Low Temperature X-ray Diffraction Study of ZnCr2O4 and Ni0.5Zn0.5Cr2O4

金沢大学大学院自然科学研究科Results of x-ray diffraction measurements are presented for ZnCr2O4 and Ni0.5Zn0.5Cr2O4. Splits of the x-ray diffraction spectrum are observed in ZnCr2O4 at 12 K. In Ni0.5Zn0.5Cr2O4 no clear split is observed, but a full width at half maximum (FWHM) shows a steep increase below about 20 K. It is found that the integrated intensity of the diffraction spectra shows a softening behavior at low temperatures in ZnCr2O4. © 2008 Springer Science+Business Media, LLC

Subaru Observations for the K-band Luminosity Distribution of Galaxies in Clusters near to 3C 324 at z∼\sim1.2

We investigate the $K$-band luminosity distribution of galaxies in the region of clusters at $z\sim1.2$ near to the radio galaxy 3C 324. The imaging data were obtained during the commissioning period of the Subaru telescope. There is a significant excess of the surface number density of the galaxies with $K =$ 17--20 mag in the region within $\sim$ 40'' from 3C 324. At this bright end, the measured luminosity distribution shows a drop, which can be represented by the exponential cut off of the Schechter-function formula; the best-fitted value of the characteristic magnitude, $K^{*}$, is $\sim 18.4\pm0.8$. This measurement follows the evolutionary trend of the $K^*$ of the rich clusters observed at an intermediate redshift, which is consistent with passive evolution models with a formation redshift z_f \gtsim 2. At K \gtsim 20 mag, however, the excess of the galaxy surface density in the region of the clusters decreases abruptly, which may imply that the luminosity function of the cluster galaxies has a negative slope at the faint end. This may imply strong luminosity segregation between the inner and outer parts of the clusters, or some deficit of faint galaxies in the cluster central region of the cluster.Comment: 12 pages, 9 figures, accepted for publication in PAS

Association of Thioautotrophic Bacteria with Deep-Sea Sponges

We investigated microorganisms associated with a deep-sea sponge, Characella sp. (Pachastrellidae) collected at a hydrothermal vent site (686 m depth) in the Sumisu Caldera, Ogasawara Island chain, Japan, and with two sponges, Pachastrella sp. (Pachastrellidae) and an unidentified Poecilosclerida sponge, collected at an oil seep (572 m depth) in the Gulf of Mexico, using polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) directed at bacterial 16S rRNA gene sequences. In the PCR-DGGE profiles, we detected a single clearly dominant band in each of the Characella sp. and the unidentified Poecilosclerida sponge. BLAST search of their sequences showed that they were most similar (>99% identity) to those of the gammaproteobacterial thioautotrophic symbionts of deep-sea bivalves from hydrothermal vents, Bathymodiolus spp. Phylogenetic analysis of the near-full length sequences of the 16S rRNA genes cloned from the unidentified Poecilosclerida sponge and Characella sp. confirmed that they were closely related to thioautotrophic symbionts. Although associations between sponges and methanotrophic bacteria have been reported previously, this is the first report of a possible stable association between sponges and thioautotrophic bacteria

Superwind-Driven Intense H_2 Emission in NGC 6240

We have performed a long-slit K band spectroscopic observation of the luminous infrared galaxy NGC 6240. The peak position of the H_2 v=1-0 S(1) emission in the slit is located ~0.3" - 0.4" north of the southern nucleus. It is almost the midpoint between the southern nucleus and the peak position of the ^12CO J=1-0 emission. Based on the line-ratio analyses, we suggest the excitation mechanism of H_2 is pure thermal at most positions. In the southern region we find the following three velocity components in the H_2 emission: the blueshifted shell component (~-250 km s^-1 with respect to V_sys) which is recognized as a distinct C-shape distortion in the velocity field around the southern nucleus, the high-velocity blueshifted ``wing'' component (~-1000 km s^-1 with respect to V_sys), and the component indicating possible line splitting of ~500 km s^-1. The latter two components are extended to the south from the southern nucleus. We show that the kinematic properties of these three components can be reproduced by expanding motion of a shell-like structure around the southern nucleus. The offset peak position of the H_2 emission can be understood if we assume that the shell expanding to the north interacts with the extragalactic molecular gas. At the interface between the shell and the molecular gas concentration the cloud-crushing mechanism proposed by Cowie et al. (1981) may work efficiently, and the intense H_2 emission is thus expected there. All these findings lead us to propose a model that the most H_2 emission is attributed to the shock excitation driven by the superwind activity of the southern nucleus.Comment: 33 pages, 9 figures, accepted for publication in PAS

High-Resolution Near-Infrared Imaging of the Powerful Radio Galaxy 3C 324 at z = 1.21 with the Subaru Telescope

We have obtained high-resolution K'-band images of the powerful z=1.206 radio galaxy 3C 324 with the Subaru telescope under seeing conditions of 0.3--0.4 arcsec. We clearly resolved the galaxy and directly compared it to the optical images obtained with the Hubble Space Telescope. The host galaxy of 3C 324 is revealed to be a moderately luminous elliptical galaxy with a smooth light profile. The effective radius of the galaxy, as determined by profile fitting, is 1.3+-0.1 arcsec (1.2 kpc), which is significantly smaller than the value of 2.2 arcsec, published in Best et al. (1998, MNRAS, 292, 758). The peak of the K'-band light coincides with the position of the radio core, which implies that the powerful AGN lies at the nucleus of the host galaxy. The peak also coincides with the gap in the optical knotty structures which may be a dust lane hiding the UV-optical emission of the AGN from our line of sight; it is very likely that we are seeing the obscuring structure almost edge-on. We clearly detected the `aligned component' in the K'-band image by subtracting a model elliptical galaxy from the observed image. The red R_F702W-K color of the outer region of the galaxy avoiding the aligned component indicates that the near infrared light of the host galaxy is dominated by an old stellar population.Comment: 21 pages (10 figures), accepted for publication in PAS

Spatiotemporal T790M Heterogeneity in Individual Patients with EGFR-Mutant Non–Small-Cell Lung Cancer after Acquired Resistance to EGFR-TKI

IntroductionEpidermal growth factor receptor (EGFR) mutation T790M accounts for approximately half of acquired resistances to EGFR-tyrosine kinase inhibitor (TKI). Because T790M is mediated by TKI exposure, its penetration and “on–off” may affect T790M status.MethodsWe retrospectively reviewed T790M status and clinical course of patients who had undergone multiple rebiopsies after acquired resistance to EGFR-TKI.ResultsOf 145 patients with EGFR-mutant NSCLC receiving rebiopsy after acquired resistance, 30 underwent multiple site rebiopsies, and 24 received repeated rebiopsies at the same lesion. In 22 patients who underwent rebiopsies from both central nervous system (CNS; 20 cerebrospinal fluids [CSF] and 2 brain tumoral tissues) and thoracic lesions (7 lung tissues, 14 pleural effusions, and 1 lymph node), 12 were thoracic-T790M-positive. Of these 12 patients, 10 were CNS-T790M-negative, despite exhibiting thoracic-T790M-positive. All 10 thoracic-T790M-negatives were CNS-T790M-negative. Three patients revealed a spatial heterogeneous T790M status among their thoracic lesions. In 24 patients receiving repeated rebiopsies at the same lesion (12 lung tissues, 6 CSFs, and 6 pleural effusions), T790M status of lung lesions varied in five patients after TKI-free interval. In all five patients whose T790M status changed from positive to negative, EGFR-TKI rechallenge was effective. In three of these five patients, after further TKI exposure, T790M status changed from negative to positive again. There was also a patient whose CSF T790M status changed from negative to positive after high-dose erlotinib therapy.ConclusionsT790M status in an individual patient can be spatiotemporally heterogeneous because of selective pressure from EGFR-TKI

ホウレンソウ雌性間性株における突然変異誘発ならびに低シュウ酸個体の選抜

This study was conducted to evalute mutagenesis in gynomonoecious spinach (Spinacia oleracea L.) plants for inducing low oxalate variants.Gamma-ray and ion beams of 220 MeV12C5+ and 50MeV 4He2+ ware used as mutagen in seed irradiation. Optimum dosages for irradiation were determined to be about 100Gy, 15-20Gy and 150-200Gy in gamma-ray, 12C5+ and 4He2+, respectively. In M2 generation, there was one line segregating albino seedlings, one line segregating xantha seedlings and two lines segregating dioesious spinach. To save on labor and time for analysis, selection of low oxalate variants in M2generation was conducted by a two-step selebtion which consisted of the first snalysis of bulked leaves from 2 plants as one specimen followed by the second analysis of selected individual plants. In the first analysis of 813 specimens, we selected 13 specimens as low and 9 specimens as high in oxalate content. In the second analysus, there was consistency in the distribution of low and high oxalate content corresponding to the first screening, indicating that selebtion of low oxalate variants could be achived by this two-step selebtion with half the labor and time for analysis as compares to non-bulked method. There were no clear differences in distribution of oxalate content between M3progenies of plants selected as low or high oxalate content, suggesting that the low oxalate content in plants isolated in M2generation was not of a genetic origin. From these results, it seems to be necessary to explore a variant with obvious deviation from the bontinuous variation of oxalate content in the M 2 generation.本実験では，ホウレンソウ雌性間性株における突然変異誘発ならびに低シュウ酸個体の選抜を試みた．種子照射の変異原としては，γ線と220MeV 12