83 research outputs found
Effects of finite sizes of atomic nuclei on shear modulus and torsional oscillations in neutron stars
The shear modulus of neutron star matter is one of the important properties
for determining torsional oscillations in neutron stars. We take into account
the effects of finite sizes of spherical nuclei on the shear modulus and
examine the frequencies of crustal torsional oscillations. The shear modulus
decreases owing to the finite-size effect, which in turn decreases the
frequencies of torsional oscillations. In particular, the finite-size effect
becomes more crucial for oscillations with a larger azimuthal quantum number
and for neutron star models with a weaker density dependence of nuclear
symmetry energy. In practice, when one identifies the quasi-periodic
oscillations from a neutron star, where the magnetic effect is negligible, with
crustal torsional oscillations, the finite-size effect can be more significant
at frequencies higher than Hz.Comment: Accepted for publication in MNRA
Submillimeter ALMA Observations of the Dense Gas in the Low-Luminosity Type-1 Active Nucleus of NGC 1097
We present the first 100 pc scale view of the dense molecular gas in the
central ~ 1.3 kpc region of the type-1 Seyfert NGC 1097 traced by HCN (J=4-3)
and HCO+ (J=4-3) lines afforded with ALMA band 7. This galaxy shows significant
HCN enhancement with respect to HCO+ and CO in the low-J transitions, which
seems to be a common characteristic in AGN environments. Using the ALMA data,
we study the characteristics of the dense gas around this AGN and search for
the mechanism of HCN enhancement. We find a high HCN (J=4-3) to HCO+ (J=4-3)
line ratio in the nucleus. The upper limit of the brightness temperature ratio
of HCN (v2=1^{1f}, J=4-3) to HCN (J=4-3) is 0.08, which indicates that IR
pumping does not significantly affect the pure rotational population in this
nucleus. We also find a higher HCN (J=4-3) to CS (J=7-6) line ratio in NGC 1097
than in starburst galaxies, which is more than 12.7 on the brightness
temperature scale. Combined from similar observations from other galaxies, we
tentatively suggest that this ratio appears to be higher in AGN-host galaxies
than in pure starburst ones similar to the widely used HCN to HCO+ ratio. LTE
and non-LTE modeling of the observed HCN and HCO+ lines using J=4-3 and 1-0
data from ALMA, and J=3-2 data from SMA, reveals a high HCN to HCO+ abundance
ratio (5 < [HCN]/[HCO+] < 20: non-LTE analysis) in the nucleus, and that the
high-J lines (J=4-3 and 3-2) are emitted from dense (10^{4.5} < n_H2 [/cc] <
10^6), hot (70 < Tkin [K] < 550) regions. Finally we propose that the high
temperature chemistry is more plausible to explain the observed enhanced HCN
emission in NGC 1097 than the pure gas phase PDR/XDR chemistry.Comment: 28 pages, 17 figures, 10 tables. Accepted to PAS
ALMA Observations of the Submillimeter Dense Molecular Gas Tracers in the Luminous Type-1 Active Nucleus of NGC 7469
We present ALMA Cycle 1 observations of the central kpc region of the
luminous type-1 Seyfert galaxy NGC 7469 with unprecedented high resolution
(0.5 0.4 = 165 pc 132 pc) at submillimeter wavelengths.
Utilizing the wide-bandwidth of ALMA, we simultaneously obtained HCN(4-3),
HCO(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860
m continuum. The region consists of the central 1 component and
the surrounding starburst ring with a radius of 1.5-2.5. Several
structures connect these components. Except for CO(3-2), these dense gas
tracers are significantly concentrated towards the central 1,
suggesting their suitability to probe the nuclear regions of galaxies. Their
spatial distribution resembles well those of centimeter and mid-infrared
continuum emissions, but it is anti-correlated with the optical one, indicating
the existence of dust obscured star formation. The integrated intensity ratios
of HCN(4-3)/HCO(4-3) and HCN(4-3)/CS(7-6) are higher at the AGN position
than at the starburst ring, which is consistent to our previous findings
(submm-HCN enhancement). However, the HCN(4-3)/HCO(4-3) ratio at the AGN
position of NGC 7469 (1.110.06) is almost half of the corresponding value
of the low-luminosity type-1 Seyfert galaxy NGC 1097 (2.00.2), despite the
more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the
ratio is comparable to that of the close vicinity of the AGN of NGC 1068
( 1.5). Based on these results, we speculate that some other heating
mechanisms than X-ray (e.g., mechanical heating due to AGN jet) can contribute
significantly for shaping the chemical composition in NGC 1097.Comment: Fixed typos in the title. 15 pages, 8 figures, 4 tables: accepted for
publication in ApJ. Comments welcom
Effect of Zn substitution for Cu on CaNaCuOCl near the hole concentration of 1/8 per Cu
A weakening of superconductivity upon substitution of Cu by Zn (0.5~1 %) is
observed in a high-T_c cuprate, Ca_{2-x}Na_xCuO2Cl2, near the hole
concentration of 1/8 per Cu. The superconducting transition temperature and its
volume fraction, estimated by magnetic susceptibility, exhibit a sizable
anomaly for x=0.12~0.14, where the slowing down of Cu spin fluctuations below 5
K is demonstrated by muon spin relaxation experiments. These observations are
in close resemblance to other typical cuprates including YBa2Cu3O_{7-d}, and
Bi2Sr2Ca_{1-x}Y_xCu2O_{8+d}, providing further evidence that Zn-induced
"stripe" correlation is a universal feature of high-T_c cuprate superconductors
common to that of La_{2-x}A_{x}CuO4 (A=Ba, Sr).Comment: 4 pages, 3 figure
ALMA Observations of Multiple-CO and C Lines Toward the Active Galactic Nucleus of NGC 7469: X-Ray-dominated Region Caught in the Act
We used the Atacama Large Millimeter/submillimeter Array (ALMA) to map
CO( = 1-0), CO( = 2-1), CO( = 3-2), CO(
= 2-1), and [CI](-) emission lines around the type 1 active
galactic nucleus (AGN) of NGC 7469 () at pc resolutions.
The CO lines are bright both in the circumnuclear disk (central pc)
and the surrounding starburst (SB) ring ( kpc diameter), with two
bright peaks on either side of the AGN. By contrast, the [CI](-)
line is strongly peaked on the AGN. Consequently, the brightness temperature
ratio of [CI](-) to CO(2-1) is at the AGN, as
compared to in the SB ring. Our local thermodynamic equilibrium (LTE)
and non-LTE models indicate that the enhanced line ratios (or CI enhancement)
are due to an elevated C/CO abundance ratio () and temperature
( K) around the AGN as compared to the SB ring (abundance ratio
, temperature K), which accords with the picture of the
X-ray-dominated Region (XDR). Based on dynamical modelings, we also provide
CO(1-0)-to- and [CI](-)-to-molecular mass conversion factors at
the central pc of this AGN as and
(K km s pc), respectively.
Our results suggest that the CI enhancement is potentially a good marker of
AGNs that could be used in a new submillimeter diagnostic method toward dusty
environments.Comment: 25 pages, 12 figures, 8 tables. Accepted for publication in ApJ.
Minor updates in a replacemen
DOCK2 is involved in the host genetics and biology of severe COVID-19
「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target
The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force
「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection
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