Astrocytic gliomas: MRI and pathological grade.

The relationship between MR configuration and pathological grade was studied in 41 histologically verified supratentorial astrocytic gliomas with a 0.5T superconductive MR system. The gliomas included 13 low-grade astrocytomas (LGAs), 14 anaplastic astrocytomas (AAs) and 14 glioblastoma multiformes (GBMs). MRI configurations were classified into nine criteria which were scored and statistically analyzed. The mean values of LGAs, AAs and GBMs were 0.45 +/- 0.31, 1.18 +/- 0.20 and 1.47 +/- 0.22. In each grade, MRI score increased as pathological grades increased (p &#60; 0.01-0.001). LGAs had significantly lower values than AAs in five of the nine criteria (55.6%); heterogeneity, cyst or necrosis, edema or mass effect, border definition, and the degree of contrast enhancement, and lower values than GBMs in eight criteria (88.9%) except for hemorrhage. Three criteria (33.3%), heterogeneity, cyst or necrosis, and flow void sign were significantly higher in GBMs than AAs. The four variables, heterogeneity, cyst or necrosis, edema or mass effect and border definition, proved to be important factors related to the pathological grade in a multiple regression analysis.</p

Electronic structure of multiferroic BiFeO3 by resonant soft x-ray emission spectroscopy

[[abstract]]The electronic structure of multiferroic BiFeO3 has been studied using soft x-ray emission spectroscopy. The fluorescence spectra exhibit that the valence band is mainly composed of O 2p state hybridized with Fe 3d state. The band gap corresponding to the energy separation between the top of the O 2p valence band and the bottom of the Fe 3d conduction band is 1.3 eV. The soft x-ray Raman scattering reflects the features due to the charge-transfer transition from O 2p valence band to Fe 3d conduction band. These findings are similar to the result of electronic structure calculation by density-functional theory within the local spin-density approximation that included the effect of Coulomb repulsion between localized d states.[[booktype]]紙本[[booktype]]電子

A Substellar Companion to Pleiades HII 3441

We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0".49 +/- 0".02 (66 +/- 2 AU) and a mass of 68 +/- 5 M_J based on three observations in the J-, H-, and K_S-band. The spectral type is estimated to be M7 (~2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0 +26.1/-8.8 %. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.Comment: Main text (14 pages, 4 figures, 4 tables), and Supplementary data (8 pages, 3 tables). Accepted for Publications of Astronomical Society of Japa