Faint warm debris disks around nearby bright stars explored by AKARI and IRSF

Context: Debris disks are important observational clues for understanding planetary-system formation process. In particular, faint warm debris disks may be related to late planet formation near 1 AU. A systematic search of faint warm debris disks is necessary to reveal terrestrial planet formation. Aims: Faint warm debris disks show excess emission that peaks at mid-IR wavelengths. Thus we explore debris disks using the AKARI mid-IR all-sky point source catalog (PSC), a product of the second generation unbiased IR all-sky survey. Methods : We investigate IR excess emission for 678 isolated main-sequence stars for which there are 18 micron detections in the AKARI mid-IR all-sky catalog by comparing their fluxes with the predicted fluxes of the photospheres based on optical to near-IR fluxes and model spectra. The near-IR fluxes are first taken from the 2MASS PSC. However, 286 stars with Ks<4.5 in our sample have large flux errors in the 2MASS photometry due to saturation. Thus we have measured accurate J, H, and Ks band fluxes, applying neutral density (ND) filters for Simultaneous InfraRed Imager for Unbiased Survey (SIRIUS) on IRSF, the \phi 1.4 m near-IR telescope in South Africa, and improved the flux accuracy from 14% to 1.8% on average. Results: We identified 53 debris-disk candidates including eight new detections from our sample of 678 main-sequence stars. The detection rate of debris disks for this work is ~8%, which is comparable with those in previous works by Spitzer and Herschel. Conclusion: The importance of this study is the detection of faint warm debris disks around nearby field stars. At least nine objects have a large amount of dust for their ages, which cannot be explained by the conventional steady-state collisional cascade model.Comment: 17 pages, 21 figures, accepted for publication in Astronomy and Astrophysic

Conditioned media of glial cell lines induce alkaline phosphatase activity in cultured artery endothelial cells Identification of interleukin-6 as an induction factor

AbstractConditioned media of human glial cell lines induced alkaline phosphatase activity in cultured calf artery endothelial cells. The maximal alkaline phosphatase activity in the culture was comparable to the level in isolated brain capillary endothelial cells. An induction factor in the conditioned media was purified and identified as interleukin-6 from its amino-terminal sequence, molecular weight, amino acid composition and immunoreactivity. Recombinant interleukin-6 had similar induction activity. Our findings raise the possibility that interleukin-6 induces and modulates alkaline phosphatase activity in endothelial cells during normal development of the blood—brain barrier and under certain pathological conditions

Studies on Bile Pigments VIII. A Form of Direct Reacting Bilirubins Appearing in Jaundiced Urine

Separation of the urinary ester-form bilirubin was attempted, and the results obtained may be summarized as follows: 1. A brown pigment was obtained from jaundiced urine by the following procedures; namely, salting out, methanol extraction, chloroform flocculation, and separation on cellulose column. The pigment has been found to be easily soluble in water, displaying the absorption maximum at 420 - 410 m&#956; at pH 7.0, and it also gave a positive reaction both to GMELIN's and EHRLICH's diazo reagents within a minute without the addition of alcohol. These characteristics agree well with those of the socalled ester-form bilirubin. 2. On the basis of the results of paper chromatography and paper electrophoresis, the pigment has been determined to contain no amino acid, steroid, nor reducing substance. Moreover, no glucuronic acid could be detected whether examined in vitro or by paper chromatography together with paper electrophoresis, either.</p

Studies on Silage-Making : (XXII) The Nutrient Contert of Sweet Potato(Ipomoea Batatas L. var. edulis) at the Different Stages and the Quality of Sweet Potato Vine Silage

7月2日植えつけのサツマイモについて,飼料的利用の角度から,ツルとイモの収量を9月28日から11月25日の間6回収穫してその成分と収量を調査するとともに,ツルのサイレージをそれぞれの収穫の時期につくり,その品質ならびに飼料養分を調査した. 1)イモヅルによる養分の最大収穫期は,10月29日で,イモの最大収穫量の期日は11月10日であった. 飼料としてツルとイモの両者を利用する場合は,10月末～11月初旬に収穫するのがよいことになる. 2)収穫調査6期の材料で,イモヅルサイレージを調製したが,でき上がりサイレージの品質は,時期による差はほとんどなく,いずれも良質のものが得られた. 3)イモヅルサイレージのヤギによる消化率は,材料が10月中旬までのものが,下旬以降の材料からつくったサイレージに比較して少しく高かった. 10月19日以前の3期のサイレージの有機物の消化率は70%程度で,10月30日以降の3期のサイレージの有機物の消化率は65老程度であった. 4)ヤギとウサギによるサイレージの消化率は,本実験の前半のサイレージでは,ヤギがウサギにまさる消化率を示したが,後半では,余り差がなかった. 粗繊維の消化率は,いずれもウサギがヤギより低かった. 5)10アールあたりの圃場から生産されるイモヅルそサイレージを調製する場合TDNの収量からみて,10月下旬に収穫するのがよく,イモの収量もあわせて考える場合は10月末～11月初めに収穫するのが適当と推察された. 6)イモヅルのプロビタミンA含量は,生育が進むにつれて,その含量は低下する. 埋蔵中に失われるプロビタミンA盤は,極端に遅い期の材料のものを除いては,11～25%程度であった. 埋蔵期別による明確な差異は認められなかった

An Adaptive Observer via Optimal Control Law

This paper deals with the adaptive observer which estimates the states and parameters of unknown system. It is shown that the adaptive observer problem is reduced to the identification of the transformation matrix for an arbitrary designable observer. Moreover, the adaptive process of the unknown parameters is reduced to the linear optimal regulator problem. As the result, a new method is presented to obtain an appropriate adaptive process with good insight. And, in this identification, a linear filter is found to be also useful against noises in input-output data. To achieve high accuracy, a particular nonlinear filtering can improve SN ratio only in the direction of the unknown vector. Even if SN ratio of input-output data has zero dB, sufficient accuracy can be accomplished within suitable correction time. This design algorithm seems to be rather straightforward and practical. Since input sequence is required to be only sufficiently general, the method is applicable to on-line identification also

Flight Performance of the AKARI Cryogenic System

We describe the flight performance of the cryogenic system of the infrared astronomical satellite AKARI, which was successfully launched on 2006 February 21 (UT). AKARI carries a 68.5 cm telescope together with two focal plane instruments, Infrared Cameras (IRC) and Far Infrared Surveyor (FIS), all of which are cooled down to cryogenic temperature to achieve superior sensitivity. The AKARI cryogenic system is a unique hybrid system, which consists of cryogen (liquid helium) and mechanical coolers (2-stage Stirling coolers). With the help of the mechanical coolers, 179 L (26.0 kg) of super-fluid liquid helium can keep the instruments cryogenically cooled for more than 500 days. The on-orbit performance of the AKARI cryogenics is consistent with the design and pre-flight test, and the boil-off gas flow rate is as small as 0.32 mg/s. We observed the increase of the major axis of the AKARI orbit, which can be explained by the thrust due to thermal pressure of vented helium gas.Comment: 19 pages, 10 figures, and 6 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japa