140 research outputs found
Modeling line-driven disk wind for broad absorption lines of quasars
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
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
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 and bolometric luminosity erg
s based on the two-dimensional radiation-hydrodynamic simulations. A
radiation-driven ``lotus-like'' multi-shell outflow is launched from the inner
part ( 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 () from the disk plane, reflecting the
non-spherical radiation field and nonuniform dust-free gas. Moreover, we found
that the sublimation radius of - 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 cm for pc. Gases near
the disk plane ( 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; Fukami, sp. nov. (Cnidaria, Anthozoa, Scleractinia), a new coral species previously considered as a variant of Paragoniastrea deformis, from Japan and northern Taiwan
A new zooxanthellate scleractinian coral, Paragoniastrea variabilis Kishi, Nomura &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; 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
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
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
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
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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