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In 2011, by 1.3 mm wavelength VLBI radio wave observations of the SgrA*, Fish, V. L. et al showed that the emissions tightly related to the formation of a black hole shadow have a remarkably large time-varying feature within a region of less than 50 μas. The present paper suggests that the origin of the time variation in the observed emission is due to effects of the orbital motion of the existing super-massive black hole binary orbiting at SgrA* with a period of 2150±2.5 s. This suggestion is based on observations of decameter radio wave pulses from SgrA*. We show a good correlation between the time variation in the coherent flux density of the VLBI results and the time variation model of estimated emission intensities based on the periodic motion of the super-massive black hole binary by applying parameters deduced from the decameter radio wave pulse observation model (DRWP-Model). With further confirmation by Fourier analyses of the potential periodicity of the VLBI data that show the same periods of DRWP Model, we conclude that the time variation detected by the 1.3 mm wavelength radio wave VLBI is evidence of an existing super-massive black hole at Sgr A*.

Solution processable cross-linked core-shell poly[poly(ethylene glycol)methylether methacrylate]-block-poly(2,5-dibromo-3-vinylthiophene) (poly(PEGMA)m-b-poly(DB3VT)n) nanoparticles are firstly explored as charge storage materials for transistor-type memory devices owing to their efficient and controllable ability in electric charge transfer and trapping.

Synthetic aperture radar (SAR) processing was applied to the observation data of Lunar Radar Sounder (LRS), which is an HF sounder which was installed onboard a Japanese lunar exploration orbiter, Kaguya, for the purpose of imaging lunar subsurface structure. A two-media model was introduced to the LRS SAR algorithm to define the reference function of the LRS SAR processing. The LRS SAR algorithm has two free parameters, i.e., dielectric constant of the subsurface medium and synthetic aperture. The effect of these free parameters on LRS SAR imaging was studied by simulation and was verified by actual LRS observation data. A practical guideline for LRS SAR processing was drawn. The dielectric constant of the subsurface medium may be ignored in practice so far as the synthetic aperture is smaller than 10 km. For a larger synthetic aperture case, assumption of a moderate dielectric constant (e = 6 ~ 8) of the subsurface medium is effective in realizing good focusing of deep targets. Finally, taking full advantage of ground processing, advanced processing was attempted. Off-nadir focusing SAR processing proved to be effective in imaging oblique objects whose dominant scattering angle was not the angle toward zenith. Changing the dielectric constant of the two-media model proved to be effective in focusing/defocusing small objects, thus enabling us to localize the object's position as surface or subsurface.

Magnetic compression anastomosis (MCA) provides a minimally invasive treatment creating a nonsurgical, sutureless enteric anastomosis in conjunction with an interventional radiologic technique by using 2 high-power magnets. Recently, the MCA technique has been applied to bile duct strictures after living donor liver transplantation or major hepatectomy. Herein we described use of MCA for bile duct stenosis 5 months after donor left hepatectomy in a 24-year-old man who presented with a stricture at the porta hepatis and intrahepatic bile duct dilatation. Unsuccessful transpapillary biliary drainage and balloon dilatation through a percutaneous transhepatic biliary drainage (PTBD) route led to the MCA. A 4-mm-diameter cylindrical samarium-cobalt (Sm-Co) daughter magnet with a long nylon wire was placed at the superior site of the obstruction through the PTBD route. A 5-mm-diameter Sm-Co parent magnet with an attached nylon handle was endoscopically inserted into the common bile duct and placed at the inferior site of obstruction. The 2 magnets were attracted, sandwiching the stricture and establishing a reanastomosis. In conclusion, the MCA technique was a unique procedure for choledochocholedochostomy in a patient with bile duct stenosis after donor hepatectomy.

Well-defined amphiphilic block copolymers, poly[poly(ethylene glycol) methyl ether methacrylate]-block-poly(2,5-dibromo-3-vinylthiophene) poly(PEGMA)-b-poly(DB3VT), were synthesized by reversible addition–fragmentation chain transfer polymerization. A facile bottom-up modification was developed for preparing cross-linked core–shell nanoparticles from the amphiphilic block copolymers, in which an in situ Suzuki coupling reaction was carried out between 2,5-dibromide groups in the block copolymers and various diboronic acid compounds in the presence of a palladium catalyst after micelle formation in THF/H2O solution. The stable and uniform core–shell structure was confirmed by scanning force microscopy and dynamic light scattering observations. Furthermore, the size of the cross-linked core–shell nanoparticles could be controlled by adjusting the compositions of each segment in the block copolymers and Suzuki coupling reaction conditions. The relationship between the optical properties and chemical structur...

Immunologic tolerance is the goal for all transplant surgeons. We have reported that repeated donor-specific antigen transfusion (DST) via the portal vein allowed rapid reduction of immunosuppressants with decreased acute cellular rejection episodes among living donor liver transplantations (LDLT). Moreover, we demonstrated that intraportal DST induced macrochimerism of donor type CD56+ T cells in the liver graft. We examined the impact of FoxP3+CD4+CD25+ T cells in recipients who acquired almost tolerance after LDLT with intraportal DST. We defined the amount of immunosuppressants administered less than one time per week as "almost tolerance" after LDLT, which occurred among 14% of DST patients after adult-to-adult LDLT. Two patients (4%) have gotten been we used from immunosuppressants more than 2 years after LDLT 4 years prior. We examined the impact of FoxP3+CD4+CD25+ T cells both in recipients with almost daily immunosuppressants and those who acquired almost tolerance. The proportion of FoxP3+/CD4+CD25+ T cells in the almost tolerance group was significantly higher than that in the almost daily immunosuppressant group (P

Subarachnoid haemorrhage (SAH) is known as one of the aetiologies of out-of-hospital cardiac arrest (OHCA). However, the mechanisms of circulatory collapse in these patients have remained unclear.We examined 244 consecutive OHCA patients transferred to our emergency department. Head computed tomography was performed on all patients and revealed the existence of SAH in 14 patients (5.9%, 10 females). Among these, sudden collapse was witnessed in 7 patients (50%). On their initial cardiac rhythm, all 14 patients showed asystole or pulseless electrical activity, but no ventricular fibrillation (VF). Return of spontaneous circulation (ROSC) was obtained in 10 of the 14 patients (14.9% of all ROSC patients) although all resuscitated patients died later. The ROSC rate in patients with SAH (71%) was significantly higher than that of patients with either other types of intracranial haemorrhage (25%, n=2/8) or presumed cardiovascular aetiologies (22%, n=23/101) (p0.01). On electrocardiograms, ST-T abnormalities and/or QT prolongation were found in all 10 resuscitated patients. Despite their electrocardiographic abnormalities, only 3 patients showed echocardiographic abnormalities.The frequency of SAH in patients with all causes of OHCA was about 6%, and in resuscitated patients was about 15%. The initial cardiac rhythm revealed no VF even though half had a witnessed arrest. A high ROSC rate was observed in patients with SAH, although none survived to hospital discharge.

Background We have developed a new portocaval (PC) shunt creation technique for use in small-for-size (SFS) graft liver transplantations. PC shunts are already used to avoid SFS graft syndrome in cases of adult-to-adult living donor liver transplantation (LDLT), but the current method of creating these shunts is subject to two problems: reportal hypertension and liver dysfunction after premature ligation of the PC shunt; and graft atrophy and liver dysfunction because of the loss of portal venous flow late in the recovery period after LDLT. Methods Our new technique avoids these two problems simultaneously by using the interposed obliterated ligamentum teres hepatis (LTH) to create the PC shunt, then obstructing the PC shunt after regeneration of the liver graft. Results We have used this technique in four cases. In all cases, portal venous pressures after shunting were lower than those before shunting, and PC shunts with lower portal pressure were obstructed faster than that with higher portal pressure. Conclusion Our results suggest that the LTH can function as a shape memory graft to reduce portal venous flow after regeneration of the graft liver. Using the LTH to create a PC shunt might help to prevent both SFS graft syndrome early in the recovery period after LDLT and loss of portal venous flow late in the recovery period.

著者人数: 14名, Accepted: 2010-06-29, 資料番号: SA1002887000

Observations of the subsurface geology of the Moon help advance our understanding of lunar origin and evolution. Radar sounding from the Kaguya spacecraft has revealed subsurface layers at an apparent depth of several hundred meters in nearside maria. Comparison with the surface geology in the Serenitatis basin implies that the prominent echoes are probably from buried regolith layers accumulated during the depositional hiatus of mare basalts. The stratification indicates a tectonic quiescence between 3.55 and 2.84 billion years ago; mare ridges were formed subsequently. The basalts that accumulated during this quiet period have a total thickness of only a few hundred meters. These observations suggest that mascon loading did not produce the tectonics in Serenitatis after 3.55 billion years ago. Global cooling probably dominated the tectonics after 2.84 billion years ago.

Postoperative biliary tract complications remain one of the most serious problems facing patients who undergo living-donor liver transplantation. The aim of this study was to analyze the clinical implications of three different methods of biliary reconstruction in left-lobe adult living-donor liver transplantation.We retrospectively compared three groups of patients: those who had Roux-en-Y hepaticojejunostomy (HJ; n = 11) biliary reconstruction, those who had duct-to-duct hepaticohepaticostomy (HH) with external stent (n = 11), and those who had HH with a T-tube (n = 6). Median follow-up for each group was 31, 30, and 10 months, respectively.Bile leaks were observed in 45.5% of the patients in both the HJ group and the HH with external stent group. Biliary anastomotic strictures occurred in 9% of the Roux-en-Y HJ patients and in 27.2% of those who had HH with external stent. No biliary complications were observed in the HH with a T-tube group (P = 0.049).Biliary reconstruction using HH with a T-tube may decrease the incidence of biliary complications. Despite the relatively short follow-up period, these encouraging preliminary results may warrant further studies of this biliary reconstruction technique in left-lobe adult living-donor liver transplantation.

We present a detailed description of the features of solar "micro-type III" radio bursts, which are elements of the so-called type III storms, using long-term observations made by the Geotail and Akebono satellites. Micro-type III bursts are characterized by short-lived, continuous, and weak emission. Their average power is estimated to be well below that of the largest type III bursts, by 6 orders of magnitude. When they occur, these bursts have a distribution of emitted power flux that is different from that of ordinary type III bursts, indicating that they are not just weaker versions of the ordinary bursts. Micro-type III burst activity is not accompanied by significant solar soft X-ray activity. We identify the active regions responsible for micro-type III bursts by examining the concurrence of their development and decay with the bursts. It is found that both micro and ordinary type III bursts can emanate from the same active region without interference, indicating the coexistence of independent electron acceleration processes. It is suggested that the active regions responsible for micro-type III bursts generally border on coronal holes.

Objective In this study we compared the potential roles of preoperative human-telomerase reverse transcriptase (h-TERT) mRNA versus α-fetoprotein (AFP) mRNA expression in the peripheral blood as a tool to predict prognosis and tumor recurrence after living donor liver transplantation (LDLT) in hepatocellular carcinoma (HCC) patients. Patients and Methods We examined 14 patients with unresectable HCC who underwent LDLT. Six patients displayed stage IVA HCC that deviated from the Milan criteria, while the rest of the patients fell within the limitations of the Milan criteria. We analyzed the relationship between preoperative h-TERT mRNA or AFP mRNA expression in the peripheral blood and survival without recurrence. Results There was no significant difference between the survival curves without recurrence of those patients who did versus did not meet the Milan criteria. There was also no significant difference between the survival curves without recurrence among patients with positive versus negative AFP mRNA expression. However, there was a significant difference ( P = .005) between the survival curves without recurrence of those patients with positive preoperative h-TERT mRNA expression versus those who either had an initially negative preoperative h-TERT mRNA or who converted from positive to negative after neoadjuvant immunochemotherapy. Conclusions h-TERT mRNA seemed to prove more valuable than AFP mRNA not only to assess preoperative treatment modalities and postoperative patient surveillance, but also to evaluate prospective LDLT patients with HCC. Moreover, use of h-TERT mRNA could potentially expand the indications for transplantation to patients outside the Milan criteria.

Objectives There has been remarkable progress in recent technical innovations for laparoscopic hepatectomy. However, a laparoscopic procedure rarely has been indicated for donation of the liver in living-related liver transplantation (LRLT). Here, we described the technique and the outcome of video-assisted donor hepatectomy (VADH) for adult-to-adult LRLT. Methods For 13 donors in adult-to-adult LRLT, 3 types of major hepatectomy—right hemihepatectomy (3), and left hemihepatectomy, with or without the caudate lobe (10)—were performed through video-assisted procedures; surgical manipulation via ports or via a 12-cm incision and viewing through a laparoscope or through incision were combined and used. Results VADH was completed in 13 donors, with a median operation time of 363 ± 33 minutes and a median blood loss of 302 ± 191 mL. No complications specific to video-assisted procedures, postoperative bile leak, or bleeding were observed. The restoration of the liver function was smooth, and the use of an analgesic (median: 1.2 times) was reduced, compared with the historical control (median: 3.8 times) that underwent a standard donation of the liver. Currently, all donors are healthy and have returned to their previous activities. The grafts have been functioning well, excluding 3 recipients who succumbed to serious complications unrelated to the video-assisted procedure. Conclusion We have shown a new method of VADH through a 12-cm laparotomy for adult-to-adult LRLT. This technique is as feasible as standard open donor hepatectomy, with less pain and with improved postoperative symptoms.

In order to investigate spatial and temporal variations of fast and slow Z-mode waves frequently observed in the equatorial plasmasphere, statistical studies have been performed by using plasma wave observation data obtained by the Akebono satellite within a period from 1989 to 1995. It has been clarified that fast and slow Z-mode waves are intensified within ±5° of geomagnetic latitudes in an altitude range from 6000 km to the apogee (10500 km) of the satellite without obvious local time dependence. Long-term averaged intensity of fast Z-mode waves has almost the same orders of magnitude as that of slow Z-mode waves. These results indicate that significant part of fast Z-mode waves are not produced by the linear mode conversion process from slow Z-mode waves, but excited by more direct process. Furthermore, the region of intensified fast and slow Z-mode waves has been spread in a wider geomagnetic latitude range of ±10° during geomagnetic storms. These evidences suggest that one of the possible free energy sources is ring current particles injected into the equatorial region of the plasmasphere during geomagnetic storms.

Variations of cold plasma density distribution and large-scale electric field in the inner magnetosphere and plasmasphere during a geomagnetic storm were investigated by using the observation data of the Akebono satellite which has been carried out for more than 15 yeas since March, 1989. We focus on the super geomagnetic storm on March 13–15, 1989, for which the maximum negative excursion of the Dst index was −589 nT. During the main phase of the magnetic storm, the strong convection electric field with a spatially inhomogeneous structure appears in the inner magnetosphere between L = 2.0 and 7.0. The averaged intensity of the electric field was in a range of about 2.5–9.2 mV/m. The spatial distribution in the magnetic equatorial region indicates that the magnitude within an L-value range of 2.2–7.0 is much larger than that observed at L = 7.0–10.0. Associated with the appearance of the strong convection electric field, the cold plasma density near the trough region around L = 3.0–6.0 was enhanced with one or two order magnitude, compared with that in the magnetically quiet condition. This implies that a mount of the ionospheric plasma may be supplied from the topside ionosphere into the trough and plasmasphere regions by the frictional heating due to the fast plasma convection in the ionosphere as pointed out by previous studies on the enhancements of plasma density in these regions, based on incoherent scatter radar and total electron content (TEC) observations (e.g., Yeh and Foster, 1990; Foster et al., 2004). During the recovery phase of the magnetic storm, the convection electric field observed in the inner magnetosphere and plasmasphere regions recovers within 3-4 days almost up to the level of the magnetically quiet condition.

We report a case of cervical spondylitis that developed during treatment with a series of stellate ganglion blocks. A 65‑year‑old man was scheduled for 10 sessions of stellate ganglion block for treatment of right‑sided deafness of sudden onset due to Ramsay Hunt syndrome. Administration of betamethasone was started 5 days before the first block and was continued for 6 weeks. After disinfection of the skin by povidone iodine each stellate ganglion block was performed via the paratracheal approach. The first four block sessions were uneventful. However during the fifth session the patient complained of neck pain. After 10 sessions the deafness improved and the patient was discharged from the hospital. Three weeks after discharge he was readmitted for sustained neck and bilateral shoulder pain and numbness of the right hand. Cervical roentgenography and magnetic resonance imaging revealed spondylitis of C5 and C6. Antibiotics were administered for 2 weeks. The inflammatory variables on blood examination improved but cervical roentgenography performed 8 weeks after the last block showed that the vertebral body of C6 was nearly completely destroyed. Four months after the last block the vertebral bodies of C5 and C6 had fused .T his case indicates that when stellate ganglion block is performed in patients who are taking a corticosteroid the disinfection procedure must be strictly followed and that if the patient complains of neck or shoulder pain cervical roentgenography or magnetic resonance imaging or both should be immediately performed to assess the presence of spondylitis. (J Nippon Med Sch 2005; 72: 295―299)

消化管ストーマの合併症で傍ストーマヘルニアは比較的多いが嵌頓することは稀である.今回われわれは,傍ストーマヘルニア嵌頓に陥り緊急手術を要した症例を経験したので報告する.症例は72歳,女性.平成6年直腸癌で腹会陰式直腸切断術が施行されS状結腸瘻が造設された.平成11年5月13日左側腹部痛,嘔吐を主訴に来院した.腹部CTでストーマ近傍皮下に拡張した腸管を認め,傍ストーマヘルニア嵌頓による絞扼性イレウスと診断し緊急手術施行した.術中所見で,ストーマの位置は腹直筋外縁でその頭側にヘルニア門があり嵌頓した小腸を認めたため,絞扼解除・ヘルニア修復術を施行した.本症例のヘルニア発生原因としては, 1)患者が肥満体であった, 2)ストーマ作製位置が腹直筋外縁であった,と考えられた.傍ストーマヘルニアを予防するためには,腹直筋中央を貫くストーマを確実な手技で造設することが肝要と思われた.

This 59-year-old woman underwent living donor liver transplantation using a left lobe graft as an aid for autoimmune hepatitis in 2003. Splenectomy was also performed because of blood type incompatibility. Follow-up endoscopic and computed tomography examinations showed gastroesophageal varices with extra hepatic portal vein thrombosis in 2007 that increased (esophageal varices [EV]: locus superior [Ls], moderately enlarged, beady varices [F2], Blue varices [Cb], presence of small in number and localized red color sign [RC1] and telangiectasia [TE+], gastric varices [GV]: extension from the cardiac orifice to the fornix [Lg-cf], moderately enlarged, beady varices [F2], white varices [Cw], absence of red color sign [RC-]). Portal venous flow to the gastroesophageal varices was also confirmed from a large right gastric vein. The splenic vein was thrombosed. Blood flow to the liver graft was totally supplied from the hepatic artery. The graft was functioning well. Because these gastroesophageal varices had a high risk of variceal bleeding, we decided to proceed with a portal reconstruction of a surgical portosystemic shunt in 2008. Severe adhesions were observed around the portal vein. It was impossible to perform portal reconstruction. There were relatively fewes adhesious in the left lower side of the abdominal cavity. We decided to create an inferior mesenteric vein to left gonadal vein shunt. The portal vein pressure decreased from 31.0 to 21.5 cm H2O thereafter. The postoperative course was smooth without any complication. This patient was discharged on the postoperative day 15. Follow-up endoscopic study showed the improvement in the gastroesophageal varices (EV: Ls, F2, Cb, RC(-), GV: Lg-c, F2, Cw, RC-) at 3 months after the operation. We also comfirmed the patency of the shunt by serial computed tomography examinations.

One recently apparent trend in increasing traffic accidents in Japan is the increase in nighttime accidents. To address this problem, various traffic safety measures have been introduced aiming at safer road traffic environments. Among these measures, road lighting, in particular ‘local lighting’ has been introduced in an increasing number as a countermeasure against nighttime accidents. However, in terms of number of fatal accidents by road profile, the ‘at intersection’ accounts for the largest portion of the fatalities. Therefore, a more effective intersection lighting measure must be studied. This paper discusses the illuminance levels expected for intersection lighting from the viewpoint of traffic accident reduction effect and reports the review result. The means used in reviewing were accident data before and after introduction of accident countermeasure and statistical analysis. It was learned from the result of these review works that an average road surface illuminance at intersections maintained at 20 lx or higher, as a level expected for intersection lighting, can provide the effect of accident countermeasure, and that an average road surface illuminance of 30 lx can further positively develop a statistically significant result as to reduction in traffic accidents.

By the plasma wave sounder on board the Akebono satellite, the radio wave echoes, and plasma wave resonances have been observed through out the topside ionosphere and plasmasphere. The radio wave echoes had been observed even at altitude of 6,000 km showing feature of duct propagation. The plasma bulge structure were also confirmed in the high latitude topside ionosphere. The results of the sounder experiments show the principal resonances such as plasma resonances at f p , upper hybrid resonances at f UHR and harmonics of the electron cyclotron frequency at nfc; harmonic number n in the plasmasphere becomes higher than 10, sometimes. The sequence of the diffuse plasma resonance f Dn changes the occurrence mechanism between the topside ionosphere and the plasmasphere with boundary regions around the altitude of 3,000 km. As a remarkable new finding, f D0 (n=0 case of the sequence of the diffuse plasma resonance) have been found. The occurrence of f D0 resonance gives confirmation to the mechanism of f Dn generation as the instability of electrostatic electron cyclotron harmonic waves being associated with non linear wave particle interaction.

Seasonal variations in the vertical distributions of occurrence probabilities of auroral kilometnc radiation (AKR) sources and auroral acceleration regions indicated by upward-flowing ion (UFI) events were compared based on statistical analyses of plasma waves and energetic particles data observed by the Akebono satellite. The peak altitude in the vertical distribution of occurrence probability of AKR sources whose emission intensities were larger than -150dBW/m^2-Hz occurred at 5000-6000 km in the summer polar region and at 3000-4000 km in the winter polar region. The analyses have also clarified that the vertical distributions of occurrence probabilities of auroral acceleration regions also show seasonal variations that are quite similar to those of the AKR sources. Based on the observation that intense AKR emissions can be generated even in high-density plasma, we suggest that processes other than cyclotron maser instability (CMI), such as mode conversions, may be dominant under conditions of dense ambient plasma in the summer polar regions. The contri-bution of the emissions generated by these mechanisms to the seasonal variations in the vertical distributions of AKR sources is thought to be significant.

It has been necessary requirements to determine the global electron density distribution in the plasmasphere with time resolutions, of less than a day. We have provided solutions to this requirement using the wave normal directions, delay time of Omega signals and the in situ electron density observed on-board the Japanese satellite Akebono (Sawada et al., Journal of Geophysical Research 98(11) (1993) 267, Kimura et al., Advance Space Research 15(2) (1995) 103, Advance Space Research 18(6) (1996) 279, Journal of Atmospheric and Solar-Terrestrial Physics 59 (1997) 1569). The present paper is intended to review our earlier studies.

The pitch angle distribution of relativistic electrons in the inner radiation belt and its relation to local plasma waves were investigated using the data from the Akebono satellite. It was found that energetic electrons (>1 MeV) in the inner radiation belt showed an unexpected dumbbell distribution near the magnetic equator. This feature was commonly observed both in magnetically disturbed and undisturbed conditions. It was also found that this anomalous pitch angle distribution of energetic electrons was always accompanied with the enhancement of local UHR waves around the magnetic equator. These newly found features indicate the existence of an unknown wave-particle interaction process between the relativistic electrons and quasi-electrostatic plasma waves in the equatorial region of the plasmasphere.

The Lunar Radar Sounder (LRS) experiment on-board the SELENE (SELenological and ENngineering Explorer) spacecraft has been planned for observation of the subsurface structure of the Moon, using HF radar operating in the frequency range around 5 MHz. The fundamental technique of the instrumentation of LRS is based on the plasma waves and sounder experiments which have been established through the observations of the earth’s magnetosphere, plasmasphere and ionosphere by using EXOS-B (Jikiken), EXOS-C (Ohzora) and EXOS-D (Akebono) satellites; and the plasma sounder for observations of the Martian ionosphere as well as surface land shape are installed on the Planet-B (Nozomi) spacecraft which will arrive at Mars in 2003. For the exploration of lunar subsurface structures applying the developed sounder technique, discrimination of weak subsurface echo signals from intense surface echoes is important; to solve this problem, a frequency modulation technique applied to the sounder RF pulse has been introduced to improve the resolution of range measurements. By using digital signal processing techniques for the generation of the sounder RF waveform and on-board data analyses, it becomes possible to improve the S/N ratio and resolution for the subsurface sounding of the Moon. The instrumental and theoretical studies for developing the LRS system for subsurface sounding of the Moon have shown that the LRS observations on-board the SELENE spacecraft will give detailed information about the subsurface structures within a depth of 5 km from the lunar surface, with a range resolution of less than 75 m for a region with a horizontal scale of several tens of km. This capability is evaluated to be sufficient for study of the thermal history of the lunar surface region relating to a time scale of several tens of millions of years.

Beige mice lack natural killer (NK) cytotoxicity, although NK cells are normally present. In recent studies, NK T cells have been newly identified. We therefore examined the number and function of NK T cells in beige mice. The number of NK T cells was at a normal level in the liver of beige mice. NK cytotoxicity was decreased in the liver of these mice, whereas NK T cytotoxicity was intact. When immunochemical staining for perforin was conducted, the majority of NK cells and the minority of NK T cells in beige mice carried a giant granule, containing perforin, in the cytoplasm. In the case of control B6 mice, the majority of NK cells and the minority of NK T cells had multiple, dispersed granules containing perforin. These results suggest that NK T cytotoxicity is unaffected by the beige mutation, owing to their cytotoxicity being mediated without the secretion system of perforin.

c-kit + Lin - cells are present in various immune organs, including the liver, thymus, and bone marrow, where lymphoid, myeloid, or erythroid cells are generated. To compare their properties as lymphoid precursors, c-kit + Lin - cells purified from various organs of B6.Ly5.1 mice were injected into 6.5 Gy-irradiated B6.Ly5.2 mice. Depending on the source of the c-kit + cells, the degree of entrance and expansion of lymphoid cells differed in the liver and thymus of recipient mice, c-kit + cells isolated from the bone marrow entered and expanded prominently in both the liver and thymus, whereas c-kit + cells from the thymus did not do so at all. On the other hand, c-kit + cells isolated from the liver and spleen showed an intermediate pattern, namely, they took a long time to enter and expand in the liver and thymus of recipient mice. All of these c-kit + cells had the potential to give rise to lymphoid cells, which were specific to the liver and thymus, respectively. We previously showed that progenitor cells for extrathymic T cells in the liver and those for conventional T cells in the thymus are not always supplied by the bone marrow, as shown by experiments using parabiosis. Taken together with those previous data, the present results suggest that c-kit + Lin cells isolated from various immune organs have organ specific properties.

Dynamic spectra of S-bursts of Jovian decametric radiations are obtained by using a high time resolution radio spectrograph which has a time resolutionof 2 msec and the bandwidth of 2 MHz.Within occurrence of 65 S-burst events observed in the period from 1983 to 1999, 26 events have been identified as the S-N burst events, which are characterized by the interaction between the S-burst emissions and the Narrow band emissions. In the dynamic spectra of the S-N burst, the trend of emissions with negative and slower frequency drift named as “Trailing Edge Emission” are often observed shortly after the appearance of the S-burst.Detailed analyses of these phenomena revealed that the Trailing Edge Emission is not a manifestation of S-burst with slower drift rate but a variation ofN-burst. The results suggested that S-burst and the associated Trailing Edge Emission are formed simultaneously started from a common region with different drift rates. It has been further suggested that the appearance of the S-burstsis not controlled by the geometrical effect between the source region and theobserver, but directly reflects the generation of the source region widelydistributed in an altitude range from a few thousands km to 30,000 km, alongthe Io flux tube.

The statistical analyses of intensity and occurrence-frequency of auroral kilometric radiation (AKR) observed by the plasma wave and sounder experiment (PWS) onboard the Akebono (EXOS-D) satellite have been carried out for the seven-year period from March 1989 to February 1996. The results show clear seasonal variations of AKR intensity and occurrence-frequency both in the northern and southern polar regions. AKR exhibits an increase in the intensity and occurrence-frequency of intense emissions in the winter polar regions; thus there is a distinct north-south asymmetry of AKR. This tendency of asymmetry feature of AKR emission sources becomes more prominent in the high frequency range. These results have given strong confirmation to the GEOTAIL observation reported by Kasaba et al. [1997]. The origin of this asymmetry of AKR emissions are plausibly related with the seasonal dependence of the acceleration processes of the auroral electrons as has been suggested by Newell et al. [1996].

In order to clarify the origin of the so-called quasi periodic echoes (QPE) that have been often detected by radar observations in the presence of sporadic-E (Es) layers in the nighttime midlatitude ionosphere, two sounding rockets were launched during the SEEK (Sporadic-E Experiment over Kyushu) campaign. Each rocket carried a swept-frequency impedance probe to measure the E-region electron-density (Ne) profile. Using the four Ne profiles obtained during the two rocket flights together with a neutral-wind profile obtained from a trimethyl aluminum (TMA) chemical release experiment on one of the rockets and QPE obtained with a ground-based radar, we consider the role of wind shear in the formation of the observed Es layers, and the question of whether QPE are associated with Es layers that are modulated in altitude. The Ne profiles of Es structures that were obtained in the presence of QPE were characterized by the highly concentrated thin layers. The formation of such a thin layer by a neutral-wind shear process was confirmed in comparison with the TMA measurements. The peak Ne values of the Es layers ranged from 2.2 to 9.3 × 104 el/cm³ near 100-km altitude. These primary Es layers were accompanied by significant secondary structures that were located about 12 to 20 km above the main Es layers and had peak Ne that ranged from 5.2 × 10³ to 1.3×104 el/cm³. The average altitude profiles of QPE approximately covered the range where the Es-layer peaks appeared. Our principal finding is that the observed Es structures tended to resemble horizontally stratified layers rather than structures with deep altitude modulation like previous QPE model, although the rocket measurements were separated from those by radar by 90 to 145 km.

Determination of global electron density distribution in the plasmasphere has been attempted using the wave normal directions and delay time of Omega signals, and in-situ electron density observed on the Akebono satellite. The present study is based on the assumption that the plasma model is represented by a diffusive equilibrium (DE) model with temperature gradient along a magnetic field line, and that the electron density at a reference altitude (1000km) is dependent on L-value. Relative concentrations of ion constituents H+, He+, and O+ at the reference altitude are determined by fitting as either L-independent or L-dependent. For the altitude range below the reference altitude, we have adopted a distribution which has one maximum density at the F2 peak and one minimum density at the E valley, both being referred to the IRI model. The parameters related to these models are determined by the non-linear least squares fitting method for the in-situ electron density, the wave normal direction and the delay time of Omega signals observed by Akebono. Wave normal directions and delay time at Akebono for the model are determined by ray tracing. The validity of our plasmaspheric model based on the DE model was checked by comparing it with the SUPIM (Sheffield University Plasmaspheric and Ionospheric Model), and we can conclude that our model is flexible enough to represent the general global distributions of the electron density in the plasmasphere, although it is possible that in some cases, unrealistic distributions of the plasma temperatures should be used in the model. The reliability of our fitting algorithm was also checked by computer simulations, and we have confirmed that the global electron density distribution can be determined from the satellite wave data, without any significant error. Several plasmaspheric electron density distributions are shown as a result of applying our method to Akebono data.

Polarization measurements of Io-related Jovian decametric radiations (DAM's) were made in a frequency range from 20.5 to 25.5 MHz at the Zao observatory of Tohoku University, Japan. In the analyses of axial ratios of polarization ellipses, the following two factors were particularly investigated which were expected to deform the original axial ratios of Io-related DAM's; i.e., i) interferences caused by reflected wave components from ground, and ii) mutual cross-talks between one free-space mode wave to another free-space mode wave in anisotropic magnetized plasma along the ray paths. Totally 20 Io-related radio storms and 2 non-Io-A radio storms were selected for the analyses. Our major results are as follows: i) Most of Io-related DAM events indicate highly right-handed (RH) elliptical polarization and the mean value of the axial ratios for RH events is -0.31 ± 0.09 (standard deviation). ii) Io-A and 10-13 related DAM events indicate the significant difference in their axial ratios; i.e., -0.35 ± 0.08 and -0.26 ± 0.06 for RH Io-A and RH Io-B related DAM events, respectively. iii) Io-related DAM events indicate slightly more linear polarization than non-Io-A DAM events.

Observation results of the Jovian decameter wave emissions in the period of the passages of fragments of Shoemaker-Levy 9 comet through the Jovian magnetosphere indicated extremely large enhancements of Jovian decameter wave radiations (JDR), being caused by dust-plasma clouds moving across the Jovian magnetic fields. The total emission power of the decameter wave radiations was increased to the level of approximately 10 times larger than the regular maximum level of the emissions of the Jovian decameter radiation in a corresponding frequency range. The Jovian decameter wave radiations have continuously been emitted for six months, long after the passage of the fragments of Shoemaker-Levy 9 comet; the evidence suggests that the Jovian plasma environment has been completely changed by the remnants of dust clouds that were left behind the Shoemaker-Levy 9 comet fragments.

High electron temperature in the equatorial ionization anomaly region detected first by Kyokko satellite and later observed frequently by Hinotori satellite are found to be closely associated with the ionization crests of the anomaly. This phenomenon, called the equatorial electron temperature anomaly, is found to occur predominantly in the equinoctial months and to become enhanced with the increase in solar activity. It is mainly a nighttime phenomenon and shows maximum temperature enhancement at around 2100 LT. Using a theoretical model, a mechanism for its occurrence is presented. The mechanism is based on the plasma transport in the evening equatorial ionosphere resulting from the sunset electrodynamical processes.

From the upper hybrid frequency data observed by PWS onboard the Akebono satellite, the entire plasma density profile along the satellite paths have been obtained being based on the plasma neutrality condition. The analyses of the plasma density deduced from the upper hybrid frequency reveal the dynamical variation of the plasmaspheric plasma density profile (PPDP). The PPDP variation is especially characterized by the intimate correspondence to the time variation of Dst that indicates the time derivative-coefficient larger than 5 nT/hour. Variation phenomena of PPDP are divided into two categories depending on the phases of Dst variations; these are the phenomena which occur in the phase of the positive time derivative-coefficient (PDC) of Dst; and the phenomena which occur in the phase of the negative time derivative-coefficient (NDC) of Dst. Both in PDC, and NDC phases, the plasmapause structures show the sharpening of their cliff feature of the plasma density distribution, but a few hours later, all these traditionally convinced enhancement effects of the plasma convection in the neighboring plasma sheet regions are taken. over by the effects of plasmapause disruption without depending on the local time of the consideration. These plasmapause disruptions are caused by the exodus of the plasmaspheric plasma in the NDC phase while the hot plasma sheet plasma immigrates into the plasmasphere in the phase of PDC. Because of extreme inhomogeneity of the plasma temperature between the original plasmaspheric warm plasma and hot plasma from the plasma sheet region, there exist sharp discontinuous boundaries across the magnetic field lines in the plasmasphere. The evidence has been detected as the “donkey ears” phenomena by the observation of PWS onboard the Akebono satellite. It is disclosed that the exodus of plasma from the plasmasphere in NDC phase of Dst, and the immigration of plasma into the plasmasphere in PDC phase are caused by E × B drift due to the induction electric field that is strictly related to ∂B/∂t. The arrival of the front of the injected hot plasma delays with times ranging from 15 h to 2.5 h corresponding to the time derivative-coefficient of Dst, respectively from 5 nT/hour to 30 nT/hour. As higher the time derivative-coefficient becomes, the faster the drift velocity is increased; i.e., the delay time of arrival of the hot plasma front from the original plasmapause position to the satellite level becomes short for the fast E × B drift.