Bigradient Phase Referencing

We propose bigradient phase referencing (BPR), a new radio-observation technique, and report its performance using the Japanese very-long-baseline-interferometry network (JVN). In this method, a weak source is detected by phase-referencing using a primary calibrator, in order to play a role as a secondary calibrator for phase-referencing to a weak target. We will be given the opportunity to select a calibrator from lots of milli-Jansky sources, one of which may be located at the position closer to the target. With such a smaller separation, high-quality phase-referencing can be achieved. Furthermore, a subsequent more-sophisticated calibration can relocate array's focus to a hypothetical point much closer to the target; a higher quality of phase referencing is available. Our demonstrative observations with strong radio sources have proved the capabilities of BPR in terms of image dynamic ranges and astrometric reproducibility. The image dynamic range on a target has been improved with a factor of about six compared to that of normal phase-referencing; the resultant position difference of target's emission between two epochs was only 62+-50 micro-arcsecond, even with less than 2300-km baselines at 8.4 GHz and fast-switching of a target-calibrator pair of a 2.1-degree separation.Comment: 10 pages, 4 figures, accepted for publication in PAS

Fermented persimmon extract (kaki-shibu) is useful as a standard for component analyses of persimmon phytobezoars

The definite diagnosis of persimmon phytobezoar (i.e., diospyrobezoar) is often accomplished by a component analysis using infrared spectroscopy. However, no studies have been conducted to investigate which substance is the best as a standard for the component analysis. Here we analyzed tannic acid, Japanese persimmon (kaki), fermented persimmon extract (kaki-shibu), conventional dried persimmon, and dried persimmon smoked in sulfur (ampo-kaki) by infrared spectroscopy to determine which would be optimal as a component analysis standard. The spectrum between 1,600 to 600cm－1 of a persimmon phytobezoar was quite similar to the spectrum of kaki-shibu rather than that of tannic acid. Consequently, we conclude that kaki-shibu should be used as a standard for infrared spectroscopy analyses of persimmon phytobezoars

Urgent open embolectomy for cardioembolic cervical internal carotid artery occlusion

Acute ischemic stroke attributable to cervical internal carotid artery (ICA) occlusion is frequently associated with severe disability or death and is usually caused by atherosclerosis. By contrast, the cardioembolic cervical ICA occlusion is rare, and feasibility of urgent recanalization remains unclear. We present the first study in the literature that focuses on urgent open embolectomy for the treatment of cardioembolic cervical ICA occlusion. A retrospective review of the charts for patients undergoing open embolectomy was performed. Between April 2006 and September 2007, 640 consecutive patients with acute ischemic stroke were treated. Of them, three patients (0.47%) with the acute complete cardioembolic cervical ICA occlusion underwent urgent open embolectomy. All patients presented with profound neurological deficits and atrial fibrillation. The urgent open embolectomy achieved complete recanalization in all patients without any complications. All emboli in three patients were very large and fibrinous in histological findings. Two of three patients showed rapid improvement in neurological functions after surgical treatments. The cardioembolic occlusion of the cervical ICA is rare, but its possibility should be considered in patients with acute ischemic stroke suffering profound neurological deficits and atrial fibrillation. Urgent open embolectomy may be a treatment option to obtain successful recanalization for cardioembolic cervical ICA occlusion and is recommended because it is technically easier and similar to carotid endarterectomy.ArticleNEUROSURGICAL REVIEW. 33(3):341-348 (2010)journal articl

Ultrastructural Analysis of an Enterolith Composed of Deoxycholic Acid

A 67-year-old Japanese man underwent enterotomy because of enterolith ileus. Component analysis by infrared spectroscopy revealed that the enterolith was composed of a high concentration of deoxycholic acid. We further analyzed and compared the ultrastructure of the enterolith and a commercially available powdered form of deoxycholic acid by means of scanning electron microscopy and energy dispersive X-ray spectroscopy. Energy dispersive X-ray spectroscopy analysis revealed that the ratios of carbon and oxygen in the enterolith were equal to those in the deoxycholic acid powder. Scanning electron microscopy analysis showed rectangular prism-shaped particles on the surface of the enterolith. This structure was similar to that of the deoxycholic acid powder. The surgically removed enterolith had a twisted and coiled appearance. Possible mechanisms underlying the formation of this unique form are discussed

Japanese VLBI Network observations of radio-loud narrow-line Seyfert 1 galaxies

We performed phase-reference very long baseline interferometry (VLBI) observations on five radio-loud narrow-line Seyfert 1 galaxies (NLS1s) at 8.4 GHz with the Japanese VLBI Network (JVN). Each of the five targets (RXS J08066+7248, RXS J16290+4007, RXS J16333+4718, RXS J16446+2619, and B3 1702+457) in milli-Jansky levels were detected and unresolved in milli-arcsecond resolutions, i.e., with brightness temperatures higher than 10^7 K. The nonthermal processes of active galactic nuclei (AGN) activity, rather than starbursts, are predominantly responsible for the radio emissions from these NLS1s. Out of the nine known radio-loud NLS1s, including the ones chosen for this study, we found that the four most radio-loud objects exclusively have inverted spectra. This suggests a possibility that these NLS1s are radio-loud due to Doppler beaming, which can apparently enhance both the radio power and the spectral frequency.Comment: 8 pages, 2 figures, accepted for publication in PAS