Prognostic factors and mortality among adult patients with acute leukemia and infection

During the period 1986 to 1996, a total of 258 sporadic cases of community-acquired legionellosis was reported, giving a mean annual morbidity rate of 0.9 per 100,000 population. Majority of the cases (91.5%) was serologically diagnosed by the indirect fluorescent antibody (IFA) test against Legionella pneumophila based on single sera with a titre of > or = 1:1024. The others were confirmed by a four-fold increase in IFA titre to a minimum of 1:128 (7.4%) and by culture (1.1%). Cases were reported predominantly among males, ethnic Indians, the elderly and those with concurrent medical conditions. The overall case-fatality rate was 14.7%, with the rate significantly higher among those aged > or = 45 years (21%), smokers (20.4%) and those with concurrent medical conditions (22.5%). Seroepidemiological studies among the healthy population based on an IFA titre of > or = 1:32 showed a prevalence of between 10.3% and 21.9%. Of the various occupational groups investigated, high seroprevalence rates were found in foreign construction workers (52.6%) and occupants of a building investigated for an unusual building-related illness (76.1%). Environmental surveillance of Legionella bacteria showed that 36% of cooling towers, 15% to 19% of decorative fountains and waterfalls and 2% of spa pools were positive. The majority (85%) of environmental isolates was identified as Legionella pneumophila: 54.8% of serogroup 1 and 5% of Pontiac subtype.     

The southern boundary of Larderello geothermal field

The southern area of the Larderello geothermal field presents some typical characteristics of the peripheral areas of vapor-dominated systems where the reservoir passes from confined to unconfined conditions. In the natural state, steam rising from depth in upflow zones migrates laterally towards the zones where the reservoir becomes unconfined, partly condensing and partly feeding natural manifestations. Two different zones are recognizable: (a) Monterotondo, where the vapor-dominated system and the cold external aquifers are separated by a low permeability “barrier” and the physical conditions change strongly over short distances. (b) Lagoni Rossi-Carboli, where the two systems are connected, at shallow depth, through thin, isolated, permeable channels and interfere with one another. The physical conditions there vary gradually with distance. The gas content in the fluid produced increases with the distance from the upflow zones, but at a lower rate in the vicinity of confinement boundaries than in zones in which the reservoir is confined throughout. The accumulation of gas is avoided by the venting to the atmosphere of the laterally migrating steam. Water recharge increased to a significant rate only when the reservoir pressure declined and water influx took the place of the original steam outflow through the shallow permeable formations.     

Competition between recovery and recrystallization in two tungsten supplies according to ITER specifications

In thermonuclear fusion devices, tungsten, implemented as armour material of plasma facing components, is in direct contact with the plasma. Due to high heat flux (20 MW/m\(^{2}\) ), a premature cracking can be observed in relation with the loss of tungsten mechanical properties. It is usually attributed to two competing restoration processes: recovery and recrystallization. A recent investigation on two tungsten supplies according to ITER specifications has highlighted that hardness abatement at high temperature leads to overestimate the recrystallization fraction, which may be a consequence of the significant contribution of recovery during annealing. The present article aims at investigating this phenomenon through the use of a dedicated mean field recrystallization model that, unlike JMAK models, accounts for physical parameters at the microstructure scale such as recovery parameter or grain boundary mobility. The methodology is applied on the two tungsten supplies for ITER. It allows discriminating, for the first time, the respective contributions of recovery and recrystallization to the macroscopic softening in the high temperature range (from 1450 to \(1800\,^{\circ }{\text {C}}\)) and annealing times (0–3500 s). The approach has led to the conclusions that the two supplies merely differ from their initial (delivery) state through the stored energy, the initial recrystallized fraction and the grain size but not from intrinsic physical parameters such as recovery parameter or grain boundary mobility.

     

Chemical patterns of thermal aquifers in the volcanic islands of the Aegean Arc, Greece

Thermal spring waters and associated gases discharging on several volcanic islands and on mainland Greece along the Hellenic Volcanic Arc (HVA) in the south Aegean sea have been investigated. The chemical characteristics of most of the spring waters suggest that the water in their feeding aquifers is largely derived from seawater that enters the hydrological circuits and mixes with local neutral low-salinity bicarbonate waters. There are however discrepancies between the simple theoretical mixing line between local meteoric waters and seawater, and the actual mixing line. This mixing is accompanied by partial Mg and SO₄ precipitation to secondary minerals and by the addition of K, Ca, HCO₃, B, NH₄, and SiO₂ to the solutions as a result of water-rock interaction processes.At Milos and Nisyros, where active hydrothermal systems are present at shallow depth, the silica content of the thermal springs is much higher than that of springs on the other islands and mainland Greece. This suggests higher thermal gradients at depth there, and the ascent of geothermal fluids to the surface along fractures prevalently located in the fumarolic fields within the latest eruptive centers and calderas. The fact that the springs are anomalously enriched in silica only at Milos and Nisyros suggests indirectly that, apart from Santorini island, where steam vents are present at the surface, the fluids from the active high-enthalpy geothermal systems do not rise to the surface anywhere else along the HVA. If present, they are well confined under thick and impermeable covers.     

The Tianjin geothermal field (north-eastern China): Water chemistry and possible reservoir permeability reduction phenomena

Injection of spent (cooled) thermal fluids began in the Tianjin geothermal district, north-eastern China, at the end of the 1990s. Well injectivities declined after 3–4 years because of self-sealing processes that reduced reservoir permeability. The study focuses on the factors that may have caused the observed decrease in permeability, using chemical and isotopic data on fluids (water and gas) and mineral phases collected from production and injection wells. The results of data processing and interpretation indicate that (1) it is very unlikely that calcite and silica precipitation is taking place in the reservoir; (2) the Fe- and Zn-rich mineral phases (e.g. sulfides, hydroxides and silicates) show positive saturation indexes; (3) SEM and XRD analyses of filtered material reveal that the latter mineral phases are common; (4) visual observation of casings and surface installations, and of corrosion products, suggests that a poor quality steel was used in their manufacture; (5) significant quantities of solids (e.g. quartz and feldspar crystals) are carried by the geothermal fluid; (6) seasonal changes in fluid composition lead to a reduction in casing corrosion during the summer.     

Geothermal prospecting by geochemical methods on natural gas and water discharges in the vulsini mts volcanic district (central Italy)

The Latera and Torre Alfina geothermal fields were discovered in the Vulsini Mts district (central Italy) in the 70s. The fluid produced by the two geothermal systems is a high pCO₂ (around 7 MPa) sodium chloride solution (T.D.S. is 9200 ppm at Latera and 7800 at Torre Alfina), with high SiO₂ and H₃BO₃ contents. The fluid temperature taken at well bottom is about 155°C at Torre Alfina, whereas at Latera it ranges from 200 to over 350°C. In spite of these temperatures, recorded in producing wells, previous geochemical prospectings using geothermometers in natural thermal manifestations had predicted temperatures no higher than 140°C in all the Vulsini district. This contrasting feature between real temperatures and those evaluated during prospecting is caused by the fast circulation of large amounts of meteoric waters in the aquifer located in the shallow parts of the carbonate reservoir formations, and by the short interaction between the latter and the deep geothermal fluids.In the present study a new geochemical survey on thermal and cold springs, stream samples, as well as natural gas emissions has been carried out. A critical review of the main geothermometers, some considerations about the hydraulic behavior of the reservoir formations, and the cross comparison between NH₄⁺/B ratio, pCO₂ and SiO₂ content in both cold and thermal waters, have led to the conclusion that in the Vulsini Mts there are no shallow anomalous areas apart from those already discovered at Latera and Torre Alfina.The present method could be successfully applied in other geothermal systems, where the potential reservoir is represented by carbonate formations.