Bayesian Approach to Find a Long-Term Trend in Erratic Polarization Variations Observed in Blazars

We developed a method to separate a long-term trend from observed temporal variations of polarization in blazars using a Bayesian approach. The temporal variation of the polarization vector is apparently erratic in most blazars, while several objects occasionally exhibited systematic variations, for example, an increase of the polarization degree associated with a flare of the total flux. We assume that the observed polarization vector is a superposition of distinct two components, a long-term trend and a short-term variation component responsible for short flares. Our Bayesian model estimates the long-term trend which satisfies the condition that the total flux correlates with the polarized flux of the short-term component. We demonstrate that assumed long-term polarization components are successfully separated by the Bayesian model for artificial data. We applied this method to photopolarimetric data of OJ 287, S5 0716+714, and S2 0109+224. Simple and systematic long-term trends were obtained in OJ 287 and S2 0109+224, while no such a trend was identified in S5 0716+714. We propose that the apparently erratic variations of polarization in OJ 287 and S2 0109+224 are due to the presence of the long-term polarization component. The behavior of polarization in S5 0716+714 during our observation period implies the presence of a number of polarization components having a quite short time-scale of variations.Comment: 12 pages, 7 figures, accepted for publication in PAS

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

Climatic and atmospheric histories over the past 700,000 years from the Dome Fuji deep ice core, Antarctica

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月26日（月） 国立国語研究所 ２階講

A double peak of the coercive force near the compensation temperature in the rare earth iron garnets

The behavior of the coercive force, Hc, of ferrimagnets near the compensation temperature, Tcomp, for polycrystalline rare earth iron garnets R3Fe5O12 (R = Gd, Tb, Dy, Ho and Er) has been studied in detail. The present experimental results have verified the double peak in Hc near Tcomp for these rare earth iron garnets R3Fe5O12. For Dy3Fe5O12, the experimental values are Tcomp = 224 K, Hc (max) = 600 Oe at Tcomp ±δ K andδ ≈ 10 K. The two peaks of Hc arise at 214 and 232 K. The appearance of the double peak of Hc is an intrinsic and characteristic property for R3Fe5O12. The results can be understood on the basis of a simple model. The hysteresis loop in the magnetization is caused by rotation of single domain under the influence of crystalline anisotropy rather than domain wall displacements of the multi-domain structure. The rare earth ion behaves as superimposed paraprocess under the influence of weak exchange field produced by iron sublattices and an external magnetic field

Ice Core Records of Antarctic Warming Events in the Last Glacial Period

第3回極域科学シンポジウム　横断セッション「海・陸・氷床から探る後期新生代の南極寒冷圏環境変動」11月26日（月） 国立国語研究所 ２階講

Severe accidental colchicine poisoning by the autumn crocus: A case of successful treatment

AbstractBackgroundThe common garden plant autumn crocus contains colchicine and its derivatives. Colchicine poisoning causes abdominal cramps and diarrhea within hours. Several days later, multiorgan failure, pancytopenia, and cardiovascular collapse occur.1,2 Severe colchicine poisoning is associated with high mortality.Case reportA 63-year-old woman who accidentally ingested an autumn crocus, which contained ∼0.38 mg colchicine, had severe vomiting and was taken to an emergency center. She presented with symptoms of gastroenterocolitis within 1 hour of ingestion, and bone marrow hypoplasia with pancytopenia developed on the 3rd day after ingestion. We continued administration of granulocyte colony-stimulating factor (300 μg) for 5 days until we confirmed that the patient's white blood cell count was increasing. Also, there was focal and segmental intestinal ischemia and some cakes of charcoal remained in the intestinal tract. Therefore, we presumed that nonocclusive mesenteric ischemia was caused by hypotension with severe dehydration, although pseudo-obstruction due to the activated charcoal may have been a contributing factor. We were able to promptly intervene to treat paralytic ileus and gastrointestinal edema before anticipated worsening of abdominal compartment syndrome, by conducting open peritoneal drainage. Despite severe poisoning, our patient survived with intensive care. Conclusion: Colchicine intoxication may lead to a sudden and extreme critical course. Therefore, as there is no means to predict prognosis from initial severity of symptoms at onset, we suggest that all patients suspected of colchicine intoxication should be managed in hospital with continuous vital sign monitoring and frequent laboratory testing for at least a few days after ingestion

Detection of Polarimetric Variations Associated with the Shortest Time-Scale Variability in S5 0716+ + 714

We present the result of near-infrared and optical observations of the BL Lac object S5 0716$+$714 carried out by the KANATA telescope. S5 0716$+$714 has both a long term high-amplitude variability and a short-term variability within a night. The shortest variability (microvariability) time-scale is important for understanding the geometry of jets and magnetic field, because it provides a possible minimum size of variation sources. Here, we report the detection of 15-min variability in S5 0716$+$714, which is one of the shortest time-scales in optical and near-infrared variations observed in blazars. The detected microvariation had an amplitude of $0.061{\pm}0.005$ mag in $V$ band and a blue color of $\Delta(V-J)=-0.025{\pm}0.011$. Furthermore, we successfully detected an unprecedented, short time-scale polarimetric variation which correlated with the brightness change. We revealed that the microvariation had a specific polarization component. The polarization degree of the variation component was higher than that of the total flux. These results suggest that the microvariability originated from a small and local region where the magnetic field is aligned.Comment: 5 pages, 4 figures; Publications of the Astronomical Society of Japan letter accepte

カンセツ リウマチ ニ タイスル メトトレキセート チリョウチュウ ニ コウド ノ ハンケッキュウ ゲンショウ オ キタシ シボウ シタ 5レイ ノ ケントウ

Background : Methotrexate （MTX） is placed as an anchor drug of treatment for rheumatoid arthritis （RA）. However, many cases suffered from side effects of MTX such as interstitial pneumonia and hematological toxicity. We investigated ５ cases that died of severe pancytopenia under treatment with low-dose MTX for RA. Methods : We reviewed the clinical features of ５ cases that developed severe pancytopenia and were transferred to Tokushima Prefectural Central Hospital under treatment with low-dose MTX for RA from ２０１１-２０１５. Results : All the cases were women, and were under treatment with low-dose MTX. The periods of medication of MTX were not clear. All the cases had renal insufficiency, and had a severe infection induced by pancytopenia and some cases developed disseminated intravascular coagulation （DIC）. At once we started intensive care, but all patients died in a short term. Conclusions : Women, the elderly, and renal insufficiency can be risk factors of severe pancytopenia induced by MTX even if low dosage. We should carefully treat these patients with MTX

Dwarf Novae in the Shortest Orbital Period Regime: I. A New Short Period Dwarf Nova, OT J055717+683226

We report the observation of a new dwarf nova, OT J055717+683226, during its first-ever recorded superoutburst in December 2006. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67+/- 0.03 min (0.05324+/-0.00002 d). The next superoutburst was observed in March 2008. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be ~480 d. The supercycle is much shorter than those of WZ Sge-type dwarf novae having supercycles of >~ 10 yr, which are a major population of dwarf novae in the shortest orbital period regime (<~85 min). Using a hierarchical cluster analysis, we identified seven groups of dwarf novae in the shortest orbital period regime. We identified a small group of objects that have short supercycles, small outburst amplitudes, and large superhump period excesses, compared with those of WZ Sge stars. OT J055717+683226 probably belongs to this group.Comment: 14 pages, 11 figures, accepted for publication in PAS