, thalidomide attenuated peritoneal permeability for creatinine, compared to the CG group. Our results indicate the potential utility of thalidomide for preventing peritoneal fibrosis

Stabilization of Pseudomonas aeruginosa Cytochrome c551 by Systematic Amino Acid Substitutions Based on the Structure of Thermophilic Hydrogenobacter thermophilus Cytochrome c552

A heterologous overexpression system for mesophilic Pseudomonas aeruginosa holocytochrome c551 (PA c551) was established using Escherichia coli as a host organism. Amino acid residues were systematically substituted in three regions of PA c551 with the corresponding residues from thermophilic Hydrogenobacter thermophilus cytochrome c552 (HT c552), which has similar main chain folding to PA c551, but is more stable to heat. Thermodynamic properties of PA c551 with one of three single mutations (Phe-7 to Ala, Phe-34 to Tyr, or Val-78 to Ile) showed that these mutants had increased thermostability compared with that of the wild-type. Ala-7 and Ile-78 may contribute to the thermostability by tighter hydrophobic packing, which is indicated by the three dimensional structure comparison of PA c551 with HT c552. In the Phe-34 to Tyr mutant, the hydroxyl group of the Tyr residue and the guanidyl base of Arg-47 formed a hydrogen bond, which did not exist between the corresponding residues in HT c552. We also found that stability of mutant proteins to denaturation by guanidine hydrochloride correlated with that against the thermal denaturation. These results and others described here suggest that significant stabilization of PA c551 can be achieved through a few amino acid substitutions determined by molecular modeling with reference to the structure of HT c552. The higher stability of HT c552 may in part be attributed to some of these substitutions.This work was supported in part by grants from the Japanese Ministry of Education, Science and Culture

Quantitative analysis of major elements in igneous rocks with X-ray fluorescence spectrometer “ZSX primus II” using a 1:10 dilution glass bead

Detailed procedures of sample processing including preparation of a 1: 10 dilution glass bead and evaluations of calibration lines of the X-ray fluorescence spectrometer for major element compositions of igneous rock samples are presented. We used 11 igneous rock standard samples of the Geological Survey of Japan and the synthetic material for the calibration. A powdered rock sample ignited at 900 ° C for four hours and lithium tetraborate as an alkali flux ignited at 700 ° C for four hours are weighed 0.4000 ± 0.0001 g and 4.0000 ± 0.0001 g, respectively. The mixture of rock powder sample and lithium tetraborate is put into a platinum crucible and fused to a glass bead. The calibration lines for basalts and andesites named "Major12" analyze 10 major elements such as Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K and P in 10 minutes. The result of repeated analyses of six standard materials shows that the relative standard deviations are less than 3% and relative errors are less than 1.2%. Therefore, the calibration lines "Major12" are sufficient to be applied to routine measurement of igneous rocks. For analysis of ultramafic rocks, another set of calibration lines "majorOl\u27\u27 was made based on standard samples including synthesized materials of SiO, and MgO reagents, and the calibration lines cover wider Si, Mg, Ni and Cr ranges than "Major12". The calibration lines "majorOl\u27\u27 successfully reproduced concentrations of nine major element compositions (Si, Ti, Al, Fe, Mn, Mg, Ca, Ni, Cr) of the standard samples of ultramafic rocks

Accumulation of Ulva spp. (Chlorophyta) and other seaweed thalli on the shallow sea bottom of Hiroshima Bay (A preliminary survey)

広島湾奥部の大野瀬戸周辺の砂泥海底域で，小型底曳き網（ナマコ桁網）と潜水により，アオサ類等をはじめとする海藻類の堆積状況を調査した。38種の海藻・海草類が採集されたが，現存量では底曳き網による採集物の64～100％をアオサ類が占めていた。アオサ類は水深5m以浅で最も多く採集され，砂浜・干潟に連続する海底勾配の緩やかな浅海底がアオサ類の増殖帯になっていると考えられた。Biomass of Ulva spp. (Chlorophyta) causing ‘green tide’ and other seaweeds accumulated on shallow sea bottom in inner area of Hiroshima Bay was estimated by trawl-net and SCUBA surveys. Thirty-eight species of seaweed and seagrass was sampled, but Ulva spp. was dominant occupying 64-100 % in biomass of all samples. Ulva spp. was sampled most abundantly at the stations shallower than 5 m, and it was indicated that sea bottom with a gentle slope, and located offshore of sandy beaches or tidal-flats offers a suitable condition for Ulva growth