Background:Developments in anaesthesia during the recent decades include new drugs with limited unwanted side effects and the need for anaesthesia in new interventions, together with new groups of patients that in the past were considered to be beyond help. Aims:Study I: To determine the bolus dose of remifentanil that depresses the ventilatory drive as deeply as 1 µg/kg of fentanyl.Study II: To t

Groundwater plays a key role in public water supplies around the world, and consideration of the social dimension is a key issue in sustainable groundwater management. In Hanoi, the capital of Vietnam, the situation of groundwater resources is disastrous because the quality has seriously degraded recently. Hence, in this study, a social sustainability assessment framework of groundwater resources

Many wells in the Sanriku region used as sources for water supply systems were heavily contaminated by the tsunami of the 2011 great Tohoku earthquake on March 11 in 2011. To better understand the nature of the groundwater contamination by the tsunami inundation and to clarify the recovery process of contaminated groundwater at the study wells, groundwater monitoring has been conducted once or twi

Groundwater contamination by nitrate is a common problem in many parts of the world. The agriculturally important Shimabara district in Nagasaki, Japan, is experiencing this problem. The general source of drinking water of the study area is groundwater and consequently the nitrate contamination is a significant problem. For this reason, a groundwater investigation was performed and water samples w

Groundwater nitrate pollution is one of the most prevalent water-related environmental problems worldwide. The objective of this study is to identify the determinants of nitrogen pollutant changes with a focus on the nitrogen generation process. The novelty of our research framework is to cost-effectively identify the factors involved in nitrogen pollutant generation using public data. This study

Landfilling municipal solid waste incineration (MSWI) residue alkalizes the waste layer, causing a subsequent decrease in microbial activity and a delay in the decomposition of organic matter. In this study, efficiencies of neutralization of the leachate and organic matter decomposition in the waste layer in a column filled with MSWI residue using aeration and compost addition were evaluated. Tota

Macroscopic dispersivity is the most important factor for analysing the convection-dispersion equation (CDE) at the field scale, and it is well known that macroscopic dispersivities vary with the scale of observation. In this study, artificial heterogeneous hydraulic conductivity fields were generated with the stochastic fractal model (fς model). Macroscopic dispersivities were evaluated for two-d

The installation of recharge wells and subsurface flow barriers are among several strategies proposed to control seawater intrusion on coastal groundwater systems. In this study, we performed laboratory-scale experiments and numerical simulations to determine the effects of the location and application of recharge wells, and of the location and penetration depth of flow barriers, on controlling se

Groundwater contamination by nitrate from agricultural fields is a problem shared by many parts of the world. Kagoshima prefecture, Japan, is an important agricultural district experiencing this problem. In this study, laboratory column experiments were performed and a numerical model was developed to improve understanding of nitrate transport process through volcanic ash soils overlying the aquif

Artificial subsurface barriers are among several countermeasures proposed to control seawater intrusion into coastal aquifers. We performed experimental and numerical studies to investigate the dynamics of residual saltwater trapped in the storage area upon installation of cutoff walls. Experimental results showed that after wall installation, the residual saltwater wedge initially flattened causi

The hydrologic assessment of a lake water budget can be helpful in achieving proper water management and sustainable water use. A model to analyze a lake water budget was developed and verified for Lake Ikeda, Japan. Lake evaporation was estimated by numerical analyses of lake water temperature and the lake energy budget. Inflow from the lake catchment area and leakage from the lake bottom were es

In the construction of subsurface dams in coastal aquifers, investigations of the movement and removal of residual saltwater in the storage area are not usually carried out because of difficulties in monitoring. Experimental and numerical studies were thus performed to understand the saltwater dynamics due to the installation of cut-off walls. Experimental results for cut-off walls with opening on

Column experiments using two Japanese volcanic ash soils (Akahoya and Kuroboku soils) were carried out to improve understanding of solute transport characteristics through volcanic ash soil. As the contaminant source, a mixed solution of KNO3 and K2SO4 was applied from the top of the column. Temporal changes of cations and anions in the effluent were measured at prescribed time intervals. Breakthr

Hydrological assessment of the effect of water utilization on a lake water budget isindispensable for proper water management. A model to estimate lake water level was developed for Lake Ikeda, Japan, and was applied to investigate the lake water budget and to examine the effect of agricultural water management on the lake water level. The calculated lake water levels agreed well with the measured

Seawater intrusion in coastal aquifers is a widespread and serious problem in many parts of the world. Groundwater degradation due to seawater intrusion is often accentuated in small island aquifers due to overpumping or limited replenishing amounts of precipitation. Seawater intrusion and groundwater dynamics in a small limestone aquifer on Yoron Island, Japan, were investigated. Observations in

Two global optimization methods based on Genetic Algorithms (GA) and Shuffled Complex Evolution (SCE-UA) method were examined to evaluate reaction terms in a reactive solute transport model involving cation exchange reactions. Although the both algorithms can minimize the objective function after succession of generations, SCE-UA method appears superior to GA in that its performance depends less o

In a costal aquifer, saltwater intrusion is frequently observed due to an excess exploitation. There are many researches focused on the saltwater intrusion. However, there are few researches, which take into consideration the mixing processes in a stratified heterogeneous aquifer. In the present study, a laboratory experiment and numerical simulation are made in order to understand the phenomena i

In general, a natural aquifer has a hydrogeologically non-uniform structure. The movement of pollutants in groundwater is affected by such structural properties during transport by local advection and microscopic dispersion. The macroscopic dispersion coefficient increases linearly with travel distance or travel time at the initial stage after the pollutant is released, and then converges asymptot