Cosmic Star Formation Activity at z=2.2 Probed by H-alpha Emission Line Galaxies

We present a pilot narrow-band survey of H-alpha emitters at z=2.2 in the Great Observatories Origins Deep Survey North (GOODS-N) field with MOIRCS instrument on the Subaru telescope. The survey reached a 3 sigma limiting magnitude of 23.6 (NB209) which corresponds to a 3 sigma limiting line flux of 2.5 x 10^-17 erg s^-1 cm^-2 over a 56 arcmnin^2 contiguous area (excluding a shallower area). From this survey, we have identified 11 H-alpha emitters and one AGN at z=2.2 on the basis of narrow-band excesses and photometric redshifts. We obtained spectra for seven new objects among them, including one AGN, and an emission line above 3 sigma is detected from all of them. We have estimated star formation rates (SFR) and stellar masses (M_star) for individual galaxies. The average SFR and M_star is 27.8M_solar yr^-1 and 4.0 x 10^10M_solar, respectivly. Their specific star formation rates are inversely correlated with their stellar masses. Fitting to a Schechter function yields the H-alpha luminosity function with log L = 42.82, log phi = -2.78 and alpha = -1.37. The average star formation rate density in the survey volume is estimated to be 0.31M_solar yr^-1Mpc^-3 according to the Kennicutt relation between H-alpha luminosity and star formation rate. We compare our H-alpha emitters at z=2.2 in GOODS-N with narrow-band line emitters in other field and clusters to see their time evolution and environmental dependence. We find that the star formation activity is reduced rapidly from z=2.5 to z=0.8 in the cluster environment, while it is only moderately changed in the field environment. This result suggests that the timescale of galaxy formation is different among different environments, and the star forming activities in high density regions eventually overtake those in lower density regions as a consequence of "galaxy formation bias" at high redshifts.Comment: Accepted for publication in PASJ Subaru Special Issue, 11 pages, 10 figure

Magnetic Field Amplification Associated with the Richtmyer-Meshkov Instability

The amplification of a magnetic field due to the Richtmyer-Meshkov instability (RMI) is investigated by two-dimensional MHD simulations. Single-mode analysis is adopted to reveal definite relation between the nonlinear evolution of RMI and the field enhancement. It is found that an ambient magnetic field is stretched by fluid motions associated with the RMI, and the strength is amplified significantly by more than two orders of magnitude. The saturation level of the field is determined by a balance between the amplified magnetic pressure and the thermal pressure after shock passage. This effective amplification can be achieved in a wide range of the conditions for the RMI such as the Mach number of an incident shock and the density ratio at a contact discontinuity. The results suggest that the RMI could be a robust mechanism of the amplification of interstellar magnetic fields and cause the origin of localized strong fields observed at the shock of supernova remnants.Comment: 16 pages, 9 figures, accepted for publication in Ap

Thermophysical Property Measurements of Refractory Oxide Melts With an Electrostatic Levitation Furnace in the International Space Station

Due to their high melting temperatures and the risk of contamination from the crucibles, molten oxides which melting temperatures are above 2000 °C can hardly be processed using conventional methods. This explains that their thermophysical properties are very scarce. Containerless methods with gas flows have been developed and several thermophysical properties such as density, surface tension, and viscosity have been reported. However, the gas flow has detrimental side effects such as deformation of the sample and induction of internal flows in the molten sample, which affect the accuracy of the measurements. The electrostatic levitation furnace onboard the International Space Station (ISS-ELF), which utilizes the Coulomb force to levitate and melt samples in microgravity, has several advantages for thermophysical property measurements of refractory oxide melts. Levitation without a gas flow coupled to a reduced gravity environment minimizes the required levitation (positioning) force and reduces the deformation as well as the internal flow. This report briefly introduces the ISS-ELF facility and the thermophysical property measurement methods. The measured density, surface tension, and viscosity of molten Al2O3 are then presented and compared with the ones obtained by other methods. Finally, the measured data of refractory oxides whose melting temperatures are above 2,400 °C are summarized

Evidence for an antiferroquadrupolar ordering in YbSb probed by 121Sb and 123Sb nuclear magnetic resonances

Formation of the antiferroquadrupolar (AFQ) ordering in YbSb (NaCl-type structure) was evidenced microscopically with the 121Sb and 123Sb nuclear magnetic resonance (NMR) measurements. We have observed in the NMR linewidth below TQ=5 K the appearance of an additional field-independent contribution that is proportional to the nuclear electric-quadrupole moment. Thus, the field-independent contribution can be addressed not to any long-range magnetic orderings but to a broken symmetry of the charge distribution associated with the AFQ ordering. The AFQ ordering also gives rise to a large anisotropic Knight shift broadening caused by the anisotropy in the transferred hyperfine field and/or magnetic susceptibility. Fluctuations of the Yb 4f moments are also investigated by using the 121,123Sb spin-lattice relaxation rate measurement

眼球毒性の観察された農薬についての文献的考察

Pesticides evaluated previously by the Food Safety Commission of the Cabinet Office, Japan were in vestigated retrospectively for induction of ocular toxicity. A total of 339 assessment reports representing 345 compounds were investigated. Ocular toxicity was observed in 56 compounds. Target sites were pupils for 21 compounds, retinas for 21 compounds, lenses for 16 compounds, corneas for 15 compounds, conjunctiva for 3 compounds and whole eyeballs for 2 compounds. These ocular toxicities were not related to local irritation, but were due to systemic exposure after oral absorption. For many of these compounds, the mechanism (s) of ocular toxicities are unknown. Ocular toxicities were only induced at considerably higher doses of exposure compared to the acceptable daily intake (ADI) with sufficient safety margins for ocular toxicity. Although it is unlikely that ocular toxicities induced by these chemicals will occur in humans, it is though that future studies anticipating actual human exposure conditions and associated pharmacokinetic information will be important

Relationship between XBP1 genotype and personality traits assessed by TCI and NEO-FFI

There have been several researches on the role of personality in the pathophysiology of bipolar disorder. Recently, a polymorphism of XBP1, a pivotal gene in the endoplasmic reticulum (ER) stress response, was shown to contribute to the genetic risk factor for bipolar disorder. Therefore, in this study, we examined the relationship between the XBP1 gene polymorphism and the personality traits assessed by two self-rating scales, a shortened version of Temperament and Character Inventory (TCI) and NEO-Five Factor Inventory (NEO-FFI) in healthy subjects. The present results suggested that the XBP1 gene polymorphism was associated with the NEO-FFI score of neuroticism in female subjects. However, no significant differences in the other personality scale scores of both assessments were observed among normal subjects with -116C/C, C/G and G/G genotypes. Further investigations are necessary to examine the relationship in patients with bipolar disorder, or use full version of various self-rating personality assessments

Densities of Liquid Tm2O3, Yb2O3, and Lu2O3 Measured by an Electrostatic Levitation Furnace Onboard the International Space Station

Liquid densities of three lanthanoid sesquioxides (Tm2O3, Yb2O3, and Lu2O3), whose melting temperatures are above 2400 °C, were measured using an electrostatic levitation furnace onboard the International Space Station (ISS). Each sample was positively charged, and its position was controlled by Coulomb forces between the sample and the surrounding electrodes. Following heating and melting of the sample by high-power lasers, its volume was calculated from its spherical shape in its liquidus phase. After weighing the mass of the sample returned to Earth, its density was determined. The densities (ρ) of Tm2O3, Yb2O3, and Lu2O3 can be expressed as ρTm2O3 = 8304 − 0.18 × (T − Tm), ρYb2O3 = 8425 − 0.55 × (T − Tm), and ρLu2O3 = 8627 − 0.43 × (T − Tm), respectively, where Tm is their melting temperatures