Suzaku investigation into the nature of the nearest ultraluminous X-ray source, M33 X-8

The X-ray spectrum of the nearest ultraluminous X-ray source, M33 X-8, obtained by Suzaku during 2010 January 11 -- 13, was closely analyzed to examine its nature. It is, by far, the only data with the highest signal statistic in 0.4 -- 10 keV range. Despite being able to reproduce the X-ray spectrum, Comptonization of the disk photons failed to give a physically meaningful solution. A modified version of the multi-color disk model, in which the dependence of the disk temperature on the radius is described as r^(-p) with p being a free parameter, can also approximate the spectrum. From this model, the innermost disk temperature and bolometric luminosity were obtained as T_in = 2.00-0.05+0.06 keV and L_disk = 1.36 x 10^39 (cos i)^(-1) ergs/s, respectively, where i is the disk inclination. A small temperature gradient of p = 0.535-0.005+0.004, together with the high disk temperature, is regarded as the signatures of the slim accretion disk model, suggesting that M33 X-8 was accreting at high mass accretion rate. With a correction factor for the slim disk taken into account, the innermost disk radius, R_in =81.9-6.5+5.9 (cos i)^(-0.5) km, corresponds to the black hole mass of M \sim 10 M_sun (cos i)^(-0.5). Accordingly, the bolometric disk luminosity is estimated to be about 80 (cos i)^(-0.5)% of the Eddington limit. A numerically calculated slim disk spectrum was found to reach a similar result. Thus, the extremely super-Eddington luminosity is not required to explain the nature of M33 X-8. This conclusion is utilized to argue for the existence of intermediate mass black holes with M > 100 M_sun radiating at the sub/trans-Eddington luminosity, among ultraluminous X-ray sources with L_disk > 10^(40) ergs/s.Comment: 10 pages, 4 figures, PASJ accepte

Axisymmetric wakes behind a slender body including zero-momentum configurations

An experimental investigation of turbulent axisymmetric wakes including the zero-momentum case was carried out. Mean and fluctuation velocity profiles were measured and self-similar profiles were observed that decayed very rapidly when the momentum was adjusted to be zero. The wake behavior was found to be sensitive to any small mismatch of momentum and the relaxation zone strongly depended on the intensity and scale of the turbulence in the initial wake

Identification of a 100 kDa Microtubule-Associated Protein from Xenopus Eggs

A 100 kDa protein was identified by a combination of microtubule affinity chromatography and microtubule co-sedimentation from Xenopus egg extracts. The 100 kDa protein was expressed in Stage VI oocytes and early embryos, and then decreased at tailbud stage. The 100 kDa protein was found in adult organs such as brain and liver. Immunofluorescent microscopy revealed that the 100 kDa protein was mainly detected in spinal cord, notochordal sheath, optic cup, lens and cement gland in tailbud embryos. In Xenopus A6 cells, the 100 kDa protein showed filamentous networks in the peripheral cytoplasm and uniform distribution around the nucleus. During cell division, the 100 kDa protein was localized to the mitotic apparatus. The 100 kDa protein may have some roles in microtubule dynamics, organization of the mitotic apparatus and maintenance of cell shape

Variant Forms of α-Fetoprotein Transcripts Expressed in Human Hematopoietic Progenitors: IMPLICATIONS FOR THEIR DEVELOPMENTAL POTENTIAL TOWARDS ENDODERM

Hematopoietic stem cells have been identified as multipotent cells that give rise to all adult hematopoietic lineages. Although the hematopoietic lineage is derived from the mesodermal germ layer in the embryo, recent data suggest that bone marrow cells with an antigenic profile consistent with that of hematopoietic stem cells can also differentiate to cell types of the endodermal lineages, such as hepatocytes. However, the molecular mechanisms associated with these events are entirely unknown. For decades, alpha-fetoprotein (AFP) has been used as a differentiation marker for endodermal cells, because it was thought that the transcription of AFP mRNA is tightly regulated in a developmental and tissue-specific process. In this report we describe two new variant forms of AFP transcripts in human hematopoietic progenitors that are not expressed in mature cells. The variant AFP (vAFP) cDNA sequences isolated from a multipotent hematopoietic cell line, K562, revealed that the vAFP differed from the authentic transcript, consisting of 15 exons, by replacing exon 1 of AFP with one or two exons located in the 5'-untranslated region of the AFP gene. In addition to the K562 cell line, vAFP transcripts were detected in normal bone marrow, thymus, and brain but were not detected in normal spleen, intestine, liver, or the hepatocellular carcinoma cell line, HepG2. This suggests expression in normal hematopoietic progenitors. This hypothesis was confirmed by the finding that CD34(+)Lin(-) hematopoietic progenitor cells purified from cord blood by flow cytometric sorting also expressed the variant transcripts. These results suggest that some hematopoietic progenitors are in a state that permits them to express certain types of transcripts that have been considered unique to endoderm

WEEDS PROMOTE THE DEVELOPMENT OF ARBUSCULAR MYCORRHIZAL FUNGI IN ORGANIC WHEAT FIELDS

Understanding the interaction between aboveground vegetation and arbuscular mycorrhizal fungi (AMF) in organic agriculture is of great importance to develop more efficient and sustainable agricultural production systems. This study was conducted to evaluate the effect of weeds on AMF and the effect of AMF on wheat (Triticum aestivum L.) grain quality in an organic field in the weed-free and weedy conditions. The soil microbial profile was characterized using phospholipid fatty acids (PLFA) analysis. We found that the presence of weeds increased the proportion of AMF. The enhanced activity of AMF did not affect the quality of wheat grain grown with sufficient soil phosphorus (P)