Spatial extent of molecular gas, dust, and stars in massive galaxies at z=2 determined with ALMA and JWST

We present the results of 0.6"-resolution observations of CO J=3-2 line emission in 10 massive star-forming galaxies at z=2 with the Atacama Large Millimeter/submillimeter Array (ALMA). We compare the spatial extent of molecular gas with those of dust and stars, traced by the 870 $\mu$m and 4.4 $\mu$m continuum emissions, respectively. The average effective radius of the CO emission is 1.7 kpc, which is about 50 percent larger than that of the 870 $\mu$m emission and is comparable with that of the 4.4 $\mu$m emission. Utilizing the best-fit parametric models, we derive the radial gradients of the specific star-formation rate (sSFR), gas depletion timescale, and gas-mass fraction within the observed galaxies. We find a more intense star-formation activity with a higher sSFR and a shorter depletion timescale in the inner region than in the outer region. The central starburst may be the primary process for massive galaxies to build up a core. Furthermore, the gas-mass fraction is high, independent of the galactocentric radius in the observed galaxies, suggesting that the galaxies have not begun to quench star formation. Given the shorter gas depletion timescale in the center compared to the outer region, quenching is expected to occur in the center first and then propagate outward. We may be witnessing the observed galaxies in the formation phase of a core prior to the forthcoming phase of star formation propagating outward.Comment: 8 pages, 4 figures, 1 table, submitted to ApJ

Spectroscopic evidence of photogenerated carrier separation by built-in electric field in Sb-doped n-BaSi2/B-doped p-BaSi2 homojunction diodes

The operation of a BaSi2 homojunction solar cell is first demonstrated. In n+-BaSi2 (20 nm)/p-BaSi2 (500 nm)/p+-BaSi2 (50 nm) homojunction diodes on p+-Si(111) (resistivity ρ 0.1 Ω cm) heterojunction diodes, but are high in the range between 600 and 1200 nm. The difference in spectral response demonstrates the photogenerated carrier separation by the built-in electric field in the homojunction diode

Decrease in electrical contact resistance of Sb-doped n+-BaSi2 layers and spectral response of an Sb-doped n+-BaSi2/undoped BaSi2 structure for solar cells

We investigated how the electron concentration n in a 300-nm-thick Sb-doped n+-BaSi2 layer grown by molecular beam epitaxy affected the contact resistance R C to surface electrodes (Al, indium–tin-oxide). As the n of n-BaSi2 increased, R C decreased and reached a minimum of 0.019 Ω cm2 at n = 2.4 × 1018 cm−3 for the Al electrodes. This value was more than 1 order of magnitude smaller than that obtained for Al/B-doped p-BaSi2. We believe that this significant decrease in R C came from Sb segregation. Furthermore, the internal quantum efficiency (IQE) spectrum was evaluated for an Sb-doped n+-BaSi2 (20 nm)/undoped BaSi2 (500 nm)/n+-Si(111) structure. Its IQE reached as high as ~50% over a wide wavelength range under a small bias voltage of 0.1 V applied between the top and bottom electrodes

Endoscopic Self-Expandable Metal Stent Placement for Malignant Afferent Loop Obstruction After Pancreaticoduodenectomy: A Case Series and Review

In this study, we assessed a series of our cases in which endoscopic self-expandable metal stents (SEMSs) were used to treat malignant afferent loop obstruction (ALO) that arose after pancreaticoduodenectomy (PD). We retrospectively examined the records of 7 patients who underwent endoscopic SEMS placement for malignant ALO following PD. Clinical success was achieved in all cases. The median procedure time was 30 min (range, 15–50 min). There were no cases of stent occlusion, and no procedure-related adverse events were encountered. All patients died of their primary disease, and the median overall survival period was 155 days (range, 96–374 days). A re-intervention involving endoscopic ultrasound-guided hepaticogastrostomy combined with antegrade stenting was performed for obstructive jaundice and acute cholangitis in 1 case. In conclusion, endoscopic SEMS placement may be an effective and safe treatment for malignant ALO that arises after PD

Spectral evolution of GRB 060904A observed with Swift and Suzaku -- Possibility of Inefficient Electron Acceleration

We observed an X-ray afterglow of GRB 060904A with the Swift and Suzaku satellites. We found rapid spectral softening during both the prompt tail phase and the decline phase of an X-ray flare in the BAT and XRT data. The observed spectra were fit by power-law photon indices which rapidly changed from $\Gamma = 1.51^{+0.04}_{-0.03}$ to $\Gamma = 5.30^{+0.69}_{-0.59}$ within a few hundred seconds in the prompt tail. This is one of the steepest X-ray spectra ever observed, making it quite difficult to explain by simple electron acceleration and synchrotron radiation. Then, we applied an alternative spectral fitting using a broken power-law with exponential cutoff (BPEC) model. It is valid to consider the situation that the cutoff energy is equivalent to the synchrotron frequency of the maximum energy electrons in their energy distribution. Since the spectral cutoff appears in the soft X-ray band, we conclude the electron acceleration has been inefficient in the internal shocks of GRB 060904A. These cutoff spectra suddenly disappeared at the transition time from the prompt tail phase to the shallow decay one. After that, typical afterglow spectra with the photon indices of 2.0 are continuously and preciously monitored by both XRT and Suzaku/XIS up to 1 day since the burst trigger time. We could successfully trace the temporal history of two characteristic break energies (peak energy and cutoff energy) and they show the time dependence of $\propto t^{-3} \sim t^{-4}$ while the following afterglow spectra are quite stable. This fact indicates that the emitting material of prompt tail is due to completely different dynamics from the shallow decay component. Therefore we conclude the emission sites of two distinct phenomena obviously differ from each other.Comment: 19 pages, 9 figures, accepted for publication in PASJ (Suzaku 2nd Special Issue

X-ray Radiation Damage Effects on Double-SOI Pixel Detectors for the Future Astronomical Satellite "FORCE"

We have been developing the monolithic active pixel detector "XRPIX" onboard the future X-ray astronomical satellite "FORCE". XRPIX is composed of CMOS pixel circuits, SiO2 insulator, and Si sensor by utilizing the silicon-on-insulator (SOI) technology. When the semiconductor detector is operated in orbit, it suffers from radiation damage due to X-rays emitted from the celestial objects as well as cosmic rays. From previous studies, positive charges trapped in the SiO2 insulator are known to cause the degradation of the detector performance. To improve the radiation hardness, we developed XRPIX equipped with Double-SOI (D-SOI) structure, introducing an additional silicon layer in the SiO2 insulator. This structure is aimed at compensating for the effect of the trapped positive charges. Although the radiation hardness to cosmic rays of the D-SOI detectors has been evaluated, the radiation effect due to the X-ray irradiation has not been evaluated. Then, we conduct an X-ray irradiation experiment using an X-ray generator with a total dose of 10 krad at the SiO2 insulator, equivalent to 7 years in orbit. As a result of this experiment, the energy resolution in full-width half maximum for the 5.9 keV X-ray degrades by 17.8 $\pm$ 2.8% and the dark current increases by 89 $\pm$ 13%. We also investigate the physical mechanism of the increase in the dark current due to X-ray irradiation using TCAD simulation. It is found that the increase in the dark current can be explained by the increase in the interface state density at the Si/SiO2 interface.Comment: 15 pages, 12 figures, accepted for publication in Journal of Astronomical Telescopes, Instruments, and System

Significance of Coronary Artery Calcium Score in the Target Lesion Evaluated by Multi-detector Computed Tomography for Selecting Treatment of Rotational Atherectomy in Patients with Coronary Artery Disease

We investigated whether coronary artery calcium score (CAC) in the target lesion on the multidetector computed tomography angiography (CTA) predicts the addition of the Rotational atherectomy (Rota) during percutaneous coronary intervention (PCI). Lesion CAC on CTA were evaluated with quantitative coronary analysis (QCA) on coronary angiography for predicting the Rota treatment in 114 consecutive patients (165 target lesions) with first PCI (68 ± 9 years old, females: 17.6%). Rota was added in 8 patients (11 lesions). The lesion length and diameter stenosis on QCA, and lesion length and lesion CAC on CTA were the primary factors associated with the addition of Rota. Using the cut-off value based on receiver operating characteristic analysis, the sensitivity and specificity for predicting the Rota based on QCA was 72.7% in 8 of 11 lesions (vessels) with Rota and the specificity was 74% in 114 of 154 without Rota in the lesion length of ≥ 23mm (χ2=10.9, p=0.001), and 54.5% in 6 of 11 lesions with Rota and the specificity was 79.2% in 122 of 154 without Rota in the diameter stenosis of ≥ 83% (χ2=6.6, p=0.01). Those based on CTA were 90.9% in 10 of 11 lesions with Rota and 77.3% in 119 of 154 without Rota in the lesion length of ≥ 34mm (χ2=24.1, p<0.001), and 90.9% in 10 of 11 with Rota and 88.3% in 136 of 154 without Rota in the lesions with CAC ≥453 (χ2=45.7, p<0.001). Lesion CAC on CTA is most predictive of addition of Rota during PCI