Areas affected by routine radiocarbon (14C) discharges from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) and accidental releases in March 2011 were investigated by analysis of cores from Japanese cypress and cedar trees growing at sites 9 and 24 km northwest of the plant. 14C concentrations in tree rings from 2008–2014 (before and after the accident) were determined by accelerator mass spectrometry, with 14C activities in the range 231–256 Bq kg−1 C. Activities during the period 2012–2014, after FDNPP shutdown, represent background levels, while the significantly higher levels recorded during 2008–2010, before the accident, indicate uptake of 14C from routine FDNPP operations. The mean excess 14C activity for the pre-accident period at the sites 9 and 24 km northwest of the plant were 21 and 12 Bq kg−1 C, respectively, indicating that the area of influence during routine FDNPP operations extended at least 24 km northwest. The mean excess tree-ring 14C activities in 2011 were 10 and 5.8 Bq kg−1 C at 9 and 24 km northwest, respectively, documenting possible impact of the FDNPP accident on 14C levels in trees.

Electron-beam-induced soft-X-ray emission spectroscopy (SXES) that uses a grating spectrometer has been introduced to a conventional scanning electron microscope (SEM) for characterizing desired specimen areas of bulk materials. The spectrometer was designed as a grazing incidence flat-field optics by using aberration corrected (varied line spacing) gratings and a multichannel plate detector combined with a charge-coupled device camera, which has already been applied to a transmission electron microscope. The best resolution was confirmed as 0.13 eV at Mg L-emission (50 eV), which is comparable with that of recent dedicated electron energy-loss spectroscopy instruments. This SXES-SEM instrument presents density of states of simple metals of bulk Mg and Li. Apparent band-structure effects have been observed in Si L-emission of Si wafer, P L-emission of GaP wafer, and Al L-emissions of intermetallic compounds of AlCo, AlPd, Al2Pt, and Al2Au.

We analyze sea-ice conditions along seven segments of the Northern Sea Route (NSR) over four time periods. We researched sea ice by segment, using data from the satellite microwave sensors SMMR, SSM/I and AMSR-E. The four analysis periods (periods I–IV: 1980–88, 1989–2001, 2002–06 and 2007–11, respectively) were determined based on changes in the extent of minimum sea ice throughout the Arctic Ocean. Sea ice showed a decreasing tendency from period I to period IV. For example, sea-ice area in period IV decreased compared to previous periods in the eastern East Siberian Sea and around Severnaya Zemlya, areas that had very high sea-ice concentrations in period I. Sea-ice area in the eastern East Siberian Sea decreased sharply during period III, whereas the Severnaya Zemlya area maintained a high ice concentration. In period IV, sea-ice coverage around Severnaya Zemlya was low, although it remained at 25% in the area east of Severnaya Zemlya, which is a key area for navigation. The proportion of multi-year (MY) ice drastically decreased after winter 2002, and only a small amount of MY ice existed in the winters of 2003–06. MY ice disappeared from the eastern East Siberian Sea after 2007. On the other hand, around Severnaya Zemlya the proportion of MY ice showed cyclic ups and downs between 1997 and 2008. Thus, the persistence of various types of sea ice varies according to region. The persistence of various types of sea ice around Severnaya Zemlya also varied each year.

Fetal lung maturity assessment in twin pregnancy has been discussed, but is still controversial. The purpose of this study is to predict the occurrence of respiratory distress syndrome (RDS) using lamellar body count (LBC) and analyze the validity of LBC for fetal lung maturity assessment in twin pregnancy. Three-hundred two amniotic fluid samples were obtained at cesarean section from 29 to 38 weeks of gestation. Samples were analyzed immediately with no centrifugation and the number of lamellar bodies was counted using a platelet channel on the Sysmex SF-3000. There were 18 neonates (6.0%) suffering from RDS. An LBC cut-off value of 2.95 × 104/μL resulted in 91.5% sensitivity and 83.3% specificity for predicting RDS. This cut-off value for predicting RDS was the same as that in singleton pregnancy. Moreover, the median LBC value in RDS cases was significantly lower than in non-RDS cases (1.50 ± 1.1 × 104/μL vs. 10.6 ± 7.5 × 104/μL; p < .001). This is the first report on the validity of LBC in twin pregnancy and also the largest study on fetal lung maturity assessment in twin pregnancy. An LBC value of >2.95 × 104/μL means reassuring findings for RDS even in twin pregnancy. We believe the data in this study provide valuable, new information for the management of twin pregnancies.

We investigated the anisotropic g tensors of nine kinds of organic semiconductor molecules in the cationic state by density functional theory (DFT) calculations. Large anisotropy was obtained in sulfur-containing molecules because of the large spin-orbit coupling at the sulfur atoms. The calculated g values were validated by electron spin resonance (ESR) experiments for the cation radicals in solution.

The efficiency of the energy conversion rate in the relativistic magnetic reconnection is investigated by means of Relativistic Resistive Magnetohydrodynamic (R2MHD) simulations. We confirmed that the simple Sweet-Parker type magnetic reconnection is a slow process for the energy conversion as theoretically predicted by Lyubarsky (2005). After the Sweet-Parker regime, we found a growth of the secondary tearing instability in the elongated current sheet. Then the energy conversion rate and the outflow velocity of reconnection jet increase rapidly. Such a rapid energy conversion would explain the time variations observed in many astrophysical flaring events.

To construct a more realistic model of relativistic reconnection, we extend our R2MHD code to R3MHD code by including the radiation effects (Relativistic Resistive Radiation Magnetohydrodynamics R3MHD). The radiation field is described by the 0th and 1st moments of the radiation intensity (Farris et al. 2008, Shibata et al. 2011). The code has already passed some one-dimensional and multi-dimensional numerical problems. We demonstrate the first results of magnetic reconnection in the radiation dominated current sheet.

Following an International Geophysical Year project, we conducted meteorological observations during 2004–07 around the Suntar–Khayata range in eastern Siberia, where a strong temperature inversion exists throughout the winter. The temperature on the flat plain around Oymyakon (~700ma.s.l.) was ~20°C lower than that in a glaciated area located at ~2000ma.s.l. The inversion remained stable from October to April due to the Siberian high. Snowfall was limited to the beginning and end of winter. The stable conditions prevented atmospheric disturbances and inhibited snowfall during midwinter. From 1945 to 2003, glaciers in the Suntar–Khayata range retreated, with an area reduction of 19.3%. To assess this retreat, we estimated the response of the glaciers to climate change. According to US National Centers for Environmental Prediction (NCEP) data, the temperature in this region increased by ~1.9°C over 60 years. By calculating snow accumulation and ablation, the sensitivity of the equilibrium-line altitude (ELA) to the temperature shift was evaluated. We estimated snow precipitation based on precipitation at <0°C and ablation using the degree-day method. By these estimates, the ELA of Glacier No. 31, assumed 2350 m at present, could rise ~150m if temperature rises an average of 1°C. Furthermore, a 1.8°C temperature rise could cause the ELA to rise to 2600ma.s.l., removing the accumulation zone. With no accumulation zone, the glacier body would decrease, roughly halving in volume after ~400 years.

With decreases in Arctic sea-ice extent in recent years, the Northern Sea Route (NSR) and Northwest Passage (NWP), which we collectively term the Arctic Sea Route (ASR), have become open for navigation more frequently. The ASR connects the Pacific and Atlantic Oceans, with the NSR following the Siberian coast, and the NWP following the north coast of North America. This study evaluated long-term ice concentrations along both routes using microwave data from the SMMR and SSM/I sensors, and analyzed details using data from the AMSR-E passive microwave sensor. The data were used to determine the number of navigable days according to various sea-ice concentrations. Analysis of SMMR and SSM/I data showed a remarkably large number of navigable days on the NSR since 1995. For the NWP, the low resolution of the SMMR and SSM/I data for the Canadian Arctic Archipelago made analysis difficult, but long-term change in the sea-ice distribution on the ASR was indicated. Analysis of the AMSR-E microwave sensor data revealed navigable days along the NSR in 2002 and from 2005 to 2009 (except 2007). For navigation purposes, the sea-ice decrease in specific regions is important, as well as the decrease across the Arctic Ocean as a whole. For the NWP, numerous navigable days were identified in the period 2006–08.

The seasonal duration of sea-ice cover in the region immediately north of Hokkaido in the Sea of Okhotsk was estimated from daily sea-ice concentration maps (1995–2009) produced by the Japanese Coast Guard. The results show that this period is generally well represented by the proxy record of sea-ice duration in the region of Utoro in the Shiretoko peninsula. Comparison of the duration of seasonal sea-ice cover along the coast of Hokkaido with meteorological conditions over the period of sea-ice mapping by the Japanese Coast Guard indicates that all sea ice will disappear from the coast of Hokkaido once air temperature is increased by 2–4˚C over present values by the effects of climate change.

Radiocarbon ages of Choukai Jindai cedar tree rings growing in the excess era of 14C concentrations during 2757–2437 cal BP were measured using 2 types of 14C measurement methods, i.e. liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The difference between the 2 methods is 3.7 ± 5.2 14C yr on average for 61 single-year tree rings, indicating good agreement between the methods. The Choukai data sets show a small sharp bump with an average 14C age of 2497.1 ± 3.0 14C yr BP during 2650–2600 cal BP. Although the profile of the Choukai LSC data set compares well with that of IntCal04, having a 14C age difference of 4.6 ± 5.3 14C yr on average, the Choukai LSC 14C ages indicate variability against the smoothed profile of IntCal04.

In the recent development of the studies in iron-based superconductors, high-pressure experiments have been played an important role. Large enhancement of Tc with applying pressure and pressure-induced superconductivity were reported in LaFeAsO1-xFx. In this work, electrical, magnetic and structural measurements on 1111 type Ca(Fe1-xCox)AsF and 11 type Fe(Se1-xTex)0.92 under high pressure have been performed. For Ca(Fe1-xCox)AsF, the substitution of Co suppressed the magnetic and structural transitions and raised superconductivity. Pressure-induced superconductivity was observed for x = 0.0 and 0.05. The highest Tc was obtained in parent compound under high pressure, in contrast to LaFeAsO1-xFx. These results suggest that the substitution of Co increases carrier concentration and induces disorder in the FeAs superconducting layer. For FeTe0.92, pressure-induced superconductivity was not detected under high pressure up to 19 GPa, although the resistive anomaly due to the structural and magnetic phase transition was suppressed by applying pressure.

We measured the radiocarbon ages of 165 single-year tree rings from a Japanese Choukai Jindai cedar using accelerator mass spectrometry (AMS). By wiggle-matching the Choukai_AMS data set to the IntCal04 calibration data using OxCal v 3.10 and using the variation of the correlation coefficients between the Choukai_AMS and IntCal04 data sets, we precisely re-estimated that the 321 Choukai Jindai cedar tree rings range from 780 to 460 cal BC with an accuracy of 8 yr. The Choukai_AMS data set is older than the 3 raw data sets of European tree rings that comprise IntCal04. The Belfast and Seattle data sets are younger by −21.3 ± 5.5 and −22.7 ± 5.6 14C yr, respectively. The Choukai Jindai cedar is ∼22 14C yr older than the European tree rings, which is equivalent to an offset of −2.8‰ in 14C. In addition, the Choukai_AMS data set correlates well with the Belfast and Seattle data sets, with correlation coefficients of 0.89 and 0.68, respectively, between the temporal profiles. Hence, the temporal profile of the Choukai 14C ages shows a global variation.

The ‘Okhotsk Sea Ice Observation Experiment’ 93' was carried out in February 1993 in the southern part of the Sea of Okhotsk and in Lake Saroma, Japan. The aim of the experiment was to investigate how effectively Synthetic Aperture Radar (SAR) can monitor sea ice in this region. Satellite data from JERS-1/SAR (J-SAR), ERS-1/SAR CESAR), and SPOT-2/HRV, as well as data from airborne sensors and ground-truth data, were utilized. From the overall analysis of those data, several results were obtained. First, the range of backscatter of the ice cover on Lake Saroma was determined, as well as a relation between ice type and backscatter. Second, a method for making SAR mosaic images was developed to monitor sea ice over a wide area. When comparing J-SAR(L-band) data with E-SAR(C-band) data acquired simultaneously over the same area, J-SAR proved to be superior to E-SAR in showing the existence of sea ice. And third, it was confirmed that the backscatter of E-SAR was correlated to the ice thickness, which may be explained by the relation between the backscatter and the ice-surface temperature.

The magnetic characteristics of the dilute magnetic system GaGdN are investigated by mainly soft-X-ray magnetic circular dichroism (MCD) in energy range of 1160 – 1240 eV. The strong MCD signals up to 30 % at 15K are observed. The temperature dependence of its intensity is not on simple Curie-Weiss curve and depicts three-step curve. A step around 40 – 100K suggests a new magnetic phase. The luminescence spectrum of GaGdN at low temperature is divided into three parts consisting of two broad bands around 432 nm and 503 nm and a sharp peak at 652 nm. This sharp line is assigned to the intra-transition of f – f orbital owing to the weak temperature dependence of the intensity and peak position. AlGdN grown by molecular beam epitaxy produces luminescence at 318.5 nm. X-ray absorption fine structure is examined to survey the occupancy of the Gd ion in the grown specimens.