How much asymmetry is there in bond returns and exchange rates?

We measure asymmetries in the distribution of bond returns and exchange rates and test their statistical significance. Asymmetries are sizable when measured by the coefficient of skewness, a measure that is highly affected by outliers. In contrast, robustly measured asymmetries to outliers often disagree in sign or size, implying that much of the asymmetries measured by the coefficient of skewness can be attributed to extreme observations. Asymmetries in many government bonds returns are only statistically significant according to tests based on the coefficient of skewness.> ; On the contrary, only tests based on robust measures indicate statistically significant asymmetries in the exchanges rates of Japanese yen, a major funding currency for carry trades, as well as in New Zealand dollar and Australian dollar, major investing currencies for carry trades. This observation suggests that sources of asymmetry in carry trades and in government bond returns can be fundamentally different.International finance

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

Living Donor Liver Transplantation to a Survivor of LiverResection for Hepatocellular Carcinoma with Major Portal Vein Invasion

We present a case of living donor liver transplantation to a 3-year disease-free survivor of liver resection for hepatocellular carcinoma (HCC) with major portal vein invasion. A 48-year-old man had HCC in the right lobe with a portal venous tumor thrombus extending into the left portal vein. An extended right lobectomy with thrombectomy was performed to remove the thrombus. Three years after liver resection, the patient experienced liver failure, with massive ascites and jaundice due to the formation of a thrombus in the main and left portal veins. During the 3 years after liver resection, no metastasis or recurrence of HCC had been detected, and tumor markers had been within normal ranges. The portal venous thrombus did not show any arterial enhancement under contrast-enhanced computed tomography, suggesting that the co-existence of any HCC component in the portal venous thrombus may have been negative. Based on these findings, living donor liver transplantation was performed using a right lobe graft from the patientʼs son. The patient is alive at 87 months after the transplantation, with no evidence of HCC recurrence

Strategies to enhance the excitation energy-transfer efficiency in a light-harvesting system using the intra-molecular charge transfer character of carotenoids

Fucoxanthin is a carotenoid that is mainly found in light-harvesting complexes from brown algae and diatoms. Due to the presence of a carbonyl group attached to polyene chains in polar environments, excitation produces an excited intra-molecular charge transfer. This intra-molecular charge transfer state plays a key role in the highly efficient (∼95%) energy-transfer from fucoxanthin to chlorophyll a in the light-harvesting complexes from brown algae. In purple bacterial light-harvesting systems the efficiency of excitation energy-transfer from carotenoids to bacteriochlorophylls depends on the extent of conjugation of the carotenoids. In this study we were successful, for the first time, in incorporating fucoxanthin into a light-harvesting complex 1 from the purple photosynthetic bacterium, Rhodospirillum rubrum G9+ (a carotenoidless strain). Femtosecond pump-probe spectroscopy was applied to this reconstituted light-harvesting complex in order to determine the efficiency of excitation energy-transfer from fucoxanthin to bacteriochlorophyll a when they are bound to the light-harvesting 1 apo-proteins