260 research outputs found
Experimental Verification of a One-Dimensional Diffraction-Limit Coronagraph
We performed an experimental verification of a coronagraph. As a result, we
confirmed that, at the focal region where the planetary point spread function
exists, the coronagraph system mitigates the raw contrast of a star-planet
system by at least even for the 1- star-planet
separation. In addition, the verified coronagraph keeps the shapes of the
off-axis point spread functions when the setup has the source angular
separation of 1. The low-order wavefront error and the non-zero
extinction ratio of the linear polarizer may affect the currently confirmed
contrast. The sharpness of the off-axis point spread function generated by the
sub- separated sources is promising for the fiber-based observation
of exoplanets. The coupling efficiency with a single mode fiber exceeds 50%
when the angular separation is greater than 3--4. For
sub- separated sources, the peak positions (obtained with Gaussian
fitting) of the output point spread functions are different from the angular
positions of sources; the peak position moved from about to
as the angular separation of the light source varies from
to . The off-axis throughput including the
fiber-coupling efficiency (with respect to no focal plane mask) is about 40%
for 1- separated sources and 10% for 0.5- separated ones
(excluding the factor of the ratio of pupil aperture width and Lyot stop
width), where we assumed a linear-polarized-light injection. In addition,
because this coronagraph can remove point sources on a line in the sky, it has
another promising application for high-contrast imaging of exoplanets in binary
systems.Comment: 18 pages, 10 figures, accepted for the Publications of the
Astronomical Society of the Pacifi
Suzaku observations of the Hydra A cluster out to the virial radius
We report Suzaku observations of the northern half of the Hydra A cluster out
to ~1.4 Mpc, reaching the virial radius. This is the first Suzaku observations
of a medium-size (kT ~3 keV) cluster out to the virial radius. Two observations
were conducted, north-west and north-east offsets, which continue in a filament
direction and a void direction of the large-scale structure of the Universe,
respectively. The X-ray emission and distribution of galaxies elongate in the
filament direction. The temperature profiles in the two directions are mostly
consistent with each other within the error bars and drop to 1.5 keV at 1.5
r_500. As observed by Suzaku in hot clusters, the entropy profile becomes
flatter beyond r_500, in disagreement with the r^1.1 relationship that is
expected from accretion shock heating models. When scaled with the average
intracluster medium (ICM) temperature, the entropy profiles of clusters
observed with Suzaku are universal and do not depend on system mass. The
hydrostatic mass values in the void and filament directions are in good
agreement, and the Navarro, Frenk, and White universal mass profile represents
the hydrostatic mass distribution up to ~ 2 r_500. Beyond r_500, the ratio of
gas mass to hydrostatic mass exceeds the result of the Wilkinson microwave
anisotropy probe, and at r_100, these ratios in the filament and void
directions reach 0.4 and 0.3, respectively. We discuss possible deviations from
hydrostatic equilibrium at cluster outskirts. We derived radial profiles of the
gasmass- to-light ratio and iron-mass-to-light ratio out to the virial radius.
Within r_500, the iron-mass-to-light ratio of the Hydra A cluster was compared
with those in other clusters observed with Suzaku.Comment: 16 pages, 15 figures; Accepted for publication in PAS
Expansion Velocity of Ejecta in Tycho's Supernova Remnant Measured by Doppler Broadened X-ray Line Emission
We show that the expansion of ejecta in Tycho's supernova remnant (SNR) is
consistent with a spherically symmetric shell, based on Suzaku measurements of
the Doppler broadened X-ray emission lines. All the strong K_alpha line
emission show broader widths at the center than at the rim, while the centroid
energies are constant across the remnant (except for Ca). This is the pattern
expected for Doppler broadening due to expansion of the SNR ejecta in a
spherical shell. To determine the expansion velocities of the ejecta, we
applied a model for each emission line feature having two Gaussian components
separately representing red- and blue-shifted gas, and inferred the Doppler
velocity difference between these two components directly from the fitted
centroid energy difference. Taking into account the effect of projecting a
three-dimensional shell to the plane of the detector, we derived average
spherical expansion velocities independently for the K_alpha emission of Si, S,
Ar, and Fe, and K_beta of Si. We found that the expansion velocities of Si, S,
and Ar ejecta of 4700+/-100 km/s are distinctly higher than that obtained from
Fe K_alpha emission, 4000+/-300 km/s, which is consistent with segregation of
the Fe in the inner ejecta. Combining the observed ejecta velocities with the
ejecta proper-motion measurements by Chandra, we derived a distance to the
Tycho's SNR of 4+/-1 kpc.Comment: Accepted to Apj, 25 pages, 7 figures, 5 table
Preoperative prognostic nutritional index predicts postoperative infectious complications and oncological outcomes after hepatectomy in intrahepatic cholangiocarcinoma
Background: In the surgical treatment of intrahepatic cholangiocarcinoma (ICC), postoperative complications may be predictive of long-term survival. This study aimed to identify an immune-nutritional index (INI) that can be used for preoperative prediction of complications.
Patients and methods: Multi-institutional data from 316 patients with ICC who had undergone surgical resection were retrospectively analysed, with a focus on various preoperative INIs.
Results: Severe complications (Clavien-Dindo grade III-V) were identified in 66 patients (20.8%), including Grade V complications in 7 patients (2.2%). Comparison of areas under the receiver operating characteristic curve (AUCs) among various INIs identified the prognostic nutritional index (PNI) as offering the highest predictive value for severe complications (AUC = 0.609, cut-off = 50, P = 0.008). Multivariate analysis revealed PNI = 50, n = 142) and a low-PNI group (PNI
Conclusion: Preoperative PNI appears useful as an INI correlating with postoperative severe complications and as a prognostic indicator for ICC
Statistics of 207 Lya Emitters at a Redshift Near 7: Constraints on Reionization and Galaxy Formation Models
We present Lya luminosity function (LF), clustering measurements, and Lya
line profiles based on the largest sample, to date, of 207 Lya emitters (LAEs)
at z=6.6 on the 1-deg^2 sky of Subaru/XMM-Newton Deep Survey (SXDS) field. Our
z=6.6 Lya LF including cosmic variance estimates yields the best-fit Schechter
parameters of phi*=8.5 +3.0/-2.2 x10^(-4) Mpc^(-3) and L*(Lya)=4.4 +/-0.6
x10^42 erg s^(-1) with a fixed alpha=-1.5, and indicates a decrease from z=5.7
at the >~90% confidence level. However, this decrease is not large, only =~30%
in Lya luminosity, which is too small to be identified in the previous studies.
A clustering signal of z=6.6 LAEs is detected for the first time. We obtain the
correlation length of r_0=2-5 h^(-1) Mpc and bias of b=3-6, and find no
significant boost of clustering amplitude by reionization at z=6.6. The average
hosting dark halo mass inferred from clustering is 10^10-10^11 Mo, and duty
cycle of LAE population is roughly ~1% albeit with large uncertainties. The
average of our high-quality Keck/DEIMOS spectra shows an FWHM velocity width of
251 +/-16 km s^(-1). We find no large evolution of Lya line profile from z=5.7
to 6.6, and no anti-correlation between Lya luminosity and line width at z=6.6.
The combination of various reionization models and our observational results
about the LF, clustering, and line profile indicates that there would exist a
small decrease of IGM's Lya transmission owing to reionization, but that the
hydrogen IGM is not highly neutral at z=6.6. Our neutral-hydrogen fraction
constraint implies that the major reionization process took place at z>~7.Comment: 28 pages, 23 figures. Accepted for publication in Ap
Efficacy of surgical management for recurrent intrahepatic cholangiocarcinoma: A multi-institutional study by the Okayama Study Group of HBP surgery
Background The prognosis of intrahepatic cholangiocarcinoma (ICC) has been poor, because of the high recurrence rate even after curative surgery. This study aimed to evaluate the prognostic impact of surgical resection of recurrent ICC. Patients and methods A total of 345 cases of ICC who underwent hepatectomy with curative intent in 17 institutions were retrospectively analyzed, focusing on recurrence patterns and treatment modalities for recurrent ICC. Results Median survival time and overall 5-year recurrence-free survival rate were 17.8 months and 28.5%, respectively. Recurrences (n = 223) were classified as early (recurrence at 1 year, n = 92). Median survival time was poorer for early recurrence (16.3 months) than for late recurrence (47.7 months,p<0.0001). Treatment modalities for recurrence comprised surgical resection (n = 28), non-surgical treatment (n = 134), and best supportive care (BSC) (n = 61). Median and overall 1-/5-year survival rates after recurrence were 39.5 months and 84.6%/36.3% for surgical resection, 14.3 months and 62.5%/2.9% for non-surgical treatment, and 3 months and 4.8%/0% for BSC, respectively (p<0.0001). Multivariate analysis identified early recurrence, simultaneous intra- and extrahepatic recurrence, and surgical resection of recurrence as significant prognostic factors. In subgroup analyses, surgical resection may have positive prognostic impacts on intra- and extrahepatic recurrences, and even on early recurrence. However, simultaneous intra- and extrahepatic recurrence may not see any survival benefit from surgical management. Conclusion Surgical resection of recurrent ICC could improve survival after recurrence, especially for patients with intra- or extrahepatic recurrence as resectable oligo-metastases
Editorial: Conflicts
The Editorial Board reflects on the theme of 'conflict', as observed in the work published in this issue, and in the wider world
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