Long-term outcome in 109 adult patients operated on for hydrocephalus.

To examine the long-term effects of surgery in adult hydrocephalus we conducted a cross-sectional questionnaire study assessing both the patients' sense of well-being, and changes in gait, living conditions, daily need of sleep and bladder function. One-hundred-and-nine consecutive patients operated for non-communicating hydrocephalus (N-CH) (22) and communicating normal pressure hydrocephalus (NPH), both idiopathic (38) and secondary (49) were included. For survival analyses, three reference groups were selected from the general population and from the Northern Sweden MONICA Project. At long-term follow-up, 29 (27%) patients had died. Sixty-eight patients (62%) returned the questionnaire, while 12 (11%) patients did not reply. The median follow-up time was 4.2 years (range 2.3 - 6.2 years). Fifty-four (79%) of these patients reported that they still felt improved and 60% had persisting observable improvement of gait, living conditions, bladder function and need of sleep. Intention-to-treat analyses revealed that 54 (50%) of the patients still felt better and 37% remained functionally improved. The standardized mortality ratio (observed/expected) was 3.01 (CI: 2.01 - 4.32).

Inhibition of methane oxidation by volatile sulfur compounds (CH3SH and CS2) in landfill cover soils.

Methanethiol and carbon disulphide were investigated for their ability to inhibit methane oxidation in two landfill cover soils. Methanethiol was found to be a competitive inhibitor, and at concentrations occurring in landfills, both these VSCs (volatile sulfur compounds) had inhibitory effects on the methane oxidation rates. Analysis of the phospholipid fatty acid contents in the soils indicated that type I-methanotrophs were more affected than type II. These effects of VSCs on methane oxidation are likely to have implications both for the establishment and the selectivity of a methane oxidizing microflora in landfills.

Measurements of methane emissions from landfills using a time correlation tracer method based on FTIR absorption spectroscopy.

Methane is an important climate gas contributing significantly to global warming. A large part of the anthropogenic emissions of methane comes from landfills. Due to the biogenic origin of these emissions and the inhomogeneous characteristics of landfills and their soil cover, these emissions show large spatial variation. Thus, development of reliable and cost-effective methods for measurements of these emissions is an important task and a challenge to the scientific community. Traditionally, field chamber methods have been used but also different area integrating methods based on downwind plume measurements. These measurements have been supported by meteorological data either directly from local measurements or by controlled release of tracer gas from the landfill providing the dispersion characteristics of the plume. In this paperwe describe a method,the Time Correlation Tracer method, combining controlled tracer gas release from the landfill with time-resolved concentration measurements downwind the landfill using FTIR absorption spectroscopy. The method has been tested and used on measurements at a landfill in southern Sweden over the past 1.5 years. The method has proven to be a usable method for measurements of total methane emission from landfills, and under favorable meteorological conditions we estimate an achievable accuracy of 15-30%. The real time analysis capability of the FTIR makes it possible to judge the success of the measurement already on site and to decide whether more measurements are necessary. The measurement strategy is relatively simple and straightforward, and one person can make a measurement from a medium sized landfill (1-4 ha) within a few days to a week depending on the meteorological situation.

Methane oxidation in two Swedish landfill covers measured with carbon-13 to carbon-12 isotope ratios.

The release of methane (CH4) from landfills to the atmosphere and the oxidation of CH4 in the cover soils were quantified with static chambers and a 13C-isotope technique on two landfills in Sweden. One of the landfills had been closed and covered 17 years before this investigation while the other was recently covered. On both landfills, the tops of the landfills were compared with the sloping parts in the summer and winter. Emitted CH4, captured in chambers, was significantly enriched in 13C during summer compared with winter (P < 0.0001), and was enriched relative to anaerobic-zone methane. The difference between emitted and anaerobic zone delta 13C-CH4 was used to estimate soil methane oxidation. In summer, these differences ranged from 9 to 26@1000, and CH4 oxidation was estimated to be between 41 and 50% of the produced CH4 in the new landfill, and between 60 and 94% in the old landfill. In winter, when soil temperature was below 0 degree C, no difference in delta 13C was observed between emitted and anaerobic-zone CH4, suggesting that there was no soil oxidation. The temperature effect shown in this experiment suggests that there may be both seasonal and latitudinal differences in the importance of landfill CH4 oxidation. Finally the isotopic fractionation factor (alpha) varied from 1.023 to 1.038 and was temperature dependent, increasing at colder temperatures. Methanotrophic bacteria appeared to have high growth efficiencies and the majority of the methane consumed in incubations did not result in immediate CO2 production.

Clinical evaluation of single-tooth restorations supported by osseointegrated implants: a retrospective study.

This retrospective study of Brånemark implants presents results from 93 implants for single-tooth replacements placed in 77 patients from 1987 to 1990. Only two implants were lost: one before the abutment operation and one during the first year in function. Patients' reactions to the rehabilitations were very positive regarding esthetic aspects and function. The most obvious problem was related to loose abutment screws. Forty-three percent of the abutment screws had to be retightened during the follow-up period, and for this reason, nine cemented crowns had to be remade.