140 research outputs found

    Modeling line-driven disk wind for broad absorption lines of quasars

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    The disk wind, which is powered by the radiation force due to spectral lines (line force), is studied for broad absorption line (BAL) quasars. We investigate the structure of the disk wind based on the non-hydrodynamic method and compare with wind properties inferred from X-ray observations of BAL quasars. In this paper, we apply the stellar wind theory to the initial condition (the mass outflow rate at the base of the wind). We found the funnel-shaped winds with a half opening angle of 50^{circ} for the case of epsilon=0.3-0.9 and M_{BH}=10^{7-8.5}M_odot, where epsilon is the Eddington ratio and M_{BH} is the black hole mass. Thus, the absorption features are observed for an observer of which a viewing angle is around 50^{circ}. A probability of BAL quasars is 7-11%, which is roughly consistent the abundance ratio of BAL quasars, 10-15%. Here, the probability is estimated by the solid angle, that the absorbing features would be detected, divided by 4pi. In contrast, if the Eddington ratio is smaller than 0.01 or if the black hole is very massive, M_{BH} < 10^9M_{odot}, the disk wind is not launched due to the less effective line force. Then, the quasars are identified as non-BAL quasars independently of the observer's viewing angle.Comment: 10 pages, 6 figures. Accepted for publication in PAS

    Highly Efficient CRISPR-Associated Protein 9 Ribonucleoprotein-Based Genome Editing in Euglena gracilis

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    Euglena gracilis, a unicellular phytoflagellate microalga, is a promising biomaterial for foods, feeds, and biofuels. However, targeted mutagenesis in this species has been a long-standing challenge. We recently developed a transgene-free, highly efficient, genome editing method for E. gracilis using CRISPR/Cas9 ribonucleoproteins (RNPs). Our method achieved mutagenesis rates of approximately 80% or more through an electroporation-based direct delivery of Cas9 RNPs. Therefore, this method is suitable for basic research and industrial applications, such as the breeding of Euglena. For complete details on the use and execution of this protocol, please refer to Nomura et al. (2019)

    Multiphase Gas Nature in the Sub-parsec Region of the Active Galactic Nuclei I: Dynamical Structures of Dusty and Dust-free Outflow

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    We investigated dusty and dust-free gas dynamics for a radiation-driven sub-pc scale outflow in an active galactic nucleus (AGN) associated with a supermassive black hole 107M10^7 M_\odot and bolometric luminosity 104410^{44} erg s1^{-1} based on the two-dimensional radiation-hydrodynamic simulations. A radiation-driven ``lotus-like'' multi-shell outflow is launched from the inner part (r0.04r \lesssim 0.04 pc) of the geometrically thin disk, and it repeatedly and steadily produces shocks as mass accretion continues through the disk to the center. The shape of the dust sublimation radius is not spherical and depends on the angle (θ\theta) from the disk plane, reflecting the non-spherical radiation field and nonuniform dust-free gas. Moreover, we found that the sublimation radius of θ20\theta \sim 20-6060 deg varies on a timescale of several years. The ``inflow-induced outflow" contributes the obscuration of the nucleus in the sub-parsec region. The column density of the dust-free gas is NH1022N_{\rm H} \gtrsim 10^{22} cm2^{-2} for r0.04r \lesssim 0.04 pc. Gases near the disk plane (θ30\theta \lesssim 30 degree) can be the origin of the Compton-thick component, which was suggested by the recent X-ray observations of AGNs. The dusty outflow from the sub-parsec region can be also a source of material for the radiation-driven fountain for a larger scale.Comment: 13 pages, 9 figures, accepted for publication in Ap

    Paragoniastrea variabilis Kishi, Nomura &amp;amp; Fukami, sp. nov. (Cnidaria, Anthozoa, Scleractinia), a new coral species previously considered as a variant of Paragoniastrea deformis, from Japan and northern Taiwan

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    A new zooxanthellate scleractinian coral, Paragoniastrea variabilis Kishi, Nomura &amp;amp; Fukami, sp. nov. (Scleractinia, Merulinidae), is described from non-coral reef regions of Japan and northern Taiwan. This new species was previously recognized as a morphological variant of Paragoniastrea deformis (Veron, 1990) and can be morphologically distinguished from that species by lacking groove-and-tube structures on corallite wall joints, and by having larger calices, numerous septa, and up to three corallites in one valley. The new species also formed an independent clade from its congeners, P. australensis (Milne Edwards &amp;amp; Haime, 1857), P. deformis and P. russelli (Wells, 1954), in the molecular phylogeny based on the mitochondrial intergenic region and nuclear ribosomal internal transcribed spacers

    Eruption of a venous malformation through an iliac bone harvesting site after trauma

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    Harvesting grafts from the anterior iliac bone has been associated with various complications. A 50-year-old woman presented to our department with a chief complaint of right inguinal swelling and pain. Autologous bone grafts had been harvested on two previous occasions from the right anterior iliac crest for use in the reconstruction of multiple facial fractures. Computed tomography and magnetic resonance imaging revealed a full-thickness bone defect in the right anterior iliac crest. A mass was noted in the right gluteus minimus, while a multilocular cystic mass extended from the right iliac crest defect to the right inguinal region. Both the inguinal mass and gluteal mass were removed under general anesthesia. Following histopathological analysis, the gluteal mass was diagnosed as a venous malformation(VM). Based on the patient’s clinical course, iliac bone graft harvesting and trauma to the gluteal region triggered hemorrhaging from the VM. Blood components leaked out from the fragile portion of the iliac bone defect, forming a cystic lesion that developed into the inguinal mass. In this case, a coincidental VM resulted in a rare complication of iliac bone graft harvesting. These sequelae could have been avoided by planning for more appropriate ways to collect the grafts

    Parental legacy and regulatory novelty in Brachypodium diurnal transcriptomes accompanying their polyploidy

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    Polyploidy is a widespread phenomenon in eukaryotes that can lead to phenotypic novelty and has important implications for evolution and diversification. The modification of phenotypes in polyploids relative to their diploid progenitors may be associated with altered gene expression. However, it is largely unknown how interactions between duplicated genes affect their diurnal expression in allopolyploid species. In this study, we explored parental legacy and hybrid novelty in the transcriptomes of an allopolyploid species and its diploid progenitors. We compared the diurnal transcriptomes of representative Brachypodium cytotypes, including the allotetraploid Brachypodium hybridum and its diploid progenitors Brachypodium distachyon and Brachypodium stacei. We also artificially induced an autotetraploid B. distachyon. We identified patterns of homoeolog expression bias (HEB) across Brachypodium cytotypes and time-dependent gain and loss of HEB in B. hybridum. Furthermore, we established that many genes with diurnal expression experienced HEB, while their expression patterns and peak times were correlated between homoeologs in B. hybridum relative to B. distachyon and B. stacei, suggesting diurnal synchronization of homoeolog expression in B. hybridum. Our findings provide insight into the parental legacy and hybrid novelty associated with polyploidy in Brachypodium, and highlight the evolutionary consequences of diurnal transcriptional regulation that accompanied allopolyploidy

    Improved Sendai viral system for reprogramming to naive pluripotency

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    優れた多分化能を持つヒトのナイーブ型iPS細胞を迅速に作製する方法を発明. 京都大学プレスリリース. 2022-10-18.A novel method for generating naive human iPS cells with significantly higher differentiation potency. 京都大学プレスリリース. 2022-11-15.Naive human induced pluripotent stem cells (iPSCs) can be generated by reprogramming somatic cells with Sendai virus (SeV) vectors. However, only dermal fibroblasts have been successfully reprogrammed this way, and the process requires culture on feeder cells. Moreover, SeV vectors are highly persistent and inhibit subsequent differentiation of iPSCs. Here, we report a modified SeV vector system to generate transgene-free naive human iPSCs with superior differentiation potential. The modified method can be applied not only to fibroblasts but also to other somatic cell types. SeV vectors disappear quickly at early passages, and this approach enables the generation of naive iPSCs in a feeder-free culture. The naive iPSCs generated by this method show better differentiation to trilineage and extra-embryonic trophectoderm than those derived by conventional methods. This method can expand the application of iPSCs to research on early human development and regenerative medicine

    Comprehensive evaluations of a prototype full field-of-view photon counting CT system through phantom studies

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    Photon counting CT (PCCT) has been a research focus in the last two decades. Recent studies and advancements have demonstrated that systems using semiconductor-based photon counting detectors (PCDs) have the potential to provide better contrast, noise and spatial resolution performance compared to conventional scintillator-based systems. With multi-energy threshold detection, PCD can simultaneously provide the photon energy measurement and enable material decomposition for spectral imaging. In this work, we report a performance evaluation of our first CdZnTe-based prototype full-size photon counting CT system through various phantom imaging studies. This prototype system supports a 500 mm scan field-of-view (FOV) and 10 mm cone coverage at isocenter. Phantom scans were acquired using 120 kVp from 50 to 400 mAs to assess the imaging performance on: CT number accuracy, uniformity, noise, spatial resolution, material differentiation and quantification. Both qualitative and quantitative evaluations show that PCCT has superior image quality with lower noise and improved spatial resolution compared to conventional energy integrating detector (EID)-CT. Using projection domain material decomposition approach with multiple energy bin measurements, PCCT virtual monoenergetic images (VMIs) have lower noise, and superior performance in quantifying iodine and calcium concentrations. These improvements lead to increased contrast-to-noise ratio (CNR) for both high and low contrast study objects and can significantly reduce the iodine contrast agent to achieve the same CNR as EID-CT. PCCT can also generate super-high resolution (SHR) images using much smaller detector pixel size than EID-CT and dramatically push the spatial resolution limit. These initial results demonstrate that PCCT based on CdZnTe detectors has huge potential in clinical settings
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