Evaluation of hydrogen absorption cells for observations of the planetary coronas.

Newly designed Lyman-alpha absorption cells for imaging hydrogen planetary corona were characterized using an ultra high resolution Fourier transform spectrometer installed on the DESIRS (Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron) beamline of Synchrotron SOLEIL in France. The early absorption cell installed in the Japanese Mars orbiter NOZOMI launched in 1998 had not been sufficiently optimized due to its short development time. The new absorption cells are equipped with the ability to change various parameters, such as filament shape, applied power, H2 gas pressure, and geometrical configuration. We found that the optical thickness of the new absorption cell was ∼4 times higher than the earlier one at the center wavelength of Lyman-alpha absorption, by optimizing the condition to promote thermal dissociation of H2 molecules into two H atoms on a hot tungsten filament. The Doppler temperature of planetary coronas could be determined with an accuracy better than 100 K with the performance of the newly developed absorption cell.

Evidence for global electron transportation into the jovian inner magnetosphere.

Jupiter's magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves.

High sensitivity microchannel plate detectors for space extreme ultraviolet missions.

Microchannel plate (MCP) detectors have been widely used as two-dimensional photon counting devices on numerous space EUV (extreme ultraviolet) missions. Although there are other choices for EUV photon detectors, the characteristic features of MCP detectors such as their light weight, low dark current, and high spatial resolution make them more desirable for space applications than any other detector. In addition, it is known that the photocathode can be tailored to increase the quantum detection efficiency (QDE) especially for longer UV wavelengths (100-150 nm). There are many types of photocathode materials available, typically alkali halides. In this study, we report on the EUV (50-150 nm) QDE evaluations for MCPs that were coated with Au, MgF(2), CsI, and KBr. We confirmed that CsI and KBr show 2-100 times higher QDEs than the bare photocathode MCPs, while Au and MgF(2) show reduced QDEs. In addition, the optimal geometrical parameters for the CsI deposition were also studied experimentally. The best CsI thickness was found to be 150 nm, and it should be deposited on the inner wall of the channels only where the EUV photons initially impinge. We will also discuss the techniques and procedures for reducing the degradation of the photocathode while it is being prepared on the ground before being deployed in space, as adopted by JAXA's EXCEED mission which will be launched in 2013.

Endoscopic mucosal resection for early gastric cancer: comparison of two modifications of the cap method.

BACKGROUND AND STUDY AIM: Endoscopic mucosal resection using a cap (EMR-C) is an established method for curative resection of early neoplastic lesions; prelooping of the snare may however be difficult and lead to imprecise resection. We therefore compared two modifications of the conventional technique using outer snare placement with an accessory channel in a prospective, nonrandomized study. PATIENTS AND METHODS: Between October 2004 and March 2007, 54 patients (men 37, women 17; mean age 71 years) underwent EMR. One method involved an internally retained snare (IRS) cap, with a fixed prelooped snare inside the cap; the other method used an externally guided snare (EGS) cap with the snare guided over an oblique cap. The main outcome parameters were specimen size, en bloc resection, and complications. RESULTS: There was no difference between use of the IRS and EGS cap methods in relation to specimen size (27.6 vs. 27.1 mm), or rates of en bloc resection (88.9 % vs. 83.3 %); only one perforation occurred, and this was in the EGS group. CONCLUSION: Both techniques appeared to provide similar efficacy, the inner rim of the IRS cap stabilizes aspiration of the lesion compared with the EGS cap that does not have it.

Grasping-forceps-assisted endoscopic submucosal dissection using a novel irrigation cap-knife for large superficial early gastric cancer.

The technique of endoscopic submucosal dissection (ESD) needs special skills and involves a long procedure. We therefore developed a new type of dissection knife, the irrigation cap-knife (the Kume cap-knife attachment, which uses a fixed snare), that facilitates ESD by just sliding over the muscle layer with a coagulating current. The ESD procedure using the irrigation cap-knife was performed in seven patients with intramucosal gastric cancer. The tumor was separated from the surrounding normal mucosa using the insulated-tip knife. Submucosal dissection was then performed by pushing our device along the muscle layer while applying a coagulating current, at the same time as a grasping forceps, deployed through the accessory channel, was used to push the lesion away from the muscle layer. The rate of en bloc resection was 100% (7/7). The irrigating cap-knife was extremely useful for ESD of large intramucosal cancers in the stomach.

Gamma-ray detection efficiency of the microchannel plate installed as an ion detector in the low energy particle instrument onboard the GEOTAIL satellite.

A microchannel plate (MCP) assembly has been used as an ion detector in the low energy particle (LEP) instrument onboard the magnetospheric satellite GEOTAIL. Recently the MCP assembly has detected gamma rays emitted from an astronomical object and has been shown to provide unique information of gamma rays if they are intense enough. However, the detection efficiency for gamma rays was not measured before launch, and therefore we could not analyze the LEP data quantitatively. In this article, we report the gamma-ray detection efficiency of the MCP assembly. The measured efficiencies are 1.29%+/-0.71% and 0.21%+/-0.14% for normal incidence 60 and 662 keV gamma rays, respectively. The incident angle dependence is also presented. Our calibration is crucial to study high energy astrophysical phenomena by using the LEP.

Serum pepsinogen can predict response to H2-receptor antagonist in patients with functional dyspepsia.

BACKGROUND: Therapy for the relief of symptoms of functional dyspepsia is unpredictable. AIM: To identify which patients may benefit from antisecretory therapy. METHODS: Twenty-seven patients with functional dyspepsia were selected to receive H2-receptor antagonist (H2RA) treatment for 4 weeks. Serum pepsinogen A, pepsinogen C and gastrin were measured, and Helicobacter pylori status was determined. Symptoms were assessed at baseline and after H2RA treatment. RESULTS: Fourteen patients were identified as H2RA responders and the remaining patients were non-responders. No differences were found between responders and non-responders with regard to serum pepsinogen A, pepsinogen C, gastrin and H. pylori status. However, the pepsinogen A/C ratio was significantly higher in responders than in non-responders. Ten of the 13 functional dyspepsia patients (77%) with a high value of the pepsinogen A/C ratio (> or = 4.5) achieved symptom resolution by H2RA, compared with only one of the eight patients (13%) with a low value of the pepsinogen A/C ratio (< or = 3.0). CONCLUSIONS: The serum pepsinogen A/C ratio seems to identify those functional dyspepsia patients for whom acid control provides benefit. This ratio may be a practical tool for the management of functional dyspepsia patients.