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We carried out a system-level analysis of epigenetic regulators (ERs) and detailed the protein&ndash, protein interaction (PPI) network characteristics of disease-associated ERs. We found that most diseases associated with ERs can be clustered into two large groups, cancer diseases and developmental diseases. ER genes formed a highly interconnected PPI subnetwork, indicating a high tendency to interact and agglomerate with one another. We used the disease module detection (DIAMOnD) algorithm to expand the PPI subnetworks into a comprehensive cancer disease ER network (CDEN) and developmental disease ER network (DDEN). Using the transcriptome from early mouse developmental stages, we identified the gene co-expression modules significantly enriched for the CDEN and DDEN gene sets, which indicated the stage-dependent roles of ER-related disease genes during early embryonic development. The evolutionary rate and phylogenetic age distribution analysis indicated that the evolution of CDEN and DDEN genes was mostly constrained, and these genes exhibited older evolutionary age. Our analysis of human polymorphism data revealed that genes belonging to DDEN and Seed-DDEN were more likely to show signs of recent positive selection in human history. This finding suggests a potential association between positive selection of ERs and risk of developmental diseases through the mechanism of antagonistic pleiotropy.

We examined the dorsal lingual surfaces of an adult bharal (Pseudois nayaur) by scanning electron microscopy. The filiform papillae of the lingual apex and body consisted of a main papilla and smaller secondary papillae. The filiform papilla of the lingual body was big as compared to that of the lingual apex. The connective tissue cores of the filiform papillae consisted of several processes. The fungiform papilla was round in shape. The connective tissue cores of the fungiform papillae were flower-bud shaped. The lenticular papillae of large size were limited on the lingual prominence. The connective tissue cores of the lenticular papillae were hair-like in shape. The vallate papillae were located on both sides of the posterolateral aspects. The vallate papillae were flattened-oval shaped and the papillae were surrounded by an oval-shaped trench. The connective tissue cores of the vallate papillae were covered with numerous small spines The lingual surface of the bharal closely resembled that of the family Bovidae.

Ten-eleven translocation (TET) proteins, a family of Fe2+- and 2-oxoglutarate-dependent dioxygenases, are involved in DNA demethylation. Three TET paralogs have been identified (TET1, TET2, and TET3) and they show different patterns of tissue-specific expression. In our previous evolutionary studies, we found that the TET1 and TET2 genes underwent positive selection more frequently than the TET3 gene, possibly due to changes in the selective constraints during their evolutionary process. In this study, we performed a network-based analysis of the mRNA expression profiles of TET knockdown and the TET-containing co-expression modules identified in early human developmental stages. Analyses based on the PPI subnetwork demonstrated that TET DEGs PPI subnetwork genes were more evolutionarily conserved than all the human-chimpanzee orthologs during evolutionary history. GO annotation of gene co-expression modules containing a TET gene ortholog revealed particular features of the potential role of TET gene family members. Our study implicated the TET1 module in fundamental aspects of cellular physiology, such as the regulation of glucose metabolism, and the TET2 module in GPCR signal transduction. The TET3 module was related to signaling pathways involved in developmental regulation. The evolutionary rate and phylogenetic age distribution analysis of network member genes also support these network-based analyses. The present study provides an integrated view of TET gene family properties and might be informative for elucidating the molecular mechanisms of their biological functions.

Repeat hybrid micro-gravity measurements were conducted to detect the gravity change caused by hot spring water production around Beppu in eastern Kyushu, Japan. An A10 #017 absolute gravimeter (Micro-g LaCoste) and a CG-5 #549 gravimeter (Scintrex) were used for this study in intervals of three to four months at eight gravity stations. According to the results obtained with the absolute gravimetry, a gravity change of up to 33 μgal was detected at the Beppu Geothermal Research Laboratory (BGRL) reference station. The observed absolute gravity was compared with the groundwater level, and there was a good correlation between the gravity changes and the groundwater level changes. Based on the precipitation, groundwater level, and soil character, the effect of the water content changes in the unsaturated zone was estimated precisely by using a Gwater-1D. This calculation can explain that the gravity seasonal changes were caused by the groundwater level changes. After removal of noise effects (e.g., tidal movement, precipitation, and shallow groundwater level changes), the residual gravity changes, which were measured by the relative gravimeter, were subdivided into two types of responses. Gravity changes up to 90 μgal were observed from April 2014 to July 2015. After that, gravity became stable, except for small seasonal changes.

To respond to the high demand for high dynamic range imaging suitable for moving objects with few artifacts, we have developed a single-exposure dynamic range image sensor by introducing a triple-gain pixel and a low noise dual-gain readout circuit. The developed 3 μm pixel is capable of having three conversion gains. Introducing a new split-pinned photodiode structure, linear full well reaches 40 ke−. Readout noise under the highest pixel gain condition is 1 e− with a low noise readout circuit. Merging two signals, one with high pixel gain and high analog gain, and the other with low pixel gain and low analog gain, a single exposure dynamic rage (SEHDR) signal is obtained. Using this technology, a 1/2.7”, 2M-pixel CMOS image sensor has been developed and characterized. The image sensor also employs an on-chip linearization function, yielding a 16-bit linear signal at 60 fps, and an intra-scene dynamic range of higher than 90 dB was successfully demonstrated. This SEHDR approach inherently mitigates the artifacts from moving objects or time-varying light sources that can appear in the multiple exposure high dynamic range (MEHDR) approach.

Immediately after the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, the necessity of increasing the power supply using renewable energy was widely discussed in Japan. Small-scale geothermal power generating facilities with ≦2000 kW capacity were assessed as a renewable energy resource. In Beppu-Onsen hot spring, where high temperature hot springs discharge through a wide area, small-scale geothermal power generation started as early as 2013. This report describes difficulties faced by power generating facility operators as well as countermeasures taken by the local governments of Oita Prefecture and Beppu CitTy, and by scientists. The author’s ideas related to future conservation of geothermal and hot spring resources in Beppu are also presented.

In Hirata River at Beppu, Oita prefecture, the inflow of hot spring drainage into the rivers increases the Nile tilapia, an alien species. It is a tradeoff between the hot spring use and river ecosystem. In order to understand details of the mechanisms connecting hot spring use and ecosystem, we investigated the river water quality and the water temperature from the upper reaches to the river mouth in the Hirata River. The results show that the hot spring drainage flowing in a specific section affects the estuary area. Additionally, it is revealed that the current average water temperature of hot spring drainage is very good condition for Nile tilapia in the estuary area. It is suggested that the tradeoffs between the hot spring use and the ecosystems can be resolved by suppressing high-temperature unused hot spring drainage, and/or by collecting hot spring drainage and reduce its average temperature further by using its thermal energy more extensively.

In volcanic areas, hydrothermal systems are characterized by high bulk electrical conductivity, which is a combination of high-salinity/temperature pore water and hydrothermally-altered rock matrix. The present study focuses on better understanding the influence of the hydrothermal alteration on the surface conductivity associated with generation and stability of smectite. As a case study, the GSB borehole site at Beppu geothermal area in southwest Japan was selected; at this site, hydrothermal fluids with a relatively high temperature (150 °C) flow at a shallow depth. The physical properties related to electrical conductivity (formation factor, surface conductivity, and porosity) were estimated on the basis of Revil model using conductivity measurements of the drillcores. Strong hydrothermal alteration at the site GSB was shown by high surface conductivity (10− 2–10− 1 S/m) and high cementation exponent (2.5–4.5). From the comparison between the vertical profiles of the bulk conductivity, pore water conductivity, and surface conductivity, it was shown that the rock matrix makes a non-negligible contribution to the bulk conductivity at the site. This contribution to bulk conductivity is quite different from that of low-temperature hydrothermal systems, where the contribution from the pore water dominates because there is little or no hydrothermal alteration. Furthermore, comparison between the findings of this study and low-temperature hydrothermal systems showed that the surface conductivity could simply reflect temperature to which the rock has been exposed. The surface conductivity maintains the small value at the low temperatures such as 150 °C, its value decreases relative to that at the temperatures of 100–150 °C. This relationship is consistent with the generation and stability of smectite at active hydrothermal systems, and places strong constraints on the quantitative interpretation of the electrical conductivity structure of a volcano.

A remarkably high Li/B ratio has been recognized from a crush-leached fluid extracted from a foliation-parallel quartz vein, IR27, intercalated with a pelitic schist in the northern proximal to the Western Iratsu body of the Sambagawa metamorphic belt, SW Japan. Thin section observation shows that most quartz grains in the vein are polygonal and rarely show the undulatory extinction. These facts suggest that the quartz grains in the vein could be recrystallized under relatively high-T condition with the stress free environment, and that these fluid inclusions could be trapped during the peak metamorphic stage. Most fluid inclusions in the investigated sample are composed of liquid and vapor. Raman spectroscopy revealed that the liquid phase is aqueous fluid and the vapor is mainly a mixture of CH4 and N2. Their ice melting temperatures determined by microthermometry, ranging from -3.5 to -7.1 °C, show a striking contrast against the data of the fluid inclusions in later stage veins, ranging from -0.6 to -1.7 °C. However, the homogenization temperatures of IR27 are much lower than the peak metamorphic temperature of the host pelitic schist. The partition coefficients between the host rock and released fluid (Drock/fluid) calculated from P-T pseudosection show that DBrock/fluid tends to be higher than DLirock/fluid in a pelitic system, because of generally high modes of white mica in pelitic schists. The calculation suggests that the crush-leached fluid obtained from the quartz vein intercalated with the pelitic schist has higher Li/B ratio than fluids of those intercalated with the metabasite.

To understand deep groundwater flow systems and their interaction with CO2 emanated from magma at depth in a volcanic edifice, deep groundwater samples were collected from hot spring wells in the Aso volcanic area for hydrogen, oxygen and carbon isotope analyses and measurements of the stable carbon isotope ratios and concentrations of dissolved inorganic carbon (DIC). Relations between the stable carbon isotope ratio (δ13CDIC) and DIC concentrations of the sampled waters show that magma-derived CO2 mixed into the deep groundwater. Furthermore, groundwaters of deeper areas, except samples from fumarolic areas, show higher δ13CDIC values. The waters' stable hydrogen and oxygen isotope ratios (δD and δ18O) reflect the meteoric-water origin of that region's deep groundwater. A negative correlation was found between the altitude of the well bottom and the altitude of groundwater recharge as calculated using the equation of the recharge-water line and δD value. This applies especially in the Aso-dani area, where deeper groundwater correlates with higher recharge. Groundwater recharged at high altitude has higher δ13CDIC of than groundwater recharged at low altitude, strongly suggesting that magmatic CO2 is present to a much greater degree in deeper groundwater. These results indicate that magmatic CO2 mixes into deeper groundwater flowing nearer the magma conduit or chamber.

Stable isotopic variations (i.e. δ 18 O and δ 13 C) of stalagmites have been widely recognized as a powerful tool to reconstruct the paleoclimate/environment of terrestrial areas. δ 18 O and δ 13 C values of a stalagmite calcite are known, however, to be cumulative signals of complex climatic and hydrogeological processes. In order to assess the reliability of stable isotopic ratios of stalagmites as climate proxies, we performed a systematic comparison between the temporal variation in annual precipitation amounts and temporal variation in δ 18 O and δ 13 C values of a stalagmite calcite. First, we analyzed a stalagmite collected in Ciawitali Cave, West Java, Indonesia. This finding is that the number of growth bands is coincident with uranium series disequilibrium age, within error. This is the first documentation of a stalagmite having annual bands in the Asian equatorial region. Next, we compared annual variations in δ 18 O and δ 13 C values in the growth bands with annual variations in precipitation amounts that have occurred since the 1950s at Cikidang station near the cave, showing significant negative correlations. This result suggests that δ 18 O and δ 13 C values in stalagmites calcite are effective proxies of ancient precipitation in this study area. Furthermore, based on travel time of dripwater in Ciawitali Cave (Yamada et al., 2008), this study performed the systematic comparison between temporal variation in annual precipitation amounts and those in δ 18 O and δ 13 C values of the stalagmite calcite, by taking the travel time of groundwater into account. Negative correlation disappears when the travel time is taken into consideration, suggesting that δ 18 O and δ 13 C values of the stalagmite calcite are immediately influenced by climatic conditions.

The formation of imminent hydrochemical precursors of earthquakes is investigated by the simulation for water–rock reaction in a brittle aquifer. Sixty-one soaking experiments were carried out with granodiorite and trachyandesite grains of different sizes and three chemically-distinct waters for 6 to 168 h. The experimental data demonstrate that water–rock reaction can result in both measurable increases and decreases of ion concentrations in short times and that the extents of hydrochemical variations are controlled by the grain size, dissolution and secondary mineral precipitation, as well as the chemistry of the rock and groundwater. The results indicate that water–rock reactions in brittle aquifers and aquitards may be an important genetic mechanism of hydrochemical seismic precursors when the aquifers and aquitards are fractured in response to tectonic stress.

(2010). Some blue colored lake and pond waters in Japan. SIL Proceedings, 1922-2010: Vol. 30, No. 9, pp. 1416-1420.

One feature of volcanic lakes influenced by subaqueous fumaroles existing at lake bottoms (called active crater lakes) is the remarkable color of their waters: turquoise or emerald green. The active crater lake named Yudamari at Mt. Nakadake of Aso volcano, Japan, takes on a milky pale blue-green. The particular blue component of the lake water color results from Rayleigh scattering of sunlight by very fine aqueous colloidal sulfur particles; the green component is attributable to absorption of sunlight by dissolved ferrous ions. An objective color observation conducted during 2000–2007 revealed that the lake water color changed from blue-green to solid green. The disappearance of the blue ingredient of the water color will result in diminution of aqueous colloidal sulfur from chemical analyses of lake waters sampled simultaneously. The aqueous sulfur is produced by the reaction of sulfur dioxide and hydrogen sulfide supplied from subaqueous fumaroles. However, its production efficiency decreases by domination of sulfur dioxide in the subaqueous fumarolic sulfur gas species with increasing subaqueous fumarolic temperature. The disappearance of blue ingredients from the blue-green color of the lake water may be attributed to activation of subaqueous fumarole activity.

After the phreatic eruption in 1982-83, volcanic activities at Kusatsu-Shirane volcano had been decreasing and reached a minimum in 1990, had turned to a temporal rise in activity up to 1994 and then decreased again at least up to 1997. During this low-activity period we observed a relatively short (

Microthermometry and micro-Raman spectroscopy are performed on fluid inclusions within lenticular quartz veins elongated parallel to the main foliation of a pelitic schist of the Sanbagawa metamorphic belt, Saganoseki, Kyushu, Japan. The fluid inclusions are isolated or are arranged along the planes, which are developed subparallel (∼ 20°) to the main foliation of the quartz veins. Both types of fluid inclusions show similar homogenization temperatures and compositions in the H2O-NaCl-CH4 system. The trapping P-T conditions of the isolated fluid inclusions are determined to be 3.7-6.5 kbar and 320-450 °C by combining microthermometry and the pressure dependence of CH4 Raman shift. The estimated P-T range is consistent with the peak metamorphic conditions of the host rock (6-8 kbar, 300-400 °C) or bit lower, suggesting that the fluid inclusions are primary or secondary ones trapped at a relevant depth and they are potential evidence on the fluid composition derived from metamorphic reactions at 10-20 km depths.

Fluid migration in subduction zones is one of the key phenomena to understand the global mass transfer system. While active volcanoes provide the most recognizable conduits for fluid flow in active margins, the existence of a large number of active fluid seepages demonstrates that other forms of fluid release are also important in subduction zone settings. The authors collected fluid samples from springs and wells across the forearc area in Kyushu, a southwestern island of Japan, covering hot spring activities associated with active volcanism and the Median Tectonic Line (MTL), a major fault system present in the southwestern part of Japan. In order to determine sources of these fluids, halogen concentrations as well as 129 I/I and 36 Cl/Cl ratios were measured in samples from several locations. While Cl concentrations of the forearc fluids in Kyushu range between seawater and meteoric water value, I concentrations are considerably higher than seawater value. Fluids in the Miyazaki area are much higher in I, and somewhat higher in Br, than waters in the Oita area, which is closely associated with the MTL. The differences between those two areas are also pronounced in 129 I/I ratios, which range between 800 and 900 × 10 −15 in the Oita area and between 100 and 360 × 10 −15 in the Miyazaki area. The 129 I/I ratios obtained from the Oita area are compatible with an I derivation from subducting marine sediments, similar to findings from an earlier investigation of fluids collected from Satsuma-Iwojima, an active volcano south of Kyushu Island. In the Miyazaki area, on the other hand, I ages are too old to be derived from currently subducting marine sediments and point to a derivation from old organic-rich materials in the upper plate of the forearc region. The results demonstrate the presence of very different fluid systems in the forearc area of Kyushu: old CH 4 -rich fluids dominate in the seaward side of the forearc, while fluids close to the MTL and the Quaternary Volcanic Front demonstrate derivations from subducting marine sediments. The latter fluids in the MTL area probably are transported through the fractures associated with the fault activities, suggesting that this fault system reaches the transition zone between upper and lower plates in this region.

本研究では,白濁したエメラルドグリーンを呈する日本の代表的な活動的強酸性火口湖である阿蘇山中岳の湯だまり,草津白根山の湯釜において,色彩測定,水質分析,浮遊物質(単体硫黄)の粒度分布測定を行い,それらの結果に基づいて呈色因子および呈色機構について考察した。火口湖水に浮遊する単体イオウの粒度分布は,青白色を呈する合成イオウコロイド溶液のそれと類似し,レイリー散乱(青色)とミー散乱(乳白色)に関与するイオウコロイドの存在を確認した。色彩計を用いた色の測定結果は,火口湖の呈色がイオウコロイドによる入射太陽光の散乱によるものだけではなく,溶存するFe2+の太陽光の吸収による呈色が合わさっていることを示した。

Chemical and stable carbon isotopic analyses of dissolved inorganic carbon (DIC) were carried out for groundwater samples collected from cold springs and shallow wells in the Unzen volcanic region in 1999 and 2000. All of the data sets plotted on the carbon isotope ratio (δ13C) vs 1/DIC diagram can be explained by mixing of volcanic CO2 with DIC equilibrated with soil CO2. Groundwater DIC showing a high mixing ratio of volcanic CO2 appears to have a tendency to distribute along two major faults near the activity center of the 1990–1995 eruption. This suggests that these faults are escape routes of volcanic CO2 diffused into the volcanic edifice. The total flux of the volcanic DIC discharged from the cold springs is shown to be one to two orders of magnitude lower than the roughly estimated flux of volcanic CO2 discharged from the summit during the eruptive period.

The Chinoike-Jigoku hot pool in Beppu geothermal field, Central Kyushu, Japan, displays a blood-red color due to the hematite (Fe 2 O 3 ) deposited at the bottom of the pool. The colors of the deposits collected on 1 October 1990, on 27 March 1995, and on 6 March 1996 were measured with a colorimeter. The results show that the red deposits became yellower in 1995 and 1996 than they were in 1990. X-ray diffraction (XRD) patterns and chemical compositions of the deposits indicate that the discoloration of the Chinoike-Jigoku pool water is caused by an increase in the content of jarosite [KFe 3 (SO 4 ) 2 (OH) 6 ]. The temperature of the subsurface thermal water beneath the Chinoike-Jigoku hot pool, as estimated by the anhydrite chemical geothermometer, has declined from 200 to 150 °C over the past 25 years. The Na and Cl concentrations of the hot spring water discharging from Chinoike-Jigoku have decreased, while the SO 4 concentration has increased. The temporal variations in subsurface temperature and dissolved ion concentrations suggest that the mixing ratio between the high–temperature, neutral Na–Cl type water and the relatively low-temperature, acid H–SO 4 type water that form the thermal water of Chinoike–Jigoku has changed over the last 25 years. Hydrothermal studies of jarosite stability have confirmed that the increase in jarosite content in the deposits was caused by a temperature drop of the mixed thermal water beneath Chinoike-Jigoku pool, due to an increase in the contribution of the cooler H–SO 4 water type to the thermal mixture.

Thermal waters in hydrothermal ponds, bathing pools and the brines of geothermal electric power plants commonly have a characteristic blue color. Although many researchers have assumed that the blue color is due to a colloidal suspension and/or absorption by dissolved ferrous iron or by water itself, there has been no specific effort to identify the physical nature of this phenomenon. We have tested, in synthetic and natural solutions, whether aqueous colloidal silica is responsible for the blue color. Aqueous colloidal silica is formed by silica polymerization in thermal waters of the neutral-chloride type which contain initially monomeric silica in concentrations up to three times above the solubilities of amorphous silica. The hue of the blue thermal waters in the pools tested agrees with that of a synthesized colloidal silica solution. Grain-size analyses of aqueous colloidal silica in the blue-colored thermal waters demonstrate that the color is caused by Rayleigh scattering from aqueous colloidal silica particles with diameters (0.1–0.45 μm) smaller than the wavelengths of visible radiation.

A drastic change in lake water color from blue-green to brown was observed in the summit crater lake of Mt. Shinmoe-dake, Kirishima Volcano about 8 months after its 2008 eruption. The color change lasted for about 2 months (April–June 2009). The discoloration was attributed to a brownish color suspension that had formed in the lake water. X-ray fluorescence and Fourier transform infrared analyses of a sample of the suspension identified schwertmannite (Fe8O8(OH)6(SO4)). A cultivation test of iron-oxidizing bacteria for the sampled lake water with lakebed sediment revealed that the crater lake hosts iron-oxidizing bacteria, which likely participated in schwertmannite formation. We suggest that pyrite (FeS2) provided an energy source for the iron-oxidizing bacteria since the mineral was identified in hydrothermally altered tephra ejected by the August 2008 eruption. From consideration of these and other factors, the brownish discoloration of the summit crater lake of Mt. Shinmoe-dake was inferred to have resulted from a combined volcanic–microbial process.

The stable isotope ratios of hydrogen and oxygen were measured for rainwater samples from Typhoon No. 13, which struck Japan on September 1993, and Typhoon No. 6, which passed in July 1996. Rainwater was collected every hour over 2- to 3-day periods at Beppu, Japan (33°16′N, 131°29′E), which lies on or close to the typhoon routes. The deuterium excess parameters (δD – 8 ·δ18O) of the rainwaters vary over wide ranges from 19.22 to 1.52 for Typhoon No. 13, 1993, and from 6.02 to −8.10 for Typhoon No. 6, 1996, respectively. Rainwaters with higher d-values precipitated in the forward parts of the typhoons. This is ascribed to the possibility that the water vapors supplied by the bottom air currents from the front (rear) of the typhoons may be originally formed by rapid (gentle) evaporation of seawater. Symmetrical patterns of spatial δD and δ18O distributions within the typhoon precipitations, as estimated from the variations in the isotope ratios of the typhoon rainwaters, should appear from a continuous isotopic fractionation of water vapors with the bottom air currents converging toward the typhoon center. The weighted means of δD and δ18O of the typhoon precipitations are more negative than those of ordinary rainfall, suggesting that an isotopic influence of typhoon precipitation on surface waters, e.g., river, stream, lake, and spring waters, may be important.

Exploitation of the Beppu hydrothermal system started mainly in the lowland areas as early as the 1880s, and by the 1920s the number of wells had increased to about 1000. This caused the piezometric head of the thermal groundwater to draw down, and seawater to intrude into the thermal groundwater aquifer near the coast. A second flurry of exploitation occurred during the 1960s–70s, by which time there were over 2300 wells, and the mass and heat flows had increased due mainly to the discharge of high-temperature chloride waters in the highland areas. This caused a decline in piezometric head of the deep chloride water, a decline in the subsurface flow of chloride water towards the lowlands, and intrusion of steam-heated shallow water into the chloride water layer.

We have developed an in-situ monitoring system for aqueous polythionates in the Yugama crater lake at Kusatsu-Shirane volcano. A commercially available nitrate-selective electrode has a Nernstian response to the concentration of polythionates in solution in the range of pH 2.5–11. However, many active crater lakes contain highly acidic water (pH ranges from 0.2 to 2). The monitoring system reduces the acidity of the lake water to pH 4 without changing the concentration of polythionates using a high efficiency cation-exchange membrane technique. The monitoring system was placed in a submersed station, because the Yugama surface lake water freezes in mid-winter. The system is described and preliminary data are reported.

On 11 October 1995, Kuju Volcano (Central Kyushu, Japan) erupted steam and ash from new vents opened south of the active Kuju–Iwoyama fumarole area. The He/Ar atomic ratio of fumarolic gas, which is a possible indicator of the ratio of magmatic gas to air, suddenly decreased from 0.12–0.22 to 0.04–0.06 at the beginning of the 1995 eruption. The flux of magmatic He soon after the eruption is estimated to be almost 12 times larger than that before the eruption: values before and after the eruption are 57×10 −3 and 694×10 −3 kg/day, respectively. In contrast, the flux of air-derived He increased after the eruption by nearly 40 times than before the event: values before and soon after the eruption are 0.2×10 −3 and 7.6×10 −3 kg/day, respectively. The sudden decrease in the He/Ar ratio suggests that air has been suctioned into the flow path of uprising volcanic fluid through the surrounding formation of altered rocks piled loosely. The volume of air entrained is estimated to be nearly 1×10 4 m 3 /day.

A new low fixed pattern noise (FPN) cell structure, which can be used for photoconversion layer overlaid CCD or CMOS image sensors, was proposed and analyzed with a two-dimensional (2-D) device simulator. One of the most serious problems for this type of image sensor is the mixing of signal charges of neighboring cells during signal charge readout. The magnitude of signal mixing was as much as 20% for the conventional 2/3-in 2-million pixel STACK-CCD cell structure. FPN was very visible as a result of this signal mixing. This time, a new cell structure was proposed and analyzed to reduce signal mixing and FPN. It was possible to reduce signal mixing to a low value of 0.7% of the signal level using the new cell structure.

The fixed pattern noise reduction methods, surrounding channel stop structure and the hole accumulation operation, are proposed and evaluated for the 2/3-in two-million pixel STACK-CCD HDTV imager. The surrounding channel stop structure is surrounded by the channel stop region to suppress the fluctuation of the mean dark current from Si-SiO/sub 2/ interface and the depletion layer of p-n junction. The measured fixed pattern note (FPN) and signal-to-noise (S/N) ratio are improved from 45 electrons down to 19 electrons and from 49 dB up to 54 dB under the condition of F.8 and 2000 lux at 333 K, respectively. Therefore, the 2/3-in two-million pixel HDTV handy-type color camera with high S/N ratio and low FPN can be obtained.

Thermal water at Yufuin (Kyushu Island, Japan) is tapped through about 820 shallow wells and used mainly for hot-spring bathing purposes. Chemical and isotopic data for fluids from wells and fumaroles in Yufuin and Beppu indicate that the thermal activity at Yufuin represents a dilute, westward-flowing hydrothermal outflow plume from the Beppu hydrothermal system. Two other (eastward-flowing) outflow plumes have long been recognized at Beppu, but the Yufuin outflow plume is first recognized here. The Yufuin outflow plume is apparently a mixture of two end-member fluids: (1) deep high-temperature (250–300°C) fluid from the Beppu system having high chloride concentration (1400–1600 mg/L) and a δ 18 O value near −6.0%, and (2) meteoric water having low chloride concentration (≤7 mg/L) and a δ 18 O value near −9.2%. A permeable conduit for the vertical and lateral transport of deep fluid from the Beppu system is provided by the Yufuin Fault zone, which extends westward from the southern flank of Mt. Tsurumi volcano to the town of Yufuin. Stable isotope ratios and chloride concentrations for shallow groundwaters near the eastern end of the fault, at an elevation near 700 m, are consistent with those required for the low-chloride meteoric end-member of the Yufuin thermal waters. Recharge of this meteoric water, as well as mixing with the Beppu deep fluid, may occur along the Yufuin Fault. Enthalpy-chloride relations indicate additional conductive heating of the Yufuin waters, in the amount of 350–500 kJ/kg beyond that which can be accounted for by mixing between Beppu deep fluid and meteoric water. This could be a result of conductive heating with convection to a depth of 1–2 km. Estimates of the magnitude of the heat source for the Beppu hydrothermal system should take into account the heat being discharged at Yufuin.

A random noise for a CCD imager with an incomplete transfer-type storage diode is theoretically and experimentally discussed. The theoretical result based on the Fermi-Dirac distribution function is in good agreement with the well known experimental result as a "kTC" noise, which is equal to the square root of kTC/2. It is also shown that the random noise in the storage diode is dependent on the amount of the signal charge, and can be reduced for the small signal charge. Moreover, a small signal reset operation (SSR operation) is newly proposed to suppress the capacitive-image-lag and larger random noise. The reproduced image with the high signal-to-noise (S/N) ratio is obtained for a STACK-CCD imager with the small signal reset operation.

A single-layer metal-electrode CCD image sensor was studied with the purpose of simplifying the steps in the production process with the aim of achieving low-cost sensors and supplressing smear noise. The inter-electrode gap of the single-layer electrode was decreased to 0.3 micrometer to achieve charge-transfer efficiency of unity. Boron ion-implantation which is self-aligned to the interelectrode gap was introduced to suppress degradation in charge-transfer efficiency. A reduction in the number of process steps needed to fabricate a 1/3-inch-format 360K-pixel interline transfer CCD image sensor was achieved. Vertical resolution was 350 TV lines. Low smear noise of-108dB was obtained.

Aqueous sulfur speciation of samples of crater lake water from Crater Lake collected at Mt. Ruapehu, New Zealand since 1968 has been determined using high-performance liquid chromatography. Polythionates (S x O 6 2− ) are produced in the lake through reactions between sulfur dioxide and hydrogen sulfide gases from the subaqueous fumaroles. Their concentrations vary from 0 to a few hundred mg/l, corresponding to the activity of the volcano. The concentration of the total polythionates ( Σ S x O 6 2− = S 4 O 6 2− + S 5 O 6 2− + S 6 O 6 2− ) is found to be a good indicator of changes in the subaqueous fumarolic activity at Crater Lake. The molar S x O 6 2− /Cl − ratios of the lake water can be used to divide the volcanic activity of Crater Lake into four stages: 1. Stage I: Period of weak volcanic activity with no hydrothermal explosions. This stage is characterized by low total S x O 6 2− with a distribution order of S 5 O 6 2− > S 4 O 6 2− > S 6 O 6 2− . H 2 S is predominant among dissolved gases in the lake water. 2. Stage IIa: Quiescent period with minor hydrothermal explosions. The lake water contains high ΣS x O 6 2− with a distribution order of S 5 O 6 2− > S 4 O 6 2− > S 6 O 6 2− . Dissolved H 2 S and SO 2 gases are very low. 3. Stage IIb: Increased fumarolic activity with frequent hydrothermal explosions. Low ΣS x O 6 2− with a distribution order of S 4 O 6 2− > S 5 O 6 2− > S 6 O 6 2− . Sulfur dioxide but no H 2 S is detected in the water. 4. Stage III: Period of phreatomagmatic eruptions with lahars and intensive seismic activity. No S x O 6 2− exists but dissolved SO 2 is high in the lake water. The moderate-sized explosion of December 8, 1988, which was not preceded by any changes in lake water polythionate chemistry or seismic activity, is hypothesized to be a vent-cleaning eruption caused by blockage of ascending magmatic gases that was caused by solidification of a molten sulfur pool at the bottom of Crater Lake.