We report our identification of the optical afterglow and host galaxy of the short-duration gamma-ray burst sGRB 160821B. The spectroscopic redshift of the host is z = 0.162, making it one of the ...lowest redshift short-duration gamma-ray bursts (sGRBs) identified by Swift. Our intensive follow-up campaign using a range of ground-based facilities as well as Hubble Space Telescope, XMM-Newton, and Swift, shows evidence for a late-time excess of optical and near-infrared emission in addition to a complex afterglow. The afterglow light curve at X-ray frequencies reveals a narrow jet, deg, that is refreshed at >1 day post-burst by a slower outflow with significantly more energy than the initial outflow that produced the main GRB. Observations of the 5 GHz radio afterglow shows a reverse shock into a mildly magnetized shell. The optical and near-infrared excess is fainter than AT2017gfo associated with GW170817, and is well explained by a kilonova with dynamic ejecta mass Mdyn = (1.0 0.6) × 10−3 M and a secular (post-merger) ejecta mass with Mpm = (1.0 0.6) × 10−2 M , consistent with a binary neutron star merger resulting in a short-lived massive neutron star. This optical and near-infrared data set provides the best-sampled kilonova light curve without a gravitational wave trigger to date.
We study the kinematics of the M87 jet using the first-year data of the KVN and VERA Array (KaVA) large program, which has densely monitored the jet at 22 and 43 GHz since 2016. We find that the ...apparent jet speeds generally increase from 0.3c at 0.5 mas from the jet base to 2.7c at 20 mas, indicating that the jet is accelerated from subluminal to superluminal speeds on these scales. We perform a complementary jet kinematic analysis by using archival Very Long Baseline Array monitoring data observed in 2005-2009 at 1.7 GHz and find that the jet is moving at relativistic speeds up to 5.8c at distances of 200-410 mas. We combine the two kinematic results and find that the jet is gradually accelerated over a broad distance range that coincides with the jet collimation zone, implying that conversion of Poynting flux to kinetic energy flux takes place. If the jet emission consists of a single streamline, the observed trend of jet acceleration (Γ ∝ z0.16 0.01) is relatively slow compared to models of a highly magnetized jet. This indicates that Poynting flux conversion through the differential collimation of poloidal magnetic fields may be less efficient than expected. However, we find a nonnegligible dispersion in the observed speeds for a given jet distance, making it difficult to describe the jet velocity field with a single power-law acceleration function. We discuss the possibility that the jet emission consists of multiple streamlines following different acceleration profiles, resulting in jet velocity stratification.
The First VERA Astrometry Catalog Hirota, Tomoya; Nagayama, Takumi; Honma, Mareki ...
Publications of the Astronomical Society of Japan,
08/2020, Letnik:
72, Številka:
4
Journal Article
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Abstract
We present the first astrometry catalog from the Japanese VLBI (very long baseline interferometer) project VERA (VLBI Exploration of Radio Astrometry). We have compiled all the astrometry ...results from VERA, providing accurate trigonometric-annual-parallax and proper-motion measurements. In total, 99 maser sources are listed in the VERA catalog. Among them, 21 maser sources are newly reported, while the rest of the 78 sources are referred to in previously published results or those in preparation for forthcoming papers. The accuracy in the VERA astrometry is revisited and compared with that from the other VLBI astrometry projects such as BeSSeL (The Bar and Spiral Structure Legacy) Survey and GOBELINS (the Gould’s Belt Distances Survey) with the VLBA (Very Long Baseline Array). We have confirmed that most of the astrometry results are consistent with each other, and the largest error sources are due to source structure of the maser features and their rapid variation, along with the systematic calibration errors and different analysis methods. Combined with the BeSSeL results, we estimate the up-to-date fundamental Galactic parameters of $R_{0}=7.92\pm 0.16_{\rm {stat.}}\pm 0.3_{\rm {sys.}}\:$kpc and $\Omega _{\odot }=30.17\pm 0.27_{\rm {stat.}}\pm 0.3_{\rm {sys.}}\:$km$\:$s$^{-1}\:$kpc$^{-1}$, where $R_{0}$ and $\Omega _{\odot }$ are the distance from the Sun to the Galactic center and the Sun’s angular velocity of the Galactic circular rotation, respectively.
Unilateral hypoxia-ischemia (HI) was induced in C57/BL6 male mice on postnatal day (P) 5, 9, 21 and 60, corresponding developmentally to premature, term, juvenile and adult human brains, ...respectively. HI duration was adjusted to obtain a similar extent of brain injury at all ages. Apoptotic mechanisms (nuclear translocation of apoptosis-inducing factor, cytochrome c release and caspase-3 activation) were several-fold more pronounced in immature than in juvenile and adult brains. Necrosis-related calpain activation was similar at all ages. The CA1 subfield shifted from apoptosis-related neuronal death at P5 and P9 to necrosis-related calpain activation at P21 and P60. Oxidative stress (nitrotyrosine formation) was also similar at all ages. Autophagy, as judged by the autophagosome-related marker LC-3 II, was more pronounced in adult brains. To our knowledge, this is the first report demonstrating developmental regulation of AIF-mediated cell death as well as involvement of autophagy in a model of brain injury.
Abstract
We report the initial results of our high-cadence monitoring program on the radio jet in the active galaxy M 87, obtained by the KVN and VERA Array (KaVA) at 22 GHz. This is a pilot study ...that preceded a larger KaVA–M 87 monitoring program, which is currently ongoing. The pilot monitoring was mostly performed every two to three weeks from 2013 December to 2014 June, at a recording rate of 1 Gbps, obtaining data for a total of ten epochs. We successfully obtained a sequence of good quality radio maps that revealed the rich structure of this jet from ≲1 mas to 20 mas, corresponding to physical scales (projected) of ∼0.1–2 pc (or ∼140–2800 Schwarzschild radii). We detected superluminal motions at these scales, together with a trend of gradual acceleration. The first evidence for such fast motions and acceleration near the jet base were obtained from recent VLBA studies at 43 GHz, and the fact that very similar kinematics are seen at a different frequency and time with a different instrument suggests that these properties are fundamental characteristics of this jet. This pilot program demonstrates that KaVA is a powerful VLBI array for studying the detailed structural evolution of the M 87 jet and also other relativistic jets.
Cancer metastasis contributes significantly to cancer mortality and is facilitated by lymphangiogenesis and angiogenesis. Vascular endothelial growth factor-C (VEGF-C) and VEGF-A are involved in ...lymphangiogenesis and angiogenesis. To inhibit metastasis, combination therapy with vector-based small interfering RNA (siRNA) against VEGF-C and/or VEGF-A was conducted on murine metastatic mammary cancer. Syngeneic, inoculated, metastatic mammary cancers received direct intratumoral injection of plasmid siRNA vector targeting VEGF-C (psiRNA-VEGF-C), VEGF-A (psiRNA-VEGF-A), both VEGF-C and VEGF-A (both psiRNA-VEGF-C and psiRNA-VEGF-A vectors injected, referred to as the psiRNA-VEGF-C+A group) or a scrambled sequence (psiRNA-SCR) as control, once a week for 8 weeks. Gene electrotransfer was performed on the tumors after each injection. Tumor volume was significantly lower in the psiRNA-VEGF-A and the psiRNA-VEGF-C+A groups throughout the study. Lymph node metastasis was significantly less frequent in all therapeutic groups, whereas the multiplicity of lung metastases was significantly lower in the psiRNA-VEGF-C+A group only. All siRNA therapeutic groups showed a significant reduction in the number of dilated lymphatic vessels containing intraluminal cancer cells and microvessel density. Our data suggest that specific silencing of the VEGF-C or VEGF-A gene alone can inhibit lymph node metastasis. However, combination siRNA therapy targeting both VEGF-C and VEGF-A inhibits both lymph node and lung metastasis, rendering this combined therapy more beneficial than either alone. The observed anti-metastatic activity of siRNA-expressing vectors targeting VEGF-C or VEGF-A may be of high clinical significance in the treatment of metastatic breast cancer.
We present analyses to determine the fundamental parameters of the Galaxy based on VLBI astrometry of 52 Galactic maser sources obtained with VERA, VLBA, and EVN. We model the Galaxy's structure with ...a set of parameters, including the Galaxy center distance
$ R_0$
, the angular rotation velocity at the LSR
$ \Omega_0$
, the mean peculiar motion of the sources with respect to Galactic rotation (
$ U_{\rm src}$
,
$ V_{\rm src}$
,
$ W_{\rm src}$
), the rotation-curve shape index, and the
$ V$
component of the Solar peculiar motions,
$ V_\odot $
. Based on a Markov chain Monte-Carlo method, we find that the Galaxy center distance is constrained at a 5% level to be
$ R_0$
$ =$
8.05
$ \pm$
0.45 kpc, where the error bar includes both statistical and systematic errors. We also find that the two components of the source peculiar motion
$ U_{\rm src}$
and
$ W_{\rm src}$
are fairly small compared to the Galactic rotation velocity, being
$ U_{\rm src}$
$ =$
1.0
$ \pm$
1.5 km s
$ ^{-1}$
and
$ W_{\rm src}$
$ =$
$-$
1.4
$ \pm$
1.2 km s
$ ^{-1}$
. Also, the rotation curve shape is found to be basically flat between Galacto-centric radii of 4 and 13 kpc. On the other hand, we find a linear relation between
$ V_{\rm src}$
and
$ V_\odot $
as
$ V_{\rm src}$
$ =$
$ V_\odot $
$-$
19 (
$ \pm$
2) km s
$ ^{-1}$
, suggesting that the value of
$ V_{\rm src}$
is fully dependent on the adopted value of
$ V_\odot $
. Regarding the rotation speed in the vicinity of the Sun, we also find a strong correlation between
$ \Omega_0$
and
$ V_\odot $
. We find that the angular velocity of the Sun,
$ \Omega_{\odot}$
, which is defined as
$ \Omega_\odot$
$ \equiv$
$ \Omega_0$
$ +$
$ V_\odot/R_0$
, can be well constrained with the best estimate of
$ \Omega_\odot$
$ =$
31.09
$ \pm$
0.78 km s
$ ^{-1}$
kpc
$ ^{-1}$
. This corresponds to
$ \Theta_0$
$ =$
238
$ \pm$
14 km s
$ ^{-1}$
if one adopts the above value of
$ R_0$
and recent determination of
$ V_\odot $
$ \sim$
12 km s
$ ^{-1}$
.
A synchrotron X-ray powder diffraction pattern was measured for a lithium superionic conductor, Li7P3S11, which has a high conductivity of 3.2X10-3Scm-1 at room temperature and a low activation ...energy of 12kJmol-1 Mizuno et al., Solid State Ionics, vol. 177 (2006) 2721. The crystal structure was solved by a direct space global optimization technique and refined by the Rietveld method. The compound crystallizes in a triclinic cell, space group P-1, a=12.5009(3) A, b=6.03160(17) A, c=12.5303(3) A, alpha=102.845(3) deg , beta=113.2024(18) deg , gamma=74.467(3) deg . PS4 tetrahedra and P2S7 ditetrahedra are contained in the structure and Li ions are situated between them.
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